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  • 1.
    Aberg, Carola Höglund
    et al.
    Umeå University, Faculty of Medicine, Odontology. Umeå University, Faculty of Medicine, Odontology, Periodontology.
    Sjödin, Bengt
    Lakio, Laura
    Pussinen, Pirkko J
    Johansson, Anders
    Umeå University, Faculty of Medicine, Odontology. Umeå University, Faculty of Medicine, Odontology, Periodontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Odontology. Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    Presence of Aggregatibacter actinomycetemcomitans in young individuals: a 16-year clinical and microbiological follow-up study.2009In: Journal of clinical periodontology, ISSN 1600-051X, Vol. 36, no 10, p. 815-22Article in journal (Refereed)
    Abstract [en]

    AIM: To look for clinical signs of periodontal disease in young adults who exhibited radiographic bone loss and detectable numbers of Aggregatibacter actinomycetemcomitans in their primary dentition. MATERIAL AND METHODS: Periodontal status and radiographic bone loss were examined in each of the subjects 16 years after the baseline observations. Techniques for anaerobic and selective culture, and checkerboard, were used to detect periodontitis-associated bacterial species. The isolated A. actinomycetemcomitans strains were characterized by polymerase chain reaction. RESULTS: Signs of localized attachment loss were found in three out of the 13 examined subjects. A. actinomycetemcomitans was recovered from six of these subjects and two of these samples were from sites with deepened probing depths and attachment loss. Among the isolated A. actinomycetemcomitans strains, serotypes a-c and e, but not d or f, were found. None of the isolated strains belonged to the highly leucotoxic JP2 clone, and one strain lacked genes for the cytolethal distending toxin. CONCLUSIONS: This study indicates that the presence of A. actinomycetemcomitans and early bone loss in the primary dentition does not necessarily predispose the individual to periodontal attachment loss in the permanent dentition.

  • 2. Al-Otaibi, M
    et al.
    Al-Harthy, M
    Gustafsson, A
    Johansson, Anders
    Umeå University, Faculty of Medicine, Odontology, Periodontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    Angmar-Månsson, B
    Subgingival plaque microbiota in Saudi Arabians after use of miswak chewing stick and toothbrush2004In: Journal of Clinical Periodontology, ISSN 0303-6979, E-ISSN 1600-051X, Vol. 31, no 12, p. 1048-53Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The chewing stick, the miswak, is used in many developing countries as the traditional means for oral hygiene. It is prepared from the roots, twigs and stem of Salvadora persica or other alternative local plants. OBJECTIVES: To compare the effects of the chewing stick miswak (from S. persica) and toothbrush on subgingival plaque microflora among Saudi Arabian individuals. Further, to investigate whether components extracted from S. persica may interfere with the subgingival plaque micro-organisms. MATERIAL AND METHODS: Fifteen healthy Saudi Arabian male volunteers aged 21-36 years were included in a single-blind, randomized cross-over study. The participants were taught how to use each device properly. Plaque sampling for DNA test was performed at the baseline, 1 week after professional tooth cleaning, and after 3 weeks of either miswak or toothbrush use. Identification and quantification of microbial species were performed by the checkerboard method, using whole genomic, digoxigenin-labelled DNA probes. Inhibition zones around miswak were examined on agar plates with Actinobacillus actinomycetemcomitans and the leukotoxicity of this bacterium was analyzed in a bioassay with macrophages+/-extracts of miswak. RESULTS: Miswak and toothbrushing had a similar influence on the levels of the subgingival microbiota. However, A. actinomycetemcomitans was significantly more reduced by miswak (p<0.05) than by toothbrushing. These results were supported by our in vitro results which, indicated that extracts from S. persica might interfere with the growth and leukotoxicity of A. actinomycetemcomitans. CONCLUSIONS: In contrast to toothbrush use, miswak use significantly reduced the amount of A. actinomycetemcomitans in the subgingival plaque.

  • 3. Carlsson, G
    et al.
    Wahlin, Ylva-Britt
    Umeå University, Faculty of Medicine, Odontology, Oral and Maxillofacial Radiology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Odontology, Periodontology.
    Olsson, A
    Eriksson, T
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Odontology.
    Hänström, Lennart
    Umeå University, Faculty of Medicine, Odontology.
    Henter, JI
    Periodontal disease in patients from the original Kostmann family with severe congenital neutropenia2006In: Journal of Periodontology, ISSN 0022-3492, E-ISSN 1943-3670, Vol. 77, no 4, p. 744-751Article in journal (Refereed)
    Abstract [en]

    Patients with Kostmann syndrome (severe congenital neutropenia [SCN]) typically normalize their absolute neutrophil count (ANC) upon granulocyte colony-stimulating factor (G-CSF) therapy. However, although they no longer experience life-threatening bacterial infections, they frequently still have recurrent gingivitis and even severe periodontitis, often starting in early childhood. METHODS: We studied the periodontal disease in the four surviving patients belonging to the family originally described by Kostmann. Their odontological records, x-rays, color photos, bacterial cultures, serum antibodies to oral bacteria, and histopathological examinations were reviewed. The data were also correlated to previous investigations on their antibacterial peptides and molecular biology. RESULTS: Three patients had periodontal disease, despite normal ANC and professional dental care, and had neutrophils deficient in antibacterial peptides. One of these patients also had a heterozygous mutation in the neutrophil elastase gene, had severe periodontal disease and overgrowth of the periodontal pathogen Actinobacillus actinomycetemcomitans in the dental flora, and 15 permanent teeth had been extracted by the age of 27. One bone marrow-transplanted patient had no periodontal disease. CONCLUSIONS: Normalized ANC levels are not sufficient to maintain normal oral health in SCN patients, and because neutrophils are important for first-line defense and innate immunity, the deficiency of the antibacterial peptide LL-37 probably explains their chronic periodontal disease. Professional dental care is still important for SCN patients, despite treatment with G-CSF and normal ANC levels. Whether antibacterial peptides play a role in the pathogenesis of periodontitis in other patients remains to be elucidated.

  • 4.
    Claesson, Rolf
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Gudmundson, Jan
    Östersund, Sweden.
    Höglund-Åberg, Carola
    Umeå University, Faculty of Medicine, Department of Odontology.
    Haubek, Dorte
    Aarhus, Denmark.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Detection of a 640-bp deletion in the Aggregatibacter actinomycetemcomitans leukotoxin promoter region in isolates from an adolescent of Ethiopian origin2015In: Journal of Oral Microbiology, ISSN 2000-2297, E-ISSN 2000-2297, Vol. 7, article id 26974Article in journal (Refereed)
    Abstract [en]

    The expression of the leukotoxin of Aggregatibacter actinomycetemcomitans is regulated by the leukotoxin promoter. A 530-bp deletion or an 886-bp insertion sequence (IS) element in this region has earlier been described in highly leukotoxic isolates. Here, we report on highly leukotoxic isolate with a 640-bp deletion, which was detected in an adolescent of Ethiopian origin.

  • 5.
    Claesson, Rolf
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Höglund-Åberg, Carola
    Umeå University, Faculty of Medicine, Department of Odontology.
    Haubek, Dorte
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Age-related prevalence and characteristics of Aggregatibacter actinomycetemcomitans in periodontitis patients living in Sweden2017In: Journal of Oral Microbiology, ISSN 2000-2297, E-ISSN 2000-2297, Vol. 9, article id 1334504Article in journal (Refereed)
    Abstract [en]

    Background: The presence of Aggregatibacter actinomycetemcomitans in patients with periodontitis has been extensively studied for decades. Objective: To study the prevalence of A. actinomycetemcomitans in younger and older periodontitis patients and to genetically characterize isolates of this bacterium. Design: Data from microbiological analyses of 3459 subgingival plaque samples collected from 1445 patients, 337 'younger' patients (<= 35 yrs) and 1108 'older' patients (>35 yrs) during 15 years (2000-2014), has been summerized. Isolates of A. actinomycetemcomitans were serotyped, leukotoxin promoter typed (JP2 and non JP2) and arbitrarily primed PCR (APPCR) genotyped. The origin of the JP2 genotype detected in the study population was determined. Results: The prevalence of A. actinomycetemcomitans was higher among younger than older patients and samples from the younger patients contained higher proportions of the bacterium. Serotype b was more prevalent among younger patients and the majorty of these isolates was from the same AP-PCR genotype. The JP2 genotype was detected in 1.2% of the patients, and the majority of these carriers were of non-African origin. Conslusions: For presence and charcteristics of A. actinomycetemcomitans in clinical samples the age of the carriers were a discriminating factor. Additional, apparently non- African carriers of the JP2 genotype of A. actinomycetemcomitans were identified.

  • 6.
    Claesson, Rolf
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Kanasi, Eleni
    Umeå University, Faculty of Medicine, Department of Odontology.
    Anders, Johansson
    Umeå University, Faculty of Medicine, Department of Odontology.
    Sotirios, Kalfas
    School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
    A new cleavage site for elastase within the complement component 32010In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 118, no 10, p. 765-768Article in journal (Refereed)
    Abstract [en]

    The lysosomal enzyme elastase was earlier shown to cleave the complement molecule C3. During somepreliminary experiments on the interactions of certain pathogenic bacteria with the innate defencemechanisms, we observed C3 cleavage, in the presence of elastase, to fragments not previouslydescribed. To elucidate this proteolytic reaction, the present study was conducted. Degradation of C3in mixtures with elastase or cathepsin G was detected by an immunoblot procedure using anti-C3c andanti-C3d antibodies after separating the proteins by SDS-PAGE. Certain C3 fragments were analysedfor amino acid sequence. The results revealed the existence of a cleavage site for elastase at the positionalanine1350 ⁄ lysine1351 of the C3 molecule, which has not been previously described. The fragmentresulted from this cleavage has a size of about 39 kDa and it contains a part or the whole of C3d. Thiscleavage was distinct from the one previously described at position 987 ⁄ 988, which gives a 34 kDaC3d-containing fragment.

  • 7.
    Claesson, Rolf
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Lagervall, Maria
    Department of Periodontology at Skanstull, Stockholm County Council, Stockholm, Sweden.
    Höglund-Åberg, Carola
    Umeå University, Faculty of Medicine, Department of Odontology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Haubek, Dorte
    Department of Pediatric Dentistry, School of Dentistry, Aarhus, Denmark.
    Detection of the highly leucotoxic JP2 clone of Aggregatibacter actinomycetemcomitans in members of a Caucasian family living in Sweden2011In: Journal of Clinical Periodontology, ISSN 0303-6979, E-ISSN 1600-051X, Vol. 38, no 2, p. 115-121Article in journal (Refereed)
    Abstract [en]

    Background: Carriers of the JP2 clone of Aggregatibacter actinomycetemcomitans exhibit an enhanced risk for developing aggressive periodontitis compared with individuals carrying non-JP2 clones. While the JP2 clone is almost exclusively detected among adolescents of African descent, reports on Caucasians colonized with the JP2 clone are remarkably few.

    Objective: The aim of this paper is to report on the history of periodontal disease and microbiological findings in a Caucasian family.

    Material and Methods: A. actinomycetemcomitans and other periodontitis-associated bacterial species in subgingival plaque samples were quantified by conventional culture technique. Leucotoxin promoter typing, serotyping and further characterizations of A. actinomycetemcomitans isolates were performed by PCR. DNA sequencing of the pseudogene, hbpA was performed to determine the origin of the detected JP2 clones. Further, genetically ancestry testing of family members was carried out.

    Results: The JP2 clone was detected in samples from two of the family members, a 33-year-old daughter and her 62-year-old mother. Relationship of their JP2 clones with JP2 clone strains from the Mediterranean area of Africa was indicated. Genotyping confirmed the Caucasian origin of all family members.

    Conclusions: Caucasian JP2 carriers exist and older subjects can carry the JP2 clone of A. actinomycetemcomitans.

  • 8.
    Claesson, Rolf
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Sjögren, Ulf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Esberg, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Brundin, Malin
    Umeå University, Faculty of Medicine, Department of Odontology.
    Granlund, Margareta
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Actinomyces radicidentis and Actinomyces haliotis, coccoid Actinomyces species isolated from the human oral cavity2017In: Anaerobe, ISSN 1075-9964, E-ISSN 1095-8274, Vol. 48, p. 19-26Article in journal (Refereed)
    Abstract [en]

    There are few reports on the bacterial species Actinomyces radicidentis in the literature. In this study, putative A. radicidentis isolates were collected from 16 root canal samples from 601 examined patients. The isolates were examined by biochemical tests, 16S rRNA gene sequencing, Arbitrarily-primed (AP-) PCR, antibiotic susceptibility testing, and MALDI-TOF analyses. In parallel, two A. radicidentis reference strains and two putative A. radicidentis isolates from United Kingdom were tested. Sixteen of the 18 isolates were confirmed as A. radicidentis. The remaining two isolates, both of which were isolated from root canals (one from Sweden and the other from the UK), but were identified as Actinomyces haliotis by sequencing ∼ 1300 base pairs of the 16S rRNA-gene. This isolates had a divergent, but between them similar, AP-PCR pattern, and a common distribution of sequence signatures in the 16S rRNA gene, but were not identified by MALDI-TOF. A. haliotis is a close relative to A. radicidentis, hitherto only been described from a sea-snail. The identity of A. haliotis was confirmed by a phylogenetic tree based on 16S rRNA gene sequences with species specific sequences included, and by additional biochemical tests. The examined bacteria exhibited similar antibiotic susceptibility patterns when tested for 10 separate antibiotic classes with E-tests (bioMérieux). The MIC90 for β-lactams (benzylpenicillin and cefuroxime) and vancomycin was 0.5 mg/L, for colistin and ciprofloxacin 8 mg/mL and for the other antibiotic classes ≤ 25 mg/mL The isolation of A. haliotis from infected dental root canals cast doubt on the accepted opinion that all Actinomyces infections have an endogenous source.

  • 9.
    Dahlén, Gunnar
    et al.
    Göteborgs Universitet.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Höglund Åberg, Carola
    Umeå University, Faculty of Medicine, Department of Odontology, School of Dentistry.
    Haubek, Dorte
    Aarhus University Denmark.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, School of Dentistry.
    Kwamin, Francis
    Ghana University, Ghana.
    Subgingival bacteria in Ghanaian adolescents with or without progression of attachment loss2014In: Journal of Oral Microbiology, ISSN 2000-2297, E-ISSN 2000-2297, Vol. 6, article id 23977Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: This study describes subgingival bacterial profiles associated with clinical periodontal status in Ghanaian adolescents with or without progression of attachment loss.

    MATERIALS AND METHODS: Among 500 adolescents included in a cohort study, 397 returned 2 years later for a periodontal re-examination, including full-mouth CAL measurements. At follow-up, a subgroup of 98 adolescents was also subjected to bacterial sampling with paper points at four periodontal sites (mesial aspect of 11, 26, 31, and 46) and analyzed with the checkerboard DNA-DNA hybridization technique against DNA-probes from nine periodontitis-associated bacterial species.

    RESULTS: The 98 Ghanaian adolescents examined in the present study were similar to the entire group examined at the 2-year follow-up with respect to age, gender, and CAL ≥3 mm. A high detection frequency of Fusobacterium nucleatum and Prevotella intermedia (>99%) using checkerboard analysis was found, while for Aggregatibacter actinomycetemcomitans the detection frequency was <50%. A strong correlation was found at the individual level between the presence of P. intermedia and the total CAL change, and P. intermedia and Porphyromonas gingivalis were strongly correlated with a change in CAL and probing pocket depth (PPD) at the sampled sites. In a linear regression model, a significant discriminating factor for the total CAL change in the dentition during the 2-year follow-up period was obtained for P. intermedia and public school.

    CONCLUSION: This study indicates that subgingival bacterial species other than A. actinomycetemcomitans, for example, P. intermedia, have a significant association with periodontal breakdown (change in CAL) in Ghanaian adolescents with progression of periodontal attachment loss.

  • 10.
    Ennibi, Oum Keltoum
    et al.
    Department of Periodontology, School of Dentistry, Mohammed V University, Morocco.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Akkaoui, Sanae
    Laboratory of Oral Microbiology and Biotechnology, School of Dentistry, Mohammed V University in Rabat, Morocco.
    Reddahi, Sarah
    Department of Periodontology, School of Dentistry, Mohammed V University, Morocco.
    Kwamin, Francis
    Dental School University of Ghana, Ghana.
    Haubek, Dorte
    Section for Pediatric Dentistry, Department of Dentistry and Oral Health, Aarhus University, Denmark.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    High salivary levels of JP2 genotype of Aggregatibacter actinomycetemcomitans is associated with clinical attachment loss in Moroccan adolescents2019In: Clinical and experimental dental research, ISSN 2057-4347, Vol. 5, no 1, p. 44-51Article in journal (Refereed)
    Abstract [en]

    It has previously been shown that the presence of Aggregatibacter actinomycetemcomitans in subgingival plaque is significantly associated with increased risk for clinical attachment loss. The highly leukotoxic JP2 genotype of this bacterium is frequently detected in adolescents with aggressive forms of periodontitis. The aims of the study were to quantify the levels of JP2 and non-JP2 genotypes of A. actinomycetemcomitans in saliva of Moroccan adolescents with the JP2 genotype earlier detected in the subgingival plaque. The salivary concentrations of inflammatory proteins were quantified and linked to the clinical parameters and microbial findings. Finally, a mouth rinse with leukotoxin-neutralizing effect was administrated and its effect on the levels the biomarkers and A. actinomycetemcomitans examined. The study population consisted of 22 adolescents that previously were found to be positive for the JP2 genotype in subgingival plaque. Periodontal registration and sampling of stimulated saliva was performed at baseline. A mouth rinse (active/placebo) was administrated, and saliva sampling repeated after 2 and 4 weeks rinse. The salivary levels of JP2 and non-JP2 were analyzed by quantitative PCR and inflammatory proteins by ELISA. Both the JP2 and the non-JP2 genotype were detected in all individuals with significantly higher levels of the non-JP2. Enhanced levels of the JP2 genotype of A. actinomycetemcomitans was significantly correlated to the presence of attachment loss (≥3 mm). Salivary concentrations of inflammatory biomarkers did not correlate to periodontal condition or levels of A. actinomycetemcomitans. The use of active or placebo leukotoxin-neutralizing mouth rinse did not significantly interfered with the levels of these biomarkers. Saliva is an excellent source for detection of A. actinomycetemcomitans on individual basis, and high levels of the JP2 genotype were significantly associated with the presence of clinical attachment loss.

  • 11.
    Esberg, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Sheng, Nongfei
    Umeå University, Faculty of Medicine, Department of Odontology.
    Mårell, Lena
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Persson, Karina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Borén, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Strömberg, Nicklas
    Umeå University, Faculty of Medicine, Department of Odontology.
    Streptococcus Mutans Adhesin Biotypes that Match and Predict Individual Caries Development2017In: EBioMedicine, ISSN 0360-0637, E-ISSN 2352-3964, Vol. 24, p. 205-215Article in journal (Refereed)
    Abstract [en]

    Dental caries, which affects billions of people, is a chronic infectious disease that involves Streptococcus mutans, which is nevertheless a poor predictor of individual caries development. We therefore investigated if adhesin types of S.mutans with sucrose-independent adhesion to host DMBT1 (i.e. SpaP A, B or C) and collagen (i.e. Cnm, Cbm) match and predict individual differences in caries development. The adhesin types were measured in whole saliva by qPCR in 452 12-year-old Swedish children and related to caries at baseline and prospectively at a 5-year follow-up. Strains isolated from the children were explored for genetic and phenotypic properties. The presence of SpaP B and Cnm subtypes coincided with increased 5-year caries increment, and their binding to DMBT1 and saliva correlated with individual caries scores. The SpaP B subtypes are enriched in amino acid substitutions that coincided with caries and binding and specify biotypes of S. mutans with increased acid tolerance. The findings reveal adhesin subtypes of S. mutans that match and predict individual differences in caries development and provide a rationale for individualized oral care.

  • 12. Hirschfeld, Josefine
    et al.
    Roberts, Helen M
    Chapple, Iain L C
    Parčina, Marijo
    Jepsen, Søren
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Effects of Aggregatibacter actinomycetemcomitans leukotoxin on neutrophil migration and extracellular trap formation.2016In: Journal of Oral Microbiology, ISSN 2000-2297, E-ISSN 2000-2297, Vol. 8, article id 33070Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Aggressive periodontitis is associated with the presence of Aggregatibacter actinomycetemcomitans, a leukotoxin (Ltx)-producing periodontal pathogen. Ltx has the ability to lyse white blood cells including neutrophils.

    OBJECTIVES: This study was aimed at investigating the interactions between neutrophils and Ltx with regard to the chemotactic properties of Ltx and the release of neutrophil extracellular traps (NETs).

    METHODS: Neutrophils from healthy blood donors were isolated and incubated for 30 min and 3 h with increasing concentrations of Ltx (1, 10, and 100 ng/mL) as well as with A. actinomycetemcomitans strains (NCTC 9710 and HK 1651) producing different levels of Ltx. Formation of NETs and cell lysis were assessed by microscopy, fluorescence-based assays, and measurement of released lactate dehydrogenase. Neutrophil migration in response to different Ltx gradients was monitored by real-time video microscopy, and image analysis was performed using ImageJ software.

    RESULTS: Although Ltx (10 and 100 ng/mL) and the leukotoxic A. actinomycetemcomitans strain HK 1651 lysed some neutrophils, other cells were still capable of performing NETosis in a concentration-dependent manner. Low doses of Ltx and the weakly leukotoxic strain NCTC 9710 did not lead to neutrophil lysis, but did induce some NETosis. Furthermore, all three concentrations of Ltx enhanced random neutrophil movement; however, low directional accuracy was observed compared with the positive control (fMLP).

    CONCLUSIONS: The results indicate that Ltx acts both as a neutrophil activator and also causes cell death. In addition, Ltx directly induces NETosis in neutrophils prior to cell lysis. In future studies, the underlying pathways involved in Ltx-meditated neutrophil activation and NETosis need to be investigated further.

  • 13.
    Holgerson, Pernilla L
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Vestman, Nelly R
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Öhman, Carina
    Umeå University, Faculty of Medicine, Department of Odontology.
    Domellöf, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
    Tanner, Anne CR
    Hernell, Olle
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
    Johansson, Ingegerd
    Umeå University, Faculty of Medicine, Department of Odontology.
    Oral microbial profile discriminates breast-fed from formula-fed infants2013In: Journal of Pediatric Gastroenterology and Nutrition - JPGN, ISSN 0277-2116, E-ISSN 1536-4801, Vol. 56, no 2, p. 127-136Article in journal (Refereed)
    Abstract [en]

    Objectives: Little is known about the effect of diet on the oral microbiota of infants, although diet is known to affect the gut microbiota. The aims of the present study were to compare the oral microbiota in breast-fed and formula-fed infants, and investigate growth inhibition of streptococci by infant-isolated lactobacilli.

    Methods: A total of 207 mothers consented to participation of their 3-month-old infants. A total of 146 (70.5%) infants were exclusively and 38 (18.4%) partially breast-fed, and 23 (11.1%) were exclusively formula-fed. Saliva from all of their infants was cultured for Lactobacillus species, with isolate identifications from 21 infants. Lactobacillus isolates were tested for their ability to suppress Streptococcus mutans and S sanguinis. Oral swabs from 73 infants were analysed by the Human Oral Microbe Identification Microarray (HOMIM) and by quantitative polymerase chain reaction for Lactobacillus gasseri.

    Results: Lactobacilli were cultured from 27.8% of exclusively and partially breast-fed infants, but not from formula-fed infants. The prevalence of 14 HOMIM-detected taxa, and total salivary lactobacilli counts differed by feeding method. Multivariate modelling of HOMIM-detected bacteria and possible confounders clustered samples from breast-fed infants separately from formula-fed infants. The microbiota of breast-fed infants differed based on vaginal or C-section delivery. Isolates of L plantarum, L gasseri, and L vaginalis inhibited growth of the cariogenic S mutans and the commensal S sanguinis: L plantarum >L gasseri >L vaginalis.

    Conclusions: The microbiota of the mouth differs between 3-month-old breast-fed and formula-fed infants. Possible mechanisms for microbial differences observed include species suppression by lactobacilli indigenous to breast milk.

  • 14.
    Höglund Åberg, Carola
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Molecular Periodontology.
    Antonoglou, Georgios
    Umeå University, Faculty of Medicine, Department of Odontology, Molecular Periodontology.
    Haubek, Dorte
    Section for Pediatric Dentistry, Department of Dentistry, Health, Århus University, Århus, Denmark.
    Kwamin, Francis
    Dental School University of Ghana, Accra, Ghana.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Cytolethal distending toxin in isolates of Aggregatibacter actinomycetemcomitans from Ghanaian adolescents and association with serotype and disease progression 2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 6, p. e65781-Article in journal (Refereed)
    Abstract [en]

    Background and Objectives: The cytolethal distending toxin (Cdt) is a highly conserved exotoxin that are produced by a number of Gram negative bacteria, including Aggregatibacter actinomycetemcomitans, and affects mammalian cells by inhibiting cell division and causing apoptosis. A complete cdt-operon is present in the majority of A. actinomycetemcomitans, but the proportion of isolates that lack cdt-encoding genes (A, B and C) varies according to the population studied. The objectives of this study were to examine serotype, Cdt-genotype, and Cdt-activity in isolates of A. actinomycetemcomitans collected from an adolescent West African population and to examine the association between the carrier status of A. actinomycetemcomitans and the progression of attachment loss (AL).

    Material and Methods: A total of 249 A. actinomycetemcomitans isolates from 200 Ghanaian adolescents were examined for serotype and cdt-genotype by PCR. The activity of the Cdt-toxin was examined by DNA-staining of exposed cultured cells and documented with flow cytometry. The periodontal status of the participants was examined at baseline and at a two-year follow-up.

    Results: Presence of all three cdt-encoding genes was detected in 79% of the examined A. actinomycetemcomitans isolates. All these isolates showed a substantial Cdt-activity. The two different cdt-genotypes (with and without presence of all three cdt-encoding genes) showed a serotype-dependent distribution pattern. Presence of A. actinomycetemcomitans was significantly associated with progression of AL (OR = 5.126; 95% CI = [2.994 - 8.779], p < 0.001).

    Conclusion: A. actinomycetemcomitans isolated from the Ghanaian adolescents showed a distribution of serotype and cdt-genotype in line with results based on other previously studied populations. Presence of A. actinomycetemcomitans was significantly associated with disease progression, in particular the b serotype, whereas the association with disease progression was not particularly related to cdt-genotype, and Cdt-activity.

  • 15.
    Höglund Åberg, Carola
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Haubek, Dorte
    Århus University.
    Kwamin, Francis
    Ghana University.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Leukotoxic activity of Aggregatibacter actinomycetemcomitans and periodontal attachment loss2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 8, p. e104095-Article in journal (Refereed)
    Abstract [en]

    Aggregatibacter actinomycetemcomitans is a Gram-negative periodontitis-associated bacterium that expresses a toxin that selectively affects leukocytes. This leukotoxin is encoded by an operon belonging to the core genome of this bacterial species. Variations in the expression of the leukotoxin have been reported, and a well-characterized specific clonal type (JP2) of this bacterium with enhanced leukotoxin expression has been isolated. In particular, the presence of the JP2 genotype significantly increases the risk for the progression of periodontal attachment loss (AL). Based on these findings we hypothesized that variations in the leukotoxicity are linked to disease progression in infected individuals. In the present study, the leukotoxicity of 239 clinical isolates of A. actinomycetemcomitans was analysed with different bioassays, and the genetic peculiarities of the isolates were related to their leukotoxicity based on examination with molecular techniques. The periodontal status of the individuals sampled for the presence of A. actinomycetemcomitans was examined longitudinally, and the importance of the observed variations in leukotoxicity was evaluated in relation to disease progression. Our data show that high leukotoxicity correlates with an enhanced risk for the progression of AL. The JP2 genotype isolates were all highly leukotoxic, while the isolates with an intact leukotoxin promoter (non-JP2 genotypes) showed substantial variation in leukotoxicity. Genetic characterization of the non-JP2 genotype isolates indicated the presence of highly leukotoxic genotypes of serotype b with similarities to the JP2 genotype. Based on these results, we conclude that A. actinomycetemcomitans harbours other highly virulent genotypes besides the previously described JP2 genotype. In addition, the results from the present study further highlight the importance of the leukotoxin as a key virulence factor in aggressive forms of periodontitis.

  • 16.
    Höglund Åberg, Carola
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Kwamin, Francis
    Ghana University.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Dahlén, Gunnar
    Göteborgs Universitet.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Haubek, Dorte
    Århus Universitet, Danmark.
    Progression of attachment loss is strongly associated with presence of the JP2 genotype of Aggregatibacter actinomycetemcomitans: a prospective cohort study of a young adolescent population2014In: Journal of Clinical Periodontology, ISSN 0303-6979, E-ISSN 1600-051X, Vol. 41, no 3, p. 232-241Article in journal (Refereed)
    Abstract [en]

    AIM: To assess the progression of attachment loss (AL) during a two-year period according to the presence of JP2 and non-JP2 genotypes of A. actinomycetemcomitans in a Ghanaian adolescent population.

    METHODS: A total of 500 adolescents (mean age 13.2 years, SD± 1.5) were enrolled in the study. After two years, 397 (79.4%) returned for a periodontal re-examination, including the measurement of AL. The carrier status of the JP2 and non-JP2 genotypes of A. actinomycetemcomitans was evaluated in a baseline examination two years earlier.

    RESULTS: Individuals who carried the JP2 genotype of A. actinomycetemcomitans had a significantly increased risk (relative risk (RR) = 7.3) of developing AL ≥ 3 mm. The mean AL at the follow-up and the mean two-year progression of AL was significantly higher in the JP2 genotype-positive group (n=38) compared with the group positive for the non-JP2 genotypes of A. actinomycetemcomitans (n=169), and the group of A. actinomycetemcomitans-negative individuals (n=190). The JP2 genotype was strongly associated with the progression of AL ≥ 3 mm (OR= 14.3). The non-JP2 genotypes of A. actinomycetemcomitans were also, however less pronounced, associated with the progression of AL ≥ 3 mm (OR=3.4).

    CONCLUSION: The JP2 genotype of A. actinomycetemcomitans is strongly associated with the progression of AL.

  • 17.
    Höglund Åberg, Carola
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Molecular Periodontology.
    Kwamin, Francis
    Univ Ghana, Sch Dent, Accra, Ghana.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Molecular Periodontology. Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Haubek, Dorte
    Århus Univ, Dept Dent, Århus, Denmark.
    Presence of JP2 and Non-JP2 genotypes of aggregatibacter actinomycetemcomitans and periodontal attachment loss in adolescents in Ghana2012In: Journal of Periodontology, ISSN 0022-3492, E-ISSN 1943-3670, Vol. 83, no 12, p. 1520-1528Article in journal (Refereed)
    Abstract [en]

    Background: Limited data are reported concerning the presence of A. actinomycetemcomitans and attachment loss (AL) in sub-Saharan countries. The authors investigate the carrier frequency of JP2 and non-JP2 genotypes of A. actinomycetemcomitans and the presence of AL in Ghanaian adolescents and evaluate socioeconomic conditions and oral hygiene practices. Methods: Five hundred individuals (mean +/- SD age: 13.2 +/- 1.5 years) in public and private schools were interviewed about demographic characteristics and oral hygiene practices and were given a full-mouth periodontal examination. Subgingival plaque samples were obtained from periodontal sites around permanent first molars and incisors. The carrier status of A. actinomycetemcomitans at the individual level was determined based on results obtained by cultivation and polymerase chain reaction. Results: The findings of this study show a relatively high carrier rate of JP2 and non-JP2 genotypes of Aggregatibacter actinomycetemcomitans in the Ghanaian adolescent population and the presence of this bacterium is associated with the occurrence of AL. The overall carrier rate of A. actinomycetemcomitans was 54.4%, and the highly leukotoxic JP2 genotype was detected in 8.8% of the study population. A total of 107 (21.4%) individuals had >= 1 tooth with AL >= 3 mm. The majority of the individuals carrying A. actinomycetemcomitans (80.1%) (P<0.001) and of the periodontally diseased individuals (91.6%) (P<0.001) were found in public schools. Conclusions: A. actinomycetemcomitans and AL were frequently found in Ghanaian adolescents. The school type was the strongest predictor of both presence of A. actinomycetemcomitans and AL.

  • 18.
    Jensen, Anne B.
    et al.
    Aarhus University, Denmark.
    Haubek, Dorte
    Aarhus University, Denmark.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Nørskov-Lauritsen, Niels
    Aarhus University, Denmark.
    Comprehensive antimicrobial susceptibility testing of a large collection of clinical strains of Aggregatibacter actinomycetemcomitans does not identify resistance to amoxicillin2019In: Journal of Clinical Periodontology, ISSN 0303-6979, E-ISSN 1600-051X, Vol. 46, no 8, p. 846-854Article in journal (Refereed)
    Abstract [en]

    AIM: The present study aims to determine the susceptibility of Aggregatibacter actinomycetemcomitans to amoxicillin by investigating a large collection of oral strains of diverse geographical origin.

    METHODS: Two hundred and fifty-seven A. actinomycetemcomitans strains were serotyped using a multiplex polymerase chain reaction, and minimal inhibitory concentration (MIC) values of amoxicillin were determined using the agar dilution method (range 0.25 to 8.0 mg/L). The plates were spot-wise inoculated with approximately 104 colony-forming units, incubated in 5% CO2 at 37 C°, and visually inspected after 24 and 48 hours. A MIC ≤ 2.00 mg/L was categorised as susceptible using EUCAST interpretative criteria for Haemophilus species.

    RESULTS: Amoxicillin MIC-values varied from 0.25 mg/L to 2.00 mg/L, and all tested strains, including strains previously reported as resistant, were susceptible to amoxicillin. The MIC50 was 1.00 mg/L and the MIC90 was 2.00 mg/L.

    CONCLUSION: Meticulous investigation of strains including isolates previously reported as resistant could not confirm the emergence of resistance to β-lactams in A. actinomycetemcomitans. Based on the present in vitro results, amoxicillin can be considered a key oral antimicrobial agent for treatment of A. actinomycetemcomitans. This article is protected by copyright. All rights reserved.

  • 19.
    Jensen, Anne Birkeholm
    et al.
    Aarhus University, Aarhus, Denmark.
    Lund, Marianne
    Aarhus University, Aarhus, Denmark.
    Nørskov-Lauritsen, Niels
    Aarhus University, Aarhus, Denmark.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Reinholdt, Jesper
    Aarhus University, Aarhus, Denmark.
    Haubek, Dorte
    Aarhus University, Aarhus, Denmark.
    Differential Cell Lysis Among Periodontal Strains of JP2 and Non-JP2 Genotype of Aggregatibacter actinomycetemcomitans Serotype B Is Not Reflected in Dissimilar Expression and Production of Leukotoxin2019In: Pathogens, ISSN 2076-0817, Vol. 8, no 4, article id 211Article in journal (Refereed)
    Abstract [en]

    Leukotoxic potential of Aggregatibacter actinomycetemcomitans strains has been studied by the use of several methods, and results differ depending on the methods used. The aim of the present study was to perform a comprehensive examination of the leukotoxic potential of a collection of A. actinomycetemcomitans strains by use of three quantitative methods, Western blotting, ELISA, and mRNA expression assay and compare these results with previous data obtained by a cell lysis assay. A higher leukotoxic potential among JP2 genotype strains compared to non-JP2 genotype strains of A. actinomycetemcomitans was found by Western blotting, ELISA and mRNA expression assay. Leukotoxicity as determined by cell lysis assay showed a variation among strains examined, not only depending on being part of JP2 genotype vs. non-JP2 genotype group of A. actinomycetemcomitans. The leukotoxicity of A. actinomycetemcomitans strains as determined by cell lysis assay did not correspond to the leukotoxic potential of A. actinomycetemcomitans strains as determined by three quantitative methods. A comparison of the results obtained by ELISA and mRNA expression assay showed a reasonable correlation between these two methods. It seems important to use more than one method to assess the LtxA-related virulence capacity of A. actinomycetemcomitans in order to obtain comprehensive understanding of the leukotoxic potential of A. actinomycetemcomitans strains.

  • 20.
    Johansson, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Hänström, Lennart
    Umeå University, Faculty of Medicine, Department of Odontology.
    Kalfas, S
    Umeå University, Faculty of Medicine, Department of Odontology.
    Serum-mediated release of leukotoxin from the cell surface of the periodontal pathogen Actinobacillus actinomycetemcomitans.2003In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 111, no 3, p. 209-215Article in journal (Refereed)
    Abstract [en]

    The leukotoxin of the periodontopathogen Actinobacillus actinomycetemcomitans is an important virulence factor that lyses human neutrophils and monocytes and thus, it may enable the bacterium to evade the local host defense. The toxin also induces degranulation of neutrophils and cytokine release in monocytes. To trigger these biological activities, leukotoxin has to be released from the bacterium and diffuse into the periodontal tissues. To date, the conditions found to cause toxin release have been artificial and have included high ion concentration and alkaline conditions. To study the release of the toxin under conditions mimicking the natural environment of the periodontium the ability of human serum to enable leukotoxin release from the bacterial surface was examined. Suspensions of leukotoxic A. actinomycetemcomitans strains were incubated with various concentrations of human serum or serum albumin. The suspensions were centrifuged and the leukotoxin in the supernatants or the cell pellets was detected by gel electrophoresis and immunoblotting. Serum was found to cause the rapid release of leukotoxin from the bacteria in a concentration-dependent manner. Pure albumin exhibited a similar effect. The leukotoxin released was active against human neutrophils. Only a minor proportion of it was associated with membranous vesicles produced by the bacteria. The results indicate that serum, a fluid closely related to the exudate in inflamed periodontal pockets, releases leukotoxin from the cell surface of A. actinomycetemcomitans. The process may enable the diffusion of the toxin from the bacterial biofilm into the surrounding tissues, where it can exert its biological effect.

  • 21.
    Johansson, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Höglund Åberg, Carola
    Umeå University, Faculty of Medicine, Department of Odontology.
    Haubek, D.
    Oscarsson, Jan
    Umeå University, Faculty of Medicine, Department of Odontology.
    The cagE gene sequence as a diagnostic marker to identify JP2 and non-JP2 highly leukotoxic Aggregatibacter actinomycetemcomitans serotype b strains.2017In: Journal of Periodontal Research, ISSN 0022-3484, E-ISSN 1600-0765, Vol. 52, no 5, p. 903-912Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND OBJECTIVE:Aggregatibacter actinomycetemcomitans is involved in oral and systemic infections, and is associated with, eg aggressive forms of periodontitis and with endocarditis. The cagE gene encodes a ≈39 kDa putative exotoxin expressed by A. actinomycetemcomitans. The level of conservation of cagE, and its possible significance in periodontal disease, has not yet been thoroughly investigated. In the present study, the role of the cagE gene as a diagnostic marker has been investigated.

    MATERIAL AND METHODS:We have used conventional polymerase chain reaction (PCR), quantitative PCR and whole genome sequencing data to determine the prevalence of cagE in A. actinomycetemcomitans based on analysis of: (i) 249 isolates, collected and cultivated in a Ghanaian longitudinal cohort study; (ii) a serotype b collection of 19 strains; and (iii) the 36 A. actinomycetemcomitans genomes available in the NCBI database.

    RESULTS:Whereas cagE was absent in the other serotypes, our data support that this gene sequence is linked to a virulent and highly leukotoxic group of serotype b strains, including both JP2 and non-JP2 genotypes of A. actinomycetemcomitans.

    CONCLUSION:We propose that cagE has the potential to be used as a PCR-based gene marker for the identification of a virulent and highly leukotoxic group of serotype b strains, including both JP2 and non-JP2 genotypes. This finding might be of importance in the risk assessment of the development of periodontal attachment loss in young individuals and hence suggested to be a relevant discovery in future development of new diagnostic tools and/or treatment strategies.

  • 22.
    Johansson, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Höglund-Åberg, Carola
    Umeå University, Faculty of Medicine, Department of Odontology.
    Haubek, Dorte
    Lindholm, Mark
    Umeå University, Faculty of Medicine, Department of Odontology.
    Jasim, Sarah
    Umeå University, Faculty of Medicine, Department of Odontology.
    Oscarsson, Jan
    Umeå University, Faculty of Medicine, Department of Odontology.
    Genetic Profiling of Aggregatibacter actinomycetemcomitans Serotype B Isolated from Periodontitis Patients Living in Sweden2019In: Pathogens, ISSN 2076-0817, Vol. 8, no 3, p. 1-13, article id 153Article in journal (Refereed)
    Abstract [en]

    The bacterium Aggregatibacter actinomycetemcomitans is associated with aggressive forms of periodontitis and with systemic diseases, such as endocarditis. By assessing a Ghanaian longitudinal adolescent cohort, we earlier recognized the cagE gene as a possible diagnostic marker for a subgroup of JP2 and non-JP2 genotype serotype b A. actinomycetemcomitans strains, associated with high leukotoxicity as determined in a semi-quantitative cell assay. This group of A. actinomycetemcomitans is associated with the progression of attachment loss. In the present work, we used conventional polymerase chain reaction (PCR) and quantitative PCR to perform the cagE genotyping of our collection of 116 selected serotype b A. actinomycetemcomitans strains, collected over a period of 15 years from periodontitis patients living in Sweden. The A. actinomycetemcomitans strains carrying cagE (referred to as cagE+; n = 49) were compared to the cagE-negative strains (n = 67), present at larger proportions in the subgingival plaque samples, and were also much more prevalent in the young (≤35 years) compared to in the old (>35 years) group of patients. Our present results underline the potential use of cagE genotyping in the risk assessment of the development of periodontal attachment loss in Swedish adolescents.

  • 23.
    Johansson, Elisabeth
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Hygiene.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    van Dijken, J W V
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Hygiene.
    Antibacterial effect of ozone on cariogenic bacterial species.2009In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 37, no 6, p. 449-453Article in journal (Refereed)
    Abstract [en]

    Objective: The aim was to evaluate the antibacterial effect of ozone on cariogenic bacterial species with and without the presence of saliva and a possible effect on the salivary proteins.

    Methods: Suspensions of Actinomyces naeslundii (ACTCC 12104T), Lactobacilli casei (N CTC 151) and Streptococcus mutans (NCTC 10449), in salt buffer or in saliva, were exposed to ozone gas delivered by the ozone generator Healozone™ 2130C. Aliquots of the suspensions were taken after 10, 30 and 60s ozone exposures and cultivated on agar plates. Initial number of bacteria per ml was 8.0×107 (SD 2.2×107) (A. naeslundii), 1.0×108 (SD 3.1×106) (L. casei) and 1.0×108 (SD 7.0×105) (S. mutans), respectively. The proteins were separated by SDS electrophoresis and visualized by silver staining.

    Results: In salt buffer 92%, 73% and 64% of the initial numbers of A. naeslundiiS. mutans and L. casei, respectively, were killed already after 10s ozone exposure, while approximately 99.9% of the bacteria were dead after a 60s exposure. After 10 and 30s, but not after 60s exposure to ozone, S. mutans and L. casei were less efficiently killed in saliva compared to the salt buffer. Various saliva proteins were degraded by ozone after a 60s exposure.

    Conclusions:The cariogenic species S. mutansL. casei and A. naeslundii were almost eliminated following 60s of ozone treatment. This killing was reduced in the presence of saliva although increasing the ozone application time to 60s overcame these reductants in saliva. Detection of altered salivary proteins indicates that saliva components constitute additional targets for ozone.

  • 24.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Abd, H
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Sandström, G
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Cellular and molecular response of human macrophages exposed to Aggregatibacter actinomycetemcomitans leukotoxin.2011In: Cell death & disease, ISSN 2041-4889, Vol. 2, p. e126-Article in journal (Refereed)
    Abstract [en]

    Aggregatibacter (Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative bacterium associated with severe forms of periodontitis. A leukotoxin, which belongs to the repeats-in-toxin family, is believed to be one of its virulence factors and to have an important role in the bacterium's pathogenicity. This toxin selectively kills human leukocytes by inducing apoptosis and lysis. Here, we report that leukotoxin-induced cell death of macrophages proceeded through a process that differs from the classical characteristics of apoptosis and necrosis. A. actinomycetemcomitans leukotoxin-induced several cellular and molecular mechanisms in human macrophages that led to a specific and excessive pro-inflammatory response with particular secretion of both interleukin (IL)-1β and IL-18. In addition, this pro-inflammatory cell death was inhibited by oxidized ATP, which indicates involvement of the purinergic receptor P2X(7) in this process. This novel virulence mechanism of the leukotoxin may have an important role in the pathogenic potential of this bacterium and can be a target for future therapeutic agents.

  • 25.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology. Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Abd, Hadi
    Centre for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, Solna, Sweden.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Sandström, Gunnar
    Centre for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, Solna, Sweden ; Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institute, Stockholm, Sweden.
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Inflammatory cell death of human macrophages in response to Aggregatibacter actinomycetemcomitans leukotoxinManuscript (Other academic)
    Abstract [en]

    Aggregatibacter (Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative bacterium associated with severe forms of periodontitis. A leukotoxin, which belongs to the Repeats in Toxin (RTX) family, is believed to be one of its virulence factors and to play an important role in the bacterium's pathogenicity. This toxin selectively kills human leukocytes by inducing apoptosis and lysis. Here we report that leukotoxin-induced cell death of macrophages proceeded through a process that differs from the classical characteristics of apoptosis and necrosis. Interestingly, this process resembled pyroptosis, and resulted in an extensive leukotoxin-induced interleukin-1β (IL-1β) secretion. This activation was mainly mediated by caspase-1 activation, while the levels of mRNA for IL-1β were not affected by the leukotoxin. A similar pattern was seen for IL-18, but the level of that cytokine was about 30 times lower. Both of these cytokines are synthesized as biologically inactive precursors and need active caspase-1 for their activation and secretion. In conclusion, A. actinomycetemcomitans leukotoxin induces a pyroptosis-like cell death in human macrophages and that leads to a specific and excessive pro-inflammatory response. This novel virulence mechanism of the leukotoxin may play an important role in the pathogenic potential of this bacterium.

  • 26.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology. Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Chen, Casey
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology. Parod.
    IL-1beta secretion induced by Aggregatibacter (Actinobacillus) actinomycetemcomitans is mainly caused by the leukotoxin2008In: International Journal of Medical Microbiology, ISSN 1438-4221, E-ISSN 1618-0607, Vol. 298, no 5/6, p. 529-541Article in journal (Refereed)
    Abstract [en]

    Aggregatibacter (Actinobacillus) actinomycetemcomitans forms a leukotoxin that selectively lyses primate neutrophils, monocytes and triggers apoptosis in promyeloic cells and degranulation of human neutrophils. Recently, we showed that the leukotoxin causes activation of caspase-1 and abundant secretion of bio-active IL-1beta from human macrophages. In this study, we show that high levels of IL-beta correlated with a high proportion of A. actinomycetemcomitans in clinical samples from a patient with aggressive periodontitis. To determine the relative contribution of leukotoxin to the overall bacteria-induced IL-1beta secretion, macrophages were isolated from peripheral blood and exposed to different concentrations of live A. actinomycetemcomitans strains with either no, low or high production of leukotoxin. Cell lysis and levels of IL-1beta, IL-6, TNF-alpha and caspase-1 were measured by ELISA and flow cytometry. Leukotoxin was the predominant cause of IL-1beta secretion from macrophages, even in the A. actinomycetemcomitans strain with low leukotoxin production. Macrophages exposed to non-leukotoxic bacteria accumulated cytosolic pro-IL-1beta, which was secreted by a secondary exposure to leukotoxic bacteria. In conclusion, the present study shows for the first time that A. actinomycetemcomitans-induced IL-1beta secretion from human macrophages in vitro is mainly caused by leukotoxin.

  • 27.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Hänström, L
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Lerner, Ulf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Cell Biology.
    Kalfas, S
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Abundant secretion of bioactive interleukin-1beta by human macrophages induced by Actinobacillus actinomycetemcomitans leukotoxin2005In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 73, no 1, p. 453-458Article in journal (Refereed)
    Abstract [en]

    Actinobacillus actinomycetemcomitans produces a leukotoxin that selectively kills human leukocytes. Recently, we reported that macrophages are highly sensitive to leukotoxin and that their lysis involves activation of caspase 1. In this study, we show that leukotoxin also induces the production and release of proinflammatory cytokines from human macrophages. The macrophages were challenged with leukotoxin or lipopolysaccharide (LPS) from A. actinomycetemcomitans or LPS from Escherichia coli, and the production and secretion of interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor alpha (TNF-alpha) were determined at the mRNA and protein levels by reverse transcription-PCR and enzyme-linked immunosorbent assay, respectively. Leukotoxin (1 to 30 ng/ml) induced abundant production and secretion of IL-1beta, while the effects on IL-6 and TNF-alpha production were limited. Leukotoxin (1 ng/ml) caused a 10-times-higher release of IL-1beta than did LPS (100 ng/ml). The secreted IL-1beta was mainly the bioactive 17-kDa protein. At higher concentrations (>30 ng/ml), leukotoxin caused secretion of mainly inactive cytokine, the 31-kDa pro-IL-1beta. The presence of specific antibodies to IL-1beta or of a caspase 1 inhibitor blocked the secretion and production of the cytokine. Supernatants of leukotoxin-challenged macrophages stimulated bone resorption when tested in a mouse calvarial model. The activity could be blocked by an IL-1 receptor antagonist or specific antibodies to IL-1beta. We concluded that A. actinomycetemcomitans leukotoxin can trigger abundant production and secretion of bioactive IL-1beta by human macrophages, which is mediated by activation of caspase 1.

  • 28.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Hänström, L
    Kalfas, S
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Caspase 1 involvement in human monocyte lysis induced by Actinobacillus actinomycetemcomitans leukotoxin2003In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 71, no 8, p. 4448-4455Article in journal (Refereed)
    Abstract [en]

    Actinobacillus actinomycetemcomitans, an oral bacterium implicated in the etiology of periodontal diseases, produces a leukotoxin that selectively lyses primate neutrophils and monocytes, the major populations of defense cells in the periodontium. Though lysis requires expression of the receptor lymphocyte function-associated molecule 1 (LFA-1) on the cell surface, not all LFA-1-expressing leukocyte populations are equally susceptible to the toxin. In this study, the susceptibility of human leukocytes to leukotoxin-induced lysis is compared to their expression of LFA-1 and the activity of caspase 1. Cytolysis was determined by the activity of lactate dehydrogenase released from peripheral human leukocytes after 1-h exposure to leukotoxin. Monocytes were lysed at leukotoxin concentrations of > or = 5 ng/ml, while the corresponding values for neutrophils and lymphocytes were approximately 10 times greater. Similar LFA-1 expression was found in all susceptible cell populations irrespective of their degree of sensitivity to the toxin. Exposure of monocytes to leukotoxin increased their caspase 1 activity about fivefold within 10 to 20 min. Presence of the caspase 1 inhibitor Ac-YVAD-CMK significantly blocked the leukotoxin-induced lysis of monocytes only. At sublytic concentrations, leukotoxin induced no apoptotic activity in monocytes, as revealed by the lack of caspase 3 activation and DNA fragmentation. Monocytes are the most lysis-sensitive leukocytes for A. actinomycetemcomitans leukotoxin. Their lysis by this toxin depends on caspase 1 activation and proceeds through a process that differs from classical apoptosis.

  • 29.
    Konradsson, Katarina
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Hygiene.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    van Dijken, Jan
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Hygiene.
    Dental biofilm, gingivitis and interleukin-1 adjacent to approximal sites of a bonded ceramic.2007In: Journal of Clinical Periodontology, ISSN 0303-6979, E-ISSN 1600-051X, Vol. 34, no 12, p. 1062-1067Article in journal (Refereed)
    Abstract [en]

    Aim: The aim of this study was to investigate in vivo the influence of aged, resin-bonded, ceramic restorations on approximal dental biofilm formation and gingival inflammatory response, associated with and without customary oral hygiene. Material and Methods: In a cross-sectional and in a 10-day experimental gingivitis study, Quigley-Hein plaque index, gingival index (GI), crevicular fluid and its levels of interleukin (IL)-1alpha, -1beta and receptor antagonist were measured at appoximal surfaces of leucite-reinforced bonded ceramic coverages, resin composite restorations and enamel and compared intra-individually in 17 participants. Results: No differences were found between the ceramic, composite and enamel regarding plaque index, GI, levels of IL-1alpha, -1beta and the receptor antagonist. Throughout, higher crevicular fluid amounts were observed at ceramic sites compared with the enamel (p<0.05). In the experimental gingivitis, plaque index, GI, crevicular fluid and its IL-1alpha levels increased significantly. Conclusion: The need for optimal oral hygiene and professional preventive oral health care does not seem to be reduced with regard to approximal surfaces of aged, resin-bonded, leucite-reinforced ceramic restorations in comparison with those of a hybrid, resin composite and enamel.

  • 30.
    Konradsson, Katarina
    et al.
    Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    van Dijken, Jan
    Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
    Mutans streptococci and lactobacilli in plaque on a leucite-reinforced dental ceramic and on a calcium aluminate cement.2006In: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 10, no 3, p. 175-180Article in journal (Refereed)
    Abstract [en]

    In this in vivo study, the proportions of mutans streptococci and lactobacilli in plaque were examined (1) on proximal surfaces of bonded, leucite-reinforced ceramic crowns and (2) on class V restorations of calcium aluminate cement (CAC). The examined proportions were intraindividually compared with those of resin composite and enamel. Mutans streptococci and lactobacilli in samples from plaque that was accumulated for 10 days on the following surfaces were determined by cultivation on blood agar plates and species-selective plates: (1) proximal leucite-reinforced ceramic crown, class II composite and enamel (n=11); and (2) class V restoration of CAC and composite, and enamel (n=17). Mutans streptococci and lactobacilli in the samples were distributed in three groups: 0, >0-1, and >1% of total bacteria. The surfaces with detected mutans streptococci were similarly distributed between the materials and enamel. The highest proportion of mutans streptococci and lactobacilli were observed on ceramic followed by composite and enamel. A higher proportion of lactobacilli, but not of mutans streptococci, was detected on enamel compared to CAC and composite. However, no significant differences were found between the surfaces. Conclusively, the materials investigated did not show different relative proportions of mutans streptococci and lactobacilli in plaque, compared to enamel.

  • 31.
    Lopes, Jose Pedro
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Stylianou, Marios
    Backman, Emelie
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Holmberg, Sandra
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Jass, Jana
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Urban, Constantin F.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Evasion of Immune Surveillance in Low Oxygen Environments Enhances Candida albicans Virulence.2018In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 9, no 6, article id e02120-18Article in journal (Refereed)
    Abstract [en]

    Microbial colonizers of humans have evolved to adapt to environmental cues and to sense nutrient availability. Oxygen is a constantly changing environmental parameter in different host tissues and in different types of infection. We describe how Candida albicans, an opportunistic fungal pathogen, can modulate the host response under hypoxia and anoxia. We found that high infiltration of polymorphonuclear leukocytes (PMNs) to the site of infection contributes to a low oxygen milieu in a murine subdermal abscess. A persistent hypoxic environment did not affect viability or metabolism of PMNs. Under oxygen deprivation, however, infection with C. albicans disturbed specific PMN responses. PMNs were not able to efficiently phagocytose, produce ROS, or release extracellular DNA traps. Failure to launch an adequate response was caused by C. albicans cell wall masking of β-glucan upon exposure to low oxygen levels which hindered PAMP sensing by Dectin-1 on the surfaces of PMNs. This in turn contributed to immune evasion and enhanced fungal survival. The cell wall masking effect is prolonged by the accumulation of lactate produced by PMNs under low oxygen conditions. Finally, adaptation to oxygen deprivation increased virulence of C. albicans which we demonstrated using a Caenorhabditis elegans infection model.IMPORTANCE Successful human colonizers have evolved mechanisms to bypass immune surveillance. Infiltration of PMNs to the site of infection led to the generation of a low oxygen niche. Exposure to low oxygen levels induced fungal cell wall masking, which in turn hindered pathogen sensing and antifungal responses by PMNs. The cell wall masking effect was prolonged by increasing lactate amounts produced by neutrophil metabolism under oxygen deprivation. In an invertebrate infection model, C. albicans was able to kill infected C. elegans nematodes within 2 days under low oxygen conditions, whereas the majority of uninfected controls and infected worms under normoxic conditions survived. These results suggest that C. albicans benefited from low oxygen niches to increase virulence. The interplay of C. albicans with innate immune cells under these conditions contributed to the overall outcome of infection. Adaption to low oxygen levels was in addition beneficial for C. albicans by reducing susceptibility to selected antifungal drugs. Hence, immunomodulation of host cells under low oxygen conditions could provide a valuable approach to improve current antifungal therapies.

  • 32.
    Oscarsson, Jan
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Lindholm, Mark
    Umeå University, Faculty of Medicine, Department of Odontology.
    Höglund-Åberg, Carola
    Umeå University, Faculty of Medicine, Department of Odontology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Tools of Aggregatibacter actinomycetemcomitans to Evade the Host Response2019In: Journal of Clinical Medicine, ISSN 2077-0383, Vol. 8, no 7, article id 1079Article in journal (Refereed)
    Abstract [en]

    Periodontitis is an infection-induced inflammatory disease that affects the tooth supporting tissues, i.e., bone and connective tissues. The initiation and progression of this disease depend on dysbiotic ecological changes in the oral microbiome, thereby affecting the severity of disease through multiple immune-inflammatory responses. Aggregatibacter actinomycetemcomitans is a facultative anaerobic Gram-negative bacterium associated with such cellular and molecular mechanisms associated with the pathogenesis of periodontitis. In the present review, we outline virulence mechanisms that help the bacterium to escape the host response. These properties include invasiveness, secretion of exotoxins, serum resistance, and release of outer membrane vesicles. Virulence properties of A. actinomycetemcomitans that can contribute to treatment resistance in the infected individuals and upon translocation to the circulation, also induce pathogenic mechanisms associated with several systemic diseases.

  • 33.
    Persson, Anitha
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Hygiene.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    van Dijken, Jan
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Hygiene.
    Levels of mutans streptococci and lactobacilli in plaque on aged restorations of an ion-releasing and a universal hybrid composite resin2005In: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 63, no 1, p. 21-25Article in journal (Refereed)
    Abstract [en]

    The purpose of this in vivo study was to evaluate the cariogenic microflora of plaque on aged restorations of a hydroxyl, fluoride, and calcium ion-releasing composite resin (IRCR) (Ariston pHc), and to compare it intra-individually with a universal hybrid composite resin and enamel. Each of 19 subjects received one proximal restoration of the IRCR, one proximal universal hybrid composite resin restoration (CR) and each subject had one non-filled proximal enamel control surface to make intra-individual comparisons possible. To avoid peak ion releases from the materials, aged restorations were studied. Plaque was collected from 57 surfaces using sterile applicator tips. Samples were cultured to determine the numbers of mutans streptococci, lactobacilli, and total microorganisms. The relative numbers for mutans streptococci (% of total bacteria) were: IRCR 0.59%, CR 0.40%, enamel 0.22%. Two outliers were found in the IRCR group. Excluding these outliers resulted in a relative number of 0.33%. Lactobacilli were detected in the plaque from only 9 surfaces and at very low relative proportions for all three surfaces: 0.01%. The enamel surfaces showed the lowest relative numbers of mutans streptococci and lactobacilli, but the differences were not significant. It can be concluded that the ion release of the IRCR did not influence the growth of cariogenic microorganisms in dental plaque.

  • 34.
    Persson, Anitha
    et al.
    Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
    Lingström, Peter
    Bergdahl, Maud
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Odontology.
    van Dijken, Jan
    Umeå University, Faculty of Medicine, Odontology, Dental Hygiene.
    Buffering effect of a prophylactic gel on dental plaque in institutionalised elderly2007In: Gerodontology, ISSN 0734-0664, E-ISSN 1741-2358, Vol. 24, no 2, p. 98-104Article in journal (Refereed)
    Abstract [en]

    Objectives: The effect of multiple daily applications of a prophylactic gel, with buffering substances, on plaque acidogenicity in elderly institutionalised individuals was evaluated. Background: Many elderly suffer from reduced salivary flow, poor oral hygiene and increased levels of cariogenic bacteria and are considered to be at an increased risk for coronal and root caries. Reinforcing the buffering capacity of dental plaque by the addition of substances such as bicarbonate and phosphates may decrease their caries activity. Materials and methods: Fourteen elderly, with subjective dry mouth, were treated for 16-day-periods at random with: (i) Profylin fluoride gel with buffering components; (ii) Profylin fluoride gel without buffering components and (iii) rinsing with water. Applications were made four times a day and each period was followed by a 2-week wash-out period. The plaque pH was registered after a carbohydrate challenge and the following were recorded before and after each test period: stimulated salivary secretion rate, buffer capacity, number Colony Farming Units (CFU) mutans streptococci, lactobacilli and a sample of Candida albicans on oral mucosa. Results: Eleven participants (mean age 76.6 years) fulfilled the study. Changes in plaque pH measurements, when calculated as area under the curve (AUC(6.2) and AUC(5.7)) values (pH x min), before and after each of the three treatments, showed no significant differences. A tendency to a higher plaque acidogenicity and amount of cariogenic microorganisms was found after the gel treatments. C. albicans was found in low levels. Conclusion: Frequent applications of the gel did not result in an improved neutralising effect in the elderly. This may be caused by a combination of several factors, such as the level of oral dryness of the individuals and low solubility, release and retention of the gel substances in plaque. Instead, an increased plaque acidogenicity was noted.

  • 35.
    Persson, Karina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Esberg, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Cariology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Cariology.
    Strömberg, Nicklas
    Umeå University, Faculty of Medicine, Department of Odontology, Cariology.
    The pilin protein FimP from Actinomyces oris: crystal structure and sequence analyses2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 10, p. e48364-Article in journal (Refereed)
    Abstract [en]

    The Actinomyces oris type-1 pili are important for the initial formation of dental plaque by binding to salivary proteins that adhere to the tooth surface. Here we present the X-ray structure of FimP, the protein that is polymerized into the type-1 pilus stalk, assisted by a pili-specific sortase. FimP consists of three tandem IgG-like domains. The middle and C-terminal domains contain one autocatalyzed intramolecular isopeptide bond each, a feature used by Gram-positive bacteria for stabilization of surface proteins. While the N-terminal domain harbours all the residues necessary for forming an isopeptide bond, no such bond is observed in the crystal structure of this unpolymerized form of FimP. The monomer is further stabilized by one disulfide bond each in the N- and C-terminal domains as well as by a metal-coordinated loop protruding from the C-terminal domain. A lysine, predicted to be crucial for FimP polymerization by covalent attachment to a threonine from another subunit, is located at the rim of a groove lined with conserved residues. The groove may function as a docking site for the sortase-FimP complex. We also present sequence analyses performed on the genes encoding FimP as well as the related FimA, obtained from clinical isolates.

  • 36. Sofrata, Abier H
    et al.
    Claesson, Rolf L K
    Umeå University, Faculty of Medicine, Odontology. Umeå University, Faculty of Medicine, Odontology, Oral Microbiology.
    Lingström, Peter K
    Gustafsson, Anders K
    Strong antibacterial effect of miswak against oral microorganisms associated with periodontitis and caries.2008In: Journal of Periodontology, ISSN 0022-3492, E-ISSN 1943-3670, Vol. 79, no 8, p. 1474-9Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The chewing stick (miswak) is used for oral hygiene in many parts of the world. In addition to the mechanical removal of plaque, an antibacterial effect has been postulated; however, tests of miswak extract from Salvadora persica (Arak) disclosed only low to moderate antibacterial effects. This may be attributable to the extraction process. Our aim was to test in vitro the antibacterial effect of miswak pieces, without extraction, on bacteria implicated in the etiology of periodontitis and caries. METHODS: Miswak pieces were standardized by size and weight (0.07 and 0.14 g) and tested against Streptococcus mutans, Lactobacillus acidophilus, Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Porphyromonas gingivalis, and, as a reference, Haemophilus influenzae. The miswak pieces were tested in two ways: embedded in the agar plate or suspended above the agar plate. RESULTS: The inhibitory effect was most pronounced on P. gingivalis, A. actinomycetemcomitans, and H. influenzae, less on S. mutans, and least on L. acidophilus. Suspended miswak had comparable or stronger effects than miswak embedded in agar. The 0.14-g suspended miswak exhibited significantly greater inhibition on A. actinomycetemcomitans and H. influenzae than the 0.14-g miswak embedded in agar (P<0.01 and P<0.001, respectively). CONCLUSIONS: Miswak embedded in agar or suspended above the agar plate had strong antibacterial effects against all bacteria tested. The antibacterial effect of suspended miswak pieces suggests the presence of volatile active antibacterial compounds.

  • 37.
    Vestman, Nelly Romani
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Timby, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
    Holgerson, Pernilla Lif
    Umeå University, Faculty of Medicine, Department of Odontology.
    Kressirer, Christine A
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Domellöf, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
    Öhman, Carina
    Umeå University, Faculty of Medicine, Department of Odontology, School of Dentistry.
    Tanner, Anne CR
    Hernell, Olle
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
    Johansson, Ingegerd
    Umeå University, Faculty of Medicine, Department of Odontology, School of Dentistry.
    Characterization and in vitro properties of oral lactobacilli in breastfed infants2013In: BMC Microbiology, ISSN 1471-2180, E-ISSN 1471-2180, Vol. 13, p. 193-Article in journal (Refereed)
    Abstract [en]

    Background: Lactobacillus species can contribute positively to general and oral health and are frequently acquired by breastfeeding in infancy. The present study aimed to identify oral lactobacilli in breast and formula-fed 4 month-old infants and to evaluate potential probiotic properties of the dominant Lactobacillus species detected. Saliva and oral swab samples were collected from 133 infants who were enrolled in a longitudinal study (n=240) examining the effect of a new infant formula on child growth and development. Saliva was cultured and Lactobacillus isolates were identified from 16S rRNA gene sequences. Five L. gasseri isolates that differed in 16S rRNA sequence were tested for their ability to inhibit growth of selected oral bacteria and for adhesion to oral tissues. Oral swab samples were analyzed by qPCR for Lactobacillus gasseri.

    Results: 43 (32.3%) infants were breastfed and 90 (67.7%) were formula-fed with either a standard formula (43 out of 90) or formula supplemented with a milk fat globule membrane (MFGM) fraction (47 out of 90). Lactobacilli were cultured from saliva of 34.1% breastfed infants, but only in 4.7% of the standard and 9.3% of the MFGM supplemented formula-fed infants. L. gasseri was the most prevalent (88% of Lactobacillus positive infants) of six Lactobacillus species detected. L. gasseri isolates inhibited Streptococcus mutans binding to saliva-coated hydroxyapatite, and inhibited growth of S. mutans, Streptococcus sobrinus, Actinomyces naeslundii, Actinomyces oris, Candida albicans and Fusobacterium nucleatum in a concentration dependent fashion. L. gasseri isolates bound to parotid and submandibular saliva, salivary gp340 and MUC7, and purified MFGM, and adhered to epithelial cells. L. gasseri was detected by qPCR in 29.7% of the oral swabs. Breastfed infants had significantly higher mean DNA levels of L. gasseri (2.14 pg/uL) than infants fed the standard (0.363 pg/uL) or MFGM (0.697 pg/uL) formula.

    Conclusions: Lactobacilli colonized the oral cavity of breastfed infants significantly more frequently than formulafed infants. The dominant Lactobacillus was L. gasseri, which was detected at higher levels in breastfed than formula-fed infants and displayed probiotic traits in vitro.

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