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Negi, Neema
Publications (4 of 4) Show all publications
Negi, N. & Das, B. K. (2018). CNS: Not an immunoprivilaged site anymore but a virtual secondary lymphoid organ. International Reviews of Immunology, 37(1), 57-68
Open this publication in new window or tab >>CNS: Not an immunoprivilaged site anymore but a virtual secondary lymphoid organ
2018 (English)In: International Reviews of Immunology, ISSN 0883-0185, E-ISSN 1563-5244, Vol. 37, no 1, p. 57-68Article, review/survey (Refereed) Published
Abstract [en]

The cardinal dogma of central nervous system (CNS) immunology believed brain is an immune privileged site, but scientific evidences gathered so far have overturned this notion proving that CNS is no longer an immune privileged site, but rather an actively regulated site of immune surveillance. Landmark discovery of lymphatic system surrounding the duramater of the brain, made possible by high resolution live imaging technology has given new dimension to neuro-immunology. Here, we discuss the immune privilege status of CNS in light of the previous and current findings, taking into account the differences between a healthy state and changes that occur during an inflammatory response. Cerebrospinal fluid (CSF) along with interstitial fluid (ISF) drain activated T cells, natural killer cells, macrophages and dendritic cells from brain to regional lymph nodes present in the head and neck region. To keep an eye on inflammation, this system hosts an army of regulatory T cells (CD25+ FoxP3+) that regulate T cell hyper activation, proliferation and cytokine production. This review is an attempt to fill the gaps in our understanding of neuroimmune interactions, role of innate and adaptive immune system in maintaining homeostasis, interplay of different immune cells, immune tolerance, knowledge of communication pathways between the CNS and the peripheral immune system and lastly how interruption of immune surveillance leads to neurodegenerative diseases. We envisage that discoveries should be made not only to decipher underlying cellular and molecular mechanisms of immune trafficking, but should aid in identifying targeted cell populations for therapeutic intervention in neurodegenerative and autoimmune disorders.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
Keywords
Astrocytes, blood-brain barrier, CNS, microglia, lymphatics
National Category
Immunology
Identifiers
urn:nbn:se:umu:diva-144964 (URN)10.1080/08830185.2017.1357719 (DOI)000424246300005 ()28961037 (PubMedID)
Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2018-06-09Bibliographically approved
Negi, N. & Ahmad, A. (2018). Current updates on fungal endocarditis. Fungal Biology Reviews, 32(1), 1-9
Open this publication in new window or tab >>Current updates on fungal endocarditis
2018 (English)In: Fungal Biology Reviews, ISSN 1749-4613, E-ISSN 1878-0253, Vol. 32, no 1, p. 1-9Article, review/survey (Refereed) Published
Abstract [en]

Fungal endocarditis (FE) is a rare disease but in recent years its incidence as well as mortality is increasing particularly in developing nations. Candida and Aspergillus species occupy the prominent position as etiological agents of this invasive disease. Intravenous devices such as pacemakers, central line related thrombosis and prolonged use of antibiotics are major risk factors for FE. The epidemiology of endocarditis cases is also evolving over time with exceptionally rare species causing more invasive disease. Research over the last decade has also delineated the underlying pathogenic mechanism of FE. Improved understanding of these mechanisms will help to combat the increasing problem of antimicrobial drug resistance. The diagnosis of FE is dependent on the sensitivity and specificity of the method as fungi generally do not grow well in blood cultures. More advanced techniques including molecular and immunological assays now play a central role in accurate identification of causative fungal pathogens especially in culture negative scenario. In developing nations such as India, blood culture reports are generally negative due to prior antibiotic therapy. Echocardiography has emerged as the potential imaging technique for identifying invasive endocarditis including small masses of vegetation or abscess. Successful treatment often requires both the surgical interventions and prolonged antifungal therapy. In the present review, we briefly highlight the mechanisms of pathogenesis of this rare emerging disease along with the risk factors involved, the diagnostic criteria and the treatment strategy.

Keywords
Diagnosis, Fungal endocarditis, Pathogenesis, Treatment
National Category
Infectious Medicine
Identifiers
urn:nbn:se:umu:diva-145613 (URN)10.1016/j.fbr.2017.11.001 (DOI)000425575100001 ()
Available from: 2018-03-21 Created: 2018-03-21 Last updated: 2018-06-09Bibliographically approved
Grundström, C., Kumar, A., Priya, A., Negi, N. & Grundström, T. (2018). ETS1 and PAX5 transcription factors recruit AID to Igh DNA. European Journal of Immunology, 48(10), 1687-1697
Open this publication in new window or tab >>ETS1 and PAX5 transcription factors recruit AID to Igh DNA
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2018 (English)In: European Journal of Immunology, ISSN 0014-2980, E-ISSN 1521-4141, Vol. 48, no 10, p. 1687-1697Article in journal (Refereed) Published
Abstract [en]

B lymphocytes optimize antibody responses by class switch recombination (CSR), which changes the expressed constant region exon of the immunoglobulin heavy chain (IgH), and by somatic hypermutation (SH) that introduces point mutations in the variable regions of the antibody genes. Activation-induced cytidine deaminase (AID) is the key mutagenic enzyme that initiates both these antibody diversification processes by deaminating cytosine to uracil. Here we asked the question if transcription factors can mediate the specific targeting of the antibody diversification by recruiting AID. We have recently reported that AID is together with the transcription factors E2A, PAX5 and IRF4 in a complex on key sequences of the Igh locus. Here we report that also ETS1 is together with AID in this complex on key sequences of the Igh locus in splenic B cells of mice. Furthermore, we show that both ETS1 and PAX5 can directly recruit AID to DNA sequences from the Igh locus with the specific binding site for the transcription factor. Taken together, our findings support the notion of a targeting mechanism for the selective diversification of antibody genes with limited genome wide mutagenesis by recruitment of AID by PAX5 and ETS1 in a transcription factor complex.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
Activation-induced cytidine deaminase, Class switch recombination, Protein interactions, Somatic hypermutation, Transcription factors
National Category
Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-152886 (URN)10.1002/eji.201847625 (DOI)000446431600008 ()30089192 (PubMedID)
Funder
Swedish Cancer SocietySwedish Research Council
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2018-10-31Bibliographically approved
Kumar, A., Priya, A., Ahmed, T., Grundström, C., Negi, N. & Grundström, T. (2018). Regulation of the DNA Repair Complex during Somatic Hypermutation and Class-Switch Recombination. Journal of Immunology, 200(12), 4146-4156
Open this publication in new window or tab >>Regulation of the DNA Repair Complex during Somatic Hypermutation and Class-Switch Recombination
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2018 (English)In: Journal of Immunology, ISSN 0022-1767, E-ISSN 1550-6606, Vol. 200, no 12, p. 4146-4156Article in journal (Refereed) Published
Abstract [en]

B lymphocytes optimize Ab responses by somatic hypermutation (SH), which introduces pointmutations in the variable regions of the Ab genes and by class-switch recombination (CSR), which changes the expressed C region exon of the IgH. These Ab diversification processes are initiated by the deaminating enzyme activation-induced cytidine deaminase followed by many DNA repair enzymes, ultimately leading to deletions and a high mutation rate in the Ab genes, whereas DNA lesions made by activation-induced cytidine deaminase are repaired with low error rate on most other genes. This indicates an advanced regulation of DNA repair. In this study, we show that initiation of Ab diversification in B lymphocytes of mouse spleen leads to formation of a complex between many proteins in DNA repair. We show also thatBCR activation, which signals the end of successful SH, reduces interactions between some proteins in the complex and increases other interactions in the complex with varying kinetics. Furthermore, we show increased localization of SH-and CSR-coupled proteins on switch regions of the Igh locus upon initiation of SH/CSR and differential changes in the localization upon BCR signaling, which terminates SH. These findings provide early evidence for a DNA repair complex or complexes that may be of functional significance for carrying out essential roles in SH and/or CSR in B cells.

Place, publisher, year, edition, pages
American Association of Immunologists, 2018
National Category
Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-151570 (URN)10.4049/jimmunol.1701586 (DOI)000442386300029 ()29728513 (PubMedID)
Funder
Swedish Cancer SocietySwedish Research Council
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2018-09-10Bibliographically approved
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