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Background: The use of alternative and renewable fuels in the transport sector is growing rapidly due to increasing demand for sustainable energy solutions, however implying an increased risk for human exposure to emissions from these new fuels.

Methods: In this study, we examined the effects on BEAS-2B cells of particulate matter (PM) emissions, derived from the use of petroleum diesel (SD10) and rapeseed methyl ester (RME100) in a truck engine. We assessed several endpoints, including the induction of apoptotic and necrotic cell death, reactive oxygen species generation inside cells, inflammatory response, and cell cycle alterations.

Results: The characteristics of the exhaust PM varied between the two fuels, where the RME100-derived PM contained lower levels of polycyclic aromatic hydrocarbons and elemental carbon compared to SD10. Toxicological analyses revealed that PM from RME100 induced weaker oxidative stress and cell death responses than SD10. However, unlike SD10, RME100 PM caused a notable arrest in the S-G2/M phase of the cell cycle.

Conclusions: In summary, fuel type clearly influenced the characteristics of PM emissions from a heavy-duty diesel engine, which in turn affected the particles’ biological activity. Overall, RME100 exhaust PM exhibited lower toxicity compared to petroleum diesel PM in the BEAS-2B cell model.

Background: Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of the skin and internal organs, mostly affecting young and middle-aged women. Significant questions remain as to its pathogenesis, especially the triggers for the associated interstitial lung disease (SSc-ILD). We examined the extent to which SSc and SSc-ILD were related to oxidative stress and altered metal homeostasis at the air-lung interface.

Methods: In this case-control study, we recruited 20 SSc patients, of which 11 had SSc-ILD. Eighteen healthy individuals were recruited as age-matched healthy controls, for a total of 38 study participants. Low molecular weight antioxidants (ascorbate, urate and glutathione), metal transport and chelation proteins (transferrin and ferritin) and metals (Fe and Cu) concentrations, including a measure of the catalytically active metal pool, were determined in respiratory tract lining fluid (RTLF) collected by bronchoalveolar lavage from the SSc group and compared with healthy controls.

Results: In the SSc group, 14 individuals were of female sex (70%) and the median age was 57 years (range 35–75). We observed evidence of oxidative stress in the RTLFs of SSc patients, characterised by increased concentrations of glutathione disulphide (GSSG, P<0.01), dehydroascorbate (DHA, P<0.05) and urate (P<0.01). This was associated with elevated RTLF Fe (P=0.07) and Cu (P<0.001), and evidence of a catalytic metal pool, demonstrated by an enhanced rate of ascorbate oxidation in the recovered lavage fluid (p<0.01). Cu concentrations were significantly associated with the ascorbate depletion rate (r=0.76, P<0.001), and GSSG (r=0.38, P<0.05) and protein carbonyl (r=0.44, P<0.01) concentrations. Whilst these markers were all increased in SSc patients, we found no evidence for an association with SSc-ILD.

Conclusions: These data confirm the presence of oxidative stress in the airways of SSc patients and, for the first time, suggest that an underlying defect in metal homeostasis at the air-lung interface may play a role in disease progression.

Background: Exposure to standard petrodiesel exhaust is linked to adverse health effects. Moreover, there is a mounting request to replace fossil-based fuels with renewable and sustainable alternatives and, therefore, rapeseed methyl ester (RME) and other biofuels have been introduced. However, recent toxicological research has indicated that biodiesel exhaust may also induce adverse health-related events.

Aim: To determine whether exposure to 100% RME biodiesel (BD100) exhaust would cause an acute airway neutrophilic recruitment in humans.

Methods: Fourteen healthy subjects underwent exposure to diluted BD100 exhaust and filtered air for 1-h, in a blinded, random fashion. Bronchoscopy with endobronchial mucosal biopsies, bronchial wash (BW) and bronchoalveolar lavage (BAL) was performed six hours after exposure. Differential cell counts and inflammatory markers were determined in the supernatant and biopsies were stained immunohistochemically.

Results: Compared with filtered air, BD100 exhaust exposure increased bronchial mucosal endothelial P-selectin adhesion molecule expression, as well as neutrophil, mast cell and CD68 + macrophage numbers. An increased influx of neutrophils and machrophages was also seen in BW.

Conclusion: Exposure to biodiesel exhaust was associated with an acute airway inflammation that appeared similar to preceding petrodiesel exposure studies. The present findings, together with the recently reported adverse cardiovascular effects after similar biodiesel exposure, indicate that biodiesel is not free of toxicity and may affect human health.

Background: A substantial proportion of individuals with COPD have never smoked, and it is implied to be more common than previously anticipated but poorly studied.

Aim: To describe the process of recruitment of never-smokers with COPD from a population-based cohort (n = 30 154).

Methods: We recruited never-smokers with COPD, aged 50–75 years, from six University Hospitals, based on: 1) post broncho-dilator forced expiratory volume in 1 second/forced vital capacity (FEV₁/FVC) < 0.70 and 2) FEV₁ 50–100% of predicted value and 3) being never-smokers (self-reported). In total 862 SCAPIS participants were identified, of which 652 were reachable and agreed to a first screening by telephone. Altogether 128 (20%) were excluded due to previous smoking or declined participation. We also applied a lower limit of normal (LLN) of FEV₁/FVC (z-score<-1.64) according to the Global Lung Initiative to ensure a stricter definition of airflow obstruction.

Results: Data on respiratory symptoms, health status, and medical history were collected from 492 individuals, since 32 were excluded at a second data review (declined or previous smoking), prior to the first visit. Due to not matching the required lung function criteria at a second spirometry, an additional 334 (68%) were excluded. These exclusions were by reason of: FEV₁/FVC ≥0.7 (49%), FEV₁ > 100% of predicted (26%) or z-score ≥ −1,64 (24%). Finally, 154 never-smokers with COPD were included: 56 (36%) women, (mean) age 60 years, FEV₁ 84% of predicted, FEV₁/FVC: 0.6, z-score: −2.2, Oxygen saturation: 97% and BMI: 26.8 kg/m².

Conclusions: The challenges of a recruitment process of never-smokers with COPD were shown, including the importance of correct spirometry testing and strict inclusion criteria. Our findings highlight the importance of repeated spirometry assessments for improved accuracy in diagnosing COPD.

Background: Diesel exhaust (DE) induces neutrophilia and lymphocytosis in experimentally exposed humans. These responses occur in parallel to nuclear migration of NF-κB and c-Jun, activation of mitogen activated protein kinases and increased production of inflammatory mediators. There remains uncertainty regarding the impact of DE on endogenous antioxidant and xenobiotic defences, mediated by nuclear factor erythroid 2-related factor 2 (Nrf2) and the aryl hydrocarbon receptor (AhR) respectively, and the extent to which cellular antioxidant adaptations protect against the adverse effects of DE.

Methods: Using immunohistochemistry we investigated the nuclear localization of Nrf2 and AhR in the epithelium of endobronchial mucosal biopsies from healthy subjects six-hours post exposure to DE (PM₁₀, 300 µg/m³) versus post-filtered air in a randomized double blind study, as a marker of activation. Cytoplasmic expression of cytochrome P450s, family 1, subfamily A, polypeptide 1 (CYP1A1) and subfamily B, Polypeptide 1 (CYP1B1) were examined to confirm AhR activation; with the expression of aldo–keto reductases (AKR1A1, AKR1C1 and AKR1C3), epoxide hydrolase and NAD(P)H dehydrogenase quinone 1 (NQO1) also quantified. Inflammatory and oxidative stress markers were examined to contextualize the responses observed.

Results: DE exposure caused an influx of neutrophils to the bronchial airway surface (p = 0.013), as well as increased bronchial submucosal neutrophil (p < 0.001), lymphocyte (p = 0.007) and mast cell (p = 0.002) numbers. In addition, DE exposure enhanced the nuclear translocation of the AhR and increased the CYP1A1 expression in the bronchial epithelium (p = 0.001 and p = 0.028, respectively). Nuclear translocation of AhR was also increased in the submucosal leukocytes (p < 0.001). Epithelial nuclear AhR expression was negatively associated with bronchial submucosal CD3 numbers post DE (r = −0.706, p = 0.002). In contrast, DE did not increase nuclear translocation of Nrf2 and was associated with decreased NQO1 in bronchial epithelial cells (p = 0.02), without affecting CYP1B1, aldo–keto reductases, or epoxide hydrolase protein expression.

Conclusion: These in vivo human data confirm earlier cell and animal-based observations of the induction of the AhR and CYP1A1 by diesel exhaust. The induction of phase I xenobiotic response occurred in the absence of the induction of antioxidant or phase II xenobiotic defences at the investigated time point 6 h post-exposures. This suggests DE-associated compounds, such as polycyclic aromatic hydrocarbons (PAHs), may induce acute inflammation and alter detoxification enzymes without concomitant protective cellular adaptations in human airways.

Background: Exposure to wood smoke has been shown to contribute to adverse respiratory health effects including airway infections, but the underlying mechanisms are unclear. A preceding study failed to confirm any acute inflammation or cell influx in bronchial wash (BW) or bronchoalveolar lavage (BAL) 24 h after wood smoke exposure but showed unexpected reductions in leukocyte numbers. The present study was performed to investigate responses at an earlier phase, regarding potential development of acute inflammation, as well as indications of cytotoxicity.

Methods: In a double-blind, randomised crossover study, 14 healthy participants were exposed for 2 h to filtered air and diluted wood smoke from incomplete wood log combustion in a common wood stove with a mean particulate matter concentration of 409 µg/m3. Bronchoscopy with BW and BAL was performed 6 h after exposure. Differential cell counts, assessment of DNA-damage and ex vivo analysis of phagocytic function of phagocytosing BAL cells were performed. Wood smoke particles were also collected for in vitro toxicological analyses using bronchial epithelial cells (BEAS-2B) and alveolar type II-like cells (A549).

Results: Exposure to wood smoke increased BAL lactate dehydrogenase (LDH) (p = 0.04) and reduced the ex vivo alveolar macrophage phagocytic capacity (p = 0.03) and viability (p = 0.02) vs. filtered air. BAL eosinophil numbers were increased after wood smoke (p = 0.02), while other cell types were unaffected in BW and BAL. In vitro exposure to wood smoke particles confirmed increased DNA-damage, decreased metabolic activity and cell cycle disturbances.

Conclusions: Exposure to wood smoke from incomplete combustion did not induce any acute airway inflammatory cell influx at 6 h, apart from eosinophils. However, there were indications of a cytotoxic reaction with increased LDH, reduced cell viability and impaired alveolar macrophage phagocytic capacity. These findings are in accordance with earlier bronchoscopy findings at 24 h and may provide evidence for the increased susceptibility to infections by biomass smoke exposure, reported in population-based studies.