Séverine Audusseau

Increased Expression of IL-33 in Severe Asthma: Evidence of Expression by Airway Smooth Muscle Cells

IL-33, a new member of the IL-1 cytokine family, promotes Th2 inflammation, but evidence on the implications of this cytokine in asthma is lacking. IL-33 would be mainly expressed by structural cells, but whether proinflammatory cytokines modulate its expression in airway smooth muscle cells (ASMC) is unknown. Endobronchial biopsies were obtained from adults with mild (n = 8), moderate (n = 8), severe (n = 9), asthma and from control subjects (n = 5). Immunocytochemistry, laser-capture microdissection, reverse transcriptase, and real-time quantitative PCR were used for determining IL-33 expression in the lung tissues. ASMC isolated from resected lung specimens were cultured with proinflammatory cytokines and with dexamethasone. IL-33 expression by ASMC was determined by PCR, ELISA, and Western blotting. Higher levels of IL-33 transcripts are detected in biopsies from asthmatic compared with control subjects, and especially in subjects with severe asthma. ASMC show IL-33 expression at both protein and mRNA levels. IL-33 and TNF-α transcript levels correlate in the lung tissues, and TNF-α up-regulates IL-33 expression by cultured ASMC in a time- and dose-dependent manner. IFN-γ also increases IL-33 expression and shows synergistic effect with TNF-α. Dexamethasone fails to abolish TNF-α-induced IL-33 up-regulation. IL-33 expression increases in bronchial biopsies from subjects with asthma compared with controls, as well as subjects with asthma severity. ASMC are a source of the IL-33 cytokine. Our data propose IL-33 as a novel inflammatory marker of severe and refractory asthma.

Immunological responses in C3H/HeJ mice following nose-only inhalation exposure to different sizes of beryllium metal particles

Beryllium is used in a wide variety of industries. Chronic beryllium disease is the most common occupational disease among workers following exposure to Be. The objective of this study was to determine the immunologic effects of two different particle sizes of Be metal, <2.5 µm (fine Be or Be‐F) and <10 µm (inhalable Be or Be‐I) on C3H/HeJ mice following 3 weeks of nose‐only inhalation exposure at a target concentration of 250 µg m−3. Mice were sacrificed either on day 28 or day 42 (Be‐F group only) after exposure. The mass median aerodynamic diameter obtained in the inhalation chamber was 1.5 ± 0.1 µm for Be‐F and 4.1 ± 0.6 µm for Be‐I. Results showed peri‐bronchial inflammation with early granulomatous changes in exposed mice. The extent of the inflammation appeared more severe for mice sacrificed at day 42. Splenocyte proliferation was higher for mice exposed to fine particles compared with Be‐I and control animals. Flow‐cytometric analysis indicated a significantly greater expression of CD4+, CD8+ and intracellular IFN‐γ expression for both Be particle sizes, particularly for fine particles. Cytokine assays of bronchoalveolar lavage revealed significantly greater levels of IL‐12, TNF‐α and IFN‐γ for mice exposed to fine particles. Our findings suggest that exposure to fine particles may induce more pronounced immunological effects than inhalable particles. Copyright

Urinary levels, tissue concentrations and lung inflammation after nose-only exposure to three different chemical forms of beryllium.

This study aimed to determine the toxicity and toxicokinetic of three Be chemical species A total of 120 mice (four groups of 30) were nose‐only exposed. The first group was used as a control while the three others were exposed to 250 μg m−3 of fine particles of three different Be species (Be metal, Be–F; Be oxide, BeO–F; Be aluminium, BeAl–F). Exposure lasted over three consecutive weeks, five days per week and 6 h per day. Blood and several tissues were collected one week after exposure. Urines were collected before the beginning of exposure, at the end of every week of exposure and one week after exposure. Results showed that urine concentrations were different from one Be species to another and that excretion continued after the end of exposure. Except for BeO–F, where Be urine concentrations were stable during the three weeks of exposure, concentrations of Be–F and BeAl–F reached a peak after the first week. According to particle size, BeO–F obtained the highest theoretical pulmonary deposition rate, which partially led to the highest Be lung concentration. This group also presented the lowest urine concentration but that did not lead to more severe lung inflammation. Moreover, even if BeAl–F obtained the lowest percentage theoretical pulmonary deposition, it showed the highest Be urinary concentration, the lowest Be lung concentration and the lowest lung toxicity. In this specific case, a high Be concentration in urine did not reflect a high exposure or a severe toxic effect. Copyright

Beryllium contamination and exposure monitoring in an inhalation laboratory setting

Beryllium (Be) is used in several forms: pure metal, beryllium oxide, and as an alloy with copper, aluminum, or nickel. Beryllium oxide, beryllium metal, and beryllium alloys are the main forms present in the workplace, with inhalation being the primary route of exposure. Cases of workers with sensitization or chronic beryllium disease challenge the scientific community for a better understanding of Be toxicity. Therefore, a toxicological inhalation study using a murine model was performed in our laboratory in order to identify the toxic effects related to different particle sizes and chemical forms of Be. This article attempts to provide information regarding the relative effectiveness of the environmental monitoring and exposure protection program that was enacted to protect staff (students and researchers) in this controlled animal beryllium inhalation exposure experiment. This includes specific attention to particle migration control through intensive housekeeping and systematic airborne and surface monitoring. Results show that the protective measures applied during this research have been effective. The highest airborne Be concentration in the laboratory was less than one-tenth of the Quebec OEL (occupational exposure limit) of 0.15 μg/m3. Considering the protection factor of 103 of the powered air-purifying respirator used in this research, the average exposure level would be 0.03 × 10— 4 μg/m3, which is extremely low. Moreover, with the exception of one value, all average Be concentrations on surfaces were below the Quebec Standard guideline level of 3 μg/100 cm2 for Be contamination. Finally, all beryllium lymphocyte proliferation tests for the staff were not higher than controls.

Increased autophagy-related 5 gene expression is associated with collagen expression in the airways of refractory asthmatics

Background Fibrosis, particularly excessive collagen deposition, presents a challenge for treating asthmatic individuals. At present, no drugs can remove or reduce excessive collagen in asthmatic airways. Hence, the identification of pathways involved in collagen deposition would help to generate therapeutic targets to interfere with the airway remodeling process. Autophagy, a cellular degradation process, has been shown to be dysregulated in various fibrotic diseases, and genetic association studies in independent human populations have identified autophagy-related 5 (ATG5) to be associated with asthma pathogenesis. Hence, the dysregulation of autophagy may contribute to fibrosis in asthmatic airways. Objective This study aimed to determine if (1) collagen deposition in asthmatic airways is associated with ATG5 expression and (2) ATG5 protein expression is associated with asthma per se and severity. Methods Gene expression of transforming growth factor beta 1, various asthma-related collagen types [collagen, type I, alpha 1; collagen, type II, alpha 1; collagen, type III, alpha 1; collagen, type V, alpha 1 (COL5A1) and collagen, type V, alpha 2], and ATG5 were measured using mRNA isolated from bronchial biopsies of refractory asthmatic subjects and assessed for pairwise associations. Protein expression of ATG5 in the airways was measured and associations were assessed for asthma per se, severity, and lung function. Main results In refractory asthmatic individuals, gene expression of ATG5 was positively associated with COL5A1 in the airways. No association was detected between ATG5 protein expression and asthma per se, severity, and lung function. Conclusion and clinical relevance Positive correlation between the gene expression patterns of ATG5 and COL5A1 suggests that dysregulated autophagy may contribute to subepithelial fibrosis in the airways of refractory asthmatic individuals. This finding highlights the therapeutic potential of ATG5 in ameliorating airway remodeling in the difficult-to-treat refractory asthmatic individuals.

Interleukin-33 in asthma: insights into pro-inflammatory roles of airway structural cells

Background Interleukin-33 (IL-33) is a novel cytokine that triggers inflammatory immune responses, but evidence of its role in human asthma, a common allergic airway disease, is lacking. There is also a paucity of information regarding which cells express IL-33, and what conditions promote its expression. We sought to investigate whether IL-33 is expressed in the lung tissue from patients with asthma.