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Montréal, Canada

Behr M.A.,McGill University | Behr M.A.,ll International Center | Divangahi M.,McGill University | Divangahi M.,ll International Center | Divangahi M.,Meakins Christie Laboratories
Current Opinion in Microbiology | Year: 2015

Mycobacterium tuberculosis contributed to the discovery of delayed-type hypersensitivity and cell-mediated immunity. However, the biochemical basis for the immunogenicity of the mycobacterial cell wall has until recently remained unknown. Recent findings: Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) responds to bacterial peptidolycan-derived muramyl dipeptide (MDP). Whereas most bacteria produce N-acetyl MDP, mycobacteria produce an unusual modified form of MDP, called N-glycolyl MDP. Disruption of N-glycolyl MDP synthesis in mycobacteria greatly diminishes the contribution of NOD2 to mycobacterial sensing. Additionally, N-glycolyl MDP is more potent and efficacious than N-acetyl MDP at inducing innate responses and T cell-mediated immunity. Summary: The sensitivity of NOD2 to the mycobacterial peptidoglycan may link the natural history of both innate and adaptive immunity to mycobacterial infection. © 2014 Elsevier Ltd. Source

Hepple R.T.,McGill University | Hepple R.T.,Meakins Christie Laboratories
Free Radical Biology and Medicine | Year: 2016

Both skeletal muscle and cardiac muscle are subject to marked structural and functional impairment with aging and these changes contribute to the reduced capacity for exercise as we age. Since mitochondria are involved in multiple aspects of cellular homeostasis including energetics, reactive oxygen species signaling, and regulation of intrinsic apoptotic pathways, defects in this organelle are frequently implicated in the deterioration of skeletal and cardiac muscle with aging. On this basis, the purpose of this review is to evaluate the evidence that aging causes dysfunction in mitochondria in striated muscle with a view towards drawing conclusions about the potential of these changes to contribute to the deterioration seen in striated muscle with aging. As will be shown, impairment in respiration and reactive oxygen species emission with aging are highly variable between studies and seem to be largely a consequence of physical inactivity. On the other hand, both skeletal and cardiac muscle mitochondria are more susceptible to permeability transition and this seems a likely cause of the increased recruitment of mitochondrial-mediated pathways of apoptosis seen in striated muscle. The review concludes by examining the role of degeneration of mitochondrial DNA versus impaired mitochondrial quality control mechanisms in the accumulation of mitochondria that are sensitized to permeability transition, whereby the latter mechanism is favored as the most likely cause. © 2016 Elsevier Inc. Source

Arshad S.H.,David Hide Asthma and Allergy Research Center | Arshad S.H.,University of Southampton | Dharmage S.C.,University of Melbourne | Ferreira F.,Christian Doppler Laboratory | And 7 more authors.
Clinical and Experimental Allergy | Year: 2012

As in previous years, we felt it would be of value to our readership to summarize the new information provided by the authors who have published in Clinical and Experimental Allergy in 2011 and set this in the context of recent advances in our understanding of the pathogenesis and management of allergic disease in all its many manifestations. In 2011, about 210 articles were published in Clinical and Experimental Allergy including editorials, reviews, opinion articles, guidelines, letters, book reviews and of course at the heart of the journal, papers containing original data. As before, this review is divided into sections based on the way the journal is structured, although this year we have grouped together all the papers dealing with mechanisms of allergic disease, whether they involve patients (clinical mechanisms), pure in vitro studies (basic mechanisms) or animal models (experimental models), as we felt this was a more coherent way to deal with the subject. In the field of asthma and rhinitis, the relationship between airway inflammation and airway dysfunction was of perennial interest to investigators, as were phenotypes and biomarkers. Aspirin hypersensitivity appeared in studies in several papers and there was new interest in asthma in the elderly. The mechanisms involved in allergic disease describe advances in our understanding of T cell responses, the relationship between inflammation and disease, mast cell and basophil activation, steroid resistance and novel therapies. In the section dealing with epidemiology, studies seeking to identify risk factors for allergic disease including vitamin D are prominent, as once again are studies investigating gene-environment interactions. The clinical allergy section focuses on drug allergy, food allergy and immunotherapy. The area of oral immunotherapy for food allergy is well covered and we were grateful to Stephen Durham for guest editing an outstanding special issue on immunotherapy in the centenary year of Leonard Noon's pioneering work. Lastly, in the field of allergens, the interest in component-resolved diagnosis continues to grow and there are also articles describing important novel cultivars and the effect of food processing on the allergenic properties of foods. Another terrific year, full of important and high-quality work,which the journal has been proud to bring to the allergy community. © 2012 Blackwell Publishing Ltd. Source

Roussel L.,Meakins Christie Laboratories | Houle F.,Laval University | Chan C.,Royal Victoria Hospital | Yao Y.,Meakins Christie Laboratories | And 7 more authors.
Journal of Immunology | Year: 2010

Neutrophilic inflammation plays an important role in lung tissue destruction occurring in many chronic pulmonary diseases. Neutrophils can be recruited to sites of inflammation via the action of the cytokine IL-17. In this study, we report that IL-17RA and IL-17RC mRNA expression is significantly increased in asthmatic bronchoscopic biopsies and that these receptors are not only expressed on epithelial and inflammatory cells but also on endothelial cells. IL-17 potently stimulates lung microvascular endothelial cells to produce chemoattractants (CXCL8 and derivatives of the 5-lipoxygenase pathway) that selectively drive neutrophil but not lymphocyte chemotaxis. Moreover, IL-17 promotes endothelial activation by inducing the expression of endothelial adhesion markers (E-selectin, VCAM-1, and ICAM-1) in a p38 MAPK-dependent manner. This increased expression of adhesion molecules stimulates the trans-endothelial migration of neutrophils, as well as the transmigration of HT-29 colon carcinoma cells, suggesting a further role in promoting lung metastasis. Finally, IL-17 increased neutrophil adhesion to the endothelium in vivo as determined by intravital microscopy of mice cremaster muscle. Overall, our results demonstrate that IL-17 is a potent activator of the endothelium in vivo leading to neutrophil infiltration. Therefore, preventing neutrophil recruitment by blocking the action of IL-17 on endothelial cells may prove to be highly beneficial in diseases in which neutrophilic inflammation plays a key role. Copyright © 2010 by The American Association of Immunologists, Inc. Source

Robins S.,Meakins Christie Laboratories | Roussel L.,Meakins Christie Laboratories | Schachter A.,Meakins Christie Laboratories | Risse P.-A.,Meakins Christie Laboratories | And 5 more authors.
American Journal of Respiratory Cell and Molecular Biology | Year: 2011

Severe or refractory asthma affects 5 to 15% of all patients with asthma, but is responsible for more than half of the health burden associated with the disease. Severe asthma is characterized by a dramatic increase in smooth muscle and airway inflammation. Although glucocorticoids are the mainstay of treatment in asthma, they are unable to fully control the disease in individuals with severe asthma. We found that airway smooth muscle cells (ASMCs) from individuals with severe asthma showed elevated activities of the ERK1/ERK2 and p38MAPK pathways despite treatment with oraland inhaled glucocorticoids, which increased the expression of DUSP1, a phosphatase shown to limit p38 MAPK activity. In ex vivo ASMCs, TNF-α but not IL-17A induced expression of the neutrophil chemoattractant CXCL8. Moreover, TNF-α led to up-regulation of the ERK1/ERK2 and p38 MAPKs pathways, with only the latter being sensitive to pretreatment with the glucocorticoid dexamethasone. In contrast to epithelial and endothelial cells, TNF-α - stimulated CXCL8 synthesis was dependent on ERK1/ERK2 but not on p38 MAPK.Moreover, suppressingERK1/ ERK2activationpreventedneutrophil recruitment by ASMCs, whereas suppressing p38 MAPK activity had no impact. Taken together, these results highlight the ERK1/ERK2 MAPK cascade as a novel and attractive target in severe asthma because the activation of this pathway is insensitive to the action of glucocorticoids and is involved in neutrophil recruitment, contributing the to inflammation seen in the disease. Source

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