Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

by Ho Cheong-Yip. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 198-222). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Asthma is a respiratory disease that affects 2.5-3 million Canadians. This condition is characterized by a Th2-driven immune response that implicates the infiltration of eosinophils and remodelling of the airways. In the last decade, airway smooth muscle cells (ASMC) have became the subject of intense research in the field of inflammatory lung diseases including asthma. It is known that ASMC respond to a wide variety of inflammatory mediators such as cytokines and chemokines. Function of ASMC in the context of asthma has extended beyond its traditional role of a structural cell. Indeed, it is believed that they can participate in the initiation and the perpetuation of the inflammatory response that takes place in the airway of asthmatic subjects. The general aim of this work was to investigate the role of ASMC in the pathogenesis of asthma. More specifically, we studied the expression of two C-C chemokine receptors, CCR3 and CCR1 in the context of asthma. / For the first time, this work describes the expression of chemokine receptors by ASMC. We have shown that eotaxin, an important chemokine in asthma, induces migration of ASMC through the activation of CCR3. Although CCR3 expression is not regulated by Th2 cytokines in vitro, ASMC isolated from asthmatic patients expressed intrinsically higher levels of the surface receptor when compared to controls. We also describe the expression of CCR1 by ASMC, a receptor involved in airway remodelling in an animal model of asthma. We reported the expression of CCR1 mRNA in biopsies obtained from mild, moderate and severe asthmatics and showed that mild group express the highest level of CCR1. We also confirmed that ASMC express the receptor in vivo and showed that stimulation of this receptor with its ligands induces intra-cellular calcium mobilization, which confirms its functionality. Regulation of CCR1 on ASMC was also assessed using proinflammatory, Th1 and Th2 cytokines. We found that TNF-alpha and to a lesser extent, IFN-gamma, upregulated CCR1 mRNA and protein expression, while Th2 cytokines had no effect. The effect of these two cytokines was totally suppressed by either dexamethasone or mithramycin. / Collectively, our results demonstrate the expression of functional C-C chemokine receptors by ASMC. Interestingly, we have shown that CCR3 activation mediates ASMC migration and provides a new possible mechanism for the increased smooth muscle mass observed in asthmatic patients. Although the exact function of the CCR1 expressed by ASMC is unknown, our results suggest an involvement in asthma pathogenesis, possibly through airway remodelling.

The present thesis explores the relationship between occupational rhinitis and occupational asthma under the postulates of the "united airways disease" concept that refers to the multiple links observed between rhinitis and asthma. Accordingly, the main objective of this thesis is to demonstrate the concomitant expression of significant changes in nasal patency and bronchial calibre following exposure to occupational agents during specific inhalation challenges, complementing the assessment with the investigation of changes in markers of airways inflammation in nasal lavage. To achieve the objectives, we set up a protocol to diagnose occupational rhinitis and conducted a study from January 2005 to January 2007 at Hopital du Sacre-Coeur de Montreal in subjects undergoing investigation for occupational asthma. The reliability of the main research tools---acoustic rhinometry and nasal lavage---used to investigate occupational rhinitis was tested by analyzing the reproducibility of the methods. Both methods proved sufficiently reproducible to be included in our investigative protocol. The results presented in this thesis demonstrate a joint reaction of the nose and the lungs in a group of study subjects after performing specific inhalation challenge. This supports the concept of a "united airways disease" and its applicability to rhinitis and asthma of occupational origin. However, the results also show that although occupational rhinitis frequently coexists with occupational asthma it can also be present without occupational asthma. The assessment of upper airways inflammation in a subgroup of study subjects by the nasal lavage method allows us to observe significant changes in eosinophils counts after the challenge that correlates with the decrease in nasal patency observed in the same subjects.

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The regulation of systemic immune responses is dependent on individual cell responses that will concur to induce a coherent response against a stimulus. In turn, cell response is dependent on the processing of intracellular signals generated at the cell membrane and transmitted through successive protein modifications to the nucleus in order to activate gene transcription. This is referred to as intracellular signalling. Tight control of these mechanisms is required to generate an appropriate cell response to environmental stimulations and globally to establish an appropriate immune response. Among protein modifications used to transmit a signal to the nucleus, protein tyrosine phosphorylation represents a pivotal method used by immune cells to rapidly induce signalling. While protein tyrosine kinases (PTKs) phosphorylate proteins, protein tyrosine phosphatases (PTPs) regulate the signalling by removing the phosphate group. The goal of this study was to better characterize intracellular signalling events involved in allergic asthma, a chronic inflammatory disease involving a Th2 immune response. In a first time, we investigated the role of PTPs in the development of asthma. We show that inhibition of global PTP activity in mice, during either the allergen sensitization or the allergen challenge phase, reduces asthma development and is linked to an increased Th1 response in the spleen and lung. Secondly, we revealed that TC-PTP inhibition reduces asthma development, while PTP-1B inhibition exacerbates inflammatory cells recruitment to the lung. Inhibition of either SHP-1 or PTP-PEST activity did not significantly modulate asthma development in our model. In a third set of experiments, we got interested in the signalling pathways triggered by the pro-inflammatory molecules myeloid-related proteins (MRPs) 8 and 14. MRPs are small cytosolic proteins recently described to have extracellular functions. MRP8 expression is resistant to corticosteroid treatment, and potentially promotes inflammation in corticosteroid-treated patients. We identified that MRPs induce signal through the action of TLR-4 and trigger the activation of MEK/ERK and JNK pathways that lead to NF-kappaB translocation. Collectively, our data provide a new characterization of signalling pathways engaged in allergic asthma. This should be helpful in the elaboration of new therapeutic approaches targeting precise pathways to inhibit mechanisms of inflammation.

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INTRODUÇÃO: A inflamação das vias aéreas na asma envolve respostas imunes inatas. Os receptores do tipo Toll (Toll-like receptors, TLRs) e a citocina linfopoetina do estroma tímico (thymic stromal lymphopoietin, TSLP) estão envolvidos na inflamação brônquica da asma, mas a expressão destas proteínas em vias aéreas grandes e pequenas de asmáticos ainda não foi investigada. Os objetivos deste estudo foram analisar a expressão protéica de TLR2, TLR3, TLR4 e TSLP em vias aéreas grandes e pequenas de asmáticos, comparar sua expressão entre asmáticos tabagistas e não tabagistas e investigar se a expressão dos TLRs está associada à infecção por Chlamydophila pneumoniae e Mycoplasma pneumoniae. MÉTODOS: Foram analisadas por método imuno-histoquímico e análise de imagens as expressões de TLR2, TLR3, TLR4 e TSLP em vias aéreas grandes e pequenas de 24 indivíduos falecidos por asma (13 não tabagistas e 11 tabagistas) e 9 controles não asmáticos. A análise das proteínas foi realizada em quatro regiões das vias aéreas: camadas epitelial, interna, muscular e externa. A presença de C. pneumoniae e M. pneumoniae no tecido pulmonar foi investigada por meio de reação em cadeia da polimerase em tempo real. RESULTADOS: Os indivíduos asmáticos apresentaram maior expressão de TLR2 nas camadas epitelial e externa de vias aéreas grandes e pequenas, e maior TLR2 na camada muscular de vias aéreas pequenas. Asmáticos tabagistas tiveram menor expressão de TLR2 nas camadas interna e externa de vias aéreas pequenas do que asmáticos não tabagistas. Indivíduos asmáticos tiveram maior expressão de TSLP na camada epitelial e externa de vias aéreas grandes, aumento de TLR3 na camada externa de vias aéreas grandes e aumento de TLR4 na camada externa de vias aéreas pequenas. O DNA de C. pneumoniae e M. pneumoniae não foi detectado em nenhum indivíduo asmático ou controle. CONCLUSÕES: Os receptores da imunidade inata TLR2, 3 e 4 e a citocina TSLP estão aumentados nas vias aéreas de pacientes falecidos por asma, e a expressão dos TLRs não está associada à presença de Chlamydophila pneumoniae e Mycoplasma pneumoniae nos pulmões. O tabagismo em asmáticos parece reduzir a expressão de TLR2 em vias aéreas pequenas. Estes resultados sugerem que os TLRs 2, 3 e 4 e a TSLP podem contribuir com a inflamação brônquica presente em exacerbações graves de asma e que as bactérias C. pneumoniae e M. pneumoniae não estão envolvidas em óbitos por asma / INTRODUCTION: Airway inflammation in asthma involves innate immune responses. Toll-like receptors (TLRs) and the cytokine thymic stromal lymphopoietin (TSLP) are involved in bronchial inflammation in asthma, but the expression of these proteins in large and small airways of asthmatics has not been investigated. The aims of this study were to analyze the protein expression of TLR2, TLR3, TLR4 and TSLP in large and small airways of asthmatics, to compare their expression in smoking and nonsmoking asthmatics and to investigate if TLR expression in associated with infection by Chlamydophila pneumoniae and Mycoplasma pneumoniae. METHODS: Using immunohistochemistry and image analysis, we investigated the expression of TLR2, TLR3, TLR4 and TSLP in large and small airways of 24 fatal asthma patients (13 nonsmokers and 11 smokers) and 9 nonasthmatic controls. The protein expression was analyzed in four regions of the airways: epithelial, internal, airway smooth muscle and outer layers. C. pneumoniae and M. pneumoniae presence in lung tissue was analyzed by real-time polymerase chain reaction. RESULTS: Fatal asthma patients had increased expression of TLR2 in the epithelial and outer layers of large and small airways, and also higher TLR2 in the muscle layer of small airways. Smoking asthmatics had lower TLR2 in the inner and outer layers of small airways than nonsmoking asthmatics. TSLP was increased in the epithelial and outer layers of large airways. Asthmatics also had greater TLR3 in the outer layer of large airways and greater TLR4 in the outer layer of small airways. C. pneumoniae and M. pneumoniae DNA was not detected in asthmatics or controls. CONCLUSIONS: Innate immunity receptors TLR2, 3 and 4 and innate cytokine TSLP are increased in the airways of fatal asthma patients, and TLRs expression is not associated with the presence of Mycoplasma pneumoniae and Chlamydophila pneumoniae in the lungs. Smoking may reduce TLR2 expression in the small airways of asthmatics. These results suggest that TLR2, 3, 4 and TSLP may contribute to the bronchial inflammation seen in severe exacerbations of asthma and that M. pneumoniae and C. pneumoniae are not involved in fatal asthma exacerbations