Lung disease is the third leading cause of death worldwide. The only curative intervention for end-stage lung disease is lung transplantation, which remains limited by the shortage of viable donor organs. Strategies to improve outcomes for patients with end-stage lung disease include: (i) ex vivo recovery of initially unusable donor lungs to a level suitable for transplantation, and (ii) repair of damaged lungs in situ to avoid the need for transplantation. Recovery of damaged lungs both ex vivo and in situ necessitates precise regulation of the lung extracellular environment, which includes biochemical, physical, and mechanical stimuli across scales. This thesis describes the development of bioengineering tools, including bioreactors and biomaterials, that leverage the lung extracellular environment across cellular, tissue, and organ scales to: (i) recover whole injured donor lungs ex vivo, (ii) assess and repair regional lung tissue injury in situ, and (iii) study the pathological cellular microenvironment in cystic fibrosis. In Chapter 1, regulation of the organ macroenvironment (ventilation, perfusion, systemic metabolism) with a homeostatic cross-circulation bioreactor enabled up to 100 hours of ex vivo lung support and recovery of injured human donor lungs. In Chapter 2, quantitative analysis of localized lung tissue properties, including lung sounds, enabled detection and assessment of pulmonary air leak, and recapitulation of lung microenvironmental features (structure, mechanics, composition) in a therapeutic biomaterial sealant enabled rapid treatment of air leaks. In Chapter 3, the first quantitative characterization of the cystic fibrosis matrisome (matrix proteome) identified pathological alterations to the microenvironment, and investigated implications for inflammation and immunity in cystic fibrosis. Collectively, these studies demonstrate that macro- and microenvironmental signals, including ventilation and perfusion mechanics, homeostatic metabolic regulation, and extracellular matrix structure and composition, can be leveraged to reveal previously unknown drivers of disease and promote recovery and repair of damaged lungs.

Abstract not available

Lung transplantation is the only therapeutic approach for patients presenting end-stage pulmonary failure. Despite progress made in organ preservation and immunosuppression, primary graft dysfunction and obliterative bronchiolitis still hamper short-term and long-term outcomes, respectively. Interleukin-17 recently emerged as a major actor in several immuno-inflammatory disorders. Clinical and experimental evidence also suggest the implication of interleukin-17 or type 17 CD4+ T cells in lung rejection. We therefore investigated the contribution of this cytokine to graft pathology in a murine model of tracheal transplantation that recapitulates pathological features of lung rejection including the development of obliterative airway disease.<p>We first demonstrated that interleukin-17 contributes to inflammatory lesions in the early phase post-transplantation. Interleukin-17 was found to be produced by &61543;&61540;+ T cells and CD4+ T cells infiltrating the graft and interleukin-17 neutralization significantly reduced the development of epithelial lesions together with inhibition of interleukin-6 and heat-shock-protein 70 gene transcription.<p>We then investigated the contribution of interleukin-17 to obliterative airway disease. Although interleukin-17 did not play a dominant role in absence of immunosuppression, it was found to contribute to airway pathology in animals receiving cyclosporin A. Under this treatment, we first observed dramatic changes in the composition of the lymphocyte populations infiltrating the graft: the numbers of CD8+ T cells producing interferon-&61543; and type 1 CD4+ T cells were dramatically decreased while the numbers of type 17, and also type 2 CD4+ T cells were unaffected. The pathological relevance of these findings was first demonstrated by the prolongation of graft survival afforded by the depletion of CD4+ T cells in cyclosporin A-treated animals. Furthermore, graft rejection was also delayed in mice genetically deficient in either interleukin-17 or interleukin-4, providing evidence that type 17 and type 2 CD4+ T cells actively contribute to graft rejection in cyclosporin A-treated recipients. On the other hand, parallel experiments in interferon-&61543;-deficient mice revealed that interferon-& / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

This work discusses the role of CT in the etection and quantification of chronic allograft rejection in patients after lung transplantation and provides solutions to the technical challenges involved with this approach. / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished