Type 1 Diabetes (T1D) is an autoimmune disease characterized by the destruction of insulin-producing beta cells in the pancreas. Amelioration of T1D and the prevention of its detrimental complications are possible through islet transplantation, wherein hormone-producing clusters of cells, islets of Langerhans (islets), are separated from the pancreas and transplanted into a diabetic patient. However, alterations due to the effects of organ recovery, cold ischemia time (CIT), and islet isolation may increase the inflammatory and immunogenic properties of these islets, thereby predisposing them to functional impairment and rejection in a transplant. Understanding the inflammatory properties of islets will allow for the development of strategies that decrease early islet loss and effectively enhance engraftment and long-term function. Therefore, the aims of this study were to 1) identify and characterize populations of antigen presenting cells (APC) and other immune cells in nonhuman primate (NHP) islets in situ and after isolation; and 2) characterize the expression and functional role of CD40 and the IFN alpha receptor in NHP islets, including their effects on islet immunogenicity. A surprising result of these studies was that half of the APC present in isolated NHP islets were B lymphocytes. We observed that the number of islet-resident immune cells increased with islet size, and described the localization pattern of these cells within islets. We characterized CD40 expression in NHP islets, demonstrating that multiple CD40 isoforms are expressed, and made the novel finding that functional CD40 is expressed on the somatostatin-producing δ cells. When CD40 was stimulated with its ligand, it induced downstream signaling changes, increased proinflammatory cytokine release, and increased islet immunogenicity. Based on our results, we have hypothesized a model of CD40 signaling in islet δ cells. Microarray analysis revealed expression changes in many inflammatory molecules integral to inflammation, the immune response, and apoptosis in islets that had endured increased CIT, demonstrating the unfavorable conditions created within islets following organ recovery, CIT, and islet isolation. Furthermore, we demonstrated that the IFN alpha receptor is present on isolated NHP islets, and that stimulation with IFN alpha leads to increased proinflammatory cytokine release, surface receptor upregulation, and a decrease in immunogenicity. In summary, in NHP islets we have defined the type and quantity of immune cells, the inflammatory molecules expressed, including CD40 and the IFN alpha receptor, and their downstream functional roles in an immune response.

The long-term success of lung transplantation has been challenged by chronic graft dysfunction, which is manifested as obliterative bronchiolitis (OB). We demonstrated that allograft airway fibrosis is a dynamic process of tissue remodelling, in which cellular and matrix components dynamically change before or after complete obliteration of the airway lumen. This dynamic process was associated with changes in expression and activity of matrix metalloproteinases (MMPs). The early inflammatory phase was associated with MMP-dependent migration of blood-borne fibrocytes, which highly express MMP-9 and MMP-12. ‘Established’ fibrosis was associated with MMP-2 and MMP-14 expressed by myofibroblasts in both human OB lesions and their animal models. In established allograft airway fibrosis, general MMP inhibition resulted in apoptosis of myofibroblasts in vivo and in vitro, while low-doses of MMP-inhibitor treatment induced upregulation of MMP-2, increased collagenolytic activity, and significantly decreased myofibroblasts and collagen. The dynamic process of tissue remodelling in established allograft airway fibrosis was supported by underlying continuous alloimmune responses, in particular, direct T-cell-myofibroblast contact. iii Modulation of tissue remodelling using a low-dose MMP inhibitor in combination with cyclosporine induced partial regression of fibrosis after its establishment. We further demonstrated the mechanism of alloimmune responses unique to the lung. Human and animal studies demonstrated that bronchioles develop de novo lymphoid tissue characterized by formation of high endothelial venules and homing of effector memory T-cells. A following study demonstrated the important role of local immunological memory maintained by the intrapulmonary lymphoid tissue in exerting effector function in allograft rejection. Collectively, the present studies support the hypothesis that tissue remodelling is an important mechanism of allograft airway fibrosis. Regulation of tissue remodelling and underlying tissue injury is important not only to arrest aberrant remodelling of allograft airways but likely to reverse aberrant remodelling and to regenerate normal tissue architecture in airways after lung transplantation.

The long-term success of lung transplantation has been challenged by chronic graft dysfunction, which is manifested as obliterative bronchiolitis (OB). We demonstrated that allograft airway fibrosis is a dynamic process of tissue remodelling, in which cellular and matrix components dynamically change before or after complete obliteration of the airway lumen. This dynamic process was associated with changes in expression and activity of matrix metalloproteinases (MMPs). The early inflammatory phase was associated with MMP-dependent migration of blood-borne fibrocytes, which highly express MMP-9 and MMP-12. ‘Established’ fibrosis was associated with MMP-2 and MMP-14 expressed by myofibroblasts in both human OB lesions and their animal models. In established allograft airway fibrosis, general MMP inhibition resulted in apoptosis of myofibroblasts in vivo and in vitro, while low-doses of MMP-inhibitor treatment induced upregulation of MMP-2, increased collagenolytic activity, and significantly decreased myofibroblasts and collagen. The dynamic process of tissue remodelling in established allograft airway fibrosis was supported by underlying continuous alloimmune responses, in particular, direct T-cell-myofibroblast contact. iii Modulation of tissue remodelling using a low-dose MMP inhibitor in combination with cyclosporine induced partial regression of fibrosis after its establishment. We further demonstrated the mechanism of alloimmune responses unique to the lung. Human and animal studies demonstrated that bronchioles develop de novo lymphoid tissue characterized by formation of high endothelial venules and homing of effector memory T-cells. A following study demonstrated the important role of local immunological memory maintained by the intrapulmonary lymphoid tissue in exerting effector function in allograft rejection. Collectively, the present studies support the hypothesis that tissue remodelling is an important mechanism of allograft airway fibrosis. Regulation of tissue remodelling and underlying tissue injury is important not only to arrest aberrant remodelling of allograft airways but likely to reverse aberrant remodelling and to regenerate normal tissue architecture in airways after lung transplantation.

Texte remanié de: Th. doct.--Ethnol.--Bordeaux 2, 2000. Titre de soutenance : Prélèvements et transplantations d'organes et de tissus : de la thérapeutique à l'imaginaire social. / Bibliogr. p. 153-157.

Thèse de doctorat : Médecine. Immunologie : Université de Nantes : 2006. / Bibliogr.

Thèse : Médecine : Paris : 1863. / N° d'ordre : 118. Bibliographie: p. [103]-106.

Zugl.: Halle (Saale), Univ., Diss., 2008

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on February 2, 2010. Major professor: Matthew A. Burd, D.V.M. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Agriculture." "December 2009." Includes bibliographical references (p. 47-52).

Proefschrift--Amsterdam. / "Summary and conclusions" in English. "Literatuur": p. [111]-113.

published_or_final_version / Orthopaedics and Traumatology / Doctoral / Doctor of Philosophy