Diabetes mellitus is amongst the leading causes of morbidity and mortality worldwide. Insulin-producing pancreatic β-cells are central in establishing adequate glucose regulation and loss of... Show moreDiabetes mellitus is amongst the leading causes of morbidity and mortality worldwide. Insulin-producing pancreatic β-cells are central in establishing adequate glucose regulation and loss of functional β-cells results in the development of diabetes. Although it was previously thought that fully differentiated cells cannot change phenotype, murine studies recently indicated that mature β-cells can change identity into other islet cells under conditions of (metabolic) stress.We present a novel agarose based microwell culture system that can be used for aggregate formation of human or rodent islet cells. We show that this platform provides reproducible results to study aggregation of primary human islet cells. Using this culture system together with β-cell specific lineage tracing, we find that mature human β-cells can spontaneously lose their identity and convert into glucagon-containing α-cells. We then used human pancreatic tissue from donors with T2DM and matched controls to explore loss of β-cell identity in T2DM. We report that cells indicative of loss of β-cell identity are found more frequently in tissue samples from donors with a history of T2DM. Finally, we show that Pax4 and GLP-1 receptor agonists can partially prevent loss of identity β-cell in our ex vivo model. Show less
Type 1 Diabetes is caused by destruction of insulin producing beta-cells by autoimmune T-cells. Replacement of beta-cells through transplantation can supply new beta-cells, however these are at... Show moreType 1 Diabetes is caused by destruction of insulin producing beta-cells by autoimmune T-cells. Replacement of beta-cells through transplantation can supply new beta-cells, however these are at renewed peril of destruction through auto- and alloreactive immune responses. In this thesis, immune challenges, intervention strategies and biomarkers to guide treatment are investigated. Patient heterogeneity was identified as contributing factor to variations in efficacy of immune intervention therapies for type 1 diabetes. Immune infiltrations that matched with immune monitoring results were seen around islets transplanted to the liver of a patient. Cytokine and autoantibody immune markers were described that correlated with outcome of islet transplantation and combined kidney and pancreas transplantation. Immune consequences of tapering immune suppression after islet transplantation to minimize side effects were explicated. The immunological challenges that await beta-cells of alternative sources after transplantation, such as beta-cell lines and embryonic stem cells, were explored and pointed to need for immune protection and immune monitoring in early transplantation trials. These results support further investigation of immune intervention with disease specific immune modulation and beta-cell encapsulation strategies to achieve the desired drastic improvement in efficacy-risk balance for type 1 diabetes therapies. Show less
Pancreas transplantation and islet of Langerhans transplantation are potential solutions to treat patients with type 1 diabetes. However, pancreas grafts are scarce and there is a shortage of donor... Show morePancreas transplantation and islet of Langerhans transplantation are potential solutions to treat patients with type 1 diabetes. However, pancreas grafts are scarce and there is a shortage of donor pancreata relative to the number of patients needing a transplant. The aim of this thesis was to further optimize pancreas graft survival in pancreas transplantation and to optimize islet isolation outcomes in islet of Langerhans transplantation, leading to better use of available organs. The focus in pancreas transplantation should be on optimizing recipients to improve graft survival and on improving quality of pancreata procured by centers not performing pancreas transplantation (for example, by training procurement surgeons to optimize pancreas procurement, thereby increasing the number of transplantable organs. In islets transplantation, it is recommended that the reporting of donor, pancreas and isolation factors should become more standardized, which would enable us to determine more accurately which factors are important predictors for islet isolation outcome. Furthermore, if more biomedical factors (e.g. the presence of hyperemic islets) would be reported in addition to the other factors, we would be able to assess the independent effect of these biomedical factors for islet isolation outcome and eventually the effect on islet transplantation in the clinical setting. Show less
Type 1 diabetes is a common, multifactorial disease in which T cell autoimmunity plays an important role. Important research advances in recent years have fuelled the expectation that a definitive... Show moreType 1 diabetes is a common, multifactorial disease in which T cell autoimmunity plays an important role. Important research advances in recent years have fuelled the expectation that a definitive cure for the disease can be achieved for a large number of patients. In the first part of this thesis, the considerable clinical and immunological potential for intervention in the diabetogenic autoimmune process is described of the T cell costimulatory molecule CTLA4 and the autologous heat shock protein peptide DiaPep277. The second part focuses on islet and pancreas transplantation as a cure for type 1 diabetes. Next to the influence of allograft rejection and the effects of immunosuppressive therapy, associations are described between the presence and recurrence of diabetes-specific autoimmunity and clinical outcome of transplantation. Furthermore, possible factors are identified that may be modulated for improvement of outcome, and predictive biomarkers are suggested that may guide future treatment. In conclusion, this thesis recognizes T cell autoimmunity as an important entity in type 1 diabetes therapy, distinct from other types of immune reactivity. Tailored therapy for individual patients guided by close immune monitoring is being developed but needs to be improved further to establish a definitive cure for type 1 diabetes. Show less
