Pancreastatin ELISA Kit

T cells reactive to b cell Ags are critical players in the development of autoimmune type 1 diabetes. Using a panel of diabetogenic CD4 T cell clones derived from the NOD mouse, we recently identified the b cell secretory granule protein, chromogranin A (ChgA), as a new autoantigen in type 1 diabetes. CD4 T cells reactive to ChgA are pathogenic and rapidly transfer diabetes into young NOD recipients. We report in this article that NOD. ChgA(-/-) mice do not develop diabetes and show little evidence of autoimmunity in the pancreatic islets. Using tetramer analysis, we demonstrate that ChgA-reactive T cells are present in these mice but remain naive. In contrast, in NOD. ChgA(+/+) mice, a majority of the ChgA-reactive T cells are Ag experienced. Our results suggest that the presence of ChgA and subsequent activation of ChgA-reactive T cells are essential for the initiation and development of autoimmune diabetes in NOD mice.

Background: The expression of a specific combination of transcription factors (TFs) in the multipotent progenitor cells (MPCs) is critical for determining pancreatic cell fate. NKX6.1 expression in PDX1(+) MPCs is required for functional beta cell generation. We have recently demonstrated the generation of a novel population of human pluripotent stem cell (hPSC)-derived MPCs that exclusively express NKX6.1, independently of PDX1 (PDX1(-)/NKX6.1(+)). Therefore, the aim of this study was to characterize this novel population to elucidate its role in pancreatic development.& para;& para;Methods: The hPSCs were exposed to two differentiation protocols to generate MPCs that were analyzed using different techniques.& para;& para;Results: Based on the expression of PDX1 and NKX6.1, we generated three different populations of MPCs, two of them were NKX6.1(+). One of these NKX6.1 populations coexpressed PDX1 (PDX1(+)/NKX6.1(+)) which is known to mature into functional beta cells, and an additional novel population did not express PDX1 (PDX1(-)/NKX6.1(+)) with an undefined role in pancreatic cell fate. This novel population was enriched using our recently established protocol, allowing their reorganization in three-dimensional (3D) structures. Since NKX6.1 induction in MPCs can direct them to endocrine and/or ductal cells in humans, we examined the coexpression of endocrine and ductal markers. We found that the expression of the pancreatic endocrine progenitor markers chromogranin A (CHGA) and neurogenin 3 (NGN3) was not detected in the NKX6.1(+) 3D structures, while few structures were positive for NKX2.2, another endocrine progenitor marker, thereby shedding light on the origin of this novel population and its role in pancreatic endocrine development Furthermore, SOX9 was highly expressed in the 3D structures, but cytokeratin 19, a main ductal marker, was not detected in these structures.& para;& para;Conclusions: These data support the existence of two independent NKX6.1(+) MPC populations during human pancreatic development and the novel PDX1(-)/NKX6.1(+) population may be involved in a unique trajectory to generate beta cells in humans.