The cause of fertility problems in insulin-dependent diabetes is largely unknown. To evaluate the role of autoimmunity-associated phenomena in the testis as a possible cause of the derangement in spermatogenesis, the stage-specific apoptosis of germ cells in the insulitis phase of pre-diabetes was quantified in the testes of non-obese diabetic (NOD) mice. The seminiferous epithelium of normal BALB/c and NOD mice contained cells positive for in-situ end-labelling (ISEL) of DNA. ISEL-positive germ cells formed clusters in the seminiferous epithelium of the NOD mice in marked contrast to the seminiferous epithelium of the BALB/c mice, which contained only individual cells positive for ISEL. ISEL-positive cells were present in the basal and luminal compartments of the epithelium. Ultrastructural analysis and demonstration of externalized phosphatidyl serine confirmed that the cells were undergoing apoptosis. The ultrastructurally apoptotic cells included spermatogonia, spermatocytes and spermatids. In cytological squash preparations of segments of seminiferous tubules from NOD mice aged 17-20 weeks, the number of ISEL-positive cells/mm tubule was significantly lower in segments at stages I-II of the seminiferous epithelial wave but higher at stages III-IV in comparison to BALB/c mice. The numbers of ISEL-positive cells/mm tubule in the other stages were similar in the two strains of mice. Analysis of 32P-3'-end labelled DNA from the testes showed that the BALB/c mice had relatively more DNA fragmentation than did the NOD mice. These data suggest that autoimmune insulitis in the NOD mice is associated with increased amounts and abnormal stage distribution of apoptosis in the seminiferous epithelium, resulting in derangement of spermatogenesis.
The role of cytokine balance and lipid antigen presentation in the development of diabetes was studied using immunohistochemistry of cytokines in the pancreas of non-obese diabetic mice (NOD) and BALB/c mice at various ages. In both the NOD and BALB/c mice, interleukin 10 (IL-10) was expressed in the islets. IL-10 was also present in the epithelial cells of the exocrine tissue in both strains. In the NOD mice, IL-10 disappeared from both the islets and the exocrine tissue at 16 weeks of age. At this age, IL-10 was still present in the islets and exocrine tissue of the BALB/c pancreata. IL-10 was not present in the pancreata of diabetic NOD mice. IL-6 first appeared in the pancreas at 10 weeks of age and disappeared at the age of 16 weeks in both NOD and BALB/c mice. It was present in the endothelial cells. Neither the pancreata of normal BALB/c mice nor NOD mice at 2-16 weeks of age contained tumor necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), IL-4, or IL-12. At 8 weeks of age, a few IL-2+ cells were found in the pancreas of one of three NOD mice. CD1d was already present in both strains at 2 weeks of age but disappeared from the NOD mice at 16 weeks of age. CD1d localized to walls of tubular structures probably representing collecting tubules. These results suggest that in the NOD mice the disappearance of the T(H0), T(H1), and T(H2) responses inhibiting IL-10 from the islets at the age of 16 weeks may trigger the final stage of the immune response leading to overt diabetes. The simultaneous disappearance of CD1d suggests that activation of immune responses against lipid antigens does not play a role in this stage of the disease.
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