Modulation of low-dose streptozotocin-induced diabetes in mice by administration of antibodies to I-A, I-E and I-J determinants

Suppression of insulitis and diabetes in B cell-deficient mice treated with streptozocin: B cells are essential for the TCR clonotype spreading of islet-infiltrating T cells

In order to clarify the role of B cells in the development of insulitis and diabetes, B cell-deficient (B(-)) mice treated with streptozocin (STZ) were studied. The extent of insulitis and the cumulative incidence of diabetes were significantly suppressed in B(-) mice (P < 0.0001), indicating that B cells are crucial for the progression of insulitis and diabetes. Accumulation of both CD4(+) T cells and B cells was observed in islets of B(+) mice, while CD4(+) T cells but not B cells were found in B(-) mice. A few CD8(+) T cells and macrophages were detectable in both types of mice. The immunohistochemical study did not reveal any change in the subpopulations of infiltrating lymphocytes except for the absence of B cells in the B(-) mice. TCR V(beta) gene repertoire usage of islet-infiltrating T cells was restricted to some extent in the B(+) or B(-) mice, but there was no significant difference between the B(+) and B(-) mice, suggesting that the initial islet-reactive T cell response can occur in the absence of B cells. In contrast, TCR clonotype spreading of islet-infiltrating T cells was significantly suppressed in B(-) mice compared with B(+) mice (P < 0.0001). These data suggest that initial priming of T cells is not impaired and TCR V(beta) repertoire usage is not limited by the lack of B cells, while B cells are important essentially for the spreading of islet-infiltrating clonal T cells in autoimmune diabetic mice induced with STZ.

Increased waist size and weight in relation to consumption of Areca catechu (betel-nut); a risk factor for increased glycaemia in Asians in east London

Type 2 diabetes is commoner in Asians than Caucasians. Many nitrosamines are diabetogenic, causing both type 2 and type 1 diabetes. Of CD1 mice fed with betel-nut or associated nitrosamines 8.5% develop glucose intolerance with marked obesity. Glycaemia and anthropometric risk markers for type 2 diabetes were therefore examined in relation to betel usage in 993 'healthy' Bangladeshis by one bilingual research-worker (N.M.). Of these, 12% had known diabetes. A further 145 of 187 subjects 'at-risk' of diabetes (spot glucose > 6.5 mmol/l < 2 h after food, or > 4.5 mmol/l > 2 h after food) had a second blood glucose sample taken; sixty-one were confirmed as 'at-risk', and had an oral glucose tolerance test; nine new diabetics were identified. Multiple regression analysis showed that spot blood glucose values decreased with time after eating (P = 0.0005) and increased independently with waist size (P = 0.0005) and age (P = 0.0005) without relationships to other aspects of the diet, season or smoking. Waist size was strongly related to betel usage independent of other factors such as age. Betel use interacted with sex, relating to increasing glycaemia only in females. Since waist and age were the major markers of increasing glycaemia we suggest that betel chewing, a habit common to about 10% of the world population (more than 200 million people) may contribute to the risk of developing type 2 diabetes mellitus.

Multidose streptozotocin induction of diabetes in BALB/cBy mice induces a T cell proliferation defect in thymocytes which is reversible by interleukin-4

Thymic T cell function in streptozotocin-treated (STZ) diabetic mice has been examined. STZ administration suppresses thymic T cell proliferation in response to mitogen stimulation in vitro. Secretion of IL-4 was dramatically reduced; however, secretion of IL-2 or IFN-gamma was not significantly inhibited. RT-PCR analysis of thymocyte RNA revealed that levels of IL-4 mRNA were dramatically decreased in STZ-treated mice. Levels of mRNA encoding IFN-gamma were similar, but the appearance was delayed in thymocytes derived from STZ-treated mice, implying differential regulation of IL-4 and IFN-gamma. Defective thymocyte proliferation was partially restored by exposure to IL-2 in vitro; however, IL-4 completely reversed the STZ-induced defect. Administration in vivo of IL-4 before STZ treatment reversed the STZ-induced thymocyte proliferation defect and prevented both pancreatic islet destruction and hyperglycemia. Thymocyte cell surface differentiation markers were not appreciably different from control mice. Collectively these experiments suggest that STZ treatment of mice reduces expression of IL-4 which is associated with development of autoimmune diabetes.

Animal models of autoimmune endocrine disease and their uses in developing new methods of intervention

This review provides basic information concerning the major animal models in use for the study of autoimmune endocrine diseases (AEDs). Although several other models exist which parallel human AEDs such as autoimmune orchitis, most research in this area has centred on animal models of insulin-dependent diabetes mellitus (IDDM) and thyroiditis. These models, between them, appear to exhibit most of the disease manifestations of their human counterparts and thereby permit the study of possible methods of intervention in the disease process. While no one model represents a perfect correlation with the human disease it represents, common characteristics are recognizable between them. For instance, the central role of activated T cells in controlling the disease process. The chapter continues by examining the various ways in which models of autoimmunity, specifically IDDM and experimental allergic thyroiditis (EAT), have been used to investigate the possibility of preventing or arresting autoimmune destruction. Several different approaches are described that illustrate the variety of techniques that have proven both potentially, or in reality, effective and those that have proven less efficacious than first hoped.

Betel nut (Areca catechu) consumption and the induction of glucose intolerance in adult CD1 mice and in their F1 and F2 offspring

Many mutagenic nitroso compounds are also diabetogenic. Betel-nut (Areca catechu) chewing populations have an increased incidence of foregut cancers related to betel-nut nitrosamines which suggests that betel consumption could be diabetogenic. Young adult CD1 mice with a low spontaneous incidence of diabetes were fed betel nut in standard feed for 2-6 days. Single point (90 min) intra-peritoneal glucose tolerance tests were used to follow glucose tolerance up to 6 months of age. Glucose intolerance was defined as over 3 SD above mean control values. Glucose intolerance was found in 3 of 51 male and 4 of 33 female adult mice which were fed the betel diet (p < 0.01). Studies on the progeny of these mice are presented separately for animals studied in Aberdeen (Group 1) and London (Group 2). In matings of Group 1 betel-fed parents glucose intolerance was found in 4 of 25 male and 1 of 22 female F1 offspring, with significant hyperglycaemia in F1 males born to hyperglycaemic but not to normoglycaemic mothers (p < 0.01). In the F2 generation 4 of 23 males and 1 of 16 females and in the F3 generation 1 of 16 males and 0 of 20 females were glucose intolerant. In the Group 2 studies where betel-fed parents were mated to normal controls glucose intolerance was found in 10 of 35 male and 10 of 33 female F1 progeny (p < 0.005), and mean islet areas were increased in offspring of betel-fed parents (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)