Transgenic expression of interleukin 10 in the pancreas renders resistant mice susceptible to low dose streptozotocin-induced diabetes

Transgenic mice expressing interleukin 10 (IL-10) within the beta cells of the pancreas were used to assess the role of this cytokine in the development of diabetes following low-dose streptozotocin treatment. Nontransgenic mice injected with low doses of streptozotocin were largely resistant to the induction of hyperglycaemia; that is, average blood glucose values, although above mean blood glucose levels of buffer-injected controls, did not exceed 14 mmol/l. In sharp contrast, IL-10 transgenic mice exhibited significant sensitivity to the diabetogenic actions of streptozotocin resulting in a mean blood glucose level of 21.6 mmol/l at the end of the 56-day study period. Histological analysis of pancreata from streptozotocin-injected transgenic mice revealed severe insulitis and destruction of pancreatic beta cells, whereas their streptozotocin-injected nontransgenic littermates remained completely insulitis-free. According to immunocytochemical analysis, the pancreatic inflammatory infiltrates of streptozotocin-injected transgenic mice contained CD4+ and CD8+ T lymphocytes, B lymphocytes and macrophages. Furthermore, various adhesion molecules, the co-stimulatory molecule B7-1 and the Ia antigen could be detected. Splenocytes from streptozotocin-injected transgenic mice did not transfer disease to irradiated syngeneic nontransgenic recipients, suggesting that the presence of IL-10 in streptozotocin-injected mice had a general immunostimulatory effect but did not lead to the activation of beta cell-specific T cells. Our data suggest a critical role for IL-10 in the development of diabetes in vivo despite its established immunosuppressive activities in vitro.

Transient and permanent neonatal diabetes

Neonatal diabetes, which may be transient or permanent, is rare. Most patients are full-term but small- for-date infants. Typical symptoms of diabetes mellitus occur within the first 4 weeks of life, requiring insulin therapy and very strict blood glucose monitoring. Subsequent growth and psychomotor development are usually normal. In about 33% of these patients the diabetes remains permanent; the transient cases, however, often develop permanent diabetes mellitus later in life. Exocrine pancreatic insufficiency is present in some patients. Neonatal diabetes differs from type-I diabetes in many aspects and seems to form a distinct entity of inborn pancreatic malfunction.

Nonspecific immunity in diabetes: hyperglycemia decreases phagocytic activity of leukocytes in diabetic patients

Phagocytic activity of leukocytes in blood was examined in 70 patients with diabetes mellitus. 40 of them had insulin-dependent diabetes--(IDDM) or type I, while there were 30 patients with noninsulin-dependent diabetes (NIDDM) or type II. Phagocytic activity of leukocytes was determined by quantitative method of ingestion, on the principle of quantifying phagocytized fungi (Saccharomyces cerevisiae) and free phagocytes (nonphagocytizing leukocytes) by means of a phase-contrast microscope. The data have been statistically processed by the Student t-test and variance analysis test (Duncan test). The index of phagocytosis amounted to 3.2 +/- 0.77 in diabetic patients, while it was 3.47 +/- 0.29 in healthy examinees from the control group, thus yielding a statistically significant difference, p < 0.05. Out of all examined parameters (blood glucose, glycosylized hemoglobin, mean glucose value) phagocytic activity of leukocytes showed a statistically significant correlation with mean value of glucose in blood. Patients with mean glucose value higher than 12 mmol/l showed a significantly lower index of phagocytosis (2.9 +/- 0.84) than patients whose mean glucose value was lower than 12 mmol/l (3.5 +/- 0.59), p < 0.05. Neither age and sex of the patients nor chronic complications caused by diabetes affected the phagocytic activity of leukocytes in diabetic patients. There was no significant difference in the phagocytic activity of leukocytes between patients with IDDM and those with NIDDM.

Induction of insulin resistance by autoantibodies to insulin receptors following on an acute Coxsackie B4 infection

We report a case of a young women who developed hyperglycemia shortly after Coxsackie B4 infection. Her clinical course was characterized by insulin resistance and the presence of anti-insulin receptor antibodies, without acanthosis nigricans.

Serum immunoglobulin concentrations in diabetic patients

The relationship between glycated haemoglobin (an index of long-term diabetic control), fructosamine (an index of intermediate-term diabetic control), and serum IgA, IgG, and IgM was studied in 110 diabetic patients (41 Type 1 and 69 Type 2) and compared with 111 healthy non-diabetic subjects. Significant increases in serum IgA (by 82.7%, p < 0.001) and IgG (by 35.2%, p < 0.001) concentrations were observed whereas the concentration of IgM was significantly decreased (by 46.7%, p < 0.001) in diabetic patients compared with non-diabetic subjects. Using Spearman's rank correlations, IgA correlated with fructosamine (r = 0.77, p < 0.001), HbA1 (r = 0.76, p < 0.001), and albumin (r = -0.58, p < 0.001) for the entire population sample but only fructosamine (r = 0.19, p < 0.05) and HbA1 (r = 0.28, p < 0.001) correlated with IgA in diabetic patients, respectively. It is concluded that abnormal levels of IgA, IgG, and IgM are very common in diabetic patients in whom serum IgA concentrations are influenced by the degree of glycaemic control. Whether changes in IgA and other immunoglobulins are implicated in the pathogenesis of diabetic complications (such as susceptibility to infection) deserve further study.

[Effect of metabolically uncompensated diabetes mellitus on mononuclear cell populations in peripheral blood]

The study has been aimed at comparison of the number of peripheral blood mononuclear white cells in the E. SRBC, EA, EAC, SIg markers in patients with insulin dependent (type 1) and non-insulin dependent (type 2) diabetes and healthy donors. There was no marked difference in the numbers of surface markers E SRBC and SIg among the 3 groups. Significant increase in the number of cells with markers: FcIg and C3 fragment of complement was noted in patients with diabetes type 1 and type 2. No relation between the number of mononuclear cells in peripheral blood and the blood glucose level was observed.

Islet cell cytoplasmic antibodies (ICA) in diabetes and disorders of glucose tolerance

Islet cell cytoplasmic antibodies were determined in 85 individuals 60 to 74 years old with fasting hyperglycaemia, in 65 patients with cystic fibrosis, in 113 patients with pancreatitis, in 21 patients with Turner's phenotype, and in 135 first-degree relatives of patients with Type 1 (insulin-dependent) diabetes. Islet cell antibodies were absent in all 60 to 74-year-old subjects with fasting hyperglycaemia detected by screening, and who did not require insulin treatment within 3 years. Islet cell antibodies were also absent in all patients with pancreatitis, cystic fibrosis, or Turner's phenotype. Islet cell antibodies were detected in 2 out of 135 (1.5%) first-degree relatives of new Type 1 diabetic patients, and in 1 out of 371 (0.3%) non-diabetic control subjects. During 12 years of follow-up 1 of the 2 first-degree relatives with islet cell antibodies and the only positive control developed Type 1 diabetes. It is suggested that islet cell antibodies are primarily associated with Type 1 diabetes and not with other disorders of glucose tolerance.

Characterization of pancreatic T lymphocytes associated with beta cell destruction in the non-obese diabetic (NOD) mouse

Pancreatic beta cell destruction in the non-obese diabetic (NOD) mouse is mediated by T lymphocytes and macrophages and accelerated by cyclophosphamide. We purified pancreatic T lymphocytes from the NOD mouse for comparative phenotypic and functional analysis with T lymphocytes from spleen, peripheral blood and regional lymph nodes. Pancreatic T lymphocytes from NOD-Wehi mice, which have an incidence of spontaneous diabetes of less than 5%, had a CD4:CD8 ratio of 1.25 +/- 0.23 compared with 2.44 +/- 0.31 for peripheral blood lymphocytes. After cyclophosphamide, the CD4:CD8 ratio of pancreatic lymphocytes increased to 2.30 +/- 0.24 at day 7. T lymphocytes bearing IL-2 receptors increased two- to three-fold in number and their secretion of GM-CSF/IL-3 and IFN-gamma increased to a maximum on day 7. Pancreatic insulin content and mRNA levels declined sharply between days 10 and 12, at which time the majority of pancreatic T lymphocytes in hyperglycaemic mice were CD8+ (CD4:CD8 ratio 0.63 +/- 0.04 compared to 4.14 +/- 1.05 in peripheral blood). The pancreatic T lymphocyte CD4:CD8 ratio in prediabetic NOD-Lt mice, which have an incidence of spontaneous diabetes of about 60% at 150 days, was similar to that in untreated NOD-Wehi mice, but 25% of their pancreatic CD8 T lymphocytes were IL-2-receptor positive. Thus, significant changes in the phenotype of NOD pancreatic T lymphocytes following cyclophosphamide were not reflected in peripheral blood or spleen T lymphocytes. The earliest change after cyclophosphamide was an increase in activated, predominantly CD4+ T lymphocytes; with the development of beta cell destruction and hyperglycaemia, pancreatic T lymphocytes were, as in human IDDM, predominantly CD8+.

Nonenzymatic glycosylation of immunoglobulin G impairs complement fixation

Transient hyperglycemia in patients receiving total parenteral nutrition may be associated with impaired immune function. The effects of short-term hyperglycemia on one aspect of antimicrobial immune function, ie, the ability of IgG to fix complement, were investigated. Aliquots of anti-human albumin, anti-horse ferritin, and anti-alkaline phosphatase were incubated for 0, 8, 16, 24, 48, and 96 hr with either 0 or 240 mg of glucose per deciliter of buffer. All samples were analyzed for the degree of glycation using a thiobarbituric acid assay, and for complement fixation ability using a microcomplement fixation assay. Significant increases in glycation over control samples were observed after only 16 hr (31 vs 15 mmol 5-hydroxymethylfurfural/mol IgG, p less than 0.01). Complement fixation was significantly altered after 48 hr of incubation (76 +/- 5% vs 90 +/- 8% total serum complement fixed by albumin/anti-albumin complex, p less than 0.03) when four of the 84 (4.7%) IgG lysine residues were glycated. It is demonstrated that a significant reduction in complement fixation by immunoglobulin occurs with elevated glucose concentrations and that this may play a clinically significant role in transiently hyperglycemic patients.

Short-term hyperglycemia depresses immunity through nonenzymatic glycosylation of circulating immunoglobulin

Hyperglycemia accompanies a myriad of clinical conditions and causes an acceleration in the nonenzymatic glycosylation (NEG) of proteins. Since many proteins lose function when glycosylated, we assessed the effect of hyperglycemia on the function of immunoglobulin G. Twenty newborn Sprague-Dawley rats underwent splenectomy and 20, splenic mobilization alone. After 3 weeks, all animals received an intraperitoneal injection of Streptococcus pneumoniae. Twelve hours later, ten animals from each group received either control (CIG) or glycosylated (GIG) human immunoglobulin (0.3 gm/kg) intraperitoneally. Asplenic animals receiving GIG lived 28.5 hours vs. 49.6 hours for those receiving CIG (p less than 0.0001). Animals with spleens receiving GIG lived 48.2 hours vs. 51.7 hours for those receiving CIG (p = 0.03). Short-term glycosylation of immunoglobulin causes its inactivation. This may contribute to the increased risk of infection noted in hyperglycemic animals.

Complement-dependent antibody-mediated cytotoxicity in the spontaneously diabetic BB/OK rat: association with beta cell volume density

The present study examined in the spontaneously diabetic BB/OK rat whether a relationship exists between the appearance of complement-dependent antibody-mediated cytotoxicity (C'AMC) in serum and the relative beta cell volume density determined in pancreatic biopsies. C'AMC was estimated by 51Cr release from prelabeled major histocompatibility complex-compatible neonatal rat islet cells after exposure to rat serum and rabbit complement. Fifty-one percent (72/141) of sera from BB/OK rats with newly diagnosed diabetes were positive for C'AMC. At onset of hyperglycemia, insulin-immunoreactive beta cells were only detectable in pancreas biopsies of 25% (10/40) of the BB/OK rats who displayed mild hyperglycemia (plasma glucose 8.3-13.0 mmol/l) and low serum C'AMC. A twofold increase (p less than 0.01) of C'AMC and loss of the remaining beta cells was evident in untreated animals upon their reexamination within 1 week after diagnosis of hyperglycemia. Initiation of insulin therapy prevented neither the increase in C'AMC activity nor the decrease in the beta cell volume density. In contrast, three out of four mildly hyperglycemic BB/OK rats treated with cyclosporin A maintained both their initial C'AMC levels and relative beta cell volume density not only throughout the treatment period (4 weeks) but also for at least 4 weeks thereafter. In one additional animal receiving cyclosporin A no protection of the remaining beta cells could be achieved and C'AMC levels were markedly increased. It is concluded that the appearance of increased C'AMC in serum may reflect autoimmune reactions against the islet beta cells of spontaneously diabetic BB/OK rats. The increase of C'AMC seen in untreated as well as insulin-treated BB/OK rats, which were even devoid of beta cells, suggests that C'AMC activity appears secondary to the loss of beta cells. These results do not support the hypothesis of a direct beta cell destruction via intrainsular complement activation.

Handicaps to host defense. Effects of hyperglycemia on C3 and Candida albicans

The hyperglycemic patient remains persistently at risk for infectious complications. Whether ascribable to diabetes mellitus, to the administration of glucocorticoids, or to the infusion of hyperalimentation fluids, hyperglycemia may impair several mechanisms of humoral host defense, including such varied neutrophil functions as adhesion, chemotaxis, and phagocytosis. In addition, binding of glucose to the biochemically active site of the third component of complement C3 inhibits the attachment of this protein to the microbial surface and thereby impairs opsonization. Last, several pathogens frequently encountered in hyperglycemic patients possess unique mechanisms of virulence that flourish in the hyperglycemic environment. Most notable in this regard is the yeast Candida albicans, which expresses a glucose-inducible protein that is structurally and functionally homologous to a complement receptor on mammalian phagocytes. This protein promotes adhesion in the yeast and subverts phagocytosis by the host. Thus, hyperglycemia serves as a central mechanism in the predisposition of hyperglycemic patients to infection.

[Hypoinsulinemia, hyperglycemia and circulating antibodies to the islet cells during the development of streptozotocin diabetes in rats]

The time course of metabolic parameters and islet cell surface antibodies (ICSA) in low-dose streptozotocin (STZ)-induced diabetes in rats was studied, a total STZ dose being 160 mg/kg body weight. Two-phase diabetes development was observed. Initial mild hypoinsulinemia and hyperglycemia turned to more severe diabetes after day 24 which was preceded by the first ICSA peak at day 13. The second ICSA peak occurred at day 35. The data obtained suggest that in this model of diabetes the toxic STZ effect induces both the diabetic syndrome and humoral autoimmunity to beta-cells, and the latter leads to further impairment of diabetes.

Fish oil-enriched diet and reduction of low-dose streptozocin-induced hyperglycemia. Inhibition of macrophage activation

Repeated low doses of streptozocin (STZ; 40 mg/kg, 5 injections/day) induce hyperglycemia in certain strains of mice after a latency of 1 wk. Omega-3 polyunsaturated fatty acids (omega 3FA) have been reported to suppress immune processes by blockade of the cyclooxygenase pathway of arachidonic acid metabolism. We investigated the effects of diets high in omega 3FA on the development of diabetes in the low-dose STZ-induced diabetes (LDSTZ-D) model. Male C57BL/6J mice were on a fish oil diet (FOD) as a source of omega 3FA 8 wk before STZ injection. Controls received laboratory chow only or a coconut oil diet (COD). Blood glucose levels in FOD mice were reduced (12.5 vs. 28 mM for COD mice, P less than .001) 60 days after STZ injection with a diet in which 20% of the calories were from fish oil. In FOD mice, immunohistology showed reduced numbers of class II antigen-expressing cells in pancreatic islets followed by a decreased extent of insulitis. FOD significantly decreased the number of Fc receptor-negative dendritic cells in cytospin preparations of islets isolated from diabetic mice. Interleukin 1-like activity of peritoneal exudate cell supernatants isolated from mice on FOD was reduced. FOD did not improve insulin secretion of isolated islets from LDSTZ-D mice. These data indicate a beneficial effect of FOD on the immune component of the mouse LDSTZ-D model.

Natural history of incidental hyperglycemia and glycosuria of childhood

We prospectively followed 29 children and adolescents over a 1- to 8-year period who were referred for evaluation of hyperglycemia (in the absence of diabetes) or glycosuria found on routine screening or during acute illness. On initial examination, four subjects had islet cell autoantibodies, 4 of 22 had an abnormal intravenous glucose tolerance test result, 6 of 22 had low first-phase insulin release on intravenous glucose tolerance testing, and 10 of 20 had impaired glucose tolerance on oral glucose tolerance testing. On follow-up, insulin-dependent diabetes had developed in two of the four subjects with islet cell autoantibodies. The other two subjects with islet cell antibodies have had persistently abnormal glucose tolerance on both oral and intravenous glucose tolerance testing and have low first-phase insulin responses. Diabetes has developed in none of 25 subjects without islet cell antibodies, although two have persistently abnormal glucose tolerance or insulinopenia. All five subjects with islet cell antibodies or human leukocyte antigen DR3/DR4 with initial impaired glucose tolerance have either acquired diabetes or have abnormal glucose tolerance. In contrast, only one of five subjects with initial impaired glucose tolerance but lacking these markers has persistent glucose intolerance. We conclude that in the absence of islet cell antibodies or human leukocyte antigen DR3/DR4 heterozygosity, incidental hyperglycemia or glycosuria is unlikely to be associated with progression or diabetes.

Assessment of pancreatic islet-cell population in the hyperglycemic athymic nude mouse: immunohistochemical, ultrastructural, and hormonal studies

Previous studies in diabetic animal models have demonstrated altered pancreatic islet-cell populations. To further characterize the diabetic syndrome in our athymic nude mouse colony, we studied the population of endocrine cells in pancreatic islets of 4-week-old normoglycemic and 8-week-old hyperglycemic athymic nude (nu/nu) mice using immunohistochemistry, morphometry, and electron microscopy. In normoglycemic 4-week athymic nu/nu mice, the proportions of B (insulin-secreting) cells and A (glucagon-secreting) cells were similar to those in control Balb/c mice; however, the D (somatostatin-secreting) cells were significantly decreased in nu/nu mice. The populations of B and A cells appeared to be normal in hyperglycemic 8-week-old nu/nu mice while there was a significant increase in the proportion of D cells when compared with the proportion in Balb/c mice. Electron microscopic studies indicated that the appearance of B and A cells was similar in the 8-week-old hyperglycemic nu/nu and in controls; however, the D cells appeared to be enlarged and were finely packed with electron-dense secretory granules. Radioimmunoassays of the pancreatic content (micrograms/g fresh pancreas) of insulin, glucagon, and somatostatin in pancreata in 8-week-old normal Balb/c and hyperglycemic athymic nude mice were similar; however, the somatostatin content was significantly increased in the 8-week-old hyperglycemic nu/nu mice compared with age and sex-matched controls. These results demonstrate an altered D cell population and an increase in somatostatin levels in the pancreatic islets of the hyperglycemic athymic nude mouse animal model.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of class II MHC antigens in murine pancreas after streptozocin-induced insulitis

In this study, most class II antigen expression during streptozocin-induced insulitis was associated with the mononuclear cells infiltrating the pancreas. During the early stages of the insulitis response, phagocytic cells expressing class II antigens and containing beta-cell debris were often observed. Although there was de novo expression of class II antigens by ductular epithelium associated with the exocrine portion of the pancreas and transient expression by vascular endothelial cells, the endocrine cells of the islets remained devoid of class II antigens throughout the period of observation (42 days).

Effect of helper and/or cytotoxic T-lymphocyte depletion on low-dose streptozocin-induced diabetes in C57BL/6J mice

The low-dose streptozocin (STZ) model of diabetes has been reported to involve direct STZ beta-cytotoxicity and/or immunologically mediated beta-cell destruction. Because the T-lymphocyte dependency of such a model is controversial, we further assessed the role of T-lymphocytes by determining the occurrence and magnitude of hyperglycemia as well as the pancreatic insulin contents in both STZ-injected nude C57BL/6J male mice and STZ-injected euthymic C57BL/6J male mice selectively depleted in helper and/or cytotoxic T-lymphocytes with monoclonal antibodies (MoAbs). The effectiveness of MoAb treatment was assessed in lymph node cells by flow-microfluorometry analysis and in spleen cells by concanavalin A stimulation, allospecific cytotoxic T-lymphocyte activity, and T-lymphocyte lymphokine production. Sixteen days after the first STZ injection, hyperglycemia (plasma glucose greater than 200 mg/dl) occurred in significantly fewer helper T-lymphocyte-depleted mice (P less than .005) or helper and cytotoxic T-lymphocyte-depleted mice (P less than .001) than in non-MoAb-treated mice. However, a progressive increase in the number of mice with hyperglycemia ensued in all MoAb-treated groups, and 2 mo after STZ was administered, the prevalence of hyperglycemia, mean plasma glucose levels, and pancreatic insulin contents did not differ significantly from the values obtained in the non-MoAb-treated animals. Similarly, STZ-injected C57BL/6J male nude mice developed hyperglycemia that was associated with a marked decrease in pancreatic insulin contents on a time course comparable with that of STZ-injected euthymic C57BL/6J male mice depleted in helper or in helper and cytotoxic T-lymphocytes by MoAbs.(ABSTRACT TRUNCATED AT 250 WORDS)

Polymorphonuclear leucocyte dysfunction during short term metabolic changes from normo- to hyperglycemia in type 1 (insulin dependent) diabetic patients

Polymorphonuclear leucocyte (PMN) ingestion of particles coated with lipopolysaccharide (LPS) from Escherichia coli was compared to other PMN functions in seven patients with insulin dependent diabetes mellitus (IDDM) during short-term controlled metabolic changes from normo- to hyperglycemia without ketoacidosis. Factors known to interfere with PMN functions were excluded. PMN ingestion of particles coated with both LPS and bovine serum albumin became reduced from normo- to hyperglycemia. PMN motility was impaired in IDDM, but did not seem to be affected by short-term changes in metabolic control. PMN metabolism did not change from normo-to hyperglycemia. Particle-uptake by diabetic PMN is impaired after short term hyperglycemia in the range normally occurring in diabetics in every-day life.