Effects of balloon injury on neointimal hyperplasia in steptozotocin-induced diabetes and in hyperinsulinemic nondiabetic pancreatic islet-transplanted rats.

BACKGROUND: The mechanisms of increased neointimal hyperplasia after coronary interventions in diabetic patients are still unknown. METHODS AND RESULTS: Glucose and insulin effects on in vitro vascular smooth muscle cell (VSMC) proliferation and migration were assessed. The effect of balloon injury on neointimal hyperplasia was studied in streptozotocin-induced diabetic rats with or without adjunct insulin therapy. To study the effect of balloon injury in nondiabetic rats with hyperinsulinemia, pancreatic islets were transplanted under the kidney capsule in normal rats. Glucose did not increase VSMC proliferation and migration in vitro. In contrast, insulin induced a significant increase in VSMC proliferation and migration in cell cultures. Furthermore, in VSMC culture, insulin increased MAPK activation. A reduction in neointimal hyperplasia was consistently documented after vascular injury in hyperglycemic streptozotocin-induced diabetic rats. Insulin therapy significantly increased neointimal hyperplasia in these rats. This effect of hyperinsulinemia was totally abolished by transfection on the arterial wall of the N17H-ras-negative mutant gene. Finally, after experimental balloon angioplasty in hyperinsulinemic nondiabetic islet-transplanted rats, a significant increase in neointimal hyperplasia was observed. CONCLUSIONS: In rats with streptozotocin-induced diabetes, balloon injury was not associated with an increase in neointimal formation. Exogenous insulin administration in diabetic rats and islet transplantation in nondiabetic rats increased both blood insulin levels and neointimal hyperplasia after balloon injury. Hyperinsulinemia through activation of the ras/MAPK pathway, rather than hyperglycemia per se, seems to be of crucial importance in determining the exaggerated neointimal hyperplasia after balloon angioplasty in diabetic animals

Alpha-Lipoic Acid for the Prevention of Diabetic Macular Edema

Introduction: To evaluate the effect of alpha-lipoic acid (ALA) on the occurrence of diabetic macular edema. Methods: Randomized, double-blind, placebo-controlled, multicenter, multinational study. Patients were randomized to the treatment group with 600 mg ALA per day or the placebo group. Every 6 months stereo fundus photographs, HbA1c levels, and an ophthalmological examination were documented. The primary endpoint was the occurrence of clinically significant macular edema (CSME) within a follow-up period of 2 years. Results: We randomized 235 patients with type II diabetes mellitus into the treatment group (mean age 58.0 years) and 232 into the placebo group (mean age 57.9 years). Mean HbA1c level was 8.1, with no significant differences between the treatment (mean 8.2, SD +/- 1.35) and placebo groups (mean 8.1, SD +/- 1.29). HbA1c values remained constant over time. In the treatment and placebo groups, 84 and 86 patients (35.7 and 37.1%) had insulin-dependent diabetes mellitus (IDDM) with a median duration of diabetes of 9.3 versus 9.0 years in the placebo group. Visual acuity remained unchanged during the entire trial. Concerning the primary endpoint, the study provided a negative result, i.e. 26/235 patients in the treatment group and 30/232 patients in the placebo group developed CSME. Confirmatory intention-to-treat analysis of the primary endpoint revealed no statistically significant difference between groups (log-rank test, p = 0.7108, HR = 0.9057 with CI = 0.5355-1.5317). Median follow-up was identical (2.00 years). Conclusions: A daily dosage of 600 mg ALA does not prevent the occurrence of CSME in IDDM patients. Copyright (C) 2011 S. Karger AG, Base

Insulin-Like Growth Factor (IGF)-I and -11 and IGFBinding Proteins-l, -2, and -3 in Children and Adolescents with Diabetes Mellitus: Correlation with Metabolic Control and Height Attainment.

The putative effects of diabetes and metabolic control on circulating levels of insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) remain controversial. In the present study, serum levels of IGF-I and IGF-II and IGFBP-1, -2, and -3 were measured in 58 patients (age, 0.8-17 yr) with treated (51 subjects) or untreated (7 subjects) insulin-dependent diabetes mellitus (IDDM) and were compared with the levels in normal subjects. In the untreated patients IGF-I and IGF-II were decreased as compared with the healthy controls. In the treated diabetics IGF-I and IGF-II were reduced; IGFBP-2 (only in prepubertal subjects) and IGFBP-3 were increased. Furthermore, age-adjusted values of IGF-I, IGF-II, and IGFBP-3 were lower in prepubertal than in pubertal patients. Regression analysis revealed a negative correlation between hemoglobin (Hb)A1c and standard deviation scores (SDS) of IGF-I and a positive association between HbA1c and IGFBP-1 SDS or IGFBP-2 SDS. In the treated patients HbA1c was positively related to IGFBP-1 SDS and IGFBP-2 SDS when applying simple regression analysis and to IGFBP-2 SDS when using a multiple regression model. Strong correlations were observed between height SDS and IGF-I SDS, IGF-II SDS, and IGFBP-3 SDS in prepubertal subjects who had had IDDM for at least 2 yr, but not in adolescents. Such correlations have also been found in healthy children and adolescents. In conclusion; 1) IDDM is associated with alterations of the IGF-IGFBP system, which are partially accounted for by differences in metabolic control and pubertal status; 2) the lower plasma concentrations of serum IGF-I may play a role in the pathogenesis of growth impairment of poorly controlled prepubertal, but not pubertal, children and adolescents with IDDM; and 3) in addition, a potential role of the altered IGF-IGFBP system for the development of diabetic late complications is hypothesized

Cytoplasmic islet cell antibodies recognize distinct islet antigens in IDDM but not in stiff man syndrome

Cytoplasmic islet cell antibodies are well-established predictive markers of IDDM. Although target molecules of ICA have been suggested to be gangliosides, human monoclonal ICA of the immunoglobulin G class (MICA 1-6) produced from a patient with newly diagnosed IDDM recognized glutamate decarboxylase as a target antigen. Here we analyzed the possible heterogeneity of target antigens of ICA by subtracting the GAD-specific ICA staining from total ICA staining of sera. This was achieved 1) by preabsorption of ICA+ sera with recombinant GAD65 and/or GAD67 expressed in a baculovirus system and 2) by ICA analysis of sera on mouse pancreas, as GAD antibodies do not stain mouse islets in the immunofluorescence test. We show that 24 of 25 sera from newly diagnosed patients with IDDM recognize islet antigens besides GAD. In contrast, GAD was the only islet antigen recognized by ICA from 7 sera from patients with stiff man syndrome. Two of these sera, however, recognized antigens besides GAD in Purkinje cells. In patients with IDDM, non-GAD ICA were diverse. One group, found in 64% of the sera, stained human and mouse islets, whereas the other group of non-GAD ICA was human specific. Therefore, mouse islets distinguish two groups of non-GAD ICA and lack additional target epitopes of ICA besides GAD. Longitudinal analysis of 6 sera from nondiabetic ICA+ individuals revealed that mouse-reactive ICA may appear closer to clinical onset of IDDM in some individuals

Disassociation between glomerular hyperfiltration and extracellular volume in diabetic rats

Disassociation between glomerular hyperfiltration and extracellular volume in diabetic rats. The relationship of the development of glomerular hyperfiltration in diabetes to changes in extracellular fluid volume has not been previously examined. To accomplish this task, male Wistar rats were chronically cannulated in the bladder, femoral artery and vein. Control measurements of glomerular filtration rate (GFR), renal plasma flow (RPF), extracellular fluid volume (ECF), and urinary sodium excretion were performed on two separate days prior to infusion of streptozotocin (65 mg/kg body wt i.v.). After infusion of streptozotocin, the IDDM rats were separated into two groups: untreated IDDM group of rats and IDDM rats treated with insulin at doses sufficient to normalize blood glucose (Ultralente, 2 to 8 IU/day). A third group of normal non-diabetic rats served as time controls. Measurements of renal function occurred at 1, 4, 7, 11, and 15 days after infusion of streptozotocin. Blood glucose in the non-diabetic measurement period averaged 137 ± 30 mg/dl and increased from 412 ± 55 after 24 hours in the untreated diabetic rats to 533 ± 33 mg/dl after 15 days of IDDM. The time controls and the insulin-treated diabetic rats did not differ in blood glucose values at the time measurements were performed. Glomerular filtration rate increased from 1.0 ± 0.1 to 1.7 ± 0.1 ml/min/100g body wt by day 15 in the untreated diabetic rats with significant increases in GFR within 24 hours. GFR of both time controls and the insulin-treated IDDM rats did not significantly vary during the time of the study. The increase in GFR in the untreated IDDM group was associated with a concomitant increase in RPF. However, ECF decreased in both the insulin treated and untreated groups by one day after streptozotocin infusion and was less than control throughout the 15 day IDDM measurement period. Therefore, the data indicate that the development of hyperfiltration in IDDM is not caused by ECF expansion and cannot be temporally linked to changes in ECF

An immunomodulating mycotoxin interferes with the development of autoimmune diabetes in diabetes-prone BB/Wor rats

Various fungal products have immunomodulating activity and some have been studied regarding prevention of transplantation rejection. Prior to this investigation, the mycotoxin, gliotoxin (GT), has never been investigated as an immunotherapeutic drug for autoimmune disease. GT is a fungal secondary metabolite and a member of the epipolythiodioxopiperazine (ETP) family which has been shown to inhibit phagocytosis, induction of cytolytic T cells and the proliferation of T cells following mitogen stimulation. GT also induces in vitro apoptosis in certain immune cell types. More importantly, GT exhibits selective activity towards cells of hemopoietic origin. Autoimmune diseases are disorders caused by immune responses to self antigens. Insulin dependent diabetes mellitus (IDDM) is an organ-specific autoimmune disease in which insulin secreting pancreatic islet β-cells are destroyed leading to hyperglycemia, ketoacidosis and various systemic complications. Because of its potential effects on the immune system, we evaluated GT for its ability to prevent IDDM. This study is the first to successfully use GT to prevent an autoimmune process. GT prevented IDDM in spontaneously diabetic DP/BB rats without causing significant adverse effects among the treated animals. GT treated rats developed diabetes at a rate of 55% by 120 days of age compared to 90% for control rats. GT treatment also significantly decreased serum glucose levels from an average 278 mg/dl to 185.67 mg/dl among non-diabetic/pre-diabetic animals. A series of studies was conducted on 65 days old DP/BB rats, prior to development of diabetes to phenotypically characterize the splenic lymphocytes recovered from animals chronically treated with GT. A parallel study examined the direct effects of GT on splenocyte preparations incubated with this mycotoxin. This study found that GT selectively affects certain lymphocyte subsets. Animals treated with GT showed involution of splenic follicles and several effects on lymphocyte subpopulations were found. In vitro treatment of splenocytes with GT revealed decreased CD4+ and increased CD8+ T cell subsets. CD8+ T cells function as an important regulator of autoimmunity, especially influencing the activity of CD4+ T cells. GT effects on CD4+ and CD8+ T cells are consistent with changes anticipated to inhibit IDDM pathogenesis. In vivo treatment with GT did not result in detectable alterations in relative CD4+ and CD8+ cell subsets, although this may have been more related to pharmacologic reasons than the physiological effects of GT. Importantly, this study found that both in vitro and in vivo GT treatments significantly enhanced the detectable RT6 surface marker. The RT6+ T cell subset is a key regulatory element in IDDM pathogenesis. Increased numbers of RT6 surface markers may be involved with IDDM prevention or may be a result of it. GT induced lymphocyte apoptosis among spleen cells from DP/BB rats was altered in vitro. The average increase in apoptotic cells due to GT treatment was nearly four fold. Results from this study suggested that the mechanism whereby GT prevents IDDM in DP/BB rats is through apoptosis. Coupled with the finding of altered lymphocyte populations, it may be suggested that apoptosis of regulatory cells, or effector cells is involved in diabetes prevention in this system. The finding that CD8+ cells and NK cells which include cytotoxic effectors that can promote pancreatic damage, were not decreased by GT treatment suggests that the effects may reside with regulatory cells rather than with effectors, although additional study is warranted to fully understand this process. This research is the first to show that GT has a protective effect against an autoimmune disease. We also found that GT is a selective immunomodulator altering the ratio of CD4+ and CD8+ lymphocytes and causing increased RT6+ surface marker to appear as an important subset of lymphocytes. This study is also the first to demonstrate that apoptosis due to GT treatment occurs in intact animals. Because indicators of systemic toxicity showed that GT is relatively benign in experimental animals, as evidenced by lack of irreversible histopathology, normal weight gain and normal leukocyte counts, and it has a beneficial effect on IDDM development, GT should be considered for continued evaluation as a potential IDDM preventive drug