Dietary polyherbal supplementation decreases CD3+ cell infiltration into pancreatic islets and prevents hyperglycemia in nonobese diabetic mice

Type 1 diabetes mellitus results from autoimmune-mediated destruction of pancreatic islet β-cells, a process associated with inflammatory signals. We hypothesized that dietary supplementation with botanicals known to contain anti-inflammatory properties would prevent losses in functional β-cell mass in nonobese diabetic (NOD) mice, a rodent model of autoimmune-mediated islet inflammation that spontaneously develops diabetes. Female NOD mice, a model of spontaneous autoimmune diabetes, were fed a diet supplemented with herbal extracts (1.916 g total botanical extracts per 1 kg of diet) over a 12-week period. The mice consumed isocaloric matched diets without (controls) and with polyherbal supplementation (PHS) ad libitum starting at a prediabetic stage (age 6 weeks) for 12 weeks. Control mice developed hyperglycemia (>180 mg/dL) within 16 weeks (n = 9). By contrast, mice receiving the PHS diet did not develop hyperglycemia by 18 weeks (n = 8). Insulin-positive cell mass within pancreatic islets was 31.9% greater in PHS mice relative to controls. We also detected a 26% decrease in CD3+ lymphocytic infiltration in PHS mice relative to mice consuming a control diet. In vitro assays revealed reduced β-cell expression of the chemokines CCL2 and CXCL10 after overnight PHS addition to the culture media. We conclude that dietary PHS delays initiation of autoimmune-mediated β-cell destruction and subsequent onset of diabetes mellitus by diminishing islet inflammatory responses.