Macrophages, cytokines and β-cell death in Type 2 diabetes

The pathology of islets from patients with Type 2 diabetes displays an inflammatory process characterized by the presence of immune cell infiltration, cytokines, apoptotic cells, amyloid deposits and, eventually, fibrosis. Indeed, analysis of β-cells from patients with Type 2 diabetes displays increased IL-1β (interleukin 1β) expression. Furthermore, increased islet-associated macrophages are observed in human Type 2 diabetic patients and in most animal models of diabetes. Importantly, increased numbers of macrophages are detectable very early in high-fat-fed mice islets, before the onset of diabetes. These immune cells are probably attracted by islet-derived chemokines, produced in response to metabolic stress, and under the control of IL-1β. It follows that modulation of intra-islet inflammatory mediators, particularly interleukin-1β, may prevent islet inflammation in Type 2 diabetes and therefore presents itself as a promising therapeutic approach.