Pioglitazone inhibits the expression of inflammatory cytokines from both monocytes and lymphocytes in patients with impaired glucose tolerance

Objective - The current study determines whether pioglitazone (PIO) therapy reduces both monocyte and lymphocyte inflammatory activity and their ability to induce inflammation in other tissues. Methods and Results - Monocyte and lymphocyte cytokine gene and protein expression of interleukin (IL)-6 were first shown to be greater in subjects with impaired glucose tolerance (IGT) than in subjects with normal glucose tolerance. Sixty-six IGT subjects were then randomized to 4,5 months of placebo or PIO therapy. After receiving PIO, subjects had lower triglycerides and higher HDL cholesterol (P<0.05) than did subjects receiving placebo. Monocyte gene and protein expression of IL-1β, IL-6, and IL-8 (and IL-2, IL-6 and IL-8 from lymphocytes) was significantly lower after PIO therapy in the resting state, as well as after lipopolysaccharide (LPS) stimulation (P<0.05 for all). Moreover, IL-6, IL-8, and MCP-1 gene expression were decreased by nearly 50% in human adipocytes exposed to conditioned media from monocytes or lymphocytes from PIO treated subjects. Conclusion - These results demonstrate that PIO therapy in IGT can reduce proinflammatory gene and protein expression from both monocytes and lymphocytes. This intervention also reduces the inflammatory cross-talk between these immune cells and adipose tissue, which could in turn contribute to the metabolic improvements resulting from PIO therapy.