Effect of Liraglutide (Victoza) on Inflammation in Human Adipose Tissue and Blood

Overview

The objective of this study is to test the hypothesis that liraglutide (commonly known as Victoza) can promote an anti-inflammatory macrophage phenotype in human adipose tissue and blood, thereby reducing localized and systemic inflammation which are risk factors for cardiovascular disease and may contribute to hyperglycemia. This will be done after 4 weeks of treatment during which weight will remain stable, and again after 12 weeks, during which liraglutide-related weight loss occurs.

It has now been established that the high risk of cardiovascular disease that is associated with obesity and type 2 diabetes is related to the systemic inflammation that underlies these conditions. Previous studies have shown that there are numerous types of immune cells in human adipose tissue, some of these are the macrophages. These cells can exist in two states: M2, which can inhibit classical inflammatory response, and M1 which secrete proinflammatory cytokines. The investigators have data to suggest that the role of inflammatory cells in adipose tissue is a strong contributor to systemic inflammation. A recent study showed that a GLP-1 analog (liraglutide, also known as Victoza) may help decrease inflammation via promoting M2 differentiation of macrophages. The purpose of this study is to quantify macrophage phenotype (M1 vs M2) in subcutaneous adipose tissue in moderately-obese diet controlled diabetics at baseline, after four weeks of weight-maintenance using liraglutide, and after 12 weeks of liraglutide treatment as compared to placebo. Aim 1: Quantify M1 and M2 (surface and intracellular markers) polarization via flow cytometry in subcutaneous abdominal adipose tissue and peripheral blood mononuclear cells at baseline and after 4 weeks administration of liraglutide versus placebo to weight-stable, obese, type 2 diabetic patients. Weight loss will be prevented in order to ascertain the effect of liraglutide alone. Aim 2: Quantify M1 and M2 (surface and intracellular markers) polarization via flow cytometry in subcutaneous adipose tissue and peripheral blood mononuclear cells after 12 weeks of liraglutide treatment, during which dietary restrictions are lifted and spontaneous weight loss, as would occur in the clinical setting, is allowed. To eliminate confounding by weight loss, a placebo-treated group will undergo matched dietary weight loss for comparison to the liraglutide group to ascertain whether changes in macrophage polarization at 12 weeks are greater in the liraglutide group. Aim 3: Quantify macrophage-mediated localized and systemic inflammation by measuring M1/M2-related inflammatory cytokines in adipose tissue and peripheral blood after 4 and 12 weeks administration of liraglutide versus placebo to obese, type 2 diabetic patients.