School of Medicine

Chronic low-grade inflammation is associated with metabolic syndrome and insulin resistance, which is the primary defect leading to type 2 diabetes mellitus. In humans, dietary interventions have been shown to increase insulin sensitivity, with one of the hypothesized mechanisms being reduced activation of pathways that promote chronic inflammation. The objective of this study was to analyze pro-inflammatory gene expression in CD14+ circulating monocytes from metabolic syndrome subjects before, during, and after two diet interventions. The study was a randomized, single-blind, controlled trial of a 12-week long, 1500 calorie diet. The active diet included low glycemic index bread products, EPA/DHA fish oil capsules (2.4g EPA+DHA/day), and delphinidin polyphenol capsules (300 mg, 10,000 ORAC units/day). The placebo diet included market variety bread products, corn oil capsules, and corn starch capsules. We hypothesized that the active dietary components would act synergistically to significantly improve the inflammatory gene expression profile of the subjects as compared to placebo diet. Baseline, midpoint, and endpoint mRNA expression profiles from monocyte RNA samples were assessed for 30 obese subjects. Post-hoc analysis of real-time quantitative polymerase chain reaction (RT-qPCR) results to measure the expression levels of twelve inflammatory marker genes of interest revealed significant reduction in toll-like receptor 2 (TLR2), CD11c, and tumor necrosis factor alpha (TNFα) expression in circulating monocytes of active group as compared to the placebo group, P<.05. This study was part of a parent clinical trial showing that average fasting insulin and HOMA-IR improved significantly in the active group but not the placebo group. This monocyte gene expression data will contribute to painting the picture of how the composition of a low calorie diet modulates inflammation and insulin sensitivity.