Adiponectin is an adipose tissue-specific protein that is abundantly present in the circulation and suggested to be involved in insulin sensitivity and development of atherosclerosis. Because cytokines are suggested to regulate adiponectin, the aim of the present study was to investigate the interaction between adiponectin and three adipose tissue-derived cytokines (IL-6, IL-8, and TNF-α). The study was divided into three substudies as follows: 1) plasma adiponectin and mRNA levels in adipose tissue biopsies from obese subjects [mean body mass index (BMI): 39.7 kg/m², n = 6] before and after weight loss; 2) plasma adiponectin in obese men (mean BMI: 38.7 kg/m², n = 19) compared with lean men (mean BMI: 23.4 kg/m², n = 10) before and after weight loss; and 3) in vitro direct effects of IL-6, IL-8, and TNF-α on adiponectin mRNA levels in adipose tissue cultures. The results were that 1) weight loss resulted in a 51% ( P < 0.05) increase in plasma adiponectin and a 45% ( P < 0.05) increase in adipose tissue mRNA levels; 2) plasma adiponectin was 53% ( P < 0.01) higher in lean compared with obese men, and plasma adiponectin was inversely correlated with adiposity, insulin sensitivity, and IL-6; and 3) TNF-α ( P < 0.01) and IL-6 plus its soluble receptor ( P < 0.05) decreased adiponectin mRNA levels in vitro. The inverse relationship between plasma adiponectin and cytokines in vivo and the cytokine-induced reduction in adiponectin mRNA in vitro suggests that endogenous cytokines may inhibit adiponectin. This could be of importance for the association between cytokines (e.g., IL-6) and insulin resistance and atherosclerosis.

Background: The consumption of sucrose-sweetened soft drinks (SSSDs) has been associated with obesity, the metabolic syndrome, and cardiovascular dis

Human adipose tissue (AT) produces several adipokines including monocyte chemoattractant protein (MCP)-1, involved in the pathogenesis of atherosclerosis. Objective: Human AT cultures, isolated adipocytes, and stromal-vascular cells were used to investigate the relationship among AT-resident macrophages, MCP-1, and adiposity and the regulation of MCP-1. Results: mRNA levels of specific macrophage markers (CD68 and CD14) are correlated with adiposity in sc AT and visceral AT (P < 0.05). MCP-1 production is higher in stromal-vascular cells vs. adipocytes (P < 0.01) and correlates with macrophage markers in both AT compartments (P < 0.05). MCP-1 release is higher in obese subjects (P < 0.05) and in VAT (P < 0.01), but after adjusting for AT-resident macrophages, the differences disappear. MCP-1 is stimulated by IL-1β, TNF-α, IL-8, IL-4, and IL-6 + IL-6-soluble receptor and is decreased by dexamethasone, IL-10, metformin, and thiazolidinediones. Discussion: MCP-1 is correlated with specific macrophage markers, adiposity, and AT localization, but the relationship seems to be related to the number of AT-resident macrophages. Despite this, MCP-1 may be involved in obesity-related health complications, and the decrease of MCP-1 by metformin and thiazolidinediones suggests that these antidiabetic compounds have antiinflammatory properties improving the low-grade inflammatory state observed in obesity.

Obesity is associated with low-grade inflammation, insulin resistance, type 2 diabetes, and cardiovascular disease. This study investigated the effect of a 15-wk lifestyle intervention (hypocaloric diet and daily exercise) on inflammatory markers in plasma, adipose tissue (AT), and skeletal muscle (SM) in 27 severely obese subjects (mean body mass index: 45.8 kg/m²). Plasma samples, subcutaneous abdominal AT biopsies, and vastus lateralis SM biopsies were obtained before and after the intervention and analyzed by ELISA and RT-PCR. The intervention reduced body weight ( P < 0.001) and increased insulin sensitivity (homeostasis model assessment; P < 0.05). Plasma adiponectin ( P < 0.001) increased, and C-reactive protein ( P < 0.05), IL-6 ( P < 0.01), IL-8 ( P < 0.05), and monocyte chemoattractant protein-1 ( P < 0.01) decreased. AT inflammation was reduced, determined from an increased mRNA expression of adiponectin ( P < 0.001) and a decreased expression of macrophage-specific markers (CD14, CD68), IL-6, IL-8, and tumor necrosis factor-α ( P < 0.01). After adjusting for macrophage infiltration in AT, only IL-6 mRNA was decreased ( P < 0.05). Only very low levels of inflammatory markers were found in SM. The intervention had no effect on adiponectin receptor 1 and 2 mRNA in AT or SM. Thus hypocaloric diet and increased physical activity improved insulin sensitivity and reduced low-grade inflammation. Markers of inflammation were particularly reduced in AT, whereas SM does not contribute to this attenuation of whole body inflammation.