Proinflammatory cytokines IL-6 and TNF-α and the development of inflammation in obese subjects

Abstract

Background: The development of obesity and related disorders, e.g., type II diabetes (T2D), hypertension, and metabolic disturbances is strongly related to increased levels in proinflammatory cytokines (IL-1, IL-6, and TNF-α). Both IL-6 and TNF-α are secreted by adipocytes and their concentration correlates with the percentage and distribution of fat tissue in the body. Both cytokines are the main factors responsible for the induction of acute phase proteins production (e.g., CRP) and to inflammatory state. Objective: To compare of TNF-α and IL-6 concentrations in serum from obese subjects with those in subjects with normal BMI and to analyze the relation between TNF-α, IL-6, BMI and the inflammatory state as measured by the level of CRP. Material and methods: The study included 80 obese subject (54 males and 26 females) BMI > 25 kg/m2. A control group consisted of 53 healthy subjects (24 males and 29 females) with BMI < 25 kg/m2. To determine the blood plasma concentration of IL-6 and TNF, commercial ELISA assay kits were used. Results: The concentration of IL-6 was lower in the control compared with the obese patients, but a significance difference concerned only female subjects (P = 0.001). TNF-α concentration was significantly higher in all obese subjects (P < 0.001). A higher level of this cytokine was also found in patients with obesity suffering from T2DM. A positive correlation was present between IL-6 and TNF-α concentrations. Only did the IL-6 level correlate with the concentration of CRP in serum. Conclusions: The study confirmed that increased inflammatory cytokines lead to the persistence of inflammation in obese subjects. However, some other factors, such as gender, may contribute to the development of obesity-related inflammatory states.