The crosstalk between insulin resistance, systemic inflammation, redox imbalance and the thyroid in subjects with obesity

Abstract

We aimed at assessing the interaction between visceral adipose tissue (VAT), insulin resistance (IR), circulating levels of monocyte chemoattractant protein-1 (MCP-1) and malondialdehyde (MDA) and the thyroid parameters in obese subjects. Methods. Obese subjects without thyroid pathologies or diseases associated with systemic inflammation and OS were recruited. Insulinemia, visceral fat thickness, metabolic and thyroid parameters were assayed. Circulating levels of MCP-1 and MDA were used to quantify inflammation and OS. Results. A number of 160 obese subjects were included. The MCP-1 level increased with the degree of obesity and HOMA-IR. MCP 1 was positively associated with antithyroperoxidase antibody (TPOab) levels and the frequency of Hashimoto’s thyroiditis (HT). The MDA level was positively correlated with the degree of obesity, aspartate aminotransferase and MCP-1. MDA was an independent predictor for the occurrence of hypothyroidism. IR patients showed higher fT3 levels and a positive association between insulin and TPOab levels. Conclusions. Systemic inflammation increased with VAT, IR and OS and was correlated with the frequency and the severity of HT, suggesting that, in obesity, MCP-1 could be part of the etiopathogenesis of autoimmune thyroiditis. MDA was an independent risk factor for hypothyroidism; therefore, redox imbalance associated with obesity can produce cell damage and thyroid dysfunction. FT3 is increased in IR patients, thus being a marker for the severity of metabolic impairment.