Increased proinflammatory markers and lipoperoxidation in obese individuals: Inicial inflammatory events?

Background: Chronic inflammation associated to obesity increases the risk for developing insulin resistance (IR), hyperglycemia, hypertension and hyperlipidemia. The initial factors involved in generating the inflammatory events in the obesity remain unclear. Therefore, this study was aimed to determine inflammatory and oxidative markers in the blood of obese individuals with normal clinical and biochemical parameters and with or without IR.

Methods: Nineteen obese non-diabetic and nine lean subjects were studied for serum levels of TNF-α, IL-1β, adiponectin, angiotensin II, insulin, malondialdehyde (MDA) and the expressions of RAGE (advanced glycation end product receptor), AT1 (Ang II receptor), s100A12 protein (RAGE ligand) and nuclear factor-κB (NF-κB) in circulating mononuclear cells (CMC) by available antibodies and commercial kits. CMC were also cultured to determine pro-inflammatory mediators.

Results: Insulin was increased in obese subjects with IR. Decreased serum adiponectin in obese individuals and increased TNF-α, IL-1β and CMC bearing RAGE, AT1 and s100A12 in obese individuals without IR were found. High values of serum MDA in obese subjects were observed. Similar TNF-content in cultures from obese and controls, increased cellular IL-1β content in cultures from obese individuals without IR and high content of MDA in supernatants from obese individual cultures were observed.

Conclusions: The inflammatory events were mainly observed in obese individuals without IR. The absent of inflammatory events and high levels of insulin in obese subjects with IR, suggest a protector role of insulin for developing inflammatory events. These data can represent initial aspects of the chronic inflammation observed in the obesity.