Serum levels of interleukin-13 increase in subjects with insulin resistance but do not correlate with markers of low-grade systemic inflammation

Abstract

Experimental evidence in mice suggests a role for interleukin- (IL-) 13 in insulin resistance and low-grade systemic inflammation. However, IL-13 serum levels have not been assessed in subjects with insulin resistance, and associations of IL-13 with parameters of low-grade systemic inflammation are still unknown. Our main goal was to examine the systemic levels of IL-13 in patients with insulin resistance, while also studying the relationship of IL-13 with anthropometric, metabolic, and low-grade systemic inflammatory markers. Ninety-two participants were included in the study and divided into insulin-resistant patients and noninsulin-resistant controls. Blood levels of IL-13, glucose, insulin, triglycerides, cholesterol, tumor necrosis factor-alpha (TNF-α), IL-10, proinflammatory (Mon-CD11c+CD206−), and anti-inflammatory (Mon-CD11c−CD206+) monocytes, as well as anthropometric parameters, were measured in all volunteers. Insulin-resistant patients showed 2.5-fold higher serum levels of IL-13 than controls (P < 0 0001) and significantly increased values of TNF-α and Mon-CD11c+CD206−, with concomitant reductions in IL-10 and Mon-CD11c−CD206+. Increased IL-13 was extraordinarily well associated with hyperglycemia (r = 0 7362) and hypertriglyceridemia (r = 0 7632) but unexpectedly exhibited no significant correlations with TNF-α (r = 0 2907), IL-10 (r = −0 3882), Mon-CD11c+CD206− (r = 0 2745) or Mon-CD11c−CD206+ (r = −0 3237). This study demonstrates that IL-13 serum levels are elevated in patients with insulin resistance without showing correlation with parameters of low-grade systemic inflammation.