The Roles of IL-6, IL-10, and IL-1RA in Obesity and Insulin Resistance in African-Americans

• Published in: The journal of clinical endocrinology and metabolism Vol. 96; no. 12; pp. E2018 - E2022
• Main Authors: Charles, Bashira A, Doumatey, Ayo, Huang, Hanxia, Zhou, Jie, Chen, Guanjie, Shriner, Daniel, Adeyemo, Adebowale, Rotimi, Charles N
• Format: Journal Article
• Language: English
• Published: United States Endocrine Society 01-12-2011; Copyright by The Endocrine Society
• Subjects: Adult; African Americans; Analysis; Blood; Computers; Evaluation; Family; Female; Hips; Hormones; Humans; Insulin Resistance; Interleukin 1 Receptor Antagonist Protein - blood; Interleukin-10 - blood; Interleukin-6 - blood; JCEM Online: Brief Reports; Male; Middle Aged; Obesity; Obesity - immunology; Research (statistical design)
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2011-1497

Objective:
The aim of the study was to investigate the associations between IL-1 receptor antagonist (IL-1RA), IL-6, IL-10, measures of obesity, and insulin resistance in African-Americans.
Research Design and Methods:
Nondiabetic participants (n = 1025) of the Howard University Family Study were investigated for associations between serum IL (IL-1RA, IL-6, IL-10), measures of obesity, and insulin resistance, with adjustment for age and sex. Measures of obesity included body mass index, waist circumference, hip circumference, waist-to-hip ratio, and percent fat mass. Insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR). Data were analyzed with R statistical software using linear regression and likelihood ratio tests.
Results:
IL-1RA and IL-6 were associated with measures of obesity and insulin resistance, explaining 4–12.7% of the variance observed (P values < 0.001). IL-1RA was bimodally distributed and therefore was analyzed based on grouping those with low vs. high IL-1RA levels. High IL-1RA explained up to 20 and 12% of the variance in measures of obesity and HOMA-IR, respectively. Among the IL, only high IL-1RA improved the fit of models regressing HOMA-IR on measures of obesity. In contrast, all measures of obesity improved the fit of models regressing HOMA-IR on IL. IL-10 was not associated with obesity measures or HOMA-IR.
Conclusions:
High IL-1RA levels and obesity measures are associated with HOMA-IR in this population-based sample of African-Americans. The results suggest that obesity and increased levels of IL-1RA both contribute to the development of insulin resistance.