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Circulating tumor necrosis factor alpha is higher in non-obese, non-diabetic Mexican Americans compared to non-Hispanic white adults

Abstract:

Mexican Americans (MA) exhibit high risk for the insulin resistance syndrome characterized by subclinical inflammation and greater risk for type 2 diabetes compared with non-Hispanic white (NHW) adults. The reasons for this phenomenon remain obscure. Because the inflammatory cytokine, tumor necrosis factor-alpha (TNFα), is associated with insulin resistance in various models of obesity and diabetes, we sought to determine whether circulating concentrations of this cytokine and its soluble receptors are higher in MA than NHW, and also to determine if the TNFα system is related to the lower insulin sensitivity in MA. Fasting blood samples were used to determine concentrations of TNFα, soluble TNF receptors 1 (sTNFR1) and 2 (sTNFR2) in the same 13 MA (7 women, 6 men, age=27.0±2.0 years, BMI=23.0±0.7) and 13 NHW (7 women, 6 men, age=24.8±1.5 years, BMI=22.8±0.6) previously shown to exhibit differences in insulin sensitivity. Circulating TNFα was significantly higher (3.11±0.38 vs. 2.10±0.24 pg/ml, p<0.05) and sTNFR2 was significantly lower (1324±85 vs. 1925±127 pg/ml, p<0.05) among MA compared with NHW subjects. Soluble TNFR1 was not different between groups (MA: 970±111 pg/ml vs. NHW: 1218±73 pg/ml, p=0.07). TNFα, sTNFR1 and sTNFR2 were not correlated with HOMA-IR when the two groups were analyzed in aggregate. This study documents higher circulating TNFα concentrations in non-obese, non-diabetic MA, a population group at increased risk for the metabolic syndrome and the untoward effects of sub-clinical inflammation. The clinical implications of this difference, if any, are not yet known. © 2005 Elsevier Ltd. All rights reserved.