Toll-like receptor signaling and serum levels of interferon β and lipopolysaccharide binding protein are related to abdominal obesity: a case-control study between metabolically healthy and metabolically unhealthy obese individuals

Abstract

It is still unclear whether toll-like receptor (TLR) signaling and serum levels of inflammatory markers in metabolically unhealthy abdominally obese (MUAO) are due to their obesity and/or their metabolic state. We hypothesized that abdominal obesity is an important mediator of the association of metabolic state with TLR signaling and serum inflammatory markers. Therefore, in this case-control study, we compared the expression levels of TLR4 and Toll/interleukin-1 receptor domain containing adaptor protein-inducing interferon β (TRIF) and serum concentrations of interferon β and lipoprotein-binding protein (LBP) in metabolically healthy abdominally obese (MHAO) and MUAO individuals. Basal blood samples from 65 abdominally obese subjects with waist circumference (WC) of at least 95 cm were collected to determine serum metabolic parameters, IFNβ, and LBP. Those with 3 or more metabolic alterations were defined as MUAO (n = 34), and those having 2 or less were classified as MHAO (n = 31). Furthermore, messenger RNA (mRNA) was isolated from peripheral blood mononuclear cells. TLR4 and TRIF gene expression assay was performed using quantitative real-time polymerase chain reaction. There were significant differences in serum fasting blood sugar (P = .017), triglyceride (P < .001), cholesterol (P = .002), and lowdensity lipoprotein cholesterol (P = .034) between the MUAO and MHAO groups, whereas no Keywords: Toll-like receptor 4 Toll/interleukin-1 receptor domain containing adaptor proteininducing interferon Interferon β Abdominal obesity Metabolic health NUTRITION RESEARCH 55 (2018) 11 – 2 0 Abbreviations: BMI, body mass index; BP, blood pressure; CRP, C-reactive protein; FBS, fasting blood sugar; HDL-C, high-density lipoprotein cholesterol; IFNs, Interferons; IFNβ, interferon β; ILs, interleukins; LBP, lipopolysaccharide-binding protein; LPS, Lipopolysaccharide; LBP, lipopolysaccharide-binding protein; MetS, metabolic syndrome; MHAO, metabolically healthy abdominally obese; MUAO, metabolically unhealthy abdominally obese; PA, physical activity; PBMCs, peripheral blood mononuclear cells; TG, triglyceride; TLRs, toll-like receptors; TNF-α, tumor necrosis factor α; TRIF, Toll/IL-1 receptor domain containing adaptor protein-inducing interferon β; WC, waist circumference