Lipopolysaccharide-binding Protein And Leptin Are Associated With Stress-induced Interleukin-6 Cytokine Expression Ex Vivo In Obesity

Abstract

Obesity is associated with enhanced inflammation and mental stress, but limited information has addressed the potential additive effect of psychological stress on obesity-associated inflammation. PURPOSE: The purpose of this study was to examine whether obese subjects would elicit a greater host immune response (IL-6 mRNA and cytokine expression) to lipopolysaccharide (LPS) in response to acute mental stress. METHODS: Twenty healthy male subjects (10 obese [age 28.13 ± 2.24 yrs] and 10 normal-weight [24.02 ± 1.50 yrs]) were recruited to participate in a 20 min bout of acute mental stress. Blood samples for LPS-stimulated IL-6 cytokine and mRNA determinations were collected prior to, immediately after, and one hour after stress. RESULTS: We demonstrated that whole blood cells from obese subjects elicited a greater concentration of LPS-induced IL-6 cytokine (p = 0.036) in conjunction with its mRNA expression (p < 0.001) following acute mental stress compared to the cells of the normal-weight subjects. Furthermore, stress-induced IL-6 cytokine response to LPS ex vivo was correlated with the baseline levels of plasma LPS binding protein (LBP) (r = 0.541, p = 0.014) and leptin (r = 0.554, p = 0.010). CONCLUSION: These findings are consistent with the idea that endogenous inflammatory agents (e.g., LBP and leptin), often elevated with obesity, enhance inflammatory responses to psychological stress.