Aims: Infection with specific pathogens may lead to increased adiposity. The human adenovirus 36 (Ad36) is a relatively new factor in promoting adipogenesis. It seems to improve the metabolic profile, expanding adipose tissue and enhancing insulin sensitivity in animal models. The aim of this study was to investigate whether any association or predictor effect of Ad36 seropositivity is present in non-alcoholic fatty liver disease (NAFLD), a condition associated with obesity and insulin resistance (IR).
Methods: Sixty-five NAFLD patients and 114 controls were investigated. Ultrasound bright liver score (BLS), body composition, IR evaluated by homeostasis model assessment of insulin resistance index (HOMA or HOMA-IR) and serum neutralization assay for antibodies to Ad36 were assessed.
Results: Ad36-seropositive patients have a lower risk of bright liver [OR 0.505 (95% confidence interval (CI) 0.265-0.962)]; greater IR leads to a higher risk of bright liver [OR 9.673 (95% CI 4.443-21.058)]. Among NAFLD, Ad36-seropositive vs. Ad36-seronegative patients did not show a significant IR difference. Ad36-seropositive NAFLD patients, with the same levels of HOMA and BLS, had greater body mass index and body fat mass, in comparison with seronegative NAFLD patients. By a multiple linear regression model, BLS was explained by HOMA (beta 0.513; P<0.0001), high density lipoprotein cholesterol (beta-0.219, P<0.006) and Ad36 seropositivity (beta-0.202, P<0.005); Ad36 seropositivity did not explain HOMA in the other multiple logistic regression model.
Conclusions: Ad36 seropositivity is not associated with a significant difference of IR in NAFLD patients, but is associated with a greater adiposity. Ad36 seropositivity is associated with a lower occurrence of NAFLD and bright liver, which, conceivably, is not directly mediated by IR.