Increased Plasma Levels of Asymmetric Dimethylarginine in Nonalcoholic Fatty Liver Disease: Relation With Insulin Resistance, Inflammation, and Liver Histology

Background and Aim Cardiovascular disease (CVD) is the most frequent cause of death in nonalcoholic fatty liver disease (NAFLD). Insulin resistance, hepatic dysfunction, and chronic inflammation are factors interacting in explaining the increased CVD incidence in NAFLD. We aimed to evaluate the effects of insulin resistance and inflammatory biomarkers on asymmetric dimethylarginine (ADMA) levels, a predictor of CVD. We also investigated relationship between these markers and histological findings in patients with NAFLD. Patients and Methods Plasma ADMA, high-sensitivity C-reactive protein (hs-CRP), interleukin 6 (IL-6), and homeostasis model assessment of insulin resistance (HOMA-IR) were measured in 70 patients with histologically verified NAFLD (53 with nonalcoholic steatohepatitis [NASH], 17 with non-NASH) and 12 controls. Results The HOMA-IR (5.3 [3.9] vs 1.9 [1], P < 0.001), hs-CRP (5.6 [4.2] vs 2.2 [2.3] mg/L, P < 0.001), ADMA (0.81 [0.25] vs 0.48 [0.24] mol/L, P = 0.005), and IL-6 (4.1 [1.2] vs 1.0 [0.4] pg/mL, P < 0.001) levels were all found higher in the NAFLD group than the control group. The ADMA levels were significantly higher in patients with NAFLD independent from HOMA-IR and body composition (P = 0.02). The IL-6 and HOMA-IR levels of the NASH group were found significantly higher than those of the non-NASH group. The only determinant significantly correlated to ADMA was HOMA-IR. Conclusions Our data suggested that although ADMA levels are independently higher in NAFLD, the only determinant correlated to ADMA is HOMA-IR and not inflammatory biomarkers (hs-CRP, IL-6) or presence/absence of NASH.