Severity of non-alcoholic steatohepatitis is associated with substitution of adipose tissue in skeletal muscle

Background and Aims: The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is now focusing on its organ cross-talk with not only adipose tissue but also systemic skeletal muscle. Cross-sectional and longitudinal studies were conducted to determine the role of intramuscular adipose tissue content (IMAC) measured by computed tomography on the severity of NAFLD/non-alcoholic steatohepatitis (NASH). Methods: Two hundred eight Japanese patients with NAFLD/NASH diagnosed by liver biopsy were enrolled into a cross-sectional study. Twenty-one patients were enrolled in a longitudinal study and received a programmed diet and exercise intervention, in some cases the combination of pharmacotherapy. We measured IMAC in the multifidus muscle and biochemical parameters, and conducted liver histology to assess NAFLD/NASH status. Results: Histopathological stage in terms of simple steatosis and Brunt's classification was significantly correlated with IMAC (P < 0.01). Multivariate logistic regression analysis indicated that risk factors associated with the severity of NASH were IMAC and aging (IMAC: odds ratio = 2.444, P < 0.05; Age: odds ratio = 2.355, P < 0.05). The interventions improved histopathological changes in 11 patients with NASH as well as IMAC. Conclusion: These results suggest that skeletal muscle fat accumulation may have been linked to the pathogenesis and severity of NASH.