Mukitake mushroom (Panellus serotinus) alleviates nonalcoholic fatty liver disease through the suppression of monocyte chemoattractant protein 1 production in db/db mice

Nonalcoholic fatty liver disease (NAFLD) is emerging as the most common liver disease in industrialized countries. Thus, the discovery of food components that would ameliorate NAFLD is of interest. Various mushrooms have been used in folk medicine for the treatment of lifestyle diseases in eastern countries and several compounds that modulate immune system, lower blood lipid levels, inhibit tumor and viral action have been isolated from them. In this study, we tested whether feeding Panellus serotinus (Mukitake) to db/db mice protects them from hepatic injury. After 4 weeks of feeding, hepatomegaly, hepatic triglyceride accumulation and elevated hepatic injury markers in serum were markedly alleviated in Mukitake-fed db/db mice compared with control mice. These effects were partly attributable to the enhancement of lipolytic enzyme activity and the suppression of lipogenic enzyme activities due to the Mukitake diet. The severe hyperinsulinemia in control db/db mice tended to attenuate in Mukitake-fed mice due to an enhanced production of adiponectin, which improves insulin sensitivity. Moreover, production of monocyte chemoattractant protein 1 (MCP1), an inflammatory cytokine, was markedly suppressed by the Mukitake diet. In addition, water-soluble extracts of Mukitake powder showed an inhibitory effect on inhibitor of κB (IκB) kinase (IKK) β, whose activation is required for nuclear factor κB (NFκB)-mediated inflammatory response. We speculate that the development and progression of NAFLD was prevented by the reduction of MCP1 production through the interference in the IKKβ-NFκB signaling pathway in Mukitake-fed db/db mice.