Dihydromyricetin alleviates methotrexate-induced hepatotoxicity via suppressing the ‎TLR4/NF-κB pathway and NLRP3 inflammasome/caspase 1 axis.

The anticancer drug methotrexate (MTX) is known to cause hepatotoxicity as a possibly fatal adverse effect that hinders its clinical application. Although the natural flavonoid, dihydromyricetin (DHM), has antioxidant and anti-inflammatory effects; its role against MTX-induced hepatotoxicity has not been explored yet. For this, rats were administrated DHM orally for two weeks at a dose of 300 mg/kg per day, with or without a single i.p. injection of 40 mg/kg MTX on the 9th day of the experiment. MTX caused deterioration in liver structure and function, depicted by an increase in liver enzymes; ALT and AST. Moreover, MTX induced oxidative stress, shown by increasing malondialdehyde and decreasing reduced glutathione and total antioxidant capacity, initiated the inflammatory response via upregulated expression of Toll-like receptor 4 (TLR4) and its downstream transcription factor, nuclear factor-kappa B (NF-κB p65). Consequent to TLR4 signaling cascade, Nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammosome was activated and caused caspase 1 mediated transformation of proinflammatory cytokines interleukin 1β (IL-1β) and interleukin 18 (IL-18) into their active forms. Interestingly, administering DHM with MTX improved liver structure and function, as well as significantly decreased all oxidative stress and inflammatory signaling. Collectively, DHM possesses antioxidant and anti-inflammatory properties that can ameliorate MTX-induced hepatotoxicity, through down-regulation of liver TLR4/NF-κB and therefore prohibit activation of NLRP3/caspase 1 pathway.