Protective Effects of Antcin H Isolated from Antrodia cinnamomea Against Neuroinflammation in Huntington's Disease via NLRP3 Inflammasome Inhibition.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the expansion of a CAG trinucleotide repeat in the huntingtin (HTT) gene. When the CAG repeat exceeds 36, it results in the accumulation of the mutant HTT (mHTT) protein in neurons and glial cells. Key pathological mechanisms in HD include excitotoxicity, energy dysfunction, impaired mitochondrial function, increased oxidative stress, and neuroinflammation. The NLRP3 inflammasome is a multimeric protein complex element of NLRP3, ASC, and caspase-1, which regulates interleukin (IL)-1β and IL-18 secretion. The NLRP3 inflammasome plays an important role in inflammatory reactions and is involved in the pathogenesis of several neurodegenerative diseases. We have previously demonstrated high NLRP3 inflammasome expression levels in the striatum of R6/2 mice (a transgenic HD mouse model). Systematic administration of an NLRP3 inhibitor (MCC950) to R6/2 mice suppressed the NLRP3 inflammasome, decreased IL-1β and reactive oxygen species production, and reduced neuronal toxicity, suggesting protective effects against HD. Antrodia cinnamomea is an indigenous medicinal fungus in Taiwan, which shows diverse medicinal and pharmacological activities, but its effects in HD are not well understood. Herein, we report that systematic administration of Antcin-H isolated from A. cinnamomea to R6/2 mice suppressed the NLRP3 inflammasome, IL-1β production, and reduced neuronal toxicity. Most importantly, oral administration of Antcin-H reduced disease progression by increasing neuronal survival, reducing neuroinflammation during an extended lifespan, and improving motor dysfunction in R6/2 mice. Taken together, our data suggest that Antcin-H has therapeutic potential for treating HD.