Statins activate the NLRP3 inflammasome and inhibit the Hippo pathway to promote myopathy
Authors: Robin Nazli , Barra Nicole , Patoli Danish , Watt Kevin , Nguyen Khang , Foley Kevin , Li Yujin , Tamrakar Akhilesh , Rebalka Irena , Huang Michael , Davis Rhianna , Chan Darryl , Duggan Brittany , Henriksbo Brandyn , Gregorevic Paul , Sweeney Gary , Hawke Thomas , Py Benedicte , Schertzer Jonathan 
Published: May 2023

High blood cholesterol affects ~30% of adult Canadians and doubles the risk of cardiac events. Statins are widely used for lowering cholesterol levels, but statins have pleiotropic effects that can be mediated by lowering protein prenylation. The most prevalent side effect of statin therapy is myopathy. Overt myotoxicity and rhabdomyolysis are rare (<0.01%) but, low-level myopathy, muscle pain, weakness, and exercise intolerance with no overt signs of muscle damage occur in 7-29% of statin users. When symptoms of myopathy are persistent, the only recourse is to change the type or dose of statin or stop taking statins, which can negate the benefits of statins. Our work demonstrated that statins promote low-level myopathy via lower protein prenylation and activation of the innate immune sensor, the NLRP3 inflammasome. The hippo pathway participates in the regulation of cell fate and muscle mass. Inhibition of Transcriptional coactivator (YAP) leads to muscle atrophy. We hypothesize that muscle cell autonomous statin-induced myopathy occurs through activation of the NLRP3 inflammasome and inhibition of YAP/TAZ. We built a muscle cell model of low-level statin-induced myopathy using inflammasome priming with low-level lipopolysaccharide (LPS) and exposure of C2C12 myotubes to clinically relevant doses of statins (i.e., 1-2 μM fluvastatin) in vitro. Statin myopathy was evinced by increased transcript levels of atrogin-1 and decreased myotube diameter. Adeno-associated virus 6 (AAV6) overexpression of hyperactive human YAP1 (YAPS127A) in C2C12 mitigated statin-mediated increases in atrogin-1 and lower myotube diameter compared to vector/vehicle controls in LPS primed myotubes. Statins also promoted the nuclear accumulation of FOXO1 and decreased levels of phosphorylated FOXO1/3a. Restoring protein prenylation and blocking the NLRP3 inflammasome prevented statin-induced nuclear accumulation of FOXO1 and mitigated decreased levels of p-FOXO1/3a. These results showed that prenylation and activation of NLRP3 inflammasome are both upstream of the FOXO activation. Our results demonstrated that activation of YAP in the presence of statins mitigated measures of statin-induced myopathy and that NLRP3 activation is upstream of FOXO activation, which is a known regulator of Atrogin-1. Further investigation to characterize the mechanism of statin-induced myopathy can lead to an enhanced understanding of statin-induced myopathy and the establishment of next-generation statin therapies without muscular side effects. Natural Sciences and Engineering Research Council (NSERC) of Canada This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.