Abstract 3018: Expression Of The Aim2 Inflammasome In Skeletal Is Modulated By Surgical Bypass And Is A Target To Reduce Ischemic Myopathy In Pad

Abstract

Introduction: Peripheral arterial disease (PAD) causes skeletal muscle myopathy and impairment, yet relevant pathways are understudied. We reported a new role for the absent in melanoma 2 (AIM2) inflammasome in PAD myocyte function. We hypothesize that AIM2 is an important mediator of cell death pathways in PAD muscle and is reduced by revascularization. Methods: Myocytes were obtained commercially or from ischemic and perfused PAD muscle using cell sorting. mRNA libraries underwent next generation sequencing (NGS) and differential gene expression (DGE) mapped to the GRCh368 human genome. Ingenuity Pathway Analysis (IPA) identified relevant biological pathways filtered by both fold change (fc) >2 and false discovery rate of p< 0.05. Sections were procured from human gastrocnemius before and after vascular bypass and analyzed for AIM2 with immunofluorescence (IF) and western blot (WB). Inflammatory caspase-1 activity was measured +/- siRNA against AIM2. Statistical analysis included t- test and ANOVA + post-hoc analysis. P<0.05 was considered significant. Results: DGE and IPA on isolated myocytes highlighted Neutrophil Degranulation and Pathogen Induced Cytokine Storm Signaling Pathways to be significantly altered in ischemic muscle cells (Fig1, p < 1xE-30 each, N=4) emphasizing AIM2 inflammasome activation (CASP1, fc 30.73; NLRP3/ASC/CASP1, fc 27.23; PYCARD fc 40.63; IL1B fc 63.49). AIM2 protein was high in PAD by IF and WB. Caspase-1 activity was attenuated in the presence of AIM2 inhibition (N=3; ****p<0.0001 in PAD). AIM2 expression was significantly reduced after surgery for PAD (p<0.05, N=6/group, t-test). Conclusion: AIM2 inflammasome expression in PAD induces pyroptotic caspase activity and is attenuated by surgical bypass, directly demonstrating a unique biologic benefit of muscle revascularization in PAD. Targeting AIM2 pathways either pharmacologically or by surgery may help to reduce myopathic damage in ischemic muscle from PAD.