Deciphering the Role of Metabolic Changes on Epigenetic Regulation in Chronic Limb Threatening Ischemia and Surgical Revascularization

About This Grant

Chronic limb-threatening ischemia (CLTI), the most severe form of peripheral artery disease, impacts over 25 million people and is characterized by ischemic rest pain, non-healing ulcers, gangrene, and an increased risk of limb amputation or death. Despite advances in surgical revascularization, amputation rates remain high in CLTI. CLTI patients undergoing limb amputation exhibit a distinct mitochondrial disease, whereas pre-surgical CLTI patients' muscle displays a compensatory upregulation of mitochondrial proteins despite impaired oxidative phosphorylation. CLTI's metabolic insufficiency and limited O₂ delivery create significant challenges, yet their impact on epigenetic regulation remains unexplored. In CLTI, poor mitochondrial function and low O2 availability drive the accumulation of acetyl-CoA and lactate, which serve as substrates for histone acetylation and lactylation. My preliminary work show increased histone acetylation and lactylation levels in ischemic muscle, linking CLTI's metabolic challenges to these histone modifications. C57BL/6J and BALB/cJ mouse strains exhibit distinct ischemic responses, corresponding with stark differences in skeletal muscle mitochondrial function and ischemic regeneration. Whether histone acetylation and lactylation regulate these strain-specific differences remains unknown. My preliminary data reveals a divergence in mitochondrial performance across CLTI patients following surgical revascularization, suggesting that patient-specific metabolic and epigenetic factors may influence treatment outcomes. In this predoctoral fellowship proposal, I will test the hypothesis that mitochondrial dysfunction in CLTI drives epigenetic changes in ischemic muscle, influencing post-revascularization recovery. Aim 1 will define how mitochondrial-driven changes alter the epigenetic landscape of skeletal muscle in the CLTI limb and in response to surgical revascularization. I will quantify histone modifications in skeletal muscle from BALB/cJ and C57BL/6J mice post-femoral artery ligation (FAL) and in CLTI patient biopsies from non-ischemic, ischemic, and post-revascularization regions to assess strain- and disease-specific differences. I will perform chromatin immunoprecipitation sequencing (ChIP-seq) to identify regions of the genome affected by identified histone modifications. Aim 2 I will determine if pharmacologically modulating metabolite abundance or histone deacetylase activity impacts limb function and recovery in mice subject to FAL. To test this, I will manipulate acetyl-CoA and lactate levels using a pyruvate dehydrogenase activator and lactate dehydrogenase inhibitor and modulate histone acetylation and lactylation with an FDA-approved HDAC inhibitor in BALB/cJ mice following FAL. A detailed training program with strong mentorship that involves specific research skill enhancement in molecular biology, epigenetics, and multi-omics has been developed. I will receive career mentoring involving grant/manuscript writing, presentation skills, and professional development opportunities. Completion of this proposal will result in exceptional scientific and professional training, which will provide a strong foundation for my career goals.