Abstract 9811: Bone Marrow-Derived Mir-181a/b Controls Hematopoiesis, Monocytosis, and Angiogenic Responses in Diabetic Critical Limb Ischemia

Abstract

Introduction: Humans with peripheral artery disease (PAD) that develop critical limb ischemia (CLI) have a high risk of amputation and cardiovascular complications. Diabetes mellitus (DM) is a prominent risk factor in development of CLI, yet the molecular mechanisms remain incompletely understood. Objective: To investigate microRNA biomarkers and their involvement in the pathogenesis of CLI in human subjects and mice with and without diabetes. Methods: miRNA-seq of diabetic patients with or without CLI was compared to diabetic mice with acute or subacute limb ischemia to identify conserved miRNAs. miRNA knockout (KO) mice on chow or high fat diet were generated to explore impact on CLI. Results: miR-181 family members were among the top conserved miRNAs from mice to human subjects. Compared to wild type (WT) controls, systemic Mir181a2b2 KO mice on chow-fed diet had increased blood flow recovery following FAL and higher M1-macrophage polarization in ischemic skeletal muscles. KO macrophages increased CCL4 and VEGFA to promote angiogenesis. Conversely, diabetic KO mice had impaired revascularization in limbs compared to WT, due to abrogation of circulating Ly6C hi monocytes with reduced accumulation of macrophages in ischemic skeletal muscles. Furthermore, M2-like macrophages deficient of miR-181a/b under diabetic conditions failed to produce pro-angiogenic cytokines. Reduced monocytosis in KO mice was a result of impaired hematopoiesis with increased CXCR4 signaling in Lin - Sca1 + Kit + (LSK) cells in the bone marrow. Importantly, supplying diabetic KO mice with exogenous delivery of Ly6C hi monocytes from non-diabetic KO mice rescued the impaired revascularization after limb ischemia. Conclusions: MiR-181a/b is a putative biomarker of diabetic CLI and contributes to alterations in hematopoiesis, monocytosis, and macrophage polarization. Pathways regulated by miR-181a/b may provide therapeutic targets for PAD patients at risk of developing CLI.