Peripheral artery disease (PAD) caused by atherosclerosis leads to considerable morbidity and mortality throughout the world, in large part, due to tissue damage from both acute and chronic occlusive ischemia. Preclinical studies have identified mechanisms involving bone marrow derived macrophage (BMDM) -dependent angiogenesis in an inflammation suppressed state and we recently defined a novel IL-1beta-dependent transcriptional regulation of the pro-angiogenic isoform of VEGF-A. We sought to understand the impact of diabetes on inflammatory angiogenesis in the context of aging. We hypothesized that the uncoupling of IL-1beta and VEGF-A expression with consequent impairments in angio/arteriogenesis. Control mice at 26-week-old of age or mice with experimental diabetes have reductions of angio/arteriogenesis, using a PAD model of femoral artery ligation that involves macrophage-directed blood flow recovery. Combined aging with chronic diabetes led to further reductions in blood flow recovery consequent to impaired angiogenesis. We also found elevated VEGF-R2 (relative to VEGF-R1) expression in the inflammatory “M1” state which was associated with elevations of IL-1beta and VEGF-A. Interestingly selective inhibition of VEGF-R2 led to reduced VEGF-A expression despite stable IL-1beta levels, suggesting an uncoupling of the relationship between IL-1beta and VEGF-A. Lastly, BMDMs from aged, diabetic mice demonstrated an uncoupling of IL-1beta and VEGF-A expression and VEGF-R2 was decreased in aged, diabetic BMDMs. Defining inflammatory macrophages as key, early drivers of angio/arteriogenesis via IL-1beta and VEGF-A/VEGF-R2 signaling supports a paradigm shift away from inflammation-suppression for adequate healing, allowing for macrophage reprograming strategies that promote appropriate inflammation-dependent healing responses.
C.S.Mantsounga: None. S.Sharma: None. C.Lee: None. R.Carley: None. G.Choudhary: None. A.R.Morrison: None.
National Institute of Health NIGMS (P20GM103652)