| Background:Peripheral artery disease(PAD),characterized by high risk of cardiovascular complications and mortality,is a growing public health problem.Atherosclerotic plaques affecting lower extremity arteries induce ischemia in lower limb,and lead to a high risk of cardiovascular adverse events along with limb loss.Further understanding of the physiopathology of PAD is urgently needed to advance development of efficacious therapeutic strategies.Macrophage-mediated inflammatory response is closely associated with the neovascularization process following hindlimb ischemia(HLI).Previous study has demonstrated that heme oxygenase-1(HO-1)in macrophages evoked proinflammatory reactions and tissue damage.Here,we evaluated the role played by macrophage-derived HO-1 and elucidated its underlying molecular mechanisms in perfusion recovery after hindlimb ischemia.Methods and Results:We found significant upregulation of HO-1 in mouse ischemic muscles after HLI surgery,and with most of this expression occurring in infiltrated macrophages.Myeloid conditional HO-1-defcient mice exhibited higher perfusion recovery,evidenced by restored blood flow,motor function and attenuated tissue damage as well as increased capillary density in the gastrocnemius muscles after HLI,relative to littermate controls.This protective effect was accompanied by reduced nod-like receptor family,pyrin domain containing 3(NLRP3)inflammasome activation in the infiltrated macrophages without the alteration of macrophage infiltration and polarization.Moreover,suppressing inflammasome activation with NLRP3 inhibitor MCC950 improved blood flow and capillary density in wild-type(WT)mice compared to untreated mice.Mechanistically,suppressing HO-1 abolished TNF-α-induced NLRP3 protein rather than m RNA expression in bone marrow-derived macrophages(BMDMs),indicating that HO-1 mediated post-transcriptional regulation of NLRP3.Furthermore,HO-1inhibition promoted autolysosome-dependent degradation of NLRP3 in BMDMs.Matrigel tube formation assay revealed that HO-1 deletion abrogated the antiangiogenic effect of inflammasome-activated macrophages.Conclusions:Taken together,these findings indicate that myeloid HO-1 deficiency promotes perfusion recovery after HLI by accelerating autolysosomal degradation of NLRP3.The underlying mechanism of action is a potential target for therapeutic angiogenesis in ischemic diseases. |
