Kidney transplantation is the most effective treatment for end-stage renal failure, and antibody-mediated rejection remains the leading cause of late allograft loss. Macrophages, as central effectors of innate immunity, play a crucial role in the initiation, progression and tissue damage of antibody-mediated rejection. This article reviews the spatiotemporal dynamic evolution of macrophage polarization status in different stages of antibody-mediated rejection, the fine regulation of key signaling pathways for macrophage polarization, macrophage related molecules and the application prospects of targeted macrophage therapy. In depth analysis of the research progress of macrophages in antibody-mediated rejection, aiming to provide important theoretical basis for the development of precision diagnostic tools based on macrophages and novel immune intervention targets for antibody mediated rejection, ultimately promoting the improvement of long-term prognosis in kidney transplantation.

Objective:To explore the role of macrophage polarization on pericyte-to-myofibroblast transition and renal allograft fibrosis after kidney transplantation(KT).Methods:Allograft tissues were harvestedfrom recipients with chronic allograft dysfunction(CGD)and normal kidney tissues.The expression and distribution of M1/M2 macrophages in kidney tissues were detected by routine and immunofluorescent staining; mRNA of CD68, CD206 and iNOS detected by polymerase chain reaction(PCR); Murine vascular pericytes subjected to TGF-β1 in vitro and the expressions of α-SMA and PDGFR-β in perivascular cells detected by immunoblotting and cellular fluorescence; The co-culturing models of vascular pericytes and M1/M2 macrophages were constructed.The expressions of α-SMA and PDGFR-β in pericytes were detected by immunoblotting, cellular fluorescence and PCR.Results:A marked infiltration of CD68+ iNOS+ M1 macrophages was present in allograft tissues of recipients with CGD while no obvious infiltration of CD68 + CD206 + was observed.The mRNA levels of CD68, iNOS and CD206 were significantly higher in CGD group than those in control group( P<0.05); In CGD allograft tissues, protein expressions of α-SMA and PDGFR-β spiked markedly( P<0.05)while cells with double staining of α-SMA and PDGFR-β were markedly infiltrated in interstitial area of CGD allograft.TGF-β1 could induce a marked elevation of PMT-related markers in a time-dependent manner( P<0.05); Immunoblotting and cellukar fluorescence indicated that M1 macrophages could promote the elevations of α-SMA and PDGFR-β in pericytes in vitro while M2 macrophages showed no effect on pericyte-to-myofibroblast transition in pericytes. Conclusions:M1 macrophage polarization may promote the formation of renal allograft interstitial fibrosis through promoting PMT.