[ 1 ] Ochando J, Fayad ZA, Madsen JC, Netea MG, Mulder WJM. Trained immunity in organ transplantation. Am J Transplant 2020;20(1):10–8. link1

[ 2 ] Lakkis FG, Li XC. Innate allorecognition by monocytic cells and its role in graft rejection. Am J Transplant 2018;18(2):289–92. link1

[ 3 ] Bosch TPP, Hilbrands LB, Kraaijeveld R, Litjens NHR, Rezaee F, Nieboer D, et al. Pretransplant numbers of CD16+ monocytes as a novel biomarker to predict acute rejection after kidney transplantation: a pilot study. Am J Transplant 2017;17(10):2659–67. link1

[ 4 ] Oberbarnscheidt MH, Zeng Q, Li Q, Dai H, Williams AL, Shlomchik WD, et al. Non-self recognition by monocytes initiates allograft rejection. J Clin Invest 2014;124(8):3579–89. link1

[ 5 ] Li XC. The significance of non-T-cell pathways in graft rejection: implications for transplant tolerance. Transplantation 2010;90(10):1043–7. link1

[ 6 ] Zhao Y, Chen S, Lan P, Wu C, Dou Y, Xiao X, et al. Macrophage subpopulations and their impact on chronic allograft rejection versus graft acceptance in a mouse heart transplant model. Am J Transplant 2018;18(3):604–16. link1

[ 7 ] Ochando J, Ordikhani F, Boros P, Jordan S. The innate immune response to allotransplants: mechanisms and therapeutic potentials. Cell Mol Immunol 2019;16(4):350–6. link1

[ 8 ] Chu Z, Sun C, Sun L, Feng C, Yang F, Xu Y, et al. Primed macrophages directly and specifically reject allografts. Cell Mol Immunol 2020;17(3):237–46. link1

[ 9 ] Zhu L, Zhao Q, Yang T, Ding W, Zhao Y. Cellular metabolism and macrophage functional polarization. Int Rev Immunol 2015;34(1):82–100. link1

[10] Chen S, Yang J, Wei Y, Wei X. Epigenetic regulation of macrophages: from homeostasis maintenance to host defense. Cell Mol Immunol 2020;17 (1):36–49. link1

[11] Zhao Y, Zou W, Du J, Zhao Y. The origins and homeostasis of monocytes and tissue-resident macrophages in physiological situation. J Cell Physiol 2018;233(10):6425–39. link1

[12] Martinez FO, Sica A, Mantovani A, Locati M. Macrophage activation and polarization. Front Biosci 2008;13(13):453–61. link1

[13] Locati M, Curtale G, Mantovani A. Diversity, mechanisms, and significance of macrophage plasticity. Annu Rev Pathol 2020;15:123–47. link1

[14] Nahrendorf M, Swirski FK. Abandoning M1/M2 for a network model of macrophage function. Circ Res 2016;119(3):414–7. link1

[15] Italiani P, Boraschi D. From monocytes to M1/M2 macrophages: phenotypical vs. functional differentiation. Front Immunol 2014;5:514.

[16] Zhang H, Li Z, Li W. M2 macrophages serve as critical executor of innate immunity in chronic allograft rejection. Front Immunol 2021;12:648539. link1

[17] Hou Y, Zhu L, Tian H, Sun HX, Wang R, Zhang L, et al. IL-23-induced macrophage polarization and its pathological roles in mice with imiquimodinduced psoriasis. Protein Cell 2018;9(12):1027–38. link1

[18] Chistiakov DA, Bobryshev YV, Orekhov AN. Changes in transcriptome of macrophages in atherosclerosis. J Cell Mol Med 2015;19(6):1163–73. link1

[19] Paoletti E, Bussalino E, Bellino D, Tagliamacco A, Bruzzone M, Ravera M, et al. Early interstitial macrophage infiltration with mild dysfunction is associated with subsequent kidney graft loss. Clin Transplant 2019;33(6):e13579. link1

[20] Toki D, Zhang W, Hor KL, Liuwantara D, Alexander SI, Yi Z, et al. The role of macrophages in the development of human renal allograft fibrosis in the first year after transplantation. Am J Transplant 2014;14(9):2126–36. link1

[21] Bergler T, Jung B, Bourier F, Kühne L, Banas MC, Rümmele P, et al. Infiltration of macrophages correlates with severity of allograft rejection and outcome in human kidney transplantation. PLoS ONE 2016;11(6):e0156900. link1

[22] Azad TD, Donato M, Heylen L, Liu AB, Shen-Orr SS, Sweeney TE, et al. Inflammatory macrophage-associated 3-gene signature predicts subclinical allograft injury and graft survival. JCI Insight 2018;3(2):e95659. link1

[23] Bräsen JH, Khalifa A, Schmitz J, Dai W, Einecke G, Schwarz A, et al. Macrophage density in early surveillance biopsies predicts future renal transplant function. Kidney Int 2017;92(2):479–89 link1

[24] Einecke G, Mengel M, Hidalgo L, Allanach K, Famulski KS, Halloran PF. The early course of kidney allograft rejection: defining the time when rejection begins. Am J Transplant 2009;9(3):483–93. link1

[25] Llaudo I, Fribourg M, Medof ME, Conde P, Ochando J, Heeger PS. C5aR1 regulates migration of suppressive myeloid cells required for costimulatory blockade-induced murine allograft survival. Am J Transplant 2019;19 (3):633–45. link1

[26] Yang F, Li Y, Zhang Q, Tan L, Peng L, Zhao Y. The effect of immunosuppressive drugs on MDSCs in transplantation. J Immunol Res 2018;2018:5414808. link1

[27] Wu T, Zhao Y, Zhao Y. The roles of myeloid-derived suppressor cells in transplantation. Expert Rev Clin Immunol 2014;10(10):1385–94. link1

[28] van den Bosch TP, Kannegieter NM, Hesselink DA, Baan CC, Rowshani AT. Targeting the monocyte–macrophage lineage in solid organ transplantation. Front Immunol 2017;8:153. link1

[29] Pascual-Gil S, Epelman S. Monocyte-derived macrophages: the missing link in organ transplantation. Immunity 2018;49(5):783–5. link1

[30] Benichou G, Tonsho M, Tocco G, Nadazdin O, Madsen JC. Innate immunity and resistance to tolerogenesis in allotransplantation. Front Immunol 2012;3:73. link1

[31] Penfield JG, Wang Y, Li S, Kielar MA, Sicher SC, Jeyarajah DR, et al. Transplant surgery injury recruits recipient MHC class II-positive leukocytes into the kidney. Kidney Int 1999;56(5):1759–69. link1

[32] Lan HY, Yang N, Brown FG, Isbel NM, Nikolic-Paterson DJ, Mu W, et al. Macrophage migration inhibitory factor expression in human renal allograft rejection. Transplantation 1998;66(11):1465–71. link1

[33] Grau V, Gemsa D, Steiniger B, Garn H. Chemokine expression during acute rejection of rat kidneys. Scand J Immunol 2000;51(5):435–40. link1

[34] Zhang H, Gao S, Yan L, Zhu G, Zhu Q, Gu Y, et al. EPO derivative ARA290 attenuates early renal allograft injury in rats by targeting NF-jB pathway. Transplant Proc 2018;50(5):1575–82. link1

[35] Arango Duque G, Descoteaux A. Macrophage cytokines: involvement in immunity and infectious diseases. Front Immunol 2014;5:491. link1

[36] Russell ME, Wallace AF, Hancock WW, Sayegh MH, Adams DH, Sibinga NE, et al. Upregulation of cytokines associated with macrophage activation in the Lewis-to-F344 rat transplantation model of chronic cardiac rejection. Transplantation 1995;59(4):572–8. link1

[37] Pattison JM, Nelson PJ, von Leuttichau I, Krensky AM, Huie P, Farshid G, et al. RANTES chemokine expression in cell-mediated transplant rejection of the kidney. Lancet 1994;343(8891):209–11. link1

[38] Cheng L, Xing H, Mao X, Li L, Li X, Li Q. Lipocalin-2 promotes m1 macrophages polarization in a mouse cardiac ischaemia-reperfusion injury model. Scand J Immunol 2015;81(1):31–8. link1

[39] Kaul AM, Goparaju S, Dvorina N, Iida S, Keslar KS, de la Motte CA, et al. Acute and chronic rejection: compartmentalization and kinetics of counterbalancing signals in cardiac transplants. Am J Transplant 2015;15(2):333–45. link1

[40] Furukawa Y, Mandelbrot DA, Libby P, Sharpe AH, Mitchell RN. Association of B7–1 co-stimulation with the development of graft arterial disease: studies using mice lacking B7–1, B7–2, or B7–1/B7-2. Am J Pathol 2000;157 (2):473–84. link1

[41] Panzer SE, Wilson NA, Verhoven BM, Xiang D, Rubinstein CD, Redfield RR, et al. Complete B cell deficiency reduces allograft inflammation and intragraft macrophages in a rat kidney transplant model. Transplantation 2018;102 (3):396–405. link1

[42] Grau V, Stehling O, Garn H, Steiniger B. Accumulating monocytes in the vasculature of rat renal allografts: phenotype, cytokine, inducible no synthase, and tissue factor mRNA expression. Transplantation 2001;71 (1):37–46. link1

[43] Jose MD, Le Meur Y, Atkins RC, Chadban SJ. Blockade of macrophage colonystimulating factor reduces macrophage proliferation and accumulation in renal allograft rejection. Am J Transplant 2003;3(3):294–300. link1

[44] Le Meur Y, Jose MD, Mu W, Atkins RC, Chadban SJ. Macrophage colonystimulating factor expression and macrophage accumulation in renal allograft rejection. Transplantation 2002;73(8):1318–24. link1

[45] Oldenborg PA, Zheleznyak A, Fang YF, Lagenaur CF, Gresham HD, Lindberg FP. Role of CD47 as a marker of self on red blood cells. Science 2000;288 (5473):2051–4. link1

[46] Barclay AN, Van den Berg TK. The interaction between signal regulatory protein alpha (SIRPa) and CD47: structure, function, and therapeutic target. Annu Rev Immunol 2014;32(1):25–50. link1

[47] Wang Y, Wang H, Bronson R, Fu Y, Yang YG. Rapid dendritic cell activation and resistance to allotolerance induction in anti-CD154-treated mice receiving CD47-deficient donor-specific transfusion. Cell Transplant 2014;23(3):355–63. link1

[48] Wang H, Wu X, Wang Y, Oldenborg PA, Yang YG. CD47 is required for suppression of allograft rejection by donor-specific transfusion. J Immunol 2010;184(7):3401–7. link1

[49] Zhang M, Wang H, Tan S, Navarro-Alvarez N, Zheng Y, Yang YG. Donor CD47 controls T cell alloresponses and is required for tolerance induction following hepatocyte allotransplantation. Sci Rep 2016;6(1):26839. link1

[50] Chen M, Wang Y, Wang H, Sun L, Fu Y, Yang YG. Elimination of donor CD47 protects against vascularized allograft rejection in mice. Xenotransplantation 2019;26(2):e12459. link1

[51] Xiao Z, Banan B, Xu M, Jia J, Manning PT, Hiebsch RR, et al. Attenuation of ischemia-reperfusion injury and improvement of survival in recipients of steatotic rat livers using CD47 monoclonal antibody. Transplantation 2016;100(7):1480–9. link1

[52] Wang X, Xu M, Jia J, Zhang Z, Gaut JP, Upadhya GA, et al. CD47 blockade reduces ischemia/reperfusion injury in donation after cardiac death rat kidney transplantation. Am J Transplant 2018;18(4):843–54. link1

[53] Xu M, Wang X, Banan B, Chirumbole DL, Garcia-Aroz S, Balakrishnan A, et al. Anti-CD47 monoclonal antibody therapy reduces ischemia-reperfusion injury of renal allografts in a porcine model of donation after cardiac death. Am J Transplant 2018;18(4):855–67. link1

[54] Pengam S, Durand J, Usal C, Gauttier V, Dilek N, Martinet B, et al. SIRPa/CD47 axis controls the maintenance of transplant tolerance sustained by myeloidderived suppressor cells. Am J Transplant 2019;19(12):3263–75. link1

[55] Wu YL, Ye Q, Eytan DF, Liu L, Rosario BL, Hitchens TK, et al. Magnetic resonance imaging investigation of macrophages in acute cardiac allograft rejection after heart transplantation. Circ Cardiovasc Imaging 2013;6 (6):965–73. link1

[56] Hancock WW, Thomson NM, Atkins RC. Composition of interstitial cellular infiltrate identified by monoclonal antibodies in renal biopsies of rejecting human renal allografts. Transplantation 1983;35(5):458–63. link1

[57] Pabois A, Pagie S, Gérard N, Laboisse C, Pattier S, Hulin P, et al. Notch signaling mediates crosstalk between endothelial cells and macrophages via Dll4 and IL6 in cardiac microvascular inflammation. Biochem Pharmacol 2016;104:95–107. link1

[58] Zhao W, Zhang Z, Zhao Q, Liu M, Wang Y. Inhibition of interferon regulatory factor 4 attenuates acute liver allograft rejection in mice. Scand J Immunol 2015;82(3):262–8. link1

[59] Ratliff NB, McMahon JT. Activation of intravascular macrophages within myocardial small vessels is a feature of acute vascular rejection in human heart transplants. J Heart Lung Transplant 1995;14(2):338–45. link1

[60] Wu C, Zhao Y, Xiao X, Fan Y, Kloc M, Liu W, et al. Graft-infiltrating macrophages adopt an M2 phenotype and are inhibited by purinergic receptor P2X7 antagonist in chronic rejection. Am J Transplant 2016;16 (9):2563–73. link1

[61] Lamb KE, Lodhi S, Meier-Kriesche HU. Long-term renal allograft survival in the United States: a critical reappraisal. Am J Transplant 2011;11 (3):450–62. link1

[62] Kitchens WH, Chase CM, Uehara S, Cornell LD, Colvin RB, Russell PS, et al. Macrophage depletion suppresses cardiac allograft vasculopathy in mice. Am J Transplant 2007;7(12):2675–82. link1

[63] Nikolic-Paterson DJ, Wang S, Lan HY. Macrophages promote renal fibrosis through direct and indirect mechanisms. Kidney Int Suppl 2014;4(1):34–8. link1

[64] Meng XM, Nikolic-Paterson DJ, Lan HY. TGF-b: the master regulator of fibrosis. Nat Rev Nephrol 2016;12(6):325–38. link1

[65] Ikezumi Y, Suzuki T, Yamada T, Hasegawa H, Kaneko U, Hara M, et al. Alternatively activated macrophages in the pathogenesis of chronic kidney allograft injury. Pediatr Nephrol 2015;30(6):1007–17. link1

[66] Wang YY, Jiang H, Pan J, Huang XR, Wang YC, Huang HF, et al. Macrophage-tomyofibroblast transition contributes to interstitial fibrosis in chronic renal allograft injury. J Am Soc Nephrol 2017;28(7):2053–67. link1

[67] van den Bosch TPP, Caliskan K, Kraaij MD, Constantinescu AA, Manintveld OC, Leenen PJM, et al. CD16+ monocytes and skewed macrophage polarization toward M2 type hallmark heart transplant acute cellular rejection. Front Immunol 2017;8:346. link1

[68] Liu Y, Chen W, Wu C, Minze LJ, Kubiak JZ, Li XC, et al. Macrophage/monocytespecific deletion of Ras homolog gene family member A (RhoA) downregulates fractalkine receptor and inhibits chronic rejection of mouse cardiac allografts. J Heart Lung Transplant 2017;36(3):340–54. link1

[69] Liu W, Xiao X, Demirci G, Madsen J, Li XC. Innate NK cells and macrophages recognize and reject allogeneic nonself in vivo via different mechanisms. J Immunol 2012;188(6):2703–11. link1

[70] Christen T, Nahrendorf M, Wildgruber M, Swirski FK, Aikawa E, Waterman P, et al. Molecular imaging of innate immune cell function in transplant rejection. Circulation 2009;119(14):1925–32. link1

[71] Yamamoto N, Einaga-Naito K, Kuriyama M, Kawada Y, Yoshida R. Cellular basis of skin allograft rejection in mice: specific lysis of allogeneic skin components by non-T cells. Transplantation 1998;65(6):818–25. link1

[72] Yoshida R, Sanchez-Bueno A, Yamamoto N, Einaga-Naito K. Ca2+-dependent, Fas- and perforin-independent apoptotic death of allografted tumor cells by a type of activated macrophage. J Immunol 1997;159(1):15–21. link1

[73] Dai H, Lan P, Zhao D, Abou-Daya K, Liu W, Chen W, et al. PIRs mediate innate myeloid cell memory to nonself MHC molecules. Science 2020;368 (6495):1122–7. link1

[74] Carretero-Iglesia L, Bouchet-Delbos L, Louvet C, Drujont L, Segovia M, Merieau E, et al. Comparative study of the immunoregulatory capacity of in vitro generated tolerogenic dendritic cells, suppressor macrophages, and myeloidderived suppressor cells. Transplantation 2016;100(10):2079–89. link1

[75] Riquelme P, Tomiuk S, Kammler A, Fändrich F, Schlitt HJ, Geissler EK, et al. IFN-c-induced iNOS expression in mouse regulatory macrophages prolongs allograft survival in fully immunocompetent recipients. Mol Ther 2013;21 (2):409–22. link1

[76] Hutchinson JA, Riquelme P, Sawitzki B, Tomiuk S, Miqueu P, Zuhayra M, et al. Cutting edge: immunological consequences and trafficking of human regulatory macrophages administered to renal transplant recipients. J Immunol 2011;187(5):2072–8. link1

[77] Riquelme P, Amodio G, Macedo C, Moreau A, Obermajer N, Brochhausen C, et al. DHRS9 is a stable marker of human regulatory macrophages. Transplantation 2017;101(11):2731–8. link1

[78] Yang F, Li Y, Zou W, Xu Y, Wang H, Wang W, et al. Adoptive transfer of IFN-cinduced M-MDSCs promotes immune tolerance to allografts through iNOS pathway. Inflamm Res 2019;68(7):545–55. link1

[79] Wu T, Zhao Y, Wang H, Li Y, Shao L, Wang R, et al. mTOR masters monocytic myeloid-derived suppressor cells in mice with allografts or tumors. Sci Rep 2016;6:20250. link1

[80] Riquelme P, Haarer J, Kammler A, Walter L, Tomiuk S, Ahrens N, et al. TIGIT+ iTregs elicited by human regulatory macrophages control T cell immunity. Nat Commun 2018;9(1):2858. link1

[81] Hu X, Liu G, Hou Y, Shi J, Zhu L, Jin D, et al. Induction of M2-like macrophages in recipient NOD-scid mice by allogeneic donor CD4+ CD25+ regulatory T cells. Cell Mol Immunol 2012;9(6):464–72. link1

[82] Conde P, Rodriguez M, van der Touw W, Jimenez A, Burns M, Miller J, et al. DC-SIGN+ macrophages control the induction of transplantation tolerance. Immunity 2015;42(6):1143–58. link1

[83] Liu G, Ma H, Qiu L, Li L, Cao Y, Ma J, et al. Phenotypic and functional switch of macrophages induced by regulatory CD4+ CD25+ T cells in mice. Immunol Cell Biol 2011;89(1):130–42. link1

[84] Hutchinson JA, Riquelme P, Geissler EK, Fändrich F. Human regulatory macrophages. Methods Mol Biol 2011;677:181–92. link1

[85] Ribechini E, Hutchinson JA, Hergovits S, Heuer M, Lucas J, Schleicher U, et al. Novel GM-CSF signals via IFN-cR/IRF-1 and AKT/mTOR license monocytes for suppressor function. Blood Adv 2017;1(14):947–60. link1

[86] Broichhausen C, Riquelme P, Geissler EK, Hutchinson JA. Regulatory macrophages as therapeutic targets and therapeutic agents in solid organ transplantation. Curr Opin Organ Transplant 2012;17(4):332–42. link1

[87] Zhao Y, Shen X, Na N, Chu Z, Su H, Chao S, et al. mTOR masters monocyte development in bone marrow by decreasing the inhibition of STAT5 on IRF8. Blood 2018;131(14):1587–99. link1

[88] Mercalli A, Calavita I, Dugnani E, Citro A, Cantarelli E, Nano R, et al. Rapamycin unbalances the polarization of human macrophages to M1. Immunology 2013;140(2):179–90. link1

[89] Braza MS, van Leent MMT, Lameijer M, Sanchez-Gaytan BL, Arts RJW, PérezMedina C, et al. Inhibiting inflammation with myeloid cell-specific nanobiologics promotes organ transplant acceptance. Immunity 2018;49 (5):819. 28.e6. link1

[90] Salehi S, Sosa RA, Jin YP, Kageyama S, Fishbein MC, Rozengurt E, et al. Outside-in HLA class I signaling regulates ICAM-1 clustering and endothelial cell-monocyte interactions via mTOR in transplant antibody-mediated rejection. Am J Transplant 2018;18(5):1096–109. link1

[91] Murphy GJ, Waller JR, Sandford RS, Furness PN, Nicholson ML. Randomized clinical trial of the effect of microemulsion cyclosporin and tacrolimus on renal allograft fibrosis. Br J Surg 2003;90(6):680–6. link1

[92] Mizuiri S, Iwamoto M, Miyagi M, Kawamura T, Sakai K, Arai K, et al. Activation of nuclear factor-kappa B and macrophage invasion in cyclosporin A- and tacrolimus-treated renal transplants. Clin Transplant 2004;18(1):14–20. link1

[93] Kakuta Y, Okumi M, Miyagawa S, Tsutahara K, Abe T, Yazawa K, et al. Blocking of CCR5 and CXCR3 suppresses the infiltration of macrophages in acute renal allograft rejection. Transplantation 2012;93(1):24–31. link1

[94] Young BA, Burdmann EA, Johnson RJ, Alpers CE, Giachelli CM, Eng E, et al. Cellular proliferation and macrophage influx precede interstitial fibrosis in cyclosporine nephrotoxicity. Kidney Int 1995;48(2):439–48. link1

[95] Savikko J, Teppo AM, Taskinen E, von Willebrand E. Different effects of tacrolimus and cyclosporine on PDGF induction and chronic allograft injury: evidence for improved kidney graft outcome. Transpl Immunol 2014;31 (3):145–51. link1

[96] Hölschermann H, Dürfeld F, Maus U, Bierhaus A, Heidinger K, Lohmeyer J, et al. Cyclosporine a inhibits tissue factor expression in monocytes/macrophages. Blood 1996;88(10):3837–45. link1

[97] Shao K, Lu Y, Wang J, Chen X, Zhang Z, Wang X, et al. Different effects of tacrolimus on innate and adaptive immune cells in the allograft transplantation. Scand J Immunol 2016;83(2):119–27. link1

[98] Kannegieter NM, Hesselink DA, Dieterich M, Kraaijeveld R, Rowshani AT, Leenen PJ, et al. The effect of tacrolimus and mycophenolic acid on CD14+ monocyte activation and function. PLoS ONE 2017;12(1):e0170806. link1

[99] Ikezumi Y, Suzuki T, Karasawa T, Hasegawa H, Kawachi H, Nikolic-Paterson DJ, et al. Contrasting effects of steroids and mizoribine on macrophage activation and glomerular lesions in rat thy-1 mesangial proliferative glomerulonephritis. Am J Nephrol 2010;31(3):273–82. link1

[100] Palin NK, Savikko J, Rintala JM, Koskinen PK. Intensive perioperative simvastatin treatment protects from chronic kidney allograft injury. Am J Nephrol 2015;41(4–5):383–91. link1

[101] Tillmann FP, Grotz W, Rump LC, Pisarski P. Impact of monocyte–macrophage inhibition by ibandronate on graft function and survival after kidney transplantation: a single-centre follow-up study over 15 years. Clin Exp Nephrol 2018;22(2):474–80. link1