Recipient Resident Macrophage Plays a Crucial Role in Acute Graft-Versus-Host-Disease after Allogeneic Stem Cell Transplantation By Regulation of Damage-Associated Molecular Pattern Phagocytosis

Introduction Evidence shows allogeneic hematopoietic stem cell transplantation (alloHSCT) provides life-sustaining therapy for many hematologic malignancies. Unfortunately, in many cases it is complicated by acute-graft-versus-host disease (aGVHD), a life-threatening sequela. Most interstitial tissues contain populations of resident macrophages. Multiple studies have investigated the role of infiltrating macrophages in aGVHD, but little is known about the role of resident macrophage in aGVHD. To address this issue, we adopt a LysM cre/cre-Hif1a flox/flox mice (KO)as host mice with abnormal macrophage whose host resident macrophage remains unchanged early after allo-HSCT. KO mice received alloHSCT after Total body irradiation (TBI) from wild-type(WT) mice of BALB/c background. The neutrophil and circulating monocyte/macrophage were replaced by WT cells and the resident macrophage remains unchanged after this procedure. The grade of aGVHD and survival was observed. Methods Recipient mice are on the background of C57BL/6(H-2 b), and donor mice are wild-type BALB/c (H-2 d ) mice. All mice used were 8-12 week old. All animal experiment protocols were approved. LysM cre/cre (CRE) mice were taken as control recipients. Mice were exposed to TBI split into two doses separated by 4h. KO and CRE C57/BL mice received 9 Gy TBI. 18h after irradiation, mice of two groups were injected i.v with 1×10 7BM cells and 1.5×10 7 splenocytes isolated from WT BALB/c mice. aGVHD score and survival are monitored daily. Isolation of Kupffer subsets was performed as CD45 +CD11b + Ly6G -F4/80 +, which from KO and CRE mice of GVHD model were taken to do single-cell sequencing assay. Survival curves were plotted by the Kaplan-Meier method. The statistical significance between group means was determined using t-test by Graphpad prism9.5. The level of significance was set at P