IDDF2024-ABS-0254 A novel mechanism and potential therapeutic target for intestinal fibrosis in crohn’s disease: CD47-SIRPa mediated crosstalk between macrophage and stromal cells

Background Intestinal fibrosis is a common complication of Crohn's disease (CD), but no anti-fibrotic therapy is currently available. Recently, upregulation of CD47 signaling has been shown as a unified mechanism in different fibrotic diseases, which could be regulating macrophage phagocytosis and activation. This study aims to investigate the role and therapeutic potential of CD47-SIRPa in intestinal fibrosis. Methods Thirty CD patients who underwent surgery due to fibrosis-induced intestinal obstruction were included in this study and the intestinal tissues were collected from both fibrotic and normal sites. Chronic dextrane sodium sulfate (DSS) mouse model was used and anti-CD47 antibody was treated intraperitoneally. Human and mice tissues were applied for single-cell RNA sequencing, flow cytometry, pathological evaluation, immunofluorescence staining and qPCR. Smart-seq were performed to detect the functional change of mice macrophage. Results Single-cell RNA sequencing and Smart-seq showed significantly elevated expression of CD47 in stromal cells and SIRPa in pro-fibrotic immature macrophages during fibrosis (IDDF2024-ABS-0254 Figure 1). The proportion of CD47+ stromal cells and SIRPa+ macrophages increased and co-located in fibrotic lesions. After flow sorting, qPCR showed that CD47+ stromal cells were in senescence-associated secretory phenotype (SASP), secreting more pro-fibrotic and pro-inflammatory factors (IDDF2024-ABS-0254 Figure 2). Anti-CD47 treatment significantly attenuated mice intestinal fibrosis compared to the control (IDDF2024-ABS-0254 Figure 3). There was a reduced number of CD47+ stromal cells and SIRPa+ macrophages as well as decreased expression of fibrosis-related genes after anti-CD47 treatment. Smart-seq showed that after treating anti-CD47 antibody, macrophages acquired an immune-suppressing and anti-fibrotic phenotype. These macrophages also had lower expression of 'don't eat me signal', regaining the capacity of phagocytosis. Meanwhile, anti-CD47 treatment led to the deactivation of JAK-STAT and MAPK signaling pathway while up-regulated the expression of inhibitory nuclear factor ID3 in macrophages, which may together contribute to the decrease of SIRPa expression and promote the macrophage phagocytic response (IDDF2024-ABS-0254 Figure 4). Conclusions CD47-SIRPa mediated macrophage-stromal cell crosstalk significantly contributed to intestinal fibrosis in CD and may be a therapeutic target for intestinal fibrosis.