IDDF2024-ABS-0252 Clostridium butyricum attenuates intestinal barrier injury by promoting PPARγ-mediated efferocytosis in macrophages

Background The prevalence of inflammatory bowel disease (IBD) has been on the rise in developing countries. However, the mechanism of interaction between gut microbiota and immunity, especially how probiotics regulate the imbalance of mucosal immunity in IBD, remains unclear. Hence, this study aims to explore the role of Clostridium butyricum (C. butyricum) in M2 macrophage-mediated intestinal barrier injury repairation regarding the mechanism of efferocytosis. Methods C. butyricum was treated in DSS-induced colitis mice to observe the gut barrier and the macrophage phenotype (IDDF2024-ABS-0252 Figure 1. C. butyricum promoted polarization and efferocytosis of macrophage in colitis mice (A) The flow chart of the experiment). The efferocytosis-related gene expression in terms of mucosal healing was explored in colitis mice with or without clodronate liposome treatment. RNA-sequencing was used to study the mechanism of C. butyricum on macrophage efferocytosis. Results We found that C. butyricum relieved intestinal inflammation and intestinal barrier injury in colitis mice (IDDF2024-ABS-0252 Figure 1. C. butyricum promoted polarization and efferocytosis of macrophage in colitis mice (B,C) The wight loss and histological images of mice). M2 macrophages and the efferocytosis-related genes were upregulated after C. butyricum treatment (IDDF2024-ABS-0252 Figure 1. C. butyricum promoted polarization and efferocytosis of macrophage in colitis mice (D-I) The frequency and efferocytosis-related genes expression of macrophage). Macrophage deletion induced by clodronate liposomes prevented the role of C. butyricum on the intestinal barrier and macrophage phenotype (IDDF2024-ABS-0252 Figure 1. C. butyricum promoted polarization and efferocytosis of macrophage in colitis mice (J-M) The effect of C. butyricum after macrophage clearance). RNA-sequencing revealed differentially expressed genes upregulated and downregulated (IDDF2024-ABS-0252 Figure 2. The role of C. butyricum on inflammation suppression and efferocytosis was mediated PPAR activation (A) The numbers of differentially expressed genes after C. butyricum treatment). KEGG enrichment results suggested that the PPAR pathway were significantly enriched and the expression of PPAR pathway-related genes was identified (IDDF2024-ABS-0252 Figure 2. The role of C. butyricum on inflammation suppression and efferocytosis was mediated PPAR activation (B,C) The result of enrichment analysis and differentially expressed genes that enriched in PPAR pathway). C. butyricum upregulated the expression of PPARδ and PPARγ, not PPARα (IDDF2024-ABS-0252 Figure 2. The role of C. butyricum on inflammation suppression and efferocytosis was mediated PPAR activation (D-F) The relative expression of genes). Furthermore, PPARγ inhibitor GW9662 instead of PPARδ inhibitor GSK3787 could prevent the role of C. butyricum in inflammation suppression and macrophage efferocytosis promotion (IDDF2024-ABS-0252 Figure 2. The role of C. butyricum on inflammation suppression and efferocytosis was mediated PPAR activation (G,H) The weight loss and colon length of mice). Conclusions Our findings demonstrated that C. butyricum attenuated intestinal inflammation and barrier injury by promoting M2 macrophage polarization and efferocytosis, which is partly mediated by PPARγ activation.