RAB13 regulates macrophage polarization in sepsis.

To select the core target (RAB13) in sepsis patients' peripheral blood and investigate its molecular functions and possible mechanisms. The peripheral blood of sepsis patients (n = 21) and healthy individuals (n = 9) within 24 h after admission were collected for RNA-seq, and differential gene screening was performed by iDEP online analysis software (P < 0.01; log2FC ≥ 2) and enrichment analysis, the potential core target RAB13 was screened out. The association between RAB13 expression and sepsis severity was explored using multiple datasets in the GEO database, and survival analysis was conducted. Subsequently, peripheral blood mononuclear cells (PBMCs) from sepsis and control groups were isolated, and 10 × single-cell sequencing was used to identify the main RAB13-expressing cell types. Finally, LPS was used to stimulate THP1 cells to construct a sepsis model to explore the function and possible mechanism of RAB13. We found that RAB13 was a potential core target, and RAB13 expression level was positively associated with sepsis severity and negatively correlated with survival based on multiple public datasets. A single-cell sequencing indicated that RAB13 is predominantly localized in monocytes. Cell experiments validated that RAB13 is highly expressed in sepsis, and the knockdown of RAB13 promotes the polarization of macrophages towards the M2 phenotype. This mechanism may be associated with the ECM-receptor interaction signaling pathway. The upregulation of RAB13 in sepsis patients promotes the polarization of M2-like macrophages and correlates positively with the severity of sepsis.