Identification and functional experimental verification of efferocytosis-related diagnostic biomarkers for sepsis

Sepsis is associated with substantial global morbidity and mortality, imposing a severe socioeconomic burden worldwide. Efferocytosis refers to the clearance of apoptotic cells by phagocytes, which is critical for maintaining immune homeostasis and resolving inflammation. Dysfunction of efferocytosis has been implicated in the pathogenesis of sepsis. This study aimed to investigate the diagnostic value of efferocytosis-related genes in sepsis.

Gene expression data on sepsis patients and efferocytosis-related genes were acquired from GEO and GeneCards databases. Differential expression analysis and Venn analysis were applied to identify efferocytosis-related differentially expressed genes (DEGs) between healthy control and sepsis. LASSO regression was employed to screen diagnostic genes, and then the diagnostic value of these genes in sepsis was evaluated in internal and external cohorts. We also explored differences in immune cells infiltration as well as immune checkpoints between control and sepsis. Finally, miRNAs and drug molecules that have regulatory relationships with genes were predicted.

Five genes (ADAM9 (ADAM metallopeptidase domain 9), GPR18 (G protein-coupled receptor 18), ID3 (inhibitor of DNA binding 3), MIR21 (the transcription level of MIR21 gene), and S1PR5 (sphingosine-1-phosphate receptor 5)) were identified as efferocytosis-related candidate diagnostic genes and confirmed to have favorable discriminative performance in the discovery cohorts (all AUC > 0.8). GSEA analysis showed that these genes were mainly involved in metabolism-related pathways, such as pantothenate and coA biosynthesis. Moreover, these genes were significantly associated with some immune cells (such as resting NK cells and M0 macrophages) and immune checkpoints (such as PD-L1/PDCD1 and PD-L2/PDCD1LG2). Candidate genes ID3 and ADAM9 were regulated by multiple miRNAs. And ADAM9 was functionally verified in macrophage inflammatory models.

The five efferocytosis-related genes identified in this study show promising diagnostic value for sepsis, and ADAM9 was further functionally validated as a modulator of inflammation, migration, and efferocytosis in macrophages. These findings provide a useful reference for biomarker exploration, though the functional roles of GPR18, ID3, MIR21, and S1PR5 in sepsis remain to be investigated in future studies.