Systematic analysis of programmed cell death-related genes in sepsis reveals immune heterogeneity and enables patient...

Sepsis is a life-threatening syndrome characterized by dysregulated host response to infection. Programmed cell death (PCD) pathways, including apoptosis, necroptosis, and pyroptosis, play a critical role in sepsis pathophysiology. However, the crosstalk between PCD, metabolic reprogramming, and immune heterogeneity remains poorly understood.

We analyzed transcriptomic data from the GSE57065 and GSE95233 datasets. Differentially expressed genes (DEGs) were intersected with programmed cell death-related genes (PCDRGs). Consensus clustering was performed to identify molecular subtypes. A risk stratification model was constructed using LASSO and Random Forest algorithms. The immune landscape was deconvoluted using CIBERSORT. To validate cellular mechanisms, we integrated single-cell RNA sequencing (scRNA-seq) data, analyzing cell type-specific expression, intercellular communication (CellChat), and pathway enrichment. Additionally, the reliability of the identified signature was verified in a murine sepsis model (burn injury combined with Pseudomonas aeruginosa infection) using quantitative real-time PCR (qPCR).

We identified 14 dysregulated PCDRGs in sepsis. Clustering based on these genes revealed two distinct patient subgroups: an "adaptive-dominant" cluster (enriched in T cell activation) and an "innate-dominant" cluster (enriched in neutrophil degranulation and heme metabolism). A 5-gene risk signature (IFNGR1, PYGL, JAK2, HMGB2, BMX) was constructed, which robustly stratified patients in the discovery and external validation cohorts (AUC > 0.97). Experimental validation in septic mice confirmed that the expression levels of all five hub genes were significantly upregulated in peripheral blood, consistent with the human transcriptomic findings. High-risk patients exhibited severe immune imbalance characterized by neutrophil/monocyte expansion and lymphocyte depletion. Single-cell analysis confirmed that hub genes were predominantly expressed in myeloid lineages. Furthermore, high-risk patients displayed intensified Monocyte-Dendritic Cell (DC) crosstalk driven by inflammatory signaling, with transcriptional programs in these cells converging on neutrophil degranulation pathways.

This study establishes a robust PCDRG-based risk signature that captures the immune-metabolic heterogeneity of sepsis. The signature enables patient stratification and reflects disease-associated immune states. Our findings suggest a potential association between dysregulated PCD genes in myeloid cells and an innate immune-dominant, hyper-inflammatory phenotype, providing potential biomarkers and therapeutic insights for sepsis.