NFKBIA Centered Monocyte States Define a Single Cell Validated Oxidative Stress Signature for Sepsis

Early diagnosis of sepsis remains difficult because clinical features, microbiology, and conventional inflammatory biomarkers are heterogeneous. We reanalyzed public blood transcriptomic datasets to test whether oxidative stress-related expression patterns could provide an interpretable host-response signal for sepsis. Oxidative stress-related genes were profiled in a discovery cohort, summarized with an oxidative stress score, and evaluated through comparative diagnostic modeling and external validation. MAPK1, NFKBIA, and RAF1 formed a compact three-gene signature and were incorporated into an interpretable nomogram. In the GSE6535 training cohort, the three-gene nomogram achieved good discrimination (AUC, 0.860), while performance in the independent GSE54514 cohort was acceptable but moderate (AUC, 0.708), supporting cautious cross-dataset transportability. Immune and pathway analyses associated the signature with neutrophil-related inflammatory activity, translational regulation, and cellular stress-response programs. Complementary single-cell RNA-seq analysis localized oxidative stress activity and MAPK1/NFKBIA/RAF1 expression to discrete monocyte states, with coordinated NF-kB/NRF2-related activity, inflammatory ligand signals, trajectory patterns, and NFKBIA-centered network features supporting biological plausibility. These findings suggest that the MAPK1/NFKBIA/RAF1 signature may provide an interpretable auxiliary host-response signal for sepsis diagnosis, while prospective clinical and experimental validation remains required.