The dynamic changes of serum levels of PD-1/PD-L1 correlate with the therapeutic effectiveness of antibiotics in patients with sepsis.

BACKGROUND: Sepsis-induced immunosuppression is a significant contributor to mortality, with the programmed cell death protein 1 and its ligand (PD-1/PD-L1) pathway playing a central role in T-cell exhaustion. While their dynamics as biomarkers for monitoring treatment response in specific infections, such as Enterobacteriaceae-induced sepsis, remain unclear. MATERIALS AND METHODS: This study enrolled 63 patients with Enterobacteriaceae septicemia and 59 healthy controls. Serum levels of sPD-1/sPD-L1 were quantified at admission (Day 0) and on Days 3, 7, and 14. Patients were stratified into responders and non-responders based on clinical outcomes. RESULTS: At Day 0, sepsis patients had significantly higher levels of sPD-1 and sPD-L1 compared to healthy controls (p < 0.001). Longitudinal analysis revealed that patients who responded favorably to treatment exhibited a significant progressive decline in both biomarkers over the 14-day period. In contrast, non-responders maintained persistently elevated levels. Furthermore, initial sPD-1/sPD-L1 concentrations positively correlated with SOFA score, lactate level and PCT level. Furthermore, the analysis showed that the antibiotics β-lactam/β-lactamase inhibitor and carbapenem might not directly influence the sPD-1/sPD-L1 levels. CONCLUSION: Serum sPD-1 and sPD-L1 levels are significantly elevated in Enterobacteriaceae sepsis and dynamically decreased in patients responding to therapy. These findings underscore their potential as valuable prognostic biomarkers for monitoring immune reconstitution and treatment efficacy.