EBV reactivation and immunoparalysis indicate a harmful immune endotype in sepsis.

BACKGROUND: Sepsis is increasingly recognized as a highly dynamic immunological disorder in which hyperinflammation and anti-inflammatory processes occur simultaneously. The clinical phenotype depends on which arm predominates at a given time, resulting in an early phase that is typically dominated by hyperinflammation and a subsequent phase characterized by hypoinflammation, also referred to as immunoparalysis (IP). Epstein-Barr virus (EBV) reactivation has been associated with an immunosuppressive status. However, its interaction with IP and resulting immune phenotypes remains poorly defined so far. In this current study, we investigated the temporal dynamics of EBV reactivation and IP status, and assessed their impact on immune signatures and mortality in sepsis.

METHODS: In this retrospective cohort of 124 intensive care unit (ICU) patients with sepsis, we performed analysis of EBV load by qPCR and analyzed the inflammatory stage by quantifying HLA-DR molecules on monocytes (mHLA-DR) using flow cytometry. Patients with < 5,000 mHLA-DR/monocyte were classified positive for immunoparalysis (IP+). Cytokine profiles and vital sign were analyzed in parallel. Patients were assigned to four sepsis groups based on EBV/IP status (EBV- IP-, EBV + IP-, EBV- IP+, EBV + IP+). Time-dependent Cox models (start-stop structure) were used to estimate hazard ratios (HR) for mortality, adjusted for age, sex and Sequential Organ Failure Assessment (SOFA) score. Cytokines and clinical markers were compared using Kruskal-Wallis and rank-based analyses.

RESULTS: EBV positivity was associated with higher hazard of death (HR 3.30, 95% CI 1.24-8.81, p = 0.0009), while IP showed a similar but nonsignificant trend (HR 2.14, 95% CI 0.93-4.90, p = 0.073). The combined EBV + IP+ group exhibited the highest mortality (HR 7.23, 95% CI 2.24-23.3, p = 0.0009). This group also showed the strongest cytokine activation (IL-6, IL-8, IL-10, IL-17 A, IL-18, MCP-1) and lowest mHLA-DR expression, indicating a mixed hyperinflammatory and immunosuppressed phenotype. In contrast, EBV- IP- patients displayed the most immunocompetent baseline profile.

CONCLUSION: Our preliminary findings suggest that EBV reactivation superimposed on immunoparalysis is associated with a harmful sepsis endotype combining excessive cytokine activity with impaired monocyte function. Further studies are needed to evaluate if the dynamic monitoring of EBV DNA and mHLA-DR expression may enable early identification of patients at highest risk and guide targeted immunomodulatory or antiviral interventions.