Background
Endotype classification becomes the cornerstone of understanding sepsis pathogenesis. Macrophage activation-like syndrome (MALS) and immunoparalysis are the best recognized major endotypes, so far. Interferon-gamma (IFNγ) action on tissue macrophages stimulates the release of the cytotoxic chemokine CXCL9. It was investigated if this mechanism may be an independent sepsis endotype.
Methods
In this cohort study, 14 patient cohorts from Greece, Germany and Italy were studied. The cohorts were 2:1 randomly split into discovery and validation sets. Sepsis was defined by the Sepsis-3 definitions and blood was sampled the first 24 h from meeting the Sepsis-3 definitions. Concentrations of IFNγ, CXCL9, IP-10 (IFNγ induced protein-10), soluble CD163 and ferritin were measured. The endotype of IFNγ-driven sepsis (IDS) was defined in the discovery set as the combination of a) blood IFNγ above a specified cut-off associated with the minimal risk for immunoparalysis (defined as ≥8000 HLA-DR receptors on CD45/CD14-monoytes); and b) increase of CXCL9.