CXCR4+ PD-L1+ neutrophils are increased in non-survived septic mice

The dysregulated host response to infections can lead to sepsis, a complex disease characterized by a spectrum of clinical phenotypes associated with the host immune response variability and outcomes. This heterogeneity poses challenges for implementing specific therapeutic approaches. While clinical sepsis phenotypes are well distinguished, the mechanisms driving these heterogeneous responses remain poorly understood. Using an unbiased experimental approach, we analysed immune cell activation profiles in survived and non-survived CLP-septic to gain insights into the immunological mechanisms by which neutrophils contribute to the hyperinflammatory septic phenotype. Our finds reveal that non-survived septic mice exhibit increased frequencies of immature CXCR4+ PD-L1+ neutrophils and monocytes in the bloodstream, accompanied by an accumulation of trafficking-specific CXCR4+ PD-L1+ neutrophils into the lungs. The increased PD-L1 expression on CXCR4+ neutrophils is associated with increase of IFN-gamma signaling pathways. Additionally, the IFN-gamma and LPS promote an activation profile of CXCR4+ PD-L1+ neutrophils, exhibiting a phenotype associated with inflammation and organ damage. Notably, abrogating the IFN-gamma reduced susceptibility to CLP-sepsis and diminished PD-L1 expression on CXCR4+ neutrophils. This study provides molecular and functional insights into the immune cell activation profiles associated with the worsening of the septic hyperinflammatory phenotype experimental model. The CXCR4+ PD-L1+ neutrophils population and elevated plasmatic IFN-gamma levels highlighted here represent promising targets for therapeutic modulation in clinical sepsis hyperinflammatory phenotype.