Skull bone marrow-derived IL-10⁺VEGF-α⁺neutrophils exert neuroprotective effects in aged TBI

Aging increases the risk and worsens the prognosis of traumatic brain injury. Neutrophils contribute to the secondary neuroinflammatory response after TBI. Nevertheless, the biological functions and underlying mechanisms contributing to the age-related heterogeneity of neutrophils in elderly individuals with TBI remain inadequately understood. The study identified a unique neutrophil subpopulation with elevated IL-10 expression, functionally enriched in young TBI tissues. CellChat analysis revealed significant intercellular communication between IL-10⁺neutrophils and endothelial cells, with elevated expression of Vegfa. GO/KEGG analysis exhibit characteristics associated with reducing inflammatory responses, inhibiting oxidative stress, promoting angiogenesis and tissue remodeling. The IL-10 Ab intervention led to a deterioration in neurological outcomes in young TBI. SCENIC analysis demonstrated that the transcription factor NR2C2 regulates the distinct neutrophils. Transplantation experiments using GFP⁺ mouse bone marrow indicated that it could be a source of skull bone marrow. Transcriptome sequencing confirmed that phenotypic changes in dHL-60 cells, following NR2C2 overexpression, activate signaling pathways involved in Complement and coagulation cascades Immune, Hematopoietic cell lineage Immune, Jak STAT and Toll like receptor. The regulation of NR2C2 was achieved through siRNA knockdown technology to mitigate the effects of NO-prednisolone. NR2C2 overexpression, induced by NO-prednisolone, leads to the production of IL-10⁺VEGF-α⁺neutrophils in the brain tissue of aged mice with TBI, resulting in improved blood-brain barrier integrity, reduced pathological changes in brain tissue injury, inhibition of neuroinflammation, and significant enhancement of neurobehavioral function. CONCLUSION: This study explored the role of a specific subset of skull-derived IL-10⁺VEGF-α⁺neutrophils in TBI, with an emphasis on age-related immune cell heterogeneity. The findings indicate that these neutrophils exhibit anti-inflammatory and reparative properties, and are associated with the transcription factor NR2C2 and the potential therapeutic agent NO-prednisolone. This research provides potential interventions for treating TBI in the aging population.