NEO1 modulates the A1 astrocyte polarization in subarachnoid hemorrhage through the cPLA2-MAVS signaling pathway

Neuroinflammation following subarachnoid hemorrhage (SAH) plays a critical role in multiple pathological pathways and poor prognosis. Several studies have indicated that resting astrocytes can polarize into at least two distinct phenotypes following SAH, pro-inflammatory A1 phenotype and anti-inflammatory A2 phenotype. However, the specific polarization patterns of astrocytes after SAH have not been fully elucidated. Targeting A1 astrocytes after SAH may represents a promising strategy for mitigating neuroinflammatory and enhancing neurological recovery. Our single-cell RNA sequencing revealed an increase in A1 astrocytes after SAH. Furthermore, the data suggested that NEO1 may be involved in astrocyte polarization. Then, we generated astrocyte-specific NEO1 conditional knockout (cKO) mice by crossing NEO1^fl/fl with GFAP-Cre mice. Using an intravascular puncture-induced SAH mouse model, we demonstrated that NEO1 downregulation significantly inhibits A1 astrocyte polarization and reduces associated inflammatory factor release. To investigate the mechanisms underlying NEO1-mediated astrocyte polarization, we performed transcriptome sequencing. This analysis revealed significantly decreased mRNA levels of cPLA2, MAVS, and NF-κB following NEO1 knockout in astrocyte. cPLA2-MAVS interaction plays an important role in activating the NF-κB transcriptional program. Based on these findings, we hypothesized that NEO1 functions through this signaling pathway. To validate our hypothesis, we overexpressed cPLA2 in primary astrocytes using lentiviral vectors and performed in vitro experiments. Results demonstrated that cPLA2 overexpression effectively reversed NEO1 knockout-induced suppression of A1 polarization. Furthermore, miglustat administration significantly attenuated neuroinflammation and improved neurological functional recovery following SAH. Collectively, our findings reveal that NEO1 inhibition alleviates A1 astrocyte polarization following SAH through the cPLA2-MAVS pathway.