Adhesion-Related Pathways and Functional Polarization of Astrocytes in Traumatic Brain Injury: Insights from Single-cell RNA Sequencing.

Traumatic brain injury (TBI) induces profound functional heterogeneity in astrocytes, yet the regulatory mechanisms underlying this diversity remain poorly understood. In this study, we analyzed single-cell RNA sequencing data from the cortex and hippocampus of TBI mouse models to characterize astrocyte subtypes and their functional dynamics. We identified two major reactive subtypes: A1 astrocytes, enriched in inflammatory response, synaptic regulation, and neurodegenerative disease-related pathways; and A2 astrocytes, enriched in lipid metabolism, extracellular matrix (ECM) remodeling, and phagosome formation pathways. These functional differences were consistently observed across datasets with varying injury severities. Notably, adhesion-related pathways-including gap junctions, adherens junctions, and calcium-dependent adhesion-showed significant subtype-specific expression patterns and temporal shifts. Pseudotime trajectory analysis further suggested a potential transition between A1 and A2 states, accompanied by dynamic regulation of adhesion-related genes. Our findings highlight the complex and context-dependent roles of astrocytes in TBI and propose cell adhesion as a key modulator of astrocyte functional polarization.