Brain Tissue-Derived Exosomal Proteomics Identifies Chemotaxis-Associated Protein Changes After Traumatic Brain Injury: An Exploratory Hippocampal Transcriptomic Comparison.

Traumatic brain injury (TBI) involves both primary and secondary pathological processes, including hemorrhage, ischemia, edema, and neuroinflammation. Although tissue-derived exosomes have emerged as important mediators of intercellular communication within local tissue microenvironments, their role in TBI-associated inflammatory responses remains incompletely understood. This study integrated brain tissue-derived exosomal proteomics with publicly available hippocampal transcriptomic data to investigate the potential association between tissue-derived exosomes and chemotaxis-related inflammatory responses after TBI. Brain tissue-derived exosomes were isolated, characterized, and subjected to label-free proteomic analysis. Public hippocampal transcriptomic data from GSE173975 were analyzed, and differentially expressed proteins (DEPs) and genes (DEGs) were identified from the exosomal proteomic and transcriptomic datasets, respectively. Functional enrichment, co-enrichment, and protein-protein interaction network analyses were performed, followed by quantitative real-time PCR, exosomal western blotting, and Transwell migration assays for validation and functional assessment. In total, 190 DEPs and 465 DEGs were identified. Co-enrichment analyses highlighted immune- and inflammation-related processes, particularly chemotaxis-related processes and chemokine signaling. LGALS3 and ITGB2 were increased at the exosomal protein level in brain tissue-derived exosomes from TBI rats and also showed increased hippocampal mRNA expression, whereas CCL2, CCL3, and CCR5 were upregulated at the hippocampal mRNA level. Functionally, TBI-derived exosomes enhanced BV2 microglial migration in vitro. Overall, these findings suggest that injury-associated brain tissue-derived exosomes may be associated with chemotaxis-related inflammatory and pro-migratory responses after TBI.