Proteomics and bioinformatics reveal insights into neuroinflammation in the acute to subacute phases in rat models of spinal cord contusion injury

Neuroinflammation is recognized as a hallmark of spinal cord injury (SCI). Although neuroinflammation is an important pathogenic factor that leads to secondary injuries after SCI, neuroprotective anti-inflammatory treatments remain ineffective in the management of SCI. Moreover, the molecular signatures involved in the pathophysiological changes that occur during the course of SCI remain ambiguous. The current study investigated the proteins and pathways involved in C5 spinal cord hemi-contusion injury using a rat model by means of 4-D label-free proteomic analysis. Furthermore, two Gene Expression Omnibus (GEO) transcriptomic datasets, Western blot assays, and immunofluorescent staining were used to validate the expression levels and localization of dysregulated proteins. The present study observed that the rat models of SCI were associated with the enrichment of proteins related to the complement and coagulation cascades, cholesterol metabolism, and lysosome pathway throughout the acute and subacute phases of injury. Intriguingly, the current study also observed that 75 genes were significantly altered in both the GEO datasets, including ANXA1, C1QC, CTSZ, GM2A, GPNMB, and PYCARD. Further temporal clustering analysis revealed that the continuously upregulated protein cluster was associated with immune response, lipid regulation, lysosome pathway, and myeloid cells. Additionally, five proteins were further validated by means of Western blot assays and the immunofluorescent staining showed that these proteins coexisted with the F4/80+ reactive microglia and infiltrating macrophages. In conclusion, the proteomic data pertaining to the current study indicate the notable proteins and pathways that may be novel therapeutic targets for the treatment of SCI.