Single-cell sequencing reveals the optimal time window and mechanism of anti-inflammatory treatment in spinal cord injury

Though the occurrence of neuroinflammation after spinal cord injury (SCI) is essential for antigen clearance and tissue repair, excessive inflammation results in cell death and axon dieback. The effect of anti-inflammatory medicine utilized in clinical treatment remains debatable owing to the inappropriate therapeutic schedule that does not align with the biological process of immune reaction. A better understanding of the immunity process is critical to promote effective anti-inflammatory therapeutics. However, cellular heterogeneity, which results in complex cellular functions, is a major challenge. In this study, we performed single-cell RNA sequencing by profiling the tissue proximity to the injury site at different time points after SCI. Depending on the analysis of single-cell data and histochemistry observation, we proposed an appropriate time window for anti-inflammatory medicine treatment. We also verified the mechanism of typical anti-inflammatory medicine MPSS, which was found attributable to the activation inhibition of cells with pro-inflammatory phenotype through the down-regulation of pathways such as TNF, IL2, and MIF. These pathways could also be provided as targets for anti-inflammatory treatment. Collectively, we provide a therapeutic schedule of 1–3 dpi (days post-injury) to argue against classical early pulse therapy and provide some pathways for target therapy in the future. Overall design: Spinal cord tissue at 1,3,7 days post-injury and intact tissue was used in single-cell sequency for analysis of immunity reaction through SCI. MPSS and PBS treated spinal cord was used for the analysis of medicine mechanism.