MCC950 ameliorates cognitive function by reducing white matter microstructure damage in rats after SAH

Single-Cell Transcriptomics Revealed White Matter Repair Following Subarachnoid Hemorrhage

Existing research indicates the potential for white matter injury repair during the subacute phase following subarachnoid hemorrhage (SAH). However, elucidating the role of brain cell subpopulations in the acute and subacute phases of SAH pathogenesis remains challenging due to the cellular heterogeneity of the central nervous system. In this study, single-cell RNA sequencing was conducted on SAH model mice to delineate distinct cell populations. Gene Set Enrichment Analysis was performed to identify involved pathways, and cellular interactions were explored using the CellChat package in R software. Validation of the findings involved a comprehensive approach, including magnetic resonance imaging, immunofluorescence double staining, and Western blot analyses. This study identified ten major brain clusters with cell type-specific gene expression patterns. Notably, we observed infiltration and clonal expansion of reparative microglia in white matter-enriched regions during the subacute stage after SAH. Additionally, microglia-associated pleiotrophin (PTN) was identified as having a role in mediating the regulation of oligodendrocyte precursor cells (OPCs) in SAH model mice, implicating the activation of the mTOR signaling pathway. These findings emphasize the vital role of microglia-OPC interactions might occur via the PTN pathway, potentially contributing to white matter repair during the subacute phase after SAH. Our analysis revealed precise transcriptional changes in the acute and subacute phases after SAH, offering insights into the mechanism of SAH and for the development of drugs that target-specific cell subtypes.

Remote Ischemic Post-conditioning Reduces Cognitive Impairment in Rats Following Subarachnoid Hemorrhage: Possible Involvement in STAT3/STAT5 Phosphorylation and Th17/Treg Cell Homeostasis

The inflammatory response following subarachnoid hemorrhage (SAH) may lead to Early Brain Injury and subsequently contribute to poor prognosis such as cognitive impairment in patients. Currently, there is a lack of effective strategies for SAH to ameliorate inflammation and improve cognitive impairment in clinical. This study aims to examine the inhibitory impact of remote ischemic post-conditioning (RIPostC) on the body's inflammatory response by regulating Th17/Treg cell homeostasis after SAH. The ultimate goal is to search for potential early treatment targets for SAH. The rat SAH models were made by intravascular puncture of the internal carotid artery. The intervention of RIPostC was administered for three consecutive days immediately after successful modeling. Behavioral experiments including the Morris water maze and Y-maze tests were conducted to assess cognitive functions such as spatial memory, working memory, and learning abilities 2 weeks after successful modeling. The ratio of Th17 cells and Treg cells in the blood was detected using flow cytometry. Immunofluorescence was used to observe the infiltration of neutrophils into the brain. Signal transducers and activators of transcription 5 (STAT5) and signal transducers and activators of transcription 3 (STAT3) phosphorylation levels, receptor-related orphan receptor gamma-t (RORγt), and forkhead box protein P3 (Foxp3) levels were detected by Western blot. The levels of anti-inflammatory factors (IL-2, IL-10, IL-5, etc.) and pro-inflammatory factors (IL-6, IL-17, IL-18, TNF-α, IL-14, etc.) in blood were detected using Luminex Liquid Suspension Chip Assay. RIPostC significantly improved the cognitive impairment caused by SAH in rats. The results showed that infiltration of Th17 cells and neutrophils into brain tissue increased after SAH, leading to the release of pro-inflammatory factors (IL-6, IL-17, IL-18, and TNF-α). This response can be inhibited by RIPostC. Additionally, RIPostC facilitates the transfer of Treg from blood to the brain and triggers the release of anti-inflammatory (IL-2, IL-10, and IL-5) factors to suppress the inflammation following SAH. Finally, it was found that RIPostC increased the phosphorylation of STAT5 while decreasing the phosphorylation of STAT3. RIPostC reduces inflammation after SAH by partially balancing Th17/Treg cell homeostasis, which may be related to downregulation of STAT3 and upregulation of STAT5 phosphorylation, which ultimately alleviates cognitive impairment in rats. Targeting Th17/Treg cell homeostasis may be a promising strategy for early SAH treatment.