The Characteristics And Regulatory Mechanism Of Intracranial Aquaporins After Traumatic Brain Injury:Delineating At Single-Cell Level

ObjectiveTraumatic Brain Injury(TBI)is a common disease in modern society.Acute secondary cerebral edema is a common complication of TBI,which has a high mortality and disability rate.Currently,hypertonic drug dehydration and decompression of bone flares are common treatments,however,uncontrolled malignant cerebral edema still exists,resulting in poor prognosis.Aquaporin(AQPs)is recognized as a potential target for the prevention and treatment of cerebral edema,while no effective drug is available at present,and the regulatory mechanism of aquaporin is also unclear.In this study,single-cell sequencing was used to accurately analyze the types of aquaporins and their distribution in central nervous system,and to further explore the potential regulatory mechanisms.This study provides theoretical support for clinical drug development and clinical prevention and treatments.MethodsIn this study,Single-cell RNA sequencing of 3 TBI mice and 3 sham mice were included to analyze the differences of transcriptome of before and after TBI.Through data quality control and dimensionality reduction clustering,cellular components and subcellular types were Identified and annotated.The functional differences of different cell types between TBI group and Sham group were demonstrated from the perspectives of differential gene expression,transcriptional factor activity and pathway variation analysis.Based on the differential expression of AQP4 in astrocytes,prediction of transcription factors and enrichment of pathways,the potential mechanism of AQP4 up-regulation after TBI was proposed.Through the crosstalk between cell populations,we further reveal the different roles of two kinds of astrocytes after TBI.ResultsWe identified 5 main cell types and a total of 24 cell subtypes in mouse brain tissue.By observing the distribution and expression of AQP4,we proposed that the cerebrospinal fluid barrier composed of protoplasmic astrocytes and ependymal cells is the main way of fluid exchange between the center and external fluid after TBI.Through analysis of the transcription characteristics of astrocytes,we proposed that vasopressin stimulation after TBI may be an important factor leading to up-regulation of AQP4 in protoplasmic astrocytes.It is also found that fibro astrocytes mainly protect and support nerve cells after TBI,while protoplasmic astrocytes are associated with intracranial fluid regulation.ConclusionIn this study,the subtypes of central nervous system aquaporins and their distribution among different cell types were identified at the single-cell level after TBI.Two subtypes of astrocytes were identified and the specific functions of the two subtypes were proved.Vasopressin has been shown to be a potential mechanism of AQP4 up-regulation in protoplasmic astrocytes.Our study provides a new direction for the regulation of aquaporins in central nervous system.