A Preliminary Exploration Of Peripheral Blood GFAP/UCHL1 Proteins And Gut Microbiota As The Predictive Biomarkers Of Hypertensive Brain Injury

BACKGROUND AND PURPOSEHypertension is not only the most common chronic disease but also the most important risk factor for cerebrovascular disease.Hypertensive brain complications such as stroke,cerebrovascular abnormalities,dementia,etc.,are the main causes of death in hypertensive patients.At present,there are few indicators for early prediction of hypertensive brain injury in clinical practice,and the diagnosis is mainly made through clinical symptoms and signs,magnetic resonance imaging technology,cerebrovascular imaging,etc.However,these detection methods are limited to a certain extent.Current studies suggest that neuroinflammation and gut microbiota are involved in the progression of hypertension.When hypertensive brain injury occurs,specific tissue components or products released from damaged brain tissues can enter the cerebrospinal fluid or blood,and these components may be used as predictors of hypertensive brain damage.At present,biomarkers such as S100B protein,glial fibrillary acidic protein(GFAP),and ubiquitin carboxy-terminal hydrolase L1(UCHL1)have been isolated from serum and cerebrospinal fluid,but it is not clear whether they can be used to predict hypertensive brain damage.The purpose of this study was to investigate whether GFAP,UCHL1 protein and gut microbiota can be used as biomarkers of hypertensive brain injury,and the role of astrocytes/enteroglias in hypertensive brain injury,thereby providing theoretical foundation for the early prediction prevention and treatment of hypertensive brain injury.METHODS AND RESULTS6-week-old male spontaneously hypertensive rats(SHR)and normal blood pressure Kyoto rats(WKY)were randomly divided into four different groups,WKY regular feeding(W),WKY high-salt feeding(WN),SHR regular feeding(S),SHR high-salt feeding(SN).The body weight,blood pressure,GFAP protein and UCHL1 protein content in peripheral blood of the four groups were monitored for 12 weeks.MRI was performed at the end of the experiment.Sequencing of the 16s rRNA gene was used to detect changes in the gut microbiota,and the levels of nerve injury and neuroinflammation were analyzed by ELISA,immunofluorescence,and Tunel.1.Elevated blood pressure was observed in the three group(WN,S and SN),while the increase of blood pressure in SN group was more obvious.At the 8th week of the experiment,the weight of rats in SN group began to decrease.The neurological damage in the SN group was far more severe than that in the other groups.MRI scan revealed multiple micro-hemorrhage points in the brain tissue of the SN group.2.The contents of GFAP and UCHL1 in sera of the WN group,the S group and the SN group increased with the processing time,and the protein levels of the S group and the SN group were significantly higher than those of the W group at the 8th week of the experiment(P<0.05).3.There are differences in the types and abundance of the gut microbiota of the four groups of rats.The abundance of Proteobacteria in the SN group increased.Apart from this,the abundance of Lachnospiraceae,Clostridium-UCG-014,Lachnospiraceae_NK4A136_group and Blautia decreased significantly,while Escherichia_shigella and Klebsiella increased(P<0.05).4.The levels of inflammatory factors TNF-α,IL-6 and GFAP,UCHL1 and S100B proteins in the brain tissue and small intestine tissue of SHR increased(P<0.05).HE and Tunel staining showed neuronal damage and increased apoptotic cells in the SN group.Immunofluorescence staining showed that astrocytes and EGCs in the WN group,the S group,and the SN group were obviously activated and proliferated.CONCLUSIONS1.High-salt diet promotes the increase of SHR blood pressure and aggravates brain damage.The expression of GFAP and UCHL1 proteins were related to the severity of brain injury,and they can be used for early prediction of brain injury.2.Under the conditions of high salt and hypertension,the type and abundance of the gut microbiota of Spontaneously hypertensive rats changed significantly,and the gut microbiota participated in hypertensive brain injury through the gut-brain axis.3.Activated glial cells play an important role in the gut-brain axis nervous system damage in hypertensive rats by enhancing the expression of GFAP,S100B protein and increasing the level of inflammatory factors.