The Role And Mechanism Of Caveolin-1 In Angiotensin ? Induced Cerebral Small Vessel Disease

Cerebral small vessel disease(CSVD)is a common disease existing in people over 90 years old.Hypertension is an important factor in the occurrence of CSVD.The pathological characteristics of CSVD disease are complex.The main pathological changes are cognitive dysfunction,blood-brain barrier(BBB)damage,and neuroinflammatory response.Vascular dementia caused by CSVD is the second-largest type of dementia after Alzheimer's disease.Cognitive dysfunction is the main cause of the serious burden of life,but there is no standard strategy for the treatment of CSVD.Caveolin-1(Cav-1)is mainly expressed in endothelial cells in brain tissue,which is involved in signal transduction and molecular transport of various physiological processes.In recent years,it has been found that Cav-1 is related to the pathological process of neurodegenerative diseases and plays an important role in cognitive function,while iron overload is a common phenomenon in neurodegenerative diseases.The purpose of this study is to explore the role of Cav-1 and iron overload in CSVD,especially in cognitive function,to provide new ideas for the treatment of CSVD disease.1.NR improves Ang ? induced CSVD: after infused with angiotensin ?(Ang ?)for 28 days in mice,the cognitive function of mice was evaluated by behavioral methods;the integrity of BBB,the fluorescence intensity of MBP and neuroinflammatory molecules(GFAP and IBA1)were detected by immunofluorescence;and the expression TNF-?,ASM,Cav-1 and Ferritin were detected by immunoblotting.The behavioral tests showed the recognition ability of mice to novel objects decreased significantly after Ang ? infused for 28 days.Immunofluorescence analysis showed that FITC-dextran could penetrate brain tissue,and the fluorescence intensity of GFAP and IBA1 increased significantly,and the fluorescence intensity of MBP decreaed.The results of immunoblotting showed that the expression of TNF-? increased significantly.The above results demonstrated that mice infused with Ang ? could lead to cognitive dysfunction,BBB leakage and neuroinflammatory response,and these pathological manifestations were consistent with the phenotype of CSVD.Furthermore,nicotinamide riboside(NR)was used to treat mice that infused with Ang ?.The results showed that NR supplementation could not only reduce the expression of CSVD in mice but also reduce the iron overload caused by Ang ?.The mechanism may be through the regulation of the ASM / Cav-1 / Ferritin pathway.2.Cav-1 regulates the cognitive dysfunction caused by Ang ?: the previous study found that mice infused with Ang ? for 28 days not only showed cognitive dysfunction but also iron overload in brain tissue.It is speculated that iron overload may be the cause of cognitive dysfunction.Immunoblotting analysis showed that inhibition of Cav-1 expression by daidzein could aggravate the iron overload caused by Ang ?,while the activation of Cav-1 by AP-Cav-1 could reduce the iron overload caused by Ang ?.Behavioral tests showed that the cognitive function of mice was improved after AP-Cav-1 or Deferoxamine(DFO)treatment.The results of laser Doppler showed that the activation of Cav-1 could restore the decrease of cerebral blood flow(CBF)caused by Ang ?.Immunofluorescence showed that the activation of Cav-1 could increase the number of mature neurons in the hippocampus of mice.The above results showed that the activation of Cav-1 could reverse the abnormal iron metabolism and the cognitive dysfunction caused by Ang ? in mice.3.Cav-1 mediates iron metabolism in endothelial cells: it is not clear whether Cav-1 mediates iron transport or metabolism.Our results suggested that Cav-1 may mediate the regulation of iron metabolism,so we used siRNA to decrease the expression of Cav-1 in endothelial cells.Immunoblotting showed that Cav-1 knockdown could significantly upregulate the expression of Ferritin in endothelial cells,while the expression of iron transport protein(TfR1,FPN,and DMT1)had no significant changes.Immunoblotting results showed that Cav-1 knowndown significantly decreased the expression of FBXL5 related to IRP2 degradation.Living cell staining showed that Cav-1 knockdown could increase the concentration of divalent iron in mitochondria.These results suggested that Cav-1 mediates the regulation of iron metabolism in cells.To sum up,our data confirmed that the symptoms of mice caused by Ang ? were consistent with the pathological and behavioral manifestations of CSVD,and NR could improve these symptoms,which may be due to the regulation of Cav-1 expression and the iron metabolism.Moreover,we found for the first time that Cav-1 was related to iron metabolism in brain tissue.Activation of Cav-1 could increase the number of neurons in the hippocampus and improve the cognitive function in mice.The study of endothelial cells confirmed that the knockdown of Cav-1 can reduce the expression of FBXL5 and lead to the disorder of iron metabolism.Based on the above results,we demonstrated that Cav-1 mediated the pathological process and iron metabolism of CSVD caused by Ang ?,we speculate that Cav-1 is a potential target for the treatment of cognitive dysfunction in CSVD.