The Role Of Ubiquitin Carboxyl Terminal Hydrolase L1 In The Development Of Hypertension And Vascular Remodeling And The Underlying Mechanism

Background Vascular remodeling is the pathophysiological basis of hypertension and its complications and inflammation plays an important role in vascular remodeling.Angiotensin Ⅱ is a strong pro-inflammatory factor involved in the occurrence and development of hypertension.UCH-L1(Ubiquitin carboxyl-terminal hydrolase L1)is an important member of the ubiquitination enzyme family.Recent studies have shown that UCH-L1 is involved in cardiovascular diseases such as cardiac hypertrophy and atrial fibrillation by activating inflammatory signaling pathways,but its role in the hypertensive vascular remodeling and dysfunction remains unclear.Aims To investigate the role and mechanism of UCH-L1 in vascular remodeling and dysfunction in hypertension.To identify whether UCH-L1 can be used as a new target for the effective control of hypertension.Methods:1.Animal model UCH-L1 knockdown mice(UCH-L1+/-),bone marrow chimeramice and C57BL/6J were treated with a UCH-L1 specific antagonist LDN of 8-10 weeks were used to construct a model of hypertension by subcutaneous infusion of angiotensin Ⅱ for 14 days at a dose of 490 ng/kg/min or DOCA-salt treatment for 21 days.2.Blood pressure The systolic blood pressure of mice was measured by radiotelemetry or tail-cuff system.3.Examination of tissue pathology and immune cells Hematoxylin and eosin(H&E)staining was used to observe the infiltration of vessel interstitial inflammatory cells.Masson‘s trichrome stain was performed to analyze fibrosis in vascular tissue.Immunohistochemistry was performed to analyze macrophage recruitment.The number of immunoinflammatory cells in vascular the tissue was analyzed by flow cytometry.4.Analysis of gene expression Real-time quantitative PCR was used to detect the expression levels of genes related to vascular fibrosis and inflammation.5.Vascular relaxation studies The isolated thoracic aorta was cut into 4 mm segments and mounted on force transducers in organ chambers.After stimulation by noradrenaline to detect the constriction function,vascular responses to increasing concentrations of acetylcholine and sodium nitroprusside were recorded to detect endothelial vasodilation.6.Statistical analysis All data are expressed as mean ± SEM.If data were normally distributed,the student t test was used to determine the significant difference between two groups.If the data were not normally distributed,the Mann-Whitney test was used.More than three groups of data were analyzed by ANOVA.Results1.Angiotensin Ⅱ treatment for 14 days,significantly upregulated the expression of UCH-L1 in the vascular tissues of the mice compared with sham control.2.Compared with the sham control mice,Ang Ⅱ treatment markedly induced elevation of arterial blood pressure,vascular fibrosis,inflammatory response which was manifested by the increased infiltration of macrophages and expression of proinflammatory cytokines(IL-1β,IL-6,TNF-α)in the vascular tissue,oxidative stress(increased DHE densitity and expression of NADPH oxidases NOX1 、 NOX2 and NOX4)and vascular endothelial systolic dysfunction.Conversely,these pathological changes and functional abnormalities were significantly reduced in the UCH-L1 knockdown mice.3.Therapeutic administration of UCH-L1 specific inhibitor LDN blunts Ang Ⅱ induced hypertension,vascular wall thickness,fibrosis,inflammatory response and oxidative stress compared with the vehicle-treated C57BL/6J mice after Ang Ⅱ infusion.4.Compared with wild-type mice,UCH-L1 knockdown observably reduced the arterial blood pressure,vascular fibrosis,the expression of pro-inflammatory cytokines and oxidative stress by DOCA-salt treatment.5.Widetype mice transplanted with UCH-L1 knockdown bone marrow(BM)cells had a lower arterial blood pressure,and improvement of vessel fibrosis,inflammatory cell infiltration,oxidative stress and vascular dysfunction,compared with widetype transplanted with widetype BM cells.Conclusions The present study demonstrates a critical role of UCH-L1 in Ang Ⅱ or DOCAsalt induced hypertensive vascular remodeling.Mechanistically,Ang Ⅱ treatment induces the upregulation of UCH-L1,which recruits and activates bone-marrowderived macrophages to the periphery of the blood vessels that results in vascular wall thickness,fibrosis,inflammatory response and oxidative stress,thereby leading to vascular remodeling and dysfunction.Thus,selective inhibition of UCH-L1 activity represents a new potential target for treating vascular remodeling in hypertension.