The Role Of Sphingosine 1-Phosphate Receptor 2 In The Pathogenesis Of Thoracic Aortic Dissection And Related Mechanisms

1 The study on the expression difference of sphingosine 1-phosphate receptor 2 between pathological tissues of thoracic aortic dissection and normal control tissuesObjective:Thoracic aortic dissection(TAD)is a severe clinical condition that is unpredictable and frequently results in a fatal outcome.In recent years,the molecular mechanisms of TAD have been widely studied,accumulating evidences showed that TAD is an inflammatory disease.Sphingosine-1-phosphate receptor 2(S1PR2)signaling acts as an accomplice in multiple inflammatory conditions including a range of vascular disease.Here,we explored the expression difference of S1PR2 between the pathological tissues of TAD lesions and normal control tissues.Methods:The fresh TAD specimens(n=10)were dissected during surgery,and control ascending aortic tissues without aortic aneurysm/dissection,collagen disease,or previous aortic repair were obtained from heart transplantation donors(n=6).Three-week-old male C57BL/6J mice purchased from the Sibeifu Laboratory Animal Technology Company(Beijing,China)were randomly divided into following groups:(1)the CON group(n=6,administered normal drinking water);(2)the TAD group(n=10,sequentially administeredβ-aminopropionitrile fumarate+Angiotensin Ⅱ).Finally,the expression differences of S1PR1,S1PR2 and S1PR3 between the pathological tissues of TAD patients and mouse model and normal control tissues were analyzed.Results:Among participants that provided aorta specimens,there was no significant difference in demographics,smoking history,body mass index and comorbidities.During four-week animal experiments,no difference was found in body weight and systolic blood pressure measured before AngⅡ administration between two experimental groups.Additionally,80%of mice in the TAD group developed TAD or died due to aortic rupture.Western blot analysis,RT-qPCR and immunohistochemistry experiments revealed that S1PR2 was highly expressed in the pathological tissues of TAD patients and mouse model when compared with control aortic tissues,while no significant expression difference of S1PR1 and S1PR3 was observed in two groups.Conclusion:S1PR2 was highly expressed in the pathological tissues of TAD patients and mouse model when compared with control aortic tissues,while no significant expression difference of S1PR1 and S1PR3 was observed in two groups.2 The Role of Sphingosine 1-Phosphate Receptor 2 in the Pathogenesis of Thoracic Aortic Dissection and Related MechanismsObjective:Thoracic aortic dissection(TAD)is due to the degeneration of the media layer of aortic wall and causes a high mortality rate,while molecular mechanisms for the development of TAD are still not completely understood.Till now,despite significant improvement in surgical and endovascular repair,no pharmacologic therapy has been proven to be efficacious in preventing disease progression and reducing morbidity and mortality in clinical conditions.Numerous evidences showed that inappropriate inflammation is the central trigger in the TAD formation.Sphingosine-1-phosphate receptor 2(S1PR2)signaling acts as an accomplice in multiple inflammatory conditions.Furthermore,we found that S1PR2 was highly expressed in the pathological tissues of TAD patients and mouse model in the firsr part of our study.Here,we explored the effect of S1PR2 on the pathogenesis of TAD,and related mechanismsMethods:The fresh TAD specimens(n=10),control ascending aortic tissues(n=6),and the serum of TAD patients(n=67)and healthy volunteers(n=55)were colleted.Three-week-old male C57BL/6J mice purchased from the Sibeifu Laboratory Animal Technology Company(Beijing,China)were randomly divided into following groups:(1)the CON(vehicle)group(n=32,administered normal drinking water and vehicle);(2)the TAD+vehicle group(n=32,administered BAPN,AngⅡ,and vehicle);(3)the JTE013 group(n=32,administered BAPN,AngⅡ,and JTE013).The number of TAD cases and death cases due to TAD rupture were observed in each group.Pathological sections staining and terminal deoxynucleotidyl transferase dUTP nick-end labeling(TUNEL)staining were used to evalute the architecture of aortic wall.The infiltration of inflammatory cells,expression of inflammatory factors,neutrophil extracellular traps(NETs)density and angiogenesis were analyzed by western blot,quantitative real-time PCR(qRT-PCR)or immunohistochemistry experiments,separately.Further,the possible association between S1PR2 signaling and NETs in the TAD formation was analyzed.Results:Among participants that provided aorta specimens,there was no significant difference in all clinical characteristics.Among participants that provided blood samples,significantly elevated SBP,DBP,hs-CRP,D-Dimer,aortic diameter,blood counts included white blood cell,neutrophil,monocytes and decreased lymphocytes count were detected in TAD patients when compared with the matched healthy volunteers.While no significant difference occurred for the comparisons of other clinical characteristics.In the TAD mouse model,JTE013,a specific S1PR2 antagonist,not only blunted TAD formation and aortic rupture,but also preserved elastic fiber architecture,reduced smooth muscle cells apoptosis level,and mitigated aortic wall inflammation.Augmented tissue protein expression of SPHK1(a rate-limiting enzyme of S1P),citrullinated histone H3(a specific marker of NETs),and serum S1P,CitH3 were detected in TAD patients.Surgical repair normalized the serum S1P and CitH3 levels.Immunofluorescence staining revealed that S1PR2 colocalized with NETs.The protein expression levels of SPHK1 and serum S1P levels positively correlated with protein expression and serum levels of CitH3,separately.Furthermore,JTE013 treatment reduced NETs accumulation.Conclusion:Inhibiting S1PR2 attenuates TAD formation and prevents aortic rupture.Targeting S1PR2 may provide a promising treatment strategy against TAD.