Low-dose Aspirin Treatment Attenuates Rat Salt-Sensitive Hypertension Via Platelet COX-1 And Complement Cascade Pathway

Objective:As an effective anti-platelet drug,aspirin has been widely used in the prevention and treatment of various cardiovascular diseases,like myocardial infarction and stroke.while,the role of aspirin in salt-sensitive hypertension is still unclear.The pathogenesis of salt-sensitive hypertension is complex,which is associated with renal sodium dysfunction,increased sympathetic excitability,and abnormal immune system.Recent studies have been found that abnormal activation of platelets can participate in vascular lesions such as endothelial function damage,vascular sclerosis and vascular inflammation by inducing inflammatory responses,which promoted the development of various cardiovascular diseases.Clinical studies indicated that the platelet activity is enhanced in patients with salt-sensitive hypertension.The present study aim to investigate whether aspirin can participate in the development of salt-sensitive hypertension via inhibiting platelet abnormal activation,and explore related mechanisms.The study may provide novel evidence and reference for the prevention and treatment of salt-sensitive hypertension and organ damage.Methods:In vivo study:SPF male DSS rats and their control SS-13BN rats were treated with normal salt(0.4%NaCl,NS),high salt(8%NaCl,HS)and high salt add aspirin(HS+ASA,10 mg/kg/d)for 8 weeks.Common carotid artery cannulation and tail-cuff method were used to measure arteary blood pressure(BP).Flow cytometry were used to detect the percentage of leukocyte-platelet adhesion,platelet activation and leukocyte infiltration in vessels.Tail bleeding determination and platelet-collagen static adhesion testting were performed for detection of platelet activity.Immunohistochemistry were used to study renal leukocyte infiltration.Acetylcholine(Ach)-dependent vasoconstriction and diastolic function were detected by Power-lab system.Western blot were used to detect vascular function.The expression of vascular function(eNOS,iNOS,vWF and ET-1)and renal inflammatory factors(IL-6,IL-1? and TNF-?)were determined by RT-PCR.Enzyme-linked immunosorbent assay(ELISA)were used to measure the expression of soluble thromboxane TXA2 in peripheral blood and the changes of platelet protein levels under different treatment were detected by proteomic analysis.In vitro study:Leukocytes and platelets were enriched from peripheral blood in DSS rats,the platelets were pretreated with aspirin,COX-1 inhibitor and COX-2 inhibitor,respectively.The leukocyte were dyed with BCF-AM,and then incubated with platelets and lung microvascular endothelial cells(PMVEC)under normal salts(133 mM NaCl)and high salt(173 mM NaCl)environment,Respectively.Adhesion between leukocytes and endothelial cells was observed unde a fluorescent inverted microscope.Results:The blood pressure was significantly increased in high salt treated DSS rats which compared with the control group.After aspirin intervention,blood pressure was significantly lower than that in high salt group(P<0.05),meanwhile,the blood pressure in SS-13BN rats with no significant difference.The results of flow cytometry showed that the high salt diet made the activation of platelet and the aggregation rate of leukocytes and platelets increased obviously compared with the control group,while the aspirin gavage normalized the upregulated blood pressure(P<0.05).Immunohistochemistry results indicated that the high salt diet increased the leukocytes infiltration into kidney and vascular,which blunted by aspirin intervention.Vasoconstriction and diastolic function of vascular in DSS rats were significantly attenuated afer high salt diet with incresed expression of vWF,ET-1 and iNOS as well as the decreased eNOS,and aspirin treatment could effectively improve vascular function and normalized the protein expression(P<0.05).Real-time PCR results also revealved that the expression of kidney inflammatory factors was significantly increased in DSS rats with high salt diet compared with the control group,and aspirin treatment could reduce the increase of inflammatory factors caused by high salt.Proteomic results showed that long term high salt diet activated the blood coagulation and complement pathways in the platelets,but the activation was blocked by the administration of aspirin in DSS rats.Conclusion:In conclusion,aspirin ameliorates the HS diet-induced aggravation of high BP by preventing the adhesion of leukocytes to endothelial cells via the inhibition of the platelet COX-1 but not the COX-2 pathway.Aspirin treatment also reverses the abnormal complement and coagulation cascades in DSS rats fed a HS diet.These results highlight a new property of aspirin in protecting vascular endothelial dysfunction,which may be beneficial in the treatment of salt-sensitive hypertension.