Protective Effect And Mechanism Of Crocin On Monocrotaline Induced Pulmonary Hypertension In Rats

The etiology of pulmonary arterial hypertension(PAH)is complex,and pulmonary vascular remodeling is the pathological basis of PAH.Among them,inflammation is considered to play an major role in the germination and development of PAH,and is a key factor in pulmonary vascular remodeling in the later stage of the disease.P38 mitogen-activated protein kinase(P38MAPK)is the most vital member of the MAPK family to influence inflammatory response and regulate the expression of various inflammatory factors.Nuclear factor-κB(NF-κB)is a key transcriptional activator of the inflammatory response,which can regulate the expression and secretion of many inflammatory mediators,such as interleukin-1(IL-1),tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),chemokine CC family ligand 2(CCL2)and other inflammatory mediators,causing a series of inflammatory responses.P38MAPK signaling pathway and NF-κB signaling pathway can jointly affect the germination and development of inflammation through interaction.The CCL2/chemokine receptor 2(CCR2)pathway plays a crucial role in the activation and migration of macrophages,and has long been regarded as an important clinical target for various chronic inflammatory diseases.Crocin has a good anti-inflammatory effect.The purpose of this study was to observe the changes of inflammatory factors in patients with PAH and their correlation with disease severity,and to explore the clinical significance of inflammatory indexes;To observe whether crocin can protect the rat model of PAH induced by monocrotaline by regulating P38MAPK/NF-κB pathway and CCL2/CCR2pathway.Part One changes of inflammatory factors in patients with pulmonary arterial hypertensionObjective:To study the changes of inflammatory factors in blood of patients with PAH and its correlation with disease severity,and to explore the clinical significance of inflammatory indexes.Methods:The subjects in the idiopathic PAH(IPAH)group,the connective tissue disease-related PAH(CTD-PAH)group and the control group were tested for IL-6,hs-CRP and NT-pro BNP;echocardiography;WHO functional class and 6-minute walking distance(6MWD).Result:The expression level of IL-6 and hs-CRP in the blood of PAH patients increased significantly,and the cardiac function and activity tolerance decreased.Inflammatory factors were significantly correlated with pulmonary artery pressure,cardiac function and activity tolerance.Summary:Inflammation play a big part in the occurrence and development of PAH.Part Two The protective effect of crocin on monocrotaline induced pulmonary arterial hypertension in rats and its effect on inflammationObjective:To observe the effect of crocus on pulmonary arterial pressure,cardiopulmonary tissue structure,P38MAPK/NF-κB inflammatory pathway and related inflammatory factors in rats with PAH induced by monocrotaline(MCT).Methods:MCT-injected rats received daily intragastric infusion of crocin for 4 weeks.Right ventricular systolic pressure(RVSP),mean pulmonary artery pressure(mPAP),right ventricular hypertrophy index(RVHI)and right ventricular mass index(RVMI)were measured;HE staining and masson trichrome staining were used to observe the pathological changes of lung and right ventricle;Detection the changes of inflammatory factors and p38MAPK/NF-κB inflammatory pathway in lung and right ventricle by molecular biological method.Result:In PAH rats,mPAP,RVSP,RVHI and RVMI were significantly increased;pulmonary arterioles were hypertrophic;inflammatory cell infiltration and collagen fiber hyperplasia were obvious in cardiopulmonary tissue;the expression of p38MAPK/NF-κB pathway and other inflammatory factors was significantly increased;the expression level of oxidative stress response was significantly increased in the lung.In rats injected with crocin after MCT injection,RVSP,mPAP,RVHI and RVMI did not increase significantly,pulmonary arteriole hyperplasia and hypertrophy,inflammatory cell infiltration and collagen fiber hyperplasia in cardiopulmonary tissue were improved,the expression of p38MAPK/NF-κB pathway and other inflammatory factors was inhibited,and the expression level of oxidative stress response in the lung decreased.Summary:PAH is closely related to inflammation,and crocin can significantly reduce the degree of inflammation and delay the progression of PAH,and its mechanism is related to reducing the activation of p38MAPK/NF-κB pathway and thereby reducing the secretion of inflammatory factors.Part Three Effects of crocin on CCL2/CCR2 pathway in rats with mo-nocrotaline-induced pulmonary arterial hypertensionObjective:To observe the changes of CCL2/CCR2 pathway and macrophage chemotaxis in heart and lung tissue of PAH rats induced by MCT and the effect of crocin on these changes.Methods:MCT-injected rats received daily intragastric infusion of crocin for 4 weeks.The levels of CCL2 in the lung and right ventricle of rats were detected;the lung and right ventricle were double-stained by immunofluorescence for CCR2 and the macrophage marker CD68.Result:The CD68~+macrophage expression area coincided with the CCR2~+expression area in the heart and lung tissues of all rats.The expression of CCL2/CCR2 pathway and the infiltration of CD68~+macrophages in the lung tissue and right ventricle of the PAH group were significantly increased.However,the expression of CCL2/CCR2 pathway in the heart and lung tissues of rats treated with crocin after MCT injection was significantly down-regulated,and the infiltration of CD68~+macrophages was reduced.Summary:Crocin can reduce the expression of CCL2/CCR2 pathway and inhibit the migration of macrophages,thereby alleviating MCT-induced PAH in rats.Conclusion:1.Inflammation plays an important role in the occurrence and development of PAH.2.Crocin inhibited the migration of macrophages by regulating the CCL2/CCR2 signaling pathway;inhibited the further expression of inflammation by acting on the p38MAPK/NF-κB pathway,effectively delaying the occurrence of PAH.3.Inflammation is a complex multi-link process in PAH,and crocin can play an anti-inflammatory role by regulating multiple inflammatory signaling pathways.