| Atrial fibrillation(AF)is very common in clinical type of arrhythmia and its clinical manifestation exists in many diseases,not only high mortality and morbidity and severe complications such as cardiac insufficiency and thromboembolism etc.,since its occurrence mechanism is unclear.It is believed that atrial ion channel electrical remodeling and atrial tissue remodeling exist in atrial fibrillation.Atrial fibrosis is the most prominent manifestation of atrial tissue remodeling in patients with atrial fibrillation.The total number of myocardial cells is mainly composed of a variety of non-myocardial cells,more than 90% of which are myocardial fibroblasts,which can synthesize extracellular matrix(ECM)such as collagen.The content of ECM components can be used to assess the extent of organ fibrosis.Ecm account for about 49%and 17% of that total volume of myocardial tissue in the atrium and ventricle,respectively.Collagen fibers present the most important position in the composition of ECM.The former is composed of five collagen subtypes,of which type I collagen accounts for about 85% of the total myocardial collagen and type ? collagen accounts for about 11% of the total myocardial collagen.The ratio of type ? collagen to type ? collagen plays an important role in maintaining the normal structure of myocardial tissue and the integrity of cardiac function,especially basic fibroblast growth factor(bFGF)and connective tissue growth factor(CTGF)act an indispensable member in the formation and development of fibrotic diseases.Some studies have shown that ctgf expression in pulmonary veins is increased,which may explain the serious interstitial fibrosis changes in the area around pulmonary veins in patients with persistent atrial fibrillation.However,the specific mechanism of atrial fibrosis is not fully understood.The expression of ctgf and bFGF in atrial muscle of patients with atrial fibrillation and the role of atrial fibrosis are rarely reported at home and abroad.This study is divided into three parts: the first part discusses the changes of atrial fibrosis in sick persons with these disease and atrial fibrillation;The second part discusses the relationship between cytokines CTGF and bFGF and atrial fibrosis in AF.Elisa,immunohistochemistry,RT-PCR and western blotting were used to detect the levels of bFGF and ctgf in serum of patients with different types of atrial fibrillation in rheumatic heart disease,the expression and localization of type I collagen,type ? collagen,bfgf and CTGF in atrial tissue,and the differences of gene transcription level and protein expression level,so as to explore their roles and correlations in the occurrence and development of atrial fibrosis.To provide experimental basis for the study of the molecular mechanism of atrial fibrosis in atrial fibrillation,and have important theoretical and clinical significance for the prevention of atrial fibrillation and the search for new therapeutic targets.Objectives:1.To investigate the changes of atrial fibrosis in patients with atrial fibrillation by detecting the content and distribution of collagen in atrial tissueof atrial fibrillation,and further confirm that atrial fibrosis is a momentous tissue structure reconstruction in the process of atrial fibrillation.2.To explore the role of CTGF and bFGF in atrial fibrosis in patients with atrial fibrillation by detecting the changes of serum CTGF and bFGF levels and the changes of CTGF and bFGF mrna and protein levels in atrial tissues,and to provide experimental benchmark for the precaution and therapy of atrial fibrillation.Methods:1.By collecting the clinical data of RHD patients and atrial tissue samples during thoracotomy,the patients were divided into sinus rhythm group and atrial fibrillation group.the atrial tissue of patients with sinus rhythm group was taken as the control,the distribution of collagen in atrial tissue was detected by masson staining method,the distribution of collagen in atrial tissue was detected by masson staining method,the content of collagen in atrial tissue was detected by hydroxyproline method,and the expression changes of collagen ?and collagen ? mrna in atrial tissue were detected by rt-PCR method.2.The levels of CTGF and bFGF were measured by ELISA.The expression and distribution of CTGF and bFGF in atrial tissue were detected by immunohistochemistry.CTGF and bFGF mrna were detected by rt-PCR.The levels of CTGF and bFGF protein in atrial tissues of each group were detected by western-blot.Results:1.A total of 54 effective cases were collected,including 18 patients in sinus rhythm group and 34 patients in atrial fibrillation group.the clinical data showed that the left atrial diameter(LAd)in persistent atrial fibrillation group was significantly greater than that in sinus rhythm group(p<0.05).No obviousimparity in age,sex,LVEF and valve lesions between the two groups.(P>0.05).2.Collagen distribution masson staining showed that the blue collagen fibers were primaryly scattered in the myocardial interstitium.The positive expression in cardiac muscle of sinus rhythm group and atrial fibrillation group increased gradually.The results of hydroxyproline assay and semi-quantitative analysis of collagen staining images showed that collagen content in AF group was comparatively supernaler than SR group(P<0.01).3.The results of rt-PCR showed that the expression of type ? collagen and type ? collagen mrna in atrial tissue increased gradually in sinus rhythm control group and atrial fibrillation group.The expression of type ? collagen mrna was significantly different in each group(P<0.05),but the expression of type ? collagen mrna was not significantly different in the wind heart group(P>0.05).4.In the SR suite and AF suite,the serum level of presentation CTGF increased gradually,and present obvious imparity in this two suites(P<0.05).CTGF was mainly expressed in the cytoplasm of cardiac myocytes,partly in the nucleus,and in brown granules.The expression of CTGF in atrial tissue was increased by immunohistochemistry,mrna and protein levels(P<0.05).5.The level of serum bFGF increased gradually in the sinus rhythm control group and atrial fibrillation group of rheumatic heart disease(P<0.05).b FGF is mainly expressed in the cytoplasm of cardiac myocytes and is brown and granular.Immunohistochemical detection of bFGF in atrial tissue,mrna expression.There may presents obvious imparity in this two suites(P<0.05).6.Correlation analysis between ctgf and bfgf mrna levels and type I collagen mrna showed that af group was positively correlated with type Icollagen,but sinus rhythm group was not correlated with type I collagen.Conclusions:1.In the SR suite and AFsuite,the collagen content of atrial tissue increased gradually,especially type ? collagen,suggesting that the formation and sustainability of AF is related to the collagen metabolism of atrial fibrosis,which is an important tissue structure reconstruction in the development of atrial fibrillation.2.Cytokines CTGF and bFGF may be involved in collagen metabolism of AF,and may present a indispensable location in the formation and sustainability of atrial fibrillation,and may be one of the targets of anti-fibrosis therapy of atrial fibrillation. |
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