The Study Of Differential Expression Of MiRNA-146 Between Stanford Type B Aortic Dissection Patients And Normal People And Investigate The Risk Factors Of Type B Dissection

BackgroundAortic dissection (AD) is a kind of catastrophic cardiovascular disease. Studies in these years have shown that the incidence of acute aortic dissection was 2-2.5 cases per 100,000 people, which means there will be 6,000-10,000 patients in the United States each year. The AD patients are at great risk,40% of patients died immediately, and one more percent of the patients died in each hour.5%-20% patients died during surgery or after that in very short time. Only 50%-70% of the patients survive from surgery for more than five years. Although the incidence of dissection is associated with many factors, but unluckily, the cause of spontaneous aortic dissection remains unclear.Currently the pathogenesis of aortic dissection has not yet been fully elucidated, but some predisposing factors that may be relevant.1. Hereditary middle aortic abnormalities, such as Marfan syndromes, Ehlers-Danlos syndromes, Loeys-Dietz syndromes, congenital ovarian dysgenesis (Turner’s syndromes), etc.2. Increasing aortic wall stress, such as hypertension, pheochromocytoma, trauma, abuse of cocaine. 3. Inflammatory vascular disease, such as Takayasu arteritis, giant cell arteritis, Behcet’s arteritis.4. Other factors include pregnancy, polycystic kidney disease, long-term use of corticosteroids or immunosuppressive agents. Hypertension is the only clear risk factor for aortic dissection, and other factors have not yet been fully elucidated.Many researchers have tried to explore the pathogenesis of aortic dissection, especially in molecular genetics; abnormal gene structure and expression are considered to be the basis of the incidence of aortic dissection.Micro-ribonucleic acids (MicroRNA, miRNAs) recently attracted the attention of scientists because its function and normal expression are associated with cardiovascular disease. miRNAs are a class of small non-coding RNA sequences made from about 22 nucleotides, and highly conserved. Its size by about 70-90 bases of single-stranded RNA with hairpin structures precursor after processing enzyme Dicer to generate double-stranded RNA, the double-stranded miRNAs was inducted into silencing complex. A single-stranded mature miRNA retains, while the other one is degraded. miRNA molecule is combined with complementary base of mRNA 3 ’end untranslated regions (UTR), inhibit mRNA translation or degradation of target mRNA In the post-transcriptional level, and regulate the expression level of the gene. Preliminary results of this study found that the result of the DNA microarray shows that compared with normal aorta, aortic tissue from aortic dissection patients, whose miRNAs were differentially expressed. Therefore, in this study we collected clinical data and peripheral blood samples from both aortic dissection patients and normal volunteers, try to validate the different expression of miRNA-146 in reverse transcription-polymerase chain reaction (RT-PCR), then use logistic regression analysis to investigate the risks factors associated with aortic dissection. We hope that we can understand aortic dissection deeply by this study.ObjectivesThis study consists of two parts. Part one is based on the previous research results, expand the sample size, and collect clinical data and peripheral blood samples from both aortic dissection patients and normal volunteers, validate the different expression of miRNA-146 in reverse transcription-polymerase chain reaction (RT-PCR). In the second we use logistic regression analysis to investigate the risks factors associated with aortic dissection. We hope that we can understand aortic dissection deeply by this study.MethodsPartⅠAfter approval by the hospital ethics committee and informed consent of patients, we collected 43 cases of peripheral venous blood samples from Stanford type B aortic dissection patients who were hospitalized in the department of cardiology in Guangdong general hospital from 2014.36 volunteers were enrolled as control groups, matching gender, age, coronary heart disease, diabetes, family history of cardiovascular disease and liver function; aortic dissection, major cardiovascular diseases and cancer patients were excluded. Everyone enrolled had been collected 10ml venous blood into EDTA tubes and placed in-80℃ refrigerator. Using RT-PCR technology to verify the content of miRNA-146 in both dissection patients and the volunteers. Detection of gene expression in all samples were relative expression level and leveling by the U6 snRNA, and two groups were compared using 2^-ΔΔCt method. Using SPSS 13.0 to analyze the results of the verification, comparison between groups using χ2 test or Fisher’s exact test indicated normal distribution of measurement data is resented in (x±s),2^-ΔΔCt value data using rank sum test, P <0.05 was considered statistically significant difference.Part IIAll subjects were divided into patient group and the control group while in hospital. We numbered everyone and record sex, age, hypertension, coronary heart disease, diabetes, family history of cardiovascular disease and smoking history; then we examined their clinical data including bilateral common carotid arteries medial thickness (LCCA-IMT, RCCA-IMT), interventricular septum thickness (IVS), left ventricular posterior wall thickness (LVPW), total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), serum creatinine (CREA), blood urea nitrogen (BUN), alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum total protein (TP), albumin (ALB), fasting plasma glucose (GLU), glycated hemoglobin (HbA1c), blood uric acid (URIC), red blood cell count (RBC), platelet count (PLT), white blood cell count (WBC), hemoglobin (HGB), D-dimer (D-DI), international normalized ratio (INR), miRNA-146 level and other indicators. Using spss 13.0 statistical software for data analysis. Count data expressed as a percentage, among groups were compared using Pearson χ2 test or Yip continuity correction or Fisher’s exact test, measurement data of normal distribution showed as (x±s), groups were compared using the two-sample t-test; nonparametric using Wilcoxon test; multivariate Logistic retrospective analysis was used of risk factors associated with progressive aortic dissection occurred. Test level P<0.05 was considered statistically significant difference.ResultsPartⅠRank sum test results show that the average 2^-ΔΔCt value of the case group rank was 50.53, the control group was 27.42, Mann-Whitney U test shows that Z is-4.459, P=0.000<0.05, The results showed significantly difference between two groups cases of miRNA-146 relative expression, MiRNA-146 expression levels in patients with aortic dissection was significantly higher than the general population of non-risk aortic dissection.Part ⅡEach independent factor associated (hypertension, smoking history, ALB, miRNA-146 relative expression of 2^-ΔΔCt values, D-dimer) may occur with aortic dissection as independent variables included in the multivariate Logistic regression analysis model, whether the occurrence of aortic dissection or not as the dependent variable (the occurrence of dissection:Y= 1, not occurred:Y= 0). The results showed that hypertension is an independent risk factor for the occurrence of aortic dissection, and serum albumin levels were protective factors of aortic dissection.ConclusionsPartⅠValidated by RT-PCR technique, compared with non aortic dissection people, miRNA-146 expression was significantly up regulated in patients with type B aortic dissection, this may be associated with the pathogenesis of aortic dissection.Part ⅡHypertension is an important risk factor for the occurrence of aortic dissection, and serum albumin levels are protective factors. Possible causes may be albumin has the antioxidant effect, which could inhibit the inflammatory response in vivo.