| BackgroundWhile coronary artery ectasia (CAE), defined as local or diffuse dilation (exceeding 1.5 times of normal adjacent reference segment), is a non-obstructive coronary artery disease. It can lead to myocardial ischemia, angina pectoris and even myocardial infarction. CAE is a rare coronary artery disease with low incidence, and it is difficult to distinguish CAE from coronary atherosclerosis in terms of severity of angina pectoris and clinical symptoms. CAE usually occurs with concomitant coronary atherosclerosis, and has been suggested to be a variant coronary artery disease. Everyday clinical practice tends to underestimate the impact of coronary ectasia merely due to the yet unknown natural history of this condition, its relative rarity and the subsequent difficulties in conducting randomized trials to compare different forms of treatment. The continuously expanding implementation of coronary angiography in the investigation of cardiovascular disease is likely to acculminate a higher absolute numbers of patients diagnosed with coronary ectasia. In this setting, the need for appropriate clinical recommendations should not be overlooked. However,the pathogenesis of CAE remains poorly understood. CAE has been thought to be related to endothelial dysfunction and inflammation. The relationship between coronary atherosclerosis and CAE is unknown, and their pathology in the development of CHD is unclear. Understanding the mechanisms may be of particular importance on acquiring an insight into the nature of coronary ectasia and its possible relation to the atherosclerotic process, and may also have direct clinical implications in the management and follow-up strategy of this condition.GDF-15 is a number of transforming growth factor beta-TGF (beta) super-family. In physiological condition, the expression of GDF-15 is higher in placenta and prostate but lower in liver, kidney and heart. But in stress-induced condition, the expression of GDF-15 increased significantly. The study found that the expression of GDF-15 significantly increased in myocardial cells in vitro when injuryed by ischemia or ischemia-reperfusion. Many clinical trials show that, when the myocardial cells were injuryed by myocardial ischemia, GDF-15 was highly secreted to resistant myocardial lesions. It is important to explore the protective function of GDF-15 in patients of CAE.Objective1. By the retrospective study, the clinical significance and coronary angiography images of 48 CAE patients diagnosised as CAE were totally analysed.2. By measuring a variety of cellular factors, including nitric oxide (NO), endothelin-1 (ET-1), matrix metalloproteinase-9 (MMP-9), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) and growth differentiation factor-15 (GDF-15), the different mechanisms and the key roles played by these factors were discussed in the process of CAE and stenosic lesions.3. At the gene level, aiming to get the variation of CAE and OCAD (Obstructive coronary artery disease), we studyed the SNP of ACE Intron 16 I/D, AT1R 1166 A/C, MMP-91562 C/T and GDF-15-3148C/G.4. To stimulate the HUVEC with HDL, LDL, oxLDL, Glu, Insulin, Angll and three antagonists of MAPK signal transmission pathway with different concentration and time in vitro. The expressions of GDF-15 in HUVEC were analyzed by real time RT-PCR. Thus to explore the changes of the level of GDF-15 in endothelial cells injured by atherosclerosis risk factors.5. To explore the roles of GDF-15 played in endothelial cells, we measure the expression of nitric oxide (NO), nitric oxide synthase (eNOS), endothelin (ET-1), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in HUVEC cells stimulated by GDF-15 at different concentration and time in vitro.Methods1. The study group consisted of individuals who had been referred for coronary angiography because of chest pain. Forty-eight patients of CAE admitted to the Cardiology Department of the Peking Union Medical College Hospital were recruited from January 2005 to December 2009 for this study. The clinical characteristics, coronary angiography images and follow-up by telephone and clinic were retrospective analysed.2. CAE, obstructive coronary artery diseases (OCAD) and the Normal coronary arteries (NCA) were all age-and gender-matched patients who were selected in a consecutive manner from the catheterized patients during the same study period. Age, sex, cigarettes smoking, alcohol drinking, diabetes mellitus (DM), hypertension, hypercholesterolemia, and family history were recorded. The plasma levels of NO, ET-1, MMP-9, TIMP-1 and GDF-15 were determined by ELISA kits. According to the different characteristics of coronary artery injury, the CAE group was divided into two subgroups:isolated coronary artery ectasia (ICAE) and coronary with both Ectasia and Stenosis (CAE+Stenosis). Difference of variety of cellular factors in each group were further anaylsis.3. In the gene level, using restriction fragment length polymorphism, fragment length polymorphism and direct sequencing techniques, the genotypes of all subjects ACE Intron 16 I/D, AT1R 1166 A/C, MMP-91562 C/T and GDF-15-3148 C/G polymorphism were analysis.4. The HUVEC was stimulated with HDL, LDL, oxLDL, Glu, Insulin, AngⅡand three antagonists of MAPK signal transmission pathway with different concentration and time in vitro. The expressions of GDF-15 in HUVEC were analyzed by real time RT-PCR to detect the level changes.5. In vitro, HUVEC cells were stimulated by GDF-15 in 2 time groups (36h and 72h) and each of which with five concentrations (0,400,600,800,1000,1500 pg/mL). Endothelial cell nitric oxide concentration in the supernatant was detected by Elisa kit. The expression levels of ET-1, eNOS, ICAM-1 and VCAM-lwere determined bv RT-PCR.6. All statistical analyses were performed using the SPSS statistics program, version 13.0. Data are presented as means+SD and percentage, as appropriate. We used theχ2 test to analyze category data, the Student's t-test or Mann-Whitney U-test to evaluate differences between 2 groups. The correlation between variables of groups was assessed by the Pearson and Spearman correlation tests for parametric and nonparametric variables. Logistic regression analyses were used to determine whether plasma biomarkers were associated with CAE. All p-values are reported with two-tail test. The alpha-level is 0.05.Results1. There were no significant differences in baseline characteristics of risk factors in CAE and OCAD. Clinical symptoms were not effective to distinguish CAE from CAD.2. Single-vessel lesion were more prevalent in patients with CAE; RCA was the most commonly involved coronary in CAE with single-vessel lesion. In this study, there were 28 cases (58.3%)with isolated coronary artery ectasia and 20 cases (41.7%) with both CAE and stenosis.3. NO levels in CAE group were significantly higher than OCAD group (P=0.007). In subgroup analysis, NO levels in ICAE and CAE+Stenosis group were significantly higher than OCAD group (P= 0.022, P= 0.014, respectively). There were no statistically differences on ET-1 in each group (P> 0.05).4. Compared with NCA and OCAD groups, MMP-9 levels in CAE were significantly higher (P= 0.004 and P= 0.025, respectively). For further analysis, ICAE has higher MMP-9 level than OCAD (P=0.027), and the MMP-9 in CAE+Stenosis group were higher than ICAE. TIMP-1 levels in NCA Group were significantly higher than other groups (P<0.05), but there were no significantly difference between the CAE and OCAD group.5. Compared with NCA and OCAD groups, GDF-15 levels in CAE were significantly higher (P= 0.045 and P= 0.037, respectively). Subgroup analysis showed that ICAE had higher GDF-15 level than OCAD (P=0.027), and the GDF-15 in CAE+Stenosis group were higher than ICAE.6. There were no significantly differences of ACE Intron 16 I/D, AT1R 1166 A/C, MMP-91562 C/T and GDF-15-3148C/G polymorphism among these groups. It is suggested that these genotypes has no correlation with the CAE process.7. In this study, there were no relationship between MMP-91562 C/T polymorphism and plasma levels of MMP-9.8. In this study, there were no relationship between GDF-15-3148C/G polymorphism and plasma levels of GDF-15.9. HUVEC stimulated by different concentrations of LDL for 12 hours, GDF-15 expression levels are not the same, but GDF-15 expression levels at 24 hours were decreased; HUVEC stimulated by different concentrations of HDL for 24 hours, GDF-15 expression levels were upregulated; after stimulation of different concentrations of oxLDL 12 or 24 hours, the expression of GDF-15 were significantly upregulated.10. High glucose can increase the expression of GDF-15; different concentrations of insulin for 12 hours increased the expression of GDF-15, low-concentration group increased expression with longer time; high glucose with different concentrations of insulin combined for 12 and 24 hours can decreased the expression of GDF-15.11. After stimulated by different concentrations of AngⅡc for 6 hours or 12 hours, the expression of GDF-15 was upregulated in a obviously concentration dependent meaner. GDF-15 expression was significantly increased with SB203580 after added for 6 hours,12 hours and 24 hours. The expression of GDF-15 was significantly increased after SP600125 was added for 6 hours but decreased significantly after 12 hours. GDF-15 expression increased after U0126 was added for 6 hours, but decreased after 12 hours and 24 hours'stimulation.12. GDF-15 could increase the expression of eNOS in HUVEC in a concentration dependent manner, but higher concentration with longer time stimulation of GDF-15 caused a decrease of eNOS.13. With stimulation of GDF-15 for 36 hours and 72 hours, the HUVEC expression of ET-1 decreased.14. GDF-15 could decrease the expression of ICAM-1 in HUVEC in a certain concentration.15. GDF-15 could decrease the expression of VCAM-1 in HUVEC in a certain concentration.16. With stimulation of GDF-15 for 36 hours and 72 hours, the secretion of NO in HUVEC increased in certain concentration.Conclusions1. The clinical symptoms of CAE and OCAD patients were similar. Single-vessel lesion were most commonly seen in CAE. RCA was the most commonly involved coronary artery. The ectasic arteries of CAE patients were often coexcisting with coronary atherosclerosis.2. A cardiovascular protective mechanism may compensate the existing cardiovascular risk factors in coronary ectasia and such mechanism was significantly diminished in coronary artery atherosclerosis. Coronary ectasia may present as an early stage of coronary atherosclerosis. Biomarkers might be useful in predicting different stages of coronary atherosclerosis.3. MMP-91562 C/T and GDF-15-3148C/G polymorphisms were not statistically different between CAE and OCAD. And they were not associated with plasma MMP-9 and GDF-15 levels.4. A variety of risk factors could impact the expression of GDF-15 in HUVEC. Since GDF-15 has some benefial effect, such as reducing inflammation, promoting tumor cell apoptosis, inhibiting cell proliferation. The results indicated that GDF-15 may-play a certain protective role in endothelial cells. 5. Experiments in vitro suggested:with a certain concentration range, GDF-15 plays certain protective role in endothelial cells and could enhance endothelial function. |
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