Relation Of AT1R Gene Polymorphism And AngⅡ And ET With Myocardial Damage In Severe Preeclampsia Patients And Their Fetus

Preeclampsia is one of the hypertension state in pregnancy, which is the special complication of gestation, imperiling the mother and fetus seriously, especially severe preeclampsia (S-PE). Severe preeclampsia is one of the most important reasons of maternal and fetus mortality, the incidence is 9.4%. The onset of the preeclampsia heart disease is severe preeclampsia .The preeclampsia heart disease is character by the heart failure sign group due to the myocardial damage, showing left heart failure and lung edema, which make up 5% of the total heart disease in gestation and is the second leading cause to maternal mortality. Meanwhile, some reports indicate that the fetal cadiocyte present homogenous and compensated hypertrophy due to the severe preeclampsia, at last the systole and diastole function of heart become abnormal.The primary pathological change of severe preeclampsia is the Small vessels spasmodism all over the body. In the preeclampsia heart disease patient, the endocardium shows cadiocyte hypertrophy, endochylema granulation, stroma focal fibronolysis, in some severe patients there are punctate hemorrhage and focal necrosis. The change of cardiac muscle fibers can be observed under the electron microscope, wide degeneration, interstitial edema, swelling blood vessel endothelium, narrow lumens, microthrombus can be founded sometimes. All signs indicated that myocardial damage has already occurred due to poor supply of blood in the severe preeclampsia. Left ventricular hypertrophy is the severe outcome caused by Small vessels spasmodism, so the preload and afterload of heart may be increased, left ventricular end diastolic period diameter and left atrial diameter should be enlarged, interventricular septum thickening can be observed in some cases, all of these changes lead to the left ventricular diastolic function decreased. in brief, due to small vessels spasmodism, the peripheral resistance increase, the blood pressure step up, cardiac load be added, left ventricular end-diastolic pressure is increased, but the systole function is decreased. Considerable researches have suggested that severe preeclampsia patients possess conspicuous genetic predisposition and high risk of cardiovascular disease. Renin-angiotensin system play the important role in keeping electrolyte balance and adjusting the cardiovascular activity, especially angiotensinⅡ(AngⅡ) is the most powerful. AngⅡis the one of the most powerful endogenous vasoconstriction substance we have known. It has the significant contribution to maintain cardiovascular homeostasis and to bring about myocardial hypertrophy. Only by the help of AngⅡreceptor can AngⅡwork, especially AngiotensinⅡType 1 Receptor(AT1R), the function of AngⅡmay be changed if the AT1R alter in molecular biology. AT1R as a kind of membrane receptor, it process every characteristic of hormone, distributing on the blood vessel smooth muscle cell, maintaining metabolic balance and the tension of blood vessel. Some results demonstrates that AT1R gene polymorphic site A1166C can lead to the increase of AT1R density, thus, the high risk of cardiovascular disease may be taken place. In comparison to the normal control group, AT1R gene polymorphic site A1166C has high activity in the heart failure patients.The patients with preeclampsia are more sensitive to AngⅡthan normal pregnant women, due to AT1R, AngⅡcan work on the cadiocyte and desmocyte membrane, thus, the myocardial contractile force and heart rate increased, mesenchymocyte hyperplasia, cadiocyte growth and development, at last, myocardium hypertrophy and proliferation. After binding with AT1R, AngⅡcan accelerate the hydrolysis procedure from phosphoinositide to inositol triphosphate and diglyceride when the phospholipase C are activated by Gp equestron. Inositol triphosphate and diglyceride augment calcium in endochylema, active deoxyribonucleaseⅠdepended by calcium, so the DNA break and cadiocyte die. The level of AngⅡincrease would lead to the blood vessel contraction, catecholamine and aldosterone releasing, so the myocard apoptosis and pachynsis occur, then, the interstitial fibrosis and cadiocyte reconstruction can be observed, these changes can lead to poor prognosis in the heart failure patients.The abnormal of function and morphous of blood vessel endothelium are closely relation with severe preeclampsia, AT1R increase endothelin(ET) in the blood, which is a kind of biologically active peptide released by vascular endothelial cell. Endothelin has power to contract blood vessel and is ten times powerful than AngⅡ, besides, it can make smooth muscle cell proliferated, by this way, it participate the procedure of hypertension, artherosclerosis, pneumocardial disease, asthma and so on. Endothelin play a important role in the affection of ischemia due to angiospasm and the damage of blood vessel endothelium, it can interfere the energy metabolism of cadiocyte by inhibiting the procedure of intaking energy metabolic substrate, it also can aggravate the damage of cadiocyte lipid peroxidation, which make more much ET released, then, these ET participate the procedure of ischemia-reperfusion. ET is a vasoconstriction factor, which not only stimulate and active many hormones and cytokine but also widely participate the physiological and pathological regulation of body. Meanwhile, it participate the physiopathologic procedure of cardiovascular disease and increase the myocardial contractile force, as well as promote the hyperplasia of smooth muscle and function of neuroendocrine. Some data show that ET plays the important role in the procedure of inducing the heart failure.BackgroundMany researcher believe that essential hypertension is closely relation with the adenine be shifted by cytosine on AT1R gene polymorphic site A1166C. A few studies illustrate that the relation of AT1R gene polymorphism with the heart damage in the severe preeclampsia patients. AngⅡas one of the most powerful endogenous vasoconstriction substance can regular angiotasis and maintain blood-volume, stimulate the proliferation of cadiocyte as well as synthesis and cumulate of ecto-cyte collagen, so it play a important part in the maintaining of angiomyocardiac homoeostasis. Sufficient clinic and breadboard findings indicate that AngⅡis relation with pathologic interstitial fibrosis and heart remodeling and failure. AT1R genic mutation can influence the sensitivity of AngⅡ, thus, AngⅡpathologic effect shows individual difference. ET lies in the vascular endothelial cell, which is the one of the most powerful endogenous vasoconstriction substance. A lot of studies confirm that ET is much more in the severe preeclampsia patients than in the normal pregnant women, and would increase with the deterioration. However, no prior work exists on the problem whether AT1R gene polymorphism and AngⅡand ET lie in the fetus and whether they influence the structure and function of maternal and fetal heart or not. Fifty-three severe preeclampsia patients who be treated in the First affiliated hospital of Xinjiang Medical university were included in the present study, meanwhile, forty-eight normal pregnant women were selected as control group. In order to approach the relation of AngⅡand ET level in plasma and the preeclampsia cardiac disease, we measure the index of left ventricle and systolic function by Doppler ultrasound, and obtain the AngⅡand ET level in plasma by radio-immunity. Besides, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)and allele-specific PCR(ASP)and many modern molecular biology methods were used to detect and analyses the AT1R gene polymorphic site A1166C related with preeclampsia. In a word, the study is aimed at finding out the relation of AT1R gene polymorphism and preeclampsia cardiac disease, then to explore how the genetic factor contribute to the preeclampsia cardiac disease from molecular level.MethodsFifty-three severe preeclampsia patients who be treated in the First affiliated hospital of Xinjiang Medical university were included in the present study, they were chosen completely at random from April, 2006 to September, 2007 (case group). Meanwhile, forty-eight normal pregnant women were selected as control group. The index of left ventricle and systolic function of subjects and their fetus were measured by Doppler ultrasound, the index include left ventricular mass index(LVMI)and relative wall thickness(RWT) ? cardiac output(CO) ? cardiac index(CI) ? ejection factor(EF)and parameter of E and A and E/A of atrioventricular valveblood flow, the indexes be used to evaluate the degree of heart damage and the function of diastole and systole.5ml mother's peripheral venous blood and 5ml fetal umbilic blood of all subjects were collectedAngⅡand ET level in plasma were measured by radio-immunity, the AT1R gene polymorphic site A1166C were detected and analyzed with polymerase chain reaction method.(PCR)Comparison the AT1R gene polymorphism and AngⅡ, ET and LVMI and RWT, EF and E/A between two groups and between mothers and fetus.Remarks 11.selected and eliminated criteria of severe preeclampsia1) Selected criteria: the pregnant is in the 34-36 gestational week blood pressure≥160/110mmHg Urine protein≥300mg/24h or (++)2) Eliminated criteria:essential hypertension;renal hypertension2.Selected criteria of the control group:The normal pregnant women whose blood pressure and urine analysis are normal were confirmed without heart disease by the examination of electrocardiogram and ultrasonic cardiogram. 3.The blood pressure were measured with sit position by standard Sphygmomano- metric procedure every 5min for 3 times, then get the mean value, systolic pressure<140mmHg, diastolic pressure<90mmHg.Remarks 21.Ultraphonic criteria of left ventricle structure1) normal:LVMI≤106g/m2, RWT≤0.44;2) left ventricle inward reconstruction:LVMI≤106g/m2, RWT>0.44;3) left ventricle inward pachynsis:LVMI >106g/m2, RWT>0.44;4) left ventricle outward pachynsis::LVMI >106g/m2, RWT≤0.44?2.Ultraphonic criteria of abnormal cardiac functionEF and CO and CI are the index of evaluating the left ventricle systolic function, E/A and RFF are parameter of evaluating the left ventricle diastolic function.Abnormal of left ventricle systolic function:EF<50% or CO<3.5L/min or CI<2.2L/ (min·m2)Abnormal of left ventricle diastolic function:E/A<1 ?The way to examine the left ventricle inward reconstruction by ultrasound: calculate left ventricular mass(LVM)and left ventricular mass index ( LVMI) with Devereux formula, calculate ejection fraction (EF) with Simpson method, determine E and A and E/A of atrioventricular valveblood flow by Doppler ultrasound.Program1.Experiment technique1) the AT1R gene polymorphic site A1166C were detected and analyzed with polymerase chain reaction method.(PCR)2) AngⅡand ET level in plasma were measured by senior technician in nuclear medicine department.3) Maternal and fetal hearts were examined by special doctor.2.Statistical method:1) Statistic data was deal with SPSS 13.0, measurement data are described with mean and standard deviation.2) Comparison of AT1R gene polymorphism between two groups with chi square test3) Comparison of LVMI and RWT and CO and CI and EF, as well as E and A and E/A of atrioventricular valveblood flow between two groups with t-test?4) Comparison of the AT1R gene polymorphic site A1166C and left ventricular mass index and relative wall thickness between mothers and fetus in severe preeclampsia group with analysis of covariance.5) To analyze two variance correlation with Pearson correlation analysis. P<0.05 indicates that contrast are statistical significanceResult1.The frequency of AT1R gene 1166 polymorphic site variant (AC+CC) in the pregnant women and fetal case group are higher than in the control group, the variation is statistically significant. (P<0.05), the variation between the two groups of C allele frequency is statistically significant too (P<0.05)2.The ratio of AT1R gene 1166 polymorphic site variant (AC+CC) to the wild type is 5.21(OR) in the pregnant women. 95% confidence interval is 2.35~13.52. It's means that the risk of severe preeclampsia for those pregnant women whose AT1R gene 1166 polymorphic site variant occur would increase 5.21 times. The ratio of AT1R gene 1166 polymorphic site variant (AC+CC) to the wild type is 5.09 (OR) in the fetus. 95% confidence interval is 2.08~12.95. It's means that the risk of severe preeclampsia for fetus whose AT1R gene 1166 polymorphic site variant occur would increase 5.09 times.3. The index of left ventricle structure in the case group is much more than it in the control group, the variation is significant statistically significant (P<0.01), the concentric hypertrophy is most commonly (LVMI>106 g/m2, RWT>0.44). The end-diastolic dimension (EDV) and end-systolic volume (ESV) of left ventricle in the case group are higher obviously then it in the control group (P<0.01), ejection fraction (EF) of left ventricle in the case group are lower obviously then it in the control group (P<0.01), the variation of cardiac index (CI) and E/A is significant statistically significant (P<0.01); the variation of cardiac output (CO) and stroke volume (SV) is no statistically significant (P>0.05).4. Left ventricular mass index (LVMI) of the pregnant women with AT1R gene 1166 polymorphic site AA-type is more than 106 g/m2, Relative wall thickness (RWT) is 0.44±0.06, it shows eccentric hypertrophy, left ventricular mass index (LVMI) of the pregnant women with AT1R gene 1166 polymorphic site AC+CC-type is more than 106 g/m2, Relative wall thickness (RWT) is more than 0.44, it shows concentric hypertrophy. Compare these index by single factor group comparison, the result shows that the variation of left ventricular mass (LVM) and left ventricular mass index (LVMI) in AT1R gene 1166 polymorphic site AC+CC-type and AT1R gene 1166 polymorphic site AA-type is statistically significant (P<0.05), the variation of relative wall thickness (RWT) in AT1R gene 1166 polymorphic site AC+CC-type and AT1R gene 1166 polymorphic site AA-type is significant statistically significant (P<0.01)5. Compare the case group and control group, the variation of fetal interventricular septum thickness at enddiastole (IVST) is significant statistically significant (P<0.05), the variation of fetal left ventricular post wall thickness (PWT) is statistically significant (P=0.05). Compare the fetal case group of AT1R gene 1166 polymorphic site AC+CC-type and AT1R gene 1166 polymorphic site AA-type, the variation of the interventricular septum thickness at end diastole (IVST) and Relative wall thickness (RWT) is statistically significant (P<0.05).6. The result of multiple factor Logistic regression analysis for the pregnant women shows that genetype (x1) and family medical history (x2) and systolic pressure (x3) as well as body mass index (BMI)(x5) are all high risks to increase the incidence of the left ventricle reconstitution, the relative risk (OR) of them are 2.893 (95%CI is 1.082-8.865) and 4.572 (95%CI is 2.038-14.891) and 3.875 (95%CI is 1.864-8.518) and 2.594 (95%CI is 1.121-7.816), they can be take as independent risk factor for left ventricle reconstitution in severe preeclampsia .7. The concentration of angiotensinⅡin the case groups of pregnant women and fetus are no more than it in the control groups, the variation is no significant (P>0.05). The index of left ventricle structure and function in severe preeclampsia pregnant women and their fetus have nothing to do with the concentration of angiotensinⅡ(AngⅡ).8. The concentration of angiotensinⅡin the severe preeclampsia women and their fetus who with AT1R gene 1166 polymorphic site AC+CC-type is much more than the fetus who with AT1R gene 1166 polymorphic site AA-type, the variation is statistically significant (P<0.05).9. The level of ET in case groups both pregnant women and fetus is significant higher than it in the control group (P<0.01).10. In the both severe preeclampsia and normal pregnant women, the relation of the ET level with IVST, LVSD, PWT, LVM is positive correlation (P<0.05), the relation with LVMI is closely (P<0.001), the relation with the ratio of E/A is negative correlation (P<0.001). The level of ET is no related with LVDD and RWT and EF (P>0.05).11. The ET level of pregnant women and their fetus with AT1R gene 1166 polymorphic site AC+CC-type is higher than it with AT1R gene 1166 polymorphic site AA-type, the variation is statistically significant (P<0.05).Conclusion1. The relation of AT1R gene 1166 polymorphism with severe preeclampsia is positive correlation, indicating that the very site might be a risk factor for severe preeclampsia, the risk of preeclampsia would increase when AT1R gene 1166 C allel occur, it means that AT1R gene 1166 C allel is a predisposing genes for preeclampsia.2. The expression of AT1R gene 1166 polymorphism in severe pregnant women as same as the expression in their fetus, Gene mutation of AT1R gene 1166 C allel can be take as a important geno-marker to predict severe preeclampsia, the early prophylaxis could be done for the high-risk group with AT1R gene 1166 polymorphic site AC and CC-type.3. Left ventricle reconstruction occurs in the severe preeclampsia patients and their fetus. AT1R gene 1166 polymorphic site AC/CC-type and C allel are related to the left ventricle reconstruction of severe preeclampsia patients and their fetus.4. The change of left ventricle configuration in severe preeclampsia patients is related to the poor pregnant outcome and can be observed by echocardiogram, concentric reconstruction and concentric hypertrophy are independent risk factors for predicting poor pregnant outcome.5. Excluding the factor of AngⅡlevel, the left ventricle reconstruction of severe preeclampsia is affected by the blood vessel reactance to the AngⅡand activation of AT1R. AngⅡand AT1R can cause left ventricle cadiocyte hypertrophy and interstitial remodeling of pregnant women and fetus respectively.6. The plasma concentration of ET is a sensitive index, gene mutation of AT1R gene 1166 C allel in severe preeclampsia pregnant women and fetus is related to the increase of ET level.