Alternative Roles of STAT3 and MAPK Signaling Pathways in the MMPs Activation and Progression of Lung Injury Induced by Cigarette Smoke Exposure in ACE2 Knockout Mice

Inflammation-mediated abnormalities in the renin-angiotensin system (RAS) and expression of matrix metalloproteinases (MMPs) are implicated in the pathogenesis of lung injury. Angiotensin converting enzyme II (ACE2), an angiotensin converting enzyme (ACE) homologue that displays antagonist effects on ACE/angiotensin II (Ang II) axis, could also play a protective role against lung diseases. However, the relationship between ACE2 and MMPs activation in lung injury is still largely unclear. The purpose of this study is to investigate whether MMPs activity could be affected by ACE2 and which ACE2 derived signaling pathways could be also involved via using a mouse model with lung injury induced by cigarette smoke (CS) exposure for 1 to 3 weeks. Wild-type (WT; C57BL/6) and ACE2 KO mice (ACE2^-/-) were utilized to study CS-induced lung injury. Increases in the resting respiratory rate (RRR), pulmonary immunokines, leukocyte infiltration and bronchial hyperplasia were observed in the CS-exposed mice. Compared to WT mice, more serious physiopathological changes were found in ACE2^-/- mice in the first week of CS exposure. CS exposure increased pulmonary ACE and ACE2 activities in WT mice, and significantly increased ACE in ACE2^-/- mice. Furthermore, the activity of pulmonary MMPs was decreased in CS-exposed WT mice, whereas this activity was increased in ACE2^-/- mice. CS exposure increased the pulmonary p-p38, p-JNK and p-ERK1/2 level in all mice. In ACE2^-/- mice, a significant increase p-STAT3 signaling was detected; however, no effect was observed on the p-STAT3 level in WT mice. Our results support the hypothesis that ACE2 deficiency influences MMPs activation and STAT3 phosphorylation signaling to promote more pulmonary inflammation in the development of lung injury.     

The relationship between ACE inhibitory activity and degradations of sulfur containing materials in Dolsan leaf mustard juice

This study was carried out to investigate the relationship ACE inhibitory activity and degradations of sulfur containing materials in Dolsan leaf mustard juice (DLMJ). The changes of sulfur containing materials which were treated with autolysis, myrosinase, ascorbate and papain were studied, as well as the changes of ACE inhibitory activity in DLMJ. At 37°C, sulfur containing materials by autolysis decreased most rapidly from 0.43% to 0.13% in the second day. Conversely, ACE inhibitory activity increased most from 66% to 87%, in the second day at 37°C. As myrosinase concentrations increased more, sulfur containing materials in DLMJ decreased more. The ACE inhibitory activities at 0, 0.5, 1, 2, and 4 Units of myrosinase for 240 min later were 70, 74, 75, 82, and 85%, respectively. At 1 mM ascorbate, concentrations of sulfur containing materials in DLMJ decreased more significantly on the second day than on the other days. At 1 mM ascorbate for 6 days, ACE inhibitory activity reached a maximum of about 92%. And, an increase of papain concentration was noted in accordance with a decreased sulfur containing materials. The maximum rate of ACE inhibitory activity at control, 3, 6, and 12 Units of papains treatments was shown as 70, 70, 75, and 78% at 60 min, respectively. These results suggested that the degradation of sulfur containing materials led to the increase of ACE inhibitory activity. Consequently, it was suggested that ACE inhibiting was significantly related to the degradatives of sulfur containing materials.     

The distinction between transudates and exudates

Summary The first step in the diagnosis of pleural effusions is the distinction between exudates and transudates. The aim of this study was to evaluate the usefulness of various parameters for the differentiation of pleural exudates and transudates. We recorded clinical characteristics, final diagnoses, and measured pleural fluid and serum levels of albumin, protein, LDH, cholesterol, and bilirubin of 381 consecutive patients with pleural effusion. Seventy-one (23%) pleural effusions were transudates and 236 were exudates. As a single criterion, the pleural fluid to serum albumin ratio >0.5 was the most accurate parameter (88.4%). An albumin gradient of 12 g/l had an accuracy of 75% in the whole population but it detected 96% of transudative effusions in patients treated with diuretics. Light’s criteria and abbreviated Light’s criteria had similar accuracies, 87.8% vs. 88.2%, respectively. In conclusions, different alternatives can be used instead of Light’s criteria.     

Parallel effects of genetic variation in ACE activity in baboons and humans

Like humans, savannah baboons (Papio sp.) show heritable interindividual variation in complex physiological phenotypes. One prominent example of such variation involves production of the homeostatic regulator protein angiotensin converting enzyme (ACE), which shows heritable variation in both baboons and humans. In humans, this phenotypic variation is associated with an Alu insertion-deletion polymorphism in the ACE gene, which explains approximately half of the variation in serum ACE activity. We identified a similar Alu insertion-deletion polymorphism in the baboon ACE homologue and measured its frequency in a wild population and a captive population of baboons. We also analyzed the contribution of ACE genotype at this indel to variation in serum ACE activity in the captive population. When conditioned on weight, a known factor affecting ACE activity in humans, age and ACE genotype both accounted for variance in ACE activity; in particular, we identified a significant nonadditive interaction between age and genotype. A model incorporating this interaction effect explained 21.6% of the variation in residual serum ACE activity. Individuals homozygous for the deletion mutation exhibited significantly higher levels of ACE activity than insertion-deletion heterozygotes at younger ages (10-14 years), but showed a trend towards lower levels of ACE activity compared with heterozygotes at older ages (> or =15 years). These results demonstrate an interesting parallel between the genetic architecture underlying ACE variation in humans and baboons, suggesting that further attention should be paid in humans to the relationship between ACE genetic variation and aging.     

肠淋巴液引流对失血性休克小鼠心肌组织ACE/ACE2的作用

目的：观察失血性休克后小鼠心肌组织血管紧张素转换酶（ACE）/ACE2平衡的变化及肠淋巴液引流（PHSML）的作用。方法：BALB/c雄性小鼠24只,随机分为对照组、假手术组、休克组、休克+引流组（n=6）。建立失血性休克模型,行液体复苏;休克+引流组液体复苏后,引流肠淋巴液。在液体复苏后6 h或假手术组相应时间点、对照组于麻醉后,留取心肌组织,qRT-PCR法检测ACE、ACE2、血管紧张素Ⅱ （Ang Ⅱ）1型受体（AT1R）、Mas相关G蛋白偶联受体（Mas1R）的mRNA表达,ELISA方法检测Ang Ⅱ和Ang （1-7）含量。结果：休克组小鼠心肌组织ACE与AT1R mRNA表达、Ang Ⅱ水平均显著高于对照组与假手术组,ACE2与Mas1R mRNA表达显著低于对照组与假手术组、Ang （1-7）含量显著低于对照组,ACE/ACE2、Ang Ⅱ/Ang （1-7）、AT1R/Mas1R显著高于对照组与假手术组;PHSML引流显著抑制了失血性休克对这些指标的作用。结论：失血性休克上调心肌ACE-Ang Ⅱ-AT1R轴、下调ACE2-Ang （1-7）-Mas1R轴表达,引起ACE/ACE2失衡;PHSML引流下调ACE-Ang Ⅱ-AT1R轴、上调ACE2-Ang （1-7）-Mas1R轴表达,在一定程度上维持了ACE/ACE2平衡。     

血管紧张素转换酶2-血管紧张素1-7-Mas轴对血管作用的研究进展

血管紧张素转换酶2（ACE2）和Mas受体的发现使人们对肾素-血管紧张素（RAS）有了更全面的认识。ACE2可水解血管紧张素Ⅰ和血管紧张素Ⅱ直接或间接生成血管紧张素1-7（Ang 1-7）,并与高血压的形成密切相关。Ang 1-7主要通过Mas受体引起血管舒张、抑制细胞增殖。ACE2-Ang1-7-Mas轴的发现为RAS的研究、高血压等心血管疾病的防治和新药开发提供了新的思路和方向。     

ACE2/Ang-(1–7) signaling and vascular remodeling

The renin-angiotensin system (RAS) regulates vascular tone and plays a critical role in vascular remodeling, which is the result of a complex interplay of alterations in vascular tone and structure. Inhibition of the RAS has led to important pharmacological tools to prevent and treat vascular diseases such as hypertension, diabetic vasculopathy and atherosclerosis. Angiotensin converting enzyme 2 (ACE2) was recently identified as a multifunctional monocarboxypeptidase responsible for the conversion of angiotensin (Ang) II to Ang-(1–7). The ACE2/Ang-(1–7) signaling has been shown to prevent cellular proliferation, pathological hypertrophy, oxidative stress and vascular fibrosis. Thus, the ACE2/Ang-(1–7) signaling is deemed to be beneficial to the cardiovascular system as a negative regulator of the RAS. The addition of the ACE2/Ang-(1–7) signaling to the complexities of the RAS may lead to the development of novel therapeutics for the treatment of hypertension and other vascular diseases. The present review considers recent findings regarding the ACE2/Ang-(1–7) signaling and focuses on its regulatory roles in processes related to proliferation, inflammation, vascular fibrosis and remodeling, providing proof of principle for the potential use of ACE2 as a novel therapy for vascular disorders related to vascular remodeling.     

Vascular endothelial growth factor in malignant pleural effusion associated with lung cancer

The presence of vascular endothelial growth factor (VEGF) was examined by enzyme immunoassay in 60 cytology-documented malignant pleural effusions associated with primary lung cancer and 51 other benign and malignant pleural effusions. Exudative pleural effusions contained significantly higher amounts of VEGF than transudative pleural effusions. Among exudative pleural effusions, levels of VEGF in malignant pleural effusions associated with lung cancer were significantly higher than those of benign exudative pleural effusions. There was no significant difference in pleural VEGF in patients with different histological types or clinical stages of lung cancer. Serial measurement of pleural VEGF levels was performed in six lung cancer patients treated with intrapleural instillation of recombinant interferon γ, and reduction of pleural effusion was associated with decreasing pleural VEGF levels. These findings suggest that VEGF has a role in the accumulation of exudative pleural effusions, especially that of malignant pleural effusion associated with lung cancer. Received: 14 April 1999 / Accepted: 10 June 1999     

Joseph Rudinger memorial lecture: Unexpected functions of angiotensin converting enzyme,beyond its enzymatic activity

Angiotensin converting enzyme (ACE) is a well‐known enzyme, largely studied for its action on hypertension, as it produces angiotensin II from angiotensin I. This paper describes two original behaviours of ACE. We showed that ACE could hydrolyse gastrin, a neuropeptide from the gastrointestinal tract, releasing the C‐terminal amidated dipeptide H‐Asp‐Phe‐NH₂. This dipeptide is believed to be involved in the gastrin‐induced acid secretion in the stomach. This hypothetic mechanism of action of gastrin resulted in a strategy to rationally design gastrin receptor antagonists. Beyond, we showed that the brain renin angiotensin system (RAS) could be activated by a new characterized peptide named acein, resulting in stimulation of dopamine release within the striatum. This new and original ‘receptor‐like’ activity for brain membrane‐bound ACE is quite significant taking into account the role of dopamine in the brain, particularly in neurodegenerative diseases. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

细胞因子IFN-γ,IL-2,TNF-α和ADA对结核性和恶性胸腔积液鉴别诊断的价值

目的：探讨细胞因子γ-干扰素（IFN-γ）、白介素-2（IL-2）、肿瘤坏死因子-α（TNF-α）和腺苷脱氨酶（ADA）对结核性和恶性胸腔积液的鉴别诊断的价值。方法：以2012年9月至2013年3月期间在青岛大学医学院附属医院呼吸科及青岛胸科医院未经治疗的胸腔积液患者为研究对象,其中恶性胸腔积液患者46例,结核性胸腔积液患者42例。采用双抗体夹心酶联免疫吸附测定法（ELISA）分别检测结核性和恶性胸腔积液患者中IFN-γ、IL-2、TNF-α及ADA的表达情况。并应用ROC曲线分析两组患者胸腔积液中IFN-γ、IL-2、TNF-α及ADA的表达差异及意义。结果：结核性胸腔积液组IFN-γ、IL-2、TNF-α及ADA的表达明显高于恶性胸腔积液组,差异有统计学意义（t=8.118、8.126、8.066、7.221;P=0.000、0.000、0.000、0.000,P〈0.001）;ROC曲线分析结果显示胸腔积液中IFN-γ、IL-2、TNF-α及ADA的诊断临界值为201.45 pg/mL、41.91 pg/mL、21.55 pg/mL、33.78 U/L;诊断敏感度分别为91.3%、93.5%、91.2%、89.1%;特异度分别为91.0%、92.1%、89.9%、90.1%。结论：胸腔积液中IFN-γ、IL-2、TNF-α及ADA的表达对结核性和恶性胸腔积液诊断与鉴别诊断具有重要参考价值。     

Characterization of Angiotensin Converting Enzyme-2 (ACE2) in Human Urine

Angiotensin converting enzyme-2 (ACE2) is a recently described membrane-bound carboxypeptidase identified by its homology to ACE, the enzyme responsible for the formation of the potent vasoconstrictor angiotensin II (Ang II). ACE2 inactivates Ang II and is thus thought to act in a counter-regulatory fashion to ACE. ACE2 is highly expressed in epithelial cells of distal renal tubules, and recent evidence indicates that expression is increased in a range of renal diseases. A soluble form of ACE, generated by proteolytic cleavage of the membrane-bound form, has been shown to be present in urine; although evidence for a similar release of ACE2 has been reported in cell culture, it is not yet known whether this occurs in vivo. The present study has identified ACE2 in human urine, both by a sensitive fluorescence-based activity assay and by Western immunoblot. Levels of ACE2 were surprisingly higher than ACE, which may reflect preferential targeting of the enzyme to the luminal surface of the renal epithelium. Future studies will determine whether increased expression of ACE2 in renal diseases are reflected in higher urinary levels of this novel enzyme.Australian Peptide Conference Issue.     

类ACE抑制肽的合成及其活性分析

血管紧张素转换酶(angiotensin converting enzyme,ACE)通过作用于维持血压正常的肾素-血管紧张系统(rennin-angiotensin system, RAS)和激肽释放酶 激肽系统(kallikrein-kinin system, KKS),使其失衡导致血压升高．而ACE活性抑制肽可以竞争性地与ACE的活性中心结合,从而抑制ACE的活性,使血压降低．天然来源的ACE抑制肽与传统的降压药物相比效果较好,无毒副作用,对正常血压没有影响,对于高血压的治疗和人类健康具有重要意义. 本文以酪蛋白中提取的ACE活性抑制肽KVLPVP为先导肽,根据ACE抑制肽的结构特点,设计合成一系列的类ACE肽(similar ACE-like peptides). 利用反相高效液相色谱法(RP-HPLC)直接测定其体外ACE抑制活性. 结果表明,当芳香性的氨基酸残基Phe、Tyr、His和疏水性Val残基位于C-端时会提高多肽的ACE抑制活性,尤其是His位于C 端时,ACE抑制活性更强. 通过对比先导肽与所合成的类ACE肽的ACE活性抑制率,可以发现,类ACE肽的ACE活性抑制率均高于先导肽．基于不同氨基酸残基位于C-端时对多肽的ACE抑制活性的研究,可以为降血压药物分子设计和筛选提供基础.     

The acute-phase proteins serum amyloid A and C reactive protein in transudates and exudates

The distinction between exudates and transudates is very important in the patient management. Here we evaluate whether the acute-phase protein serum amyloid A (SAA), in comparison with C reactive protein (CRP) and total protein (TP), can be useful in this discrimination. CRP, SAA, and TP were determined in 36 exudate samples (27 pleural and 9 ascitic) and in 12 transudates (9 pleural and 3 ascitic). CRP, SAA, and TP were measured. SAA present in the exudate corresponded to 10% of the amount found in serum, that is, the exudate/serum ratio (E/S) was 0.10 +/- 0.13. For comparison, the exudate/serum ratio for CRP and TP was 0.39 +/- 0.37 and 0.68 +/- 0.15, respectively. There was a strong positive correlation between serum and exudate SAA concentration (r = 0.764; p < 0.0001). The concentration of SAA in transudates was low and did not overlap with that found in exudates (0.02-0.21 versus 0.8-360.5 g/mL). SAA in pleural and ascitic exudates results mainly from leakage of the serum protein via the inflamed membrane. A comparison of the E/S ratio of SAA and CRP points SAA as a very good marker in discriminating between exudates and transudates.     

ACE2及其特殊功能

血管紧张素转换酶2（angiotensin—converting enzyme 2,ACE2）是新发现的与血管紧张素转换酶（ACE）相关的羧肽酶,在肾素-血管紧张素系统（rennin-angiotensin system,RAS）中ACE2可以使AngⅡ转换为Ang1-7,从而产生与血管紧张素Ⅱ相反的效应,同时ACE2还可使Ang I转换为Ang1-9。研究发现：ACE2与高血压、SARS以及肾脏、生殖等系统的疾病有着密切的关系。     

Reciprocal changes in renal ACE/ANG II and ACE2/ANG 1-7 are associated with enhanced collecting duct renin in Goldblatt hypertensive rats

Alterations in the balance between ANG II/ACE and ANG 1-7/ACE2 in ANG II-dependent hypertension could reduce the generation of ANG 1-7 and contribute further to increased intrarenal ANG II. Upregulation of collecting duct (CD) renin may lead to increased ANG II formation during ANG II-dependent hypertension, thus contributing to this imbalance. We measured ANG I, ANG II, and ANG 1-7 contents, angiotensin-converting enzyme (ACE) and ACE2 gene expression, and renin activity in the renal cortex and medulla in the clipped kidneys (CK) and nonclipped kidneys (NCK) of 2K1C rats. After 3 wk of unilateral renal clipping, systolic blood pressure and plasma renin activity increased in 2K1C rats (n = 11) compared with sham rats (n = 9). Renal medullary angiotensin peptide levels were increased in 2K1C rats [ANG I: (CK = 171 ± 4; NCK = 251 ± 8 vs. sham = 55 ± 3 pg/g protein; P < 0.05); ANG II: (CK = 558 ± 79; NCK = 328 ± 18 vs. sham = 94 ± 7 pg/g protein; P < 0.001)]; and ANG 1-7 levels decreased (CK = 18 ± 2; NCK = 19 ± 2 pg/g vs. sham = 63 ± 10 pg/g; P < 0.001). In renal medullas of both kidneys of 2K1C rats, ACE mRNA levels and activity increased but ACE2 decreased. In further studies, we compared renal ACE and ACE2 mRNA levels and their activities from chronic ANG II-infused (n = 6) and sham-operated rats (n = 5). Although the ACE mRNA levels did not differ between ANG II rats and sham rats, the ANG II rats exhibited greater ACE activity and reduced ACE2 mRNA levels and activity. Renal medullary renin activity was similar in the CK and NCK of 2K1C rats but higher compared with sham. Thus, the differential regulation of ACE and ACE2 along with the upregulation of CD renin in both the CK and NCK in 2K1C hypertensive rats indicates that they are independent of perfusion pressure and contribute to the altered content of intrarenal ANG II and ANG 1-7.     

Angiotensin I-converting enzyme insertion-related genotypes and allele are associated with higher susceptibility of endometriosis and leiomyoma

Endometriosis and leiomyoma display features similar to malignancy, requiring neovascularization to proliferation and growth. Altered vascular-related genes might be related to the development of endometriosis and leiomyoma. Polymorphisms of the angiotensin-converting enzyme (ACE) insertion/deletion (I/D) genes have been linked with some vascular diseases. This study investigates whether ACE I/D gene polymorphisms could be used as markers of susceptibility in endometriosis and leiomyoma. Women were divided into three groups: (1) endometriosis (n = 125); (2) leiomyoma (n = 120); (3) normal controls (n = 128). Genomic DNA was obtained from peripheral leukocyte. ACE I/D gene polymorphisms in intron 16 were amplified by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) Genotypes and allelic frequencies in both groups were compared. We observed the genotype distribution and allele frequency of ACE I/D gene polymorphisms in both groups were significantly different. Proportions of ACE*I homozygote/heterozygote/D homozygote in both groups were: (1) 50.4/24/25.6%; (2) 25/23.33/51.67%; (3) 10.2/29.7/60.1%. Proportions of I/D alleles in each group were: (1) 62.4/37.6%; (2) 36.7/63.3%; (3) 25/75%. We concluded that ACE*I/D gene polymorphisms are associated with endometriosis and leiomyoma susceptibilities. ACE*I-related genotypes and allele are strongly related to the occurrence of endometriosis and moderately related to the occurrence of leiomyoma.     

Cytopathological spectrum of unusual malignant pleural effusions at a tertiary care centre in north India

BACKGROUND: Cytological examination of pleural fluid is one of the most informative laboratory procedures in the diagnosis of pleural effusions. Although tuberculosis is the commonest cause of pleural effusions in developing countries, tumours, including grade ones, can present with effusions. OBJECTIVE: The aim of the present study was to evaluate the uncommon causes of malignant pleural effusion. METHODS: A 2-year retrospective analysis of pleural fluid cytological specimens submitted to the Department of Cytopathology, PGIMER, Chandigarh between January 2003 and December 2004 was performed to retrieve unusual metastases. Out of a total of 898 samples reviewed, 710 were negative for malignancy and 24 cases were suspicious for malignancy. The remaining 164 cases were positive for malignancy, out of which 38 cases revealed malignancies other than adenocarcinoma. RESULTS: The 38 unusual malignancies metastasizing to the pleural cavity included 29 haematological malignancies (non-Hodgkin's lymphoma, acute lymphoid leukaemia, multiple myeloma and chronic myeloid leukaemia) and nine non-haematological malignancies (Ewing's sarcoma, neuroblastoma, Wilms' tumour, squamous cell carcinoma, small-cell carcinoma and malignant fibrous histiocytoma). CONCLUSION: Although metastatic adenocarcinoma was the commonest aetiology of malignant pleural effusions, a significant number of unusual causes of malignant pleural effusion were also encountered.     

Attenuation of changes in G(i)-proteins and adenylyl cyclase in heart failure by an ACE inhibitor, imidapril

Cardiac dysfunction in animals with congestive heart failure due to myocardial infarction (MI) is known to be associated with a wide variety of defects in receptor and post-receptor mechanisms. Since the heart function have been shown to be improved by treatment with different angiotensin converting enzyme (ACE) inhibitors, we examined the effects of imidapril, an ACE inhibitor, on changes in post-receptor mechanisms involving adenylyl cyclase (AC) and G proteins in the failing heart. Heart failure in rats was induced by occluding the coronary artery and 3 weeks later the animals were treated daily with 1 mg/kg (orally) imidapril for 5 weeks. The animals were assessed for their left ventricular function and crude membranes were isolated from the viable left ventricle and examined for AC activities as well as G-protein activities and expression. Animals with heart failure exhibited depressions in ventricular function and AC activities in the absence or presence of forskolin, NaF and Gpp(NH)p. The AC activity in the presence of pertussis toxin was increased whereas that in the presence of cholera toxin was decreased in the failing heart. Protein contents and mRNA levels for G_i-proteins were increased whereas those for G_s-proteins were unaltered in the infarcted heart. All these changes due to MI were prevented by imidapril treatment. The results indicate that the depressed cardiac function in the failing heart may partly be due to the direct effects of changes in AC and G_i proteins.     

AT2R − 1332 G:A polymorphism and its interaction with AT1R 1166 A:C,ACE I/D and MMP-9 − 1562 C:T polymorphisms: Risk factors for susceptibility to preeclampsia

The possible association of angiotensin type 2 receptor (AT2R) − 1332 G:A polymorphism with susceptibility to preeclampsia was studied in 252 women consisted of 155 women with preeclampsia and 97 healthy pregnant women. Also, the interaction of this polymorphism with angiotensin type 1 receptor (AT1R) 1166 A:C, angiotensin converting enzyme insertion/deletion (ACE I/D) and also with matrix metalloproteinase-9 (MMP-9) − 1562 C:T polymorphism was investigated. The AT2R − 1332 G:A polymorphism was detected using PCR–RFLP method. Significantly higher frequencies of GG+GA genotype and G allele of AT2R were observed in mild (80.2%, p = 0.003 and 47.5%, p = 0.012, respectively) and severe (77.8%, p = 0.034 and 48.1%, p = 0.026, respectively) preeclampsia compared to controls (60.8% and 35.1%, respectively). The presence of G allele was associated with 1.69-fold increased risk of preeclampsia (p = 0.005). In severe preeclamptic women, systolic and diastolic blood pressures in the presence of GG+GA genotype were significantly higher compared to those in the presence of AA genotype. The concomitant presence of both alleles of AT2R G and AT1R C was associated with 1.3 times increased risk of mild preeclampsia (p = 0.03). There was an interaction between AT2R G and ACE D alleles that significantly increased the risk of mild and severe preeclampsia by 1.38- and 1.3-fold, respectively. Also, interaction between MMP-9 T and AT2R G alleles increased the risk of severe preeclampsia 1.39-fold (p = 0.028). Our study demonstrated that the G allele of AT2R − 1332 G:A polymorphism is associated with an increased risk of preeclampsia. Also, epistatic interaction of G allele and each allele of the AT1R C, ACE D and MMP-9 T was associated with the risk of preeclampsia. Our findings suggest that the renin–angiotensin system (RAS) variants and gene–gene interactions affect the risk of preeclampsia.