Angiotensinogen gene haplotype is associated with the prevalence of Japanese non-alcoholic steatohepatitis

No Association Between AGT Gene Polymorphisms with Hypertension in a South African Population

Purpose

Hypertension is a leading cause of cardiovascular-related morbidity and mortality worldwide, with a prevalence increasing at an alarming rate in both middle- and low-income countries. Various environmental and genetic factors have been attributed to play a significant role in the increasing prevalence of hypertension. Single nucleotide polymorphisms (SNPs) in the angiotensinogen (AGT) gene are reported to have a significant association with hypertension; however, there are limited studies done on South African populations. Therefore, this case-control study aimed to investigate the association between AGT SNPs (rs2004776, rs3789678, rs5051 and rs7079) with hypertension in a study population of isiXhosa-speaking participants from the Eastern Cape Province in South Africa.

Materials and Methods

The SNPs were genotyped in 250 hypertensive cases and 237 normotensive controls, using TaqMan genotyping assays.

Results

For the SNP rs2004776, the frequency of CC genotype (18.4%) and C allele (44%) in hypertensive cases showed no significant differences (p = 0.52, χ2 = 1.32), when compared to the normotensive control group (CC: 19.8% and C allele: 43%). Similar results were obtained for the genotypic and allelic frequencies between hypertensive cases and normotensive controls for rs3789678 (p = 0.88, χ2=0.26) and rs5051 (p = 0.57, χ2=1.12), and rs7079 (p = 0.33, χ2=2.23). These findings demonstrate that there were no significant associations between the SNPs rs2004776, rs3789678, rs7079, rs5051 with hypertension in our study population.

Conclusion

These findings suggest that AGT gene polymorphisms are not associated with the development of hypertension in the studied population. The present study represents the first genetic report to investigate the AGT gene polymorphisms with hypertension in an isiXhosa-speaking South African population.

Nonalcoholic Fatty Liver Disease (NAFLD) and Cardiovascular Risk: Is Imaging Helpful?

Nonalcoholic Fatty Liver Disease (NAFLD) is proving to be a globally prevalent condition. Moreover, NAFLD may be an independent risk factor associated with higher cardiovascular (CVD) morbidity and mortality. Further studies are needed to assess whether NAFLD needs to be included in the atherosclerotic risk score algorithms or whether patients with NAFLD need to be screened early on to assess their CVD risk especially since imaging such as positron emission tomography can be used to assess both NAFLD and CV disease at the same time. Therefore employing cardiovascular imaging modalities to investigate the incidence, extent, and nature of atherosclerotic lesions in NAFLD may be beneficial. Additionally, whether treating NAFLD halts the progression of CVD on imaging remains to be seen. Further research to delineate NAFLD and CVD associations, deciphering screening imaging modalities, and investigating targeted interventions could improve CVD morbidity and mortality in NAFLD.

NAFLD-related hepatocellular carcinoma: The growing challenge

Hepatocellular carcinoma (HCC) is a common cause of cancer-related mortality and morbidity worldwide. With the obesity pandemic, NAFLD-related HCC is contributing to the burden of disease exponentially. Genetic predisposition and clinical risk factors for NAFLD-related HCC have been identified. Cirrhosis is a well-known and major risk factor for NAFLD-related HCC. However, the occurrence of NAFLD-related HCC in patients without cirrhosis is increasingly recognized and poses a significant challenge regarding cancer surveillance. It is of paramount importance to develop optimal risk stratification scores and models to identify subsets of the population at high risk so they can be enrolled in surveillance programs. In this review, we will discuss the risks and prediction models for NAFLD-related HCC.

Polymorphism rs7079 in miR-31/-584 Binding Site in Angiotensinogen Gene Associates with Earlier Onset of Coronary Artery Disease in Central European Population

Angiotensinogen (AGT) represents a key component of the renin-angiotensin-aldosterone system (RAAS). Polymorphisms in the 3' untranslated region (3'UTR) of the AGT gene may alter miRNA binding and cause disbalance in the RAAS. Within this study, we evaluated the possible association of AGT +11525C/A (rs7079) with the clinical characteristics of patients with coronary artery diseases (CAD). Selective coronarography was performed in 652 consecutive CAD patients. Clinical characteristics of the patients, together with peripheral blood samples for DNA isolation, were collected. The genotyping of rs7079 polymorphism was performed with TaqMan^® SNP Genotyping Assays. We observed that patients with the CC genotype were referred for coronarography at a younger age compared to those with the AA+CA genotypes (CC vs. AA+CA: 59.1 ± 9.64 vs. 60.91 ± 9.5 (years), p = 0.045). Moreover, according to the logistic regression model, patients with the CC genotype presented more often with restenosis than those with the CA genotype (p = 0.0081). In conclusion, CC homozygotes for rs7079 present with CAD symptoms at a younger age compared with those with the AA+CA genotype, and they are more prone to present with restenosis compared with heterozygotes.

A new model of the mechanism underlying lead poisoning: SNP in miRNA target region influence the AGT expression level

Background

To determine if the rs7079 polymorphism located in the 3′ UTR of the angiotensinogen gene (AGT) altered AGT gene expression and the risk of lead poisoning. A case-control study and luciferase reporter gene assay identified a significant association between rs7079 variants and the risk of lead poisoning.

Results

Serum AGT levels were significantly higher in individuals carrying the rs7079 CA genotype, as compared to those carrying the rs7079 CC genotype. The binding of the miRNA mimics miR-31-5p and miR-584-5p to the 3′ UTR of AGT differed based on which rs7079 variant was present, implying that AGT gene expression depends on the rs7079 variant carried.

Conclusions

The rs7079 C to A substitution reduced the binding of miR-31-5p/miR-584-5p to the 3′ UTR of AGT, possibly altering the risk of lead poisoning.

Non-alcoholic fatty liver disease and hypertension: coprevalent or correlated?

OBJECTIVE

To provide a comprehensive review summarizing the existing evidence on the association between nonalcoholic fatty liver disease (NAFLD) and hypertension (HT) independent of other components of metabolic syndrome.

METHODS

We searched the literature through Medline and the Cochrane Library for studies evaluating the relationship between hypertension and fatty liver disease.

RESULTS

Studies testing this association are limited, but agree that HT and fatty liver disease are inter-related independent of other components of the metabolic syndrome such as obesity and diabetes mellitus. Clinical evidence shows that NAFLD is associated with new-onset HT, whereas increased blood pressure is related to the development of fatty liver disease and the possible subsequent progression to liver fibrosis. Insulin resistance and activation of the renin-angiotensin-aldosterone system (RAAS) might provide potential pathophysiologic links between these clinical entities. Until further evidence is available, patients with HT should be meticulously evaluated and treated for fatty liver disease and vice versa. RAAS inhibitors have been tested in NAFLD, presenting a favorable profile by decreasing insulin resistance and fibrosis progression.

CONCLUSION

NAFLD and HT are associated independent of traditional cardiovascular risk factors. Insulin resistance appears to be the main linking mechanism. Although RAAS inhibitors are the most beneficial treatment option for HT in patients with NAFLD, randomized studies on the administration of these agents in HT patients with NAFDL are warranted to provide optimal treatment options in these high cardiovascular risk individuals.

Analogy between non-alcoholic steatohepatitis (NASH) and hypertension: a stepwise patient-tailored approach for NASH treatment

Non-alcoholic steatohepatitis (NASH) is a common liver disorder worldwide. Although there has been improvement in our understanding of the natural history and pathogenesis of the disease, there is still no approved therapy for NASH. NASH shares many similarities with primary hypertension, in that both are extremely common disorders that can easily lead to serious complications if left untreated. Both conditions are viewed as "silent killers", because the disease can progress over a period of time prior to the occurrence of potentially deadly outcomes. While attempts to find the "miracle pill" for NASH are unrealistic, we can make an analogy with the "stepwise combination" approach developed over the last few decades for the treatment of hypertension. In the present review, we summarize some of the similarities in the concepts that underlie NASH and hypertension. The development of a stepwise patient-tailored method for the treatment of NASH is presented.

Hypertension, diabetes, atherosclerosis and NASH: Cause or consequence?

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common forms of chronic liver disease worldwide and its prevalence is expected to continue rising. NAFLD has traditionally been considered a consequence of metabolic syndrome (MetS). However, the link between NAFLD and MetS components, especially type 2 diabetes mellitus (T2DM), hypertension (HTN), and cardiovascular disease (CVD) is more complex than previously thought. Indeed, the adverse effects of NAFLD extend far beyond the liver, with a large body of clinical evidence now suggesting that NAFLD may precede and/or promote the development of T2DM, HTN and atherosclerosis/CVD. The risk of developing these cardiometabolic diseases parallels the underlying severity of NAFLD. Accumulating evidence suggests that the presence and severity of NAFLD is associated with an increased risk of incident T2DM and HTN. Moreover, long-term prospective studies indicate that the presence and severity of NAFLD independently predicts fatal and nonfatal CVD events. In this review, we critically discuss the rapidly expanding body of clinical evidence that supports the existence of a bi-directional relationship between NAFLD and various components of MetS, particularly T2DM and HTN, as well as the current knowledge regarding a strong association between NAFLD and CVD morbidity and mortality. Finally, we discuss the most updated putative biological mechanisms through which NAFLD may contribute to the development of HTN, T2DM and CVD.

Significance of genetic polymorphisms in patients with nonalcoholic fatty liver disease

Because of recent advances in genetic research such as genome-wide association studies, the underlying genetic mechanisms of nonalcoholic fatty liver disease (NAFLD) pathophysiology have been elucidated. Here, we present a review of the current literature on the impact of genetic polymorphisms in patients with NAFLD. These genetic polymorphisms, which regulate lipid metabolism, glucose metabolism, and the renin-angiotensin system, are involved in NAFLD onset, steatosis, inflammation, fibrosis, and hepatocellular carcinoma (HCC). Among these genetic polymorphisms, many studies and meta-analyses have demonstrated that position 148 (rs738409 C/G) of the patatin-like phospholipase domain-containing protein (PNPLA3) is a genetic factor associated with NAFLD pathophysiological features, such as hepatic fat level, hepatic inflammation, fibrosis, and HCC. However, the impact of genetic polymorphisms on NAFLD pathophysiology appears to differ among ethnic groups. Therefore, further studies with larger sample sizes are needed for each ethnic group.

Risk given by AGT polymorphisms in inducing susceptibility to essential hypertension among isolated populations from a remote region of China: A case-control study among the isolated populations

INTRODUCTION

Hypertension is a serious risk factor affecting up to 30% of the world's population with a heritability of more than 30-50%. The aim of this study was to investigate the contribution of the polymorphisms localized in the angiotensinogen (AGT) gene, a main component of the renin-angiotensin-aldosterone system, in inducing the susceptibility to essential hypertension (EH) among isolated populations (Yi and Hani minorities) with low prevalence rate from the remote region of Yunnan in China.

METHODS

A case-control association study was performed, and all subjects were genotyped for the seven single nucleotide polymorphisms localized in the AGT region by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Three polymorphisms, i.e. rs5046, rs5049, and rs2478544, were significantly associated with EH among the Hani minority. The associations, found in the Yi minority, did not reach a conclusive level of statistical significance. The polymorphisms of rs2478544 and rs5046 caused the transformations of exonic splicing enhancer sites and transcription factor binding sites, respectively, in the bioinformatic analyses. The haplotype-rs5046T, rs5049A, rs11568020G, rs3789679C, rs2478544C was susceptible for EH among the Hani minority.

CONCLUSION

Our findings suggested that the AGT polymorphisms have played a vital role in determining an individual's susceptibility to EH among the isolated population, which would be helpful for EH management in the remote mountainous region of Yunnan in China.

Human angiotensinogen +11525 C/A polymorphism modulates its gene expression through microRNA binding

Hypertension is a serious risk factor for cardiovascular disease. Like other complex disease, hypertension is caused by a combination of genetic and environmental factors. The renin-angiotensin system plays an important role in the regulation of blood pressure. Angiotensinogen (AGT) gene is associated with essential hypertension in Caucasians, Japanese, and Asian-Indian subjects. AGT gene may also be associated with cardiac hypertrophy, coronary atherosclerosis, and microangiopathy related cerebral damage. Human AGT gene has a C/A polymorphism at nucleoside 11525 (rs7079) that is located in the 3'-untranslated region (3'-UTR) and is modestly associated with increased blood pressure. We show here that miR-31 and miR-584 bind strongly to the hAGT 3'-UTR containing 11525C allele compared with 11525A allele. We also show that transfection of miR-31 and miR-584 downregulates the hAGT mRNA and protein levels in human liver cells. These studies may provide new therapeutic approach to reduce hypertension.