A novel marker in pregnant with preeclampsia: renalase

The effect of RNLS gene polymorphisms on preeclampsia susceptibility: a meta-analysis study

Aim: The authors designed a meta-analysis to find a comprehensive result of the impact of RNLS polymorphisms on preeclampsia (PE) susceptibility. Methods: The online databases PubMed, Scopus, and Google Scholar were employed for the purpose of literature search. Data analysis was conducted using STATA (ver. 12.0) and MetaGenyo web tool. Results: The findings showed that the RNLS rs10887800 polymorphism could increase risk of PE in allelic, codominant heterozygous and dominant genetic models. In addition, the analysis indicated that the RNLS rs2576178 polymorphism was associated with higher risk of PE in allelic, codominant homozygous, dominant, and recessive models. Conclusion: The findings of meta-analysis showed that the RNLS rs10887800 and rs2576178 polymorphisms could increase risk of PE in several genetic models.

Renalase Levels are Decreased in Maternal Blood and Placental Tissues in Pregnancies Associated with Preterm Preeclampsia

Preeclampsia (PEC) is a complication of pregnancy associated with hypertension and the risk of eclampsia. The pathophysiology of PEC is unknown and identifying factors associated with PEC during pregnancy is crucial for placental, fetal, and maternal health. Renalase (RNLS) is an anti-inflammatory secretory flavoprotein associated with hypertension. Recent data demonstrated a correlation between maternal serum RNLS and PEC, and work from our group identified RNLS expression in the placenta. However, it remains unknown whether RNLS levels in placenta are altered by preeclampsia. Additionally, it is unclear if there is a differential effect of preterm and term PEC on RNLS. We demonstrate that serum RNLS was reduced in preterm cases of PEC. Similarly, placental RNLS was diminished in the chorion of preterm cases of PEC. However, a reduction of RNLS in the decidua was observed with all cases of PEC, while the levels of RNLS within the placental villi were similar in all cases. Overall, we demonstrate that RNLS correlates with PEC both systemically in maternal serum and locally within the placenta, with variable effects on the different layers of the placenta and more pronounced in preterm cases.

Advances and Challenges in Biomarkers Use for Coronary Microvascular Dysfunction: From Bench to Clinical Practice

Coronary microvascular dysfunction (CMD) is related to a broad variety of clinical scenarios in which cardiac microvasculature is morphologically and functionally affected, and it is associated with impaired responses to vasoactive stimuli. Although the prevalence of CMD involves about half of all patients with chronic coronary syndromes and more than 20% of those with acute coronary syndrome, the diagnosis of CMD is often missed, leading to the underestimation of its clinical importance. The established and validated techniques for the measurement of coronary microvascular function are invasive and expensive. An ideal method to assess endothelial dysfunction should be accurate, non-invasive, cost-effective and accessible. There are varieties of biomarkers available, potentially involved in microvascular disease, but none have been extensively validated in this heterogeneous clinical population. The investigation of potential biomarkers linked to microvascular dysfunction might improve the assessment of the diagnosis, risk stratification, disease progression and therapy response. This review article offers an update about traditional and novel potential biomarkers linked to CMD.

Renalase and its receptor, PMCA4b, are expressed in the placenta throughout the human gestation

Placental function requires organized growth, transmission of nutrients, and an anti-inflammatory milieu between the maternal and fetal interface, but placental factors important for its function remain unclear. Renalase is a pro-survival, anti-inflammatory flavoprotein found to be critical in other tissues. We examined the potential role of renalase in placental development. PCR, bulk RNA sequencing, immunohistochemistry, and immunofluorescence for renalase and its binding partners, PMCA4b and PZP, were performed on human placental tissue from second-trimester and full-term placentas separated into decidua, placental villi and chorionic plates. Quantification of immunohistochemistry was used to localize renalase across time course from 17 weeks to term. Endogenous production of renalase was examined in placental tissue and organoids. Renalase and its receptor PMCA4b transcripts and proteins were present in all layers of the placenta. Estimated RNLS protein levels did not change with gestation in the decidual samples. However, placental villi contained more renalase immunoreactive cells in fetal than full-term placental samples. RNLS co-labeled with markers for Hofbauer cells and trophoblasts within the placental villi. Endogenous production of RNLS, PMCA4b, and PZP by trophoblasts was validated in placental organoids. Renalase is endogenously expressed throughout placental tissue and specifically within Hofbauer cells and trophoblasts, suggesting a potential role for renalase in placental development and function. Future studies should assess renalase's role in normal and diseased human placenta.

Associations of Renalase With Blood Pressure and Hypertension in Chinese Adults

Objective

Renalase, a novel secretory flavoprotein with amine oxidase activity, is secreted into the blood by the kidneys and is hypothesized to participate in blood pressure (BP) regulation. We investigated the associations of renalase with BP and the risk of hypertension by examining renalase single nucleopeptide polymorphism (SNPs), serum renalase levels, and renal expression of renalase in humans.

Methods

① Subjects (n = 514) from the original Baoji Salt-Sensitive Study cohort were genotyped to investigate the association of renalase SNPs with longitudinal BP changes and the risk of hypertension during 14 years of follow-up. ② Two thousand three hundred and ninety two participants from the Hanzhong Adolescent Hypertension Study cohort were used to examine the association of serum renalase levels with hypertension. Renalase expression in renal biopsy specimens from 193 patients were measured by immunohistochemistry. ③ Renalase expression was compared in hypertensive vs. normotensive patients.

Results

① SNP rs7922058 was associated with 14-year change in systolic BP, and rs10887800, rs796945, rs1935582, rs2296545, and rs2576178 were significantly associated with 14-year change in diastolic BP while rs1935582 and rs2576178 were associated with mean arterial pressure change over 14 years. In addition, SNPs rs796945, rs1935582, and rs2576178 were significantly associated with hypertension incidence. Gene-based analysis found that renalase gene was significantly associated with hypertension incidence over 14-year follow-up after adjustment for multiple measurements. ② Hypertensive subjects had higher serum renalase levels than normotensive subjects (27.2 ± 0.4 vs. 25.1 ± 0.2 μg/mL). Serum renalase levels and BPs showed a linear correlation. In addition, serum renalase was significantly associated with the risk of hypertension [OR = 1.018 (1.006–1.030)]. ③ The expression of renalase in human renal biopsy specimens significantly decreased in hypertensive patients compared to non-hypertensive patients (0.030 ± 0.001 vs. 0.038 ± 0.004).

Conclusions

These findings indicate that renalase may play an important role in BP progression and development of hypertension.

Renalase gene polymorphisms and plasma levels are associated with preeclampsia: a hospital-based study in the Chinese cohort

Preeclampsia (PE) is one of the major contributors to maternal and fetal mortality worldwide. Many host-related biomolecules regulate the pathophysiology of PE. The current study aims to examine the role of the renalase in PE manifestations. A total of 384 Chinese women consisting of subjects with normotensive pregnancy (n = 105), women with PE (n = 121), and healthy women (n = 158) were included in the study. Serum renalase level was measured in all subjects by ELISA. Renalase gene polymorphisms (rs10887800, rs2576178, and rs2296545) were genotyped by PCR-RFLP. The pregnant women had elevated renalase levels compared to healthy controls and subjects with PE. Renalase level was negatively correlated with systolic and diastolic blood pressure. Interestingly, renalase was positively correlated with the glomerular filtration rate. Prevalence of homozygous mutant (GG) and minor allele (G) for rs10887800 and rs2576178 renalase gene polymorphisms were significantly higher in PE patients compared to normotensive pregnant women and healthy controls. Furthermore, an association of G-G-C haplotype with susceptibility to PE was also noticed. A low level of renalase may be associated with an increased risk of PE during pregnancy. Renalase gene polymorphisms (rs10887800 and rs2576178) are correlated with serum renalase and are associated with predisposition to PE development in the Chinese cohort.

Renalase-A new understanding of its enzymatic and non-enzymatic activity and its implications for future research

Renalase was first described in 2005 and since then it became an object of scientific interest because of its proposed ability to catalyse circulating neurotransmitters and its promising antihypertensive effects. However, further research on the enzymatic activity of renalase did not confirm these initial findings and yielded that renalase serves to oxidize isomeric forms of β-NAD(P)H and recycle them by forming β-NAD(P)+. Moreover, in contrast to initial assumptions, it is indicated that renalase's enzymatic activity is confined to the cell and that extracellular renalase loses its enzymatic properties. These new reports led scientists to question as to whether renalase, as an enzyme, still has the potential to influence various systemic physiological responses (e.g. blood pressure). It was also put into question whether many physiological discoveries published based on the notion that renalase is secreted into the blood and acts by oxidation of catecholamines can still be considered valid. In this article, we attempt to review the literature to confront these doubts and find further possible directions of research on the importance of renalase. Our aim was to evaluate recent reports of non-enzymatic activity for renalase.

Association of renalase gene polymorphisms with the risk of hypertensive disorders of pregnancy in northeastern Han Chinese population

Renalase is a novel enzyme that can regulate blood pressure by degrading circulating catecholamines. We aimed to evaluate the possible effect of rs2296545, rs2576178 and rs10887800 polymorphisms of the renalase gene (RNLS) on the development of hypertensive disorders of pregnancy (HDP). This case-control study consisted of 185 patients with HDP and 380 normotensive pregnant women from the northeastern Chinese Han population. Association analyses were performed using PLINK, to compare allele and genotype frequencies in cases and controls. Adjustment for logistic regression analysis was performed by permutation testing. In the HDP patients compared with controls, we found that there was statistically significant difference in genotype distribution of rs2296545 (p = .037). Rs2296545 and rs2576178 polymorphisms have 1.91-fold (p = .004) and 1.73-fold (p = .015) increased risk of HDP in the dominant model, respectively. When compared preeclampsia (PE) to control, the RNLS rs2296545 polymorphism was significantly associated with PE risk in the dominant model (p = .021). We next analyzed the haplotypes of these SNPs and there was no difference between controls and HDP or PE. These findings suggest that rs2296545 was significantly associated with HDP and PE risk and the rs2576178 polymorphism may increase the susceptibility to HDP.

Roles and mechanisms of renalase in cardiovascular disease: A promising therapeutic target

Cardiovascular disease (CVD) is prevalent worldwide and remains a leading cause of death. Although substantial progress has been made in the diagnosis and treatment of CVD, the prognosis remains unsatisfactory. Renalase is a newly discovered cytokine that is synthesized by the kidney and then secreted into blood. Numerous studies have suggested the efficacy of renalase in treating CVD by metabolizing catecholamines in the circulatory system. As a new biomarker of heart disease, renalase is normally recognized as a signalling molecule that activates cytoprotective intracellular signals to lower blood pressure, protect ischaemic heart muscle and promote atherosclerotic plaque stability in CVD, which subsequently improves cardiac function. Due to its important regulatory role in the circulatory system, renalase has gradually become a potential target in the treatment of CVD. This review summarizes the structure, mechanism and function of renalase in CVD, thereby providing preclinical evidence for alternative approaches and new prospects in the development of renalase-related drugs against CVD.

Maternal kidney function during pregnancy: systematic review and meta-analysis

OBJECTIVES

To review systematically current literature on kidney function changes during pregnancy, in order to estimate the extent of adaptation over the course of both healthy physiological and complicated singleton pregnancies, and to determine healthy pregnancy reference values.

METHODS

PubMed (NCBI) and EMBASE (Ovid) electronic databases were searched, from inception to July 2017, for studies on kidney function during uncomplicated and complicated pregnancies. Included studies were required to report a non-pregnant reference value of kidney function (either in a non-pregnant control group or as a prepregnancy or postpartum measurement) and a pregnancy measurement at a predetermined and reported gestational age. Kidney function measures assessed were glomerular filtration rate (GFR) measured by inulin clearance, GFR measured by creatinine clearance and serum creatinine level. Pooled mean differences between pregnancy measurements and reference values were calculated for predefined intervals of gestational age in uncomplicated and complicated pregnancies using a random-effects model described by DerSimonian and Laird.

RESULTS

Twenty-nine studies met the inclusion criteria and were included in the analysis. As early as the first trimester, GFR was increased by up to 40-50% in physiological pregnancy when compared with non-pregnant values. Inulin clearance in uncomplicated pregnancy was highest at 36-41 weeks, with a 55.6% (53.7; 95% CI, 44.7-62.6 mL/min) increase when compared with non-pregnant values, and creatinine clearance was highest at 15-21 weeks' gestation, with a 37.6% (36.6; 95% CI, 26.2-46.9 mL/min) increase. Decrease in serum creatinine level in uncomplicated pregnancy was most prominent at 15-21 weeks, with a 23.2% (-0.19; 95% CI, -0.23 to -0.15 mg/dL) decrease when compared with non-pregnant values. Eight studies reported on pregnancies complicated by a hypertensive disorder. Meta-regression analysis showed a significant difference in all kidney function parameters when comparing uncomplicated and hypertensive complicated pregnancies.

CONCLUSIONS

In healthy pregnancy, GFR is increased as early as the first trimester, as compared with non-pregnant values, and the kidneys continue to function at a higher rate throughout gestation. In contrast, kidney function is decreased in hypertensive pregnancy. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

A Novel Biomarker Renalase and Its Relationship with its Substrates in Schizophrenia

Background

Schizophrenia, particularly the form related to excessive dopamine (DA), is a chronic psychotic disorder affecting millions of people worldwide. Renalase metabolizes its catecholamine (CA) substrates, including DA, suggesting that there might be an association between renalase levels and schizophrenia occurrence. Therefore, the current study aimed to evaluate the renalase and CA levels in the serum of patients with schizophrenia.

Methods

The study was conducted with thirty-three schizophrenia patients and an age- and gender-matched group of thirty-one controls. Renalase and CA levels were measured by using an enzyme-linked immunosorbent assay (ELISA).

Results

Renalase levels were significantly lower in the schizophrenia patients than in the control group (p<0.05), whereas DA levels were significantly higher (p<0.05). The epinephrine (Epi) levels of both groups were similar (p=0.186), while the norepinephrine levels in patients with schizophrenia were significantly lower than those in the control group (p<0.05). The areas under the curves for the renalase-dopamine, renalase-norepinephrine and renalase-epinephrine ratios were 0.805, 95% confidence interval (CI): 0.699–0.912 (p<0.001); 0.726, 95% CI: 0.594–0.859 (p=0.032); and 0.656, 95% CI: 0.520–0.791 (p=0.02).

Conclusions

The high DA levels in patients with schizophrenia might be due to low renalase levels. Renalase enzyme levels may play a substantial role in the pathophysiology of schizophrenia. Thus, this enzyme might be a new future target for the treatment and diagnosis of schizophrenia after intrabrain renalase and DA dynamics have been further evaluated.

Direct laboratory evidence that pregnancy-induced hypertension might be associated with increased catecholamines and decreased renalase concentrations in the umbilical cord and mother’s blood

Background

Renalase (RNL) is a controversial enzyme as to whether it oxidizes catecholamines (CAs) (as is generally accepted) in the blood or not. CAs (dopamine [DPMN], epinephrine [EPI] and norepinephrine [NEPI]) are associated with hypertension, including pregnancy-induced hypertension, which occurs in 8–10% of all pregnancies. Therefore, the aim of the study was to compare CAs and renalase concentration in (i) normotensive controls (C), (ii) patients with preeclampsia (PE) and (iii) patients with severe preeclampsia (SPE), which is one of the well-known symptoms of hypertension.

Methods

This case-control study involved 90 women divided into three groups – 30 C, 30 PE and 30 SPE – whose age and body mass indexes (BMIs) were similar. A total of 270 blood samples (90 maternal samples, 90 umbilical cord artery samples and 90 umbilical cord vein samples) were obtained. CAs and RNL concentrations of the biological samples were measured by enzyme-linked immunosorbent assay (ELISA).

Results

Comparing the amounts of CAs, RNL and systolic blood pressure (SBP)/diastolic blood pressure (DBP) between healthy control pregnant women and pregnant women with PE and SPE (SBP/DBP was 120/80 mm Hg for C, above 140/90 mm Hg for PE and above 160/110 mm Hg for SPE), the levels of CAs were significantly increased whereas RNL was reduced. The correlation between SBP/DBP and the amount of RNL in pregnant women with PE and SPE was negative.

Conclusions

These novel results are evidence that hypertension seen in PE and SPE is directly related to increased levels of CAs and reduced RNL concentrations. The use of RNL preparations may be preferred in future to prevent maternal and perinatal morbidity and mortality due to pregnancy-induced hypertension.

Serum anti mullerian hormone and renalase levels in predicting the risk of preeclampsia

OBJECTIVE

The aim of the study was to explore the association of serum AMH and Renalase with the risk of preeclampsia thereby assessing them as screening tools, reducing the risk of gravid consequences of preeclampsia.

MATERIALS AND METHODS

This cross-sectional study recruited n = 95 pregnant women between 14 and 32 gestational weeks. They were categorized as a) women with gestational hypertension (n = 45); b) women with pre-eclampsia (n = 20) and c) normotensive pregnant women (n = 30) according to the ACOG criteria. Anthropometrics data and blood and urine samples were collected. AMH and Renalase levels were measured by ELISA assay.

RESULTS

The mean age of study cohort was 27.3 ± 6.2 year and weight was 65.1 ± 14.1 kg. Blood pressures were significantly higher in pre-eclamptic patients versus both the gestational hypertensive females and controls (p < 0.05). AMH was found to be significantly higher in controls but no difference was observed between gestational hypertensive and pre-eclamptic patients. No difference was seen for serum Renalase among the three groups (p > 0.05). AMH showed a negative weak correlation with diastolic blood pressure (r = -0.272; p = 0.008) that remained significant even after adjustment (r = -0.236; p = 0.023) whereas Renalase did not show any difference (r = -0.051; p > 0.05). Females with low levels of AMH were 1.07 times at risk of developing hypertension even after adjustment for age and BMI (p < 0.05).

CONCLUSION

Low AMH levels may lead to hypertension in pregnancy suggesting a role in detecting vascular diseases as well as its effect on ovarian aging. However, further research is required to establish a causal relationship.