Association of Imaging Classification of Intracranial Cerebral Atherosclerotic Vascular Stenosis in Ischemic Stroke and Renalase Gene Polymorphisms

The Effect of Renalase rs2576178 and rs10887800 Polymorphisms on Ischemic Stroke Susceptibility in Young Patients (<50 Years): A Case-Control Study and In Silico Analysis

Background

Ischemic stroke (IS) is the most common form of cerebrovascular accident which its precise etiology remains mysterious. Renalase is a catecholamine-degrading enzyme playing a major role in blood pressure control. Recent studies show the effect of renalase activity on various diseases like IS. In the current study, we examined the possible effects of renalase gene (RNLS) rs2576178 and rs10887800 variants at the 5′-flanking and intron 6 regions on IS, respectively.

Methods

One hundred and fifty-four IS patients younger than 50 years and 165 age- and sex-matched controls were recruited in the study. For genotyping of rs2576178 and rs10887800 variants, the PCR-RFLP method was used.

Results

The RNLS rs10887800 AG genotype was more repeated in IS patients, but the difference was marginally nonsignificant (P = 0.054). This variant was associated with IS in the overdominant model, and the AG genotype is associated with a1.6-fold increased risk of IS compared to AA+ GG genotypes (OR = 1.6, 95% CI: 1-2.5, P = 0.033). No relationship was observed between RNLS rs2576178 polymorphism and IS in all genetic models. The findings of the haplotype and combination effects of rs10887800 and rs2576178 variants on IS showed no significant association. The in silico analysis showed no effect of rs2576178 and rs10887800 polymorphisms in the RNA structure, but the alteration of RNA sequence in rs2576178 results in the lack of a MBNL1 protein binding site.

Conclusions

RNLS rs10887800 but not rs2576178 polymorphism was associated with IS susceptibility in the overdominant model (AG vs AA+ GG genotypes).

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.

Atorvastatin and losartan may upregulate renalase activity in hypertension but not coronary artery diseases: The role of gene polymorphism

The aim is to explore the treatment effect of coronary artery disease (CAD) and hypertension on plasma levels of renalase activity and also the possible association of renalase rs10887800 gene polymorphism with CAD and hypertension. A total of 286 patients who received coronary angiography were included in the study. Subjects were divided into four groups including (1) hypertensive with no CAD (H-Tens, n = 60); (2) CAD with hypertension (CAD + H-Tens, n = 71); (3) CAD with no hypertension (CAD, n = 61); and (4) nonhypertensive with no CAD as a control group (Con, n = 69). The plasma renalase activity was measured using the Amplex Red Monoamine Oxidase Assay Kit. Renalase rs10887800 single-nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Atorvastatin (P = 0.005), losartan (P < 0.001), and captopril (P = 0.001) were administered significantly more in case groups compared with the Con group. Significant higher and lower levels of renalase activity were observed in H-Tens and CAD patients compared with control subjects (P < 0.001 for both comparisons). Furthermore, no significant differences were obtained in the risk or protective effects of renalase rs10887800 SNP against hypertension and/or CAD in both recessive and dominant genetic models (P > 0.05). According to the findings of the present study, atorvastatin and losartan therapy assumes considerable significance in alleviating hypertension, but not CAD, by increasing the renalase activity. Furthermore, it was found that renalase rs10887800 is less likely a predisposing factor for susceptibility to hypertension and/or CAD in an Iranian southeast population.

Genetic Variation of the Kalirin Gene is Associated with ICAS in the Chinese Population

Intracranial atherosclerotic stenosis (ICAS) is one of the most common causes of ischemic stroke (IS), especially in recurrent patients. Several studies have demonstrated an intimate association between the genetic mutation of the KALRN gene and IS. The main aim of this study was to clarify the relationship between three single nucleotide polymorphisms (SNPs) of KALRN and ICAS in a northern Chinese population and further explore the underlining mechanism. The relationship between each SNP and ICAS and the related components were examined in five models (co-dominant, dominant, recessive, heterozygous, and additive). Multivariate logistic regression models were applied and adjusted for 10,000 permutation tests. Haplotype regression analysis was performed to determine the associations between haplotypes and the severity of ICAS. qRT-PCR was used to confirm the mRNA level of Kalirin. SNP rs6438833 of the Kalirin gene in the additive model was associated with ICAS (OR = 1.642, 95%CI: 1.129-2.388, P_Dom = 0.048). After performing 10,000 permutations, the result showed a trend toward statistical significance (Pper = 0.048). Haplotypes of the KALRN gene were not significantly associated with ICAS (global significance, p = 0.090). qRT-PCR showed that the expression of KALRN 9 in IS patients was almost threefold the control group (p < 0.0005). SNPs of the KALRN gene are associated with ICAS in the northern Chinese population.

Renalase: its role as a cytokine, and an update on its association with type 1 diabetes and ischemic stroke

PURPOSE OF REVIEW

Remarkable progress has been achieved over the past 2 years in understanding the cellular actions of renalase, its pathophysiology and potential therapeutic utility.

RECENT FINDINGS

There has been a paradigm shift in our thinking about the mechanisms underlying the cellular actions of renalase. We now understand that, independent of its enzymatic properties, renalase functions as a signaling molecule, a cytokine that interacts with a yet-to-be identified plasma membrane receptor(s) to activate protein kinase B and the mitogen-activated protein kinase pathway. These signaling properties are critical to its cytoprotective effects. New information regarding renalase's enzymatic function as an α-nicotinamide adenine dinucleotide oxidase/anomerase will be reviewed. Lastly, we will discuss the association of certain single nucleotide polymorphisms in the renalase gene with type 1 diabetes and with ischemic stroke, and the clinical implications of these findings.

SUMMARY

The consistent association of renalase single nucleotide polymorphisms and the development of type 1 diabetes is a great interest particularly because we now understand that renalase functions as a cytokine. Future work on renalase should focus on exploring the identity of its receptor(s), and its potential role as an immune modulator.

Renalase, kidney and cardiovascular disease: are they related or just coincidentally associated?

Cardiovascular diseases, including hypertension are the leading cause of death in the developed countries. Diabetes and chronic kidney disease became also more prevalent reaching almost the level of epidemy. Researchers are looking eagerly for the new risk and/or pathogenetic factors, as well as therapeutic option in these disease. It has been suggested that human kidney releases a protein named renalase into the bloodstream. It is supposed to be an enzyme which breaks down catecholamines in the blood circulation and regulate blood pressure. However, there were several doubts whether renalase exerts monoaminooxidase activity, or if it is monoaminooxidase at all. Recently, a hypothesis that it is also a cytokine was postulated. Studies on renalase polymorphisms in hypertension, cardiovascular disease or diabetes are inconsistent. Similarly, there are several discrepancies in the animal on the possible role of renalase in hypertension and cardiovascular diseases. Some studies report a protective role of renalase in acute kidney injury, whereas others showed that renalase levels were mainly dependent on kidney function, indicating rather a role of kidney in excretion of this substance. Moreover, validated assays are needed to evaluate renalase levels and activity. On one hand a deeper and more accurate link between renalase and cardiovascular diseases require further profound research, on the other hand whether or not renalase protein could be a new therapeutic target in these pathologies should also be considered. Whether renalase, discovered in 2005, might be a Holy Grail of hypertension, linking kidney and cardiovascular diseases, remains to be proven.