Valsartan Promoting Atherosclerotic Plaque Stabilization by Upregulating Renalase: A Potential-Related Gene of Atherosclerosis

Current Toolset in Predicting Acute Coronary Thrombotic Events: The “Vulnerable Plaque” in a “Vulnerable Patient” Concept

Despite major advances in pharmacotherapy and interventional procedures, coronary artery disease (CAD) remains a principal cause of morbidity and mortality worldwide. Invasive coronary imaging along with the computation of hemodynamic forces, primarily endothelial shear stress and plaque structural stress, have enabled a comprehensive identification of atherosclerotic plaque components, providing a unique insight into the understanding of plaque vulnerability and progression, which may help guide patient treatment. However, the invasive-only approach to CAD has failed to show high predictive value. Meanwhile, it is becoming increasingly evident that along with the “vulnerable plaque”, the presence of a “vulnerable patient” state is also necessary to precipitate an acute coronary thrombotic event. Non-invasive imaging techniques have also evolved, providing new opportunities for the identification of high-risk plaques, the study of atherosclerosis in asymptomatic individuals, and general population screening. Additionally, risk stratification scores, circulating biomarkers, immunology, and genetics also complete the armamentarium of a broader “vulnerable plaque and patient” concept approach. In the current review article, the invasive and non-invasive modalities used for the detection of high-risk plaques in patients with CAD are summarized and critically appraised. The challenges of the vulnerable plaque concept are also discussed, highlighting the need to shift towards a more interdisciplinary approach that can identify the “vulnerable plaque” in a “vulnerable patient”.

Renalase: a novel regulator of cardiometabolic and renal diseases

Renalase is a ~38 kDa flavin-adenine dinucleotide (FAD) domain-containing protein that can function as a cytokine and an anomerase. It is emerging as a novel regulator of cardiometabolic diseases. Expressed mainly in the kidneys, renalase has been reported to have a hypotensive effect and may control blood pressure through regulation of sympathetic tone. Furthermore, genetic variations in the renalase gene, such as a functional missense polymorphism (Glu37Asp), have implications in the cardiovascular and renal systems and can potentially increase the risk of cardiometabolic disorders. Research on the physiological functions and biochemical actions of renalase over the years has indicated a role for renalase as one of the key proteins involved in various disease states, such as diabetes, impaired lipid metabolism, and cancer. Recent studies have identified three transcription factors (viz., Sp1, STAT3, and ZBP89) as key positive regulators in modulating the expression of the human renalase gene. Moreover, renalase is under the post-transcriptional regulation of two microRNAs (viz., miR-29b, and miR-146a), which downregulate renalase expression. While renalase supplementation may be useful for treating hypertension, inhibition of renalase signaling may be beneficial to patients with cancerous tumors. However, more incisive investigations are required to unravel the potential therapeutic applications of renalase. Based on the literature pertaining to the function and physiology of renalase, this review attempts to consolidate and comprehend the role of renalase in regulating cardiometabolic and renal disorders.

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.

Association of renalase with clinical outcomes in hospitalized patients with COVID-19

Renalase is a secreted flavoprotein with anti-inflammatory and pro-cell survival properties. COVID-19 is associated with disordered inflammation and apoptosis. We hypothesized that blood renalase levels would correspond to severe COVID-19 and survival. In this retrospective cohort study, clinicopathologic data and blood samples were collected from hospitalized COVID-19 subjects (March—June 2020) at a single institution tertiary hospital. Plasma renalase and cytokine levels were measured and clinical data abstracted from health records. Of 3,450 COVID-19 patients, 458 patients were enrolled. Patients were excluded if <18 years, or opted out of research. The primary composite outcome was intubation or death within 180 days. Secondary outcomes included mortality alone, intensive care unit admission, use of vasopressors, and CPR. Enrolled patients had mean age 64 years (SD±17), were 53% males, and 48% non-whites. Mean renalase levels was 14,108·4 ng/ml (SD±8,137 ng/ml). Compared to patients with high renalase, those with low renalase (< 8,922 ng/ml) were more likely to present with hypoxia, increased ICU admission (54% vs. 33%, p < 0.001), and cardiopulmonary resuscitation (10% vs. 4%, p = 0·023). In Cox proportional hazard model, every 1000 ng/ml increase in renalase decreased the risk of death or intubation by 5% (HR 0·95; 95% CI 0·91–0·98) and increased survival alone by 6% (HR 0·95; CI 0·90–0·98), after adjusting for socio-demographics, initial disease severity, comorbidities and inflammation. Patients with high renalase-low IL-6 levels had the best survival compared to other groups (p = 0·04). Renalase was independently associated with reduced intubation and mortality in hospitalized COVID-19 patients. Future studies should assess the pathophysiological relevance of renalase in COVID-19 disease.

Hepatic Lipid Metabolism Disorder and Atherosclerosis

Lipid metabolism disorder plays a fundamental role in the pathogenesis of atherosclerosis. As the largest metabolic organ of the human body, liver has a key role in lipid metabolism by influencing fat production, fat decomposition, and the intake and secretion of serum lipoproteins. Numerous clinical and experimental studies have indicated that the dysfunction of hepatic lipid metabolism is closely tied to the onset of atherosclerosis. However, the identity and functional role of hepatic lipid metabolism responsible for these associations remain unknown. This review presented that cholesterol synthesis, cholesterol transport, and the metabolism of triglyceride, lipoproteins, and fatty acids are all associated with hepatic lipid metabolism and atherosclerosis. Moreover, we also discussed the roles of gut microbiota, inflammatory response, and oxidative stress in the pathological association between hepatic lipid metabolism and atherosclerosis. These significant evidences support strongly that hepatic lipid metabolism disorders may increase the risk of atherosclerosis.

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.

Relationship between Renalase Expression and Kidney Disease: an Observational Study in 72 Patients Undergoing Renal Biopsy

The relationship between the levels of renalase and changes in proteinuria, hypertension, renal function, renal tubular epithelial cell apoptosis and B-cell lymphoma-2 (Bcl-2) expression was investigated in patients (chronic nephritis, primary nephrotic syndrome or other kidney disease) that underwent renal biopsy. The study group comprised 72 patients undergoing renal biopsy. Patient profiles and renal function were collected. Concentrations of renalase and Bcl-2 were measured by immunohistochemistry. Tubular injury was detected by periodic acid Schiff staining (PAS) and renal tubular epithelial cell apoptosis was assessed by TUNEL assay. The expression of renalase was significantly lower in renal biopsy specimens than in normal kidney tissues. There was a positive linear relationship between renalase and some serum and cardiac indices; a negative correlation was found between age, eGFR, Ccr and 24-h urinary protein. Renal tubule injury index and tubular epithelial cell apoptosis index showed a negative linear correlation with renalase. The results showed that renalase probably increased the expression of Bcl-2. By two independent samples t-test, renalase levels were significantly increased in the non-hypertension group than in the hypertension group. One-way ANOVA showed that renalase expression was higher in samples with Lee's grade III than in those with Lee's grade V. The expression of renalase was significantly decreased in patients who underwent renal biopsy, and was also associated with blood and renal function. The research proved that renalase may reduce renal tubular injury and apoptosis of renal tubular epithelial cells through the mitochondrial apoptosis pathway, finally achieving the purpose of delaying the progress of renal failure.

Effect of Tetramethylpyrazine on Atherosclerosis and SCAP/SREBP-1c Signaling Pathway in ApoE-/- Mice Fed with a High-Fat Diet

Lipid metabolism dysregulation plays a crucial role in the occurrence of atherosclerosis (As). SCAP/SREBP signaling is the main pathway for regulating lipid metabolism. Tetramethylpyrazine (TMP), a Traditional Chinese Medicine (TCM) for treating angina pectoris, has antiatherosclerotic effects and ameliorates blood lipids disturbance. However, its precise mechanism remains unclear. This study investigated the mechanism of TMP in ameliorating As in mice model. After six weeks of high-fat diet, 30 ApoE^−/− mice were randomized (n = 10) and treated with Lipitor, TMP, or distilled water for six weeks. The serum blood lipids and insulin levels were measured. The expressions of PAQR3, Insig-1, SCAP, SREBP-1c, IRS-1, PI3K, Akt, and mTORC-1 in the adipose tissues were determined. The results showed that TMP could significantly decrease blood lipids levels, insulin, and corrected plaque area of the ApoE^−/− mice as compared to the untreated mice (P < 0.05, P < 0.01). Moreover, TMP could significantly downregulate the expressions of SCAP, SREBP-1c, PAQR3, IRS-1, PI3K, Akt, and mTORC1 (P < 0.01). Thus, TMP may ameliorate lipid metabolism disorder and As by downregulating PAQR3 and inhibiting SCAP/SREBP-1c signaling pathway. In addition, PI3K/Akt/mTORC1 signaling pathway may be involved in this process.

Atorvastatin attenuates p‑cresyl sulfate‑induced atherogenesis and plaque instability in ApoE knockout mice

p-cresyl sulfate (PCS) is a protein-bound uremic toxin retained in the blood of patients with chronic kidney disease (CKD) As atherosclerosis is a primary cardiovascular complication for patients with CKD, the aim of the present study was to investigate the mechanisms underlying the aggravation of atherosclerosis by PCS. In addition, the effect of atorvastatin was assessed in reversing the effects of PCS. PCS was revealed to promote the initiation and progression of atherosclerosis. Following treatment with atorvastatin, apolipoprotein E knockout mice demonstrated a reduction in PCS-induced atherogenesis and plaque vulnerability. In addition, atorvastatin decreased the protein expression levels of vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1, and the interaction between leukocytes and endothelia. The plasma lipid profiles of mice were not significantly affected by gavage of low-dose atorvastatin. The results of the present study indicate that PCS promotes plaque growth and instability by enhancing leukocyte-endothelium interaction, and that these effects may be attenuated by atorvastatin treatment.

Rs10887800 renalase gene polymorphism is associated with an increased risk of coronary artery disease in hemodialyzed patients

Purpose

Coronary artery disease (CAD) is common in patients with end-stage renal disease (ESRD). Recent studies have suggested that renalase, a novel FAD-dependent amine oxidase, may play an important role in the pathogenesis of cardiovascular complications in ESRD patients. The aim of the study was to investigate the association between renalase gene polymorphisms and a risk of CAD in patients on hemodialysis.

Methods

In a case–control study, a total of 309 hemodialyzed patients (107 with and 202 without CAD) were genotyped for two SNPs in the renalase gene (rs10887800 and rs2576178) using the PCR–RFLP method.

Results

By multivariate logistic regression analysis, we found that rs10887800GG genotype was associated with an increased risk of CAD under the codominant model [GG vs AA; adjusted OR 2.66 (95 % CI, 1.19–5.94), p = .017] and under the recessive model [GG vs AG + AA; adjusted OR 2.10 (95 % CI, 1.10–4.02), p = .025]. The rs2576178 polymorphism did not influence the risk of CAD.

Conclusion

The study suggested for the first time that the rs10887800 renalase gene polymorphism may be involved in the pathogenesis of CAD in hemodialyzed patients and thus could be considered a new genetic risk factor for CAD in this population.

Serum Renalase Levels Correlate with Disease Activity in Lupus Nephritis

Introduction

Lupus nephritis (LN) is among the most serious complications of systemic lupus erythematosus (SLE), which causes significant morbidity and mortality. Renalase is a novel, kidney-secreted cytokine-like protein that promotes cell survival. Here, we aimed to investigate the relationship of serum renalase levels with LN and its role in the disease progression of LN.

Methods

For this cross-sectional study, 67 LN patients and 35 healthy controls were enrolled. Seventeen active LN patients who received standard therapies were followed up for six months. Disease activity was determined by the SLE Disease Activity–2000 (SLEDAI-2K) scoring system and serum renalase amounts were determined by ELISA. Predictive value of renalase for disease activity was assessed. Furthermore, the expression of renalase in the kidneys of patients and macrophage infiltration was assessed by immunohistochemistry.

Results

Serum renalase amounts were significantly higher in LN patients than in healthy controls. Moreover, patients with proliferative LN had more elevated serum renalase levels than Class V LN patients. In proliferative LN patients, serum renalase levels were significantly higher in patients with active LN than those with inactive LN. Serum renalase levels were positively correlated with SLEDAI-2K, 24-h urine protein excretion, ds-DNA and ESR but inversely correlated with serum albumin and C3. Renalase amounts decreased significantly after six-months of standard therapy. The performance of renalase as a marker for diagnosis of active LN was 0.906 with a cutoff value of 66.67 μg/ml. We also observed that the amount of renalase was significantly higher in glomerular of proliferative LN along with the co-expression of macrophages.

Conclusion

Serum renalase levels were correlated with disease activity in LN. Serum renalase might serve as a potential indicator for disease activity in LN. The marked increase of glomerular renalase and its association with macrophages suggest that it might play an important role in disease progression of LN.