Modulation of vitamin D signaling is a potential therapeutic target to lower cardiovascular risk in chronic kidney disease

Vitamin D3 as Potential Treatment Adjuncts for COVID-19

Severe acute respiratory syndrome coronavirus type (SARS-CoV2, also known as COVID-19), which is the latest pandemic infectious disease, constitutes a serious risk to human health. SARS-CoV2 infection causes immune activation and systemic hyperinflammation which can lead to respiratory distress syndrome (ARDS). ARDS victims are characterized by a significant increase in IL-6 and IL-1. Macrophage activation, associated with the “cytokine storm”, promotes the dysregulation of the innate immunity. So far, without vaccines or specific therapy, all efforts to design drugs or clinical trials are worthwhile. Vitamin D and its receptor vitamin D receptor (VDR) exert a critical role in infections due to their remarkable impact on both innate and adaptive immune responses and on the suppression of the inflammatory process. The protective properties of vitamin D supplementation have been supported by numerous observational studies and by meta-analysis of clinical trials for prevention of viral acute respiratory infection. In this review, we compare the mechanisms of the host immune response to SARS-CoV2 infection and the immunomodulatory actions that vitamin D exerts in order to consider the preventive effect of vitamin D supplementation on SARS-CoV2 viral infection.

1,25-Dihydroxyvitamin D3 Does Not Affect MicroRNA Expression When Suppressing Human Th17 Differentiation

Background

Vitamin D is an import regulator of T helper 17 (Th17) differentiation, but our understanding of the underlying mechanisms remains limited. In the present study, we aimed to detect the expression levels of microRNAs (miRNAs) during human Th17 differentiation and evaluate the effects of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), the bioactive form of vitamin D, on Th17 differentiation and miRNA expression.

Material/Methods

We cultured human peripheral blood mononuclear cells (PBMC) in vitro and activated them with anti-CD3 and anti-CD28 antibodies in the presence of Th17-promoting cytokines interleukin (IL)-23, IL-1β, TGF-β1, and IL-6 for 72 hours. 1,25(OH)₂D₃ was added to the medium at a final concentration of 100 nM on day 0. The production of IL-17A in culture medium was detected by enzyme-linked immunosorbent assay (ELISA). The expression levels of miRNAs during Th17 differentiation were determined by quantitative polymerase chain reaction (qPCR).

Results

Six miRNAs were found to be dysregulated during human Th17 differentiation. Of these miRNAs, hsa-miR-155 was significantly up-regulated (median fold change: 3.61, P<0.05), whereas hsa-miR-20b, hsa-miR-21, hsa-miR-181a, hsa-miR-210, and hsa-miR-301a were significantly down-regulated (median fold change: 0.44, 0.37, 0.18, 0.15, and 0.26, respectively, P<0.05). 1,25(OH)₂D₃ treatment significantly decreased IL-17A production (median [interquartile range], 745.7 [473.5] pg/mL vs. 2535.4 [2153.3] pg/mL, P<0.05). However, expression of these miRNAs was not changed after 1,25(OH)₂D₃ treatment.

Conclusions

1,25(OH)₂D₃ suppressed human Th17 differentiation without affecting miRNA expression.

Subclinical cardiovascular disease markers and vitamin D deficiency in non-dialysis chronic kidney disease patients

INTRODUCTION

Since 25-hydroxyvitamin D (25(OH)D) deficiency has been linked to an increased risk for cardiovascular disease (CVD) in the hemodialysis population, we aimed to determine the relationship between serum 25(OH)D level and markers of subclinical CVD in non-dialysis chronic kidney disease (CKD) patients.

MATERIAL AND METHODS

This cross-sectional, single-center study prospectively enrolled 87 clinically stable CKD patients (median age: 61 (57-66) years, 51% male, median estimated glomerular filtration rate (eGFR): 32 (27-37) ml/min). Five markers of subclinical CVD were assessed: intima-media thickness, abdominal aortic calcifications (AAC) using the Kauppila score, cardio-ankle vascular index, ankle-brachial index (ABI) and interventricular septum thickness.

RESULTS

Vascular (37%), glomerular (23%) and interstitial (18%) nephropathies were the main causes of CKD. 25(OH)D had a median value of 14 (12.5-17.1) ng/ml, and its levels decreased with eGFR (rs = 0.19; p = 0.04). Patients with 25(OH)D deficiency (54%) were older, had a higher serum alkaline phosphatase level, lower ABI and higher AAC score. There were no differences between the two groups regarding other traditional or non-traditional risk factors for atherosclerosis. The association between subclinical CVD markers and 25(OH)D was further evaluated in multivariable binomial logistic regression models adjusted for CV risk factors. Lower 25(OH)D level was retained as an independent predictor only for pathological ABI.

CONCLUSIONS

This is the first study to evaluate the relationship between a large set of subclinical CVD markers and 25(OH)D deficiency in non-dialysis CKD patients. We found that hypovitaminosis D is associated with subclinical peripheral arterial disease, independently of other cardiovascular risk factors.

Effects of coenzyme Q10 supplementation on C-reactive protein and homocysteine as the inflammatory markers in hemodialysis patients; a randomized clinical trial

Background: The most leading cause of death in end-stage renal disease (ESRD) patients are cardiovascular disease and inflammatory markers are related to coronary events. CO-Q10 (coenzyme Q10) is a protective supplement from free radical oxidative damage. In addition, hyperhomocysteinemia is an independent coronary artery disease (CAD) risk factor.

Objectives: Due to increasing oxidative stress in dialysis patients, and the effect of CO-Q10 in decrease oxidative stress, in this work, we assessed the effect of CO-Q10 on C-reactive protein (CRP) level as an inflammatory marker and homocysteine in dialysis patients.

Patients and Methods: This was a single-blind, randomized cross over clinical trial. Patients with ESRD were randomly allotted to two groups. All patients received placebo and C0- Q10 100mg/d during the three months in each stage, with two week washout period. Plasma level of CRP and homocysteine from the start of the work and at the conclusion of each menses, are evaluated.

Results: Thirty-four patients randomized, but 26 patients complete study protocol. The treatment effect of CO-Q10 on CRP level is significant (P < 0.001) (95% CI = -20.1 to -10.5) and it was also significant for the increasing albumin level. (P = 0.044) (95% CI = 0. 0-0.6), But there was not any substantial effect on serum homocysteine level (P = 0.630).

Conclusions: CO-Q10 could significantly decrease CRP level as an inflammatory marker and can protect cardiovascular events.

Effect of methoxy polyethylene glycol-epoetin beta on oxidative stress in predialysis patients with chronic kidney disease

Background

There is data in the literature indicating increased oxidative stress in chronic kidney disease (CKD). Erythropoiesis-stimulating agents (ESAs), which are commonly used to treat anemia in patients with CKD, seem to have an antioxidant action, which could be a part of nephroprotection. The aim of the current study was to investigate the effect of a long half-life ESA, methoxy polyethylene glycol-epoetin beta (Mircera), on some markers of oxidative stress in predialysis patients with CKD.

Material/Methods

Peripheral blood was collected from 28 predialysis CKD patients 2 times, before Mircera treatment and after achieving target hemoglobin (Hb), and 15 healthy subjects (control group). Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activity in erythrocytes were measured according to commonly used methods as a function of the antioxidant defense system. To assess reactive oxygen species (ROS) production, malondialdehyde (MDA) concentration in erythrocytes and in plasma was measured according to a commonly used method.

Results

SOD, GSH-Px, and CAT activity were similar, but plasma and erythrocyte MDA concentrations were significantly higher in CKD patients before ESA treatment in comparison to the control group. SOD, GSH-Px, and CAT activity was significantly higher, but plasma and erythrocyte MDA concentrations were significantly lower, in CKD patients after ESA treatment in comparison to these patients before treatment. We did not find a significant correlation between Hb concentration and SOD, GSH-Px, and CAT activity and plasma, as well as erythrocyte MDA concentrations. Analysis of all investigated groups showed a significant negative correlation between Hb concentration and plasma MDA concentration.

Conclusions

Our results suggest that treatment of anemia with methoxy polyethylene glycol-epoetin beta may inhibit oxidative stress in predialysis patients with CKD by enhancing the antioxidant defense system and reducing ROS production.

Vitamin D deficiency is associated with atherosclerosis-promoting risk factor clustering but not vascular damage in children

Background

Vitamin D has been associated with multiple cardiometabolic risk factors in children but there is a paucity of studies examining its correlation to vascular function and structure. Our objective was to determine whether there is a correlation between vitamin D, cardiometabolic risk, vascular distensibility and carotid artery intima-media thickness (CIMT) in high-risk children.

Material/Methods

This was a cross-sectional, cohort study that compared vitamin D to cardiometabolic risk factors, carotid artery distensibility, and CIMT in 74 children with multiple, modifiable atherosclerosis-promoting risk factors. Vitamin D was used as a continuous variable and also categorized as deficient (<20 ng/mL) or sufficient (≥20 ng/mL). Seven modifiable atherosclerosis-promoting risk factors were analyzed – body mass index, systolic blood pressure, total cholesterol, triglyceride, high density lipoprotein cholesterol, fasting insulin, & tobacco smoke exposure history.

Results

For the entire cohort, vitamin D was 26.1±9.4 ng/mL (6–63 ng/mL); and the levels were deficient in 20%. The number of modifiable atherosclerosis promoting risk factors per child was 3.3±1.6. Distensibility index was 2.62±0.87% per 10 mmHg, CIMT 0.54±0.06 mm. There was an inverse correlation between vitamin D and risk factor score (r=−0.27, p=0.02); this remained significant after adjusting for age, sex, and race. There was no association between vitamin D levels and distensibility index or CIMT.

Conclusions

Even though vitamin D levels were inversely correlated with cardiometabolic risk factor score in high-risk children, there are no demonstrable vascular functional or structural effects.

Fibroblast growth factor-23 helps explain the biphasic cardiovascular effects of vitamin D in chronic kidney disease

Hypovitaminosis D is highly prevalent in chronic kidney disease (CKD). Recently, vitamin D has sparked widespread interest because of its potential favorable benefits on cardiovascular disease (CVD). Evidence from clinical studies and animal models supports the existence of biphasic cardiovascular effects of vitamin D, in which lower doses suppress CVD and higher doses stimulate CVD. However, the mechanism for the different effects remains unclear. Fibroblast growth factor-23 (FGF-23) is a recently identified member of the FGF family, and thought to be actively involved in renal phosphate and vitamin D homeostasis. More specifically, Vitamin D stimulates FGF-23 secretion and is inhibited by increased FGF-23. Given this background, we hypothesize that FGF-23 may provide a unique tool to explain the biphasic cardiovascular effects of vitamin D in CKD. The data presented in this review support the hypothesis that FGF-23 may be linked with the high cardiovascular risk in CKD through accelerating the onset of vascular calcification, secondary hyperparathyroidism, left ventricular hypertrophy and endothelial dysfunction. Therefore, modulation of FGF-23 may become a potential therapeutic target to lowing cardiovascular risk in CKD. Several clinical interventions, including decreased phosphate intake, phosphate binders, cinacalcet plus concurrent low-dose vitamin D, C-terminal tail of FGF-23 and renal transplantation, have been employed to manipulate FGF-23.

Reduction in atherosclerotic events: a retrospective study in an outpatient cardiology practice

INTRODUCTION

Although atherosclerotic disease cannot be cured, risk of recurrent events can be reduced by application of evidence-based treatment protocols involving aspirin, beta blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and statin medications. We studied atherosclerotic event rates in a patient population treated before and after the development of aggressive risk factor reduction treatment protocols.

MATERIAL AND METHODS

We performed a retrospective chart review of patients presenting for follow-up treatment of coronary artery disease in a community cardiology practice, comparing atherosclerotic event rates and medication usage in a 2-year treatment period prior to 2002 and a 2-year period in 2005-2008. Care was provided in both the early and later eras by 7 board-certified cardiologists in a suburban cardiology practice. Medication usage was compared in both treatment eras. The primary outcome was a composite event rate of myocardial infarction, cerebrovascular events, and coronary interventions.

RESULTS

Three hundred and fifty-seven patients were studied, with a follow-up duration of 12.1 (±3.5) years. There were 132 composite events in 104 patients (29.1%) in the early era compared to 40 events in 33 patients (9.2%) in the later era (p < 0.0001). From the early to the later eras, there was an increase in use of β-blockers (66% to 83%, p < 0.0001), angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (34% to 80%, p < 0.0001), and statins (40% to 90%, p < 0.0001).

CONCLUSIONS

Application of aggressive evidence-based medication protocols for treatment of atherosclerosis is associated with a significant decrease in atherosclerotic events or need for coronary intervention.