Molecular mechanism of vitamin D in the cardiovascular system

Determining correlation between changes in blood pressure and vitamin D levels: Analyzing influencing factors in hypertensive adults at Family Medicine Clinics

Background

Dietary sodium and renin-angiotensin system activity are pivotal in causing primary hypertension. Vitamin D levels inversely relate to the renin-angiotensin system. Our study investigates the association between vitamin D fluctuations and blood pressure control in hypertensive patients undergoing general health checkups.

Methodology

A cross-sectional study enrolled participants with essential hypertension from family medicine clinics at the Aga Khan University Hospital, Karachi, coming for a general health checkup. Data including demographics, Vitamin D levels, blood pressure, factors associated with hypertension, and vitamin D deficiency were noted and analyzed using SPSS 20. Post-stratification chi-square test was applied to check for the association between different categorical variables.

Results

In a study of 203 hypertensive subjects (mean age: 58.07 ± 11 years, 56.2% male, 63.5% Urdu speaking), 41.4% were smokers, and 63.1% had other comorbidities along with hypertension. Significant vitamin D deficiency was observed in 81.8%, with 55.7% exhibiting uncontrolled blood pressure. Vitamin D levels were significantly associated with blood pressure changes, sun exposure, gender, physical activity, and salt restriction. Smoking and obesity are also correlated with blood pressure changes.

Conclusion

Pakistan faces significant hypertension and vitamin D deficiency burdens. Our study found a potential link between varying vitamin D levels and blood pressure fluctuations in hypertensive patients, warranting further research.

Effect of Vitamin D supplementation on blood pressure in hypertensive individuals with hypovitaminosis D: a systematic review and meta-analysis

In the present study, we aimed to conduct a literature review and meta-analysis to assess the effect of Vitamin D supplementation on SBP and DBP levels in individuals with hypertension and hypovitaminosis D. PubMed, Scopus, Web of Science, and SciELO were systematically searched for relevant publications until January 2023. The review has been registered at PROSPERO (CRD42023400035). To compare the effects of vitamin D with placebo, the mean differences with 95% confidence intervals (95% CIs) were pooled based on the random-effects model. Subgroup analyses were performed to identify the source of heterogeneity, and assessment of study quality was conducted using the GRADE approach. Publication bias was evaluated using funnel plots and Egger's tests. In total, 14 randomized controlled trials (RCTs) were included in this systematic review, and 11 trials were selected for meta-analysis. The data showed that Vitamin D significantly decreased SBP levels; however, it did not affect DBP levels. In subgroup analysis, Vitamin D supplementation significantly decreased in SBP in studies involving individuals over 60 years of age, with a dose greater than 400 000 IU, duration greater than 8 weeks, frequency of weekly supplementation in studies conducted in Asia. In addition, subgroup analysis revealed a significant reduction in DBP in the weekly frequency subgroups and in the studies carried out in Asia. This meta-analysis indicated that Vitamin D significantly reduced the SBP in individuals with hypertension and hypovitaminosis D. Further, well designed trials are necessary to validate these results.

Association of vitamin D receptor polymorphisms with cardiometabolic conditions in Pakistani population

Apart from bone related effects, vitamin D has roles in immune modulation, hypertension, diabetes and cardiovascular diseases. Metabolic functions of vitamin D are mediated after binding with vitamin D receptor (VDR). VDR polymorphisms affect its physiological functions. Several VDR single nucleotide polymorphisms (SNPs) were reported previously. However, VDR polymorphisms causing influence on cardiovascular and metabolic disorders have not been investigated in the Pakistani population so far. Therefore, the present study was conducted to evaluate the role of VDR polymorphisms (rs2228570 and rs7975232) in the pathobiology of cardiometabolic disorders. In total, 400 cardiometabolic patients and 226 healthy control human adults were enrolled from Faisalabad, Pakistan. Biochemical parameters (serum glucose, liver function test, renal function test and lipid profile) were analyzed by standard kit methods. Genetic analysis was done by ARMS-PCR assay. Data was analyzed in SPSS v20. Regression analysis revealed that GG and AG genotypes of rs2228570 A>G polymorphism significantly increased the risk of hypertension in cardiovascular patients by 5.29 and 5.94 times respectively (GG: OR=5.29, 95% CI=1.63-17.2, p=0.005; AG: OR=5.94, 95% CI=1.70-20.7, p=0.005). However, rs7975232 C>A polymorphism was not correlated with cardiometabolic conditions. In conclusion, GG and AG genotypes of VDR SNP rs2228570 significantly contribute to hypertension in cardiovascular disease patients.

Vitamin D Determinants, Status, and Antioxidant/Anti-inflammatory-Related Effects in Cardiovascular Risk and Disease: Not the Last Word in the Controversy

Beyond its key role in calcium homeostasis, vitamin D has been found to significantly affect the cardiovascular (CV) system. In fact, low vitamin D levels have been associated with increased CV risk, as well as increased CV morbidity and mortality. The majority of effects of this molecule are related directly or indirectly to its antioxidative and anti-inflammatory properties. Generally, vitamin D insufficiency is considered for 25-hydroxyvitamin D (25(OH)D) levels between 21-29 ng/mL (corresponding to 52.5-72.5 nmol/L), deficiency as 25(OH)D levels less than 20 ng/mL (<50 nmol/L), and extreme deficiency as 25(OH)D less than 10 ng/mL (<25 nmol/L). However, the definition of an optimal vitamin D status, as defined by 25(OH)D, remains controversial for many extra-bone conditions, including CV disease. In this review, confounding factors affecting the 25(OH)D measurement and status will be discussed. In particular, available evidence on the mechanism and role of vitamin D in relation to CV risk and disease through its antioxidant effect will be reported, also facing the aspect regarding the debate on the minimum blood 25(OH)D level required to ensure optimal CV health.

Impact of Vitamin D Supplementation on the Clinical Outcomes and Epigenetic Markers in Patients with Acute Coronary Syndrome

Vitamin D has recently been found to influence the renin-angiotensin system (RAS); it can reduce the effects of renin-angiotensin system inhibitors (RASI) by decreasing plasma renin. This study examines the effect of vitamin D supplements on cardiac fibrosis markers, echocardiographic parameters, and epigenetic markers in patients with established acute coronary syndrome (ACS). It also looks at the incidence of vitamin D receptor (VDR) gene polymorphisms Apa I (rs7975232), Bsm I (rs1544410), Taq I (rs731236), and Fok I (rs2228570) and its association with the development of secondary major acute cardiovascular events (MACE) and heart failure (HF). A randomized controlled trial in which patients were divided into two groups was performed. Group 1 comprised of 125 ACS patients who received ACS standard therapy alone, while Group 2 consisted of 125 ACS patients who received ACS standard therapy plus vitamin D according to their vitamin D levels. Patients were monitored for 24 months to find subsequent MACE and HF. Vitamin D therapy for ACS patients resulted in a substantial decline in end systolic and end diastolic volumes (p = 0.0075 and 0.002, respectively), procollagen type III N-terminal peptide (PIIINP) and soluble ST2 levels (p = 0.007 and 0.001, respectively), as well as in ejection fraction and vitamin D level (p = 0.0001 and 0.008, respectively). In addition, vitamin D treatment was linked to a significant decline in the levels of noncoding RNA, such as mir361, lncRNA MEG3, and lncRNA Chaer (p = 2.9 × 10-4, 2.2 × 10-6, and 1.2 × 10-5, respectively). Furthermore, patients who suffered MACE had significantly higher levels of the Bsm I CC and Fok I GG genotypes (p = 4.8 × 10-4 and 0.003, respectively), while patients with HF had significantly higher levels of the Taq I AA genotype (p = 4.2 × 10-7). Supplementing ACS patients with vitamin D has been demonstrated to limit cardiac fibrosis and echocardiographic parameters, as well as epigenetic markers. Additionally, MACE and HF among ACS patients may be related to genetic variations among VDR gene polymorphisms.

Role of vitamin D in pathogenesis and severity of COVID-19 infection

Coronavirus disease (COVID-19) is an infectious disease caused by a new virus that causes respiratory illness. Older adults and individuals who have pre-existing chronic medical conditions are at higher risk for more serious complications from COVID-19. Hypovitaminosis D is attributed to the increased risk of lung injury and acute respiratory distress syndrome (ARDS) as well as diabetes, cardiovascular events and associated comorbidities, which are the main causes of severe clinical complications in COVID-19 patients. Considering the defensive role of vitamin D, mediated through modulation of the innate and adaptive immune system as well as inhibition of the Renin Angiotensin System (RAS), vitamin D supplementation might boost the immune system of COVID-19 patients and reduce severity of the disease in vitamin D deficient individuals.

Vitamin D deficiency in British South Asians, a persistent but avoidable problem associated with many health risks (including rickets, T2DM, CVD, COVID-19 and pregnancy complications): the case for correcting this deficiency

High vitamin D deficiency rates, with rickets and osteomalacia, have been common in South Asians (SAs) arriving in Britain since the 1950s with preventable infant deaths from hypocalcaemic status-epilepticus and cardiomyopathy. Vitamin D deficiency increases common SA disorders (type 2 diabetes and cardiovascular disease), recent trials and non-linear Mendelian randomisation studies having shown deficiency to be causal for both disorders. Ethnic minority, obesity, diabetes and social deprivation are recognised COVID-19 risk factors, but vitamin D deficiency is not, despite convincing mechanistic evidence of it. Adjusting analyses for obesity/ethnicity abolishes vitamin D deficiency in COVID-19 risk prediction, but both factors lower serum 25(OH)D specifically. Social deprivation inadequately explains increased ethnic minority COVID-19 risks. SA vitamin D deficiency remains uncorrected after 70 years, official bodies using 'education', 'assimilation' and 'diet' as 'proxies' for ethnic differences and increasing pressures to assimilate. Meanwhile, English rickets was abolished from ~1940 by free 'welfare foods' (meat, milk, eggs, cod liver oil), for all pregnant/nursing mothers and young children (<5 years old). Cod liver oil was withdrawn from antenatal clinics in 1994 (for excessive vitamin A teratogenicity), without alternative provision. The take-up of the 2006 'Healthy-Start' scheme of food-vouchers for low-income families with young children (<3 years old) has been poor, being inaccessible and poorly publicised. COVID-19 pandemic advice for UK adults in 'lockdown' was '400 IU vitamin D/day', inadequate for correcting the deficiency seen winter/summer at 17.5%/5.9% in White, 38.5%/30% in Black and 57.2%/50.8% in SA people in representative UK Biobank subjects when recruited ~14 years ago and remaining similar in 2018. Vitamin D inadequacy worsens many non-skeletal health risks. Not providing vitamin D for preventing SA rickets and osteomalacia continues to be unacceptable, as deficiency-related health risks increase ethnic health disparities, while abolishing vitamin D deficiency would be easier and more cost-effective than correcting any other factor worsening ethnic minority health in Britain.

Correlation analysis between vitamin A, D, and E status with altitude, seasonal variation, and other factors, among children aged 0-6 years in a Chinese population living in the Tibetan plateau of Ganzi prefecture

OBJECTIVE

We attempted to understand the status of vitamin (Vit) A, D, and E in children aged 0-6 living in the Tibetan plateau areas of Ganzi prefecture, to provide the basis for relevant government departments to carry out physical examinations of these children and to prevent and cure four key diseases (Infantile diarrhea, nutritional anemia, rickets, and infantile pneumonia).

METHODS

Serum retinol and tocopherol levels were detected using high-performance liquid chromatography (HPLC). Serum levels of 25-(OH)D were detected by high-performance liquid chromatography-tandem mass spectrometry (LC-MS). The polynomial logistic regression was used to analyze the effects of age, season, altitude, and gender on Vit A, D, and E levels.

RESULTS

Vit A and D had the lowest mean serum levels before the age of 1 year and with the most significant deficiency rates. The lowest Vit E levels were seen in the Toddlerhood group. The rates of deficiency and insufficiency were the highest. Vit A, D, and E levels were significantly affected by seasonal changes and were significantly higher in the summer than in any other season. Vit A and D were significantly affected by altitude, and their levels were lowest above 4 km.

CONCLUSION

The overall levels of Vit A, D, and E in children aged 0-6 in the Tibetan plateau areas of Ganzi prefecture were lower than those in the plain's areas.

Could Vitamin D Be Effective in Prevention of Preeclampsia?

Prevention of preeclampsia (PE) remains one of the most significant problems in perinatal medicine. Due to the possible unpredictable course of hypertension in pregnancy, primarily PE and the high complication rate for the mother and fetus/newborn, it is urgent to offer pregnant women in high-risk groups effective methods of preventing the PE development or delaying its appearance. In addition, due to the association of PE with an increased risk of developing cardiovascular diseases (CVD) in later life, effective preeclampsia prevention could also be important in reducing their incidence. Ideal PE prophylaxis should target the pathogenetic changes leading to the development of PE and be safe for the mother and fetus, inexpensive and freely available. Currently, the only recognized method of PE prevention recommended by many institutions around the world is the use of a small dose of acetylsalicylic acid in pregnant women with risk factors. Unfortunately, some cases of PE are diagnosed in women without recognized risk factors and in those in whom prophylaxis with acetylsalicylic acid is not adequate. Hence, new drugs which would target pathogenetic elements in the development of preeclampsia are studied. Vitamin D (Vit D) seems to be a promising agent due to its beneficial effect on placental implantation, the immune system, and angiogenic factors. Studies published so far emphasize the relationship of its deficiency with the development of PE, but the data on the benefits of its supplementation to reduce the risk of PE are inconclusive. In the light of current research, the key issue is determining the protective concentration of Vit D in a pregnant woman. The study aims to present the possibility of using Vit D to prevent PE, emphasizing its impact on the pathogenetic elements of preeclampsia development.

Vitamin D and COVID-19: A review on the role of vitamin D in preventing and reducing the severity of COVID-19 infection

Severe Acute Respiratory Syndrome Coronavirus‐2 (SARS‐CoV‐2) is a pathogenic coronavirus causing COVID‐19 infection. The interaction between the SARS‐CoV‐2 spike protein and the human receptor angiotensin‐converting enzyme 2, both of which contain several cysteine residues, is impacted by the disulfide‐thiol balance in the host cell. The host cell redox status is affected by oxidative stress due to the imbalance between the reactive oxygen/nitrogen species and antioxidants. Recent studies have shown that Vitamin D supplementation could reduce oxidative stress. It has also been proposed that vitamin D at physiological concentration has preventive effects on many viral infections, including COVID‐19. However, the molecular‐level picture of the interplay of vitamin D deficiency, oxidative stress, and the severity of COVID‐19 has remained unclear. Herein, we present a thorough review focusing on the possible molecular mechanism by which vitamin D could alter host cell redox status and block viral entry, thereby preventing COVID‐19 infection or reducing the severity of the disease.

Coronavirus disease 2019, vitamin D and kidney function

PURPOSE OF REVIEW

The purpose of this review is to summarize the emerging studies analyzing the association between vitamin D and risk of COVID-19 infection and severity, as well as the early interventional studies investigating the protective effect of vitamin D supplementation against COVID-19.

RECENT FINDINGS

Studies investigating the association between vitamin D levels and risk of COVID-19 infection and risk of severe disease and mortality among those infected have yielded mixed results. Thus far, the majority of studies investigating the association between vitamin D and COVID-19 have been observational and rely on vitamin D levels obtained at the time of admission, limiting causal inference. Currently, clinical trials assessing the effects of vitamin D supplementation in individuals with COVID-19 infection are extremely limited. Randomized, interventional trials may offer more clarity on the protective effects of vitamin D against COVID-19 infection and outcomes.

SUMMARY

Decreased levels of vitamin D may amplify the inflammatory effects of COVID-19 infection, yet, data regarding the mortality benefits of vitamin D supplementation in COVID-19-infected individuals are still limited. Current observational data provides the impetus for future studies to including randomized controlled trials to determine whether vitamin D supplementation in COVID-19-infected individuals with kidney disease can improve mortality outcomes.

New Roles for Vitamin D Superagonists: From COVID to Cancer

Vitamin D is a potent steroid hormone that induces widespread changes in gene expression and controls key biological pathways. Here we review pathophysiology of vitamin D with particular reference to COVID-19 and pancreatic cancer. Utility as a therapeutic agent is limited by hypercalcemic effects and attempts to circumvent this problem have used vitamin D superagonists, with increased efficacy and reduced calcemic effect. A further caveat is that vitamin D mediates multiple diverse effects. Some of these (anti-fibrosis) are likely beneficial in patients with COVID-19 and pancreatic cancer, whereas others (reduced immunity), may be beneficial through attenuation of the cytokine storm in patients with advanced COVID-19, but detrimental in pancreatic cancer. Vitamin D superagonists represent an untapped resource for development of effective therapeutic agents. However, to be successful this approach will require agonists with high cell-tissue specificity.

Vitamin D and Lung Outcomes in Elderly COVID-19 Patients

Background and aim: Vitamin D deficiency is frequently reported in patients with SARS-CoV-2 infection. The aim of this study was to correlate the 25OH-Vitamin D serum concentrations with clinical parameters of lung involvement, in elderly patients hospitalized for SARS-CoV-2 infection. Methods: Sixty-five consecutive COVID-19 patients (mean age 76 ± 13 years) and sixty-five sex- and age-matched control subjects (CNT) were analyzed. The following clinical parameters, including comorbidities, were collected at admission: type of pulmonary involvement, respiratory parameters (PaO2, SO2, PaCO2, PaO2/FiO2), laboratory parameters (including 25OH-vitamin D, D-dimer, C-reactive protein). Results: Significantly lower vitamin D serum levels were found in COVID-19 patients than in CNT (median 7.9 vs 16.3 ng/mL, p = 0.001). Interestingly, a statistically significant positive correlation was observed between vitamin D serum levels and PaO2 (p = 0.03), SO2 (p = 0.05), PaO2/FiO2 (p = 0.02), while a statistically significant negative correlation was found between vitamin D serum levels and D-dimer (p = 0.04), C-reactive protein (p = 0.04) and percentage of O2 in a venturi mask (p = 0.04). A negative correlation was also observed between vitamin D serum levels and severity of radiologic pulmonary involvement, evaluated by computed tomography: in particular, vitamin D was found significantly lower in COVID-19 patients with either multiple lung consolidations (p = 0.0001) or diffuse/severe interstitial lung involvement than in those with mild involvement (p = 0.05). Finally, significantly lower vitamin D serum levels were found in the elderly COVID-19 patients who died during hospitalization, compared to those who survived (median 3.0 vs 8.4 ng/mL, p = 0.046). Conclusions: This study confirms that 25OH-vitamin D serum deficiency is associated with more severe lung involvement, longer disease duration and risk of death, in elderly COVID-19 patients. The detection of low vitamin D levels also in younger COVID-19 patients with less comorbidities further suggests vitamin D deficiency as crucial risk factor at any age.

Review on COVID-19 Etiopathogenesis, Clinical Presentation and Treatment Available with Emphasis on ACE2

In December 2019, Wuhan city in the Hubei province of China reported for the first time a cluster of patients infected with a novel coronavirus, since then there has been an outburst of this disease across the globe affecting millions of human inhabitants. Severe acute respiratory syndrome coronavirus type-2 (SARS-CoV-2), is a member of beta coronavirus family which upon exposure caused a highly infectious disease called novel coronavirus disease-2019 (COVID-19). COVID-19, a probably bat originated disease was declared by World Health Organization (WHO) as a global pandemic in March 2020. Since then, despite rigorous global containment and quarantine efforts, the disease has affected nearly 56,261,952 laboratory confirmed human population and caused deaths of over 1,349,506 lives worldwide. Virus passes in majority through respiratory droplets and then enters lung epithelial cells by binding to angiotensin converting enzyme 2 (ACE2) receptor and there it undergoes replication and targeting host cells causing severe pathogenesis. Majority of human population exposed to SARS-CoV-2 having fully functional immune system undergo asymptomatic infection while 5-10% are symptomatic and only 1-2% are critically affected and requires ventilation support. Older people or people with co-morbidities are severely affected by COVID-19. These categories of patients also display cytokine storm due to dysfunctional immune response which brutally destroys the affected organs and may lead to death in some. Real time PCR is still considered as standard method of diagnosis along with other serology, radiological and biochemical investigations. Till date, no specific validated medication is available for the treatment of COVID-19 patients. Thus, this review provides detailed knowledge about the different landscapes of disease incidence, etiopathogenesis, involvement of various organs, diagnostic criteria's and treatment guidelines followed for management of COVID-19 infection since its inception. In conclusion, extensive research to recognize novel pathways and their cross talk to combat this virus in precarious settings is our future positive hope.

MECHANISMS IN ENDOCRINOLOGY: Vitamin D and COVID-19

The SARS-CoV-2 virus responsible for the COVID-19 pandemic has generated an explosion of interest both in the mechanisms of infection leading to dissemination and expression of this disease, and in potential risk factors that may have a mechanistic basis for disease propagation or control. Vitamin D has emerged as a factor that may be involved in these two areas. The focus of this article is to apply our current understanding of vitamin D as a facilitator of immunocompetence both with regard to innate and adaptive immunity and to consider how this may relate to COVID-19 disease. There are also intriguing potential links to vitamin D as a factor in the cytokine storm that portends some of the most serious consequences of SARS-CoV-2 infection, such as the acute respiratory distress syndrome. Moreover, cardiac and coagulopathic features of COVID-19 disease deserve attention as they may also be related to vitamin D. Finally, we review the current clinical data associating vitamin D with SARS-CoV-2 infection, a putative clinical link that at this time must still be considered hypothetical.

Can a Combination of AT1R Antagonist and Vitamin D Treat the Lung Complication of COVID-19?

Severe Acute Respiratory Distress Syndrome caused by a novel human coronavirus SARS-CoV-2 named COVID-19 and declared as a pandemic. This paper reviews the possibility of repurposing angiotensin type 1 receptor (AT1R) antagonists and vitamin D to treat COVID-19. ACE2 protein found on the cell membranes is the target of SARS-CoV-2 for entering into the host cells. Viral spike protein-binding with ACE2 down-regulates it. As ACE2 is known to protect the lung from injuries, SARS-CoV-2-induced ACE2 deficiency may expose patients to lung damage. AT1R antagonists and vitamin D increase the expression of ACE2 independently. Besides, vitamin D suppresses the compensatory increase in renin levels following the inhibition of the renin-angiotensin system by AT1R antagonists. Therefore, a combination of AT1R antagonists and vitamin D may offer protection against COVID-19 induced lung injury.

Clinical characteristics, laboratory findings, radiographic signs and outcomes of 61,742 patients with confirmed COVID-19 infection: A systematic review and meta-analysis

INTRODUCTION

In the current time where we face a COVID-19 pandemic, there is no vaccine or effective treatment at this time. Therefore, the prevention of COVID-19 and the rapid diagnosis of infected patients is crucial.

METHOD

We searched all relevant literature published up to February 28, 2020. We used Random-effect models to analyze the appropriateness of the pooled results.

RESULT

Eighty studies were included in the meta-analysis, including 61,742 patients with confirmed COVID-19 infection. 62.5% (95% CI 54.5-79, p < 0.001) of patients had a history of recent travel endemic area or contact with them. The most common symptoms among COVID-19 infected patients were fever 87% (95% CI 73-93, p < 0.001), and cough 68% (95% CI 55.5-74, p < 0.001)), respectively. The laboratory analysis showed that thrombocytosis was present in 61% (95% CI 41-78, p < 0.001) CRP was elevated in 79% (95% CI 65-91, p < 0.001), and lymphopenia in 57.5% (95% CI 42-79, p < 0.001). The most common radiographic signs were bilateral involvement in 81% (95% CI 62.5-87, p < 0.001), consolidation in 73.5% (95% CI 50.5-91, p < 0.001), and ground-glass opacity 73.5% (95% CI 40-90, p < 0.001) of patients. Case fatality rate (CFR) in <15 years old was 0.6%, in >50 years old was 39.5%, and in all range group was 6%.

CONCLUSIONS

Fever and cough are the most common symptoms of COVID-19 infection in the literature published to date. Thombocytosis, lymphopenia, and increased CRP were common lab findings although most patients included in the overall analysis did not have laboratory values reported. Among Chinese patients with COVID-19, rates of hospitalization, critical condition, and hospitalization were high in this study, but these findings may be biased by reporting only confirmed cases.

A brief review of interplay between vitamin D and angiotensin-converting enzyme 2: Implications for a potential treatment for COVID-19

The novel coronavirus disease 2019 (COVID-19) is rapidly expanding and causing many deaths all over the world with the World Health Organization (WHO) declaring a pandemic in March 2020. Current therapeutic options are limited and there is no registered and/or definite treatment or vaccine for this disease or the causative infection, severe acute respiratory coronavirus 2 syndrome (SARS-CoV-2). Angiotensin-converting enzyme 2 (ACE2), a part of the renin-angiotensin system (RAS), serves as the major entry point into cells for SARS-CoV-2 which attaches to human ACE2, thereby reducing the expression of ACE2 and causing lung injury and pneumonia. Vitamin D, a fat-soluble-vitamin, is a negative endocrine RAS modulator and inhibits renin expression and generation. It can induce ACE2/Ang-(1-7)/MasR axis activity and inhibits renin and the ACE/Ang II/AT1R axis, thereby increasing expression and concentration of ACE2, MasR and Ang-(1-7) and having a potential protective role against acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Therefore, targeting the unbalanced RAS and ACE2 down-regulation with vitamin D in SARS-CoV-2 infection is a potential therapeutic approach to combat COVID-19 and induced ARDS.

Vitamin D levels condition the outcome benefits of renin-angiotensin system inhibitors (RASI) among patients undergoing percutaneous coronary intervention

BACKGROUND

Vitamin D deficiency is estimated as the most common medical condition worldwide, with severe implications on survival and on several inflammatory, immune-mediated and thrombotic disorders, and especially for cardiovascular disease. Recent studies have suggested that vitamin D could directly regulate the Renin-Angiotensin System (RAS) activity, therefore potentially interfering with the pharmacological effects of RAS Inhibitors (RASI), an issue that has seldom been explored. Therefore, the aim of the present study was to evaluate the prognostic impact of the use of RASI according to vitamin D levels among patients with coronary artery disease (CAD) undergoing percutaneous coronary intervention (PCI).

METHODS

Consecutive patients undergoing PCI were included. Main clinical features and chemistry parameters were assessed at admission. Vitamin D levels were measured by chemiluminescence immunoassay kit LIAISON® Vitamin D assay (Diasorin Inc). Severe deficiency was defined for 25(OH)D < 10 ng/mL. The primary study endpoint was defined as the occurrence of major cardiovascular events (MACE, a composite of death, recurrent Myocardial Infarction (MI) and target vessel revascularization) at the longest available follow-up.

RESULTS

We included a total of 705 patients, that were divided according to vitamin D tertiles (< 12.7 ng/mL; 12.7-21.59 ng/mL; ≥21.6 ng/mL) and use of RASI. RASI therapy was significantly associated to arterial hypertension, creatinine, lower 25(OH)D, use of statins, diuretics, ASA and ticagrelor across vitamin D tertiles. At a median follow-up of 996 [377-1552] days, MACE occurred in 174 (24.7 %) patients. Severe hypovitaminosis D was significantly associated with a higher rate of MACE (HR[95 %CI] = 0.75[0.62-0.91], p = 0.004). The use of RASI significantly lowered the rate of MACE in patients with lower vitamin D (I tertile: 41.3 % vs 25.9 %, adjusted HR[95 %CI] = 0.43[0.26-0.73], p = 0.002); whilst a non-significant effect was observed for II and III tertiles values (18.6 %vs 29.5 %, adjusted HR[95 %CI] = 1.16[0.57-2.34], p = 0.69, and 21.2 % vs 12.6 %, adjusted HR[95 %CI] = 1.1[0.46-2.62], p = 0.83) (p int = 0.04). A similar prognostic interaction for RASI and vitamin D was observed for cardiovascular mortality and MI (p int = 0.03).

CONCLUSION

Among patients undergoing PCI, the use of RASI was associated with lower risk of MACE only among patients with lower levels of vitamin D. Future larger studies are certainly warranted in order to define the prognostic implications of vitamin D supplementation on the RAS system modulation, especially among patients treated with RASI.

Status and influential factors of vitamin D among children aged 0 to 6 years in a Chinese population

BACKGROUND

Vitamin D insufficiency and deficiency in childhood are common. However, the status and influential factors of vitamin D during different ages are not clear. This study aimed to survey vitamin D concentrations in children aged 0 to 6 years and explore its influential factors.

METHODS

A total of 6953 children were recruited in Wuxi City of East China from January to December in 2016. Enzyme-linked immunosorbent assay was used to determine the serum concentrations of 25-hydroxyvitamin D [25(OH)D].

RESULTS

The median vitamin D concentrations in the infant group (0-1 years of age) was 69.40 nmol/L, which were higher than that in both the toddlerhood group (1-3 years of age; 62.30 nmol/L) and the preschool group (3-6 years of age; 50.85 nmol/L). In addition, the median vitamin D concentrations were 71.70 nmol/L in summer, which was higher than that in spring (64.25 nmol/L), autumn (62.95 nmol/L) and winter (64.10 nmol/L). However, no difference was observed between genders (P = 0.974). Furthermore, the prevalence of vitamin D deficiency (< 50 nmol/L) was 48.1% in the preschool group (3-6 years of age), which was higher than the 21.2% vitamin D deficiency in the toddlerhood group (1-3 years of age) and the 17.9% vitamin D deficiency in the infant group (0-1 years of age). Interestingly, a nonlinear association between 25(OH) D and air temperature was observed.

CONCLUSIONS

A high prevalence of vitamin D deficiency was common in a Chinese population of children 0-6 years old, especially in the preschool-aged children. Therefore, we suggested that we should pay more attention to vitamin D supplementation in Chinese young children.

Association between vitamin D and hypertension in people coming for health check up to a tertiary care centre in South India

INTRODUCTION

Vitamin D has many effects apart from its role in calcium metabolism and bone health. Vitamin D is derived from endogenous ultraviolet-B induced vitamin D synthesis in the skin, and the current high prevalence of vitamin D deficiency in India, can be attributed to lifestyle related low sunlight exposure. Identification of the vitamin D receptor (VDR) in almost all human cells, suggests a role in extra skeletal diseases. Studies have shown that vitamin D deficiency is an independent risk factor for hypertension.

AIM

To evaluate the association between vitamin D and hypertension in people coming for health check up to a tertiary care center in South India.

MATERIALS AND METHODS

Study was carried out as a cross sectional study in a tertiary care hospital in South India. Participants (520) were both males and females (337 males and 183 females), between the age group of 20-60 years attending the comprehensive health check up clinic of our hospital.

STATISTICAL ANALYSIS

Statistical analysis was done using IBM SPSS statistics 20.0.

RESULTS

Severe vitamin D deficiency was highly prevalent in people with hypertension than in people without hypertension (P value <0.001).

CONCLUSION

Since India is a tropical country, till recently it was believed that vitamin D deficiency and its ill effects are uncommon. But it was found that, vitamin D deficiency was highly prevalent in people with hypertension in South India, emphasizing the need of early vitamin D supplementation. Therefore, to reduce cardiovascular morbidity, early identification of vitamin D deficiency and appropriate vitamin D supplementation may be of primary importance in population, especially like ours, having high prevalence.

Association of Vitamin D Status with Chronic Disease Risk Factors and Cognitive Dysfunction in 50⁻70 Year Old Adults

Vitamin D deficiency/insufficiency has been primarily associated with skeletal disorders, however, since vitamin D receptors are found on multiple types of cells, there is also a link to increased chronic disease risk and all-cause mortality. The aim of this study was to examine whether deficient/insufficient vitamin D levels are associated with risk factors of chronic diseases and cognitive dysfunction in 50 to 70 year old adults. Participants completed the health status, three-day dietary record and vitamin D food frequency, sun exposure, and international physical activity questionnaires. Cognitive function of the participants was assessed using the Automated Neuropsychological Assessment Metrics while body composition (percent body fat, android/gynoid ratio) was assessed using Dual Energy X-ray Absorptiometry. Applanation tonometry was used to obtain pressure wave forms at the radial artery to examine arterial stiffness and central pressures. A fasting blood draw was taken to measure vitamin D, blood lipid and glucose levels. Fifty percent of the participants (36/72) were vitamin D deficient/insufficient. Individuals in the low physical activity (PA) group had lower serum vitamin D concentration compared to those in the high PA group (p = 0.04). Moreover, serum vitamin D levels were negatively related to risk factors of chronic diseases; blood glucose (r = -0.38; p = 0.01), triglycerides (r = -0.27; p = 0.02), and android/gynoid ratio (r = -0.32; p = 0.01). Deficient/insufficient vitamin D levels are linked to the risk factors of chronic diseases in men and women aged 50 to 70 years.

Association of vitamin D receptor gene polymorphisms with serum 25(OH)D levels and metabolic syndrome in Thai population

Metabolic syndrome (MetS) increases the risk of developing cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). The vitamin D receptor gene (VDR) polymorphisms have been found associated with MetS and serum 25(OH)D levels but these associations remain controversial. The aim of this study was to investigate the relationship between the VDR polymorphisms and MetS, metabolic components, and serum 25(OH)D levels within the Thai population. A case-control study included 237 participants with MetS according to the MetS diagnostic criteria of NCEP ATPIII and 376 controls. Anthropometric data, blood pressure, lipid profiles, serum 25 (OH)D, and fasting blood glucose were measured. VDR FokI, BsmI, TaqI, and Cdx2 polymorphisms were genotyped by using PCR-HRM. There were no significant differences in the frequencies of VDR genotypes and alleles between MetS and the control groups. VDR TaqI TT, and BsmI BB + Bb genotypes were associated with lower 25(OH)D levels (p < 0.05) in comparison to TaqI Tt, and BsmI bb genotypes in the MetS group, respectively. In addition, the VDR Cdx2 GG genotype was associated with higher WC compared with the AG genotype in all subjects (p < 0.05). Logistic regression analysis revealed that BB + Bb genotypes of the VDR BsmI had significantly increased the odds ratio (OR) of hypertriglyceridemia when compared with the bb genotype (OR 1.87; 95% CI 1.10-3.19, p = 0.022). In conclusion, VDR BsmI variant was associated with hypertriglyceridemia and may be predisposed to developing MetS. VDR TaqI and BsmI polymorphisms seems to influence serum 25(OH)D levels in MetS subjects, while Cdx2 polymorphism may influence WC in all subjects.

Serum 25-hydroxyvitamin D and the risk of stroke in Hong Kong Chinese

Low vitamin D levels have been associated with various cardiovascular diseases; however, whether it is associated with stroke remains inconclusive. We aimed to evaluate the association between serum 25-hydroxyvitamin D and risk of stroke. We conducted a cohort study consisting of 3,458 participants from the Hong Kong Osteoporosis Study aged ≥45 at baseline, examined between 1995 and 2010 and followed up using electronic medical records. Ischaemic and haemorrhagic stroke were defined using the ICD-9 code. In multivariable Cox-proportional hazard regression, quintiles 1 and 4 were significantly associated with increased risk of stroke when compared to the highest quintile (Quintile 1: HR, 1.78; 95 % CI, 1.16–2.74 and quintile 4: HR, 1.61; 95 % CI, 1.07–2.43). A similar association was observed in both men and women. In subgroup analysis, the association was specifically observed for ischaemic stroke, but not haemorrhagic stroke. Using a penalized regression spline, the association between vitamin D and risk of stroke was in a reverse J-shape, with the lowest risk of stroke being observed at 25(OH)D levels between 70 and 80 nmol/l. In conclusion, a low vitamin D level is associated with increased risk of ischaemic stroke; however, whether high vitamin D level is also associated with increased risk of stroke requires further study.

Supplementary Material to this article is available at www.thrombosis-online.com.

Efficacy of High-Dose Supplementation With Oral Vitamin D3 on Depressive Symptoms in Dialysis Patients With Vitamin D3 Insufficiency: A Prospective, Randomized, Double-Blind Study

Psychological problems are common among end-stage renal disease patients undergoing dialysis. We aim to evaluate whether high-dose vitamin D3 (VD3) supplementation has beneficial effects on depressive symptoms in dialysis patients. This prospective, randomized, and double-blind trial includes 746 dialysis patients with depression treated in 3 hospitals in Southeast China. Depression was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders criteria. Patients were randomly assigned to 52-week treatment of oral 50,000 IU/wk VD3 (cholecalciferol) (test group) or a placebo (control group). The presence of depressive symptoms was evaluated using the Chinese version of Beck Depression Inventory (BDI) II both before and after treatment. Sociodemographic data, clinical data, nutritional indexes, inflammatory biomarkers, and plasma VD3 concentrations were also determined. Finally, 726 patients completed the experiments, including 362 tested patients and 364 controls. After 52 weeks, the depressive symptoms were not significantly improved in the test group (mean BDI II scores changed from -1.1 ± 0.3 to -3.1 ± 0.6) versus the control group. Multivariable logistic regression showed BDI scores were not significantly improved in the test group versus the control group with adjustment for age, sex, comorbidity index, dialysis modality, or (OH)D levels (multivariable-adjusted mean change or MAMC [95% confidence interval (CI)], -2.3 [-2.48 to -1.83]) in the whole dialysis population. After stratification by depression types, the findings do support a significant relationship between the VD3 supplementation and the improvement in BDI II scores in dialysis patients with vascular depression (MAMC [95% CI], -4.4 [-5.08 to -2.76]), but the effect was not significant for major depressive disorders (MAMC [95% CI], -0.9 [-1.52 to -0.63]). The high-dose VD3 supplementation did not significantly reduce the depressive symptoms in our total dialysis population, but a beneficial effect on vascular depression was found, probably mainly based on the improvement of cardiovascular risk factors.

Vitamin D and cardiovascular disease prevention

Vitamin D is a precursor of the steroid hormone calcitriol that is crucial for bone and mineral metabolism. Both the high prevalence of vitamin D deficiency in the general population and the identification of the vitamin D receptor in the heart and blood vessels raised interest in the potential cardiovascular effects of vitamin D. Experimental studies have demonstrated various cardiovascular protective actions of vitamin D, but vitamin D intoxication in animals is known to induce vascular calcification. In meta-analyses of epidemiological studies, vitamin D deficiency is associated with an increased cardiovascular risk. Findings from Mendelian randomization studies and randomized, controlled trials (RCTs) do not indicate significant effects of a general vitamin D supplementation on cardiovascular outcomes. Previous RCTs, however, were not adequately designed to address extraskeletal events, and did not focus on vitamin D-deficient individuals. Therefore, currently available evidence does not support cardiovascular benefits or harms of vitamin D supplementation with the commonly used doses, and whether vitamin D has cardiovascular effects in individuals with overt vitamin D deficiency remains to be evaluated. Here, we provide an update on clinical studies on vitamin D and cardiovascular risk, discuss ongoing vitamin D research, and consider the management of vitamin D deficiency from a cardiovascular health perspective.

The Associations Between the Polymorphisms of Vitamin D Receptor and Coronary Artery Disease: A Systematic Review and Meta-Analysis

Vitamin D receptor (VDR) polymorphisms were indicated to be associated with coronary artery disease (CAD); however, published studies reported inconsistent results.The aim of this meta-analysis is to reach a more accurate estimation of the relationship between VDR genetic polymorphisms and CAD risk.Eligible studies were retrieved by searching PubMed, Embase, VIP, Wanfang and China National Knowledge Infrastructure databases. Included and excluded criteria were formulated. The case group was patients with CAD, and the control group was healthy subjects. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate VDR polymorphisms associations with CAD risk. Heterogeneity was evaluated by Q statistic and I statistic.Seven studies of a total of 2306 CAD patients and 4151 control subjects met the inclusion criteria. The pooled results from Taq1 showed increased risk in allelic model (OR = 1.14, 95% CI = 1.02-1.28), dominant model (OR = 1.21, 95% CI = 1.02-1.43), heterozygote model (OR = 1.19, 95% CI = 1.00-1.1.42), and homozygote model (OR = 1.27, 95% CI = 1.01-1.61). Besides, Fok1 T > C showed decreased risk in allelic model (OR = 0.81, 95% CI = 0.65-1.00) and Fok1 A > G also showed decreased risk in allelic model (OR = 0.67, 95% CI = 0.45-1.00) and recessive model (OR = 0.55, 95% CI = 0.31-0.97). In Caucasian subgroup, Bsm1showed increased risk in allelic model (OR = 1.23, 95% CI = 1.02-1.47), heterozygote model (OR = 1.20, 95% CI = 1.00-1.44), and homozygote model (OR = 1.22, 95% CI = 1.02-1.45). In CAD patients with type 2 diabetes mellitus (T2DM), Apa1showed a decreased risk in heterozygote model (OR = 0.80, 95% CI = 0.66-0.98); however, increased risk in recessive model (OR = 5.00, 95% CI = 2.74-9.13) was discovered in CAD patients without T2DM.The Fok1 polymorphism may play a protective role in CAD, and the possible protective role in Apa1 CA genotype in CAD patients with T2DM needs further studies. The Taq1 polymorphism is found to be associated with a significant increase in CAD risk based on our analysis; moreover, increased risk in Apa1 polymorphism in CAD patients without T2DM and Bsm1 polymorphism in Caucasian group is also detected.

Genetic variation in vitamin D receptor gene (Fok1:rs2228570) is associated with risk of coronary artery disease

OBJECTIVE

The Fok1 polymorphism (rs2228570) in vitamin D receptor gene appears to be the only polymorphism influencing size of translated protein. Investigations into its association with coronary artery disease (CAD) are sparse.

METHODS

Male patients (n = 98) with verified CAD were recruited alongside age- and sex-matched controls (n = 55). Genotyping was performed by PCR-RFLP and plasma 25-Hydroxyvitamin D levels were assessed by HPLC-UV.

RESULTS

The C-variant (mutant) was predominantly expressed in patients compared to controls (68.9% versus 55.5%; p = 0.025). The observed genotypes were not associated with 25-Hydroxyvitamin D levels.

CONCLUSION

This study presents Fok1 polymorphism as a potential genetic marker for CAD.

Vitamin D status, hypertension and ischemic stroke: a clinical perspective

The relationship between vitamin D deficiency and stroke was cross-sectionally evaluated in the high-risk Asian Indian population. Age- and gender-matched, 239 ischemic stroke patients and 241 control subjects were recruited. Vitamin D status was estimated by measuring serum 25-hydroxyvitamin D (25(OH)D) levels. After multivariate adjustment for a range of potential covariates in a logistic regression model, an inverse association was found between serum 25(OH)D concentration and risk of ischemic stroke: subjects with severely low 25(OH)D levels (⩽9.33 ng ml(-1)) were found to be at 3.13-fold (95% confidence interval (CI), (1.22-8.07)) increased risk of ischemic stroke as compared with those with high levels. Adjustment for systolic blood pressure levels was found to abrogate this association (odds ratio (OR)=2.00, 95% CI=0.61-6.50). On stratification, a pronounced association was found between low 25(OH)D and risk of ischemic stroke in hypertensives, OR=13.54, 95% CI=1.94-94.43 as compared with no association in non-hypertensives, (Pinteraction=0.04). We conclude that high blood pressure partly explains the association between 25(OH)D levels and ischemic stroke. Presence of hypertension amply aggravates the risk of ischemic stroke associated with low vitamin D levels. Meticulous management of hypertension, regular monitoring of serum 25(OH)D levels and treatment of severe vitamin D deficiency, particularly in hypertensive subjects, could help in effective prevention of stroke.

Non-linear associations between serum 25-OH vitamin D and indices of arterial stiffness and arteriosclerosis in an older population

BACKGROUND

several studies have been pointing towards a non-linear relationship between serum 25(OH)D and cardiovascular disease. Next to vitamin D deficiency, also higher levels of 25(OH)D have been reported to be associated with increased cardiovascular risk. We aimed to investigate the nature of the relationship between serum 25(OH)D and measures of arterial stiffness and arteriosclerosis in an elderly population.

DESIGN

cross-sectional.

SETTING/SUBJECTS

a subgroup of the B-PROOF study was included to determine associations between serum 25(OH)D and arterial stiffness and atherosclerosis (n = 567, 57% male, age 72.6 ± 5.6 years, mean serum 25(OH)D 54.6 ± 24.1 nmol/l).

METHODS

carotid intima media thickness (IMT) was assessed using ultrasonography and pulse wave velocity (PWV) was determined with applanation tonometry. Associations were tested using multivariable restricted cubic spline functions and stratified linear regression analysis.

RESULTS

the associations between serum 25(OH)D and carotid IMT or PWV were non-linear. Spline functions demonstrated a difference between 25(OH)D deficient and sufficient individuals. In serum 25(OH)D sufficient participants (≥50 nmol/l; n = 287), a positive association with IMT and serum 25(OH)D was present (β 1.24; 95%CI [0.002; 2.473]). PWV levels were slightly lower in vitamin D deficient individuals, but the association with 25(OH)D was not significant.

CONCLUSION

our study demonstrates that associations of serum 25(OH)D and PWV and IMT in an elderly population are not linear. In particular from serum 25(OH)D levels of 50 nmol/l and up, there is a slight increase of IMT with increasing 25(OH)D levels.

Vitamin D deficiency and cardiovascular disease: potential mechanisms and novel perspectives

Interest in contemporary vitamin D research has been sparked in recent years, stemming from the identification of vitamin D receptors in virtually all cells as well as the enzymatic machinery necessary to produce its active form. Both epidemiological and in-vitro studies have linked vitamin D deficiency to enigmatic diseases including cardiovascular disease; however, a clear mechanistic link remains missing. This review highlights conclusions of observational studies, in-vitro experiments and randomized-controlled trials that aimed to link deficiency of the sunshine vitamin to one of the leading causes of death in the world, cardiovascular disease. Furthermore, putative mechanisms viewed from a novel perspective are also discussed.

Vitamin D receptor gene polymorphisms (TaqI and ApaI) in relation to 25-hydroxyvitamin D levels and coronary artery disease incidence

CONTEXT/OBJECTIVE

Previous studies have illustrated the association of the ApaI and TaqI polymorphisms of the vitamin D receptor gene, located in non-coding and coding regions, respectively, with diseases such as cancer and cardiovascular disease; however, investigating such association in Egyptian patients with coronary artery disease (CAD) has never been formerly attempted.

MATERIALS AND METHODS

Male patients (n = 137), 35-50 years of age, with verified CAD, were recruited alongside age- and sex-matched controls (n = 58). Genotyping and 25-hydroxyvitamin D [25(OH)D] measurement were performed by polymerase chain reaction RFLP and HPLC, respectively.

RESULTS

Comparison of the genotypic distribution of both the TaqI and ApaI polymorphisms between patients and controls yielded insignificant results (p = 0.55 and 0.7, respectively). Comparison of the allelic distribution of both polymorphisms also yielded insignificant results. The TaqI polymorphism was not found to predict 25(OH)D levels, whereas the wild-type genotype of the ApaI polymorphism was associated with greater levels of 25(OH)D (p = 0.02), taking all subjects into consideration.

DISCUSSION/CONCLUSION

This study presents the ApaI and TaqI polymorphisms as non-influencing players in the pathogenesis of CAD in Egyptian males and the ability of only the ApaI polymorphism to predict 25(OH)D levels, thus warranting further investigations of the triangular relationship between the polymorphisms, 25(OH)D and CAD incidence.

Vitamin D receptor signaling in renal and cardiovascular protection

The high prevalence of vitamin D deficiency in patients with chronic kidney disease is believed to be an important risk factor for the cardiorenal syndrome commonly seen in this patient population. African Americans suffer a disproportionally high incidence of renal and cardiovascular disease with poor disease outcome, which may be partly attributed to their low vitamin D status in part owing to low subcutaneous photoproduction of vitamin D. Mounting evidence from animal and clinical studies has shown beneficial effects of vitamin D therapy on the renal and cardiovascular systems, and the underlying renoprotective and cardioprotective mechanisms of vitamin D receptor (VDR)-mediated signaling are under intense investigation. In this article, our most recent understanding of the renal protective mechanism of the podocyte VDR signaling against diabetic nephropathy and the anti-atherosclerotic role of macrophage VDR signaling in the regulation of atherosclerosis is reviewed.

Vitamin D induces increased systolic arterial pressure via vascular reactivity and mechanical properties

Background/Aims

The aim of this study was to evaluate whether supplementation of high doses of cholecalciferol for two months in normotensive rats results in increased systolic arterial pressure and which are the mechanisms involved. Specifically, this study assesses the potential effect on cardiac output as well as the changes in aortic structure and functional properties.

Methods

Male Wistar rats were divided into three groups: 1) Control group (C, n = 20), with no supplementation of vitamin D, 2) VD3 (n = 19), supplemented with 3,000 IU vitamin D/kg of chow; 3) VD10 (n = 21), supplemented with 10,000 IU vitamin D/kg of chow. After two months, echocardiographic analyses, measurements of systolic arterial pressure (SAP), vascular reactivity, reactive oxygen species (ROS) generation, mechanical properties, histological analysis and metalloproteinase-2 and -9 activity were performed.

Results

SAP was higher in VD3 and VD10 than in C rats (p = 0.001). Echocardiographic variables were not different among groups. Responses to phenylephrine in endothelium-denuded aortas was higher in VD3 compared to the C group (p = 0.041). Vascular relaxation induced by acetylcholine (p = 0.023) and sodium nitroprusside (p = 0.005) was impaired in both supplemented groups compared to the C group and apocynin treatment reversed impaired vasodilation. Collagen volume fraction (<0.001) and MMP-2 activity (p = 0.025) was higher in VD10 group compared to the VD3 group. Elastin volume fraction was lower in VD10 than in C and yield point was lower in VD3 than in C.

Conclusion

Our findings support the view that vitamin D supplementation increases arterial pressure in normotensive rats and this is associated with structural and functional vascular changes, modulated by NADPH oxidase, nitric oxide, and extracellular matrix components.

The role of vitamin D deficiency in cardiovascular disease: where do we stand in 2013?

The high worldwide prevalence of vitamin D deficiency is largely the result of low sunlight exposure with subsequently limited cutaneous vitamin D production. Classic manifestations of vitamin D deficiency are linked to disturbances in bone and mineral metabolism, but the identification of the vitamin D receptor in almost every human cell suggests a broader role of vitamin D for overall and cardiovascular health. The various cardiovascular protective actions of vitamin D such as anti-diabetic and anti-hypertensive effects including renin suppression as well as protection against atherosclerosis and heart diseases are well defined in previous experimental studies. In line with this, large epidemiological studies have highlighted vitamin D deficiency as a marker of cardiovascular risk. However, randomized controlled trials (RCTs) on vitamin D have largely failed to show its beneficial effects on cardiovascular diseases and its conventional risk factors. While most prior vitamin D RCTs were not designed to assess cardiovascular outcomes, some large RCTs have been initiated to evaluate the efficacy of vitamin D supplementation on cardiovascular events in the general population. When considering the history of previous disappointing vitamin RCTs in general populations, more emphasis should be placed on RCTs among severely vitamin D-deficient populations who would most likely benefit from vitamin D treatment. At present, vitamin D deficiency can only be considered a cardiovascular risk marker, as vitamin D supplementation with doses recommended for osteoporosis treatment is neither proven to be beneficial nor harmful in cardiovascular diseases.

Vitamin D receptor signaling inhibits atherosclerosis in mice

Although vitamin D has been implicated in cardiovascular protection, few studies have addressed the role of vitamin D receptor (VDR) in atherosclerosis. Here we investigate the effect of inactivation of the VDR signaling on atherogenesis and the antiatherosclerotic mechanism of vitamin D. Low density lipoprotein receptor (LDLR)(-/-)/VDR(-/-) mice exhibited site-specific accelerated atherogenesis, accompanied by increases in adhesion molecules and proinflammatory cytokines in the aorta and cholesterol influx in macrophages. Macrophages showed marked renin up-regulation in the absence of VDR, and inhibition of renin by aliskiren reduced atherosclerosis in LDLR(-/-)/VDR(-/-) mice, suggesting that the renin-angiotensin system (RAS) promotes atherosclerosis in the absence of VDR. LDLR(-/-) mice receiving LDLR(-/-)/VDR(-/-) BMT developed larger lesions than LDLR(-/-) BMT controls. Moreover, LDLR(-/-) mice receiving Rag-1(-/-)/VDR(-/-) BMT, which were unable to generate functional T and B lymphocytes, still had more severe atherosclerosis than Rag-1(-/-) BMT controls, suggesting a critical role of macrophage VDR signaling in atherosclerotic suppression. Aliskiren treatment eliminated the difference in lesions between Rag-1(-/-)/VDR(-/-) BMT and Rag-1(-/-) BMT recipients, indicating that local RAS activation in macrophages contributes to the enhanced atherogenesis seen in Rag-1(-/-)/VDR(-/-) BMT mice. Taken together, these observations provide evidence that macrophage VDR signaling, in part by suppressing the local RAS, inhibits atherosclerosis in mice.