A narrow-band ultraviolet B course improves vitamin D balance and alters cutaneous CYP27A1 and CYP27B1 mRNA expression levels in haemodialysis patients supplemented with oral vitamin D

Raising awareness on the therapeutic role of cholecalciferol in CKD: a multidisciplinary-based opinion

Vitamin D is recognized to play an essential role in health and disease. In kidney disease, vitamin D analogs have gained recognition for their involvement and potential therapeutic importance. Nephrologists are aware of the use of oral native vitamin D supplementation, however, uncertainty still exists with regard to the use of this treatment option in chronic kidney disease as well as clinical settings related to chronic kidney disease, where vitamin D supplementation may be an appropriate therapeutic choice. Two consecutive meetings were held in Florence in July and November 2016 comprising six experts in kidney disease (N = 3) and bone mineral metabolism (N = 3) to discuss a range of unresolved issues related to the use of cholecalciferol in chronic kidney disease. The panel focused on the following six key areas where issues relating to the use of oral vitamin D remain controversial: (1) vitamin D and parathyroid hormone levels in the general population, (2) cholecalciferol in chronic kidney disease, (3) vitamin D in cardiovascular disease, (4) vitamin D and renal bone disease, (5) vitamin D in rheumatological diseases affecting the kidney, (6) vitamin D and kidney transplantation.

Vitamin D-Related Gene Polymorphisms, Plasma 25-Hydroxy-Vitamin D, Cigarette Smoke and Non-Small Cell Lung Cancer (NSCLC) Risk

Epidemiological studies regarding the relationship between vitamin D, genetic polymorphisms in the vitamin D metabolism, cigarette smoke and non-small cell lung cancer (NSCLC) risk have not been investigated comprehensively. To search for additional evidence, the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique and radioimmunoassay method were utilized to evaluate 5 single-nucleotide polymorphisms (SNPs) in vitamin D receptor (VDR), 6 SNPs in 24-hydroxylase (CYP24A1), 2 SNPs in 1α-hydroxylase (CYP27B1) and 2 SNPs in vitamin D-binding protein (group-specific component, GC) and plasma vitamin D levels in 426 NSCLC cases and 445 controls from China. Exposure to cigarette smoke was ascertained through questionnaire information. Multivariable linear regressions and mixed effects models were used in statistical analysis. The results showed that Reference SNP rs6068816 in CYP24A1, rs1544410 and rs731236 in VDR and rs7041 in GC were statistically significant in relation to reduction in NSCLC risk (p < 0.001-0.05). No significant connection was seen between NSCLC risk and overall plasma 25-hydroxyvitamin D [25(OH)D] concentrations, regardless of smoking status. However, the mutation genotype of CYP24A1 rs6068816 and VDR rs1544410 were also significantly associated with increased 25(OH)D levels only in both the smoker and non-smoker cases (p < 0.01-0.05). Meanwhile, smokers and non-smokers with mutated homozygous rs2181874 in CYP24A1 had significantly increased NSCLC risk (odds ratio (OR) = 2.14, 95% confidence interval (CI) 1.47-3.43; p = 0.031; OR = 3.57, 95% CI 2.66-4.74; p = 0.019, respectively). Smokers with mutated homozygous rs10735810 in VDR had significantly increased NSCLC risk (OR = 1.93, 95% CI 1.41-2.76; p = 0.015). However, smokers with mutated homozygous rs6068816 in CYP24A1 had significantly decreased NSCLC risk (OR = 0.43, 95% CI 0.27-1.02; p = 0.006); and smokers and non-smokers with mutated homozygous rs1544410 in VDR had significantly decreased NSCLC risk (OR = 0.51, 95% CI 0.34-1.17; p = 0.002; OR = 0.26, 95% CI 0.20-0.69; p = 0.001, respectively). There are significant joint effects between smoking and CYP24A1 rs2181874, CYP24A1 rs6068816, VDR rs10735810, and VDR rs1544410 (p < 0.01-0.05). Smokers with mutated homozygous rs10735810 in VDR had significantly increased NSCLC risk (OR = 1.93, 95% CI 1.41-2.76; p = 0.015). In summary, the results suggested that the lower the distribution of vitamin D concentration, the more the genetic variations in CYP24A1, VDR and GC genes may be associated with NSCLC risk. In addition, there are significant joint associations of cigarette smoking and vitamin D deficiency on NSCLC risk.

Relative importance of the determinants of serum levels of 25-hydroxy vitamin D in patients with chronic kidney disease

INTRODUCTION

The cause of vitamin D deficiency in chronic kidney disease (CKD) is probably multi-factorial; however, the relative importance of each potential determinant is uncertain.

AIMS

To determine factors associated with serum levels of 25-hydroxy vitamin D (25OHD) and their relative importance in a cohort of pre-dialysis CKD patients.

MATERIAL AND METHODS

Incident patients admitted to a CKD outpatient clinic were included. Those who were receiving vitamin D supplements or anticonvulsants were excluded. In addition to demographic and clinical data, information about outdoor physical activity, season of blood collection, prescription of statins, anti-angiotensin drugs and xanthine-oxidase inhibitors were included as potential determinants. Johnson's relative weights analysis was used to estimate the relative importance of each potential determinant and the results were expressed as percentage contribution to multiple R.

RESULTS

The study group consisted of 397 patients, 30 of whom were excluded. The mean serum level of 25OHD was 13.7±7.4ng/ml, and 81% of patients had serum levels lower than 20ng/ml. By multiple linear regression and relative weights analyses, the best determinants of low serum 25OHD levels and their relative importance were: higher proteinuria (28.5%), old age (21.4%), low physical activity (19.4%), female gender (19.3%) and low serum bicarbonate levels (11.4%).

CONCLUSIONS

Proteinuria and age are the determinants with the highest relative importance for predicting 25OHD levels in CKD patients.

The trials and tribulations of vitamin D: time for the 'sunshine' vitamin to come in out of the cold - or just more broken promises?

We are presently faced with the competing notions of modern life being a 'state of vitamin D depletion', implying a widespread need to supplement with vitamin D, or, the opposite view, which is that the present evidence can only support at best selective targeted vitamin D intervention. This is important as there is evidence that over the last 40-50 years there were downwards global trends in serum 25(OH)D concentrations, while individual consumption of vitamin D as supplements rose. For this reason and many others, a large population-based interventional study, the VITAL trial, was designed to try to establish the health value of vitamin D supplementation. VITAL is a huge primary prevention trial looking at the effects of vitamin D repletion in preventing cancer and cardiovascular disease in a fundamentally healthy population. This may seem an unusual approach given that what we mostly know about vitamin D is that is has some effects on the skeleton. This review looks to explore current knowledge about vitamin D in health and disease, and at how this is now undergoing significant reappraisal and revision. We will carefully critique the VITAL study design to see if it will allow for the construction of the detailed portfolio of clinical evidence so urgently needed to allow us better to understand role of vitamin D supplementation in health and disease.