A variant in CYP2R1 predicts circulating vitamin D levels after supplementation with high-dose of vitamin D in healthy adolescent girls

Accumulated LPS induced by colitis altered the activities of vitamin D-metabolizing hydroxylases and decreased the generation of 25-hydroxyvitamin D

It is generally accepted that low vitamin D (VD) levels are associated with a high prevalence factor for Inflammatory bowel disease (IBD). IBD patients have observed higher levels of lipopolysaccharide (LPS), ALT, and AST than healthy people. Gut-derived LPS causes inflammatory injury in the liver and kidney. The VD-metabolizing mechanism is involved in the liver and kidney, which means IBD might impact VD metabolism. However, whether IBD affects VD metabolism has not been studied. In vitro LPS resulted in decreased CYP2R1 in liver cells as well as decreased CYP27B1 and increased CYP24A1 in kidney cells, revealing that LPS changed the activities of several hydroxylases. Mice with acute colitis had an increased LPS in serum and liver with mild hepatic injuries, while mice with chronic colitis had a significant elevation of LPS in serum, liver, and kidney with hepatorenal injuries. Thus, the liver hydroxylase for VD metabolism would be the first to be affected in IBD. Consequently, serum 25-hydroxyvitamin D declined dramatically with a significant elevation of 24,25-dihydroxyvitamin D and 1,24,25-trihydroxyvitamin D. Unchanged serum levels of 1,25-dihydroxyvitamin D might be the result of other factors in vivo. In acute colitis, a small dosage (4 IU/day) of cholecalciferol could protect the colon, decrease the serum level of LPS, and finally increase serum 25-hydroxyvitamin D. However, this improvement of cholecalciferol was fading in chronic colitis. These results suggested that VD supplementations for preventing and curing IBD in the clinic should consider hepatorenal hydroxylases and be employed as soon as possible for a better outcome.

The impact of genetic variants related to vitamin D and autoimmunity: A systematic review

Over the past few years, there has been a notable increment in scientific literature aimed at unraveling the genetic foundations of vitamin D signaling and its implications for susceptibility to autoimmunity, however, most of them address isolated diseases. Here, we conducted a systematic review of genetic variants related to vitamin D and autoimmune diseases and we discussed the current landscape of susceptibility and outcomes. Of 65 studies analyzed, most variants cited are in vitamin D binding protein (VDBP; rs2282679 GC gene), 25-hydroxylase (rs10751657 CYP2R1), 1α-hydroxylase (rs10877012, CYP27B1) and the nuclear hormone receptor superfamily [FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) in VDR gene]. Therefore, our findings confirmed the associations of several genetic variants of vitamin D signaling with a broad spectrum of autoimmune diseases/traits. In addition, given the low number of papers found with functional analysis, further studies to elucidate the real effect that the variants exert on Vitamin D signaling are recommended.

Impact of daily vitamin D3 supplementation on the risk of vitamin D deficiency with the interaction of rs2282679 in vitamin D binding protein gene (GC) among overweight and obese children and adolescents: A one-year randomized controlled trial

Background

The rs2282679 polymorphism in the vitamin D binding protein (DBP) gene may influence the response to vitamin D supplementation. Therefore, we examine the effect of 1-year vitamin D supplementation on vitamin D deficiency (VDD) with the interaction of rs2282679 polymorphism in overweight and obese children and adolescents.

Materials and methods

The participants (n = 300) were part of a randomized controlled trial who received a daily supplement of either 1,000 or 2,000 IU or four supplements of 1,000 IU weekly (equal to 600 IU daily) of vitamin D₃ for 12 months. Genotyping was performed using amplification refractory mutation system polymerase chain reaction (ARMS-PCR).

Results

The mean of 25(OH)D values at baseline for participants with the TT, TG, and GG genotypes were 15.4, 14.4, and 10.8 ng/mL, respectively, and were not different between the three genotype groups (P = 0.062). A significant reduction in VDD was observed after vitamin D supplementation with dosages of 1,000 or 2,000 IU compared to 600 IU. No significant association of genotypes with risk of VDD was observed in each intervention group after vitamin D supplementation, except, that individuals with TG genotype showed a higher risk of VDD compared to those with TT genotype in the 2,000 IU group after 6 months of supplementation [odds ratio (95% CI): 6.94; 1.30-37.02]. We observed no interaction between time duration, three genotypes, and dosages with serum 25(OH)D, calcium, phosphorus, alkaline phosphatase, and parathyroid hormone levels.

Conclusion

Response to vitamin D supplementation by three doses of 600, 1,000, and 2,000 IU could not be affected by rs2282679 polymorphism during 12 months in overweight and obese children and adolescents.

Three monthly doses of 150,000 IU of oral cholecalciferol correct vitamin D deficiency in adolescents: A pragmatic study

OBJECTIVES

To assess the efficacy of an oral high-dose cholecalciferol regimen in correcting vitamin D deficiency (VDD) in adolescents and to explore potential predictive factors on the response to treatment.

METHODS

This is a retrospective chart review conducted in the Adolescent Outpatient Clinic, Geneva University Hospitals, Switzerland. One hundred-three otherwise healthy vitamin D deficient [serum 25-hydroxyvitamin D, 25(OH)D, level <50 nmol/L] adolescents (mean age 16.6) attending the clinic between 1 January 2016 and 31 December 2018 received 150,000 IU of oral cholecalciferol every month for 3 months (cumulative dose of 450,000 IU). We measured the change in serum 25(OH)D levels pre- and post-treatment and the achievement of serum 25(OH)D level post-treatment ≥75 nmol/L.

RESULTS

The mean serum 25(OH)D level increased by 320%, from 26 nmol/L at baseline to 83 nmol/L at the end of the study (P < .001). The rise was significantly higher for patients initially tested in the winter/spring (mean 65 nmol/L) compared with those initially tested in the summer/autumn (mean 48 nmol/L) (P < .003). No clear relationship was found between the response to treatment and the vitamin D status at baseline. The effect of age, gender, origin and body mass index was not statistically significant.

CONCLUSIONS

The present intermittent high-dose regimen is effective in treating VDD in healthy adolescents without significant variations in response between different subgroups.

Genetic variations of CYP2R1 (rs10741657) in Bangladeshi adults with low serum 25(OH)D level-A pilot study

Background

Some studies revealed that despite having sufficient sun exposure and dietary supply, the level of serum 25(OH)D in Bangladeshi adults is lower than its normal range. Genetic pattern of an individual is also an essential factor that regulates the level of serum 25(OH)D. However, the genetic variations of CYP2R1 (rs10741657) and their association with low serum 25(OH)D level in Bangladeshi adults are yet to be explored.

Objective

This study was conducted to determine the frequency of variants of rs10741657 of CYP2R1 gene and its association with low serum 25(OH)D level among Bangladeshi adults.

Method

This pilot study was conducted among thirty individuals with low serum 25(OH)D level as the study population and ten subjects with sufficient serum 25(OH)D level as controls based on the inclusion and exclusion criteria. Genetic analysis of rs10741657 of CYP2R1 including primer designing, DNA extraction, PCR of target region with purification and Sanger sequencing of the PCR products were done accordingly. For statistical analysis, One-way ANOVA followed by LSD test, Freeman-Halton extension of Fisher’s exact test, Chi-square test (χ²) test and unpaired student t-test were performed.

Results

In this study, genetic variants of CYP2R1 (rs10741657) among the study population were genotype GG (63.30%), GA (30%) and AA (6.7%). Minor allele frequency of the study population was 0.217. The association between GG and GA genotypes of CYP2R1 (rs10741657) with low serum 25(OH)D level among the study population was found and it was statistically significant. Statistically significant differences were also observed between the genotypes and alleles of the study population and controls.

Conclusions

The presence of ‘GG’ and ‘GA’ genotypes of rs1041657 in CYP2R1 gene is associated with low serum 25(OH)D level among Bangladeshi adults in this pilot study.

Association of Vitamin D Metabolism Gene Polymorphisms with Autoimmunity: Evidence in Population Genetic Studies

A high prevalence of vitamin D (calcidiol) serum deficiency has been described in several autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis (AR), and systemic lupus erythematosus (SLE). Vitamin D is a potent immunonutrient that through its main metabolite calcitriol, regulates the immunomodulation of macrophages, dendritic cells, T and B lymphocytes, which express the vitamin D receptor (VDR), and they produce and respond to calcitriol. Genetic association studies have shown that up to 65% of vitamin D serum variance may be explained due to genetic background. The 90% of genetic variability takes place in the form of single nucleotide polymorphisms (SNPs), and SNPs in genes related to vitamin D metabolism have been linked to influence the calcidiol serum levels, such as in the vitamin D binding protein (VDBP; rs2282679 GC), 25-hydroxylase (rs10751657 CYP2R1), 1α-hydroxylase (rs10877012, CYP27B1) and the vitamin D receptor (FokI (rs2228570), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) VDR). Therefore, the aim of this comprehensive literature review was to discuss the current findings of functional SNPs in GC, CYP2R1, CYP27B1, and VDR associated to genetic risk, and the most common clinical features of MS, RA, and SLE.

Association study between genetic variants in vitamin D metabolism related genes and childhood autism spectrum disorder

Vitamin D deficiency has been implicated as a risk factor for autism spectrum disorder (ASD). This case-controlled study was to determine the association between single nucleotide polymorphisms (SNPs) in genes encoding vitamin D metabolism related enzymes and childhood ASD in a Chinese Han population. Both autistic children and age-and gender-matched healthy controls were recruited from September 2012-November 2017. The severity of ASD was evaluated by the childhood autism rating scale (CARS). Taqman probe based real-time PCR was applied to examine genotypes. The association between SNPs and the risk of ASD or the disease severity was examined through the logistic regression. This study recruited 249 children with ASD and 353 healthy controls. The G/A genotype (P = 0.0112) or the G allele (P = 0.0117) of CYP24A1 rs17219315, and the G/A genotype of CYP27B1 rs4646536 (P = 0.0341) were significantly associated with an increased risk of ASD. In addition, multivariate analysis found that A allele of both CYP2R1 rs12794714 (P = 0.0159) and CYP27B1 rs4646536 (P = 0.0268) were significantly associated with the severity of ASD. Genetic polymorphisms in vitamin D metabolism related enzymes are associated with the risk of childhood ASD and the severity of the disease.