The influence of vitamin D receptor genetic variants on bone mineral density and osteoporosis in Chinese postmenopausal women

Eldecalcitol prevents muscle loss and osteoporosis in disuse muscle atrophy via NF-κB signaling in mice

We investigated the effect of eldecalcitol on disuse muscle atrophy. C57BL/6J male mice aged 6 weeks were randomly assigned to control, tail suspension (TS), and TS-eldecalcitol-treated groups and were injected intraperitoneally twice a week with either vehicle (control and TS) or eldecalcitol at 3.5 or 5 ng for 3 weeks. Grip strength and muscle weights of the gastrocnemius (GAS), tibialis anterior (TA), and soleus (SOL) were determined. Oxidative stress was evaluated by malondialdehyde, superoxide dismutase, glutathione peroxidase, and catalase. Bone microarchitecture was analyzed using microcomputed tomography. The effect of eldecalcitol on C2C12 myoblasts was analyzed by measuring myofibrillar protein MHC and the atrophy markers Atrogin-1 and MuRF-1 using immunofluorescence. The influence of eldecalcitol on NF-κB signaling pathway and vitamin D receptor (VDR) was assessed through immunofluorescence, (co)-immunoprecipitation, and VDR knockdown studies. Eldecalcitol increased grip strength (P < 0.01) and restored muscle loss in GAS, TA, and SOL (P < 0.05 to P < 0.001) induced by TS. An improvement was noted in bone mineral density and bone architecture in the eldecalcitol group. The impaired oxidative defense system was restored by eldecalcitol (P < 0.05 to P < 0.01 vs. TS). Eldecalcitol (10 nM) significantly inhibited the expression of MuRF-1 (P < 0.001) and Atrogin-1 (P < 0.01), increased the diameter of myotubes (P < 0.05), inhibited the expression of P65 and P52 components of NF-κB and P65 nuclear location, thereby inhibiting NF-κB signaling. Eldecalcitol promoted VDR binding to P65 and P52. VDR signaling is required for eldecalcitol-mediated anti-atrophy effects. In conclusion, eldecalcitol exerted its beneficial effects on disuse-induced muscle atrophy via NF-κB inhibition.

Modulation of the vitamin D/vitamin D receptor system in osteoporosis pathogenesis: insights and therapeutic approaches

Osteoporosis is a prevalent bone disorder characterized by low bone mineral density (BMD) and deteriorated bone microarchitecture, leading to an increased risk of fractures. Vitamin D (VD), an essential nutrient for skeletal health, plays a vital role in maintaining bone homeostasis. The biological effects of VD are primarily mediated through the vitamin D receptor (VDR), a nuclear receptor that regulates the transcription of target genes involved in calcium and phosphate metabolism, bone mineralization, and bone remodeling. In this review article, we conduct a thorough literature search of the PubMed and EMBASE databases, spanning from January 2000 to September 2023. Utilizing the keywords "vitamin D," "vitamin D receptor," "osteoporosis," and "therapy," we aim to provide an exhaustive overview of the role of the VD/VDR system in osteoporosis pathogenesis, highlighting the most recent findings in this field. We explore the molecular mechanisms underlying VDR's effects on bone cells, including osteoblasts and osteoclasts, and discuss the impact of VDR polymorphisms on BMD and fracture risk. Additionally, we examine the interplay between VDR and other factors, such as hormonal regulation, genetic variants, and epigenetic modifications, that contribute to osteoporosis susceptibility. The therapeutic implications of targeting the VDR pathway for osteoporosis management are also discussed. By bringing together these diverse aspects, this review enhances our understanding of the VD/VDR system's critical role in the pathogenesis of osteoporosis and highlights its significance as a potential therapeutic target.

Vitamin D receptor gene polymorphisms influence on clinical profile and bone mineral density at different skeletal sites in postmenopausal osteoporotic women

Bone remodeling is marked by bone synthesis and absorption balance, and any altered dynamic in this process leads to osteoporosis (OP). The interaction of hormonal, environmental and genetic factors regulate bone metabolism. Since vitamin D displays a classic role in bone metabolism regulation, acting through vitamin D receptor (VDR), the genetic variants within VDR were the first ones associated with bone density and remodelling. Therefore, we investigated whether three single nucleotide polymorphisms (SNPs) within VDR were associated with OP differential susceptibility and clinical profile from postmenopausal versus healthy women from Northeast Brazil. Genetic association study enrolling 146 postmenopausal osteoporotic women as the patient group and 95 healthy age-matched women as the control group. We assessed three SNPs within VDR (rs11168268, rs1540339 and rs3890733), considering the clinical profile of all patients. Our results showed an association of rs11168268 G/G genotype with higher bone mineral density (BMD) mean for the total hip (A/A = 0.828 ± 0.09; A/G = 0.081 ± 0.13; G/G = 0.876 ± 0.12, p = .039), and the rs3890733 T/T genotype was associated with increased OP risk in patients below 60 years old (odds ratio [OR] = 5.12, 95% confidence interval [CI ]= 1.13-23.27, p = .012). The rs1540339 T/T genotype was associated with protection for individuals with low melanin deposition when compared to the high melanin deposition group (OR = 0.24, 95%CI = 0.06-0.94, p = .029). Additionally, 61% of patients presented deficient vitamin D serum levels. The SNP rs11168268 G/G was associated with a significantly increased mean total hip BMD in patients OP, highlighting this SNP and its relationship with BMD.

Decisive gene strategy on osteoporosis: a comprehensive whole-literature-based approach for conclusive candidate gene targets

Purpose: Previous meta-analyses only examined the association between single gene polymorphisms and osteoporosis; there is no compilation of all gene loci that correlate with osteoporosis in the literature. In this study, we develop a new literature-based approach, a decisive gene strategy (DGS), to examine the sufficiency of the cumulative sample size for each gene locus and to assess whether a definite conclusion of the association between the gene locus and osteoporosis can be drawn.

Methods: The DGS was used to search PubMed, Embase, and Cochrane databases for all meta-analyses that correlated gene polymorphisms with osteoporosis. Trial sequential analysis was employed to examine the sufficiency of the cumulative sample size. Finally, we assessed the importance of gene loci in osteoporosis based on whether there were enough sample sizes and the heterogeneity of the literature with the I² value.

Results: After excluding 169 irrelevant publications, 39 meta-analysis papers were obtained. Among Caucasians, in 17 gene loci, there were eight gene loci (e.g., vitamin D Receptor ApaI rs7975232) with sufficient cumulative sample size to confirm that they were unrelated to the disease. Among Asians, in 15 gene loci, four gene loci that had sufficient sample sizes were risk factors: VDR FokI rs2228570 (odds ratio (OR) = 1.44, 95% confidence interval (CI) = 1.22–1.70), TGF β1 rs1800470 (OR = 1.35, 95% CI = 1.10–1.65), IGF1 rs2288377 (OR = 1.44, 95% CI = 1.28–1.62), and IGF1 rs35767 (OR = 1.20, 95% CI = 1.06–1.36), respectively, whereas one gene locus, ESR2 RsaI rs1256049 (OR = 0.69, 95% CI = 0.59–0.81), was a protective factor.

Conclusions: The DGS successfully identified five gene loci in osteoporosis that will apply to other diseases to find causal genes, which may contribute to further genetic therapy.

High-Throughput Absolute Quantification Sequencing Revealed Osteoporosis-Related Gut Microbiota Alterations in Han Chinese Elderly

Objective

Accumulative evidence suggests that gut microbiota play an important role in bone remodeling and hence bone health maintenance. This study aimed to explore the association of gut microbiota with the risk of osteoporosis and to identify potential disease-related taxa, which may be promising targets in osteoporosis prevention and treatment in the future.

Methods

Absolute quantification 16S ribosomal RNA gene sequencing was used to detect absolute and relative abundances of gut microbiota in 44 patients with osteoporosis and 64 controls. In combination with one of our previous studies, a total of 175 samples were involved in the relative abundance analysis.

Results

Compared with the controls, the patients with osteoporosis had higher absolute and relative abundances of Bacteroidetes phylum, and Bacteroides and Eisenbergiella genera. The absolute abundances of Clostridium_XlVa, Coprococcus, Lactobacillus, and Eggerthella genera increased, and that of the Veillonella genus decreased in the osteoporosis group. As for relative abundance, that of the Parabacteroides and Flavonifractor genera increased, whereas that of the Raoultella genus decreased in the osteoporosis group. Controlling for potential confounders, the associations of Clostridium_XlVa, Coprococcus, and Veillonella genera with the risk of osteoporosis did not maintain significance. Ridge regression analysis suggested that Bacteroides is associated with reduced bone mineral density (BMD) and T-score at lumbar spines, and Anaerovorax is associated with increased BMD at the femoral neck. Functional predictions revealed that 10 Kyoto Encyclopedia of Genes and Genomes pathways were enriched in the osteoporosis group.

Conclusions

Gut microbiota compositions may contribute to the risk of osteoporosis. Several specific taxa and functional pathways are identified to associate with reduced bone density, thus providing epidemiologic evidence for the potential role of aberrant gut microbiota in osteoporosis pathogenesis.

Vitamin D Receptor FokI, ApaI, and TaqI Polymorphisms in Lead Exposed Subjects From Saudi Arabia

Vitamin D receptor (VDR) gene polymorphisms were reported to influence blood lead levels (BLL) and the response of subjects to the symptoms of lead toxicity. However, no studies have been conducted in the Saudi Arabian population which has unique ethnicity and socio-demographic features. This study examined the polymorphisms in exon 2 (allele 1) and intron 8 (allele 2 and allele 3) of VDR gene and their relation to BLLs. As per the CDC guidelines, the recruited lead-exposed workers (N = 130) were categorized to two groups viz., low BLL group (<10 μg/dL) and high BLL group (>10 μg/dL). The low BLL group had a mean BLL of 4.37 μg/dL, while the high BLL group had levels of 18.12 μg/dL (p < 0.001). Overall, the genetic variants, TC and CC in the VDR FokI were significantly associated with a risk of lead toxicity and the allele "C" was a risk factor (p = 0.00026). Furthermore, the TT genotype of VDR ApaI significantly increased the risk of developing lead poisoning (p = 0.0006). The VDR TaqI SNP was not significantly associated with lead toxicity. The highest BLLs for VDR FokI-CC, VDR ApaI-GG, and VDR TaqI-TT genotypes from High BLL group were 18.42, 15.26, and 18.75 μg/dL, respectively. Older age (51-60 years) was found to be a significant confounding factor for BLLs (p = 0.012). Additional studies in larger sample sizes are needed to firmly establish the role of VDR genotypes and genetic susceptibility to lead poisoning.

Correlation analysis between 25-hydroxyvitamin D3, vitamin B12 and vitamin C and endothelial function of patients with CHD

The aim of the study was to investigate the correlation between levels of 25-hydroxyvitamin D3, vitamin B12 and C and endothelial function of patients with coronary heart disease (CHD). Forty patients with CHD diagnosed in Shanghai Tenth People's Hospital from May 2016 to April 2017 were selected as the observation group. A total of 45 healthy individuals were selected as the control group. The participants included 54 males and 31 females. General information was collected. Peripheral serum biochemical indicators, levels of 25-hydroxyvitamin D3, vitamin B12 and C, homocysteine (Hcy), nitric oxide (NO) and endothelial NOS (eNOS) were measured. Arterial lesions detected by coronary angiography were recorded and indexes of observation and control group were compared for the correlation analysis. A proportion of hypertensive patients and their body mass index (BMI) were significantly higher in the observation than in the control group (P<0.05). Levels of 25-hydroxyvitamin D3, vitamin B12 and C in peripheral blood of observation were significantly lower than those of the control group (P<0.05). Compared with the control group, incidence of single-branch lesion and non-lesion rate were significantly lower, but incidence of double- and triple-branch lesions were significantly higher in observation than in control group (P<0.05). In addition, the level of Hcy in the observation group was higher than that in the control group, but levels of NO and eNOS in observation were significantly lower than those in control group (P<0.05. The correlation analysis revealed that 25-hydroxyvitamin D3 (r=0.792, P<0.01), vitamin B12 (r=0.635, P<0.01) and vitamin C (r=0.703, P<0.01) were negatively correlated with serum NO level. Thus, hypertension, BMI, 25-hydroxyvitamin D3, vitamin B12 and C have independent predictive value for coronary endothelial dysfunction (P<0.05). In conclusion, serum levels of 25-hydroxyvitamin D3, vitamin B12 and C are closely related to vascular endothelial dysfunction in patients with CHD and affect the severity of vascular endothelial dysfunction in patients with CHD.

The associations between dietary patterns and bone health, according to the TGF-β1 T869→C polymorphism, in postmenopausal Iranian women

BACKGROUND/OBJECTIVE

Recent studies have shown that dietary variants and genetic variants play a decisive role in the risk of developing osteoporosis. Therefore, the objective of the present study was to examine associations between dietary pattern and bone health, according to the TGF-β1 T869→C polymorphism, in postmenopausal Iranian women.

MATERIALS AND METHODS

In this study, 264 postmenopausal women aged from 46 to 78 years were examined. Body composition was measured by a body composition analyzer and physical activity by the short-form physical activity questionnaire. Bone mineral density was measured by the DEXA method. Dietary patterns were determined using factor analysis on 27 foods groups, employing a valid, reliable 147-item semi-quantitative food frequency questionnaire. The dietary patterns were analyzed by the factor analysis method. Blood samples were taken for measuring blood parameters. DNA samples from participants were genotyped using the RFLP-PCR method.

RESULTS

Three dietary patterns were identified, namely: mediterranean diet, traditional diet, and unhealthy diet-one of which was associated with bone health. Postmenopausal women following a Mediterranean diet had lower weight and central obesity (0.05 > P). Higher adherence to a Mediterranean pattern was positively associated with Z-score L2_L4 lumbar spine (0.05 > P). TGF-β1 T869→C genotypes, after adjustment, were not directly correlated with bone mineral density and body composition (0.05 < P). Moreover, these findings demonstrated that in participants adhering to a Traditional dietary pattern, the C allele carrier group (TC and CC genotypes) had a lower L2_L4 Z-score (P = 0.05).

CONCLUSION

It seems that the mediterranean diet can be a beneficial dietary pattern in the prevention of osteoporosis and obesity in postmenopausal women. Furthermore (probably in the C allele carrier group), lower vitamin D intake, coupled with adherence to a traditional dietary pattern, reduces the deposition of TGF-beta and increases the risk of lumbar spine osteoporosis.

Lack of association between vitamin D receptor genes BsmI as well as ApaI polymorphisms and osteoporosis risk: A pooled analysis on Chinese individuals

BACKGROUND

As for the association between vitamin D receptor (VDR) gene polymorphisms and osteoporosis, the current results have yielded conflicts. Therefore, we performed a pooled analysis based on Chinese individuals to provide comprehensive data on the association between VDR BsmI, ApaI, Tru9I polymorphisms and osteoporosis risk.

METHODS

Studies were identified using PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure and Chinese Biology Medicine databases through to January 2017. Studies were screened according to the predefined inclusion and exclusion criteria. The association between VDR BsmI, ApaI, Tru9I polymorphisms and osteoporosis was evaluated by calculating pooled odds ratios (ORs) based on the individual ORs. The significance of the pooled OR was evaluated by a Z-test. All statistical analyses were conducted using Stata 12.0 software (StataCorp, College Station, TX, USA).

RESULTS

A total of 13 studies with 1141 osteoporosis cases and 1263 controls were included in this meta-analysis. It revealed that VDR Tru9I polymorphism was associated with an increased risk of osteoporosis in a common model (OR = 2.67, CI 95% = 1.59-4.49). No significant association was observed between VDR BsmI, ApaI and osteoporosis.

CONCLUSION

In conclusion, this meta-analysis suggests that VDR Tru9I polymorphism may be associated with osteoporosis risk in Chinese individuals, while BsmI, ApaI polymorphisms might not be a risk factor for osteoporosis.