Influence of vitamin D and estrogen receptor gene polymorphisms on calcium absorption: BsmI predicts a greater decrease during energy restriction

Modulation of Osteogenic Differentiation by CYBB in Osteoporotic Models

Osteoporosis (OP) is a prevalent systemic skeletal disease characterized by increased bone fragility and fracture risk. Identifying factors that influence osteogenic differentiation in OP is crucial. We screened genes associated with OP from the Gene Expression Omnibus (GEO) database and constructed a weighted correlation network analysis (WGCNA) to identify hub genes, validating our findings in external and clinical cohorts. Various experiments assessed the proliferation, apoptosis, and osteogenic differentiation abilities of bone marrow mesenchymal stem cells (BMSCs) following CYBB knockdown. We established a postmenopausal OP model in rats through bilateral ovariectomy (OVX) and evaluated OP severity using three-dimensional computed tomography (3D-CT) and H&E staining. Differential gene expression analysis revealed that CYBB was significantly upregulated in OP, with the highest area under the curve (AUC) among differentially expressed genes (DEGs). Notably, CYBB expression in BMSCs decreased over time. Knockdown of CYBB promoted BMSC proliferation and reduced apoptosis, as demonstrated by Alizarin red and ALP staining, which indicated enhanced osteogenic differentiation. Markers such as RUNX1, RUNX2, ALP, secreted phosphoprotein 1 (SPP1), and bone sialoprotein (BSP) were upregulated post-knockdown. In vivo, CYBB knockdown improved bone mineral density (BMD), relative bone volume fraction (BV/TV), and trabecular number (Tb.N). In conclusion, CYBB influences OP progression by modulating bone formation.

Bone Fracture Incidence in Postmenopausal Women: Results of a 10 Year Follow Up in a RAC-OST-POL Study of rs1544410, rs7975232 and rs731236 Polymorphisms

BACKGROUND

The clinical significance of the genetic influence of vitamin D receptor polymorphisms has still not been well-analyzed.

OBJECTIVES

To verify whether rs1544410, rs7975232 and rs731236 polymorphisms are associated with a higher 10-year fracture risk in postmenopausal women.

METHODS

The study group was a subset of a pre-defined population as part of the broader epidemiological research called the RAC-OST-POL Study and consisted of 358 postmenopausal women, chosen randomly from Racibórz (Poland) inhabitants (mean baseline age 65 ± 6.9 years, BMI 31.2 ± 5.5 kg/m2). From all participants' medical history, data concerning co-morbidities, fracture history, the medication used, parental history of bone fractures, cigarettes and alcohol use were taken at baseline. Moreover, rs1544410, rs7975232 and rs731236 polymorphisms were analyzed. Next, over the following 10 years, participants were contacted once a year and questioned concerning new fractures events and their circumstances.

RESULTS

We did not find statistically significant main effects on the fracture incidence of single-polymorphism variants. However, there were some significant findings dependent on the co-existence of these polymorphisms and medical factors. Women with a positive history of parental fracture and configuration of CC rs7975232, AA rs731236 and CC rs1544410 had a higher fracture incidence. The risk of bone fracture was also significantly higher in the group of heterozygotes of AC rs7975232 if their BMI value was in the categories of normal weight or overweight, or if they were treated with calcium or vitamin D.

CONCLUSIONS

Polymorphisms of rs1544410, rs7975232 and rs731236 are connected with the fracture incidence in postmenopausal women. Nevertheless, its influence should be considered with co-existing clinical factors, especially paternal fracture history, prior fracture, BMI value, any osteoporotic treatment or calcium/vit. D supplementation.

Effect of Cdx2 Polymorphism on the Relationship between Dietary Calcium Intake and Peak Bone Mass in Young Japanese Women

Studies investigating the effect of the caudal-type homeobox protein 2 (Cdx2) polymorphism in the vitamin D receptor gene and calcium intake on bone mass have shown inconsistent results. This study investigated whether the effect of calcium intake on peak bone mass is affected by Cdx2 polymorphism in young Japanese women. A cross-sectional study of 500 young women was conducted. Dietary intake was assessed by the Food Frequency Questionnaire. The osteo sono-assessment index (OSI), assessed by the qualitative ultrasound method, was used as a bone mass index. The subjects were divided into two groups by the median calcium intake. The OSI was not different among Cdx2 genotypes and between calcium groups (p = 0.960, p = 0.191, respectively). The interaction between calcium and Cdx2 genotypes on the OSI approached significance (GG versus GA and AA genotypes, p = 0.092). The difference in the OSI between calcium groups was significant in the GG genotype (p = 0.028), but not in the GA or AA genotypes (p = 0.501, p = 0.306, respectively). Adjustment for covariates (body mass index and physical activity) did not change the results. In conclusion, the relationship between dietary calcium intake and peak bone mass may vary according to Cdx2 polymorphism.

An insight into the paradigms of osteoporosis: From genetics to biomechanics

Considered as one of the major epidemics of the 21st century, osteoporosis affects approximately 200 million people globally, with significant worldwide impact on rates of morbidity and mortality and massive socioeconomic burdens. Mainly characterized by decreased bone mineral density (BMD) and increased risk of bone fragility/deterioration, this devastating silent epidemic typically has no symptoms until a fracture occurs. The multifactorial disease, osteoporosis is instigated by complex interactions between genetic, metabolic and environmental factors, with severe impact on the biomechanics of the musculoskeletal system. This article provides a review of the epidemiology, genetic and biomechanical aspects of primary osteoporosis. The review begins with a summary of the epidemiology and global prevalence of osteoporosis. Sections 1 and 2 discuss the genetic associations and molecular signaling pathways involved in normal and pathological osteogenesis while Section 3 explores the biomechanics of osteoporosis and its quantitative damaging effects on critical bone mechanical properties, and associated bone remodeling. Overall, this review summarizes the recent findings about osteoporosis and emphasizes the importance of an integrative holistic approach in investigating osteoporosis towards providing better informed, more effective preventive and treatment modalities. Importantly, this work also explores the limited available literature on the various aspects of osteoporosis in the United Arab Emirates (UAE), Gulf Cooperation Council (GCC), and Middle East despite its alarming prevalence in the region, and highlights the need for further research and studies taking into consideration the importance of the vitamin D receptor (VDR) gene influencing the development of osteoporosis.

Association between polymorphisms in vitamin D receptor gene and adolescent idiopathic scoliosis: a meta-analysis

PURPOSE

This meta-analysis was performed to clarify whether the two single nucleotide polymorphisms (ApaI and BsmI) in vitamin D receptor (VDR) gene conferred susceptibility to adolescent idiopathic scoliosis (AIS).

METHODS

A comprehensive literature search in five online databases (PubMed, EMBASE, ISI Web of Science, CNKI, and Wanfang) was performed to identify studies that analyzed the association between VDR gene polymorphisms and risk of AIS. Observational studies met the predetermined inclusion criteria were selected for meta-analysis. The most appropriate genetic model was identified using a genetic model-free approach. Meta-analysis was performed using RevMan 5.3 software.

RESULTS

Five eligible studies were included in this meta-analysis, which involved a total of 717 cases and 554 controls. A statistically significant association was observed between BsmI polymorphism and AIS (OR 1.90, 95% CI 1.32, 2.62). In subgroup analysis by ethnicity, the association between BsmI polymorphism and AIS was significant in Asians (OR 2.06, 95% CI 1.56, 2.73) but not in Caucasians (OR 0.70, 95% CI 0.23, 2.19). However, the ApaI polymorphism was not associated with AIS. Moreover, no evidence of association between BMD and the two VDR gene polymorphisms was detected.

CONCLUSIONS

Meta-analysis of existing data suggested that BsmI was associated with increased risk of AIS in Asian populations. Nevertheless, further studies with rigorous design and more ethnic groups are encouraged to validate our findings. These slides can be retrieved under Electronic Supplementary Material.

Newly Developed Rat Model of Chronic Kidney Disease-Mineral Bone Disorder

Aim: Chronic kidney disease–mineral bone disorder (CKD–MBD) is associated with all-cause and cardiovascular morbidity and mortality in patients with CKD. Thus, elucidating its pathophysiological mechanisms is essential for improving the prognosis. We evaluated characteristics of CKD–MBD in a newly developed CKD rat model.

Methods: We used male Sprague–Dawley (SD) rats and spontaneously diabetic Torii (SDT) rats, which are used as models for nonobese type 2 diabetes. CKD was induced by 5/6 nephrectomy (Nx). At 10 weeks, the rats were classified into six groups and administered with a vehicle or a low- or high-dose paricalcitol thrice a week. At 20 weeks, the rats were sacrificed; blood and urinary biochemical analyses and histological analysis of the aorta were performed.

Results: At 20 weeks, hemoglobin A1c (HbA1c) levels, blood pressure, and renal function were not significantly different among the six groups. Serum calcium and phosphate levels tended to be higher in SDT-Nx rats than in SD-Nx rats. The urinary excretion of calcium and phosphate was significantly greater in SDT-Nx rats than in SD-Nx rats. After administering paricalcitol, serum parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) levels were significantly higher in SDT-Nx rats than in SD-Nx rats. The degree of aortic calcification was significantly more severe and the aortic calcium content was significantly greater in SDT-Nx rats than in SD-Nx rats.

Conclusions: We suggest that our new CKD rat model using SDT rats represents a useful CKD–MBD model, and this model was greatly influenced by paricalcitol administration. Further studies are needed to clarify the detailed mechanisms underlying this model.

The relationship between vitamin D receptor (VDR) polymorphism and the occurrence of osteoporosis in menopausal Iranian women

BACKGROUND

Osteoporosis, a multifactorial disease with reduced bone mineral density which increases the probability of bone fractures, is caused by calcium deficiency, and its incidence increases with age. It has been determined that mutations in functional regions of vitamin D receptor gene will affect the metabolism of minerals especially calcium and, therefore, bone density. The present study evaluates the relation between vitamin D receptor polymorphisms, TaqI (rs731236) and ApaI (rs7975232), and osteoporosis in menopausal Azari women in Zanjan province.

MATERIALS AND METHODS

This case-control study has been conducted on 50 menopausal women suffering from osteoporosis and 50 menopausal women who did not suffer from osteoporosis in Zanjan province. The diagnosis of osteoporosis was confirmed using DEXA instrument. Peripheral blood was collected from the subjects and controls to extract DNA and assess the ApaI and TaqI polymorphisms using PCR-RFLP method. The results were interpreted using independent T-test, chi-square, and Pearson correlation coefficient with a p-value less than 0.05.

RESULTS

There was not a significant difference between the frequency of ApaI (AA/Aa/aa) and TaqI (TT/Tt/tt) genotypes in cases (mean age 68.72) and controls (mean age 64.7) (p=0.37 and p=0.64, respectively). In addition, ApaI/TaqI allele haplotype in osteoporotic population showed non-significant relation (p value=0.563) compared with the control group.

DISCUSSION AND CONCLUSION

The relationship between the genotypes and osteoporosis, cancers, and mineral metabolism disorders has been studied for a long time. Although there has been a significant relation between the aforementioned genotypes and osteoporosis or reduced mineral density-related bone fractures in some studied, some other studies have opposing results. Therefore, it is only possible to reach an acceptable conclusion by studying the haplotype of the polymorphisms in subjects.