Osteoporosis prevention--a worthy and achievable strategy

Identification of key variants correlated with susceptibility of primary osteoporosis in the Chinese Han group

BACKGROUND

Primary osteoporosis is a systemic skeletal disease characterized by reduced bone mass and vulnerability to fractures. The genetics of osteoporosis in the Chinese population remain unclear, which hinders the prevention and treatment of osteoporosis in China. This study aimed to explore the susceptibility genes and the roles played by their variants in osteoporosis.

METHODS

Blood samples were collected from 45 osteoporosis patients and 30 healthy individuals, and genome-wide association study was performed on array data. The expression levels of the candidate gene in different genotypes were further determined by using quantitative real-time PCR. Moreover, the differentiation capacity of bone marrow mesenchymal stem cells under different genotypes from osteoporosis patients was investigated.

RESULTS

The most significant variant rs1891632 located in the upstream (918 bp) region of CRB2, which could down-regulate the expression levels of CRB2 in genotype-tissue expression database and played an essential role in the regulation of osteoblastic and osteoclastic differentiation during skeletal development. Another significant variant rs1061657 located within the 3'UTR region of TBX3 gene. We found that the mRNA levels of TBX3 decreased in the bMSCs of old osteoporosis patients. Interestingly, osteoblast differentiation capacity and TBX3 mRNA levels were similar between the young healthy individuals carrying derived and ancestral allele of rs1061657, whereas the differentiation capacity and TBX3 mRNA levels dramatically declined in elderly patients with osteoporosis.

CONCLUSIONS

The variant rs1061657 might affect the osteogenesis of bMSCs in an age-dependent manner and that TBX3 may be a key susceptibility gene for primary osteoporosis. In conclusion, CRB2 and TBX3 may influence the development of osteoporosis; additionally, rs1891632 and rs1061657, as the key variants first reported to be associated with primary osteoporosis, may potentially contribute to predicting the risk of osteoporosis (especially for older individuals) and may serve as therapeutic targets.

Sclerostin as a biomarker of physical exercise in osteoporosis: A narrative review

Osteoporosis, a disease of low bone mass, is characterized by reduced bone mineral density (BMD) through abnormalities in the microarchitecture of bone tissue. It affects both the social and economic areas, therefore it has been considered a lifestyle disease for many years. Bone tissue is a dynamic structure exhibiting sensitivity to various stimuli, including mechanical ones, which are a regulator of tissue sclerostin levels. Sclerostin is a protein involved in bone remodeling, showing an anti-anabolic effect on bone density. Moderate to vigorous physical activity inhibits secretion of this protein and promotes increased bone mineral density. Appropriate exercise has been shown to have an osteogenic effect. The effectiveness of osteogenic training depends on the type, intensity, regularity and frequency of exercise and the number of body parts involved. The greatest osteogenic activity is demonstrated by exercises affecting bone with high ground reaction forces (GRF) and high forces exerted by contracting muscles (JFR). The purpose of this study was to review the literature for the effects of various forms of exercise on sclerostin secretion.

The effects and mechanism of paeoniflorin in promoting osteogenic differentiation of MC3T3-E1

Background

The incidence of osteoporosis and osteoporotic fractures is increasing every year. Traditional Chinese Medicine (TCM) can shed new light on the treatment of osteoporosis. This study aimed to explore the role and mechanism of paeoniflorin in promoting osteogenic differentiation of an osteoblast precursor cell line (MC3T3-E1).

Methods

MC3T3-E1 cells were cultured in osteogenic induction medium (OIM) and OIM combined with different concentrations of paeoniflorin. The optimal dose of paeoniflorin was assessed by a cell counting kit-8 (CCK-8) assay. Then, alkaline phosphatase (ALP) and Alizarin Red S (ARS) staining were performed to assess the osteogenic capacity of paeoniflorin. The transcription of osteogenic genes and the expression of osteogenic proteins were assessed by RT-PCR and Western blotting, respectively. The transcription of Wnt/β-catenin signaling pathway genes and proteins was assessed by RT-PCR and Western blotting, respectively. Finally, Dickkopf-1 (DKK-1), a Wnt/β-catenin signaling pathway inhibitor, was used to identify whether the Wnt/β-catenin signaling pathway was involved in the osteogenic differentiation of paeoniflorin. Osteoclastogenesis in RAW264.7 cells was identified by tartrate-resistant acid phosphatase (TRAP) staining.

Results

At concentrations ranging from 0.1 to 100 μM, paeoniflorin was not cytotoxic to MC3T3-E1 cells. Paeoniflorin significantly increased the osteogenic differentiation of MC3T3-E1 cells in a dose-dependent manner. Moreover, paeoniflorin significantly increased osteogenic differentiation gene and protein expression. Through bioinformatic analysis, paeoniflorin-affected genes were found to be involved in different signaling pathways, such as the Wnt/β-catenin signaling pathway. Paeoniflorin enhanced β-catenin and CyclinD1 expression compared with that of the control groups. DKK-1 partially reversed the promoting effects of paeoniflorin in promoting osteogenic differentiation of MC3T3-E1 cells. Moreover, paeoniflorin inhibited the osteoclastogenesis of RAW264.7 cells.

Conclusion

Paeoniflorin promotes osteogenic differentiation in MC3T3-E1 cells by regulating the Wnt/β-catenin pathway. Paeoniflorin is a potential therapeutic agent for the treatment of osteoporosis.

Different Training Durations and Frequencies of Tai Chi for Bone Mineral Density Improvement: A Systematic Review and Meta-Analysis

Objective

Tai Chi shows potential as a safe and cost-effective intervention to improve bone mineral density (BMD). However, the various effects caused by different training durations and frequencies have not been evaluated. This updated systematic review aims to explore the effectiveness of Tai Chi in attenuating bone mineral density loss based on different training durations and frequencies.

Methods

We conducted an extensive database search in Cochrane Central Register of Controlled Trials, PubMed, EMBASE, Web of Science, Chinese Biomedical Literature Database, China Knowledge Resource Integrated Database, Wanfang Data, and China Science and Technology Journal Database on randomized controlled trials that examined Tai Chi for BMD improvement. Two reviewers independently performed data screening and extraction. Study quality was evaluated using the Cochrane Handbook for Systematic Reviews of Interventions.

Results

A total of 23 randomized controlled trials involving 1582 patients were identified. The aggregated results have shown significant benefits in favor of Tai Chi on BMD improvement in the lumbar spine (SMD = 0.36, 95% [0.13, 0.59], P=0.002), femoral neck (SMD = 0.40, 95% [0.16, 0.63], P=0.0009), femoral trochanter (SMD = 0.43, 95% CI [0.20, 0.66], P=0.0002), and Ward's triangle (SMD = 0.31, 95% [0.15, 0.48], P=0.002). Such favorable benefits in Tai Chi can only be seen when compared with the nonexercise group, and Tai Chi showed no significant improvement in BMD change when compared with other exercises group. Subgroup analyses showed various effects of BMD improvement based on different training durations and frequencies of Tai Chi. Tai Chi is effective in attenuating BMD loss with an intervention frequency of >4 days/week in the lumbar spine, with an intervention frequency of >4 days/week or an intervention duration of >10 months in the femoral neck, and with an intervention duration of >10 months or a frequency of ≤4 days/week in Ward's triangle.

Conclusions

The results demonstrated that Tai Chi may have benefits in attenuating BMD loss. Different training durations and frequencies may result in variable effectiveness. Researchers should focus more on the training durations and frequencies of Tai Chi so that a more definitive claim can be made regarding the beneficial effects for BMD improvement.