Association betweenGREM2 gene polymorphism with osteoporosis and osteopenia in postmenopausal women

Comprehensive analysis of circRNA expression profiles in postmenopausal women differing in bone mineral density

Postmenopausal osteoporosis (PMOP) seriously endangers the bone health of older women. Although there are currently indicators to diagnose PMOP, early diagnostic biomarkers are lacking. Circular ribonucleic acid (circRNA) has a stable structure, regulates gene expression, participates in the pathological process of disease, and has the potential to become a biomarker. The purpose of this study was to investigate circRNAs that could be used to predict patients with early PMOP. Ribonucleic acid (RNA) sequencing was performed on peripheral blood leukocytes from 15 female patients to identify differential circRNAs between different groups. Using bioinformatics analysis, enrichment analysis was performed to discover relevant functions and pathways. CircRNA-micro ribonucleic acid (miRNA) interaction analysis and messenger ribonucleic acid (mRNA) prediction and network construction help us to understand the relationship between circRNA, miRNA, and mRNA. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the gene expression of candidate circRNAs. We screened out 2 co-expressed differential circRNAs, namely hsa_circ_0060849 and hsa_circ_0001394. By analyzing the regulatory network, a total of 54 miRNAs and 57 osteoporosis-related mRNAs were identified, which, as potential downstream target genes of hsa_circ_0060849 and hsa_circ_0001394, may play a key role in the occurrence and development of PMOP. The occurrence and development of PMOP is regulated by circRNAs, and hsa_circ_0060849 and hsa_circ_0001394 can be used as new diagnostic markers and therapeutic targets for early PMOP.

The relationship between FOSB and SOCS3 gene polymorphisms and the susceptibility to periodontitis and osteopenia in the Chinese population

The aim is to analyze the relationship and significance of the FOS, FOSB, Suppressors of cytokine signaling (SOCS), and hypoxia-inducible factor 1 (HIF1) gene loci and their polymorphisms with periodontitis and osteopenia in the Chinese population. In this case-control study, data on questionnaires, periodontal examination, bone mineral density, and FOS, FOSB, SOCS3, and HIF1 gene loci and their polymorphisms were obtained from 474 participants. The data were analyzed using the analysis of variance, Kruskal-Wallis test, χ² test, and logistic regression. The incidence of osteopenia was significantly increased in patients with periodontitis compared to controls (58.6 vs. 34.4%, P < 0.001). Accordingly, the risk was increased 2.21-fold compared with controls (95% CI 2.09-4.95). Osteopenia patients had a significantly higher risk of periodontitis than patients with normal bone density (OR = 3.22, 95% CI 2.09-4.94). There were significant positive associations between FOSB and SOCS3 polymorphisms and periodontitis and osteopenia susceptibility. Individuals carrying the G/G genotype of the FOSB gene rs708905 locus had an increased risk of periodontitis (OR = 5.06, 95% CI 2.36-10.86) and osteopenia (OR = 3.26, 95% CI 1.34-7.96). Compared with the C/C genotype, the A/A genotype of the FOSB rs8105114 locus was associated with a significantly higher risk of periodontitis (OR = 2.14, 95% CI 1.02-4.53) and osteopenia (OR = 2.85, 95% CI 1.12-7.22). Compared with the A/A genotype, the risk of periodontitis in the G/G genotype of the SOCS3 rs7207782 locus was increased 3.10-fold (P < 0.001), and the risk of osteopenia was increased 2.01-fold (P = 0.023). There was a bidirectional relationship between periodontitis and osteopenia. The rs708905 G/G and rs8105114 A/A genotypes of FOSB and the rs7207782 G/G genotype of SOCS3 were risk factors for both periodontitis and osteopenia in the Chinese population, which could increase knowledge about disease‑specific and cross‑disease genetic pattern.

Integrative Analysis of LGR5/6 Gene Variants, Gut Microbiota Composition and Osteoporosis Risk in Elderly Population

Objective: This study aimed to explore the relationships between the common variants of R-spondin/Wnt signaling genes, gut microbiota composition, and osteoporosis (OP) risk in elderly Chinese Han population.

Design: Dual-energy X-ray absorptiometry was used to obtain the OP-associated measurements at multiple skeleton sites among all 1,168 participants. Genotyping data was obtained by using the next-generation sequencing in the discovery stage (n = 400, 228 OP patients) and SNPscan technology in the replication stage (n = 768, 356 OP patients). Bioinformatic analysis was performed to provide more evidence for the genotype-OP associations. The 16S ribosomal RNA gene high-throughput sequencing technology was adopted to explore OP-associated gut microbiota variations.

Results: The genetic variants of rs10920362 in the LGR6 gene (P-FDR = 1.19 × 10^–6) and rs11178860 in the LGR5 gene (P-FDR = 1.51 × 10^–4) were found to associate with OP risk significantly. Several microbial taxa were associated with the BMDs and T-scores at multiple skeleton sites. The associations between rs10920362 and BMD-associated microbiota maintained significance after adjusting confounders. The rs10920362 CT/TT genotype associated with a decreased relative abundance of Actinobacteria (β = −1.32, P < 0.001), Bifidobacteriaceae (β = −1.70, P < 0.001), and Bifidobacterium (β = −1.70, P < 0.001) compared to the CC genotype.

Conclusion: Our findings suggested that the variants loci of LGR6 may be associate with OP pathogenesis via gut microbiota modifications. The relationship between host genetics and gut microbiome provides new perspectives about OP prevention and treatment.

Deletion of Gremlin-2 alters estrous cyclicity and disrupts female fertility in mice

Members of the differential screening-selected gene aberrative in neuroblastoma (DAN) protein family are developmentally conserved extracellular binding proteins that antagonize bone morphogenetic protein (BMP) signaling. This protein family includes the Gremlin proteins, GREM1 and GREM2, which have key functions during embryogenesis and adult physiology. While BMPs play essential roles in ovarian follicle development, the role of the DAN family in female reproductive physiology is less understood. We generated mice null for Grem2 to determine its role in female reproduction in addition to screening patients with primary ovarian insufficiency for variants in GREM2. Grem2-/- mice are viable, but female Grem2-/- mice have diminished fecundity and irregular estrous cycles. This is accompanied by significantly reduced production of ovarian anti-Müllerian hormone (AMH) from small growing follicles, leading to a significant decrease in serum AMH. Surprisingly, as AMH is a well-established marker of the ovarian reserve, morphometric analysis of ovarian follicles showed maintenance of primordial follicles in Grem2-/- mice like wild type littermates. While Grem2 mRNA transcripts were not detected in the pituitary, Grem2 is expressed in hypothalami of wild type female mice, suggesting the potential for dysfunction in multiple tissues composing the hypothalamic-pituitary-ovarian axis that contribute to the subfertility phenotype. Additionally, screening 106 women with primary ovarian insufficiency identified one individual with a heterozygous variant in GREM2 that lies within the predicted BMP-GREM2 interface. In total, these data suggest Grem2 is necessary for female fecundity by playing a novel role in regulating the HPO axis and contributing to female reproductive disease.

Association of Gremlin-2 gene polymorphisms with osteoporosis risk in Chinese postmenopausal women

The Gremlin-2 (GREM2) plays crucial roles in modulating bone homeostasis through the bone morphogenetic protein-2 pathway. However, GREM2 gene variants in osteoporosis were less frequent in a Chinese population. Therefore, the present study recruited 310 patients with osteoporosis and 339 healthy postmenopausal women to assess the correlation of GREM2 gene polymorphisms with the risk of osteoporosis. Polymerase chain reaction (PCR) and Sanger sequencing were utilized to genotype samples. The results showed that GREM2 gene rs4454537, not rs11588607, polymorphism was significantly associated with an increased risk of osteoporosis in postmenopausal women. Moreover, stratified analyses indicated a significant association between rs4454537 polymorphisms and body mass index of <25 kg/m². Additionally, the association between GREM2 rs4454537 polymorphism and clinical characteristics was assessed, which showed that this locus decreased the bone mineral density (BMD) in postmenopausal osteoporotic individuals. Furthermore, individuals with CC genotype appeared to have a higher GREM2 expression compared with those bearing the TT genotype of rs4454537 polymorphism. However, the genotype distribution of rs4454537 polymorphism showed no statistical difference between osteoporotic patients as a function of fracture status. In summary, GREM2 rs4454537 polymorphism decreases BMD and increases osteoporotic risk in postmenopausal women.

[Simvastatin promotes murine osteoclasts apoptosis in vitro through NFATc1 pathway]

OBJECTIVE

To explore the mechanism by which simvastatin (SIM) regulates osteoclast apoptosis.

METHODS

Murine macrophage RAW264.7 cells were divided into 5 groups, namely group A (control group), group B (sRANKL+ M-CSF), group C (SIM+sRANKL+M-CSF), group D (VIVIT peptide+sRANKL+ M-CSF), and group E (SIM+VIVIT peptide+sRANKL+M-CSF). WST-1 assay was used to assess the effects of simvastatin on the proliferation activity of the osteoclasts, and flow cytometry was performed to analyze the effects of SIM and VIVIVIT peptide (a NFATc1 pathway inhibitor) on apoptosis of the osteoclasts. The translocation of NFATc1 into the nucleus was investigated using immunofluorescence assay, and Western blotting was employed to assess the effect of SIM on the phosphorylation of NFATc1 in the nucleus.

RESULTS

WST-1 assay showed that SIM (1×10^-6 mol/L) treatment for 24 and 48 h significantly inhibited the proliferation of the osteoclasts (P=0.039 and 0.022, respectively). Compared with the control group, the SIM-treated osteoclasts exhibited significantly reduced cell percentage in G0/G1 phase (P=0.041) and increased cells in sub-G1 phase (P=0.028) with obvious cell apoptosis. DAPI staining and flow cytometry showed that both SIM and VIVIVIT peptide alone significantly promoted osteoclast apoptosis (P=0.002 and 0.015, respectively), and their combination produced a similar pro-apoptosis effect (P=0.08). Immunofluorescence and Western blotting showed that SIM significantly inhibited the intranuclear translocation of NFATc1 and the phosphorylation of NFATc1 pathway protein (P=0.013).

CONCLUSIONS

SIM promotes osteoclast apoptosis through NFATc1 signaling pathway.

Denosumab effects on serum levels of the bone morphogenetic proteins antagonist noggin in patients with transfusion-dependent thalassemia and osteoporosis

INTRODUCTION

Noggin is an antagonist of bone morphogenetic proteins (BMPs) and has a strong effect on osteogenesis. Osteoporosis is a common complication of transfusion dependent beta-thalassemia (TDT) and denosumab has been recently emerged as a promising therapeutic option. This was a post hoc investigation of serum noggin levels among TDT patients with osteoporosis who participated in a randomized, placebo-control, phase 2b study.

METHODS

Patients received either 60 mg denosumab (n = 32) or placebo (n = 31) every 6 months for 12 months. Noggin was measured, for the first time in thalassemia patients, at baseline and at 12 months, using a recently developed high sensitivity fluorescent immunoassay.

RESULTS

Both groups showed a significant increase in noggin serum levels (denosumab p < 0.001; placebo p < 0.0001). Interestingly, the increase was higher in the placebo group. Furthermore, we observed a strong correlation between noggin and wrist bone mineral density (r = -0.641, p = 0.002) only in the denosumab group.

CONCLUSION

In conclusion, higher noggin levels reflected more BMP inhibition, since our assay detects free bioactive noggin, which in turn impaired bone formation in placebo group. Therefore, denosumab possibly regulates noggin and favours bone turnover in TDT patients with osteoporosis through a novel mechanism of action.