[Osteocalcin, a key molecule for bone endocrine functions]

A natural agent, 5-deoxycajanin, mitigates estrogen-deficiency bone loss via modulating osteoclast-osteoblast homeostasis

Hyperactive osteoclasts and hypoactive osteoblasts usually result in osteolytic conditions such as estrogen-deficiency bone loss. Few natural compounds that both attenuating bone resorption and enhancing bone formation could exert effects on this imbalance. 5-Deoxycajanin (5-D), an isoflavonoid extracted from Cajan leaf with estrogen-like properties, were found to have beneficial pharmacological effects on rebalancing the activities of osteoclasts and osteoblasts. This study revealed that 5-D at the same concentration could inhibit osteoclastogenesis of BMMs and promoted osteoblast differentiation of BMSCs. 5-D not only attenuated the fluorescent formation of RANKL-induced F-actin belts and NFATc1, but also activated ALP and RUNX2 expressions. As to downstream factor expressions, 5-D could block osteoclast-specific genes and proteins including NFATc1 and CTSK, while increased osteogenic genes and proteins including OPG and OCN, as confirmed by Real-time PCR and Western Blotting. Additionally, the network pharmacology and molecular docking identified the involvement of 5-D in the MIF and MAPK signaling pathways and the stable binding between 5-D and MAPK2K1. Further Western blot studies showed that 5-D decreased the phosphorylation of p38 and ERK in osteoclasts, but promoted these phosphorylations in osteoblasts. In a female C57BL/6J mouse model of estrogen deficiency-induced bone loss, 5-D demonstrated efficacy in enhancing BMD through attenuating osteoclast activities and promoting osteogenesis. These results underscore the potential application of 5-D on treating osteolysis resulting from hyperactive osteoclasts and hypoactive osteoblasts, shedding light on modulating osteoclast-osteoblast homeostasis.

Diagnosis of Low Bone Mass Density: Serological versus Radiological Methods

Context

Bone remodeling comprises balanced coupling of bone formation and resorption, and low bone mineral density (BMD) demonstrates high rates of bone resorption. Osteoporosis is a chronic asymptomatic disease with fragile bones and impending risk of fractures mediated by minor trauma. Whereas bone mineralization and integrity are determined by calcium and vitamin D, specific serum markers such as bone specific alkaline phosphatase (ALP) and osteocalcin (OC) play a vital role in bone formation.

Materials and Methods

Serum calcium, vitamin D, ALP, and OC levels were measured in 2,145 Saudi students aged 18–22 years at Umm Al-Qura University. The BMD was measured by dual-energy X-ray absorptiometry (DEXA), and the findings were statistically evaluated. The following statistics were utilized in the analysis: the SPSS software was used to record, tabulate, and statistically evaluate the results.

Results

Low BMD cases accounted for 27.46% of all cases investigated, with considerably higher serum calcium, bone-specific ALP, and OC levels compared to control cases, but significantly lower serum vitamin D levels. In low BMD instances, there was no association between serum markers and DEXA findings.

Conclusion

Serum indicators by themselves may be useful for screening and predicting patients at risk of osteoporosis, as well as assessing treatment response. The combination of serum markers and DEXA measures is more effective in detecting low BMD.

Enhanced migration and adhesion of peripheral blood neutrophils from SAPHO patients revealed by RNA-Seq

Background

SAPHO syndrome is a rare disease characterized by inflammatory lesions on skin and bones. Diversified manifestation and inadequate understanding of etiology has limited its diagnosis and treatment. The co-occurrence of other immune-mediated diseases strongly suggests an involvement of autoimmunity in SAPHO syndrome. However, the role of the largest population of circulating immune cells, neutrophils, is still not well explored. In this study, we performed RNA sequencing to profile the mRNA expression of neutrophils purified from peripheral blood of SAPHO patients to identify key genes associated with SAPHO syndrome, trying to find new functional molecules or biomarkers for this rare disease.

Results

A total of 442 differentially expressed genes were identified (p < 0.05, fold change > 2), in which 294 genes were upregulated and 148 genes were downregulated. Five differentially expressed genes of interest were verified by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR), among which S100A12 was upregulated and positively related to high-sensitivity C-reactive protein (hsCRP), while the downregulated gene MYADM was positively related to osteocalcin. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that differentially expressed genes were enriched in “systemic lupus erythematosus” and “ECM-receptor interaction”. Gene ontology (GO) enrichment showed that differentially expressed genes may participate in biological processes such as “cell migration” and “cell adhesion”.

Conclusions

In conclusion, this study provides a first insight into transcriptome characteristics of SAPHO syndrome, indicating an over-active neutrophil recruitment in patients and possibly suggesting molecular candidates for further study on diagnosis and pathology of this disease.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1169-3) contains supplementary material, which is available to authorized users.