The importance of the Wnt/β-catenin pathway and LRP5 protein in bone metabolism of postmenopausal women

Clinical and Genetic Features of Chinese Adult Patients With Chronic Non-Bacterial Osteomyelitis: A Single Center Report

Objectives

Chronic non-bacterial osteomyelitis (CNO) is a rare polygenic autoinflammatory bone disease. We aimed to characterize the clinical manifestations and gene variants of Chinese adult patients with CNO.

Methods

By reviewing data of all CNO patients being diagnosed and followed up at the Center for Adult Autoinflammation Diseases, Department of Rheumatology, Peking Union Medical College Hospital, clinical and genetic features of these patients were evaluated and concluded.

Results

The median age of disease onset was 19 (6-64) years old, and adult-onset was observed in 6 (60%) patients. The mean time of diagnosis delay was 92 ± 78 months. The common symptoms were bone pain (10, 100%), fever (9, 90%), and arthritis (6, 60%). In total, there were 54 skeletal lesions, and each patient had no less than 2 lesions. The most frequently affected sites included lower limbs (20.5%), mandible, vertebrae and pelvis (17.5%, separately). Variants of 4 genes were detected in our study including COL1A1, PSTPIP1, LRP5 and CLCN7. In seven patients who were treated with combination therapy containing tumor necrosis factor (TNF) α inhibitors, five (55.6%) had a complete response and 2 (44.4%) had a partial response.

Conclusion

This is the first and largest case series of CNO in the Chinese adult patients. Four novel genetic mutations potentially associated with CNO were identified. Notably, CNO should be considered in the differential diagnosis of adult patients with long disease course and recurrent multifocal osteomyelitis of unknown cause, and these patients might benefit from combination therapy containing TNFα inhibitors.

The genetic polymorphisms of key genes in WNT pathway (LRP5 and AXIN1) was associated with osteoporosis susceptibility in Chinese Han population

BACKGROUND

Genetic factors play a critical role in the pathogenesis of osteoporosis. The imbalance of WNT/β-catenin will cause the occurrence of osteoporosis. LRP5 and AXIN1 play an important role in the classical Wnt/β-catenin signaling pathway. Our study was aimed to determine the association between five candidate single nucleotide polymorphisms (SNPs) of LRP5 or AXIN1 and osteoporosis susceptibility in Chinese Han population.

METHODS

A total of 599 osteoporosis patients and 599 healthy individuals were recruited for this case-control study. Agena MassARRAY was used to genotype SNPs. The association between SNPs and osteoporosis susceptibility in different genetic models was analyzed by PLINK software. We used false-positive report probability (FPRP) analysis to detect whether the positive results were just chance or noteworthy observations. Multifactor dimension reduction (MDR) was used to analyze the interaction of SNP-SNP in the osteoporosis risk. Finally, haplotype analysis was performed by plink1.07 and Haploview software.

RESULTS

We found that LRP5 rs11228240, AXIN1 rs2301522, and rs9921222 were significantly associated with the osteoporosis susceptibility. The results of subgroup analysis showed that LRP5 rs11228240 (protective factor) and AXIN1 rs2301522 (risk factor) were associated with the susceptibility of osteoporosis among participants who were age >60 years, female or BMI ≤ 24; AXIN1 rs9921222 significantly increased the risk of osteoporosis among participants with BMI ≤ 24. The genotype A_rs2301522C_rs9921222 could increase the susceptibility of osteoporosis (p = 0.026). The rs11228219_LPR5, rs11228240 _LPR5, rs2301522_AXIN1, and rs9921222_AXIN1 four-site model was the best model for predicting the osteoporosis risk (test accuracy = 0.541; CVC = 10/10).

CONCLUSIONS

The LRP5-rs11228240, AXIN1-rs2301522, and AXIN1- rs9921222 were associated with osteoporosis susceptibility in Chinese Han population.

Epigallocatechin gallate regulates inflammatory responses and new bone formation through Wnt/β-Catenin/COX-2 pathway in spondyloarthritis

OBJECTIVE

Spondyloarthritis (SpA) is mainly characterized by bone erosion, new bone formation, inflammation and potential disability. Epigallocatechin gallate (EGCG) has been proved to be closely related with the regulation of inflammation and bone metabolism. However, whether EGCG could improve SpA remains unclear.

METHODS

SpA animal model was established using proteoglycan. Cell proliferation were measured by CCK-8 assay. The mRNA expression levels of genes were detected using qRT-PCR, protein levels were assessed via western blotting and immunohistochemistry. ELISA assay was performed to examined the inflammatory cytokine release. Lesions in spine cartilage tissues were observed using hematoxylin-eosin (HE) and Safranin O staining. Alkaline phosphatase (ALP) assay and Alizarin Red S staining was used to investigate osteoblast mineralization.

RESULTS

We found that EGCG could inhibit inflammation and new bone formation in SpA mice. Besides, inflammatory factor expression and osteogenic differentiation in osteoblasts isolated from SpA mice were also decreased by EGCG. Further, EGCG treatment suppressed the activation of Wnt/β-Catenin/COX-2 pathway and the activator of this pathway partially reversed the effects of EGCG on inflammation and osteoblast differentiation.

CONCLUSIONS

EGCG repressed inflammatory responses and new bone formation, and further improved SpA through Wnt/β-Catenin/COX-2 pathway. Our findings may provide a new thought for the prevention and treatment of SpA.

Associations of LRP5 Gene With Bone Mineral Density, Bone Turnover Markers, and Fractures in the Elderly With Osteoporosis

Objective: The study aimed to explore the associations of rs4988300 and rs634008 in the low-density lipoprotein receptor-related protein 5 (LRP5) gene with bone mineral density (BMD), bone turnover markers (BTM), and fractures in elderly patients with osteoporosis (OP). Methods: Our study included 328 unrelated OP patients with or without fractures. Genomic DNA was extracted for genotyping. BTM levels were assessed by electrochemiluminescence (ECL). Dual-energy X-ray absorptiometry (DXA) was employed to measure BMD in the lumbar spine (LS) and proximal femur. Basic features between the OP and fracture groups were analyzed using the t-test. The Chi-square test was performed to analyze the differences in allele and genotype frequencies. The associations of single-nucleotide polymorphisms (SNPs) with BMD and BTM in the subgroups were investigated by the analysis of covariance (ANCOVA) adjusted for confounding factors. Results: In both females and males, individuals with fractures exhibited higher BTM levels and lower BMD values than those with OP (P < 0.05). The allele and genotype frequencies of rs4988300 in the subgroups were significantly different (P < 0.05). In both females and males suffering from OP, participants with rs4988300 GG or rs634008 TT presented lower procollagen I N-terminal propeptide (PINP) levels (P < 0.05). Women with OP carrying rs4988300 GG exhibited lower BMD values at FN and TH (P < 0.05). In both females and males with fractures, individuals carrying rs4988300 GG genotype or rs634008 TT genotype exhibited lower PINP levels and BMD values at FN and TH than those with other genotypes (P < 0.05). Conclusions: Rs4988300 and rs634008 polymorphisms in the LRP5 gene are associated with bone phenotypes in the elderly with OP or fractures.