[The role of semaphorin 4D in the mechanism of bisphosphonate-related osteonecrosis of the jaw in rats]

PURPOSE

To study the expression level of semaphorin 4D (Sema4D) in bisphosphonate-related osteonecrosis of the jaw (BRONJ) and to explore its possible role in the occurrence of BRONJ.

METHODS

BRONJ-like rat model was established by intraperitoneal injection of zoledronic acid assisted with tooth extraction. The maxillary specimens were extracted for imaging and histological examination, and bone marrow mononuclear cells(BMMs) and bone marrow mesenchymal stem cells(BMSCs) of each group were obtained in vitro for co-culture. Trap staining and counting were performed on monocytes after osteoclast induction. RAW264.7 cells were induced by osteoclast orientation under bisphosphonates(BPs) environment, and Sema4D expression was detected. Similarly, MC3T3-E1 cells and BMSCs were induced to osteogenic orientation in vitro, and the expression level of osteogenic and osteoclastic related genes ALP, Runx2, and RANKL was detected under the intervention of BPs, Sema4D and Sema4D antibody. Statistical analysis of the data was performed using GraphPad Prism 8.0 software.

RESULTS

BRONJ-like rat model was successfully constructed. Two weeks after tooth extraction, the healing of the tooth extraction wound in the experimental group was significantly limited, and the tooth extraction wound was exposed. H-E staining results showed that regeneration of new bone in the extraction socket of the experimental group was significantly restricted, dead bone was formed, and the healing of the soft tissue was limited. The results of trap staining showed that the number of osteoclasts in the experimental group was significantly less than that in the control group. Micro-CT results showed that bone mineral density and bone volume fraction in the extraction socket of the experimental group were significantly lower than those of the control group. Immunohistochemical results showed that compared with the control group, the expression level of Sema4D in the experimental group was significantly increased. In vitro studies showed that compared with the control group, the osteoclast induction of BMMs in the experimental group was significantly lower than that in the control group. BMSCs in the experimental group significantly reduced the induction of osteoclasts. Osteoclastic induction experiments revealed that bisphosphonates could effectively inhibit the formation of osteoclasts, and the expression of Sema4D was significantly reduced. Osteogenic induction experiment found that Sema4D significantly reduced the expression of Runx2 and RANKL genes in osteoblasts, while the expression of ALP gene decreased and the expression of RANKL up-regulated after adding Sema4D antibody.

CONCLUSIONS

BPs can interfere with normal bone healing time by up-regulating the expression of Sema4D in tissues, leading to coupling disorder between osteoclasts and osteoblasts with inhibition of the maturation of osteoclasts, thereby inhibiting the growth of osteoblasts. Differentiation and expression of related osteogenic factors mediate the development of BRONJ.

Analysis of the effect of zoledronic acid on gene differences in rat jaw

BACKGROUND

With the widespread use of bisphosphonates, there are more and more complications about bisphosphonates, bisphosphonate-related osteonecrosis of the jaw is one.In the past ten years, there have been many studies on the mechanism of bisphosphonate associated jaw necrosis.

OBJECTIVE

To investigate the influence and analysis of zoledronic acid on gene differences in rat jaw.

METHODS

Six Sprague-Dawley female rats were randomly divided into control group (n = 3) and experimental group (n = 3). The experimental group received zoledronic acid injection for 12 weeks (dose of 0.2 mg / kg, 3 times a week).Control groups were injected with normal saline for 12 weeks. All rats were subjected to left mandibular first molar extraction 12 weeks later.After 8 weeks of tooth extraction, all rats were sacrificed and the mandible was removed.RNA-seq was used to analyze differential gene changes in all mandibles. Bioinformatics analysis of differential genes.

RESULTS

Compared with the two rat groups, there were 2,830 different genes, including 1,001 upregulated genes and 1,829 down-regulated genes. Gene Ontology analysis revealed that the upregulated genes were mainly associated with immune-related pathways. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that Hedgehog signaling pathway, Notch signaling pathway and Hippo signaling pathway were associated with upregulated genes. After the Gene Set Enrichment Analysis, the Gene Ontology analysis showed that 2559 / 6588 gene sets are upregulated in phenotype experimental group,and 342 gene sets with p <0.05. The Kyoto Encyclopedia of Genes and Genomes analysis revealed that 95 / 316 gene sets are upregulated in phenotype experimental group, and four gene sets(Notch pathway, other types of O-glycan biosynthesis, ovarian steridogenesis and Hippo pathway) with p <0.05.

CONCLUSIONS

Changes in differential genes are mainly related to immune-related processes and pathways, and pathways related to bone metabolism. The up-regulation of some genes can promote the progress of Bisphosphonate-related osteonecrosis of the jaw.

Macrophage miR-149-5p induction is a key driver and therapeutic target for BRONJ

Bisphosphonate-related (BP-related) osteonecrosis of the jaw (BRONJ) is one of the severe side effects of administration of BPs, such as zoledronic acid (ZA), which can disrupt the patient’s quality of life. Although the direct target of skeletal vasculature and bone resorption activity by BPs has been phenomenally observed, the underlying mechanism in BRONJ remains largely elusive. Thus, it is urgently necessary to discover effective therapeutic targets based on the multifaceted underlying mechanisms in the development of BRONJ. Here, we determined the inhibitory role of ZA-treated macrophages on osteoclast differentiation and type H vessel formation during tooth extraction socket (TES) healing. Mechanistically, ZA activated the NF-κB signaling pathway and then induced p65 nuclear translocation in macrophages to promote miR-149-5p transcription, resulting in impaired osteoclast differentiation via directly binding to the Traf6 3′-UTR region. Moreover, we identified that miR-149-5p–loaded extracellular vesicles derived from ZA-treated bone marrow–derived macrophages could regulate biological functions of endothelial cells via the Rap1a/Rap1b/VEGFR2 pathway. Furthermore, local administration of chemically modified antagomiR-149-5p was proven to be therapeutically effective in BRONJ mice. In conclusion, our findings illuminate the dual effects of miR-149-5p on skeletal angiogenesis and bone remolding, suggesting it as a promising preventive and therapeutic target for BRONJ.

Pharmacogenomics of osteonecrosis of the jaw

Osteonecrosis of the jaw (ONJ) is a rare but serious drug induced adverse event, mainly associated with the use of antiresorptive medications, such as intravenous (IV) bisphosphonates (BPs) in cancer patients. In this review, we evaluated all the pharmacogenomic association studies for ONJ published up to December 2018. To date, two SNPs (CYP2C8 rs1934951 and RBMS3 rs17024608) were identified to be associated with ONJ by two genome-wide association studies (GWAS). However, all six subsequent candidate gene studies failed to replicate these results. In addition, six discovery candidate gene studies tried to identify the genetic markers in several genes associated with bone remodeling, bone mineral density, or osteoporosis. After evaluating the results of these 6 studies, none of the SNPs was significantly associated with ONJ. Recently, two whole-exome sequencing (WES) analysis (including one from our group) were performed to identify variants associated with ONJ. So far, only our study successfully replicated discovery result indicating SIRT1 SNP rs7896005 to be associated with ONJ. However, this SNP also did not reach genome-wide significance. The major limitations of these studies include lack of replication phases and limited sample sizes. Even though some studies had larger sample sizes, they recruited healthy individuals as controls, not subjects treated with BPs. We conclude that a GWAS with a larger sample size followed by replication phase will be needed to fully investigate the pharmacogenomic markers of ONJ.

Altered microRNA expression profile in the peripheral lymphoid compartment of multiple myeloma patients with bisphosphonate-induced osteonecrosis of the jaw

Bisphosphonates are formidable inhibitors of osteoclast-mediated bone resorption employed for therapy of multiple myeloma (MM) subjects with osteolytic lesions. Osteonecrosis of the jaw (ONJ) is an uncommon drug-induced adverse event of these agents. MicroRNAs (miRNAs) are a group of small, noncoding RNAs nucleotides, which are essential post-transcriptional controllers of gene expression. They have a central role in the normal bone development. The goal of our study was to investigate 18 miRNAs, whose targets were previously validated and described in MM subjects without ONJ, in peripheral lymphocytes of MM subjects with bisphosphonate-induced ONJ. Utilizing reverse transcription quantitative polymerase chain reaction, we evaluated miRNAs in five healthy subjects and in five MM patients with ONJ. Our experimental data revealed that a diverse miRNA signature for ONJ subjects emerged with respect to control subjects. Using the filter for in silico analysis, among the 18 miRNAs, we recognized 14 dysregulated miRNAs. All these miRNAs were significantly over-expressed in patients vs controls (MIR-16-1, MIR-21, MIR-23A, MIR-28, MIR-101-1, MIR-124-1, MIR-129, MIR-139, MIR-145, MIR-149, MIR-202, MIR-221, MIR-424, MIR-520). Among them, six were strongly upregulated (fourfold upregulated and more). These miRNAs target numerous pathways and genes implicated in calcium ion binding, bone resorption, mineralization of bone matrix, and differentiation and maintenance of bone tissue. A modified microRNA expression profile after zoledronate therapy could participate to the onset of ONJ. Targeting these miRNAs could provide a new opportunity for the prevention or treatment of ONJ.

Association between CYP2C8 (rs1934951) polymorphism and bisphosphonate-related osteonecrosis of the jaws in patients on bisphosphonate therapy: a meta-analysis

AIMS

Bisphosphonate-related osteonecrosis of the jaws (BONJ) is a severe complication in patients on bisphosphonate therapy. The study was conducted to verify the association between CYP2C8 (rs1934951) polymorphism and BONJ predisposition.

METHODS

The relative epidemiologic studies were identified in PubMed and Embase to conduct a meta-analysis using STATA.

RESULTS

In the pooled analysis with multiple cancer types, patients carrying the CYP2C8 rs1934951 AA or AG genotype showed no significantly increased BONJ susceptibility compared with those carrying the wild GG genotype [dominant: odds ratio (OR) = 2.05, 95% confidence interval (CI) = 0.67-6.29, p = 0.209; recessive: OR = 1.88, 95% CI = 0.23-15.6, p = 0.560; AG vs. GG: OR = 2.07, 95% CI = 0.80-5.32, p = 0.133, and AA vs. GG: OR = 1.34, 95% CI = 0.48-3.74, p = 0.578]. A significant association between AA and AG genotypes of CYP2C8 (rs1934951) and BONJ risk was found in the subgroup analysis of multiple myeloma (dominant: OR = 5.77, 95% CI = 1.21-27.63, p = 0.028; AG vs. GG: OR = 5.02, 95% CI = 2.06-12.23, p = 0.001, and AA vs. GG: OR = 16.23, 95% CI = 1.72-78.7, p = 0.015).

CONCLUSION

The results indicated that AA and AG genotypes of CYP2C8 (rs1934951) might be predictors for multiple myeloma patients at high risk to develop BONJ.

Genomewide pharmacogenetics of bisphosphonate-induced osteonecrosis of the jaw: the role of RBMS3

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious adverse drug reaction. We conducted a genomewide association study to search for genetic variants with a large effect size that increase the risk for BRONJ.

METHODS

We ascertained BRONJ cases according to the diagnostic criteria of the American Association of Oral and Maxillofacial Surgeons. We genotyped cases and a set of treatment-matched controls using Illumina Human Omni Express 12v1 chip (733,202 markers). To maximize the power of the study, we expanded the initial control set by including population and treatment-tolerant controls from publicly available sources. Imputation at the whole-genome level was performed to increase the number of single nucleotide polymorphisms (SNPs) investigated. Tests of association were carried out by logistic regression, adjusting for population structure. We also examined a list of candidate genes comprising genes potentially involved in the pathogenesis of BRONJ and genes related to drug absorption, distribution, metabolism, and excretion.

RESULTS

Based on principal component analysis, we initially analyzed 30 white cases and 17 treatment-tolerant controls. We subsequently expanded the control set to include 60 genetically matched controls per case. Association testing identified a significant marker in the RBMS3 gene, rs17024608 (p-value < 7 × 10(-8)); individuals positive for the SNP were 5.8× more likely to develop BRONJ (odds ratio, 5.8; 95% confidence interval, 3.1-11.1). Candidate gene analysis further identified SNPs in IGFBP7 and ABCC4 as potentially implicated in BRONJ risk.

CONCLUSION

Our findings suggest that genetic susceptibility plays a role in the pathophysiology of BRONJ, with RBMS3 having a significant effect in the risk.