A systematic review and meta-analysis of efficacy and safety of Romosozumab in postmenopausal osteoporosis

Examining Romosozumab Adherence and Side Effects in Osteoporotic Patients After Surgical Fracture Fixation: A Comparative, Descriptive, and Hypothesis-Generating Study with Non-Fractured Controls

OBJECTIVES

The study aims to evaluate adherence to Romosozumab treatment in osteoporotic patients after surgical fracture fixation and compare side effects with non-fractured controls on the same therapy.

METHODS

This retrospective case-control study was conducted at the Orthopaedic Department of Policlinico Universitario di Roma "Tor Vergata", following the principles of the Declaration of Helsinki. It included postmenopausal women aged over 60, with the case group receiving Romosozumab after fracture fixation, and the control group consisting of women on Romosozumab therapy without fracture fixation. Exclusion criteria included psychiatric conditions, contraindications to Romosozumab, high-energy trauma, or other bone metabolism disorders. Data on fractures, surgeries, FRAX (Fracture Risk Assessment Tool) scores, BMD (Bone Mineral Densit) values, and follow-up details were collected. Side effects, including nasopharyngitis and severe events like hypocalcemia, stroke, and myocardial infarction, were recorded. Adherence was assessed via pharmacy records and patient interviews during routine clinical follow-up visits. Statistical analysis was performed using descriptive statistics, t-tests, and chi-square tests.

RESULTS

The study included 25 patients, with 12 in the surgical group and 13 in the conservative treatment group. The surgical group had a mean age of 67.3 years and a follow-up of 374 days, while the conservative group had a mean age of 76.4 years and a follow-up of 287 days. The surgical group underwent various fracture treatments, including femoral, humeral, and distal radius fractures, while the conservative group was treated with immobilization. There were no significant differences in FRAX scores or BMD values between the two groups. Vitamin D levels increased significantly in both groups after supplementation, but parathyroid hormone levels showed no difference. No new fractures occurred, and surgical patients had no delayed union or nonunion, though two had superficial wound infections.

CONCLUSIONS

Both groups adhered well to Romosozumab therapy, with no severe side effects; minor side effects included myalgia in the surgical group and shoulder arthralgia in the conservative group. Romosozumab is well-tolerated and adherent in osteoporotic patients after osteosynthesis surgery, with adverse events similar to non-fractured individuals. While the study design is appropriate, multicenter trials would improve the sample size and allow for subgroup analysis based on fracture type and demographics.

An update on the pharmacotherapy of osteoporosis

INTRODUCTION

Osteoporosis is a chronic metabolic bone disease characterized by progressive bone loss and structural deterioration, increasing fracture risk and morbidity. As the global population ages, its incidence is rising, underscoring the urgent need for more effective prevention and treatment strategies.

AREAS COVERED

This review synthesizes the latest evidence and guidelines from leading international societies, establishing a contemporary framework for osteoporosis pharmacotherapy. It emphasizes best practices and explores future directions in treatment optimization and fracture prevention.

EXPERT OPINION

To optimize outcomes, enhancing early detection, refining treatment strategies, and prioritizing patient-centered care are essential. Improving diagnosis through increased use of bone mineral density (BMD) assessments and identifying secondary causes are critical steps to addressing underdiagnosis, particularly in men. Pharmacotherapies play a vital role in management; while bisphosphonates serve as a cost-effective first-line treatment, denosumab and anabolic agents like Teriparatide and romosozumab are essential alternatives for high-risk patients. Future directions in osteoporosis management emphasize advancing treatment strategies through novel drug targets and innovative delivery systems, alongside personalized medicine approaches considering individual genetic and comorbidity profiles. Enhanced adherence strategies and further research into combination therapies and monitoring tools are crucial for improving prevention and treatment outcomes, ultimately reducing the fragility fracture burden worldwide.

Evaluation of Peri-Implant Bone Repair in Ovariectomized Rats Submitted to the Implant Placement Functionalized with Anti-Sclerostin

(1) Background: The challenges in Implantology involve the development of alternative methods to enhance bone repair in patients with systemic conditions, such as osteoporosis. This study aimed to evaluate the effect of a local anti-sclerostin monoclonal antibody (Scl-Ab) on the functionalization of titanium implant surfaces through a dip-coating technique in peri-implant bone repair. (2) Methods: A total of 32 female rats were separated into four groups (n = 8): SHAM NT (Sham surgery), OVX NT (ovariectomy), SHAM Scl-Ab (SHAM; implants functionalized with Scl-Ab), and OVX Scl-Ab (OVX; implants functionalized with Scl-Ab). Implant surgery was executed 30 days after ovariectomy, and the rats were euthanized 28 days postoperatively. The right tibia was used for removal torque and RT-PCR, while the left tibia was collected for micro-CT and laser confocal microscopy. (3) Results: Functionalization with Scl-Ab significantly increased the gene expression of bone markers, especially ALP, in the SHAM Scl-Ab group compared to the other groups (p < 0.05). (4) Conclusions: Some parameters of this study indicate that implants functionalized with anti-sclerostin bone anabolic drug enhance peri-implant bone repair, especially in healthy rats. However, more studies must be carried out to confirm the therapeutic benefits of this approach.

Cardiovascular outcomes of romosozumab treatment-real-world data analysis

Romosozumab is a potent treatment for osteoporosis, with significant effects on bone density and fracture prevention. This study evaluated the cardiovascular safety of romosozumab in a real-world cohort of postmenopausal women at high fracture risk. We retrospectively evaluated postmenopausal women who initiated treatment with romosozumab between January 1, 2020, and June 30, 2023. We examined the occurrence of a major adverse cardiovascular event (MACE) across two distinct segments during the treatment period and after its conclusion. After applying inclusion and exclusion criteria, 847 women were followed for a median of 729 days (IQR: 445-1060). The incidence rate of MACE was 24.0 (95% CI 17.7-32.5) per 1000 person-years during the study period. The change in the rate of MACE from 0-90 days and 90-365 days post-treatment initiation was 0.04 and 0.06 events per 1000 days, respectively. The difference in the rate between these intervals was not statistically significant (p = .09). After 1 yr of treatment, the slope of MACE increased to 0.10, differing significantly from the preceding 12 mo on treatment (p<.001). The incidence of MACE was higher in those with a background of previous cardiovascular disease or diabetes at all timepoints, as expected. The consistency in event rates during treatment suggests that romosozumab is not associated with an increase in MACE in postmenopausal women. This finding challenges reports suggesting an increase in cardiovascular events within the first year of romosozumab treatment.

Responders and non-responders to romosozumab treatment

INTRODUCTION

Romosozumab is an anti-sclerostin antibody drug with potent bone formation-promoting and bone resorption-inhibiting properties. It enhances bone mineral density and has a novel effect in preventing fractures. However, there have been reports of non-responders to romosozumab.

FINDINGS

If the least significant change is defined as 3%, only 2-12% of patients with spine osteoporosis are non-responders, and romosozumab is highly effective in this population. Low-type 1 amino-terminal propeptide (P1NP) levels during the early treatment phase are associated with non-responders early in treatment. The researchers found a cutoff value of 50.3 μg/L of P1NP in the first month of treatment. In contrast, hip osteoporosis does not respond (54-57% of the time). Low P1NP levels at the start of treatment increase the risk of non-responders. The cutoff value for P1NP was reported as 53.7 μg/L at the beginning of treatment. However, failure to meet these cutoff values does not necessarily indicate that the patient is a non-responder and does not justify a change in drug administration.

CONCLUSIONS

In spine osteoporosis, romosozumab demonstrates high effectiveness, with approximately 2-12% of patients showing no response. However, in hip osteoporosis, approximately 54-57% do not respond to the treatment with romosozumab.

Latest on Anabolic Agents for Osteoporosis Treatment

In the last decades, novel therapeutics with anabolic bone properties have been developed and are currently used in the management of osteoporosis particularly in patients with high-risk of fragility fractures. These drugs include PTH-Related Analogues, teriparatide and abaloparatide, and the anti-sclerostin agent romosozumab, this latter drug currently approved only in female patients. Their efficacies in preventing fragility fractures are widely demonstrated and their potential serious side effects were progressively downgraded, including risk of malignancies in teriparatide- and cardiovascular events in romosozumab-users, respectively. Further data are warranted about their efficacy in glucocorticoids-induces osteoporosis and fracture healings.

The role of bone in energy metabolism: A focus on osteocalcin

Understanding the mechanisms involved in whole body glucose regulation is key for the discovery of new treatments for type 2 diabetes (T2D). Historically, glucose regulation was largely focused on responses to insulin and glucagon. Impacts of incretin-based therapies, and importance of muscle mass, are also highly relevant. Recently, bone was recognized as an endocrine organ, with several bone proteins, known as osteokines, implicated in glucose metabolism through their effects on the liver, skeletal muscle, and adipose tissue. Research efforts mostly focused on osteocalcin (OC) as a leading example. This review will provide an overview on this role of bone by discussing bone turnover markers (BTMs), the receptor activator of nuclear factor kB ligand (RANKL), osteoprotegerin (OPG), sclerostin (SCL) and lipocalin 2 (LCN2), with a focus on OC. Since 2007, some, but not all, research using mostly OC genetically modified animal models suggested undercarboxylated (uc) OC acts as a hormone involved in energy metabolism. Most data generated from in vivo, ex vivo and in vitro models, indicate that exogenous ucOC administration improves whole-body and skeletal muscle glucose metabolism. Although data in humans are generally supportive, findings are often discordant likely due to methodological differences and observational nature of that research. Overall, evidence supports the concept that bone-derived factors are involved in energy metabolism, some having beneficial effects (ucOC, OPG) others negative (RANKL, SCL), with the role of some (LCN2, other BTMs) remaining unclear. Whether the effect of osteokines on glucose regulation is clinically significant and of therapeutic value for people with insulin resistance and T2D remains to be confirmed.

Treatment effects, adverse outcomes and cardiovascular safety of romosozumab - Existing worldwide data: A systematic review and meta-analysis

Background

Romosozumab is a novel monoclonal antibody that binds to sclerostin, and has dual effects of increasing bone formation and decreasing bone resorption, giving it a unique mechanism of action. The objective of this study was to perform a systematic review and meta-analysis based on existing worldwide data on treatment effects and safety of romosozumab in randomized controlled trials.

Methods

A systematic search was carried out on four databases including PubMed, Embase, Web of Science and Cochrane Central Register of Controlled Trials (CENTRAL). The keywords used for search was "(romosozumab) AND (osteoporosis OR safety)". Randomized controlled trial or post-hoc studies of the included randomized controlled trial which studied the effects and safety of romosozumab were included. The quality of selected studies was assessed with the Cochrane collaboration tool and the PEDro scale.

Results

20 studies were included for qualitative analysis. 14 studies were included for meta-analysis. In total, there were 13,507 (n = 13,507) participants with 637 men and 12,870 women from original cohorts. The overall mean difference was in favor of romosozumab treatment for lumbar spine (10.04 (95 % confidence interval (CI) = 7.51-12.57; p < 0.00001)), total hip (4.04 (95 % CI = 3.10-4.99; p < 0.00001)) and femoral neck bone mineral density (3.77 (95 % CI = 2.90-4.64; p < 0.00001)) at 12 months. There was significantly less likelihood of new vertebral fractures with romosozumab compared to control (odds ratio (OR) 0.42 (95 % CI = 0.20-0.89); p = 0.02) at 12 months of treatment. There was significantly less likelihood of new vertebral fracture at 24 months with 12 months of romosozumab followed by sequential treatment with anti-resorptive compared to control with only anti-resorptive agent use (OR 0.36 (95 % CI = 0.18-0.71); p = 0.003). There was no significant difference in serious adverse events and fatal adverse events with use of romosozumab compared with control in our meta-analyses. There were no significant differences in serious cardiovascular events in Asian population of romosozumab with control group with 12 months of romosozumab treatment followed by 24 months of anti-resorptive agent with OR 1.09 (95 % CI = 0.40-2.96; P = 0.86). There was no significant difference between romosozumab group and control group for the median time to radiographic healing. Our qualitative analysis on Quantitative Computed Tomography (QCT), Finite element analysis (FEA) and bone biopsy analyses demonstrated that romosozumab improved parameters and measures in these domains as well.

Conclusion

In conclusion, our study showed that romosozumab was an effective agent to treat osteoporosis with high quality evidence. There were no significant differences in the adverse events, serious adverse events, fatal adverse events identified. Further subgroup analysis of cardiovascular events and cardiovascular death in the total population showed no differences either.

The translational potential of this article

Given the results, romosozumab is an effective agent to treat patients with very-high risk of osteoporotic fractures.

Efficacy and safety of romosozumab: a meta-analysis of placebo-controlled trials

INTRODUCTION

We aimed to comprehensively compile placebo-controlled trials on the efficacy and safety of romosozumab (210 mg, subcutaneously, once monthly) in postmenopausal women and men with osteoporosis.

MATERIALS AND METHODS

PubMed, Google Scholar, and ClinicalTrials.gov were searched for relevant placebo-controlled trials (as of January 1, 2024). Percent change in bone mineral density (BMD), falls, fractures, and adverse events (AEs) after drug administration were collected. Risk ratios (RRs) and mean differences (MDs) with 95% confidence intervals (CIs) were calculated.

RESULTS

Six trials (7990 patients; follow-up period, 6-12 months) were included. Compared with placebo, romosozumab significantly increased lumbar spine BMD (MD = 12.69; 95% CI 11.10-14.29), total hip BMD (MD = 4.42; 95% CI 3.03-5.80), and femoral neck BMD (MD = 3.99; 95% CI 2.42-5.57) at 12 months. Romosozumab significantly decreased falls (RR = 0.80; 95% CI 0.68-0.93) and major osteoporotic fractures (RR = 0.37; 95% CI 0.25-0.54), but increased injection-site reactions (RR = 1.83; 95% CI 1.46-2.30) within 12 months. No significant differences were observed in other AEs (including cardiovascular AEs) within 12 months.

CONCLUSION

Romosozumab treatment resulted in a significant BMD gain, reduced falls and major osteoporotic fractures. It was generally well-tolerated, including the cardiovascular aspects. However, clinicians should consider the occurrence of minor AEs (e.g., injection-site reactions).

FasL impacts Tgfb signaling in osteoblastic cells

Fas ligand (FasL, CD178) belongs to classical apoptotic molecules, however, recent evidence expands the spectrum of FasL functions into non-apoptotic processes which also applies for the bone. Tgfb subfamily members (Tgfb1, Tgfb2, Tgfb3) represent major components in osteogenic pathways and extracellular matrix. Their possible association with FasL has not yet been investigated but can be postulated. To test such a hypothesis, FasL deficient (gld) calvaria-derived cells were examined with a focus on the expression of Tgfb receptor ligands. The qPCR analysis revealed significantly increased expression of Tgfb1, Tgfb2 and Tgfb3 in gld cells. To check the vice versa effect, the gld cells were stimulated by soluble FasL. As a consequence, a dramatic decrease in expression levels of all three ligands was observed. This phenomenon was also confirmed in IDG-SW3 (osteoblastic cells of endochondral origin). TFLink gateway identified Fosl2 as an exclusive candidate of FasL capable to impact expression of all three Tgfb ligands. However, Fosl2 siRNA did not cause any significant changes in expression of Tgfb ligands. Therefore, the upregulation of the three ligands is likely to occur separately. In this respect, we tested the only exclusive candidate transcription factor for Tgfb3, Prrx1. Additionally, an overlapping candidate for Tgfb1 and Tgfb2, Mef2c capable to modulate expression of sclerostin, was examined. Prrx1 as well as Mef2c were found upregulated in gld samples and their expression decreased after addition of FasL. The same effect of FasL treatment was observed in the IDG-SW3 model. Taken together, FasL deficiency causes an increase in the expression of Tgfb ligands and stimulation by FasL reduces Tgfb expression in osteoblastic cells. The candidates mediating the effect comprise Prrx1 for Tgfb3 and Mef2c for Tgfb1/2. These results indicate FasL as a novel cytokine interfering with Tgfb signaling and thus the complex osteogenic network. The emerging non-apoptotic functions of FasL in bone development and maintenance should also be considered in treatment strategies such as the anti-osteoporotic factor.

Association Between Combined Polymetallic Exposure and Osteoporosis

Combined polymetallic exposure may be an influential factor in osteoporosis. This study aimed to explore the association between polymetallic combined exposure and osteoporosis. A total of 2115 participants were included. Plasma concentrations of 22 metals were determined by inductively coupled plasma mass spectrometry. Osteoporosis was defined as a T ≤  - 2.5. The least absolute shrinkage and selection operator (LASSO) regression, binary logistics regression, and Bayesian kernel machine regression (BKMR) model were used to explore the association between plasma metals and osteoporosis. LASSO regression showed that 10 metals were associated with osteoporosis in the total population (magnesium, calcium, manganese, nickel, cobalt, arsenic, selenium, rubidium, cadmium, aluminum) and women (magnesium, calcium, molybdenum, nickel, cobalt, arsenic, selenium, rubidium, cadmium, aluminum), and four metals associated with men (magnesium, cobalt, aluminum, iron). Logistics regression showed that in total population, magnesium (ORQ3 = 0.653, 95% CI = 0.446-0.954) was negatively correlated with osteoporosis, while aluminum (ORQ2 = 1.569, 95% CI = 1.095-2.248, ORQ4 = 1.616, 95% CI = 1.109-2.354) and cadmium (ORQ4 = 1.989, 95% CI = 1.379-2.870) were positively correlated; in women, magnesium (ORQ3 = 0.579, 95% CI = 0.379-0.883) was negatively correlated with osteoporosis, while aluminum (ORQ2 = 1.563, 95% CI = 1.051-2.326, ORQ4 = 1.543, 95% CI = 1.024-2.326) and cadmium (ORQ3 = 1.482, 95% CI = 1.003-2.191, ORQ4 = 1.740, 95% CI = 1.167-2.596) were positively correlated. BKMR model showed that combined polymetallic exposure had an overall positive effect on osteoporosis, magnesium was negatively associated with osteoporosis, and cadmium, selenium, and aluminum were positively associated with osteoporosis. Metal mixtures in plasma were associated with osteoporosis risk. Magnesium may reduce the risk of osteoporosis, while cadmium, selenium, and aluminum may increase the risk of osteoporosis. Future studies needed to explore correlations and mechanisms.

Effects of romosozumab combined with routine therapy on pain relief, disease progression and adverse reactions in patients with postmenopausal osteoporosis: a systematic review and meta-analysis

Background

Postmenopausal osteoporosis (PMOP) increases fracture risk in women. Though traditional treatments are slow to act, combining romosozumab with conventional therapy shows promise. Despite its growing use, studies on effectiveness are limited. This study aims to systematically evaluate the combined therapy's impact on pain relief, disease progression, and adverse reactions in PMOP patients.

Methods

Databases including PubMed, EMBASE, ScienceDirect, and the Cochrane Library were searched from their inception to September 2023 to identify randomized controlled trials (RCTs) evaluating the role of romosozumab in PMOP. Random or fixed effect models were employed for statistical analysis. Two reviewers independently assessed the quality of the included studies and extracted the data. The meta-analysis was conducted using RevMan 5.4 software.

Results

Six RCTs with a total sample size of 17,985 cases were included. The incidence of vertebral fractures was compared and analyzed after 12 and 24 months of treatment. Romosozumab significantly reduced the incidence of vertebral fractures at 24 months (OR = 0.36; 95% CI: 0.35-0.52) but not at 12 months (OR = 0.39; 95% CI: 0.14-1.05). It was also associated with a decreased incidence of nonvertebral fractures (OR = 0.79; 95% CI: 0.66-0.94) and clinical fractures at 24 months (OR = 0.70; 95% CI: 0.59-0.82) compared to standard therapy. Romosozumab demonstrated a significant improvement in percentage change in bone mineral density (BMD) [mean difference (MD) = 10.38; 95% CI: 4.62-16.14] and in hip joint BMD (MD = 4.24; 95% CI: 2.92-5.56). There was no notable difference in adverse reactions compared to standard care (p > 0.05). Funnel plots displayed a predominantly symmetrical pattern, suggesting no evidence of publication bias in the selected literature.

Conclusion

Combining romosozumab with conventional therapy effectively treats PMOP, significantly reducing vertebral, non-vertebral, and clinical fractures while increasing BMD in the hip, femoral neck, and lumbar spine. However, further high-quality studies are needed for validation.

Comparison of the Clinical Efficacy of Anabolic Agents and Bisphosphonates in the Patients With Osteoporotic Vertebral Fracture: Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

We investigated the clinical efficacy of anabolic agents compared with bisphosphonates (BPs) for the incidence of new osteoporotic vertebral fracture (OVF) and fracture healing of OVF in the patients with OVF via meta-analyses of randomized controlled trials (RCTs).

METHODS

Electronic databases, including PubMed, Embase, and Cochrane Library were searched for published RCTs till December 2022. The RCTs that recruited participants with osteoporosis at high-/very high-risk of fracture (a history of osteoporotic vertebral or hip fracture) or fresh OVF were included in this study. We assessed the risk of bias on every included RCTs, estimated relative risk (RR) for the incidence of new OVF and fracture healing of OVF, and overall certainty of evidence. Meta-analyses were performed by Cochrane review manager (RevMan) ver. 5.3. Cochrane risk of bias 2.0 and GRADEpro/GDT were applied for evaluating methodological quality and overall certainty of evidence, respectively.

RESULTS

Five hundred eighteen studies were screened, and finally 6 eligible RCTs were included in the analysis. In the patients with prevalent OVF, anabolic agents significantly reduced the incidence of new OVF (teriparatide and romosozumab vs. alendronate and risedronate [RR, 0.57; 95% confidence interval, 0.45-0.71; p < 0.00001; high-certainty of evidence]; teriparatide vs. risedronate [RR, 0.50; 95% confidence interval, 0.37-0.68; p < 0.0001; high-certainty of evidence]). However, there was no evidence of teriparatide compared to alendronate in fracture healing of OVF (RR, 1.23; 95% confidence interval, 0.95-1.60; p = 0.12; low-certainty of evidence).

CONCLUSION

In the patients with prevalent OVF, anabolic agents showed a significant superiority for preventing new OVF than BPs, with no significant evidence for promoting fracture healing of OVF. However, considering small number of RCTs in this study, additional studies with large-scale data are required to obtain more robust evidences.

Monoclonal antibodies in patients with osteoporosis and renal insufficiency: An updated systematic review and meta-analysis

Objectives

There are challenges for the treatment of osteoporosis in patients with kidney failure and monoclonal antibodies (MAb) might be a suitable therapy. However, the efficacy and safety of MAb among patients with osteoporosis and renal insufficiency remains unclear.

Methods

We systematically searched PubMed, Embase, and Cochrane Central for studies evaluating the efficacy and safety of the use of MAb in patients with osteoporosis and renal insufficiency. We pooled risk ratios (RR) and 95% confidence intervals (CI) for binary outcomes. Mean difference (MD) was used for continuous outcomes.

Results

We included 5 studies with 33,550 patients. MAb therapy decreased the risk of vertebral fractures (RR 0.32; 95% CI 0.26-0.40; P < 0.01) when compared to placebo and no statistical difference was found when comparing to bisphosphonate (RR 0.71; 95% CI 0.49-1.03; P = 0.07). MAb therapy also decreased the risk of nonvertebral fractures (RR 0.79; 95% CI 0.69-0.91; P = 0.0009). Lumbar spine bone mineral density (BMD) was higher in the MAb therapy when compared to both placebo (MD 10.90; 95% CI 8.00-13.80; P < 0.01) and bisphosphonate (MD 7.66; 95% CI 6.19-9.14; P < 0.01). There was no statistically significant difference in the change of estimated glomerular filtration rate and in the incidence of hypocalcemia and serious adverse events between groups.

Conclusions

There were reductions in both vertebral and nonvertebral fracture risks, alongside improvements in BMD among patients with renal insufficiency treated with MAb.

Correlation study between bone metabolic markers, bone mineral density, and sarcopenia

OBJECTIVE

To investigate the correlation between bone metabolism markers, bone mineral density (BMD), and sarcopenia.

METHODS

A total of 331 consecutive patients aged ≥ 60 years who were hospitalized between November 2020 and December 2021 were enrolled. Participants were divided into sarcopenia and non-sarcopenia groups according to the Asian Working Group on Sarcopenia criteria (AWGS, 2019). The clinical data, bone metabolism markers (β-CTX, N-MID, and TP1NP), and BMD were compared between the two groups.

RESULTS

Age, β-CTX, and N-MID of the sarcopenia group were higher than those of the non-sarcopenia group (P < 0.05), but the BMD T values were lower than those of the non-sarcopenia group (P < 0.05). Binary logistic regression analysis showed that increased femoral neck BMD (FNBMD) was a protective factor for sarcopenia, while increased β-CTX was a risk factor. Pearson/Spearman correlation analysis showed that the diagnostic indices of sarcopenia were positively correlated with FNBMD and negatively correlated with β-CTX and N-MID. Multiple linear regression analysis revealed that BMI and FNBMD significantly positively affected muscle strength and appendicular skeletal muscle mass (ASM). The FNBMD significantly positively affected physical performance, while β-CTX significantly negatively affected muscle strength, ASM, and physical performance.

CONCLUSION

Increased FNBMD may be a protective factor against sarcopenia, and increased β-CTX may be a risk factor. The FNBMD significantly positively affected the diagnostic indices of sarcopenia, while β-CTX significantly negatively affected them. BMD and bone metabolism marker levels may be considered in early screening for sarcopenia.

The Impact of Non-alcohol Fatty Liver Disease on Bone Mineral Density is Mediated by Sclerostin by Mendelian Randomization Study

Non-alcoholic fatty liver disease (NAFLD) has been found to be associated with osteoporosis (OP) in observational studies. However, the precise causal relationship between NAFLD and OP remains unclear. Here, we used Mendelian randomization (MR) to explore the causal relationship. We selected NAFLD-related single-nucleotide polymorphisms from a genome-wide meta-analysis (8434 cases and 434,770 controls) as instrumental variants. We used inverse variance weighted analysis for the primary MR analysis. Furthermore, we used similar methodologies in parallel investigations of other chronic liver diseases (CLDs). We performed sensitivity analyses to ensure the reliability of the results. We observed a causality between NAFLD and forearm bone mineral density (FABMD) (beta-estimate [β]: - 0.212; p-value: 0.034). We also found that sclerostin can act as a mediator to influence the NAFLD and FABMD pathways to form a mediated MR network (mediated proportion = 8.8%). We also identified indications of causal relationships between other CLDs and OP. However, we were unable to establish any associated mediators. Notably, our analyses did not yield any evidence of pleiotropy. Our findings have implications in the development of preventive and interventional measures aimed at managing low bone mineral density in patients with NAFLD.

Potential causal associations of PM2.5 and osteoporosis: a two-sample mendelian randomization study

Background: Observational studies suggest a potential association between atmospheric particulate matter 2.5 (PM2.5) and osteoporosis, but a causal association is unclear due to the presence of confounding factors. Methods: We utilized bone mineral density indices at four specific sites to represent osteoporosis: femoral neck (FN-BMD), lumbar spine (LS-BMD), forearm (FA-BMD), and heel (HE-BMD). The PM2.5 data was obtained from the UK Biobank database, while the datasets for FN-BMD, LS-BMD, and FA-BMD were obtained from the GEFOS database, and the dataset for HE-BMD was obtained from the EBI database. A two-sample Mendelian randomization analysis was conducted using mainly the inverse variance weighted method, horizontal pleiotropy and heterogeneity were also assessed. Results: The results indicated that PM2.5 was not correlated with a decrease in FN-BMD (β: -0.305, 95%CI: -0.762, 0.153), LS-BMD (β: 0.134, 95%CI: -0.396, 0.666), FA-BMD (β: -0.056, 95%CI: -1.172,1.060), and HE-BMD (β: -0.084, 95%CI: -0.261,0.093). Additionally, acceptable levels of horizontal pleiotropy and heterogeneity were observed. Conclusion: In contrast to most observational studies, our research did not discover a potential causal relationship between PM2.5 and the development of osteoporosis.

Corylifol A suppresses osteoclastogenesis and alleviates ovariectomy-induced bone loss via attenuating ROS production and impairing mitochondrial function

Osteoporosis is a systemic disease characterized by an imbalance in bone homeostasis, where osteoblasts fail to fully compensate for the bone resorption induced by osteoclasts. Corylifol A, a flavonoid extracted from Fructus psoraleae, has been identified as a potential treatment for this condition. Predictions from network pharmacology and molecular docking studies suggest that Corylifol A exhibits strong binding affinity with NFATc1, Nrf2, PI3K, and AKT1. Empirical evidence from in vivo experiments indicates that Corylifol A significantly mitigates systemic bone loss induced by ovariectomy by suppressing both the generation and activation of osteoclasts. In vitro studies further showed that Corylifol A inhibited the activation of PI3K-AKT and MAPK pathways and calcium channels induced by RANKL in a time gradient manner, and specifically inhibited the phosphorylation of PI3K, AKT, GSK3 β, ERK, CaMKII, CaMKIV, and Calmodulin. It also diminishes ROS production through Nrf2 activation, leading to a decrease in the expression of key regulators such as NFATcl, C-Fos, Acp5, Mmp9, and CTSK that are involved in osteoclastogenesis. Notably, our RNA-seq analysis suggests that Corylifol A primarily impacts mitochondrial energy metabolism by suppressing oxidative phosphorylation. Collectively, these findings demonstrate that Corylifol A is a novel inhibitor of osteoclastogenesis, offering potential therapeutic applications for diseases associated with excessive bone resorption.

Cardiac Arrhythmia and Heart Failure Shortly After Starting Romosozumab for Osteoporosis: A Case-Based Review

Romosozumab is a humanized monoclonal antibody that targets the sclerostin protein, which regulates bone formation and resorption. It is a novel therapy in the treatment of post-menopausal women with osteoporosis. The evidence regarding romosozumab's cardiovascular safety is conflicting. We report the first post-marketing case demonstrating cardiac events (i.e., atrial fibrillation and congestive heart failure) in a female patient with osteoporosis likely triggered by romosozumab. A literature review on romosozumab and cardiovascular disease is discussed extensively. For osteoporotic patients with cardiovascular risk factors (e.g., hypertension, coronary artery disease, and stroke), the benefits of fracture prevention should be weighed against potential cardiovascular risks before prescribing romosozumab. Real-world data on post-marketing surveillance will shed light on the potential safety signals of romosozumab.

Association between periodontal disease and osteoporosis in postmenopausal women: A systematic review and meta-analysis

Objective

To evaluate the relationship between periodontitis and postmenopausal osteoporosis.

Methods

This research was carried out according to the principles laid down by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline statement. We searched the Web of Science, Embase, PubMed, The Cochrane Library, CNKI, VIP, and WanFang databases from inception to July 1, 2023 to collect all relevant publications, with no restrictions on publication date or Languages. Cochrane's tool for assessing RoB was used to evaluate the RoB for RCTs. The Newcastle-Ottawa Scale was used to assess the RoB for cohort studies and case-control studies. Mean differences (MD) with 95 % confidence intervals (CI) were used for analysis of continuous data. Heterogeneity was measured using the I2 statistic. Revman 5.4 software was used for the meta-analysis.

Results

28 observational studies with 19611 patients, including 5813 cases in the postmenopausal osteoporosis group and 13798 cases in the non-osteoporosis group. The studies showed that the degrees of clinical attachment loss (CAL), probing depth (PD), gingival recession (GR), simplified oral hygiene index (OHIS), and percentage of sites with bleeding on probing (BOP) in the postmenopausal osteoporosis group were higher than those in the non-osteoporosis group[CAL(MD = 0.89(mm), 95 % CI [0.48,1.30], p < 0.00001), PD (MD = 0.27(mm), 95 % CI [0.13, 0.41], p = 0.0001), GR (MD = 0.28(mm), 95 % CI [0.20, 0.35], p < 0.00001), OHIS (MD = 1.32,95 % CI [1.12,1.51], p < 0.00001), BOP(MD = 12.71(%), 95 % CI [3.24,22.18], p = 0.009)]. Eleven studies found that bone mineral density (BMD) in the postmenopausal osteoporosis group was lower than that in non-osteoporosis group (MD = -0.41(U/cm2), 95 % CI [-0.77,-0.05], p = 0.03). The combined analysis results of the studies in the two groups showed that there were no significant differences in the loss of alveolar crestal height (ACH)[(MD = -1.76(%),95%CI [-3.64,0.12], p = 0.07)].

Conclusion

Postmenopausal osteoporosis patients are more likely to suffer from periodontitis, and the condition is easily aggravated.

Bone Involvement in Rheumatoid Arthritis and Spondyloartritis: An Updated Review

Several rheumatologic diseases are primarily distinguished by their involvement of bone tissue, which not only serves as a mere target of the condition but often plays a pivotal role in its pathogenesis. This scenario is particularly prominent in chronic inflammatory arthritis such as rheumatoid arthritis (RA) and spondyloarthritis (SpA). Given the immunological and systemic nature of these diseases, in this review, we report an overview of the pathogenic mechanisms underlying specific bone involvement, focusing on the complex interactions that occur between bone tissue's own cells and the molecular and cellular actors of the immune system, a recent and fascinating field of interest defined as osteoimmunology. Specifically, we comprehensively elaborate on the distinct pathogenic mechanisms of bone erosion seen in both rheumatoid arthritis and spondyloarthritis, as well as the characteristic process of aberrant bone formation observed in spondyloarthritis. Lastly, chronic inflammatory arthritis leads to systemic bone involvement, resulting in systemic bone loss and consequent osteoporosis, along with increased skeletal fragility.

Therapeutic Antibodies in Medicine

Antibody engineering has developed into a wide-reaching field, impacting a multitude of industries, most notably healthcare and diagnostics. The seminal work on developing the first monoclonal antibody four decades ago has witnessed exponential growth in the last 10-15 years, where regulators have approved monoclonal antibodies as therapeutics and for several diagnostic applications, including the remarkable attention it garnered during the pandemic. In recent years, antibodies have become the fastest-growing class of biological drugs approved for the treatment of a wide range of diseases, from cancer to autoimmune conditions. This review discusses the field of therapeutic antibodies as it stands today. It summarizes and outlines the clinical relevance and application of therapeutic antibodies in treating a landscape of diseases in different disciplines of medicine. It discusses the nomenclature, various approaches to antibody therapies, and the evolution of antibody therapeutics. It also discusses the risk profile and adverse immune reactions associated with the antibodies and sheds light on future applications and perspectives in antibody drug discovery.

Using sequential pharmacotherapy for the treatment of osteoporosis: an update of the literature

INTRODUCTION

Osteoporosis, which is characterized by compromised bone density and heightened susceptibility to fractures, is a substantial public health concern, especially among the aging population. Underdiagnosis, undertreatment, and therapy non-adherence contribute to its impact. Anabolic and dual-action agents like teriparatide, abaloparatide, and romosozumab have emerged as effective treatments, allowing rapid gains in bone mineral density (BMD) and reducing fracture risk. However, administering treatments in the correct order is paramount, with an 'anabolic first' approach gaining traction for patients at high risk of fractures. This strategy involves starting anabolic therapies, followed by antiresorptive agents as maintenance therapy. It is important to note that the effectiveness of anabolic agents differs between treatment-naive and previously treated patients: tailored treatment approaches are therefore necessary. This comprehensive strategy adheres to clinical guidelines, emphasizing individualized care, early intervention, and patient-centered management to mitigate the burden of osteoporosis and enhance patients' quality of life.

AREA COVERED

The aim of this review is to summarize recent evidence on the sequential treatment of osteoporosis and to provide recommendations on the best treatment strategies.

EXPERT OPINION

Effective treatments, such as anabolic agents, are key in high-risk patients, who require an 'anabolic first' approach. Sequential therapy, specifically tailored to a patient's history, can help to optimize prevention and management of fractures.

Anti-resorptive therapy in the osteometabolic patient affected by periodontitis. A joint position paper of the Italian Society of Orthopaedics and Traumatology (SIOT) and the Italian Society of Periodontology and Implantology (SIdP)

This joint report from the Italian Society of Orthopaedics and Traumatology (SIOT) and the Italian Society of Periodontology and Implantology (SIdP) aims for a consensus around the scientific rationale and clinical strategy for the management of osteoporotic patients affected by periodontitis who are undergoing anti-resorptive (AR) therapy to manage the risk of the occurrence of a medication-related osteonecrosis of the jaws (MRONJ). Osteoporosis and periodontitis are chronic diseases with a high prevalence in aging patients, and they share some of the same pathogenetic mechanisms based upon inflammation. Available evidence shows the relationship among osteoporosis, AR agents, periodontitis and implant therapy in relation to the incidence of MRONJ. Uncontrolled periodontitis may lead to tooth loss and to the need to replace teeth with dental implants. Tooth extraction and surgical dental procedures are recognized as the main risk factors for developing MRONJ in individuals taking AR therapy for osteometabolic conditions. Although the incidence of MRONJ in osteometabolic patients taking AR therapy may be as low as 0.9%, the increasing prevalence of osteoporosis and the high prevalence of periodontitis suggest that this potential complication should not be overlooked. Good clinical practice (GCP) guidelines are proposed that aim at a more integrated approach (prescriber, dentist, periodontist and dental hygienist) in the management of periodontitis patients undergoing AR therapy for osteometabolic disorders to reduce the risk of MRONJ. Dental professional and prescribers should educate patients regarding the potential risk associated with the long-term use of AR therapy and oral health behavior.

Diagnosis and management of osteoporosis in Saudi Arabia: 2023 key updates from the Saudi Osteoporosis Society

The Saudi Osteoporosis Society (SOS) has updated its guidelines for the diagnosis and management of osteoporosis in Saudi Arabia (SA), with emphasis on postmenopausal women. This document is relevant to all healthcare professionals in SA involved in the care of patients with osteoporosis and osteoporosis-related fractures.

INTRODUCTION

The SOS launched the first national osteoporosis guidelines in 2015 and spearheaded the Gulf Cooperation Council Countries (GCC) osteoporosis consensus report in 2020 which was under the auspices of the European Society for Clinical and Economic Aspects of Osteoporosis (ESCEO). This paper highlights a major update of the guidelines in the SA setting.

METHODS

This guideline is an adaptation of the current guidelines derived from ESCEO, the American Association of Clinical Endocrinologists (AACE), and the GCC osteoporosis consensus report and studies on osteoporosis done in SA. Where accessible, the timeliest systematic review, meta-analysis, and randomized controlled trials were used as evidence.

RESULTS

The present update includes new recommendations for the assessment of osteoporosis taking into consideration the Saudi model of FRAX for fracture probabilities, appropriate doses for the maintenance of vitamin D status and calcium, the use of representative blood analytes for therapy monitoring, the use of romosozumab and sequential therapy in the pharmacological management strategies, and the establishment of fracture liaison services to prevent secondary fractures.

CONCLUSION

This updated guideline is for all healthcare professionals involved in osteoporosis and post-fracture care and management in SA and harmonized the most up-to-date changes in the field based on evidence-based medicine for use in the local setting.

Physiopathology of Osteoporosis: Nursing Involvement and Management

Osteoporosis is a major public health problem today. We are facing an aging society where the average life expectancy continues to increase. Osteoporosis affects more than 30% of postmenopausal women due to hormonal changes that occur during this time. Postmenopausal osteoporosis is therefore of particular concern. The aim of this review is to identify the etiology, pathophysiology, diagnosis and treatment of this disease and lay the foundation for the role nurses should play in preventing postmenopausal osteoporosis. Several risk factors are associated with osteoporosis. In addition to age and sex, genetics, ethnicity, diet, or the presence of other disorders determine the development of this disease. The key factors include exercise, a balanced diet, and high levels of vitamin D. This is primarily from a solar source, and infancy is the time when future bone formation is greatest. There are now medications that can complement these preventive measures. The work of nursing staff is not only prevention, but also early detection and early treatment. In addition, imparting information and knowledge about the disease to the population is key to preventing an osteoporosis epidemic. In this study, a detailed description is provided of the biological and physiological disease, the preventive measures currently being researched, the information currently available to the population, and how health professionals address osteoporosis from a preventive perspective.

Paracrine and endocrine functions of osteocytes

Osteocytes are dendritic-shaped cells embedded in the bone matrix and are terminally differentiated from osteoblasts. Inaccessibility due to their location has hindered the understanding of the molecular functions of osteocytes. However, scientific advances in the past few decades have revealed that osteocytes play critical roles in bone and mineral metabolism through their paracrine and endocrine functions. Sclerostin produced by osteocytes regulates bone formation and resorption by inhibiting Wnt/β-catenin signaling in osteoblast-lineage cells. Receptor activator of nuclear factor κ B ligand (RANKL) derived from osteocytes is essential for osteoclastogenesis and osteoclast activation during postnatal life. Osteocytes also secrete fibroblast growth factor 23 (FGF23), an endocrine FGF that regulates phosphate metabolism mainly by increasing phosphate excretion and decreasing 1, 25-dihydroxyvitamin D production in the kidneys. The regulation of FGF23 production in osteocytes is complex and multifactorial, involving many local and systemic regulators. Antibodies against sclerostin, RANKL, and FGF23 have emerged as new strategies for the treatment of metabolic bone diseases. Improved undrstanding of the paracrine and endocrine functions of osteocytes will provide insight into future therapeutic options.

Evidence of the static magnetic field effects on bone-related diseases and bone cells

Static magnetic fields (SMFs), magnetic fields with constant intensity and orientation, have been extensively studied in the field of bone biology both fundamentally and clinically as a non-invasive physical factor. A large number of animal experiments and clinical studies have shown that SMFs have effective therapeutic effects on bone-related diseases such as non-healing fractures, bone non-union of bone implants, osteoporosis and osteoarthritis. The maintenance of bone health in adults depends on the basic functions of bone cells, such as bone formation by osteoblasts and bone resorption by osteoclasts. Numerous studies have revealed that SMFs can regulate the proliferation, differentiation, and function of bone tissue cells, including bone marrow mesenchymal stem cells (BMSCs), osteoblasts, bone marrow monocytes (BMMs), osteoclasts, and osteocytes. In this paper, the effects of SMFs on bone-related diseases and bone tissue cells are reviewed from both in vivo studies and in vitro studies, and the possible mechanisms are analyzed. In addition, some challenges that need to be further addressed in the research of SMF and bone are also discussed.

The Role of Sympathetic Nerves in Osteoporosis: A Narrative Review

Osteoporosis, a systemic bone disease, is characterized by decreased bone density due to various reasons, destructed bone microstructure, and increased bone fragility. The incidence of osteoporosis is very high among the elderly, and patients with osteoporosis are prone to suffer from spine fractures and hip fractures, which cause great harm to patients. Meanwhile, osteoporosis is mainly treated with anti-osteoporosis drugs that have side effects. Therefore, the development of new treatment modalities has a significant clinical impact. Sympathetic nerves play an important role in various physiological activities and the regulation of osteoporosis as well. Therefore, the role of sympathetic nerves in osteoporosis was reviewed, aiming to provide information for future targeting of sympathetic nerves in osteoporosis.

A Mini Review on Osteoporosis: From Biology to Pharmacological Management of Bone Loss

Osteoporosis refers to excessive bone loss as reflected by the deterioration of bone mass and microarchitecture, which compromises bone strength. It is a complex multifactorial endocrine disease. Its pathogenesis relies on the presence of several endogenous and exogenous risk factors, which skew the physiological bone remodelling to a more catabolic process that results in net bone loss. This review aims to provide an overview of osteoporosis from its biology, epidemiology and clinical aspects (detection and pharmacological management). The review will serve as an updated reference for readers to understand the basics of osteoporosis and take action to prevent and manage this disease.

Osteoporosis and fractures in rheumatoid arthritis - risk factors

In this chapter, we emphasize among rheumatoid arthritis (RA) patients, whom and how to screen for osteoporosis. We highlight certain modalities, advancements in technology, secondary osteoporosis workup, and laboratory testing as well as their caveats. Finally, we discuss current guidance on how to direct the laboratory and radiology testing in the context of the individual patient with RA to guide and select from the osteoporosis treatment options currently available.

Current Status of the Diagnosis and Management of Osteoporosis

Osteoporosis has been defined as the silent disease of the 21st century, becoming a public health risk due to its severity, chronicity and progression and affecting mainly postmenopausal women and older adults. Osteoporosis is characterized by an imbalance between bone resorption and bone production. It is diagnosed through different methods such as bone densitometry and dual X-rays. The treatment of this pathology focuses on different aspects. On the one hand, pharmacological treatments are characterized by the use of anti-resorptive drugs, as well as emerging regenerative medicine treatments such as cell therapies and the use of bioactive hydrogels. On the other hand, non-pharmacological treatments are associated with lifestyle habits that should be incorporated, such as physical activity, diet and the cessation of harmful habits such as a high consumption of alcohol or smoking. This review seeks to provide an overview of the theoretical basis in relation to bone biology, the existing methods for diagnosis and the treatments of osteoporosis, including the development of new strategies.

Effects of diabetes on osteocytes

PURPOSE OF REVIEW

Better understanding of the mechanisms underlying skeletal dysfunction in the context of diabetes is needed to guide the development of therapeutic interventions to reduce the burden of diabetic fractures. Osteocytes, the 'master regulators' of bone remodeling, have emerged as key culprits in the pathogenesis of diabetes-related skeletal fragility.

RECENT FINDINGS

Both type 1 diabetes and type 2 diabetes cause chronic hyperglycemia that, over time, reduces bone quality and bone formation. In addition to acting as mechanosensors, osteocytes are important regulators of osteoblast and osteoclast activities; however, diabetes leads to osteocyte dysfunction. Indeed, diabetes causes the accumulation of advanced glycation end-products and senescent cells that can affect osteocyte viability and functions via increased receptor for advanced glycation endproducts (RAGE) signaling or the production of a pro-inflammatory senescence-associated secretory phenotype. These changes may increase osteocyte-derived sclerostin production and decrease the ability of osteocytes to sense mechanical stimuli thereby contributing to poor bone quality in humans with diabetes.

SUMMARY

Osteocyte dysfunction exists at the nexus of diabetic skeletal disease. Therefore, interventions targeting the RAGE signaling pathway, senescent cells, and those that inhibit sclerostin or mechanically stimulate osteocytes may alleviate the deleterious effects of diabetes on osteocytes and bone quality.

The Impact of COVID-19 in Bone Metabolism: Basic and Clinical Aspects

The use of standard procedures for the diagnosis of osteoporosis and assessment of fracture risk significantly decreased during the COVID-19 pandemic, while the incidence of fragility fractures was mostly unaltered. Both COVID-19 per se and its treatments are associated with a negative impact on bone health. Preclinical models show that mice infected with SARS-CoV2 even without symptoms display loss of trabecular bone mass two weeks post infection, due to increased numbers of osteoclasts. Osteoporosis medications do not aggravate the clinical course of COVID-19, while preclinical data suggests possible beneficial effects of some therapies. While vitamin D deficiency is clearly associated with a worse clinical course of COVID-19, evidence of improved patient outcome with vitamin D supplementation is lacking. Osteoporosis treatment should not be generally discontinued, and recommendations for substituting therapies are available. Osteoporosis therapies do not interfere with the efficacy or side-effect profiles of COVID-19 vaccines and should not be stopped or indefinitely delayed because of vaccination.

Pros and Cons of Skeletal Medications in the COVID-19 Era

Purpose of Review

This review provides an overview regarding osteoporosis therapies during the COVID-19 pandemic.

Recent Findings

The COVID-19 pandemic has disrupted treatments for osteoporosis and resulted in decreased adherence particularly for parenteral regimens. Osteoporosis medications are safe and effective during the pandemic and should be continued whenever possible. Bisphosphonates have long-lasting effects on bone turnover such that delays in their administration are unlikely to be harmful to skeletal health. In contrast, interruption of denosumab treatment is strongly discouraged because of rapid loss of bone mass and an associated increased risk for rebound vertebral fractures. When osteoanabolic treatments cannot be continued during the pandemic, change to an oral bisphosphonate is advised. Preclinical data suggest possible beneficial effects of some therapies against COVID-19, but require validation in clinical studies. Vitamin D deficiency is associated with a more severe COVID-19 clinical course but data supporting improvements in outcomes with vitamin D supplementation are lacking.

Summary

The impact of the COVID-19 pandemic on long-term bone health remains unknown but focused interventions to ensure osteoporosis treatment initiation/maintenance should be implemented. Future studies are needed to determine whether osteoporosis medications have an impact on SARS-CoV-2 pathophysiology and COVID-19 clinical outcomes.

Crosstalk between the gut microbiota and postmenopausal osteoporosis: Mechanisms and applications

Postmenopausal osteoporosis (PMO) results from a reduction in bone mass and microarchitectural deterioration in bone tissue due to estrogen deficiency, which may increase the incidence of fragility fractures. The number of people suffering from PMO has increased over the years because of the rapidly aging population worldwide. However, several pharmacological agents for the treatment of PMO have many safety risks and impose a heavy financial burden to patients and society. In recent years, the "gut-bone" axis has been proposed as a new approach in the prevention and treatment of PMO. This paper reviews the relationship between the gut microbiota and PMO, which mainly includes the underlying mechanisms between hormones, immunity, nutrient metabolism, metabolites of the gut microbiota and intestinal permeability, and explores the possible role of the gut microbiota in these processes. Finally, we discuss the therapeutic effects of diet, prebiotics, probiotics, and fecal microbiota transplantation on the gut microbiota.

Sclerostin is a promising therapeutic target for oral inflammation and regenerative dentistry

Sclerostin is the protein product of the SOST gene and is known for its inhibitory effects on bone formation. The monoclonal antibody against sclerostin has been approved as a novel treatment method for osteoporosis. Oral health is one of the essential aspects of general human health. Hereditary bone dysplasia syndrome caused by sclerostin deficiency is often accompanied by some dental malformations, inspiring the therapeutic exploration of sclerostin in the oral and dental fields. Recent studies have found that sclerostin is expressed in several functional cell types in oral tissues, and the expression level of sclerostin is altered in pathological conditions. Sclerostin not only exerts similar negative outcomes on the formation of alveolar bone and bone-like tissues, including dentin and cementum, but also participates in the development of oral inflammatory diseases such as periodontitis, pulpitis, and peri-implantitis. This review aims to highlight related research progress of sclerostin in oral cavity, propose necessary further research in this field, and discuss its potential as a therapeutic target for dental indications and regenerative dentistry.

Positive and Negative Regulators of Sclerostin Expression

Sclerostin is secreted from osteocytes, binds to the Wnt co-receptor Lrp5/6, and affects the interaction between Wnt ligands and Lrp5/6, which inhibits Wnt/β-catenin signals and suppresses bone formation. Sclerostin plays an important role in the preservation of bone mass by functioning as a negative regulator of bone formation. A sclerostin deficiency causes sclerosteosis, which is characterized by an excess bone mass with enhanced bone formation in humans and mice. The expression of sclerostin is positively and negatively regulated by many factors, which also govern bone metabolism. Positive and negative regulators of sclerostin expression and their effects are introduced and discussed herein based on recent and previous findings, including our research.

Osteocytes and the pathogenesis of hypophosphatemic rickets

Since phosphorus is a component of hydroxyapatite, its prolonged deprivation affects bone mineralization. Fibroblast growth factor 23 (FGF23) is essential for maintaining phosphate homeostasis and is mainly produced by osteocytes. FGF23 increases the excretion of inorganic phosphate (Pi) and decreases the production of 1,25-dihydroxyvitamin D in the kidneys. Osteocytes are cells of osteoblastic lineage that have undergone terminal differentiation and become embedded in mineralized bone matrix. Osteocytes express FGF23 and other multiple genes responsible for hereditary hypophosphatemic rickets, which include phosphate-regulating gene homologous to endopeptidase on X chromosome (PHEX), dentin matrix protein 1 (DMP1), and family with sequence similarity 20, member C (FAM20C). Since inactivating mutations in PHEX, DMP1, and FAM20C boost the production of FGF23, these molecules might be considered as local negative regulators of FGF23. Mouse studies have suggested that enhanced FGF receptor (FGFR) signaling is involved in the overproduction of FGF23 in PHEX-deficient X-linked hypophosphatemic rickets (XLH) and DMP1-deficient autosomal recessive hypophosphatemic rickets type 1. Since FGFR is involved in the transduction of signals evoked by extracellular Pi, Pi sensing in osteocytes may be abnormal in these diseases. Serum levels of sclerostin, an inhibitor Wnt/β-catenin signaling secreted by osteocytes, are increased in XLH patients, and mouse studies have suggested the potential of inhibiting sclerostin as a new therapeutic option for the disease. The elucidation of complex abnormalities in the osteocytes of FGF23-related hypophosphatemic diseases will provide a more detailed understanding of their pathogenesis and more effective treatments.