Mechanisms of Bone Remodeling Disorder in Hemophilia

Effects of PCSK9 on thrombosis and haemostasis in a variety of metabolic states: Lipids and beyond (Review)

Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors are widely recognised as being able to induce a potent reduction in low‑density lipoprotein‑cholesterol. An increasing number of studies have suggested that PCSK9 also influences the haemostatic system by altering platelet function and the coagulation cascade. These findings have significant implications for anti‑PCSK9 therapy in patients with specific coagulation conditions, including expanded indications, dose adjustments and drug interactions. The present review summarises the changes in PCSK9 levels in individuals with liver diseases, chronic kidney diseases, diabetes mellitus, cancer and other disease states, and discusses their impact on thrombosis and haemostasis. Furthermore, the structure, effects and regulatory mechanisms of PCSK9 on platelets, coagulation factors, inflammatory cells and endothelial cells during coagulation and haemostasis are described.

Insights and implications of sexual dimorphism in osteoporosis

Osteoporosis, a metabolic bone disease characterized by low bone mineral density and deterioration of bone microarchitecture, has led to a high risk of fatal osteoporotic fractures worldwide. Accumulating evidence has revealed that sexual dimorphism is a notable feature of osteoporosis, with sex-specific differences in epidemiology and pathogenesis. Specifically, females are more susceptible than males to osteoporosis, while males are more prone to disability or death from the disease. To date, sex chromosome abnormalities and steroid hormones have been proven to contribute greatly to sexual dimorphism in osteoporosis by regulating the functions of bone cells. Understanding the sex-specific differences in osteoporosis and its related complications is essential for improving treatment strategies tailored to women and men. This literature review focuses on the mechanisms underlying sexual dimorphism in osteoporosis, mainly in a population of aging patients, chronic glucocorticoid administration, and diabetes. Moreover, we highlight the implications of sexual dimorphism for developing therapeutics and preventive strategies and screening approaches tailored to women and men. Additionally, the challenges in translating bench research to bedside treatments and future directions to overcome these obstacles will be discussed.

Association of bone mineral density and potential risk factors for osteoporosis in patients with severe haemophilia A

INTRODUCTION

In people with haemophilia (PWH), recurrent episodes of bleeding lead to joint deterioration and bone resorption. To date, the effects of various other factors on bone mineral density (BMD) reduction have found conflicting results.

AIM

The aim of this study was to analyse the relationships between BMD, bone mineral content (BMC), and trabecular bone score (TBS) parameters based on the dual X-ray absorptiometry method (DXA) and potential risk factors for osteoporosis in patients with severe haemophilia A.

METHODS

Fifty-five men with severe haemophilia A, aged 18-68 years, and 59 healthy volunteer men were enrolled in this study. Densitometric-derived lumbar spine and femoral neck BMD, BMC, and TBS were measured. Blood analyses were performed for morphology parameters, liver and kidney function parameters, and viral status. Serum levels of oestradiol (E2 ), testosterone (T), dehydroepiandrosterone sulphate (DHEA-S), parathormone, and vitamin D were measured.

RESULTS

Patients showed significantly lower BMD compared to controls (p < .003). The result below the expected range for age was nearly double (6.82% vs. 3.92%) in PWH under 50 years old compared to controls. Haemophilic patients also exhibited significantly higher vitamin D3 deficiency (p < .0001), which was strongly associated with low TBS. Additionally, low body mass index and high neutrophil/lymphocyte ratio were correlated with low BMC and BMD.

CONCLUSIONS

This study confirms the prevalence of low BMD and BMC in patients with haemophilia in Poland. Factors that contribute to low BMD are primarily vitamin D deficiency, low BMI, high neutrophil/lymphocyte ratio, and low testosterone/oestradiol ratio.

Pathogenesis and treatment of osteoporosis in patients with hemophilia

INTRODUCTION

Hemophilia is a rare X-linked recessive inherited bleeding disorder caused by mutations of the genes encoding coagulation factor VIII (FVIII) or IX (FIX). Patients with hemophilia (PWH) often have a high risk of osteoporosis and fractures that is usually ignored. Herein, we review the underlying mechanisms of osteoporosis and the increased risk of fractures and their treatment in patients with FVIII or FIX deficiency.

METHODS

The PubMed, Web of Science, Embase, and Cochrane Library databases were searched to identify original research articles, meta-analyses, and scientific reviews on the mechanisms or treatment of osteoporosis in PWH.

RESULTS

The pathogenic mechanisms of osteoporosis in PWH are multifactorial and remain unclear. The available evidence shows that FVIII and FIX deficiency may directly affect bone metabolism by interfering with the RANK/RANKL/OPG pathway. Other potential mechanisms of osteoporosis in PWH include thrombin deficiency and the unloading and immobilization of bone, which will affect osteoblast and osteoclast activity by changing the cytokine profiles. The treatment of osteoporosis in PWH includes antiresorptive, anabolic, and dual-action drugs; weight-bearing exercise; fall prevention; and prophylactic coagulation factor replacement therapy. However, clinical studies of the efficacy of anti-osteoporotic agents in osteoporosis of PWH are urgently needed.

CONCLUSION

This review summarizes recent progress in research on the pathogenesis of osteoporosis in PWH and provides insights into potential treatment for osteoporosis in PWH.

Risk of Fractures, Repeated Fractures and Osteoporotic Fractures among Patients with Hemophilia in Taiwan: A 14-Year Population-Based Cohort Study

The world is aging, and hemophilia patients are as well. The association between patients with hemophilia (PWH) and low bone mineral density is clear. However, the incidence of fractures in patients with hemophilia is inconclusive, and no research has yet explored repeated fractures among PWH. In this study, we investigated the incidence of all-site fractures, repeated fractures and osteoporotic fractures amongst PWH. The study compared the incidence of all-site fractures, repeated fractures and osteoporotic fractures occurring in all PWH who were enrolled in Taiwan's National Health Insurance Research Database between 1997 and 2013 with an age- and gender-matched group from the general population. Eight-hundred thirty-two PWH, along with 8320 members of the general population, were included in the final analysis. After multivariate COX regression analysis with an adjustment for confounding factors, it was found that PWH experienced a higher risk of osteoporotic fracture (HR: 1.25 with 95% CI of 1.03-2.52) but only saw a neutral effect with regards to both all-sites of fracture (HR: 1.00 with 95% CI of 0.92-1.09) and repeated fractures (HR: 1.01 with 95% CI of 0.92-1.10), when compared with the general population. This 14-year population-based cohort study showed that PWH had a higher risk of osteoporotic fracture, but that hemophilia only had a neutral effect in all-sites of fracture and repeated fractures. Screening, prevention and treatment for osteoporosis and further osteoporotic fractures among PWH, in order to improve quality of life and achieve healthy aging in this particular population, remain essential.

Effect of emicizumab prophylaxis on bone and joint health markers in people with haemophilia A without factor VIII inhibitors in the HAVEN 3 study

INTRODUCTION

Emicizumab prophylaxis significantly reduces bleeding events; however, the associated impact on bone/joint health is unknown.

AIM

To explore the effect of emicizumab prophylaxis on bone/joint health in people with haemophilia A (PwHA) without FVIII inhibitors enrolled in HAVEN 3 (NCT02847637).

METHODS

Haemophilia joint health scores (HJHS; v2.1) were evaluated at baseline and Weeks 49 and 97 in PwHA receiving emicizumab (n = 134), and at baseline and Weeks 49, 73 and 97 in PwHA who switched to emicizumab after 24 weeks of no prophylaxis (n = 17). Bone and joint biomarkers were measured in 117 PwHA at baseline and at Weeks 13, 25, 49 and 73.

RESULTS

HJHS was lower for PwHA who were previously on FVIII prophylaxis, aged <40 years or had no target joints at baseline compared with PwHA who were receiving no prophylaxis, aged ≥40 years or with target joints. Clinically significant mean (95% confidence interval) improvements from baseline of -2.13 (-3.96, -.29) in HJHS joint-specific domains were observed at Week 49 in PwHA with at least one target joint at study entry (n = 71); these changes were maintained through Week 97. Improvements in HJHS from baseline were also observed for PwHA aged 12-39 years. Biomarkers of bone resorption/formation, cartilage degradation/synthesis, and inflammation did not change significantly during emicizumab prophylaxis.

CONCLUSIONS

Clinically relevant improvements in HJHS were observed in younger PwHA and those with target joints after 48 weeks of emicizumab in HAVEN 3. Biomarkers of bone/joint health did not show significant changes during 72 weeks of emicizumab prophylaxis.

Bispecific antibodies for the treatment of hemophilia A

INTRODUCTION

Emicizumab is a bispecific antibody exerting cofactor function of FVIIIa irrespective of the presence of FVIII inhibitors. Long-term data of phase 1/2 and phase 3 studies have been accumulated. Various questions such as indicated patients, ITI, application to PUPs, hemostatic treatment including surgeries, and emicizumab-related morbidity remain to be solved.

AREAS COVERED

The review describes the mode of action, data from pre-/post-marketing and ongoing clinical studies according to PubMed search and our own works.

EXPERT OPINION

For patients with a persistent inhibitor, emicizumab is a definite therapeutic option, although the possibility of BPAs-associated thromboembolic/TMA events raises concerns. The use of ITI together with emicizumab prophylaxis is being examined in clinical trials. For non-inhibitor, especially pediatric patients, emicizumab prophylaxis can be an option. Outcome assessment 'beyond ABR' such as joint health, physical/mental activity, QOL is required. Furthermore, continuous data collection for emicizumab-related adverse events and morbidity would be recommended.