The bone disease associated with factor VIII deficiency in mice is secondary to increased bone resorption

Could PTH/Ca Ratio Serve as a New Marker for Evaluating Bone Metabolism in Hemophilia Patients?

Background/Objectives: Low bone mineral density (BMD) is common in hemophilia patients. Identifying high-risk patients for low BMD early is essential to prevent complications and reduce morbidity. The parathyroid hormone (PTH)/calcium (Ca) ratio is a cost-effective marker for predicting BMD, highlighting the need for routine screening and early intervention in this population. Hemophilia is a hereditary bleeding disorder caused by deficiencies in clotting factors VIII (hemophilia A) and IX (hemophilia B). Patients with hemophilia are at risk of low bone mineral density (BMD). This study aimed to evaluate the prevalence of low BMD, associated risk factors, and raise awareness regarding its significance in hemophilia patients. Methods: We retrospectively assessed bone metabolism in 62 hemophilia patients followed at our center. BMD was evaluated using dual-energy X-ray absorptiometry (DEXA). Additionally, serum levels of 25-OH-D3, alkaline phosphatase, PTH, Ca, phosphor, and creatinine were measured. The PTH/Ca, PTH/25-OH-D3, and Ca×25-OH-D3/PTH ratios were calculated. Results: The median age of the 62 patients with hemophilia included in the study (hemophilia A: 87.1%, hemophilia B: 12.9%) was 37 years (range: 21-66), and all were male. Of these patients, 67.7% (n = 42) had severe, 21% (n = 13) had moderate, and 11.3% (n = 7) had mild hemophilia. A total of 85.5% of patients were on factor prophylaxis, and 75.4% had a target joint. In laboratory analysis, the median 25-OH-D3 level was 13.4 µg/L and 75% patients had 25-OH-D3 deficiency. According to DEXA results, 62.9% had lower than normal BMD. When we divided the patients into normal and low BMD groups according to DEXA results, weight (p = 0.006), height (p = 0.024), factor levels (p = 0.004), PTH (p = 0.010), AST (p = 0.029), and PTH/Ca (p = 0.011) levels were statistically significantly different between the groups. The severity of the disease and the rate of receiving prophylaxis were higher in the group with low BMD (p = 0.015, p = 0.006, respectively). In multivariate analysis, PTH/Ca ratio and weight were found to be independent risk factors for BMD. A linear relationship was found between PTH/Ca ratio and BMD. The optimal cut-off value for PTH/Ca was 6.57, with a selectivity of 65% and specificity of 82%. When we divided the patients into groups according to the cut-off value of 6.57, we found that the probability of low BMD increased approximately 7-fold in the group with PTH/Ca > 6.57 (OR 7.045, 95% CI 1.485-33.42, p = 0.014). There was an inverse association between patient weight and low BMD (p = 0.043). Conclusions: Low BMD is a critical public health concern frequently observed in patients with hemophilia. The study highlights a high rate of low BMD and 25-OH-D3 deficiency in hemophilia patients, with the PTH/Ca ratio shown to be useful in predicting BMD. The PTH/Ca ratio is suggested as an accessible, cost-effective, and practical test for evaluating BMD in hemophilia patients.

Bone and Hemophilia: The Role of Factor VIII-Systematic Review

Factor VIII (FVIII) is involved in several molecular pathways and biological processes; indeed, it has a role in the coagulative cascade, cardiovascular disease, hypertension, brain and renal function, cancer incidence and spread, macrophage polarization, and angiogenesis. Hemophilic patients usually present an increase in fracture risk, bone resorption, and an excess of osteoporosis as compared to healthy individuals. Several studies have tried to clarify their etiology but unfortunately it is still unclear. This review focuses on the role of FVIII in bone biology by summarizing all the knowledge present in the literature. We carried out a systematic review of the available literature following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Several studies demonstrated that FVIII is involved in different molecular pathways interfering with bone physiology; it exerts interesting effects on OPG/RANK/RANKL pathways and thrombin/PAR1 pathways. These data confirm a relationship between FVIII and bone metabolism; however, there are still many aspects to be clarified. This review highlights the role of the coagulation factor FVIII in bone metabolism, suggesting new hypotheses for future studies both in vitro and in vivo to better understand the important pleiotropic role of FVIII and hopefully to develop new therapeutic agents for skeletal diseases.

Murine vs. Human Osteoblast Responses to Coagulation and Inflammatory Factors: Reconsidering the Use of Animal Models in Hemophilia a Research

Background/Objectives: Hemophilia A is associated with frequent bleeding episodes, joint damage, and reduced bone mineral density (BMD). The role of coagulation factors and inflammatory cytokines on bone metabolism, particularly on osteoblast function, is of increasing interest. However, significant inter-species differences in bone remodeling raise concerns about the translatability of findings from murine models to human systems. This study aims to investigate the effects of human coagulation factors and cytokines on bone formation, focusing on inter-species differences in the cell viability and mineralization of murine and human osteoblasts. Methods: Murine MC3T3-E1 and human SaOs-2 osteoblasts were cultured in osteoblast differentiation medium supplemented with various coagulation factors (FVIII, vWF, vWF-FVIII, FIX, FX, thrombin, and FVIII-thrombin) or cytokines (IL-6, TNF-α). Cell viability was assessed at both two-week and three-week time points using the CCK-8 assay, and mineralization was evaluated via Alizarin red S staining. Results: Coagulation factors significantly enhanced cell viability in human osteoblasts but had no effects on the murine counterpart. FX inhibited mineralization in human cells, while murine cells showed no significant changes. TNF-α stimulated mineralization in murine osteoblasts but inhibited it in human cells, highlighting species-specific responses to inflammatory cytokines. Similar trends in response patterns were observed at two and three weeks, with greater consistency at the later time point. Conclusions: These findings reveal critical inter-species differences in osteoblast responses to coagulation factors and cytokines, raising questions about the validity of using murine models to study human bone metabolism. Future research must account for these differences to ensure that preclinical models accurately reflect human pathophysiology, particularly in the context of hemophilia A.

Effects of coagulation factors on bone cells and consequences of their absence in haemophilia a patients

Haemophilia is associated with reduced bone mass and mineral density. Due to the rarity of the disease and the heterogeneity among the studies, the pathogenesis of bone loss is still under investigation. We studied the effects of coagulation factors on bone cells and characterized in a pilot study the osteoclastogenic potential of patients' osteoclast precursors. To evaluate the effect of coagulation factors on osteoclasts, we treated Healthy Donor-Peripheral Blood Mononuclear Cells (HD-PBMC) with Factor VIII (FVIII), von Willebrand Factor (VWF), FVIII/VWF complex, activated Factor IX (FIXa), activated Factor X (FXa) and Thrombin (THB). FVIII, VWF, FVIII/VWF, FXa and THB treatments reduced osteoclast differentiation of HD-PBMC and VWF affected also bone resorption. Interestingly, PBMC isolated from patients with moderate/severe haemophilia showed an increased osteoclastogenic potential due to the alteration of osteoclast precursors. Moreover, increased expression of genes involved in osteoclast differentiation/activity was revealed in osteoclasts of an adult patient with moderate haemophilia. Control osteoblasts treated with the coagulation factors showed that FVIII and VWF reduced ALP positivity; the opposite effect was observed following THB treatment. Moreover, FVIII, VWF and FVIII/VWF reduced mineralization ability. These results could be important to understand how coagulation factors deficiency influences bone remodeling activity in haemophilia.

Gender equity in hemophilia: need for healthcare, familial, and societal advocacy

Hemophilia is a rare bleeding disorder caused by a genetic defect on chromosome X. It is inherited as an X-linked trait, and hence, it is more frequently diagnosed in males, whereas women have been traditionally considered only as carriers of the disease. However, the role of women in families of patients with hemophilia is pivotal. As mothers, sisters, daughters, and female partners of patients with hemophilia, they play a central role in the management of the patient, considering healthcare, social, and familial aspects, but they might be affected by the disease as well, particularly in regions where consanguinity is frequent. This paper aims to explore the involvement of women in hemophilia, including their carrier status, bleeding symptoms, treatment challenges, and psychosocial impact not only related to male patients, but also as patients affected with hemophilia themselves. We advocate health equity, equal access to healthcare for men and women with hemophilia and dedicated resources to improve the unique needs of the women dealing with hemophilia, ultimately leading to improved care and quality of life.

Haemophilia and Fragility Fractures: From Pathogenesis to Multidisciplinary Approach

Haemophilia A (HA) and haemophilia B (HB) are X-linked inherited bleeding disorders caused by the absence or deficiency of coagulation factors VIII (FVIII) and IX (FIX), respectively. Recent advances in the development of effective treatments for haemophilia have led to a significant increase in life expectancy. As a result, the incidence of some comorbidities, including fragility fractures, has increased in people with haemophilia (PWH). The aim of our research was to perform a review of the literature investigating the pathogenesis and multidisciplinary management of fractures in PWH. The PubMed, Scopus and Cochrane Library databases were searched to identify original research articles, meta-analyses, and scientific reviews on fragility fractures in PWH. The mechanism underlying bone loss in PWH is multifactorial and includes recurrent joint bleeding, reduced physical activity with consequent reduction in mechanical load, nutritional deficiencies (particularly vitamin D), and FVIII and FIX deficiency. Pharmacological treatment of fractures in PWH includes antiresorptive, anabolic and dual action drugs. When conservative management is not possible, surgery is the preferred option, particularly in severe arthropathy, and rehabilitation is a key component in restoring function and maintaining mobility. Appropriate multidisciplinary fracture management and an adapted and tailored rehabilitation pathway are essential to improve the quality of life of PWH and prevent long-term complications. Further clinical trials are needed to improve the management of fractures in PWH.

Osteoporosis Remains Constant in Patients with Hemophilia-Long-Term Course in Consideration of Comorbidities

INTRODUCTION

 Patients with hemophilia (PWHs) suffer from an increased risk of osteoporosis. Multiple hemophilia and hemophilic arthropathy associated factors correlate with a low bone mineral density (BMD) in PWHs. The aim of this study was to assess the long-term development of BMD in PWH as well as to analyze potentially influencing factors.

METHODS

 A total of 33 adult PWHs were evaluated in a retrospective study. General medical history, specific-hemophilia-associated comorbidities, joint status using the Gilbert score, calcium level, and vitamin D level as well as at least two results of bone density measurements with a minimum range of 10 years per patient were taken into account.

RESULTS

 The BMD did not change significantly from one point of measurement to the other. A total of 7 (21.2%) cases of osteoporosis and 16 (48.5%) cases of osteopenia were identified. The two following significant correlations could be revealed: the higher the patients' body mass index, the higher their BMD (r = 0.41; p = 0.022). Moreover, a high Gilbert score came along with a low BMD (r = -0.546; p = 0.003).

CONCLUSION

 Even if PWHs frequently suffer from a reduced BMD, our data suggest that their BMD remains constant on a low level in the course of time. A risk factor of osteoporosis often found in PWHs is a vitamin D deficiency and joint destruction. Therefore, a standardized screening of PWHs on BMD reduction by collecting vitamin D blood level and assessing joint status seems appropriate.

Intra-articular injection of platelet-rich plasma in patients with hemophilia and painful knee joint cartilage degeneration

INTRODUCTION

Knee arthropathy causes pain to people with hemophilia (PWH). One of the current controversies is whether injections of intra-articular platelet-rich plasma (PRP) are effective in relieving the knee pain of PWH.

AREAS COVERED

A narrative literature review was conducted on the efficacy of PRP injections in the knees of PWH.

EXPERT OPINION

Intra-articular PRP knee injections are widely used in patients with knee osteoarthritis to relieve pain and delay total knee arthroplasty. Although numerous publications have supported the use of PRP in knee osteoarthritis, there is still major controversy regarding its true usefulness, given that a number of studies with a high degree of evidence have failed to show the efficacy of PRP. With respect to painful hemophilic arthropathy, the use of PRP injections is even more controversial, as there are only four publications on the subject supporting the use of PRP in hemophilia, all of them with a low degree of evidence. A publication with grade 1 evidence recommended against the use of PRP in hemophilic arthropathy because its efficacy has not been demonstrated. My opinion is that intra-articular PRP injections should not be used in hemophilia until there is more evidence of its benefits.

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.

The Profile of Markers of Bone Turnover, Inflammation and Extracellular Neutrophil Traps on Bone Mass in Haemophilia and the Development of Haemophilic Arthropathy

Background: The aim of the study is to evaluate selected biomarkers of bone turnover, inflammation, neutrophil trap and factors predisposing haemophiliacs to bone loss, and to analyse their relationship with clinical features, treatment and complications. Methods: The levels of interleukin 6 (IL-6); citrullinated histone (CH3); osteocalcin (BGLAP); bone alkaline phosphatase (BALP); N-terminal procollagen type I propeptide (P1NP); and C-terminal collagen type I telopeptide (C1CP) were examined in 60 patients with haemophilia. Results: The cut-off value for BGLAP is 26.41 ng/mL, and 929.7 pg/mL for CH3. There is a statistically significant difference between BGLAP, BALP, C1CP and CH3 concentrations, depending on the prophylaxis used. The median concentration of BGLAP in patients taking the factor on demand is 28.0 ng/mL, BALP 322.5 U/L, C1CP 191.2 ng/mL and CH3 1114.4 pg/mL. In patients taking recombinant coagulation factor VIII/IX as prophylaxis of bleeding, the median BGLAP concentrations are 35.9 ng/mL, BALP 280.9 U/L, C1CP 161.6 ng/mL and CH3 952.5 pg/mL. BGLAP and BALP concentrations are dependent on the development of haemophilic arthropathic. Conclusions: The concentrations of selected markers of bone turnover and NETs may help to identify patients at particular risk of developing haemophilic arthropathy and bone metabolic turnover abnormalities.

Osteoporosis in hemophilia: what is its importance in clinical practice?

INTRODUCTION

The relationship between severe hemophilia and osteoporosis has been well established in the literature. However, although the importance of its prevention in order to reduce the risk of bone fractures has been reported, the importance of its treatment in clinical practice has not been well analyzed.

AREAS COVERED

In this paper a review of the available clinical and experimental information on osteoporosis in hemophilia has been performed, to better understand the relationship between hemophilia and osteoporosis. Prevention of osteoporosis in hemophilia should include primary hematological prophylaxis; a diet appropriate in calcium and vitamin D; a regular exercise program that includes aerobics, strength training and balance and flexibility activities; restriction of tobacco and alcohol use; and limitation of the duration of immobilization.

EXPERT OPINION

Prevention of osteoporosis in hemophilic patients is paramount. However, it is noteworthy that there is only one publication on the treatment of osteoporosis in patients with hemophilia. Until further research is done on this topic, the existing recommendations for non-hemophilic patients should be followed. They include the use of antiresorptives (estrogens, selective estrogen receptor modulators, bisphosphonates, denosumab) and anabolic agents (teriparatide, abaloparatide, romosozumab). Further studies on the management of osteoporosis in patients with hemophilia are required.

Health issues in women and girls affected by haemophilia with a focus on nomenclature, heavy menstrual bleeding, and musculoskeletal issues

Introduction

Women and girls affected by haemophilia, including haemophilia carriers (WGH) are at risk of bleeding symptoms that may go unrecognized, including heavy menstrual bleeding (HMB) and musculoskeletal bleeding. Terminology continues to evolve.

Aim

To describe the current recommendations for nomenclature surrounding WGH, and the current understanding of HMB, iron deficiency, and musculoskeletal complaints in these patients.

Methods

Literature was reviewed and summarized.

Results

With regards to nomenclature, women with factor levels less than 50% should be classified as having haemophilia, while carriers with normal levels should be characterized accordingly to symptomatology. HMB and resultant iron deficiency are common among WGH, have a multitude of downstream effects, and maybe overlooked due to stigma around menstruation. Musculoskeletal bleeding and resultant joint changes are increasingly recognized in this population but do not necessarily correlate with factor levels.

Conclusion

Although progress has been made in the care of WGH, much work remains to further improve their care.

Osteoporosis management and falls prevention in patients with haemophilia: Review of haemophilia guidelines

INTRODUCTION

Patients with haemophilia (PWH) have a high prevalence of osteoporosis, falls and fractures at all ages. The role of haemophilia itself may contribute to low bone mineral density (BMD) due to coagulation factor deficiency. Guidelines for the management of osteoporosis, fracture and fall risk may help to reduce fracture and fall risk, and delay osteoporosis onset.

AIM

We aim to review current haemophilia guidelines regarding osteoporosis prevention, screening, diagnosis and management, and fall prevention.

METHOD

A database search (Ovid MEDLINE) revealed two haemophilia guidelines (World and British) published within the last ten years. Local Australian haemophilia guidelines were identified through a manual search.

RESULTS

All haemophilia guidelines were found to contain inadequate recommendations for osteoporosis management and fall prevention due to a lack of evidence in the literature.

CONCLUSION

Further studies are required to assess the trajectory of bone health in PWH, the mechanism of bone loss in PWH, and the effectiveness of weight-bearing exercises, interventions for fall prevention, screening programmes, and use of anti-osteoporosis medications in PWH across the lifecourse.

Low Bone Mineral Density in Hemophiliacs

Objective

To review the current knowledge on bone health in patients with hemophilia A and the underlying pathogenetic mechanisms.

Data Sources

Original research articles, meta-analyses, and scientific reviews.

Data Synthesis

Already in childhood, patients with hemophilia A are prone to low bone mineral density, leading to osteopenia and/or osteoporosis. Initially associated with the life style of hemophilia, today we are faced with accumulating evidence that coagulation factor VIII is involved directly or indirectly in bone physiology.

Conclusion

Understanding the role of factor VIII and the mechanisms of decreased bone mineral density in hemophilia A is critically important, especially as non-factor replacement therapies are available, and treatment decisions potentially impact bone health.

Therapeutic Effects of Kefir Peptides on Hemophilia-Induced Osteoporosis in Mice With Deficient Coagulation Factor VIII

Osteoporosis is a clinically prevalent comorbidity in patients with hemophilia. A preventive effect of kefir peptides (KPs) on postmenopausal osteoporosis has been proved. The aim of this study was to evaluate the therapeutic effect of KPs for the treatment of osteoporosis in coagulation factor VIII (FVIII) gene knockout mice (F8KO), a model of hemophilia A. In this study, male F8KO mice at 20 weeks of age were orally administered different doses of KPs for 8 weeks. The therapeutic effects of KPs were shown in the femoral trabeculae and the 4th lumbar vertebrae, which increased the trabecular bone mineral density (BMD), bone volume (Tb.BV/TV), and trabecular number (Tb.N) and decreased the trabecular separation (Tb.Sp), and they were also observed in the femoral cortical bones, in which the mechanical properties were enhanced in a dose-dependent manner. Characterization of receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), and interleukin 6 (IL-6) demonstrated that the serum RANKL/OPG ratio and IL-6 levels were significantly decreased in the F8KO mice after the KP treatment. Tartrate-resistant acid phosphatase (TRAP) staining of mature osteoclasts indicated that the therapeutic effect of KPs in F8KO mice was associated with the functions of KPs to inhibit RANKL-induced osteoclastogenesis by reducing serum RANKL/OPG ratio and IL-6 secretion. The present study is the first to address the potentials of KPs for the treatment of hemophilia-induced osteoporosis in mice and it also provides useful information for the application of KPs as a complementary therapy for the treatment of osteoporosis in hemophilic patients.

Deletion of Coagulation Factor IX Compromises Bone Mass and Strength: Murine Model of Hemophilia B (Christmas Disease)

Osteopenia and osteoporosis have increasingly become a recognized morbidity in those persons with hemophilia (PwH) receiving inadequate prophylactic clotting factor replacement. Animal models can control or eliminate genetic and environmental factors and allow for invasive testing not clinically permissible. Here, we describe the skeletal phenotype of juvenile and adult male mice with a genetically engineered deficiency in coagulation factor IX (FIX KO). Although the somatic growth of FIX KO mice matched that of their wild-type (WT) littermates at 10 and 20 weeks of age, the FIX KO mice displayed reduced bone mineral density (BMD), reduced cortical and cancellous bone mass, and diminished whole bone fracture resistance. These findings coupled with parallel observations in a murine model of hemophilia A (FVIII deficiency) point to an effector downstream of the coagulation cascade that is necessary for normal skeletal development. Further study of potential mechanisms underlying the bone disease observed in rare clotting factor deficiency syndromes may lead to new diagnostic and therapeutic insights for metabolic bone diseases in general.

The Bone Microarchitecture Deficit in Patients with Hemophilia Is Influenced by Arthropathy, Hepatitis C Infection, and Physical Activity

Low bone mineral density (BMD) is common in patients with hemophilia (PWHs). The aim of the present study was to describe BMD and microarchitecture in PWHs in Northern Germany and to determine factors contributing to possible skeletal alterations. Demographic characteristics, BMD and microarchitecture, bone metabolism markers, and orthopaedic joint score (OJS) were assessed during routine check-ups. Areal BMD was assessed by dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine. Volumetric BMD and microarchitecture were quantified by high-resolution peripheral quantitative computed tomography at the distal radius and tibia. Eighty male PWHs (median age, 33 years; range, 18-77) were retrospectively analyzed, of whom 67 (84.0%) and 13 (16.0%) had hemophilia A and B, respectively. Fifty-four (68.0%), six (7.0%), and 20 (25.0%) patients had severe, moderate, or mild hemophilia, and 35 (44.0%) were hepatitis C virus (HCV) positive. DXA analysis revealed low BMD (Z-score ≤ - 2.0) in 27.5% of PWHs, and higher bone turnover values were associated with lower BMD. Bone microarchitecture was dominated by cortical deficits at the radius and trabecular deficits at the tibia. Cortical deficits at the radius were influenced by lower body mass index, low-grade inflammation, and treatment regimen (higher cortical thickness on primary prophylaxis). Trabecular alterations at the tibia were mainly associated with OJS and HCV status. A positive effect of self-reported sportive activity on BMD could be shown. In conclusion, our findings demonstrate that the site-specific microarchitectural deficit observed in PWHs is primarily negatively influenced by poor joint status, inflammation, HCV infection, and high bone turnover.

FVIII at the crossroad of coagulation, bone and immune biology: Emerging evidence of biological activities beyond hemostasis

Hemophilia A is an X-linked hereditary disorder that results from deficient coagulation factor VIII (FVIII) activity, leading to spontaneous bleeding episodes, particularly in joints and muscles. FVIII deficiency has been associated with altered bone remodeling, dysregulated macrophage polarization, and inflammatory processes that are associated with the neoformation of abnormal blood vessels. Treatment based on FVIII replacement can lead to the development of inhibitors that render FVIII concentrate infusion ineffective. In this context, hemophilia has entered a new therapeutic era with the development of new drugs, such as emicizumab, that seek to restore the hemostatic balance by bypassing pathologically acquired antibodies. We discuss the potential extrahemostatic functions of FVIII that may be crucial for defining future therapies in hemophilia.

Mechanisms of Bone Remodeling Disorder in Hemophilia

Hemophilia is caused by a lack of antihemophilic factor(s), for example, factor VIII (FVIII; hemophilia A) and factor IX (FIX; hemophilia B). Low bone mass is widely reported in epidemiological studies of hemophilia, and patients with hemophilia are at an increased risk of fracture. The detailed etiology of bone homeostasis imbalance in hemophilia is unclear. Clinical and experimental studies show that FVIII and FIX are involved in bone remodeling. However, it is likely that antihemophilic factors affect bone biology through thrombin pathways rather than via their own intrinsic properties. In addition, among patients with hemophilia, there are pathophysiological processes in several systems that might contribute to bone loss. This review summarizes studies on the association between hemophilia and bone remodeling, and might shed light on the challenges facing the care and prevention of osteoporosis and fracture in patients with hemophilia.

Biomarkers of bone disease in persons with haemophilia

INTRODUCTION

Persons with haemophilia (PwH) have abnormally low bone density and increased risk of fractures. We previously demonstrated decreased skeletal health in factor VIII (FVIII)-deficient mice. Thus, we hypothesized factor deficiency is an independent risk factor for decreased skeletal health.

AIM

We seek to identify differences in bone-related cytokine expression among PwH and healthy controls.

METHODS

We evaluated plasma samples from 79 participants with severe FVIII deficiency and 51 age-matched healthy controls. Plasma samples were assessed for RANKL and OPG, cytokines that regulate bone metabolism, and CTX-1, a biomarker for bone resorption, as well as 10 bone-related cytokines.

RESULTS

CTX-1 is higher among samples from FVIII-deficient participants compared to controls (P < .01) but not among participants with recent factor use (within 24 hours of sample collection) (P = .21). Among PwH greater than 16 years of age (PwH ≥ 16), OPG is increased with recent factor use (P < .01) but not without (P = .34). Lower levels of TNF-α (P < .01), interleukin (IL)-12 (P < .01) and IL-10 (P < .001) were found among samples from PwH. Controlling for subject age, IL-12 and IL-10 levels are lower in PwH ≥ 16 (P < .01, P < .001) but not PwH under 16 (PwH < 16) (P > .05). Levels of TNF-α were lower among PwH < 16 only (P < .05). These differences are not observed in participants with recent factor use.

CONCLUSIONS

In PwH, markers of bone metabolism and circulating cytokine levels are abnormal. Recent factor use reverses many of these differences suggesting FVIII replacement ameliorates this pathology. This study suggests bone disease present in PwH is intrinsic to FVIII deficiency.

Low bone mass and hypovitaminosis D in haemophilia: A single-centre study in patients with severe and moderate haemophilia A and B

INTRODUCTION

Haemophilia (H) is frequently associated with a multifactorial reduction in bone mineral density (BDM), but little is known about possible differences between HA and HB according to their severity.

AIM

To evaluate the association between low bone mineral density (BMD), 25-hydroxyvitamin D [25(OH)D] concentrations and bone turnover markers in patients with HA and HB younger or older than 50 years.

METHODS

In 78 patients <50 years and 33 patients >50 years with severe (S) or moderate (M) HA and HB, BMD was measured by dual-energy X-ray absorptiometry at femoral neck (FN) and lumbar spine and then correlated to annual bleeding rate (ABR), World Federation of Haemophilia orthopaedic joint scale (WFH score), 25(OH)D concentrations, parathyroid hormone (PTH), amino-terminal telopeptide of type 1 collagen (NTx), urinary pyridinolines, osteocalcin and bone-specific alkaline phosphatase.

RESULTS

Overall, a high prevalence of hypovitaminosis D was diagnosed. In patients <50 years, low FN-BMD was significantly more frequent in HA than in HB, while PTH, pyridinolines, ABR and WFH score were associated with H type and severity. In patients >50 years, similarly low FN-BMD was observed in HA and HB, while ABR and WFH score were associated with H type and severity, being milder in HB.

CONCLUSIONS

Low bone mass is a frequent comorbidity in haemophilic patients of all ages, apart from those with MHB. Clinical and laboratory assessments confirm a higher bone impairment and faster bone resorption in HA compared with HB. Looking at H type and severity, MHB seems to have a normal bone metabolism and a less severe disease.

Switching patients in the age of long-acting recombinant products?

Introduction: Prophylaxis with factor replacement therapy is the gold standard for the treatment of hemophilia, but this often requires frequent infusions. A number of long-acting factor products have been developed to reduce the burden on patients. Areas covered: This is an overview of information presented at two symposia held at the World Federation of Hemophilia and International Society on Thrombosis and Haemostasis - Scientific and Standardization Committee annual meetings. The pharmacokinetic, safety and efficacy data for long-acting recombinant products are reviewed, with a focus on recombinant factor IX albumin fusion protein (rIX-FP) and rVIII-SingleChain. This overview also provides a guide for managing a patient's switch to long-acting products. Expert opinion: Long-acting products may allow patients to maintain or decrease bleeding rates whilst increasing their dosing interval, which may in turn reduce the burden on patients and caregivers. When switching patients to long-acting products health-care professionals should provide balanced and thorough education to the patient, whilst supporting their emotional well-being. Regimens should address patients' needs and goals but should also be guided by clinical phenotype and pharmacokinetic assessment. Follow-up should assess safety concerns, bleeding rates, joint health and the impact of the regimen on patients' lifestyle.

Management of comorbidities in haemophilia

With the introduction of clotting factor concentrates in the early 1970s, significant improvements in quality of life and life expectancy of persons with haemophilia (PWH) were realized. Unfortunately, as a result of transmission of HIV and hepatitis C virus (HCV) by contaminated concentrates in the 1980s, many of these gains were lost. Now with four decades of PWH unexposed to contaminated factor products and current treatments capable of suppressing and eliminating HIV and HCV, respectively, the survival rate is once again increasing. In addition to the usual comorbidities associated with advanced age in the general population, several specific issues occur in patients with bleeding disorders. This manuscript explores the incidence and management of the comorbidities of the ageing PWH with a focus on cardiovascular disease and osteoporosis.

Reduced bone formation in males and increased bone resorption in females drive bone loss in hemophilia A mice

Hemophilia A (HA), a rare X-linked recessive genetic disorder caused by insufficient blood clotting factor VIII, leaves affected individuals susceptible to spontaneous and traumatic hemorrhage. Although males generally exhibit severe symptoms, due to variable X inactivation, females can also be severely impacted. Osteoporosis is a disease of the skeleton predisposing patients to fragility fracture, a cause of significant morbidity and mortality and a common comorbidity in HA. Because the causes of osteoporosis in HA are unclear and in humans confounded by other traditional risk factors for bone loss, in this study, we phenotyped the skeletons of F8 total knockout (F8 ^TKO) mice, an animal model of severe HA. We found that trabecular bone accretion in the axial and appendicular skeletons of male F8 ^TKO mice lagged significantly between 2 and 6 months of age, with more modest cortical bone decline. By contrast, in female mice, diminished bone accretion was mostly limited to the cortical compartment. Interestingly, bone loss was associated with a decline in bone formation in male mice but increased bone resorption in female mice, a possible result of sex steroid insufficiency. In conclusion, our studies reveal a sexual dimorphism in the mechanism driving bone loss in male and female F8 ^TKO mice, preventing attainment of peak bone mass and strength. If validated in humans, therapies aimed at promoting bone formation in males but suppressing bone resorption in females may be indicated to facilitate attainment of peak mass in children with HA to reduce the risk for fracture later in life.

Osteoporosis in Patients With Hemophilia: Single-Center Results From a Middle-Income Country

Increased number of patients with hemophilia have been identified to have osteoporosis at early ages. Low bone mineral density in the setting of hemophilia has been associated with decreased mobility, sedentary life style, on demand treatment or delayed prophylaxis, low body weight and viral infections. The aim of this study was to investigate the impact of hemophilia on bone health of adult patients living in a middle income country. A total of 61 adult patients with hemophilia who were followed at the Hematology Department of Cerrahpaşa Medical Faculty, Istanbul University-Cerrahpaşa were consecutively included in this study. Bone health of the patients was assessed using the bone mineral density (BMD) and vitamin D levels. Z and t scores are used for evaluation of BMD in patients with hemophilia aged < 50 and ≥ 50 years, respectively. Information on treatment and co-morbidities including viral diseases were obtained from the medical files of the recruited patients. Bone mineral density was found normal in 30, and low in 29 patients. Vitamin D levels were below 20 ng/ml in 46 patients. No significant relationship was found between the severity of hemophilia and bone density. Vitamin D levels were significantly lower in patients who had a history of joint intervention. Neither annual bleeding rate nor the treatment modality (on demand versus prophylaxis) were associated with the bone mineral density and vitamin D levels. Annual factor consumption was higher in patients whose bone mineral densities was low both in femoral and lumbar regions. The results of this study depicting the situation of adult hemophilia population from a middle income country show that bone mineral density and vitamin D levels were decreased in a considerable amount of patients at early ages.

Bone health in symptomatic carriers of haemophilia A: a protocol for a multicentre prospective matched-cohort study

INTRODUCTION

Haemophilia A is an X linked inherited bleeding disorder, caused by a decrease in coagulation factor VIII. Persons with haemophilia experience repeated musculoskeletal bleeding, which can lead to decreased range of motion, irreversible joint damage, low bone mineral density (BMD), and are at greater risk for osteoporosis. Women heterozygous for this mutation, also known as haemophilia A carriers, can have bleeding symptoms and even experience joint bleeding evidenced by radiological soft tissue and osteochondral changes. The prevalence of low BMD as a risk factor for osteoporosis has never been evaluated in carriers of haemophilia, and given the recent findings which suggest subclinical musculoskeletal bleeding in carrier women, we hypothesise that they too are at risk of impaired bone health.

METHODS AND ANALYSIS

This is a national multicentre prospective matched-cohort study to compare BMD T-scores among symptomatic haemophilia A carriers, 50 years of age or older, with age-matched and body mass index-matched non-carriers (1:1). A total of 40 symptomatic carriers and 40 matched non-carriers will be recruited from St. Michael's Hospital, Kingston General Hospital in Ontario, Canada and Foothills Medical Centre in Alberta, Canada. Multivariable linear regression models will be used to estimate the effect of haemophilia carriership on BMD T-scores, adjusting for age, body mass index and other relevant covariates.

ETHICS AND DISSEMINATION

The protocol was designed and will be conducted in compliance with applicable laws, rules and regulations. Research ethics approval was obtained from St. Michael's Hospital, Foothills Medical Centre, and Kingston General Hospital. Findings will be presented at international venues such as the American Society of Haematology and the World Federation of Haemophilia World Congress. The authors of this study will seek publication in journals such as Blood, Journal of Thrombosis and Haemostasis, American Journal ofHematology and British Journal ofHaematology.

Hemophilia A and B mice, but not VWF-/-mice, display bone defects in congenital development and remodeling after injury

While joint damage is the primary co-morbidity of hemophilia, osteoporosis and osteopenia are also observed. Coagulation factor VIII deficient (FVIII^−/−) mice develop an osteoporotic phenotype in the absence of induced hemarthrosis that is exacerbated two weeks after an induced joint injury. Here we have compared comprehensively the bone health of clotting factor VIII, factor IX, and Von Willebrand Factor knockout (FVIII^−/−, FIX^−/−, and VWF^−/− respectively) mice both in the absence of joint hemorrhage and following induced joint injury. We found FVIII^−/− and FIX^−/− mice, but not VWF^−/− mice, developmentally have an osteoporotic phenotype. Unilateral induced hemarthrosis causes further bone damage in both FVIII^−/− and FIX^−/− mice, but has little effect on VWF^−/− bone health, indicating that the FVIII.VWF complex is not required for normal bone remodeling in vivo. To further investigate the bone healing following hemarthrosis in hemophilia we examined a two week time course using microCT, serum chemistry, and histological analysis. Elevated ratio of osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL), increased osterix⁺ osteoblastic cells, and decreased smoothness of the cortical bone surface were evident within several days of injury, indicative of acute heterotopic mineralization along the cortical surface. This was closely followed by increased interleukin-6 (IL-6) levels, increased osteoclast numbers, and significant trabecular bone loss. Uncoupled and disorganized bone formation and resorption continued for the duration of the study resulting in significant deterioration of the joint. Further elucidation of the shared mechanisms underlying abnormal bone homeostasis in the absence of FVIII or FIX is needed to guide evidence-based approaches to the screening and treatment of the prevalent bone defects in hemophilia A and B.

Risk of osteoporotic fractures as a consequence of haemophilia: A nationwide population-based cohort study

AIM

Low bone mineral density occurs more commonly in patients with haemophilia (PWH) than the general population. However, the risk of haemophilia-related osteoporotic fractures has not been well established. We aim to explore the relationship between haemophilia and the development of osteoporotic fractures following haemophilia.

METHODS

This was a nationwide population-based cohort study based on the data in the Taiwan National Health Insurance Research Database (TNHIRD). Patients who were diagnosed with haemophilia were selected. A comparison cohort was formed of patients without haemophilia who were matched according to age and sex. The incidence rate and the hazard ratios (HRs) of new-onset osteoporotic fractures were calculated for both cohorts.

RESULTS

The haemophilia cohort consisted of 75 patients, and the comparison cohort comprised 300 matched control patients without haemophilia. The risk of osteoporotic fractures was higher in the haemophilia cohort than in the comparison cohort (HR = 5.41, 95% confidence interval [CI] = 2.42-12.1, P < 0.001). After adjustments for age, sex, comorbidities, urbanizations and socio-economic status, PWH were 4.37 times more likely to develop osteoporotic fractures (95% CI = 1.88-10.17, P = 0.001) as compared to matched cohort. In addition, the incidence of newly diagnosed osteoporotic fractures was significantly increased after 5-year follow-up durations.

CONCLUSION

Though our study by TNHIRD presented methodologic flaws by its design nature, we observed that haemophilia may increase the risk of osteoporotic fractures and the cumulative incidence was significantly higher for PWH diagnosed more than 5 years. Clinicians should pay particular attention to osteoporotic fractures following haemophilia in PWH as they age.

Blood-induced bone loss in murine hemophilic arthropathy is prevented by blocking the iRhom2/ADAM17/TNF-α pathway

Hemophilic arthropathy (HA) is a debilitating degenerative joint disease that is a major manifestation of the bleeding disorder hemophilia A. HA typically begins with hemophilic synovitis that resembles inflammatory arthritides, such as rheumatoid arthritis, and frequently results in bone loss in patients. A major cause of rheumatoid arthritis is inappropriate release of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) by the TNF-α convertase (TACE; also referred to as ADAM17) and its regulator, iRhom2. Therefore, we hypothesized that iRhom2/ADAM17-dependent shedding of TNF-α also has a pivotal role in mediating HA. Here, we show that addition of blood or its components to macrophages activates iRhom2/ADAM17-dependent TNF-α shedding, providing the premise to study the activation of this pathway by blood in the joint in vivo. For this, we turned to hemophilic FVIII-deficient mice (F8-/- mice), which develop a hemarthrosis following needle puncture injury with synovial inflammation and significant osteopenia adjacent to the affected joint. We found that needle puncture-induced bleeding leads to increased TNF-α levels in the affected joint of F8-/- mice. Moreover, inactivation of TNF-α or iRhom2 in F8-/- mice reduced the osteopenia and synovial inflammation that develops in this mouse model for HA. Taken together, our results suggest that blood entering the joint activates the iRhom2/ADAM17/TNF-α pathway, thereby contributing to osteopenia and synovitis in mice. Therefore, this proinflammatory signaling pathway could emerge as an attractive new target to prevent osteoporosis and joint damage in HA patients.

Von Willebrand disease in the elderly: clinical perspectives

Von Willebrand disease (VWD) is an inherited bleeding disorder that affects up to 1% of the population. In most cases, VWD results from a mutation in the von Willebrand Factor (VWF) gene, which alters the amount and function of VWF, a key glycoprotein in both primary and secondary hemostasis. A comprehensive analysis of patients with VWD should include VWF activity, antigen levels, platelet function, and a careful bleeding history. Treatment options include antifibrinolytics, desmopressin, and VWF replacement therapy. VWF levels fluctuate due to age, stress, environmental exposures, and pharmacologic treatment. Treatment guidelines exist to treat and prevent bleeding for patients undergoing surgery and medical procedures, but often these must be reevaluated in the setting of age-related comorbidities including cardiovascular events, venous thrombosis, and malignancy. In addition, many age-related complications are associated with a secondary acquired von Willebrand syndrome (AVWS), including malignancies, hypothyroidism, cardiovascular diseases, and cardiac replacement devices. The current literature is limited by a lack of older patients in clinical trials. Larger studies are needed to determine if age-related comorbidities affect VWD patients at different frequencies than the general elderly population. There is also a significant need for registry-based studies to evaluate many age-related comorbidities in VWD patients.

Impact of target joint and FVIII inhibitor οn bone properties in children with haemophilia A: A peripheral quantitative computed tomography study

BACKGROUND

Haemophilic children are prone to low bone mass accrual.

OBJECTIVE

To assess bone properties in haemophilic children, using peripheral quantitative computed tomography (pQCT) and to correlate findings with clinical data.

SUBJECTS/METHODS

Peripheral quantitative computed tomography scan of both radii and tibiae were performed in 31 haemophilic A children (severe 24, mean age 11.2 years). Seven subjects had a history of inhibitors. Five children had an upper extremity target-joint and 12 had at least one lower extremity target-joint. The following parameters were measured: trabecular, total and cortical bone density and content (TBD, ToBD, CBD, TbC, CC), strength-stress index (SSI), and tibial cross-sectional area (CA), outer and inner bone contour length (PERI, ENDO) and cortical thickness (CTHC).

RESULTS

Mean right radius TBD was significantly higher than the left one (P = 0.015). In subjects with arm target-joint, radius TBD was significantly lower in the target than in non-target arm (186.6 ± 60.4 vs 218.6 ± 39.8, P = 0.032). Left arm target-joint subjects had significantly lower left radius TBD in comparison to subjects without arm target-joint (155.4 ± 50.3 vs 215.7 ± 37.9, P = 0.019). There were no similar differences in leg target-joint. Bone quality and geometry parameters in cortical compartment were significantly lesser in inhibitor group, with statistically significant side-to-side differences for legs and arms and left side predominance.

CONCLUSION

In children with haemophilia A and a history of target-joint and/or FVIII inhibitor, abnormalities may occur in the long bones as were revealed by pQCT, where low trabecular density and weak cortical bone quality in upper and lower extremities, respectively, were confirmed.

Increased bone resorption in hemophilia

In patients with hemophilia, osteoporosis is frequently observed for which the etiology remains unclear. The aim of this paper is to review the available experimental evidence indicating the presence of this disorder in patients with hemophilia, explore the potential mechanisms which may lead to reduced bone mineral density (BMD) and speculate on useful interventions to circumvent it. A narrative review of the English literature up to April 2018 was performed. The available evidence demonstrates an increased rate of bone resorption and an excess of osteoporosis among patients with hemophilia. FVIII and FIX may act through at least two pathways: promoting bone formation by a thrombin-mediated mitogenic effect on osteoblasts and by cytokine-mediated osteoclast activity. Another potential indirect mechanism mediated through the RANK-RANKL pathway has been suggested but remains controversial. The role of confounders such as lack of activity and immobility must be considered.

Abnormal joint and bone wound healing in hemophilia mice is improved by extending factor IX activity after hemarthrosis

Wound healing requires interactions between coagulation, inflammation, angiogenesis, cellular migration, and proliferation. Healing in dermal wounds of hemophilia B mice is delayed when compared with hemostatically normal wild-type (WT) mice, with abnormal persistence of iron deposition, inflammation, and neovascularity. We observed healing following induced joint hemorrhage in WT and factor IX (FIX) knockout (FIX^-/-) mice, examining also parameters previously studied in an excisional skin wound model. Hemostatically normal mice tolerated this joint bleeding challenge, cleared blood from the joint, and healed with minimal pathology, even if additional autologous blood was injected intra-articularly at the time of wounding. Following hemarthrosis, joint wound healing in hemophilia B mice was impaired and demonstrated similar abnormal histologic features as previously described in hemophilic dermal wounds. Therefore, studies of pathophysiology and therapy of hemophilic joint bleeding performed in hemostatically normal animals are not likely to accurately reflect the healing defect of hemophilia. We additionally explored the hypothesis that the use of a FIX replacement protein with extended circulating FIX activity could improve synovial and osteochondral wound healing in hemophilic mice, when compared with treatment with unmodified recombinant FIX (rFIX) in the established joint bleeding model. Significantly improved synovial wound healing and preservation of normal osteochondral architecture are achieved by extending FIX activity after hemarthrosis using glycoPEGylated FIX when compared with an equivalent dose of rFIX. These results suggest that treating joint bleeding only until hemostasis is achieved may not result in optimal joint healing, which is improved by extending factor activity.

Influence of body weight on bone mass, architecture and turnover

Weight-dependent loading of the skeleton plays an important role in establishing and maintaining bone mass and strength. This review focuses on mechanical signaling induced by body weight as an essential mechanism for maintaining bone health. In addition, the skeletal effects of deviation from normal weight are discussed. The magnitude of mechanical strain experienced by bone during normal activities is remarkably similar among vertebrates, regardless of size, supporting the existence of a conserved regulatory mechanism, or mechanostat, that senses mechanical strain. The mechanostat functions as an adaptive mechanism to optimize bone mass and architecture based on prevailing mechanical strain. Changes in weight, due to altered mass, weightlessness (spaceflight), and hypergravity (modeled by centrifugation), induce an adaptive skeletal response. However, the precise mechanisms governing the skeletal response are incompletely understood. Furthermore, establishing whether the adaptive response maintains the mechanical competence of the skeleton has proven difficult, necessitating the development of surrogate measures of bone quality. The mechanostat is influenced by regulatory inputs to facilitate non-mechanical functions of the skeleton, such as mineral homeostasis, as well as hormones and energy/nutrient availability that support bone metabolism. Although the skeleton is very capable of adapting to changes in weight, the mechanostat has limits. At the limits, extreme deviations from normal weight and body composition are associated with impaired optimization of bone strength to prevailing body size.

Haemophilia A and B as a cause for secondary osteoporosis and increased fracture risk

Despite the increasing evidence regarding its association with low bone mineral density (BMD) both in adults and children, haemophilia A or B has not yet been considered among the classic causes of secondary osteoporosis. Although the exact mechanisms are not fully elucidated, physical inactivity and vitamin D deficiency seem to play a fundamental role for such an association. Viral infections and arthropathy further compromise bone mass. Except for low BMD, patients with haemophilia seem to be at increased risk for fracture and falls. The FRAX tool may be of value in this population, for the estimation of fracture risk. Regular exercise, prophylactic factor replacement therapy in severe haemophilia, fall prevention strategies and optimization of calcium and vitamin D intake are recommended. In any case, individualized multidisciplinary approach and careful assessment and management of fracture risk are recommended.

Joint bleeding in factor VIII deficient mice causes an acute loss of trabecular bone and calcification of joint soft tissues which is prevented with aggressive factor replacement

While chronic degenerative arthropathy is the main morbidity of haemophilia, a very high prevalence of low bone density is also seen in men and boys with haemophilia. This study investigates bone degradation in the knee joint of haemophilic mice resulting from haemarthrosis and the efficacy of aggressive treatment with factor VIII in the period surrounding injury to prevent bone pathology. Skeletally mature factor VIII knock-out mice were subjected to knee joint haemorrhage induced by puncture of the left knee joint capsule. Mice received either intravenous factor VIII treatment or placebo immediately prior to injury and at hours 4, 24, 48, 72 and 96 after haemorrhage. Mice were killed 2-weeks after injury and the joint morphology and loss of bone in the proximal tibia was assessed using microCT imaging. Quantitative microCT imaging of the knee joint found acute bone loss at the proximal tibia following injury including loss of trabecular bone volumetric density and bone mineral density, as well as trabecular connectivity density, number and thickness. Unexpectedly, joint injury also resulted in calcification of the joint soft tissues including the tendons, ligaments, menisci and cartilage. Treatment with factor VIII prevented this bone and soft tissue degeneration. Knee joint haemorrhage resulted in acute changes in adjacent bone including loss of bone density and mineralization of joint soft tissues. The rapid calcification and loss of bone has implications for the initiation and progression of osteoarthritic degradation following joint bleeding.