Discontinuing early prophylaxis in severe haemophilia leads to deterioration of joint status despite low bleeding rates.

Prophylaxis is the recommended treatment for children with severe haemophilia A, but whether prophylaxis should be continued in adulthood is still under debate. Previous studies with limited follow-up have suggested that some patients may be able to stop prophylaxis in adulthood, while maintaining good joint health. This single-centre observational cohort study examined patients with severe haemophilia A born 1970-1988 without inhibitor development, and assessed the long-term consequences of discontinuing prophylaxis. Patient-initiated changes in prophylaxis, including all switches to on-demand treatment lasting a minimum of two consecutive weeks, were recorded from the time self-infusion began until the last evaluation. Sixty-six patients were evaluated at a median age of 32.4 years: 26 % of patients had stopped prophylaxis for a median of 10 years, 15 % had interrupted prophylaxis and 59 % had continued prophylaxis. Annual joint bleeding rate (AJBR), Haemophilia Joint Health Score (HJHS-2.1; 0-124 points), radiological Pettersson score (0-78 points) and Haemophilia Activities List score (HAL; 100-0 points) were compared between patients who stopped and patients who continued prophylaxis. Although self-reported bleeding rates and functional limitations were similar in both groups (AJBR: 1.5 vs 1.2 and HAL: 84 vs 84 for those who stopped and continued prophylaxis, respectively), objective assessment of joint status showed increased arthropathy after 10 years of on-demand treatment in patients who stopped prophylaxis compared with those who continued (HJHS: 23 vs. 14 and Pettersson: 16 vs 5, respectively; P< 0.01). These results support continuation of long-term prophylaxis in adults and demonstrate the need for objective monitoring of joint status.

IL-1ß, in contrast to TNFα, is pivotal in blood-induced cartilage damage and is a potential target for therapy.

Joint bleeding after (sports) trauma, after major joint surgery, or as seen in hemophilia in general leads to arthropathy. Joint degeneration is considered to result from the direct effects of blood components on cartilage and indirectly from synovial inflammation. Blood-provided proinflammatory cytokines trigger chondrocytes and induce the production of cartilage-degrading proteases. In the presence of erythrocyte-derived iron, cytokines stimulate radical formation in the vicinity of chondrocytes inducing apoptosis. To unravel the role of interleukin (IL) 1ß and tumor necrosis factor (TNF) α in the pathogenesis of this blood-induced cartilage damage, the effect of antagonizing these cytokines was examined in human in vitro cultures. Addition of recombinant human IL-1ß monoclonal antibody or IL-1 receptor antagonist resulted in a dose- and time-dependent protection of cartilage from blood-induced damage. In higher concentrations, almost complete normalization of cartilage matrix proteoglycan turnover was achieved. This was accompanied by a reduction in IL-1ß and IL-6 production in whole blood cultures, whereas TNFα production remained unaffected. Interestingly, addition of a TNFα monoclonal antibody, although demonstrated to inhibit the direct (transient) effects of TNFα on cartilage, exhibited no effect on blood-induced (prolonged) cartilage damage. It is demonstrated that IL-1ß is crucial in the development of blood-induced joint damage, whereas TNFα is not. This hierarchical position of IL-1ß in blood-induced joint damage warrants studies on targeting IL-1ß to potentially prevent joint degeneration after a joint bleed.

The detrimental effects of iron on the joint: a comparison between haemochromatosis and haemophilia.

Joint damage due to (recurrent) joint bleeding in haemophilia causes major morbidity. Although the exact pathogenesis has not been fully elucidated, a central role for iron is hypothesised. Likewise, in hereditary haemochromatosis joint destruction is caused by iron overload. A comparison between these types of arthropathy could provide more insight in the influence of iron in inducing joint damage. A literature review was performed to compare both disorders with respect to their clinical and histological characteristics, and preclinical studies on the influence of iron on different joint components were reviewed. Similarities in the features of arthropathy in haemochromatosis and haemophilia are cartilage degeneration, subchondral bone changes with osteophyte and cyst formation, and osteoporosis. In both disorders synovial inflammation and proliferation are seen, although this is much more explicit in haemophilia. Other substantial differences are the age at onset, the occurrence of chondrocalcinosis radiographically and calcium pyrophosphate dihydrate deposition disease in haemochromatosis, and a rapid progression with joint deformity and neovascularisation in haemophilia. Preclinical studies demonstrate detrimental effects of iron to all components of the joint, resulting in synovial inflammation and hyperplasia, chondrocyte death, and impaired osteoblast function. These effects, particularly the synovial changes, are aggravated in the presence of a pro-inflammatory signal, which is prominent in haemophilic arthropathy and minimal in haemochromatosis. Additional research is needed to further specify the role of iron as a specific target in treating these types of arthropathy.

Deferasirox limits cartilage damage following haemarthrosis in haemophilic mice.

Joint bleeds in haemophilia result in iron-mediated synovitis and cartilage damage. It was evaluated whether deferasirox, an iron chelator, was able to limit the development of haemophilic synovitis and cartilage damage. Haemophilic mice were randomly assigned to oral treatment with deferasirox (30 mg/kg) or its vehicle (control) (30 mg/kg). Eight weeks after start of treatment, haemarthrosis was induced. After another five weeks of treatment, blood-induced synovitis and cartilage damage were determined. Treatment with deferasirox resulted in a statistically significant (p< 0.01) decrease in plasma ferritin levels as compared to the control group (823 ng/ml ± 56 and 1220 ng/ml ±114, respectively). Signs of haemophilic synovitis, as assessed by the Valentino score [range 0 (normal) - 10 (most affected)], were not different (p=0.52) when comparing the control group with the deferasirox group. However, deferasirox treatment resulted in a statistically significant (p< 0.01) reduction in cartilage damage, as assessed by the loss in Safranin O staining [range 0 (normal) - 6 (most affected)], when comparing the deferasirox group with the control group: score 2 (65.4 % vs 4.2 %), score 3 (26.9 % vs 4.2 %), score 4 (7.7 % vs 20.8 %), score 5 (0 % vs 54.2 %), and score 6 (0 % vs 16.7 %). Treatment with deferasirox limits cartilage damage following the induction of a haemarthrosis in haemophilic mice. This study demonstrates the role of iron in blood-induced cartilage damage. Moreover, these data indicate that iron chelation may be a potential prevention option to limit the development of haemophilic arthropathy.

Hemarthrosis in hemophilic mice results in alterations in M1-M2 monocyte/macrophage polarization.

INTRODUCTION: Joint bleedings result in iron-mediated synovitis and cartilage destruction. Monocyte/macrophage polarization affects their role in iron homeostasis. This study evaluates the effects of hemarthrosis on monocyte/macrophage polarization. MATERIALS AND METHODS: Using a murine hemophilia model of acute joint bleeding and flow cytometry, we evaluated monocyte/macrophage polarization in blood, spleen, synovium, and knee lavage at day 1, 2, and 7 following the induction of hemarthrosis. RESULTS: Induction of hemarthrosis resulted in a transient shift of blood monocytes towards a M1 type (control 13 vs. 1847 counted cells at day 1; p<0.01), a temporary decrease of spleen M1 monocytes (control 2841 vs. 1086 counted cells at day 1; p=0.02), and a sustained decrease of spleen M2 red pulp macrophages (control 1853 vs. 673 counted cells at day 7; p=0.01). In addition, an increase in M1 (control 119 vs. 592 counted cells at day 1; p=0.04) and M2 (control 247 vs. 650 counted cells at day 1; p=0.02) synovial macrophages was noted. In the joint lavage, a temporary increase in M1 monocytes (control 20 vs. 125 counted cells at day 1; p=0.04) and a more sustained increase in M2 monocytes (control 73 vs. 186 counted cells at day 2; p<0.01) was observed. CONCLUSIONS: This study demonstrates alterations in monocyte/macrophage polarization following hemarthrosis resulting in a blood monocyte M1 phenotype and a combined M1-M2 monocyte/macrophage phenotype in the joint. Based on the different capabilities of M1 and M2 cells, modulating polarization of distinct monocyte/macrophage populations might represent interesting prophylactic or therapeutic approaches for joint bleedings.

Haemarthrosis stimulates the synovial fibrinolytic system in haemophilic mice.

Recurrent joint bleeding is the most common manifestation of haemophilia resulting in haemophilic arthropathy (HA). The exact pathophysiology is unknown, but it is suggested that arthropathy is stimulated by liberation of fibrinolytic activators from the synovium during haemarthrosis. The aim of this study was to test the hypothesis that haemarthrosis activates the local synovial fibrinolytic system in a murine haemophilia model. The right knees of haemophilic and control mice were punctured to induce haemarthrosis. The left knees served as internal control joints. Synovial levels of urokinase-type plasminogen activator (uPA), plasminogen activator inhibitor 1 (PAI-1), plasmin, and alpha-2-antiplasmin (A2AP) were compared between the punctured and control knees. In haemophilic mice, an increase in synovial cells expressing urokinase-type plasminogen activator (uPA) in the right punctured knee versus the left unaffected knee was observed: (47% vs 43%) (p=0.03). Additionally, in haemophilic mice, haemarthrosis induced an increase in uPA (0.016 ng/ml vs 0.01 ng/ml) (p=0.03) and plasmin (0.53 µg/ml vs 0.46 µg/ml) (p=0.01) as promoters of fibrinolysis. Synovial levels of PAI-1 (0.32 ng/ml vs 0.17 ng/ml) (p<0.01) was also increased, whereas synovial levels of A2AP were unchanged: (0.021 µg/ml vs 0.021 µg/ml) (p=0.15). Enhanced uPA production was confirmed in human stimulated synovial fibroblast cultures and elevated levels of plasmin were confirmed harmful to human cartilage tissue explants. In this study we demonstrate that haemarthrosis in haemophilic mice induces synovial uPA expression and results in an increase in synovial plasmin levels, making the joint more vulnerable to prolonged and subsequent bleedings, and adding directly to cartilage damage.

A short time window to profit from protection of blood-induced cartilage damage by IL-4 plus IL-10.

OBJECTIVE: IL-4 plus IL-10 prevents blood-induced cartilage damage. The aim of the present study was to evaluate whether cartilage damage can still be averted by addition of IL-4 plus IL-10 when added after the onset of a bleed and whether aspiration of blood prior to addition of IL-4 plus IL-10 is of additive protective value. METHODS: Healthy canine hip and human shoulder cartilage was exposed to whole blood for 4 days. IL-4 plus IL-10 was administered directly or after a delay of several hours up to 2 days. Furthermore, blood was aspirated after 1 or 2 days and subsequently IL-4 plus IL-10 was added. IL-1ß concentration and cartilage matrix proteoglycan turnover were determined. RESULTS: Exposure of canine and human cartilage to blood decreased the proteoglycan synthesis rate and content and increased proteoglycan release. IL-4 plus IL-10 only prevented blood-induced damage of canine cartilage when added directly, not after 4 h or later. For human cartilage, IL-4 plus IL-10 limited blood-induced damage as well as IL-1ß production when administered within 4-8 h after the onset of a bleed, but not thereafter. Aspiration of blood within 24 h fully prevented cartilage damage. Subsequent addition of IL-4 plus IL-10 was not of additive value. CONCLUSION: For humans, there is a short time window after onset of a joint bleed in which IL-4 plus IL-10 can limit blood-induced cartilage damage. Furthermore, aspiration of a joint to shorten blood exposure fully prevents cartilage damage. Both options can be considered in the treatment of a joint haemorrhage.

A single intra-articular injection with IL-4 plus IL-10 ameliorates blood-induced cartilage degeneration in haemophilic mice.

The combination of interleukin (IL)-4 and IL-10 protects against blood-induced cartilage damage in vitro. It has been hypothesized that the combination of these cytokines is effective if applied early in the process of cartilage damage. The present study investigated whether a single intra-articular injection of IL-4 plus IL-10 immediately after a joint bleed limits cartilage damage in an in vivo haemophilia mouse model of blood-induced joint damage. Factor VIII knockout mice with severe haemophilia A were punctured once with a needle below the patella to induce a joint haemorrhage. Subsequently IL-4 plus IL-10 (n = 24) or vehicle (n = 24) was injected intra-articularly. After 35 days, the time needed for development of detectable joint degeneration, knee joints were examined for cartilage damage by macroscopic and microscopic evaluation. A single intra-articular injection of IL-4 plus IL-10 ameliorated progression of cartilage degeneration caused by a single joint bleed to a certain extent. No effect on inflammation was observed at this time point. A single intra-articular injection of IL-4 plus Il-10 directly after a single joint bleed limits progression of cartilage degeneration over time. Improved bioavailability (half-life) of both cytokines might improve their protective ability in the development of cartilage degeneration, and probably also inflammation.

Unfavourable cardiovascular disease risk profiles in a cohort of Dutch and British haemophilia patients.

Cardiovascular disease (CVD) mortality is reported to be decreased in haemophilia patients, but reports on the prevalence of CVD risk factors are conflicting. A cross-sectional assessment of CVD risk profiles was performed in a large cohort of haemophilia patients. Baseline data on CVD risk factors of 709 Dutch and UK haemophilia patients aged ≥30 years were analysed and compared with the general age-matched male population. CVD risk profiles were assessed using the QRISK®2-2011 and SCORE algorithms. Although QRISK® 2 was only validated in the UK, comparison with SCORE indicated similar properties of QRISK®2 in both Dutch and UK patients (correlation 0.86). Mean age was 49.8 years. Hypertension was more common in haemophilia patients than in the general population (49% vs. 40%), while the prevalences of obesity and hypercholesterolaemia were lower (15 vs. 20% and 44 vs. 68%, respectively), and those of diabetes and smoking were similar. The predicted 10-year QRISK®2 risk was significantly higher in haemophilia patients than in the general population (8.9 vs. 6.7%), indicating more unfavourable cardiovascular disease risk profiles. This increased risk became apparent after the age of 40 years. Our results indicate an increased prevalence of hypertension and overall more unfavourable CVD risk profiles in haemophilia patients compared with the general age-matched male population.

Blood-Induced Joint Damage: The Devastating Effects of Acute Joint Bleeds versus Micro-Bleeds.

OBJECTIVE: Four days of blood exposure leads to irreversible cartilage damage in vitro. In contrast, intermittent intra-articular blood injections twice a week during 4 weeks (mimicking micro-bleeds) in a canine model resulted in transient damage only. In this study, it was evaluated whether acute joint bleeds are more harmful than micro-bleeds in a canine model of knee arthropathy. DESIGN: Seven dogs received 4 sequential daily intra-articular blood injections twice in 2 weeks (mimicking 2 acute 4-day joint bleeds). Seven other dogs received the same blood load but in a total of 8 injections intermittently over the 4-week period with at least 1 day in between (mimicking micro-bleeds over the same timespan). Contralateral knees served as controls. Ten weeks after the last injection cartilage matrix turnover and synovial inflammation were evaluated. RESULTS: Only after the acute joint bleeds the release of newly formed and total (resident) cartilage matrix glycosaminoglycans were increased (P = 0.04 and P = 0.01, respectively). Furthermore, in animals with the acute joint bleeds cartilage glycosaminoglycan content was decreased (P = 0.01) and not in animals with micro-bleeds. Mild synovial inflammation was observed in both groups (both P < 0.0001) but was not different between groups. CONCLUSIONS: In contrast to micro-bleeds, 2 acute joint bleeds lead to prolonged cartilage damage independent of the level of synovial inflammation. This model suggests that micro-bleeds are less devastating than acute joint bleeds with respect to joint damage, which might be of relevance to treatment of joint bleeds in clinical practice.

Increased prevalence of hypertension in haemophilia patients.

An increased prevalence of hypertension is reported in haemophilia patients, but data from large, unbiased studies are lacking. The aim of our study was to cross-sectionally assess the prevalence of hypertension in a large cohort of 701 haemophilia patients. Blood pressure (BP) measurements performed in 386 Dutch and 315 UK haemophilia patients aged 30 years or older were analysed and compared with the general age-matched male population. Mean values of up to three BP measurements were used when available. Hypertension was defined as BP over 140/90 mmHg and/or the use of antihypertensive medication. A total of 49% of patients had severe haemophilia. Mean age was 49.8 years. The prevalence of hypertension was significantly higher in haemophilia patients (49%, 95% confidence interval [CI] 45-53) than in the general population (40%, 95% CI 37-43). The prevalence of hypertension was higher in patients with severe haemophilia than in those with non-severe disease, but similar across haemophilia types and in Dutch and UK patients. Multiple BP measurements were available for 70%.The prevalence of hypertension was similar in patients with multiple BP measurements and the complete cohort. Hypertension was not significantly associated with renal function, a history of renal bleeding or with infection with hepatitis C or HIV, but it was associated with overweight/obesity and age. In conclusion, the prevalence of hypertension is higher in haemophilia patients than in the general population. The cause of this increased prevalence is unknown. Blood pressure measurements should be part of standard care in haemophilia patients aged 30 years or older.

History of non-fatal cardiovascular disease in a cohort of Dutch and British patients with haemophilia.

OBJECTIVE: Cardiovascular disease (CVD) mortality is reported to be lower in haemophilia patients than in the general population, but information on the occurrence of non-fatal CVD is lacking. The aim of our study was to assess CVD history in a cohort of living haemophilia patients. METHODS: Retrospective data on the occurrence of myocardial infarction, angina pectoris, ischaemic stroke and intracranial bleeding in 709 living Dutch and British haemophilia patients aged 30 yr or older were analysed and compared with the general age-matched male population. RESULTS: There was a trend towards a lower cumulative incidence of myocardial infarction (1.7% vs. 4.0%) and ischaemic stroke (0% vs. 1.5%) in patients with severe haemophilia than in the general population, while the occurrence of angina pectoris was similar (3.2 vs. 3.7%). As expected, the cumulative incidence of intracranial bleeding was, on the other hand, significantly increased in haemophilia patients (1.6% vs. 0.4% in the general population). CONCLUSION: Our results suggest a protective effect of severe haemophilia against acute ischaemic CVD.

Coagulation aggravates blood-induced joint damage in dogs.

OBJECTIVE: Joint bleeding due to trauma, major joint surgery, or hemophilia leads to joint damage. It is unclear if there are differences between coagulating blood and anticoagulated blood with respect to joint degeneration, especially in vivo. Therefore, we undertook this study to evaluate in a canine in vivo model whether intraarticular exposure to coagulating blood is more destructive than exposure to anticoagulated blood, and whether inflammation plays a role in the cartilage- damaging process. METHODS: In 7 dogs the left knees were injected with coagulating blood 4 times a week during weeks 1 and 4, and the right knees were injected with saline. In 7 other dogs, anticoagulated heparinized blood was injected, and heparinized saline was used as control. Ten weeks after the last injection, cartilage matrix turnover and synovial inflammation were analyzed. To study inflammation-independent cartilage damage, explants of cartilage from at least 6 human donors per group were exposed in vitro to coagulating and anticoagulated blood, plasma, and serum for 4 days. Cartilage matrix turnover was determined after a recovery period of 12 days. RESULTS: Canine knees injected with coagulating blood showed more disturbed proteoglycan turnover than knees injected with anticoagulated blood. Synovial inflammation was present only after intraarticular injections with coagulating blood. In in vitro experiments, exposure of human cartilage explants to coagulating blood resulted in more damage than did exposure to anticoagulated blood, while exposure to plasma and serum did not alter cartilage matrix turnover. CONCLUSION: This study shows that coagulating blood causes more long-lasting in vivo joint damage than anticoagulated blood, thereby suggesting that along with joint bleeding in hemophilia, exposure to intraarticular blood should also be avoided during surgery and trauma to prevent joint damage.

Non-fatal cardiovascular disease, malignancies, and other co-morbidity in adult haemophilia patients.

INTRODUCTION: With increasing life expectancy, more haemophilia patients will be confronted with age-related problems. To ensure optimal care, it is important to know the occurrence of both fatal and non-fatal cardiovascular disease, malignancies and other types of co-morbidity in these patients. Our aim was to retrospectively assess the occurrence of co-morbidity and causes of death in a substantial birth-cohort of haemophilia patients. METHODS: Data on all types of co-morbidity were collected from medical records of 408 haemophilia patients (204 severe, 204 non-severe) born before 1971, and compared with the Dutch age-matched general male population. RESULTS: Ten patients had 11 myocardial infarctions, none of which were fatal. The cumulative incidence of non-fatal myocardial infarction was significantly lower in patients with severe haemophilia than in the general population (0.5% versus 4.8%), but was not decreased in patients with non-severe haemophilia (4.4%). Intracranial bleeding occurred significantly more often in haemophilia patients. The occurrence of non-virus related malignancies, and other non-virus related co-morbidities was similar in haemophilia patients and the general population. HIV infection was present in 12% of patients, and hepatitis C infection in 56%. Seventy-eight patients (19%) were deceased. Main causes of death were malignancies, AIDS, hepatitis C, and intracranial bleeding. CONCLUSIONS: Our results showed a decreased occurrence of myocardial infarction in patients with severe haemophilia, suggesting a protective effect of very low clotting factor levels on thrombotic cardiac events. No differences were found between haemophilia patients and the general population in the occurrence of any other type of non-virus related co-morbidity.

Coronary artery calcification in hemophilia A: no evidence for a protective effect of factor VIII deficiency on atherosclerosis.

OBJECTIVE: Ischemic heart disease mortality is lower in hemophilia patients than in the general male population. As coagulation plays a role in the inflammatory pathways involved in atherogenesis, we investigated whether the clotting factor deficiency protects hemophilia patients from developing atherosclerosis. METHODS AND RESULTS: Coronary artery calcification, measured with multidetector-row computed tomography, was compared between 42 men, ≥59 years, with severe or moderate hemophilia A, and 613 nonhemophilic men from the Rotterdam Study, a prospective population-based study. None of the study subjects were HIV infected or had a history of cardiovascular disease. Coronary artery calcification was quantified by calculating the Agatston score and calcification mass. Data were analyzed using linear regression. Mean difference (ß) of the natural log-transformed Agatston score between men with and without hemophilia was 0.141 (95% CI -0.602 to 0.885, P=0.709). Results did not change after adjustment for age, body mass index, hypercholesterolemia, hypertension, and use of antidiabetic medication (ß=0.525, 95% CI -0.202 to 1.252, P=0.157). Comparable results were found for calcification mass. CONCLUSION: The extent of coronary artery atherosclerosis is comparable between elderly men with and without hemophilia. Results from this study underline the importance of screening and treating atherosclerosis risk factors in hemophilia patients.

The combination of the biomarkers urinary C-terminal telopeptide of type II collagen, serum cartilage oligomeric matrix protein, and serum chondroitin sulfate 846 reflects cartilage damage in hemophilic arthropathy.

OBJECTIVE: Hemophilic arthropathy, with characteristics of inflammatory (rheumatoid arthritis) and degenerative (osteoarthritis) joint damage, occurs at an early age, is associated with minor comorbidity, and is restricted to 3 pairs of large joints. The aim of this study was to determine whether commonly used serum and/or urinary biomarkers of cartilage and bone turnover for which assay kits are commercially available are associated with the severity of joint damage in patients with various degrees of hemophilic arthropathy and, thus, whether this disease could be useful in the identification and evaluation of such biomarkers. METHODS: Blood and urine samples were collected from 36 patients with various degrees of hemophilic arthropathy. Commercially available assays for the most frequently investigated serum and urine biomarkers were performed: urinary C-terminal telopeptide of type I collagen (CTX-I), urinary CTX-II, serum CTX-I, serum CTX-II, serum cartilage oligomeric matrix protein (COMP), serum cartilage cleavage products C1,2C and C2C, and serum chondroitin sulfate 846 (CS-846). Radiographs of the ankles, knees, and elbows in all patients were evaluated for the degree of joint damage according to the Pettersson score, which is based on cartilage and periarticular bone changes and is specific for hemophilic arthropathy. RESULTS: Urinary CTX-II, serum C1,2C, and serum CS-846 levels correlated with the overall Pettersson score and with the joint space narrowing component. Regression analysis showed that combined indexes of different markers increased the degree of correlation for the combination of urinary CTX-II, serum COMP, and serum CS-846. Bone-specific markers (urinary/serum CTX-I and serum C1,2C) did not correlate with specific bone-related items of the Pettersson score (osteoporosis and erosions). CONCLUSION: These results support the idea that a combination of biomarkers relates significantly better to the severity of joint damage than do individual biomarkers. The combination of urinary CTX-II, serum COMP, and serum CS-846 correlated best with the degree of arthropathy. Because of its specific characteristics and restricted involvement, hemophilic arthropathy may prove useful in the screening of newly developed biomarkers of joint damage.

Understanding haemophilic arthropathy: an exploration of current open issues.

Haemophilic arthropathy is joint damage evolving from recurrent joint bleeds that occur in patients suffering from the clotting disorder haemophilia. Insight into the pathogenetic mechanism of this blood-induced arthropathy yields possible treatment targets and modalities useful to reduce this invalidating co-morbidity of haemophilia. Joint bleeding leads to initially independent adverse changes in both the synovial tissue and the articular cartilage. These subsequently influence each other: the synovial inflammatory changes enhancing cartilage damage and vice versa. Consequently, effective treatment strategies will have to affect both pathways.

Interleukin-10 protects against blood-induced joint damage.

Despite prophylactic treatment, haemophilia patients suffer from spontaneous joint bleeds, which lead to severe joint damage. Also after joint trauma, an intra-articular haemorrhage can add to joint damage over time. This study evaluated interleukin 10 (IL-10) in the search for possible interventions to prevent or limit the damaging effects of joint bleeds. Human articular cartilage tissue explants were cultured in the presence or absence of 50% v/v blood (or its cellular components) for 4 d (the expected blood load in vivo after a joint haemorrhage), followed by a recovery period of 12 d. Pharmacological dosages of IL-10 reached during treatment (1 or 10 ng/ml) were added. Additionally, cartilage and synovial tissue obtained from joints with end-stage haemophilic arthropathy (HA) were cultured in the presence of IL-10 (10 ng/ml). IL-10 protected cartilage from the damaging effects of blood exposure, measured by its effects on proteoglycan turnover. In addition, IL-10 beneficially influenced cartilage from patients with HA and reduced the production of the inflammatory cytokines IL-1beta and tumour necrosis factor-alpha by haemophilic synovial tissue. Taken together, although effects were obtained in vitro, IL-10 protects against blood-induced joint damage and might be further evaluated as candidate in treatment of tissue damaging effects of joint haemorrhages.