Relationship between iron deposits and tissue damage in the synovium: an ultrastructural study

Identification of potential ferroptosis key genes and immune infiltration in rheumatoid arthritis by integrated bioinformatics analysis

Objective

Ferroptosis is of vital importance in the development of Rheumatoid arthritis (RA). The purpose of this project is to clarify the potential ferroptosis-related genes, pathways, and immune infiltration in RA by bioinformatics analysis.

Methods

We acquired ferroptosis-related genes (FRGs) from Ferroptosis database (FerrDb). We obtained the Gene dataset of RA (GSE55235) from the Gene Expression Omnibus (GEO) Database, screened the differentially expressed genes (DEGs) in RA and control samples, and then took the intersection of it and FRGs. Aiming to construct the protein-protein interaction (PPI) networks of the FRGs-DEGs, STRING database and Cytoscape software 3.7.0 would be used. Furthermore, hub genes were identified by CytoNCA, a Cytoscape plug-in. The gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment of FRGs-DEGs were performed.

Results

We identified 34 FRGs-DEGs, including 7 upregulated and 27 downregulated genes by taking the intersection of the FRGs and DEGs. PPI analysis identified a total of 3 hub genes(VEGFA, PTGS2, and JUN). GO enrichment analyses and KEGG Pathway enrichment displayed that the FRGs-DEGs are involved in the response to oxidative stress and corticosteroid, heme binding, FoxO-signal pathway. Results of immune infiltration displayed that increased infiltration of T cells, while Macrophages M2 less may be related to the occurrence of RA.

Conclusion

The hub genes involved in ferroptosis in RA may be VEGFA, PTGS2, and JUN, which are mainly involved in FoxO-signal pathway. T cell, Mac, and plasma cells may be involved in the regulation of RA-joints-synovial-inflammation.

Synovitis and joint health in patients with haemophilia: Statements from a European e-Delphi consensus study

INTRODUCTION

Synovitis, a common feature in haemophilia, is triggered by the presence of blood in joints, and represents the first step towards the development of chronic arthropathy. Synovitis may be detected early by means of ultrasound or magnetic resonance imaging scan; clinical joint scores are less sensitive in this setting. Regular long-term prophylaxis with clotting factor concentrates, as primary prophylaxis and tailored to individual needs, has high efficacy in preventing synovitis. In general, higher factor levels lower bleeding risk, but no direct correlation between factor levels and synovitis incidence has been demonstrated.

AIM

This study aimed to develop an expert consensus relating to the definition, pathophysiology, diagnosis, prevention, follow-up and treatment of synovitis, recognising its relevance for joint health and taking into account existing knowledge gaps.

METHODS

A Delphi consensus study was designed and performed. An expert group prepared 22 statements based on existing literature; a wider expert panel subsequently voted on these.

RESULTS

Retention of panellists was high. Four statements required amending and consensus on all statements was achieved after three rounds of voting.

CONCLUSION

This e-Delphi consensus study addressed the importance of synovitis in joint health of people with haemophilia and highlighted knowledge gaps in this field. Studies on the natural course of synovitis are lacking and the biological mechanisms underlying this process are not yet fully elucidated. While basic and clinical research proceeds in this field, expert consensus can help guide clinicians in their routine clinical practice, and Delphi methodology is often used to produce best-practice guidelines.

Beef intake and risk of rheumatoid arthritis: Insights from a cross-sectional study and two-sample Mendelian randomization

Background

Beef is common in daily diet, but its association with the risk of rheumatoid arthritis (RA) remains uncertain. The objective of this study is to explore the relationship between beef intake and the risk of RA.

Materials and methods

We investigated the association between beef intake and risk of RA by multivariate logistic regression, based on the National Health and Nutrition Examination Survey (NHANES) 1999–2016 involving 9,618 participants. The dose–response relationship between beef intake and RA was explored as well. Furthermore, we performed Mendelian randomization (MR) analysis to examine the causal effect of beef intake on RA. Genetic instruments for beef intake were selected from a genome-wide association study (GWAS) including 335,576 individuals from the UK Biobank study, and summary statistics relating to RA were obtained from a GWAS meta-analysis of 14,361 RA patients and 43,923 controls. The inverse-variance weighted (IVW) approach was used to estimate the causal association, and MR-Egger regression and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) test were applied to evaluate the pleiotropy and outliers.

Results

Compared with the lowest quintile (0 to ≤33.50 g/d), beef intake was found to be significantly associated with the risk of RA [odds ratio (OR): 1.94; 95% confidence interval (CI): 1.20–3.12] in the third quintile (50.26 to ≤76.50 g/d). Moreover, a reversed “U” dose–response relationship between beef and RA (Pnon–linearity = 0.023) was found. In the MR analysis, beef intake was associated with an increased risk of RA (OR: 3.05; 95% CI: 1.11–8.35; P = 0.030) by the IVW method. The results from MR-Egger regression and MR-PRESSO test showed that there were no pleiotropic variations and outliers.

Conclusion

This study indicated that there is suggestive evidence to support the causal effect of beef intake on the risk of RA, while further studies are warranted to elucidate the exact association.

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.

Hereditary haemochromatosis presenting to rheumatology clinic as inflammatory arthritis

Hereditary haemochromatosis (HH) is the most commonly identified genetic disorder in Caucasians. HH has a wide variety of clinical manifestations. As such, the presenting complaint in new diagnoses of HH can be non-specific such as fatigue; however, joint symptoms such as arthralgia are also common. These joint symptoms closely mimic the features of other musculoskeletal diseases such as rheumatoid arthritis (RA). Early diagnosis of HH is key to prevent long-term irreversible complications such as liver damage, diabetes and degenerative joint disease. We present a case of HH which was initially suspected to be early RA, with ultrasound findings of active synovitis. High clinical suspicion, a raised serum ferritin followed by genetic testing for C282Y mutation confirmed the diagnosis of HH. The synovitis responded to corticosteroids and was suspected to be due to pseudogout a known complication of HH. Early diagnosis and treatment resulted in a favourable outcome.

Hemophilic arthropathy: Current knowledge and future perspectives

Hemophilia A and B are rare X-linked inherited bleeding disorders caused by complete or partial deficiency in or the absence of coagulation factors VIII and IX. Recurrent joint bleeding (hemarthrosis) is the most frequent clinical manifestation of severe hemophilia. Unless appropriately managed, even subclinical hemarthrosis can lead to the development of hemophilic arthropathy, a disabling condition characterized by joint remodelling, chronic pain, and a reduced quality of life, and eventually requires joint replacement. Given the lack of specific treatments to reduce blood-induced synovitis, the prevention of bleeding is pivotal to the maintenance of joint health. Prophylactic coagulation factor replacement therapy using extended half-life recombinant drugs has significantly improved patients' quality of life by reducing the burden of intravenous injections, and the more recent introduction of nonreplacement therapies such as subcutaneous emicizumab injections has improved treatment adherence and led to the greater protection of patients with hemophilia A. However, despite these advances, chronic arthropathy is still a significant problem. The introduction of point-of-care ultrasound imaging has improved the diagnosis of acute hemarthrosis and early hemophilic arthropathy, and allowed the better monitoring of progressive joint damage, but further research into the underlying mechanisms of the disease is required to allow the development of more targeted treatment. In the meantime, patient management should be based on the risk factors for the onset and progression of arthropathy of each individual patient, and all patients should be collaboratively cared for by multidisciplinary teams of hematologists, rheumatologists, orthopedic surgeons, and physiotherapists at comprehensive hemophilia treatment centers.

On-demand treatment with the iron chelator deferasirox is ineffective in preventing blood-induced joint damage in haemophilic mice

INTRODUCTION

Early intervention in the devastating process of haemophilic arthropathy (HA) is highly desirable, but no disease-modifying therapy is currently available. Considering the pivotal role of iron in the development of HA, iron chelation is considered a promising therapeutic approach. A previous study in haemophilic mice demonstrated that treatment with the iron chelator deferasirox (DFX) 8 weeks before joint bleed induction, attenuated cartilage damage upon blood exposure. However, in haemophilia patients this approach is not opportune given the unpredictable occurrence of hemarthroses.

AIM

To evaluate the effectiveness of on-demand DFX treatment, initiated immediately after joint bleed induction.

METHODS

A joint bleed was induced in 66 factor VIII-deficient mice by infra-patellar needle puncture. Mice were randomly assigned to treatment with either placebo (drinking water) or DFX (dissolved in drinking water) throughout the study. Five weeks after joint bleed induction, inflammation and cartilage damage were assessed histologically. Joints of ten bleed naive haemophilic mice served as controls.

RESULTS

A joint bleed resulted in significant inflammation and cartilage damage in the blood-exposed joint compared with those of control animals, in both the placebo and DFX group (all p = <.05). No differences in tibiofemoral or patellar inflammation (p = .305 and p = .787, respectively) nor cartilage damage (p = .265 and p = .802, respectively) were found between the blood-exposed joints of both treatment groups.

CONCLUSION

On-demand treatment with DFX does not prevent joint damage following blood exposure in haemophilic mice. DFX seems unable to reach the joint in time to exert its effect before the irreversible harmful process is initiated.

Musculoskeletal complications associated with pathological iron toxicity and its molecular mechanisms

Iron is fundamental for several biological functions, but when in excess can lead to the development of toxic events. Some tissues and cells are more susceptible than others, but systemic iron levels can be controlled by treating patients with iron-chelating molecules and phlebotomy. An early diagnostic can be decisive to limit the progression of musculoskeletal complications like osteoarthritis and osteoporosis because of iron toxicity. In iron-related osteoarthritis, aggravation can be associated to a few events that can contribute to joints articular cartilage exposure to high iron concentrations, which can promote articular degeneration with very little chance of tissue regeneration. In contrast, bone metabolism is much more dynamic than cartilage, but progressive iron accumulation and ageing can be decisive factors for bone health. The iron overload associated with hereditary diseases like hemochromatosis, hemophilias, thalassemias and other hereditary anaemias increase the negative impact of iron toxicity in joints and bone, as well as in life quality, even when iron levels can be controlled. The molecular mechanisms by which iron can compromise cartilage and bone have been illusive and only in the last 20 years studies have started to shed some light into the molecular mechanisms associated with iron toxicity. Ferroptosis and the regulation of intracellular iron levels is instrumental in the balance between detoxification and induced cell death. In addition, these complications are accompanied with multiple susceptibility factors that can aggravate iron toxicity and should be identified. Therefore, understanding tissues microenvironment and cell communication is fundamental to contextualize iron toxicity.

Major dietary patterns and food groups in relation to rheumatoid arthritis in newly diagnosed patients

BACKGROUND

Evidence suggests that dietary patterns might act as environmental triggers in the development of chronic disorders such as rheumatoid arthritis (RA). However, data regarding the relationship between food patterns and RA are still limited and conflicting. In the current study, the authors aim to evaluate a link between major dietary patterns and RA in new case patients.

METHODS

This study was conducted in a case-control manner on 50 patients with newly diagnosed RA and 100 healthy individuals living in Mashhad, Iran. The individuals' dietary intake was assessed using a validated food frequency questionnaire (FFQ). The major dietary patterns were identified using factor analysis based on data from FFQ. Multivariable-adjusted logistic regression models were used to measure the associations between patterns and RA.

RESULTS

Three major dietary patterns were identified. High-level adherence to Western pattern had a positive association with RA (multivariable-adjusted OR tertile 3 vs. 1:1.95; 95% CI: 1.09-3.92; p-trend: .046), while the healthy pattern was inversely related to RA (multivariable-adjusted OR tertile 3 vs. 1:0.12; 95% CI: 0.03-0.44; p-trend: .001). No significant association was observed between the traditional pattern and RA.

CONCLUSIONS

Our findings revealed that people with dietary behaviors close to the Western dietary pattern are more likely to develop the disease. However, adhering to healthy and well-balanced dietary patterns rich in whole grains, low-fat dairies, white meats, eggs, fruits, vegetables, tea, and vegetable oils was found to be inversely correlated with the risk of RA.

Icariin enhances cell survival in lipopolysaccharide-induced synoviocytes by suppressing ferroptosis via the Xc-/GPX4 axis

The mechanism of action of synovitis, as the vital pathological process of rheumatoid arthritis and osteoarthritis, remains to be elucidated. The effects and the mechanism of icariin (ICA), which is a promising therapeutic agent in synovitis, was investigated in the present study. In addition, ferroptosis, a vital cell process involved in several diseases, was also studied in synovitis for the first time. Lipopolysaccharide (LPS)-induced synoviocytes served as a synovitis cell model. The cells were divided into control, LPS and experimental groups and were treated with different concentrations of ICA. Cell viability was determined by Cell Counting Kit-8 assay and cell death was determined by flow cytometry. The expression levels of proteins (GPX4, SLC7A11, SLC3A2L, TRF, Nrf2 and NCOA4) were measured by western blotting. Quantification of malondialdehyde (MDA), iron and glutathione peroxidase 4 (GPX4) activity levels were performed via using corresponding assay kits. Cell death was increased, and cell viability was decreased in LPS-induced synoviocytes. Furthermore, MDA levels and iron content were elevated and GPX levels was reduced in LPS-induced synoviocytes. Transferrin receptor protein 1 and nuclear receptor coactivator 4 were upregulated and proteins of the Xc-/GPX4 axis, as well as nuclear factor erythroid 2-related factor 2, were decreased by LPS treatment. All aforementioned LPS affects were alleviated by ICA via a concentration-dependent manner. ICA counteracted the effects of RSL3, a ferroptosis activator, on cell viability, lipid peroxidation, iron content and relative protein expression of ferroptosis in synoviocytes. ICA protects the cells from death in synoviocytes induced by LPS, via the inhibition of ferroptosis by activating the Xc-/GPX4 axis, which can be exploited as a new therapeutic strategy for synovitis.

Dietary Habits and Nutrition in Rheumatoid Arthritis: Can Diet Influence Disease Development and Clinical Manifestations?

Rheumatoid arthritis (RA) is a systemic, autoimmune disease characterized by joint involvement, with progressive cartilage and bone destruction. Genetic and environmental factors determine RA susceptibility. In recent years, an increasing number of studies suggested that diet has a central role in disease risk and progression. Several nutrients, such as polyunsaturated fatty acids, present anti-inflammatory and antioxidant properties, featuring a protective role for RA development, while others such as red meat and salt have a harmful effect. Gut microbiota alteration and body composition modifications are indirect mechanisms of how diet influences RA onset and progression. Possible protective effects of some dietary patterns and supplements, such as the Mediterranean Diet (MD), vitamin D and probiotics, could be a possible future adjunctive therapy to standard RA treatment. Therefore, a healthy lifestyle and nutrition have to be encouraged in patients with RA.

A Molecular Revolution in the Treatment of Hemophilia

For decades, the monogenetic bleeding disorders hemophilia A and B (coagulation factor VIII and IX deficiency) have been treated with systemic protein replacement therapy. Now, diverse molecular medicines, ranging from antibody to gene to RNA therapy, are transforming treatment. Traditional replacement therapy requires twice to thrice weekly intravenous infusions of factor. While extended half-life products may reduce the frequency of injections, patients continue to face a lifelong burden of the therapy, suboptimal protection from bleeding and joint damage, and potential development of neutralizing anti-drug antibodies (inhibitors) that require less efficacious bypassing agents and further reduce quality of life. Novel non-replacement and gene therapies aim to address these remaining issues. A recently approved factor VIII-mimetic antibody accomplishes hemostatic correction in patients both with and without inhibitors. Antibodies against tissue factor pathway inhibitor (TFPI) and antithrombin-specific small interfering RNA (siRNA) target natural anticoagulant pathways to rebalance hemostasis. Adeno-associated virus (AAV) gene therapy provides lasting clotting factor replacement and can also be used to induce immune tolerance. Multiple gene-editing techniques are under clinical or preclinical investigation. Here, we provide a comprehensive overview of these approaches, explain how they differ from standard therapies, and predict how the hemophilia treatment landscape will be reshaped.

Bleed volume of experimental knee haemarthrosis correlates with the subsequent degree of haemophilic arthropathy

BACKGROUND

Haemophilic arthropathy is the main morbidity of haemophilia. The individual pathological response to the same number of clinically evident joint bleeds is highly variable; thus, it remains unknown if certain joint bleeding characteristics are critical for the development of arthropathy.

AIM

To study the relation between bleed volume and subsequent development of arthropathy, we aimed to develop quantitative in vivo imaging of active joint bleeds in a mouse model of haemophilia.

METHODS

Haemophilia A (F8-KO) and wild-type (WT) mice were IV-dosed with a micro-CT blood pool contrast agent prior to an induced knee haemarthrosis or sham procedure. The mice were micro-CT scanned five times the following 2 days to characterise and quantify the induced haemarthrosis in vivo. On Day 14, the mice were euthanized and pathological changes evaluated by histology and micro-CT. Additionally, bleeding characteristics in vehicle-treated F8-KO mice were compared with those of recombinant FVIII (rFVIII)-treated F8-KO mice.

RESULTS

F8-KO mice had a significantly larger bleed volume than WT mice at all scan time points. The bleed volume 12 hours after induction of haemarthrosis correlated with the subsequent degree of arthropathy. Presence of µCT-detectable bone pathology was associated with a significantly increased bleed volume among F8-KO mice. rFVIII treatment significantly reduced bleed volume in F8-KO mice.

CONCLUSION

Quantitative in vivo contrast-enhanced micro-CT imaging can be used to characterize and quantify joint bleeds in a mouse model of haemophilic arthropathy. The bleed volume correlates with the subsequent degree of arthropathy.

Are we really what we eat? Nutrition and its role in the onset of rheumatoid arthritis

Accumulating research evidence suggests that individual dietary factors and dietary patterns might be implicated in the risk of development of rheumatoid arthritis (RA). This narrative review aims to present this evidence and provide nutritional recommendations for reducing RA risk in susceptible individuals. Overall, a 'Western' type diet rich in energy intake, total and saturated fat, an unbalanced ratio of n-3 to n-6 fatty acids, high in refined carbohydrates and sugar and low in fiber and antioxidants might increase the risk of RA both directly through increasing inflammation and indirectly through increasing insulin resistance and obesity, with the latter being a known risk factor for RA. On the contrary, consumption of long-chain omega-3 polyunsaturated fatty acids, derived from fish and fish oil, is associated with a reduced risk of RA probably due to their anti-inflammatory properties. The Mediterranean diet (MD), rich in plant-based foods such as wholegrains, legumes, fruit, vegetables, extra-virgin olive oil and low in red meat consumption, might have the potential to reduce the risk of RA. Based on current research evidence, it is suggested that adherence to the MD enhanced with an increased consumption of fatty fish, reduced consumption of sugar-sweetened drinks and maintenance of a normal body weight, contributes to reducing the risk of RA. Further research on RA susceptibility will allow for more specific dietary recommendations to be made.

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.

Quinaldic acid in synovial fluid of patients with rheumatoid arthritis and osteoarthritis and its effect on synoviocytes in vitro

BACKGROUND

Previously, we have demonstrated that kynurenic acid (KYNA), an endogenous metabolite of tryptophan formed along kynurenine pathway, is present in synovial fluid of rheumatoid arthritis (RA) and osteoarthritis (OA) patients. In this study, the goal was to investigate the presence of quinaldic acid (QUDA), a putative metabolite of KYNA, in synovial fluid of RA and OA patients.

METHODS

The effect of QUDA on proliferation and motility of synovial fibroblasts and its interaction with KYNA were determined in vitro. The study was conducted on synovial fluid obtained from 38 patients with RA and 15 patients with OA. QUDA was identified and quantified using the gas chromatography-mass spectrometry (GC-MS) method. In vitro experiments were conducted on rabbit synoviocyte cell line HIG-82.

RESULTS

Presence of QUDA was detected in all 53 samples of synovial fluid. The concentration of QUDA in synovial fluid obtained from patients with RA was 28.6 ± 14.9 pmol/ml, which was lower in comparison with OA 42.3 ± 10.0 pmol/ml. QUDA content positively correlated with the number of tender joints and negatively with the total cell counts determined in synovial fluid of RA patients. It did not correlate with KYNA content. QUDA reduced both proliferation and motility of synoviocytes in a dose-dependent manner. The enhancement of antiproliferative action of QUDA by KYNA was evidenced.

CONCLUSIONS

Data show a local deficit of QUDA in RA patients and suggest its potential role as an endogenous substance controlling synoviocyte viability.

Iron accumulation in senescent cells is coupled with impaired ferritinophagy and inhibition of ferroptosis

Cellular senescence is characterised by the irreversible arrest of proliferation, a pro-inflammatory secretory phenotype and evasion of programmed cell death mechanisms. We report that senescence alters cellular iron acquisition and storage and also impedes iron-mediated cell death pathways. Senescent cells, regardless of stimuli (irradiation, replicative or oncogenic), accumulate vast amounts of intracellular iron (up to 30-fold) with concomitant changes in the levels of iron homeostasis proteins. For instance, ferritin (iron storage) levels provided a robust biomarker of cellular senescence, for associated iron accumulation and for resistance to iron-induced toxicity. Cellular senescence preceded iron accumulation and was not perturbed by sustained iron chelation (deferiprone). Iron accumulation in senescent cells was driven by impaired ferritinophagy, a lysosomal process that promotes ferritin degradation and ferroptosis. Lysosomal dysfunction in senescent cells was confirmed through several markers, including the build-up of microtubule-associated protein light chain 3 (LC3-II) in autophagosomes. Impaired ferritin degradation explains the iron accumulation phenotype of senescent cells, whereby iron is effectively trapped in ferritin creating a perceived cellular deficiency. Accordingly, senescent cells were highly resistant to ferroptosis. Promoting ferritin degradation by using the autophagy activator rapamycin averted the iron accumulation phenotype of senescent cells, preventing the increase of TfR1, ferritin and intracellular iron, but failed to re-sensitize these cells to ferroptosis. Finally, the enrichment of senescent cells in mouse ageing hepatic tissue was found to accompany iron accumulation, an elevation in ferritin and mirrored our observations using cultured senescent cells.

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Altered iron homeostasis in senescent cells is driven by impaired ferritinophagy.

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Impaired ferritinophagy causes functional cellular iron deficiency.

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senescent cells are resistant to iron mediated cell death including ferroptosis.

Pathophysiology of Hemophilic Arthropathy

Spontaneous joint bleeding and repeated hemarthroses lead to hemophilic arthropathy—a debilitating disease with a significant negative impact on mobility and quality of life. Iron, cytokines, and angiogenic growth factors play a pivotal role in the onset of the inflammatory process that involves the synovial tissue, articular cartilage, and subchondral bone, with early damages and molecular changes determining the perpetuation of a chronic inflammatory condition. Synovitis is one of the earliest complications of hemarthrosis, and is characterized by synovial hypertrophy, migration of inflammatory cells, and a high degree of neo-angiogenesis with subsequent bleeding. The pathogenic mechanisms and molecular pathways by which blood in the joint cavity causes articular cartilage and subchondral bone destruction have yet to be fully elucidated. Both cytokines and matrix metalloproteinases and hydroxyl radicals may induce chondrocyte apoptosis. Members of the tumor necrosis factor receptor superfamily (such as the molecular triad: osteoprotegerin—OPG; receptor activator of nuclear factor κB—RANK; RANK ligand—RANKL) seem instead to play a major role in the inflammatory process. These pathogenic processes interact with each other and ultimately lead to a fibrotic joint and the disabling condition characteristic of hemophilic arthropathy.

The Role of Angiogenesis in Haemophilic Arthropathy: Where Do We Stand and Where Are We Going?

Haemophilia is an inherited bleeding disorder that can lead to degenerative joint arthropathy due to recurrent bleeding episodes affecting the musculoskeletal system of the patient. The cause of bleeding can be either traumatic or spontaneous. The pathogenesis of haemophilic arthropathy is unclear as many factors like iron, inflammatory cytokines, and angiogenic factors contribute to this process. Blood into joints can deteriorate the bone to such an extent that the patient experiences pain, reduction of the range of movement, and deformity of the joint, conditions that could have a great impact on quality of life. Over the years, management of haemophilic arthropathy has changed. Nowadays, early diagnosis with high resolution imaging like magnetic resonance imaging along with application of prophylaxis regimens can reduce the extent of damage to the joints. However, not all haemophilia patients have access to these interventions as cost may be prohibitive for some of them. The need for new, easy, and cost-effective strategies with the ability to identify early changes could be beneficial and could make a difference in the management of haemophilic arthropathy. Understanding the mechanism of processes like angiogenesis in the mechanism of developing arthropathy could be innovative for these patients and could help in the detection of new early diagnostic and therapeutic markers.

Connective tissue growth factor (CTGF/CCN2) in haemophilic arthropathy and arthrofibrosis: a histological analysis

INTRODUCTION

Joint haemorrhage is the principal clinical manifestation of haemophilia frequently leading to advanced arthropathy and arthrofibrosis, resulting in severe disability. The degree and prevalence of arthrofibrosis in hemophilic arthropathy is more severe than in other forms of arthropathy. Expression of connective tissue growth factor (CTGF) has been linked to many fibrotic diseases, but has not been studied in the context of haemophilic arthropathy.

AIM

We aim to compare synovial tissues histologically from haemophilia and osteoarthritis patients with advanced arthropathy in order to compare expression of proteins that are possibly aetiologic in the development of arthrofibrosis.

METHODS

Human synovial tissues were obtained from 10 haemophilia and 10 osteoarthritis patients undergoing joint surgery and processed for histology and immunohistochemistry.

RESULTS

All samples from haemophilia patients had synovitis with hypertrophy and hyperplasia of synovial villi. Histologically, synovial tissues contained hyperplastic villi with increased cellularity and abundant haemosiderin- and ferritin-pigmented macrophage-like cells (HMCs), with a perivascular localization in the sub-surface layer. CTGF staining was observed in the surface layer and sub-surface layer in all haemophilia patients, exclusively co-localizing with HMCs. Quantification showed that the extent of CTGF-positive areas was correlated with the degree of detection of HMCs. CTGF was not observed in any of the samples from osteoarthritis patients.

CONCLUSION

Using histological analysis, we showed that CTGF expression is elevated in haemophilia patients with arthrofibrosis and absent in patients with osteoarthritis. Additionally, we found that CTGF is always associated with haemosiderin-pigmented macrophage-like cells, which suggests that CTGF is produced by synovial A cells following the uptake of blood breakdown products.

The metabolic role of the gut microbiota in health and rheumatic disease: mechanisms and interventions

The role of the gut microbiome in animal models of inflammatory and autoimmune disease is now well established. The human gut microbiome is currently being studied as a potential modulator of the immune response in rheumatic disorders. However, the vastness and complexity of this host-microorganism interaction is likely to go well beyond taxonomic, correlative observations. In fact, most advances in the field relate to the functional and metabolic capabilities of these microorganisms and their influence on mucosal immunity and systemic inflammation. An intricate relationship between the microbiome and the diet of the host is now fully recognized, with the microbiota having an important role in the degradation of polysaccharides into active metabolites. This Review summarizes the current knowledge on the metabolic role of the microbiota in health and rheumatic disease, including the advances in pharmacomicrobiomics and its potential use in diagnostics, therapeutics and personalized medicine.

Iron overload in a murine model of hereditary hemochromatosis is associated with accelerated progression of osteoarthritis under mechanical stress

OBJECTIVE

Hereditary hemochromatosis (HH) is a disease caused by mutations in the Hfe gene characterised by systemic iron overload and associated with an increased prevalence of osteoarthritis (OA) but the role of iron overload in the development of OA is still undefined. To further understand the molecular mechanisms involved we have used a murine model of HH and studied the progression of experimental OA under mechanical stress.

DESIGN

OA was surgically induced in the knee joints of 10-week-old C57BL6 (wild-type) mice and Hfe-KO mice. OA progression was assessed using histology, micro CT, gene expression and immunohistochemistry at 8 weeks after surgery.

RESULTS

Hfe-KO mice showed a systemic iron overload and an increased iron accumulation in the knee synovial membrane following surgery. The histological OA score was significantly higher in the Hfe-KO mice at 8 weeks after surgery. Micro CT study of the proximal tibia revealed increased subchondral bone volume and increased trabecular thickness. Gene expression and immunohistochemical analysis showed a significant increase in the expression of matrix metallopeptidase 3 (MMP-3) in the joints of Hfe-KO mice compared with control mice at 8 weeks after surgery.

CONCLUSIONS

HH was associated with an accelerated development of OA in mice. Our findings suggest that synovial iron overload has a definite role in the progression of HH-related OA.

The effect of platelet-rich plasma formulations and blood products on human synoviocytes: implications for intra-articular injury and therapy

BACKGROUND

The effect of platelet-rich plasma (PRP) on chondrocytes has been studied in cell and tissue culture, but considerably less attention has been given to the effect of PRP on synoviocytes. Fibroblast-like synoviocytes (FLS) compose 80% of the normal human synovium and produce cytokines and matrix metalloproteinases that can mediate cartilage catabolism.

PURPOSE

To compare the effects of leukocyte-rich PRP (LR-PRP), leukocyte-poor PRP (LP-PRP), red blood cell (RBC) concentrate, and platelet-poor plasma (PPP) on human FLS to determine whether leukocyte and erythrocyte concentrations of PRP formulations differentially affect the production of inflammatory mediators.

STUDY DESIGN

Controlled laboratory study.

METHODS

Peripheral blood was obtained from 4 donors and processed to create LR-PRP, LP-PRP, RBCs, and PPP. Human synoviocytes were cultured for 96 hours with the respective experimental conditions using standard laboratory conditions. Cell viability and inflammatory mediator production were then evaluated.

RESULTS

Treatment with LR-PRP resulted in significantly greater synoviocyte death (4.9% ± 3.1%) compared with LP-PRP (0.72% ± 0.70%; P = .035), phosphate-buffered saline (PBS) (0.39% ± 0.27%; P = .018), and PPP (0.26% ± 0.30%; P = .013). Synoviocytes treated with RBC concentrate demonstrated significantly greater cell death (12.5% ± 6.9%) compared with PBS (P < .001), PPP (P < .001), LP-PRP (P < .001), and LR-PRP (4.9% ± 3.1%; P < .001). Interleukin (IL)-1β content was significantly higher in cultures treated with LR-PRP (1.53 ± 0.86 pg/mL) compared with those treated with PBS (0.22 ± 0.295 pg/mL; P < .001), PPP (0.11 ± 0.179 pg/mL; P < .001), and RBCs (0.64 ± 0.58 pg/mL; P = .001). IL-6 content was also higher with LR-PRP (32,097.82 ± 22,844.300 pg/mL) treatment in all other groups (P < .001). Tumor necrosis factor-α levels were greatest in LP-PRP (9.97 ± 3.110 pg/mL), and this was significantly greater compared with all other culture conditions (P < .001). Interferon-γ levels were greatest in RBCs (64.34 ± 22.987 pg/mL) and significantly greater than all other culture conditions (P < .001).

CONCLUSION

Treatment of synovial cells with LR-PRP and RBCs resulted in significant cell death and proinflammatory mediator production.

CLINICAL RELEVANCE

Clinicians should consider using leukocyte-poor, RBC-free formulations of PRP when administering intra-articularly.

Iron deposits in the chronically inflamed central nervous system and contributes to neurodegeneration

Neurodegenerative disorders are characterized by the presence of inflammation in areas with neuronal cell death and a regional increase in iron that exceeds what occurs during normal aging. The inflammatory process accompanying the neuronal degeneration involves glial cells of the central nervous system (CNS) and monocytes of the circulation that migrate into the CNS while transforming into phagocytic macrophages. This review outlines the possible mechanisms responsible for deposition of iron in neurodegenerative disorders with a main emphasis on how iron-containing monocytes may migrate into the CNS, transform into macrophages, and die out subsequently to their phagocytosis of damaged and dying neuronal cells. The dying macrophages may in turn release their iron, which enters the pool of labile iron to catalytically promote formation of free-radical-mediated stress and oxidative damage to adjacent cells, including neurons. Healthy neurons may also chronically acquire iron from the extracellular space as another principle mechanism for oxidative stress-mediated damage. Pharmacological handling of monocyte migration into the CNS combined with chelators that neutralize the effects of extracellular iron occurring due to the release from dying macrophages as well as intraneuronal chelation may denote good possibilities for reducing the deleterious consequences of iron deposition in the CNS.

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.

The clotting system - a major player in wound healing

Wound healing involves a complex series of interactions between coagulation, inflammation, angiogenesis, and cellular migration and proliferation. Our laboratory has developed an excisional dermal wound model in mice in order to study some of these processes and to determine how coagulation defects affect wound healing. In contrast to wild type mice, haemophilia B mice typically show delayed healing, signs of bleeding into the wound, and significant wound expansion. The difference in wound size may result from limited fibrin deposition in haemophilic animals and the subsequent inability to anchor the platelet plug to the surrounding tissues, thus allowing wound expansion through oedema. Haemophilic mice also demonstrate impaired wound healing times. However, while pre-treatment with factor IX or human activated factor VII improves some wound characteristics in haemophilia B animals, the time to wound healing is still delayed and signs of ongoing bleeding are evident. Haemophilic mice also show a deficient initial inflammatory response and increased angiogenesis, which, in turn, leads to increased bleeding: in the absence of robust haemostasis, these fragile, newly sprouted vessels have a tendency to bleed. Taken together, these observations suggest that ongoing haemostasis is necessary for normal wound healing. If this is correct, then optimal wound healing in haemophilia would require therapy until at least the point that vessel formation is stabilized. The goal of such treatment would be to avoid a feedback cycle in which bleeding tends to lead to further bleeding. Once initiated, this cycle may be difficult to control.

Trace elements and rheumatoid arthritis (RA)--pathogenetic and therapeutic aspects

Rheumatoid arthritis is characterized by increased activity of macrophages which produce toxic forms of oxygen. Such oxygen has been suggested as mediator also of rheumatoid inflammation. Gold accumulates in lysosomes of the macrophages and stabilizes lysosomal and other cell membranes leading to reduced liberation of toxic oxygen. Intracellular production of metallothionein can be induced. Zinc in high doses parenterally can immobilize macrophages and also induce metallothionein-like proteins. Copper and zinc are components of SOD which detoxifies oxygen, and copper-thiolate complexes are reported to be anti-inflammatory. The therapeutic effect of penicillamine and other thiols like aurothiomalate may also be related to an anti-oxidative action. Therapeutic induction of increased intracellular levels of glutathione or administration of selenium in such a form that it incorporates into glutathione-peroxidase and increases the efficacy of the enzyme may lead to accelerated metabolism of toxic oxygen.

Physiopathology of haemophilic arthropathy

Haemophilic arthropathy, which shares some clinical and biological injury characteristics with rheumatoid arthritis, is characterized by two main features: chronic proliferative synovitis and cartilage destruction. It is the consequence of repeated extravasation of blood into joint cavities, but its exact pathogenesis, particularly with regard to early changes in the joint, is still incompletely understood. This review presents recent findings obtained in experiments performed in vitro and using animal models, which have improved our knowledge of the pathogenesis of haemophilic arthropathy. These experimental studies show that haemophilic arthropathy is a multifactorial event in which the deposit of iron in the joints appears to exert a central role. First, iron may promote the apoptosis of chondrocytes by catalysing the formation of oxygen metabolites; this may explain the fact that intra-articular blood exerts a directly harmful effect on cartilage before, and independent of synovial changes. Secondly, iron may also act on the synovial membrane by favouring its proliferation through the induction of proto-oncogenes involved in cellular proliferation and stimulation of inflammatory cytokines as well as abrogation of apoptosis. These two processes, one degenerative and cartilage-mediated, the other inflammatory and synovium-mediated could occur in parallel or sequentially. Overall, it may be expected that these experimental results will yield new therapeutic strategies capable of effectively preventing the occurrence of this still serious and common complication in patients with severe haemophilia.

Efficacy of Siddha formulation Kalpaamruthaa in ameliorating joint destruction in rheumatoid arthritis in rats

BACKGROUND

Rheumatoid arthritis (RA) is a kind of chronic inflammatory autoimmune disease. The degradation of extracellular matrix and cartilage pave way in understanding the molecular mechanisms in RA. Degradation of cartilage is a more complex event involving the local release of metallaoproteases and lysosomal enzymes that mediate inflammation in joints and in the synovial fluid in RA.

OBJECTIVES

In the present study, the efficacy of a Siddha preparation named Kalpaamruthaa (KA) in ameliorating the disease process via markedly reducing the joint destruction was demonstrated in adjuvant induced arthritis rat model. KA consists of Semecarpus anacardium nut milk extract (SA), dried powder of Emblica officinalis fruit and honey.

MATERIAL AND METHODS

Both SA and KA were administered at dose of 150 mg/kg b.wt. for 14 days after 14 days of adjuvant injection in rats. The activity of lysosomal enzymes, the level of collagen, glycosaminoglycans (GAGs) and its degradative products were analyzed in control and experimental animals.

RESULTS AND CONCLUSION

The study revealed that KA exhibited a profound reduction (p<0.05) in the activities of lysosomal enzymes and thereby decreasing (p<0.05) the levels of GAGs and its fractions when compared to arthritis rats. The latter was confirmed by Safrannin O staining for GAGs in the interphalangeal joints of control and experimental animals. The effect of KA was found to be improved than SA and this might be due to the combined interactions of phytoconstituents present in KA.

(32)P colloid radiosynovectomy in treatment of chronic haemophilic synovitis: Iran experience

Repeated intra-articular bleeding with subsequent development of chronic synovitis and cartilage changes, leading to haemophilic arthropathy, is one the most debilitating problems in haemophilic patients. Radiosynovectomy is a familiar therapeutic choice in management of chronic synovitis in haemophilia. We report the treatments results of synoviorthesis with (32)P chromic phosphate with emphasis on clinical aspects. Between 2002 and 2006 we performed 66 procedures in 53 patients. Seven patients were excluded. The remaining 46 patients were followed for an average of 31 months. The mean age of patients at the time of injection was 15.9 years (range: 6-28). There were three repeat injections. According to Fernandez-pallazi and Cavilgia clinical classification (Table 1) [23], nine joints were Stage II and 46 were Stage III. In latest follow-up, 77% of patients reported at least a 50% decrease in bleeding frequency after treatment (P < 0.0001). The need for antihaemophilic factor consumption dropped by about 74% postradiosynovectomy (P < 0.0001). In most of the injected joints, the range of motion remained stable or improved. A trend was found for the number of haemarthrosis to increase after a period of considerable improvement. Synoviorthesis using (32)P effectively reduces the intra-articular bleeding rate and factor concentrate use. Durability of the response seems to be unpredictable, perhaps attributable to the late intervention. An early radiosynovectomy might be more helpful in terms of stability of response to treatment.

Histological changes in murine haemophilic synovitis: a quantitative grading system to assess blood-induced synovitis

Haemophilia is a congenital disorder that results in frequent bleeding into joints, in which a chronic and debilitating arthritis develops. The presence of blood evokes an inflammatory and proliferative synovial reaction. Although the molecular mechanisms and biochemical pathways which underlie this disorder are not known, significant advances have been made by studying a murine model of human haemophilic synovitis. In order to better understand and correlate the pathological, molecular and biochemical changes, it has become necessary to grade the histological changes observed. Despite a search of the literature and review of relevant publications, none of the currently utilized schemes were appropriate, and therefore a novel grading scheme was developed. After review of over 1000 histological sections, six characteristic changes were identified: (i) synovial hyperplasia; (ii) vascularity; (iii) discolouration by haemosiderin; (iv) the presence of blood (erythrocytes); (v) villus formation; and (vi) cartilage erosion. Synovial hyperplasia and vascularity were present in variable amounts and were quantitatively scored (0-3), while the other changes were qualitatively scored as absent or present (0 or 1). Application of the grading scheme was tested and a high interobserver correlation (greater than 80%) was found. The scheme was easy to learn even by novices, with no prior experience. The availability of the histological grading scheme for murine synovitis will allow for precise evaluation of the pathological changes following joint bleeding, and facilitate correlations with molecular and biochemical changes that lead to these changes.

Cutaneous wound healing is impaired in hemophilia B

We used a mouse model to test the hypothesis that the time course and histology of wound healing is altered in hemophilia B. Punch biopsies (3 mm) were placed in the skin of normal mice and mice with hemophilia. The size of the wounds was measured daily until the epidermal defect closed. All wounds closed in mice with hemophilia by 12 days, compared with 10 days in normal animals. Skin from the area of the wound was harvested at different time points and examined histologically. Hemophilic animals developed subcutaneous hematomas; normal animals did not. Macrophage infiltration was significantly delayed in hemophilia B. Unexpectedly, hemophilic mice developed twice as many blood vessels in the healing wounds as controls, and the increased vascularity persisted for at least 2 weeks. The deposition and persistence of ferric iron was also greater in hemophilic mice. We hypothesize that iron plays a role in promoting excess angiogenesis after wounding as it had been proposed to do in hemophilic arthropathy. We have demonstrated that impaired coagulation leads to delayed wound healing with abnormal histology. Our findings have significant implications for treatment of patients with hemophilia, and also highlight the importance of rapidly establishing hemostasis following trauma or surgery.

Pathogenesis of haemophilic arthropathy

The pathogenetic mechanism of haemophilic arthropathy is multifactorial and includes degenerative cartilage-mediated and inflammatory synovium-mediated components. Intra-articular blood first has a direct effect on cartilage, as a result of the iron-catalysed formation of destructive oxygen metabolites (resulting in chondrocyte apoptosis), and subsequently affects the synovium, in addition to haemosiderin-induced synovial triggering. Both processes occur in parallel, and while they influence each other they probably do not depend on each other. This concept resembles degenerative joint damage as found in osteoarthritis as well as inflammatory processes in rheumatoid arthritis. These processes finally result in a fibrotic and destroyed joint.

Pathogenesis of hemophilic arthropathy

Intra-articular bleeding is the most common clinical manifestation of hemophilia, and can adversely affect joints and lead to arthropathy. Affected joints are associated with changes to the synovium, bone, cartilage and blood vessels. Iron plays a critical role in the pathogenesis of this condition, and may exert its effects through a variety of different mechanisms. Hemophilic arthropathy shares some injury characteristics with rheumatoid arthritis, although the degree of analogy is a matter of some debate. The influences of the mechanisms underlying joint inflammation are better understood for rheumatoid arthritis than for hemophilia, and it is hoped that this knowledge can be used to provide a more comprehensive knowledge of the pathological process of hemophilic arthropathy. This, in turn, may enable novel targets for therapeutic intervention to be identified.

Prophylaxis and von Willebrand's disease (vWD)

Von Willebrand disease (vWD) is an inherited bleeding disorder with a prevalence of approximately 1% in the general population. The bleeding occurs in this disorder primarily because of abnormalities in platelet adhesion, due to a primary deficiency or defect in the von Willebrand factor (vWF) often with a concomitant decrease in factor VIII (FVIII) levels. The mainstay of treatment for the majority of patients with vWD is desmopressin, which releases vWF from endothelial cells. For patients in which desmopressin is neither suitable or recommended, coagulation factor concentrates containing both vWF with FVIII are the alternative therapeutic option for controlling bleeding. Joint disease is an uncommon but disabling complication of vWD. The arthropathy results from recurrent bleeding into a joint, with the ankle and hip being the joints most often affected, particularly in patients with type 3 vWD. Without adequate treatment, persistent bleeding into joints can result in pain, joint degeneration, swelling and loss of range of motion (ROM). There is some evidence to suggest that joint bleeding and subsequent joint damage might be prevented by early prophylaxis. A soon to open clinical trial by the Von Willebrand Disease Prophylaxis Network (vWD PN) aims to further explore this treatment concept. This article addresses the prophylaxis of vWD, with a particular focus on joint disease.

Synovitis in a murine model of human factor VIII deficiency

Recurrent joint bleeding is the most common musculoskeletal manifestation of haemophilia and leads to a target joint and synovitis. The pathobiology of haemophilic synovitis (HS) is not well understood. Here the histopathological changes that occur following haemarthrosis were examined in an animal model for human HS. After two haemarthrosis, there was soft tissue and joint swelling and histological changes of acute synovitis included infiltration of the sub-synovial layer by mononuclear cells and neutrophils, thickening of the synovial membrane with villus formation, and hyperplasia of blood vessels. Subacute changes were evident after three haemarthrosis; muscle atrophy was present and an intense mononuclear cell infiltrate filled the sub-synovial space. There was destruction of articular surfaces and loss of cartilage. Seventeen months after three haemarthrosis, chronic joint changes included gross deformity and loss of congruence due to dense fibrotic tissue filling the joint space. The mononuclear inflammatory cell infiltrate and thickened synovial membrane persisted. Pits and erosions of articular surfaces and sub-chondral cysts were present. There was fibro-cartilage and new bone formation. This model of human HS should be useful to fully evaluate the biochemical and molecular changes that occur following joint bleeding and to test novel therapeutics to prevent HS.

Inhibition of antithrombin by hyaluronic acid may be involved in the pathogenesis of rheumatoid arthritis

Thrombin is a key factor in the stimulation of fibrin deposition, angiogenesis, proinflammatory processes, and proliferation of fibroblast-like cells. Abnormalities in these processes are primary features of rheumatoid arthritis (RA) in synovial tissues. Tissue destruction in joints causes the accumulation of large quantities of free hyaluronic acid (HA) in RA synovial fluid. The present study was conducted to investigate the effects of HA and several other glycosaminoglycans on antithrombin, a plasma inhibitor of thrombin. Various glycosaminoglycans, including HA, chondroitin sulfate, keratan sulfate, heparin, and heparan, were incubated with human antithrombin III in vitro. The residual activity of antithrombin was determined using a thrombin-specific chromogenic assay. HA concentrations ranging from 250 to 1000 μg/ml significantly blocked the ability of antithrombin to inhibit thrombin in the presence of Ca²⁺ or Fe³⁺, and chondroitin A, B and C also reduced this ability under the same conditions but to a lesser extent. Our study suggests that the high concentration of free HA in RA synovium may block antithrombin locally, thereby deregulating thrombin activity to drive the pathogenic process of RA under physiological conditions. The study also helps to explain why RA occurs and develops in joint tissue, because the inflamed RA synovium is uniquely rich in free HA along with extracellular matrix degeneration. Our findings are consistent with those of others regarding increased coagulation activity in RA synovium.

Increased expression of humanin peptide in diffuse-type pigmented villonodular synovitis: implication of its mitochondrial abnormality

OBJECTIVES

To define the pathogenesis of pigmented villonodular synovitis (PVNS), by searching for highly expressed genes in primary synovial cells from patients with PVNS.

METHODS

A combination of subtraction cloning and Southern colony hybridisation was used to detect highly expressed genes in PVNS in comparison with rheumatoid synovial cells. Northern hybridisation was performed to confirm the differential expression of the humanin gene in PVNS. Expression of the humanin peptide was analysed by western blotting and immunohistochemistry. Electron microscopic immunohistochemistry was performed to investigate the distribution of this peptide within the cell.

RESULTS

68 highly expressed genes were identified in PVNS. Humanin genes were strongly expressed in diffuse-type PVNS, but were barely detected in nodular-type PVNS, rheumatoid arthritis, or osteoarthritis. Humanin peptide was identified in synovium from diffuse-type PVNS, and most of the positive cells were distributed in the deep layer of the synovial tissue. Double staining with anti-humanin and anti-heat shock protein 60 showed that humanin was expressed mainly in mitochondria. Electron microscopy disclosed immunolocalisation of this peptide, predominantly around dense iron deposits within the siderosome.

CONCLUSIONS

Increased expression of the humanin peptide in mitochondria and siderosomes is characteristic of synovial cells from diffuse-type PVNS. Humanin is an anti-apoptotic peptide which is encoded in the mitochondrial genome. Present findings suggest that mitochondrial dysfunction may be the principal factor in pathogenesis of diffuse-type PVNS and that humanin peptide may play a part in the neoplastic process in this form of PVNS.

Experimental haemophilic synovitis: rationale and development of a murine model of human factor VIII deficiency

Haemophilia is a genetic disease as a result of the deficiency of blood coagulation factor VIII or IX. Bleeding is common, especially into joints where an inflammatory, proliferative synovitis develops resulting in a debilitating arthritis, haemophilic arthropathy. The pathogenesis of blood-induced haemophilic synovitis (HS) is poorly understood. The gross, microscopic and ultrastructural changes that occur in the synovial membrane following human and experimental hemarthrosis have been described. Repeated episodes of bleeding induce synoviocyte hypertrophy and hyperplasia, an intense neovascular response and inflammation of the synovial membrane. The component(s) in blood that initiates these changes is(are) not known, although iron is often proposed as one possibility. Here, we describe a novel murine model of human haemophilia A, which facilitates the examination of large number of animals and tissue specimens. The effects of hemarthrosis on the physical, gross and microscopic changes evoked following joint bleeding are described. Controlled, blunt trauma to the knee joint consistently resulted in joint swelling because of a combination of bleeding and inflammation. Hemosiderin was found in the synovial membrane. Similar to hemarthrosis in human haemophilia, joint bleeding resulted in acute morbidity evidenced by inactivity, weight loss and immobility. With time the animals recovered. The model of experimental murine HS described here has utility in the study of the pathogenesis of HS. This is the first of a series of articles, which will discuss the pathophysiology and characterize the model, with comparison of his model to others which have been published previously. It should provide a useful model to test potential therapeutic interventions.

Pathobiology of hemophilic synovitis I: overexpression of mdm2 oncogene

Hemophilia is a genetic disease caused by a deficiency of blood coagulation factor VIII or IX. Bleeding into joints is the most frequent manifestation of hemophilia. Hemarthrosis results in an inflammatory and proliferative disorder termed hemophilic synovitis (HS). In time, a debilitating, crippling arthritis, hemophilic arthropathy, develops. Although the clinical sequence of events from joint bleeding to synovitis to arthropathy is well documented, the component or components in blood and the molecular changes responsible for hemophilic synovitis are not known. Iron has long been suspected to be the culprit but direct evidence has been lacking. Previously, we showed that iron increased human synovial cell proliferation and induced c-myc expression. Here we show that bleeding into a joint in vivo and iron in vitro result in increased expression of the p53-binding protein, mdm2. Iron induced the expression of mdm2 by normal human synovial cells approximately 8-fold. In a murine model of human hemophilia A, hemarthrosis resulted in pathologic changes observed in human hemophilic synovitis and a marked increase in synovial cell proliferation. Iron, in vitro, induced the expression of mdm2. The molecular changes induced by iron in the blood may be the basis of the increase in cell proliferation and the development of hemophilic synovitis.

Differing effects of two iron compounds on experimental arthritis, TNF-α levels and immune response in mice

The effects of ferric-sorbitol-citrate and ferric-citrate on the severity of experimental arthritis, TNF-alpha secretion and the immune status were examined in mice. Arthritis was induced by footpad injection of methylated BSA and intraperitoneal injection of Bordetella pertussis. Joint and footpad swelling were measured weekly by a caliper. TNF-alpha serum levels were measured by ELISA. The immune status was determined by the response of mouse lymphocytes to ConA in vitro and by the antigen-presenting cell assay. Experimental arthritis was aggravated by ferric-citrate, whereas ferric-sorbitol-citrate did not promote it. If applied to normal (non-arthritic) mice three times a week for 4 weeks, ferric-sorbitol-citrate stimulated isolated splenocytes to increase production of TNF-alpha, the function of antigen-presenting cells and lymphocyte proliferation in response to ConA in vitro. TNF-alpha production by cultured splenocytes was also stimulated. In mice with antigen-induced arthritis, iron compounds did not additionally stimulate TNF-alpha production. Thus, we have shown that ferric-sorbitol-citrate stimulated TNF-alpha production, antigen-presenting cell activity and cellular immune response. Development of antigen-induced arthritis and TNF-alpha production in arthritic mice were not stimulated.

North American prophylaxis studies for persons with severe haemophilia: background, rationale and design

Arthropathy is associated with the greatest cost and morbidity to persons with haemophilia. Clinical protocols have been developed empirically to prevent or retard the development of joint disease using routine infusions of replacement factor concentrate. However, randomized clinical trials to determine optimal therapy to prevent joint disease in persons with severe haemophilia are lacking. Two clinical trials are ongoing to answer important clinical questions about the prevention of arthropathy. The first, a US randomized clinical trial, is comparing an aggressive multiple-infusion episode-based protocol to standard alternate-day prophylaxis to determine whether prevention of joint disease requires prevention of the bleeding event, per se, or can be achieved by promoting complete resolution of each bleeding event in the joint. This study included the development and validation of sensitive new physical and imaging scales to detect the earliest signs of joint disease in young children. The second, a single-arm, open-label Canadian study, is asking whether prevention of joint disease in young children can be individualized by escalating the dose and frequency of routine replacement infusions of factor concentrate based upon the clinical course of haemophilia in the affected child. Both of these studies will contribute valuable information regarding optimal therapy and will help establish evidence-based medicine for the management of severe haemophilia.