Pathological mechanism of joint destruction in haemophilic arthropathy.

Haemophilic arthropathy (HA), caused by intra-articular haemorrhage, is one of the most common complications in patients with haemophilia. Factor replacement therapy provides missing coagulation factors to prevent children with haemophilia from joint bleeding and decreases their risk for HA. However, haemophilia patients in developing countries are still suffering from HA due to insufficient replacement therapy. Symptoms such as pain and activity limitations caused by HA seriously affect the functional abilities and quality of life of patients with HA, causing a high disability rate in the haemophilia cohort. The pathological mechanism of HA is complicated because the whole pathological mainly involves hypertrophic synovitis, osteopenia, cartilage and bone destruction, and these pathological changes occur in parallel and interact with each other. Inflammation plays an important role in the whole complex pathological process, and iron, cytokines, growth factors and other factors are involved. This review summarizes the pathological mechanism of HA to provide background for clinical and basic research.

p53 predominantly regulates IL-6 production and suppresses synovial inflammation in fibroblast-like synoviocytes and adjuvant-induced arthritis.

BACKGROUND: Dominant-negative somatic mutations of p53 has been identified in the synovium of patients with rheumatoid arthritis (RA), in which interleukin (IL)-6 has been established as a pivotal inflammatory cytokine. The aim of this study was to clarify the significance of p53 in the longstanding inflammation in RA by modulating IL-6. METHODS: We established adjuvant-induced arthritis (AIA) in Lewis rats and treated them with p53 activator, and then analyzed the histopathology of the synovium and IL-6 expression. Human fibroblast-like synoviocytes (FLS) were cultured and transfected with p53-siRNA or transduced with adenovirus (Ad)-p53, and then assessed with MTT, TUNEL staining, and luciferase assay. IL-1ß, tumor necrosis factor (TNF)-α and IL-17 were used to stimulate FLS, and subsequent IL-6 expression as well as relevant signal pathways were explored. RESULTS: p53 significantly reduced synovitis as well as the IL-6 level in the AIA rats. It controlled cell cycle arrest and proliferation, but not apoptosis. Proinflammatory cytokines inhibited p53 expression in FLS, while p53 significantly suppressed the production of IL-6. Furthermore, IL-6 expression in p53-deficient FLS was profoundly reduced by NF-kappaB, p38, JNK, and ERK inhibitors. CONCLUSION: Our findings reveal a novel function of p53 in controlling inflammatory responses and suggest that p53 abnormalities in RA could sustain and accelerate synovial inflammation mainly through IL-6. p53 may be a key modulator of IL-6 in the synovium and plays a pivotal role in suppressing inflammation by interaction with the signal pathways in RA-FLS. Interfering with the p53 pathway could therefore be an effective strategy to treat RA.

Lysophosphatidic acid receptor inhibition as a new multipronged treatment for rheumatoid arthritis.

OBJECTIVE: To investigate the effect of lysophosphatidic acid (LPA) receptor inhibition in a mouse model of autoantibody-mediated arthritis. METHODS: Arthritis was induced in C57BL/6 mice by K/BxN serum transfer. Arthritic mice were treated with the LPA receptor antagonist, Ki16425 and arthritis severity was assessed clinically and histologically. Expression of inflammatory mediators in joints was identified by a mouse cytokine array and validated by western blot and real-time PCR assays. Effects of treatment with LPA receptor antagonist or with small interfering RNA on bone metabolism were assessed by in vitro assays of osteoclastogenesis, bone resorption, osteoblasts differentiation and bone mineralisation. RESULTS: Mice treated with the LPA receptor antagonist Ki16425 showed attenuated arthritis characterised by reduction of synovial inflammation, cartilage damage and, more markedly, bone erosion. We detected increased apoptosis, reduction of inflammatory mediators and of bone remodelling proteins in arthritic joints from mice treated with Ki16425. In addition, we demonstrated that inhibition or suppression of LPA1 receptor reduces osteoclast differentiation and bone resorption and, on the contrary, it promotes differentiation of osteoblasts and bone mineralisation. CONCLUSIONS: Pharmacological inhibition of LPA1 receptor in the K/BxN serum-transfer arthritis model led to reduction of severity of arthritis involving multiple mechanisms, increased apoptosis, reduced inflammatory mediators and proteins involved in bone remodelling, that show LPA1 as a very promising target in rheumatoid arthritis treatment.

Inhibition of fms-like tyrosine kinase 3 alleviates experimental arthritis by reducing formation of dendritic cells and antigen presentation.

TKs are intracellular signaling molecules essential for cell homeostasis. Inhibition of TKs is used in treatment of malignancies and diabetes mellitus. The present study evaluated the role of Flt3 in antigen-induced arthritis. Mice were immunized with mBSA, and arthritis was induced by an i.a. injection of mBSA. Treatment with the Flt3 inhibitor sunitinib was started together with mBSA immunization or together with the induction of arthritis. The mBSA-injected joints were evaluated morphologically for signs of synovitis and bone/cartilage destruction. Markers of bone metabolism and antibody responses were measured by ELISA. Maturation of DCs in the bone marrow and spleen was evaluated by flow cytometry. Sunitinib treatment reduced the intensity of synovitis and the incidence of bone destruction. The reduction in bone destruction was seen when the treatment was started at the time of immunization or at the time of arthritis induction. The antiarthritic effect was achieved by inhibition of DCs, reduction of antibody production, and bone metabolism. Inhibition of Flt3 is a potent antiarthritic mechanism reducing antigen presentation, synovial inflammation, and bone resorption. Down-regulation of TKs may be a useful tool in the treatment of human RA.

The role of properdin in murine zymosan-induced arthritis.

Using properdin-deficient and wild-type mice, we have investigated the role of properdin in development and progression of zymosan-induced arthritis. At the initial phase of local, zymosan-induced inflammation, properdin-deficient and wild-type mice showed bone erosion, proteoglycan loss and cell infiltration. Compared to wild-type, properdin-deficient mice had reduced C5a and IL-6 but similar synovial TNF-alpha and sRANKL levels. Both groups showed a systemic immune response. Elevated IFN-gamma production and STAT1 signaling in splenocytes and a shift to Th1 response in popliteal lymph nodes were observed in properdin-deficient mice. Properdin-deficient mice had significantly less circulating zymosan-specific IgG antibodies than wild-type. In the chronic phase, the lack of properdin resulted in significant proteoglycan loss in the joints and lower cartilageneous STAT1 expression. The level of synovial C5a on day 30 was comparable in both groups, but C5aR staining was more apparent in the joints of properdin-deficient mice. Our data show that properdin is an important player in processes involved in inflammatory joint degradation.

Deficiency of NADPH oxidase components p47phox and gp91phox caused granulomatous synovitis and increased connective tissue destruction in experimental arthritis models.

Recent studies indicated that the nicotinamide dinucleotide phosphate oxidase (NADPH) oxidase-derived oxygen radicals plays a deleterious role in arthritis. To study this in more detail, gonarthritis was induced in NADPH oxidase-deficient mice. Mice received an intraarticular injection of either zymosan, to elicit an irritant-induced inflammation, or poly-L-lysine coupled lysozyme, to evoke an immune-complex mediated inflammation in passively immunized mice. In contrast to wild-type mice, arthritis elicited in both p47phox(-/-) and gp91(-/-) mice showed more severe joint inflammation, which developed into a granulomatous synovitis. Treatment with either Zileuton or cobra venom factor showed that the chemokines LTB4 and complement C3 were not the driving force behind the aggravated inflammation in these mice. Arthritic NADPH oxidase-deficient mice showed irreversible cartilage damage as judged by the enhanced aggrecan VDIPEN expression, and chondrocyte death. Furthermore, only in the absence of NADPH oxidase-derived oxygen radicals, the arthritic joints showed osteoclast-like cells, tartrate-resistant acid phosphatase (TRAP)-positive/multinucleated cells, extensive bone erosion, and osteolysis. The enhanced synovial gene expression of tumor necrosis factor-alpha, interleukin-1alpha, matrix metalloproteinase (MMP)-3, MMP-9 and receptor activator of NF-kappaB ligand (RANKL) might contribute to the aggravated arthritis in the NADPH oxidase-deficient mice. This showed that the involvement of NADPH oxidase in arthritis is probably far more complex and that oxygen radicals might also be important in controlling disease severity, and reducing joint inflammation and connective tissue damage.

[Seven cases of remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome].

Among the elderly patients with seronegative polyarthritis, McCarty et al. (1985) proposed a disease entity of "remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome", but only a few cases have been reported in Japan. Here we report 7 cases suspicious of RS3PE syndrome, 2 men and 5 women with an average age of 75.9 years, ranging from 67-82 years. Their common findings were (1) relatively acute onset, (2) polyarthritis, (3) pitting edema of the dorsum of both hands and both feet, and (4) negative rheumatoid factor and antinuclear antibody. McCarty et al. found that RS3 PE syndrome was more prevalent in men; however, in our experience, the opposite was observed. The clinical courses of all patients were good, and they were effectively treated either by small dosages of oral prednisolone, nonsteroidal antiinflammatory drugs, or Chinese herbal (Kampo) medicines. Since this syndrome might not be rare in Japan, it seems necessary to evaluate elderly patients with seronegative polyarthritis with pitting edema as RS3PE syndrome in their routine medical examinations.

The hemagglutination-positive phenotype of Mycoplasma synoviae induces experimental infectious synovitis in chickens more frequently than does the hemagglutination-negative phenotype.

Inoculation with hemagglutination-positive (HA+) cultures of Mycoplasma synoviae AAY-4 induced acute synovitis significantly more frequently (P = 0.001) in chicken tibiotarsal-tarsometatarsal joints than did inoculation with HA-negative (HA-) cultures derived from the same clone of AAY-4. Immunoblotting analyses showed that HA+ cultures abundantly expressed two phase-variable hemadherence-associated surface membrane proteins of 53 kDa and 48 to 50 kDa defined by monoclonal antibodies. HA- cultures lacked the 53-kDa proteins and synthesized truncated 27- to 30-kDa forms of the 48- to 50-kDa proteins. Inoculation of cyclosporin A (CsA) into infected joints significantly decreased the frequency of acute synovitis (P = 0.001). Moreover, repeated intra-articular inoculation of CsA (three doses of 1 mg at 2-day intervals) significantly reduced the local antibody response to M. synoviae in the joints treated with CsA.

Induction of a proinflammatory cytokine network by Mycoplasma arthritidis-derived superantigen (MAS).

Mycoplasma arthritidis is an arthritogenic organism for rodents, producing a superantigen (MAS). It has been postulated that mycoplasmas or superantigens thereof might play a role in human rheumatoid arthritis. Since M. arthritidis fulfills both, the present study was performed to investigate MAS-specific cytokine induction. Human or murine leukocytes were stimulated with MAS, staphylococcal enterotoxin E (SEE), or lipopolysaccharide (LPS). Cytokines were measured by ELISA, Bioassay, and RT-PCR. The response to MAS in humans was individually restricted, in contrast to the response to SEE or LPS. Furthermore, MAS showed the same capacity for inducing proinflammatory cytokines as interleukin (IL)-1 IL-6, and IL-8 as SEE and LPS. However, MAS showed a significantly decreased capacity to induce the anti-inflammatory cytokine IL-10 and IL-1RA. In mice, the reactivity to MAS was strictly MHC-II restricted, in contrast to that of SEE or LPS. The individual response to MAS in humans might be explained by the difference of the HLA-DR haplotype because H-2-differing mouse strains showed the same discrepancies. MAS induced an overproduction of proinflammatory cytokines, when its ability to induce proinflammatory and anti-inflammatory cytokines was compared with those of SEE and LPS. The individual response may explain an MHC linkage, and the failure to induce anti-inflammatory cytokines may be the reason for a chronic disease in contrast to acute inflammation.

Expression of CD60 on multiple cell lineages in inflammatory synovitis.

BACKGROUND: CD60 is a recently described T cell subset marker that is expressed on the surface of most T lymphocytes in synovial tissue and fluid and on a smaller proportion of peripheral T cells. Activation of T lymphocytes can be triggered through CD60. CD60 is also expressed by neuroectodermally derived cells in thymic epithelium and in skin. EXPERIMENTAL DESIGN: Immunohistologic analysis of CD60 expression in synovium and thymus was performed using formalin-fixed tissue samples. Nonlymphoid cell lines grown from similar tissues were analyzed by flow cytometry. RESULTS: CD60 was readily identified in formalin-fixed, paraffin-embedded tissues. Simultaneous examination of CD60 distribution and cell morphology demonstrated that, in addition to its presence on T cells, CD60 was also expressed by a variety of nonlymphoid cells in synovium, including synovial lining cells, vascular endothelium, and dendritic-appearing cells deep within synovial tissue. Synovial tissue expression of CD60 was similar in rheumatoid arthritis and in other forms of inflammatory arthritis. In addition, it was strongly expressed by giant cells in pigmented villonodular synovitis. Surface expression of CD60 was detected by flow cytometry on cultured synoviocytes and on other CD60+ nonlymphoid cells, thus excluding adsorption of CD60 shed by T cells as a sufficient explanation of the immunohistologic findings. CONCLUSIONS: These results define the T cell-activating CD60 determinant as a broadly distributed Ag within synovial tissue, with a possible functional role in the activation of a variety of cellular populations. CD60 may also be a marker for previously undescribed cell subsets in the synovial compartment, possibly including a cell population of neuroectodermal origin.

Pustular psoriasis and aseptic purulent arthritis: possible role of leukotrienes B4 and C4 in a flare of synovitis.

BACKGROUND: Arthritis is a frequent complication of pustular psoriasis. However, the mechanism of onset of this arthritis still remains unclear. OBJECTIVES: The present study was conducted to determine whether leukotriene (LT) B4 or LTC4 is one of the proinflammatory mediators that possibly enhance exacerbation of the arthritis lesions. METHODS: We investigated the condition of the arthritis and autopsy findings of two cases of generalized pustular psoriasis with the severe complication of aseptic purulent arthritis. We also measured the synovial fluid levels of LTB4 and LTC4 by radioimmunoassay. RESULTS: The collected synovial fluid was purulent, but nonbacterial, and the synovium of the knee joint showed histopathologic evidence of polymorphonuclear leukocyte (PMN) invasion, edema and dilatation of small vessels showing similarity to a histologic reaction in the skin lesions. The immunoreactive (i-) LTB4 and i-LTC4 in the samples significantly exceeded the amount measured in osteoarthritis patients used as the controls. CONCLUSION: Thus, i-LTB4 and i-LTC4 appear to be generated in the arthritis lesions of pustular psoriasis, the former attracting PMNs to the joints and the latter causing exudation of synovial fluid.

Monocyte chemoattractant protein-1 (MCP-1) in inflammatory joint diseases and its involvement in the cytokine network of rheumatoid synovium.

Macrophages infiltrated into synovium play an important role in joint destruction in inflammatory joint diseases. In this study we focused on the production of monocyte chemoattractant protein-1 (MCP-1), a recently identified monocyte chemotactic protein, by inflammatory synovium. Synovial fluid (SF) from rheumatoid arthritis (RA), osteoarthritis, gout, and traumatic arthritis contained MCP-1. MCP-1 was produced in the synovium of patients with RA and other inflammatory joint disease in in vitro culture systems; differences in the amounts produced were not significant. Synovial MCP-1 production in RA was further investigated. Levels of MCP-1 were significantly correlated with levels of IL-1 beta, IL-6, and IL-8 in the culture supernatants of synovia from RA. Using immunohistochemical techniques, MCP-1 was detected in the lining and sublining cells and in the vascular endothelial cells of rheumatoid synovia. Rheumatoid synovia with active inflammation were stained more intensely by anti-MCP-1 antibody than were those with weak or inactive inflammation. IL-1 beta and TNF-alpha stimulated the expression of MCP-1 mRNA and de novo MCP-1 synthesis by cultured synovial cells. These results suggest the production of MCP-1 by synovium of various inflammatory joint diseases. In rheumatoid synovium, a cytokine network involving MCP-1 and other proinflammatory cytokines (IL-1 beta, IL-6, IL-8, and TNF-alpha) contributes to the immunopathogenesis of RA.

[The combined action of an ultrahigh-frequency electrical field bitemporally and decimeter waves on the thymus area in the combined therapy of rheumatoid arthritis patients]. / Sochetannoe vozdeistvie élektricheskogo polia ul'travysokoi chastoty bitemporal'no i detsimetrovykh voln na oblast' timus v kompleksnoi terapii bol'nykh revmatoidnym artritom.

The thymus of rheumatoid arthritis (RA) patients was exposed to combined action of bitemporal UHF electric field and decimeter waves to study immunomodulating effect of the combination. Biochemical, immunological and endocrinological findings during the patients follow-up gave evidence for conclusion on activation of the hypothalamic-hypophyseal-thymic axis. A response was achieved in RA seronegative variant with concomitant synovitis. This may be due to genetic factors.

Aloe vera and the inflamed synovial pouch model.

Administration of air under the skin produced a pouch wall that closely resembled a synovium in that the inner lining was made up of macrophages and fibroblasts. Administration of 1% carrageenan directly into the 7-day-old air pouch produced an inflammation characterized by an increased number of mast cells in pouch fluid as well as an increase in wall vascularity. A punch biopsy weight of the pouch wall did not reveal an increase in 1% carrageenan-treated animals. However, a 10% Aloe vera treatment of carrageenan-inflamed synovial pouches reduced the vascularity 50% and the number of mast cells in synovial fluid 48%. The pouch wall punch biopsy weight was increased by A. vera, which was verified by histologic examination of the inner synovial lining. Aloe vera stimulated the synovial-like membrane, as evidenced by an increased number of fibroblasts, suggesting that A. vera stimulated fibroblasts for growth and repair of the synovial model. The synovial air pouch can be used to study simultaneously the acute anti-inflammatory and fibroblast stimulating activities of A. vera.

C reactive protein and immunoglobulin G in synovial fluid and serum in joint disease.

C reactive protein (CRP) and immunoglobulin G (IgG) were measured in synovial fluid and serum of 72 patients (29 with rheumatoid arthritis (RA), 17 with osteoarthritis, 11 with crystal synovitis, seven with undifferentiated arthritis, and eight with seronegative arthritis). The synovial fluid:serum (SF:S) ratios were compared with those calculated from the SF:S ratios of transferrin, caeruloplasmin, and alpha 2 macroglobulin, using the binomial test within groups and the Mann-Whitney test between groups. In RA synovial fluid CRP concentrations were lower than expected and IgG concentrations higher than expected. In osteoarthritis CRP concentrations were higher than expected. In seronegative arthritis IgG concentrations were raised. The ratio of CRP:IgG was depressed in RA. These findings are consistent with a role for CRP in the inflammatory process of RA, while the CRP:IgG ratio may be of value in the differential diagnosis of joint disease.

Neuromodulation of synovitis: capsaicin effect on severity of experimental arthritis.

This study addresses the effect of capsaicin on the severity of inflammation in experimental arthritis in the cat. Animals were sensitized with methylated bovine serum albumin (mBSA) and sequential serum antibody levels measured by enzyme-linked immunosorbent assay (ELISA). Synovitis was induced by intra-articular injection of mBSA. Histopathology revealed marked inflammatory cell infiltration and synovial cell hypercellularity, in comparison with the saline-injected control joint which showed no synovitis. In animals given intra-articular capsaicin concurrently with mBSA, there was consistently a diminution in the severity of inflammation compared with contralateral joints receiving mBSA alone. In this experimental system capsaicin appears to moderate the severity of inflammation in feline antigen-induced arthritis.

Reactive oxygen species selectively deplete normal T lymphocytes via a hydroxyl radical dependent mechanism.

Chronic inflammatory synovitis is characterized by both lymphocytic infiltrates and persistent polymorph exudates. Activated polymorphs release reactive oxygen species (ROS) during inflammation, but the contribution that these make to the lymphocyte abnormalities associated with RA has been little studied. We therefore investigated the cytotoxic effects of the reactive oxygen species on human peripheral blood mononuclear cells (PBMC). PBMC were exposed to RPMI 1640 medium previously irradiated for up to 60 min. Consistent dose-dependent killing was observed at 24 h. Antioxidant studies indicated that H2O2 was the effective species. Catalase, which specifically degrades H2O2, gave almost total protection against cell death, while superoxide dismutase (SOD), thiourea, and mannitol were largely ineffective. Addition of exogenous H2O2 caused an identical pattern of cell death to that observed with irradiated medium. PBMC cultures supplemented with desferrioxamine (a ferric iron chelator) also gave significant protection, suggesting that H2O2 mediated its effects via OH radicals. Analysis of lymphocyte subpopulations showed that ROS caused a selective depletion, depending on the level of H2O2 present. Low levels induced a specific loss of CD8+ cells, while higher concentrations caused significant loss of CD4+ T cells as well. sIg+ B cells were unaffected at either concentration. This selective lymphotoxic effect of ROS may be of considerable importance in the pathogenesis of autoimmune inflammatory disease.

Immune complex deposition in the development of acute synovitis in the rabbit knee joint: quantitative, kinetic and morphological aspects.

The pathology of acute synovitis induced by immune complexes was investigated in this study. The reversed passive Arthus method of lesion induction was utilized, in conjunction with radiolabeled cell and protein markers, to quantitate inflammatory parameters and ascertain their kinetics in the synovial tissues of the rabbit. The rates of increased vessel permeability, polymorphonuclear leukocyte infiltration and platelet deposition were studied using 125-I-albumin, 51-CR-PMN-leukocytes and 111-In-platelets, respectively. Increase in vessel permeability over time was found to directly correlate with increased leukocyte infiltration (r = 9.08; P less than 0.01). Similar correlations between vascular permeability and platelet accumulation, and leukocyte infiltration and platelet accumulation, were not observed. The histological evaluation of synovial lesions corroborated the kinetic findings.

The effect of anti-inflammatory and rheumatoid disease modifying drugs on prolonged immune and non-immune inflammation in the six-day air pouch of rats.

The six-day air pouch model of synovitis in rats was used to study the effects of non-steroidal and anti-rheumatic drugs on cell accumulation and exudate formation. Inflammation was induced in the six-day air pouch either with the non-immune irritant carrageenan or the immune irritant Bordetella pertussis. Indomethacin reduced cell accumulation and exudate formation in both models. In contrast levamisole and D-penicillamine were unable to reduce either parameter, D-penicillamine actually producing at certain times a pro-inflammatory effect. The steroid dexamethasone caused the total inhibition of inflammatory exudate formation and cell accumulation. The six-day air pouch of rats may therefore be useful for the detection of agents which inhibit chronic inflammation.