[Vitamin D like one of few prevention possibilities for autoimmune diseases?] / Hoe helpt vitamine D auto-immuunziekten voorkomen?

Data from elderly Americans of an age of ≥50 years that were included in a large nationwide, randomized, double-blind, placebo-controlled prevention trial, show that vitamin D supplementation, alone or in combination with omega-3 fatty acids, reduces autoimmune disease risk with 22%. These Americans were treated with 2000 IU/day cholecalciferol (vitamin D) for a period of 5 years alone or in combination with 1g/day omega-3 fatty acids. Both treatments resulted in a significant reduction of the incidence of autoimmune diseases. The findings were more pronounced after two years after the start of the supplementation. Having a lower body index seems to be beneficial for the vitamin D effects. The question is via which pathophysiological mechanism(s) does vitamin D work. More and more of the secrets of the effects of vitamin D on the immune system and in particular on T cells are becoming identified and this study motivates to dig further.

The anti-inflammatory potency of biologics targeting tumour necrosis factor-α, interleukin (IL)-17A, IL-12/23 and CD20 in hidradenitis suppurativa: an ex vivo study.

BACKGROUND: Biologics targeting inflammatory mediators can achieve clinical improvements in hidradenitis suppurativa (HS). However, their clinical efficacy shows great interpatient variability in daily practice. OBJECTIVES: To investigate the anti-inflammatory potency of a selection of currently available biologics and prednisolone for the treatment of HS in an ex vivo skin culture system using lesional HS biopsies. METHODS: Lesional skin samples from 10 patients with HS and skin samples from five healthy controls were cultured ex vivo and exposed to prednisolone or biologics targeting tumour necrosis factor (TNF)-α, interleukin (IL)-17A, IL-12/23p40 or CD20 (adalimumab, infliximab, secukinumab, ustekinumab and rituximab, respectively). Real-time quantitative polymerase chain reaction and cytokine bead arrays were used to measure the inhibitory effect of the biologics on cytokines and antimicrobial peptides (AMPs). RESULTS: The relative mRNA expression of all tested cytokines and AMPs was significantly downregulated by all anti-inflammatory agents (P < 0·001). The protein production of the proinflammatory cytokines TNF-α, interferon γ, IL-1ß, IL-6 and IL-17A was significantly inhibited by adalimumab, infliximab, ustekinumab, prednisolone (all P < 0·001) and rituximab (P = 0·0071), but not by secukinumab (P = 0·0663). On both mRNA and protein levels, adalimumab, infliximab and prednisolone reduced the levels of a broader mix of individual cytokines than secukinumab, ustekinumab and rituximab. Moreover, a significant inhibitory effect on mRNA expression levels of inflammatory markers in healthy control skin was observed only for TNF-α inhibitors (P < 0·001) and prednisolone (P = 0·0015). CONCLUSIONS: This ex vivo study suggests that TNF-α inhibitors and prednisolone are the most powerful inhibitors of proinflammatory cytokines and AMPs in HS lesional skin, which concurs with our clinical experience in patients with HS.

Experimental Arthritis Mouse Models Driven by Adaptive and/or Innate Inflammation.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease mainly affecting synovial joints. The clinical presentation of RA shows the heterogeneity of this disease with its underlying complex interactions between the innate and adaptive immune system and flare-ups of disease. Different disease models such as collagen induced arthritis, antigen induced arthritis, and Streptococcal cell wall induced arthritis can be exploited to investigate different aspects of the pathogenesis of arthritis. The disease can be monitored macroscopically over time via scoring systems. For histological examination, paraffin embedded knee sections can be used for hematoxylin and eosin staining to visualize cellular infiltration as well as for tartrate-resistant acid phosphatase (TRAP) staining to identify osteoclast-like cells. Cellular infiltration of the synovium by different myeloid cells such as tissue resident macrophages, dendritic cells and neutrophils can be monitored using flow cytometry. Here, we describe the methods for inducing the different mouse models for arthritis, including scoring systems per model, histological and flow cytometric analysis.

Arthritic and non-arthritic synovial fluids modulate IL10 and IL1RA gene expression in differentially activated primary human monocytes.

OBJECTIVE: Synovitis with an increased presence of macrophages is observed in osteoarthritis (OA) and rheumatoid arthritis (RA). Given the important role of macrophages in arthritis, we investigated the influence of OA and RA synovial fluid (SF) on primary human monocytes (Mo), their lineage precursors. METHOD: Adherent monocytes without any stimulation (Mo(-)) or stimulated with IFN-γ and TNF-α (Mo(IFN-γ/TNF-α)) or IL-4 (Mo(IL-4)) were exposed to SF from 6 donors without any known joint disease (SF-Ctrl), 10 OA donors (SF-OA), and 10 RA donors (SF-RA). The transcriptional expression of IL6, IL1B, TNFA, IL10, CCL18, CD206, and IL1RA was analyzed. RESULTS: Mo(-) exposed to SF-RA had a lower expression of IL10 and a higher expression of IL1RA than when exposed to SF-Ctrl. Mo(IL-4) exposed to SF-RA had a lower expression of IL10 and CCL18 than when exposed to SF-Ctrl and Mo(IFN-γ/TNF-α) were not affected by SF-RA. Mo exposed to SF-OA also expressed less IL10, but only upon stimulation with IL-4, and expressed more IL1RA than when exposed to SF-Ctrl in any condition. CONCLUSION: A lower expression of IL10 may be regarded as a response to less inflammatory conditions since IL10 expression is higher in response to IFN-γ/TNF-α stimulation, probably as a feedback mechanism. Therefore, the lower expression of IL10 and the higher expression of IL1RA in Mo exposed to arthritic than to non-arthritic SF suggest that arthritic SF is mainly reducing the inflammatory responses in Mo. This may mimic the response of monocytes/macrophages recruited to the joint, where feedback mechanisms counteract pro-inflammatory processes.

Th17 cells, but not Th1 cells, from patients with early rheumatoid arthritis are potent inducers of matrix metalloproteinases and proinflammatory cytokines upon synovial fibroblast interaction, including autocrine interleukin-17A production.

OBJECTIVE: Both Th1 cells and Th17 cells have been recognized in rheumatoid arthritis (RA); however, it remains unclear whether Th1 cells and/or Th17 cells are involved in driving disease chronicity and destructiveness. The aim of this study was to identify and characterize the functional role of Th17 cells in early RA. METHODS: Flow cytometry analysis was performed on peripheral blood mononuclear cells (PBMCs) from treatment-naive patients with early RA and age-matched healthy volunteers. PBMCs from these patients, naive T cells, and primary CCR6- Th1 cells and CCR6+ Th17 cells were sorted and cultured in the absence or presence of synovial fibroblasts from patients with early RA (RASFs), and cytokine expression and gene transcription were analyzed. In addition, tumor necrosis factor α (TNFα)- and interleukin-17A (IL-17A)-blocking experiments were performed. RESULTS: In the PBMCs of treatment-naive patients with early RA, an increased fraction of IL-17A-and TNFα-producing CCR6+ Th17 cells was observed. When cocultured with RASFs, these primary Th17 cells were potent inducers of IL-6 and IL-8 and the tissue-destructive enzymes matrix metalloproteinase 1 (MMP-1) and MMP-3, whereas primary Th1 cells or naive T cells were not. Importantly, specific up-regulation of IL-17A but not TNFα or interferon-γ was observed in RASF/Th17 cell cocultures. In addition to TNFα blocking, IL-17A neutralization was required to further down-regulate Th17 activity in RASF/Th17 cell cocultures. CONCLUSION: Th17 cells, but not Th1 cells, cooperated with RASFs in a proinflammatory feedback loop, revealing a potential mechanism by which human Th17 cells drive chronic destructive disease in patients with RA. Furthermore, the neutralization of IL-17A activity is essential in current anti-TNF therapies to suppress Th17 cell activity in patients with early RA and potentially other Th17 cell-mediated disorders.

1,25-dihydroxyvitamin D3 modulates Th17 polarization and interleukin-22 expression by memory T cells from patients with early rheumatoid arthritis.

OBJECTIVE: To examine the immunologic mechanism by which 1,25-dihydroxyvitamin D(3) (1,25[OH](2)D(3)) may prevent corticosteroid-induced osteoporosis in patients with early rheumatoid arthritis (RA), with a focus on T cell biology. METHODS: Peripheral blood mononuclear cells (PBMCs) and CD4+CD45RO+ (memory) and CD4+CD45RO- (non-memory) T cells separated by fluorescence-activated cell sorting (FACS) from treatment-naive patients with early RA were stimulated with anti-CD3/anti-CD28 in the absence or presence of various concentrations of 1,25(OH)(2)D(3), dexamethasone (DEX), and 1,25(OH)(2)D(3) and DEX combined. Levels of T cell cytokines were determined by enzyme-linked immunosorbent assay and flow cytometry. RESULTS: The presence of 1,25(OH)(2)D(3) reduced interleukin-17A (IL-17A) and interferon-gamma levels and increased IL-4 levels in stimulated PBMCs from treatment-naive patients with early RA. In addition, 1,25(OH)(2)D(3) had favorable effects on tumor necrosis factor alpha (TNFalpha):IL-4 and IL-17A:IL-4 ratios and prevented the unfavorable effects of DEX on these ratios. Enhanced percentages of IL-17A- and IL-22-expressing CD4+ T cells and IL-17A-expressing memory T cells were observed in PBMCs from treatment-naive patients with early RA as compared with healthy controls. Of note, we found no difference in the percentage of CD45RO+ and CD45RO- cells between these 2 groups. Interestingly, 1,25(OH)(2)D(3), in contrast to DEX, directly modulated human Th17 polarization, accompanied by suppression of IL-17A, IL-17F, TNFalpha, and IL-22 production by memory T cells sorted by FACS from patients with early RA. CONCLUSION: These data indicate that 1,25(OH)(2)D(3) may contribute its bone-sparing effects in RA patients taking corticosteroids by the modulation of Th17 polarization, inhibition of Th17 cytokines, and stimulation of IL-4.

Does anti-mutated citrullinated vimentin have additional value as a serological marker in the diagnostic and prognostic investigation of patients with rheumatoid arthritis? A systematic review.

OBJECTIVE: To review the diagnostic and prognostic value of anti-mutated citrullinated vimentin (MCV) in rheumatoid arthritis, taking into account the already available serology. METHODS: Medline was searched via PubMed (1966 to May 2008) for anti-MCV and related terms, arthritis and arthropathies. Studies with anti-MCV, arthritis/arthropathy, and primary data on diagnosis and/or prognosis were included. Their methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) instrument for diagnostic studies and the modified Hayden list for prognostic studies. RESULTS: Of 14 eligible studies, 11 included diagnostic data and 3 included prognostic data. No study evaluated anti-MCV as an added diagnostic test to the already available anti-cyclic citrullinated peptide (CCP) and rheumatoid factor serology. One study included the optimal patient spectrum resulting in a sensitivity of 0.59 and specificity of 0.98. A total of 10 diagnostic case-control studies using the same anti-MCV kit showed a sensitivity of 0.64-0.84 and a specificity of 0.79-0.96. This almost equalled the performance of anti-CCP in the same studies. The prognostic evaluation of anti-MCV was limited by differences in study methodology, outcome and statistical modelling. Individual studies showed moderate associations for anti-MCV and radiological progression with the strength of the association comparable to that of anti-CCP. CONCLUSIONS: Study heterogeneity, choice of study population and methodological limitations limited overall conclusions about the true diagnostic and prognostic test performance of anti-MCV. Evidence from the diagnostic case-control studies suggests that anti-MCV may be used as an alternative for anti-CCP.

Comparison of E-selectin expression at mRNA and protein levels in murine models of inflammation.

BACKGROUND: Drug targeting to activated endothelial cells via E-selectin is currently being explored as a new approach to treat chronic inflammatory disorders. This approach uses E-selectin directed antibodies as carrier molecules to selectively deliver anti-inflammatory drugs into activated endothelial cells, thereby theoretically decreasing drug-associated side-effects. Therapeutic effects of developed drug targeting constructs will have to be tested in animal models of inflammation, in which E-selectin is expressed during the course of the disease. In this study several murine models of inflammation were investigated regarding expression of E-selectin. METHODS: E-selectin expression was determined both at the mRNA level using RT-PCR and at the protein level by immunohistochemistry using two monoclonal antibodies (10E9.6 and MES-1). The models studied included delayed type hypersensitivity induced skin inflammation, dextran sodium sulphate induced colitis, kidney ischemia/reperfusion injury, atherosclerosis in ApoE knockout mice, and collagen induced arthritis. RESULTS: In all animal models E-selectin mRNA expression was detected, although to a different extent. In contrast, only the delayed type hypersensitivity model and, to a minor extent, the collagen induced arthritis model showed E-selectin protein expression. CONCLUSION: These results stress the need to determine E-selectin protein expression and not only mRNA expression, when choosing an animal model for testing E-selectin directed drug targeting preparations. In addition, in the arthritis model, E-selectin protein detection was dependent on the particular anti-E-selectin antibody used. This finding may not only have implications for the development and/or choice of homing devices to be used in E-selectin directed drug targeting preparations, but also for inflammation research in general.

Local overexpression of adeno-viral IL-4 protects cartilage from metallo proteinase-induced destruction during immune complex-mediated arthritis by preventing activation of pro-MMPs.

OBJECTIVE: To determine whether IL-4 protects against metalloproteinase-induced cartilage destruction during immune complex mediated arthritis and to elucidate its mechanism. METHODS: Experimental immune complex arthritis (ICA) was raised by injecting lysozyme into the knee joints of mice which previously were given anti-lysozyme antibodies. Three days before ICA induction, mice were injected into the right knee joint with either IL-4 expressing or empty control recombinant human type 5 adenovirus. Joint inflammation and cartilage destruction (PG depletion, erosion) was measured by histology of total knee joints. Aggrecan breakdown in cartilage caused by metalloproteinases (MMPs) was studied by immunolocalization using anti-VDIPEN antibodies. RESULTS: Four days after ICA induction, histological analysis showed comparable exudate and infiltrate in both groups. Depletion of proteoglycans as measured by loss of red staining was also comparable in both groups. IL-4 treatment inhibited MMP-mediated neoepitope expression by 90%. Moreover, cartilage matrix erosion was evident in all animals (10 out of 10 mice) in the control group and significantly diminished (only two out of ten mice) in the IL-4 treated group. Incubation of patellae with APMA, which activates latent MMPs resulted in VDIPEN expression which was not significantly different from control ICA indicating that comparable amounts of latent pro-MMPs are present in IL-4 treated arthritic knee joints. CONCLUSION: This study indicates that during ICA, IL-4 largely prevents MMP-mediated aggrecan breakdown and severe cartilage erosion. IL-4 does not inhibit production of latent MMPs by the chondrocyte but predominantly interferes with its activation.

Therapeutic effect of neutralizing endogenous IL-18 activity in the collagen-induced model of arthritis.

Two distinct IL-18 neutralizing strategies, i.e. a rabbit polyclonal anti-mouse IL-18 IgG and a recombinant human IL-18 binding protein (rhIL-18BP), were used to treat collagen-induced-arthritic DBA/1 mice after clinical onset of disease. The therapeutic efficacy of neutralizing endogenous IL-18 was assessed using different pathological parameters of disease progression. The clinical severity in mice undergoing collagen-induced arthritis was significantly reduced after treatment with both IL-18 neutralizing agents compared to placebo treated mice. Attenuation of the disease was associated with reduced cartilage erosion evident on histology. The decreased cartilage degradation was further documented by a significant reduction in the levels of circulating cartilage oligomeric matrix protein (an indicator of cartilage turnover). Both strategies efficiently slowed disease progression, but only anti-IL-18 IgG treatment significantly decreased an established synovitis. Serum levels of IL-6 were significantly reduced with both neutralizing strategies. In vitro, neutralizing IL-18 resulted in a significant inhibition of TNF-alpha, IL-6, and IFN-gamma secretion by macrophages. These results demonstrate that neutralizing endogenous IL-18 is therapeutically efficacious in the murine model of collagen-induced arthritis. IL-18 neutralizing antibody or rhIL-18BP could therefore represent new disease-modifying anti-rheumatic drugs that warrant testing in clinical trials in patients with rheumatoid arthritis.

IL-1-independent role of IL-17 in synovial inflammation and joint destruction during collagen-induced arthritis.

T cell IL-17 displays proinflammatory properties and is expressed in the synovium of patients with rheumatoid arthritis. Its contribution to the arthritic process has not been identified. Here, we show that blocking of endogenous IL-17 in the autoimmune collagen-induced arthritis model results in suppression of arthritis. Also, joint damage was significantly reduced. In contrast, overexpression of IL-17 enhanced collagen arthritis. Moreover, adenoviral IL-17 injected in the knee joint of type II collagen-immunized mice accelerated the onset and aggravated the synovial inflammation at the site. Radiographic and histologic analysis showed markedly increased joint destruction. Elevated levels of IL-1beta protein were found in synovial tissue. Intriguingly, blocking of IL-1alphabeta with neutralizing Abs had no effect on the IL-17-induced inflammation and joint damage in the knee joint, implying an IL-1 independent pathway. This direct potency of IL-17 was underscored in the unabated IL-17-induced exaggeration of bacterial cell wall-induced arthritis in IL-1beta(-/-) mice. In conclusion, this data shows that IL-17 contributes to joint destruction and identifies an IL-1-independent role of IL-17. These findings suggest IL-17 to be a novel target for the treatment of destructive arthritis and may have implications for tissue destruction in other autoimmune diseases.

IL-17 derived from juxta-articular bone and synovium contributes to joint degradation in rheumatoid arthritis.

The origin and role of IL-17, a T-cell derived cytokine, in cartilage and bone destruction during rheumatoid arthritis (RA) remain to be clarified. In human ex vivo models, addition of IL-17 enhanced IL-6 production and collagen destruction, and inhibited collagen synthesis by RA synovium explants. On mouse cartilage, IL-17 enhanced cartilage proteoglycan loss and inhibited its synthesis. On human RA bone explants, IL-17 also increased bone resorption and decreased formation. Addition of IL-1 in these conditions increased the effect of IL-17. Blocking of bone-derived endogenous IL-17 with specific inhibitors resulted in a protective inhibition of bone destruction. Conversely, intra-articular administration of IL-17 into a normal mouse joint induced cartilage degradation. In conclusion, the contribution of IL-17 derived from synovium and bone marrow T cells to joint destruction suggests the control of IL-17 for the treatment of RA.

Il-4 and IL-13, but not IL-10, protect human synoviocytes from apoptosis.

Interleukin-4, which has been contemplated for the treatment of rheumatoid arthritis and/or osteoarthritis because of its anticatabolic properties, has also been shown to modulate apoptosis. Because inadequate apoptosis is thought to contribute to synovial hyperplasia, we have investigated the ability of IL-4 and other Th2 cytokines to protect human synovial cells from apoptosis. Human synoviocytes or synovial explants were pretreated with IL-4, IL-10, and IL-13 before exposure to NO donor sodium-nitro-prusside (SNP). Apoptosis was evaluated by microscopy, annexin V-FITC, 3-(4,5-dimethylthiazol-2-gl)-5-(3-carboxymethoxylphenyl)-2-(4-sulphophenyl-2H: tetrazolium inner salt (MTS) test, pulse field gel electrophoresis, and a method proposed in this study based on (32)P Klenow end labeling of high m.w. DNA. Pretreatment by IL-4 or IL-13, but not IL-10, protected human synoviocytes from apoptosis induced by SNP. Even at doses as high as 2 mM SNP, up to 86% and 56% protection was achieved, after IL-4 and IL-13 treatment, respectively. Cell survival was dependent on IL concentration. IL-4 and IL-13 also had antiapoptotic effects on SNP-treated human synovial explants. Effects of IL-4 and IL-13 varied in the presence of phosphatidylinositol-3 kinase and protein kinase C inhibitors, implying the involvement of these pathways in antiapoptotic signaling. Antiapoptotic effects were dramatically inhibited by LY294002, and partially by the protein kinase C inhibitor Gö 6976, while insulin-like growth factor increased synoviocyte survival. The possibility that IL-4 and IL-13 may enhance synovial expansion in vivo by their antiapoptotic effects is discussed.

Potential of modulatory cytokines in the rheumatoid arthritis process.

Rheumatoid arthritis is a chronic systemic disorder of unknown etiology. It is now generally accepted that the proinflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor-alpha are key mediators in the pathology of rheumatoid arthritis. Controlling the production and the activity of these mediators represents a major therapeutic goal. First data from clinical trials that showed efficacy, however, also revealed that blockade of these cytokines did not fully control the arthritis in all patients. Recent discoveries of novel cytokines in the pathology of arthritis such as IL-17, IL-18 and RANK ligand (RANKL) will help us better understand the pathogenesis of chronic arthritis and may contribute to improvement of current therapies. IL-4 and IL-10 are pleiotropic cytokines and are considered promising modulators in the control of rheumatoid arthritis.

An IFN-gamma-independent proinflammatory role of IL-18 in murine streptococcal cell wall arthritis.

IL-18 is a member of the IL-1 family of proteins that exerts proinflammatory effects. It was formally known as IFN-gamma-inducing factor and is a pivotal cytokine for the development of Th1 responses. Apart from Th1 immune-stimulatory activity, IL-18 induces the production of proinflammatory cytokines such as TNF-alpha and IL-1 in vitro. The goal was to investigate the role of endogenous IL-18 in murine streptococcal cell wall (SCW)-induced arthritis. Furthermore, we investigated whether IL-18 neutralization had an impact on local TNF and IL-1 production. C57BL/6, BALB/c, and IFN-gamma-deficient mice were injected with 2 mg of rabbit anti-murine IL-18 Abs shortly before induction of arthritis by intra-articular injection of 25 microg of SCW fragments into the right knee joint. Suppression of joint swelling was noted on days 1 and 2 of SCW arthritis after blockade of endogenous IL-18. Analysis of local cytokine concentrations showed that IL-18, TNF-alpha, and IL-1ss levels were decreased. Severe inhibition of chondrocyte proteoglycan synthesis was seen in the vehicle-treated control animals, whereas a reversal of the inhibition of chondrocyte proteoglycan synthesis was found in the anti-IL-18-exposed animals. Blockade of endogenous IL-18 in IFN-gamma-deficient mice showed results similar to those found in wild-type animals, identifying a role for IL-18 that is IFN-gamma independent. The present study indicates that IL-18 is a proinflammatory cytokine during the onset of murine SCW arthritis, and this inflammatory role of IL-18 is IFN-gamma independent.

IL-4 gene therapy for collagen arthritis suppresses synovial IL-17 and osteoprotegerin ligand and prevents bone erosion.

Bone destruction is the most difficult target in the treatment of rheumatoid arthritis (RA). Here, we report that local overexpression of IL-4, introduced by a recombinant human type 5 adenovirus vector (Ad5E1mIL-4) prevents joint damage and bone erosion in the knees of mice with collagen arthritis (CIA). No difference was noted in the course of CIA in the injected knee joints between Ad5E1mIL-4 and the control vector, but radiographic analysis revealed impressive reduction of joint erosion and more compact bone structure in the Ad5E1mIL-4 group. Although severe inflammation persisted in treated mice, Ad5E1mIL-4 prevented bone erosion and diminished tartrate-resistant acid phosphatase (TRAP) activity, indicating that local IL-4 inhibits the formation of osteoclast-like cells. Messenger RNA levels of IL-17, IL-12, and cathepsin K in the synovial tissue were suppressed, as were IL-6 and IL-12 protein production. Osteoprotegerin ligand (OPGL) expression was markedly suppressed by local IL-4, but no loss of OPG expression was noted with Ad5E1mIL-4 treatment. Finally, in in vitro studies, bone samples of patients with arthritis revealed consistent suppression by IL-4 of type I collagen breakdown. IL-4 also enhanced synthesis of type I procollagen, suggesting that it promoted tissue repair. These findings may have significant implications for the prevention of bone erosion in arthritis.

Reduction of interleukin-17-induced inhibition of chondrocyte proteoglycan synthesis in intact murine articular cartilage by interleukin-4.

OBJECTIVE: To investigate the role of interleukin-4 (IL-4) and IL-10 in basal and IL-1- and IL-17-mediated inhibition of chondrocyte metabolism. METHODS: Cartilage explants of patellae from naive mice were incubated with IL-17 and/or IL-1 alone or were pretreated with IL-4 and IL-10. In addition, knee joints of naive mice were injected intraarticularly with IL-4 and IL-10 alone or were coinjected with IL-1. Chondrocyte proteoglycan (PG) synthesis was measured in intact murine articular cartilage. Levels of nitric oxide (NO) were measured using the Griess reagent. RESULTS: IL-17, a novel cytokine secreted by CD4+ activated memory T cells, inhibited chondrocyte PG synthesis in intact murine articular cartilage, although the suppressive effect was less potent than that of IL-1. The suppressive effect of IL-17 was completely abolished in the presence of L-NIO (L-NS-[1-iminoethyl]ornithine), an inhibitor of NO metabolism, and IL-17 only slightly induced inhibition of PG synthesis in cartilage explants of patellae from iNOS (inducible NO synthase) knockout mice. This indicates that the suppressive effect of IL-17 was mediated by NO. Pretreatment with IL-4, but not IL-10, significantly reduced the inhibition of chondrocyte PG synthesis induced by IL-1 or IL-17. The IL-4-induced reduction in the inhibitory effects of IL-1 and IL-17 on chondrocyte PG synthesis was accompanied by decreased NO formation in the culture supernatants. CONCLUSION: IL-17 plays a role in the inhibition of chondrocyte PG synthesis. IL-4 and IL-10 have no effect on basal chondrocyte metabolism. However, IL-4-pretreated cartilage is less sensitive to the suppressive effect of IL-1 as well as IL-17. This suggests that IL-4 is protective in T cell-driven cartilage disturbances, probably through reduction of iNOS.

Intra-articular IL-10 gene transfer regulates the expression of collagen-induced arthritis (CIA) in the knee and ipsilateral paw.

We studied the effects of local IL-10 application, introduced by a recombinant human type 5 adenovirus vector, in the mouse knee joint during the early phase of CIA. One intra-articular injection with the IL-10-expressing virus (Ad5E1mIL-10) caused substantial over-expression of IL-10 in the mouse knee joint, using virus dosages which did not induce distracting inflammation. High expression of IL-10 was noted for a few days, being maximal at day 1. One intra-articular injection of Ad5E1mIL-10 in the knee joints of collagen type II (CII)-immunized mice, before onset of CIA was noted, reduced the incidence of collagen arthritis in that knee. Of high interest, the protective effect of local IL-10 expression by Ad5E1mIL-10 was not restricted to the knee joint alone. The arthritis incidence in the ipsilateral paw was highly suppressed. In contrast, local IL-10 over-expression was not effective when treatment was started after onset of CIA. Further analysis in the acute streptococcal cell wall-induced arthritis model revealed that local IL-10 over-expression markedly suppressed the production of tumour necrosis factor-alpha (TNF-alpha) and IL-1alpha, but had no significant effect on IL-1beta and IL-12 production in the inflamed synovium. These data indicate that local over-expression of IL-10 in the knee joint of mice regulates the expression of collagen arthritis, probably through down-regulation of TNF-alpha.