Flare-up of experimental arthritis in mice with murine recombinant IL-1

An inflammation-inducible adenoviral expression system for local treatment of the arthritic joint

To achieve a disease-regulated transgene expression for physiologically responsive gene therapy of arthritis, a hybrid promoter was constructed. The human IL-1 beta enhancer region (-3690 to -2720) upstream of the human IL-6 promoter region (-163 to +12) was essential in mounting a robust response in HIG-82 synovial fibroblasts and in RAW 264,7 macrophages. A replication-deficient adenovirus was engineered with luciferase (Luc) controlled by the IL-1/IL-6 promoter (Ad5.IL-1/IL-6-Luc). LPS caused a 23- and 4.6-fold induction of Luc. activity in RAW cells infected with Ad5.IL-1/IL-6-Luc or the conventional Ad5.CMV-Luc construct, respectively. Next, adenoviruses (10(6) ffu) were injected into the knees of C57Bl/6 mice. An intra-articular injection of zymosan, 3 days after Ad5.IL-1/IL-6-Luc, increased Luc. activity by 39-fold but had no effect in the Ad5.CMV-Luc joints. The constitutive CMV promoter was rapidly silenced and could not be reactivated in vivo. In contrast, the IL-1/IL-6 promoter could be reactivated by Streptococcal cell wall (SCW)-induced arthritis up to 21 days after infection. Next the IL-1/IL-6 promoter was compared to the C3-Tat/HIV-LTR two-component system in wild-type, IL-6(-/-) and IL-1(-/-) gene knockout mice. Both systems responded well to LPS-, zymosan- and SCW-induced arthritis. However, the basal activity of the IL-1/IL-6 promoter was lower and IL-6 independent. This study showed that the IL-1/IL-6 promoter is feasible to achieve disease-regulated transgene expression for treatment of arthritis.

Mediators of inflammation are down-regulated while apoptosis is up-regulated in rheumatoid arthritis synovial tissue by polymerized collagen

The aim of the study was to determine whether collagen-polyvinylpyrrolidone (collagen-PVP) modifies some proinflammatory responses in synovium cultures from rheumatoid arthritis (RA) patients. Synovium from 10 RA patients were cultured with or without 1% collagen-PVP. Tissues on the 3rd, 5th and 7th culture day were sectioned and stained by the Herovici technique. Total collagen and type I/III collagen ratios were evaluated by the Woessner micromethod and by interrupted gel electrophoresis, respectively. Collagenolytic activity was assessed by degradation of [3H]-collagen in supernatants. TIMP-1, IL-1beta and TNF-alpha were determined in supernatants by ELISA, and the results were normalized by DNA concentration. IL-1beta, TNF-alpha, IL-6, IL-8, MMP-1, TIMP-1, Cox-1, VCAM-1, ICAM-1 and Fas/APO95 expression was evaluated by immunohistochemistry. Apoptosis was detected by TUNEL technique. The histological analysis and electrophoresis revealed a 1.7-fold increase of type III collagen in a time-dependent fashion in collagen-PVP-treated cultures. Proinflammatory cytokines (IL-1beta: 58 +/- 9 versus 22 +/- 10; TNF-alpha: 41 +/- 6 versus 11 +/- 3; IL-8: 59 +/- 12 versus 29 +/- 9; treated versus untreated), adhesion molecule (ICAM-1: 57 +/- 11 versus 29 +/- 15; VCAM-1: 49 +/- 7 versus 21 +/- 13; treated versus untreated) as well as Cox-1 (59 +/- 10 versus 20 +/- 3) expression was down-regulated in RA synovium treated. Meanwhile, TIMP-1 (36 +/- 7 versus 57 +/- 11) and Fas expression (20 +/- 10 versus 55 +/- 13) and apoptosis (14 +/- 3 versus 55 +/- 5) were up-regulated in treated cultures compared with controls. In supernatants, the collagenolytic activity, as well as IL-1beta and TNF-alpha, levels were all down-regulated in treated cultures (two, three, fourfold, respectively). The addition of collagen-PVP to synovium-induced down-modulation of some inflammatory parameters and an increase in apoptosis of synovial cells. Perhaps this mechanism could contribute to inhibit outgrowth of pannus formation and to down-regulate inflammation of joints in patients with RA.

Systemic macrophage activation in locally-induced experimental arthritis

Local and systemic macrophage activation was examined during the course of monoarticular murine antigen-induced arthritis (AIA), induced by systemic immunization and subsequent local induction. The levels of tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, IL-12p70, and nitric oxide (NO) were determined in joints, sera, and supernatants of peritoneal macrophages (the latter unstimulated or stimulated ex vivo with LPS/IFN-gamma). In comparison with normal mice, systemic immunization (day 0) was associated to significant rise of TNF-alpha in serum, IL-1beta in the joints, IL-6 in unstimulated macrophages and IL-12p70 in stimulated macrophages. Local induction led to a further significant increase of: (i) TNF-alpha, IL-1beta, and IL-6 in the joints; and (ii) IL-1beta, and IL-6 in sera and stimulated macrophages during acute and/or early chronic AIA (days 1 to 7). Unstimulated macrophages showed increased NO release (day 3), while stimulated macrophages significantly increased secretion of IL-12p70 (day 1). In late chronic AIA (day 21), cytokine/NO expression returned to immunization levels or below at all sites; solely IL-1beta in the joints remained significantly above normal levels. Therefore, the prevalently local AIA model is characterized by a mixture of local and systemic activation of the mononuclear phagocyte system (MPS). While systemic MPS activation preceding arthritis induction can be attributed to systemic immunization, further systemic activation during arthritis appears an integral pathogenetic component of AIA.

Role of tumour necrosis factor alpha in experimental arthritis: separate activity of interleukin 1beta in chronicity and cartilage destruction

Chronic arthritis is characterised by persistent joint inflammation and concomitant joint destruction. Using murine arthritis models and neutralising antibodies as well as cytokine specific knockout conditions, it was found that tumour necrosis factor alpha (TNFalpha) is important in early joint swelling. Membrane bound TNFalpha is sufficient to drive this aspect of inflammation as well as the acute cellular infiltrate in the synovial tissue. Interleukin 1 (IL1) is not necessarily a dominant cytokine in early joint swelling, but has a pivotal role in sustained cellular infiltration and erosive cartilage damage. TNFalpha independent IL1 production is a prominent feature in murine arthritis models. These observations provide evidence for potential uncoupling of joint inflammation and erosive changes, implying that both cytokines need to be targeted to achieve optimal treatment.

Increased vulnerability of postarthritic cartilage to a second arthritic insult: accelerated MMP activity in a flare up of arthritis

OBJECTIVE

Murine antigen induced arthritis (AIA) is a chronic, smouldering inflammation. Flares of arthritis can be induced by antigen rechallenge or exposure to inflammatory mediators like interleukin 1 (IL1). These flares are characterised by a fast and marked proteoglycan (PG) depletion if compared with the initial arthritis. This study investigated the involvement of metalloproteinases in both the initial and the flare phase of arthritis.

METHODS

Murine AIA was induced and a flare up of arthritis was induced by injection of 10 ng of IL1beta. Messenger RNA levels of MMP-1 and -3 were studied by RT-PCR. MMP activity in cartilage, during both primary AIA as well as the flare up of arthritis, was studied by immunodetection of MMP specific neoepitopes in aggrecan (VDIPEN). Cartilage just before flare induction was analysed for presence of MMPs at the mRNA level as well as at the protein level by zymography.

RESULTS

At the onset of AIA, a fast upregulation of mRNA for stromelysin and collagenase was noted. However, no VDIPEN epitopes were detected during this early phase of arthritis. They appeared when PG depletion was severe at day 7 of arthritis and disappeared when cartilage was repaired. IL1 injection into a knee joint at week 4 of AIA caused a flare up of arthritis, coinciding with a fast and marked PG degradation. This degradation was characterised by accelerated expression of VDIPEN epitopes if compared with the expression in primary AIA. Analysis of cartilage at week 4 of AIA showed still increased mRNA levels of MMP-1 and -3. Moreover, increased levels of latent MMPs were present as well, as APMA activation induced profound VDIPEN epitope. In vitro exposure to IL1 did show increased PG breakdown but no VDIPEN expression, suggesting that factors in addition to IL1 are needed to cause the in vivo VDIPEN expression.

CONCLUSIONS

The fast and marked PG depletion seen in a flare up of AIA coincides with accelarated expression of MMP induced neoepitopes compared with expression during primary AIA. This accelerated expression is probably linked to increased levels of latent enzyme, which were found to be present in the cartilage before induction of a flare up.

Role of interleukin 1 in antigen-induced exacerbations of murine arthritis

The mechanism underlying the chronic and intermittent course of rheumatoid arthritis is not elucidated. In the present study, the role of interleukin 1 (IL-1) was investigated in exacerbations of antigen-induced arthritis in mice. A flare-up of smoldering inflammation (weeks 3 to 4 of antigen-induced arthritis) was inducible by injection of a small amount of methylated bovine serum albumin into the hypersensitive knee joint. Immunohistochemistry showed IL-1 expression in the synovial lining layer and in focal areas of the inflamed synovium during the flare-up. IL-1 was also measured in 1-hour culture supernatant of synovial tissue taken during the flare-up by a bioassay. The expression of both immunoreactive and bioactive IL-1 in the hypersensitive joint peaked around 6 hours after antigen (2 micrograms of methylated bovine serum albumin) injection and declined thereafter. Antigen rechallenge induced an acute joint swelling of the arthritic joint but not in the naive joint of the sensitized mouse, yet synovia of both joints produced IL-1 after antigen injection. Remarkably, a single intravenous injection of rabbit anti-IL-1 alpha and -beta antibodies 1 hour before antigen rechallenge neutralized IL-1 in the joint. Anti-IL-1 treatment significantly reduced the antigen-induced joint swelling (30 to 40%) but did not affect the profound influx of polymorphonuclear cells in the onset of the exacerbation. However, a profound relief of the inflammation (synovitis) was obtained by IL-1 blockade on day 4 of the exacerbation. Chondrocyte proteoglycan synthesis was markedly suppressed in the antigen-challenged naive knee joints suggesting that this was a direct IL-1 effect as the inflammation was insignificant. Anti-IL-1 treatment was able to maintain chondrocyte proteoglycan synthesis in the antigen-rechallenged joint, which was highly suppressed in the control group. Furthermore, the enhanced proteoglycan breakdown in the antigen-rechallenged joints was significantly decreased in the anti-IL-1 group. We concluded that IL-1 is an important mediator in exacerbations of murine arthritis, and amelioration of cartilage pathology was obtained with anti-IL-1 antibody treatment.

Role of IL-2 and IL-4 in exacerbations of murine antigen-induced arthritis

In this study the roles of different T-cell subsets, and produced cytokines, were investigated in an animal model for acute exacerbations. Flare-up reactions are inducible in the chronic phase of a smouldering antigen-induced inflammation by injection of a small amount of an antigen into a hyper-reactive knee joint. In vivo treatment with anti-CD4 monoclonal antibodies (mAb) almost totally blocked the flare reaction, whereas anti-CD8 treatment did not exert any effect. The role of T-helper 1 (Th1) cells in delayed-type hypersensitivity-resembling diseases is generally entitled proinflammatory, whereas Th2 cells act in an anti-inflammatory manner. To investigate the role of these T-cell subsets in flare-up reactions, anti-interleukin-2 (IL-2) and anti-IL-4 mAb treatments were performed. Anti-IL-2 treatment partly blocked the flare reaction, and anti-IL-4 treatment, although the result was unexpected, blocked the flare more efficiently. Furthermore, when human recombinant IL-2 (hrIL-2) and murine recombinant IL-4 (mrIL-4) were co-injected with the antigen to test their ability respectively to potentiate or down-regulate the flare reaction, both cytokines demonstrated additional pro-inflammatory effects, although hrIL-2 was more potent than mrIL-4. The mere effect of hrIL-2 and mrIL-4 was studied by direct injection into a hyperreactive joint. No flare-up reaction or cell-influx could be induced, suggesting that other mediators are needed to exert pro-inflammatory effects of IL-2 or IL-4. We conclude that not only Th1 cells, but also Th2 lymphocytes (at least regarding IL-4 production) may play a pro-inflammatory role in flare-up reactions of chronic arthritis. Considering therapeutic application of Th2 cell-derived cytokines, one should be aware of the possible pro-inflammatory potential of IL-4.

Interleukin-1 beta enhances capsaicin-induced neurogenic vasodilatation in the rat skin

1. This study examined the effect of interleukin-1 beta (IL-1 beta) on the capsaicin-induced increase in cutaneous blood flow of anaesthetized rats as measured by laser Doppler flowmetry. 2. The substances were administered by intraplantar subcutaneous injection of 10 microliters-volumes, saline being injected into one hindpaw and IL-1 beta into the other. 3. IL-1 beta (0.5-500 pg) was without effect on blood flow on its own but dose-dependently enhanced the hyperaemic response to intraplantar capsaicin (0.3 microgram) up to 180% (P < 0.05) of the response seen in saline-treated paws. 4. Il-1 beta-(163-171), a fragment devoid of proinflammatory activity, failed to enhance capsaicin-induced hyperaemia when given at a dose of 50 pg. 5. Indomethacin (10 mg kg-1, i.p.) did not alter the capsaicin-induced vasodilatation but prevented IL-1 beta (50 pg) from augmenting the hyperaemic response to capsaicin. 6. The hyperaemia evoked by intraplantar calcitonin gene-related peptide (0.038-3.8 ng) was not altered by IL-1 beta (50 pg). 7. These data indicate that IL-1 beta enhances the cutaneous hyperaemic response to afferent nerve stimulation with capsaicin in a prostaglandin-dependent manner. This proinflammatory action of the cytokine appears to arise from sensitization of afferent nerve endings.

Amelioration of established murine collagen-induced arthritis with anti-IL-1 treatment

Inflammatory cytokines have been implicated in the pathogenesis of rheumatoid arthritis. To validate a key role for IL-1 in arthritic processes we have studied the protective effect of neutralizing antimurine IL-1 antibodies in the murine collagen-induced arthritis (CIA) model. Combination of anti-IL-1 alpha and anti-IL-1 beta given before onset of arthritis was shown to prevent disease completely. Remarkably, a single treatment was also highly effective in the established phase of arthritis, reducing both inflammation as well as cartilage destruction. Suppression was most pronounced with the combination, but anti-IL-1 beta alone also induced significant relief. Finally, we studied the protective effect of IL-1 neutralization on cartilage metabolism in a unilateral expression model of collagen arthritis. To this end zymosan was injected in one knee joint before onset of disease, resulting in accelerated expression in that particular joint and the draining paw. Anti-IL-1 treatment started after accelerated expression of arthritis was able to fully normalize chondrocyte synthetic function, which was highly suppressed in the control group. It is concluded that IL-1 is an important determinant in both inflammation and cartilage destruction in collagen arthritis, and this may have implications for therapy in human arthritis.

Cationic immune complex arthritis in mice--a new model. Synergistic effect of complement and interleukin-1

A novel cationic immune-complex-mediated arthritis (ICA) model was developed in mice. The highly cationic protein lysozyme was coupled to poly-L-lysine (PLL) and injected intra-articularly into the knee joint of the mouse, shortly after systemic administration of specific antibodies. A vehement joint inflammation developed, characterized by severe joint swelling and the influx of predominantly polymorphonuclear (PMN) leukocyte. Unique properties were combined in this protein. First, an excellent retention of the antigen in joint structures was found, facilitating sufficient IC formation in the synovial tissue and at the cartilage surface. Secondly, PLL.lysozyme appeared to be a potent inducer of interleukin-1 (IL-1). Similar IL-1 production was measured at 6 hours, in both immune or nonimmune mice. Neutralization with antibodies against either IL-1 alpha or IL-1 beta revealed that IL-1 alpha was the dominant cytokine. Resident cells were responsible for this IL-1 production since a comparable IL-1 signal was measured after intra-articular injection of PLL.lys in neutropenic mice. We further investigated whether IL-1 and complement factors were involved in the onset of this ICA. Neutralizing the IL-1 production with antibodies directed against IL-1 alpha and beta showed a significant decrease in joint swelling. Complement depletion by cobra venom factor also prevented the onset of arthritis for the greater part. Only a minor swelling remained at 6 hours after eliciting arthritis, which was similar to the swelling after injecting the antigen alone and probably reflects IL-1 mediated inflammation. In this study, the authors show a synergistic action of IL-1 and complement in the onset of cationic ICA. Unique properties of the antigen such as excellent retention and its ability to induce IL-1 are combined within one molecule and make this antigen arthritogenic in the presence of antibodies and complement activation.