Pharmacological studies of antigen-induced arthritis in BALB/c mice. I. Characterization of the arthritis and the effects of steroidal and non-steroidal anti-inflammatory agents

Evaluating the effect of ursodeoxycholic acid (UDCA) in comparison with dexamethasone and diclofenac in a rat model of rheumatoid arthritis

Ursodeoxycholic acid (UDCA) is known for its major effects on the liver, but its impact on autoimmune diseases is not well understood. This study aimed to assess the effectiveness of UDCA in controlling rheumatoid arthritis (RA) in an in vivo setting. Experimental RA was induced in rats using Freund's complete adjuvant, and the effects of UDCA (50,100 mg/kg) were compared to those of dexamethasone and diclofenac by measuring changes in paw size, IL-17, pro-inflammatory cytokines, oxidative stress (GSH, MDA), and radiological changes. The administration of UDCA resulted in decreased cartilage damage, reduced paw edema, and a decrease in the release of pro-inflammatory cytokines and oxidative stress. Additionally, X-ray joint alterations were observed in the UDCA-treated group compared to the dexamethasone and diclofenac groups. These results suggest that UDCA has anti-rheumatoid arthritis properties due to its ability to minimize oxidative stress and inflammation in arthritis-affected rats.

Melastoma malabathricum Linn attenuates complete freund's adjuvant-induced chronic inflammation in Wistar rats via inflammation response

BACKGROUND

Natural products use for arthritis treatment is gaining importance in the medical worldt. Various studies reports medical importance of Melastoma malabathricum Linn. (MM) (Melastomataceae), also known as "putki," has a broad range of health benefits, for its free radical scavenging constituents. The current investigation scrutinizes the antioxidant and anti-inflammatory effect of MM against adjuvant-induced arthritis in experimental rats.

METHODS

High-performance thin layer chromatography (HPTLC) was used for estimation of phytochemical-constituents present in the MM extract. Protective effect of MM extract in Wistar rats was estimated using CFA-induced model. The rats were divided into different groups with six rats in each group. All animals received oral administration of MM and indomethacin for 28 days. The body weight and arthritic score were scrutinized at regular intervals. At the end of experimental protocol, the rats were sacrificed, and blood samples were used for antioxidant, hematological parameters, pro-inflammatory and inflammatory mediator, respectively. Histopathological observation was used to evaluate the protective effect of MM extract.

RESULT & DISCUSSION

Current study confirmed the preventive effect of MM against adjuvant-induced paw edema, paw redness and arthritic progression. MM significantly (P < 0.001) modulated the oxidative stress parameters as well as hematological parameter induced by CFA. The result also altered the distorted level of proinflammatory mediators and inflammatory mediator, which further reinforce the implication of MM in CFA induced arthritis. Histological analyses of joints of rats showed a reduction in the synovial hyperplasia and mononuclear infiltration in the MM treated group which provides evidence for the antiarthritic effect of MM.

CONCLUSION

From above parameters our study states that the MM is capable of restraining the alteration produced via adjuvant-induced arthritis in aminals. The repressing effect of MM could be attributed, at least in part, to antioxidant, hematological and anti-inflammatory effect. Figure Caption: Melastoma Malabathricum Linn Attenuates Complete Freund's Adjuvant-Induced Chronic Inflammation in Wistar rats by Inflammation Response.

Bridging autoantibodies and arthritis: the role of Fc receptors

Autoantibodies represent a hallmark of Rheumatoid arthritis (RA), which is a chronic inflammatory autoimmune disease characterized by inflammation and damage in the joints. Anti-Citrullinated Protein Antibodies (ACPA) are the most prominent autoantibodies present in RA patients. These autoantibodies have been intensively investigated during the last 20 years due to their diagnostic and predictive value. Furthermore, they are believed to be involved in mediating the damage associated with RA. Antibodies of the IgG isotype interact with the immune system via Fcγ receptors expressed on immune cells as well as nonimmune cells. These receptors, therefore, form the bridge between Fcγ receptor-positive cells and antibodies complexed to antigen allowing the modulation and activation of cellular immune responses that are involved in immune defense against invading microorganisms. However, in case triggered by antibodies against self-antigens, they can also play a pivotal role in the induction and perpetuation of autoimmune diseases such as RA. Mouse models have been indispensably important for understanding the role of Fcγ receptors in the development of arthritis. Here we discuss the contribution of autoantibodies to the pathogenesis of arthritis in preclinical animal models, as well as RA, in relation to their interaction with the different (immune inhibitory and activating) Fcγ receptors.

Do non-steroidal anti-inflammatory drugs influence chronic inflammation? The effects of piroxicam on chronic antigen-induced arthritis in rats

OBJECTIVE

The effects of non-steroidal anti-inflammatory drugs (NSAIDs) on acute inflammation have been thoroughly investigated. NSAIDs are, however, also prescribed for patients with chronic inflammation, such as rheumatoid arthritis (RA), and objective improvement suggestive of anti-inflammatory action from NSAIDs has not been convincingly shown in chronic RA. An antigen-induced arthritis (AIA) model was used to investigate the effects of piroxicam on chronic inflammation.

METHODS

AIA was induced by injecting methylated bovine serum albumin (mBSA) into the knee joints of previously immunized rats that were treated orally with the NSAID piroxicam or with saline. This treatment was started either before AIA was induced or after it had reached a chronic phase. The findings were recorded by clinical and histological assessment of the joints.

RESULTS

The piroxicam group developed significantly less acute and subsequent chronic knee joint inflammation but this was only evident if the drug was administered prior to the intra-articular mBSA injections. Piroxicam treatment that was initiated during the chronic inflammation did not have any clinical effect, whereas short-term corticosteroid treatment abolished the chronic inflammation. Moreover, histological analysis of the chronic inflammation revealed significantly more inflammatory changes in the piroxicam group compared with the control group.

CONCLUSIONS

Piroxicam treatment had no beneficial effects on the chronic stable inflammation in this model and might even delay histological resolution. As the anti-inflammatory effect of piroxicam is restricted to acute inflammation, the use of NSAIDs during periods of chronic stable arthritis in humans, such as in RA, may need to be investigated.

Enhancement by dexamethasone of the therapeutic benefits of cisplatin via regulation of tumor angiogenesis and cell cycle kinetics in a murine tumor paradigm

We have investigated in the current study, the possible modulatory effects of dexamethasone on cisplatin cytotoxicity in Ehrlich ascites carcinoma (EAC)-bearing female Swiss albino mice. Cisplatin (3.5mg/kg) was injected IP for 3 consecutive days in mice previously inoculated SC with EAC cells in the right flank. Dexamethasone (2.5mg/kg) was administered SC alone or 24h ahead of cisplatin challenge, and these regimens were given for 3 consecutive days. Dexamethasone enhanced the anti-tumor effects of cisplatin, clearly demonstrated by the increased mean tumor growth time (TGT) and tumor growth delay time (TGDT) values compared to cisplatin alone. The effects of dexamethasone on tumor angiogenesis and cell cycle distribution of EAC cells have been addressed as possible mechanisms, whereby the glucocorticoid could probably augment cisplatin cell-kill. Indeed, dexamethasone enhanced the angiostatic activity of cisplatin by 52.5%. The glucocorticoid also synchronized the EAC cells in the G2/M phase, secondary to its regulatory role on the transcriptional and translational activity in these cells, thus, exposing them to the dramatic cytotoxic potential of cisplatin. One could conclude that dexamethasone enhanced the anti-tumor effects of cisplatin via augmenting its angiostatic activity and modulating cell cycle kinetics. Also, dexamethasone did not alter cisplatin-induced nephrotoxicity, thus demonstrating an improved therapeutic potential.

Mineralocorticoid receptor mediates glucocorticoid treatment effects in the autoimmune mouse ear

The standard treatment for many hearing disorders is glucocorticoid therapy, although the cochlear mechanisms involved in steroid-responsive hearing loss are poorly understood. Cochlear dysfunction in autoimmune mice has recently been shown to be controlled with the mineralocorticoid aldosterone as effectively as with the glucocorticoid prednisolone. Because aldosterone regulates sodium, potassium, and other electrolyte homeostasis, this implied the restoration of hearing with the mineralocorticoid was due to its impact on cochlear ion transport, particularly in the stria vascularis. This also suggested glucocorticoids may be controlling hearing recovery in part through their binding to the mineralocorticoid receptor in addition to their glucocorticoid receptor-mediated anti-inflammatory and immunosuppressive functions. Therefore, the aim of the present study was to better delineate the role of the mineralocorticoid receptor in steroid control of hearing in the autoimmune mouse. Spironolactone, a mineralocorticoid receptor antagonist, was administered to MRL/MpJ-Fas(lpr) autoimmune mice in combination with either aldosterone or prednisolone to compare their hearing and systemic disease with mice that received either steroid alone. ABR thresholds showed either aldosterone or prednisolone alone preserved hearing in the mice, but spironolactone prevented both steroids from maintaining normal cochlear function. This suggested both steroids are preserving hearing through the mineralocorticoid receptor within the ear to regulate endolymph homeostasis. The spironolactone treatment did not block normal glucocorticoid receptor-mediated immune-suppression functions because mice receiving prednisolone, either with or without spironolactone, maintained normal body weights, hematocrits, and serum immune complexes. Thus, reducing systemic autoimmune disease was not sufficient to control hearing if mineralocorticoid receptor-mediated functions were blocked. It was concluded the inner ear mineralocorticoid receptor is a significant target of glucocorticoids and a factor that should be considered in therapeutic treatments for steroid-responsive hearing loss.

Correlation of tumor phenotype with c-fms proto-oncogene expression in an in vivo intraperitoneal model for experimental human breast cancer metastasis

Although proto-oncogene expression has been shown to correlate with clinical outcome in breast carcinoma, an experimental model has not been proposed to study this phenomenon in vivo. In addition, the ability to modulate this proto-oncogene in vivo to correlate with phenotypic behavior has not been determined. Utilizing an intraperitoneal model for metastatic spread with BT20 human breast carcinoma cells, clonally expanded cells expressing five fold higher c-fms protein were compared with parent BT20 cells as well as an underexpressing clone using intrasplenic injection following left flank cut-down in female nude and Severe combined immunodeficient (SCID) mice. Athymic BALB/c nude and SCID animals were observed for clinical evidence of tumorigenicity with necropsy performed at either 50 or 80 days unless compromised earlier. Immunohistochemistry (IHC) of the harvested tumors was performed to correlate c-fms expression from its original in vitro culture to the in vivo model. At day 50, differences in primary tumor take and spread to the pelvis were already evident favoring the c-fms over-expression group with IHC of these tumors revealing significantly higher intensity of staining for c-fms, (mean H score of 205 vs. 43 in the over-expression and parent groups, respectively). At day 80, tumor take and spread was comparable; however, tumor size in the over-expression group was significantly larger than the parent and under-expressing group in both the BALB/c and SCID experiments. Modulation of c-fms proto-oncogene expression was also achieved using the anti-glucocorticoid, RU-486, via oral administration to SCID mice with subsequent correlation to IHC staining. This model thus provides tumors of significant size and organ diversity which retain their phenotype early in tumorigenesis allowing an early endpoint to assess efficacy of novel treatments.

Anti-inflammatory activity of Seabuckthorn (Hippophae rhamnoides) leaves

Immunomodulatory activity of Seabuckthorn (SBT) leaf extract was evaluated in adjuvant induced arthritis (AIA) rat model. Inflammation was induced by injecting Complete Freund's Adjuvant (CFA) in the right hind paw of rats. SBT extract was administered intraperitoneally to treat the inflammation. The extent of inflammation and treatment response was evaluated by clinical analysis, scintigraphic visualization using technitium-99m-glutathione (Tc99m-GSH) and lymphocyte proliferation. Serial evaluation was carried out on days 1, 7, 14, 21 and 28 after creation of inflammation. The Tc99m-GSH uptake in the inflamed leg was compared with the normal contralateral leg of the same animal. The measurements were done by obtaining scintigraphic images using gamma camera and an online computer. Both qualitative and quantitative evaluation of radiotracer accumulation was considered to evaluate the anti-inflammatory response. The lymphocyte proliferation study revealed cellular immunosuppression during the early phase of the disease. Administration of SBT extract on the same day or 5 days prior to inflammatory insult into the joint, significantly reduced the inflammation as compared to the untreated animals in a dose dependent manner. These observations suggest that the SBT leaf extract has a significant anti-inflammatory activity and has the potential for the treatment of arthritis.

The modulation of intra-articular inflammation, cartilage matrix and bone loss in mono-articular arthritis induced by heat-killed Myobacterium tuberculosis

Inflammation models for the assessment of anti-rheumatic drug activity utilize a variety of stimuli and sites. However, the determination of cartilage and bone degradation remains time consuming and problematic. A rapid rat model of Mycobacterium tuberculosis monoarticular arthritis with induces of inflammation, as well as patellar cartilage proteoglycan and bone degradation has been reported. This study characterizes this model with respect to the actions of anti-rheumatic drugs. Dexamethasone, cyclosporin and prednisolone inhibited all three parameters. Methotrexate inhibited joint inflammation alone, whilst azathioprine was without effect. Levamisole inhibited cartilage and bone degradation without affecting joint inflammation. NSAIDs were divided in their actions. Naproxen, piroxicam, diclofenac and tiaprofenic acid all inhibited joint inflammation and bone loss, but naproxen and piroxicam both significantly potentiated cartilage proteoglycan loss. This model appears to rely on cellular recruitment at this early stage, the anti-metabolites being ineffective. The modulation of inflammation can result in a protection against cartilage and bone damage in arthritis; however, certain NSAIDs are detrimental to cartilage integrity. The pharmacological manipulation of inflammatory arthritis can therefore dislocate inflammation from its effects on tissue destruction.

Correlation between accelerated presbycusis and decreased immune functions

The aim of the current study is to analyze the relationship between presbycusis and the immune system, which is affected by pathogenic environments, and to devise a strategy for the prevention of presbycusis using the SAMP1 mouse, an animal model for accelerated senescence that shows both immunological dysfunction and hearing loss caused by the impairment of spiral ganglion cells in the cochlea. When these mice were bred in different pathogenic environments, we found that the development of age-related diseases such as presbycusis was delayed in the mice bred under clean conditions. Prednisolone administration showed no significant prevention of the development of presbycusis in the mice, suggesting that autoimmune mechanisms are not involved in the acceleration of presbycusis. It is conceivable that pathogen-induced infections impose a severe stress on the host, impairing the host's immune functions. A reduction in the number of pathogens may therefore prevent the acceleration of the aging process. These findings suggest that not only the gene backgrounds but also immune functions affect the development of presbycusis in SAMP1 mice. Further studies into the relationship between systemic immune functions and the neuro-generation system may provide additional information about the treatment for age-related diseases.

Aldosterone and prednisolone control of cochlear function in MRL/MpJ-Fas(lpr) autoimmune mice

Recently this laboratory showed aldosterone, a mineralocorticoid that only enhances sodium transport, was as effective as the glucocorticoid prednisolone in restoring cochlear function in autoimmune mice. To further test this relationship between sodium transport and autoimmune hearing loss, dosage comparisons were made of prednisolone and aldosterone control of the auditory dysfunction in autoimmune MRL/MpJ-Fas(lpr) mice. Mice were tested at 2 months of age to establish baseline auditory brainstem response (ABR) thresholds, hematocrit, serum immune complexes, and anti-nuclear antibodies. Mice were then given different doses of prednisolone or aldosterone in their drinking water for 2 months. After the treatment period, most untreated water controls showed elevation of ABR thresholds due to the ongoing autoimmune disease. However, the steroid groups had significantly more mice with improved or unchanged thresholds. Both steroids improved stria vascularis morphology, although aldosterone appeared to be more effective. The immune suppressive prednisolone caused a dose-related improvement in levels of serum immune complexes and hematocrit, hallmarks of systemic autoimmune disease. Aldosterone, which has no immune suppressive function, did not alter systemic disease. The comparable efficacy of prednisolone and aldosterone in restoring auditory function suggests steroid reversal of autoimmune hearing loss in mice is due to increasing stria vascularis sodium transport and not suppression of systemic autoimmune reactions.

Steroid treatment in young MRL.MpJ-Fas(lpr) autoimmune mice prevents cochlear dysfunction

Corticosteroid therapy reverses clinical autoimmune sensorineural hearing loss, although little is known of how steroids restore normal auditory function. If suppression of systemic autoimmune processes underlies hearing restoration, then preventing autoimmune symptoms from developing should prevent cochlear dysfunction. MRL. MpJ-Fas(lpr) autoimmune mice were used to test this potential mechanism by initiating oral prednisolone treatment at 6 weeks of age, prior to autoimmune disease and hearing loss onset. The steroid treatment group was given prednisolone in their drinking water, while untreated controls were given tap water. Treatment continued for 7 months with periodic evaluations of cochlear function with auditory brainstem response (ABR) audiometry. Autoimmune mice given the steroid lived longer and did not develop levels of serum immune complexes seen in their untreated controls. Also, their ABR thresholds remained near normal throughout the 7 months of treatment, while untreated controls showed progressive threshold elevations typical for autoimmune disease. This correlation of suppressed systemic autoimmune activity and maintenance of normal cochlear function identifies one potential mechanism for autoimmune hearing loss and hearing restoration with steroid therapy. The autoimmune mouse should serve as a valuable model for future studies of the cochlear mechanisms responsive to steroid treatment in autoimmune hearing loss.

Steroid treatment improves cochlear function in the MRL.MpJ-Fas(lpr) autoimmune mouse

Corticosteroid therapy is used to reverse autoimmune sensorineural hearing loss, although little is known of the mechanism by which this occurs. This has been due to the lack of a suitable animal model with spontaneous hearing loss that is steroid responsive. The present study examined the effects of prednisolone treatment on auditory thresholds in the MRL.MpJ-Fas(lpr) autoimmune mouse to determine its suitability as such a model. Autoimmune mice at 3.5-4. 5 months of age were evaluated by pure-tone auditory brainstem response (ABR) to establish threshold elevations due to the disease. The steroid treatment group was then given prednisolone in their drinking water for 2.5 months, while untreated controls were given tap water. Significantly more steroid treated mice survived to the time of post-treatment ABR evaluation. Half of the steroid treated ears demonstrated either improvement or no change in cochlear function compared to only 25% in the untreated controls. Overall, cochlear thresholds in the untreated controls increased by 14.7 dB, whereas no significant threshold increase was seen in the steroid treated group (4.3 dB) over the treatment period. No qualitative anatomical differences were seen in the ears of those mice surviving to the end of the study. These findings establish the autoimmune mouse as a model for studies of steroid responsive mechanisms within the ear. This could apply to autoimmune sensorineural hearing loss, as well as any hearing disorder for which steroid therapy is recommended.

Animal models of arthritis: relevance to human disease

Animal models of arthritis are used to evaluate potential antiarthritis drugs for clinical use. Therefore capacity of the model to predict efficacy in human disease is one of the most important criteria in model selection. Animal models of rheumatoid arthritis (RA) with a proven track record of predictability include rat adjuvant arthritis, rat type II collagen arthritis, mouse type II collagen arthritis, and antigen-induced arthritis in several species. Agents currently in clinical use (or trials) that are active in these models include corticosteroids, methotrexate, nonsteroidal anti-inflammatory drugs, cyclosporin A, leflunomide, interleukin-1 receptor antagonist, and soluble tumor necrosis factor receptors. For some of these agents, the models also predict that toxicities seen at higher doses for prolonged periods would preclude dosing in humans at levels that might provide disease-modifying effects. Animal models of osteoarthritis (OA) include mouse and guinea pig spontaneous OA, meniscectomy and ligament transection in guinea pigs, meniscectomy in rabbits, and meniscectomy and cruciate transection in dogs. None of these models have a proven track record of predictability in human disease because there are no agents that have been proven to provide anything other than symptomatic relief in human OA. Efficacy data and features of the various models of RA and OA are discussed with emphasis on their proven relevance to human disease.

Anti-inflammatory/antiarthritic ketonic bisphosphonic acid esters

Bisphosphonate ester 2 is an inhibitor of inflammation, but is devoid of antiarthritic effects. SAR studies on a series of related bisphosphonate esters resulted in compounds 6e, 6i, 6j, and 6m, which exhibited excellent inhibition of an arthritis model, in addition to potent anti-inflammatory effects.

Application of computer-based histomorphometry to the quantitative analysis of methylprednisolone-treated adjuvant arthritis in rats

Analyses of paw edema and histomorphometry were performed on tibio-talar joints to determine arthritic pathological responses in untreated 28-day adjuvant-induced polyarthritis (AIP) rats, and to determine the drug effect on inhibiting these responses in AIP rats treated with methylprednisolone. Histomorphometric measurements were performed on regions including articular joint space, synovial tissue, articular and epiphyseal cartilage, epiphyseal and metaphyseal bone marrow, and endosteal and periosteal cortical bone surfaces. Analysis of paw edema indicated that paw volume was significantly increased in untreated AIP rats. This increase in paw volume was partially prevented in AIP rats treated with 0.3 mg methylprednisolone/kg per day, and completely prevented in AIP rats treated with the two higher dose levels (1 and 3 mg/kg per day). Histomorphometric analysis of untreated AIP tibio-talar joints showed decreased articular joint space whereas synovial tissue area increased and a minor, but significant, articular cartilage erosion area occurred. Epiphyseal growth cartilage area was decreased. Trabecular bone area in distal tibial epiphyseal and metaphyseal regions was markedly decreased whereas bone marrow area increased involving a large number of macrophages and osteoclasts. Eroded endocortical bone area was increased while cortical bone area decreased. Marked osteophyte proliferation occurred on the periosteal surface. These arthritic pathological changes were inhibited by the treatment of methylprednisolone in a dose-dependent fashion. The animals treated with the highest dose of methylprednisolone complete prevented the development of the AIP-induced pathological changes. These data confirmed qualitative histological evaluation of arthritic changes but did not correlate with the anti-edema effects of methylprednisolone (100% inhibition at 1.0 and 3.0 mg/kg, p.o.). It is suggested that quantitative histomorphometry be used to determine more precisely the AIP rat model and the effects of drugs on different histopathological features in this experimental model of arthritis in preference to paw edema which gives a more limited picture of the arthritic response.

The effect of an interleukin-1 receptor antagonist protein on type II collagen-induced arthritis and antigen-induced arthritis in mice

OBJECTIVE

To investigate the anti-arthritic effect of recombinant human interleukin-1 receptor antagonist protein (IRAP) in two experimental models of arthritis.

METHODS

Recombinant IRAP was administered daily to mice with type II collagen-induced arthritis (CIA) or with antigen-induced arthritis (AIA) provoked by methylated bovine serum albumin (mBSA). Disease incidence and severity were assessed by a clinical index and histologic features. Serum antibody to type II collagen, spleen cell proliferation to mBSA, and anti-IRAP antibodies were measured as indices of immune function.

RESULTS

IRAP reduced the incidence and delayed the onset of CIA and suppressed the antibody response to type II collagen. In contrast, IRAP did not affect the pathogenesis of AIA and had no effect on either humoral or cellular immune responses to mBSA in arthritic mice.

CONCLUSION

These observations suggest that interleukin-1 may play a prominent role in the development of some, but not all, forms of arthritis.

Characterisation and pharmacological sensitivity of antigen arthritis induced by methylated bovine serum albumin in the rat

The optimum conditions for the induction of antigen-induced arthritis in the rat have been studied. Two immunisations with methylated bovine serum albumin (mBSA) (0.5 mg) in Freund's complete adjuvant (FCA) containing 0.375 mg Mycobacterium tuberculosis followed by an intra-articular injection of mBSA (0.5 mg) led to the production of a chronic, erosive arthritis. The development of the arthritis was associated with the appearance of T lymphocytes and other inflammatory cells in the synovium. Male and female animals were equally susceptible to the disease. Prednisolone, indomethacin and methotrexate inhibited the development of the arthritis but ibuprofen and D-penicillamine were without any significant effect.

The effects of flurbiprofen on the passive transfer of adjuvant-induced arthritis

The effect of flurbiprofen on the passive transfer of adjuvant-induced arthritis was studied to determine if flurbiprofen acted in the donor and/or recipient arms of this model. Groups of donor and recipient rats were treated with either placebo or flurbiprofen 4 mg/kg. Joint scores were markedly decreased in recipient rats treated with flurbiprofen irrespective of the whether donor animals were treated with placebo or flurbiprofen (p less than 0.01). There was also a moderate decrease in the ability of donor cells from rats treated with flurbiprofen to suppress the severity of arthritis (p less than 0.01); however, this effect was less marked than that seen in recipient animals. These data imply that flurbiprofen may act at multiple sites in adjuvant-induced arthritis, but the major site of action of flurbiprofen in this model is in the recipient animals.

In vivo evidence for a key role of IL-1 in cartilage destruction in experimental arthritis

Cartilage destruction in murine antigen induced arthritis is characterized by enhanced degradation of proteoglycans and inhibition of chondrocyte proteoglycan synthesis. Within this model common NSAIDs only suppress joint swelling, and to some extent granulocyte infiltration, but leave the process of cartilage destruction undisturbed. Evidence is now accumulating that the vast amount of activated granulocytes in the joint space are of minor importance, and that interleukin-1 (IL-1) is the key mediator in this process. Treatment of mice with neutralizing antibodies against IL-1 resulted in relief of chondrocyte proteoglycan synthesis inhibition and prevented matrix destruction. This indicates that it makes sense to focus future therapy on elimination of IL-1.

Induction of an acute erosive monarticular arthritis in mice by interleukin-1 and methylated bovine serum albumin

We examined the effect of interleukin-1 (IL-1) administration on a mild and transient inflammatory response in the knees of mice injected intraarticularly with methylated bovine serum albumin (mBSA). Injection of mBSA on day 0 into nonsensitized mice caused a weak inflammatory response confined to the infrapatellar fat pads and involved infiltration by mononuclear cells, neutrophils, and eosinophils. The response developed between days 4 and 7 and resolved by day 28. No erosion of cartilage or subchondral bone was seen. In contrast, mBSA-treated mice injected with recombinant human IL-1 beta subcutaneously in the ipsilateral footpad on days 0-3 developed a severe monarticular arthritis in the antigen-injected knee. Pannus developed, extending over the articular surfaces, and extensive erosion of cartilage and subchondral bone occurred. Multinucleated giant cells, together with fibrin-like material, were observed at sites of active bone erosion and debris, and large numbers of neutrophils were seen in the joint space. These pathologic features represent a new arthritis model in which IL-1 profoundly augments a weak inflammatory response and induces acute erosive joint destruction, supporting the hypothesis that IL-1 is an important cytokine in the pathogenesis of arthritis.

The effects of sensitization protocols on arthritic responses in antigen-induced arthritis

Three different immunization protocols were studied for their effect on methylated bovine serum albumin (mBSA)-induced arthritis. Mice were immunized with mBSA in Freund's incomplete adjuvant containing dextran and challenged 3 weeks later with antigen in one knee. After 7-14 days a strong inflammatory reaction developed without significant erosions of articular cartilage or bone. The reaction resolved between 28 and 35 days. In contrast, mice immunized with mBSA and complete Freund's adjuvant (CFA) developed inflammation that was accompanied by erosive disease. However, this pathology also resolved after 28-35 days. Mice immunized with mBSA in modified CFA developed inflammation and co-incident erosive disease that persisted for 60 days. Thus, three distinct arthropathies can be evoked depending on the immunization protocol employed.

Effects of NSAIDs on the metabolism of sulphated glycosaminoglycans in healthy and (post) arthritic murine articular cartilage

Several non-steroidal anti-inflammatory drugs (NSAIDs) were studied for their effects on normal and damaged murine articular cartilage, both in vitro and in vivo. In vitro, in the absence of serum, sodium salicylate caused significant suppression of 35S-glycosaminoglycan (GAG) synthesis, whereas tiaprofenic acid, piroxicam, prednisolone sodium phosphate and several other NSAIDs were without effect. Trypsin-mediated proteoglycan depletion did not change the susceptibility of the articular chondrocyte to these drugs. Similarly, no enhancement of drug effect was seen when arthritic cartilage was taken from an acutely inflamed joint, and prenisolone sodium phosphate even seemed to diminish inflammation-mediated suppression of 35S-GAG synthesis. The short term in vivo effects of some of the drugs were tested in mice with unilateral zymosan-induced arthritis. At day 1 after arthritis induction, in vivo 35S-GAG synthesis by the cartilage of the arthritic joint was decreased to 63%. Only sodium salicylate suppressed in vivo 35S-GAG synthesis in the healthy and arthritic joint to the same extent in both. At day 28, GAG synthesis in the postarthritic joint was enhanced to 160%. This type of cartilage appeared to be more susceptible to drug effects, since all drugs tested showed clear suppression of the augmented GAG production in vivo. Finally, in vivo drug effects were tested on normal and enhanced 35S-GAG degradation, the latter in the zymosan-induced arthritic joint. Both tiaprofenic acid and prednisolone sodium phosphate appeared to suppress degradation in healthy and, to some extent, in arthritic cartilage.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of nonsteroidal antiinflammatory drugs on cartilage destruction in antigen induced arthritis in mice

The nonsteroidal antiinflammatory drugs, salicylate, piroxicam and tiaprofenic acid, and the steroid prednisolone were investigated in a long-term study for their potential detrimental or beneficial effects on joint cartilage in mice with antigen induced monoarthritis. Daily drug treatment over a period of 4-7.5 weeks did not affect the histological characteristics of normal joints at all. Articular chondrocyte synthetic activity was even stimulated after salicylate and tiaprofenic acid treatment, but the significance of this finding is not yet clear. Cartilage damage, caused by inflammation in the knee joint, was neither markedly deteriorated nor attenuated by these drugs. Minor antiinflammatory properties as measured by decrease in edema using 99mTc-uptake and in the change of inflammatory cells were only evident with prednisolone, piroxicam and salicylate.

Pharmacological studies of antigen-induced arthritis in BALB/c mice. II. The effects of second-line antirheumatic drugs and cytotoxic agents on the histopathological changes

The effects of treatment with second-line antirheumatic drugs and cytotoxic agents on the severity of experimental monoarticular arthritis in BALB/c mice have been investigated. The arthritis was assessed histologically in terms of synovitis and erosions of cartilage and bone. Azathioprine (20 mg/kg) and sulphasalazine (10-30 mg/kg oral; 30-100 mg/kg i.p.) produced significant suppression of synovitis and erosions when administered daily for 4 weeks commencing 2 weeks after induction of the arthritis. Dapsone (1-10 mg/kg) and to a lesser extent methotrexate (2 mg/kg) produced some suppression of erosive disease when administered daily for 4 weeks commencing 2 weeks after induction of the arthritis but this failed to reach statistical significance. Chloroquine, D-penicillamine and sodium aurothiomalate all failed to have any effect on the disease with any of the treatment schedules used. Auranofin had no effect on the disease when treatment commenced 2 weeks after intra-articular injection but produced variable suppression at high doses when administered from the day of intra-articular injection.