Autoimmunity to collagen in adjuvant arthritis of rats

Curculigoside exerts significant anti‑arthritic effects in vivo and in vitro via regulation of the JAK/STAT/NF‑κB signaling pathway

The present study aimed to investigate the anti-arthritic effects of curculigoside isolated from the rhizome of Curculigo orchioides Gaertn in vivo and in vitro, as well as to determine the potential underlying mechanisms. A rat model of arthritis was induced with type II collagen. Arthritic rats were treated with curculigoside (50 mg/kg) and blood samples were collected to determine serum levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-10, IL-12 and IL-17A. Furthermore, indices of the thymus and spleen were determined. The anti-proliferative effects of curculigoside were detected with Cell Counting kit-8 assays in rheumatoid arthritis-derived fibroblast-like synoviocyte MH7A cells. In addition, expression levels of Janus kinase (JAK)1, JAK3, signal transducer and activator of transcription (STAT)3, nuclear factor (NF)-κB p65 and its inhibitor (IκB) were determined by western blotting. The results revealed that curculigoside inhibited paw swelling and arthritis scores in type II collagen-induced arthritic (CIA) rats. Additionally, curculigoside decreased serum levels of TNF-α, IL-1β, IL-6, IL-10, IL-12 and IL-17A in CIA rats. Curculigoside also significantly inhibited MH7A cell proliferation in a time and concentration-dependent manner. Furthermore, treatment downregulated the expression of JAK1, JAK3 and STAT3, and upregulated cytosolic nuclear factor (NF)-κB p65 and IκB. In conclusion, the results of the present study indicated that curculigoside exhibited significant anti-arthritic effects in vivo and in vitro, and the molecular mechanism may be associated with the JAK/STAT/NF-κB signaling pathway.

Matrine Exerts a Strong Anti-Arthritic Effect on Type II Collagen-Induced Arthritis in Rats by Inhibiting Inflammatory Responses

To investigate anti-arthritic effects of matrine isolated from the roots of S. flavescens on type II collagen-induced arthritis (CIA) in rats and to explore its related potential mechanisms, CIA rats were established and administered with matrine (20, 40 or 80 mg/kg/days, for 30 days). Subsequently, blood was collected to determine serum levels of TNF-α, IL-1β, IL-6, IL-8, IL-17A, IL-10, MMP-2, MMP-3 and MMP-9, and hind paws and knee joints were collected for histopathological examination. Furthermore, indices of the thymus and spleen were determined, and synovial tissues were collected to determine the protein expressions of p-IκB, IκB, Cox-2 and iNOS. Our results indicated that matrine significantly suppressed inflammatory reactions and synovial tissue destruction. Matrine inhibited paw swelling, arthritis indices and weight loss in CIA rats. Additionally, matrine decreased the levels of TNF-α, IL-1β, IL-6, IL-8, IL-17A, MMP-2, MMP-3 and MMP-9. Matrine also down-regulated expressions of p-IκB, Cox-2, and iNOS but up-regulated IκB in synovial tissues in CIA rats. The results suggested matrine possesses an anti-arthritic effect in CIA rats via inhibiting the release of pro-inflammatory cytokines and proteins that promote the NF-κB pathway.

Regulation of synoviocyte activity by resveratrol in rats with adjuvant arthritis

The aim of this study was to investigate the preventive effects of resveratrol (Res) on rats with adjuvant arthritis (AA) and the mechanism(s) of action. An AA model was established by injection of Freund’s complete adjuvant (FCA). Vascular endothelial growth factor (VEGF) was visualized in joint specimens using immunohistochemistry. IL-1β and TNF-α production in synoviocytes was determined by radioimmunoassay (RIA). The mRNA expression of IL-1β and TNF-α was observed in synoviocytes using the reverse transcription (RT)-PCR method. The synoviocytes of the AA model were stimulated by Res or treated with the protein kinase C (PKC) inhibitor chelerythrine prior to stimulation. The expression of phosphorylated ERK1/2 (p-ERK1/2) was detected by western blotting. Res was able to reduce the elevated levels of IL-1β and TNF-α, and inhibit the mRNA expression of IL-1β and TNF-α in the synoviocytes of the AA model rats. VEGF expression in the Res-treated group was significantly lowered. The protein expression levels of p-ERK1/2 were significantly higher in the Res-treated group compared with those of the model group, while p-ERK1/2 was markedly lower in the group pretreated with chelerythrine. Res has a therapeutic effect on AA rats, which may be correlated with its immunoregulatory actions, and may activate p-ERK1/2 in synoviocytes via PKC.

Analgesic effect of electroacupuncture on inflammatory pain in collagen-induced arthritis rats: mediation by alpha2- and beta-adrenoceptors

This study was designed to investigate whether alpha- and beta-adrenergic systems mediate the analgesic effect of electroacupucture (EA) on inflammatory pain in a rat model of collagen-induced arthritis (CIA). To induce CIA, male Sprague-Dawley rats were immunized with bovine type II collagen emulsified in Freund's incomplete adjuvant, followed by a booster injection 14 days later. After induction of arthritis, the inflammatory pain threshold by the tail flick latency decreased as time passed and reached the minimum value at 4th week. Four weeks after the first immunization, low-frequency EA stimulation (2 Hz, 0.07 mA, 0.3 ms) delivered to Zusanli (ST(36)) for 30 min showed the analgesic effect. And also, the analgesic effect of EA was blocked by pretreatment with yohimbine (alpha2-adrenoceptor antagonist, 2 mg/kg, i.p.), but not by pretreatment with prazosin (alpha1-adrenoceptor antagonist, 1 mg/kg, i.p.) and propranolol (non-selective beta-adrenoceptor antagonist, 10 mg/kg, i.p.). These results suggest that the low-frequency EA can relieve the inflammatory pain in CIA, and the analgesic effect of EA can be mediated by alpha2- and beta-adrenoceptor, but not by alpha1-adrenoceptor.

Selective cyclooxygenase-2 inhibitor prevents reduction of trabecular bone mass in collagen-induced arthritic mice in association with suppression of RANKL/OPG ratio and IL-6 mRNA expression in synovial tissues but not in bone marrow cells

We performed this study to clarify whether celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, prevents trabecular bone mass reduction by suppressing arthritis-related increase of bone resorption, and to discriminate differences in actions on bone among celecoxib, SC-58560 (a selective COX-1 inhibitor), and indomethacin. Eight-week-old DBA/1J male mice were divided into six groups as follows. Control untreated (Normal) and collagen-induced arthritic (CIA) mice were compared with four treatment groups: celecoxib was orally administered to CIA mice at doses of 0 (Vehicle), 16 (COX2L), and 75 (COX2H) mg/kg, in addition to two groups of mice treated with SC-58560 (COX1) or indomethacin (IND). Histomorphometry showed a significant decrease in tibial trabecular bone volume in arthritic mice, which was corrected by COX2H. The increased osteoclast surface and number in the Vehicle group were suppressed by COX2L, COX2H, and IND. The decreased bone formation rate in Vehicle was elevated by COX2H without statistical significance. A high ratio of mRNA expression of receptor activator of NF-kappaB ligand (RANKL)/osteoprotegerin (OPG) in Vehicle synovial tissue was suppressed by COX2L and COX2H. The increased expression of interleukin (IL)-6 mRNA in Vehicle was suppressed by COX2L, COX2H, and IND, although no difference in this expression was observed in bone marrow cells among all groups. In conclusion, in CIA mice, celecoxib suppresses arthritis-related increase in bone resorption at low and high doses and prevents trabecular bone mass reduction at high doses in association with suppression of osteoclast development in bone marrow through inhibition of RANKL/OPG ratio and IL-6 mRNA expression in inflammatory synovial tissue.

Hypernociception elicited by tibio-tarsal joint flexion in mice: a novel experimental arthritis model for pharmacological screening

Mice have been used as animal model to study mechanisms underlying inflammatory and immune diseases. The present study describes a model of joint inflammation-induced hypernociception to discriminate pharmacological tests in mice. A polypropylene tip probe with a large area (4.15 mm2) applied on the plantar surface of the hind paw was used to produce a dorsal flexion of tibio-tarsal joint. Experiments were performed to demonstrate that the probe application did not provoke cutaneous nociception. The decrease in the withdrawal threshold of inflamed joint was used as nociceptive parameter. Administration of zymosan in the tibio-tarsal joint induced a dose and time-dependent hypernociception elicited by articular dorsal flexion movement. Maximal joint hypernociception was detected between 7 and 24 h after zymosan injection, and matched maximal inflammation score as determined by histopathology and neutrophil migration assay. In agreement with the inflammatory hypernociceptive paradigm, flexion-elicited hypernociception induced by zymosan was dose-dependently inhibited by morphine (2-8 mg/kg) and by an effective dose of indomethacin (5 mg/kg). The present study demonstrated that the tibio-tarsal flexion reflex is a behavioral nociceptive model that allows a quantitative evaluation of inflammatory joint hypernociception in mice and its pharmacological modulation.

Antinociceptive effect and the mechanism of bee venom acupuncture (Apipuncture) on inflammatory pain in the rat model of collagen-induced arthritis: Mediation by alpha2-Adrenoceptors

The antinociceptive effect and the mechanism of bee venom acupuncture (BVA) on inflammatory pain, especially in the rat model of collagen-induced arthritis (CIA), have not yet been fully studied. This study was designed to investigate the antinociceptive effect and its mu-opioid and alpha2-adrenergic mechanism of BVA in the CIA rat model. To induce CIA, male Sprague-Dawley rats were immunized with bovine type II collagen emulsified in Freund's incomplete adjuvant followed by a booster injection 14 days later. The antinociceptive effect was evaluated by tail flick latency (TFL). After induction of arthritis, the inflammatory pain threshold decreased as time passed, and there was no big change of the pain threshold after 3 weeks. Three weeks after the first immunization, BVA (0.25 mg/kg) injected into the Zusanli acupoint (ST36) showed the antinociceptive effect. Furthermore, the antinociceptive effect of BVA was blocked by yohimbine (alpha2-adrenergic receptor antagonist, 2 mg/kg, i.p) pretreatment, but not by naloxone (mu-opioid receptor antagonist, 2 mg/kg, i.p.) pretreatment. These results suggest that BVA can relieve inflammatory pain in CIA and the antinociceptive effect of BVA can be mediated by alpha2-adrenergic receptor.

Increase in GABAergic Cells and GABA Levels in the Spinal Cord in Unilateral Inflammation of the Hindlimb in the Rat

The effects of chronic peripheral inflammation on spinal cord gamma-aminobutyric acid (GABA) were examined in the rat. Following the injection of complete Freund's adjuvant in the left hindlimb footpad an increased number of immunoreactive cells occurred in ipsilateral laminae I - III of the dorsal horn from L3 to L5. GABA-immunoreactive cells were more numerous than contralaterally 1 week after the onset of the inflammation, reached maximal numbers after 3 - 4 weeks, and declined thereafter. Differences from control sides were statistically significant except at week 6. GABA levels in homogenates of the ipsilateral lumbar enlargement were increased significantly at 4 weeks. Since increases in GABA occurred in the spinal cord zone of projection of the nerves supplying the inflamed foot, the central response is surmised to result from the increased nociceptive input arriving from the periphery. However, the transmission from primary axons to GABA interneurons is not likely to be monosynaptic since profiles containing glutamate decarboxylase or GABA immunoreactivity are known to be predominantly presynaptic, and rarely postsynaptic, to primary afferent endings in electron micrographs in the rat. The findings support the function attributed to spinal GABA in modulating nociceptive input at segmental level.

Stage-dependent changes in trabecular bone turnover and osteogenic capacity of marrow cells during development of type II collagen-induced arthritis in mice

Rheumatoid arthritis (RA) is a disease characterized by inflammatory polyarthritis leading to destruction of the joints and reduction in bone mass. However, the relationship between bone mass and turnover is not yet clear in RA patients. To clarify the effect of bone turnover and marrow osteogenic capacity on mass and structure during the development of arthritis, we examined DBA1/J mice for 8 weeks after the first immunization with bovine type II collagen at the age of 9 weeks. Localized arthritis developed at 4 weeks and advanced arthritis at 6 weeks postimmunization. Urinary deoxypyridinoline levels in arthritic mice were significantly higher at 4 weeks, and levels were maintained thereafter. Their serum osteocalcin levels were significantly reduced compared with controls at 2 and 6 weeks, but did not differ significantly from those in the control group at 4 and 8 weeks. Three-dimensional (3D) trabecular bone volume of the proximal tibia measured by 3D microcomputed tomography (micro-CT) in the arthritic mice became significantly lower at 4 weeks and decreased further at 6 weeks compared with controls. Parameters of 3D trabecular bone structure, such as structure model index and trabecular bone pattern factor, were increased at 4 and 6 weeks, respectively. Trabecular osteoclast number increased and bone formation rates decreased at 8 weeks. The number of total bone marrow cells (BMCs), adherent stromal cells, and area of mineralized nodule formation in the tibia of arthritic mice were significantly reduced compared with controls at 6 weeks. Numbers of total fibroblastic colony-forming units (CFU-f) and alkaline phosphatase (ALP)-positive CFU-f colonies also decreased. However, the values of these osteogenic parameters corrected for the total BMCs and/or adherent stromal cells did not differ significantly between the arthritic and control groups. These data indicate that an increase in bone resorption led to the reduction in trabecular bone mass and deterioration of 3D structure during the localized arthritic stage. The reduction in bone marrow osteogenic potential in the advanced arthritic stage was due to the reduction in the number of total bone marrow cells, and differentiation of osteogenic cells was apparently unaffected. The reduction in bone formation may not be substantial in this arthritic model.

Suppression of collagen-induced arthritis by oral or nasal administration of type II collagen

We directly compared the effects of oral and nasal administration of collagen type II (CII) on disease progression, cytokine production and T cell responses in DBA/1 mice. Lymphocytes were assayed for proliferation and cytokine production and cell lines established. T cells from fed or nasally treated groups proliferated significantly less and produced markedly less IFN-gamma than the non-fed immunized group 10 days after immunization and prior to onset of arthritis. T cell lines established from fed or nasally treated mice showed a pattern of cytokine production involving IL-4, IL-10 and TGF-beta, whereas T cell lines from the control group produced more IFN-gamma and IL-2. Suppression of clinical measures of arthritis was equivalent in the nasal and orally treated groups. Animals were then tested for IFN-gamma production 70 days after a booster immunization at a time when disease was apparent. Mucosally treated animals secreted less IFN-gamma as compared to controls, even at this late time point. Suppression of collagen induced arthritis (CIA) by nasal treatment of mice with CII was associated with diminished levels of TNF-alpha and IL-6 mRNA expression in the joints of tolerized mice, two cytokines known to be involved in the inflammatory and pathological process of CIA. These results demonstrate the induction of antigen specific Th2 and TGF-beta secreting regulatory cells following both oral and nasal treatment, which is associated with suppression of local inflammation in the joints and decreased Th1 type responses in the periphery throughout the course of the illness.

Testicular-associated immune deviation and prevention of adjuvant-induced arthritis by three tolerization methods

A new tolerizing effect, testicular-associated immune deviation (TAID), was produced in rats by injecting antigen, emulsified with adjuvant, into the testicle. TAID abrogated the delayed hypersensitivity response to subsequent immunization. This study also assessed the effect of anterior chamber-associated immune deviation (ACAID), the aforementioned TAID and an equivalent tolerization method named alternative in vitro immune deviation (AVID), on adjuvant-induced arthritis (AIA). ACAID was produced by introducing antigen, emulsified with adjuvant, into the anterior chamber of the eye. AVID was achieved by exposing peritoneal exudate cells to antigen in the presence of fetal calf serum in vitro and then injecting the cells intraperitoneally. Antigen in adjuvant was administered intradermally to Dark Agouti rats, which are normally susceptible to AIA. One week after treatment with ACAID, TAID or AVID, the rats became resistant to AIA. The presence of neutralizing antibody to transforming growth factor-beta2 (TGF-beta2) in the culture abrogated the AVID effect. We concluded that introducing an antigen to the testicle induces immune deviation, and that prior introduction of the antigen to macrophages in an appropriate immune suppressive context, such as ACAID, TAID or AVID, prevents AIA.

Clinical and histological assessment of collagen-induced arthritis progression in the diabetes-resistant BB/Wor rat

Collagen-induced arthritis in the diabetes-resistant BB (DR BB)/Wor rat is a severe, aggressive disease initiated by immunization with heterologous native Type II collagen. Onset of clinical symptoms reproducibly occurs in 100% of animals between days 10 and 12 following collagen immunization. Hypertrophy of the synovial lining is the first histological manifestation of the early inflammatory arthritis. A mild inflammatory infiltrate in the synovium rapidly becomes a fibrovascular pannus eroding articular cartilage and subchondral bone. Beginning at the joint margins, an active synovitis is present. Light microscopy and immunohistochemical staining show the infiltrate to be comprised of mononuclear (lymphocytes, macrophages) and polymorphonuclear inflammatory cells. In addition, there is histological evidence for chronic inflammatory nodules and necrotizing vasculitis in connective tissue from diseased joints, both morphologic features associated with rheumatoid arthritis in humans. Subchondral bone erosion appears to be mediated largely by the resorptive action of activated osteoclasts. These histological parameters of disease progression in the DR BB/Wor rat are similar to human rheumatoid arthritis. The extensive degree of similarity in the pathology of DR BB/Wor rat collagen-induced arthritis and human rheumatoid arthritis supports the role of this model as an in vivo disease model for human rheumatoid arthritis.

The role of T cells in the regulation of B cell tolerance

The study of conventional models of B cell tolerance has suggested that self-tolerance is imposed on B cells at an early stage in their development due to a peculiar sensitivity of immature B cells to tolerance induction. While this concept accounts for some aspects of central B cell tolerance, it is inconsistent with recent reports of tolerance induction in mature splenic B cells from immunoglobulin transgenic mice. We present an alternative model, the hierarchical model (Aust. N. Z. J. Med. 25, 761-767, 1995), in which regulation of naive B cell reactivity is a function of antigen signal strength and availability of T cell help, but is independent of B cell maturation stage. In turn, the development of tolerance or memory in the T cell compartment is dependent on a combination of antigen-MHC recognition by T cells and antigen-nonspecific signalling by antigen-presenting cells. Using a transgenic model of T-B collaboration, we have shown that both immature and mature self-reactive B cells can be rescued and induced to secrete auto-antibody if the B cell determinant is linked to a carrier protein bearing a foreign T cell determinant.

Suppression of adjuvant arthritis in rats by oral administration of type II collagen in combination with type I interferon

The oral administration of 3 micrograms but not 300 micrograms of type II collagen (CII) significantly suppressed adjuvant arthritis in rats that was induced by immunization with Mycobacterium tuberculosis. Feeding 5000 units of type I interferon was also effective in downregulating the disease. More suppression of adjuvant arthritis was observed when both CII and interferon were orally given. Delayed-type hypersensitivity responses to M. tuberculosis were inhibited in interferon- but not in CII-fed animals. There were no delayed responses to CII in M. tuberculosis-immunized rats fed either CII or interferon. However, the delayed response to M. tuberculosis plus CII was significantly reduced by CII as well as interferon given orally. Feeding both CII and interferon was more effective in suppressing the delayed responses to M. tuberculosis plus CII. A similar suppression was observed in proliferative responses of lymph-node cells to M. tuberculosis, CII, or M. tuberculosis plus CII in-vitro. These results suggest that the suppression of adjuvant arthritis by oral administration of CII is due to tolerance to CII in which a bystander suppression mechanism appears to be involved. Orally administered interferon seems to suppress nonspecifically cellular immune responses. The oral administration of CII in combination with interferon may be a novel way to treat T cell-mediated diseases.

The effect of silicone-gel on the immune response

Silicone materials have been used in medical applications for at least 30 years. Despite this long history of use the question whether silicones can mediate an immunological reaction that may be detrimental to the host remains unanswered. Most studies on the biocompatability of silicones conclude that silicones are chemically stable compounds, which however are often capable of eliciting a benign chronic inflammatory response. Recently, our laboratory has conducted a series of animal experiments aimed at determining the immunological adjuvancy potential of silicone-gel taken from commercial breast implants. Our previous studies have indicated that silicone-gel is a potent humoral (antibody) adjuvant. Our present studies have found that silicone-gel is capable of eliciting auto-antibodies to rat thyroglobulin and bovine collagen II. However this immune response did not produce any histological evidence of thyroiditis or arthritis. Theories to explain why silicone-gel behaves as an adjuvant are discussed along with discussion of the hypothesis on the desirability of replacing silicone-gel with a more hydrophilic material in bioimplants.

Oral administration of type II collagen suppresses non-specifically induced chronic arthritis in rats

The present study was designed to investigate the efficacy of oral administration of type II collagen (CII) on non-specifically induced chronic arthritis in rats, induced by intra-articular injection of a mineral oil, squalene. When CII was fed before injection of squalene, no chronic arthritis developed. Feeding CII after the induction of arthritis was also effective in suppressing the progression of chronic joint inflammation. Lymph node cells from rats with squalene-induced arthritis failed to show proliferative responses to CII. In rats fed and primed with CII, there was a decrease in proliferative responses to CII. Arthritis induced by the mineral oil was markedly suppressed by the spleen cells from animals fed CII. These results indicate that non-specifically induced arthritis may be downregulated by the oral administration of CII and that the downregulation of joint inflammation may be due to the generation of CII-specific regulatory T cells that react to CII abundance in cartilage.

Meloxicam: a potent inhibitor of adjuvant arthritis in the Lewis rat

The effects of meloxicam, piroxicam, diclofenac and tenidap on the swelling of hind paws, radiologically-detectable bone and cartilage destruction of hind paws, increase in spleen weight, increase in erythrocyte sedimentation rate and changes in serum protein composition in male Lewis rats with adjuvant arthritis were studied following once-daily oral administration of these drugs for 21 days. All the drugs dose-dependently inhibited hind paw swelling. For equal activity against hind paw swelling caused by the secondary reaction, the required daily dose of piroxicam was about twice that of meloxicam; those of diclofenac and tenidap were about 3.5 and 60 times higher respectively. The bone and cartilage destruction induced by adjuvant arthritis were inhibited by meloxicam at low daily doses and by piroxicam at doses approximately four times those of meloxicam. Diclofenac and tenidap had only a weak effect on radiologically-detectable lesions when administered at doses sufficient to reduce paw swelling. Meloxicam also had a dose-dependent corrective effect on the systemic changes which occur in adjuvant arthritic rats, e.g. increase in spleen weight, increase in erythrocyte sedimentation rate and changes in serum protein composition. Piroxicam produced similar effects, at 3-4 times higher doses. Diclofenac and tenidap did not show comparable effects when administered at appropriate doses. These findings indicate that the action of meloxicam and piroxicam differs from that of diclofenac and tenidap in adjuvant arthritis in the Lewis rat. At oral doses which significantly reduce edema formation, only meloxicam and piroxicam showed a significant effect on systemic parameters of adjuvant disease in the Lewis rat.

Regulation of the immune response--lessons from transgenic models

Generation of the immune antigen receptor repertoire by means of semi-random recombination requires a mechanism for ensuring that self reactivity is constrained. A model is presented which accounts not only for the generation of self tolerance during ontogeny but also for regulation of tolerance and immunity in peripheral immune responses. The model proposes a hierarchy of immune regulation in which antigen presenting cells (APCs) determine the responses of T cells and T cells those of B cells. APCs respond to environmental triggers such as microbes, particulate antigen and tissue injury by becoming highly immunogenic for T cells. At other times, APCs can either be non-stimulatory or tolerogenic, depending on their environment. The model suggests that during ontogeny T and B cells mature in a tolerogenic environment in the thymus and bone marrow, thus ensuring that immunological tolerance results from early contact with self antigen.

Downregulation of silicone-induced chronic arthritis by gastric administration of type II collagen

We previously demonstrated that intra-articular injection of silicone in rats induced acute arthritis followed by chronic destructive joint inflammation in which T cells played a role. To investigate whether the model of T cell-mediated chronic silicone-induced arthritis (SIA) is modified by oral administration of type II collagen (CII), rats were fed CII either before or after intra-articular injection of silicone. We found that feeding CII either before or after intra-articular injection of silicone markedly suppressed the development of chronic arthritis. The early phase of acute joint inflammation was not affected by the oral antigen. There were no proliferative responses to CII of lymph node cells from rats with SIA. The proliferation to CII of lymph node cells from CII-primed rats was markedly suppressed by the addition of spleen cells from animals fed CII. Furthermore, the proliferative response to keyhole limpet hemocyanin (KLH) of KLH-sensitized lymph node cells was also suppressed by the addition of CII plus spleen cells from CII-fed animals. Injection of the spleen cells into rats followed by intra-articular injection of silicone inhibited the development of chronic SIA. These results indicate that T cell-mediated chronic arthritis may be downregulated by oral administration of CII and that the downregulation of joint inflammation may be due to the generation of CII-specific regulatory lymphocytes that react to CII abundant in cartilage.

Suppression of antigen-induced arthritis in Lewis rats by oral administration of type II collagen

OBJECTIVE

To assess the effect of orally administered type II collagen (CII) in antigen-induced arthritis (AIA).

METHODS

Arthritis was induced in Lewis rats by immunization with methylated bovine serum albumin (mBSA) in Freund's complete adjuvant, followed by an intraarticular injection of mBSA 2 weeks later. Different doses of CII, mBSA, and an unrelated control protein, keyhole limpet hemocyanin (KLH), were orally administered 5 times over several days prior to the induction of arthritis. Ankle joint swelling and delayed-type hypersensitivity (DTH) responses were measured.

RESULTS

Joint swelling was significantly reduced at a dose of 3 micrograms and 30 micrograms of CII, but not at 300 micrograms. The most prominent suppression of AIA was observed when rats were fed 10 mg of mBSA, whereas oral KLH had no effect. DTH responses were significantly reduced in the mBSA-fed rats, but not in rats that were fed CII or KLH.

CONCLUSION

Oral CII can suppress arthritis in an animal model in which immunity to collagen does not play a role. The effect is dose dependent and occurs at lower doses of CII. These results demonstrate the biologic relevance of bystander suppression associated with oral tolerance, and the potential use of this approach to treat human inflammatory joint disease.

Anti-type I collagen antibodies in advanced phases of adjuvant arthritis

The aim of this study was to elucidate the existence of autoantibodies directed to type I collagen as a response to connective tissue alterations that occur in inflammatory diseases. We have demonstrated the presence of antibodies to type I collagen during the time course of adjuvant arthritis, by means of the ELISA technique. These autoantibodies reached the highest levels in advanced phases of the arthritic process from 8 to 10 weeks after mycobacteria administration. The hind-paw swelling and the anti-type I collagen antibodies remained for at least 18 weeks post-induction.

Time course of antibodies against IgG and type II collagen in adjuvant arthritis. Role of mycobacteria administration in antibody production

The aim of this study was to elucidate, during the time course of adjuvant arthritis, the existence of antibodies directed to IgG (rheumatoid factor-like) and antibodies against type II collagen. In a second study, we also studied the relation between antibody production, arthritic process and mycobacteria administration. We have demonstrated the presence of antibodies to IgG and type II collagen by means of ELISA techniques. This reactivity appeared on day 7 post-induction, decreased later, and increased progressively from day 21 until last day studied (day 56 post-induction). We have also quantified antibodies against a soluble fraction of Mycobacterium butyricum, the inductor of the disease. Anti-mycobacteria antibodies appeared during the first seven days after induction, but from day 14, when systemic inflammation began, their levels suddenly increased. There is a positive correlation between anti-mycobacteria antibody levels and articular swelling. Anti-IgG and anti-collagen antibody production was not directly linked to arthritic process since these antibodies were synthesized when M. butyricum was administered intraperitoneally, which does not induce arthritis. Anti-mycobacteria antibody concentration was higher when arthritis induction by mycobacterial was successful than when it was unsuccessful.

Effect of pregnancy on proteoglycan-induced progressive polyarthritis in BALB/c mice: remission of disease activity

Proteoglycan-induced arthritis is a murine autoimmune model displaying many similarities to human rheumatoid arthritis and ankylosing spondylitis, as has been documented by clinical, immunological and histopathological studies. Since the onset of arthritis correlates with the serum antibody level to mouse cartilage proteoglycan (PG), it is believed that these autoreactive antibodies may play crucial roles in the pathological mechanisms of PG-induced arthritis. We have found that fertility in these PG-induced arthritic mice had been reduced but, unlike collagen-induced arthritis, had not been completely lost. Moreover, pregnancy had a beneficial effect upon the clinical symptoms with very little or no influence on serum antibody levels. Although fertility was retained and arthritic mothers delivered healthy offspring, the birth frequency was significantly less than in non-arthritic age-matched controls. Furthermore, the presence of anti-PG autoantibodies (predominantly IgG1 subclass) transmitted from arthritic mothers to infants transplacentally and by milk during the lactation period did not render these offspring either resistant or more sensitive to subsequent induction of arthritis. Subsequent immunization of infants with 'arthritogenic' PG revealed an unaltered susceptibility to arthritis induction.

Adjuvant arthritis pretreatment with type II collagen and Mycobacterium butyricum

A treatment previous to adjuvant arthritis induction has been performed with type II collagen (CII) or Mycobacterium butyricum (Mb), which is the inducer of the pathology. Pretreatment was administered in two different ways: a) subcutaneously or intradermally 14 days before arthritis induction, and b) intravenously 3 days before induction. In order to relate the change in inflammation to the corresponding antigen immune response, serum antibodies and delayed type hypersensitivity (DTH) against CII or Mb were studied. Pretreatment with s.c. CII 14 days before induction produced slight protection against arthritis and significantly delayed its onset; systemic inflammation showed good positive correlation with anti-CII antibodies. The CII administered i.v. 3 days before arthritic challenge did not significantly modify the inflammatory process. The use of i.d. subarthritogenic doses of Mb 14 days before induction protected a high percentage of the animals from the posterior arthritic challenge; this protection was accompanied by high anti-Mb antibody titers and DTH reaction. When Mb was given i.v. 3 days before induction, a partial protection of inflammation was observed; arthritis was milder and its onset was delayed. These changes were accompanied by reduced humoral and cellular response to Mb.

The effect of anti-adhesion molecule antibody on the development of collagen-induced arthritis

In order to study how inflammatory cells including autoimmune lymphocytes interact with each other to develop collagen-induced arthritis (CIA), we injected monoclonal antibodies against mouse LFA-1 and ICAM-1 into DBA/1 mice immunized with type II collagen (CII). Both antibodies suppressed the development of CIA. These antibodies showed no effect on anti-CII antibody response, although they both significantly suppressed DTH response. It was suggested that anti-adhesion molecule antibodies suppress CIA mainly through their effect on cell-mediated immunity, without affecting humoral immunity under the conditions used.

Autoimmunity in non-human primates: the role of major histocompatibility complex and T cells, and implications for therapy

Two autoimmune disease models were studied in rhesus monkeys: type II collagen-induced arthritis (CIA) and experimental allergic encephalomyelitis (EAE). Unrelated outbred animals were used in these studies. In both models disease resistant and susceptible individuals could be identified. Susceptibility correlated with in vitro cellular responsiveness to antigen in the CIA model. In both models resistant as well as susceptible individuals developed a humoral response to the inducing antigen. However, there is an indication that IgM antibodies play a crucial role in the induction of CIA. No clear association between major histocompatibility complex (MHC) type and disease incidence was found although a higher frequency of a certain DR type was observed in EAE susceptible monkeys. It is likely that both the antigen binding capacity of the MHC class II molecules and the T-cell repertoire play an important role in determining whether disease will develop or not.

Urinary N-acetyl-beta-D-glucosaminidase as a marker of renal injury in adjuvant arthritis

In the present study we have determined if renal damage occurs with adjuvant arthritis (AA). As a sensitive indicator of renal injury in tubular cells, urinary N-acetyl-beta-D-glucosaminidase (NAG) was measured at predetermined times after arthritis induction. Urinary protein, sodium and potassium excretion were also evaluated. NAG levels in arthritic animals were higher than those in healthy ones from day 12 after induction and the levels remained high during the study period. A significant positive correlation was noted between urinary NAG excretion and disease severity reflected by hind paw edema. Protein excretion also increased in arthritic animals but there was no correlation between urinary protein, NAG levels, and degree of inflammation. Changes in urine sodium and potassium levels did not reach statistical significance. Thus, we can conclude that some renal damage occurred in this experimental model of chronic inflammation.

T cell lines responding to Mycoplasma arthritidis and chondrocytes in the Mycoplasma arthritidis infection of rats

CD 4+ T cell lines responding specifically to Mycoplasma (M.) arthritidis were established from spleen and lymph nodes of a Lewis rat infected with M. arthritidis. The T cell response to M. arthritidis was MHC class II-restricted. M. arthritidis-reactive T cell lines also responded to syngeneic chondrocytes suggesting that M. arthritidis and chondrocytes may share a common antigenic structure. The T cell lines reacting with chondrocytes may play an important role in the chronic stage of the M. arthritidis-induced arthritis of rats by maintaining immune reactions initiated by M. arthritidis antigens and originally established to eliminate the mycoplasmas. These autoimmune reactions could perpetuate after disappearance of the mycoplasmas and possibly last for the entire lifetime.

Adjuvant-induced arthritis in rats. Evidence that autoimmunity to homologous collagens types I, II, IX and XI is not involved in the pathogenesis of arthritis

We examined the sera of arthritic outbred Wistar and Sprague-Dawley rats and inbred Fisher 344 and Wistar-Lewis rats for autoantibodies to rat type I, II, IX and XI collagens following the induction of arthritis with mycobacteria (MTB). Although many sera collected over an extended time were assayed in addition to acid eluates of arthritic joints, convincing evidence for autoimmunity to collagen could not be demonstrated. Instead, modest non-specific reactions were observed to collagen, irrelevant proteins, and buffer-treated plastic microtitre wells. In contrast, antibodies to purified protein derivative (PPD) were detected in the sera of rats developing adjuvant-induced arthritis, and antibodies to type II collagen, in the sera and joint eluate of rats developing experimental collagen-induced arthritis. Lastly, delayed-type hypersensitivity responses to collagen could not be detected, nor could adjuvant-induced arthritis be attenuated by soluble collagen injected intravenously before challenge with MTB. We conclude that adjuvant-induced arthritis and experimental collagen-induced arthritis are distinct models of rheumatic disease and that autoimmunity to collagen is neither prevalent in adjuvant-induced arthritis nor necessary for its pathogenesis.

Bisphosphonates in collagen arthritis

Bisphosphonates suppress bone destruction in various diseases. We studied the effects of 3-amino-hydroxypropylidene-1,1-bisphosphonate (APD), and dimethyl-APD in the collagen model of chronic arthritis in rats. The incidence and severity of arthritis was not lower in rats treated with APD or dimethyl-APD compared with controls. The cellular and humoral immune responses to collagen were also similar in the treated and untreated animals. In all animal groups the same bone destruction was found radiographically 42 days after immunization. This study demonstrates that bisphosphonates do not suppress the course of collagen arthritis in rats.

Collagen arthritis in the rat is initiated by CD4+ T cells and can be amplified by iron

The role of iron in arthritis was studied by administering ferric citrate (Fe-cit) to age-matched, female Sprague-Dawley rats immunized with chick type II collagen on Day 0. Rats received intravenously (iv) either Fe-cit (7.7 mg/kg body wt) or an identical concentration of sodium citrate on varying days after immunization. Transferrin saturation peaked (88-95%) 1 hr post-Fe-cit and returned to baseline values within 24 hr. Injection of Fe-cit on either Day 3 or Day 5, but not on Day 7 or Day 9, significantly (P less than 0.03) increased the incidence of arthritis. Synovium from the infrapatellar fat pad was harvested on Days 0-10 for analysis by immunocytochemistry. The inceptual morphologic change in the synovium following collagen immunization in rats not injected iv was an increase in the number of CD4+ and transferrin receptor+ mononuclear cells in perivascular regions; compared to Day 0 both cell types had increased two- to threefold by Day 3. On Day 7, an increase in CD8+ mononuclear cells occurred and the first polymorphonuclear leukocytes were noted. These alterations resulted in a peak in the CD4-CD8 ratio on Day 3, with a gradual decline thereafter. Although Fe-cit administration promoted the ingress of these mononuclear cells, it did not change the CD4-CD8 ratio significantly or recruit polymorphonuclear leukocytes into the joint tissue. Serum antibody titers to type II collagen, measured 20 days after immunization by an enzyme-linked immunosorbent assay, and delayed-type hypersensitivity to collagen, measured by a radiometric ear assay on Day 23, did not differ significantly between the groups. As well as showing that the initial intrasynovial event in collagen arthritis is perivascular infiltration by members of the CD4+ T cell subset displaying a phenotypic sign of activation, these findings demonstrate that iron administered at a critical time after immunization enhances the induction of collagen arthritis. The coincidence of this brief period of susceptibility with maximum CD4-CD8 ratios within the synovium and its occurrence prior to the stage of neutrophil infiltration are consistent with the possibility that the augmenting effect of iron is mediated by the inducer T cell subset.

Experimental synovitis induced by collagen-specific T cell lines

Type II collagen (CII) and ovalbumin (OV) reactive T cell lines were developed from the lymph node cells of Louvain rats previously immunized with the respective antigen. Histologic sections of rat knees injected intraarticularly (ia) with 10(6) cells from line CII (VA) or CII (VII) were graded blindly. Significant synovitis (P less than 0.000001 and 0.004, respectively) was evident compared to OV line recipients. Pannus developed within 48 hr, persisted for at least 4 to 6 weeks, was inducible with fewer than 10(3) CII cells, and required viable lymphocytes. The process was independent of anticollagen antibodies and was associated with the lines' capacity to elaborate a previously described 65-kDa CII-binding arthritogenic lymphokine. Line CII (VIII), which could not elicit a synovitis, did not produce detectable quantities of this factor. A line- and antigen-specific synovitis, comparable to the ia injection protocol, was also induced by intravenous administration of 2 x 10(7) CII (VA) cells and ia challenge with soluble collagen. These studies demonstrate that CII lines bearing the T helper phenotype can evoke a sustained synovitis and suggest that this experimental process is associated with the release of an arthritogenic lymphokine and not dependent on the formation of antibodies to CII.

Collagen arthritis in rats, arthritogenic lymphokines and other aspects

This review will mainly highlight data from selected, independent studies which collectively implicate a primary role for T cells in the pathogenesis of collagen arthritis in rats. Conferring insusceptibility to this experimental disease with the use of polyclonal, T cell specific antiserum provided direct initial evidence for this conclusion. Substantiation for the theory of a dominant T cell role in collagen arthritis was afforded by T cell line vaccination; scrutiny showed that the mechanism accounting for this protection was a specific down-regulation of the cellular response to collagen. Additional support came from experiments which showed that as few as 10(3) type II collagen specific T line cells were capable of provoking a sustained proliferative synovitis when instilled into the knee joint cavity of syngeneic naive rats. Further analysis of this phenomenon revealed that the arthritogenic capacity of various collagen-reactive line cells correlated with their ability to release a 65-Kd, collagen-binding lymphokine. This antigen-specific lymphokine was designated arthritogenic factor, based on an arthritogenic activity in the knee joint bioassay similar to that of the cells. A functional and physicochemically identical rat arthritogenic factor has also been identified in the adjuvant model of arthritis. These data support the premise that a major effector mechanism in experimental rat arthritis is the release of arthritogenic factor by expanded clones of autoreactive T cells; they also indicate that substantive efforts should be undertaken to seek to identify arthritogenic factor-like lymphokines in patients with chronic inflammatory synovial disease. As an equally plausible alternative hypothesis, the review will close with a brief discussion of recent findings supporting the possible involvement of cartilage-binding, complement-fixing anti-type II collagen antibodies in the pathogenesis of rheumatoid arthritis.

Experimental autoimmune arthritis in mice. II. Early events in the elicitation of the autoimmune phenomenon induced by homologous type II collagen

Intradermal injection of 100 micrograms of native homologous type II collagen (CII) into DBA/1-susceptible mice induced a progressive and chronic polyarthritis. This experimental autoimmune arthritis (EAA) closely mimicked the clinical evolution of human rheumatoid arthritis (RA) except for the sex linkage. Males were highly susceptible to EAA induction even when the amount of autoantigen injected was reduced to 25 micrograms. Conversely, females remained resistant to the disease even when a booster injection of 50 micrograms was administered. With regard to age, no major difference in the incidence was observed, although younger males developed a more severe arthritis than older ones. Anti-CII autoantibodies were detected in all immunized animals, regardless of the presence or absence of joint pathology. However, in arthritic mice, the onset of the disease was associated with a predominance of IgG2a autoantibodies. Kinetic studies revealed that females as well as males exhibited early histological lesions and detectable humoral responses toward mouse CII as of the second week postimmunization. Moreover, a specific cellular autoreactivity to homologous CII occurred in different lymphoid organs with a higher intensity in females than in males. Taken together, these findings suggest that homologous CII injection induces an early subclinical arthritis that develops progressively in all immunized mice, but would be down-regulated several weeks after priming, exclusively in females.

Polyarthritis and the air pouch reaction: dissimilarity of adjuvant and collagen models

The formation of an air pouch in the subcutaneous tissues of a rat previously inoculated intradermally with Freund's mycobacterial adjuvant for the induction of arthritis, provokes a marked but transient inflammatory reaction in the cavity lining of the pouch. The dependence of this reaction on arthritis development was investigated. It was found that rats inoculated with mycobacterial adjuvant by subcutaneous or intraperitoneal injection failed to produce either a pouch reaction or develop arthritis. Intradermal injections of carrageenan, mycobacteria (M. tuberculosis in saline), Freund's incomplete adjuvant alone or containing Salmonella typhimurium lipopolysaccharide and Bordetella pertussis organisms or mycobacterial adjuvant containing egg albumin were also ineffective. Intradermal injections of type II collagen in Freund's incomplete adjuvant did induce arthritis but no pouch reaction; however, this could be elicited after direct challenge with antigen. Pretreatment of rats intraperitoneally with saline suspensions of mycobacteria or a moderate dose of cyclophosphamide prevented both the pouch reaction and arthritis developing to intradermal mycobacterial adjuvant. Pretreatment of rats with mycobacteria was without effect on type II collagen-induced arthritis. From the results of this study it would appear that the air pouch reaction and arthritis induced by adjuvant are directly associated. The inability of collagen to induce a similar reaction demonstrates a fundamental dissimilarity with mycobacterial adjuvant in its mechanism of production of arthritis.

Attenuation of collagen arthritis and modulation of delayed-type hypersensitivity by type II collagen reactive T-cell lines

T-cell lines were established from the lymph node cells of syngeneic Louvain (LOU) rats previously immunized with native chick type II collagen (CII) emulsified in incomplete Freund's adjuvant. The CII lines proliferated in vitro to type II collagen but not to type I collagen, ovalbumin (OV), or PPD. Control lines, developed from LOU rats immunized with OV emulsified in complete Freund's adjuvant, were OV specific because they did not respond to other antigens in vitro. CII line cells could adoptively transfer delayed-type hypersensitivity (DTH) but did not induce IgG antibody production to collagen. Moreover, the intravenous administration of 2 X 10(7) CII line cells prevented the subsequent induction of collagen arthritis following immunization and suppressed DTH to collagen without affecting antibody responses in the recipients. Spleen cells, but not sera, from these resistant rats decreased CII line reactivity in vitro. OV or irradiated CII lines had no effect on clinical or immunologic parameters in this model. These findings demonstrate protection from arthritis afforded by T-cell line transfer and suggest that the phenomenon results from down-regulation of the recipients' cellular immunity to collagen.

Anti-immunoglobulin antibody detection in adjuvant arthritis by an ELISA technique

Sprague-Dawley rats, injected in the hind paw with heat-killed mycobacteria dispersed in oil, develop a severe polyarthritis. In this paper, we detected and quantified by a micro-ELISA technique autoantibodies against immunoglobulins in rats with adjuvant arthritis. Increased total anti-immunoglobulin antibodies levels were found from 3 days after induction and remained elevated until day 42. IgG anti-immunoglobulin antibodies in arthritic animals were significantly elevated during days 35-42. These results show that alterations in the humoral immune response (synthesis of anti-immunoglobulin antibodies) are present in adjuvant arthritis as they are in human rheumatoid arthritis.

Characterization of the antibody response in mice with type II collagen-induced arthritis, using monoclonal anti-type II collagen antibodies

Twenty monoclonal antibodies reactive with type II collagen were characterized as to their determinant specificity and their reactivity with cartilage-derived components. The monoclonal antibodies reacted with 7 different epitopes on the native type II collagen triple helical structure. Antibodies defining 3 of these epitopes occurred more frequently in sera from arthritic mice than in sera from nonarthritic mice. In vivo injection of some selected autoreactive antibodies caused synovitis, but in no case did it give rise to full-blown arthritis.

An arthritogenic lymphokine in the rat

A type II collagen-specific arthritogenic lymphokine has been identified in the rat. Arthritogenic factor (AF) is a 65 kD protein generated in vitro by T cells from rats with collagen arthritis, and it induces an erosive, proliferative synovitis when injected into the knee joint of syngeneic naive recipients. Complement does not appear to be required. These data identify a potential T cell-mediated effector mechanism in this model, and suggest that AF may function in other inflammatory synovial diseases.

The study and manipulation of experimental autoimmune disease using T lymphocyte lines

Autoimmune diseases include entities of varied clinical expression such as juvenile onset diabetes mellitus, rheumatoid arthritis, multiple sclerosis, and thyroiditis. Nevertheless, these autoimmune diseases have a common origin; they are caused by clones of lymphocytes that specially attack the individual's own body components. To study autoimmune processes, we have isolated and grown as long-term cell lines the T lymphocytes that mediate several different experimental autoimmune diseases in rats or mice. These cell lines have increased our understanding of pathogenesis, but perhaps more importantly, it appears that suitably attenuated lines can be used to immunize the individual animal against its own autoimmune cells. Thus, autoimmune cells can be used as vaccines to prevent or treat the autoimmune process.

The autologous mixed lymphocyte reaction is decreased in Freund's adjuvant-injected rats of arthritis-susceptible and -insusceptible strains

We examined the T-non-T cell autologous mixed lymphocyte reaction (AMLR) of spleen cells from rats with arthritis induced by Freund's complete adjuvant in an effort to establish an animal model for the study of the relationship between the AMLR and autoimmune disease. We found that the splenic T-non-T AMLR was markedly decreased in rats with adjuvant-induced arthritis and that this decrease was mediated by suppressor cells within the nylon-wool-adherent stimulator cell population. However, we also found a similar decrease in the AMLR of arthritis-resistant Fisher 344 rats that received Freund's complete adjuvant but did not develop arthritis. Control animals with local inflammation induced by turpentine, a non-arthritogenic inflammatory substance, had normal AMLR, whereas other controls given Freund's incomplete adjuvant, also a non-arthritogenic substance, had a modest responder cell-mediated decrease in AMLR. These studies help to clarify the relationship between the decreased AMLR and the pathogenesis of adjuvant-induced arthritis by demonstrating that: 1) the acute-phase inflammatory response does not reduce the AMLR; and 2) the decreased AMLR can occur in the absence of overt autoimmune disease. This latter observation calls into question the proposed pathogenetic relationship between the AMLR and autoimmune disease states.

Inhibition of collagen II arthritis by simultaneous administration of concanavalin A and other substances with antigen emulsion

Several pharmacological agents, some of which are known to have effects on the immune system, decrease the incidence of collagen II-induced arthritis when added to the antigen emulsion. Concanavalin A, which has been reported to exert suppressive effects on the immune system in vivo, consistently reduced the immune response to the collagen antigen. These effects were dose and time dependent. The suppressive effects of pokeweed mitogen, tilorone and carrageenan on anti-collagen II responses were somewhat variable. Suppressive activity could be observed with concanavalin A and levamisole when the drugs were injected at a site distant from the collagen emulsion. These studies indicate that local administration of drugs is an effective approach for demonstrating the activity of some agents that may alter the course of collagen II disease through an effect on the immune system.