Characterization of a spontaneously occurring arthritis in male DBA/1 mice

Levofloxacin induces differential effects in the transcriptome between the gut, peripheral and axial joints in the Spondyloarthritis DBA/1 mice: Improvement of intestinal dysbiosis and the overall inflammatory process

To analyze the effect of levofloxacin-induced intestinal microbiota modifications on intestinal, joint, and systemic inflammation in the DBA/1 mice with spontaneous arthritis. The study included two groups of mice, one of which received levofloxacin. The composition and structure of the microbiota were determined in the mice's stool using 16S rRNA sequencing; the differential taxa and metabolic pathway between mice treated with levofloxacin and control mice were also defied. The effect of levofloxacin was evaluated in the intestines, hind paws, and spines of mice through DNA microarray transcriptome and histopathological analyses; systemic inflammation was measured by flow cytometry. Levofloxacin decreased the pro-inflammatory bacteria, including Prevotellaceae, Odoribacter, and Blautia, and increased the anti-inflammatory Muribaculaceae in mice's stool. Histological analysis confirmed the intestinal inflammation in control mice, while in levofloxacin-treated mice, inflammation was reduced; in the hind paws and spines, levofloxacin also decreased the inflammation. Microarray showed the downregulation of genes and signaling pathways relevant in spondyloarthritis, including several cytokines and chemokines. Levofloxacin-treated mice showed differential transcriptomic profiles between peripheral and axial joints and intestines. Levofloxacin decreased the expression of TNF-α, IL-23a, and JAK3 in the three tissues, but IL-17 behaved differently in the intestine and the joints. Serum TNF-α was also reduced in levofloxacin-treated mice. Our results suggest that the microbiota modification aimed at reducing pro-inflammatory and increasing anti-inflammatory bacteria could potentially be a coadjuvant in treating inflammatory arthropathies.

Inflammatory Foot Involvement in Spondyloarthritis: From Tarsitis to Ankylosing Tarsitis

Spondyloarthritis (SpA) is a group that includes a wide spectrum of clinically similar diseases manifested by oligoarticular arthritis and axial or peripheral ankylosis. Although axial SpA is predominant in Caucasians and adult-onset patients, juvenile-onset and Latin American patients are characterized by severe peripheral arthritis and particularly foot involvement. The peripheral involvement of SpA can vary from tarsal arthritis to the most severe form named ankylosing tarsitis (AT). Although the cause and etiopathogenesis of axSpA are often studied, the specific characteristics of pSpA are unknown. Several animal models of SpA develop initial tarsitis and foot ankylosis as the main signs, emphasizing the role of foot inflammation in the overall SpA spectrum. In this review, we attempt to highlight the clinical characteristics of foot involvement in SpA and update the knowledge regarding its pathogenesis, focusing on animal models and the role of mechanical forces in inflammation.

Atractylodin Suppresses Dendritic Cell Maturation and Ameliorates Collagen-Induced Arthritis in a Mouse Model

The aim of this study was to evaluate the immunomodulatory effects of atractylodin, a polyethylene alkyne, on the maturation of bone marrow-derived dendritic cells (BM-DC) as well as its antirheumatic effect on collagen-induced arthritis (CIA) in DBA/1 mice. Our results indicate that atractylodin effectively suppressed the secretion of pro-inflammatory cytokines, expression of costimulatory molecules, and p38 MAPK, ERK, and NF-κBp65 signaling pathways in LPS-incubated dendritic cells (DCs). Additionally, the proliferation and cytokine secretion (IFN-γ and IL-17A) of CD8⁺ and CD4⁺ T cells were reduced. In a murine CIA model, intraperitoneal injection of atractylodin significantly alleviated the severity of the disease progression, as indicated by reduced paw swelling, clinical arthritis scores, and pathological changes of joint tissues. In addition, the overall proliferation of T cells stimulated by type II collagen and the abundance of Th1 and Th17 in the spleens were also significantly decreased with atractylodin treatments. Furthermore, atractylodin significantly downregulated the expression levels of CD40, CD80, and CD86 of DCs in the spleens. In conclusion, this study shows for the first time that atractylodin has potential to manipulate the maturation of BM-DCs and should be further explored as a therapeutic agent in the treatment of rheumatoid arthritis (RA).

The effect of anti-IL-6 receptor antibody for the treatment of McH-lpr/lpr-RA1 mice that spontaneously developed destructive arthritis and enthesitis

Background

McH-lpr/lpr-RA1 mice are a new strain of mice which spontaneously develop destructive arthritis and enthesitis in the ankle. There is no published data that drug treatment has been trialed on these mice. This study examined the effect of the mouse anti-IL-6 receptor antibody, MR16–1, for the treatment of arthritis and enthesitis in McH-lpr/lpr-RA1 mice.

Methods

Male McH-lpr/lpr-RA1 mice were randomly divided into control and treatment groups. MR16–1 was administered from 10 weeks of age for the treatment group. Saline was applied for the control group. The drug was administered once a week, at an initial dose of 2 mg, then maintained at 0.5 mg once per week thereafter. The effects were evaluated by the histopathological synovitis score, in vivo imaging using indocyanine green liposomes, and analysis of the gene expression of inflammatory cytokines.

Results

Tissue analyses were carried out at 14, 17 and 20 weeks of age. The synovitis scores of treated groups were significantly lower compared with those of the control group at 14 and 17 weeks of age. The kappa coefficient was 0.77. However, progression of entheseal ossification persisted in the MR16–1 treated group. In vivo imaging using indocyanine green liposomes showed significant decreases in signal intensities of treated groups at week 14, but no significant differences were observed at week 18. Blood serum amyloid A levels in treated groups were significantly lower at 17 weeks of age. The gene expression levels of Tnf and Il17 were also significantly lower in MR16–1 treated groups.

Conclusions

Administration of the anti-IL-6 receptor antibody is effective for the treatment of synovitis and bone destruction of McH-lpr/lpr-RA1 mice. McH-lpr/lpr-RA1 mice may be a suitable experimental model for the development of new treatments for destructive arthritis and enthesitis. IL-6 signal blockade could contribute to the treatment of destructive arthritis, and further studies should be carried out to confirm its potential in the prevention of enthesopathy developed to ossification.

Conjugated Linoleic Acid Isomers Trans-10, Cis-12 and Cis-9, Trans-11 Prevent Collagen-Induced Arthritis in a Direct Comparison

Mixed-isomer conjugated linoleic acid (CLA) and the individual isomers, trans-10, cis-12 (CLAt10c12) and cis-9, trans-11 (CLAc9t11), decrease severity of collagen-induced arthritis (CA) when consumed after disease onset. Few studies have been conducted exploring the role of CLA in the prevention of autoimmune diseases. These studies suggest that isomer-specific effects may be occurring; however, a direct comparison of CLAt10c12 and CLAc9t11 has yet to be conducted. A study to compare the ability of CLAt10c12 and CLAc9t11 to prevent CA and assess their effects on early inflammation was performed. DBA/1 mice were fed a semipurified diet containing 6% corn oil (CO), 5.5% CO and 0.5% CLAt10c12, or 5.5% CO and 0.5% CLAc9t11 (n = 27 per diet) starting three weeks before CA primary immunization. Effects on disease incidence and severity, anticollagen antibodies, plasma and paw cytokines, and hepatic fatty acids were measured. Arthritis incidence was reduced by a minimum of 34% in mice fed either CLA isomer compared to those fed CO diet (p = 0.06). In mice that did develop arthritis (n = 9-12 mice per treatment), CLAt10c12 reduced arthritic severity to a greater extent than CLAc9t11 and CO (p = 0.03). CLA isomer treatment attenuated the increased hepatic arachidonic acid (ARA; 20:4n-6) observed with arthritis at one-week postonset (p = 0.03), while no differences in anticollagen antibodies or cytokines were observed between dietary treatments. These results suggest that CLA isomers may be effective at preventing specific immune-mediated inflammatory diseases, in part, through modulation of the ARA cascade.

The benefits and limitations of animal models for translational research in cartilage repair

Much research is currently ongoing into new therapies for cartilage defect repair with new biomaterials frequently appearing which purport to have significant regenerative capacity. These biomaterials may be classified as medical devices, and as such must undergo rigorous testing before they are implanted in humans. A large part of this testing involves in vitro trials and biomechanical testing. However, in order to bridge the gap between the lab and the clinic, in vivo preclinical trials are required, and usually demanded by regulatory approval bodies. This review examines the in vivo models in current use for cartilage defect repair testing and the relevance of each in the context of generated results and applicability to bringing the device to clinical practice. Some of the preclinical models currently used include murine, leporine, ovine, caprine, porcine, canine, and equine models. Each of these has advantages and disadvantages in terms of animal husbandry, cartilage thickness, joint biomechanics and ethical and licencing issues. This review will examine the strengths and weaknesses of the various animal models currently in use in preclinical studies of cartilage repair.

An in vitro model for the pathological degradation of articular cartilage in osteoarthritis

The objective of this study was to develop an in vitro cartilage degradation model that emulates the damage seen in early-stage osteoarthritis. To this end, cartilage explants were collagenase-treated to induce enzymatic degradation of collagen fibers and proteoglycans at the articular surface. To assess changes in mechanical properties, intact and degraded cartilage explants were subjected to a series of confined compression creep tests. Changes in extracellular matrix structure and composition were determined using biochemical and histological approaches. Our results show that collagenase-induced degradation increased the amount of deformation experienced by the cartilage explants under compression. An increase in apparent permeability as well as a decrease in instantaneous and aggregate moduli was measured following collagenase treatment. Histological analysis of degraded explants revealed the presence of surface fibrillation, proteoglycan depletion in the superficial and intermediate zones and loss of the lamina splendens. Collagen cleavage was confirmed by the Col II-3/4Cshort antibody. Degraded specimens experienced a significant decrease in proteoglycan content but maintained total collagen content. Repetitive testing of degraded samples resulted in the gradual collapse of the articular surface and the compaction of the superficial zone. Taken together, our data demonstrates that enzymatic degradation with collagenase can be used to emulate changes seen in early-stage osteoarthritis. Further, our in vitro model provides information on cartilage mechanics and insights on how matrix changes can affect cartilage's functional properties. More importantly, our model can be applied to develop and test treatment options for tissue repair.

Spontaneous arthritis and ankylosis in male DBA/1 mice: further evidence for a role of behavioral factors in "stress-induced arthritis"

Background

Ageing male DBA/1 mice spontaneously develop arthritis in the hind paws. We and others have demonstrated that this model shares striking features with human spondyloarthritis, in particular entheseal involvement, progressive ankylosis but also dactylitis. Here, we report on our recent experience with this model highlighting how changes in the animal facility affect the development of the disease.

Findings

Ageing male DBA/1 mice from different litters were caged together (6 mice per cage) at the age of 10 weeks. The mice were checked twice a week for clinical signs of arthritis. Disease severity was assessed in further detail post-mortem by scoring for histomorphological characteristics. DBA/1 mice spontaneously develop macroscopically detectable arthritis, presenting as joint swelling or toe stiffness. Standard settings with open cages lead to an almost 100% incidence by the age of 26 weeks. The introduction of larger cages and filter tops reducing exposure to other cages dramatically affected incidence. Other negative factors include excess bedding material reducing the impact of walking and running. Switching back to the original conditions resulted again in a high incidence, further optimized by sensory exposure to female mice. We also showed that the related DBA/2 strain is sensitive to the disease.

Conclusions

Changing environmental factors in the housing conditions of DBA/1 mice severely affects the spontaneous development of arthritis. This points out that the model is very sensitive to external stress and sensory factors that are likely affecting the behavior of the male mice and that the model needs to be optimized in different situations.

The role of bone morphogenetic proteins in ankylosing spondylitis

Ankylosing spondylitis (AS), the best-known form of spondyloarthritis (SpA), is a remodelling arthritis characterized by chronic inflammation and bone formation. Ankylosis of the axial skeleton and sacroiliac joints leads to an impairment of spinal mobility, progressive spinal fusion and an increased risk of spinal fractures. The nature of the relationship between inflammation and new bone formation in AS has been controversial and questions remain as to whether there is a direct relationship between inflammation and new bone formation. Like others, we have hypothesized that the molecular pathways underlying ankylosis recapitulate the process of endochondral bone formation and that bone morphogenetic proteins (BMPs) play a key role in this process in AS. Furthermore, we discuss the entheseal stress hypothesis, which proposes that inflammation and ankylosis are linked but largely independent processes, and consider observations from mouse models and other human diseases which also imply that biomechanical factors contribute to the pathogenesis of AS. As current therapeutics, such as tumour necrosis factor inhibitors do not impede disease progression and ankylosis in AS, it is the pathways discussed in this review that are the now the focus for the identification of future drug targets.

Lipopolysaccharide treatment suppresses spontaneously developing ankylosing enthesopathy in B10.BR male mice: the potential role of interleukin-10

Background

Ankylosing enthesopathy (ANKENT) is an animal model of human ankylosing spondylitis. ANKENT is an inflammatory disease affecting the ankle and tarsal joints of the hind limbs in susceptible mouse strains. In the disease, the participation of intestinal microbiota components was suggested. Therefore, we attempted to increase the incidence of ANKENT by systemic administration of lipopolysaccharide (LPS), which is a component of bacterial cellular walls and stimulates inflammatory processes.

Methods

ANKENT occurrence, serum cytokine profiles, spleen cellular composition and in vitro cytokine response to LPS were analysed in LPS-treated and control LPS-untreated B10.BR male mice.

Results

Contrary to expectations, LPS treatment decreased the incidence of ANKENT in LPS-treated group compared to control LPS-untreated group. Flow cytometry analysis of splenocytes showed an increased percentage of macrophages, dendritic cells and neutrophils and a decreased percentage of B cells, T cells and T helper cells in LPS-treated males following LPS administration. In addition, LPS-treated males had significantly elevated IL-6 and IL-10 serum levels. At 20–22 weeks after the final LPS application, splenocytes from LPS-treated mice were more susceptible to in vitro LPS stimulation than those of the controls and produced significantly higher levels of TNFα and IL-6.

Conclusions

Repeated systemic stimulation with microbial component lipopolysaccharide in early adulthood significantly reduced the incidence of ANKENT in B10.BR mice and this finding can support the “hygiene hypothesis”. In LPS-treated mice, the innate immunity parameters and the level of anti-inflammatory IL-10 cytokine were significantly increased. Nevertheless, the immunological mechanism of the LPS protective effect remains unclear.

Translational animal models using veterinary patients - An example of canine osteoarthritis (OA)

Background and purpose The use of laboratory animals in pain research has powerfully contributed to our detailed understanding of the physiological mechanisms of pain. Animal models also represent an essential tool to screen and select novel drug molecules with potentially analgesic properties. Despite of the inevitable input of laboratory animal trials, recent studies have shown that animal pain models have repeatedly failed to predict clinical analgesic efficacy and adverse side effects of potential drug molecules in human pain patients. This paper provides a review of the laboratory animal models of OA, which have been developed to test efficacy of novel analgesics. The paper also presents spontaneous OA in canine veterinary patients, and methods to observe chronic pain in nonverbal dogs. Methods PubMed data base was searched as a reference list to locate most relevant articles. A number of 118 articles including 4 reviews were located. Web pages of 4 establishments and 2 private organizations were also accessed. Results The clinical expression and pathogenesis of naturally occurring OA in dogs is considered an analogous disease that occurs in humans, including pain and lameness. OA may occur in any joint in dogs as well as in humans. Primary idiopathic OA in dogs is rare, but certain breeds may be predisposed to it. For the most part, canine OA is considered secondary to acquired or congenital musculoskeletal disorders. Concomitant factors, such as aging and obesity, likely accelerate progression. However, mechanical factors appear to predominate in the etiopathogenesis of canine spontaneous OA. Both subjective (validated questionnaire) and objective (gait analysis) tools are available to measure OA related pain in dogs. Information on the prevalence of canine OA is limited, but rough surveys suggest that 11 million dogs in the United States and 5 million in Europe could suffer from OA. Ethical considerations concerning the use of privately owned dogs can be resolved by a careful experimental design. Conclusion Canine spontaneous OA could serve as a translational animal model that would more closely mimick clinical OA related pain conditions in humans. Privately owned dogs would make a solution to fix the gap between animal pain models and clinical trials when testing potential analgesic drug molecules. Close interdisciplinary cooperation would guarantee that both scientific and ethical intentions would be achieved. Implications The predictability of translational pain research would improve by using privately owned dogs as chronic pain models when testing novel analgesics.

Ankylosing enthesitis associated with up-regulated IFN-gamma and IL-17 production in (BXSB x NZB) F(1) male mice: a new mouse model

We found that in contrast to (BXSB x NZB) F(1) female mice that spontaneously develop severe systemic lupus erythematosus (SLE), male (BXSB x NZB) F(1) mice are not prone to SLE, but instead develop seronegative ankylosing enthesitis in ankle/tarsal joints only when caged in groups, with the incidence reaching 83% at 7 months of age. This ankylosis is microscopically characterized by a marked proliferation of fibroblast-like cells positive for bone morphogenetic protein (BMP)-2 in association with heterotropic formation of cartilages and bones in hyperplastic entheseal tissues and subsequent fusion of tarsal bones. Elevated potentials of popliteal lymph node T cells producing interleukin (IL)-17 and interferon (IFN)-gamma were significantly associated with joint ankylosis, suggesting the involvement of these cytokines in effector phase mechanisms of the disease, including up-regulated BMP signaling pathways. There was no difference in serum autoantibody levels between affected and unaffected mice. Parental BXSB and NZB strains of both sexes did not develop the disease even when caged in groups, indicating that the disease develops under the control of susceptibility genes derived from both parental strains. These results indicate that (BXSB x NZB) F(1) male mice are a suitable model for clarifying genetic, environmental and molecular mechanisms underlying ankylosing enthesitis and related diseases.

Animal models of spondyloarthritis

Animal models are available for the study of several different aspects of spondyloarthritis. The models include naturally occurring spontaneous disorders in primates and rodents, spontaneous disorders in transgenic or gene-deleted rodents and induced disorders in rodents. Areas of investigation to which these models contribute include the role HLA-B27, processes of spinal and peripheral joint inflammation and calcification, immune responses to candidate antigens and the role of TNF.

In vivo magnetic resonance imaging of animal models of knee osteoarthritis

Recent technical developments in high-field magnetic resonance (MR) scanners, improvement in radio frequency coil design and gradient performance along with the development of efficient pulse sequences and new methods of enhancing contrast have made high-quality imaging of animal arthritis models feasible. MR can provide high-resolution structural information about the osteoarthritic changes in animal models, and also information about the biophysical properties of cartilage. This paper reviews the MR techniques available for animal knee imaging, and the various MR-derived readouts of knee osteoarthritis in animal models. Pitfalls in interpreting animal joint anatomy and joint composition are highlighted.

Novel recombinant congenic mouse strain developing arthritis with enthesopathy

Based on the hypothesis that the complex pathological and immunological manifestations of rheumatoid arthritis (RA) and the related diseases are under the control of multiple gene loci with allelic polymorphism, a recombinant congenic mouse strain was prepared between an MRL/Mp-lpr/lpr (MRL/lpr) strain, which develops arthritis resembling RA, and a non-arthritic strain C3H/HeJ-lpr/lpr (C3H/lpr). In MRL/lpr x (MRL/lpr x C3H/lpr) F1 mice, the mice developing severe arthritis were selected based on joint swelling to further continue intercrosses, and then an McH-lpr/lpr-RA1 (McH/lpr-RA1) strain was established and its histopathological phenotypes of joints and autoimmune traits were analyzed. Arthritis in McH/lpr-RA1 mice developed at a higher incidence by 20 weeks of age, compared with that in the MRL/lpr mice, who had severe synovitis (ankle, 60.3%; knee, 65.1%), and also fibrous and fibrocartilaginous lesions of articular ligamenta resembling enthesopathy (ankle, 79.4%; knee, 38.1%), resulting in ankylosis. The lymphoproliferative disorder was less, and serum levels of IgG and IgG autoantibodies including anti-dsDNA and rheumatoid factor were lower than those of both MRL/lpr and C3H/lpr strains. McH/lpr-RA1 mice may provide a new insight into the study of RA regarding the common genomic spectrum of seronegative RA and enthesopathy.

Collagen-induced arthritis

The collagen-induced arthritis (CIA) mouse model is the most commonly studied autoimmune model of rheumatoid arthritis. Autoimmune arthritis is induced in this model by immunization with an emulsion of complete Freund's adjuvant and type II collagen (CII). This protocol describes the steps necessary for acquisition, handling and preparation of CII, as well as selection of mouse strains, proper immunization technique and evaluation of the arthritis incidence and severity. Typically, the first signs of arthritis appear in this model 21-28 days after immunization, and identification of the arthritic limbs is not difficult. Using the protocol described, the investigator should be able to reproducibly induce a high incidence of CIA in various strains of genetically susceptible mice as well as learn how to critically evaluate the pathology of the disease. The total time for the preparation of reagents and the immunization of ten mice is about 1.5 h.

A mechanistic approach to understanding conjugated linoleic acid's role in inflammation using murine models of rheumatoid arthritis

A naturally occurring fatty acid, conjugated linoleic acid (CLA), reduces immune-induced TNF and inducible cyclooxygenase (COX-2) expression; key mediators of inflammation in rheumatoid arthritis (RA). On the basis of previous work, it was hypothesized that dietary CLA would act as an anti-inflammatory agent in select animal models of RA. In the collagen antibody-induced arthritis (CAIA) model, mice fed CLA (mixed isomers of c9, t11, and t10, c12-CLA) for 3 wk before anticollagen antibody injection had reduced lipopolysaccharide-induced plasma TNF levels and had arthritic scores that were 60% of mice fed corn oil (CO). In the collagen-induced arthritis (CIA) model, mice fed mixed isomers of CLA for 21 days before immunization had lower IgG(1) titers, earlier signs of joint inflammation, but similar arthritis scores compared with CO fed mice during the remaining 70-day post-injection period. Beginning on day 80 to 133, CLA-fed mice had arthritic scores 70% that of the CO-fed mice. In a second CIA experiment, CLA was fed only after the booster injection. Plasma IgG(1) levels were not reduced and arthritis onset was delayed 4 days in CLA-fed mice compared with the CO-fed mice. Peak arthritis score was similar between CLA and CO-fed mice from day 35 to 56. Because CLA reduced inflammation in the CAIA model, delayed onset of arthritis in the CIA model (CIA experiment 2) and reduced arthritis score after day 80 in the CIA model (CIA experiment 1), we concluded that dietary CLA exhibited anti-inflammatory activity that was dependent on antibody.

A non-major histocompatibility locus determines tissue specificity in the pathogenic process underlying synovial proliferation in a mouse arthropathy model

BACKGROUND

The incidence and characteristics of spontaneous ankylosis in the ankle of specific F(1) mice descended from two Fas-deficient strains were reported. Here the coincidence of synovial proliferation and ankylosis in the descendent F(2) mice is reported.

AIM

To clarify whether the two distinct manifestations are genetically different.

METHODS

An arthropathic group of mice (MCF(2)) were bred by intercrossing MRL/Mp.Fas(lpr)-sap(-)/sap(-) and C3H/He.Fas(lpr) mice. All mice were killed by bleeding under anaesthesia when they were 6 months old. Pathological grades for synovial proliferation were determined by microscopical examination. To obtain a linkage locus, the whole genome of male MCF(2) mice was scanned by using 73 microsatellite markers.

RESULTS

Synovial proliferation was equally observed in male and female MCF(2) mice. No correlation was observed between the grades of synovial proliferation and the ankylosis occurring in the MCF(2) mice. A suggestive susceptibility locus was shown in the middle of chromosome 11. This locus was an MRL allele with a recessive inheritance mode.

CONCLUSION

The pathogenic mechanisms of synovial proliferation and ankylosis are genetically different. The present locus is overlapped with some loci associated with rheumatoid arthritis and with others associated with experimental arthritides.

Is there a role for TNF-alpha in anti-neutrophil cytoplasmic antibody-associated vasculitis? Lessons from other chronic inflammatory diseases

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is the most common cause of rapidly progressive glomerulonephritis and immune-mediated pulmonary renal syndrome. Now that the acute manifestations of the disease generally can be controlled with immunosuppressive drugs, ANCA-associated vasculitis has become a chronic and relapsing inflammatory disorder. The need to develop safer and more effective treatment has led to great interest in the mediators of chronic inflammation. There are many lessons to be learned from studies of other chronic inflammatory diseases, particularly rheumatoid arthritis (RA). The identification of a TNF-alpha-dependent cytokine cascade in the in vitro cultures of synovium in joints of patients with RA led to studies of TNF blockade in experimental models of arthritis and subsequently to clinical trials. These have culminated in the widespread introduction of anti-TNF therapy not only in RA but also in Crohn disease, ankylosing spondylitis, and several other chronic inflammatory disorders. Following a similar investigative pathway, studies that show the importance of TNF production by leukocytes and intrinsic renal cells in glomerulonephritis have been followed by the demonstration of the effectiveness of TNF blockade in several experimental models of glomerulonephritis and vasculitis. In experimental autoimmune vasculitis, improvement in disease was paralleled by a reduction in leukocyte transmigration, as demonstrated by intravital microscopy. The benefit of infliximab (a mAb to TNF) in ANCA-associated vasculitis was recently reported in a prospective open-label study. However, the use of etanercept (a soluble TNF receptor fusion protein) was not found to be of significant benefit in a randomized, controlled trial in patients with Wegener granulomatosis. Therefore, there is a need for further evaluation of the use of anti-TNF antibodies in patients with ANCA-associated glomerulonephritis.

Genetic characterisation of spontaneous ankylosing arthropathy with unique inheritance from Fas-deficient strains of mice

BACKGROUND

The spontaneous onset of macroscopic arthropathy in the ankle of the particular F1 mice descended from two Fas-deficient strains of mice; a mutant substrain of MRL/Mp.Fas(lpr) (MRL/rpl) and C3H/He.Fas(lpr) (C3H/lpr) was recently observed.

AIM

To histopathologically characterise and genetically interpret the unique inheritance mode of disease in this arthropathy model.

METHODS

MRL/rpl, C3H/lpr, (MRL/rpl x C3H/lpr; MC) F1, (C3H/lpr x MRL/rpl; CM) F1 and MCF2 mice were bred under specific pathogen-free conditions. Histopathological grade of arthropathy was determined at 6 months by examination under a light microscope. To search for a linkage locus to the arthropathy, the whole genome of selected 48 male MCF2 mice with 71 polymorphic microsatellite markers was scanned, followed by quantitative trait locus analysis.

RESULTS

The incidence of microscopically defined arthropathy in the male and female MCF1 groups was 100% and 19.4%, respectively. No incidence was observed in the parental strains, MRL/rpl and C3H/lpr, and in CMF1 mice. In the MCF1 mice, the arthropathy mainly affected the ankle joints and was histopathologically characterised by marked entheseal proliferation with chondrocytic differentiation and ossification in the ankle joints, the manifestations similar to ankylosing enthesitis reported previously. An MRL/rpl-derived autosomal dominant susceptibility locus was mapped in the distal of D7Mit68 (60 cM) to the ankylosis onset.

CONCLUSION

The MCF1 mice stably develop spontaneous ankylosing disorders in the ankle, with a male predominance. The unique inheritance mode of ankylosis is possibly interpreted by the genetic interaction between the autosomal dominant locus and a Y-linked locus.

Development of spontaneous multisystem autoimmune disease and hypersensitivity to antibody-induced inflammation in Fcgamma receptor IIa-transgenic mice

OBJECTIVE

The major human Fc receptor, FcgammaRIIa, is the most widespread activating FcR. Our aim was to determine the role of FcgammaRIIa in a transgenic mouse model of immune complex-mediated autoimmunity and to characterize the development of spontaneous autoimmune disease.

METHODS

Arthritis was induced in normal and FcgammaRIIa-transgenic mice by immunization with type II collagen (CII) or by transfer of arthritogenic anti-CII antibodies. Also, mice that spontaneously developed autoimmune disease were assessed by clinical scoring of affected limbs, histology and serology, and measurement of autoantibody titers and cytokine production.

RESULTS

FcgammaRIIa-transgenic mice developed collagen-induced arthritis (CIA) more rapidly than did archetypal CIA-sensitive DBA/1 (H-2q) mice, while nontransgenic C57BL/6 (H-2b) mice did not develop CIA when similarly immunized. Passive transfer of a single dose of anti-CII antibody induced a more rapid, severe arthritis in FcgammaRIIa-transgenic mice than in nontransgenic animals. In addition, most immune complex-induced production of tumor necrosis factor alpha by activated macrophages occurred via FcgammaRIIa, not the endogenous mouse FcR. A spontaneous, multisystem autoimmune disease developed in aging (>20 weeks) transgenic mice (n = 25), with a 32% incidence of arthritis, and by 45 weeks, all mice had developed glomerulonephritis and pneumonitis, and most had antihistone antibodies. Elevated IgG2a levels were seen in mice with CIA and in those with spontaneous disease.

CONCLUSION

The presence of enhanced passive and induced autoimmunity, as well as the emergence of spontaneous autoimmune disease at 20-45 weeks of age, suggest that FcgammaRIIa is a very important factor in the pathogenesis of autoimmune inflammation and a possible target for therapeutic intervention.

Modulation of bone morphogenetic protein signaling inhibits the onset and progression of ankylosing enthesitis

Joint ankylosis is a major cause of disability in the human spondyloarthropathies. Here we report that this process partially recapitulates embryonic endochondral bone formation in a spontaneous model of arthritis in DBA/1 mice. Bone morphogenetic protein (BMP) signaling appears to be a key molecular pathway involved in this pathological cascade. Systemic gene transfer of noggin, a BMP antagonist, is effective both as a preventive and a therapeutic strategy in the mouse model, mechanistically interfering with enthesial progenitor cell proliferation in early stages of the disease process. Immunohistochemical staining for phosphorylated smad1/5 in enthesial biopsies of patients with spondyloarthropathy reveals active BMP signaling in similar target cells. Our data suggest that BMP signaling is an attractive therapeutic target for interfering with structural changes in spondyloarthropathy either as an alternative or complementary approach to current antiinflammatory treatments.

Accelerating effect of an MRL gene locus on the severity and onset of arthropathy in DBA/1 mice

OBJECTIVE

To analyze the influence of the genetic background of an arthritis-prone strain of mice, MRL, on the spontaneous development of arthropathy in DBA/1 mice, which histopathologically resembles enthesopathy in humans, and to clarify the strain-specific gene loci and their interactions that confer susceptibility to arthropathy.

METHODS

MRL, DBA/1, (MRL x DBA/1)F(1), and (MRL x DBA/1)F(2) intercross mice were prepared, and the severity and onset of arthropathy of the ankle joints in individual mice were quantified (0-3 and 0-5 scale, respectively). A genome-wide scan of 271 male F(2) intercross mice with polymorphic microsatellite markers was performed.

RESULTS

Only male DBA/1, (MRL x DBA/1)F(1), and (MRL x DBA/1)F(2) mice developed arthropathy. The macroscopic and histopathologic findings of arthropathy in the F(2) mice were similar to those in the parental DBA/1 mice, but the onset was significantly earlier. In the quantitative trait locus analysis of male F(2) mice, 1 susceptibility locus for both the severity and early onset of the disease in the region of an MRL allele, Amd1, was located at marker D10Mit259 (map position 40.0 cM), which was common to 1 of the sialadenitis susceptibility loci in MRL mice, Asm1. Another susceptibility locus for the severity and early onset of arthropathy in the region of a DBA allele, Amd2, was located at D3Mit46 (29.5 cM). These loci manifested an additive effect on the development of arthropathy.

CONCLUSION

Arthropathy in DBA/1 mice is under the control of an allelic combination of gene loci, one of which is common to the locus for sialadenitis in MRL/MpJ-lpr/lpr mice.

A robust model of adjuvant-induced chronic unilateral arthritis in two mouse strains

We have developed a model of unilateral adjuvant-arthritis that is reproducible across two mouse strains. DBA/1 and C57BL/6 male mice were injected intra-articularly into a stifle joint with FCA (5 microg in 5 microl) once per week for 4 weeks. Measurements of joint diameter and joint histopathology were used to monitor the course of the arthritis. Inflammatory hyperalgesia was assessed as the pressure causing a limb withdrawal. FCA injection into the mouse stifle joint caused a pronounced increase in joint diameter when compared to the contralateral limb or vehicle controls. There was also a significant decrease in the pressure required to elicit a withdrawal of the injected limb. Histology showed arthritic changes, including synovial hypertrophy and polymorphonuclear neutrophil infiltration. In established chronic inflammation, seven days of treatment with either indomethacin (NSAID) or prednisolone (steroid) caused a significant decrease in joint inflammation and associated hyperalgesia. FCA induces a long-lasting joint inflammation in DBA/1 and C57BL/6 mice, which is restricted to the injected joint and exhibits some of the pathology associated with an arthritic condition. This model will be useful in examining the effect of joint inflammation on nociceptor sensitisation in both normal and transgenic mice.

Dependence on interferon-γ for the spontaneous occurrence of arthritis in DBA/1 mice

OBJECTIVE

Male DBA/1 mice are known to spontaneously develop arthritis in the hind legs. The present study was undertaken to investigate the role of endogenous interferon-gamma (IFNgamma) in the pathogenesis of this ankylosing enthesopathy.

METHODS

The role of IFNgamma was studied by examining the development of arthritis in IFNgamma receptor-knockout (IFNgammaR-KO) DBA/1 mice as compared with wild-type mice, and by treatment of wild-type mice with monoclonal anti-IFNgamma antibody. IFNgamma-disrupted and wild-type mice were mixed and housed in the same cage, and clinical symptoms of arthritis were assessed weekly for at least 9 weeks. Histologic examination was performed at the end of the experiment.

RESULTS

In DBA/1 wild-type mice, 70% of the animals developed clinical symptoms of spontaneous arthritis, such as redness and swelling of the proximal interphalangeal joints, toe stiffness, and ankylosis. As evident from microscopic evaluation, the arthritis was mainly characterized by formation of new cartilage and bone, originating at the entheses and leading to ankylosis. The incidence and severity of arthritis, both clinically and histologically, were significantly reduced in IFNgammaR-KO mice. In wild-type mice, neutralizing anti-IFNgamma antibody inhibited the occurrence of the disease for the duration of treatment.

CONCLUSION

The results suggest that endogenous IFNgamma plays an important role in the initial stages of spontaneous arthritis, and that the inflammatory components in its pathogenesis are more prominent than has been believed. In view of the similarity between this disease and spondylarthropathies in humans, the data suggest that endogenous IFNgamma may also play a disease-promoting role in the human condition and thus may serve as a target for therapy.

Mice lacking endogenous major histocompatibility complex class II develop arthritis resembling psoriatic arthritis at an advanced age

OBJECTIVE

To describe and characterize a novel inflammatory toe disease with severe bone destruction that developed spontaneously in "humanized" (HLA transgenic) mice lacking their own major histocompatibility complex (MHC).

METHODS

We studied 5 different HLA transgenic mouse lines (HLA-DR2.Ab(0), DR3.Ab(0), DR4.Ab(0), DQ6.Ab(0), and DQ8.Ab(0)) in similar genetic background for an extended period of time (>14 months). Clinical, radiologic, and histologic abnormalities were monitored, and the MHC-related major immunologic parameters in affected and resistant mice were compared.

RESULTS

Animals of 4 transgenic lines (HLA-DR2.Ab(0), DR4.Ab(0), DQ6.Ab(0), and DQ8.Ab(0)) developed severe toe inflammation accompanied by progressive bone resorption, hyperkeratosis, alopecia, loss of nails, and shortening and thickening of the distal phalanges. HLA-DR3.Ab(0) transgenic mice were resistant to inflammation. The disease manifested only at advanced ages (6 months or older) and affected 70-100% of the mice, with a female preponderance. The clinical signs and the radiographic and histopathologic features of the affected toes were not similar to those of any disease previously described in mice but did resemble those described for human psoriatic arthritis (PsA). Mice from the 4 susceptible lines expressed lower levels of the HLA transgene and exhibited significantly fewer CD4+ cells in the peripheral blood and reduced natural killer cell activity compared with mice from the resistant HLA-DR3.Ab(0) line.

CONCLUSION

This novel, spontaneously developing PsA-like toe disease in MHC-manipulated mice seems to be related to the absence of endogenous MHC class II. Replacement with HLA transgene expression that is insufficient (or no replacement at all) may result in imbalanced MHC class I and class II functions and lead to development of the disease.

Streptococcus sanguis modulates type II collagen-induced arthritis in DBA/1J mice

Native type II collagen is tolerogenic when given orally or i.p. to DBA/1J mice and induces autoimmune arthritis when given s.c. in CFA. The tolerogenic epitope is contained in cyanogen bromide fragment 11 (CB11) and is structurally mimicked by PGEQGPK within the platelet aggregation-associated protein (PAAP) on Streptococcus sanguis. To learn whether S. sanguis modulates transmucosally the Ag-specific development of autoimmune arthritis, DBA/1J pups were given live S. sanguis, CB11, or type II collagen intragastrically. Feeding S. sanguis at 6 days postpartum delayed the onset of arthritis, and reduced the rate, final severity, and percentage of affected limbs. Next, PAAP(+) S. sanguis and type II collagen were tested for T cell cross-reactivity. T cells primed with the tolerogenic epitope of type II collagen proliferated more when incubated with PAAP(+) S. sanguis than with PAAP(-) Streptococcus gordonii or type II collagen, suggesting an Ag-specific transmucosal tolerogenic effect. In neonatal mice, therefore, bacterial surface Ags that mimic self can transmucosally stimulate Ag-specific inhibitory T cells. In adult mice immunized with type II collagen, these Ag-specific inhibitory T cells manifest later as attenuated arthritis. The PAAP(+) S. sanguis appear to activate adult memory, rather than naive, type II collagen-specific T cells, suggesting that systemic challenge with commensal self-mimicking microorganisms may perpetuate existing autoimmunity, but not initiate autorecognition.

The genetic and immunopathological processes underlying collagen-induced arthritis

Animal models of rheumatoid arthritis (RA) have provided substantial insights into basic pathogenic mechanisms of chronic inflammatory arthritis and autoimmune disease in general. Of the variety of models reported, collagen-induced arthritis (CIA) has been the most characterized in terms of both its pathogenesis and its underlying immunological basis. Collagen-induced arthritis has also been the model of choice in terms of testing potential new therapeutic agents for the treatment of human RA. Nevertheless, the complex nature of the balance between T-cell cytokines and the chronic inflammatory processes is only recently becoming clear. This review focuses on these developments, highlighting their implications for our understanding of RA and for the use of CIA as a suitable animal model.

Chronic relapsing homologous collagen-induced arthritis in DBA/1 mice as a model for testing disease-modifying and remission-inducing therapies

OBJECTIVE

To test whether the chronic relapsing arthritis induced by immunizing DBA/1 mice with homologous type II collagen is a valuable model for testing disease-modifying antiarthritic drugs.

METHODS

Six-week-old male DBA/1 mice were immunized with murine type II collagen in Freund's complete adjuvant, resulting in a chronic relapsing polyarthritis in >80% of the mice 4 weeks after immunization. At the onset of clinical arthritis, mice were treated for 4 weeks with different treatments, including anti-tumor necrosis factor (anti-TNF) and antiinterleukin-12 (anti-IL-12) antibodies, salbutamol, or indomethacin. Alternatively, treatment was administered as a pulse at the beginning of clinical arthritis. Pulse treatments tested included anti-CD3 in combination with anti-TNF, anti-TNF alone, and anti-CD4, either alone or in combination with anti-TNF. After 4 weeks of arthritis, mice were killed and hind paws were assessed histologically for joint damage.

RESULTS

Anti-TNF and salbutamol both suppressed clinical arthritis more effectively than indomethacin and, moreover, protected the joints from damage, whereas indomethacin did not. Anti-IL-12 treatment initiated after the onset of clinical symptoms accelerated disease. Pulse therapy with anti-CD3 plus anti-TNF was found to induce remission, clinically as well as histologically, whereas a pulse with either anti-CD4, anti-TNF, or the combination of anti-CD4 plus anti-TNF was less effective.

CONCLUSION

Chronic relapsing homologous collagen-induced arthritis is a valuable model for identifying remission-inducing antiarthritic drugs and has predictive value with respect to their joint-protective potency.

Osteoarthritis-like lesions in transgenic mice harboring a small deletion mutation in type II collagen gene

OBJECTIVE

The present study was conducted on transgenic Del1 (+/-) mice harboring six copies of a transgene with small deletion mutation engineered into mouse type II collagen gene. Incorporation of transgene into mouse genome was predicted to cause reduced mechanical strength of articular cartilage with deposition of structurally inferior collagen network and consequently to predispose the animal to early-onset joint degeneration.

DESIGN

Progression of degenerative chances in the knee joints of Del1 (+/-) and control mice was followed by macroscopic and histologic analyses at 3-5 month intervals between 3 and 22 months of age. Expression and distribution of type II collagen was studied with Northern hybridization, RNase protection assay and immunohistochemistry.

RESULTS

Articular cartilage degeneration began with superficial fibrillation at the age of 3 months in Del1 (+/-) mice. These changes coincided with a significant reduction in the expression of both endogenous and transgene-derived type II collagen mRNA. The defects gradually progressed into erosions penetrating the articular cartilage, bony sclerosis, degeneration of menisci, mineralization of various joint structures, cyst formation and exposure of subchondral bone. Nontransgenic controls also developed osteoarthritic lesions, but these appeared significantly later and were less severe. Increased transcription of type IIA procollagen mRNA, typical for chondroprogenitor cells and cartilage repair was also observed at six months in Del1 (+/-) mice.

CONCLUSION

These findings suggest that the impact of truncated type II collagen transgene, together with maturation-related reduction in type II collagen production significantly contribute to the early-onset degeneration of knee joints in Del1 (+/-) mice. These mice with osteoarthritis-like phenotype should provide a useful model for studies on the early pathogenic mechanisms involved in articular cartilage degeneration.

Complementation between HLA-DR4 (DRB1*0401) and specific H2-A molecule in transgenic mice leads to collagen-induced arthritis

We generated transgenic mice with DRB1*0401 gene with mutation in the beta2 domain (aa 110 and 139) for better interaction with mCD4. The DR4 transgene was introduced into H2-Aq (B10RQB3) and H2-Af (B10RFB3) to examine the role of DR4 in collagen arthritis. The HLA-DR molecules in these mice were found to be functional on the basis of their positive/negative selection of the Vbeta T cell repertoire. H2-Aq mice are resistant to porcine CII-induced arthritis. The RQB3/DR4 mice (H2Aq/DR4) developed severe collagen induced arthritis (CIA) when immunized with Porcine type II collagen while the negative littermates were resistant. RQB3.DR4 mice were also highly susceptible to CIA induced by Human CII while negative littermates got only mild disease. However, RFB3/DR4 mice (H2Af/ DR4) did not get CIA with any type II collagen. Therefore, the DR4 gene in the context of H2-Aq predisposes to severe arthritis but not in the context of H2-Af. Antibodies to renatured cyanogen bromide (CB) cleaved fragments of PII in RQB3/DR4 mice and negative littermates suggest that the presence of DR4 does not result in any differences in specificity of antibody response to CB fragments. These results indicate that a specific gene complementation occurring between DR4 and H2.Aq but not DR4 and H2Af promotes the induction of arthritis with PII and HII in these mice. A similar interaction may be involved between DR and DQ molecules in human RA.

Collagen-induced arthritis development requires alpha beta T cells but not gamma delta T cells: studies with T cell-deficient (TCR mutant) mice

Collagen type II (CII)-induced arthritis (CIA) in mice is a model for rheumatoid arthritis (RA) in which the role of T lymphocytes remains controversial. To clarify this, we have bred a targeted gene deletion of TCR beta or delta loci into two mouse strains susceptible to CIA, the B10.Q and DBA/1 strains. The TCRbeta-/- mice lacked alphabeta T cells, which was compensated by an expansion of B cells, gammadelta T cells and NK cells. The beta-/- mice, but not control beta+/- littermates, were completely resistant to CIA. The production of anti-CII IgG antibodies was also abolished in beta-/- mice, revealing a strict alphabeta T cell dependency. In contrast, beta-/- mice produced reduced, but significant, anti-CII IgM titers after immunization with either CII or ovalbumin, indicating a multispecificity for these alphabeta T cell-independent IgM antibodies. The TCRdelta-/- mice lacked gammadelta T cells but had no other significant changes in lymphocyte or monocyte subsets. The cytokine response (IL-2, IL-4, IL-10 and IFN-gamma) in delta-/- mice, quantified by flow cytometry staining of mitogen-stimulated lymphocytes, was indistinguishable from normal mice. Likewise, no statistically significant differences were observed in CIA between mice lacking gammadelta T cells and control littermates, considering arthritis incidence, day of disease onset, maximum arthritic score, anti-CII IgG titers and disease course. We conclude that alphabeta T cells are necessary for CIA development and for an IgG response towards CII, whereas gammadelta T cells are neither necessary nor sufficient for development of CIA.

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.

Staphylococcal enterotoxin B induces arthritis in female DBA/1 mice but fails to induce activation of type II collagen-reactive lymphocytes

It has been proposed that superantigens are involved in the pathogenesis of autoimmune diseases. To test the possibility of superantigens inducing arthritis in naive mice, V beta 8-reactive superantigen staphylococcal enterotoxin B (SEB) was injected into naive mice. We used female DBA/1 mice, because they were susceptible to collagen-induced arthritis (CIA), in which the pathogenic T cells were supposed to preferentially use limited V betas of T cell receptors including V beta 8. Mild monoarthritis developed in uninjected hindlimbs of mice administered with SEB in higher frequency (an average incidence of 24%) than the control phosphate-buffered saline-injected mice (4.2%). Autoimmune responses in mice administered with SEB were compared with those in mice developing CIA. However, activation of type II collagen (IIC)-reactive T cells was not detected in SEB-injected mice. Production of autoantibodies, anti-IIC antibody and rheumatoid factor was also undetected. Although exact mechanisms of pathogenesis of this arthritis remain to be known, V beta 8+ T cells were activated for a long period and the unresponsiveness of V beta 8+ T cells was not detected in this strain. From these results, we discuss the pathogenesis of arthritis induced by SEB and the possibility that superantigen may play a role in the induction of autoimmune diseases.

Organ-specific disease provoked by systemic autoimmunity

Rheumatoid arthritis (RA) is a chronic joint disease characterized by leukocyte invasion and synoviocyte activation followed by cartilage and bone destruction. Its etiology and pathogenesis are poorly understood. We describe a spontaneous mouse model of this syndrome, generated fortuitously by crossing a T cell receptor (TCR) transgenic line with the NOD strain. All offspring develop a joint disease highly reminiscent of RA in man. The trigger for the murine disorder is chance recognition of a NOD-derived major histocompatibility complex (MHC) class II molecule by the transgenic TCR; progression to arthritis involves CD4+ T, B, and probably myeloid cells. Thus, a joint-specific disease need not arise from response to a joint-specific antigen but can be precipitated by a breakdown in general mechanisms of self-tolerance resulting in systemic self-reactivity. We suggest that human RA develops by an analogous mechanism.

A natural disruption of the secretory group II phospholipase A2 gene in inbred mouse strains

The synovial fluid or group II secretory phospholipase A2 (sPLA2) has been implicated as an important agent involved in a number of inflammatory processes. In an attempt to determine the role of sPLA2 in inflammation, we set out to generate sPLA2-deficient mice. During this investigation, we observed that in a number of inbred mouse strains, the sPLA2 gene was already disrupted by a frameshift mutation in exon 3. This mutation, a T insertion at position 166 from the ATG of the cDNA, terminates out of frame in exon 4, resulting in the disruption of the calcium binding domain in exon 3 and loss of both activity domains coded by exons 4 and 5. The mouse strains C57BL/6, 129/Sv, and B10.RIII were found to be homozygous for the defective sPLA2 gene, whereas outbred CD-1:SW mice had variable genotype at this locus. BALB/c, C3H/HE, DBA/1, DBA/2, NZB/BIN, and MRL lpr/lpr mice had a normal sPLA2 genotype. The sPLA2 mRNA was expressed at very high levels in the BALB/c mouse small intestine, whereas in the small intestine of the sPLA2 mutant mouse strains, sPLA2 mRNA was undetectable. In addition, PLA2 activity in acid extracts of the small intestine were approximately 40 times higher in BALB/c than in the mutant mice. Transcription of the mutant sPLA2 gene resulted in multiple transcripts due to exon skipping. None of the resulting mutant mRNAs encoded an active product. The identification of this mutation should not only help define the physiological role of sPLA2 but also has important implications in mouse inflammatory models developed by targeted mutagenesis.

Lifelong moderate running training increases the incidence and severity of osteoarthritis in the knee joint of C57BL mice

BACKGROUND

Inbred C57BL male mice express a high incidence of spontaneous osteoarthritis of the knee joint at the age of 18 months. We used this strain of mice to find out the effects of life-long, moderate running exercise on the health of articular cartilage and the incidence of osteoarthritis.

METHODS

Male mice (294) were divided into controls and runners. The runners were trained daily between 2 and 18 months of age. The speed was 13.3 m/min and the distance on a flatbelt treadmill was 1,000 m/day. The mice were sacrificed at the ages of 2, 6, 10, 14, and 18 months. The knee joints were sectioned in frontal direction and the osteoarthritic changes were graded using a conventional light microscope. The reproducibility of the grading method was tested by calculating the extended kappa-coefficient for the results of six researchers.

RESULTS

The incidence of osteoarthritis at the age of 18 months increased from 72% in controls to 88% in runners in the medial tibial condyles (P < 0.05), and from 80 to 96% in the lateral tibial condyles (P < 0.001). The incidence of the most severe osteoarthritic changes rose from 16% in controls to 36% in runners in the medial tibial condyles, and from 4 to 36% in the lateral tibial condyles.

CONCLUSION

According to our results, the moderate, long-lasting running exercise accelerates the development of osteoarthritis in the knee joints of C57BL mice.

Collagen-induced arthritis in T cell receptor V beta congenic B10.Q mice

B10.Q (H-2q) mice congenic for the truncated T cell receptor (TCR) V beta a and V beta c haplotypes were derived to examine the influence of TCR V beta genomic deletions in murine collagen-induced arthritis (CIA). Previous studies using gene complementation and segregation analyses suggested that in SWR (H-2q) mice, possession of the V beta a gene deletion results in CIA resistance. However, other studies have suggested alternative hypotheses. Thus, analysis of TCR V beta congenic mice allows for direct examination of V beta genotypes in CIA control. After immunization with bovine type II collagen, B10.Q-V beta a mice showed no difference in arthritis susceptibility, onset, or severity when compared with prototype B10.Q mice. In contrast, B10.Q-V beta c mice, which lack the V beta 6, 15, 17, and 19 families in addition to the V beta a deletion, were highly resistant to CIA. In vivo depletion of V beta 6+ T cells in B10.Q-V beta a mice significantly delayed arthritis onset suggesting that, among those V beta genes present in V beta a but absent in V beta c, V beta 6+ T cells contribute to arthritogenesis. Our findings show that, in B10.Q-V beta congenic mice, while the V beta a genotype does not prevent CIA, the highly truncated V beta c genotype renders B10.Q mice resistant to CIA. Thus, deletions within the V beta TCR genome can indeed influence CIA and suggests that the TCR repertoire displays only marginal flexibility in response to arthritogenic stimuli.

IgG glycosylation in autoimmune-prone strains of mice

The relationship between increased levels of IgG oligosaccharide chains lacking galactose (G0) and the development of rheumatoid arthritis is unclear. In order to further our understanding of the observed correlation between raised serum G0 and arthritis, we have studied G0 levels in arthritis-prone and non-susceptible (i.e. non-arthritis-prone) mice and the effects on G0 of mycobacterial antigens, which have been postulated to play a role in the early events leading to the development of arthritis. We have shown that different age-matched mouse strains have characteristic 'resting' levels of G0 which (in six out of seven strains of mice) increase with age. We have also shown that these increases can be enhanced by immunization of arthritis-prone strains of mice with an adjuvant containing mycobacteria (Freund's complete adjuvant (FCA)), suggesting that deflects in the ability to regulate these G0 changes may be related to susceptibility to arthritis.