Characterization of a novel and spontaneous mouse model of inflammatory arthritis
- Iris A Adipue1,
- Joel T Wilcox1,
- Cody King1,
- Carolyn AY Rice1,
- Katherine M Shaum1,
- Cory M Suard1,
- Elri ten Brink1,
- Stephen D Miller†2 and
- Eileen J McMahon†1Email author
© Adipue et al.; licensee BioMed Central Ltd. 2011
Received: 2 March 2011
Accepted: 12 July 2011
Published: 12 July 2011
Mouse models of rheumatoid arthritis (RA) have proven critical for identifying genetic and cellular mechanisms of the disease. Upon discovering mice in our breeding colony that had spontaneously developed inflamed joints reminiscent of RA, we established the novel IIJ (inherited inflamed joints) strain. The purpose of this study was to characterize the histopathological, clinical, genetic and immunological properties of the disease.
To begin the IIJ strain, an arthritic male mouse was crossed with SJL/J females. Inheritance of the phenotype was then tracked by intercrossing, backcrossing and outcrossing to other inbred strains. The histopathology of the joints and extraarticular organ systems was examined. Serum cytokines and immunoglobulins (Igs) were measured by ELISA and cytometric bead array. Transfer experiments tested whether disease could be mediated by serum alone. Finally, the cellular joint infiltrate and the composition of secondary lymphoid organs were examined by immunohistochemistry and flow cytometry.
After nine generations of intercrossing, the total incidence of arthritis was 33% (304 of 932 mice), with females being affected more than males (38% vs. 28%; P < 0.001). Swelling, most notably in the large distal joints, typically became evident at an early age (mean age of 52 days). In addition to the joint pathology, which included bone and cartilage erosion, synovial hyperproliferation and a robust cellular infiltration of mostly Gr-1+ neutrophils, there was also evidence of systemic inflammation. IL-6 was elevated in the sera of recently arthritic mice, and extraarticular inflammation was observed histologically in multiple organs. Total serum Ig and IgG1 levels were significantly elevated in arthritic mice, and autoantibodies such as rheumatoid factor and Ig reactive to joint components (collagen type II and joint homogenate) were also detected. Nevertheless, serum failed to transfer disease. A high percentage of double-negative (CD4-CD8-) CD3+ TCRα/β+ T cells in the lymphoid organs of arthritic IIJ mice suggested significant disruption in the T-cell compartment.
Overall, these data identify the IIJ strain as a new murine model of inflammatory, possibly autoimmune, arthritis. The IIJ strain is similar, both histologically and serologically, to RA and other murine models of autoimmune arthritis. It may prove particularly useful for understanding the female bias in autoimmune diseases.
Rheumatoid arthritis (RA) is a systemic and chronic disease. The most characteristic symptoms are severe synovial inflammation, cartilage and/or bone destruction and bony nodule formation in the diarthrodial joints, but extraarticular manifestations are also prevalent and include pericarditis and vasculitis as well as pulmonary complications such as pleuritis and pulmonary fibrosis [1–3]. The worldwide prevalence of RA among adults is estimated to be between 0.3% and 2%, with more women affected than men [4–6]. Although the prevalence of RA does increase with age, the majority of adults with RA are diagnosed between the ages of 30 and 50 years. A juvenile form of disease, with onset before 16 years of age, does exist, and while differences in classification and diagnosis make estimates difficult, the prevalence of RA among children likely ranges between 0.007% and 0.4% worldwide . RA is a debilitating disease associated with increased mortality and a decrease in survival by 3 to 10 years . It is also a major cause of inability to work, with a little over one-third of RA patients reporting an inability to work within five years of diagnosis .
Unlike many other forms of arthritis, RA is autoimmune in nature. Autoantibodies are found in the vast majority of patients. While B-cell autoantigens include collagen type II, citrullinated proteins and glucose-6-phosphate isomerase, the classic example is rheumatoid factor (RF), an autoantibody specific for the Fc portion of immunoglobulin G (IgG) . RF is found in 70% to 80% of adult RA patients and has been used as a diagnostic indicator for the past five decades . While B cells have been successful targets for therapy in at least a subset of patients [10, 12, 13], the focus has shifted more toward T cells as the primary lymphocyte driving disease [11, 14–17]. Drugs that limit T-cell activation help to ameliorate disease, and many of the genes associated with an increased susceptibility to RA are involved in T-cell function [11, 18]. Though RA was once described as "Th1-driven," evidence is mounting that Th17 cells are the primary T-helper cell subset promoting disease [16, 17, 19].
While lymphocytes account for the autoreactivity in RA, the inflammation itself results from a plethora of cytokines that recruit peripheral immune cells, promote synovial proliferation and induce osteoclast maturation to increase bone resorption . Many proinflammatory cytokines, such as TNF-α and IL-6, have been the targets of therapeutic biologic drugs that successfully limit inflammation . Secreted primarily by activated macrophages, TNF-α is believed to have a particularly central role, as it induces the release of many other cytokines and chemokines and activates many of the cell types present in the inflamed synovium, including polymorphonuclear cells, endothelial cells, chondrocytes and osteoclasts . IL-6 is similarly known for its pleiotropic functions . It is the primary cytokine responsible for the acute phase response observed in RA, contributing to systemic inflammation , and strongly influences lymphocyte maturation, promoting both plasma cell and Th17 differentiation [23, 24].
Mouse models of RA have been critical for understanding the underlying genetic and cellular mechanisms of pathogenesis [25–27]. Both induced and spontaneous models have been developed. In the most common experimentally induced models, injection of adjuvant and various joint matrix components, such as collagen type II or proteoglycan aggrecan, causes autoimmune arthritis in susceptible inbred mouse strains [28, 29]. Spontaneous models can be subdivided by their mode of origination: (1) development of autoimmune-prone strains by selective mixing of previously existing inbred strains (for example, the MRL/lpr strain [30, 31]), (2) targeted gene manipulation (for example, T-cell receptor (TCR)-transgenic K/BxN model , TNF-α overexpression models , IL-1Ra-knockout  and gp130Y759F-induced mutant ) and (3) identification of spontaneous mutants from breeding colonies (for example, SKG mice with a point mutation in Zap-70 ). While these models replicate many aspects of human RA, none of them mimic the disease completely. In fact, it is unlikely that RA itself is a single disease, but instead may be subdivided into various subsets (for example, RF-seropositive and RF-seronegative) with distinct etiologies. Therefore, each mouse model is potentially important not only for reinforcing the existence of common or even universal mechanisms of disease but also for revealing unique aspects not yet reflected in the other models.
In this report, we describe a new mouse line that spontaneously develops chronic inflammatory arthritis most evident in the large distal joints. Called the IIJ (inherited inflamed joints) strain, it was derived from arthritic (AR) animals discovered in a breeding colony at Northwestern University. One male AR mouse of predominantly SJL/J background was used to begin the line, and, after 13 generations of inbreeding, the phenotype remains stable. RA incidence in the entire colony is approximately 33%, with females developing arthritis more often than males. Joint histology confirmed cartilage and bone erosion, synovial proliferation and robust leukocyte infiltration. In addition to the inheritance pattern and histopathology, we describe the clinical and immunological properties of disease.
Materials and methods
The IIJ strain was established from AR mice that appeared in the 5B6 transgenic mouse-breeding colony at Northwestern University. 5B6 mice were initially developed at Harvard University . While generated on the FVB background, they were backcrossed for five generations to SJL/J before being shipped to Northwestern University, where they were then crossed with Thy1.1 congenic SJL/J mice (backcrossed more than 12 generations to SJL/J). A subset of mice with inflamed joints was discovered after several months. One AR male mouse that was negative for the 5B6 TCR transgene was crossed with SJL/J female mice to generate the F1 generation of the IIJ line. Since then, the line has been maintained with sibling-sibling mating. SJL/J mice (six to nine weeks old) were purchased from Harlan Laboratories (Indianapolis, IN, USA) or Taconic Farms (Hudson, NY, USA) and used either directly in experiments or as breeders. For inbred strain crosses, five- to six-week-old female BALB/c, C3H, DBA1 and FVB mice were purchased from Harlan Laboratories.
Mice were housed in a specific pathogen-free (SPF) facility at Northwestern University or in a HEPA-filtered SuperMouse 750 ventilated rack and caging system (Lab Products, Inc., Seaford, DE, USA) at Westmont College. Antibiotic-treated mice were fed a modified Laboratory Rodent Diet 5001 supplemented with 0.06% amoxicillin, 0.0138% metronidazole, 0.0037% bismuth and 0.0004% omeprazole (Newco Distributors, Rancho Cucamonga, CA, USA) for eight weeks. All protocols performed were approved by the Institutional Animal Care and Use Committee of Northwestern University and the Institutional Review Board of Westmont College.
Evaluation of clinical disease
Clinical disease was evaluated using a subjective scoring method similar to previous published methods [34, 38] with minor modifications. On a weekly basis, each paw was assigned a score from 0 to 4 (0 = no disease; 1 = minor, localized swelling; 2 = moderate swelling involving majority of paw; 3 = major swelling with paws two to three times normal size; and 4 = deformity in large or small joints of paw). Scores from one reading were added together for the cumulative clinical score. Mice were considered AR when they maintained a score ≥ 2 for one paw for two consecutive readings. Disease onset was considered to be the first day that swelling was evident (score ≥ 1). For a subset of animals, disease was also tracked weekly by measuring ankle thickness with calipers. For each mouse, values for all four paws were added together to calculate the cumulative ankle thickness. At the time of joint scoring, the presence of other clinical symptoms such as evidence of colitis was also noted.
Histopathology and immunocytochemistry
Joints were prepared for H & E staining according to previously published work . Briefly, mice were killed, and their paws were removed, fixed in 10% formalin, decalcified and submerged again in 10% formalin until processed for paraffin embedding. Tissue processing, cutting of paraffin sections and H & E staining were performed at AML Laboratories, Inc. (Rosedale, MD, USA). In addition, live mice (five AR and two NAR IIJ mice) were sent to the Comparative Pathology Laboratory at the University of California, Davis. An animal necropsy was performed, and numerous organs and tissues were harvested for analysis. Sections were examined and scored for inflammation in a blinded fashion by a trained veterinary histopathologist.
Frozen tissue sections were prepared and stained according to previously published methods . Serial frozen sections were cut and stained using biotinylated primary antibodies or isotype controls (eBioscience, San Diego, CA, USA) and the Tyramide Signal Amplification Kit (PerkinElmer, Waltham, MA, USA). They were analyzed using a Leica DM5000 B fluorescence microscope (Leica Microsystems, Buffalo Grove, IL, USA and SPOT Advanced Software (SPOT Imaging Solutions, Sterling Heights, MI, USA).
Mice were given a lethal dose of Euthanasia 5 solution (Henry Schein, Inc., Port Washington, NY, USA), and blood was collected via cardiac puncture. Blood was allowed to clot for a minimum of seven minutes at room temperature. It was spun for 10 minutes at 10,000 rpm in a tabletop microcentrifuge. The serum was removed and immediately frozen at -80°C until used.
The mouse inflammation cytometric bead array (CBA) assay was performed according to the manufacturer's instructions (BD Biosciences, San Jose, CA, USA). Serum was diluted 1:4 with assay diluent. The samples were analyzed immediately using a FACSAria III cell sorter and FACSDiva software (BD Biosciences). The standard curves were made and calculations were performed using the BD Biosciences CBA software. Serum IL-17A levels were measured by ELISA using the manufacturer's protocol (eBioscience). Serum was diluted 1:5.
Cell isolation and flow cytometry
Cells from lymphoid organs (spleens and lymph nodes) were isolated as previously described . The leg-draining lymph nodes used included the axillary, brachial, inguinal and popliteal. The joints were removed and placed into a Petri dish containing 3 mL of sterile DMEM. After mincing the joints with a sterile razor blade, 1 mg/mL type II collagenase (Worthington Biochemical Corp., Lakewood, NJ, USA) and 100 μg/mL DNAse (Sigma-Aldrich, St Louis, MO, USA) were added. After incubating the samples for one hour at 37°C, a rubber plunger was used to push the tissue through a sterile metal mesh in a Petri dish to generate a single-cell suspension. The mesh was washed twice with 5 mL of Hanks' buffered saline solution (HBSS). Samples were centrifuged for five minutes at 500 × g at 4°C, resuspended in 5 mL of HBSS and strained through a 70-μm cell strainer. Live cells were counted in a hemocytometer using trypan blue exclusion.
Staining for flow cytometry was performed in 96-well U-bottomed plates. Cells (0.5 to 1 × 106 cells/well) were resuspended in 2% FCS in PBS, and a 1:100 dilution of anti-mouse CD16/32 (eBioscience) was added. Cells were incubated on ice for 15 minutes before antibody mixtures were added for staining. All antibodies were purchased from eBioscience (anti-mouse CD3ε-PE-Cy7, CD3ε-APC, CD4-FITC, CD8-APC, CD11b-PE, CD45-FITC, B220-APC, Gr-1-Pacific Blue, TCRβ-PE, Vβ6-FITC and Foxp3-APC), and their concentrations were individually optimized in comparison to an isotype control. The anti-mouse DX5-PE antibody was purchased from BD Biosciences. Cells were then incubated for 30 minutes on ice and washed three times with PBS. Cells were resuspended in PBS and analyzed immediately or fixed in 1% paraformaldehyde, stored overnight at 4°C and analyzed the next day. Intracellular Foxp3 staining was done using the Foxp3 Staining Buffer Set (eBioscience) according to the manufacturer's instructions. Data were collected on a FACSAria flow cytometer and analyzed using FACSDiva software (BD Biosciences) or FlowJo software (TreeStar, Inc., Ashland, OR, USA).
Serum immunoglobulin ELISA
Total serum Ig, IgG1 and IgG2a levels were determined by performing a sandwich ELISA based on the manufacturer's published protocols (eBioscience). Plates were coated with 2 μg/mL of polyclonal goat anti-mouse Ig (553998; BD Biosciences) diluted in PBS. Serum was diluted in 5% FCS/PBS at 1:200,000 for total Ig, 1:50,000 for IgG1 and 1:40,000 for IgG2b. The standards were serial dilutions of mouse reference serum (Bethyl Laboratories, Montgomery, TX, USA). Antibodies were detected using 0.5 μg/mL biotinylated detection antibodies (total Ig, 553999; IgG1, 553441; and IgG2a, 553388; BD Biosciences), a 1:1,000 dilution of avidin-horseradish peroxidase (eBioscience) and Super AquaBlue ELISA Substrate (eBioscience). Concentrations were determined using the standard curve and dilution factor. Duplicates were averaged.
Total RF (that is, autoantibodies to IgG, IgM or IgA isotypes specific for the Fc portion of IgG) was measured using a commercial kit following the manufacturer's instructions (Alpha Diagnostic International Inc., San Antonio, TX, USA). Serum was diluted 1:250. Each sample was run in duplicate and averaged. To normalize between runs, the results are reported as percentages of the manufacturer-provided positive controls [(Average Abssample/Average Abs+control) × 100].
Other antigen-specific total Ig ELISAs were performed by first coating high-binding 96-well plates with either 20 μg/mL collagen type II (Sigma) or 15 to 20 μg/mL joint homogenate (kindly provided by Dr Alison Finnegan). After the wells were washed, serum was diluted 1:5 in PBS and added to wells in duplicate. Reactivity was detected using the biotinylated anti-mouse Ig, avidin-horseradish peroxidase and Super AquaBlue ELISA Substrate mentioned above. Duplicates were averaged, and the results are reported as relative absorbance.
Serum was pooled and pushed through a 0.2-μm syringe filter to remove any contaminating cells. For each SJL/J recipient, 300 μL of serum were injected intraperitoneally. Mice were tracked for disease for a minimum of seven weeks. Mice were scored every two days for the first four weeks and then scored twice weekly thereafter.
Comparisons of disease incidence between groups were analyzed using Fisher's exact test. Means in the Ig ELISAs, cytokine assays and T-cell subset analyses were compared using an unpaired t-test. The mean percentages of various cell types in joint or lymphoid organ samples were compared by two-way analysis of variance.
Occurrence of arthritis in a mouse-breeding colony and the establishment of the IIJ strain
H & E staining of sagittal sections of paws revealed histopathology consistent with inflammatory arthritis (Figures 1E, 1F, 1G, 1H, 1I, 1J). Both cartilage and bone erosion was observed, along with notable inflammatory infiltration, synovial proliferation and pannus formation. A veterinary histopathologist examined the sections from five AR IIJ mice (ranging from 98 to 277 days old) and two NAR littermates in a blinded fashion. While no inflammation was reported in the NAR mice, it was evident in multiple joints of the AR mice, including all the joints in the paws (phalangeal, metacarpal/tarsal and carpal/tarsal), the stifle (or "knee") joint and, occasionally, the vertebral joints. The cellular infiltrate was largely described as neutrophilic and histocytic and was severe enough to cause abscess formation in some of the most severely AR mice. Myeloid hyperplasia was also observed in the bone marrow.
Non-Mendelian inheritance of the arthritis phenotype and influence of genetic background
Combined incidence of arthritis in first nine generations of IIJ straina
Phenotype of parentsb
Male × Female, n (%)
AR × AR
159 of 463 (34%)
84 of 207 (41%)
75 of 256 (29%)
AR × NAR
77 of 273 (28%)
41 of 120 (34%)
36 of 153 (24%)
NAR × AR
39 of 99 (39%)
22 of 53 (42%)
17 of 46 (37%)
NAR × NAR
29 of 97 (30%)
15 of 44 (34%)
14 of 53 (26%)
Overall, n (%)
304 of 932 (33%)
162 of 424 (38%)
142 of 508 (28%)
Multiple attempts were made to backcross AR IIJ mice further to SJL/J to determine whether the arthritis incidence could be increased if the contaminating FVB genes were removed (Figure 2B). Male and female AR mice from the F4 or later generations were separately crossed with SJL/J mice, and the progeny were tracked for disease. After consistently backcrossing or backcrossing followed by intercrossing, the incidence only decreased. It also decreased regardless of whether female or male AR IIJ mice were used for backcrossing. Therefore, FVB alleles likely contributed to the AR phenotype.
Low incidence of disease when arthritic IIJ mice were crossed with four other inbred strainsa
AR × BALB/c
0 of 13
2 of 25
0 of 18
0 of 19
AR × FVB
0 of 13
0 of 23
1 of 22
2 of 38
AR × DBA1
0 of 20
0 of 21
0 of 13
1 of 20
AR × C3H
1 of 16
0 of 24
0 of 15
0 of 25
Progression of clinical disease varied between arthritic IIJ mice
Typical signatures of local and systemic inflammation in arthritic IIJ mice
Though serum Ig and autoantibodies were elevated in arthritic IIJ mice, serum failed to transfer disease
Therefore, sera from AR mice were adoptively transferred into SJL/J mice to determine whether serum alone could transfer disease. Three hundred microliters of filtered and pooled sera from either AR or NAR mice were injected intraperitoneally into SJL/J mice, which were then tracked for disease. The mice were followed for over two months, but no mice (zero of six with NAR serum injected into SJL/J mice and zero of seven with AR serum into SJL/J mice) developed arthritis.
A large proportion of CD4-CD8-(double-negative) T cells in the lymph nodes of arthritic IIJ mice
Nevertheless, α/β T cell subpopulations were significantly altered. The majority of the T cells in the lymph nodes of AR mice were, surprisingly, CD4-CD8-, or double-negative (DN) (Figure 8A), a population extremely rare in normal mice. While the number of DN T cells was expanded in young and old AR mice, the number of CD4+ T cells was decreased, showing a loss of this subset specifically (Figure 8F). A similar, though less pronounced trend was also observed in the spleen (data not shown). To determine whether the decrease in CD4+ T cells resulted from a loss of T-regulatory cells (Tregs), CD25+Foxp3+ cells were examined (Figure 8E). AR mice in fact had more Tregs in their lymph nodes than their NAR littermates, suggesting an expansion of this population during chronic joint inflammation. This increase was seen in both 6- to 8-week-old and 16- to 17-week-old mice, and similar results were found when identifying Tregs on the basis of CD25 and GITR expression (data not shown). While the functionality of the Tregs is not known, the joint inflammation does not appear to be a result of a decline in this regulatory population.
The DN T cells were examined further for signs of activation and for additional lineage markers that might suggest their origins. To determine their activation and/or memory phenotype, CD69 upregulation (a reflection of recent activation) and CD45RB downregulation (a reflection of previous activation) were compared between T-cell subsets in AR mice (Figure 8B). While 25% to 45% of CD4+ and CD8+ T cells showed robust signs of activation, activation was low in the DN subset, calling into question whether the DN cells have a direct pathogenic role. Finally, since natural killer (NK) T cells lack CD4 and CD8 expression but are positive for the α/β TCR, the DN cells were examined for NK cell markers. More than 85% of the DN T cells lacked the pan-NK cell marker DX5 (Figure 8G), and therefore their origin is still under investigation.
Typhlocolitis and other extraarticular manifestations of inflammation in IIJ mice
Extraarticular inflammation in arthritic IIJ mice
Incidence of inflammatory bowel disease in IIJ straina
Arthritis and diarrhea
To screen for possible GI pathogens, eight IIJ mice (five AR and three NAR) and four sentinel SJL/J mice from the colony were sent to the Comparative Pathology Laboratory at the University of California, Davis. All the IIJ mice, regardless of arthritis status, tested positive for a Helicobacter sp: six had H. rodentium and two had a Helicobacter sp. of undetermined type. They did not test positive for other GI tract pathogens, including pinworm. None of the SJL/J sentinels tested positive for Helicobacter spp. Believed to be a part of the normal intestinal flora, H. rodentium was originally identified in 1997, when it was isolated from the intestines of asymptomatic laboratory mice . It was later found to cause mild to moderate colitis in IL-10-deficient mice  and severe IBD only when the mice were coinfected with other, more pathogenic Helicobacter spp. [45–47]. Treating IIJ mice with food tablets containing a four-antibiotic drug cocktail (0.06% amoxicillin, 0.0138% metronidazole, 0.0037% bismuth and 0.0004% omeprazole) resolved their diarrhea within three weeks (Figure 9E), and after eight weeks of treatment, the IIJ mice tested negative for all Helicobacter spp. (data not shown). While IIJ mice with active diarrhea had an elevated colon:body weight ratio, indicating inflammation, antibiotic treatment caused the ratio to normalize and become similar to the ratios of IIJ mice that had never had diarrhea (Figure 9F). While this finding does not prove that Helicobacter spp. infection specifically induced typhlocolitis in the IIJ mice, the correlation suggests that it might.
To determine whether the IIJ mice had evidence of inflammation in tissues other than the joints and the colon, various organs were harvested, stained with H & E and examined in a blinded fashion by a trained veterinary histopathologist. In addition to typhlocolitis, other extraarticular inflammation was observed in all of the AR mice, though the organs involved and the severity of inflammation were inconsistent (Table 3). Inflammation was noted in the lungs of three of five AR animals (two with mild to minimal inflammation and one with focal pleuritis). A similar number also showed inflammation in the liver and/or kidneys. Inflammation severity ranged from minimal to moderate, although one AR IIJ mouse had pronounced moderate interstitial nephritis and fibrosis in the kidneys. Finally, severe vasculitis was seen in the vertebrae of the oldest IIJ arthritis mouse (data not shown). The NAR IIJ mice showed no signs of inflammation in any organ (Table 3). Therefore, similarly to humans with RA, the AR IIJ mice had extraarticular manifestations of disease, indicating pathology of a systemic nature.
In this report, we describe a new strain of mouse, which we have named the IIJ strain, that spontaneously develops chronic inflammatory, and possibly autoimmune, arthritis that shares many similarities with human RA and other mouse models of arthritis. Though visible swelling was most evident in the large distal joints of IIJ mice, histological hallmarks of arthritis, including bone and cartilage erosion, invasive synovial hyperproliferation and immune cell infiltration were observed in all joints of the hindlimbs and forelimbs (Figure 1). Overall, the histopathology was similar to that described in previously published mouse models of autoimmune arthritis [32, 34–36]. In addition, the predominantly neutrophilic and lymphocytic infiltration into the inflamed IIJ joints (Figure 4) parallels the high number of neutrophils and T cells present in the inflamed synovial fluid of RA patients [48, 49]. Also similar to RA, inflammation was not restricted solely to the joints of IIJ mice, but was systemic in nature. Elevation of serum proinflammatory cytokines (Figure 5) and histological signs of inflammation, ranging from mild to severe, were observed in various organs (Table 3). Extraarticular manifestations of disease have also been noted in IL-1R antagonist-deficient  and SKG mice . Finally, the IIJ mice also share serological similarities with RA and other mouse models. Compared to NAR littermates, AR IIJ mice had mildly elevated serum Ig, which is due, at least partially, to elevated IgG1, a classic Th2-induced isotype (Figure 7). RA patients also have slightly increased serum Ig levels , and researchers who have studied several spontaneous mouse models of arthritis, including the K/BxN , gp130Y759F  and IL-1R antagonist deficiency models , have reported increases in IgG1 specifically. Importantly, autoantibodies were also detected in our study, as many IIJ mice were positive for RF and antibodies specific to joint components (Figure 7).
The arthritis incidence in IIJ mice also displayed the sex bias common to many complex autoimmune diseases, such as RA, multiple sclerosis and systemic lupus erythematosus (SLE) . RA incidence was higher in females than in males (38% vs. 28%; P < 0.001) (Table 1), though ultimately clinical severity and mean day of onset did not differ significantly. The sex bias appeared to be specific for the arthritis phenotype, since the incidence of typhlocolitis was similar between male and female IIJ mice (Table 4). As most models reach 100% incidence in both sexes, no other spontaneous mouse model of arthritis has found such a sex bias, although researchers who have studied both the SKG  and gp130Y759F models  have noted more severe arthritis in females. A female bias in incidence was observed in collagen-induced arthritis in humanized HLA-DR4-transgenic mice  and was attributed to both hyperactive B cells and HLA-DR4-restricted antigen presentation in female mice and increased numbers of Tregs and B-regulatory cells in male mice . The reason for the sex bias in arthritis incidence in IIJ mice remains unknown.
It remains unclear whether arthritis in the IIJ mice is truly autoimmune. The similarities to RA and other mouse models of autoimmune arthritis outlined above would strongly argue in favor of this scenario. The relative expansion of the B-cell population, elevated serum Ig and presence of autoantibodies are also strongly suggestive that this is true. Nevertheless, all AR IIJ mice did not have levels of serum autoantibodies that exceeded those of NAR littermates (Figure 7), and the increase might simply be a side effect of chronic inflammation. Some murine models of arthritis have shown elevated levels of Ig and autoantibodies, but the arthritis was lymphocyte-independent. For example, joint inflammation still occurs in the N-ethyl-N-nitrosourea-induced mutants Ali5 and Ali18, even when crossed to Rag1-/- backgrounds [55, 56]. Finally, transfer of sera from AR IIJ mice failed to induce disease in SJL/J hosts, suggesting that antibodies alone are not sufficient to cause disease. It is possible that not enough serum was transferred and/or that it was not transferred by the appropriate method (for example, intravenous rather than intraperitoneal injection). Nevertheless, the same transfer protocol successfully transfers disease in antibody-dependent arthritis models such as the K/BxN model .
The appearance of a high percentage of DN T cells in the peripheral lymphoid organs does indicate that the T-cell compartment in the AR IIJ mice is significantly disrupted (Figure 8). DN T cells are characteristic of SLE in humans as well as in murine models of SLE, such as the MRL/lpr mouse, a strain that also gets arthritis [58, 59]. Since the peripheral DN T cells in MRL/lpr mice are B220+  and those in IIJ mice are B220- (data not shown), it is unlikely that these mouse populations are identical. The origin of the DN T cells in IIJ mice remains unclear. It does not appear to caused by an expansion of NK T cells, as DN T cells lack the pan-NK cell marker DX5 (Figure 8G), and their high expression of CD3 and the TCR suggests that they are mature. The fact that CD4+ T cells decrease in number as DN T cells increase does suggest that the DN T cells might be CD4+ cells that have downregulated CD4. While downregulation of TCR coreceptors by viruses have been well documented , it has also been proposed as a natural mechanism of peripheral tolerance [61, 62]. Autoreactive T-cell clones can downregulate CD4 upon long-term stimulation in vitro , and self-specific TCR-transgenic mice can downregulate coreceptors to control autoimmunity . Nevertheless, the fact that the IIJ DN T cells largely lack an activated and/or memory phenotype (Figure 8B) argues against coreceptor downregulation due to chronic activation. The existence of a DN T-cell-regulatory population to control self-reactivity in humans and mice has been proposed [65, 66], and the expanded DN T-cell population in mice bearing the homozygous Faslpr or FasLgld mutations has been found to have regulatory properties . The ontogeny and functional ability of the IIJ DN T cells are currently under investigation.
The gene mutations and background alleles that might cause or modify the arthritis phenotype in the IIJ strain have yet to be identified. It is unlikely that the phenotype is related to either the 5B6 TCR transgenes or the Thy1.1 allele that were present in the line from which the IIJ strain was derived. A low percentage of peripheral blood T cells in the IIJ mice expressed Vβ6, the variable region used in the 5B6-transgenic TCRβ chain, and none of the IIJ mice (> 1,000 animals) have shown clinical or histological signs of EAE (for example, loss of muscle tonicity, hindlimb paralysis or inflammation in the central nervous system). Also, the arthritis occurs regardless of Thy1 status, as we have identified AR and NAR IIJ mice that are Thy1.1+Thy1.2-, Thy1.1-Thy1.2+ and Thy1.1+Thy1.2+ (data not shown). Both SJL/J and FVB background alleles likely contribute to arthritis development. The strain from which the IIJ mice were derived was predominantly SJL/J in background. Statistically, however, with a minimum of only six generations of backcrossing to SJL/J after generating the 5B6-transgenic mice on the FVB background, a small percentage of FVB alleles must be present in the IIJ strain. The fact that multiple attempts to backcross the AR IIJ mice further to SJL/J only decreased arthritis incidence also argues in favor of FVB-influencing alleles. Since backcrossing AR IIJ mice to FVB inbred mice also resulted in low AR incidence, SJL/J alleles must also be important.
The pedigree does indicate that the arthritis phenotype is a complex, non-Mendelian trait and, together with the female bias in incidence, is clearly sex-influenced. The incidence of 32% in the F1 generation after crossing the "founder" AR male with the SJL/J females argues for a dominant phenotype (Figure 2). Nevertheless, the fact that crossing two NAR IIJ mice yielded a similar incidence of arthritis suggests that the trait is also incompletely penetrant, since the NAR parents must harbor the disease-promoting alleles but do not display the trait. While it is also possible that a combination of multiple alleles must be inherited to develop the disease, the relative consistency of incidence regardless of the phenotype of the parents argues against simple segregation of multiple alleles. Furthermore, at the time of the writing of this article, the IIJ mice had been intercrossed for 14 generations and the overall incidence had not increased, despite the fact that most loci should be fixed after that much inbreeding. Therefore, while genes are undoubtedly influencing the phenotype, other factors, such as microbial stimulation of the innate immune system, or even stochastic events, such as the formation of the T- and B-cell repertoires through random rearrangements in the TCR and Ig genes, might also be involved.
Some bacteria, such as Borrelia burgdorferi and Staphylococcus aureus, or microbial products such as zymosan, a crude fungal extract of β-glycans, can induce arthritis in susceptible mouse strains [25–27]. While it cannot be completely ruled out, there is little evidence that the arthritis in the IIJ mice is caused purely by an infectious agent. The mice are maintained in a barrier facility, and arthritis incidence does not cluster by cage. Also, SJL/J mice housed in the same cage as AR IIJ mice never develop arthritis, and SJL/J sentinel mice that receive portions of bedding from over 20 cages of IIJ mice housed on the same rack also never develop arthritis. The IIJ breeding colony was transported between institutions (from Northwestern University to Westmont College) in the F3 and F4 generation, but arthritis incidence did not significantly change after the move. No viral, bacterial or parasitic pathogen has been consistently found in the IIJ strain, aside from the mice with H. rodentium infection, and the AR IIJ mice that have been treated with antibiotics to clear the Helicobacter sp. have remained AR. Nevertheless, even spontaneous arthritis can be highly influenced by microbial flora. For example, the SKG strain has a high incidence of arthritis in conventional caging conditions and a very low incidence of arthritis in SPF conditions, unless they are injected with zymosan . It is not known whether a similar innate immune system would trigger an increased incidence of arthritis in the IIJ mice.
While H. rodentium does not appear to cause the arthritis phenotype, it seems likely that it is responsible for or at least contributes to typhlocolitis, since H. rodentium infection is prevalent in both AR and NAR IIJ mice and treatment with antibiotics cleared the Helicobacter sp. and resolved the diarrhea and gut inflammation (Figure 9). As mentioned previously, H. rodentium was identified only 13 years ago, when it was isolated from asymptomatic laboratory mice . Few studies have since investigated its pathogenicity. In experimental monoinfections, H. rodentium did not cause cecal lesions or significantly change gut gene expression in either immunocompetent A/JCr mice or SCID (severe combined immunodeficiency) mice, while, in parallel experiments, a related species (H. hepaticus) did . Several studies have found that H. rodentium exacerbates gastrointestinal inflammation when coinfected with other Helicobacter spp. [45–47], although no other Helicobacter spp. were found in the IIJ mice. If this bacterial species alone is responsible for the typhlocolitis, it might reflect a particular predisposition to proinflammatory immune responses in IIJ mice. RA as well as IBDs such as ulcerative colitis and Crohn's disease are chronic inflammatory diseases, and genome-wide association studies have identified genetic loci that increase the risk for both [69–72]. Although several case studies have been published about RA patients who developed IBD [73, 74], IBD is not considered a typical extraarticular manifestation of RA [2, 3]. In contrast, joint inflammation occurs in 20% of patients diagnosed with IBD, though it is classified as peripheral or axial spondyloarthritis [42, 43] and is typically seronegative for RF and anticyclic citrullinated peptide antibodies [75, 76].
Overall, the data presented identify the IIJ strain as a new murine model of inflammatory, possibly autoimmune, arthritis. The IIJ strain is similar, both histologically and serologically, to RA and other murine models of autoimmune arthritis. In addition, the increased incidence of arthritis in female IIJ mice makes it a potentially important model for the study of the underlying causes of the sex bias in autoimmunity. Nevertheless, notable differences do exist between the disease in IIJ mice and human RA. For example, joint swelling in RA is typically symmetric in humans [1, 77], while it is asymmetric in many of the IIJ mice (Figure 3). Also, the accumulation of DN T cells in the periphery, which is so marked in IIJ mice (Figure 8), is a hallmark of SLE, not RA . Despite these differences, the IIJ strain is a new experimental tool with which to investigate the genetic and immunological mechanisms of arthritis.
cytometric bead array
Dulbecco's modified Eagle's medium
fetal calf serum
- H & E:
hemotoxylin and eosin
Hanks' balanced salt solution
inherited inflamed joints
tumor necrosis factor α.
This work was supported in part by NIH grants NS-026543 and NS-030871 and by a generous gift from Westmont College and the Office of the Provost. We thank Dr Tibor Glant and Dr Alison Finnegan for consultation in the early studies and Dr Steven Julio and Dr Michael Waterfield for careful readings of the manuscript. Julia Morrow, Laurraine Gereige, John Meyer, Heather (Parrish) Rizzo, Kirsten Holshausen, Julie Nolte, Jenna Stephens, Eva Glover and Matt Combs all provided technical assistance. Holly Anger completed the joint immunofluorescence studies. Finally, we thank Dr Wayne Iba and his students for developing a database for our mouse breeding and clinical information.
- Grassi W, De Angelis R, Lamanna G, Cervini C: The clinical features of rheumatoid arthritis. Eur J Radiol. 1998, 27 (Suppl 1): S18-S24.View ArticlePubMedGoogle Scholar
- Turesson C, O'Fallon WM, Crowson CS, Gabriel SE, Matteson EL: Extra-articular disease manifestations in rheumatoid arthritis: incidence trends and risk factors over 46 years. Ann Rheum Dis. 2003, 62: 722-727. 10.1136/ard.62.8.722.PubMed CentralView ArticlePubMedGoogle Scholar
- Young A, Koduri G: Extra-articular manifestations and complications of rheumatoid arthritis. Best Pract Res Clin Rheumatol. 2007, 21: 907-927. 10.1016/j.berh.2007.05.007.View ArticlePubMedGoogle Scholar
- Sangha O: Epidemiology of rheumatic diseases. Rheumatology (Oxford). 2000, 39 (Suppl 2): 3-12.View ArticleGoogle Scholar
- Woolf AD, Pfleger B: Burden of major musculoskeletal conditions. Bull World Health Organ. 2003, 81: 646-656.PubMed CentralPubMedGoogle Scholar
- Helmick CG, Felson DT, Lawrence RC, Gabriel S, Hirsch R, Kwoh CK, Liang MH, Kremers HM, Mayes MD, Merkel PA, Pillemer SR, Reveille JD, Stone JH, National Arthritis Data Workgroup: Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part I. Arthritis Rheum. 2008, 58: 15-25. 10.1002/art.23177.View ArticlePubMedGoogle Scholar
- Manners PJ, Bower C: Worldwide prevalence of juvenile arthritis: why does it vary so much?. J Rheumatol. 2002, 29: 1520-1530.PubMedGoogle Scholar
- Alamanos Y, Drosos AA: Epidemiology of adult rheumatoid arthritis. Autoimmun Rev. 2005, 4: 130-136. 10.1016/j.autrev.2004.09.002.View ArticlePubMedGoogle Scholar
- Sokka T, Kautiainen H, Pincus T, Verstappen SM, Aggarwal A, Alten R, Andersone D, Badsha H, Baecklund E, Belmonte M, Craig-Müller J, da Mota LM, Dimic A, Fathi NA, Ferraccioli G, Fukuda W, Géher P, Gogus F, Hajjaj-Hassouni N, Hamoud H, Haugeberg G, Henrohn D, Horslev-Petersen K, Ionescu R, Karateew D, Kuuse R, Laurindo IM, Lazovskis J, et al: Work disability remains a major problem in rheumatoid arthritis in the 2000s: data from 32 countries in the QUEST-RA study. Arthritis Res Ther. 2010, 12: R42-PubMed CentralView ArticlePubMedGoogle Scholar
- Nandakumar KS, Holmdahl R: Antibody-induced arthritis: disease mechanisms and genes involved at the effector phase of arthritis. Arthritis Res Ther. 2006, 8: 223-10.1186/ar2089.PubMed CentralView ArticlePubMedGoogle Scholar
- Goronzy JJ, Weyand CM: Developments in the scientific understanding of rheumatoid arthritis. Arthritis Res Ther. 2009, 11: 249-10.1186/ar2758.PubMed CentralView ArticlePubMedGoogle Scholar
- van Vollenhoven RF: Treatment of rheumatoid arthritis: state of the art 2009. Nat Rev Rheumatol. 2009, 5: 531-541. 10.1038/nrrheum.2009.182.View ArticlePubMedGoogle Scholar
- Edwards JC, Cambridge G: B-cell targeting in rheumatoid arthritis and other autoimmune diseases. Nat Rev Immunol. 2006, 6: 394-403. 10.1038/nri1838.View ArticlePubMedGoogle Scholar
- Firestein GS: The T cell cometh: interplay between adaptive immunity and cytokine networks in rheumatoid arthritis. J Clin Invest. 2004, 114: 471-474.PubMed CentralView ArticlePubMedGoogle Scholar
- Skapenko A, Leipe J, Lipsky PE, Schulze-Koops H: The role of the T cell in autoimmune inflammation. Arthritis Res Ther. 2005, 7 (Suppl 2): S4-S14. 10.1186/ar1703.PubMed CentralView ArticlePubMedGoogle Scholar
- Gutcher I, Becher B: APC-derived cytokines and T cell polarization in autoimmune inflammation. J Clin Invest. 2007, 117: 1119-1127. 10.1172/JCI31720.PubMed CentralView ArticlePubMedGoogle Scholar
- Nistala K, Wedderburn LR: Th17 and regulatory T cells: rebalancing pro- and anti-inflammatory forces in autoimmune arthritis. Rheumatology (Oxford). 2009, 48: 602-606. 10.1093/rheumatology/kep028.View ArticleGoogle Scholar
- Imboden JB: The immunopathogenesis of rheumatoid arthritis. Annu Rev Pathol. 2009, 4: 417-434. 10.1146/annurev.pathol.4.110807.092254.View ArticlePubMedGoogle Scholar
- Toh ML, Miossec P: The role of T cells in rheumatoid arthritis: new subsets and new targets. Curr Opin Rheumatol. 2007, 19: 284-288. 10.1097/BOR.0b013e32805e87e0.View ArticlePubMedGoogle Scholar
- Kunz M, Ibrahim SM: Cytokines and cytokine profiles in human autoimmune diseases and animal models of autoimmunity. Mediators Inflamm. 2009, 2009: 979258-PubMed CentralView ArticlePubMedGoogle Scholar
- Brennan FM, McInnes IB: Evidence that cytokines play a role in rheumatoid arthritis. J Clin Invest. 2008, 118: 3537-3545. 10.1172/JCI36389.PubMed CentralView ArticlePubMedGoogle Scholar
- Fonseca JE, Santos MJ, Canhao H, Choy E: Interleukin-6 as a key player in systemic inflammation and joint destruction. Autoimmun Rev. 2009, 8: 538-542. 10.1016/j.autrev.2009.01.012.View ArticlePubMedGoogle Scholar
- Korn T, Bettelli E, Oukka M, Kuchroo VK: IL-17 and Th17 cells. Annu Rev Immunol. 2009, 27: 485-517. 10.1146/annurev.immunol.021908.132710.View ArticlePubMedGoogle Scholar
- Manel N, Unutmaz D, Littman DR: The differentiation of human TH-17 cells requires transforming growth factor-β and induction of the nuclear receptor RORγt. Nat Immunol. 2008, 9: 641-649. 10.1038/ni.1610.PubMed CentralView ArticlePubMedGoogle Scholar
- Di Paola R, Cuzzocrea S: Predictivity and sensitivity of animal models of arthritis. Autoimmun Rev. 2008, 8: 73-75. 10.1016/j.autrev.2008.07.029.View ArticlePubMedGoogle Scholar
- Asquith DL, Miller AM, McInnes IB, Liew FY: Animal models of rheumatoid arthritis. Eur J Immunol. 2009, 39: 2040-2044. 10.1002/eji.200939578.View ArticlePubMedGoogle Scholar
- Ahlqvist E, Hultqvist M, Holmdahl R: The value of animal models in predicting genetic susceptibility to complex diseases such as rheumatoid arthritis. Arthritis Res Ther. 2009, 11: 226-10.1186/ar2600.PubMed CentralView ArticlePubMedGoogle Scholar
- Holmdahl R, Bockermann R, Backlund J, Yamada H: The molecular pathogenesis of collagen-induced arthritis in mice: a model for rheumatoid arthritis. Ageing Res Rev. 2002, 1: 135-147. 10.1016/S0047-6374(01)00371-2.View ArticlePubMedGoogle Scholar
- Glant TT, Finnegan A, Mikecz K: Proteoglycan-induced arthritis: immune regulation, cellular mechanisms, and genetics. Crit Rev Immunol. 2003, 23: 199-250. 10.1615/CritRevImmunol.v23.i3.20.View ArticlePubMedGoogle Scholar
- Hang L, Theofilopoulos AN, Dixon FJ: A spontaneous rheumatoid arthritis-like disease in MRL/l mice. J Exp Med. 1982, 155: 1690-1701. 10.1084/jem.155.6.1690.View ArticlePubMedGoogle Scholar
- Kamogawa J, Terada M, Mizuki S, Nishihara M, Yamamoto H, Mori S, Abe Y, Morimoto K, Nakatsuru S, Nakamura Y, Nose M: Arthritis in MRL/lpr mice is under the control of multiple gene loci with an allelic combination derived from the original inbred strains. Arthritis Rheum. 2002, 46: 1067-1074. 10.1002/art.10193.View ArticlePubMedGoogle Scholar
- Kouskoff V, Korganow AS, Duchatelle V, Degott C, Benoist C, Mathis D: Organ-specific disease provoked by systemic autoimmunity. Cell. 1996, 87: 811-822. 10.1016/S0092-8674(00)81989-3.View ArticlePubMedGoogle Scholar
- Keffer J, Probert L, Cazlaris H, Georgopoulos S, Kaslaris E, Kioussis D, Kollias G: Transgenic mice expressing human tumour necrosis factor: a predictive genetic model of arthritis. EMBO J. 1991, 10: 4025-4031.PubMed CentralPubMedGoogle Scholar
- Horai R, Saijo S, Tanioka H, Nakae S, Sudo K, Okahara A, Ikuse T, Asano M, Iwakura Y: Development of chronic inflammatory arthropathy resembling rheumatoid arthritis in interleukin 1 receptor antagonist-deficient mice. J Exp Med. 2000, 191: 313-320. 10.1084/jem.191.2.313.PubMed CentralView ArticlePubMedGoogle Scholar
- Atsumi T, Ishihara K, Kamimura D, Ikushima H, Ohtani T, Hirota S, Kobayashi H, Park SJ, Saeki Y, Kitamura Y, Hirano T: A point mutation of Tyr-759 in interleukin 6 family cytokine receptor subunit gp130 causes autoimmune arthritis. J Exp Med. 2002, 196: 979-990. 10.1084/jem.20020619.PubMed CentralView ArticlePubMedGoogle Scholar
- Sakaguchi N, Takahashi T, Hata H, Nomura T, Tagami T, Yamazaki S, Sakihama T, Matsutani T, Negishi I, Nakatsuru S, Sakaguchi S: Altered thymic T-cell selection due to a mutation of the ZAP-70 gene causes autoimmune arthritis in mice. Nature. 2003, 426: 454-460. 10.1038/nature02119.View ArticlePubMedGoogle Scholar
- Waldner H, Whitters MJ, Sobel RA, Collins M, Kuchroo VK: Fulminant spontaneous autoimmunity of the central nervous system in mice transgenic for the myelin proteolipid protein-specific T cell receptor. Proc Natl Acad Sci USA. 2000, 97: 3412-3417. 10.1073/pnas.97.7.3412.PubMed CentralView ArticlePubMedGoogle Scholar
- Sawa S, Kamimura D, Jin GH, Morikawa H, Kamon H, Nishihara M, Ishihara K, Murakami M, Hirano T: Autoimmune arthritis associated with mutated interleukin (IL)-6 receptor gp130 is driven by STAT3/IL-7-dependent homeostatic proliferation of CD4+ T cells. J Exp Med. 2006, 203: 1459-1470. 10.1084/jem.20052187.PubMed CentralView ArticlePubMedGoogle Scholar
- Kaplan CD, O'Neill SK, Koreny T, Czipri M, Finnegan A: Development of inflammation in proteoglycan-induced arthritis is dependent on FcγR regulation of the cytokine/chemokine environment. J Immunol. 2002, 169: 5851-5859.View ArticlePubMedGoogle Scholar
- Tompkins SM, Padilla J, Dal Canto MC, Ting JP, Van Kaer L, Miller SD: De novo central nervous system processing of myelin antigen is required for the initiation of experimental autoimmune encephalomyelitis. J Immunol. 2002, 168: 4173-4183.View ArticlePubMedGoogle Scholar
- McMahon EJ, Bailey SL, Castenada CV, Waldner H, Miller SD: Epitope spreading initiates in the CNS in two mouse models of multiple sclerosis. Nat Med. 2005, 11: 335-339. 10.1038/nm1202.View ArticlePubMedGoogle Scholar
- De Vos M: Joint involvement associated with inflammatory bowel disease. Dig Dis. 2009, 27: 511-515. 10.1159/000233290.View ArticlePubMedGoogle Scholar
- Hazenberg MP, Klasen IS, Kool J, Ruseler-van Embden JG, Severijnen AJ: Are intestinal bacteria involved in the etiology of rheumatoid arthritis? Review article. APMIS. 1992, 100: 1-9. 10.1111/j.1699-0463.1992.tb00833.x.View ArticlePubMedGoogle Scholar
- Shen Z, Fox JG, Dewhirst FE, Paster BJ, Foltz CJ, Yan L, Shames B, Perry L: Helicobacter rodentium sp. nov., a urease-negative Helicobacter species isolated from laboratory mice. Int J Syst Bacteriol. 1997, 47: 627-634. 10.1099/00207713-47-3-627.View ArticlePubMedGoogle Scholar
- Chichlowski M, Sharp JM, Vanderford DA, Myles MH, Hale LP: Helicobacter typhlonius and Helicobacter rodentium differentially affect the severity of colon inflammation and inflammation-associated neoplasia in IL10-deficient mice. Comp Med. 2008, 58: 534-541.PubMed CentralPubMedGoogle Scholar
- Myles MH, Livingston RS, Franklin CL: Pathogenicity of Helicobacter rodentium in A/JCr and SCID mice. Comp Med. 2004, 54: 549-557.PubMedGoogle Scholar
- Shomer NH, Dangler CA, Marini RP, Fox JG: Helicobacter bilis/Helicobacter rodentium co-infection associated with diarrhea in a colony of scid mice. Lab Anim Sci. 1998, 48: 455-459.PubMedGoogle Scholar
- Edwards SW, Hallett MB: Seeing the wood for the trees: the forgotten role of neutrophils in rheumatoid arthritis. Immunol Today. 1997, 18: 320-324. 10.1016/S0167-5699(97)01087-6.View ArticlePubMedGoogle Scholar
- Firestein GS: Evolving concepts of rheumatoid arthritis. Nature. 2003, 423: 356-361. 10.1038/nature01661.View ArticlePubMedGoogle Scholar
- Ishigame H, Nakajima A, Saijo S, Komiyama Y, Nambu A, Matsuki T, Nakae S, Horai R, Kakuta S, Iwakura Y: The role of TNFα and IL-17 in the development of excess IL-1 signaling-induced inflammatory diseases in IL-1 receptor antagonist-deficient mice. Ernst Schering Res Found Workshop. 2006, 56: 129-153.View ArticlePubMedGoogle Scholar
- Gottenberg JE, Miceli-Richard C, Ducot B, Goupille P, Combe B, Mariette X: Markers of B-lymphocyte activation are elevated in patients with early rheumatoid arthritis and correlated with disease activity in the ESPOIR cohort. Arthritis Res Ther. 2009, 11: R114-10.1186/ar2773.PubMed CentralView ArticlePubMedGoogle Scholar
- Lleo A, Battezzati PM, Selmi C, Gershwin ME, Podda M: Is autoimmunity a matter of sex?. Autoimmun Rev. 2008, 7: 626-630. 10.1016/j.autrev.2008.06.009.View ArticlePubMedGoogle Scholar
- Taneja V, Behrens M, Mangalam A, Griffiths MM, Luthra HS, David CS: New humanized HLA-DR4-transgenic mice that mimic the sex bias of rheumatoid arthritis. Arthritis Rheum. 2007, 56: 69-78. 10.1002/art.22213.View ArticlePubMedGoogle Scholar
- Behrens M, Trejo T, Luthra H, Griffiths M, David CS, Taneja V: Mechanism by which HLA-DR4 regulates sex-bias of arthritis in humanized mice. J Autoimmun. 2010, 35: 1-9. 10.1016/j.jaut.2009.12.007.PubMed CentralView ArticlePubMedGoogle Scholar
- Abe K, Fuchs H, Lisse T, Hans W, Hrabé de Angelis M: New ENU-induced semidominant mutation, Ali18, causes inflammatory arthritis, dermatitis, and osteoporosis in the mouse. Mamm Genome. 2006, 17: 915-926. 10.1007/s00335-006-0014-x.View ArticlePubMedGoogle Scholar
- Yu P, Constien R, Dear N, Katan M, Hanke P, Bunney TD, Kunder S, Quintanilla-Martinez L, Huffstadt U, Schröder A, Jones NP, Peters T, Fuchs H, de Angelis MH, Nehls M, Grosse J, Wabnitz P, Meyer TP, Yasuda K, Schiemann M, Schneider-Fresenius C, Jagla W, Russ A, Popp A, Josephs M, Marquardt A, Laufs J, Schmittwolf C, Wagner H, Pfeffer K, Mudde GC: Autoimmunity and inflammation due to a gain-of-function mutation in phospholipase Cγ2 that specifically increases external Ca2+ entry. Immunity. 2005, 22: 451-465. 10.1016/j.immuni.2005.01.018.View ArticlePubMedGoogle Scholar
- Korganow AS, Ji H, Mangialaio S, Duchatelle V, Pelanda R, Martin T, Degott C, Kikutani H, Rajewsky K, Pasquali JL, Benoist C, Mathis D: From systemic T cell self-reactivity to organ-specific autoimmune disease via immunoglobulins. Immunity. 1999, 10: 451-461. 10.1016/S1074-7613(00)80045-X.View ArticlePubMedGoogle Scholar
- Crispin JC, Liossis SN, Kis-Toth K, Lieberman LA, Kyttaris VC, Juang YT, Tsokos GC: Pathogenesis of human systemic lupus erythematosus: recent advances. Trends Mol Med. 2010, 16: 47-57. 10.1016/j.molmed.2009.12.005.PubMed CentralView ArticlePubMedGoogle Scholar
- Zhou T, Bluethmann H, Eldridge J, Berry K, Mountz JD: Origin of CD4-CD8-B220+ T cells in MRL-lpr/lpr mice: clues from a T cell receptor β transgenic mouse. J Immunol. 1993, 150: 3651-3667.PubMedGoogle Scholar
- Lindwasser OW, Chaudhuri R, Bonifacino JS: Mechanisms of CD4 downregulation by the Nef and Vpu proteins of primate immunodeficiency viruses. Curr Mol Med. 2007, 7: 171-184. 10.2174/156652407780059177.View ArticlePubMedGoogle Scholar
- Schonrich G, Kalinke U, Momburg F, Malissen M, Schmitt-Verhulst AM, Malissen B, Hammerling GJ, Arnold B: Down-regulation of T cell receptors on self-reactive T cells as a novel mechanism for extrathymic tolerance induction. Cell. 1991, 65: 293-304. 10.1016/0092-8674(91)90163-S.View ArticlePubMedGoogle Scholar
- Zhang L, Fung-Leung W, Miller RG: Down-regulation of CD8 on mature antigen-reactive T cells as a mechanism of peripheral tolerance. J Immunol. 1995, 155: 3464-3471.PubMedGoogle Scholar
- Nicholson LB, Anderson AC, Kuchroo VK: Tuning T cell activation threshold and effector function with cross-reactive peptide ligands. Int Immunol. 2000, 12: 205-213. 10.1093/intimm/12.2.205.View ArticlePubMedGoogle Scholar
- Illes Z, Waldner H, Reddy J, Anderson AC, Sobel RA, Kuchroo VK: Modulation of CD4 co-receptor limits spontaneous autoimmunity when high-affinity transgenic TCR specific for self-antigen is expressed on a genetically resistant background. Int Immunol. 2007, 19: 1235-1248. 10.1093/intimm/dxm094.View ArticlePubMedGoogle Scholar
- Thomson CW, Lee BP, Zhang L: Double-negative regulatory T cells: non-conventional regulators. Immunol Res. 2006, 35: 163-178. 10.1385/IR:35:1:163.View ArticlePubMedGoogle Scholar
- Voelkl S, Gary R, Mackensen A: Characterization of the immunoregulatory function of human TCR-αβ+ CD4-CD8- double-negative T cells. Eur J Immunol. 2011, 41: 739-748. 10.1002/eji.201040982.View ArticlePubMedGoogle Scholar
- Hamad AR, Mohamood AS, Trujillo CJ, Huang CT, Yuan E, Schneck JP: B220+ double-negative T cells suppress polyclonal T cell activation by a Fas-independent mechanism that involves inhibition of IL-2 production. J Immunol. 2003, 171: 2421-2426.View ArticlePubMedGoogle Scholar
- Yoshitomi H, Sakaguchi N, Kobayashi K, Brown GD, Tagami T, Sakihama T, Hirota K, Tanaka S, Nomura T, Miki I, Gordon S, Akira S, Nakamura T, Sakaguchi S: A role for fungal β-glucans and their receptor Dectin-1 in the induction of autoimmune arthritis in genetically susceptible mice. J Exp Med. 2005, 201: 949-960. 10.1084/jem.20041758.PubMed CentralView ArticlePubMedGoogle Scholar
- Fernando MM, Stevens CR, Walsh EC, De Jager PL, Goyette P, Plenge RM, Vyse TJ, Rioux JD: Defining the role of the MHC in autoimmunity: a review and pooled analysis. PLoS Genet. 2008, 4: e1000024-10.1371/journal.pgen.1000024.PubMed CentralView ArticlePubMedGoogle Scholar
- Festen EA, Goyette P, Scott R, Annese V, Zhernakova A, Lian J, Lefebvre C, Brant SR, Cho JH, Silverberg MS, Taylor KD, de Jong DJ, Stokkers PC, McGovern D, Palmieri O, Achkar JP, Xavier RJ, Daly MJ, Duerr RH, Wijmenga C, Weersma RK, Rioux JD: Genetic variants in the region harbouring IL2/IL21 associated with ulcerative colitis. Gut. 2009, 58: 799-804. 10.1136/gut.2008.166918.PubMed CentralView ArticlePubMedGoogle Scholar
- Kochi Y, Okada Y, Suzuki A, Ikari K, Terao C, Takahashi A, Yamazaki K, Hosono N, Myouzen K, Tsunoda T, Kamatani N, Furuichi T, Ikegawa S, Ohmura K, Mimori T, Matsuda F, Iwamoto T, Momohara S, Yamanaka H, Yamada R, Kubo M, Nakamura Y, Yamamoto K: A regulatory variant in CCR6 is associated with rheumatoid arthritis susceptibility. Nat Genet. 2010, 42: 515-519. 10.1038/ng.583.View ArticlePubMedGoogle Scholar
- Lettre G, Rioux JD: Autoimmune diseases: insights from genome-wide association studies. Hum Mol Genet. 2008, 17: R116-R121. 10.1093/hmg/ddn246.PubMed CentralView ArticlePubMedGoogle Scholar
- Asada Y, Isomoto H, Shikuwa S, Wen CY, Fukuda E, Miyazato M, Okamoto K, Nakamura T, Nishiyama H, Mizuta Y, Migita K, Ito M, Kohno S: Development of ulcerative colitis during the course of rheumatoid arthritis: association with selective IgA deficiency. World J Gastroenterol. 2006, 12: 5240-5243.PubMed CentralPubMedGoogle Scholar
- Georgiadis AN, Tzambouras N, Ioachim E, Tsianos EV, Agnantis N, Drosos AA: Seropositive rheumatoid arthritis associated with Crohn's disease. Clin Exp Rheumatol. 2003, 21: 363-365.PubMedGoogle Scholar
- Davis JC, Mease PJ: Insights into the pathology and treatment of spondyloarthritis: from the bench to the clinic. Semin Arthritis Rheum. 2008, 38: 83-100. 10.1016/j.semarthrit.2007.10.007.View ArticlePubMedGoogle Scholar
- Papamichael K, Tsirogianni A, Papasteriades C, Mantzaris GJ: Low prevalence of antibodies to cyclic citrullinated peptide in patients with inflammatory bowel disease regardless of the presence of arthritis. Eur J Gastroenterol Hepatol. 2010, 22: 705-709.PubMedGoogle Scholar
- Arnett FC, Edworthy SM, Bloch DA, McShane DJ, Fries JF, Cooper NS, Healey LA, Kaplan SR, Liang MH, Luthra HS, Medsger TA, Mitchell DM, Neustadt DH, Pinals RS, Schaller JG, Sharp JT, Wilder RL, Hunder GG: The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum. 1988, 31: 315-324. 10.1002/art.1780310302.View ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.