GPI-induced Arthritis Research Articles

Incidence and severity of G6PI-induced arthritis are not increased in genetically distinct mouse strains upon aging

BackgroundThe incidence of rheumatoid arthritis is correlated with age. In this study, we analyzed the association of the incidence and severity of glucose-6-phosphate isomerase (G6PI)-induced arthritis with age in two different mouse strains.MethodsYoung and very old mice from two different arthritis-susceptible wild-type mouse strains were analyzed after a single subcutaneous injection of G6PI s.c. The metabolism and the function of synoviocytes were analyzed in vitro, the production of bioactive lipid mediators by myeloid cells and synoviocytes was assessed in vitro and ex vivo by UPLC-MS-MS, and flow cytometry was used to verify age-related changes of immune cell composition and function.ResultsWhile the severity of arthritis was independent from age, the onset was delayed in old mice. Old mice showed common signs of immune aging like thymic atrophy associated with decreased CD4+ effector T cell numbers. Despite its decrease, the effector T helper (Th) cell compartment in old mice was reactive and functionally intact, and their Tregs exhibited unaltered suppressive capacities. In homeostasis, macrophages and synoviocytes from old mice produced higher amounts of pro-inflammatory cyclooxygenase (COX)-derived products. However, this functional difference did not remain upon challenge in vitro nor upon arthritis reactions ex vivo.ConclusionWhile old mice show a higher baseline of inflammatory functions, this does not result in increased reaction towards self-antigens in arthritis-susceptible mouse strains. Together, our data from two different mouse strains show that the susceptibility for G6PI-induced arthritis is not age-dependent.

Specific Increase in Joint Neutrophil Extracellular Traps and Its Relation to Interleukin 6 in Autoimmune Arthritis.

Neutrophils and their extracellular traps have been shown to play an important role in the pathogenesis of rheumatoid arthritis (RA), but the detailed mechanisms in joints are still unclear, and their regulation remains to be solved. Here, we explored neutrophil extracellular trap (NET)osis in experimental models of arthritis and further investigated the effects of interleukin-6 (IL-6) inhibition in neutrophils and NETosis. In skins of peptide GPI-induced arthritis (pGIA), citrullinated protein was detected as well as citrullinated histone expression in immunized skin but this was not specific to pGIA. Citrullinated histone expression in pGIA joints was specific to pGIA and was merged with neutrophil elastase, suggesting NETosis. Neutrophils in joints tend to upregulate IL-6 receptors when compared with bone marrow neutrophils. Administration of mouse anti-IL-6 receptor antibodies in pGIA suppressed arthritis in association with a decrease in neutrophil infiltration and NETosis in joints. In the plasma of RA patients, citrullinated protein was significantly reduced after tocilizumab treatment. Our results suggest that IL-6 enhances neutrophil chemotaxis and NETosis in inflammatory joints and could be the source of citrullinated proteins.

Contribution of Inflammation and Bone Destruction to Pain in Arthritis: A Study in Murine Glucose-6-Phosphate Isomerase-Induced Arthritis.

Arthritis is often characterized by inflammation and bone destruction. This study was undertaken to investigate the contribution of inflammation and bone destruction to pain. Inflammation, bone resorption, pain-related behaviors, and molecular markers (activating transcription factor 3 [ATF-3], p-CREB, and transient receptor potential vanilloid channel 1) in sensory neurons were measured in murine glucose-6-phosphate isomerase (G6PI)-induced arthritis, a model of rheumatoid arthritis. Depletion of Treg cells before immunization changed self-limiting arthritis into nonremitting arthritis with pronounced bone destruction. Zoledronic acid (ZA) was administered to reduce bone resorption. Compared to nondepleted mice, Treg cell-depleted mice exhibited arthritis with more severe bone destruction and higher guarding scores (P < 0.05; n = 10 mice per group) as well as more persistent thermal hyperalgesia (P < 0.05), but displayed similar mechanical hyperalgesia at the hindpaws (n = 18-26 mice per group). These pain-related behaviors, as well as an up-regulation of the neuronal injury marker ATF-3 in sensory neurons (studied in 39 mice), appeared before the clinical score (inflammation) became positive and persisted in Treg cell-depleted and nondepleted mice. In the late stage of arthritis, Treg cell-depleted mice treated with ZA showed less bone resorption (<50%; P < 0.01) and less thermal hyperalgesia (P < 0.01) than Treg cell-depleted mice without ZA treatment (n = 15 mice per group), but ZA treatment did not reduce the clinical score and local mechanical hyperalgesia. Pain-related behaviors precede and outlast self-limiting arthritis. In nonremitting arthritis with enhanced bone destruction, mainly local thermal, but not local mechanical, hyperalgesia was aggravated. The up-regulation of ATF-3 indicates an early and persisting affection of sensory neurons by G6PI-induced arthritis.

Revisit of autoimmunity to glucose-6-phosphate isomerase in experimental and rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disorder characterized by synovial inflammation in multiple joints. Autoantibodies (Abs) are the hallmark of RA, and as disease-specific and diagnostic markers, rheumatoid factor and anti-citrullinated protein antibody (ACPA) are produced pre-clinically, but their pathogenic roles in RA remain elusive. In this review, we focus on one of the candidate autoantigens in RA; glucose-6-phosphate isomerase (GPI). The arthritogenic role of GPI has been confirmed in two different mouse models: the K/BxN- and GPI-induced arthritis models. Both anti-GPI Abs and citrullinated-GPI peptide Abs have been detected in human RA. Studies conducted in these rodent models have confirmed that the pathogenesis of arthritis involves the localization of autoantigens not only in the joints but also in the circulation. In this review, we revisit and summarize the arthritogenic relevance of GPI in animal RA models and in human RA, and extend the discussion to joint-specific inflammation.

Suppression of glucose-6-phosphate-isomerase induced arthritis by oral administration of transgenic rice seeds expressing altered peptide ligands of glucose-6-phosphate-isomerase

Objective: To investigate the effects of transgenic rice seeds expressing the altered peptide ligand (APL) of human glucose-6-phosphate-isomerase (hGPI325–339) in mice model of GPI-induced arthritis (GIA).Methods: We generated transgenic rice expressing T-cell epitope of hGPI325–339 and APL12 contained in the seed endosperm. The transgenic rice seeds were orally administered prophylactically before the induction of GIA. The severity of arthritis and titers of serum anti-GPI antibodies were evaluated. We examined for IL-17 production in splenocytes and inguinal lymph node (iLN) cells, and analyzed the expression levels of functional molecules in splenocytes.Results: Prophylactic treatment of GIA mice with APL12 transgenic (APL12-TG) rice seeds significantly reduced the severity of arthritis and titers of serum anti-GPI antibodies compared with non-transgenic (Non-TG) rice-treated mice. APL12-TG and hGPI325–339 transgenic (hGPI325–339-TG) rice seeds improved the histopathological arthritis scores and decreased IL-17 production compared with non-TG rice-treated mice. APL12-TG rice-treated GIA mice showed upregulation of Foxp3 and GITR protein in CD4 + CD25 + Foxp3+ cells in the spleen compared with non-TG rice- and hGPI325–339-TG rice-treated mice.Conclusion: APL12-TG rice seeds improved the severity of GIA through a decrease in production of IL-17 and anti-GPI antibodies via upregulation of Foxp3 and GITR expression on Treg cells in spleen.

アナログペプチド発現米を用いたGPI誘導関節炎の抑制

To investigate the effects and mechanisms of transgenic rice seeds expressing the altered peptide ligand (APL) of human glucose-6-phosphate-isomerase (hGPI325-339) in mice model of GPI induced arthritis (GIA). We generated transgenic rice expressing APL12 which was analog peptide of hGPI325-339. The transgenic rice seeds were orally administered prophylactically before the induction of GIA. The severity of arthritis and titers of serum anti-GPI antibodies were evaluated. We examined IL-17 production from splenocytes and inguinal lymph node (iLN) and mesenteric lymph nodes (mLN) cells and analyzed the expression levels of functional molecules from splenocytes and iLN cells. Prophylactic treatment of GIA mice with APL12 transgenic rice seeds (APL12-TG) significantly improved the severity of arthritis, histopathological arthritis scores, and decreased titers of serum anti-GPI antibodies, BAFF mRNA in iLN cells, IL-17 production in splenocytes and iLN cells compared with non-transgenic rice-treated mice. APL12-TG-treated GIA mice showed upregulation of Foxp3 and GITR protein in CD4+CD25+ cells in the spleen. APL12-TG improved the severity of GIA through a decrease in production of IL-17 and anti-GPI antibodies via upregulation of Foxp3 and GITR expression on regulatory T cells in spleen.

Simultaneous inhibition of JAK and SYK kinases ameliorates chronic and destructive arthritis in mice.

IntroductionDespite the broad spectrum of antirheumatic drugs, RA is still not well controlled in up to 30-50 % of patients. Inhibition of JAK kinases by means of the pan-JAK inhibitor tofacitinib has demonstrated to be effective even in difficult-to-treat patients. Here, we discuss whether the efficacy of JAK inhibition can be improved by simultaneously inhibiting SYK kinase, since both kinases mediate complementary and non-redundant pathways in RA.MethodsEfficacy of dual JAK + SYK inhibition with selective small molecule inhibitors was evaluated in chronic G6PI-induced arthritis, a non-self-remitting and destructive arthritis model in mice. Clinical and histopathological scores, as well as cytokine and anti-G6PI antibody production were assessed in both preventive and curative protocols. Potential immunotoxicity was also evaluated in G6PI-induced arthritis and in a 28-day TDAR model, by analysing the effects of JAK + SYK inhibition on hematological parameters, lymphoid organs, leukocyte subsets and cell function.ResultsSimultaneous JAK + SYK inhibition completely prevented mice from developing arthritis. This therapeutic strategy was also very effective in ameliorating already established arthritis. Dual kinase inhibition immediately resulted in greatly decreased clinical and histopathological scores and led to disease remission in over 70 % of the animals. In contrast, single JAK inhibition and anti-TNF therapy (etanercept) were able to stop disease progression but not to revert it. Dual kinase inhibition decreased Treg and NK cell counts to the same extent as single JAK inhibition but overall cytotoxicity remained intact. Interestingly, treatment discontinuation rapidly reversed such immune cell reduction without compromising clinical efficacy, suggesting long-lasting curative effects. Dual kinase inhibition reduced the Th1/Th17 cytokine cascade and the differentiation and function of joint cells, in particular osteoclasts and fibroblast-like synoviocytes.ConclusionsConcurrent JAK + SYK inhibition resulted in higher efficacy than single kinase inhibition and TNF blockade in a chronic and severe arthritis model. Thus, blockade of multiple immune signals with dual JAK + SYK inhibition represents a reasonable therapeutic strategy for RA, in particular in patients with inadequate responses to current treatments. Our data supports the multiplicity of events underlying this heterogeneous and complex disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0866-0) contains supplementary material, which is available to authorized users.

Antigen-specific over-expression of human cartilage glycoprotein 39 on CD4+ CD25+ forkhead box protein 3+ regulatory T cells in the generation of glucose-6-phosphate isomerase-induced arthritis.

Human cartilage gp-39 (HC gp-39) is a well-known autoantigen in rheumatoid arthritis (RA). However, the exact localization, fluctuation and function of HC gp-39 in RA are unknown. Therefore, using a glucose-6-phosphate isomerase (GPI)-induced model of arthritis, we investigated these aspects of HC gp-39 in arthritis. The rise in serum HC gp-39 levels was detected on the early phase of GPI-induced arthritis (day 7) and the HC gp-39 mRNA was increased significantly on splenic CD4(+) T cells on day7, but not on CD11b(+) cells. Moreover, to identify the characterization of HC gp-39(+) CD4(+) T cells, we assessed the analysis of T helper (Th) subsets. As a result, HC gp-39 was expressed dominantly in CD4(+) CD25(+) forkhead box protein 3 (FoxP3)(+) refulatory T cells (T(reg)), but not in Th1, Th2 or Th17 cells. Furthermore, to investigate the effect of HC gp-39 to CD4(+) T cells, T cell proliferation assay and cytokine production from CD4(+) T cells using recombinant HC gp-39 was assessed. We found that GPI-specific T cell proliferation and interferon (IFN)-γ or interleukin (IL)-17 production were clearly suppressed by addition of recombinant HC gp-39. Antigen-specific over-expression of HC gp-39 in splenic CD4(+) CD25(+) FoxP3(+) T(reg) cells occurs in the induction phase of GPI-induced arthritis, and addition of recombinant HC gp-39 suppresses antigen-specific T-cell proliferation and cytokine production, suggesting that HC gp-39 in CD4(+) T cells might play a regulatory role in arthritis.

18 F-Fluoride positron emission tomography/computed tomography for noninvasive in vivo quantification of pathophysiological bone metabolism in experimental murine arthritis.

IntroductionEvaluation of disease severity in experimental models of rheumatoid arthritis is inevitably associated with assessment of structural bone damage. A noninvasive imaging technology allowing objective quantification of pathophysiological alterations of bone structure in rodents could substantially extend the methods used to date in preclinical arthritis research for staging of autoimmune disease severity or efficacy of therapeutical intervention. Sodium 18 F-fluoride (18 F-NaF) is a bone-seeking tracer well-suited for molecular imaging. Therefore, we systematically examined the use of 18 F-NaF positron emission tomography/computed tomography (PET/CT) in mice with glucose-6-phosphate isomerase (G6PI)–induced arthritis for quantification of pathological bone metabolism.MethodsF-fluoride was injected into mice before disease onset and at various time points of progressing experimental arthritis. Radioisotope accumulation in joints in the fore- and hindpaws was analyzed by PET measurements. For validation of bone metabolism quantified by 18 F-fluoride PET, bone surface parameters of high-resolution μCT measurements were used.ResultsBefore clinical arthritis onset, no distinct accumulation of 18 F-fluoride was detectable in the fore- and hindlimbs of mice immunized with G6PI. In the course of experimental autoimmune disease, 18 F-fluoride bone uptake was increased at sites of enhanced bone metabolism caused by pathophysiological processes of autoimmune disease. Moreover, 18 F-fluoride signaling at different stages of G6PI-induced arthritis was significantly correlated with the degree of bone destruction. CT enabled identification of exact localization of 18 F-fluoride signaling in bone and soft tissue.ConclusionsThe results of this study suggest that small-animal PET/CT using 18 F-fluoride as a tracer is a feasible method for quantitative assessment of pathophysiological bone metabolism in experimental arthritis. Furthermore, the possibility to perform repeated noninvasive measurements in vivo allows longitudinal study of therapeutical intervention monitoring.

The combined effects of iguratimod with anti-TNF^|^alpha; antibody on experimental arthritis models in mice

[Objectives] The combined effects of a new antirheumatic drug, iguratimod (IGU) with antitumor necrosis factor (TNF)α antibody (aTNFAb) were examined in two mouse models of arthritis. [Methods] In collagen-induced arthritis (CIA) model, arthritis was induced by immunization with type II collagen on day 0 and 21. IGU was orally administrated once daily and aTNFAb was intraperitoneally injected twice a week from day 25 to day 34. In glucose-6-phosphate isomerase (GPI)-induced arthritis model, arthritis was induced by immunization with recombinant GPI on day 0 and the treatments were started on day 5. IGU was orally administrated daily and aTNFAb was intravenously injected every other day to day 14. Efficacy was evaluated using arthritis scores, articular destruction scores, and blood biochemical analyses. [Results] In the CIA model, the combination of IGU and aTNFAb significantly inhibited the arthritis and articular destruction more effectively than as monotherapies. Serum interleukin (IL)-1β and IL-6 levels were also reduced significantly with combined treatment. The decline in serum levels of cartilage oligomeric matrix protein (COMP) and matrix metalloproteinase (MMP)3 was significantly enhanced with the IGU/aTNFAb combination. In the GPI-induced arthritis model, IGU and aTNFAb lowered the arthritis scores and the combination of both treatments showed a significant effect compared with IGU alone. Regarding anti-GPI titers on day 14, IGU and/or aTNFAb showed no significant effect. [Conclusion] In the two mouse models, the combination of IGU and aTNFAb showed greater benefit than either monotherapy, suggesting such combination therapy would be effective in clinical use.

Amelioration of experimental arthritis by stroke-induced immunosuppression is independent of Treg cell function

ObjectivesClinical evidence suggests that neurological lesions can protect from arthritis. Acute cerebral ischaemia induces severe immunosuppression, resulting in enhanced susceptibility to infections. We aimed to determine if stroke-induced immunosuppression can...

AB0158 Anti-interleukin-6 receptor antibody suppresses loss of trabecular bone volume in mice with glucose-6-phosphate isomerase-induced arthritis

BackgroundOsteoporosis can lead to increased risk of fractures, which are associated with increased morbidity and mortality. The incidence rate of osteoporosis in patients with RA is several times that in...

Activation of Invariant NKT Cells with Glycolipid Ligand α-Galactosylceramide Ameliorates Glucose-6-Phosphate Isomerase Peptide-Induced Arthritis

ObjectiveInvariant natural killer T (iNKT) cells regulate collagen-induced arthritis (CIA) when activated by their potent glycolipid ligand, alpha-galactosylceramide (α-GalCer). Glucose-6-phosphate isomerase (GPI)-induced arthritis is a closer model of human rheumatoid arthritis based on its association with CD4+ T cells and cytokines such as TNF-α and IL-6 than CIA. Dominant T cell epitope peptide of GPI (GPI325-339) can induce arthritis similar to GPI-induced arthritis. In this study, we investigated the roles of activation of iNKT cells by α-GalCer in GPI peptide-induced arthritis.MethodsArthritis was induced in susceptible DBA1 mice with GPI peptide and its severity was assessed clinically. The arthritic mice were treated with either the vehicle (DMSO) or α-GalCer. iNKT cells were detected in draining lymph nodes (dLNs) by flow cytometry, while serum anti-GPI antibody levels were measured by enzyme-linked immunosorbent assay. To evaluate GPI peptide-specific cytokine production from CD4+ T cells, immunized mice were euthanized and dLN CD4+ cells were re-stimulated by GPI-peptide in the presence of antigen-presenting cells.Resultsα-GalCer induced iNKT cell expansion in dLNs and significantly decreased the severity of GPI peptide-induced arthritis. In α-GalCer-treated mice, anti-GPI antibody production (total IgG, IgG1, IgG2b) and IL-17, IFN-γ, IL-2, and TNF-α produced by GPI peptide-specific T cells were significantly suppressed at day 10. Moreover, GPI-reactive T cells from mice immunized with GPI and α-GalCer did not generate any cytokines even when these cells were co-cultured with APC from mice immunized with GPI alone. In vitro depletion of iNKT cells did not alter the suppressive effect of α-GalCer on CD4+ T cells.Conclusionα-GalCer significantly suppressed GPI peptide-induced arthritis through the suppression of GPI-specific CD4+ T cells.

Crucial role of TNFα-induced adipose-related protein (TIARP) in the pathogenesis of autoimmune arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disorder with a variable disease outcome, and is characterized by inflammation of multiple joints. Proinflammtory cytokines, such as tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6) are thought to play crucial roles in the pathology of RA. The prognosis of patients with RA has improved significantly with the recent availability of biologics targeting TNFα and IL-6. Immunization of DBA/1 mice with glucose-6-phosphate isomerase (GPI) induces severe acute arthritis. This arthritis can be controlled by TNFα antagonists, suggesting similar etiology to RA. We performed GeneChip analysis using splenocytes of mice with GPI-induced arthritis. Among the arrayed TNFα-related genes, the expression of TNFα-induced adipose-related protein (TIARP) mRNA was the highest. TIARP was detected specifically in joints and spleens of arthritic mice. Among the splenocytes, CD11b(+) cells were the main source of TIARP mRNA. STEAP4 (the human ortholog of TIARP) was highly upregulated in joints of patients with RA and especially co-localized with CD68(+) macrophages. In this study, we discuss the role of TIARP in the generation of experimental autoimmune arthritis and the possible clinical application of for the treatment of RA.

Interleukin-6 regulates anti-arthritic effect of methotrexate via reduction of SLC19A1 expression in a mouse arthritis model

IntroductionMethotrexate (MTX) enters cells via the reduced folate carrier SLC19A1, suggesting that SLC19A1 is associated with the efficacy of MTX. We here examined the relationship between the efficacy of MTX and the expression of SLC19A1 in glucose 6-phosphate isomerase (GPI)-induced arthritis. We found that interleukin-6 (IL-6) regulated the expression of SLC19A1, so we studied the effect of a combination of MTX and anti-mouse IL-6 receptor antibody (MR16-1).MethodsGPI-induced arthritis was induced by intradermal immunization with recombinant GPI. MTX was given from the first day of immunization. Mice were injected once with MR16-1 10 days after immunization. The levels of SLC19A1 mRNA in whole hind limbs and immune cells were measured. Synovial cells from arthritic mice were cultured with cytokines, and cell proliferation and gene expressions were measured.ResultsMTX inhibited the development of GPI-induced arthritis; however, the efficacy of MTX gradually diminished. SLC19A1 expression in immunized mice with arthritis was lower than in intact mice; moreover, SLC19A1 expression in arthritic mice was further decreased when they were treated with MTX. IL-6 was highly expressed in whole hind limbs of arthritic mice. In an in vitro study using synovial cells from arthritic mice, IL-6 + soluble IL-6 receptor (sIL-6R) weakened the anti-proliferative effect of MTX and reduced SLC19A1 expression. Finally, although MR16-1 did not improve arthritis at all when administered on day 10, MTX in combination with MR16-1 more potently reduced the development of arthritis than did MTX alone. When used in combination with MTX, MR16-1 apparently reversed the decrease in SLC19A1 induced by MTX alone.ConclusionsIn the present study, we demonstrated for the first time that IL-6 reduced the efficacy of MTX by decreasing the expression of SLC19A1, which is important for MTX uptake into cells.

B Cell Depletion Reduces the Number of Autoreactive T Helper Cells and Prevents Glucose-6-Phosphate Isomerase-Induced Arthritis

The therapeutic benefit of B cell depletion in patients with rheumatoid arthritis has provided proof of concept that B cells are relevant for the pathogenesis of arthritis. It remains unknown which B cell effector functions contribute to the induction or chronification of arthritis. We studied the clinical and immunological effects of B cell depletion in glucose-6-phosphate isomerase-induced arthritis. We targeted CD22 to deplete B cells. Mice were depleted of B cells before or after immunization with glucose-6-phosphate isomerase (G6PI). The clinical and histological effects were studied. G6PI-specific antibody responses were measured by ELISA. G6PI-specific T helper (Th) cell responses were assayed by polychromatic flow cytometry. B cell depletion prior to G6PI-immunization prevented arthritis. B cell depletion after immunization ameliorated arthritis, whereas B cell depletion in arthritic mice was ineffective. Transfer of antibodies from arthritic mice into B cell depleted recipients did not reconstitute arthritis. B cell depleted mice harbored much fewer G6PI-specific Th cells than control animals. B cell depletion prevents but does not cure G6PI-induced arthritis. Arthritis prevention upon B cell depletion is associated with a drastic reduction in the number of G6PI-specific effector Th cells.

Therapeutic potential of anti–interleukin‐17A aptamer: Suppression of interleukin‐17A signaling and attenuation of autoimmunity in two mouse models

The proinflammatory cytokine interleukin-17A (IL-17A) is produced primarily by the CD4+ T cell subset called Th17 cells, which is involved in host defense, inflammation, and autoimmune disorders. This study was undertaken to investigate the effect of a high-affinity RNA molecule, called an aptamer, against human IL-17A on IL-17A-induced signal transduction in vitro and its anti-autoimmune efficacy in vivo in 2 mouse models of inflammation. By screening a large library of nuclease-resistant RNA oligonucleotides, we selected an RNA aptamer, Apt21-2, that binds human and mouse IL-17 and blocks the interaction between IL-17A and its receptor. The inhibition of IL-17A-mediated phosphorylation and marker protein production was analyzed in human and mouse cells. Mice with glucose-6-phosphate isomerase (GPI)-induced rheumatoid arthritis and myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis were used to assess efficacy. Apt21-2 prevented efficient phosphorylation of the IL-17A signaling factors IκB and JNK and inhibited the production of IL-6 in human and mouse cells. A PEGylated form of Apt21-2 (PEG21-2idT) exhibited a 50% inhibition concentration (IC(50) ) in the range of 1-2 nM and 70-80 nM in human and mouse cells, respectively. When administered immediately after immunization with GPI or MOG, PEG21-2idT inhibited in a dose-dependent manner the development of arthritic or neurologic symptoms. Significantly, PEG21-2idT slowed the progression of arthritis when administered after the onset of GPI-induced arthritis. Our findings indicate that the chemically processed anti-IL-17A aptamer PEG21-2idT inhibits the actions of IL-17A as well as the development of autoimmunity in 2 mouse models of inflammation. These results offer for the first time an aptamer-based therapeutic approach to the treatment of Th17 cell-mediated autoimmune disorders.

Ameliorated course of glucose-6-phosphate isomerase (G6PI)-induced arthritis in IFN-γ receptor knockout mice exposes an arthritis-promoting role of IFN-γ

The absence of IFN-γ signaling leads to an increased inflammatory response in many murine models of autoimmune diseases induced by a CFA-assisted immunization schedule. We investigated the role of endogenous IFN-γ in arthritis induced by immunization with glucose-6-phosphate isomerase (G6PI) in CFA in DBA/1 mice. Surprisingly, and in contrast to our previous findings in collagen-induced arthritis (CIA), G6PI-induced arthritis was found to be reduced in IFN-γ receptor-deficient (IFN-γR KO) mice, demonstrating a proinflammatory role for IFN-γ in this model. Milder disease in IFN-γR KO mice was associated with less vigorous innate and adaptive immune responses early (day 9) after immunization: less proliferation of myeloid cells in the spleen, less osteoclast formation, less G6PI-reactive Th cells (as measured by ex vivo stimulation and flow cytometry and by in vivo skin reactivity to G6PI) and lower G6PI-specific immunoglobulin serum levels. Surprisingly, on day 21, despite continued milder disease in IFN-γR KO mice, their Th cell responses were no longer diminished but augmented as compared to wild-type mice, and their numbers of immature myeloid splenocytes were also more increased. These data reveal that IFN-γ signaling is critical for the induction of the early immune responses which trigger G6PI-induced arthritis. The strikingly different clinical consequences of absent IFN-γ signaling in G6PI-induced arthritis compared with the very similarly induced CIA emphasize that the role of a single cytokine in experimentally induced arthritis depends critically on the very nature of the inciting (auto)antigen and in particular on the kinetics of the disease manifestation elicited by the antigen.

Heterogeneous Stock Mice are Susceptible to Encephalomyelitis and Antibody‐initiated Arthritis but not to Collagen‐ and G6PI‐induced Arthritis

The strategy of using heterogeneous stock (HS) mice has proven to be successful in fine mapping of quantitative trait loci in complex diseases. However, whether these mice can be used for arthritis, encephalomyelitis and autoimmune phenotypes has not been addressed. Here, we screened the Northport HS mice for arthritis phenotypes using three different models: collagen-induced arthritis (CIA), using rat, bovine or chicken collagen type II (CII); recombinant human glucose-6-phosphate isomerase (G6PI)-induced arthritis; and collagen antibody-induced arthritis (CAIA). Irrespective of the origin of collagen, we found HS mice to be fairly resistant to CIA and G6PI-induced arthritis, despite the development of antibodies against the respective antigens. On the other hand, HS mice were found to be susceptible for CAIA. Similarly, these mice developed encephalomyelitis (EAE) induced either with mouse or rat spinal cord homogenate (SCH), or with recombinant rat myelin oligodendrocyte glycoprotein, with elevated antibody levels against CNS proteins. Accordingly, we conclude that the use of HS mice for fine mapping and positional cloning of gene(s) involved in CAIA and EAE is possible, but not for collagen- and G6PI-induced arthritis.

Inducible costimulator (ICOS) blockade inhibits accumulation of polyfunctional T helper 1/T helper 17 cells and mitigates autoimmune arthritis

ObjectivesInducible costimulator (ICOS) and its ligand (ICOSL) regulate T and B cell responses. Glucose-6-phosphate isomerase (G6PI)-induced arthritis requires T and B lymphocytes. It was hypothesised that blocking ICOS/ICOSL interactions ameliorates...