Mouse Model Of RA Research Articles

Engineered self-regulating macrophages for targeted anti-inflammatory drug delivery

BackgroundRheumatoid arthritis (RA) is a systemic autoimmune disease characterized by increased levels of inflammation that primarily manifests in the joints. Macrophages act as key drivers for the progression of RA, contributing to the perpetuation of chronic inflammation and dysregulation of pro-inflammatory cytokines such as interleukin 1 (IL-1). The goal of this study was to develop a macrophage-based cell therapy for biologic drug delivery in an autoregulated manner.MethodsFor proof-of-concept, we developed “smart” macrophages to mitigate the effects of IL-1 by delivering its inhibitor, IL-1 receptor antagonist (IL-1Ra). Bone marrow-derived macrophages were lentivirally transduced with a synthetic gene circuit that uses an NF-κB inducible promoter upstream of either the Il1rn or firefly luciferase transgenes. Two types of joint like cells were utilized to examine therapeutic protection in vitro, miPSCs derived cartilage and isolated primary mouse synovial fibroblasts while the K/BxN mouse model of RA was utilized to examine in vivo therapeutic protection.ResultsThese engineered macrophages were able to repeatably produce therapeutic levels of IL-1Ra that could successfully mitigate inflammatory activation in co-culture with both tissue-engineered cartilage constructs and synovial fibroblasts. Following injection in vivo, macrophages homed to sites of inflammation and mitigated disease severity in the K/BxN mouse model of RA.ConclusionThese findings demonstrate the successful development of engineered macrophages that possess the ability for controlled, autoregulated production of IL-1 based on inflammatory signaling such as via the NF-κB pathway to mitigate the effects of this cytokine for applications in RA or other inflammatory diseases. This system provides proof of concept for applications in other immune cell types as self-regulating delivery systems for therapeutic applications in a range of diseases.

Identification of citrullinated α1-antitrypsin (A1AT) in saliva in a mouse model of rheumatoid arthritis

ObjectivesRheumatoid arthritis (RA) is an autoimmune disease characterized by progressive joint destruction. Early diagnosis and treatment, before joint deformation or destruction occurs, are crucial. Identifying novel biomarkers for RA in saliva could potentially enable early detection of the disease, prior to its onset. MethodsWe conducted a comprehensive proteomic analysis of salivary proteins in a mouse model of RA. Proteins were identified using western blotting and enzyme-linked immunosorbent assay in the serum, saliva, and ankle joints of DBA/1JJmsSlc mice, a model of RA. Ankle joints and submandibular glands were stained with hematoxylin and eosin and immunostained, and the results were compared with those of control mice. ResultsCitrullinated alpha-1 antitrypsin (A1AT, 46 kDa) was commonly detected in the saliva, serum, and ankle joints of mice with severe RA and was confirmed through proteomic analysis. Western blotting showed a band corresponding to 46 kDa in the serum, saliva, and ankle joints. Immunostaining of the ankle joints with the A1AT antibody showed a strong positive signal in the synovium. ConclusionsIn DBA/1JJmsSlc mice, cyclic citrullinated peptide antibodies and A1AT may be involved in citrullination and contribute to the development and severity of RA, making them valuable treatment targets requiring further study.

Abstract 11 — Development of a Novel Treg Activator KINE-101 for a New Treatment Option for Rheumatoid Arthritis

Background KINE-101, a novel synthetic nonapeptide, is being developed for the treatment of rheumatoid arthritis with a distinctive mode of action. A study using a collagen-induced arthritis (CIA) mouse model showed that KINE-101 suppressed cartilage damage through inhibiting osteoclastogenesis. KINE-101 showed its therapeutic effects in suppressing auto-immune responses by activating Regulatory T cells (Tregs), a specialized subpopulation of T cells, in in-vivo studies using mouse models of RA. Following the in-vivo studies, the phase 1 clinical study for KINE-101 was conducted to assess the safety and tolerability in healthy subjects in the US. Methods Total 40 healthy subjects were enrolled to assign in 5 cohorts. Each cohort included 8 subjects composed of 6 active and 2 placebo treatment. The subjects of first 4 cohorts were administrated with 10, 30, 100, 300 mg of KINE-101 by intravenous (IV) infusion as single ascending doses (SAD), and the Cohort 5 subjects were subcutaneously (SC) injected with 96.8 mg of KINE-101. Results Except for 2 subjects in placebo group, all subjects completed the study. All the randomized subjects were included in the safety evaluation. No deaths, SAEs (Serious Adverse Events), or AEs (Adverse Events) leading to discontinuation were reported during the study periods. While total 9 TEAEs (Treatment-Emergent Adverse Events) were reported, all were assessed as mild. It included 3 headaches, 1 catheter site edema, 1 contusion and 1 nasal congestion in the treatment group, and 1 catheter site pain, 1 oral contusion and 1 COVID-19 infection in the placebo group. Oral contusion and COVID-19 occurred in the same subject, and all the other events were singular TEAEs reported in individual subjects. No injection site reactions were reported and no clinically significant changes in any laboratory values were noted. In terms of pharmacokinetic (PK) profile, KINE-101 was observed in the blood samples during and up to 5 minutes after infusion. Conclusion In the phase I clinical study, Treg activator KINE-101 demonstrated a favorable safety and tolerability profile. The most common AEs were headaches reported in 3 subjects, but all were mild and transient events. As typically seen in peptide drugs, KINE-101 has a short half-life. However, given that KINE-101 uses Treg as a proxy to exerts anti-inflammatory effects, its pharmacodynamic (PD) activity is likely to last longer. The next stage for KINE-101 will proceed to oral formulation and the Phase 2 clinical study in RA patients.

Faecalibacterium prausnitzii alleviates inflammatory arthritis and regulates IL-17 production, short chain fatty acids, and the intestinal microbial flora in experimental mouse model for rheumatoid arthritis

BackgroundRheumatoid arthritis (RA) is a systemic chronic inflammatory disease that leads to joint destruction and functional disability due to the targeting of self-antigens present in the synovium, cartilage, and bone. RA is caused by a number of complex factors, including genetics, environment, dietary habits, and altered intestinal microbial flora. Microorganisms in the gut bind to nod-like receptors and Toll-like receptors to regulate the immune system and produce various metabolites, such as short-chain fatty acids (SCFAs) that interact directly with the host. Faecalibacterium prausnitzii is a representative bacterium that produces butyrate, a well-known immunomodulatory agent in the body, and this microbe exerts anti-inflammatory effects in autoimmune diseases.MethodsIn this study, F. prausnitzii was administered in a mouse model of RA, to investigate RA pathology and changes in the intestinal microbial flora. Using collagen-induced arthritic mice, which is a representative animal model of RA, we administered F. prausnitzii orally for 7 weeks.ResultsThe arthritis score and joint tissue damage were decreased in the mice administered F. prausnitzii compared with the vehicle-treated group. In addition, administration of F. prausnitzii reduced the abundance of systemic immune cells that secrete the pro-inflammatory cytokine IL-17 and induced changes in SCFA concentrations and the intestinal microbial flora composition. It also resulted in decreased lactate and acetate concentrations, an increased butyrate concentration, and altered compositions of bacteria known to exacerbate or improve RA.ConclusionThese results suggest that F. prausnitzii exerts a therapeutic effect on RA by regulation of IL-17 producing cells. In addition, F. prausnitzii modify the microbial flora composition and short chain fatty acids in experimental RA mouse model.

Tanshinone IIA relieves arthritis by inhibiting autophagy of fibroblast-like synoviocytes via matrix metalloproteinase9/receptor for advanced glycation end product/toll-like receptor 9 signal axis in mice with collagen-induced arthritis.

In this study, we probed into the related mechanism underlying the role of Tanshinone IIA (TIIA) in RA fibroblast-like synoviocytes (RA-FLSs). We constructed a mouse model of RA using the collagen-induced arthritis (CIA) method. Gain- or loss-of-function approaches were used to manipulate matrix metalloproteinase9 (MMP9), receptor for advanced glycation end product (RAGE), and toll-like receptor 9 (TLR9) in both CIA mice and RA-FLSs following treatment with TIIA to study the in vivo and in vitro effect of TIIA through analysis of cell viability, and measurement of autophagy and inflammatory proteins as well as severity of RA. In vitro and in vivo animal experiments results showed that TIIA could inhibit the proliferation of RA-FLSs and affect autophagy, thereby improving the symptoms of RA in mice. Mechanically, TIIA could inhibit the expression of MMP9 in RA-FLSs, thereby inhibiting the shedding of RAGE and thus inhibiting the activation of TLR9. Finally, animal experiments confirmed that TIIA affected autophagy by regulating the MMP9/RAGE/TLR9 axis, and finally improve the symptoms of RA in mice. Conclusively, TIIA may inhibit expression of MMP9 to suppress the combination of RAGE and TLR9, thereby inhibiting RA-FLS proliferation and affecting autophagy, eventually improve the RA.

Splenectomy modulates the immune response but does not prevent joint inflammation in a mouse model of RA.

The spleen is the largest secondary lymphoid organ which is involved in the development of B cells and also in systemic (auto)immune responses. Using the recombinant human G1 domain-induced arthritis (GIA) model in splenectomized and control BALB/c mice, we investigated the role of the spleen in the induction and pathogenesis of autoimmune arthritis. Splenectomized mice developed GIA with a similar clinical picture to the control group. However, we observed significant alterations in the humoral and cellular immune responses in splenectomized mice. In the sera of the splenectomized mice, we found lower pro-inflammatory cytokine and anti-rhG1 IgM levels, but higher IL-4, anti-rhG1 IgG1 and anti-CCP and RF antibodies. The arthritis induction in the splenectomized group was associated with a significant expansion of activated helper T cells and an increase in the proportion of the circulating B1 and marginal zone B cell subsets. Importantly, immunization of the splenectomized mice with rhG1 induced the formation of germinal centers in the inguinal- and mesenteric lymph nodes (i/mLNs) which showed an active immune response to rhG1. Finally, both B and T cells from the mLNs of the splenectomized mice showed decreased intracellular Ca2+ signaling than those of the control group. Collectively, these findings indicate that the presence of the spleen is not critical for the induction of GIA, and in its absence the autoimmune arthritis is most likely promoted through the compensatory activity of the i/mLNs. However, our data implies the immunological role of the spleen in arthritis which could be further assessed in human RA.

Bee venom phospholipase A2 alleviates collagen-induced polyarthritis by inducing Foxp3+ regulatory T cell polarization in mice

The mechanism underlying bee venom (BV) therapy is still controversial, with opinions ranging from constituent-based pharmacological action to homeopathic-like activity. The purpose of this study was to examine whether BV phospholipase A2 (bvPLA2), an enzymatic component of BV, is a novel anti-inflammatory and anti-arthritic mediator capable of stimulating CD25+ Foxp3+ regulatory T cell (Treg) polarization in a mouse model of human rheumatoid arthritis (RA). An experimental model of RA was established in male DBA/1 mouse by 2-week-interval injections of 100 μg type II collagen emulsified in complete (first injection) or incomplete Freund’s adjuvant (second injection) at the base of the tail. During arthritis development, bvPLA2 (0.1, 0.5, 1.0 mg/kg) and/or Treg inhibitors such as anti-CD25 antibodies and peptide 60 (P60) were injected intraperitoneally for 5 weeks. Arthritic symptoms and the expansion of Tregs were then assessed by behavioral assessments, histological and micro-CT imaging, and flow cytometry. bvPLA2 injections significantly alleviated arthritic behaviors such as squeaking and joint swelling, consistent with changes seen on both histological and micro-CT images. The anti-arthritic effects of bvPLA2 were blocked by intraperitoneal injections of 0.25 mg/kg anti-CD25 antibody and 10 μg/kg P60, as determined by behavioral assessments. Flow cytometric analysis of dendritic cells, B cells, and major T cell subsets from spleens revealed a significant depletion of Tregs following anti-CD25 antibody, but not P60, treatment. bvPLA2 treatment exerted significant anti-inflammatory and anti-arthritic activities in a mouse model of RA via the induction of Tregs.

TNFα induces endothelial dysfunction in rheumatoid arthritis via LOX-1 and arginase 2: reversal by monoclonal TNFα antibodies.

Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting joints and blood vessels. Despite low levels of low-density lipoprotein cholesterol (LDL-C), RA patients exhibit endothelial dysfunction and are at increased risk of death from cardiovascular complications, but the molecular mechanism of action is unknown. We aimed in the present study to identify the molecular mechanism of endothelial dysfunction in a mouse model of RA and in patients with RA. Endothelium-dependent relaxations to acetylcholine were reduced in aortae of two tumour necrosis factor alpha (TNFα) transgenic mouse lines with either mild (Tg3647) or severe (Tg197) forms of RA in a time- and severity-dependent fashion as assessed by organ chamber myograph. In Tg197, TNFα plasma levels were associated with severe endothelial dysfunction. LOX-1 receptor was markedly up-regulated leading to increased vascular oxLDL uptake and NFκB-mediated enhanced Arg2 expression via direct binding to its promoter resulting in reduced NO bioavailability and vascular cGMP levels as shown by ELISA and chromatin immunoprecipitation. Anti-TNFα treatment with infliximab normalized endothelial function together with LOX-1 and Arg2 serum levels in mice. In RA patients, soluble LOX-1 serum levels were also markedly increased and closely related to serum levels of C-reactive protein. Similarly, ARG2 serum levels were increased. Similarly, anti-TNFα treatment restored LOX-1 and ARG2 serum levels in RA patients. Increased TNFα levels not only contribute to RA, but also to endothelial dysfunction by increasing vascular oxLDL content and activation of the LOX-1/NFκB/Arg2 pathway leading to reduced NO bioavailability and decreased cGMP levels. Anti-TNFα treatment improved both articular symptoms and endothelial function by reducing LOX-1, vascular oxLDL, and Arg2 levels.

Monocytic MDSCs skew Th17 cells toward a pro-osteoclastogenic phenotype and potentiate bone erosion in rheumatoid arthritis.

While myeloid-derived suppressor cells (MDSCs) were previously shown to promote a proinflammatory T helper (Th) 17 response in autoimmune conditions, a potential impact of the MDSC-Th17 immune axis on abnormal bone destruction in RA remains largely unknown. We investigated the correlation between the frequency of MDSCs or its subsets and joint destruction in RA patients. The reciprocal actions of patient-derived MDSCs and Th17 cells were studied using osteoclast (OC) differentiation and bone resorption assays in vitro, which were further validated using mouse models of RA. Contribution of MDSCs to osteoclastogenesis and bone erosion in vivo was determined by depletion or transfer of MDSCs. Human MDSCs, particularly monocytic MDSCs (M-MDSCs), exhibit inherent OC-differentiating capacity and positively correlate with clinical bone erosion in RA patients. Strikingly, patient-derived M-MDSCs can program Th17 cells towards a pro-osteoclastogenic phenotype, which in return potentiates OC differentiation via the receptor activator of nuclear factor κΒ ligand (RANK-L)-RANK signalling. This enhanced osteolysis driven by the reciprocal actions of M-MDSCs and Th17 cells is further confirmed using mouse models of RA. Selective depletion of M-MDSCs significantly ameliorates osteoclastogenesis and disease severity in arthritic mice, whereas transfer of M-MDSCs aggravates bone erosion associated with increased OCs in recipient mice. Our findings highlight the functional plasticity of MDSCs and identify a novel pro-osteoclastogenic pathway governed by interplay between myeloid cells and T lymphocytes in autoimmune RA.

Targeted photodynamic therapy selectively kills activated fibroblasts in experimental arthritis

ObjectiveIn RA, synovial fibroblasts become activated. These cells express fibroblast activation protein (FAP) and contribute to the pathogenesis by producing cytokines, chemokines and proteases. Selective depletion in inflamed joints could therefore constitute a viable treatment option. To this end, we developed and tested a new therapeutic strategy based on the selective destruction of FAP-positive cells by targeted photodynamic therapy (tPDT) using the anti-FAP antibody 28H1 coupled to the photosensitizer IRDye700DX.MethodsAfter conjugation of IRDye700DX to 28H1, the immunoreactive binding and specificity of the conjugate were determined. Subsequently, tPDT efficiency was established in vitro using a 3T3 cell line stably transfected with FAP. The biodistribution of [111In]In-DTPA-28H1 with and without IRDye700DX was assessed in healthy C57BL/6N mice and in C57BL/6N mice with antigen-induced arthritis. The potential of FAP-tPDT to induce targeted damage was determined ex vivo by treating knee joints from C57BL/6N mice with antigen-induced arthritis 24 h after injection of the conjugate. Finally, the effect of FAP-tPDT on arthritis development was determined in mice with collagen-induced arthritis.Results28H1-700DX was able to efficiently induce FAP-specific cell death in vitro. Accumulation of the anti-FAP antibody in arthritic knee joints was not affected by conjugation with the photosensitizer. Arthritis development was moderately delayed in mice with collagen-induced arthritis after FAP-tPDT.ConclusionHere we demonstrate the feasibility of tPDT to selectively target and kill FAP-positive fibroblasts in vitro and modulate arthritis in vivo using a mouse model of RA. This approach may have therapeutic potential in (refractory) arthritis.

In Vitro ELISA and Cell-Based Assays Confirm the Low Immunogenicity of VNAR Therapeutic Constructs in a Mouse Model of Human RA: An Encouraging Milestone to Further Clinical Drug Development.

Anti-drug antibodies (ADAs), specific for biotherapeutic drugs, are associated with reduced serum drug levels and compromised therapeutic response. The impact of ADA on the bioavailability and clinical efficacy of blockbuster anti-hTNF-α monoclonal antibodies is well recognised, especially for adalimumab and infliximab treatments, with the large and complex molecular architecture of classical immunoglobulin antibody drugs, in part, responsible for the immunogenicity seen in patients. The initial aim of this study was to develop solid-phase enzyme-linked immunosorbent assays (ELISA) and an in vitro cell-based method to accurately detect ADA and estimate its impact on the preclinical in vivo efficacy outcomes of two novel, nonimmunoglobulin VNAR fusion anti-hTNF-α biologics (Quad-X™ and D1-NDure™-C4) and Humira®, a brand of adalimumab. Serum drug levels and the presence of ADA were determined in a transgenic mouse model of polyarthritis (Tg197) when Quad-X™ and Humira® were dosed at 1 mg/kg and D1-NDure™-C4 was dosed at 30 mg/kg. The serum levels of the Quad-X™ and D1-NDure™-C4 modalities were consistently high and comparable across all mice within the same treatment groups. In 1 mg/kg and 3 mg/kg Quad-X™- and 30 mg/kg D1-NDure™-C4-treated mice, an average trough drug serum concentration of 8 μg/mL, 50 μg/mL, and 350 μg/mL, respectively, were estimated. In stark contrast, Humira® trough serum concentrations in the 1 mg/kg treatment group ranged from <0.008 μg/mL to 4 μg/mL with trace levels detected in 7 of the 8 animals treated. Trough serum Humira® and Quad-X™ concentrations in 3 mg/kg treatment samples were comparable; however, the functionality of the detected Humira® serum was significantly compromised due to neutralising ADA. The impact of ADA went beyond the simple and rapid clearance of Humira®, as 7/8 serum samples also showed no detectable capacity to neutralise hTNF-α-mediated cytotoxicity in a murine fibrosarcoma (L929) cell assay. The neutralisation capacity of all the VNAR constructs remained unchanged at the end of the experimental period (10 weeks). The data presented in this manuscript goes some way to explain the exciting outcomes of the previously published preclinical in vivo efficacy data, which showed complete control of disease at Quad-X™ concentrations of 0.5 mg/kg, equivalent to 10x the in vivo potency of Humira®. This independent corroboration also validates the robustness and reliability of the assay techniques reported in this current manuscript, and while it comes with the caveat of a mouse study, it does appear to suggest that these particular VNAR constructs, at least, are of low inherent immunogenicity.

Longitudinal micro-CT as an outcome measure of interstitial lung disease in TNF-transgenic mice.

IntroductionRheumatoid arthritis associated interstitial lung disease (RA-ILD) is a debilitating condition with poor survival prognosis. High resolution computed tomography (CT) is a common clinical tool to diagnose RA-ILD, and is increasingly being adopted in pre-clinical studies. However, murine models recapitulating RA-ILD are lacking, and CT outcomes for inflammatory lung disease have yet to be formally validated. To address this, we validate μCT outcomes for ILD in the tumor necrosis factor transgenic (TNF-Tg) mouse model of RA.MethodsCross sectional μCT was performed on cohorts of male TNF-Tg mice and their WT littermates at 3, 4, 5.5 and 12 months of age (n = 4–6). Lung μCT outcomes measures were determined by segmentation of the μCT datasets to generate Aerated and Tissue volumes. After each scan, lungs were obtained for histopathology and 3 sections stained with hematoxylin and eosin. Automated histomorphometry was performed to quantify the tissue area (nuclei, cytoplasm, and extracellular matrix) and aerated area (white space) within the tissue sections. Spearman’s correlation coefficients were used to evaluate the extent of association between μCT imaging and histopathology endpoints.ResultsTNF-Tg mice had significantly greater tissue volume, total lung volume and mean intensity at all timepoints compared to age matched WT littermates. Histomorphometry also demonstrated a significant increase in tissue area at 3, 4, and 5.5 months of age in TNF-Tg mice. Lung tissue volume was correlated with lung tissue area (ρ = 0.81, p<0.0001), and normalize lung aerated volume was correlated with normalized lung air area (ρ = 0.73, p<0.0001).ConclusionsWe have validated in vivo μCT as a quantitative biomarker of ILD in mice. Further, development of longitudinal measures is critical for dissecting pathologic progression of ILD, and μCT is a useful non-invasive method to study lung inflammation in the TNF-Tg mouse model.

Elevated frequency of producing IL-17A Neutrophils in peripheral blood from patients with RA

Abstract Introduction Rheumatoid Arthritis (RA) is a systemic and chronic inflammatory disease, which affects 1–1.5% of population worldwide. Synovial membrane, cartilage and bone are the main sites affected by inflammation. The inflammatory process in RA leads to increased production of inflammatory cytokines IL-8, TNF-a, IL-6, IL-1b, IL-15, IL-18 e IL-17A in synovial fluid and serum. In addition to Th17, others cells such as gd T cells, iNKTs, mast cells and neutrophils also produce IL-17A. In mouse model of RA, IL-17A producing neutrophils seems to be important for the onset of the disease. Thus, we hypothesize that the population of IL-17A producing neutrophils is increased in patients with RA. Objective To analyze the frequency of IL-17A producing neutrophils in peripheral blood of patients with RA. Methods Peripheral blood from 68 patients with rheumatoid arthritis and 15 healthy donors has been collected, erythrocytes were lysed and peripheral blood leukocytes were stained for surface marker CD177 and for intracellular detection of IL-17A. Cells were analyzed by flow cytometry. It was also evaluated the frequency TH17 cells by flow cytometry using standard protocol. Results IL-17A producing neutrophils are increased in peripheral blood of patients with RA (0–19.5% Mean 1.66%) compared with healthy donors where no neutrophils IL-17A+ were observed (0–0.1% mean 0.05%). Surprisingly, Th17 cells were not detected in peripheral blood of patients with RA. Conclusion Neutrophils might be the most important source of IL-17A during the inflammatory response observed in patients with RA since we do not detect TH17 cells in these patients.

Adoptive transfer of a novel MIF receptor (CD74+) expressing memory T cell subpopulation is sufficient to transfer inflammatory arthritis

Abstract Rheumatoid arthritis (RA) is characterized by relapsing disease and progressive autoimmune joint destruction. The mechanism(s) for disease recurrence in previously affected joints is unknown. High expression alleles of the cytokine macrophage migration inhibitory factor (MIF) are associated with severe erosive RA. We report a novel subpopulation of T cells expressing the MIF receptor CD74, which previously has not been considered to be present in T lineage cells. CD74+ T cells comprise 1% of lymph node T cell and exhibit an effector memory phenotype (CD3+ CD74+ CD44+, CD62Llow). Notably, whole genome expression profiling (RNAseq) of CD74+ T cells revealed reduced expression of the immune checkpoint Ctla4 (3.5-fold, p=0.009), and increased expression of Stat4 and Ptpn22 (1.4-fold, p=0.001 and 0.86-fold, p=0.045), three genes that regulate T cell activation and also are linked genetically to RA pathogenesis. In the collagen-induced arthritis (CIA) mouse model of RA, we observed a 2-fold (p=0.023) expansion of CD74+ T cells after disease induction when compared to Mif−/− mice, which show no expansion of CD74+ T cells and reduced disease severity (disease score: WT: 7.8; Mif −/−: 1.4, p&amp;gt;0.001). Notably, adoptive transfer of CD74+ T cells from mice with established CIA into naive mice recapitulated joint inflammation (disease score: 4.3, p=0.001). Disease was not detectable in naïve mice that received CD74-T cells from CIA hosts. This study identifies a novel population of effector memory T cells that are capable of transferring autoimmune joint inflammation. We hypothesize that MIF responsive CD74+ effector memory T cells mediate recurrent joint inflammation and may be amenable to specific targeting by emerging MIF-directed therapies.

CD73 plays a protective role in collagen-induced arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease with significant morbidity and mortality. Recent studies suggest that modulation of adenosine signaling, a potent immunosuppressive pathway, is a promising approach for treatment of RA. Extracellular adenosine can come from two sources: transport of intracellular adenosine and hydrolysis of extracellular adenine nucleotides by CD73. In this study, we investigated the susceptibility of CD73-deficient C57BL/6 mice to collagen-induced arthritis (CIA), a well-established mouse model of RA. Our data demonstrated that CD73-deficient mice are significantly more susceptible to CIA than wild-type mice. CD73 deficiency resulted in an increased production of proinflammatory cytokines in the joints, increased Th1 T cell responses, and increased joint destruction. Surprisingly, this was accompanied by delayed anticollagen IgG responses, suggesting defective isotype class switching in CD73-deficient mice. Using bone marrow chimera mice, we demonstrated that CD73 expression on nonhematopoietic cells, but not on hematopoietic cells, was important for protection from CIA. We further demonstrated that administration of a selective A2A adenosine receptor agonist to CD73-deficient mice resulted in arthritis incidence similar to wild-type mice in support of a protective role for A2A signaling. Taken together, our study identifies CD73 as an important regulator of CIA in mice. It also strengthens the notion that CD73-generated adenosine by nonhematopoietic cells plays a protective role in RA and suggests that strategies able to enhance CD73 activity or expression levels may be a valid therapeutic option.

NR4A2 Expression Patterns in Mouse Models of Rheumatoid Arthritis

Arthritis is a group of over 100 musculoskeletal disorders affecting approximately 50 million adults in the US. In an effort to develop new drugs to treat arthritis, we are exploring the function of the orphan nuclear receptor 4A2 (NR4A2), a transcription factor over-expressed in inflamed joints. The transcriptional targets of NR4A2 include angiogenesis factors and matrix metalloproteinases (MMPs). NR4A2 appears to have a deleterious effect in synoviocytes by promoting tissue degradation, while in chondrocytes it seems to have a protective function. Previous work on human synoviocytes has shown NR4A2 to rise early in response to inflammation, leading us to hypothesize that NR4A2 may be a preliminary mediator of arthritis. To test this hypothesis in vivo, we studied NR4A2 expression patterns in two mouse models of RA: Antigen Induced Arthritis (AIA) and Serum Transfer Arthritis (STA). Tissue sections were obtained from healthy and arthritic mice at early, mid, and late time-points following induction. Joint cross-sections were examined via immunohistochemical staining, and NR4A2 positive cells were quantified in synovial and cartilage tissues. In the AIA model, NR4A2 protein levels peaked in synovium at day 10 of disease (mid stage, 50% positive) and declined later in disease. In cartilage, protein levels reached a maximum at day 8 (early stage, 70%) and subsequently declined as well. In contrast, NR4A2 was not expressed in the STA model, despite apparent joint degradation. NR4A2 has been shown to be expressed in STA arthritis by other researchers, so it is unknown why STA samples did not show NR4A2 expression in our experiment.

A1.70 Sterile inflammation occurs in a TLR9-independent manner in experimental arthritis and rheumatoid arthritis

Background and ObjectivesRheumatoid arthritis (RA) is an inflammatory disease of unknown etiology. Toll-like receptor (TLR) 9 recognizes pathogen-derived DNA and even self DNA under certain circumstances. Interestingly, environmental factors and...

Myeloid-Derived Suppressor Cells Protect Mouse Models from Autoimmune Arthritis via Controlling Inflammatory Response

Myeloid-derived suppressor cells (MDSCs) have been reported to participate in immune suppression and autoimmune disorders. However, its role in autoimmune arthritis remains to be determined. We explored whether adoptive transfer of MDSCs in vivo would block joint inflammation and histological damage using collagen-induced arthritis (CIA) and antigen-induced arthritis (AIA) models. CD11b(+) Gr-1(+) MDSCs were isolated from the single cells from the spleens of CIA mice on day 41 or AIA mice on day 35. MDSCs (2 × 10(6)) were then transferred to AIA and CIA mice via tail vein before arthritis establishment at indicated time points. Phosphate buffered saline (PBS) was injected as control. Arthritis was evaluated by severity score and histology. The levels of TNF-α, IL-6, IL-17 and IL-10 in the serum and joints were detected by enzyme-linked immunosorbent assay (ELISA). The number of Th17 cells and macrophages in draining lymph nodes and joint tissues was assessed by flow cytometric analysis. Adoptive transfer of MDSCs significantly reduced the clinical score of arthritis, alleviated joint inflammation and histological damage both in AIA and CIA models compared with PBS-treated control groups. The levels of TNF-α, IL-6, IL-17, and IL-10 in the serum and joints were down-regulated by transfer of MDSCs. In addition, adoptive transfer of MDSCs significantly reduced the number of Th17 cells and macrophages in draining lymph nodes and joint tissues. Altogether, we demonstrate that adoptive transfer of MDSCs prevented autoimmune arthritis in mouse models of RA through inhibiting Th17 cells and macrophages. These new findings provide insights into the inhibitory functions of MDSCs and MDSCs may be used as a cell-based biotherapy in RA.

OP0185 Endogenous B Cell-Targeted Antigen Expression Induces Tolerance to Collagen Type II Arthritis in Mice

BackgroundRheumatoid arthritis (RA) is a destructive autoimmune disease. Today’s treatment is associated with side effects and only suppresses the disease. A safe and effective therapy would be to re-establish tolerance,...

THU0018 Sumo specific proteases 5 and 7 contribute to the inbalanced sumoylation level of rheumatoid athritis synovial fibroblasts

BackgroundIt has been shown previousely that posttranslational protein modification through SUMOylation is enhanced in rheumatoid athritis synovial fibroblasts (RASF) compared to osteoathritis synovial fibroblasts (OASF) and that higher levels of...