Development Of Arthritis In Mice Research Articles

Contribution of soluble epoxide hydrolase-generated metabolites to nociception, physical mobility and arthritis development in mice

Introduction: To determine if soluble epoxide hydrolase (sEH) is associated with nociception, mobility and arthritis development.

Muscadine Grape and Wine Polyphenols Alleviated the Severity of Collagen Induced Arthritis in Mice

Abstract Objectives The aim of this study was to investigate the effect of concentrated muscadine grape polyphenols (MGP) and muscadine wine polyphenols (MWP) on the onset and progression of collagen induced arthritis (CIA) in mice. Methods MGP and MWP were concentrated using Amberlite XAD16N resin. Polyphenol composition was determined on HPLC. Male DBA/1 mice were divided into four treatment groups as (1) healthy control, (2) CIA control, (3) CIA + MWP, and (4) CIA + MGP. Arthritis was induced by intradermal injection of type II collagen on days 0 and day 21. Mice in groups 3 and 4 were gavaged with MWP and MGP using a dose of 400 mg/kg body weight for a total of 21 days. Severity of CIA was evaluated using clinical arthritic score and inflammation in the hind-paws. Plasma levels of cytokines, proteases, and anti-collagen antibody were measured using ELISA. Results MGP and MWP contained anthocyanin 3, 5-diglucosides, flavonols, and ellagic acid. Mice in the CIA control group had an onset of arthritis on day 18, which was delayed to day 22 and 24 by MWP and MGP, respectively (P < 0.05). Severity of arthritis was much lower in mice gavaged with muscadine polyphenols after the onset. On day 42, the average arthritic score of mice in the CIA control group progressed to 7.75 on a scale of 0–16, while MGP and MWP significantly reduced this score to 3.75 and 4.00, respectively (P < 0.01). In addition, MGP and MWP significantly reduced the plasma concentration of TNF-α, IL-6, anti-collagen antibodies, and matrix metalloproteinase-3 in CIA mice but not to the same level of healthy mice. The plasma concentration of IL-17 was drastically elevated in CIA mice, but it was not affected by MWP or MGP like other cytokines. This suggested that muscadine polyphenols had limited impact on the Th17 cells in the immune system. Mice gavaged with MPG and MWP had comparable plasma cytokine content, suggesting similar anti-inflammation activity. Conclusions Muscadine grape and wine polyphenols blunt the development of arthritis in mice by reducing the levels of key inflammatory cytokines, antibodies, and proteases, and may offer a promising dietary approach to manage arthritic symptoms. Funding Sources Florida Department of Agriculture and Consumer Service and Florida Viticulture Advisory Council.

Blocking Interleukin-33 Alleviates the Joint Inflammation and Inhibits the Development of Collagen-Induced Arthritis in Mice.

Rheumatoid arthritis (RA) is considered a systemic chronic inflammatory joint disease characterized by chronic synovitis and cartilage and bone destruction. Interleukin-33 (IL-33) is a proinflammatory cytokine which is highly expressed in the synovium of RA patients and the joints of mice with collagen-induced arthritis (CIA) and exacerbates CIA in mice. However, the role of the IL-33-neutralizing antibody in the murine model of CIA remains unclear. In the present study, CIA mice were given intraperitoneally with polyclonal rabbit anti-murine IL-33 antibody (anti-IL-33) or normal rabbit IgG control after the first signs of arthritis. Administration of anti-IL-33 after the onset of disease significantly reduced the severity of CIA and joint damage compared with controls treated with normal rabbit IgG. Anti-IL-33 treatment also significantly decreased the serum levels of interferon-γ(IFN-γ),IL-6, IL-12, IL-33, and tumor necrosis factor-α (TNF-α). Moreover, anti-IL-33 treatment significantly downregulated the production of IFN-γ, IL-6, IL-12, IL-33, and TNF-α in ex vivo-stimulated spleen cells. Together, our results indicate that the IL-33-neutralizing antibody may provide a therapeutic strategy for RA by inhibiting the release of proinflammatory cytokines.

Infection With Clostridioides difficile Attenuated Collagen-Induced Arthritis in Mice and Involved Mesenteric Treg and Th2 Polarization.

ObjectivesRheumatoid arthritis is an autoimmune disease with multifactorial etiopathogenesis. Among the environmental factors, mucosal infections and the inducing pathobionts are gaining increasing attention. We here set out to explore the gut-joint-axis and the impact of Clostridioides difficile infection on subsequent arthritis.MethodsWe combined C. difficile infection in DBA/1J × B10.Q F1 mice with collagen induced arthritis (CIA). Mice were infected via oral gavage and infection was monitored by weight loss, colonic histology, and antibodies against bacteria. Scoring of arthritis was performed macroscopically. Intestinal microbiomes were analyzed and immune responses were monitored via quantification of transcription factor-specific mRNA isolated from the inguinal and mesenteric lymph nodes.ResultsInfection with C. difficile VPI 10463 resulted in significant weight loss and severe colitis yet accelerated the reversal towards the original microbiome after antibiotic treatment. Spontaneous clearance of VPI 10463 infection reduced the incidence of subsequent CIA and led to mesenteric Treg and Th2 polarization. However, this attenuating effect was abrogated if VPI 10463 was eradicated via vancomycin followed by fecal microbiota transplantation. Moreover, VPI 10463 infection following the onset of CIA lacked therapeutic potential.ConclusionOur results demonstrate that infection with C. difficile VPI10463 induced an inflammation of the gut that protected from subsequent arthritis development in mice. Both, microbial changes to the gut and immune cell mobilization and/or polarization may have contributed to arthritis protection. The prospect of potential therapeutic benefits resulting from C. difficile infections or some byproduct thereof call for further experiments that help elucidate exact mechanisms.

Concomitant Treatment with Etanercept and Tacrolimus Synergistically Attenuates Arthritis Progression via Inhibition of Matrix Metalloproteinase-3 Production and Osteoclastogenesis in Human TNF-α Transgenic Mice.

In the present study, we investigated the effects and mechanisms of action of a combined treatment with etanercept, a soluble tumor necrosis factor receptor (p75) Fc fusion protein, and tacrolimus, a calcineurin inhibitor on the progression of arthritis in human tumor necrosis factor-α (TNF-α) transgenic (hTNF-Tg) mice. Single-drug treatments with etanercept and tacrolimus attenuated the clinical signs but not the radiographic changes associated with the development of arthritis in mice. On the contrary, combined treatment significantly suppressed the radiographic progression and also improved the clinical signs. The combined treatment exhibited synergistic effects of the two drugs in reducing the serum matrix metalloproteinase-3 level and the number of peripheral CD11bhigh osteoclast precursor cells. Moreover, tacrolimus inhibited the cytokine-induced osteoclast differentiation in synergy with etanercept in an in vitro assay. Interestingly, tacrolimus did not inhibit the production of antidrug antibodies (ADAs) against etanercept in the hTNF-Tg mice. This result implies that the synergistic effects of etanercept and tacrolimus are not due to secondary effects derived from the suppression of ADA production by tacrolimus but are due to their primary effects. These findings suggest that concomitant treatment with etanercept and tacrolimus may be one of preferable treatment options to control disease activities for patients with rheumatoid arthritis, especially for those with bone resorption.

Experimental colitis delays and reduces the severity of collagen-induced arthritis in mice.

Amongst extraintestinal manifestations (EIM) occurring in IBD patients, rheumatologic manifestations are the most frequent. Understanding the relationships between arthritis and colitis is a prerequisite to improving the management of these patients. Microbiota of patients with IBD or rheumatologic diseases, like spondyloarthritis (SpA) is modified compared to healthy individual. Thus, we have evaluated the impact of colitis in the development of arthritis in mice and we have analyzed microbiota changes. Collagen-induced arthritis (CIA) was induced at day 0 in DBA1 mice exposed or not to Dextran Sodium Sulfate (DSS) to induce colitis between day 14 and day 21. Animals were monitored regularly for arthritis and colitis severity (clinical score, hindpaw edema). Fecal microbiota was studied by 16S rRNA deep sequencing at critical time points (D14, D14, D21 & D41). At day 41, histological scoring of the intestines and ankles were performed at the end of experiment. Induction of colitis slightly delayed arthritis onset (2 ± 1 days of delay) and reduced its severity (5.75 ± 1.62 in arthritis only group vs 4.00 ± 1.48 in arthritis + colitis group (p = 0.02 at day 28) macroscopically and histologically. In contrast, colitis severity was not influenced by arthritis development. Induction of colitis promoted a modification of microbiota composition and a decrease of α-diversity. Fecal microbiota composition was different between “colitis” and “arthritis+colitis” groups during colitis development. Interestingly a milder decrease of bacterial diversity in the “arthritis+colitis” group was observed. Concomitant experimental colitis protects mice against collagen-induced arthritis and this is associated with changes in gut microbiome composition.

Oral administration of apple condensed tannins delays rheumatoid arthritis development in mice via downregulation of T helper 17 (Th17) cell responses.

Apples are known to contain high concentrations of phenolic compounds such as condensed tannins. Consumption of condensed tannins has been reported to reduce the risk of many types of chronic diseases including allergies. However, their therapeutic effectiveness and potential in treating autoimmune disease remain controversial. Here, the effect of oral administration of apple condensed tannins (ACT) prepared from apples (Malus pumila cv. Fuji) on bovine type II collagen (CII)-induced arthritis in DBA1/J mice, a well-established murine model of human rheumatoid arthritis (RA), was evaluated. As compared to the control (without ACT administration) group, RA development was delayed and a significant reduction in the RA clinical score was observed in the ACT-administered group. Using cultured splenocytes isolated from CII-immunized mice, ACT-administration was shown to decrease the CII-induced increases in IL-17 expression and production in vitro. We propose that downregulation of T helper (Th) 17 cells is responsible for the ACT-induced RA suppression.

Pathogenic functions of B cells in autoimmune diseases: IFN-γ production joins the criminal gang.

B-cell depletion therapy has emerged as a powerful strategy to intercept the progression of T-cell-mediated autoimmune diseases such as rheumatoid arthritis, type 1 diabetes, or relapsing remitting multiple sclerosis. However, its mode of action remains incompletely defined, reflecting our incomplete understanding of the pathogenic functions of B cells in such pathologies. B cells can contribute to immune responses through the production of antibodies, presentation of antigen to T cells, and production of cytokines. In this issue of the European Journal of Immunology [Eur. J. Immunol. 2015. 45: 988-998], Olalekan etal. demonstrate that IFN-γ production by B cells is essential for the development of arthritis in mice. Lack of IFN-γ expression in B cells results in reduced autoimmune T-cell responses and autoantibody levels, impacting the arthritogenic reaction akin to that in B-cell depletion therapy. Together with other reports, the article by Olalekan etal. emphasizes the importance of cytokine-producing B cells in the pathogenesis of autoimmune diseases. In this commentary, I discuss how these findings shed new light on the roles of B cells as drivers of autoimmune pathogenesis, and how they more generally contribute to our understanding of the role of B cells in immunity.

Decorin binding proteins of Borrelia burgdorferi promote arthritis development and joint specific post-treatment DNA persistence in mice.

Decorin binding proteins A and B (DbpA and B) of Borrelia burgdorferi are of critical importance for the virulence of the spirochete. The objective of the present study was to further clarify the contribution of DbpA and B to development of arthritis and persistence of B. burgdorferi after antibiotic treatment in a murine model of Lyme borreliosis. With that goal, mice were infected with B. burgdorferi strains expressing either DbpA or DbpB, or both DbpA and B, or with a strain lacking the adhesins. Arthritis development was monitored up to 15 weeks after infection, and bacterial persistence was studied after ceftriaxone and immunosuppressive treatments. Mice infected with the B. burgdorferi strain expressing both DbpA and B developed an early and prominent joint swelling. In contrast, while strains that expressed DbpA or B alone, or the strain that was DbpA and B deficient, were able to colonize mouse joints, they caused only negligible joint manifestations. Ceftriaxone treatment at two or six weeks of infection totally abolished joint swelling, and all ceftriaxone treated mice were B. burgdorferi culture negative. Antibiotic treated mice, which were immunosuppressed by anti-TNF-alpha, remained culture negative. Importantly, among ceftriaxone treated mice, B. burgdorferi DNA was detected by PCR uniformly in joint samples of mice infected with DbpA and B expressing bacteria, while this was not observed in mice infected with the DbpA and B deficient strain. In conclusion, these results show that both DbpA and B adhesins are crucial for early and prominent arthritis development in mice. Also, post-treatment borrelial DNA persistence appears to be dependent on the expression of DbpA and B on B. burgdorferi surface. Results of the immunosuppression studies suggest that the persisting material in the joints of antibiotic treated mice is DNA or DNA containing remnants rather than live bacteria.

Rehabilitation or the death penalty: Autoimmune B cells in the dock

CD20-based monoclonal antibodies have become established as treatments for lymphoma, rheumatoid arthritis, systemic lupus erythematosus, vasculitis and dermatomyositis, with the principle therapeutic mechanism relating to B-cell depletion through effector cell engagement. An article by Brühl et al. in this issue of the European Journal of Immunology [Eur. J. Immunol. 2015. 45: 705-715] reveals a fundamentally distinct mechanism of silencing autoimmune B-cell responses. Rather than B-cell depletion, the authors use anti-CD79b antibodies to induce B-cell tolerance and suppress humoral immune responses against collagen to prevent the development of arthritis in mice. Here we highlight the differences in the mechanisms used by anti-CD20 and anti-CD79b Ab therapy and discuss why depletion of B cells may not be required to treat autoimmune arthritis and other B-cell-associated pathologies.

Peptidyl Arginine Deiminase from Porphyromonas gingivalis Abolishes Anaphylatoxin C5a Activity

Evasion of killing by the complement system, a crucial part of innate immunity, is a key evolutionary strategy of many human pathogens. A major etiological agent of chronic periodontitis, the Gram-negative bacterium Porphyromonas gingivalis, produces a vast arsenal of virulence factors that compromise human defense mechanisms. One of these is peptidylarginine deiminase (PPAD), an enzyme unique to P. gingivalis among bacteria, which converts Arg residues in polypeptide chains into citrulline. Here, we report that PPAD citrullination of a critical C-terminal arginine of the anaphylatoxin C5a disabled the protein function. Treatment of C5a with PPAD in vitro resulted in decreased chemotaxis of human neutrophils and diminished calcium signaling in monocytic cell line U937 transfected with the C5a receptor (C5aR) and loaded with a fluorescent intracellular calcium probe: Fura-2 AM. Moreover, a low degree of citrullination of internal arginine residues by PPAD was also detected using mass spectrometry. Further, after treatment of C5 with outer membrane vesicles naturally shed by P. gingivalis, we observed generation of C5a totally citrullinated at the C-terminal Arg-74 residue (Arg74Cit). In stark contrast, only native C5a was detected after treatment with PPAD-null outer membrane vesicles. Our study suggests reduced antibacterial and proinflammatory capacity of citrullinated C5a, achieved via lower level of chemotactic potential of the modified molecule, and weaker cell activation. In the context of previous studies, which showed crosstalk between C5aR and Toll-like receptors, as well as enhanced arthritis development in mice infected with PPAD-expressing P. gingivalis, our findings support a crucial role of PPAD in the virulence of P. gingivalis.

OP0174 Ppar Gamma Deficient Mice Develop Spontaneous Polyarthritis

BackgroundPeroxisome proliferator-activated receptor gamma (PPARγ) is a member of the nuclear receptor superfamily of transcription factors. PPARγ is involved in the regulation of adipocyte differentiation, glucose homeostasis and inflammation. Others...

Inhibition of Connective Tissue Growth Factor Ameliorates Disease in a Murine Model of Rheumatoid Arthritis

We have shown that connective tissue growth factor (CTGF) plays an important role in the pathogenesis of rheumatoid arthritis (RA). This study was undertaken to evaluate the effects of blockade of the CTGF pathway on the development of collagen-induced arthritis (CIA) in mice. Arthritis was induced in DBA/1J mice by immunization with a combination of type II collagen (CII) and Freund's complete adjuvant. We evaluated the development of arthritis in mice with CIA left untreated versus treated with neutralizing anti-CTGF monoclonal antibody (mAb). Inhibition of CTGF in mice treated with neutralizing anti-CTGF mAb significantly ameliorated arthritis compared to the untreated mice with CIA. Serum levels of matrix metalloproteinase 3 were reduced by anti-CTGF mAb treatment. Moreover, blockade of CTGF decreased interleukin-17 expression on purified CD4+ T lymphocytes. Although the expression of the retinoic acid receptor-related orphan receptor γt gene was not suppressed by anti-CTGF mAb treatment, that of interferon regulatory factor 4 (IRF-4) and IκBζ (Nfkbiz), which are other important molecules for the differentiation of Th17 cells, was suppressed. In addition, blockade of CTGF inhibited pathologic proliferation of T lymphocytes in response to CII restimulation in vitro. Moreover, aberrant osteoclastogenesis in mice with CIA was restored by anti-CTGF mAb treatment. Our findings indicate that blockade of CTGF prevents the progression of arthritis in mice with CIA. Anti-CTGF mAb treatment suppresses pathologic T cell function and restores aberrant osteoclastogenesis in mice with CIA. CTGF may become a new target for the treatment of RA.

Genetic control of antibody production during collagen‐induced arthritis development in heterogeneous stock mice

To identify genetic factors driving pathogenic autoantibody formation in collagen-induced arthritis (CIA), a mouse model of rheumatoid arthritis (RA), in order to better understand the etiology of RA and identify possible new avenues for therapeutic intervention. We performed a genome-wide analysis of quantitative trait loci controlling autoantibody to type II collagen (anti-CII), anti-citrullinated protein antibody (ACPA), and rheumatoid factor (RF). To identify loci controlling autoantibody production, we induced CIA in a heterogeneous stock-derived mouse cohort, with contribution of 8 inbred mouse strains backcrossed to C57BL/10.Q. Serum samples were collected from 1,640 mice before arthritis onset and at the peak of the disease. Antibody concentrations were measured by standard enzyme-linked immunosorbent assay, and linkage analysis was performed using a linear regression-based method. We identified loci controlling formation of anti-CII of different IgG isotypes (IgG1, IgG3), antibodies to major CII epitopes (C1, J1, U1), antibodies to a citrullinated CII peptide (citC1), and RF. The anti-CII, ACPA, and RF responses were all found to be controlled by distinct genes, one of the most important loci being the immunoglobulin heavy chain locus. This comprehensive genetic analysis of autoantibody formation in CIA demonstrates an association not only of anti-CII, but interestingly also of ACPA and RF, with arthritis development in mice. These results underscore the importance of non-major histocompatibility complex genes in controlling the formation of clinically relevant autoantibodies.

Genetic control of antibody production during collagen induced arthritis development in heterogeneous stock mice (171.44)

Abstract The aim of this study was to identify genetic factors driving pathogenic autoantibody formation in collagen induced arthritis (CIA), a mouse model for rheumatoid arthritis (RA) in order to understand the etiology of the disease and improve possibilities for therapeutic intervention. To this end we made a genome wide analysis of quantitative trait loci (QTL) controlling autoantibodies towards type II collagen (AC2A), anti-citrullinated protein antibodies (ACPA) and rheumatoid factors (RF). To identify loci controlling autoantibody production, we induced CIA in a heterogeneous stock (HS) derived mouse cohort. Serum samples of 1843 mice were collected before onset and at peak of the disease. All antibody concentrations were measured by ELISA and linkage analysis was performed using a linear regression based method. We identified loci controlling formation of AC2A of different IgG isotypes, antibodies to major type II collagen (CII) epitopes, to a citrullinated CII peptide and RF. The AC2A, ACPA and RF responses were all found to be controlled by distinct genes, one of the most important loci being the Immunoglobulin heavy chain (IgH) locus. Here, we provide a comprehensive genetic analysis of autoantibody formation in CIA. Our study demonstrates that not only AC2A, but interestingly also ACPA and RF are associated with arthritis development in mice. These results underscore the importance of non-MHC genes controlling the formation of clinically relevant autoantibodies.

RNAi mediated silencing of hnRNP-A2 decreases collagen-induced arthritis by inhibiting proliferation and cytokine production of cells of the mononuclear phagocytic system

BackgroundHeterogeneous nuclear ribonucleoprotein A2 (hnRNP-A2) belongs to a heterogenous family of nuclear proteins, importantly involved in mRNA trafficking, translational and transcriptional processes. Recent evidence let suggest that hnRNPs post-transcriptionally modulate...

Etiological role of cigarette smoking in rheumatoid arthritis: Nasal exposure to cigarette smoke condensate extracts augments the development of collagen-induced arthritis in mice

Cigarette smoking is a major environmental risk factor for rheumatoid arthritis (RA). However, the experimental bases supporting the etiological role of cigarette smoking in RA have not been fully provided. We have reported that cigarette smoke condensate (CSC), by means of subcutaneous injection into DBA/1J mice with collagen and complete Freund’s adjuvant or intraperitoneal injection one day before immunization, augmented the development of arthritis in the mouse model of collagen type II-induced arthritis (CIA). However, these experimental procedures may not be appropriate for cigarette smoking. In this study, we nasally exposed mice to mainstream CSC and found that CSC augmented the induction and development of arthritis and antibody level against collagen. Histological examination confirmed the augmenting effect of CSC. These findings provide experimental bases supporting the etiological role of cigarette smoking in RA.

Rosiglitazone reduces a wide range of proinflammatory profiles in synovial fibroblast SW982 under spheroid culture

Rosiglitazone (RSG) has been known to play a role in the modulation of inflammatory responses. Therefore, we sought to elucidate the underlying molecular mechanism by which RSG regulates the development of rheumatoid arthritis. Firstly, we examined the preventive effect of RSG on the inflammatory mediators induced by spheroid culture of synovial sarcoma SW982. Expression of proinflammatory cytokines under spheroid culture was more elevated than that under monolayer culture while RSG abolished inflammatory responses. The upregulation of inflammation-related genes by spheroid culture was closely associated with NFkappaB (NFκB) activation. Also, activation of p38 and c-Jun N-terminal kinase (JNK) by spheroid culture was abrogated with RSG treatment. Lastly, it was demonstrated that RSG reduced the development of arthritis in mice immunized with collagen, improving the histology of inflamed joint. In summary, RSG reduces inflammatory responses of synovial fibroblast via not only inhibition of NFκB but also modulation of both p38 and JNK.

Structure-Immune Response Relationships of Hapten-Modified Collagen II Peptides in a T-Cell Model of Allergic Contact Dermatitis

Allergic contact dermatitis (ACD) is mediated by T cells that specifically recognize hapten-modified peptides. T cells are known to recognize antigens as short processed peptides bound to major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells (APC). It has previously been demonstrated that T cells can specifically recognize carbohydrates on the lysine at position 264 of the immunodominant (256-273) sequence from type II collagen (CII) and that such recognition is critical for the development of arthritis in mice and may play a role in rheumatoid arthritis in humans. In the present study, we have used this approach in modeling ACD, but instead of the carbohydrate, the strong sensitizer 2,4-dinitrofluorobenzene (DNFB) is bound to the epsilon-amine of the lysine at position 264. Specific T-cell hybridomas of this antigenic peptide, with dinitrophenyl (Dnp) on the epsilon-amine of lysine at position 264 (CIILysDnp 3), were established from mice immunized with CIILysDnp 3. In an immune response assay, these T-cell hybridomas were tested with a series of new synthetic hapten-modified peptides, all chemically identical except for the stereochemimistry (D, L) and the length of the position-264 amino acid side chain bonding the hapten. The T-cell hybridomas recognized the CIILysDnp 3 peptide used for immunization; interestingly, they also recognized the CII peptide with a one-carbon-longer side chain (homolysine), CIIhLysDnp 6, and CIIAlaPipDnp 11, having a ring structure analogous to that of lysine with the same number of carbons in the bonding chain as in the CIILysDnp 3 peptide used for immunization. Dnp-modified CII peptides with a shorter bonding chain produced no immune response. These data demonstrate that the T-cell recognition of the Dnp-modified peptides is highly specific and moreover dependent on the length of the amino acid side chain that bonds the Dnp.

Interleukin-23 Is Required for Development of Arthritis in Mice Vaccinated and Challenged withBorreliaSpecies

We recently hypothesized that T helper 17 (Th17) cells and their associated cytokines are involved in the development of arthritis following infection with Borrelia burgdorferi. Here, we show that interleukin-23 (IL-23), a survival factor for Th17 cells, is required for the induction of arthritis in mice vaccinated with B. burgdorferi strain 297 and challenged with "Borrelia bissettii." When Borrelia-vaccinated and -challenged mice were given antibodies to the p19 subunit of IL-23, they failed to develop the histopathological changes observed in untreated vaccinated and challenged mice. In addition, viable B. bissettii organisms stimulated the secretion of IL-17 from Borrelia-immune lymph node cells during in vitro culture. When anti-IL-23 p19 antibody was included in cultures of B. bissettii organisms and Borrelia-immune lymph node cells, the production of IL-17 was reduced to levels observed in cultures containing immune cells alone. Taken together, these results support the hypothesis that Th17 cell-associated cytokines are involved in the development of Borrelia-mediated arthritis. These findings provide insight into previously overlooked immune mechanisms responsible for the development of Lyme arthritis.