Immune complexes, but not streptococcal cell walls or zymosan, cause chronic arthritis in mouse strains susceptible for collagen type II auto-immune arthritis

IL-23 in arthritic and inflammatory pain development in mice

Background

The cytokine, interleukin-23 (IL-23), can be critical for the progression of inflammatory diseases, including arthritis, and is often associated with T lymphocyte biology. We previously showed that certain lymphocyte-independent, inflammatory arthritis and pain models have a similar requirement for tumour necrosis factor (TNF), granulocyte macrophage-colony stimulating factor (GM-CSF), and C-C motif ligand 17 (CCL17). Given this correlation in cytokine requirements, we explored whether IL-23 might interact with this cytokine cluster in the control of arthritic and inflammatory pain.

Methods

The role of IL-23 in the development of pain-like behaviour was investigated using mouse arthritis models (zymosan-induced arthritis and GM-CSF-, TNF-, and CCL17-driven monoarticular arthritis) and inflammatory pain models (intraplantar zymosan, GM-CSF, TNF, and CCL17). Additionally, IL-23-induced inflammatory pain was measured in GM-CSF^−/−, Tnf^−/−, and Ccl17^E/E mice and in the presence of indomethacin. Pain-like behaviour and arthritis were assessed by relative weight distribution in hindlimbs and histology, respectively. Cytokine mRNA expression in knees and paw skin was analysed by quantitative PCR. Blood and synovial cell populations were analysed by flow cytometry.

Results

We report, using Il23p19^−/− mice, that innate immune (zymosan)-driven arthritic pain-like behaviour (herein referred to as pain) was completely dependent upon IL-23; optimal arthritic disease development required IL-23 (P < 0.05). Zymosan-induced inflammatory pain was also completely dependent on IL-23. In addition, we found that exogenous TNF-, GM-CSF-, and CCL17-driven arthritic pain, as well as inflammatory pain driven by each of these cytokines, were absent in Il23p19^−/− mice; optimal disease in these mBSA-primed models was dependent on IL-23 (P < 0.05). Supporting this cytokine connection, it was found conversely that IL-23 (200 ng) can induce inflammatory pain at 4 h (P < 0.0001) with a requirement for each of the other cytokines as well as cyclooxygenase activity.

Conclusions

These findings indicate a role for IL-23 in innate immune-mediated arthritic and inflammatory pain with potential links to TNF, GM-CSF, CCL17, and eicosanoid function.

CSF-1 in Inflammatory and Arthritic Pain Development

Pain is one of the most debilitating symptoms in many diseases for which there is inadequate management and understanding. CSF-1, also known as M-CSF, acts via its receptor (CSF-1R, c-Fms) to regulate the development of the monocyte/macrophage lineage and to act locally in tissues to control macrophage numbers and function. It has been implicated in the control of neuropathic pain via a central action on microglia. We report in this study that systemic administration of a neutralizing anti-CSF-1R or CSF-1 mAb inhibits the development of inflammatory pain induced by zymosan, GM-CSF, and TNF in mice. This approach also prevented but did not ameliorate the development of arthritic pain and optimal disease driven by the three stimuli in mice, suggesting that CSF-1 may only be relevant when the driving inflammatory insults in tissues are acute and/or periodic. Systemic CSF-1 administration rapidly induced pain and enhanced the arthritis in an inflamed mouse joint, albeit via a different pathway(s) from that used by systemic GM-CSF and TNF. It is concluded that CSF-1 can function peripherally during the generation of inflammatory pain and hence may be a target for such pain and associated disease, including when the clinically important cytokines, TNF and GM-CSF, are involved. Our findings have ramifications for the selection and design of anti-CSF-1R/CSF-1 trials.

TNF and granulocyte macrophage-colony stimulating factor interdependence mediates inflammation via CCL17

TNF and granulocyte macrophage-colony stimulating factor (GM-CSF) have proinflammatory activity and both contribute, for example, to rheumatoid arthritis pathogenesis. We previously identified a new GM-CSF→JMJD3 demethylase→interferon regulatory factor 4 (IRF4)→CCL17 pathway that is active in monocytes/macrophages in vitro and important for inflammatory pain, as well as for arthritic pain and disease. Here we provide evidence for a nexus between TNF and this pathway, and for TNF and GM-CSF interdependency. We report that the initiation of zymosan-induced inflammatory pain and zymosan-induced arthritic pain and disease are TNF dependent. Once arthritic pain and disease are established, blockade of GM-CSF or CCL17, but not of TNF, is still able to ameliorate them. TNF is required for GM-CSF-driven inflammatory pain and for initiation of GM-CSF-driven arthritic pain and disease, but not once they are established. TNF-driven inflammatory pain and TNF-driven arthritic pain and disease are dependent on GM-CSF and mechanistically require the same downstream pathway involving GM-CSF→CCL17 formation via JMJD3-regulated IRF4 production, indicating that GM-CSF and CCL17 can mediate some of the proinflammatory and algesic actions of TNF. Given we found that TNF appears important only early in arthritic pain and disease progression, targeting a downstream mediator, such as CCL17, which appears to act throughout the course of disease, could be effective at ameliorating chronic inflammatory conditions where TNF is implicated.

Bone Morphogenetic Protein and Activin Membrane-Bound Inhibitor, a Transforming Growth Factor β Rheostat That Controls Murine Treg Cell/Th17 Cell Differentiation and the Development of Autoimmune Arthritis by Reducing Interleukin-2 Signaling

OBJECTIVE

Transforming growth factor β (TGFβ) plays a prominent role in the establishment of immunologic tolerance, and mice lacking TGFβ1 die of multiorgan inflammation early in life. TGFβ controls the differentiation of CD4+ lymphocytes into Treg cells or proinflammatory Th17 cells. Although this dual capacity is modulated by the presence of additional cytokines around the activated cells, TGFβ also dissociates Th17/Treg cell differentiation in a dose-dependent manner by mechanisms still unknown. The purpose of this study was to explore the contribution of bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) to the modulation of TGFβ activity during the differentiation of CD4+ cells and in the control of immunologic tolerance in mice with collagen-induced arthritis (CIA).

METHODS

The in vitro and in vivo Treg cell and Th17 cell differentiation and the development of CIA were compared in wild-type mice and BAMBI-deficient mice.

RESULTS

BAMBI was induced after activation by TGFβ and fixed the appropriate intensity level of TGFβ signaling in CD4+ cells. Its deficiency protected mice against the development of CIA by a Treg cell- and TGFβ-dependent mechanism. Mechanistically, BAMBI was found to regulate CD25 expression and interleukin-2 (IL-2) signaling in Treg cells and in IL-2- and/or TGFβ-activated CD4+ cells and modulated Treg cell and Th17 cell differentiation both in vitro and in vivo.

CONCLUSION

Taken together, the results indicate that BAMBI is a component of a rheostat-like mechanism that, through the control of TGFβ and IL-2 signaling strength, regulates the differentiation of CD4+ lymphocytes and the development of autoimmune arthritis.

Granulocyte macrophage colony-stimulating factor induces CCL17 production via IRF4 to mediate inflammation

Data from preclinical and clinical studies have demonstrated that granulocyte macrophage colony-stimulating factor (GM-CSF) can function as a key proinflammatory cytokine. However, therapies that directly target GM-CSF function could lead to undesirable side effects, creating a need to delineate downstream pathways and mediators. In this work, we provide evidence that GM-CSF drives CCL17 production by acting through an IFN regulatory factor 4-dependent (IRF4-dependent) pathway in human monocytes, murine macrophages, and mice in vivo. In murine models of arthritis and pain, IRF4 regulated the formation of CCL17, which mediated the proinflammatory and algesic actions of GM-CSF. Mechanistically, GM-CSF upregulated IRF4 expression by enhancing JMJD3 demethylase activity. We also determined that CCL17 has chemokine-independent functions in inflammatory arthritis and pain. These findings indicate that GM-CSF can mediate inflammation and pain by regulating IRF4-induced CCL17 production, providing insights into a pathway with potential therapeutic avenues for the treatment of inflammatory diseases and their associated pain.

Rodent preclinical models for developing novel antiarthritic molecules: comparative biology and preferred methods for evaluating efficacy

Rodent models of immune-mediated arthritis (RMIA) are the conventional approach to evaluating mechanisms of inflammatory joint disease and the comparative efficacy of antiarthritic agents. Rat adjuvant-induced (AIA), collagen-induced (CIA), and streptococcal cell wall-induced (SCW) arthritides are preferred models of the joint pathology that occurs in human rheumatoid arthritis (RA). Lesions of AIA are most severe and consistent; structural and immunological changes of CIA best resemble RA. Lesion extent and severity in RMIA depends on experimental methodology (inciting agent, adjuvant, etc.) and individual physiologic parameters (age, genetics, hormonal status, etc.). The effectiveness of antiarthritic molecules varies with the agent, therapeutic regimen, and choice of RMIA. All RMIA are driven by overactivity of proinflammatory pathways, but the dominant molecules differ among the models. Hence, as with the human clinical experience, the efficacy of various antiarthritic molecules differs among RMIA, especially when the agent is a specific cytokine inhibitor.

Urokinase-type plasminogen activator and arthritis progression: role in systemic disease with immune complex involvement

Introduction

Urokinase-type plasminogen activator (u-PA) has been implicated in fibrinolysis, cell migration, latent cytokine activation, cell activation, T-cell activation, and tissue remodeling, all of which are involved in the development of rheumatoid arthritis. Previously, u-PA has been reported to play a protective role in monoarticular arthritis models involving mBSA as the antigen, but a deleterious role in the systemic polyarticular collagen-induced arthritis (CIA) model. The aim of the current study is to determine how u-PA might be acting in systemic arthritis models.

Methods

The CIA model and bone marrow chimeras were used to determine the cellular source of u-PA required for the arthritis development. Gene expression of inflammatory and destructive mediators was measured in joint tissue by quantitiative PCR and protein levels by ELISA. The requirement for u-PA in the type II collagen mAb-induced arthritis (CAIA) and K/BxN serum transfer arthritis models was determined using u-PA^-/- mice. Neutrophilia was induced in the peritoneal cavity using either ovalbumin/anti-ovalbumin or the complement component C5a.

Results

u-PA from a bone marrow-derived cell was required for the full development of CIA. The disease in u-PA^-/- mice reconstituted with bone marrrow from C57BL/6 mice was indistinguishable from that in C57BL/6 mice, in terms of clincal score, histologic features, and protein and gene expression of key mediators. u-PA^-/- mice were resistant to both CAIA and K/BxN serum transfer arthritis development. u-PA^-/- mice developed a reduced neutrophilia and chemokine production in the peritoneal cavity following ovalbumin/anti-ovalbumin injection; in contrast, the peritoneal neutrophilia in response to C5a was u-PA independent.

Conclusions

u-PA is required for the full development of systemic arthritis models involving immune complex formation and deposition. The cellular source of u-PA required for CIA is bone marrow derived and likely to be of myeloid origin. For immune complex-mediated peritonitis, and perhaps some other inflammatory responses, it is suggested that the u-PA involvement may be upstream of C5a signaling.

Fcgamma receptor cross-linking stimulates cell proliferation of macrophages via the ERK pathway

Macrophage proliferation can be stimulated by phagocytosis and by cross-linking of Fcgamma receptors (FcgammaR). In this study, we investigated the role of FcgammaR and the signaling cascades that link FcgammaR activation to cell cycle progression. This effect was mediated by the activating FcgammaR, including FcgammaRI and III, via their Fcgamma subunit. Further investigation revealed that the cell cycle machinery was activated by FcgammaR cross-linking through downstream signaling events. Specifically, we identified the extracellular signal-regulated kinase (ERK) signaling pathway as a mediator of signals from FcgammaR activation to cyclin D1 expression, because cyclin D1 expression associated with FcgammaR cross-linking was attenuated by specific inhibitors of the ERK1/2 signaling pathway, PD98059 and U0126 and the spleen tyrosine kinase (Syk) inhibitor, Piceatannol. Our findings establish a link between the ERK activation and cell cycle signaling pathways, thus providing a causal mechanism by which FcgammaR activation produces a mitogenic effect that stimulates macrophage proliferation. Macrophage mitosis following FcgammaR activation could potentially affect the outcome of macrophage interactions with intracellular pathogens. In addition, our results suggest the possibility of new treatment options for certain infectious diseases, chronic inflammatory diseases, and leukemias based on interference with FcgammaR-stimulated macrophage cell proliferation.

TLR2 modulates inflammation in zymosan-induced arthritis in mice

The interplay between the innate and acquired immune systems in chronic inflammation is not well documented. We have investigated the mechanisms of inflammation in murine zymosan-induced arthritis (ZIA) in the light of recent data on the roles of Toll-like receptor 2 (TLR2) and Dectin-1 in the activation of monocyte/macrophages by zymosan. The severity of inflammation, joint histology, lymphocyte proliferation and antibody production in response to zymosan were analyzed in mice deficient in TLR2 and complement C3, and the effects of Dectin-1 inhibition by laminarin were studied. In comparison with wild-type animals, TLR2-deficient mice showed a significant decrease in the early (day 1) and late phases (day 24) of joint inflammation. C3-deficient mice showed no differences in technetium uptake or histological scoring. TLR2-deficient mice also showed a significant decrease in lymph node cell proliferation in response to zymosan and a lower IgG antibody response to zymosan at day 25 in comparison with wild-type controls, indicating that TLR2 signalling has a role in the development of acquired immune responses to zymosan. Although laminarin, a soluble beta-glucan, was able to significantly inhibit zymosan uptake by macrophages in vitro, it had no effect on ZIA in vivo. These results show that ZIA is more prolonged than was originally described and involves both the innate and acquired immune pathways. C3 does not seem to have a major role in this model of joint inflammation.

Skewed balance in basal expression and regulation of activating v inhibitory Fcgamma receptors in macrophages of collagen induced arthritis sensitive mice

BACKGROUND

Recently, it has been found that collagen type II arthritis susceptible mouse strains are hyperreactive to immune complexes (ICs), locally deposited into their knee joints.

OBJECTIVE

To investigate whether this strain specific knee joint hyperreactivity is related to a disturbed regulation of activatory and inhibitory FcgammaR on their macrophages before and after stimulation with ICs.

METHODS

Macrophages from collagen induced arthritis susceptible strains (DBA/1 and B10.RIII) and non-susceptible strains (C57BL/6 and BALB/c) were compared. FcgammaR levels on macrophages were detected at protein level by flow cytometric analysis and at mRNA level by reverse transcriptase-polymerase chain reaction. Macrophages were stimulated with ICs, and production of cytokines and enzymes was measured at different times.

RESULTS

On synovial and peritoneal macrophages of DBA/1 mice a higher basal FcgammaRII and III expression was found, which was skewed towards the activating FcgammaRIII. In B10.RIII macrophages, however, FcgammaRIII levels were much lower. Regulation of FcgammaR mRNA levels in macrophages was tested after stimulation with ICs for one and three days. DBA/1 and B10.RIII macrophages showed a prolonged up regulation of activating FcgammaRI and III, whereas the inhibiting FcgammaRII was significantly down regulated compared with non-susceptible strains. In line with this, DBA/1 and B10.RIII macrophages showed a higher interleukin 1 (IL1) and matrix metalloproteinase (MMP) production after IC exposure, whereas IL6 production was significantly reduced.

CONCLUSIONS

This study indicates that macrophages derived from collagen type II arthritis susceptible mice show a disregulated FcgammaR expression before, and even more clearly, after activation by ICs involved in inflammation and cartilage degradation, resulting in prolonged expression of activatory FcgammaRI and III, down regulation of inhibitory FcgammaRII and increased release of IL1 and MMP.

Effects of maitake (Grifola frondosa) polysaccharide on collagen-induced arthritis in mice

We recently reported the anti-hepatitis effect of a polysaccharide, designated as the D-fraction, extracted from maitake. Its effect includes immuno-regulating activities. We investigated the effect of the glucan in collagen-induced arthritis (CIA). The D-fraction was administered to CIA mice for 30 consecutive days. Arthritis development was observed from the 4th day after the second immunization. The D-fraction did not have any influence on anti-type II collagen antibodies in blood serum or activated B cells. To determine how cellular immunity may be involved in the development of CIA, ratios of CD4+ T cells and their activated form in the axillary and inguinal lymph node T cells were detected by flow cytometry analysis. The ratios were not different between the D-fraction group and the control group. However, interleukin-1beta, granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha productions from splenic macrophages were significantly increased to 2.0, 4.7 and 1.9 times the control group level, respectively. The ratio of macrophages in the whole spleen cells was 2.3 times that of the control group, and their migrating ability was 1.9 times higher. Based on these results, we concluded that the arthritis development induced by D-fraction administration is attributable to the activation of splenic macrophages.

Fc gamma R expression on macrophages is related to severity and chronicity of synovial inflammation and cartilage destruction during experimental immune-complex-mediated arthritis (ICA)

STATEMENT OF FINDINGS: We investigated the role of Fc gamma receptors (Fc gamma Rs) on synovial macrophages in immune-complex-mediated arthritis (ICA). ICA elicited in knee joints of C57BL/6 mice caused a short-lasting, florid inflammation and reversible loss of proteoglycans (PGs), moderate chondrocyte death, and minor erosion of the cartilage. In contrast, when ICA was induced in knee joints of Fc receptor (FcR) gamma-chain(-/-) C57BL/6 mice, which lack functional Fc gamma RI and RIII, inflammation and cartilage destruction were prevented. When ICA was elicited in DBA/1 mice, a very severe, chronic inflammation was observed, and significantly more chondrocyte death and cartilage erosion than in arthritic C57BL/6 mice. The synovial lining and peritoneal macrophages of naïve DBA/1 mice expressed a significantly higher level of Fc gamma Rs than was seen in C57BL/6 mice. Moreover, elevated and prolonged expression of IL-1 was found after stimulation of these cells with immune complexes. Zymosan or streptococcal cell walls caused comparable inflammation and only mild cartilage destruction in all strains. We conclude that Fc gamma R expression on synovial macrophages may be related to the severity of synovial inflammation and cartilage destruction during ICA.