Autoimmune Th17 Cells Induced Synovial Stromal and Innate Lymphoid Cell Secretion of the Cytokine GM-CSF to Initiate and Augment Autoimmune Arthritis

Despite the importance of Th17 cells in autoimmune diseases, it remains unclear how they control other inflammatory cells in autoimmune tissue damage. Using a model of spontaneous autoimmune arthritis, we showed that arthritogenic Th17 cells stimulated fibroblast-like synoviocytes via interleukin-17 (IL-17) to secrete the cytokine GM-CSF and also expanded synovial-resident innate lymphoid cells (ILCs) in inflamed joints. Activated synovial ILCs, which expressed CD25, IL-33Ra, and TLR9, produced abundant GM-CSF upon stimulation by IL-2, IL-33, or CpG DNA. Loss of GM-CSF production by either ILCs or radio-resistant stromal cells prevented Th17 cell-mediated arthritis. GM-CSF production by Th17 cells augmented chronic inflammation but was dispensable for the initiation of arthritis. We showed that GM-CSF-producing ILCs were present in inflamed joints of rheumatoid arthritis patients. Thus, a cellular cascade of autoimmune Th17 cells, ILCs, and stromal cells, via IL-17 and GM-CSF, mediates chronic joint inflammation and can be a target for therapeutic intervention.

Quercetin attenuates zymosan-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular lesions, recruitment of inflammatory cells and increased levels of pro-inflammatory cytokine. The intra-articular administration of zymosan is an experimental model that promotes inflammatory parameters resembling RA. Therefore, this model was used to investigate the efficacy of quercetin as a treatment of articular inflammation. Treatment with quercetin dose-dependently reduced zymosan-induced hyperalgesia, articular edema and the recruitment of neutrophils to the knee joint cavity. Histological analysis confirmed that quercetin inhibited zymosan-induced arthritis. The treatment with quercetin also inhibited zymosan-induced depletion of reduced glutathione (GSH) levels, TNFα and IL-1β production, and gp91^phox, prepro-endothelin-1 (preproET-1), and cyclooxygenase-2 mRNA expression. These molecular effects of quercetin were related to the inhibition of the nuclear factor kappa-B and induction of Nuclear factor erythroid 2- related factor (Nrf2)/home oxygenase (HO-1) pathway. Thus, quercetin exerted anti-inflammatory, analgesic and antioxidant effects in experimental arthritis, suggesting quercetin is a possible candidate for arthritis treatment.

Protein tyrosine phosphatase PTPN22 regulates IL-1β dependent Th17 responses by modulating dectin-1 signaling in mice

A single nucleotide polymorphism within the PTPN22 gene is a strong genetic risk factor predisposing to the development of multiple autoimmune diseases. PTPN22 regulates Syk and Src family kinases downstream of immuno-receptors. Fungal β-glucan receptor dectin-1 signals via Syk, and dectin-1 stimulation induces arthritis in mouse models. We investigated whether PTPN22 regulates dectin-1 dependent immune responses. Bone marrow derived dendritic cells (BMDCs) generated from C57BL/6 wild type (WT) and Ptpn22-/- mutant mice, were pulsed with OVA323-339 and the dectin-1 agonist curdlan and co-cultured in vitro with OT-II T-cells or adoptively transferred into OT-II mice, and T-cell responses were determined by immunoassay. Dectin-1 activated Ptpn22-/- BMDCs enhanced T-cell secretion of IL-17 in vitro and in vivo in an IL-1β dependent manner. Immunoblotting revealed that compared to WT, dectin-1 activated Ptpn22-/- BMDCs displayed enhanced Syk and Erk phosphorylation. Dectin-1 activation of BMDCs expressing Ptpn22R619W (the mouse orthologue of human PTPN22R620W ) also resulted in increased IL-1β secretion and T-cell dependent IL-17 responses, indicating that in the context of dectin-1 Ptpn22R619W operates as a loss-of-function variant. These findings highlight PTPN22 as a novel regulator of dectin-1 signals, providing a link between genetically conferred perturbations of innate receptor signaling and the risk of autoimmune disease.

Text Mining of Rheumatoid Arthritis and Diabetes Mellitus to Understand the Mechanisms of Chinese Medicine in Different Diseases with Same Treatment

OBJECTIVE

To identify the commonalities between rheumatoid arthritis (RA) and diabetes mellitus (DM) to understand the mechanisms of Chinese medicine (CM) in different diseases with the same treatment.

METHODS

A text mining approach was adopted to analyze the commonalities between RA and DM according to CM and biological elements. The major commonalities were subsequently verified in RA and DM rat models, in which herbal formula for the treatment of both RA and DM identified via text mining was used as the intervention.

RESULTS

Similarities were identified between RA and DM regarding the CM approach used for diagnosis and treatment, as well as the networks of biological activities affected by each disease, including the involvement of adhesion molecules, oxidative stress, cytokines, T-lymphocytes, apoptosis, and inflammation. The Ramulus Cinnamomi-Radix Paeoniae Alba-Rhizoma Anemarrhenae is an herbal combination used to treat RA and DM. This formula demonstrated similar effects on oxidative stress and inflammation in rats with collagen-induced arthritis, which supports the text mining results regarding the commonalities between RA and DM.

CONCLUSION

Commonalities between the biological activities involved in RA and DM were identified through text mining, and both RA and DM might be responsive to the same intervention at a specific stage.

HCV coinfection of the HIV-infected patients with discordant CD4+ T-cell response to antiretroviral therapy leads to intense systemic inflammation

The level of proinflammatory markers was assessed in HIV-infected patients that were coinfected with hepatitis C virus (HCV) and had failed to restore the CD4⁺ T cell counts (immunological nonresponders, INR) during the antiretroviral therapy (ART). Among four patient groups (HIV⁺HCV^- and HIV⁺HCV⁺ subjects with the concordant response to ART; HIV⁺HCV^- and HIV⁺HCV⁺ subjects that were INR), the greatest systemic inflammation was in the latter group. The maximum difference was between the subjects HIV⁺HCV^-INR and HIV⁺HCV⁺ INR: the blood of coinfected patients contained significantly higher concentrations of the IP-10, sCD163, sTNF-RI, and sTNF-RII and of bacterial lipopolysaccharide. Systemic inflammation in HIV/HCV coinfected patients with the discordant response to ART is probably caused by a breach of hepatic barrier for the intestine products.

Exploring Non-Metabolic Functions of Glycolytic Enzymes in Immunity

At the beginning of the twentieth century, discoveries in cancer research began to elucidate the idiosyncratic metabolic proclivities of tumor cells (1). Investigators postulated that revealing the distinct nutritional requirements of cells with unchecked growth potential would reveal targetable metabolic vulnerabilities by which their survival could be selectively curtailed. Soon thereafter, researchers in the field of immunology began drawing parallels between the metabolic characteristics of highly proliferative cancer cells and those of immune cells that respond to perceived threats to host physiology by invading tissues, clonally expanding, and generating vast amounts of pro-inflammatory effector molecules to provide the host with protection. Throughout the past decade, increasing effort has gone into elucidating the biosynthetic and bioenergetic requirements of immune cells during inflammatory responses. It is now well established that, like tumor cells, immune cells must undergo metabolic adaptations to fulfill their effector functions (2, 3). Unraveling the metabolic adaptations that license inflammatory immune responses may lead to the development of novel classes of therapeutics for pathologies with prominent inflammatory components (e.g., autoimmunity). However, the translational potential of discoveries made toward this end is currently limited by the ubiquitous nature of the "pathologic" process being targeted: metabolism. Recent works have started to unravel unexpected non-metabolic functions for metabolic enzymes in the context of inflammation, including signaling and gene regulation. One way information gained through the study of immunometabolism may be leveraged for therapeutic benefit is by exploiting these non-canonical features of metabolic machinery, modulating their contribution to the immune response without impacting their basal metabolic functions. The focus of this review is to discuss the metabolically independent functions of glycolytic enzymes and how these could impact T cells, agents of the immune system that are commonly considered as orchestrators of auto-inflammatory processes.

Protective effect of Rumenic acid rich cow's milk against colitis is associated with the activation of Nrf2 pathway in a murine model

Dietary supplementation with pure cis9, trans11 isomer of Conjugated Linoleic Acid -known as Rumenic Acid (RA)- improves cytoprotective defenses downstream through the activation of nuclear factor-E2-related factor-2(Nrf2). This capability, when Rumenic Acid is consumed in the form of foods, is still unknown. The ability of standard (St) or cow milk naturally-enriched in RA (En) to activate Nrf2 pathway and its impact on dextran sodium sulfate (DSS)-induced colitis was comparatively evaluated. Activity of Nrf2 pathway was investigated in colonic tissue of BALB/c mice, receiving 4-week supplement with skimmed milk (SK), St or St reinforced with pure RA (RSt) providing increasing RA dose (0, 124 or 404mg RA/kg^-1 b.w, respectively). Next, the anti-oxidant/ anti-inflammatory effect produced by St or En treatment (383mg RA/kg^-1 b.w.) was explored. Finally, macroscopic and histomorphologic features of colitis were evaluated in animals challenged with 5% (w/v) DSS, at the end of St or En treatment. Significant activation of Nrf2 pathway is associated with RSt and En intake (P<0.05), but not with SK or En treatment. En pre-treatment offers better protection, in comparison with St, against pro-oxidant, pro-inflammatory signs (P<0.01) and macroscopic signs triggered by DSS. It can be concluded that Nrf2 activation by higher RA amount contained in En is, at least in part, responsible for the improved protection associated with En intake against DSS-induced colitis.

IL-4 enhances IL-10 production in Th1 cells: implications for Th1 and Th2 regulation

IL-10 is an immunomodulatory cytokine with a critical role in limiting inflammation in immune-mediated pathologies. The mechanisms leading to IL-10 expression by CD4⁺ T cells are being elucidated, with several cytokines implicated. We explored the effect of IL-4 on the natural phenomenon of IL-10 production by a chronically stimulated antigen-specific population of differentiated Th1 cells. In vitro, IL-4 blockade inhibited while addition of exogenous IL-4 to Th1 cultures enhanced IL-10 production. In the in vivo setting of peptide immunotherapy leading to a chronically stimulated Th1 phenotype, lack of IL-4Rα inhibited the induction of IL-10. Exploring the interplay of Th1 and Th2 cells through co-culture, Th2-derived IL-4 promoted IL-10 expression by Th1 cultures, reducing their pathogenicity in vivo. Co-culture led to upregulated c-Maf expression with no decrease in the proportion of T-bet⁺ cells in these cultures. Addition of IL-4 also reduced the encephalitogenic capacity of Th1 cultures. These data demonstrate that IL-4 contributes to IL-10 production and that Th2 cells modulate Th1 cultures towards a self-regulatory phenotype, contributing to the cross-regulation of Th1 and Th2 cells. These findings are important in the context of Th1 driven diseases since they reveal how the Th1 phenotype and function can be modulated by IL-4.

Th17 in Animal Models of Rheumatoid Arthritis

IL-17-secreting helper CD4 T cells (Th17 cells) constitute a newly identified subset of helper CD4 T cells that play a key role in the development of rheumatoid arthritis (RA) in its animal models. Recently, several models of spontaneous RA, which elucidate the mechanism of RA onset, have been discovered. These animal models shed new light on the role of Th17 in the development of autoimmune arthritis. Th17 cells coordinate inflammation and promote joint destruction, acting on various cells, including neutrophils, macrophages, synovial fibroblasts, and osteoclasts. Regulatory T cells cannot control Th17 cells under conditions of inflammation. In this review, the pathogenic role of Th17 cells in arthritis development, which was revealed by the recent animal models of RA, is discussed.

The role of interleukin-6 signalling and its therapeutic blockage in skewing the T cell balance in rheumatoid arthritis

Therapeutic blockage of cytokine signalling in autoimmune diseases has improved our understanding of the role of these cytokines in triggering, shaping and perpetuating autoimmune responses. In rheumatoid arthritis (RA), immunopathology is driven by a predominance of arthritogenic T helper cells secreting interferon-γ [T helper type 1 (Th1)] and interleukin (IL)-17 (Th17) over regulatory T cells (T_reg ). The pleiotropic cytokine IL-6 is crucial to the differentiation of Th17 cells and the balance between pathogenic Th17 and protective T_reg . Targeting the IL-6 receptor (IL-6R) by humanized antibodies improves signs and symptoms of RA, and has provided new insights into the mechanisms of inflammation and immune regulation. Here we review current evidence on the role of IL-6 in the pathogenesis of RA and the molecular consequences of IL-6R blockage in disease, with special focus on the Th17/T_reg balance and plasticity.

CD11b regulates the Treg/Th17 balance in murine arthritis via IL-6

Th17 cells are often associated with autoimmunity and been shown to be increased in CD11b^-/- mice. Here, we examined the role of CD11b in murine collagen-induced arthritis (CIA). C57BL/6 and CD11b^-/- resistant mice were immunized with type II collagen. CD11b^-/- mice developed arthritis with early onset, high incidence, and sustained severity compared with C57BL/6 mice. We observed a marked leukocyte infiltration, and histological examinations of the arthritic paws from CD11b^-/- mice revealed that the cartilage was destroyed in association with strong lymphocytic infiltration. The CD11b deficiency led to enhanced Th17-cell differentiation. CD11b^-/- dendritic cells (DCs) induced much stronger IL-6 production and hence Th17-cell differentiation than wild-type DCs. Treatment of CD11b^-/- mice after establishment of the Treg/Th17 balance with an anti-IL-6 receptor mAb significantly suppressed the induction of Th17 cells and reduced arthritis severity. Finally, the severe phenotype of arthritis in CD11b^-/- mice was rescued by adoptive transfer of CD11b⁺ DCs. Taken together, our results indicate that the resistance to CIA in C57BL/6 mice is regulated by CD11b via suppression of IL-6 production leading to reduced Th17-cell differentiation. Therefore, CD11b may represent a susceptibility factor for autoimmunity and could be a target for future therapy.

IL-10: A Multifunctional Cytokine in Viral Infections

The anti-inflammatory master regulator IL-10 is critical to protect the host from tissue damage during acute phases of immune responses. This regulatory mechanism, central to T cell homeostasis, can be hijacked by viruses to evade immunity. IL-10 can be produced by virtually all immune cells, and it can also modulate the function of these cells. Understanding the effects of this multifunctional cytokine is therefore a complex task. In the present review we discuss the factors driving IL-10 production and the cellular sources of the cytokine during antiviral immune responses. We particularly focus on the IL-10 regulatory mechanisms that impact antiviral immune responses and how viruses can use this central regulatory pathway to evade immunity and establish chronic/latent infections.

Olmesartan Prevented Intra-articular Inflammation Induced by Zymosan in Rats

The objective of this study was to study the effect of olmesartan medoxomil (OLM), an antihypertensive drug, on intra-articular inflammation induced by zymosan (Zy) in Wistar rats. Intra-articular inflammation was induced in the right knees of rats by 1 mg Zy dissolved in saline. The animals were divided into the following groups: saline only (oral saline and intra-articular saline); Zy only (intra-articular Zy and oral saline), and intra-articular Zy and oral OLM (5, 15, or 30 mg/kg) or diclofenac sodium (SD; 100 mg/kg). Twenty-four hours after Zy injection, synovial fluid was collected for total leukocyte counts, blood was collected for biochemical measurements, and synovial tissue was collected for histopathology, immunohistochemistry, immunofluorescence and myeloperoxidase (MPO), malonaldehyde (MDA), and non-protein sulphydryl (NPSH) assays. OLM doses of 15 and 30 mg/kg had protective effects, as evidenced by improved histopathological parameters of synovium, reduced total leukocyte counts, reduced MPO and MDA levels, and increased NPSH group levels compared with the Zy group. OLM reduced immunostaining for cyclooxygenase 2, tumour necrosis factor and interleukin 17 and increased immunostaining for superoxide dismutase and glutathione peroxidase. SD produced similar results. The drugs studied caused no change in biochemical parameters of the animals. OLM showed protective effects in this model of Zy-induced intra-articular inflammation.

Porphyromonas gingivalis infection exacerbates the onset of rheumatoid arthritis in SKG mice

Epidemiological studies have linked periodontitis to rheumatoid arthritis (RA). Porphyromonas gingivalis (Pg) was reported recently to produce citrullinated protein (CP) and increase anti-cyclic CP antibody (ACPA), both of which have been identified as causative factors of RA. In the present study, we determined the effects of Pg infection on the exacerbation of RA in a mouse model. RA model mice (SKG mice) were established by an intraperitoneal (i.p.) injection of laminarin (LA). Mice were divided into six groups, Ctrl (PBS injection), LA (LA injection), Pg/LA (Pg + LA injection), Pg (Pg injection), Ec/LA (Escherichia coli and LA injection) and Ec (E. coli injection). In order to evaluate RA, joint swelling by the arthritis score, bone morphology by microcomputed tomography (microCT), haematoxylin and eosin staining, ACPA, matrix metalloproteinase-3 (MMP-3) and cytokine level in serum by enzyme-linked immunosorbent assay were determined. Osteoclast differentiation from bone marrow mononuclear cells (BMCs) was examined to clarify the underlying mechanisms of RA. The presence of Pg and CP in joint tissue was also investigated. The arthritis score was threefold higher in the Pg/LA group than in the LA group. Severe bone destruction was observed in joint tissue of the Pg/LA group. A microCT analysis of the Pg/LA group revealed a decrease in bone density. ACPA, MMP-3, interleukin (IL)-2, IL-6, CXCL1 and macrophage inflammatory protein (MIP)-1α levels from the Pg/LA group were the highest. The osteoclastogenesis of BMCs was enhanced in the Pg/LA group. Furthermore, large amounts of Pg components and CP were detected in the Pg/LA group. In conclusion, Pg infection has the potential to exacerbate RA.

Auricular Chondritis Caused by Metal Ear Tagging in C57BL/6 Mice

Although it has been shown that auricular chondritis in rats is caused by the use of metal identification ear tags, the pathogenesis remains unclear. Based on the hypothesis that the auricular chondritis is caused by metal ions released from metal identification ear tags, we investigated the pathogenesis in male C57BL/6 mice tagged with metal identification ear tags. Twenty-six weeks after the attachment of the ear tags, visible increases in the thickness of the auricle were observed, and the concentrations of copper and iron in the tagged ears were significantly increased ( P <.05) in the tagged ears compared with the untagged ears. There was up-regulation of metallothionein (MT)-I and MT-II mRNA in the tagged ears, and this was confirmed by immunohistologic staining of the destroyed cartilage. Histopathologically, there were observed severe chondritis with extensive granulomatous inflammation, newly formed cartilage nodules, and osseous metaplasia accompanied by cellular infiltrates, such as CD4 T lymphocyte, macrophages, neutrophils, and mast cells, and expression of Th1 cytokines, such as interferon-gamma, tumor necrosis factor-alpha, and interleukin-2 in the tagged ear. Based on these results, we concluded that the release of copper and iron ions from the metal ear tags played a major role in the onset of auricular chondritis. Subsequent cellular interactions, such as CD4 T cells, macrophages, fibroblasts, and mast cells, mediated by cytokines, such as tumor necrosis factor-alpha and interferon-gamma, caused an autoimmune response that may have led to the progression of auricular chondritis as an autoimmune disease.

Loss of the Protein Tyrosine Phosphatase PTPN22 Reduces Mannan-Induced Autoimmune Arthritis in SKG Mice

The cytoplasmic phosphatase, protein tyrosine phosphatase nonreceptor type 22 (PTPN22), is a negative regulator of T cell signaling. Genome-wide association studies have shown that single-nucleotide polymorphisms in PTPN22 confer an increased risk of developing multiple autoimmune diseases in humans. The precise function of PTPN22 and how the variant protein contributes to autoimmunity is not well understood. To address this issue, we investigated the effect of PTPN22 deficiency on disease susceptibility in a mouse model of autoimmune arthritis. The SKG mouse expresses a hypomorphic mutant allele of ZAP70, which, upon exposure to fungal Ags, predisposes the mice to a CD4⁺ T cell–mediated autoimmune arthritis that closely resembles rheumatoid arthritis in humans. Surprisingly, SKG Ptpn22^−/− mice developed less severe mannan-induced arthritis compared with SKG mice. Diminution of disease was not due to significant alterations in thymocyte development or repertoire selection in SKG Ptpn22^−/− mice, even though T cell–mediated signal transduction was improved. Instead, Ptpn22 deficiency appeared to bias CD4 Th cell differentiation away from the Th17 lineage, which is pathogenic in this setting, to a more Th1/T regulatory–focused response. These data show that even small perturbations in TCR signal transduction pathways can have profound consequences on the differentiation of T cell lineages and thus for the development of autoimmune diseases.

Therapeutic antibodies that target inflammatory cytokines in autoimmune diseases

Inflammatory cytokines are key regulators of immune responses. Persistent and excessive production of inflammatory cytokines underscores the development of autoimmune diseases. Therefore, neutralizing inflammatory cytokines or antagonizing their receptor function is considered as a useful therapeutic strategy to treat autoimmune diseases. To achieve the success of such a strategy, understanding of the complex actions of these cytokines and cytokine networks is required. In this review we focus on four inflammatory cytokines--tumor necrosis factor α (TNFα), interleukin-6 (IL-6), IL-23 and IL-17--and dissect how the dysregulation of these cytokines regulates autoimmune diseases. On the basis of pre-clinical and clinical data, we specifically discuss the therapeutic rationale for targeting these cytokines and describe the potential adverse effects.

The role of high-mobility group box protein 1 in collagen antibody-induced arthritis is dependent on vascular endothelial growth factor

High-mobility group box 1 (HMGB1) has been implicated in angiogenesis and rheumatoid arthritis (RA). The aim of this study was to define more clearly the role of HMGB1 in the synovial angiogenesis and pathogenesis of an immune model of arthritis. BALB/c mice were injected with monoclonal anti-collagen antibody cocktail followed by lipopolysaccharide to induce arthritis. HMGB1 and vascular endothelial growth factor (VEGF) were over-expressed in the areas of the synovium where more inflammation and neoangiogenesis were present. The selective blockade of HMGB1 or VEGF resulted alternatively in a lower severity of arthritis evaluated by the arthritis index. Furthermore, exogenous HMGB1 administration caused a worsening of arthritis, associated with VEGF up-regulation and increased synovial angiogenesis. The selective inhibition of VEGF also resulted in no induction of arthritis in mice receiving exogenous HMGB1. Cytokine enzyme-linked immunosorbent assay (ELISA) analyses performed on peripheral blood and synovial fluid demonstrated a significant reduction of interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α in mice where HMGB1 and VEGF pathways were blocked. Interestingly, the selective blockade of HMGB1 and VEGF resulted in an increase of the peripheral IL-17A concentration. The development of arthritis mediated by HMGB1 and the synovial angiogenesis can be blocked by inhibiting the VEGF activity. The proinflammatory and proangiogenic cytokine IL-17A was increased when HMGB1 is inhibited, but the synovial angiogenesis was nevertheless reduced in this model of arthritis. Taken together, these findings shed new light on the role of this nuclear protein in the pathogenesis of arthritis in an RA-like model.

Old and new therapeutics for Rheumatoid Arthritis: in vivo models and drug development

Development of novel drugs for treatment of chronic inflammatory diseases is to a large extent dependent on the availability of good experimental in vivo models in order to perform preclinical tests of new drugs and for the identification of novel drug targets. Here, we review a number of existing rodent models for Rheumatoid Arthritis in the context of how these models have been utilized for developing established therapy in Rheumatoid Arthritis and, furthermore, the present use of animal models for studies of novel drug candidates. We have studied the literature in the field for the use of in vivo models during development of anti-rheumatic drugs; from Methotrexate to various antibody treatments, to novel drugs that are, or have recently been, in clinical trials. For novel drugs, we have explored websites for clinical trials. Although a single Rheumatoid Arthritis in vivo model cannot mirror the complexity of disease development, there exist a number of good animal models for Rheumatoid Arthritis, each defining some parts in disease development, which are useful for studies of drug response. We find that many of the established drugs were not tested in in vivo models before being used in the clinic, but rather animal models have been subsequently used to find mechanisms for efficacy. Finally, we report a number of novel drugs, tested in preclinical in vivo models, presently in clinical trials.

T follicular helper cells, T follicular regulatory cells and autoimmunity

CD4(+)T follicular helper (Tfh) cells are recognized as a distinct T-cell subset, which provides help for germinal center (GC) formation, B-cell development and affinity maturation, and immunoglobulin class switching, as an indispensable part of adaptive immunity. Tfh cell differentiation depends on various factors including cell-surface molecule interactions, extracellular cytokines and multiple transcription factors, with B-cell lymphoma 6 (Bcl-6) being the master regulator. T follicular regulatory (Tfr) cells are also located in the GC and share phenotypic characteristics with Tfh cells and regulatory T cells, but function as negative regulators of GC responses. Dysregulation of either Tfh or Tfr cells is linked to the pathogenesis of autoimmune diseases such as systemic lupus erythematosus. This review covers the basic Tfh and Tfr biology including their differentiation and function, and their close relationship with autoimmune diseases.

Investigation of the relationship between the onset of arthritis and uveitis in genetically predisposed SKG mice

Introduction

Systemic rheumatic conditions are often accompanied by intraocular inflammatory disease (termed uveitis). Despite the frequent manifestation of uveitis with arthritis, very little is understood of the underlying mechanisms that mediate the eye’s susceptibility to disease. The genetically susceptible SKG mouse strain develops arthritis that arises from an inherent mutation that disrupts T-cell antigen receptor signal transduction and thymic selection. The ensuing T-cell–mediated disease is further modulated through exposure to microbial triggers. The purpose of this study was to elucidate how a genetically determined shift in the T-cell repertoire toward self-reactive T cells that drive arthritis influences uveitis in SKG mice.

Methods

SKG mice (BALB/c mice that harbor the W163C point mutation in zeta-chain-associated protein kinase 70 [i.e., ZAP-70]) were housed under arthritis-resistant, specific pathogen–free conditions. Arthritis was induced by intraperitoneal injection with fungal glucans (zymosan or curdlan). Arthritis onset and severity were evaluated by clinical scoring, histopathology and infrared imaging within the joints. Periocular traits involving blepharoconjunctivitis were evaluated by clinical scoring and histology. Eyes were evaluated for signs of anterior uveitis using intravital videomicroscopy to document cell-trafficking responses within the iris vasculature and stroma and by histology to detect inflammatory infiltrate and tissue damage within the anterior and posterior eye segments.

Results

Exposure to zymosan resulted in the predicted arthritic, sexually dimorphic phenotype in SKG mice. The eyes of SKG mice exhibited episodic intravascular cellular responses to zymosan or curdlan as indicated by significant increases in leukocyte–endothelium interactions akin to ocular vasculitis. However, despite the significant increase in early cell-trafficking responses, cellular infiltration into the iris stroma was not observed and histopathological signs indicative of a sustained uveitis were absent. Instead, eyes of SKG mice developed blepharoconjunctivitis that coincided with arthritis and exhibited sexual dimorphism.

Conclusions

This study underscores the complexity surrounding the pathogenesis of uveitis and its relationship with arthritis. The findings suggest that distinct mechanisms exist by which pathogenic autoimmune T cells target the eyes versus joints, which likely involves the environmental context but nonetheless should be taken into account in the identification and development of effective therapies for each organ.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0725-z) contains supplementary material, which is available to authorized users.

Neuroinflammation in pulmonary hypertension: concept, facts, and relevance

Pulmonary hypertension (PH) is a progressive lung disease characterized by elevated pressure in the lung vasculature, resulting in right-sided heart failure and premature death. The pathogenesis of PH is complex and multifactorial, involving a dysregulated autonomic nervous system and immune response. Inflammatory mechanisms have been linked to the development and progression of PH; however, these are usually restricted to systemic and/or local lung tissue. Inflammation within the CNS, often referred to as neuroinflammation involves activation of the microglia, the innate immune cells that are found specifically in the brain and spinal cord. Microglial activation results in the release of several cytokines and chemokines that trigger neuroinflammation, and has been implicated in the pathogenesis of several disease conditions such as Alzheimer's, Parkinson's, hypertension, atherosclerosis, and metabolic disorders. In this review, we introduce the concept of neuroinflammation in the context of PH, and discuss possible strategies that could be developed for PH therapy based on this concept.

Glycogen synthase kinase-3 controls IL-10 expression in CD4(+) effector T-cell subsets through epigenetic modification of the IL-10 promoter

The serine/threonine kinase glycogen synthase kinase-3 (GSK3) plays an important role in balancing pro- and anti-inflammatory cytokines. We have examined the role of GSK3 in production of IL-10 by subsets of CD4(+) T helper cells. Treatment of naive murine CD4(+) T cells with GSK3 inhibitors did not affect their production of IL-10. However, treatment of Th1 and Th2 cells with GSK3 inhibitors dramatically increased production of IL-10. GSK3 inhibition also led to upregulation of IL-10 among Th1, Th2, and Th17 subsets isolated from human blood. The encephalitogenic potential of GSK3 inhibitor treated murine Th1 cells was significantly reduced in adoptive transfer experiments by an IL-10-dependent mechanism. Analysis of the murine IL-10 promoter in response to inhibition of GSK3 in Th1 cells showed modification to a transcriptionally active state indicated by changes in histone H3 acetylation and methylation. Additionally, GSK3 inhibition increased expression of the transcription factors c-Maf, Nfil3, and GATA3, correlating with the increase in IL-10. These findings are important in the context of autoimmune disease since they show that it is possible to reprogram disease-causing cells through GSK3 inhibition.

Developing chemoselective and biodegradable polyester elastomers for bioscaffold application

Thermal polyesterification has emerged as a successful method for synthesizing polyesters for biomedical applications. However, to date, no general functionalization strategy has been incorporated into materials designed by the thermal polycondensation of polyacids and polyols. Herein, we report the design of several elastomers based on the thermal polycondensation of 4-ketopimelic acid, citric acid, and one of two diols: 1,6-hexanediol or 1,4-cyclohexanedimethanol. By varying the diol and the curing conditions, several elastomers were designed with a range of physical and mechanical properties. Poly(diol 4-ketopimelate-co-diol citrate) achieved Young's modulus, ultimate tensile stress, and rupture strain values of 0.39-1.13 MPa, 0.27-1.04 MPa, and 108-426%, respectively. Additionally, the incorporation of the ketone from 4-ketopimelic acid gave these materials two advantageous characteristics: a site for covalent functionalization through oxime formation and the ability to covalently bond to the surrounding tissue through imine linkages. Biocompatibility was studied both in vitro and in vivo in order to gain a complete understanding as to how biological systems respond to these novel materials. Based on preliminary results, we believe that poly(diol 4-ketopimelate-co-diol citrate) polyketoesters are excellent candidates for biomaterials.

Rebamipide attenuates autoimmune arthritis severity in SKG mice via regulation of B cell and antibody production

Oxidative stress is involved in the pathophysiology of rheumatoid arthritis (RA). We investigated the therapeutic potential of rebamipide, a gastroprotective agent with a property of reactive oxygen species scavenger, on the development of inflammatory polyarthritis and the pathophysiological mechanisms by which rebamipide might confer anti-arthritic effects in SKG mice, an animal model of RA. Intraperitoneal (i.p.) injection of rebamipide attenuated the severity of clinical and histological arthritis. Rebampide treatment reduced the number of T helper type 1 (Th1), Th2, Th17, inducible T cell co-stimulator (ICOS)(+) follicular helper T (Tfh) transitional type (T2) and mature B cells in the spleen, but increased the number of regulatory T (Treg ), CD19(+) CD1d(high) CD5(high) , CD19(+) CD25(high) forkhead box protein 3 (FoxP3)(+) regulatory B (Breg ) cells, memory B cells, and transitional type 1 (T1) B cells. In addition, flow cytometric analysis revealed significantly decreased populations of FAS(+) GL-7(+) germinal centre B cells and B220(-) CD138(+) plasma cells in the spleens of rebamipide-treated SKG mice compared to controls. Rebamipide decreased germinal centre B cells and reciprocally induced Breg cells in a dose-dependent manner in vitro. Rebamipide-induced Breg cells had more suppressive capacity in relation to T cell proliferation and also inhibited Th17 differentiation from murine CD4(+) T cells. Together, these data show that i.p. administration of rebamipide suppresses arthritis severity by inducing Breg and Treg cells and suppressing Tfh and Th17 cells in a murine model of RA.

Suppression of experimental arthritis with self-assembling glycol-split heparin nanoparticles via inhibition of TLR4-NF-κB signaling

It has been recently shown that Toll-like receptor4 mediated nuclear factor κB (TLR4-NF-κB) signaling plays a critical role in the pathogenesis of rheumatoid arthritis mediated by pro-inflammatory cytokines in arthritic synovium. Here we evaluate the therapeutic potential of glycol-split non-anticoagulant heparin/d-erythro-sphingosine nanoparticles (NAHNPs), which have shown strong inhibitory effect against TLR4 induced inflammation, in an experimental arthritis model. NAHNP significantly inhibited the production of pro-inflammatory cytokines such as TNF-α, IL-6 and IL-1β in lipopolysaccharide (LPS)-induced primary mouse macrophages and DC2.4 dendritic cell line. The nanoparticles were administered to type II collagen-induced arthritis (CIA) mice by intraarticular injections once per day starting from onset of the disease symptoms. Treatment with NAHNP had a potent suppressive effect in CIA mice, observed with a decrease in arthritis score and footpad swelling. The animals treated with NAHNP significantly reduced levels of IgG1 and IgG2a antibodies against bovine type II collagen. Levels of proinflammatory cytokines--e.g., TNF-α, IL-6 and IL-1β in knee joints and sera were significantly inhibited compared to control mice. Moreover, nuclear localization of RelA in knee joints was significantly inhibited in NAHNP treatment, indicating down-regulation of the NF-κB signaling pathway. In addition, histological examination revealed significant suppression of inflammatory cell infiltration, joint destruction and synovial proliferation in synovium compared with control mice. These results suggest that selective inhibition of TLR4-NF-κB signaling with lipid modified heparin derivatives composited to nanostructures provides an effective therapeutic approach to inhibit chronic inflammation in an animal model of rheumatoid arthritis.

Interleukin-23 mediates the intestinal response to microbial β-1,3-glucan and the development of spondyloarthritis pathology in SKG mice

OBJECTIVE

Spondyloarthritides (SpA) occur in 1% of the population and include ankylosing spondylitis (AS) and arthropathy of inflammatory bowel disease (IBD), with characteristic spondylitis, arthritis, enthesitis, and IBD. Genetic studies implicate interleukin-23 (IL-23) receptor signaling in the development of SpA and IBD, and IL-23 overexpression in mice is sufficient for enthesitis, driven by entheseal-resident T cells. However, in genetically prone individuals, it is not clear where IL-23 is produced and how it drives the SpA syndrome, including IBD or subclinical gut inflammation of AS. Moreover, it is unclear why specific tissue involvement varies between patients with SpA. We undertook this study to determine the location of IL-23 production and its role in SpA pathogenesis in BALB/c ZAP-70(W163C)-mutant (SKG) mice injected intraperitoneally with β-1,3-glucan (curdlan).

METHODS

Eight weeks after curdlan injection in wild-type or IL-17A(-/-) SKG or BALB/c mice, pathology was scored in tissue sections. Mice were treated with anti-IL-23 or anti-IL-22. Cytokine production and endoplasmic reticulum (ER) stress were determined in affected organs.

RESULTS

In curdlan-treated SKG mice, arthritis, enthesitis, and ileitis were IL-23 dependent. Enthesitis was specifically dependent on IL-17A and IL-22. IL-23 was induced in the ileum, where it amplified ER stress, goblet cell dysfunction, and proinflammatory cytokine production. IL-17A was pathogenic, while IL-22 was protective against ileitis. IL-22+CD3- innate-like cells were increased in lamina propria mononuclear cells of ileitis-resistant BALB/c mice, which developed ileitis after curdlan injection and anti-IL-22.

CONCLUSION

In response to systemic β-1,3-glucan, intestinal IL-23 provokes local mucosal dysregulation and cytokines driving the SpA syndrome, including IL-17/IL-22-dependent enthesitis. Innate IL-22 production promotes ileal tolerance.

Systemic but no local effects of combined zoledronate and parathyroid hormone treatment in experimental autoimmune arthritis

INTRODUCTION

Local bone erosions and osteoporosis in rheumatoid arthritis (RA) are the result of a more pronounced bone resorption than bone formation. Present treatment strategies for RA inhibit inflammation, but do not directly target bone erosions. The aim of the study was in experimental arthritis to investigate the juxtaarticular and systemic effects of simultaneous osteoclast inhibition with zoledronate (ZLN) and osteoblast stimulation with parathyroid hormone (PTH).

METHODS

Arthritis was induced in 36 SKG mice. The mice were randomized to three treatment groups and an untreated group: ZLN, PTH, PTH+ZLN, and untreated. Arthritis score and ankle width measurements were performed. Histological sections were cut from the right hind paw, and design-based stereological estimators were used to quantify histological variables of bone volume and bone formation and resorption. The femora were DXA- and μCT-scanned, and the bone strength was determined at the femoral neck and mid-diaphysis.

RESULTS

Locally, we found no differences in arthritis score or ankle width throughout the study. Similarly, none of the treatments inhibited bone erosions or stimulated bone formation in the paw. Systemically, all treatments improved bone mineral density, strength of the femoral neck and mid-diaphysis, and μCT parameters of both cortical and trabecular bone. In addition, there was an additive effect of combination treatment compared with single treatments for most trabecular parameters including bone mineral density and bone volume fraction.

CONCLUSIONS

No local effect on bone was found by the combined action of inhibiting bone resorption and stimulating bone formation. However, a clear systemic effect of the combination treatment was demonstrated.

Buprenorphine does not impact the inflammatory response in haemophilia A mice with experimentally-induced haemarthrosis

Haemarthrosis is the most common clinical manifestation of haemophilia and is responsible for significant morbidity in haemophilic patients. The murine experimentally-induced knee bleeding model is an important model in haemophilia research but it is currently unknown if the use of analgesia in this model might impact on the inflammatory response. The aim was to investigate the inflammatory response after a needle induced knee bleed in haemophilia A mice treated with buprenorphine or saline. One hundred and sixty mice were randomized into two groups to blindly receive buprenorphine or saline. All the mice were anaesthetized and knee injury was induced by inserting a 30 G needle into the right knee joint. At t = 6, 24, 48 and 72 h, 20 mice from each group were terminated and the following parameters were assessed: change in body weight and joint diameter, visual bleeding score (VBS), white blood counts, haematocrit, platelet concentrations, haemoglobin, plasma haptoglobin and plasma and synovial fluid levels of 23 cytokines. Twenty mice were terminated at t = 0 receiving no injury or treatment to provide baseline measures. Twenty-one cytokines in plasma and 22 cytokines in synovial fluid, joint diameter change, VBS and blood parameters were not significantly altered by the administration of buprenorphine. Slight alterations of plasma haptoglobin at t = 48 h, body weight, plasma and synovial eotaxin and plasma G-CSF were found in buprenorphine-treated mice. We demonstrated that buprenorphine does not overall impact on the inflammatory response, and the use of buprenorphine in the knee bleeding model in haemophilic mice should be continued.

Interleukin 6 and rheumatoid arthritis

Interleukin-6 (IL-6) is a representative cytokine featuring pleiotropic activity and redundancy. A transient synthesis of IL-6 contributes to host defense against infectious agents and tissue injuries by inducing acute phase reactions and immunological and hematopoietic responses. However, uncontrolled persistent production of IL-6 may lead to the development of several immune-mediated diseases. Rheumatoid arthritis (RA) is a chronic disease with joint and systemic inflammation resulting from immunological abnormalities and it has been found that IL-6 plays a key role in the development of this disease. Clinical trials in various parts of the world of tocilizumab, a humanized anti-IL-6 receptor antibody, have proved its efficacy and tolerable safety either as monotherapy or in combination with disease-modifying antirheumatic drugs. As a result, it is currently used as a first-line biologic for the treatment of moderate-to-severe RA in more than 100 countries. Clarification of the mechanism(s) through which tocilizumab exerts its effect on RA and of the reason(s) why IL-6 is continuously produced in RA can be expected to lead to the best use of this agent for RA patients and aid in investigations into the pathogenesis of RA.

Regulatory T-cell differentiation and their function in immune regulation

Regulatory T-cells (Treg) represent a subset of CD4+ T-cells characterized by high suppressive capacity, which can be generated in the thymus or induced in the periphery. The deleterious phenotype of the Scurfy mouse, which develops an X-linked lymphoproliferative disease resulting from defective T-cell tolerance, clearly demonstrates the importance of Treg cells for the maintenance of immune homeostasis. Although significant progress has been achieved, much information regarding the development, characteristics and function of Treg cells remain lacking. This chapter highlights the most recent discoveries in the field of Treg biology, focusing on the development and role of this cell subset in the maintenance of immune balance.

CP-690550 Treatment Ameliorates Established Disease and Provides Long-Term Therapeutic Effects in an SKG Arthritis Model

Although pathogenesis of human rheumatoid arthritis (RA) remains unclear, arthritogenic T cells and downstream signaling mediators have been shown to play critical roles. An increasing numbers of therapeutic options have been added for the effective control of RA. Nevertheless, there is still a category of patients that fails treatment and suffers from progressive disease. The recently developed immunosuppressant CP-690550, a small molecule JAK kinase inhibitor, has been implicated as an important candidate treatment modality for autoimmune arthritis. In this study, we evaluated the therapeutic effect of CP-690550 on established arthritis using an SKG arthritis model, a pathophysiologically relevant animal model for human RA. CP-690550 treatment revealed remarkable long-term suppressive effects on SKG arthritis when administered to the well-advanced disease (clinical score 3.5~4.0). The treatment effect lasted at least 3 more weeks after cessation of drug infusion, and suppression of disease was correlated with the reduced pro-inflammatory cytokines, including IL-17, IFN-γ, and IL-6 and increased level of immunoregulatory IL-10.

Heat-killed VSL#3 ameliorates dextran sulfate sodium (DSS)-induced acute experimental colitis in rats

To determine the effects of heat-killed VSL#3 (B. breve, B. longum and B. infantis; L. plantarum, L. bulgaricus, L. casei and L. acidophilus; S. salivarius subsp. thermophilus) therapy in the dextran sulfate sodium (DSS)-induced acute experimental colitis in rats. Acute experimental colitis was induced in rats by 5% DSS and freely drink for seven days. Beginning on Day 8, rats underwent gavage once daily for seven days with heat-killed probiotic VSL#3 (0.6 g/kg/day), colonic damage was evaluated histologically and biochemically seven days after gavage. Expression of inflammatory related mediators (STAT3, P-STAT3) and cytokines (IL-6, IL-23, TGFβ) in colonic tissue were detected. The results revealed that heat-killed and live VSL#3 have identical anti-inflammatory properties by the assessed DAI (disease activity index), colon length, histological tissue and MPO activity. Heat-killed and live VSL#3 results in reduced IL-6, IL-23, TGFβ, STAT3 and P-STAT3 expression in colonic tissue. Heat-killed and live VSL#3 have showed the similar anti-inflammatory activity by inhibiting IL-6/STAT3 pathway in the DSS-induced acute experimental colitis in rats.

Arthritis augments breast cancer metastasis: role of mast cells and SCF/c-Kit signaling

Introduction

Breast cancer remains the second leading cause of cancer-related deaths for women in the United States. Metastasis is regulated not only by intrinsic genetic changes in malignant cells, but also by the microenvironment, especially those associated with chronic inflammation. We recently reported that mice with autoimmune arthritis have significantly increased incidence of bone and lung metastasis and decreased survival associated with breast cancer. In this study, we evaluated the mechanism underlying the increased metastasis.

Methods

We used two mouse models; one that develops spontaneous autoimmune arthritis (SKG mice) injected with metastatic breast cancer cells (4T1), and another that develops spontaneous breast cancer (MMTV-PyV MT mice) injected with type II collagen to induce autoimmune arthritis. Mast cell levels and metastasis were monitored.

Results

First, we confirmed that breast tumor-bearing arthritic mice have a significantly higher incidence of bone and lung metastasis than do their nonarthritic counterparts. Next, we showed increased recruitment of mast cells within the primary tumor of arthritic mice, which facilitates metastasis. Next, we report that arthritic mice without any tumors have higher numbers of mast cells in the bones and lungs, which may be the underlying cause for the enhanced lung and bone metastases observed in the arthritic mice. Next, we showed that once the tumor cells populate the metastatic niches (bones and lungs), they further increase the mast cell population within the niche and assist in enhancing metastasis. This may primarily be due to the interaction of c-Kit receptor present on mast cells and stem cell factor (SCF, the ligand for ckit) expressed on tumor cells. Finally, we showed that targeting the SCF/cKit interaction with an anti-ckit antibody reduces the differentiation of mast cells and consequently reduces metastasis.

Conclusion

This is the first report to show that mast cells may play a critical role in remodeling not only the tumor microenvironment but also the metastatic niche to facilitate efficient metastasis through SCF/cKit interaction in breast cancer with arthritis.

Neutrophils confer T cell resistance to myeloid-derived suppressor cell-mediated suppression to promote chronic inflammation

Low-grade chronic inflammation can persist in aging humans unnoticed for years or even decades, inflicting continuous damage that can culminate later in life as organ dysfunction, physical frailty, and some of the most prominent debilitating and deadly age-associated diseases, including rheumatoid arthritis, diabetes, heart disease, and cancer. Despite the near universal acceptance of these associations, the mechanisms underlying unresolved inflammation remain poorly understood. In this study, we describe a novel inducible method to examine systemic chronic inflammation using susceptible animal models. Induced inflammation results in unresolved innate cellular responses and persistence of the same serum proinflammatory molecules used as diagnostic biomarkers and therapeutic targets for chronic inflammation in humans. Surprisingly, we found long-term persistence of an inflammation-associated neutrophil cell population constitutively producing the proinflammatory IFN-γ cytokine, which until now has only been detected transiently in acute inflammatory responses. Interestingly, these cells appear to confer T cell resistance to the otherwise potent anti-inflammatory function of myeloid-derived suppressor cells, revealing a novel mechanism for the maintenance of chronic inflammatory responses over time. This discovery represents an attractive target to resolve inflammation and prevent the inflammation-induced pathologies that are of critical concern for the well-being of the aging population.

Suppressive effects of N-acetyl-D-glucosamine on rheumatoid arthritis mouse models

We examined effects of N-acetyl-D: -glucosamine (GlcNAc) on rheumatoid arthritis (RA) mouse models and effects of GlcNAc and glucosamine hydrochloride (GlcN) on several serum cytokine productions in RA mouse models. SKG/jcl mice were divided into control, GlcNAc, and GlcN groups. For 56 days, the control group received normal food, the GlcNAc group received 0.5 % GlcNAc-containing food, and the GlcN group received 0.5 % GlcN-containing food. GlcNAc and GlcN equally suppressed arthritis scores and histopathological scores compared to the control group. In the GlcN group, serum tumor necrosis factor-α and interleukin (IL)-6 concentrations were significantly decreased compared to the control group. In the GlcNAc group, serum IL-10, transforming growth factor β-1, and IL-2 concentrations were significantly increased compared to the control group. Our results indicated that GlcNAc also has suppressive effects on experimental RA in mouse models. The results of serum cytokine concentrations suggested that compared to GlcN, GlcNAc has a different suppressive mechanism in experimental RA models.

Bone formation and resorption are both increased in experimental autoimmune arthritis

INTRODUCTION

Arthritic bone loss in the joints of patients with rheumatoid arthritis is the result of a combination of osteoclastic bone resorption and osteoblastic bone formation. This process is not completely understood, and especially the importance of local inflammation needs further investigation. We evaluated how bone formation and bone resorption are altered in experimental autoimmune arthritis.

METHODS

Twenty-one female SKG mice were randomized to either an arthritis group or a control group. Tetracycline was used to identify mineralizing surfaces. After six weeks the right hind paws were embedded undecalcified in methylmethacrylate. The paws were cut exhaustively according to the principles of vertical sectioning and systematic sampling. 3D design-based methods were used to estimate the total number of osteoclasts, mineralizing surfaces, eroded surfaces, and osteoclast-covered bone surfaces. In addition the presence of adjacent inflammation was ascertained.

RESULTS

The total number of osteoclasts, mineralizing surfaces, eroded surfaces, and osteoclast covered surfaces were elevated in arthritic paws compared to normal paws. Mineralizing surfaces were elevated adjacent to as well as not adjacent to inflammation in arthritic mice compared to normal mice. In arthritic mice, eroded surfaces and osteoclast covered surfaces were larger on bone surfaces adjacent to inflammation than on bone surfaces without adjacent inflammation. However, we found no difference between mineralizing surfaces at bone surfaces with or without inflammation in arthritic mice.

CONCLUSIONS

Inflammation induced an increase in resorptive bone surfaces as well as formative bone surfaces. The bone formative response may be more general, since formative bone surfaces were also increased when not associated with inflammation. Thus, the bone loss may be the result of a substantial local bone resorption, which cannot be compensated by the increased local bone formation. These findings may be valuable for the development of new osteoblast targeting drugs in RA.

Increased toll-like receptor 2 expression in peptidoglycan-treated blood monocytes is associated with insulin resistance in patients with nondiabetic rheumatoid arthritis

The close relationship between increased TLR-2 expression in blood monocytes and insulin resistance in RA patients is shown in this study. Traditional risk factors for metabolic disorders, including the waist circumstance, body mass index (BMI), triglyceride (TG), and ratio of TG to high density lipoprotein (HDL) cholesterol, were closely correlated with HOMA (homoeostasis model assessment) index in patients with nondiabetic RA. Expressions of TLR2 in peripheral blood monocytes, following stimulation with peptidoglycan which is known as a TLR2 agonist, were closely correlated with the HOMA index, TNF-α, and IL-6 concentrations. Accordingly, TLR-2 receptor and its related inflammatory cytokines could be potential therapeutic targets in managing insulin resistance in RA patients.