The role of T cells in rheumatoid arthritis: new subsets and new targets

Neutrophils produce interleukin-17B in rheumatoid synovial tissue

OBJECTIVE

T helper 17 (Th17) and mast cells produce IL-17A in RA and critically contribute to the pathogenesis of RA. However, the complete IL-17 cytokine profile in RA is unknown. The aim of the study was to systematically study the expression of IL-17 family cytokines in RA.

METHODS

The expression of all IL-17 cytokines in RA synovium and pannus as well as in the synovium of OA was determined using quantitative RT-PCR (qRT-PCR). IL-17A and IL-17B were immunostained. Peripheral blood neutrophils were analysed for IL-17B. The effect of IL-17B alone or in combination with TNF-α was tested in vitro on fibroblasts and endothelial cells.

RESULTS

In all tissues IL-17B was the most expressed IL-17 family cytokine, found in lining but most strongly expressed in human neutrophil elastase containing polymorphonuclear cells. This pattern was distinct from that of IL-17A, which was found in mast cell tryptase immunoreactive cells. Circulating neutrophils contained IL-17B, verifying the in vivo results. Fibroblasts up-regulated the expression of IL-17RB, a putative receptor of IL-17B, after TNF-α stimulation. IL-17B significantly enhanced TNF-α-induced production of G-CSF and IL-6 in fibroblasts.

CONCLUSION

IL-17B, which is present in synovium, may contribute to the pathogenesis of RA. IL-17B can enhance the effects of TNF-α on the production of cytokines and chemokines that control immune cell trafficking and neutrophil homeostasis in the inflamed tissues.

Patients with the most advanced rheumatoid arthritis remain with Th1 systemic defects after TNF inhibitors treatment despite clinical improvement

Systemic immune defects might reflect severely dysregulated control of chronic inflammation related to disease progression. Th17/Treg cell imbalance has been demonstrated to be involved in rheumatoid arthritis (RA) pathogenesis. Despite controversial results, a growing anti-inflammatory role in this process has been recently attributed to Th1 responses. The aim of the study was to estimate the extent of Th1/Th17/Treg imbalance in peripheral blood (PB) of patients with short- and long-term RA in relation to cytokine milieu and its reversal after therapy with methotrexate and/or TNF inhibitors, respectively. Patients with different duration of RA (median 6 vs. 120 months) in the active phase of RA were enrolled in this study. We performed flow cytometric analysis of PB Th1, Th17, and Treg populations together with estimation of serum cytokine concentrations using cytometric bead array. Disease activity was calculated on the basis of clinical and biochemical indices of inflammation (DAS28, ESR, CRP). All parameters were measured and correlated with each other before and after 6 months therapy. Elevated levels of circulating Th17 cells and IL-6 were found in all active patients, of which Th17 cells were down-regulated by the treatment. Significantly reduced Th1 and functional CTLA-4+ Treg cell frequencies as well as Th1 cytokines observed only in progressive RA seemed to be irreversible. Although therapy induced clinical improvement in almost all patients, those with advanced RA remained with signs of inflammation. Our report demonstrates that both the extent of systemic immune abnormalities and their restoration are dependent on duration of the active RA.

Interleukin-17A- or tumor necrosis factor α-mediated increase in proliferation of T cells cocultured with synovium-derived mesenchymal stem cells in rheumatoid arthritis

Introduction

Mesenchymal stem cells (MSCs) represent promising applications in rheumatoid arthritis (RA). However, the inflammatory niche in the RA synovium could adversely affect MSC function. This study was designed to investigate biologic and immunologic properties of synovium-derived MSCs (SMSCs) in RA, with particular focus on whether cytokines can mediate increase of proliferation of T cells cocultured with SMSCs in RA.

Methods

Compared with SMSCs from eight healthy donors (HDs), SMSCs from 22 patients with RA (RAp) were evaluated. The methyl thiazolyl tetrazolium (MTT) assay was used to assess cell-population doubling and viability. Multipotentiality of SMSCs was examined by using appropriate culture conditions. Flow cytometry was used to investigate the marker phenotype of SMSCs. Immunomodulation potential of SMSCs was examined by mixed peripheral blood mononuclear cells (PBMCs) reactions, and then by PBMCs or synovial T cells with or without the addition of inflammatory cytokines (interleukin-17A (IL-17A), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ)) after stimulation with phytohemagglutinin (PHA), respectively.

Results

SMSCs from RA patients (RA-SMSCs) showed normal population doubling, cell viability, multiple differentiation characteristics, and surface markers. In either mixed PBMC reactions or PBMC proliferation stimulated with PHA, RA-SMSCs showed normal immunomodulation function compared with SMSCs from healthy donors (HD-SMSCs). However, the increase in proliferation of T cells was observed when IL-17A and TNF-α were added alone or in combination.

Conclusions

Our data suggest that the inflammatory niche, especially these cytokines, may increase the proliferation of T cells cocultured with SMSCs in RA.

Rheumatoid arthritis with deficiency pattern in traditional chinese medicine shows correlation with cold and hot patterns in gene expression profiles

In our precious study, the correlation between cold and hot patterns in traditional Chinese medicine (TCM) and gene expression profiles in rheumatoid arthritis (RA) has been explored. Based on TCM theory, deficiency pattern is another key pattern diagnosis among RA patients, which leads to a specific treatment principle in clinical management. Therefore, a further analysis was performed aiming at exploring the characteristic gene expression profile of deficiency pattern and its correlation with cold and hot patterns in RA patients by bioinformatics analysis approach based on gene expression profiles data detected with microarray technology. The TCM deficiency pattern-related genes network comprises 7 significantly, highly connected regions which are mainly involved in protein transcription processes, protein ubiquitination, toll-like receptor activated NF- κ B regulated gene transcription and apoptosis, RNA clipping, NF- κ B signal, nucleotide metabolism-related apoptosis, and immune response processes. Toll-like receptor activated NF- κ B regulated gene transcription and apoptosis pathways are potential specific pathways related to TCM deficiency patterns in RA patients; TCM deficiency pattern is probably related to immune response. Network analysis can be used as a powerful tool for detecting the characteristic mechanism related to specific TCM pattern and the correlations between different patterns.

T cells out of control--impaired immune regulation in the inflamed joint

Since the discovery of FOXP3+ regulatory T (T(REG)) cells over 15 years ago, intensive research has focused on their presence, phenotype and function in autoimmune disease. Whether deficiencies in T(REG) cells underlie autoimmune pathology and whether, or how, therapeutic approaches based on these cells might be successful is still the subject of debate. The potential role of T(REG)-cell extrinsic factors, such as proinflammatory cytokines and resistance of effector T cells to suppression, as the cause of regulatory defects in chronic autoimmune inflammation is an intensive area of research. It is now clear that, at the site of inflammation, antigen presenting cells (APCs) and proinflammatory cytokines drive effector T cell skewing and plasticity, and that these T cells can become unresponsive to regulation. In addition, expansion and function of T(REG) cells is affected by the inflammatory environment; indeed, new data suggest that, in certain conditions, T(REG) cells promote inflammation. This Review summarizes the latest findings on changes in effector T cell homeostasis in autoimmune disease and focuses on how mechanisms that normally regulate these cells are affected in the inflamed joints of patients with arthritis. These findings have important clinical implications and will affect the development of new therapeutic strategies for autoimmune arthritis.

Deficiency of β-arrestin1 ameliorates collagen-induced arthritis with impaired TH17 cell differentiation

Rheumatoid arthritis (RA) is an inflammatory disease in which interleukin 17 (IL-17)-producing T helper 17 (T(H)17) cells have been critically involved. We show that in patients with RA, the expression of a multifunctional regulator β-arrestin1 was significantly up-regulated in peripheral and synovial CD4(+) T cells, which correlated well with active phases of RA. In collagen-induced arthritis, deficiency of β-arrestin1 ameliorated disease with decreased T(H)17 cell differentiation, proinflammatory cytokine production, synovitis, and cartilage and bone destruction. Further mechanistic study reveals that β-arrestin1 promoted signal transducer and activator of transcription 3 (STAT3) activation required for T(H)17 cell differentiation through scaffolding the interaction of Janus kinase 1 and STAT3. These findings indicate a critical role for β-arrestin1 in the pathogenesis of collagen-induced arthritis and T(H)17 cell differentiation and suggest β-arrestin1 as a potential diagnostic biomarker and therapeutic target for RA.

Adaptive immunity in rheumatic diseases: bystander or pathogenic player?

Rheumatic diseases comprise a wide spectrum of different conditions. Some are caused by disturbances of the adaptive immune system, while defects in innate immune responses have been identified for others. In between are a variety of multifactorial diseases for which the evidence for a causative involvement of the adaptive immune system is still controversial. In these cases, availability of novel drugs that target key players of the adaptive immune system have improved our understanding of the relevance of adaptive immunity to the disease process, but it has also generated unprecedented findings. Rheumatoid arthritis (RA) is a prototypic example of a disease in which the relative contribution of adaptive immunity to disease pathogenesis is incompletely understood. Although numerous markers have been identified that reflect an activated adaptive immune system, several caveats render interpretation of these findings difficult. For one, the very early immune responses initiating disease are likely to take place before an individual is identified as a patient, and are thus difficult to study in the human. Furthermore, increasing evidence points to pathogenetically distinct subgroups within the clinical diagnosis RA, offering the possibility that adaptive immune responses might be relevant to one subgroup but not the other. In addition, many indications for an adaptive immune system involvement are based on associations for which the underlying mechanism is often unknown. Finally, therapeutic interventions targeting the adaptive immune system have generated heterogeneous results. The present review addresses these issues by placing adaptive immune responses in the context of rheumatic diseases, and by reviewing the evidence for a contribution of adaptive immunity to RA.

Combined use of pharmacophoric models together with drug metabolism and genotoxicity "in silico" studies in the hit finding process

In this study we propose a virtual screening strategy based on the generation of a pharmacophore hypothesis, followed by an in silico evaluation of some ADME-TOX properties with the aim to apply it to the hit finding process and, specifically, to characterize new chemical entities with potential to control inflammatory processes mediated by T lymphocytes such as multiple sclerosis, systemic lupus erithematosus or rheumatoid arthritis. As a result, three compounds with completely novel scaffolds were selected as final hits for future hit-to-lead optimization due to their anti-inflammatory profile. The biological results showed that the selected compounds increased the intracellular cAMP levels and inhibited cell proliferation in T lymphocytes. Moreover, two of these compounds were able to increase the production of IL-4, an immunoregulatory cytokine involved in the selective deviation of T helper (Th) immune response Th type 2 (Th2), which has been proved to have anti-inflammatory properties in several animal models for autoimmune pathologies as multiple sclerosis or rheumatoid arthritis. Thus our pharmacological strategy has shown to be useful to find molecules with biological activity to control immune responses involved in many inflammatory disorders. Such promising data suggested that this in silico strategy might be useful as hit finding process for future drug development.

Tracking and treating activated T cells

Upon activation, T cells of various subsets are the most important mediators in cell-mediated immune responses. Activated T cells play an important role in immune system related diseases such as chronic inflammatory diseases, viral infections, autoimmune disease, transplant rejection, Crohn disease, diabetes, and many more. Therefore, efforts have been made to both visualize and treat activated T cells specifically. This review summarizes imaging approaches and selective therapeutics for activated T cells and gives an outlook on how tracking and treating can be combined into theragnositc agents for activated T cells.

The expression and anatomical distribution of BTLA and its ligand HVEM in rheumatoid synovium

Co-inhibitory signaling from B and T lymphocyte attenuator (BTLA) can suppress lymphocyte activation and maintain peripheral tolerance. However, the expression and anatomical distribution of BTLA and its ligand, herpesvirus entry mediator (HVEM), in rheumatoid arthritis (RA) synovium have not been reported. In this study, we analyzed the expression of HVEM and BTLA in RA synovium by immunohistochemistry, and our results showed that both factors were observed in all four cases of RA samples. At the cellular level, both HVEM and BTLA were found on the cell membrane and in the cytoplasm. Fluorescence dual staining demonstrated that HVEM was chiefly on CD3(+) T cells, CD68(+) macrophages, and to a lesser extent was found on CD31(+) endothelial cells. Similarly, the expression of BTLA was observed on infiltrated CD3(+) T cells and CD68(+) macrophages. The co-expression of HVEM and BTLA with some members of the B7 family in these sections was also analyzed, and the results showed that HVEM antigen was also found on B7-H3(+) capillaries, while it was absent on B7-H1(+), B7-DC(+), B7-H4(+), and Z39Ig(+) cells. Interestingly, BTLA was observed on B7-H1(+), B7-H4(+), and HVEM(+) cells in the synovium. The characteristic expression and distribution of BTLA/HVEM in the synovium indicated that their signaling probably affects the pathogenesis of RA, and a clear understanding of their functional roles may further elucidate the pathogenesis of this disease.

Bone marrow-derived and synovium-derived mesenchymal cells promote Th17 cell expansion and activation through caspase 1 activation: contribution to the chronicity of rheumatoid arthritis

OBJECTIVE

Th17 cells have been implicated in rheumatoid arthritis (RA). We hypothesized that the interaction of T cells with bone marrow-derived mesenchymal stem cells (BM-MSCs) or with fibroblast- like synoviocytes (FLS) might, with the help of T cell-secreted inflammatory cytokines (i.e., interleukin-17A [IL-17A], tumor necrosis factor α [TNFα], and/or interferon-γ [IFNγ]), promote Th17 cell expansion and activation.

METHODS

Peripheral blood mononuclear cells (PBMCs) from healthy blood donors were cocultured with BM-MSCs or FLS from RA patients or osteoarthritis (OA) patients. Cocultures were exposed to phytohemagglutinin with or without IL-17A, TNFα, or IFNγ. Quantitative reverse transcription-polymerase chain reaction analysis, enzyme-linked immunosorbent assay, and cytofluorometry were used to measure IL-17A production.

RESULTS

Interaction of PBMCs with BM-MSCs inhibited Th1 and Th2 responses, but promoted Th17 cell expansion, as early as 24 hours, as demonstrated by increases in retinoic acid receptor-related orphan nuclear receptor γ or IL-17A messenger RNA (mRNA) levels, IL-17A secretion levels, and IL-17A-secreting cell frequency, as well as by T cell switching to the Th17 pathway after 2 rounds of stimulation with MSCs. IL-17A production was also increased in PBMCs stimulated with anti-CD3 plus anti-CD28 or in isolated CD3+ or CD45RO+ T cells, thus demonstrating the role of T cell activation. Levels of mRNA for IL-6, IL-8, and IL-1β were further amplified when T cell-secreted inflammatory cytokines were added. Interestingly, OA FLS or RA FLS also enhanced IL-17A and IL-6 production, but only RA FLS enhanced IFNγ and IL-1β production. We further demonstrated that MSC-mediated Th17 promotion requires caspase 1 activation by using an inhibitory peptide and measuring its activity.

CONCLUSION

We found that the interaction of MSCs or FLS with T cells promotes the activation and expansion of Th17 cells through caspase 1 activation. Since proinflammatory and T cell-secreted inflammatory cytokines are also amplified, this mechanism may participate in the chronicity of RA.

Autoreactive T Cells in Human Smokers is Predictive of Clinical Outcome

Cross-sectional studies have suggested a role for activation of adaptive immunity in smokers with emphysema, but the clinical application of these findings has not been explored. Here we examined the utility of detecting autoreactive T cells as a screening tool for emphysema in an at-risk population of smokers. We followed 156 former and current (ever)-smokers for 2 years to assess whether peripheral blood CD4 T cell cytokine responses to lung elastin fragments (EFs) could discriminate between those with and without emphysema, and to evaluate the relevance of autoreactive T cells to predict changes during follow-up in lung physiological parameters. Volunteers underwent baseline complete phenotypic assessment with pulmonary function tests, quantitative chest CT, yearly 6-min walk distance (6MWD) testing, and annual measurement of CD4 T cell cytokine responses to EFs. The areas under the receiver operating characteristic curve to predict emphysema for interferon gamma (IFN-γ), and interleukin 6 (IL-6) responses to EFs were 0.81 (95% CI of 0.74-0.88) and 0.79 (95% CI of 0.72-0.86) respectively. We developed a dual cytokine enzyme-linked immunocell spot assay, the γ-6 Spot, using CD4 T cell IFN-γ and IL-6 responses and found that it discriminated emphysema with 90% sensitivity. After adjusting for potential confounders, the presence of autoreactive T cells was predictive of a decrease in 6MWD over 2 years (decline in 6MWD, -19 m per fold change in IFN-γ; P = 0.026, and -26 m per fold change in IL-6; P = 0.003). In support of the human association studies, we cloned CD4 T cells with characteristic T helper (Th)1 and Th17 responses to EFs in the peripheral blood of ever-smokers with emphysema, confirming antigenicity of lung elastin in this population. These findings collectively suggest that the EF-specific autoreactive CD4 T cell assay, γ-6 Spot, could provide a non-invasive diagnostic tool with potential application to large-scale screening to discriminate emphysema in ever-smokers, and predict early relevant physiological outcomes in those at risk.

CCR5 gene polymorphism is a genetic risk factor for radiographic severity of rheumatoid arthritis

The chemokine receptor [C-C chemokine receptor 5 (CCR5)] is expressed on diverse immune effecter cells and has been implicated in the pathogenesis of rheumatoid arthritis (RA). This study sought to determine whether single-nucleotide polymorphisms (SNPs) in the CCR5 gene and their haplotypes were associated with susceptibility to and severity of RA. Three hundred fifty-seven patients with RA and 383 healthy unrelated controls were recruited. Using a pyrosequencing assay, we examined four polymorphisms -1118 CTAT(ins) (/del) (rs10577983), 303 A>G (rs1799987), 927 C>T (rs1800024), and 4838 G>T (rs1800874) of the CCR5 gene, which were distributed over the promoter region as well as the 5' and 3' untranslated regions. No significant difference in the genotype, allele, and haplotype frequencies of the four selected SNPs was observed between RA patients and controls. CCR5 polymorphisms of -1118 CTAT(del) (P = 0.012; corrected P = 0.048) and 303 A>G (P = 0.012; corrected P = 0.048) showed a significant association with radiographic severity in a recessive model, and, as a result of multivariate logistic regression analysis, were found to be an independent predictor of radiographic severity. When we separated the erosion score from the total Sharp score, the statistical significance of CCR5 polymorphisms showed an increase; -1118 CTAT(ins) (/del) (P = 0.007; corrected P = 0.028) and 303 A>G (P = 0.007; corrected P = 0.028). Neither SNPs nor haplotypes of the CCR5 gene showed a significant association with joint space narrowing score. These results indicate that genetic polymorphisms of CCR5 are an independent risk factor for radiographic severity denoted by modified Sharp score, particularly joint erosion in RA.

Therapeutic effect of an altered peptide ligand derived from heat-shock protein 60 by suppressing of inflammatory cytokines secretion in two animal models of rheumatoid arthritis

Rheumatoid arthritis is a systemic autoimmune disease mediated by T cells. Productive engagement of T cell receptors by major histocompatibility complex-peptide leads to proliferation, differentiation and the definition of effector functions. Altered peptide ligands (APL) generated by amino acid substitutions in the antigenic peptide have diverse effects on T cell response. We predicted a novel T cell epitope from human heat-shock protein 60, an autoantigen involved in the pathogenesis of rheumatoid arthritis. Three APLs were designed from this epitope and it was demonstrated that these peptides induce the activation of T cells through their ability to modify cell cycle phase's distribution of CD4+T cells from RA patients. Also, IL-17, TNF-α and IL-10 levels were determined in PBMC from these patients. Unlike the wild-type peptide and the other two APLs, APL2 increased the IL-10 level and suppressed IL-17 secretion in these assays. Therapeutic effect of this APL in adjuvant arthritis (AA) and collagen-induced arthritis (CIA) models was also evaluated. Clinical score, histopathology, inflammatory and regulatory cytokine concentration were monitored in the animals. APL2 efficiently inhibited the progression of AA and CIA with a significant reduction of the clinical and histopathologic score. Therapeutic effect of APL2 on CIA was similar to that obtained with MTX; the standard treatment for RA. This effect was associated with a decrease of TNF-α and IL-17 levels. These results suggest that the therapeutic effect of APL2 is mediated in part by down-regulation of inflammatory cytokines and support the potential use of APL2 as a therapeutic drug in RA patients.

PDLIM2 restricts Th1 and Th17 differentiation and prevents autoimmune disease

Background

PDLIM2 is essential for the termination of the inflammatory transcription factors NF-κB and STAT but is dispensable for the development of immune cells and immune tissues/organs. Currently, it remains unknown whether and how PDLIM2 is involved in physiologic and pathogenic processes.

Results

Here we report that naive PDLIM2 deficient CD4⁺ T cells were prone to differentiate into Th1 and Th17 cells. PDLIM2 deficiency, however, had no obvious effect on lineage commitment towards Th2 or Treg cells. Notably, PDLIM2 deficient mice exhibited increased susceptibility to experimental autoimmune encephalitis (EAE), a Th1 and/or Th17 cell-mediated inflammatory disease model of multiple sclerosis (MS). Mechanistic studies further indicate that PDLIM2 was required for restricting expression of Th1 and Th17 cytokines, which was in accordance with the role of PDLIM2 in the termination of NF-κB and STAT activation.

Conclusion

These findings suggest that PDLIM2 is a key modulator of T-cell-mediated immune responses that may be targeted for the therapy of human autoimmune diseases.

Cigarette smoke induction of osteopontin (SPP1) mediates T(H)17 inflammation in human and experimental emphysema

Smoking-related lung diseases are among the leading causes of death worldwide, underscoring the need to understand their pathogenesis and develop new effective therapies. We have shown that CD1a+ antigen-presenting cells (APCs) from lungs of patients with emphysema can induce autoreactive T helper 1 (T(H)1) and T(H)17 cells. Similarly, the canonical cytokines interferon-γ (IFN-γ) and interleukin-17A (IL-17A) are specifically linked to lung destruction in smokers, but how smoke activates APCs to mediate emphysema remains unknown. Here, we show that, in addition to increasing IFN-γ expression, cigarette smoke increased the expression of IL-17A in both CD4+ and γδ T cells from mouse lung. IL-17A deficiency resulted in attenuation of, whereas lack of γδ T cells exacerbated, smoke-induced emphysema in mice. Adoptive transfer of lung APCs isolated from mice with emphysema revealed that this cell population was capable of transferring disease even in the absence of active smoke exposure, a process that was dependent on IL-17A expression. Spp1 (the gene for osteopontin) was highly expressed in the pathogenic lung APCs of smoke-exposed mice and was required for the T(H)17 responses and emphysema in vivo, in part through its inhibition of the expression of the transcription factor Irf7. Thus, the Spp1-Irf7 axis is critical for induction of pathological T(H)17 responses, revealing a major mechanism by which smoke activates lung APCs to induce emphysema and identifying a pathway that could be targeted for therapeutic purposes.

IL-13 Signaling in Liver Fibrogenesis

Liver fibrosis is the final common pathway of chronic liver diseases irrespective of etiology. However, etiology deeply impacts progression and characteristics of liver fibrogenesis. IL-13 is the dominant pro-fibrotic cytokine in Schistosomiasis associated liver fibrogenesis. In vitro, IL-13 directly induces expression of fibrosis-associated genes, e.g., collagens or connective tissue growth factor, in hepatic stellate cells. Recently, potential effects of IL-13 in non-Schistosomiasis associated liver fibrosis have been uncovered. This review summarizes the potential roles of IL-13 in chronic liver disease of different etiologies, and the downstream events mediating IL-13 signaling in liver fibrogenesis.

A murine autoimmune model of rheumatoid arthritis and systemic lupus erythematosus associated with deregulated production of IL-17 and IL-21

T-helper cell 17 (Th17) cells play an important role in the pathogenesis of many autoimmune disorders including Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE). In this chapter we describe a murine model where deregulated production of IL-17 and IL-21 can lead to either lupus-like disease or RA-like symptoms depending on the genetic background. We delineate the key techniques that can be used to dissect the mechanisms responsible for the pathogenesis of these diseases at both a cellular and molecular level including in vitro Th17 cell differentiation, chromatin immunoprecipitation assays, and retroviral transduction experiments. We also describe the methodologies that can be utilized to monitor the classic clinical findings of RA and SLE in murine models. Given the broad involvement of deregulated production of IL-17 and IL-21 in autoimmunity, many of these techniques could also be valuable for the investigation of these pathways in murine models of other autoimmune diseases.

Serum free light chains as biomarkers for systemic lupus erythematosus disease activity

OBJECTIVE

To evaluate serum free light chains (FLC) as a putative biomarker of systemic lupus erythematosus (SLE) activity.

METHODS

Seventy-five SLE patients and 41 age- and sex-matched rheumatoid arthritis (RA) controls were enrolled. Disease activity was assessed using the Safety of Estrogens in Lupus Erythematosus: National Assessment version of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) definition and physician global assessments for SLE and the Disease Activity Score in 28 joints for RA. Serum FLC levels were compared against other biomarkers (IgG, C3, C4, double-stranded DNA [dsDNA] antibody). Nonparametric tests were used to compare 1) FLC and IgG in SLE versus RA and healthy controls, 2) FLC and IgG among different levels of activity in SLE, and 3) FLC in active versus nonactive RA. Correlation of FLC, C3, C4, dsDNA antibody, and IgG with the SLEDAI and modified SLEDAI (M-SLEDAI) were obtained.

RESULTS

FLC was higher in SLE than in RA; both were higher than referent healthy controls. Total FLC was significantly higher in subjects with greater SLE disease activity than lower/no activity. There were no significant differences in IgG, C4, or dsDNA antibody stratified by disease activity. Total FLC and C3 showed moderate to strong correlation with the SLEDAI and M-SLEDAI. In RA, no differences were seen in FLC levels for different levels of disease activity. Similar results were seen after controlling for renal function, age, and sex. In multiple linear regression, FLC significantly explained 50% variance of the SLEDAI after adjusting for renal function, age, and sex.

CONCLUSION

Serum FLC levels correlate strongly with disease activity in SLE, but not in RA. Serum FLC may be used as a biomarker of SLE disease activity.

Effects of interleukin (IL)-17A and IL-17F in human rheumatoid arthritis synoviocytes

Rheumatoid arthritis (RA) is a chronic inflammatory disease where the contribution of T cells is now supported by clinical results. Among the cytokines produced by T cells, interleukin (IL)-17A (previously known as IL-17) and IL-17F constitute the signature cytokines of the newly described Th17 T helper cell subset. While the effects of IL-17A on RA synoviocytes been well described, those of IL-17F remain less studied. The present review describes the effects of IL-17A and IL-17F on synoviocytes and their contribution to RA pathogenesis. Although IL-17F is less active than IL-17A when used alone, IL-17A and IL-17F induce in synoviocytes a rather similar expression pattern in the presence of tumour necrosis factor α. They enhance their response by stabilising mRNA of cytokines and enhancing receptor expression. They increase the migration, chemokine gene expression and invasiveness of synoviocytes. They contribute to disease chronicity by inhibiting synoviocyte apoptosis. Finally, they enhance metalloprotease secretion leading to cartilage damage. These properties support the combined inhibition of IL-17A and -F to control RA inflammation and joint destruction.

An altered peptide ligand corresponding to a novel epitope from heat-shock protein 60 induces regulatory T cells and suppresses pathogenic response in an animal model of adjuvant-induced arthritis

Induction of immune tolerance as therapeutic approach for autoimmune diseases constitutes a current research focal point. In this sense, we aimed to evaluate an altered peptide ligand (APL) for induction of peripheral tolerance in patients with rheumatoid arthritis (RA). A novel T-cell epitope from human heat-shock protein 60 (Hsp60), an autoantigen involved in the pathogenesis of RA, was identified by bioinformatics tools and an APL was design starting from this epitope. We investigated the ability of this APL for inducing regulatory T cells (Treg cells) in mice and evaluated the therapeutic effect of this peptide in an adjuvant-induced arthritis (AA) rat model. Clinical score, TNFα levels and histopathology were monitored, as well as the capacity of this APL for inducing Treg cells. Finally, the potentialities of the APL for inducing Treg cells were evaluated in ex vivo assays using mononuclear cells isolated from peripheral blood (PBMC). The APL induced an increase of the proportions of Treg cells in the draining lymph nodes of the injected site in mice. The APL efficiently inhibited the course of AA, with significant reduction of the clinical and histopathology score. This effect was associated with an increase of the proportions of Treg cells and a decrease of TNFα levels in spleen. Finally, stimulation of PBMCs from RA patients by the APL increases the proportions of the CD4(+)CD25(high)FoxP3(+) Treg cells. These results indicate a therapeutic potentiality of APL and support further investigation of this candidate drug for treatment of RA.

IL-17A- versus IL-17F-induced intracellular signal transduction pathways and modulation by IL-17RA and IL-17RC RNA interference in rheumatoid synoviocytes

OBJECTIVE

The aim of this study was to compare the effects of interleukin (IL)-17A and IL-17F on gene expression and signalling in human rheumatoid arthritis (RA) synoviocytes.

METHODS

IL-17A- and IL-17F-induced mRNA expression was analysed using Affymetrix microarrays. IL-6 and IL-8 secretion was evaluated by ELISA. Inhibition of two receptors (IL-17RA and IL-17RC) was achieved by small interfering RNA (saran). The effects on mitogen-activated protein kinase (MAPK), activator protein 1 (AP-1) and nuclear factor κB (NF-κB) expression and activation were evaluated by western blotting, qRT-PCR and DNA binding assay.

RESULTS

IL-17A and IL-17F induced a molecular pattern characterised by 27 inflammation-related genes for IL-17F and 165 for IL-17A. Virtually all IL-17A and IL-17F inducible genes were dependent on NF-κB activation, whereas a small number were modulated by p38. IL-17A induced activation of all three MAPKs (ERK, p38 and JNK) and downstream transcription factors AP-1 and p65 NF-κB. IL-17F was less potent but induced activation of p50 NF-κB. IL-17A was more potent at inducing IL-6 secretion than IL-17F, which was inactive alone. IL-17A and, to a lesser extent, IL-17F induced TRAF6 but not MyD88. Inhibition of either IL-17RA or IL-17RC expression via siRNA led to near complete abrogation of IL-6 expression mediated by IL-17A and the combination of IL-17F and tumour necrosis factor α.

CONCLUSION

Like IL-17A, IL-17F regulates proinflammatory gene expression by a very similar but not identical signalling pathway involving IL-17RA and IL-17RC.

Plasmid-encoded NP73-102 modulates atrial natriuretic peptide receptor signaling and plays a critical role in inducing tolerogenic dendritic cells

Background

Atrial natriuretic peptide (ANP) is an important endogenous hormone that controls inflammation and immunity by acting on dendritic cells (DCs); however, the mechanism remains unclear.

Objective

We analyzed the downstream signaling events resulting from the binding of ANP to its receptor, NPRA, and sought to determine what aspects of this signaling modulate DC function.

Methods

We utilized the inhibitory peptide, NP73-102, to block NPRA signaling in human monocyte-derived DCs (hmDCs) and examined the effect on DC maturation and induced immune responses. The potential downstream molecules and interactions among these molecules involved in NPRA signaling were identified by immunoprecipitation and immunoblotting. Changes in T cell phenotype and function were determined by flow cytometry and BrdU proliferation ELISA. To determine if adoptively transferred DCs could alter the in vivo immune response, bone marrow-derived DCs from wild-type C57BL/6 mice were incubated with ovalbumin (OVA) and injected i.v. into C57BL/6 NPRA-/- knockout mice sensitized and challenged with OVA. Lung sections were stained and examined for inflammation and cytokines were measured in bronchoalveolar lavage fluid collected from parallel groups of mice.

Results

Inhibition of NPRA signaling in DCs primes them to induce regulatory T cells. Adoptive transfer of wild type DCs into NPRA-/- mice reverses the attenuation of lung inflammation seen in the NPRA-knockout model. NPRA is associated with TLR-2, SOCS3 and STAT3, and inhibiting NPRA alters expression of IL-6, IL-10 and TGF-β, but not IL-12.

Conclusions

Modulation of NPRA signaling in DCs leads to immune tolerance and TLR2 and SOCS3 are involved in this induction.

Intra-articular electrotransfer of mouse soluble tumour necrosis factor receptor in a murine model of rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation and destruction of the joints. In the collagen-induced arthritis mouse model of RA, we developed a nonviral gene therapy method designed to block in situ the main cytokine tumour necrosis factor (TNF)-alpha

METHODS

Electrotransfer was used to deliver a plasmid encoding extracellular domain of mouse soluble TNF-alpha receptor type I fused to the Fc fragment of mouse immunoglobulin (Ig)G1 (pTNFR-Is) corresponding to a dimeric TNF-alpha soluble receptor fusion protein (mTNFR-Is/Ig).

RESULTS

Delivery of the plasmid into the knees at symptom onset improved the histological inflammation and destruction not only at the knees, but also at the ankles, indicating a local and a regional therapeutic effect. The plasmid was detected in synovial membrane and meniscus specimens from the injected joints. In the synovial membrane, 15 days post-injection, interleukin (IL)-17 and TNF-alpha mRNAs expression were increased, whereas IL-10 mRNA was unchanged. However, the empty plasmid exerted a pro-inflammatory effect 30 days post-injection.

CONCLUSIONS

These data indicate that local nonviral gene therapy against TNF-alpha is effective, although further work is needed to decrease plasmid induced inflammation.

Mice producing less reactive oxygen species are relatively resistant to collagen glycopeptide vaccination against arthritis

The bottleneck for the induction of collagen-induced arthritis in mice is the recognition of immunodominant type II collagen (CII) peptide (CII259-273) bound to the MHC class II molecule A(q). We have shown previously that the posttranslationally glycosylated lysine at position 264 in this epitope is of great importance for T cell recognition and tolerance induction to CII as well as for arthritis development. The Ncf1 gene, controlling oxidative burst, has been shown to play an important role for immune tolerance to CII. To investigate the effect of oxidation on the efficiency of immune-specific vaccination with MHC class II/glycosylated-CII peptide complexes, we used Ncf1 mutated mice. We demonstrate that normal reactive oxygen species (ROS) levels contribute to the establishment of tolerance and arthritis protection, because only mice with a functional oxidative burst were completely protected from arthritis after administration of the glycosylated CII259-273 peptide in complex with MHC class II. Transfer of T cells from vaccinated mice with functional Ncf1 protein resulted in strong suppression of clinical signs of arthritis in B10.Q mice, whereas the Ncf1 mutated mice as recipients had a weaker suppressive effect, suggesting that ROS modified the secondary rather than the primary immune response. A milder but still significant effect was also observed in ROS deficient mice. During the primary vaccination response, regulatory T cells, upregulation of negative costimulatory molecules, and increased production of anti-inflammatory versus proinflammatory cytokines in both Ncf1 mutated and wild type B10.Q mice was observed, which could explain the vaccination effect independent of ROS.

Pan-CC chemokine neutralization restricts splenocyte egress and reduces inflammation in a model of arthritis

Chemokines are key regulators of leukocyte trafficking and play a crucial role under homeostatic and inflammatory conditions. Because chemokines are involved in multiple pathologies, they represent an attractive class of therapeutic targets. However, because of the redundancy of this system, neutralizing a single chemokine may be insufficient to achieve therapeutic benefit. Our strategy was to use a Fc-fusion recombinant protein form of the poxvirus-derived viral CC chemokine inhibitor protein (vCCI-Fc) that has the ability to specifically bind to multiple CC chemokines and neutralize their activity. In this study, we demonstrate first that, in vivo, vCCI-Fc prevents CC chemokine-dependent migration of macrophages into inflamed tissue of carageenan-challenged mice. We next studied this effect of inhibiting CC chemokine activity in a model more relevant to human disease, collagen-induced arthritis. Mice receiving vCCI-Fc revealed a striking retention of splenocytes, including activated and IFN-gamma-secreting CD4(+) and CD8(+) T cells, that was associated with a concomitant decrease of cells in the draining lymph nodes. These phenomena resulted in a significant decrease in the incidence of disease and a reduction in clinical score, joint inflammation, and cartilage destruction as compared with mice receiving isotype control. Taken together, these results define a role for CC chemokines in the control of disease, as interfering with their function leads to a previously unappreciated role of controlling inflammatory cell trafficking in and out of secondary lymphoid organs.

Role of regulatory T cells in rheumatoid arthritis: facts and hypothesis

Regulatory T cells (Treg) are a CD4⁺ lymphocyte subset involved in self-tolerance and autoimmunity prevention. There is evidence for a phenotypic and/or functional impairment of this cell subset during the natural history of several chronic autoimmune/inflammatory diseases, including rheumatoid arthritis (RA). Although the intracellular transcription factor FoxP3 is thought to be the master regulator of Treg cell function, a number of other molecules expressed on the cell surface have been proposed for the identification of Treg cells. This is important in order to favour their possible selective isolation and in the development of new therapeutic strategies. In the present paper, available data on phenotypic and functional characterization of Treg cells in both peripheral blood and synovial fluid from RA patients are reviewed and their possible pathogenic role in triggering and perpetuating rheumatoid joint inflammation is discussed.

Comparison of sensitivity of Th1, Th2, and Th17 cells to Fas-mediated apoptosis

Following activation through the TCR, CD4+ T cells can differentiate into three major subsets: Th1, Th2, and Th17 cells. IL-17-secreting Th17 cells play an important role in the pathogenesis of several autoimmune diseases and in immune responses to pathogens, but little is known about the regulation of apoptosis in Th17 cells. In this study, the sensitivity of in vitro-polarized Th1, Th2, and Th17 cells to Fas-mediated apoptosis was compared directly by different methods. The order of sensitivity of T cell subsets to Fas-mediated apoptosis is: Th1 > Th17 > Th2. The greater sensitivity of Th17 cells to Fas-mediated apoptosis compared with Th2 cells correlated with their higher expression of FasL and comparable expression of the antiapoptotic molecule FLIP. The decreased sensitivity of Th17 compared with Th1 cells correlated with the higher expression of FLIP by Th17 cells. Transgenic overexpression of FLIP in T cells protected all three subsets from Fas-mediated apoptosis. These findings provide new knowledge for understanding how survival of different subsets of T cells is regulated.

Chondroitin sulfate improves synovitis in rabbits with chronic antigen-induced arthritis

OBJECTIVE

Our aim was to explore the effect of chondroitin sulfate (CS), a natural glycosaminoglycan with attributed anti-inflammatory properties, on synovitis in a rabbit model of chronic arthritis with intense systemic inflammation bolstered by endothelial lesion and atherosclerotic diet.

METHODS

Chronic arthritis was induced by intraarticular injections of ovalbumin in immunized rabbits. Systemic inflammation was boosted in these rabbits by receiving a hyperlipidemic diet after producing an endothelial lesion in the femoral arteries. A group of these rabbits were treated with CS (100mg/kg/day). At sacrifice, synovial membranes were isolated, and cyclooxygenase-2 (COX-2) and chemokine (C-C motif) ligand 2 (CCL2) mRNA, as well as protein expression were assayed by quantitative real-time polymerase chain reaction (RT-PCR) and western blot studies. Histological synovial examination was also carried out employing the histopathological synovitis score (Krenn scale).

RESULTS

CS diminished both gene expression and protein synthesis of COX-2 and CCL2, and the histopathological score of the synovial membrane, when compared to untreated rabbits. In fact, CS partially prevented the intimal layer proliferation and the inflammatory cell infiltration in the synovial membrane, which was observed in non-treated animals.

CONCLUSION

CS reduced the inflammatory response of the synovial membrane, as well as decreased the synovial histopathological lesions in our animal model. Further studies are warranted to demonstrate whether CS might be beneficial in the treatment of inflammatory arthritis.

Suppression of Autoimmune Arthritis by Small Molecule Inhibitors of the JAK/STAT Pathway

A skewed ratio of pro-inflammatory to anti-inflammatory cytokines, elevated growth factor synthesis and T- and B-lymphocyte activation are 3 hallmarks of rheumatoid arthritis (RA) pathology. Interleukin-6 (IL-6), IL-7, IL-17, IL-12/IL-23 and growth factors, granulocyte macrophage-colony stimulating factor, IL-3, and erythropoietin activate the Janus Kinase/Signal Transducers and Activators of Transcription (JAK/STAT) pathway. Evidence showed that STAT protein phosphorylation (p-STAT) by activated JAKs is permissive for p-STAT to act as transcription factors by binding to STAT-responsive gene promoter sequences. This event is critical for perpetuating RA, in part, by up-regulating pro-inflammatory cytokine gene transcription. Activation of JAK/STAT by cytokines and growth factors can induce ‘cross-talk’ with other signaling pathways by which Stress-Activated Protein/Mitogen-Activated Protein Kinase (SAP/MAPK) and Phosphatidylinositide-3-Kinase (PI3K)-mediated signaling are also activated. JAK-specific small molecule inhibitors (SMIs) were developed to test whether JAK/STAT pathway blockade would regulate autoimmune-mediated inflammation. JAK-specific SMI blockade inhibited p-STAT induced by pro-inflammatory cytokines in vitro. Systemically administered JAK-specific SMI blockade also ameliorated biomarkers of inflammation in well-validated arthritis animal models. A few JAK-specific SMIs have made their way into RA clinical trials. In fact, the JAK3-specific SMI, CP-690,500 is the first JAK/STAT SMI to be assessed for clinical efficacy in a Phase III RA trial.

Altered microRNA expression profile with miR-146a upregulation in CD4+ T cells from patients with rheumatoid arthritis

Introduction

Increasing evidence indicates that microRNAs (miRNAs) play a critical role in the pathogenesis of inflammatory diseases. The aim of the study was to investigate the expression pattern and function of miRNAs in CD4⁺ T cells from patients with rheumatoid arthritis (RA).

Methods

The expression profile of miRNAs in CD4⁺ T cells from synovial fluid (SF) and peripheral blood of 33 RA patients was determined by microarray assay and validated by qRT-PCR analysis. The correlation between altered expression of miRNAs and cytokine levels was determined by linear regression analysis. The role of miR-146a overexpression in regulating T cell apoptosis was evaluated by flow cytometry. A genome-wide gene expression analysis was further performed to identify miR-146a-regulated genes in T cells.

Results

miRNA expression profile analysis revealed that miR-146a expression was significantly upregulated while miR-363 and miR-498 were downregulated in CD4⁺ T cells of RA patients. The level of miR-146a expression was positively correlated with levels of tumor necrosis factor-alpha (TNF-α), and in vitro studies showed TNF-α upregulated miR-146a expression in T cells. Moreover, miR-146a overexpression was found to suppress Jurkat T cell apoptosis. Finally, transcriptome analysis of miR-146a overexpression in T cells identified Fas associated factor 1 (FAF1) as a miR-146a-regulated gene, which was critically involved in modulating T cell apoptosis.

Conclusions

We have detected increased miR-146a in CD4⁺ T cells of RA patients and its close correlation with TNF-α levels. Our findings that miR-146a overexpression suppresses T cell apoptosis indicate a role of miR-146a in RA pathogenesis and provide potential novel therapeutic targets.

Role for interleukin-6 in structural joint damage and systemic bone loss in rheumatoid arthritis

Interleukin-6 (IL-6) plays a key role in the local and systemic manifestations of rheumatoid arthritis (RA). IL-6 is not only a proinflammatory cytokine, but also interacts in complex ways with the cells involved in bone remodeling. In RA, IL-6 may indirectly promote osteoclastogenesis by increasing the release of RANK-L by osteoblasts and synovial cells. However, IL-6 inhibits osteoclastogenesis in vitro, via a direct mechanism. The effects of IL-6 on osteoblasts may vary with the cell differentiation stage: thus, IL-6 may promote the differentiation of pre-osteoblasts to mature osteoblasts while also diminishing the proliferation of osteoblasts at late differentiation stages. Thus, the effects of IL-6 on bone remodeling are complex and may occur in opposite directions depending on the model or experimental conditions. Nevertheless, results from studies in animal models and humans support a negative effect of IL-6 on bone. Thus, in patients with RA, blocking IL-6 may be effective both in diminishing the inflammatory manifestations and in preventing the bone complications of the disease.

Chronic arthritis aggravates vascular lesions in rabbits with atherosclerosis: a novel model of atherosclerosis associated with chronic inflammation

OBJECTIVE

To determine whether systemic inflammation induced by chronic antigen-induced arthritis (AIA) accelerates vascular lesions in rabbits with atherosclerosis.

METHODS

Two models of atherosclerosis and chronic AIA were combined. Atherosclerosis was induced by coupling a hyperlipemic diet with an endothelial lesion at the femoral arteries, while chronic AIA was induced by ovalbumin injection. Markers in sera and peripheral blood mononuclear cells (PBMCs) as well as vessels and synovial membranes from the rabbits with the double phenotype (both chronic AIA and atherosclerosis) were compared with those from rabbits with each disease alone.

RESULTS

Serum levels of interleukin-6, C-reactive protein, and prostaglandin E(2) increased in rabbits with both chronic AIA and atherosclerosis as compared with healthy animals or animals with either chronic AIA alone or atherosclerosis alone. NF-kappaB binding and CCL2 and cyclooxygenase 2 (COX-2) expression were higher in PBMCs from rabbits with both chronic AIA and atherosclerosis than in PBMCs from healthy rabbits. The intima-media thickness ratio of femoral arteries was equally increased in rabbits with atherosclerosis alone and in rabbits with both chronic AIA and atherosclerosis, but the latter group showed a higher level of macrophage infiltration. Femoral CCL2 and COX-2 expression was increased in rabbits with both chronic AIA and atherosclerosis as compared with rabbits with atherosclerosis alone. In the aortas, vascular lesions were found in 27% of rabbits with atherosclerosis alone and in 60% of rabbits with both chronic AIA and atherosclerosis. Rabbits with both chronic AIA and atherosclerosis exhibited more severe synovitis and higher synovial expression of CCL2 than did rabbits with chronic AIA alone.

CONCLUSION

The onset of chronic AIA in animals with atherosclerosis resulted in the local and systemic up-regulation of mediators of tissue inflammation and plaque instability associated with a higher incidence of aortic lesions. This model could represent a novel approach to the study of inflammation-associated atherosclerosis.

Development of proteoglycan-induced arthritis depends on T cell-supported autoantibody production, but does not involve significant influx of T cells into the joints

INTRODUCTION

Inflammatory joint destruction in rheumatoid arthritis (RA) may be triggered by autoantibodies, the production of which is supported by autoreactive T cells. Studies on RA and animal models of the disease suggest that T cells recruited in the joints can locally initiate or propagate arthritis. Herein, we investigated the role of joint-homing versus lymphoid organ-homing T cells in the development of proteoglycan-induced arthritis (PGIA), an autoimmune model of RA.

METHODS

To identify T cells migrating to the joints before and during development of autoimmune arthritis, we transferred fluorescence-labeled T cells, along with antigen-presenting cells, from BALB/c mice with PGIA to naïve syngeneic severe combined immunodeficient (SCID) mice. We then monitored the recruitment of donor T cells in the ankle joints and joint-draining lymph nodes of the recipients using in vivo two-photon microscopy and ex vivo detection methods. To limit T-cell access to the joints, we selectively depleted T cells in the blood circulation by treatment with FTY720, an inhibitor of lymphocyte egress from lymphoid organs. Reduction of T cell presence in both lymphoid organs and blood was achieved by injection of donor cells from which T cells were removed prior to transfer. T and B cells were quantitated by flow cytometry, and antigen (PG)-specific responses were assessed by cell proliferation and serum antibody assays.

RESULTS

Despite development of adoptively transferred arthritis in the recipient SCID mice, we found very few donor T cells in their joints after cell transfer. Treatment of recipient mice with FTY720 left the T-cell pool in the lymphoid organs intact, but reduced T cells in both peripheral blood and joints. However, FTY720 treatment failed to inhibit PGIA development. In contrast, arthritis was not seen in recipient mice after transfer of T cell-depleted cells from arthritic donors, and serum autoantibodies to PG were not detected in this group of mice.

CONCLUSIONS

Our results suggest that antigen-specific T cells, which home to lymphoid organs and provide help to B cells for systemic autoantibody production, play a greater role in the development and progression of autoimmune arthritis than the small population of T cells that migrate to the joints.

Inhibition of synovial hyperplasia, rheumatoid T cell activation, and experimental arthritis in mice by sulforaphane, a naturally occurring isothiocyanate

OBJECTIVE

To investigate whether sulforaphane (SFN), an isothiocyanate derived from cruciferous vegetables such as broccoli, regulates synoviocyte hyperplasia and T cell activation in rheumatoid arthritis (RA).

METHODS

Synoviocyte survival was assessed by MTT assay. The levels of Bcl-2, Bax, p53, and pAkt were determined by Western blot analysis. Cytokine concentrations in culture supernatants from mononuclear cells were analyzed by enzyme-linked immunosorbent assay. The in vivo effects of SFN were examined in mice with experimentally induced arthritis.

RESULTS

SFN induced synoviocyte apoptosis by modulating the expression of Bcl-2/Bax, p53, and pAkt. In addition, nonapoptotic doses of SFN inhibited T cell proliferation and the production of interleukin-17 (IL-17) and tumor necrosis factor alpha (TNFalpha) by RA CD4+ T cells stimulated with anti-CD3 antibody. Anti-CD3 antibody-induced increases in the expression of retinoic acid-related orphan receptor gammat and T-bet were also repressed by SFN. Moreover, the intraperitoneal administration of SFN to mice suppressed the clinical severity of arthritis induced by injection of type II collagen (CII), the anti-CII antibody levels, and the T cell responses to CII. The production of IL-17, TNFalpha, IL-6, and interferon-gamma by lymph node cells and spleen cells from these mice was markedly reduced by treatment with SFN. Anti-CII antibody-induced arthritis in mice was also alleviated by SFN injection.

CONCLUSION

SFN was found to inhibit synovial hyperplasia, activated T cell proliferation, and the production of IL-17 and TNFalpha by rheumatoid T cells in vitro. The antiarthritic and immune regulatory effects of SFN, which were confirmed in vivo, suggest that SFN may offer a possible treatment option for RA.

Expression analysis of Notch-related molecules in peripheral blood T helper cells of patients with rheumatoid arthritis

OBJECTIVE

Expression of Notch homologues in local tissue inflammation in rheumatoid arthritis (RA) and cultured synoviocytes has been reported, but the expression profile of Notch-related molecules in peripheral lymphocytes in RA remains unclear. In this study, we measured the expression of Notch receptors and downstream molecules in peripheral lymphocytes from RA patients.

METHODS

Expression of Notch receptors in peripheral lymphocytes of RA patients was assessed by both flow cytometry and real-time polymerase chain reaction (PCR). Expression of the representative Notch target gene HES-1 and the regulatory gene NUMB in purified T helper cells from RA patients was determined by real-time PCR, and expression of Notch intracellular domain (ICD) was determined by immunoblot analysis.

RESULTS

There was an increased expression of Notch 2, Notch 3, and Notch 4 in T helper cells from active RA patients, among which increased expression of Notch 3 was mainly by activated T cells. Notably, expression of Notch 3 in T cells decreased in inactive RA patients and the level was similar to that of healthy controls (HC). Notch receptors were rarely observed on B cells and no difference in expression was found between RA patients and HC. T helper cells from RA patients exhibited increased expression of the target gene HES-1 but decreased expression of the negative modulation gene NUMB of Notch signalling. There was also an increased nuclear translocation of Notch-ICD in T helper cells from active RA disease.

CONCLUSION

The present study demonstrated that T helper cells from RA patients display a significantly altered expression profile of Notch receptors and enhanced activation of Notch signalling compared with HC.

IRF4 and its regulators: evolving insights into the pathogenesis of inflammatory arthritis?

Accumulating evidence from murine and human studies supports a key role for interleukin-17 (IL-17) and IL-21 in the pathogenesis of inflammatory arthritis. The pathways and molecular mechanisms that underlie the production of IL-17 and IL-21 are being rapidly elucidated. This review focuses on interferon regulatory factor 4 (IRF4), a member of the IRF family of transcription factors, which has emerged as a crucial controller of both IL-17 and IL-21 production. We first outline the complex role of IRF4 in the function of CD4(+) T cells and then discuss recent studies from our laboratory that have revealed a surprising role for components of Rho GTPase-mediated pathways in controlling the activity of IRF4. A better understanding of these novel pathways will hopefully provide new insights into mechanisms responsible for the development of inflammatory arthritis and potentially guide the design of novel therapeutic approaches.