Regulatory T cells in rheumatoid arthritis

The Application Potential of the Regulation of Tregs Function by Irisin in the Prevention and Treatment of Immune-Related Diseases

Irisin is a muscle factor induced by exercise, generated through the proteolytic cleavage of the membrane protein fibronectin type III domain-containing protein 5 (FNDC-5). Numerous studies have shown that irisin plays a significant role in regulating glucose and lipid metabolism, inhibiting oxidative stress, reducing systemic inflammatory responses, and providing neuroprotection. Additionally, irisin can exert immunomodulatory functions by regulating regulatory T cells (Tregs). Tregs are a highly differentiated subset of mature T cells that play a key role in maintaining self-immune homeostasis and are closely related to infections, inflammation, immune-related diseases, and tumors. Irisin exerts persistent positive effects on Treg cell functions through various mechanisms, including regulating Treg cell differentiation and proliferation, improving their function, modulating the balance of immune cells, increasing the production of anti-inflammatory cytokines, and enhancing metabolic functions, thereby helping to maintain immune homeostasis and prevent immune-related diseases. As an important myokine, irisin interacts with receptors on the cell membrane, activating multiple intracellular signaling pathways to regulate cell metabolism, proliferation, and function. Although the specific receptor for irisin has not been fully identified, integrins are considered potential receptors. Irisin activates various signaling pathways, including AMPK, MAPK, and PI3K/Akt, through integrin receptors, thereby exerting multiple biological effects. These research findings provide important clues for understanding the mechanisms of irisin's action and theoretical basis for its potential applications in metabolic diseases and immunomodulation. This article reviews the relationship between irisin and Tregs, as well as the research progress of irisin in immune-related diseases such as multiple sclerosis, myasthenia gravis, acquired immune deficiency syndrome, type 1 diabetes, sepsis, and rheumatoid arthritis. Studies have revealed that irisin plays an important role in immune regulation by improving the function of Tregs, suggesting its potential application value in the treatment of immune-related diseases.

Unveiling new genetic insights in rheumatoid arthritis for drug discovery through Taxonomy3 analysis

Genetic support for a drug target has been shown to increase the probability of success in drug development, with the potential to reduce attrition in the pharmaceutical industry alongside discovering novel therapeutic targets. It is therefore important to maximise the detection of genetic associations that affect disease susceptibility. Conventional statistical methods such as genome-wide association studies (GWAS) only identify some of the genetic contribution to disease, so novel analytical approaches are required to extract additional insights. C4X Discovery has developed Taxonomy3, a unique method for analysing genetic datasets based on mathematics that is novel in drug discovery. When applied to a previously published rheumatoid arthritis GWAS dataset, Taxonomy3 identified many additional novel genetic signals associated with this autoimmune disease. Follow-up studies using tool compounds support the utility of the method in identifying novel biology and tractable drug targets with genetic support for further investigation.

multi-GPA-Tree: Statistical approach for pleiotropy informed and functional annotation tree guided prioritization of GWAS results

Genome-wide association studies (GWAS) have successfully identified over two hundred thousand genotype-trait associations. Yet some challenges remain. First, complex traits are often associated with many single nucleotide polymorphisms (SNPs), most with small or moderate effect sizes, making them difficult to detect. Second, many complex traits share a common genetic basis due to 'pleiotropy' and and though few methods consider it, leveraging pleiotropy can improve statistical power to detect genotype-trait associations with weaker effect sizes. Third, currently available statistical methods are limited in explaining the functional mechanisms through which genetic variants are associated with specific or multiple traits. We propose multi-GPA-Tree to address these challenges. The multi-GPA-Tree approach can identify risk SNPs associated with single as well as multiple traits while also identifying the combinations of functional annotations that can explain the mechanisms through which risk-associated SNPs are linked with the traits. First, we implemented simulation studies to evaluate the proposed multi-GPA-Tree method and compared its performance with existing statistical approaches. The results indicate that multi-GPA-Tree outperforms existing statistical approaches in detecting risk-associated SNPs for multiple traits. Second, we applied multi-GPA-Tree to a systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), and to a Crohn's disease (CD) and ulcertive colitis (UC) GWAS, and functional annotation data including GenoSkyline and GenoSkylinePlus. Our results demonstrate that multi-GPA-Tree can be a powerful tool that improves association mapping while facilitating understanding of the underlying genetic architecture of complex traits and potential mechanisms linking risk-associated SNPs with complex traits.

Disease-microenvironment modulation by bare- or engineered-exosome for rheumatoid arthritis treatment

BACKGROUND

Exosomes are extracellular vesicles secreted by eukaryotic cells and have been extensively studied for their surface markers and internal cargo with unique functions. A deeper understanding of exosomes has allowed their application in various research areas, particularly in diagnostics and therapy.

MAIN BODY

Exosomes have great potential as biomarkers and delivery vehicles for encapsulating therapeutic cargo. However, the limitations of bare exosomes, such as rapid phagocytic clearance and non-specific biodistribution after injection, pose significant challenges to their application as drug delivery systems. This review focuses on exosome-based drug delivery for treating rheumatoid arthritis, emphasizing pre/post-engineering approaches to overcome these challenges.

CONCLUSION

This review will serve as an essential resource for future studies to develop novel exosome-based therapeutic approaches for rheumatoid arthritis. Overall, the review highlights the potential of exosomes as a promising therapeutic approach for rheumatoid arthritis treatment.

Regulatory T-cell dysfunction and its implication for cell therapy

Regulatory T cells (Tregs) are a subtype of CD4+ T cells that can mediate immune tolerance by a multitude of immunomodulatory mechanisms. Treg-based adoptive immunotherapy is currently being tested in multiple phases I and II clinical trials in transplantation and autoimmune diseases. We have learned from the work done on conventional T cells that distinct mechanistic states can define their dysfunctions, such as exhaustion, senescence, and anergy. All three can negatively impact the therapeutic effectiveness of T-cell-based therapies. However, whether Tregs are susceptible to such dysfunctional states is not well studied, and results are sometimes found to be controversial. In addition, Treg instability and loss of FOXP3 expression is another Treg-specific dysfunction that can decreasein their suppressive potential. A better understanding of Treg biology and pathological states will be needed to compare and interpret the results of the different clinical and preclinical trials. We will review herein Tregs' mechanisms of action, describe different T-cell dysfunction subtypes and how and if they apply to Tregs (exhaustion, senescence, anergy, and instability), and finally how this knowledge should be taken into consideration when designing and interpreting Treg adoptive immunotherapy trials.

Clinical adoptive regulatory T Cell therapy: State of the art, challenges, and prospective

Rejection of solid organ transplant and graft versus host disease (GvHD) continue to be challenging in post transplantation management. The introduction of calcineurin inhibitors dramatically improved recipients' short-term prognosis. However, long-term clinical outlook remains poor, moreover, the lifelong dependency on these toxic drugs leads to chronic deterioration of graft function, in particular the renal function, infections and de-novo malignancies. These observations led investigators to identify alternative therapeutic options to promote long-term graft survival, which could be used concomitantly, but preferably, replace pharmacologic immunosuppression as standard of care. Adoptive T cell (ATC) therapy has evolved as one of the most promising approaches in regenerative medicine in the recent years. A range of cell types with disparate immunoregulatory and regenerative properties are actively being investigated as potential therapeutic agents for specific transplant rejection, autoimmunity or injury-related indications. A significant body of data from preclinical models pointed to efficacy of cellular therapies. Significantly, early clinical trial observations have confirmed safety and tolerability, and yielded promising data in support of efficacy of the cellular therapeutics. The first class of these therapeutic agents commonly referred to as advanced therapy medicinal products have been approved and are now available for clinical use. Specifically, clinical trials have supported the utility of CD4⁺CD25+FOXP3+ regulatory T cells (Tregs) to minimize unwanted or overshooting immune responses and reduce the level of pharmacological immunosuppression in transplant recipients. Tregs are recognized as the principal orchestrators of maintaining peripheral tolerance, thereby blocking excessive immune responses and prevent autoimmunity. Here, we summarize rationale for the adoptive Treg therapy, challenges in manufacturing and clinical experiences with this novel living drug and outline future perspectives of its use in transplantation.

Foxp3+ regulatory T cell therapy for tolerance in autoimmunity and solid organ transplantation

Regulatory T cells (Tregs) are critical for tolerance in humans. The exact mechanisms by which the loss of peripheral tolerance leads to the development of autoimmunity and the specific role Tregs play in allograft tolerance are not fully understood; however, this population of T cells presents a unique opportunity in the development of targeted therapeutics. In this review, we discuss the potential roles of Foxp3+ Tregs in the development of tolerance in transplantation and autoimmunity, and the available data regarding their use as a treatment modality.

Therapeutic Utility and Adverse Effects of Biologic Disease-Modifying Anti-Rheumatic Drugs in Inflammatory Arthritis

Targeting specific pathologic pro-inflammatory cytokines or related molecules leads to excellent therapeutic effects in inflammatory arthritis, including rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis. Most of these agents, known as biologic disease-modifying anti-rheumatic drugs (bDMARDs), are produced in live cell lines and are usually monoclonal antibodies. Several types of monoclonal antibodies target different pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL)-17A, IL-6, and IL-23/12. Some bDMARDs, such as rituximab and abatacept, target specific cell-surface molecules to control the inflammatory response. The therapeutic effects of these bDMARDs differ in different forms of inflammatory arthritis and are associated with different adverse events. In this article, we summarize the therapeutic utility and adverse effects of bDMARDs and suggest future research directions for developing bDMARDs.

Gain of CXCR7 function with mesenchymal stem cell therapy ameliorates experimental arthritis via enhancing tissue regeneration and immunomodulation

BACKGROUND

The major barriers to mesenchymal stem cell (MSC) therapy in rheumatoid arthritis (RA) are a low extent of tissue regeneration and insufficient immunomodulation after cell transplantation. In addition, the role of C-X-C chemokine receptor type 7 (CXCR7) and its mechanism of action in MSC-mediated osteogenic or chondrogenic differentiation and immunomodulation are unclear.

METHODS

Gain of CXCR7 function on human MSCs was carried out by lentiviral vector-mediated CXCR7 overexpression or CXCR7 agonist, TC14012. These cells were determined the role and potential mechanisms for CXCR7-regulated MSC differentiation and immunomodulation using cellular and molecular assays. The therapeutic benefits in RA were investigated in rats with collagen-induced arthritis (CIA).

RESULTS

CXCR7 was upregulated in MSCs during the induction of osteogenic or chondrogenic differentiation. Blockage of CXCR7 function inhibited osteogenic or chondrogenic differentiation of MSCs whereas gain of CXCR7 function had the opposite effects. Besides, MSCs with CXCR7 gain-of-function facilitated macrophage apoptosis and regulatory T cell differentiation in a co-culture system. Gain of CXCR7 function also promoted the production of anti-inflammatory soluble factors. A gene expression profiling assay and signaling reporter assays revealed that CXCR7 could regulate several candidate genes related to the PPAR, WNT, Hedgehog or Notch pathways, and their signaling activities, which are known to control cell differentiation and immunomodulation. Finally, MSCs with CXCR7 gain-of-function significantly reduced the articular index scores, ankle circumference, radiographic scores, histologic scores, and inflammation in rats with CIA compared with control MSCs.

CONCLUSIONS

CXCR7 promotes the osteogenic and chondrogenic differentiation of MSCs and MSC-mediated immunomodulation by regulating several signaling pathways and anti-inflammatory soluble factors. MSCs with CXCR7 gain-of-function significantly ameliorate arthritic symptoms in a CIA model.

Pathogenesis and Function of Interleukin-35 in Rheumatoid Arthritis

It is well known that RA (Rheumatoid arthritis) is an autoimmune disease characterized by multiple and symmetric arthropathy. The main pathological features of RA are synovial hyperplasia, angiogenesis, pannus formation, inflammatory cell infiltration, articular cartilage, bone destruction, and ultimately joint dysfunction, even deformity. IL-35 (Interleukin-35) is a new member of the IL-12 (Interleukin-12) family, which is an immunosuppressive and anti-inflammatory cytokine secreted mainly by Treg (T regulatory cells). There is evidence suggested that IL-35 can attenuate the progression of RA through influencing the immune and pathological process. It suggests that IL-35 played an important role in the pathogenesis of RA, and can be used as a potential target for the future treatment of RA. This review summarizes the recent advances of IL-35 in the pathological roles and the therapeutic potential roles in RA.

Anti-CCL22 increases regulatory T cells in CD4+ T cells of rheumatoid arthritis patients via STAT5 pathway

Abnormality in the number and function of CD4⁺CD25⁺FOXP3⁺ regulatory T cells (Tregs) in peripheral blood has been linked to the initiation and progression of rheumatoid arthritis (RA). Effect of chemokine CCL22 on the number of Tregs in CD4⁺ T cells and the underlying mechanism were investigated. Downregulation of peripheral Tregs were observed while upregulation of serum chemokine CCL22 in RA patients. Tregs count and the expression of FOXP3 (Tregs function-related maker) and phosphorylated-signal transducer and activator of transcription 5 (p-STAT5) in CD4⁺ T cells from RA patients were increased while C-C chemokine receptor 4 (CCR4) was decreased by anti-CCL22 antibody, however, recombinant CCL22 resulted in the opposite effects in CD4⁺ T cells from the healthy control. STAT5 inhibitor significantly reversed the effects of anti-CCL22 antibody. Similarly, sinomenine, an anti-arthritis drug, which decreased CCL22 and CCR4, showed the same trends as the above events, and was reversed by recombinant CCL22 or STAT5 inhibitor. Collectively, anti-CCL22 induced the number of Tregs via STAT5 pathway, leading to expansion of Tregs and subsequently to control of the autoimmune reaction in RA patients. Our study provides s novel strategy for RA treatment.

Plasma Markers of Inflammation Linked to Clinical Progression and Decline During Preclinical AD

Objective

To examine the prospective association between blood biomarkers of immune functioning (i.e., innate immune activation, adaptive immunity, and inflammation) and subsequent cognitive decline and clinical progression to mild cognitive impairment (MCI) in cognitively normal individuals.

Methods

The BIOCARD study is an observational cohort study of N = 191 initially cognitively healthy participants (mean age 65.2 years). Blood plasma samples were assayed for markers of chronic inflammation (TNFR1, IL-6), adaptive immunity (CD25), and innate immune activation (CD14 and CD163). Participants were followed annually for ongoing clinical assessment and cognitive testing for up to 7.3 years. Primary study outcomes were progression to MCI and cognitive change over time, as measured by a global factor score encompassing multiple cognitive domains.

Results

Higher levels of plasma TNFR1 were associated with greater risk of progression from normal cognition to MCI (HR: 3.27; 95% confidence interval, CI: 1.27, 8.40). Elevated levels of TNFR1 were also associated with steeper rate of cognitive decline on follow-up but not with baseline cognitive performance. Baseline IL-6 levels and markers of innate and adaptive immune activation showed no relationship with MCI risk or cognitive decline.

Conclusion

Inflammation, mediated by TNF signaling, may play a selective role in the early phase of AD. Accordingly, plasma TNFR1 may facilitate improved prediction of disease progression for individuals in the preclinical stage of AD.

The expression of GAS5, THRIL, and RMRP lncRNAs is increased in T cells of patients with rheumatoid arthritis

OBJECTIVE

Long non-coding RNAs (lncRNAs) comprise a large and diverse group of non-coding RNAs (ncRNAs) with important regulatory roles in various biological processes, including the immune system regulation. Rheumatoid arthritis (RA) as an autoimmune disease initiates inflammation in the synovial joints. T cells infiltrating into the synovial membrane have an important role in the pathogenesis of RA. The aim of the current investigation was to analyze the expression of four lncRNAs in the T cells from RA patients and healthy controls.

METHODS

In the current study, we investigated the expression of GAS5, RMRP, IFNϒ-AS1, and THRIL lncRNAs in circulating T cells from 20 patients with RA and 18 healthy matched controls by quantitative real-time PCR. T cell isolation was accomplished using the MAC method. We also analyzed the correlation between lncRNA expression and clinical parameters. Also, the mRNA expression levels of IL-17 and TNF-α and the association between lncRNAs and these cytokines were examined.

RESULTS

The results indicate that T cells of RA patients display increased levels of GAS5 (3.31-fold, p = 0.007), RMRP (2.43-fold, p = 0.02), and THRIL (2.14-fold, p = 0.03) lncRNAs compared with those of controls. Furthermore, a positive correlation was found between RMRP expression and disease duration in RA. Receiver operating characteristic (ROC) curve of GAS5, RMRP, and THRIL has a discriminative value in comparing RA patients and controls.

CONCLUSION

The results suggest lncRNAs may be involved in T cell dysfunction in RA. Further studies are required to see whether these lncRNAs have an effect on dysregulation of immune responses in RA disease. Key Points • 70% of non-coding sequences in the human genome are transcribed to RNA. • A growing body of evidence shows the importance of lncRNAs in innate and adaptive immune cell differentiation and functions. • Important recent works suggest a key role of immune cell lncRNAs in autoimmune processes and diseases including RA.

Regulatory T cells: the future of autoimmune disease treatment

Introduction: CD4 + T regulatory cells (Tregs) have been described as the most potent immunosuppressive cells in the human body. They have been found to control autoimmunity, and clinical attempts have been made to apply them to treat autoimmune diseases. Some specific pathways utilized by Tregs in the regulation of immune response or Tregs directly as cellular products are tested in the clinic. Areas covered: Here, we present recent advances in the research on the biology and clinical applications of Tregs in the treatment of autoimmune diseases. Expert opinion: Regulatory T cells seem to be a promising tool for the treatment of autoimmune diseases. The development of both cell-based therapies and modern pharmacotherapies which affect Tregs may strongly improve the treatment of autoimmune disorders. Growing knowledge about Treg biology together with the latest biotechnology tools may give an opportunity for personalized therapies in these conditions.

1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol ameliorates arthritic joints through reducing neutrophil infiltration mediated by IL-6/STAT3 and MIP-2 activation

The pathogenesis of rheumatoid arthritis (RA) has been implicated neutrophil extracellular traps (NETs) formation which could generate autoantigen. Neutrophil contributes to initiate and maintain the inflammatory process in the joint. In this study, we show that 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) decreases neutrophil migration by regulating the activity of STAT3, a regulator of IL-6 and MIP-2 expression. PLAG caused a decrease in IL-6 production in the RAW264.7 macrophage cell line and in rheumatoid arthritis–fibroblast-like synoviocytes via the regulation of STAT3 signaling without affecting NF-κB signaling. In a mouse model of collagen-induced arthritis (CIA), arthritic symptoms were recapitulated, with increased IL-6 level in the synovium, and PLAG treatment restored IL-6 to a level comparable to that achieved with commercial therapeutics (such as Remicade or methotrexate). Staining of joint tissue with neutrophil-specific antibody showed that PLAG significantly reduced the infiltration of neutrophils into the joint synovium of CIA mice. The inhibitory effect of PLAG on IL-6/STAT3 or MIP-2 signaling also reduced the migration of differentiated neutrophils in vitro. Therefore, PLAG inhibits the infiltration of destructive neutrophils into inflammatory sites, and can be utilized as a potent therapeutic agent for the treatment of sustained inflammation and joint destruction.

T helper 17 and T helper 1 cells are increased but regulatory T cells are decreased in subchondral bone marrow microenvironment of patients with rheumatoid arthritis

OBJECTIVES

The present study is to investigate the profiles of Th17, Th1 and Treg cells in bone marrow of patients with rheumatoid arthritis (RA).

METHODS

Flow cytometry was used to analyze the frequencies of Th17, Th1 and Treg cells in paired peripheral blood and bone marrow of 26 RA patients and 11 osteoarthritis (OA) patients, as well as 10 healthy controls. In addition, the disease activity was analyzed by the 28-joint disease activity score (DAS28).

RESULTS

The frequencies of Th17 and Th1 cells were significantly elevated in bone marrow of RA patients. Importantly, Th17 and Th1 cells were significantly elevated in bone marrow compared with the matched peripheral blood from RA patients. However, Treg cells were significantly decreased in bone marrow of RA patients compared with the matched peripheral blood of RA patients and bone marrow of osteoarthritis patients and healthy controls. Moreover, the frequencies of tumor necrosis factor-α-producing T cells were significantly elevated in bone marrow from RA patients. Additionally, Th17 and Th1 cells in bone marrow were positively correlated with DAS28, while Treg cells were negatively correlated with DAS28.

CONCLUSIONS

The present study demonstrates that Th17 and Th1 cells are markedly increased in bone marrow from RA patients. By contrast, Treg cells are significantly decreased in bone marrow from RA patients. These results suggest that local abnormality of Th17, Th1 and Treg cells in bone marrow of RA patients may contribute to bone destruction in skeletal system.

APL1, an altered peptide ligand derived from human heat-shock protein 60, increases the frequency of Tregs and its suppressive capacity against antigen responding effector CD4 + T cells from rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by a chronic relapsing-remitting joint inflammation. Perturbations in the balance between CD4 + T cells producing IL-17 and CD4 + CD25(high)FoxP3 + Tregs correlate with irreversible bone and cartilage destruction in RA. APL1 is an altered peptide ligand derived from a CD4+ T-cell epitope of human HSP60, an autoantigen expressed in the inflamed synovium, which increases the frequency of CD4 + CD25(high)FoxP3+ Tregs in peripheral blood mononuclear cells from RA patients. The aim of this study was to evaluate the suppressive capacity of Tregs induced by APL1 on proliferation of effector CD4+ T cells using co-culture experiments. Enhanced Treg-mediated suppression was observed in APL1-treated cultures compared with cells cultured only with media. Subsequent analyses using autologous cross-over experiments showed that the enhanced Treg suppression in APL1-treated cultures could reflect increased suppressive function of Tregs against APL1-responsive T cells. On the other hand, APL1-treatment had a significant effect reducing IL-17 levels produced by effector CD4+ T cells. Hence, this peptide has the ability to increase the frequency of Tregs and their suppressive properties whereas effector T cells produce less IL-17. Thus, we propose that APL1 therapy could help to ameliorate the pathogenic Th17/Treg balance in RA patients.

A study on FoxP3 and Tregs in paired samples of peripheral blood and synovium in rheumatoid arthritis

There is an increasing evidence suggesting the role of fork head boxP3 (FoxP3) in the development and the regulation of CD4⁺CD25⁺ Treg cells. T-cell regulatory mechanisms in rheumatoid arthritis patients were evaluated by the contributing factors such as pro-inflammatory cytokines, circulating immune complexes, HLA DR expression, ligand binding biomarkers, FoxP3 expression in paired samples of peripheral blood (PB) and synovial fluid (SF). These cellular responses were further correlated with the humoral immune responses such as anti-cyclic citrullinated peptides IgG (CCP), circulating immune complex-c1q IgG (CIC), immunoglobulin G (IgG) and immunoglobulin M (IgM) of the rheumatoid arthritis factor (RAF). The results suggest a definitive role of Tregs in the homeostatic control because there is an increase in FoxP3 (37%) and HLA-DR (45%) expression in the synovial fluid as compared to PB. Furthermore, humoral responses as a downstream effector mechanism are positively correlated with the pathogenesis of rheumatoid arthritis (RA). A positive relationship exists between quantitative anti-CCP production and the expression of HLA-DR. The study relates an increased and pivotal role of B cell activation in the synovial fluid thereby permitting the need to ablate the targeted B cell immune responses.

Mouse Models of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic debilitating autoimmune disorder characterized by synovitis that leads to cartilage and bone erosion by invading fibrovascular tissue. Mouse models of RA recapitulate many features of the human disease. Despite the availability of medicines that are highly effective in many patient populations, autoimmune diseases (including RA) remain an area of active biomedical research, and consequently mouse models of RA are still extensively used for mechanistic studies and validation of therapeutic targets. This review aims to integrate morphologic features with model biology and cover the key characteristics of the most commonly used induced and spontaneous mouse models of RA. Induced models emphasized in this review include collagen-induced arthritis and antibody-induced arthritis. Collagen-induced arthritis is an example of an active immunization strategy, whereas antibody- induced arthritis models, such as collagen antibody–induced arthritis and K/BxN antibody transfer arthritis, represent examples of passive immunization strategies. The coverage of spontaneous models in this review is focused on the TNFΔ ARE mouse, in which arthritis results from overexpression of TNF-α, a master proinflammatory cytokine that drives disease in many patients.

Suppression of Inflammation and Arthritis by Orally Administrated Cardiotoxin from Naja naja atra

Cardiotoxin (CTX) from Naja naja atra venom (NNAV) reportedly had analgesic effect in animal models but its role in inflammation and arthritis was unknown. In this study, we investigated the analgesic, anti-inflammatory, and antiarthritic actions of orally administered CTX-IV isolated from NNAV on rodent models of inflammation and adjuvant arthritis. CTX had significant anti-inflammatory effects in models of egg white induced nonspecific inflammation, filter paper induced rat granuloma formation, and capillary osmosis tests. CTX significantly reduced the swelling of paw induced by egg white, the inflammatory exudation, and the formation of granulomas. CTX reduced the swelling of paw, the AA clinical scores, and pathological alterations of joint. CTX significantly decreased the number of the CD4 T cells and inhibited the expression of relevant proinflammatory cytokines IL-17 and IL-6. CTX significantly inhibited the secretion of proinflammatory cytokine IL-6 and reduced the level of p-STAT3 in FLS. These results suggest that CTX inhibits inflammation and inflammatory pain and adjuvant-induced arthritis. CTX may be a novel therapeutic drug for treatment of arthritis.

B cells expressing IFN-γ suppress Treg-cell differentiation and promote autoimmune experimental arthritis

Clinical efficacy in the treatment of rheumatoid arthritis with anti-CD20 (Rituximab)-mediated B-cell depletion has garnered interest in the mechanisms by which B cells contribute to autoimmunity. We have reported that B-cell depletion in a murine model of proteoglycan-induced arthritis (PGIA) leads to an increase in Treg cells that correlate with decreased autoreactivity. Here, we demonstrate that the increase in Treg cells after B-cell depletion is due to an increase in the differentiation of naïve CD4(+) T cells into Treg cells. Since the development of PGIA is dependent on IFN-γ and B cells are reported to produce IFN-γ, we hypothesized that B-cell-specific IFN-γ plays a role in the development of PGIA. Accordingly, mice with B-cell-specific IFN-γ deficiency were as resistant to the induction of PGIA as mice that were completely IFN-γ deficient. Importantly, despite a normal frequency of IFN-γ-producing CD4(+) T cells, B-cell-specific IFN-γ-deficient mice exhibited a higher percentage of Treg cells compared with that in WT mice. These data indicate that B-cell IFN-γ production inhibits Treg-cell differentiation and exacerbates arthritis. Thus, we have established that IFN-γ, specifically derived from B cells, uniquely contributes to the pathogenesis of autoimmunity through prevention of immunoregulatory mechanisms.

[Effector T cells]

BACKGROUND

Although the present understanding of the immunopathogenesis of rheumatoid inflammation is still incomplete, there is substantial evidence that effector CD4+ T helper (Th) cells play a central role.

RESULTS

In recent years, in addition to the established Th cell subsets Th1 and Th2 cells, other subsets, such as Th9, Th17, Th22 and T follicular helper (Tfh) cells have been described. Defining the contribution of T cells in the initiation and maintenance of inflammation has been augmented by the identification of functionally distinct subsets of effector Th cells that can be classified based on their cytokine and transcription factor profiles.

CONCLUSION

Increasing knowledge of the role of these various T cell populations in chronic inflammation provides a better understanding and insights into the pathogenic mechanisms and chronification of rheumatic diseases.

Genetic polymorphisms of Foxp3 in patients with rheumatoid arthritis

OBJECTIVE

The aim of the study was to identify 2 polymorphic variants in the promoter region of the Foxp3 gene and their possible association with susceptibility to and severity of rheumatoid arthritis (RA). The association between genetic factors and pathogenesis suggests that T cells take part in the induction of RA. The CD4+CD25highFoxp3+ subset of regulatory T cells plays an essential role in preventing autoimmunity and maintaining immune homeostasis.

METHODS

Patients with RA (n = 274) and healthy individuals (n = 295) were examined for -3279 C/A and -924 A/G Foxp3 gene polymorphisms by the polymerase chain reaction-restriction fragment-length polymorphism method. Serum Foxp3 levels in patients with RA and controls were measured with ELISA.

RESULTS

Foxp3 -3279 A and -924 G alleles were associated with significantly elevated risk of RA in the population tested (p = 0.003 and p = 0.004, respectively) compared to the wild-type alleles. Overall, -3279 C/A and -924 A/G Foxp3 gene polymorphisms were in indistinct linkage disequilibrium with D' = 0.481 and r(2) = 0.225. From 4 possible haplotypes, frequencies of 2 (AG and CA) showed significant differences between both examined groups (respectively, p < 0.001 and p = 0.007). After appropriate adjustment of Bonferroni correction for multiple testing, the genotype-phenotype analysis showed no significant correlation of the Foxp3 -3279 C/A and -924 A/G polymorphisms with the disease activity, joint damage, laboratory variables, and extraarticular manifestation in patients with RA. Serum Foxp3 level was significantly higher in patients than in controls (p < 0.0001).

CONCLUSION

Current findings indicated that the Foxp3 genetic polymorphism and the Foxp3 protein level may be associated with susceptibility to RA in the Polish population.

Defective CD8+CD28+ regulatory T cell suppressor function in rheumatoid arthritis is restored by tumour necrosis factor inhibitor therapy

Balanced immunoregulatory networks are essential for maintenance of systemic tolerance. Disturbances in the homeostatic equilibrium between inflammatory mediators, immune regulators and immune effector cells are implicated directly in the pathogenesis of autoimmune diseases, including rheumatoid arthritis (RA). In this study we characterize the peripheral blood CD8(+) CD28(-) regulatory T cells (Treg) contribution to the immunoregulatory network in health and in RA. In health, CD8(+) CD28(-) Treg are suppressive but, unlike CD4(+) Treg , they function predominantly through the action of soluble mediators such as interleukin (IL)-10 and transforming growth factor (TGF)-β. Neutralization of TGF-β consistently reduced CD8(+) CD28(-) Treg suppressor function in vitro. RA, CD8(+) CD28(-) Treg are increased numerically, but have reduced expression of inducible co-stimulator (ICOS) and programmed death 1 (PD-1) compared to healthy or disease controls. They produce more IL-10 but autologous T cells express less IL-10R. This expression was found to be restored following in-vitro addition of a tumour necrosis factor inhibitor (TNFi). Deficiencies in both the CD8(+) CD28(-) Treg population and reduced sensitivity of the T responder cells impact upon their regulatory function in RA. TNFi therapy partially restores CD8(+) CD28(-) Treg ability in vivo and in vitro, despite the defects in expression of functionally relevant molecules by RA CD8(+) CD28(-) Treg compared to healthy controls. This study places CD8(+) CD28(-) Treg cells in the scheme of immune regulation alongside CD4(+) Treg cells, and highlights the importance of understanding impaired responsiveness to regulation that is common to these suppressor subsets and their restored function in response to TNFi therapy.

Tofacitinib for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects approximately 1% of the worldwide population. It primarily targets the synovial membrane of joints, leading to a synovial proliferation, joint cartilage lesion and erosions in the adjacent bone tissue. The disease is usually progressive and if the inflammatory process is not adequately suppressed, joint deformity takes place, leading to a significant functional disability and work incapacity. Over the last decade, biological therapy was established as a major step towards disease control in those patients who experienced failure after treatment with disease-modifying antirheumatic drugs. Despite the growing number of biological agents with different immunological targets, a significant number of patients do not receive appropriate disease control, or have the use of these agents limited because of adverse events. As such, the search for new molecules with a higher efficacy and better safety profile is ongoing. This article focuses on a new drug, tofacitinib, which is a synthetic disease-modifying antirheumatic drug for treatment of RA. Preclinical studies in arthritis and transplantation animal models are reviewed as a background for the possible use of tofacitinib treatment in humans. Four Phase II (one A and three B dose-ranging) trials lasting from 6 to 24 weeks in RA patients showed significant American College of Rheumatology 20 improvements as early as week 2 and sustained at week 24 in two studies. Tofacitinib Phase III studies in RA are included in a clinical program called 'ORAL Trials'. Long-term follow-up from ongoing studies will contribute to a more accurate tofacitinib efficacy and safety profile. Trials in other illness such as psoriasis, psoriatic arthritis, renal transplant rejection prevention, inflammatory bowel diseases and dry eye are underway.

CD4+CD25+ regulatory T cell depletion modulates anxiety and depression-like behaviors in mice

Stress has been shown to suppress immune function and increase susceptibility to inflammatory disease and psychiatric disease. CD4(+)CD25(+) regulatory T (Treg) cells are prominent in immune regulation. This study was conducted to determine if anti-CD25 antibody (Ab) mediated depletion of Treg cells in mice susceptibility to stress-induced development of depression-like behaviors, as well as immunological and neurochemical activity. To accomplish this, an elevated plus-maze test (EPM), tail suspension test (TST), and forced swim test (FST) were used to examine depression-like behaviors upon chronic immobilization stress. Immune imbalance status was observed based on analysis of serum cytokines using a mouse cytometric bead array in conjunction with flow cytometry and changes in the levels of serotonin (5-HT) and dopamine (DA) in the brain were measured by high performance liquid chromatography (HPLC). The time spent in the open arms of the EPM decreased significantly and the immobility time in the FST increased significantly in the anti-CD25 Ab-treated group when compared with the non stressed wild-type group. In addition, interlukin-6 (IL-6), tumor necrosis factor-á (TNF-á), interlukin-2 (IL-2), interferon-gamma (IFN-γ), interlukin-4 (IL-4) and interlukin-17A (IL-17A) concentrations were significantly upregulated in the stressed anti-CD25 Ab-treated group when compared with the non stressed wild-type group. Furthermore, the non stressed anti-CD25 Ab-treated group displayed decreased 5-HT levels within the hippocampus when compared with the non stressed wild-type group. These results suggest that CD4(+)CD25(+) Treg cell depletion modulated alterations in depressive behavior, cytokine and monoaminergic activity. Therefore, controlling CD4(+)CD25(+) Treg cell function during stress may be a potent therapeutic strategy for the treatment of depression-like symptoms.

T cells stimulated with an analog peptide of type II collagen require the Fc receptor γ-chain to secrete interleukin-4 and suppress autoimmune arthritis in mice

OBJECTIVE

To explore the characteristics of the T cell population that responds to an analog peptide (A9) of type II collagen and regulates autoimmunity, using the collagen-induced arthritis (CIA) model.

METHODS

Analog peptide A9 is a 26-amino acid peptide analogous to the sequence of a segment of type II collagen (CII245-270) but with substitutions at amino acid positions 260 (alanine for isoleucine), 261 (hydroxyproline for alanine), and 263 (asparagine for phenylalanine). We previously showed that A9 profoundly suppressed CIA and immune responses to type II collagen. In order to determine the mechanism of suppression, we used transgenic mice whose T cells express a type II collagen-specific receptor (T cell receptor) and performed passive cell transfer experiments.

RESULTS

The results demonstrated that suppression of CIA by A9 is dependent on T cells. Using multiparameter flow cytometry, we determined that the cells responsible for suppression were CD4+ and expressed high levels of Fcε receptor Iγ chain (FcRγ). To establish the significance of this finding, we obtained mice genetically deficient in FcRγ in order to perform passive transfer experiments. The resulting FcRγ-/- CD4+ T cells, when primed by culture with A9, could not transfer the suppression of arthritis or secrete cytokines in response to A9.

CONCLUSION

Taken together, the results of this study suggest that the suppression of arthritis and the Th2 cytokine profile elicited by A9 is dependent on the presence of FcRγ in T cells. These findings are novel and may have therapeutic potential for patients with autoimmune arthritis.

Role of T cells in type 2 diabetic nephropathy

Type 2 diabetic nephropathy (DN) is the most common cause of end-stage renal disease and is increasingly considered as an inflammatory disease characterized by leukocyte infiltration at every stage of renal involvement. Inflammation and activation of the immune system are closely involved in the pathogenesis of diabetes and its microvascular complications. Macrophage has been well recognized to play an important role in type 2 DN, leukocyte infiltration, and participated in process of DN, as was proposed recently. Th1, Th2, Th17, T reg, and cytotoxic T cells are involved in the development and progression of DN. The purpose of this review is to assemble current information concerning the role of T cells in the development and progression of type 2 DN. Specific emphasis is placed on the potential interaction and contribution of the T cells to renal damage. The therapeutic strategies involving T cells in the treatment of type 2 DN are also reviewed. Improving knowledge of the recognition of T cells as significant pathogenic mediators in DN reinforces the possibility of new potential therapeutic targets translated into future clinical treatments.

CD4+FoxP3+ regulatory T cells from Gαi2-/- mice are functionally active in vitro, but do not prevent colitis

Background

Mice deficient in the inhibitory G protein subunit Gαi2 spontaneously develop a T helper 1 dominated colitis. We examined whether a defect in CD4⁺FoxP3⁺ regulatory T cells (Treg) underpins the pathogenesis of colitis in the Gαi2^−/− (Gαi2-deficient) colitis model.

Methodology/Principal Findings

Using flow cytometry, we found that thymus and colonic lamina propria, but not spleen and mesenteric lymph nodes, of colitic Gαi2^−/− mice contained increased frequencies of Treg, whereas FoxP3 expression intensity was similar in Gαi2^−/− compared to Gαi2^+/− or Gαi2^+/+ wild type (WT) mice. The frequency of CD4⁺FoxP3⁺ T cells expressing CD103 was significantly increased in Gαi2^−/− compared to WT mice. Treg in colons from WT mice clustered in the T cell areas of colonic lymphoid patches (CLP), with relatively few Treg in the lamina propria, as demonstrated by immunohistochemistry. In Gαi2^−/− mice, CLP were not observed but lamina propria Treg were increased in number and frequency within the CD4⁺ infiltrate, compared to WT mice. Using an in vitro co-culture system and flow cytometric analysis of cell division we could demonstrate that the in vitro suppressive function of WT and Gαi2^−/− CD4⁺FoxP3⁺ regulatory T cells (WT-Treg and KO-Treg) was indistinguishable, but that T effector cells (CD4⁺25⁻ T cells) from Gαi2^−/− mice were less readily suppressed than WT effectors (WT-Teff) by Treg from either source. However, neither WT nor Gαi2^−/− Treg was able to suppress colitis induced by adoptive transfer of Gαi2^−/− effector T cells (KO-Teff) to RAG2^−/− recipients. The enhanced inflammatory activity of Gαi2^−/− effectors was accompanied by increased expression of an effector/memory T cell phenotype and increased cytokine secretion, especially IL-4, IL-6 and IFN-γ.

Conclusions

There is an increased frequency of Gαi2^−/− Treg in the colon, and they demonstrate no endogenous functional defect. However, Gαi2^−/− T effector cells are dramatically less susceptible to suppression in vitro, and in vivo, despite increased effective numbers of Treg, they cannot prevent disease.

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.

Quantification and phenotype of regulatory T cells in rheumatoid arthritis according to disease activity score-28

Here we studied and characterized different peripheral blood (PB) regulatory T cell (Treg) subsets in rheumatoid arthritis (RA) patients and tested the hypothesis that changes in these cells can be linked to the degree of inflammation and relapsing/remission periods. PB cells were examined from RA subjects (n = 60) with different disease activity score-28 (DAS28) and from healthy controls (n = 40). Frequencies of Treg subsets expressing characteristic membrane antigens, FoxP3 or intracellular cytokines were quantified by flow cytometry. We observed a decrease in the percentages of CD4(+)CD25(high), CD4(+)CD25(int), CD4(+)CD25(int/high)FoxP3(+), CD4(+)CD38(+), CD4(+)CD62L(+), CD8(+)CD25(high)CD45RA(+) and CD8(+)CD25(int)CD45RA(+) T cells in PB of RA patients compared to healthy controls. In addition, we found increased percentages of cells expressing membrane/intracellular regulatory antigens such as OX40 (CD134), CD45RB(low) or CTLA-4 (CD152), and a higher proportion of other T cell subsets including CD4(+)CTLA-4(+), CD4(+)IL10(+), CD4(+)CD25(int)IL10(+), CD4(+)CD25(int) TGFbeta(+), CD4(+)CD25(low) TGFbeta(+) and CD8(+)CD28(- ). We show that most of these changes parallel the intensity of inflammation, with lowest or highest values in patients with moderately/very active disease compared to healthy controls and at times to patients with inactive RA. The balance between these cell subsets and their antigen expression would determine the inflammation levels and could thus be linked to the relapsing/remission periods of the disease.

Identifying genetic loci and spleen gene coexpression networks underlying immunophenotypes in BXD recombinant inbred mice

The immune system plays a pivotal role in the susceptibility to and progression of a variety of diseases. Due to a strong genetic basis, heritable differences in immune function may contribute to differential disease susceptibility between individuals. Genetic reference populations, such as the BXD (C57BL/6J × DBA/2J) panel of recombinant inbred (RI) mouse strains, provide unique models through which to integrate baseline phenotypes in healthy individuals with heritable risk for disease because of the ability to combine data collected from these populations across both multiple studies and time. We performed basic immunophenotyping (e.g., percentage of circulating B and T lymphocytes and CD4(+) and CD8(+) T cell subpopulations) in peripheral blood of healthy mice from 41 BXD RI strains to define the immunophenotypic variation in this strain panel and to characterize the genetic architecture that underlies these traits. Significant QTL models that explained the majority (50-77%) of phenotypic variance were derived for each trait and for the T:B cell and CD4(+):CD8(+) ratios. Combining QTL mapping with spleen gene expression data uncovered two quantitative trait transcripts, Ptprk and Acp1, as candidates for heritable differences in the relative abundance of helper and cytotoxic T cells. These data will be valuable in extracting genetic correlates of the immune system in the BXD panel. In addition, they will be a useful resource for prospective, phenotype-driven model selection to test hypotheses about differential disease or environmental susceptibility between individuals with baseline differences in the composition of the immune system.

Natural killer cell degeneration exacerbates experimental arthritis in mice via enhanced interleukin-17 production

OBJECTIVE

An altered phenotype and dysfunction of natural killer (NK) cells have been observed in patients with rheumatoid arthritis. The aim of this study was to determine whether dysregulated NK cells contribute to the pathogenesis of experimental arthritis.

METHODS

For initiation of collagen-induced arthritis (CIA), DBA/1J mice were immunized with type II collagen in Freund's adjuvant. Control mice were immunized with adjuvant alone. NK cells from the blood, spleens, and bone marrow of immunized mice were analyzed by flow cytometry. Levels of interleukin-17 (IL-17) secretion and autoantibody production were measured by enzyme-linked immunosorbent assays. Immunized mice in which NK cells were depleted by anti-asialo G(M1) antibody treatment were assessed for the development of CIA. Moreover, sorting-purified NK cells from both mice with CIA and control mice were analyzed for cytokine gene expression.

RESULTS

We observed markedly reduced frequencies of NK cells in the blood and spleens of mice with CIA compared with the frequencies in adjuvant-treated control mice. Upon NK cell depletion, immunized mice displayed an early onset of arthritis with more severe clinical symptoms, which correlated with increased plasma cell generation and autoantibody production. Moreover, a substantially increased number of IL-17-secreting cells in synovial tissue and more pronounced joint damage were observed. Freshly isolated NK cells from mice with CIA showed markedly reduced expression of interferon-gamma (IFNgamma). Furthermore, coculture of normal NK cells and CD4+ T cells revealed that NK cells strongly suppressed production of Th17 cells via their IFNgamma production.

CONCLUSION

These results suggest that NK cells play a protective role in the development of experimental arthritis, an effect that is possibly mediated by suppressing Th17 cell generation via IFNgamma production.

TNF-alpha: an activator of CD4+FoxP3+TNFR2+ regulatory T cells

TNF-alpha (TNF) is a pleiotropic cytokine which can have proinflammatory or immunosuppressive effects, depending on the context, duration of exposure and disease state. The basis for the opposing actions of TNF remains elusive. The growing appreciation of CD4+FoxP3+ regulatory T cells (Tregs), which comprise approximately 10% of peripheral CD4 cells, as pivotal regulators of immune responses has provided a new framework to define the cellular and molecular basis underlying the contrasting action of TNF. TNF by itself can overcome the profound anergic state of T cell receptor-stimulated Tregs. Furthermore, in concert with IL-2, TNF selectively activates Tregs, resulting in proliferation, upregulation of FoxP3 expression and increases in their suppressive activity. Both human and mouse Tregs predominantly express TNFR2, making it possible for TNF to enhance Treg activity, which helps limit the collateral damage caused by excessive immune responses and eventually terminates immune response. TNFR2-expressing CD4+FoxP3+ Tregs comprise approximately 40% of peripheral Tregs in normal mice and present the maximally suppressive subset of Tregs. In this review, studies describing the action of TNF on Treg function will be discussed. The role of Tregs in the autoimmune disorders and cancer as well as the effect of anti-TNF therapy on Tregs, especially in rheumatoid arthritis, will also be considered.

A dual action of rheumatoid arthritis synovial fibroblast IL-15 expression on the equilibrium between CD4+CD25+ regulatory T cells and CD4+CD25- responder T cells

We previously described that fibroblast-like cells from the synovium of rheumatoid arthritis patients (RASFib) constitutively express intracellular and surface IL-15, which induces activation of cocultured T cells. Our objective was to study the effect of RASFib IL-15 expression on the function of human CD4(+)CD25(+) regulatory T cells (Treg). RASFib, through their constitutive IL-15 expression, were able to induce the proliferation of human Tregs stimulated through their TCR, and at the same time potentiated their suppressive action on the cytokine secretion of CD4(+)CD25(-) responder T cells (Tresp). In parallel, constitutive RASFib IL-15 expression mediated an up-regulated response of Tresp. Subsequently, total CD4(+) T cells, containing natural proportions of Treg and Tresp, secreted an increased amount of pathogenic cytokines when cocultured with RASFib despite the presence of proliferating Treg with superior regulatory potency. In summary, RASFib IL-15 exerts a dual action on the equilibrium between Treg and Tresp by potentiating the suppressive effect of Treg while augmenting the proinflammatory action of Tresp; the result is a shift of the Treg/Tresp balance toward a proinflammatory state. This alteration of the Treg/Tresp equilibrium is not observed in the presence of osteoarthritis synovial fibroblasts or dermal fibroblasts, which do not constitutively express surface IL-15. Additionally, Treg with superior suppressive potency were present in the peripheral blood and the synovial fluid of RA patients, but this enhanced immunoregulatory activity was not able to overcome the increased secretion of pathogenic cytokines by RA-Tresp, indicating that rheumatoid arthritis patients demonstrate an altered Treg/Tresp equilibrium in vivo.

The numbers of Foxp3 + Treg cells are positively correlated with higher grade of infiltration at the salivary glands in primary Sjogren's syndrome

This study was designed to investigate whether Foxp3( +) regulatory T (Treg) cells play a role in the histopathologic changes of primary Sjögren's Syndrome (pSS) and to evaluate other factors possibly associated with Foxp3(+) Treg cells in pSS patients. The number of FoxP3-expressing T cells in peripheral blood (PB) of 39 patients with pSS, 40 patients with rheumatoid arthritis (RA), and 28 healthy controls was measured by flow-cytometer analysis. FoxP3-expressing CD4(+)CD25(+) Treg cells were analyzed in minor salivary gland (SG) tissues of 39 pSS patients. Histopathologic changes were examined by light microscopy according to Chisholm's classification. Immunohistochemistry and immunofluorescence were performed to assess the Foxp3(+) Treg in SG biopsy specim-ens. The numbers of CD4(+) T cells and FoxP3-expressing CD4(+) T cells in PB were similar in all groups. Expression of CD25 on CD4(+) T cells in PB of patients with pSS and RA was significantly higher than in healthy controls, especially for RA patients. Immunohistochemistry and immunofluorescence showed that FoxP3(+) Treg were enriched in the SGs of pSS patients, with a positive correlation between the increase in FoxP3(+) Treg in SG and the Chisholm score in pSS (p < 0.001, r = +0.605). The increase of FoxP3( +) Treg cells in the SGs of pSS patients, which is correlated with gland infiltration, suggests that natural regulatory T cells play an important role in the pathogenesis of pSS. Further studies are required to explore the mechanisms that mediate the relationship between Treg and the pathogenesis of pSS.

T cell receptor signaling induced by an analog peptide of type II collagen requires activation of Syk

We have previously described an analog peptide of type II collagen (CII) that can suppress collagen-induced arthritis (CIA). This analog peptide represents CII(245-270), the immunodominant epitope of CII, but with substitutions at 260, 261, and 263 - CII(245-270) (A(260), B(261), and N(263)) (A9). To elucidate the mechanisms responsible for suppression, we used mice transgenic for a collagen-specific T cell receptor (TCR). When we found that APCs pulsed with A9 failed to induce T cell phosphorylation of TCR-zeta and ZAP-70, we explored alternative signaling pathways. We determined that A9 instead induced phosphorylation of spleen tyrosine kinase (Syk). The importance of Syk was confirmed by the use of chemical Syk inhibitors, which blocked both cytokine secretion and activation of GATA-3 mediated by peptide A9. In summary, T cells use an alternative pathway in response to A9 that involves Syk. This novel T cell pathway may represent an important means for altering T cell phenotypes.

Antigen-specific tolerogenic and immunomodulatory strategies for the treatment of autoimmune arthritis

OBJECTIVES

To review various antigen-specific tolerogenic and immunomodulatory approaches for arthritis in animal models and patients in regard to their efficacy, mechanisms of action, and limitations.

METHODS

We reviewed the published literature in Medline (PubMed) on the induction of antigen-specific tolerance and its effect on autoimmune arthritis, as well as the recent work on B-cell-mediated tolerance from our laboratory. The prominent key words used in different combinations included arthritis, autoimmunity, immunotherapy, innate immunity, tolerance, treatment, and rheumatoid arthritis (RA). Although this search spanned the years 1975 to 2007, the majority of the short-listed articles belonged to the period 1990 to 2007. The relevant primary as well as cross-referenced articles were then collected from links within PubMed and reviewed.

RESULTS

Antigen-specific tolerance has been successful in the prevention and/or treatment of arthritis in animal models. The administration of soluble native antigen or an altered peptide ligand intravenously, orally, or nasally, and the delivery of the DNA encoding a particular antigen by gene therapy have been the mainstay of immunomodulation. Recently, the methods for in vitro expansion of CD4+CD25+ regulatory T-cells have been optimized. Furthermore, interleukin-17 has emerged as a promising new therapeutic target in arthritis. However, in RA patients, non-antigen-specific therapeutic approaches have been much more successful than antigen-specific tolerogenic regimens.

CONCLUSION

An antigen-specific treatment against autoimmune arthritis is still elusive. However, insights into newly emerging mechanisms of disease pathogenesis provide hope for the development of effective and safe immunotherapeutic strategies in the near future.

An early sympathetic nervous system influence exacerbates collagen-induced arthritis via CD4+CD25+ cells

OBJECTIVE

Activation of the sympathetic nervous system (SNS) ameliorates collagen-induced arthritis (CIA) in the late phase of the disease but aggravates it in the presymptomatic phase. The aim of the present study was to determine whether CD4+CD25+ T cells are influenced by the SNS of mice and play a disease-modifying role in the early symptomatic phase of the disease.

METHODS

We tested the effects of the SNS on arthritis by transferring CD4+CD25+ T cells from sympathectomized mice immunized with type II collagen and from immunized, SNS-intact animals (controls). We further characterized transferred cells by studying forkhead box P3 (FoxP3) expression, cell proliferation, and cytokine secretion.

RESULTS

Using anti-dopamine-beta-hydroxylase antibodies for systemic sympathectomy, we noticed a time-dependent disease amelioration (strongest when sympathectomy was performed 7 days before immunization, with no effect 30 days after immunization). When CD4+CD25+ T cells from immunized and sympathectomized animals were transferred into mice with CIA (on day 32), disease severity was reduced compared with that in controls. However, the number of CD4+CD25+FoxP3+ cells and the FoxP3 expression level in CD4+CD25+ cells were not changed by sympathectomy. In a mixed assay of donor CD4+CD25- and CD4+CD25+ cells, proliferation was reduced when cells from sympathectomized animals were studied. In the same assay, secretion of tumor necrosis factor, interleukin-17 (IL-17), IL-10, and IL-4 (not interferon-gamma) was markedly reduced when cells were taken from sympathectomized animals. Culture of CD4+CD25+ cells with norepinephrine (10(-5)M) for 24 hours before transfer worsened the arthritis.

CONCLUSION

The SNS increases disease severity in the early phase of symptomatic CIA by stimulating several proinflammatory aspects of CD4+CD25+ T cells.

Relationship between impaired apoptosis of lymphocytes and distribution of dendritic cells in peripheral blood and synovial fluid of children with juvenile idiopathic arthritis

Introduction:

The pathogenesis of juvenile idiopathic arthritis (JIA) is not fully understood. Recently the present authors described disturbed apoptosis of JIA lymphocytes in both peripheral blood (PB) and synovial fluid (SF) as well as an abnormal distribution of blood dendritic cells (BDCs) between the PB and SF in this disease. Possible relationships between these events during the development of JIA process are assessed here.

Materials and Methods:

Lymphocyte apoptosis and BDC counts were assessed in the PB and SF of untreated JIA children. Lymphocyte apoptosis was analyzed by the Annexin-V/propydium iodide assay. Total DC (TDC) number was based on the sum of three BDC subpopulations determined using a panel of monoclonal antibodies against BDC antigens (BDCA): myeloid type 1 (mDC1, BDCA-1⁺/HLA-DR⁺/CD19^-), myeloid type 2 (mDC2, BDCA-3⁺/HLA-DR⁺/CD14^-), and plasmacytoid (pDC, BDCA-2⁺/HLA-DR⁺/CD123⁺). Cells were enumerated by the flow cytometric “single-platform” method. The concentration of tumor necrosis factor (TNF)-α and the distribution of particular lymphocyte subtypes in both PB and SF were also investigated.

Results:

There was significant positive correlation between apoptosis of PB lymphocytes and SF TDC count (p=0.002) as well as SF TNF-α concentration (p=0.007). SF TNF-α levels also correlated with SF TDC count (p=0.003). Moreover, JIA SF was distinctly enriched with CD4+ and CD8+ T lymphocytes and included CD4⁺/CD25^high cells as well. There was significant positive correlation between the number of CD4⁺/CD25^high cells and SF JIA BDC count (p=0.015).

Conclusions:

These data suggest a possible link between impaired apoptosis of PB/SF lymphocytes and increased recruitment of PB BDCs to SF and other elements of the immune system in JIA, including regulatory CD4+/CD25high cells.

Accumulation of FoxP3-expressing CD4+CD25+ T cells with distinct chemokine receptors in synovial fluid of patients with active rheumatoid arthritis

OBJECTIVE

To explore the presence and characteristics of FoxP3-expressing CD4+CD25+ regulatory T cells in synovial fluid (SF) of patients with active rheumatoid arthritis (RA).

METHODS

The frequency and chemokine receptors expression profile of FoxP3-expressing CD4+CD25+ regulatory T cells in SF and peripheral blood (PB) from RA patients and PB from healthy controls were investigated by flow cytometry using three- or four-colour intracellular staining.

RESULTS

The frequency of CD4+CD25+ FoxP3+ T cells was increased significantly in SF compared with paired PB from RA patients and PB from healthy controls (p<0.05). However, the frequency in PB from RA patients was significantly lower than in PB from healthy controls (p<0.05). Notably, CD4+CD25+FoxP3+ T cells in SF expressed increased levels of inflammation-related trafficking chemokine receptors, such as CCR4, CCR5, and CXCR4.

CONCLUSION

There is an accumulation of FoxP3-expressing regulatory T cells in RA SF, and such recruitment may be dependent on the distinct chemokine receptors expressed on regulatory T cells.