Immune effects of therapy with Adalimumab in patients with rheumatoid arthritis

Augmenting regulatory T cells: new therapeutic strategy for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune condition marked by inflammation of the joints, degradation of the articular cartilage, and bone resorption. Recent studies found the absolute and relative decreases in circulating regulatory T cells (Tregs) in RA patients. Tregs are a unique type of cells exhibiting immunosuppressive functions, known for expressing the Foxp3 gene. They are instrumental in maintaining immunological tolerance and preventing autoimmunity. Increasing the absolute number and/or enhancing the function of Tregs are effective strategies for treating RA. This article reviews the studies on the mechanisms and targeted therapies related to Tregs in RA, with a view to provide better ideas for the treatment of RA.

The Role of Adaptive Immunity in Diabetic Retinopathy

Diabetic retinopathy (DR) is currently one of the common causes of vision loss in working-age adults. It is clinically diagnosed and classified according to the vascular changes in the fundus. However, the activation of immune cells occurs before these vascular changes become detectable. These, together with molecular studies and the positive clinical outcomes of anti-inflammatory treatment, highlight the pivotal involvement of the immune system. The role of innate immunity in DR pathophysiology has been studied in depth, but the contribution of adaptive immunity remains largely elusive. This review aims to summarize our current understanding of the activation mechanism of adaptive immunity in DR microenvironments and to discuss the relationship between adaptive immunity and local vascular units or innate immunity, which opens new avenues for clinical applications in DR treatment.

Recent Progress on the Roles of Regulatory T Cells in IgG4-Related Disease

IgG4-related disease (RD) is a proposed concept of systemic inflammatory condition from Japanese researchers. Patients with IgG4-RD manifest several immunological and histological characterizations in the organs involved, including elevated levels of serum IgG4 and lympho-plasmacytic infiltration, storiform fibrosis, IgG4-positive plasma cells infiltration, and obstructive phlebitis. Nevertheless, the pathogenesis of IgG4-RD still remains unclear. It has been made clear that several immune cells with regulatory function play a vital part in several diseases. In particular, abnormalities in the function and proportion of regulatory T cells (Tregs) are implicated in several diseases, and their part in IgG4-RD has been investigated. This review offers an overview of the research in IgG4-RD related to Tregs. Herein, the basic information of Tregs, knowledge gained from animal models involving Tregs, and the role of IgG4-RD has been provided. We also included the immunological mechanisms of IgG4-RD based on the data accumulated so far in our hypothesis.

Application and prospect of targeting innate immune sensors in the treatment of autoimmune diseases

Dysregulation of auto-reactive T cells and autoantibody-producing B cells and excessive inflammation are responsible for the occurrence and development of autoimmune diseases. The suppression of autoreactive T cell activation and autoantibody production, as well as inhibition of inflammatory cytokine production have been utilized to ameliorate autoimmune disease symptoms. However, the existing treatment strategies are not sufficient to cure autoimmune diseases since patients can quickly suffer a relapse following the end of treatments. Pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), Nod-like receptors (NLRs), RIG-I like receptors (RLRs), C-type lectin receptors (CLRs) and various nucleic acid sensors, are expressed in both innate and adaptive immune cells and are involved in the development of autoimmune diseases. Here, we have summarized advances of PRRs signaling pathways, association between PRRs and autoimmune diseases, application of inhibitors targeting PRRs and the corresponding signaling molecules relevant to strategies targeting autoimmune diseases. This review emphasizes the roles of different PRRs in activating both innate and adaptive immunity, which can coordinate to trigger autoimmune responses. The review may also prompt the formulation of novel ideas for developing therapeutic strategies against autoimmune diseases by targeting PRRs-related signals.

Lymphopenia and intratumoral lymphocytic balance in the era of cancer immuno-radiotherapy

INTRODUCTION

The immune response has been recognized as a major tumor-eradication component of radiotherapy.

OBJECTIVE

This review studies, under a clinical perspective, two contrasting effects of radiotherapy, namely immunosuppression and radiovaccination.

MATERIALS AND METHODS

We critically reviewed the available clinical and experimental experience on radiotherapy-induced lymphopenia.

RESULTS

Radiation-induced tumor damage promotes radio-vaccination, enhances cytotoxic immune responses, and potentiates immunotherapy. Nevertheless, radiotherapy induces systemic and intratumoral lymphopenia. The above effects are directly related to radiotherapy fractionation and field size/location, and tumor characteristics.

DISCUSSION

Hypofractionated stereotactic and accelerated irradiation better promotes radio-vaccination and produces less severe lymphopenia. Adopting cytoprotective policies and combining lympho-stimulatory agents or agents blocking regulatory lymphocyte activity are awaited to unmask the radio-vaccination effect, enhancing the efficacy immuno-radiotherapy.

CONCLUSION

Radiation-induced lymphopenia and immunosuppression are important issues that should be considered in the design of immuno-radiotherapy clinical trials.

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.

Analysis of Sodium Chloride Intake and Treg/Th17 Lymphocytes in Healthy Individuals and Patients with Rheumatoid Arthritis or Systemic Lupus Erythematosus

We assessed different immune parameters in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) with low (LSI) and high (HSI) sodium intake. Thirty-eight patients with RA, thirty-seven with SLE, and twenty-eight healthy subjects were studied and classified as LSI or HSI. Levels and suppressive function of CD4+CD25+Foxp3+ and CD4+CD69+Foxp3- Treg cells were determined by flow cytometry in blood samples. Levels and in vitro differentiation of Th17 cells were also assessed. Similar levels of CD4+CD25+Foxp3+ and CD4+CD69+Foxp3- Treg cells were observed in LSI and HSI patients or controls. However, a positive correlation was detected between sodium intake and levels of CD4+CD25+Foxp3+ Treg cells in SLE and a negative association between CD4+CD69+Foxp3- Treg cells and sodium intake in RA. No other significant associations were detected, including disease activity and sodium intake. Moreover, the suppressor activity of CD4+CD25+Foxp3+ and CD4+CD69+Foxp3- Treg cells was similar in LSI and HSI patients or controls. The levels and in vitro differentiation of Th17 cells were also similar in LSI and HSI individuals. Our results suggest that, in the population studied (Mexican mestizo), the level of sodium intake is not apparently associated with different relevant immune parameters in healthy subjects or patients with SLE or RA.

Changes in T cell effector functions over an 8-year period with TNF antagonists in patients with chronic inflammatory rheumatic diseases

The aim of the study was to clarify the effect of long-term anti-TNF therapy on T cell function in patients with rheumatologic immune-mediated inflammatory diseases (IMID). The production of IFNγ by T cells was evaluated at baseline and after 1, 2, 4, and 8 years of anti-TNF agents by means of a QuantiFERON-TB Gold In-Tube assay. The T cell proliferation and surface co-expression of CD25/CD134 in response to phytohaemagglutinin together with the in vitro impact of anti-TNF therapy on the functional capacity of T cells were evaluated after 8 years from the onset of the biological treatment. Age-matched healthy donors were enrolled as controls. The quantitative mitogen-induced IFNγ responses significantly increased with respect to baseline at each time point, apart from the determination after 4 years. We found an increased expression of CD25/CD134 in CD4⁺ compared to CD8⁺ T cells both in patients and controls. The in vitro addition of anti-TNF agents induced a significant decrease of both the IFNγ response and of CD25/CD134, whereas no effect on the intensity of the proliferative response was observed. Our data provide a biological basis for the reassuring issues on the safety of long-term anti-TNF treatment in patients with IMID.

Roles of Regulatory T and B Cells in IgG4-Related Disease

Immunoglobulin G4 (IgG4) -related disease (RD) is a newly recognized systemic disease. Although there are several forms of IgG4-RD reported under various names, depending on the target organ and characteristics, patients with IgG4-RD manifest several immunologic and histologic abnormalities including increased levels of serum IgG4 and storiform fibrosis with infiltration of lymphocytes and IgG4-positive plasmacytes in the involved organs. However, the pathophysiology remains unclear. Regulatory immune cells play an important role in several immune-related diseases. In particular, abnormalities in regulatory T cell (Treg) and regulatory B cell (Breg) numbers and function are implicated in several immune-related (include autoimmune) conditions, and their roles in IgG4-RD have recently begun to be investigated. We provide an overview of the research conducted to date on Tregs and Bregs in IgG4-RD. We highlight the basic functions of these cells, their changes in patients with various forms of IgG4-RD, and insight gained from animal models of the disease. Based on the evidence accumulated thus far, we proposed a hypothesis for the pathophysiological mechanism of IgG4-RD with respect to the roles regulatory immune cells, and highlight the questions and venues of research deserving of further attenuation, Over all, we demonstrate that Tregs and Bregs have a clear impact on IgG4-RD, and further exploration of this field is expected to lead to a better mechanistic understanding of the disease, hopefully resulting in the in the discovery of new therapeutic targets.

Preventive Effect of a Novel Recombinant sTNFRII on Collagen-Induced Arthritis

We developed a novel trimeric sTNFRII fusion protein, named sTNFRII-gAD, which exhibited a higher in vitro antagonistic efficacy for TNFα in comparison with sTNFRII-Fc. This study aimed to investigate the arthritic protection of sTNFRII-gAD in a rat collagen-induced arthritis (CIA). The rats were injected intradermally with collagen type II at days 0 and 7. Three days after the second injection (day 10), the rats were intraperitoneally given sTNFRII-gAD or sTNFRII-Fc, or PBS. Effects of treatments were examined with respect of CIA incidence, severity and pathological changes. Serum TNFα, IL-17A and regulatory T cell (Treg) in periphery were determined at days 10 and 16, respectively. Our results showed that sTNFRIIgAD significantly reduced CIA incidence and severity (p < 0.05); meanwhile it led to a dramatic improvement in cartilage and bone damage. Moreover, the increase in serum anti-CII and IL-17A, and the reduction in Treg population were inhibited (p < 0.05) by sTNFRII-gAD or sTNFRII-Fc. Serum TNFα was found to be accumulated in the groups treated with sTNFRII-gAD or sTNFRII-Fc compared with the group treated with PBS (p < 0.05). It is noteworthy that sTNFRII-gAD displayed a better efficacy than sTNFRII-Fc in CIA incidence, pathological changes in cartilage and the elevation of anti-CII antibody, indicating that sTNFRII-gAD is potentially a more efficacious anti-TNFα agent for rheumatoid arthritis.

Altered immunoregulation in rheumatoid arthritis: the role of regulatory T cells and proinflammatory Th17 cells and therapeutic implications

In recent years several studies investigated the role of T lymphocyte subpopulations in the pathogenesis of rheumatoid arthritis (RA). Pathogenic Th17 cells mediate pannus growth, osteoclastogenesis, and synovial neoangiogenesis; hence they are key players in the development of the disease. On the other hand, regulatory T (Treg) cells are a T cell subset whose peculiar function is to suppress autoreactive lymphocytes. The imbalance between Th17 and Treg cells has been identified as a crucial event in the pathogenesis of RA. In addition, the effects of currently employed RA therapeutic strategies on these lymphocyte subpopulations have been extensively investigated. This review article aims to discuss current knowledge on Treg and Th17 cells in RA and possible implications of their therapeutic targeting in this disorder.

The effect of autoimmune arthritis treatment strategies on regulatory T-cell dynamics

PURPOSE OF REVIEW

Since their discovery over 15 years ago, intensive research has focused on the presence, phenotype and function of FOXP3(+) regulatory T cells (Treg) in autoimmune diseases such as rheumatoid arthritis (RA). The questions of whether Treg deficiencies underlie autoimmune pathology and whether or how Treg-related therapeutic approaches might be successful are still a subject of a vivid debate. In this review we give an overview of how current therapies influence Treg numbers and function in RA and juvenile idiopathic arthritis (JIA) and discuss these findings in the light of new Treg-based intervention strategies for autoimmune arthritis.

RECENT FINDINGS

The attempt to relate rheumatic diseases like rheumatoid arthritis and juvenile idiopathic arthritis to Treg has led to somewhat heterogeneous observations. So far, no clear defects in Treg numbers or function have been identified in autoimmune arthritis. The current standard therapies, that is methotrexate and biologicals, are generally effective, but the exact mechanism of action and their effect on Treg is not fully known. Nevertheless, the majority of in-vitro and ex-vivo data point towards a positive influence of these treatments on Treg number and function. These observations are not all consistent, however, and it is not known whether the observed effects on Treg are primary or secondary effects. To safely conduct targeted regulatory T-cell therapy in rheumatic diseases more knowledge about regulatory T-cell function in an inflammatory environment is needed that coincides with the initiative to elucidate the exact mechanism of current therapies.

Infections in children and adolescents with juvenile idiopathic arthritis and inflammatory bowel disease treated with tumor necrosis factor-α inhibitors: systematic review of the literature

Tumor necrosis factor alpha (TNF-α) inhibitors are increasingly administered to children and adolescents with juvenile idiopathic arthritis (JIA) and pediatric inflammatory bowel disease (pIBD). Adult studies indicate that TNF-α inhibitors lead to an increased risk of serious infections compared to other disease-modifying antirheumatic drugs. We report herein a systematic literature review detailing the epidemiology and types of infections reported in children with JIA and pIBD treated with TNF-α inhibitors. The most frequently reported infections were mild and characterized as viral in etiology. Severe bacterial and fungal infections also occurred, but were less common and possibly associated with intrinsic risk factors and concurrent immunosuppressive therapy. Few pediatric patients developed Mycobacterium tuberculosis, likely due to effective screening. There were 8 infectious fatalities in children treated with TNF-α inhibitors. Overall, although rare, serious infections occur in immunocompromised children and adolescents with JIA and pIBD receiving TNF-α inhibitors.

A Fatal Case of Relapsing Pneumonia Caused by Legionella pneumophila in a Patient with Rheumatoid Arthritis After Two Injections of Adalimumab

We present a rare fatal case of relapsing pneumonia caused by Legionella pneumophila in a patient with rheumatoid arthritis after only two injections of adalimumab. A 78-year-old Japanese woman with a 14-year history of rheumatoid arthritis was prescribed adalimumab because her disease activity remained high. However, 8 days after her second injection of adalimumab, she was admitted to our hospital and diagnosed with pneumonia caused by L. pneumophila. Following intravenous antibiotic therapy, she recovered completely from pneumonia and was discharged on day 10, but pneumonia relapsed, resulting in death 79 days after the first episode of pneumonia. L. pneumophila can lead to recurrence of pneumonia that can ultimately prove fatal, similar to the present case. A review of the pertinent literature is also presented.

Adalimumab reversed a severe lymphopenia in a patient with Crohn's disease

Patients with Crohn's disease are frequently found to have low peripheral lymphocyte counts. Lymphopenia has been linked to disease activity, the effects of therapy and the presence of an abnormal T regulatory (T(reg)) function. We present a patient with Crohn's disease and a severe total and CD4 lymphopenia that did not resolve after discontinuation of immunosuppressive treatment and resective surgery. Complete clinical remission and persistent normal levels of total and CD4 lymphocytes were observed after starting therapy with the anti-tumor necrosis factor monoclonal antibody adalimumab.

CD4+CD25+ regulatory T cells in systemic sclerosis and other rheumatic diseases

Systemic sclerosis (SSc) is a generalized connective tissue disorder, characterized by a wide spectrum of microvascular and immunological abnormalities, leading to a progressive thickening and fibrosis of the skin and other organs, such as the lungs, GI tract, heart and kidneys. SSc is thought to be an autoimmune disease owing to the presence of high affinity antibodies and possible clinical overlap with other autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis. Autoimmune diseases arise because of a breakdown in immunological self tolerance. Self tolerance is maintained via multiple regulatory mechanisms within the immune system, including the thymic deletion of self-reactive T cells and mechanisms of peripheral tolerance. In recent years, the presence of CD4(+)CD25(+)FOXP3(+) Tregs has been identified as a major mechanism of peripheral tolerance, and accumulating evidence indicates that alterations in Treg frequencies and/or function may contribute to autoimmune diseases. Here, we will review recent data on the percentage, function and phenotype of CD4(+)CD25(+) Tregs in rheumatic disease, and discuss how recent developments may guide research in this area in SSc.

Number and phenotype of rheumatoid arthritis patients' CD4+CD25hi regulatory T cells are not affected by adalimumab or etanercept

OBJECTIVE

To analyse the therapeutic effects of etanercept (ETA) or adalimumab (ADA) on the numbers and phenotypes of CD4+CD25hi Tregs in RA patients.

METHODS

RA patients received ADA (n = 28) or ETA (n = 20) and stable-dose MTX or LEF. Therapeutic responses were assessed with the 28-joint DAS (DAS-28) criteria after 12 weeks of treatment. Treg numbers and phenotypes, determined by flow cytometry using different gating strategies, were compared between responders and non-responders before and after 6 and 12 weeks of treatment.

RESULTS

The percentages of good, moderate and non-responders among patients given ADA or ETA, respectively, were 46.5, 35.7 and 17.8% or 30, 20 and 50%, with respective mean (s.d.) pre-treatment CD4+CD25hi Treg percentages of 5.5 (0.04)% or 4.95 (0.02)%. Overall, for patients with active RA given ADA or ETA, neither TNF-α-blocking agent had an effect on Tregs percentage and absolute number. Moreover, CD4+CD25hi Treg counts remained unaffected in RA responders to ADA or ETA, compared with RA non-responders. Furthermore, the CD4+CD25hiCD45RA+, CD4+CD25hiCD45RO+ and CD4+CD25hiCD62L+ cell populations were unchanged by TNF-α-blocking agents.

CONCLUSION

Neither ADA nor ETA modified the percentages or absolute numbers of circulating CD4+CD25hi Tregs and their phenotypes after being administered for 6 and 12 weeks to RA patients.

TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00234234.

Adalimumab for the treatment of Crohn's disease

Introduction:

Crohn’s disease (CD) is a chronic inflammatory bowel disease characterized by a relapsing-remitting course with trans-mural inflammation of potentially any section of the digestive tract. Adalimumab (ADA) is a subcutaneously administered, recombinant, fully human, IgG1 monoclonal antibody that binds with high affinity and specificity to human TNF-alpha, thus modulating its biologic functions and its proinflammatory effects.

Aims:

To review the available data on ADA in CD for biological properties, efficacy, and safety.

Methods:

Electronic searches were conducted using the Pubmed and SCOPUS databases from the earliest records to April 2008. The search terms used were “adalimumab”, “anti-TNF”, “TNF-alpha”, “biologicals”, “inflammatory bowel disease”, and “Crohn’s disease”. Reference lists of all relevant articles were searched for further studies.

Results:

Available studies suggest that ADA has the potential to induce and maintain clinical response and remission in moderate-severe CD, both in anti-TNF-naïve patients and in subjects who lost their response and/or became intolerant to infliximab (IFX). ADA seems also effective in maintaining corticosteroid-free remission and obtaining complete fistula closure (although no specific randomized trials are available). No concomitant immunosuppressors seem to be necessary. Side effects appear similar to IFX, while site-injection reactions are frequent and specific. Data on immunogenicity and its clinical impact are uncertain.

Conclusions:

ADA appears to be effective in inducing and maintain clinical remission in CD, including patients not manageable with IFX. Successive clinical practice and further on going trials will confirm a positive role for ADA as a new anti-TNF treatment in CD. The impact on clinical management or on resources should be more studied.

CTLA-4-Ig therapy diminishes the frequency but enhances the function of Treg cells in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune and inflammatory disease. Natural T regulatory (nTreg) cells, which constitutively express the CTLA-4 molecule, have an important role in the pathogenesis of autoimmune conditions. Although it has been reported that biological agents are able to modulate the levels or function of Treg lymphocytes, the possible effect of Abatacept (CTLA-4-Ig) therapy on these cells has not been studied in autoimmune conditions. We explored the effect of Abatacept therapy on Treg cells in patients with RA. The number of different subsets of Treg cells was analyzed by flow cytometry in the peripheral blood from 45 patients with RA that were (n = 30) or not (n = 15) under Abatacept therapy as well as in 20 healthy controls. The function of Treg cells was assessed by an assay of inhibition of lymphocyte proliferation. We found that Abatacept therapy was associated with a significant diminution in the levels of CD4+CD25(bright)Foxp3+, and CD4+CTLA-4+ nTreg cells. In contrast, the regulatory function of CD4+CD25+ lymphocytes was significantly enhanced after the administration of Abatacept. Our data suggest that CTLA-4-Ig exerts a complex and interesting effect on Treg cells in patients with RA.

Anti-TNF-α agents in the treatment of immune-mediated inflammatory diseases: mechanisms of action and pitfalls

TNF-α is a potent inducer of the inflammatory response, a key regulator of innate immunity and plays an important role in the regulation of Th1 immune responses against intracellular bacteria and certain viral infections. However, dysregulated TNF can also contribute to numerous pathological situations. These include immune-mediated inflammatory diseases (IMIDs) including rheumatoid arthritis, Crohn’s disease, psoriatic arthritis, ankylosing spondylitis, ulcerative colitis and severe chronic plaque psoriasis. Animal and human studies concerning the role of TNF-α in IMIDs have led to the development of a therapy based on TNF blockage. This article focuses first on the potential mechanisms by which the three currently licensed agents, adalimumab, etarnecept and infliximab, decrease the inflammatory activity of patients with different IMIDs. Second, it focuses on the risks, precautions and complications of the use of TNF-α inhibitors in these patients.

Discrete changes in circulating regulatory T cells during infliximab treatment of Crohn's disease

Deficiency of CD4+CD25+ regulatory T cells (Tregs) may be involved in Crohn's disease (CD) pathogenesis. In rheumatoid arthritis (RA), the anti-TNF-alpha antibody infliximab increases circulating Treg numbers. We aimed to evaluate circulating Tregs in CD before and after infliximab therapy. In 20 patients with active CD, blood samples were obtained before infusion of infliximab 5 mg/kg and 1, 7, and 42 days after therapy. Clinical, biochemical, and fecal markers of inflammation were obtained. Nine healthy volunteers served as controls. We applied a novel Treg marker, the absence of CD127 expression, to identify Tregs by whole-blood flow cytometry. Treg percentages were similar among CD patients [median 7.7%, interquartile range (IQR) 5.3-10.1%] and healthy volunteers (median 7.6% IQR 6.3-8.9%) with discrete changes (median 7.3%, IQR 4.5-10.1%) throughout the study period, irrespective of the significant clinical effect of infliximab. Unlike in RA, we found no arising population of CD62L - Tregs; however, we observed a rapid recruitment of lymphocytes and upregulation of the intestinal homing marker alpha4beta7 integrin on CD4+T cells. In conclusion, our results do not support the hypothesis that the clinical effect of infliximab is mediated by a reinforcement of defective, circulating Tregs in CD.

Reciprocal changes of Foxp3 expression in blood and intestinal mucosa in IBD patients responding to infliximab

BACKGROUND

Immune therapies may act in inflammatory bowel diseases (IBD) by modulating regulatory T cells (Tregs). Therefore, we investigated the effect of infliximab (IFX) therapy on Forkhead box protein3 (Foxp3) T cells in blood and intestinal mucosa from Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

Forty patients with active IBD (23 CD / 17 UC) were treated with IFX 5 mg/kg intravenously at weeks 0, 2, 6, and each 8 weeks thereafter. Blood samples were obtained before every infusion and T-lymphocyte subsets were characterized by flow cytometry. Foxp3 expression in intestinal biopsies from 43 patients with active IBD (19 CD / 24 UC) before and after IFX infusion and from 6 controls were assessed by quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. Plasma C-reactive protein (CRP), clinical response, and endoscopic healing data were collected in parallel.

RESULTS

IFX therapy resulted in a significant and sustained relative increase of CD4(+)CD25(+)Foxp3(+) Treg and of CD4(+)CD25(-)Foxp3(+) Treg cells in peripheral blood (both P < 0.0001 compared to baseline), particularly in responders (both P < 0.05 compared to nonresponders). The change in CRP over time inversely correlated with the increase of CD25(+)Foxp3(+) cells (P < 0.001, r = -0.39) and durable clinical response was associated with a sustained increase of circulating Foxp3(+) cells. Surprisingly, IFX therapy downregulated mucosal mRNA and protein expression of Foxp3 in UC and CD responders (both P < 0.001) but not in nonresponders.

CONCLUSIONS

IFX therapy has opposite effects in Foxp3(+) Treg cells in blood and gut mucosa, which suggests a redistribution of this important T-cell subset.

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.

[Regulatory T cells and systemic autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis, primary Sjögren's syndrome]

Regulatory/suppressor T cells (Tregs) maintain immunologic homeostasis and prevent autoimmunity. They are the guardians of dominant tolerance. Recent research reveals quantitative and/or functional defect of Tregs in systemic autoimmune diseases. In this article, past and recent studies of Tregs in human systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and primary Sjögren's syndrome (pGSS) are reviewed. Most studies report that Tregs are decreased in peripheral blood of subjects with active SLE. A population of CD4+CD25-Foxp3+ is specifically described in SLE. Tregs functions are still discussed. Tregs counts in peripheral blood of RA patients vary across studies. Enrichment of synovial fluid in Tregs contrasts with inflammation. Tregs suppressive effects are altered in vivo in RA secondary to proinflammatory cytokines environment and resistance of effector T cells to Tregs. In pGSS, the conflicting place of Tregs in the balance prevention of autoimmunity/antitumor immunity is unspecified. Immunosuppressive treatments, like corticosteroids and anti-TNF, modulate Tregs cells population. There is increasing interest in the use of Tregs as a biological therapy to preserve and restore tolerance to self-antigen. However, difficulties to characterize these lymphocytes and controversies in the results of studies refrain their use in current clinical practice.

Treatment of psoriasis in patients with hepatitis C: from the Medical Board of the National Psoriasis Foundation

BACKGROUND

Treating psoriasis in patients with concomitant hepatitis C virus (HCV) infection presents a special challenge. Not only is psoriasis exacerbated by interferon therapy, the standard of care for HCV, but many psoriasis therapies are potentially hepatotoxic, immunosuppressive, or both, which has been generally thought to be a contraindication in chronic infections such as HCV.

OBJECTIVE

Our aim was to arrive at a consensus on treating psoriasis in patients with concomitant HCV infection.

METHODS

Reports in the literature were reviewed regarding common psoriasis therapies and liver toxicity.

RESULTS

Topical therapies are first-line therapy for patients with limited psoriasis and HCV. Ultraviolet B phototherapy may be considered as a second-line treatment when needed. Ultraviolet B phototherapies in combination with topical therapies are first line for patients with moderate to severe psoriasis, and are considered safe in those patients with concomitant HCV infection. Other systemic therapies, such as acitretin, etanercept, and, possibly, other tumor necrosis factor inhibitors, are considered second line. Psoralen plus ultraviolet A should also be considered a second-line therapy.

LIMITATIONS

There are few evidence-based studies on treating psoriasis with systemic therapy in patients with pre-existing liver disease.

CONCLUSIONS

There are no large double-blind clinical trials addressing the treatment of psoriasis in patients with HCV infection and more studies are needed.

Role of regulatory T-cells in autoimmunity

There has been considerable historical interest in the concept of a specialist T-cell subset which suppresses over-zealous or inappropriate T-cell responses. However, it was not until the discovery that CD4(+)CD25(+) T-cells had suppressive capabilities both in vitro and in vivo that this concept regained credibility and developed into one of the most active research areas in immunology today. The notion that in healthy individuals there is a subset of T(reg)-cells (regulatory T-cells) involved in 'policing' the immune system has led to the intensive exploration of the role of this subset in disease resulting in a number of studies concluding that a quantitative or qualitative decline in T(reg)-cells is an important part of the breakdown in self-tolerance leading to the development of autoimmune diseases. Although T(reg)-cells have subsequently been widely postulated to represent a potential immunotherapy option for patients with autoimmune disease, several studies of autoimmune disorders have demonstrated high numbers of T(reg)-cells in inflamed tissue. The present review highlights the need to consider a range of other factors which may be impairing T(reg)-cell function when considering the mechanisms involved in the breakdown of self-tolerance rather than focussing on intrinsic T(reg)-cell factors.

Effect of arsenic on regulatory T cells

INTRODUCTION

Arsenic (As) affects the function and survival of lymphocytes, and some arsenic compounds exert a relevant antineoplastic effect. We have explored the effect of As on T regulatory cells.

RESULTS AND DISCUSSION

In vitro experiments with peripheral blood mononuclear cells from healthy subjects showed that low concentrations of As tended to increase the number of natural T regulatory (nTreg) lymphocytes, whereas concentrations >5.0 muM had an opposite effect. Furthermore, rats exposed to As showed redistribution of nTreg cells, and As administration to rats with experimental allergic encephalomyelitis increased the levels of nTreg cells in spleen and diminished the severity of this condition. On the other hand, in 47 apparently healthy subjects chronically exposed to As, we found significant inverse correlation between urinary As levels and the number and function of nTreg lymphocytes. Although most of these individuals showed enhanced levels of apoptotic lymphocytes in peripheral blood, with a diminution of mitochondrial membrane potential, no significant correlation between these parameters and urinary As was detected.

CONCLUSION

Our data indicate that As seems to have a relevant and complex effect on nTreg cells.

Regulatory T cells and their role in rheumatic diseases: a potential target for novel therapeutic development

Regulatory T cells have an important role in limiting immune reactions and are essential regulators of self-tolerance. Among them, CD4+CD25high regulatory T cells are the best-described subset. In this article, we summarize current knowledge on the phenotype, function, and development of CD4+CD25high regulatory T cells. We also review the literature on the role of these T cells in rheumatic diseases and discuss the potential for their use in immunotherapy.

Collagen-specific T-cell repertoire in blood and synovial fluid varies with disease activity in early rheumatoid arthritis

Introduction

Type II collagen is a DR4/DR1 restricted target of self-reactive T cells that sustain rheumatoid arthritis. The aim of the present study was to analyze the T-cell receptor repertoire at the onset of and at different phases in rheumatoid arthritis.

Methods

We used the CDR3 BV-BJ spectratyping to study the response to human collagen peptide 261–273 in 12 patients with DR4⁺ rheumatoid arthritis (six at the onset of disease and six during the course of disease) and in five healthy DR4⁺ relatives.

Results

The collagen-specific T-cell repertoire is quite restricted at the onset of disease, involving approximately 10 rearrangements. Within the studied collagen-specific rearrangements, nearly 75% is shared among patients. Although the size of the repertoire used by control individuals is comparable to that of patients, it is characterized by different T-cell receptors. Part of the antigen-specific T-cell repertoire is spontaneously enriched in synovial fluid. The specific T-cell repertoire in the periphery was modulated by therapy and decreased with the remission of the disease. Failure of immunoscopy to detect this repertoire was not due to suppression of collagen-driven proliferation in vitro by CD4⁺ CD25⁺ T cells. Clinical relapse of the disease was associated with the appearance of the original collagen-specific T cells.

Conclusions

The collagen-specific T-cell receptor repertoire in peripheral blood and synovial fluid is restricted to a limited number of rearrangements in rheumatoid arthritis. The majority of the repertoire is shared between patients with early rheumatoid arthritis and it is modulated by therapy.

Suppressor activity among CD4+,CD25++ T cells is discriminated by membrane-bound tumor necrosis factor alpha

OBJECTIVE

Previous studies have shown that the suppressive capacity of CD4+,CD25++ T cells is compromised in patients with rheumatoid arthritis (RA) and restored by anti-tumor necrosis factor alpha (anti-TNFalpha) therapy. Given the lack of specific cell surface markers for human Treg cells, this study aimed to define surface markers for identifying and enriching Treg cells with enhanced regulatory ability within the CD4+,CD25++ T cell compartment and to provide additional understanding of the effects of anti-TNFalpha antibodies in humans.

METHODS

The expression of membrane-bound TNFalpha in human peripheral blood CD4+ T cells was analyzed by flow cytometry in healthy individuals and RA patients before and after anti-TNFalpha treatment. Membrane-bound TNFalpha-positive and TNFalpha-negative CD4+,CD25++ T cells were purified by fluorescence-activated cell sorting, and their suppressive capacity was assessed in vitro by a standard suppression assay.

RESULTS

A substantial number of CD4+,CD25++ T cells expressed membrane-bound TNFalpha. Membrane-bound TNFalpha-positive CD4+,CD25++ T cells displayed reduced antiinflammatory cytokine production and less potent suppressor capacity, since 4 times more cells were required to achieve 50% inhibition compared with their membrane-bound TNFalpha-negative counterparts. Treatment of RA patients with TNFalpha-specific antibodies led to a reduction in the number of membrane-bound TNFalpha-positive CD4+,CD25++ T cells from peripheral blood.

CONCLUSION

Our data indicate that the absence of membrane-bound TNFalpha on CD4+,CD25++ T cells can be used to characterize and enrich for Treg cells with maximal suppressor potency. Enrichment of membrane-bound TNFalpha-negative CD4+,CD25+ cells in the CD4+,CD25++ T cell compartment may contribute to restoring the compromised suppressive ability of CD4+,CD25++ T cell populations in RA patients after anti-TNFalpha treatment.

Circulating naïve and CD4+CD25high regulatory T cells in patients with autoimmune pancreatitis

OBJECTIVE

Autoimmune pancreatitis (AIP) is a new clinical entity of pancreatic disorder. There are several immunologic and histological abnormalities specific for the disease, including increased levels of serum IgG4 and infiltration of lymphocytes and IgG4-positive plasmacytes. The role of IgG4 is unclear. Recently, regulatory T cells (Tregs) have been reported to be involved in the development of various autoimmune diseases as well as B cell shifting to IgG4-producing plasmacytes. To clarify the role of Tregs in the pathophysiology of AIP, we analyzed circulating Tregs in AIP.

METHODS

We recruited 27 patients with AIP for this study. For comparison, we also recruited 23 patients with other pancreatic disease and 32 healthy subjects as controls. We analyzed Tregs as CD4+CD25high and CD4+CD25+CD45RA+ (naïve) from peripheral blood by flow cytometry.

RESULTS

In peripheral blood, CD4+CD25high Tregs were significantly increased in AIP patients (3.01% T 1.77%) compared with alcoholic chronic pancreatitis (CP) (1.65% T 0.58%), idiopathic CP (1.53% T0.56%), and healthy control (1.72% T 0.81%, P G 0.05). Naïve Tregs significantly decreased in AIP (0.32% T 0.22%) compared with healthy control (0.83% T 0.65%) and CP group (alcoholic and idiopathic CP; 0.52% T 0.40%, P G 0.05). In untreated AIP patients,the number of CD4+CD25high Tregs and IgG4 are correlated (R =0.53, P G 0.05).

CONCLUSIONS

Increased numbers of CD4+CD25high Tregs may influence IgG4 production in AIP, whereas decreased numbers of naïve Tregs may be involved in the pathogenesis of AIP.

T lymphocytes in Sjögren's syndrome: contributors to and regulators of pathophysiology

Sjögren's syndrome is a chronic autoimmune disorder characterized by lymphocytic infiltration and malfunction of the exocrine glands, resulting in dry mouth and eyes. This multigenic and multifunctional disease can present as primary Sjögren's syndrome or secondary to an underlying connective tissue disease. Immune activation subsequent to activation or apoptosis of glandular epithelial cells in genetically predisposed individuals may expose autoantigens, which engage self-perpetuating T cell dependent autoimmune sequelae. The cellular and molecular context of this immune response may drive proinflammatory (Th1 and Th17) and restrain inhibitory (Treg) pathways. Inability to suppress the immune response results in persistent tissue damage and compromised function of salivary and lacrimal glands. Defining the contributions of participating T cells may unravel strategies for therapeutic intervention.

Tumor necrosis factor antagonist mechanisms of action: a comprehensive review

During the past 30 years, elucidation of the pathogenesis of rheumatoid arthritis, Crohn's disease, psoriasis, psoriatic arthritis and ankylosing spondylitis at the cellular and molecular levels has revealed that these diseases share common mechanisms and are more closely related than was previously recognized. Research on the complex biology of tumor necrosis factor (TNF) has uncovered many mechanisms and pathways by which TNF may be involved in the pathogenesis of these diseases. There are 3 TNF antagonists currently available: adalimumab, a fully human monoclonal antibody; etanercept, a soluble receptor construct; and infliximab, a chimeric monoclonal antibody. Two other TNF antagonists, certolizumab and golimumab, are in clinical development. The remarkable efficacy of TNF antagonists in these diseases places TNF in the center of our understanding of the pathogenesis of many immune-mediated inflammatory diseases. The purpose of this review is to discuss the biology of TNF and related family members in the context of the potential mechanisms of action of TNF antagonists in a variety of immune-mediated inflammatory diseases. Possible mechanistic differences between TNF antagonists are addressed with regard to their efficacy and safety profiles.

Experimental AA amyloidosis in mice is inhibited by treatment with triptolide, a purified traditional Chinese medicine

The effect of triptolide, which is isolated from Tripterygium Wilfordii, on induction and development of murine AA amyloidosis was studied. In the first experiment, we examined the ability of triptolide to inhibit initiation of amyloidosis. Oral or intraperitoneal administration of 480 microg/kg/day triptolide inhibited splenic amyloid deposition in both rapid and chronic induction models of mouse AA amyloidosis. Moreover, serum amyloid A (SAA) and interleukin (IL)-6 levels were also suppressed remarkably. Triptolide also immediately decreased SAA levels and reduced the incidence of amyloidosis even under conditions of high SAA levels. In the second experiment, we evaluated the influence of triptolide on development and resorption of amyloid deposition. Amyloid deposition was induced in mice by 28 daily injections of casein. After splenic and hepatic biopsies to confirm the presence of amyloid deposits, the mice immediately started to receive daily injections of 480 microg/kg/day triptolide with or without casein. Treatment with triptolide for 35 days and 105 days prevented deposition of amyloid and promoted resorption of splenic amyloid deposits. In conclusion, we show for the first time that triptolide inhibits induction and development of experimental murine amyloidosis. These results suggest that through suppression of IL-6, triptolide can reduce production of SAA. Amyloid deposition is prevented when levels of the amyloid-forming precursor protein SAA are decreased significantly.

Mycobacterium tuberculosis-induced cell death of primary human monocytes and macrophages is not significantly modulated by tumor necrosis factor-targeted biologicals

Differential induction of cell death in mycobacteria-infected monocytes and macrophages has been invoked as one possible mechanism by which some tumor necrosis factor (TNF)-targeted biologicals reactivate tuberculosis more frequently than others. We infected primary human monocytes and monocyte-derived macrophages with the virulent Mycobacterium tuberculosis strain H37Rv and followed the rate of cell death in the absence or presence of a wide concentration range of four different TNF-targeted biologicals: infliximab and adalimumab (both monoclonal antibodies to human TNF) and etanercept and polyethylene-glycols TNFR1 (fusion constructs of human TNFR2 and TNFR1, respectively). None of the TNF-targeted biologicals used modulated the death rate of monocytes/macrophages induced by infection with M. tuberculosis alone. Our data support the view that mycobacteria-induced cell death is largely independent of TNF and that the primary target for differential modulation by TNF-targeted biologicals during tuberculosis is not a recently recruited monocyte or freshly differentiated macrophage.

Guidelines for assessing immunocompetency in clinical trials for autoimmune diseases

Clinical trials testing the safety and efficacy of immunosuppressive agents for the treatment of autoimmune diseases should also be designed to evaluate immunocompetency. The most clinically relevant outcome for assessing immunocompetency is the infection rate. Therefore, a systematic approach to screening, monitoring, and reporting infections, modeled after the recommendations of the American Society of Transplantation, is presented. However, because the baseline infection rate in most autoimmune diseases is low, additional tests for immunocompetency should be considered. Evaluation of vaccine responses, an alternative clinically relevant approach, may be particularly useful. Other adjunctive approaches to evaluation of immunocompetency are discussed including immunization with non-vaccine neoantigens, surveillance of chronic viral infections, in vivo or in vitro assessment of cellular immunity, and analysis of innate immunity. Banking genetic material to allow genotyping should be considered particularly if a central repository for samples from different trials can be established.

Inhibition of anti-tuberculosis T-lymphocyte function with tumour necrosis factor antagonists

Reactivation of latent Mycobacterium tuberculosis (Mtb) infection is a major complication of anti-tumour necrosis factor (TNF)-α treatment, but its mechanism is not fully understood. We evaluated the effect of the TNF antagonists infliximab (Ifx), adalimumab (Ada) and etanercept (Eta) on anti-mycobacterial immune responses in two conditions: with ex vivo studies from patients treated with TNF antagonists and with the in vitro addition of TNF antagonists to cells stimulated with mycobacterial antigens. In both cases, we analysed the response of CD4⁺ T lymphocytes to purified protein derivative (PPD) and to culture filtrate protein (CFP)-10, an antigen restricted to Mtb. The tests performed were lymphoproliferation and immediate production of interferon (IFN)-γ. In the 68 patients with inflammatory diseases (rheumatoid arthritis, spondylarthropathy or Crohn's disease), including 31 patients with a previous or latent tuberculosis (TB), 14 weeks of anti-TNF-α treatment had no effect on the proliferation of CD4⁺ T lymphocytes. In contrast, the number of IFN-γ-releasing CD4⁺ T lymphocytes decreased for PPD (p < 0.005) and CFP-10 (p < 0.01) in patients with previous TB and for PPD (p < 0.05) in other patients (all vaccinated with Bacille Calmette-Guérin). Treatments with Ifx and with Eta affected IFN-γ release to a similar extent. In vitro addition of TNF antagonists to CD4⁺ T lymphocytes stimulated with mycobacterial antigens inhibited their proliferation and their expression of membrane-bound TNF (mTNF). These effects occurred late in cultures, suggesting a direct effect of TNF antagonists on activated mTNF⁺ CD4⁺ T lymphocytes, and Ifx and Ada were more efficient than Eta. Therefore, TNF antagonists have a dual action on anti-mycobacterial CD4⁺ T lymphocytes. Administered in vivo, they decrease the frequency of the subpopulation of memory CD4⁺ T lymphocytes rapidly releasing IFN-γ upon challenge with mycobacterial antigens. Added in vitro, they inhibit the activation of CD4⁺ T lymphocytes by mycobacterial antigens. Such a dual effect may explain the increased incidence of TB in patients treated with TNF antagonists as well as possible differences between TNF antagonists for the incidence and the clinical presentation of TB reactivation.

Regulatory T cells in human autoimmune thyroid disease

CONTEXT

T regulatory cells have a key role in the pathogenesis of autoimmune diseases in different animal models. However, less information is available regarding these cells in human autoimmune thyroid diseases (AITD).

OBJECTIVE

The objective of the study was to analyze different regulatory T cell subsets in patients with AITD.

DESIGN

We studied by flow cytometry and immunohistochemistry different T regulatory cell subsets in peripheral blood mononuclear cells (PBMCs) and thyroid cell infiltrates from 20 patients with AITD. In addition, the function of T(REG) lymphocytes was assessed by cell proliferation assays. Finally, TGF-beta mRNA in thyroid tissue and its in vitro synthesis by thyroid mononuclear cells (TMCs) was determined by RNase protection assay and quantitative PCR.

RESULTS

PBMCs from AITD patients showed an increased percent of CD4+ lymphocytes expressing glucocorticoid-induced TNF receptor (GITR), Foxp3, IL-10, TGF-beta, and CD69 as well as CD69+CD25(bright), CD69+TGF-beta, and CD69+IL-10+ cells, compared with controls. TMCs from these patients showed an increased proportion of CD4+GITR+, CD4+CD69+, and CD69+ cells expressing CD25(bright), GITR, and Foxp3, compared with autologous PBMCs. Furthermore, a prominent infiltration of thyroid tissue by CD69+, CD25+, and GITR+ cells, with moderate levels of Foxp3+ lymphocytes, was observed. The suppressive function of peripheral blood T(REG) cells was defective in AITD patients. Finally, increased levels of TGF-beta mRNA were found in thyroid tissue, and thyroid cell infiltrates synthesized in vitro significant levels of TGF-beta upon stimulation through CD69.

CONCLUSIONS

Although T regulatory cells are abundant in inflamed thyroid tissue, they are apparently unable, in most cases, to downmodulate the autoimmune response and the tissue damage seen in AITD.

Regulatory T cells in patients with systemic lupus erythematosus

Regulatory T cells have an important role in the control of self-reactivity, and in the pathogenesis of autoimmune inflammatory conditions. The aim of this work was to perform a quantitative and functional analysis of regulatory T cells in patients with systemic lupus erythematosus (SLE). We studied twenty-three patients with SLE (19 active, 4 inactive), and twenty-seven healthy subjects as well as fifteen patients with rheumatoid arthritis (RA). The following cell subsets were analyzed in peripheral blood mononuclear cells by flow cytometry: CD4+CD25+, CD4+CD25(bright), CD4+Foxp3+ (Treg cells), CD8+CD28- (Ts cells), CD4+IL-10+ (Tr1 cells), and CD4+TGF-beta+ (Th3 cells). In addition, the in vitro suppressive activity of CD4+CD25+ lymphocytes was tested. We found no significant differences in the levels of all regulatory cell subsets studied in SLE patients compared to controls and RA patients. However, a defective regulatory function of CD4+CD25+T cells was observed in a significant fraction (31%) of patients with SLE. Our data indicate that although approximately one third of patients with SLE show an abnormal immunosuppressive function of Treg lymphocytes, their levels of the different regulatory T cell subsets in peripheral blood are not significantly different from those found in controls.