Discovery and preclinical evaluation of KYS202004A, a novel bispecific fusion protein targeting TNF-α and IL-17A, in autoimmune disease models

The treatment of autoimmune and inflammatory diseases often requires targeting multiple pathogenic pathways. KYS202004A is a novel bispecific fusion protein designed to antagonize TNF-α and IL-17A, pivotal in the pathophysiology of autoimmune and inflammatory diseases. Our initial efforts focused on screening for optimal structure by analyzing expression levels, purity, and binding capabilities. The binding affinity of KYS202004A to TNF-α and IL-17A was evaluated using SPR. In vitro, we assessed the inhibitory capacity of KYS202004A on cytokine-induced CXCL1 expression in HT29 cells. In vivo, its efficacy was tested using a Collagen-Induced Arthritis (CIA) model in transgenic human-IL-17A mice and an imiquimod-induced psoriasis model in cynomolgus monkeys. KYS202004A demonstrated significant inhibition of IL-17A and TNF-α signaling pathways, outperforming the efficacy of monotherapeutic agents ixekizumab and etanercept in reducing CXCL1 expression in vitro and ameliorating disease markers in vivo. In the CIA model, KYS202004A significantly reduced clinical symptoms, joint destruction, and serum IL-6 concentrations. The psoriasis model revealed that KYS202004A, particularly at a 2  mg/kg dose, was as effective as the combination of ixekizumab and etanercept. This discovery represents a significant advancement in treating autoimmune and inflammatory diseases, offering a dual-targeted therapeutic approach with enhanced efficacy over current monotherapies.

Paradoxical psoriasis: The flip side of idiopathic psoriasis or an autocephalous reversible drug reaction?

Psoriasis is a common, chronic skin disease that results mainly from the complex interplay between T cells, dendritic cells, and inflammatory cytokines including TNF-α, IL-17, IL-12, and IL-23. Successful therapy with anti-cytokine antibodies has proved the importance of these key cytokines, especially TNF-α. During the anti-TNF-α treatment of classical idiopathic psoriasis, a small portion of patients develop new psoriasiform lesions. This contradictory phenomenon was named paradoxical psoriasis which resembles idiopathic psoriasis clinically but presents overlapped histological patterns and distinct immunological processes. In this review, we discuss the differences between idiopathic psoriasis and paradoxical psoriasis with an emphasis on their innate immunity, as it is predominant in paradoxical psoriasis which exhibits type I IFN-mediated immunity without the activation of autoreactive T cells and memory T cells. We also put up an instructive algorithm for the management of paradoxical psoriasis. The decision on drug discontinuation or switching of biologics should be made based on the condition of underlying diseases and the severity of lesions.

Rationale, current state and opportunities in combining biologic disease modifying antirheumatic drugs in rheumatoid and psoriatic arthritis

The advent of biologic disease modifying antirheumatic drugs (bDMARDs) has considerably improved patient outcomes in inflammatory arthritis. However, not all patients reach the state of remission, as disease can be resistant even to single cytokine inhibition by bDMARDs. Simultaneous or sequential inhibition of multiple cytokines may be considered in situations where disease control is not adequate under singular inhibition of cytokines. Although there have been some disappointing experiences in the past with combination of bDMARDs, the ongoing improvement of our understanding about inflammatory pathways and the overall better safety understanding of bDMARDs seem to make new biologic treatment combinations possible. This review covers the rationale and current evidence for bDMARDs combination in inflammatory arthritis.

Analysis of Novel Immunological Biomarkers Related to Rheumatoid Arthritis Disease Severity

Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs) are the most frequently used rheumatoid arthritis (RA) diagnostic markers, but they are unable to anticipate the patient's evolution or response to treatment. The aim of this study was to identify possible severity biomarkers to predict an upcoming flare-up or remission period. To address this objective, sera and anticoagulated blood samples were collected from healthy controls (HCs; n = 39) and from early RA (n = 10), flare-up (n = 5), and remission (n = 16) patients. We analyzed leukocyte phenotype markers, regulatory T cells, cell proliferation, and cytokine profiles. Flare-up patients showed increased percentages of cluster of differentiation (CD)3+CD4- lymphocytes (p < 0.01) and granulocytes (p < 0.05) but a decreased natural killer (NK)/T lymphocyte ratio (p < 0.05). Analysis of leukocyte markers by principal component analysis (PCA) and receiver operating characteristic (ROC) curves showed that CD45RO+ (p < 0.0001) and CD45RA+ (p < 0.0001) B lymphocyte expression can discriminate between HCs and early RA patients, while CD3+CD4- lymphocyte percentage (p < 0.0424) and CD45RA+ (p < 0.0424), CD62L+ (p < 0.0284), and CD11a+ (p < 0.0185) B lymphocyte expression can differentiate between flare-up and RA remission subjects. Thus, the combined study of these leukocyte surface markers could have potential as disease severity biomarkers for RA, whose fluctuations could be related to the development of the characteristic pro-inflammatory environment.

TRYBE®: an Fc-free antibody format with three monovalent targeting arms engineered for long in vivo half-life

TrYbe® is an Fc-free therapeutic antibody format, capable of engaging up to three targets simultaneously, with long in vivo half-life conferred by albumin binding. This format is shown by small-angle X-ray scattering to be conformationally flexible with favorable 'reach' properties. We demonstrate the format's broad functionality by co-targeting of soluble and cell surface antigens. The benefit of monovalent target binding is illustrated by the lack of formation of large immune complexes when co-targeting multivalent antigens. TrYbes® are manufactured using standard mammalian cell culture and protein A affinity capture processes. TrYbes® have been formulated at high concentrations and have favorable drug-like properties, including stability, solubility, and low viscosity. The unique functionality and inherent developability of the TrYbe® makes it a promising multi-specific antibody fragment format for antibody therapy.

Exocrine pancreas regeneration modifies original pancreas to alleviate diabetes in mouse models

Diabetes is a major public health issue because of its widely epidemic nature and lack of cure. Here, we show that pancreas-derived mesenchymal stem cells (PMSCs) are capable of regenerating exocrine pancreas when implanted into the kidney capsule of mice with streptozotocin (STZ)-induced diabetes. Mechanistically, we found that the regenerated exocrine pancreas elevated interleukin-6 (IL-6) in PMSC implants, which transiently activated tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) to inhibit IL-17, thereby rescuing damaged exocrine pancreas and islet β cells. In addition, we used knockout mouse models to show that global lack of IL-6, TNF-α, or IFN-γ resulted in increased severity of STZ-induced diabetes and resistance to PMSC implantation therapy, confirming the roles of these factors in safeguarding pancreatic β cells. Furthermore, removal of the kidney capsule PMSC implants at 28 days after implantation did not affect the PMSC-initiated therapeutic effect on diabetic mice. This study reveals a previously unknown role of exocrine pancreas regeneration in safeguarding β cells and demonstrates a "soil-rescues-seed" strategy for type 1 diabetes therapy.

CD4+ T-Cell Dysfunction in Severe COVID-19 Disease Is Tumor Necrosis Factor-α/Tumor Necrosis Factor Receptor 1-Dependent

Rationale: Lymphopenia is common in severe coronavirus disease (COVID-19), yet the immune mechanisms are poorly understood. As inflammatory cytokines are increased in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we hypothesized a role in contributing to reduced T-cell numbers. Objectives: We sought to characterize the functional SARS-CoV-2 T-cell responses in patients with severe versus recovered, mild COVID-19 to determine whether differences were detectable. Methods: Using flow cytometry and single-cell RNA sequence analyses, we assessed SARS-CoV-2-specific responses in our cohort. Measurements and Main Results: In 148 patients with severe COVID-19, we found lymphopenia was associated with worse survival. CD4⁺ lymphopenia predominated, with lower CD4⁺/CD8⁺ ratios in severe COVID-19 compared with patients with mild disease (P < 0.0001). In severe disease, immunodominant CD4⁺ T-cell responses to Spike-1 (S1) produced increased in vitro TNF-α (tumor necrosis factor-α) but demonstrated impaired S1-specific proliferation and increased susceptibility to activation-induced cell death after antigen exposure. CD4⁺TNF-α⁺ T-cell responses inversely correlated with absolute CD4⁺ counts from patients with severe COVID-19 (n = 76; R = -0.797; P < 0.0001). In vitro TNF-α blockade, including infliximab or anti-TNF receptor 1 antibodies, strikingly rescued S1-specific CD4⁺ T-cell proliferation and abrogated S1-specific activation-induced cell death in peripheral blood mononuclear cells from patients with severe COVID-19 (P < 0.001). Single-cell RNA sequencing demonstrated marked downregulation of type-1 cytokines and NFκB signaling in S1-stimulated CD4⁺ cells with infliximab treatment. We also evaluated BAL and lung explant CD4⁺ T cells recovered from patients with severe COVID-19 and observed that lung T cells produced higher TNF-α compared with peripheral blood mononuclear cells. Conclusions: Together, our findings show CD4⁺ dysfunction in severe COVID-19 is TNF-α/TNF receptor 1-dependent through immune mechanisms that may contribute to lymphopenia. TNF-α blockade may be beneficial in severe COVID-19.

Disease status in human and experimental arthritis, and response to TNF blockade, is associated with MHC class II invariant chain (CD74) isoform expression

Splice variants of CD74 differentially modulate the activity of cathepsin L (CTSL). As CD74 and CTSL participate in the pathogenesis of inflammatory diseases such as rheumatoid arthritis (RA), we determined whether splice variants of CD74 could be biomarkers of disease activity. Gene expression was measured in mice with collagen-induced arthritis using quantitative PCR (qPCR). In vitro studies using murine macrophage/DC-lineage cells determined the relative influence of macrophage phenotype on isoform expression and the potential to produce CTSL in response to TNF. CD74 splice variants were measured in human RA synovium and RA patients' monocytes. In arthritic mice, the expression of the p41 CD74 isoform was significantly higher in severely affected paws compared with unaffected paws or the paws of naïve mice; the p41 isoform significantly correlated with the expression of TNF in arthritic paws. Compared with M2-like macrophages, M1-like macrophages expressed increased levels of CD74 and had higher expression, secretion and activity of CTSL. RA patients that responded to TNF blockade had significantly higher expression levels of CD74 in circulating monocytes after treatment, compared with non-responders. The expression of the human CD74 isoform a was significantly higher in RA synovia, compared with osteoarthritis synovia, and was associated with CSTL enzymatic activity. This study is the first to demonstrate differential expression of the CD74 p41 isoform in an auto-immune disorder and in response to therapy. The differential expression of CD74 splice variants indicates an association, and potentially a mechanistic role, in the pathogenesis of RA.

Toward Overcoming Treatment Failure in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disorder characterized by inflammation and bone erosion. The exact mechanism of RA is still unknown, but various immune cytokines, signaling pathways and effector cells are involved. Disease-modifying antirheumatic drugs (DMARDs) are commonly used in RA treatment and classified into different categories. Nevertheless, RA treatment is based on a "trial-and-error" approach, and a substantial proportion of patients show failed therapy for each DMARD. Over the past decades, great efforts have been made to overcome treatment failure, including identification of biomarkers, exploration of the reasons for loss of efficacy, development of sequential or combinational DMARDs strategies and approval of new DMARDs. Here, we summarize these efforts, which would provide valuable insights for accurate RA clinical medication. While gratifying, researchers realize that these efforts are still far from enough to recommend specific DMARDs for individual patients. Precision medicine is an emerging medical model that proposes a highly individualized and tailored approach for disease management. In this review, we also discuss the potential of precision medicine for overcoming RA treatment failure, with the introduction of various cutting-edge technologies and big data.

Combined Etanercept, GAD-alum and vitamin D treatment: an open pilot trial to preserve beta cell function in recent onset type 1 diabetes

AIM

We aimed to study the feasibility and tolerability of a combination therapy consisting of glutamic acid decarboxylase (GAD-alum), Etanercept and vitamin D in children and adolescents with newly diagnosed with type 1 diabetes (T1D), and evaluate preservation of beta cell function.

MATERIAL AND METHODS

Etanercept Diamyd Combination Regimen is an open-labelled multi-centre study pilot trial which enrolled 20 GAD antibodies positive T1D patients (7 girls and 13 boys), aged (mean ±SD): 12.4 ± 2.3 (8.3-16.1) years, with a diabetes duration of 81.4 ± 22.1 days. Baseline fasting C-peptide was 0.24 ± 0.1 (0.10-0.35) nmol/l. The patients received Day 1-450 Vitamin D (Calciferol) 2000 U/d per os, Etanercept sc Day 1-90 0.8 mg/kg once a week and GAD-alum sc injections (20 μg, Diamyd™) Day 30 and 60. They were followed for 30 months.

RESULTS

No treatment related serious adverse events were observed. After 6 months 90-min stimulated C-peptide had improved in 8/20 patients and C-peptide area under the curve (AUC) after Mixed Meal Tolerance Test in 5 patients, but declined thereafter, while HbA1c and insulin requirement remained close to baseline. Administration of Etanercept did not reduce tumour necrosis factor (TNF) spontaneous secretion from peripheral blood mononuclear cells, but rather GAD65-induced TNF-α increased. Spontaneous interleukin-17a secretion increased after the administration of Etanercept, and GAD65-induced cytokines and chemokines were also enhanced following 1 month of Etanercept administration.

CONCLUSIONS

Combination therapy with parallel treatment with GAD-alum, Etanercept and vitamin D in children and adolescents with type 1 diabetes was feasible and tolerable but had no beneficial effects on the autoimmune process or beta cell function.

Aqueous Extract of Kan-Lu-Hsiao-Tu-Tan Ameliorates Collagen-Induced Arthritis in Mice by Inhibiting Oxidative Stress and Inflammatory Responses

Background: Kan-Lu-Hsiao-Tu-Tan (KLHTT) exhibits anti-psoriatic effects through anti-inflammatory activity in mice. However, the therapeutic effects of KLHTT on rheumatoid arthritis (RA), another significant autoimmune inflammatory disorder, have not been elucidated. Herein, we explored the anti-arthritic effects of KLHTT on collagen-induced arthritis (CIA) in mice. Methods: KLHTT was extracted by boiling water and subjected to spectroscopic analysis. Chicken collagen type II (CII) with complete Freund’s adjuvant was intradermally injected to induce CIA in DBA/1J mice. Anti-CII antibody, cytokines, malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) were measured using ELISA, thiobarbituric acid reactive substances, and a hydrogen peroxide assay kit. Splenocyte proliferation was tested using thymidine incorporation. Th1 and Th17 cells were analyzed by flow cytometry. Results: Oral KLHTT treatment (50 and 100 mg/kg) ameliorated mouse CIA by decreasing the levels of interleukin (IL)-1β, IL-6, IL-17A, and tumour necrosis factor-α in the paw homogenates and serum. KLHTT also suppressed anti-CII antibody formation, splenocyte proliferation, and splenic Th1 and Th17 cell numbers. Additionally, KLHTT showed antioxidant activity by reducing the concentrations of MDA and H₂O₂ in paw tissues. Conclusions: The therapeutic effects of KLHTT in CIA mice were through regulating oxidative stress and inflammatory responses. Our results suggest that KLHTT has potential to treat RA.

Anti-tumor necrosis factor treatment increases both the Th17 and Th22 T helper subsets in spondyloarthritis

The aim was to examine anti-tumor necrosis factor α (anti-TNFα) therapy influence changes on Th17 and Th22 cells in patients with spondyloarthritis (SpA), and its correlation with changes in clinical and magnetic resonance imaging (MRI) activity and chronicity scores. The Th17 and Th22 cells were assessed at baseline, after 12 and 52 weeks of anti-TNFα therapy by flow cytometry (ClinicalTrials.gov NCT4682724). The percentages of both Th17 and Th22 cells were increased by 70% at baseline compared with healthy controls (both p < 0.01). During treatment, these two subsets increased further to be 170% (Th17) and 123% (Th22) above levels in healthy controls (both p < 0.01). The same subsets decrease their expression of IL-23R significantly during the observation period (p < 0.05). High levels of Th17 and Th22 cells at baseline were associated with the degree of chronic changes in the sacroiliac joints on MRI and a good clinical response to anti-TNFα treatment after one year. Plasma levels were not associated with clinical changes. Th17 cells, and Th22 subsets, increased during one year of anti-TNF-α therapy in SpA, regardless of their clinical improvement. This supports that both the Th17 and Th22 subsets could be involved in the progression in SpA.

Chemokines: A Potential Therapeutic Target to Suppress Autoimmune Arthritis

BACKGROUND

Chemokines are a family of low molecular weight proteins that induce chemotaxis of inflammatory cells, which mainly depends on the recognition of a chemo-attractant gradient and interaction with the substratum. In Rheumatoid Arthritis (RA), abundant chemokines are expressed in synovial tissue, cause inflammatory cells migration into the inflamed joint that necessitates the formation of new blood vessels i.e. angiogenesis. Over the decades, studies showed that continuous inflammation may lead to the loss of tissue architecture and function, causing severe disability and cartilage destruction. In spite of the advancement of modern drug therapy, thousands of arthritic patients suffer mortality and morbidity globally. Thus, there is an urgent need for the development of novel therapeutic agents for the treatment of RA.

METHODS

This review is carried out throughout a non-systematic search of the accessible literature, will provide an overview of the current information of chemokine in RA and also exploring the future perspective of the vital role of targeting chemokine in RA treatment.

RESULTS

Since, chemokines are associated with inflammatory cells/leucocyte migration at the site of inflammation in chronic inflammatory diseases and hence, blockade or interference with chemokines activity showing a potential approach for the development of new anti-inflammatory agents. Currently, results obtained from both preclinical and clinical studies showed significant improvement in arthritis.

CONCLUSION

This review summarizes the role of chemokines and their receptors in the pathogenesis of RA and also indicates possible interactions of chemokines/receptors with various synthetic and natural compounds that may be used as a potential therapeutic target in the future for the treatment of RA.

Tumor Necrosis Factor-Alpha Antagonist Interferes With the Formation of Granulomatous Multinucleated Giant Cells: New Insights Into Mycobacterium tuberculosis Infection

More than half of tuberculosis cases in the world are due to resuscitation of dormant Mycobacterium tuberculosis (Mtb) sequestered into cell-derived structures called granulomas. It is fairly admitted that cytokines and more particularly Tumor Necrosis Factor (TNF)-α is critical in the control of Mtb infections and that anti-TNF-α drugs constitute one of the main risk factors for reactivation of latent Mtb infection. The aim of this study was to evaluate the role of etanercept, a dimeric fusion protein consisting of the extracellular ligand-binding portion of the human p75 TNF receptor linked to the Fc portion of human IgG1, in an in vitro model of human tuberculous granuloma. We showed that etanercept slightly delayed the formation of granuloma and reduced the generation of multinuclear giant cells (MGCs). In addition, etanercept exacerbated the expression of M1 polarization genes but also induced interleukin (IL)-10 release. In addition, our results indicated that etanercept inhibited cell fusion in an IL-10-dependent manner. Moreover, adalimumab, a human monoclonal anti-TNF-α IgG1 inhibited MGC formation in granuloma, without altering IL-10 secretion and induced macrophage apoptosis. Taken together, our data provides new insights into the role of TNF-α blockers in MGCs formation and the impact of such immunomodulatory drugs on tuberculous granuloma maturation.

cIAP1/2 inhibition synergizes with TNF inhibition in autoimmunity by down-regulating IL-17A and inducing Tregs

IL-17 and TNF-α are major effector cytokines in chronic inflammation. TNF-α inhibitors have revolutionized the treatment of rheumatoid arthritis (RA), although not all patients respond, and most relapse after treatment withdrawal. This may be due to a paradoxical exacerbation of T_H17 responses by TNF-α inhibition. We examined the therapeutic potential of targeting cellular inhibitors of apoptosis 1 and 2 (cIAP1/2) in inflammation by its influence on human T_H subsets and mice with collagen-induced arthritis. Inhibition of cIAP1/2 abrogated CD4⁺ IL-17A differentiation and IL-17 production. This was a direct effect on T cells, mediated by reducing NFATc1 expression. In mice, cIAP1/2 inhibition, when combined with etanercept, abrogated disease activity, which was associated with an increase in T_regs and was sustained after therapy retraction. We reveal an unexpected role for cIAP1/2 in regulating the balance between T_H17 and T_regs and suggest that combined therapeutic inhibition could induce long-term remission in inflammatory diseases.

Restored and Enhanced Memory T Cell Immunity in Rheumatoid Arthritis After TNFα Blocker Treatment

TNFα inhibitors have shaped the landscape of rheumatoid arthritis (RA) therapy with high clinical efficiency. However, their impact on T cell recall responses is not well-elucidated. We aimed to analyze the immune profiles of memory T cells in RA patients undergoing TNFα inhibitor Golimumab (GM) treatment. Frequencies of peripheral T cell subsets and cytokine expression profiles in memory T cells (T_M) upon PMA/Ionomycine stimulation were determined by flow cytometry. Antigen-specific CD8 T cell immunity was analyzed through stimulating PBMCs with CMV-EBV-Flu (CEF) viral peptide pool and subsequent intracellular IFNγ staining. Both peripheral CD8 and CD4 T cells from GM treated patients had a shift pattern characterized by an enlarged effector T_M and a reduced central T_M cell population when compared to GM untreated group. An increase in the frequencies of TNFα⁺, IL-2⁺, and IL-17⁺ CD8 T_M cells was observed whereas only TNFα⁺CD4 T_M cells increased in GM treated patients. Moreover, GM treated patients contained more peripheral IFNγ-producing CD8 T cells specific to CEF viral peptides. Together, these results show a distinct T cell subset pattern and enhanced memory T cell immunity upon GM treatment, suggesting an immunoregulatory effect of TNF inhibitor Golimumab on peripheral memory T cell responses.

Ibudilast Inhibits Chemokine Expression in Rheumatoid Arthritis Synovial Fibroblasts and Exhibits Immunomodulatory Activity in Experimental Arthritis

OBJECTIVE

Ibudilast is a well-tolerated, orally available phosphodiesterase 4 (PDE4) inhibitor used to treat asthma and stroke. Since PDE4 inhibition suppresses inflammatory mediator production and cell proliferation in leukocytes, ibudilast may be a valuable therapy for the treatment of inflammatory autoimmune diseases such as rheumatoid arthritis (RA). This study was undertaken to assess the therapeutic potential of ibudilast by measuring its capacity to modulate inflammation in human leukocytes and RA synovial fibroblasts (RASFs) and in experimental arthritis.

METHODS

Using standard curve quantitative polymerase chain reaction, the effect of ibudilast on gene expression in activated human leukocytes and RASFs was measured. Ibudilast was used to treat DBA/1 mice with collagen-induced arthritis, and an adoptive transfer model was used to assess its tolerogenic capacity.

RESULTS

Ibudilast inhibited the expression of TNF, IL12A, and IL12B and the secretion of tumor necrosis factor (TNF) and interleukin-12 (IL-12)/23p40 from leukocytes, and reduced the expression of CCL5 and CCL3 in activated RASFs. Treatment of experimental arthritis with ibudilast resulted in a reduction in IL-17-producing cells and inhibition of disease progression. When combined with a TNF inhibitor, ibudilast caused marked suppression of active disease. Exposure of leukocytes from type II collagen-immunized DBA/1 mice to ibudilast in vitro attenuated their ability to adoptively transfer arthritis to DBA/1J-Prkdc^SCID mice, providing evidence of an immunomodulatory effect.

CONCLUSION

Our findings indicate that ibudilast reduces the expression and/or secretion of inflammatory mediators from activated human leukocytes and RASFs, inhibits Th17 cell responses in vivo, and improves established arthritis. Given the established safety profile of ibudilast in humans, its clinical evaluation in RA, either alone or in combination with a TNF inhibitor, should be considered.

Anti-TNF Therapy in Spondyloarthritis and Related Diseases, Impact on the Immune System and Prediction of Treatment Responses

Immune-mediated inflammatory diseases (IMIDs), such as spondyloarthritis (SpA), psoriasis, Crohn's disease (CD), and rheumatoid arthritis (RA) remain challenging illnesses. They often strike at a young age and cause lifelong morbidity, representing a considerable burden for the affected individuals and society. Pioneering studies have revealed the presence of a TNF-dependent proinflammatory cytokine cascade in several IMIDs, and the introduction of anti-TNF therapy 20 years ago has proven effective to reduce inflammation and clinical symptoms in RA, SpA, and other IMID, providing unprecedented clinical benefits and a valid alternative in case of failure or intolerable adverse effects of conventional disease-modifying antirheumatic drugs (DMARDs, for RA) or non-steroidal anti-inflammatory drugs (NSAIDs, for SpA). However, our understanding of how TNF inhibitors (TNFi) affect the immune system in patients is limited. This question is relevant because anti-TNF therapy has been associated with infectious complications. Furthermore, clinical efficacy of TNFi is limited by a high rate of non-responsiveness (30–40%) in RA, SpA, and other IMID, exposing a substantial fraction of patients to side-effects without clinical benefit. Despite the extensive use of TNFi, it is still not possible to determine which patients will respond to TNFi before treatment initiation. The recent introduction of antibodies blocking IL-17 has expanded the therapeutic options for SpA, as well as psoriasis and psoriatic arthritis. It is therefore essential to develop tools to guide treatment decisions for patients affected by SpA and other IMID, both to optimize clinical care and contain health care costs. After a brief overview of the biology of TNF, its receptors and currently used TNFi in the clinics, we summarize the progress that has been made to increase our understanding of the action of TNFi on the immune system in patients. We then summarize efforts dedicated to identify biomarkers that can predict treatment responses to TNFi and we conclude with a section dedicated to the recently introduced inhibitors of IL-17A and IL-23 in SpA and related diseases. The focus of this review is on SpA, however, we also refer to RA on topics for which only limited information is available on SpA in the literature.

No effect of anti-TNF-α treatment on serum IL-17 in patients with rheumatoid arthritis

Introduction

Interleukin 17 (IL-17) and CC-chemokine ligand 20 (CCL20) are increasingly implicated in the pathogenesis of rheumatoid arthritis (RA). A correlation has been reported to exist between serum levels of IL-17 and CCL20 and the disease activity. However, such an effect has not been universally demonstrated. The aim of the present study was to investigate if serum levels of IL-17 and/or CCL20 reflect the disease activity and response to anti-TNF-α therapy in patients with RA.

Material and methods

Twenty-two RA patients qualified to receive anti-TNF-α treatment were prospectively assessed before and after 12 weeks of therapy. Serum concentrations of IL-17 and CCL20 were measured with high-sensitivity immunoassays. Disease activity was assessed by the 28-joint disease activity score (DAS28).

Results

Twelve weeks of therapy resulted in a satisfactory therapeutic response in the majority (91%) of patients (reflected both by clinical and standard biochemical criteria). However, serum concentrations of IL-17 and CCL20 did not change significantly over the course of therapy Moreover, they did not correlate with the disease activity, patient characteristics, and their response to therapy.

Conclusions

Serum levels of IL-17 and CCL20 do not reflect changes in the clinical and biochemical status that occur in patients undergoing anti-TNF-α treatment for RA. The lack of such an association indicates that IL-17 signalling is not affected by anti-TNF-α therapy and is thus not critically involved in the disease pathogenesis.

Modulation of T-cell responses by anti-tumor necrosis factor treatments in rheumatoid arthritis: a review

Tumor necrosis factor (TNF) is a pleiotropic cytokine involved in many aspects of immune regulation. Anti-TNF biological therapy has been considered a breakthrough in the treatment of chronic autoimmune diseases, such as rheumatoid arthritis (RA). In this review, because of the major involvement of T cells in RA pathogenesis, we discuss the effects of anti-TNF biotherapy on T-cell responses in RA patients. We also outline the potential fields for future research in the area of anti-TNF therapy in RA.This could be useful to better understand the therapeutic efficiency and the side effects that are encountered in RA patients. Better targeting of T cells in RA could help set more specific anti-TNF strategies and develop prediction tools for response.

TNF-α-induced protein 3 (TNFAIP3)/A20 acts as a master switch in TNF-α blockade-driven IL-17A expression

BACKGROUND

Anti-TNF inhibitors successfully improve the quality of life of patients with inflammatory disease. Unfortunately, not all patients respond to anti-TNF therapy, and some patients show paradoxical immune side effects, which are poorly understood. Surprisingly, anti-TNF agents were shown to promote IL-17A production with as yet unknown clinical implications.

OBJECTIVE

We sought to investigate the molecular mechanism underlying anti-TNF-driven IL-17A expression and the clinical implications of this phenomenon.

METHODS

Fluorescence-activated cell sorting, RNA sequencing, quantitative real-time PCR, Western blotting, small interfering RNA interference, and kinase inhibitors were used to study the molecular mechanisms in isolated human CD4⁺ T cells from healthy donors. The clinical implication was studied in blood samples of patients with inflammatory bowel disease (IBD) receiving anti-TNF therapy.

RESULTS

Here we show that anti-TNF treatment results in inhibition of the anti-inflammatory molecule TNF-α-induced protein 3 (TNFAIP3)/A20 in memory CD4⁺ T cells. We found an inverse relationship between TNFAIP3/A20 expression levels and IL-17A production. Inhibition of TNFAIP3/A20 promotes kinase activity of p38 mitogen-activated protein kinase and protein kinase C, which drives IL-17A expression. Regulation of TNFAIP3/A20 expression and cognate IL-17A production in T cells are specifically mediated through TNF receptor 2 signaling. Ex vivo, in patients with IBD treated with anti-TNF, we found further evidence for an inverse relationship between TNFAIP3/A20 expression levels and IL-17A-producing T cells.

CONCLUSION

Anti-TNF treatment interferes in the TNFAIP3/A20-mediated anti-inflammatory feedback loop in CD4⁺ T cells and promotes kinase activity. This puts TNFAIP3/A20, combined with IL-17A expression, on the map as a potential tool for predicting therapy responsiveness or side effects of anti-TNF therapy. Moreover, it provides novel targets related to TNFAIP3/A20 activity for superior therapeutic regimens in patients with IBD.

The Impact of Anti-TNF Therapy on CD4+ and CD8+ Cell Subsets in Ankylosing Spondylitis

OBJECTIVES

Ankylosing spondylitis (AS) is a chronic, progressive immune-mediated inflammatory disease, driven primarily by Th1 and Th17 cells. Anti-TNF therapies are successfully used in AS to achieve and maintain remission. However, their influence on the composition of T-cell subsets is not clear. We aimed to characterize the changes in the T-cell repertoire after a long-term anti-TNF treatment in AS patients.

METHODS

Twenty-two AS patients under long-term anti-TNF therapy were evaluated (15 anti-TNF responders and 7 nonresponders). A wide range of cell subtypes was analyzed with flow cytometry and compared with therapy-naïve and short-term data too.

RESULTS

Key findings include decreased proportions of naïve CD4 and CD8 cells, increased frequencies of Th1 and Th17 cells and higher Th1/Th2 ratios in the long-term anti-TNF-treated patients (responders, nonresponders and total), which was found to be significant not only when compared with healthy controls, but also with therapy-naïve and short-term anti-TNF-treated AS patients. We noted several alterations within the various activated T-cell subsets - increase in CD4HLADR cells in responders, in CD8HLADR cells in the whole AS group and in responders, and in CD4CD25 cells in responders, and decrease in CD4CD69 cell percentages in long-term treated patients - becoming evident only after long-term anti-TNF therapy.

CONCLUSIONS

This study provides a comprehensive assessment of the impact of anti-TNF therapy on the T-cell repertoire in AS. Changes in T-cell phenotype seem to develop progressively during therapy, even in inactive disease, and reflect an ongoing effector T-cell differentiation and activation, along with the parallel compensatory increase in regulatory T cells.

Th17 and CD24hiCD27+ regulatory B lymphocytes are biomarkers of response to biologics in rheumatoid arthritis

Background

The aim was to describe the regulatory B and T cells (Breg and Treg) and T helper 17 (Th17) lymphocytes before and under treatment with biologic drugs, and to assess their potential predictive value as biomarkers of response in rheumatoid arthritis (RA).

Methods

This was a non-randomised, single-centre, prospective study. Patients with active RA (American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) 2010) who required the initiation or switch to any biologic drug except rituximab were included. The main judgement criterion was the frequency and absolute number of CD24^hiCD27⁺ Breg and CD24^hiCD38^hi T2/Breg cells, CD25^hiCD127^low Treg and CD45RA⁻CD161⁺CCR6⁺ Th17 cells measured at inclusion in both patients and controls, and after 1, 3 and 6 months of treatment (M1, M3 and M6) in patients with RA, and compared with the M6 response to treatment (EULAR response and Disease Activity Score in 28 joints (DAS28) remission).

Results

Thirty-one patients with RA and 17 controls were included. There was a reduction in T2/Breg frequency at M0 in patients (p < 0.001) and absolute numbers (p = 0.014) and in immunopositive vs. immunonegative RA (p = 0.016). DAS28 remission at M6 was associated with increased frequency of Treg (p = 0.01). A higher level of CD24^hiCD27⁺ Breg at baseline was associated with DAS28 remission at M6 (p = 0.04) and a good EULAR response at M6 for abatacept-treated patients (p = 0.01). A lower M0 level of Th17 was associated with a good EULAR response at M6 (p = 0.007), notably under anti-cytokine drugs (p = 0.048).

Conclusions

Altogether, these data, although preliminary, suggest that phenotyping of T and B cells has potential value for the stratification of biologic drugs, notably with respect to choosing between abatacept and anti-cytokine blockade.

Higher efficacy of anti-IL-6/IL-21 combination therapy compared to monotherapy in the induction phase of Th17-driven experimental arthritis

Th17 cells and their cytokines are linked to the pathogenesis of rheumatoid arthritis, a chronic autoimmune disease characterized by joint inflammation. Th17 development is initiated by combined signaling of TGF-β and IL-6 or IL-21, and can be reduced in the absence of either IL-6 or IL-21. The aim of this study was to assess whether combinatorial IL-6/IL-21 blockade would more potently inhibit Th17 development, and be more efficacious in treating arthritis than targeting either cytokine. We assessed in vitro Th17 differentiation efficacy in the absence of IL-6 and/or IL-21. To investigate in vivo effects of IL-6/IL-21 blockade on Th17 and arthritis development, antigen-induced arthritis (AIA) was induced in IL-6^-/- x IL-21R^-/- mice. The therapeutic potential of this combined blocking strategy was assessed by treating mice with collagen-induced arthritis (CIA) with anti-IL-6R antibodies and soluble (s)IL-21R.Fc. We demonstrated that combined IL-6/IL-21 blocking synergistically reduced in vitro Th17 differentiation. In mice with AIA, absence of IL-6 and IL-21 signaling more strongly reduced Th17 levels and resulted in stronger suppression of arthritis than the absence of either cytokine. Additionally, anti-IL-6/anti-IL-21 treatment of CIA mice during the arthritis induction phase reduced disease development more potent than IL-6 or IL-21 inhibition alone, as effective as anti-TNF treatment. Collectively, these results suggest dual IL-6/IL-21 inhibition may be a more efficacious therapeutic strategy compared to single cytokine blockade to suppress arthritis development.

Increase in circulating Th17 cells during anti-TNF therapy is associated with ultrasonographic improvement of synovitis in rheumatoid arthritis

BACKGROUND

Anti-TNF agents have revolutionised rheumatoid arthritis (RA) treatment; however, a third of patients fail to achieve therapeutic responses. Unexpectedly, studies in murine and human arthritis have indicated that anti-TNF treatment can increase circulating T helper 17 (Th17) cells, but the relationship to treatment response is unclear. To identify immune correlates of anti-TNF treatment response, we conducted a longitudinal study using clinical, ultrasound and T cell assessments.

METHODS

Patients with RA (n = 25) were studied at protocol visits during the initial 12 weeks of anti-TNF treatment. Improvement in the disease activity score of 28 joints (DAS28) >1.2 defined treatment responders (n = 16) and non-responders (n = 9). Changes in synovial thickening and vascularity of 10 metacarpophalangeal joints were quantitatively assessed by grey scale and power Doppler ultrasound. The frequency of circulating Th17 cells was determined by IL17 enzyme-linked immunospot assay (Elispot) and flow cytometry (fluorescence-activated cell sorting (FACS)).

RESULTS

The frequency of circulating IL17-producing cells increased significantly 12 weeks after anti-TNF initiation (Elispot median (range) specific spot forming cells (spSFC)/10⁶ 360 (280-645) vs 632 (367 - 1167), p = 0.003). The increase in CD4 + IL17+ cells at 12 weeks was confirmed by FACS (median (range) %, 0.7 (0.5-0.9) vs 1.05 (0.6-1.3); p = 0.01). The increase in circulating Th17 cells inversely correlated with reduction in synovial vascularity (r = -0.68, p = 0.007) and thickening (r = -0.39; p = 0.04). Higher frequencies of circulating Th17 cells at baseline were associated with poorer anti-TNF treatment response defined by ultrasonographic measures.

CONCLUSIONS

These results demonstrate a link between changes in circulating Th17 cells with resolution of ultrasonographic features of synovial inflammation and vascularity during anti-TNF treatment. The findings may reflect redistribution of Th17 cells from inflamed joints or TNF-driven regulation of Th17 cell production.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01060098 . Registered 29 January 2010.

TLRs, future potential therapeutic targets for RA

Toll like receptors (TLR)s have a central role in regulating innate immunity and in the last decade studies have begun to reveal their significance in potentiating autoimmune diseases such as rheumatoid arthritis (RA). Earlier investigations have highlighted the importance of TLR2 and TLR4 function in RA pathogenesis. In this review, we discuss the newer data that indicate roles for TLR5 and TLR7 in RA and its preclinical models. We evaluate the pathogenicity of TLRs in RA myeloid cells, synovial tissue fibroblasts, T cells, osteoclast progenitor cells and endothelial cells. These observations establish that ligation of TLRs can transform RA myeloid cells into M1 macrophages and that the inflammatory factors secreted from M1 and RA synovial tissue fibroblasts participate in TH-17 cell development. From the investigations conducted in RA preclinical models, we conclude that TLR-mediated inflammation can result in osteoclastic bone erosion by interconnecting the myeloid and TH-17 cell response to joint vascularization. In light of emerging unique aspects of TLR function, we summarize the novel approaches that are being tested to impair TLR activation in RA patients.

Peripheral blood T helper type 17 frequency shows an inverse correlation with disease activity and magnetic resonance imaging-based osteitis and erosions in disease-modifying anti-rheumatic drug- and steroid-naive established rheumatoid arthritis

An increased expansion of T helper type 17 (Th17) cells in the synovium has been shown to play a key role in cartilage and bone destruction in rheumatoid arthritis (RA). Because the correlation of the peripheral blood helper T cell subsets and various inflammatory cytokines with the magnetic resonance imaging (MRI)-based parameters have not been studied adequately to date, we sought to look for the same in this study. RA patients with disease duration less than 36 months, disease-modifying anti-rheumatic drugs (DMARDs) and steroid-naive, were recruited. MRI of the dominant hand and wrist was performed using a 0·2 Tesla MRI machine. Peripheral blood Th1 and Th17 were enumerated by flow cytometry and serum interleukin (IL)-6 and IL-17 by enzyme-linked immunosorbent assay (ELISA). Forty consecutive seropositive RA patients [33 females, mean disease duration 12·2 months, mean disease activity score (DAS)28 = 4·4] were included. MRI revealed erosions in 80% of these subjects. On subgroup analysis, prevalence of erosions (94 versus 68%) as well as mean erosion score (11·5 ± 18·9 versus 3·5 ± 6·0) were significantly higher in established RA (13-36 months' duration) compared to early RA (0-12 months). The median peripheral blood Th17 frequencies were significantly higher in patients (1·4%) compared to healthy controls (0·7%) and had a strong negative correlation with MRI parameters of erosion and osteitis as well as with DAS28 in the established RA subgroup. The frequency of peripheral blood Th17 subset was significantly expanded in established RA which correlated inversely with disease activity as well as MRI based erosions and osteitis.

Interleukin-22 serum levels are elevated in active scleritis

PURPOSE

To evaluate serum cytokine profile from patients with active scleritis in a two-centre prospective case-control study.

METHODS

The serum of 20 active scleritis patients not treated with any local, periocular, or systemic immunomodulatory therapy (IMT) was analysed with multiplex assay to determine the levels of 11 cytokines interleukin (IL)-1β, IL-6, IL-2, IFN-γ, IL-10, IL-12p40, IL-13, IL-17A, IL-5, TNF-α, and TNF-β, and with ELISA to determine the levels of TGF-β1, IL-22, and IL-23. Twenty-five age-matched healthy volunteers were used as controls. In a subgroup of 13 patients with active disease, a second serum sample was obtained when the disease was inactive and levels of IL-22 were determined. Serum IL-22 levels from patients with active scleritis were correlated with type of scleritis (non-necrotizing and necrotizing), degree of inflammation (0-4+ :≤2+ and >2+), and associated systemic disease.

RESULTS

Serum levels of IL-22 were elevated in active scleritis patients compared to controls (6.41 ± 1.52 pg/ml versus 1.93 ± 0.39 pg/ml, p = 0.012) and significantly decreased after scleritis remission with the use of IMT (p = 0.005). There was no statistical association with scleritis type, degree of inflammation, or associated systemic disease. The serum levels of other cytokines were not significantly different from controls.

CONCLUSION

In our study cohort, IL-22 serum levels were significantly elevated in active scleritis patients compared to controls and decreased significantly after remission. Our results suggest that IL-22, a T helper (Th) 17- and Th22- derived cytokine, may play a critical role in the physiopathology of scleritis.

Combined Expression of IFN-γ, IL-17, and IL-4 mRNA by Recall PBMCs Moderately Discriminates Active Tuberculosis from Latent Mycobacterium tuberculosis Infection in Patients with Miscellaneous Inflammatory Underlying Conditions

New biomarkers are needed for discriminating active tuberculosis (TB) from latent TB infection (LTBI), especially in vulnerable groups representing the major diagnostic challenge. This pilot study was carried out to explore the diagnostic potential of selected genes, IFN-γ, IL-17, IL-4, and FoxP3, associated with TB immunity and immunopathology. IFN-γ, IL-17, IL-4, and FoxP3 mRNA expression levels were measured by quantitative reverse transcription PCR (RT-qPCR) from antigen-stimulated peripheral blood mononuclear cells of patients with active TB (n = 25); patients with miscellaneous inflammatory disorders and concomitant LTBI (n = 20), rheumatoid arthritis (RA) being the most predominant in the group (n = 11); and in healthy Bacillus Calmette–Guérin (BCG) vaccinees (n = 8). While the levels of FoxP3 mRNA did not differ between the tested groups, the cumulative expression levels of purified protein derivative-stimulated IFN-γ, IL-17, and IL-4 mRNAs were found to distinguish active TB from the whole group of LTBI with 48% sensitivity and 85% specificity. When restricting the LTBI group to RA cases only, the sensitivity was 56% and specificity 100%. When interpreting the result as positive in at least one of the mRNAs IFN-γ, IL-17, or IL-4, sensitivity of 64% and specificities of 75% (heterogeneous group of LTBI) or 100% (LTBI with RA) were achieved. Moderate discrimination of active TB from LTBI with miscellaneous inflammatory underlying conditions by using combined quantitative expression of IFN-γ, IL-17, and IL-4 mRNA seems not to be of high diagnostic potential.

Targeting CD1c-expressing classical dendritic cells to prevent thymus and activation-regulated chemokine (TARC)-mediated T-cell chemotaxis in rheumatoid arthritis

OBJECTIVES

Thymus and activation-regulated chemokine (TARC) attracts cells that express the C-C chemokine receptor type 4 (CCR4), including CD4 T cells. As expression of CCR4 is increased on peripheral T cells and intra-articular interleukin (IL)-17-producing cells in patients with rheumatoid arthritis (RA), we investigated whether TARC plays a role in the attraction of T cells to the synovial compartment. In addition, we assessed the role of classical dendritic cells (cDCs) in the production of TARC in RA.

METHOD

TARC was measured in synovial fluid (SF) samples from RA and osteoarthritis (OA) patients. Spontaneous and thymic stromal lymphopoietin (TSLP)-induced TARC production by mononuclear cells (MCs) and CD1c cDCs from peripheral blood (PB) and SF was assessed. The role of TARC in CD4 T-cell migration towards cDCs was assessed and the contribution of CD1c-expressing cells to TARC production was studied.

RESULTS

TARC concentrations were higher in SF of RA patients compared to OA patients. MCs from SF produced TARC spontaneously and produced more TARC upon stimulation than paired PBMCs. Blocking TARC strongly inhibited CD4 T-cell chemotaxis by TSLP-stimulated cDCs, associated with decreased production of tumour necrosis factor (TNF)-α. Depletion of cDCs from SFMCs strongly reduced TARC production.

CONCLUSIONS

TARC levels are increased in RA SF and our data indicate that this results from production by SFMCs and in particular CD1c cDCs. TARC attracts T cells and TARC secretion by MCs is crucially dependent on the presence of CD1c cDCs. Considering the potential of SF cDCs to activate T cells and induce pro-inflammatory cytokine secretion, targeting intra-articular cDCs constitutes a novel therapeutic approach in RA.

Changes in the pattern of cytokine production from peripheral blood mononuclear cells in patients with rheumatoid arthritis treated with infliximab and their relation to plasma arginase activity

AIM

The aim of this study was to quantify the production of T-cell cytokines from the peripheral blood mononuclear cells (PBMCs) of RA patients before and after treatment with anti-tumor necrosis factor (TNF)-α infliximab (IFX).

METHOD

We stimulated the PBMCs of RA patients (n = 24) in vitro and quantified the cytokines in the culture supernatant using enzyme-linked immunosorbent assay.

RESULTS

Unexpectedly, the cytokines tested, interferon (IFN)-γ, interleukin (IL)-4 and IL-17, were all found to have increased, rather than decreased, after the treatment. When the patients were divided into two groups according to the plasma activity of arginase, which is implicated in the immune-suppressive function of myeloid-derived suppressor cells, the substantial increase in the cytokine production ex vivo was only detected in the group in which the arginase activity was decreased after the treatment with IFX. In fact, although the ex vivo production of IL-21 increased along with the other cytokines, the plasma concentration of IL-21 decreased significantly after IFX treatment.

CONCLUSION

It is important to exercise caution in interpreting ex vivo cytokine production data, in that they can be negatively influenced by the immune-suppressive mechanisms that prevent excessive inflammation. Thus, to analyze the T-cell response accurately, T-cell markers that are detectable in the serum or plasma need to be discovered. The concentrations of IFN-γ, IL-4 and IL-17 were all below detection limits, but that of IL-21 was detectable in the plasma and inversely correlated with the production of IL-21 ex vivo. This may indicate the involvement of Th17 response in the pathogenesis of RA.

Ratio of Circulating IFNγ (+) "Th17 Cells" in Memory Th Cells Is Inversely Correlated with the Titer of Anti-CCP Antibodies in Early-Onset Rheumatoid Arthritis Patients Based on Flow Cytometry Methods of the Human Immunology Project

Rheumatoid arthritis (RA) is a systemic autoimmune disease with chronic joint inflammation characterized by activated T cells. IL-17 and Th17 cells play important roles in the pathogenesis of RA. Recently, plasticity in helper T cells has been demonstrated; Th17 cells can convert to Th1 cells. However, it remains to be elucidated whether this conversion occurs in the early phase of RA. Here, we validated the methods of the Human Immunology Project using only the cell-surface marker through measuring the actual expression of IL-17 and IFNγ. We also evaluated the expression of CD161 in human Th17 cells. We then tried to identify Th17 cells, IL-17⁺Th17 cells, and IFNγ⁺Th17 cells in the peripheral blood of early-onset RA patients using the standardized method of the Human Immunology Project. Our findings validated the method and the expression of CD161. The ratio of IFNγ⁺Th17 cells in memory T cells was inversely correlated to the titers of anti-CCP antibodies in the early-onset RA patients. These findings suggest that Th17 cells play important roles in the early phase of RA and that anti-IL-17 antibodies should be administered to patients with early phase RA, especially those with high titers of CCP antibodies.

Selective Inhibition of Membrane Type 1 Matrix Metalloproteinase Abrogates Progression of Experimental Inflammatory Arthritis: Synergy With Tumor Necrosis Factor Blockade

OBJECTIVE

In rheumatoid arthritis (RA), destruction of articular cartilage by the inflamed synovium is considered to be driven by increased activities of proteolytic enzymes, including matrix metalloproteinases (MMPs). The purpose of this study was to investigate the therapeutic potential of selective inhibition of membrane type 1 MMP (MT1-MMP) and its combination with tumor necrosis factor (TNF) blockage in mice with collagen-induced arthritis (CIA).

METHODS

CIA was induced in DBA/1 mice by immunization with bovine type II collagen. From the onset of clinical arthritis, mice were treated with MT1-MMP selective inhibitory antibody DX-2400 and/or TNFR-Fc fusion protein. Disease progression was monitored daily, and serum, lymph nodes, and affected paws were collected at the end of the study for cytokine and histologic analyses. For in vitro analysis, bone marrow-derived macrophages were stimulated with lipopolysaccharide for 24 hours in the presence of DX-2400 and/or TNFR-Fc to analyze cytokine production and phenotype.

RESULTS

DX-2400 treatment significantly reduced cartilage degradation and disease progression in mice with CIA. Importantly, when combined with TNF blockade, DX-2400 acted synergistically, inducing long-term benefit. DX-2400 also inhibited the up-regulation of interleukin-12 (IL-12)/IL-23 p40 via polarization toward an M2 phenotype in bone marrow-derived macrophages. Increased production of IL-17 induced by anti-TNF, which correlated with an incomplete response to anti-TNF, was abrogated by combined treatment with DX-2400 in CIA.

CONCLUSION

Targeting MT1-MMP provides a potential strategy for joint protection, and its combination with TNF blockade may be particularly beneficial in RA patients with an inadequate response to anti-TNF therapy.

The role of the Th17 cytokines IL-17 and IL-22 in Rheumatoid Arthritis pathogenesis and developments in cytokine immunotherapy

Over the past few years, the importance of Interleukin (IL)-17 and T helper (Th)17 cells in the pathology of Rheumatoid Arthritis (RA) has become apparent. RA is a systemic autoimmune disease that affects up to 1% of the population worldwide. It is characterized by an inflamed, hyperplastic synovium with pannus formation, leading to bone and cartilage destruction in the joints. By the production of effector cytokines like IL-17 and IL-22, the T helper 17 subset protects the host against bacterial and fungal infections, but it can also promote the development of various autoimmune diseases like RA. Hence, the Th17 pathway recently became a very interesting target in RA treatment. Up to now, several therapies targeting the Th17 cells or its effector cytokines have been tested, or are currently under investigation. This review clarifies the role of Th17 cells and its cytokines in the pathogenesis of RA, and provides an overview of the clinical trials using immunotherapy to target this particular T helper subset or the two main effector cytokines by which the Th17 cells exert their function, IL-17 and IL-22.

Anti-tumour necrosis factor treatment increases circulating T helper type 17 cells similarly in different types of inflammatory arthritis

We investigated changes in circulating T helper type 17 (Th17) cells following anti-tumour necrosis factor (TNF) in rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA) patients. Peripheral blood mononuclear cells (PBMC) were isolated from 25 RA, 15 AS and eight PsA patients at baseline 4 and 12 weeks after treatment, and Th17 cell frequencies were analysed using interleukin (IL)-17 enzyme-linked immunospot (ELISPOT) and flow cytometry. A significant increase in IL-17-producing cells was observed by ELISPOT in RA and AS patients at 12 weeks. Flow cytometry confirmed significant increases in CD4(+) IL-17(+) cells at 12 weeks in RA and AS and 4 weeks in PsA patients. Anti-TNF treatment increases circulating Th17 cells in three different diseases.

CXCL8 and CCL20 Enhance Osteoclastogenesis via Modulation of Cytokine Production by Human Primary Osteoblasts

Generalized osteoporosis is common in patients with inflammatory diseases, possibly because of circulating inflammatory factors that affect osteoblast and osteoclast formation and activity. Serum levels of the inflammatory factors CXCL8 and CCL20 are elevated in rheumatoid arthritis, but whether these factors affect bone metabolism is unknown. We hypothesized that CXCL8 and CCL20 decrease osteoblast proliferation and differentiation, and enhance osteoblast-mediated osteoclast formation and activity. Human primary osteoblasts were cultured with or without CXCL8 (2–200 pg/ml) or CCL20 (5–500 pg/ml) for 14 days. Osteoblast proliferation and gene expression of matrix proteins and cytokines were analyzed. Osteoclast precursors were cultured with CXCL8 (200 pg/ml) and CCL20 (500 pg/ml), or with conditioned medium (CM) from CXCL8 and CCL20-treated osteoblasts with or without IL-6 inhibitor. After 3 weeks osteoclast formation and activity were determined. CXCL8 (200 pg/ml) and CCL20 (500 pg/ml) enhanced mRNA expression of KI67 (2.5–2.7-fold), ALP (1.6–1.7-fold), and IL-6 protein production (1.3–1.6-fold) by osteoblasts. CXCL8-CM enhanced the number of osteoclasts with 3–5 nuclei (1.7-fold), and with >5 nuclei (3-fold). CCL20-CM enhanced the number of osteoclasts with 3–5 nuclei (1.3-fold), and with >5 nuclei (2.8-fold). IL-6 inhibition reduced the stimulatory effect of CXCL8-CM and CCL20-CM on formation of osteoclasts. In conclusion, CXCL8 and CCL20 did not decrease osteoblast proliferation or gene expression of matrix proteins. CXCL8 and CCL20 did not directly affect osteoclastogenesis. However, CXCL8 and CCL20 enhanced osteoblast-mediated osteoclastogenesis, partly via IL-6 production, suggesting that CXCL8 and CCL20 may contribute to osteoporosis in rheumatoid arthritis by affecting bone cell communication.

The IL-23-IL-17 axis in inflammatory arthritis

The discovery that the IL-23-IL-17 immune pathway is involved in many models of autoimmune disease has changed the concept of the role of T-helper cell subsets in the development of autoimmunity. In addition to TH17 cells, IL-17 is also produced by other T cell subsets and innate immune cells; which of these IL-17-producing cells have a role in tissue inflammation, and the timing, location and nature of their role(s), is incompletely understood. The current view is that innate and adaptive immune cells expressing the IL-23 receptor become pathogenic after exposure to IL-23, but further investigation into the role of IL-23 and IL-17 at different stages in the development and progression of chronic (destructive) inflammatory diseases is needed. Rheumatoid arthritis (RA) and spondyloarthritis (SpA) are the two most common forms of chronic immune-mediated inflammatory arthritis, and the IL-23-IL-17 axis is thought to have a critical role in both. This Review discusses the basic mechanisms of these cytokines in RA and SpA on the basis of findings from disease-specific animal models as well as human ex vivo studies. Promising therapeutic applications to modulate this immune pathway are in development or have already been approved. Blockade of IL-17 and/or TH17-cell activity in combination with anti-TNF therapy might be a successful approach to achieving stable remission or even prevention of chronic immune-mediated inflammatory diseases.

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.

Specific therapy to regulate inflammation in rheumatoid arthritis: molecular aspects

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which persistent inflammation of synovial tissue results in a progressive functional decline of the joint and premature mortality. TNF inhibitors were the first biological disease-modifying antirheumatic drugs (DMARDs) used to treat RA. Since then, new biological drugs have emerged, such as inhibitors of IL-1, IL-6 and others, with different mechanisms of action that include the depletion of B cells and the inhibition of T-cell costimulation. Recently, RA treatments have incorporated the use of synthetic DMARDs. This review describes the molecular aspects of the mechanisms of action of biological and synthetic DMARDs, discusses the adverse effects and limitations of established therapies and analyses the alternative approaches to RA treatment.

TNFα promotes Th17 cell differentiation through IL-6 and IL-1β produced by monocytes in rheumatoid arthritis

TNFα plays an important role in autoimmune pathogenesis and is the main therapeutic target of rheumatoid arthritis. However, its underlying mechanism is not completely understood. In this study, we described that Th17 cells were accumulated in synovial fluid, which was attributable to TNFα aberrantly produced in rheumatoid synovium. Interestingly, TNFα cannot induce IL-17 production of CD4⁺ T cells directly, but through the monocytes high levels of IL-1β and IL-6 in a TNFRI and TNFRII dependent manner from the active RA patients are produced. TNFα was shown to enhance the phosphorylation level of STAT3 and the expression level of transcription factor RORC of CD4⁺ T cells when cultured with CD14⁺ monocytes. Treatment with an approved TNFα blocking antibody showed marked reduction in the levels of IL-6, IL-1β, and IL-17 and the expression level of STAT3 phosphorylation in relation to Th17 cell differentiation in patients with rheumatoid arthritis. The study provides new evidence supporting the critical role of TNFα in the pathogenic Th17 cell differentiation in rheumatoid arthritis.

Th17 and non-classic Th1 cells in chronic inflammatory disorders: two sides of the same coin

Th17 lymphocytes, beyond their protective role in the clearance of extracellular pathogens, also play a role in the pathogenesis of several autoimmune and inflammatory diseases, such as multiple sclerosis, rheumatoid arthritis, inflammatory bowel diseases, psoriasis and contact dermatitis. Nevertheless, they are very rare at inflammatory sites in comparison with other T cell subsets. Recently, this rarity has been explained by the finding that Th17 cells rapidly shift into the Th1 phenotype in the presence of IL-12 and/or TNF-α as well as by the fact that they possess self-regulatory mechanisms limiting their own expansion. Th17 lymphocytes that have shifted towards a Th1 phenotype seem to be particularly aggressive and more pathogenic than the Th17 unshifted cells. As a consequence, the Th17-derived Th1 cells, named non-classic Th1 cells, can become a possible target for the therapy of some inflammatory disorders. In particular, convincing evidence has recently been accumulated indicating that this subset can play a role in Crohn's disease and juvenile idiopathic arthritis. More importantly, it has been shown that TNF-α inhibitors, which are used for the treatment of such diseases, appear to be able to inhibit the transition of Th17 lymphocytes to the non-classic Th1 phenotype, and thus they possibly help to dampen inflammation and arrest disease progression. Based on this context, the definition of the soluble factors involved in the shifting from Th17 towards non-classic Th1 subset as well as the comprehension of their respective pathogenic role in human inflammatory disorders would be of great help for developing novel therapeutic strategies.

The Th17 pathway as a therapeutic target in rheumatoid arthritis and other autoimmune and inflammatory disorders

Production of the pro-inflammatory cytokine interleukin (IL)-17 by Th17 cells and other cells of the immune system protects the host against bacterial and fungal infections, but also promotes the development of rheumatoid arthritis (RA) and other autoimmune and inflammatory disorders. Several biologicals targeting IL-17, the IL-17 receptor, or IL-17-related pathways are being tested in clinical trials, and might ultimately lead to better treatment for patients suffering from various IL-17-mediated disorders. In this review, we provide a clear overview of current knowledge on Th17 cell regulation and the main Th17 effector cytokines in relation to IL-17-mediated conditions, as well as on recent IL-17-related drug developments. We demonstrate that targeting the Th17 pathway is a promising treatment for rheumatoid arthritis and various other autoimmune and inflammatory diseases. However, improvements in technical developments assisting in the identification of patients suffering from IL-17-driven disease are needed to enable the application of tailor-made, personalized medicine.