The expression of IL-20 and IL-24 and their shared receptors are increased in rheumatoid arthritis and spondyloarthropathy

Immunoregulatory Pathways Involved in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) include ulcerative colitis and Crohn's disease. The immune response in ulcerative colitis is different from the Crohn's disease. Accumulating evidence suggests that IBD results from an inappropriate inflammatory response to intestinal microbes in a genetically susceptible host. Several immunoregulatory abnormalities have been reported in patients with IBD, including the ratio of proinflammatory (tumor necrosis factor alpha, IL-6, IL-1-β) to immunoregulatory cytokines (IL-10, TGF-β, IL-35) and selective activation of T-helper (Th) lymphocyte subsets (Th1, Th2, Th9, Th17, and regulatory T cells). The purpose of this review is to show the immunoregulatory pathways (regulatory cells and cytokines) involved in IBD published in recent years.

Cytokine detection and simultaneous assessment of rheumatoid factor interference in human serum and synovial fluid using high-sensitivity protein arrays on plasmonic gold chips

Background

Fluorescence-enhancing microarray on plasmonic gold film is an attractive alternative to traditional enzyme-linked immunosorbent assay (ELISA) for cytokine detection because of the increased sensitivity. The assay chemistry is similar to an ELISA sandwich assay, but owing to the gold substrate, cytokine measurements are 10 to 100 times more sensitive and can be multiplexed. Plasmonic protein microarrays are, as other immunoassays, affected by the presence of heterophilic antibodies and rheumatoid factor may lead to analytical errors with serious implications for patient care. Here, we present a plasmonic gold substrate protein microarray for high-sensitivity detection of cytokines with simultaneous assessment of rheumatoid factor interference on a single chip.

Results

Paired serum and synovial fluid samples from patients with rheumatoid arthritis (n = 18), osteoarthritis (n = 9) or healthy controls (n = 10) were arrayed on near-infrared fluorescence enhancing plasmonic gold chips spotted with cytokine-specific capture antibody and isotype control antibody. Possible rheumatoid factor interference was visualised by a non-specific signal from the isotype control antibody, and pre-treatment of samples with heat-aggregated animal IgG eliminated this background contamination. The platform was optimised using the cytokine IL-20. The protein microarray platform allowed for the detection of human IL-20 at levels <1 pg/ml with reliable IL-20 quantification over a 5-log dynamic range. Samples for which rheumatoid factor caused artefacts were identified and a method for eliminating rheumatoid factor interference was developed and validated. IL-20 protein levels were significantly higher in synovial fluid samples from patients with rheumatoid arthritis compared to osteoarthritis (p < 0.001), while serum levels of IL-20 did not differ between patients with rheumatoid arthritis, osteoarthritis or healthy controls.

Conclusion

Using novel plasmonic gold chips, we developed a highly sensitive and accurate assay platform to detect lowly expressed cytokines in biological fluids, allowing for the elimination of rheumatoid factor interference in as little as 5 μl sample volume. The detection limit was below 1 pg/ml for IL-20 and linearity was achieved over a 5-log dynamic range. This technology is highly advantageous for cytokines where sensitivity or sample volume is critical or where assessment of rheumatoid factor interference needs addressed and eliminated.

Efficacy and Safety of Anti-Interleukin-20 Monoclonal Antibody in Patients With Rheumatoid Arthritis: A Randomized Phase IIa Trial

OBJECTIVE

Interleukin-20 (IL-20) is implicated in the pathogenesis of rheumatoid arthritis (RA). The efficacy, safety, and tolerability of NNC0109-0012, a selective anti-IL-20 recombinant human monoclonal antibody (mAb), were assessed in patients with active RA who had an inadequate response to methotrexate therapy.

METHODS

Sixty-seven patients with RA were enrolled and randomized (2:1) to receive NNC0109-0012 (3 mg/kg per week, subcutaneously) or placebo in a phase IIa, double-blind, 12-week trial with a 13-week followup. The primary end point was change in the Disease Activity Score in 28 joints based on C-reactive protein level (DAS28-CRP) from baseline to week 12.

RESULTS

In patients treated with NNC0109-0012, the primary end point, improvement in the DAS28-CRP at week 12, was achieved (estimated difference -0.88; P = 0.02), with significant improvement starting at week 1. A greater response was observed in seropositive patients (estimated difference -1.66; P < 0.001), which was sustained through 13 weeks of followup, whereas no improvement was noted in patients with seronegative RA. A significant proportion of patients with seropositive RA receiving NNC0109-0012, compared to those receiving placebo, achieved treatment responses according to the American College of Rheumatology 20% (ACR20) (59% versus 21%), ACR50 (48% versus 14%), and ACR70 (35% versus 0%) levels of improvement, and showed greater improvements in the Health Assessment Questionnaire disability index (P = 0.047). The most frequent adverse events reported with NNC0109-0012 were injection site reactions and infections (e.g., herpes, nasopharyngitis, respiratory, and urinary). No serious infections or discontinuations associated with NNC0109-0012 were observed.

CONCLUSION

In this phase IIa trial, treatment with NNC0109-0012 (anti-IL-20 mAb) was effective in patients with seropositive RA as early as week 1, with further improvements to week 12. No safety or tolerability concerns were identified with weekly NNC0109-0012 administration.

Interleukin-20 promotes airway remodeling in asthma

Previous studies have demonstrated that interleukin-20 (IL-20) is a pro-inflammatory cytokine, and it has been implicated in psoriasis, lupus nephritis, rheumatoid arthritis, atherosclerosis, and ulcerative colitis. Little is known about the effects of IL-20 in airway remodeling in asthma. The aim of our study was to demonstrate the function of IL-20 in airway remodeling in asthma. To identify the expression of IL-20 and its receptor, IL-20R1/IL-20R2, in the airway epithelium in bronchial tissues, bronchial biopsy specimens were collected from patients and mice with asthma and healthy subjects and stained with specific antibodies. To characterize the effects of IL-20 in asthmatic airway remodeling, we silenced and stimulated IL-20 in cell lines isolated from mice by shRNA and recombinant protein approaches, respectively, and detected the expression of α-SMA and FN-1 by Western blot analysis. First, overexpression of IL-20 and its receptor, IL-20R1/IL-20R2, was detected in the airway epithelium collected from patients and mice with asthma. Second, IL-20 increased the expression of fibronectin-1 and α-SMA, and silencing of IL-20 in mouse lung epithelial (MLE)-12 cells decreased the expression of fibronectin-1 and α-SMA. IL-20 may be a critical cytokine in airway remodeling in asthma. This study indicates that targeting IL-20 and/or its receptors may be a new therapeutic strategy for asthma.

Toll-like receptor 2 and 4 induced interleukin-19 dampens immune reactions and associates inversely with spondyloarthritis disease activity

Spondyloarthritis (SpA) is a group of immune mediated inflammatory diseases affecting joints, gut, skin and entheses. The inflammatory process involves activation of Toll-like receptor (TLR)-2 and TLR-4 and production of cytokines and chemokines such as monocyte chemoattractant protein 1 (CCL2/MCP-1). This proinflammatory chemokine recruits monocytes to sites of inflammation and is central in the development of several immune-mediated inflammatory diseases. Interleukin (IL)-19 is a member of the IL-10 family of cytokines. IL-19-deficient mice are more susceptible to innate-mediated colitis and develop more severe inflammation in response to injury. In this work, we studied inducers of IL-19 production and effect of IL-19 on the production of CCL2/MCP-1 and proinflammatory cytokines in peripheral blood mononuclear cells (PBMCs) from healthy controls (HCs) and in PBMCs and synovial fluid mononuclear cells (SFMCs) from SpA patients. Further, we measured IL-19 in plasma from HCs and in plasma and synovial fluid from SpA patients. Constitutive IL-19 expression was present in both PBMCs and SFMCs and the secretion of IL-19 was increased by TLR-2 and TLR-4 ligands. Neutralizing IL-19 in HC PBMCs and SpA SFMCs resulted in increased production of CCL-2/MCP-1. IL-19 concentrations were decreased in synovial fluid compared with plasma and associated inversely with disease activity in SpA. SpA SFMCs produced less IL-19 in response to LPS compared with HC PBMCs. These findings indicate that IL-19 production is diminished in SpA. Taken together, impaired IL-19 control of the innate immune system might be involved in the pathogenesis of SpA.

Distribution of interleukin-10 family cytokines in serum and synovial fluid of patients with inflammatory arthritis reveals different contribution to systemic and joint inflammation

Evidence exists that interleukin (IL)-10 family cytokines may be involved in the pathogenesis of rheumatoid arthritis (RA). We sought to determine whether or not these cytokines are involved in psoriatic arthritis (PsA). We conducted a prospective study on patients with PsA, RA and osteoarthritis (OA); healthy controls (HC) were also included. We analysed IL-20, IL-24 and IL-19 serum and synovial fluid (SF) levels and change of serum levels following treatment with biological agents. IL-20 serum levels were increased in PsA and RA compared with OA patients and HC and with matched SF levels. IL-24 serum levels in PsA, RA and OA patients were higher than those in HC and also with respect to matched SF in PsA. IL-19 serum levels were higher in HC and OA compared with PsA and RA patients; IL-19 SF levels were higher in PsA and RA compared with OA patients, and in PsA compared with RA patients. PsA and RA patients showed a reduction of IL-19 serum levels after biological treatment. Therefore, IL-19 seems to be involved mainly in the joint inflammation, whereas IL-20 and IL-24 appear to participate mainly in the systemic responses. These findings may further the comprehension of the contribution of these cytokines to the inflammatory response involved in chronic arthritis, as well as to the development of novel therapeutic strategies.

Clinical pharmacokinetics of the anti-interleukin-20 monoclonal antibody NNC0109-0012 in healthy volunteers and patients with psoriasis or rheumatoid arthritis

INTRODUCTION

NNC0109-0012, a novel human monoclonal antibody that binds to and neutralizes the activity of interleukin-20, was investigated as a potential treatment for inflammatory diseases. Pharmacokinetic (PK) modeling was performed using data from four completed clinical phase 1/2 trials to better understand the clinical PK of NNC0109-0012.

METHODS

The populations included were patients with rheumatoid arthritis (RA), chronic plaque psoriasis, and healthy volunteers. NNC0109-0012 was administered subcutaneously at various dose levels (0.01-3 mg/kg) as single dose, once weekly, or multiple doses every second week for up to 12 doses. Noncompartmental methods were used to describe the PK parameters. Population PK was analyzed using nonlinear mixed-effects modeling, with body weight as the main covariate and gender, age, and population as additional covariates.

RESULTS

Across studies (N = 116), mean age and body weight ranged from 38 to 58 years and 72 to 96 kg, respectively. NNC0109-0012 displays linear PK. Time to maximum plasma concentration occurred at approximately 1 week, and the terminal half-life was approximately 3 weeks. Clearance and volume of distribution increased proportionally to body weight. No difference in clearance or volume of distribution was observed between gender or different age groups; however, clearance was slightly lower in healthy volunteers than in patients with RA.

CONCLUSION

The PK profile of NNC0109-0012 is similar to other monoclonal antibodies directed against soluble targets.

The IL-20 subfamily of cytokines--from host defence to tissue homeostasis

The interleukin-20 (IL-20) subfamily of cytokines comprises IL-19, IL-20, IL-22, IL-24 and IL-26. These cytokines are all members of the larger IL-10 family, but have been grouped together to form the IL-20 subfamily based on their usage of common receptor subunits and similarities in their target-cell profiles and biological functions. Members of the IL-20 subfamily facilitate the communication between leukocytes and epithelial cells, thereby enhancing innate defence mechanisms and tissue repair processes at epithelial surfaces. In this Review, we describe the cellular sources and targets of the IL-20 subfamily cytokines, and we detail how their expression is regulated. Much of our understanding of the unique biology of this group of cytokines is still based on IL-22, which is the most studied member of the IL-20 subfamily. Nevertheless, we attempt a broader discussion of the emerging functions of IL-20 subfamily cytokines in host defence, inflammatory diseases, cancer and metabolism.

Aryl hydrocarbon receptor SNP -130 C/T associates with dioxins susceptibility through regulating its receptor activity and downstream effectors including interleukin 24

Dioxins are persistent environmental pollutants that cause multiple adverse health effects in humans, mainly through binding to the ligand-activated transcription factor, aryl hydrocarbon receptor (AhR). Genetic variation in AhR may modulate the susceptibility to dioxins. In this study, we aimed to evaluate the effects of the single nucleotide polymorphism (SNP) -130 C/T in the AhR promoter on dioxin-inducible gene transcription, and to investigate interleukin-24 (IL-24) and interleukin-1β (IL-1β) as proxies for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure. Using primary human chorionic stromal cells, we found that cells with the TT genotype showed higher AhR mRNA and protein levels than did those of the CC genotype. Microarray was carried out to analyze the gene expression profiles of cells (CC and TT genotype) after exposing the cells to TCDD. Several genes associated with human disorders were more highly up-regulated in cells of the TT genotype. Higher up-regulation of IL-24 and IL-1β mRNA in cells with the TT genotype was observed. Furthermore, blood samples from 64 Yusho patients who were accidentally exposed to high concentrations of dioxins were analyzed for the genotype, dioxins concentrations and serum levels of IL-24 and IL-1β. We observed higher serum IL-24 levels and lower serum IL-1β levels in Yusho patients with the TT genotype than in those with the CC genotype. AhR SNP -130 C/T affects serum IL-24 and IL-1β levels, independently of serum dioxins concentrations in Yusho patients. Our observations demonstrate that SNP -130 C/T modulates AhR expression and expression levels of IL-24 and IL-1β, and suggest an association of AhR SNP -130 C/T with the susceptibility to dioxins.

Reduction of IL-20 Expression in Rheumatoid Arthritis by Linear Polarized Infrared Light Irradiation

BACKGROUND

Low-level laser is being evaluated for treating rheumatoid arthritis (RA). Recently, the linear polarized infrared light (Super Lizer, SL) irradiation may also be useful for RA treatment. However, the molecular mechanism underlying the effectiveness of SL on RA is unclear. It has been IL-20 may involved in RA disease progression.

AIM

To understand how SL action, we constructed the experimental model in vitro using human rheumatoid fibroblast-like synoviocyte (MH7A) and collagen induced (CIA) RA rat in vivo. We examined the effect of SL irradiation on IL-20 gene expression in MH7A and IL-20 protein production in CIA) rat joints.

MATERIALS AND METHODS

MH7A was cultured and challenged with IL-1ß, then examined IL-20 and IL-20R mRNA level by DNA microarray. IL-20 protein expression was examined by immunohistochemistry using a specific antibody against rat IL-20.

RESULT

Scatter plot analysis demonstrated that an increase in IL-20 gene expression by IL-1ß was reduced by SL irradiation, but IL-20R did not show a significant change. The Immunohistochemical analysis demonstrated a strong IL-20 staining in synovial membrane tissue of CIA rat joint, and SL irradiation significantly reduced the staining.

DISCUSSION

Since IL-20 has been identified as an important cytokine in the pathogenesis of RA, the reduction of IL-20 expression by SL irradiation may be one of mechanisms in reduction of inflammation in RA joints by SL irradiation suggesting that SL irradiation may be useful for RA therapy.

Cytokine networking of innate immunity cells: a potential target of therapy

Innate immune cells, particularly macrophages and epithelial cells, play a key role in multiple layers of immune responses. Alarmins and pro-inflammatory cytokines from the IL (interleukin)-1 and TNF (tumour necrosis factor) families initiate the cascade of events by inducing chemokine release from bystander cells and by the up-regulation of adhesion molecules required for transendothelial trafficking of immune cells. Furthermore, innate cytokines produced by dendritic cells, macrophages, epithelial cells and innate lymphoid cells seem to play a critical role in polarization of helper T-cell cytokine profiles into specific subsets of Th1/Th2/Th17 effector cells or regulatory T-cells. Lastly, the innate immune system down-regulates effector mechanisms and restores homoeostasis in injured tissue via cytokines from the IL-10 and TGF (transforming growth factor) families mainly released from macrophages, preferentially the M2 subset, which have a capacity to induce regulatory T-cells, inhibit the production of pro-inflammatory cytokines and induce healing of the tissue by regulating extracellular matrix protein deposition and angiogenesis. Cytokines produced by innate immune cells represent an attractive target for therapeutic intervention, and multiple molecules are currently being tested clinically in patients with inflammatory bowel disease, rheumatoid arthritis, systemic diseases, autoinflammatory syndromes, fibrosing processes or malignancies. In addition to the already widely used blockers of TNFα and the tested inhibitors of IL-1 and IL-6, multiple therapeutic molecules are currently in clinical trials targeting TNF-related molecules [APRIL (a proliferation-inducing ligand) and BAFF (B-cell-activating factor belonging to the TNF family)], chemokine receptors, IL-17, TGFβ and other cytokines.

Therapeutic opportunities of the IL-22-IL-22R1 system

Interleukin-22 (IL-22) is a key effector molecule that is produced by activated T cells, including T helper 22 (TH22) cells, TH17 cells and TH1 cells, as well as subsets of innate lymphoid cells. Although IL-22 can act synergistically with IL-17 or tumour necrosis factor, some important functions of IL-22 are unique to this cytokine. Data obtained over the past few years indicate that the IL-22-IL-22 receptor subunit 1 (IL-22R1) system has a high potential clinical relevance in psoriasis, ulcerative colitis, graft-versus-host disease, certain infections and tumours, as well as in liver and pancreas damage. This Review highlights current knowledge of the biology of the IL-22-IL-22R1 system, its role in inflammation, tissue protection, regeneration and antimicrobial defence, as well as the positive and potentially negative consequences of its therapeutic modulation.

MDA-7/IL-24: multifunctional cancer killing cytokine

First identified almost two decades ago as a novel gene differentially expressed in human melanoma cells induced to terminally differentiate, MDA-7/IL-24 has since shown great potential as an anti-cancer gene. MDA-7/IL24, a secreted protein of the IL-10 family, functions as a cytokine at normal physiological levels and is expressed in tissues of the immune system. At supra-physiological levels, MDA-7/IL-24 plays a prominent role in inhibiting tumor growth, invasion, metastasis and angiogenesis and was recently shown to target tumor stem/initiating cells for death. Much of the attention focused on MDA-7/IL-24 originated from the fact that it can selectively induce cell death in cancer cells without affecting normal cells. Thus, this gene originally shown to be associated with melanoma cell differentiation has now proven to be a multi-functional protein affecting a broad array of cancers. Moreover, MDA-7/IL-24 has proven efficacious in a Phase I/II clinical trial in humans with multiple advanced cancers. As research in the field progresses, we will unravel more of the functions of MDA-7/IL-24 and define novel ways to utilize MDA-7/IL-24 in the treatment of cancer.

Emerging cell and cytokine targets in rheumatoid arthritis

Despite major progress in the treatment of rheumatoid arthritis (RA), strong unmet medical need remains, as only a minor proportion of patients reach sustained clinical remission. New approaches are therefore necessary, and include manipulation of regulatory T cells, which might be able to restore the disturbed immune system and could even lead to a cure if this restored regulation were to prove sustainable. Logistical and conceptual problems, however, beset this attractive therapeutic approach, including difficulties with ex vivo expansion of cells, specificity of targeting and the optimal time point of administration. Therefore, alternative avenues are being investigated, such as targeting B-cell effector functions and newly identified proinflammatory cytokines. On the basis of success with B-cell depleting therapy using anti-CD20 agents, further treatment modalities are now exploring direct or indirect interference in B-cell-mediated immunity with the use of agents directed against other B-cell surface molecules. Novel approaches target intracellular B-cell signalling and regulatory B cells. New cytokine-directed therapies target important proinflammatory mediators such as GM-CSF, new members of the IL-1 family, IL-6 and its receptor, IL-17, IL-20, IL-21, IL-23 as well as synovium-specific targets. This article reviews these emerging cell and cytokine targets with special focus on biologic agents, some of which might reach the clinic soon whereas others will require considerable time in development. Nevertheless, these exciting new approaches will considerably enhance our repertoire in the battle against this potentially devastating disease.

Signaling via the IL-20 receptor inhibits cutaneous production of IL-1β and IL-17A to promote infection with methicillin-resistant Staphylococcus aureus

Staphylococcus aureus causes most infections of human skin and soft tissue and is a major infectious cause of mortality. Host defense mechanisms against S. aureus are incompletely understood. Interleukin 19 (IL-19), IL-20 and IL-24 signal through type I and type II IL-20 receptors and are associated with inflammatory skin diseases such as psoriasis and atopic dermatitis. We found here that those cytokines promoted cutaneous infection with S. aureus in mice by downregulating IL-1β- and IL-17A-dependent pathways. We noted similar effects of those cytokines in human keratinocytes after exposure to S. aureus, and antibody blockade of the IL-20 receptor improved outcomes in infected mice. Our findings identify an immunosuppressive role for IL-19, IL-20 and IL-24 during infection that could be therapeutically targeted to alter susceptibility to infection.

A simple set of validation steps identifies and removes false results in a sandwich enzyme-linked immunosorbent assay caused by anti-animal IgG antibodies in plasma from arthritis patients

Rheumatoid arthritis (RA) and spondyloarthritis (SpA) are chronic diseases characterized by activation of the immune system and production of antibodies. Thus, rheumatoid factor, anti-animal IgG antibodies and heterophilic antibodies in plasma samples from arthritis patients can interfere with immunoassays such as sandwich enzyme-linked immunosorbent assay (ELISA) systems often used in arthritis research. However, standard methodologies on how to test for false results caused by these antibodies are lacking. The objective of this study was to design a simple set of steps to validate a sandwich ELISA before using it for measuring analytes in plasma from arthritis patients. An interleukin-24 (IL-24) sandwich ELISA system was prepared with a monoclonal mouse capture antibody and a polyclonal goat detection antibody and tested for interference by rheumatoid factor, anti-animal IgG antibodies and heterophilic antibodies. Plasma samples from 23 patients with RA and SpA were used. No differences were found between plasma samples measured in wells coated with anti-IL-24 specific antibody and in wells coated with isotype control antibody (false positive results), and recombinant human IL-24 was not recovered in spiked samples (false negative results). This interference was removed after preincubating the plasma samples from patients with arthritis with goat or bovine IgG, suggesting that anti-animal IgG antibodies found in the plasma of the arthritis patients caused the false results. Additional testing showed that the signal-to-noise ratio could be increased by titration of the capture and detection antibodies and by using the ELAST amplification system. Finally, the calculated concentration of IL-24 was increased in ethylenediaminetetraacetic acid (EDTA) plasma compared to heparin plasma and serum and decreased with repetitive freeze/thaw cycles of the samples illustrating how sample handling could additionally contribute to the variations reported by different laboratories in measurement of the same analyte. This study proposes a simple set of validation steps to evaluate and optimize a sandwich ELISA before using it for measuring analytes in plasma from arthritis patients. Anti-animal IgG antibodies are also present in healthy individuals, suggesting that validation of ELISA systems for measuring non-arthritis samples could also be improved by this simple set of validation steps.

A polymorphism of interleukin-22 receptor alpha-1 is associated with the development of childhood IgA nephropathy

Recent studies suggest that dysregulated innate immunity plays an important role in the pathogenesis of immunoglobulin A nephropathy (IgAN). The interleukin-20 subfamily and its receptor, interleukin-22 receptor alpha-1 (IL-22R1), were recently identified as immunomodulators in human diseases, acting as mediators of mucosal host defense. However, the potential role of IL-22R1 in the pathogenesis of IgAN has not been explored. In the current study, 194 patients with IgAN and 287 normal controls were genotyped for coding polymorphisms of the IL-22R1 gene and the association between the polymorphisms and IgAN was investigated. Local expression of IL-22R1 was examined in patients with IgAN and healthy controls using immunohistochemistry. Our case-control analysis showed that genotypes of rs3795299 were associated with childhood IgAN. Individuals with the CC genotype of rs3795299 had about 3-fold reduced risk of IgAN compared with those with the GG genotype in the codominant model (P=0.0028) and those with the genotypes containing the G allele (GG or GC) in the recessive model (P=0.002). After Bonferroni correction, the association between the rs3795299 CC genotype and reduced risk of developing IgAN remained significant. Furthermore, the renal expression of IL-22R1 was significantly higher in healthy controls compared with subjects with IgAN. Our data suggest that the CC genotype of rs3795299 polymorphism in the IL-22R1 gene is associated with the reduced risk of IgAN, and this genetic association was supported by the higher renal expression of IL-22R1 in healthy controls compared with patients with IgAN.

IL-10-- and IL-20--expressing epithelial and inflammatory cells are increased in patients with ulcerative colitis

Interleukin (IL)-20, a pro-inflammatory cytokine, is a recently discovered member of the IL-10 family. This cytokine has been described in inflammatory diseases such as psoriasis and asthma. However, IL-20 expression in ulcerative colitis (UC) patients has not been yet described. The aim of this study was to evaluate IL-20 and IL-10 gene and protein expression and their receptors in the mucosa from UC patients. Forty UC patients and 18 non-inflamed controls were studied. IL-10, IL-20, IL-10R1, IL-10R2, IL-20R1 and IL-20R2 gene expression was determined by real time RT-PCR in colonic biopsies. Protein expression was evaluated by immunohistochemistry. Patients in remission had significantly higher IL-10 gene expression in mucosa compared with active patients and controls. Conversely, IL-10R1/B gene expression was decreased in remission compared with active UC patients and controls. IL-20 gene expression was lower in colonic mucosa from UC patients in remission compared with controls and active patients. IL-20R1/B mRNA expression was higher in remission compared with active UC patients and controls. IHQ analysis showed an increased IL-10-, IL-20-, and IL-20R2-producing cells in active UC patients. IL-10-, IL-20- and IL-20R2-expressing epithelial and inflammatory cells were increased in active UC patients, meanwhile IL-20R1 was up-regulated only on inflammatory infiltrates vs. controls. This is the first depiction of the presence of IL-20 and its receptors in UC. Much remains to be learned however, about the pathogenic mechanisms that lead to IBD. This cytokine/receptor imbalance may be implicated in the pathogenesis of UC.

Synovial inflammation, immune cells and their cytokines in osteoarthritis: a review

OBJECTIVE

Although osteoarthritis (OA) is considered a non-inflammatory condition, it is widely accepted that synovial inflammation is a feature of OA. However, the role of immune cells and their cytokines in OA is largely unknown. This narrative systematic review summarizes the knowledge of inflammatory properties, immune cells and their cytokines in synovial tissues (STs) of OA patients.

DESIGN

Broad literature search in different databases was performed which resulted in 100 articles.

RESULTS

Of 100 articles 33 solely investigated inflammation in OA ST with or without comparison with normal samples; the remaining primarily focussed on rheumatoid arthritis (RA) ST. Studies investigating different severity stages or cellular source of cytokines were sparse. OA ST displayed mild/moderate grade inflammation when investigated by means of haematoxylin and eosin (H&E) staining. Most frequently found cells types were macrophages, T cells and mast cells (MCs). Overall the number of cells was lower than in RA, although the number of MCs was as high as or sometimes even higher than in RA ST. Cytokines related to T cell or macrophage function were found in OA ST. Their expression was overall higher than in normal ST, but lower than in RA ST. Their cellular source remains largely unknown in OA ST.

CONCLUSION

Inflammation is common in OA ST and characterized by immune cell infiltration and cytokine secretion. This inflammation seems quantitatively and qualitatively different from inflammation in RA. Further research is needed to clarify the role of inflammation, immune cells and their cytokines in the pathogenesis of OA.

Expression of IL-20 in synovium and lesional skin of patients with psoriatic arthritis: differential response to alefacept treatment

Introduction

Psoriatic arthritis (PsA) is an inflammatory joint disease associated with psoriasis. Alefacept (a lymphocyte function-associated antigen (LFA)-3 Ig fusion protein that binds to CD2 and functions as an antagonist to T-cell activation) has been shown to result in improvement in psoriasis but has limited effectiveness in PsA. Interleukin-20 (IL-20) is a key proinflammatory cytokine involved in the pathogenesis of psoriasis. The effects of alefacept treatment on IL-20 expression in the synovium of patients with psoriasis and PsA are currently unknown.

Methods

Eleven patients with active PsA and chronic plaque psoriasis were treated with alefacept (7.5 mg per week for 12 weeks) in an open-label study. Skin biopsies were taken before and after 1 and 6 weeks, whereas synovial biopsies were obtained before and 4 and 12 weeks after treatment. Synovial biopsies from patients with rheumatoid arthritis (RA) (n = 10) were used as disease controls. Immunohistochemical analysis was performed to detect IL-20 expression, and stained synovial tissue sections were evaluated with digital image analysis. Double staining was performed with IL-20 and CD68 (macrophages), and conversely with CD55 (fibroblast-like synoviocytes, FLSs) to determine the phenotype of IL-20-positive cells in PsA synovium. IL-20 expression in skin sections (n = 6) was analyzed semiquantitatively.

Results

IL-20 was abundantly expressed in both PsA and RA synovial tissues. In inflamed PsA synovium, CD68⁺ macrophages and CD55⁺ FLSs coexpressed IL-20, and its expression correlated with the numbers of FLSs. IL-20 expression in lesional skin of PsA patients decreased significantly (P = 0.04) 6 weeks after treatment and correlated positively with the Psoriasis Area and Severity Index (PASI). IL-20 expression in PsA synovium was not affected by alefacept.

Conclusions

Conceivably, the relatively limited effectiveness of alefacept in PsA patients (compared with anti-tumor necrosis factor (TNF) therapy) might be explained in part by persistent FLS-derived IL-20 expression.

Molecular Mechanisms Governing IL-24 Gene Expression

Interleukin-24 (IL-24) belongs to the IL-10 family of cytokines and is well known for its tumor suppressor activity. This cytokine is released by both immune and nonimmune cells and acts on non-hematopoietic tissues such as skin, lung and reproductive tissues. Apart from its ubiquitous tumor suppressor function, IL-24 is also known to be involved in the immunopathology of autoimmune diseases like psoriasis and rheumatoid arthritis. Although the cellular sources and functions of IL-24 are being increasingly investigated, the molecular mechanisms of IL-24 gene expression at the levels of signal transduction, epigenetics and transcription factor binding are still unclear. Understanding the specific molecular events that regulate the production of IL-24 will help to answer the remaining questions that are important for the design of new strategies of immune intervention involving IL-24. Herein, we briefly review the signaling pathways and transcription factors that facilitate, induce, or repress production of this cytokine along with the cellular sources and functions of IL-24.

Regulation and functions of the IL-10 family of cytokines in inflammation and disease

The IL-10 family of cytokines consists of nine members: IL-10, IL-19, IL-20, IL-22, IL-24, IL-26, and the more distantly related IL-28A, IL-28B, and IL-29. Evolutionarily, IL-10 family cytokines emerged before the adaptive immune response. These cytokines elicit diverse host defense mechanisms, especially from epithelial cells, during various infections. IL-10 family cytokines are essential for maintaining the integrity and homeostasis of tissue epithelial layers. Members of this family can promote innate immune responses from tissue epithelia to limit the damage caused by viral and bacterial infections. These cytokines can also facilitate the tissue-healing process in injuries caused by infection or inflammation. Finally, IL-10 itself can repress proinflammatory responses and limit unnecessary tissue disruptions caused by inflammation. Thus, IL-10 family cytokines have indispensable functions in many infectious and inflammatory diseases.

The expression pattern of two novel cytokines (IL-24 and IL-29) in human fetal membranes

OBJECTIVE

interleukin (IL)-24 and -29 are novel cytokines, produced by immune cells in response to microbial antigens. The functions of these cytokines in the reproductive system are unknown. We examined the expression pattern of IL-24 and IL-29 in human fetal membranes from preterm and term births and in in vitro in response to microbial antigens.

METHODS

fetal membranes collected from cesarean sections at term (normal, not in labor) were placed in culture for 48 h. These membranes were then stimulated with bacterial lipopolysaccharide (LPS) or viral antigen poly-inosinic and cytidylic acid (polyIC) for an additional 24 h. Amniotic fluids (AF) and fetal membranes were also collected from preterm and term deliveries. IL-24 and IL-29 expressions were studied by RT-PCR. ELISA documented culture media and AF cytokine concentrations.

RESULTS

IL-24 and IL-29 expressions were seen in cultured fetal membranes regardless of stimulation. Expressions were also found in preterm and term labor membranes, but not in non-labor tissues at term. IL-24 concentrations were higher after LPS stimulation whereas IL-29 concentrations were higher after polyIC-stimulation. AF analysis did not detect either of the cytokines either preterm or term.

CONCLUSION

this is the first study to report IL-24 and IL-29 expressions in human fetal membranes. Higher concentrations of these cytokines in response to distinct infectious stimuli suggest different pathways for fetal immune response during infection.

Adaptive immune response in osteoclastic bone resorption induced by orally administered Aggregatibacter actinomycetemcomitans in a rat model of periodontal disease

There is mounting evidence that innate and adaptive immunity are critical for periodontal disease-mediated bone resorption. These studies examined the role of B and CD4 T cells in adaptive immunity of rats infected with Aggregatibacter actinomycetemcomitans (Aa). Sprague-Dawley male rats were fed Aa-containing mash or control-mash for 2 weeks. B and CD4 T cells were obtained from draining lymph nodes at 2, 4 and 12 weeks, postinoculation. Quantitative polymerase chain reaction-based messenger RNA expression was conducted for 89 cytokine family genes. Disease-relevance of the differentially expressed genes was assessed using a biological interaction pathway analysis software. B and CD4 T cells of Aa-infected rats increased and were activated, resulting in enhanced isotype-switched serum immunoglobulin G by 2 weeks postinoculation. Bone resorption was evident 12 weeks after Aa-feeding. In B cells, interleukin-2 (IL-2), macrophage-inhibiting factor, IL-19, IL-21, tumor necrosis factor (TNF), CD40 ligand (CD40L), CD70, bone morphogenetic protein 2 (BMP2), BMP3, and BMP10 were upregulated early; while IL-7, Fas ligand (FasL), small inducible cytokine subfamily E1, and growth differentiation factor 11 (GDF11; BMP11) were upregulated late (12 weeks). BMP10 was sustained throughout. In CD4 T cells, IL-10, IL-16, TNF, lymphotoxin-beta (LTbeta), APRIL, CD40L, FasL, RANKL and osteoprotegerin were upregulated early, whereas IL-1beta, IL-1RN, IL-1F8, IL-24, interferon-alpha1, GDF11 (BMP11), and GDF15 were upregulated late (12 weeks). Adaptive immunity appears crucial for bone resorption. Several of the deregulated genes are, for the first time, shown to be associated with bone resorption, and the results indicate that activated B cells produce BMP10. The study provides a rationale for a link between periodontal disease and other systemic diseases.

IL-20: biological functions mediated through two types of receptor complexes

IL-20 was discovered 10 years ago as a new member of the IL-10 family of cytokines. IL-20 shares the highest amino-acid sequence identity with IL-10, IL-24 and IL-19. IL-20 is secreted by immune cells and activated epithelial cells like keratinocytes. A high expression of the corresponding IL-20 receptor chains is detected on epithelial cells. In terms of function, IL-20 might therefore mediate a crosstalk between epithelial cells and tissue-infiltrating immune cells under inflammatory conditions. Transgenic and knockout mouse models for some cytokines and receptors of the IL-10-type cytokines have provided new insights into the biology of this family. This review will focus on the biological functions of IL-20 and its receptors within the IL-10 cytokine network.

IL-10 family of cytokines

In 2001, six immune mediators (IL-10, IL-19, IL-20, IL-22, IL-24, and IL-26) were grouped into the so-called IL-10 family of cytokines based on their similarities with respect to the structure and location of their encoding genes, their primary and secondary protein structures, and the receptor complexes used. Surprisingly, despite all these similarities, IL-10 family members possess different biological functions. The currently known facts regarding the biological effects of these six immune mediators give the impression that at least IL-10, IL-20, and IL-22 play an important role in the pathogenesis of some chronic inflammatory diseases. This review provides an overview of the most important and common aspects of the IL-10 family members.

The p38 MAPK regulates IL-24 expression by stabilization of the 3' UTR of IL-24 mRNA

Background

IL-24 (melanoma differentiation-associated gene-7 (mda-7)), a member of the IL-10 cytokine family, possesses the properties of a classical cytokine as well as tumor suppressor effects. The exact role of IL-24 in the immune system has not been defined but studies have indicated a role for IL-24 in inflammatory conditions such as psoriasis. The tumor suppressor effects of IL-24 include inhibition of angiogenesis, sensitization to chemotherapy, and p38 mitogen-activated protein kinase (MAPK)-mediated apoptosis. Current knowledge on the regulation of IL-24 expression is sparse. Previous studies have suggested that mRNA stabilization is of major importance to IL-24 expression. Yet, the mechanisms responsible for the regulation of IL-24 mRNA stability remain unidentified. As p38 MAPK is known to regulate gene expression by interfering with mRNA degradation we examined the role of p38 MAPK in the regulation of IL-24 gene expression in cultured normal human keratinocytes.

Methodology/Principal Findings

In the present study we show that anisomycin- and IL-1β- induced IL-24 expression is strongly dependent on p38 MAPK activation. Studies of IL-24 mRNA stability in anisomycin-treated keratinocytes reveal that the p38 MAPK inhibitor SB 202190 accelerates IL-24 mRNA decay suggesting p38 MAPK to regulate IL-24 expression by mRNA-stabilizing mechanisms. The insertion of the 3′ untranslated region (UTR) of IL-24 mRNA in a tet-off reporter construct induces degradation of the reporter mRNA. The observed mRNA degradation is markedly reduced when a constitutively active mutant of MAPK kinase 6 (MKK6), which selectively activates p38 MAPK, is co-expressed.

Conclusions/Significance

Taken together, we here report p38 MAPK as a regulator of IL-24 expression and determine interference with destabilization mediated by the 3′ UTR of IL-24 mRNA as mode of action. As discussed in the present work these findings have important implications for our understanding of IL-24 as a tumor suppressor protein as well as an immune modulating cytokine.

Adenovirus-mediated interleukin (IL)-24 immunotherapy for cancer

Interleukin-24 (IL-24) is a member of the IL-10 cytokine family. IL-24, also known as melanoma differentiation associated gene 7 (mda-7), is a unique cytokine in that it has cytokine properties and functions as a novel tumor suppressor gene. Studies by us and other investigators using viral and non-viral vectors have demonstrated IL-24 overexpression in human cancer cells inhibited tumor growth both in vitro and in vivo. A majority of these studies using immunodeficient animal models have focused on demonstrating the direct anticancer properties of IL-24. Very few studies have focused on studying the immunotherapeutic properties of IL-24 despite it being reported to function as a Th1 cytokine. A phase I clinical trial using an adenovirus vector expressing IL-24 (Ad-IL24/INGN241) reported Ad-IL24 treatment of cancer patients resulted in changes in cytokines and T cells. However, well-designed and detailed preclinical studies to support the clinical findings are warranted. Demonstrating immune modulation by IL-24 will provide a rationale for developing IL-24-based immunotherapeutic approaches for cancer treatment.In the present chapter, we provide experimental details for conducting IL-24-based immunotherapy studies. As it is not possible for the authors to cover all of the information the authors recommend reading other immunology-based literature and procedures for a better understanding of conducting preclinical studies.

Activation and dedifferentiation of chondrocytes: implications in cartilage injury and repair

Cartilage injury remains a major challenge in orthopedic surgery due to the fact that articular cartilage has only a limited capacity for intrinsic healing. Cartilage impaction is followed by a post-traumatic inflammatory response. Chondrocytes and synoviocytes are activated to produce inflammatory mediators and degradative enzymes which can induce a progradient cartilage self-destruction finally leading to secondary osteoarthritis (OA). However, an anti-inflammatory compensatory response is also detectable in cartilage by up-regulation of anti-inflammatory cytokines, probably a temporary attempt by chondrocytes to restore cartilage homeostasis. Matrix-assisted autologous chondrocyte transplantation (MACT) is a suitable technique for improving the rate of repair of larger articular cartilage defects. For MACT, autologous chondrocytes were isolated from a cartilage biopsy of a non-load bearing joint area. This technique requires sufficient expansion of differentiated autologous chondrocytes, which were then seeded on suitable biodegradable three-dimensional (3D) matrices to preform an extracellular cartilage matrix (ECM) before implantation into the defect. Cell expansion is accompanied by chondrocyte dedifferentiation, whereby substantial changes occur at multiple levels of chondrocyte synthetic profiles: including the ECM, cell surface receptors and cytoskeletal proteins. Since these dedifferentiated chondrocytes produce a non-specific mechanically inferior ECM, they are not suitable for MACT. 3D cultures are means of inducing and maintaining chondrocyte (re)differentiation and to preform ECM. The combination of MACT with anabolic growth factors and anti-inflammatory strategies using anti-inflammatory mediators might be useful for stabilizing the differentiated chondrocyte phenotype, to support neocartilage formation and inhibit post-traumatic cartilage inflammation and hence, the development of secondary OA.

IL-20 activates human lymphatic endothelial cells causing cell signalling and tube formation

IL-20 is an arteriogenic cytokine that remodels collateral networks in vivo, and plays a role in cellular organization. Here, we investigate its role in lymphangiogenesis using a lymphatic endothelial cell line, hTERT-HDLEC, which expresses the lymphatic markers LYVE-1 and podoplanin. Upon stimulation of hTERT-HDLEC with IL-20, we found an increase in the intracellular free calcium concentration, in Akt and eNOS phosphorylations as well as in perinuclear NO production. We found that eNOS phosphorylation and NO synthesis are highly dependent on the PI3K/Akt signalling pathway. We also found an IL-20 induced phosphorylation of Erk1/2 and mTOR, and using the MEK inhibitor PD98059 and mTOR complex inhibitor rapamycin we demonstrated the importance of these signalling pathways in IL-20-mediated proliferation. IL-20 triggered actin polymerization and morphological changes resulting in elongated cell structures, and in matrigels, IL-20 caused tube formations of hTERT-HDLEC in a PI3K- and mTOR dependent way. In a sprouting assay we found that IL-20 caused cell migration within 24 h at a rate comparable to VEGF-C, and this migration could be inhibited by wortmannin and rapamycin. These data show that IL-20 activates cell signalling resulting in lymphangiogenic processes including migration, proliferation and tube formation. Thus, IL-20 is a cytokine that has the potential of activating or modulating the formation of lymphatic vessels.

Common inflammatory mediators orchestrate pathophysiological processes in rheumatoid arthritis and atherosclerosis

RA is characterized by a systemic inflammatory state, in which immune cells and soluble mediators play a crucial role. These inflammatory processes resemble those in other chronic inflammatory diseases, such as atherosclerosis. The chronic systemic inflammation in RA can be considered as an independent risk factor for the development of atherosclerosis, and represents an important field to investigate the reasons of the increase of acute cardiovascular events in RA. In the present review, we focused on several mediators of autoimmunity, inflammation and endothelial dysfunction, which can be considered the most promising targets to prevent atherogenesis in RA. Among several mediators, the pro-inflammatory cytokine TNF-alpha has been shown as a crucial factor to induce atherosclerosis in RA patients.