Effect of IL-10 on collagen-induced arthritis in mice

Magnesium increases numbers of Foxp3+ Treg cells and reduces arthritis severity and joint damage in an IL-10-dependent manner mediated by the intestinal microbiome

BACKGROUND

Rheumatoid arthritis (RA) is a common autoimmune disease with emerging environmental and microbiome risk factors. The western diet is typically deficient in magnesium (Mg), and there is some evidence suggesting that Mg may have anti-inflammatory properties. But the actual role of Mg supplementation in arthritis or in T cell subsets has not been explored.

METHODS

We investigated the role of a high Mg diet in two different mouse models of RA induced with the KRN serum, and collagen-induced arthritis. We also characterized the phenotypes of splenocytes, gene expression, and an extensive intestinal microbiome analyses including fecal material transplantation (FMT).

FINDINGS

The high Mg diet group was significantly protected with reduced arthritis severity and joint damage, and reduced expression of IL-1β, IL-6, and TNFα. The high Mg group also had increased numbers of Foxp3+ Treg cells and IL-10-producing T cells. The high Mg protective effect disappeared in IL-10 knockout mice. FMT from the high Mg diet mice recreated the phenotypes seen in the diet-treated mice, with reduced arthritis severity, increased Foxp3+ Treg, and increased IL-10-producing T cells. Intestinal microbiome analyses using 16S rDNA sequencing revealed diet-specific changes, including reduced levels of RA-associated Prevotella in the high Mg group, while increasing levels of Bacteroides and other bacteria associated with increased production of short-chain fatty acids. Metagenomic analyses implicated additional pathways including L-tryptophan biosynthesis and arginine deiminase.

INTERPRETATION

We describe a new role for Mg in suppressing arthritis, in expanding Foxp3+ T reg cells and in the production of IL-10, and show that these effects are mediated by the intestinal microbiome. Our discoveries suggest a novel strategy for modifying the intestinal microbiome to treat RA and other autoimmune and inflammatory diseases.

FUNDING

None.

Immunoregulation of synovial macrophages for the treatment of osteoarthritis

Osteoarthritis (OA) is the most common joint disease affecting approximately 10% of men and 18% of women older than 60. Its pathogenesis is still not fully understood; however, emerging evidence has suggested that chronic low-grade inflammation is associated with OA progression. The pathological features of OA are articular cartilage degeneration in the focal area, including new bone formation at the edge of the joint, subchondral bone changes, and synovitis. Conventional drug therapy aims to prevent further cartilage loss and joint dysfunction. However, the ideal treatment for the pathogenesis of OA remains to be defined. Macrophages are the most common immune cells in inflamed synovial tissues. In OA, synovial macrophages undergo proliferation and activation, thereby releasing pro-inflammatory cytokines, including interleukin-1 and tumor necrosis factor-α, among others. The review article discusses (1) the role of synovial macrophages in the pathogenesis of OA; (2) the progress of immunoregulation of synovial macrophages in the treatment of OA; (3) novel therapeutic targets for preventing the progress of OA or promoting cartilage repair and regeneration.

Usefulness of Cytokine Gene Polymorphisms for the Therapeutic Choice in Japanese Patients with Rheumatoid Arthritis

Background

Rheumatoid arthritis (RA) is characterized by systemic synovitis with bone erosion and joint cartilage degradation. Although the analysis of polymorphisms in cytokine-encoding genes is important or understanding the pathophysiology of RA and selecting appropriate treatment for it, few studies have examined such single-nucleotide polymorphisms (SNPs) specifically in Japanese patients. This study was established to investigate the associations between polymorphisms in cytokine-encoding genes, autoantibodies and therapeutic responses in Japanese RA patients.

Methods

The subjects in this study consisted of 100 RA patients and 50 healthy controls. We extracted data on sex, age, disease duration, rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibody, and therapeutic responses, including to methotrexate (MTX) and biological disease-modifying antirheumatic drugs (DMARDs). Genomic DNA was isolated from peripheral blood, which was genotyped for IL-10, TNF-α, TGF-β₁, and IFN-γ polymorphisms.

Results

Regarding IL-10 (−592 C/A and −819 C/T), significant decreases in the frequencies of the IL-10 (−592) CC genotype and (−819) CC genotype were found in RA patients compared with the levels in controls. For IFN-γ (+874 T/A), a significant decrease in the frequency of the TT genotype was found in RA patients compared with that in controls. Regarding TGF-β₁ (+869 T/C), patients with positivity for anti-CCP antibody had a significantly lower frequency of the CC genotype than those with negativity for it. Furthermore, the IL-10 (−592) CC genotype and (−819) CC genotype might be related to the biological DMARD-response.

Conclusion

Our results suggest that the analysis of polymorphisms in cytokine-encoding genes may be useful when selecting treatment for Japanese RA patients.

Association between interleukin-10 polymorphisms and juvenile idiopathic arthritis: a meta-analysis

INTRODUCTION

The aim of this review is to investigate IL-10 polymorphisms (-1082 G/A, -819 C/T, and -592 C/A) and their association with susceptibility to JIA.

EVIDENCE ACQUISITION

A meta-analysis was conducted after database search for relevant articles (MEDLINE and EMBASE).

EVIDENCE SYNTHESIS

A total of seven studies involving 1495 patients and 1670 controls were considered in the meta-analysis. There was no association between the IL-10 -1082 G/A, -819 C/T, and -592 C/A polymorphisms and JIA in allele contrast and any of the genetic models (allele contrast: odds ratio [OR] 0.90, 95% confidence interval [CI] 0.79-1.02, P=0.09; OR=0.97, 95% CI 0.83-1.13, P=0.68; OR=0.92, 95% CI 0.81-1.06, P=0.24, respectively). In subgroup analysis, none of the subtypes of JIA including systemic, rheumatoid factor (RF)-positive polyarticular, RF-negative polyarticular, and oligoarticular was not significantly associated with IL-10 polymorphism. Meta-analysis of the IL-10 haplotype revealed no association between GCC, ACC, and ATA haplotypes and JIA.

CONCLUSIONS

This meta-analysis showed that IL-10 polymorphisms were not associated with risk of JIA.

Anti-arthritic activities of ethanol extracts of Circaea mollis Sieb. & Zucc. (whole plant) in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Circaea mollis Sieb. & Zucc., a genus of Circaea that follows Onagraceae, has been used for centuries as a folk herb in traditional Chinese medicine (TCM) and Hani Ethnopharmacy for the treatment of joint swelling and pain in rheumatoid arthritis.

AIM OF THE STUDY

This study was designed to confirm anti-arthritic effects and its underlying mechanism of ethanol extracts of Circaea mollis Sieb. & Zucc. (EEC), which may contribute to provide the pharmacological basis in the treatment of rheumatoid disease.

MATERIALS AND METHODS

Dimethylbenzene (DMB)-induced inflammatory swelling model, hot-plate pain model in mice and Freund's complete adjuvant (FCA)-induced arthritis model in rats were used to evaluate the anti-arthritis effect of EEC. Arthritis severity was done by measuring inflammatory swelling, pain threshol, paw swelling, arthritis index, body weight, spleen index and thymus index. The levels of TNF-α, IL-1β and IL-10 in sera were measured using ELISA. The pathological change of the ankle joint was also done. Phenolic composition of EEC was analyzed.

RESULTS

EEC inhibited inflammatory swelling and increased heat-induced pain threshold in mice. Furthermore, EEC significantly alleviated paw swelling and arthritis index, decreasing the spleen index and thymus index. Besides, EEC down-regulated the serum TNF-α and IL-1β, and increased the production of serum IL-10 in FCA-induced rats. Histopathological examination demonstrated that EEC can effectively relieve synovial hyperplasia, control the infiltration of the inflammatory and protect cartilage from destruction.

CONCLUSION

Our work demonstrated that EEC possessed the potential therapeutic effect against arthritis in rodents which was attributed to modulating proinflammatory cytokines TNF-α, IL-1β and anti-inflammatory factors IL-10. Flavonoids and polyphenols may contribute to the therapeutic effect of EEC on arthritis.

Ellagic acid alleviates adjuvant induced arthritis by modulation of pro- and anti-inflammatory cytokines

Rheumatoid arthritis (RA) is a chronic inflammatory disease of unknown aetiology, but it is now clear that pro-inflammatory cytokines play a central role in its pathogenesis. Ellagic acid (EA) has a variety of biological activities including anti-oxidant, anti-inflammatory, and anti-cancer properties. The aim of the present study was to evaluate the potential effect of ellagic acid on the prevention and/or treatment of adjuvant induced arthritis (AIA) model in mice. Ellagic acid treatment was started one week before AIA induction and continued for three weeks after induction of AIA. Ellagic acid treatment significantly (p < 0.01) inhibited foot paw oedematous swelling and attenuated AIA-associated pathology. Ellagic acid significantly (p < 0.01) reduced serum levels of pro-inflammatory cytokines: interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), and interleukin 17 (IL-17). However, serum levels of IL-10 and interferon γ (IFN-γ) significantly increased (p < 0.01 and p < 0.05, respectively), while serum level of transforming growth factor β (TGF-β) did not significantly alter with EA treatment. In conclusion, these results suggest that EA attenuated AIA-associated pathology in the mouse model by downregulation of pro-inflammatory cytokines and upregulation of anti-inflammatory cytokines.

Association of IL-10 gene polymorphisms and susceptibility to Juvenile Idiopathic Arthritis in Egyptian children and adolescents: a case-control study

Background

Juvenile Idiopathic Arthritis (JIA) is the most common chronic arthritis in children worldwide. Among anti-inflammatory cytokines, interleukin-10 (IL-10) is a key immunosuppressive cytokine involved in the pathogenesis of JIA. To date, only a few studies concerned the association of interleukin-10 gene polymorphisms with JIA. In this study, we aimed to investigate 3 cytokine single-nucleotide polymorphisms situated at positions -1082(G/A), −819(C/T), and −592(C/A) in the promoter region of the IL-10 gene to determine whether this polymorphism could be a marker of susceptibility to JIA in Egyptian children and adolescents. We also measured the serum level of IL-10 to assess its relation to such polymorphism.

Methods

This was a case-control study included 100 patients diagnosed with JIA, and matched with age, gender, ethnicity 100 healthy control subjects.

Interleukin-10 −1082(G/A), −819(C/T), and −592(C/A) polymorphisms were genotyped by amplification refractory mutation system- polymerase chain reaction (ARMS)-PCR methodology, while the serum IL10 levels were measured by ELISA method.

Results

Compared to the controls subjects, the frequency of IL-10- AA genotype and A allele at the –1082 position were overrepresented in patients with JIA (OR = 2.7; 95% CI: 1.1–6.4 for the AA genotype; P <0.05 and OR: 1.5; 95% CI: 1.03–2.3 for the A allele; P <0.05 respectively). On the other hand, no significant differences were found between the 2 groups in the genotype or allele frequencies for the –819 and –592 positions. Of note, we found a significant positive association between the IL-10 (-1082) AA genotype and susceptibility to polyarticular JIA (OR: 4.3; 95% CI: 1.5–12.7; P <0.01). We observed that patients with the IL-10 (-1082) AA genotype had significantly lower serum IL-10 levels (2.3 ± 0.9 pg/ml) compared to those with AG genotype (7.6 ± 1.5 pg/ml) and GG genotype (9.5 ± 1.2 pg/ml); P < 0.01, respectively.

Conclusion

We demonstrate for the first time, to the best of our knowledge, that the presence of an A allele or AA gene variant at the –1082 position of the promoter region of the interleukin-10 gene may constitute risk factors for developing JIA in Egyptian children and adolescents. Moreover, we observed a significant positive association between the IL10 –1082 AA gene variant and susceptibility to polyarticular JIA.

Mast cell depletion in the preclinical phase of collagen-induced arthritis reduces clinical outcome by lowering the inflammatory cytokine profile

Background

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease, which is characterized by inflammation of synovial joints leading to the destruction of cartilage and bone. Infiltrating mast cells can be found within the inflamed synovial tissue, however their role in disease pathogenesis is unclear. Therefore we have studied the role of mast cells during different phases of experimental arthritis.

Methods

We induced collagen-induced arthritis (CIA), the most frequently used animal model of arthritis, in an inducible mast cell knock-out mouse and determined the effect of mast cell depletion on the development and severity of arthritis.

Results

Depletion of mast cells in established arthritis did not affect clinical outcome. However, depletion of mast cells during the preclinical phase resulted in a significant reduction in arthritis. This reduction coincided with a decrease in circulating CD4⁺ T cells and inflammatory monocytes but not in the collagen-specific antibody levels. Mast cell depletion resulted in reduced levels of IL-6 and IL-17 in serum. Furthermore, stimulation of splenocytes from mast cell-depleted mice with collagen type II resulted in reduced levels of IL-17 and enhanced production of IL-10.

Conclusions

Here we show that mast cells contribute to the preclinical phase of CIA. Depletion of mast cells before disease onset resulted in an altered collagen-specific T cell and cytokine response. These data may suggest that mast cells play a role in the regulation of the adaptive immune response during the development of arthritis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1036-8) contains supplementary material, which is available to authorized users.

Targeted IL-4 therapy synergizes with dexamethasone to induce a state of tolerance by promoting Treg cells and macrophages in mice with arthritis

F8-IL-4 is a recently developed immunocytokine that delivers IL-4 to sites of inflammation by targeting the neovasculature. We previously reported that F8-IL-4, in combination with dexamethasone (DXM), provides a durable therapy in mice with collagen-induced arthritis (CIA). Therefore, the objective of this study was to identify the mechanism by which IL-4 and DXM combination therapy provides long-lasting disease remission. F8-IL-4 alone attenuated inflammation in CIA and this was associated with increased TH 2 and decreased TH 17 cell numbers in the joints. Similarly, DXM alone had an antiinflammatory effect associated with lower TH 17 cell numbers. In both cases, these therapeutic benefits were reversed once treatment was stopped. On the other hand, combination therapy with F8-IL-4 plus DXM led to a synergistic increase in the percentage of regulatory T (Treg) cells and antiinflammatory macrophages in the arthritic joint and spleen as well as IL-10 levels in serum and spleen. The net result of this was a more pronounced attenuation of inflammation and, more importantly, protection from arthritis relapse post therapy retraction. In conclusion, F8-IL-4 plus DXM is a durable treatment for arthritis that acts by promoting Treg cells in a synergistic manner, and by producing a sustained increase in antiinflammatory macrophages.

Disease-regulated local IL-10 gene therapy diminishes synovitis and cartilage proteoglycan depletion in experimental arthritis

OBJECTIVES

Rheumatoid arthritis is a chronic destructive autoimmune disease, but the course is unpredictable in individual patients. An attractive treatment would provide a disease-regulated therapy that offers personalised drug delivery. Therefore, we expressed the anti-inflammatory interleukin-10 (IL-10) gene under the control of inflammation-dependent promoters in a mouse model of arthritis.

METHODS

Proximal promoters of S100a8, Cxcl1, Mmp13, Saa3, IL-1b and Tsg6 were selected by whole-genome expression analysis of inflamed synovial tissues from arthritic mice. Mice were injected intraarticularly in knee joints with lentiviral vectors expressing a luciferase reporter or the therapeutic protein IL-10 under control of the Saa3 or Mmp13 promoter. After 4 days, arthritis was induced by intraarticular injection of streptococcal cell walls (SCW). At different time points after arthritis induction, in vivo bioluminescent imaging was performed and knee joints were dissected for histological and RNA analysis.

RESULTS

The disease-regulated promoter-luciferase reporter constructs showed different activation profiles during the course of the disease. The Saa3 and Mmp13 promoters were significantly induced at day 1 or day 4 after arthritis induction respectively and selected for further research. Overexpression of IL-10 using these two disease-inducible promoters resulted in less synovitis and markedly diminished cartilage proteoglycan depletion and in upregulation of IL-1Ra and SOCS3 gene expression.

CONCLUSIONS

Our study shows that promoters of genes that are expressed locally during arthritis can be candidates for disease-regulated overexpression of biologics into arthritic joints, as shown for IL-10 in SCW arthritis. The disease-inducible approach might be promising for future tailor-made local gene therapy in arthritis.

Type 1 regulatory T cells specific for collagen type II as an efficient cell-based therapy in arthritis

Introduction

Regulatory T (Treg) cells play a crucial role in preventing autoimmune diseases and are an ideal target for the development of therapies designed to suppress inflammation in an antigen-specific manner. Type 1 regulatory T (Tr1) cells are defined by their capacity to produce high levels of interleukin 10 (IL-10), which contributes to their ability to suppress pathological immune responses in several settings. The aim of this study was to evaluate the therapeutic potential of collagen type II–specific Tr1 (Col-Treg) cells in two models of rheumatoid arthritis (RA) in mice.

Methods

Col-Treg clones were isolated and expanded from collagen-specific TCR transgenic mice. Their cytokine secretion profile and phenotype characterization were studied. The therapeutic potential of Col-Treg cells was evaluated after adoptive transfer in collagen-antibody– and collagen-induced arthritis models. The in vivo suppressive mechanism of Col-Treg clones on effector T-cell proliferation was also investigated.

Results

Col-Treg clones are characterized by their specific cytokine profile (IL-10^highIL-4^negIFN-γ^int) and mediate contact-independent immune suppression. They also share with natural Tregs high expression of GITR, CD39 and granzyme B. A single infusion of Col-Treg cells reduced the incidence and clinical symptoms of arthritis in both preventive and curative settings, with a significant impact on collagen type II antibodies. Importantly, injection of antigen-specific Tr1 cells decreased the proliferation of antigen-specific effector T cells in vivo significantly.

Conclusions

Our results demonstrate the therapeutic potential of Col-Treg cells in two models of RA, providing evidence that Col-Treg could be an efficient cell-based therapy for RA patients whose disease is refractory to current treatments.

Opposing roles for heat and heat shock proteins in macrophage functions during inflammation: a function of cell activation state?

Macrophages function both under normothermia and during periods of body temperature elevation (fever). Whether macrophages sense and respond to thermal signals in a manner which regulates their function in a specific manner is still not clear. In this brief review, we highlight recent studies which have analyzed the effects of mild heating on macrophage cytokine production, and summarize thermally sensitive molecular mechanisms, such as heat shock protein (HSP) expression, which have been identified. Mild, physiologically achievable, hyperthermia has been shown to have both pro- and anti-inflammatory effects on macrophage inflammatory cytokine production and overall it is not clear how hyperthermia or HSPs can exert opposing roles on macrophage function. We propose here that the stage of activation of macrophages predicts how they respond to mild heating and the specific manner in which HSPs function. Continuing research in this area is needed which will help us to better understand the immunological role of body temperature shifts. Such studies could provide a scientific basis for the use of heat in treatment of inflammatory diseases.

Role of interleukin 10 transcriptional regulation in inflammation and autoimmune disease

Interleukin 10 (IL-10) is a cytokine with potent anti-inflammatory properties that plays a central role in limiting host immune response to pathogens, thereby preventing damage to the host and maintaining normal tissue homeostasis. Dysregulation of IL-10 is associated with enhanced immunopathology in response to infection as well as increased risk for development of many autoimmune diseases. Thus a fundamental understanding of IL-10 gene expression is critical for our comprehension of disease progression and resolution of host inflammatory response. In this review, we discuss modes of regulation of IL-10 gene expression in immune effector cell types, including signal transduction, epigenetics, promoter architecture, and post-transcriptional regulation, and how aberrant regulation contributes to immunopathology and disease progression.

B10 cells and regulatory B cells balance immune responses during inflammation, autoimmunity, and cancer

The ability of B cells to negatively regulate cellular immune responses and inflammation has only recently been described. Hallmark papers from a number of distinguished laboratories have identified phenotypically diverse B-cell subsets with regulatory functions during distinct autoimmune diseases, including IL-10-producing B cells, CD5+ B-1a cells, CD1d+ marginal zone B cells, and transitional-2-marginal zone precursor B cells. Most recently, a numerically rare and phenotypically unique CD1dhiCD5+CD19hi subset of regulatory B cells has been identified in the spleens of both normal and autoimmune mice. CD1dhiCD5+ B cells with the capacity to produce IL-10 have been named B10 cells as they produce IL-10 exclusively and are the predominant B-cell source of IL-10. Remarkably, B10 cells are potent negative regulators of inflammation and autoimmunity in mouse models of disease in vivo. Herein, our current understanding of B10-cell development and function is reviewed in the context of previous studies that have identified and characterized regulatory B cells, emerging evidence for B10-cell regulation of tumor immunity, and the likelihood that B10 cells exist in humans.

The B cell, arthritis, and the sympathetic nervous system

The pathogenesis of rheumatoid arthritis (RA) is still an unresolved puzzle. Many factors and inflammatory cells play together to initiate a chronic inflammatory process that, if untreated, leads to complete destruction of involved joints. Recent success in treating severe forms of RA with B cell-depleting or -modifying agents revived the concept that the B cell might play a pivotal role in the pathogenesis of some forms of arthritis. However, the rather unspecific treatment approach affecting all B cells, no matter if autoreactive or not, leads to potential harmful side-effects, e.g., severe infections. Therefore, finding regulatory systems that more specifically modulate B cell function is important to improve current treatment options. One such regulatory system is the sympathetic nervous system (SNS), which is known to modulate B cell function, but also profoundly influences arthritis development and severity. This review develops the hypothesis that the SNS via modulating B cell function influences arthritis development and progression. For this purpose data is presented that shows (1) how the SNS influences B cell function, (2) how the SNS influences arthritis development and severity, and (3) how B cells are involved in the disease process with an emphasis on possible contact points for SNS neuromodulation.

Ultra-low-dose naloxone restores the antinociceptive effect of morphine and suppresses spinal neuroinflammation in PTX-treated rats

The aim of the present study was to examine the effect of ultra-low-dose naloxone on pertussis toxin (PTX)-induced thermal hyperalgesia in rats and its underlying mechanisms. Male Wistar rats, implanted with an intrathecal catheter with or without a microdialysis probe, received a single intrathecal injection of PTX (1 microg in 5 microl saline). Four days after PTX injection, they were randomly given a different dose of naloxone (either 15 microg or 15 ng in 5 microl saline), followed by a morphine injection (10 microg in 5 microl saline) after 30 min. The results found that PTX injection induced thermal hyperalgesia and increasing excitatory amino acid (EAA; L-glutamate and L-aspartate) concentration in the spinal CSF dialysates. Ultra-low-dose naloxone not only preserved the antinociceptive effect of morphine but also suppressed the PTX-evoked EAA release as well. Moreover, ultra-low-dose naloxone plus morphine administration inhibited the downregulation of L-glutamate transporters (GTs) and the L-glutamate-metabolizing enzyme glutamine synthetase (GS), and, moreover, inhibited microglial activation and suppressed cytokine expression in PTX-treated rat spinal cords. These results show that ultra-low-dose naloxone preserves the antinociceptive effect of morphine in PTX-treated rats. The mechanisms include (a) inhibition of pro-inflammatory cytokine expression, (b) attenuation of PTX-evoked EAA release, and (c) reversion of the downregulation of GT expression.

Adenoviral delivery of interleukin-10 fails to attenuate experimental Lyme disease

Production of interleukin-10 (IL-10) by C57BL/6 mice following infection with Borrelia burgdorferi has been proposed as a mechanism whereby resistance to the development of experimental Lyme arthritis is maintained. In the current study, we sought to determine the role of IL-10 during infection of arthritis- and carditis-susceptible C3H mice. Infection of C3H IL-10(-/-) mice led to increased joint swelling and arthritis severity scores over those of wild-type C3H mice. Measurement of B. burgdorferi numbers in joints or disseminated tissues indicated a more efficient clearance of spirochetes in the absence of IL-10, similar to that reported in C57BL/6 IL-10(-/-) mice. However, in contrast to previous in vitro work, infection of C3H IL-10(-/-) mice led to decreased in vivo expression of the cytokines KC, IL-1beta, IL-4, and IL-12p70 in the infected joints. Finally, adenoviral expression of IL-10 in the infected joints of C3H mice was unable to modulate the development of severe Lyme arthritis and had no effect on spirochete clearance or Borrelia-specific antibody production. Development of Lyme carditis appeared to be independent of modulation by IL-10. These results suggest that IL-10 limits the development of joint inflammation in both arthritis-resistant and -susceptible mouse strains infected with B. burgdorferi and that increased IL-10 production cannot rescue genetic susceptibility to development of pathology in this model.

Release of heat shock protein 70 and the effects of extracellular heat shock protein 70 on the production of IL-10 in fibroblast-like synoviocytes

It has recently been suggested that heat shock protein (Hsp) 70, an intracellular protein, can be released into the extracellular compartment and exert important immunomodulatory functions. Although elevated Hsp70 has been found in synovial fluid from patients with rheumatoid arthritis (RA), its sources and extracellular functions remain unclear. In this study, we explored whether stress response such as heat stress or exposure to tumor necrosis factor-alpha (TNF-alpha) could induce Hsp70 release from RA fibroblast-like synoviocytes (FLSs) and whether extracellular Hsp70 would stimulate cytokine production in RA FLSs. Cultured FLSs were obtained from patients with RA. The expression of intracellular Hsp70 was studied by Western blot. Hsp70 release and the production of interleukin (IL)-6, IL-8, and IL-10 by RA FLSs were studied by specific enzyme-linked immunosorbent assays. The levels of Toll-like receptor (TLR) 2 and 4 mRNA and protein in FLSs were analyzed using reverse transcription-polymerase chain reaction and Western blotting. Treatment with sublethal heat shock or TNF-alpha results in the up-regulation of intracellular Hsp70 in FLSs and Hsp70 release from RA FLSs. In vitro studies show that extracellular Hsp70 can induce anti-inflammatory cytokine IL-10 production in FLSs. The mRNA and protein expression of TLR2 and TLR4 was demonstrated in FLSs, and TLR4 blocking abrogated the up-regulatory effects of Hsp70 on IL-10 production. Thus, these results lend support to the hypothesis that Hsp70 is actively released from FLSs in response to heat shock or TNF-alpha and Hsp70 may be a major paracrine/autocrine inducer of IL-10 production in FLSs via TLR4.

B-cell involvement in the pathogenesis of RA-is there a contribution of the sympathetic nervous system?

The pathogenesis of rheumatoid arthritis (RA), the most common rheumatic disease, is still an unsolved puzzle. For many years, T-cells were the main focus of research, but recently, the B-cell drew more and more attention not least, due to the observation in humans that the anti-CD20 antibody Retuximab, which selectively depletes subsets of B-cells, lessens disease symptoms. A second novel approach to understand pathomechanisms that contribute to the development and progression of arthritis focuses on the sympathetic nervous system, which is known to moderate the function of immune cells, e.g., the B-cell, and therefore, is tied into a complex neuroimmune network that influences the course of the disease. This review first discusses current research that shows the significance of B-cells in the pathogenesis of RA. It then gives a short review of knowledge regarding the role of the sympathetic nervous system (1) in RA pathogenesis and (2) in modulating B-cell responses. Finally, the hypothesis is introduced that the sympathetic nervous system via modulating B-cell function, e.g., antibody production, influences the development and progression of RA.

Comparison of single nucleotide polymorphisms in the human interleukin-10 gene promoter between rheumatoid arthritis patients and normal subjects in Malaysia

In this study, three single nucleotide polymorphisms (SNPs) located within the promoter of the human interleukin (IL)-10 gene [rs1800896 (position: -1087G>A), rs1800871 (position: -824C>T) and rs1800872 (position: -597C>A)] were investigated in 84 rheumatoid arthritis (RA) patients and 95 age- and sex-matched healthy subjects using polymerase chain reaction-restriction fragment length polymorphism method. Production of IL-10 by peripheral blood lymphocytes from the RA patients and healthy subjects cultured in the presence of Concanavalin A (Con A) was determined by using enzyme-linked immunosorbent assay. The results show that the distribution of the IL-10 genotypes did not differ significantly between RA patients and healthy subjects (P>0.05). However, a significant difference was observed in allele frequencies of -824CT, -824TT, -597CA, and -597AA between the RA patients and healthy volunteers (P=0.04). The -1087A/-824T/-597A (ATA) haplotype, which comprises all mutant alleles, was associated with lower IL-10 production when compared with the other haplotypes. In contrast, the RA patients who did not display the ATA haplotype produced significantly higher levels of IL-10 when compared with those carrying either one (P=0.012) or two (P=0.005) ATA haplotypes. Our findings suggest that there is an association between SNPs in the promoter of the human IL-10 gene and susceptibility to RA.

Antibody-mediated delivery of IL-10 inhibits the progression of established collagen-induced arthritis

The antibody-mediated targeted delivery of cytokines to sites of disease is a promising avenue for cancer therapy, but it is largely unexplored for the treatment of chronic inflammatory conditions. Using both radioactive and fluorescent techniques, the human monoclonal antibodies L19 and G11 (specific to two markers of angiogenesis that are virtually undetectable in normal adult tissues) were found to selectively localize at arthritic sites in the murine collagen-induced model of rheumatoid arthritis following intravenous (i.v.) administration. The same animal model was used to study the therapeutic action of the L19 antibody fused to the cytokines IL-2, tumour necrosis factor (TNF) and IL-10. Whereas L19-IL-2 and L19-TNF treatment led to increased arthritic scores and paw swellings, the fusion protein L19-IL-10 displayed a therapeutic activity, which was superior to the activity of IL-10 fused to an antibody of irrelevant specificity in the mouse. The anti-inflammatory cytokine IL-10 has been investigated for the treatment of patients with rheumatoid arthritis, but clinical development plans have been discontinued because of a lack of efficacy. Because the antigen recognised by L19 is strongly expressed at sites of arthritis in humans and identical in both mice and humans, it suggests that the fusion protein L19-IL-10 might help overcome some of the clinical limitations of IL-10 and provide a therapeutic benefit to patients with chronic inflammatory disorders, including arthritis.

Anti-Ischemic Effect of Selectin Blocker Through Modulation of Tumor Necrosis Factor-α and Interleukin-10

BACKGROUND

Preliminary studies in our laboratories indicate that a recently discovered synthetic drug, TBC-1269, acts as a multiple selectin blocker and provides protection against tissue damage in rats that are subjected to severe liver ischemia/reperfusion. Here, we report that this effect is dose and time dependent, with its effects acting through the modulation of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10.

MATERIAL AND METHODS

Mice subjected to 90 min of partial (70-80%) hepatic ischemia and 3 h of reperfusion were divided into eight groups (n=6/group): sham, ischemic control (IC), three groups of TBC-1269-treated animals at different concentrations (10, 20, 40, mg/kg) and another three groups of TBC-1269 given at 40 mg/kg at different times of administration: 15 min prereperfusion but after ischemia (no pretreatment), at the time of reperfusion, and at 15 min after reperfusion. The parameters measured at 3 h of reperfusion included liver function tests (alanine aminotransferase and aspartate aminotransferase), histopathology analysis and measurements using enzyme-linked immunosorbent assay in serum of TNF-alpha and IL-10. Statistical analysis included analysis of variance with P values of <0.05 for significance. Results were expressed as mean +/- SD.

RESULTS

The liver function tests showed statistically significant differences between the ischemic control group and both the sham group and the group treated with 40 mg/kg at the time of reperfusion (40@RP). These results correlated well with the histopathological analysis in that we found no difference in vacuolization, congestion, and necrosis between the 40@RP group and the sham group. The TNF-alpha and the IL-10 also reflected the protection observed in histopathology, with a decrease in TNF- alpha from the high levels observed in the IC (32 +/- 2.32 pg/mL) to a lower level of 8.5 +/- 4.04 mg observed in the 40@RP group, and an increment in the levels of the protective IL-10 from 2.8 +/- 2.9 pg/mL in the IC group versus 37.9 +/- 11.6 pg/mL in the 40@RP treated group (P<0.05). Lower doses and different times of administration of TBC-1269 did not show a protective effect. The IC group showed no difference in damage by histopathology or liver enzymes compared to the rest of the groups, except the 40@RP group.

CONCLUSION

In this work, we demonstrated that the small molecule multiple selectin inhibitor (TBC-1269) offered significant protection for the ischemic liver when given at 40 mg/kg at the time of perfusion. Lower doses and different times of administration did not show the optimal drug effect. The protection observed in the liver function tests (alanine aminotransferase and aspartate aminotransferase) and histopathology in this group was also reflected in the significant decrease in serum TNF-alpha and equally significant increase in serum protective IL-10.

Ryanodine receptor antagonism protects the ischemic liver and modulates TNF-alpha and IL-10

BACKGROUND

Dantrolene is a ryanodine receptor and intracellular calcium antagonist. The ryanodine receptor (RyR) Ca(2+) release channel mobilizes Ca(2+) from internal stores to support a variety of cellular functions, including the inflammatory response after ischemia and reperfusion. The pharmacological mechanism of dantrolene is associated with the inhibition of the release of Ca(2+) from the skeletal muscle sarcoplasmic reticulum (SR). We hypothesized that dantrolene could exert a protective effect in our model of liver ischemia and reperfusion by modulating TNF-alpha and IL-10.

MATERIAL AND METHODS

Mice subjected to 90 min of partial (70 to 80%) hepatic ischemia and 3 h of reperfusion were divided into five groups (n = 6/group): sham, ischemic control, and the dantrolene 1 mg/kg group studied at three times of administration: 15 min before reperfusion (DAN-PRE), at the time of reperfusion (DAN-RP), and 15 min after reperfusion (DAN-POS). The parameters measured at 3 h of reperfusion included serum liver function tests alanine aminotransferase (ALT) and aspartate aminotransferase (AST), TNF-alpha, and IL-10 in serum and liver histology.

RESULTS

It was demonstrated that the RyR intracellular calcium antagonist dantrolene offered the most significant protection for the ischemic liver when given before reperfusion and at the time of reperfusion. AST significantly differed between the control group and the DAN-PRE and DAN-RP groups (P < 0.05). ALT showed a statistically significant decrease in the DAN-PRE treated group and a decrease, although not significant, in the DAN-RP. Histological examination demonstrated a significant decrease in vacuolization in the same both groups (P < 0.05). Necrosis was significantly diminished when dantrolene was used at the time of reperfusion; congestion decreased in the same groups but without statistical significant difference. The levels of TNF-alpha were significantly decreased in the DAN-RP group. There was a decrease in TNF-alpha in the DAN-PRE group but not statistically significant. IL-10 reflected the protection observed in necrosis and vacuolization in the histopathology with an increment at the time of reperfusion (P < 0.05). DAN-POS did not exert a protective effect in ALT, AST, liver histology, or cytokine response.

CONCLUSION

For the first time the ryanodine receptor antagonist dantrolene offered significant functional and structural protection of the ischemic liver when given at the time for reperfusion and partial protection when given prereperfusion. RyR inhibition approach down-regulated the expression of TNF-alpha and induced an increment of the protective cytokine IL-10 when administered at the time of reperfusion. There was no protective effect of dantrolene after reperfusion.

Analog peptides of type II collagen can suppress arthritis in HLA-DR4 (DRB1*0401) transgenic mice

Rheumatoid arthritis (RA) is an autoimmune disease associated with the recognition of self proteins secluded in diarthrodial joints. We have previously established that mice transgenic for the human DR genes associated with RA are susceptible to collagen-induced arthritis (CIA) and we have identified a determinant of type II collagen (CII(263-270)) that triggers T-cell immune responses in these mice. We have also determined that an analog of CII(263-270) would suppress disease in DR1 transgenic mice. Because the immunodominant determinant is the same for both DR1 transgenic and DR4 transgenic mice, we attempted to determine whether the analog peptide that was suppressive in DR1 transgenic mice would also be effective in suppressing CIA in DR4 transgenic mice. We treated DR4 transgenic mice with two analog peptides of CII that contained substitutions in the core of the immunodominant determinant: CII(256-276) (F263N, E266D) and CII(256-270) (F263N, E266A). Mice were observed for CIA, and T-cell proliferative responses were determined. Either peptide administered at the time of immunization with CII significantly downregulated arthritis. Binding studies demonstrated that replacement of the phenylalanine residue in position 263 of the CII peptide with asparagine significantly decreased the affinity of the peptide for the DR4 molecule. In contrast, replacement of the glutamic acid residue in position 266 with aspartic acid or with alanine had differing results. Aspartic acid reduced the affinity (35-fold) whereas alanine did not. Both peptides were capable of suppressing CIA. With the use of either peptide, CII(256-276) (F263N, E266D) or CII(256-270) (F263N, E266A), the modulation of CIA was associated with an increase in T-cell secretion of IL-4 together with a decrease in IFN-gamma. We have identified two analog peptides that are potent suppressors of CIA in DR4 transgenic mice. These experiments represent the first description of an analog peptide of CII recognized by T cells in the context of HLA-DR4 that can suppress autoimmune arthritis.

Hypernociceptive role of cytokines and chemokines: targets for analgesic drug development?

Pain is one of the classical signs of the inflammatory process in which sensitization of the nociceptors is the common denominator. This sensitization causes hyperalgesia or allodynia in humans, phenomena that involve pain perception (emotional component+nociceptive sensation). As this review focuses mainly on animal models, which don't allow discrimination of the emotional component, the terms nociception and hypernociception are used to describe overt behavior induced by mechanical stimulation and increase of nociceptor sensitivity, respectively. Pro- and anti-inflammatory cytokines and chemokines are endogenous small protein mediators released by local or migrating cells whose balance modulates the intensity of inflammatory response. The inflammatory stimuli or tissue injuries stimulate the release of characteristic cytokine cascades, which ultimately trigger the release of final mediators responsible for inflammatory pain. These final mediators, such as prostanoids or sympathetic amines, act directly on the nociceptors to cause hypernociception, which results from the lowering of threshold due to modulation of specific voltage-dependent sodium channels. Furthermore, a direct effect of cytokines on nociceptors is also described. On the other hand, there are also anti-inflammatory cytokines, such as interleukin (IL)-10, IL-4 and IL-13, and IL-1 receptor antagonists (IL-1ra), which inhibit the production of hypernociceptive cytokines and/or the final hypernociceptive mediators, preventing the installation of or the increase in the hypernociception. This review highlights the importance of the direct and indirect actions of cytokines and chemokines in inflammatory and neuropathic hypernociception, emphasizing the evidence suggesting these molecules are potential targets to develop novel drugs and therapies for the treatment of pain.

Expression of interleukin-22 in rheumatoid arthritis: potential role as a proinflammatory cytokine

OBJECTIVE

Interleukin-22 (IL-22) is a novel cytokine of the IL-10 family. Although its pathophysiologic function is largely unknown, induction of acute-phase responses by IL-22 has suggested proinflammatory properties. In this study, we sought to examine whether IL-22 plays a role in the pathogenesis of rheumatoid arthritis (RA).

METHODS

Expression of IL-22 and IL-22 receptor 1 (IL-22R1) was examined by reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and immunohistochemical analysis. The effects of recombinant IL-22 (rIL-22) on cultured synovial fibroblasts derived from RA patients (RASF), with regard to the proliferation of synovial fibroblasts and production of monocyte chemoattractant protein 1 (MCP-1), were examined by alamer blue assay and enzyme-linked immunosorbent assay, respectively.

RESULTS

IL-22 messenger RNA was detected by RT-PCR in RA synovial tissues and mononuclear cells isolated from RA synovial fluid samples. High levels of IL-22 were expressed both in the lining and the sublining layers of RA synovial tissues. Staining for vimentin and CD68, as markers of synovial fibroblasts and macrophages, respectively, showed that the majority of IL-22-positive cells were synovial fibroblasts and macrophages. IL-22R1 was also expressed in both the lining and the sublining layers of RA synovial tissues. The majority of cells expressing IL-22R1 were positive for vimentin, but not for CD68. Expression of IL-22 and IL-22R1 in RASF was confirmed by RT-PCR and Western blot analysis. In vitro, rIL-22 significantly increased proliferation of RASF and production of MCP-1 by RASF above the value of medium controls. Moreover, MAPK activation was induced in RASF in response to IL-22 stimulation.

CONCLUSION

These data suggest that IL-22, produced by synovial fibroblasts and macrophages, promotes inflammatory responses in RA synovial tissues by inducing the proliferation and chemokine production of synovial fibroblasts.

Novel regulatory mechanisms of CD40-induced prostanoid synthesis by IL-4 and IL-10 in human monocytes

Interleukins IL-4 and IL-10 are considered to be central regulators for the limitation and eventual termination of inflammatory responses in vivo, based on their potent anti-inflammatory effects toward LPS-stimulated monocytes/macrophages and neutrophils. However, their role in T cell-dependent inflammatory responses has not been fully elucidated. In this study, we investigated the effects of both cytokines on the production of PGE(2), a key molecule of various inflammatory conditions, in CD40-stimulated human peripheral blood monocytes. CD40 ligation of monocytes induced the synthesis of a significant amount of PGE(2) via inducible expression of the cyclooxygenase (COX)-2 gene. Both IL-10 and IL-4 significantly inhibited PGE(2) production and COX-2 expression in CD40-stimulated monocytes. Using specific inhibitors for extracellular signal-related kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), we found that both kinase pathways are involved in CD40-induced COX-2 expression. CD40 ligation also resulted in the activation of NF-kappaB. Additional experiments exhibited that CD40 clearly induced the activation of the upstream kinases MAPK/ERK kinase 1/2, MAPK kinase 3/6, and I-kappaB in monocytes. IL-10 significantly inhibited CD40-induced activation of the ERK, p38 MAPK, and NF-kappaB pathways; however, inhibition by IL-4 was limited to the ERK pathway in monocytes. Neither IL-10 nor IL-4 affected the recruitment of TNFR-associated factors 2 and 3 to CD40 in monocytes. Collectively, IL-10 and IL-4 use novel regulatory mechanisms for CD40-induced prostanoid synthesis in monocytes, thus suggesting a potential role for these cytokines in regulating T cell-induced inflammatory responses, including autoimmune diseases.

CD4+CD25bright Regulatory T Cells Actively Regulate Inflammation in the Joints of Patients with the Remitting Form of Juvenile Idiopathic Arthritis

This study investigates the role of CD4(+)CD25(+) regulatory T cells during the clinical course of juvenile idiopathic arthritis (JIA). Persistent oligoarticular JIA (pers-OA JIA) is a subtype of JIA with a relatively benign, self-remitting course while extended oligoarticular JIA (ext-OA JIA) is a subtype with a much less favorable prognosis. Our data show that patients with pers-OA JIA display a significantly higher frequency of CD4(+)CD25(bright) T cells with concomitant higher levels of mRNA FoxP3 in the peripheral blood than ext-OA JIA patients. Furthermore, while numbers of synovial fluid (SF) CD4(+)CD25(bright) T cells were equal in both patient groups, pers-OA JIA patients displayed a higher frequency of CD4(+)CD25(int) T cells and therefore of CD4(+)CD25(total) in the SF than ext-OA JIA patients. Analysis of FoxP3 mRNA levels revealed a high expression in SF CD4(+)CD25(bright) T cells of both patient groups and also significant expression of FoxP3 mRNA in the CD4(+)CD25(int) T cell population. The CD4(+)CD25(bright) cells of both patient groups and the CD4(+)CD25(int) cells of pers-OA JIA patients were able to suppress responses of CD25(neg) cells in vitro. A markedly higher expression of CTLA-4, glucocorticoid-induced TNFR, and HLA-DR on SF CD4(+)CD25(bright) T regulatory (Treg) cells compared with their peripheral counterparts suggests that the CD4(+)CD25(+) Treg cells may undergo maturation in the joint. In correlation with this mature phenotype, the SF CD4(+)CD25(bright) T cells showed an increased regulatory capacity in vitro compared with peripheral blood CD4(+)CD25(bright) T cells. These data suggest that CD4(+)CD25(bright) Treg cells play a role in determining the patient's fate toward either a favorable or unfavorable clinical course of disease.

Autoimmune diseases as the loss of active "self-control"

Converging experimental evidence indicates that the clinical expression of autoimmunity is under the control of T cell-mediated immunoregulatory circuits. Several types of suppressor T cells have been described. Some of them are closely dependent upon cytokines such as TH2 cells and Tr1 cells. Others appear to rely more on cell-cell contact (such as CD25+ CD62L+ T cells), although some cytokines, notably TGF-beta, may be involved in their growth or their mode of action. It is tempting to separate suppressor cells that appear spontaneously, such as CD25+ T cells and NKT cells (innate immunoregulation), from those that are only observed after antigen administration, such as TH2 cells and Tr1 cells (adaptive immunoregulation). The role of these diverse cell types in the control of the onset or the progression of autoimmune diseases is likely, but still a matter of debate. A central question is to determine whether immune dysregulation precedes the burst of pathogenic autoimmunity.

The spontaneous remission of juvenile idiopathic arthritis is characterized by CD30+ T cells directed to human heat-shock protein 60 capable of producing the regulatory cytokine interleukin-10

OBJECTIVE

To test the hypothesis that T cell reactivity to self heat-shock protein 60 (Hsp60) in patients with remitting juvenile idiopathic arthritis (JIA) is part of an antiinflammatory, regulatory mechanism.

METHODS

Using peripheral blood-derived mononuclear cells (PBMCs) and synovial fluid-derived mononuclear cells (SFMCs) obtained from patients with JIA, we analyzed the expression of CD30 and the induction of regulatory cytokines in response to human and mycobacterial Hsp60.

RESULTS

In oligoarticular JIA patients, in vitro activation of PBMCs and SFMCs with Hsp60 induced a high expression of CD30 on CD4+, activated (HLA-DR-positive), memory (CD45RO+) T cells. The expression of CD30 induced by human Hsp60 was much higher than that induced by mycobacterial Hsp60. In oligoarticular JIA patients with active disease, the expression of CD30 in response to human Hsp60 was paralleled by a high interleukin-10 (IL-10):interferon-gamma (IFNgamma) ratio. In addition, restimulated human Hsp60-specific T cell lines from oligoarticular JIA patients showed a high production of IL-10 and a low production of IFNgamma. In contrast, PBMCs and SFMCs from polyarticular JIA patients responded to human Hsp60 with virtually no expression of CD30 and a low IL-10:IFNgamma ratio.

CONCLUSION

The results show that T cells responding to human Hsp60 in oligoarticular JIA patients express CD30, and during active phases of the disease, these T cells have a cytokine profile with a high IL-10:IFNgamma ratio. These findings suggest that in oligoarticular JIA patients, human Hsp60-specific CD4+ cells have a regulatory function and contribute to disease remission.

Interleukin-10 therapy--review of a new approach

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Its main biological function seems to be the limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells such as T cells, B cells, natural killer cells, antigen-presenting cells, mast cells, and granulocytes. However, very recent data suggest IL-10 also mediates immunostimulatory properties that help to eliminate infectious and noninfectious particles with limited inflammation. Numerous investigations, including expression analyses in patients, in vitro and animal experiments suggest a major impact of IL-10 in inflammatory, malignant, and autoimmune diseases. So IL-10 overexpression was found in certain tumors as melanoma and several lymphomas and is considered to promote further tumor development. Systemic IL-10 release is a powerful tool of the central nervous system to prevent hyperinflammatory processes by activation of the neuro-endocrine axis following acute stress reactions. In contrast, a relative IL-10 deficiency has been observed and is regarded to be of pathophysiological relevance in certain inflammatory disorders characterized by a type 1 cytokine pattern such as psoriasis. Recombinant human IL-10 has been produced and is currently being tested in clinical trials. This includes rheumatoid arthritis, inflammatory bowel disease, psoriasis, organ transplantation, and chronic hepatitis C. The results are heterogeneous. They give new insight into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Efficacy of interleukin-10 gene electrotransfer into skeletal muscle in mice with collagen-induced arthritis

BACKGROUND

Gene therapy is very promising in the treatment of rheumatoid arthritis (RA). Electrotransfer is a recent method reported to enhance in vivo intramuscular DNA transfection. Interleukin-10 (IL-10) has antiinflammatory effects in RA and in collagen-induced arthritis (CIA), a murine model of RA. In order to improve our strategy of gene therapy, we used electrotransfer to enhance penetration into skeletal muscle with CIA of plasmids encoding IL-10.

METHODS

CIA was induced in DBA/1 mice by immunization with bovine type II collagen. Injection into the tibial cranial muscle of low-dose (200 ng) pCOR plasmid encoding murine IL-10 (pCOR-CMV-mIL-10) was immediately followed by application of square-wave electric pulses (8 pulses of 200V/cm, 20 ms duration at 2 Hz). Control groups received empty plasmid or saline before electrotransfer.

RESULTS

When electrotransfer was performed twice on days 10 and 25 postimmunization, CIA was significantly delayed (P < 0.05) and attenuated (P < 0.001) in groups treated by electrotransfer or pCOR-CMV-mIL-10 plasmid vs. control groups. When electrotransfer of pCOR-CMV-mIL-10 plasmid was performed on days 25 and 40 postimmunization, at disease onset, the clinical severity of CIA was reduced (P < 0.05). All groups which had been electrotransferred early or late by pCOR-CMV-mIL-10 plasmid showed suppression of histological signs of arthritis.

CONCLUSIONS

Taken together, these data indicate that administration of an antiinflammatory plasmid-born gene by electrotransfer of naked DNA is effective in vivo in an arthritis model.

Interleukin-10 ameliorates the outcome of Staphylococcus aureus arthritis by promoting bacterial clearance

Staphyllococcus aureus-induced infections often result in high mortality and permanent joint destruction, despite treatment with antibiotics. IL-10 is typically regarded as an anti-inflammatory cytokine because it promotes a T helper cell type 2 response, and subsequently down-regulates cell mediated immune functions. To investigate the role of IL-10 in S. aureus-induced arthritis and sepsis, Balb/c mice, intact or defective with respect to IL-10 gene were intravenously inoculated with bacteria. IL-10-/- mice develop a more frequent and destructive arthritis compared to their congeneic controls. The mechanisms regulating such outcome may be due not only to the anti-inflammatory properties of IL-10 but also, directly or indirectly, to antibacterial features of this molecule. Indeed, inoculation of staphylococci to IL-10-/- mice resulted in higher bacterial load in blood and kidneys compared to congeneic controls. Altogether our data indicate that IL-10 is essential for efficient elimination of bacteria and thereby for protection against septic arthritis.

Collagen-induced arthritis is exacerbated in IL-10-deficient mice

IL-10 is a potent immunoregulatory cytokine attenuating a wide range of immune effector and inflammatory responses. In the present study, we assess whether endogenous levels of IL-10 function to regulate the incidence and severity of collagen-induced arthritis. DBA/1 wildtype (WT), heterozygous (IL-10+/-) and homozygous (IL-10-/-) IL-10-deficient mice were immunized with type II collagen. Development of arthritis was monitored over time, and collagen-specific cytokine production and anticollagen antibodies were assessed. Arthritis developed progressively in mice immunized with collagen, and 100% of the WT, IL-10+/-, and IL-10-/- mice were arthritic at 35 days. However, the severity of arthritis in the IL-10-/- mice was significantly greater than that in WT or IL-1+/- animals. Disease severity was associated with reduced IFN-gamma levels and a dramatic increase in CD11b-positive macrophages. Paradoxically, both the IgG1 and IgG2a anticollagen antibody responses were also significantly reduced. These data demonstrate that IL-10 is capable of controlling disease severity through a mechanism that involves IFN-gamma. Since IL-10 levels are elevated in rheumatoid arthritis synovial fluid, these findings may have relevance to rheumatoid arthritis.

Antiinflammatory effect of retrovirally transfected interleukin-10 on monosodium urate monohydrate crystal-induced acute inflammation in murine air pouches

OBJECTIVE

To investigate the role of interleukin-10 (IL-10) in the inflammatory response, the antiinflammatory effect of retrovirally transfected IL-10 was evaluated both in vitro and in vivo.

METHODS

A recombinant retrovirus containing the murine IL-10 gene was constructed using the pLXSN vector and was designated as LXSN-IL-10. Murine IL-10 was introduced into embryonic C57BL/6J fibroblast cells using LXSN-IL-10 to create C57-IL-10 cells. The effect of IL-10 in the culture supernatant of these cells was then evaluated by determining changes in the production of tumor necrosis factor alpha (TNFalpha), macrophage inflammatory protein 1alpha (MIP-1alpha), and MIP-1beta by macrophages. The antiinflammatory effect of C57-IL-10 cells was also investigated using an in vivo model of monosodium urate monohydrate (MSU) crystal-induced acute inflammation.

RESULTS

The IL-10 gene transcript and its product were detected by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The level of IL-10 in the culture supernatant of C57-IL-10 cells was estimated to be 50 ng/ml. The culture supernatant of these cells exerted the biologic activity of IL-10, showing inhibition of TNFalpha, MIP-1alpha, and MIP-1beta production by macrophages. Injection of C57-IL-10 cells into murine air pouches significantly inhibited MSU crystal-induced cellular infiltration (P < 0.01) and production of the mouse CXC chemokine KC (P < 0.05). These findings were consistent with the results obtained by the injection of recombinant human IL-10 into air pouches.

CONCLUSION

In this murine air pouch model of MSU crystal-induced inflammation, IL-10 seemed to inhibit the recruitment of neutrophils at least partly by suppressing KC production. These findings seem to suggest that IL-10 gene therapy may be useful for inflammatory diseases.

Regulatory role of interleukin-10 in experimental group B streptococcal arthritis

Intravenous inoculation of CD-1 mice with 10(7) CFU of type IV group B Streptococcus (GBS) results in a high incidence of diffuse septic arthritis, associated with high levels of systemic and local production of interleukin-1beta (IL-1beta) and IL-6. In this study, the role of the anti-inflammatory cytokine IL-10 in the evolution of GBS systemic infection and arthritis was evaluated. IL-10 production was evident in sera and joints of GBS-infected mice. Neutralization of endogenous IL-10 by administration of anti-IL-10 antibodies (1 mg/mouse) at the time of infection resulted in worsening of articular lesions and 60% mortality associated with early sustained production of IL-6, IL-1beta, and tumor necrosis factor alpha (TNF-alpha). The effect of IL-10 supplementation was assessed by administering IL-10 (100, 200, or 400 ng/mouse) once a day for 5 days, starting 1 h after infection. Treatment with IL-10 had a beneficial effect on GBS arthritis, and there was a clear-cut dose dependence. The decrease in pathology was associated with a significant reduction in IL-6, IL-1beta, and TNF-alpha production. Histological findings showed limited periarticular inflammation and a few-cell influx in the articular cavity of IL-10-treated mice, confirming clinical observations. In conclusion, this study provides further information concerning the role of IL-10 in regulating the immune response and inflammation and calls attention to the potential therapeutic use of IL-10 in GBS arthritis.

IL-10-deficient B10.Q mice develop more severe collagen-induced arthritis, but are protected from arthritis induced with anti-type II collagen antibodies

IL-10 is a pleiotropic cytokine with stimulatory and inhibitory properties, and is thought to have a protective role in rheumatoid arthritis and collagen-induced arthritis (CIA). In this study, we investigated how IL-10 deficiency affects CIA and anti-collagen type II (CII) Ab-transferred arthritis in C57BL/10.Q (B10.Q) mice. The B10.Q.IL-10(-/-) mice had an 8-cM 129/Ola fragment around the IL-10 gene. The mice were treated with antibiotics, appeared healthy, and had no colitis. T cells from IL-10(-/-) mice expressed similar levels of IFN-gamma, IL-2, and IL-4 after mitogen stimulation; however, macrophages showed a reduced TNF-alpha production compared with IL-10(+/-) littermates. IL-10(-/-) mice had an increased incidence, and a more severe CIA disease than the IL-10(+/-) littermates. To study the role of IL-10 in T cell tolerance, IL-10(-/-) were crossed into mice carrying the immunodominant epitope, CII(256-270), in cartilage (MMC) or in skin (TSC). Both IL-10(-/-) and IL-10(+/-) MMC and TSC mice were completely tolerized against CIA, indicating that lack of IL-10 in this context did not break tolerance. To investigate whether IL-10 was important in the effector phase of CIA, arthritis was induced with anti-CII Abs. Surprisingly, IL-10(-/-) were less susceptible to Ab-transferred arthritis, as only 30% showed signs of disease compared with 90% of the littermates. Therefore, IL-10 seemed to have a protective role in CIA, but seemed to exacerbate the arthritogenicity of anti-CII Abs. These data emphasize the importance of studying IL-10 in a defined genetic context in vivo, to understand its role in a complex disease like arthritis.

Interleukin-10 and the interleukin-10 receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

Murine IL-10 gene transfer inhibits established collagen-induced arthritis and reduces adenovirus-mediated inflammatory responses in mouse liver

The effects of homologous IL-10 administration during an established autoimmune disease are controversial, given its reported immunostimulatory and immunosuppressive properties. Studies of collagen-induced arthritis have shown efficacy with repeated administrations of IL-10; however, when the EBV IL-10 homologue was administered via adenovirus gene transfer technology the results were equivocal. Therefore, the present study was undertaken to elucidate the effects of prolonged homologous IL-10 administration via adenovirus-mediated gene delivery on the progression of established arthritis. Collagen type II (CII)-immunized mice received i.v. injections of 10(7) or 10(8) PFU of an E1-deleted adenoviral vector containing the murine IL-10 gene (AdIL-10), after arthritis onset. Mice were monitored for 3 wk for disease progression, and gene transduction was assessed by quantification of serum mIL-10. CII-specific cell-mediated and humoral immune responses were analyzed by lymph node cell proliferation, cytokine production, and anti-CII Ab responses. Furthermore, because adenoviral vectors have been reported to induce organ dysfunction due to cell-mediated immune responses to the viral Ags, we have also evaluated delayed-type hypersensitivity responses and reactive hepatitis to the systemically delivered adenovirus and whether the IL-10 produced could influence those responses. Sustained suppression of autoimmune arthritis and elevated serum levels of IL-10 were achieved in our study. AdIL-10 treatment reduced cell-mediated immune reactivity, but did not affect humoral responses. Furthermore, IL-10 was able to reduce, but not totally abrogate, adenovirus-induced hepatic inflammation. These findings provide further insights into the diverse interplay of immune processes involved in autoimmune inflammation and the mechanism of cytokine immunotherapy.

Interleukin-10 and the Interleukin-10 Receptor

Interleukin-10 (IL-10), first recognized for its ability to inhibit activation and effector function of T cells, monocytes, and macrophages, is a multifunctional cytokine with diverse effects on most hemopoietic cell types. The principal routine function of IL-10 appears to be to limit and ultimately terminate inflammatory responses. In addition to these activities, IL-10 regulates growth and/or differentiation of B cells, NK cells, cytotoxic and helper T cells, mast cells, granulocytes, dendritic cells, keratinocytes, and endothelial cells. IL-10 plays a key role in differentiation and function of a newly appreciated type of T cell, the T regulatory cell, which may figure prominently in control of immune responses and tolerance in vivo. Uniquely among hemopoietic cytokines, IL-10 has closely related homologs in several virus genomes, which testify to its crucial role in regulating immune and inflammatory responses. This review highlights findings that have advanced our understanding of IL-10 and its receptor, as well as its in vivo function in health and disease.

[Cytokine balance in the pathogenesis of rheumatoid arthritis]

Rheumatoid arthritis (RA) is a common, frequently severe, chronic inflammatory disease. Although the cause of RA remains unknown, recent advances in understanding its pathogenesis have been substantial. Despite the use of a variety of medications, the treatment of RA is not fully effective in most patients. A T-helper type 1 (Th1)/T-helper type 2 (Th2) cytokine imbalance has been suggested to be of pathogenic importance in several diseases. In this review, the information of cytokine balance in both the experimental model of arthritis and patients with arthritis were summarized. Furthermore, to characterize the cytokine balance at a single cell level, we analyzed the subtypes of cytokine-secreting cells in an experimental model of arthritis using a dual color enzyme-linked immunospot assay (Stardust assay) which we newly developed. These information including our findings might provide us the clue for diagnosis and therapy of arthritis.

Highly autoproliferative T cells specific for 60-kDa heat shock protein produce IL-4/IL-10 and IFN-gamma and are protective in adjuvant arthritis

Previously we have shown that T cell responses to the mycobacterial 60-kDa heat shock protein (hsp60) peptide M256-270 mediated protection against adjuvant arthritis in Lewis rats. We have demonstrated now that M256-270-primed T cells become highly reactive to naive syngeneic APC upon repetitive restimulation in vitro with peptide M256-265, comprising the conserved core of peptide M256-270. These autoproliferative responses in the absence of added Ag were MHC class II restricted and resulted in the production of IL-4/IL-10 and IFN-gamma. Enhanced autoproliferation and expression of the cell surface molecule B7.2 by these T cells were observed in response to syngeneic heat-shocked APC, which indicated that the autoproliferation and expression of B7.2 resulted from the recognition of endogenously expressed and processed hsp. Despite their strong autoreactivity, upon transfer such T cells were found to induce a significant disease reduction in adjuvant arthritis. In contrast, T cells both primed and restimulated with peptide M256-270 became unresponsive toward syngeneic APC as well as toward the conserved core peptide M256-265, and they were devoid of protective capacity. This study demonstrates that the loss of self-tolerance toward hsp60 does not necessarily lead to autoimmune disease, but that hsp60-specific self-reactive and autoproliferative T cells may mediate T cell regulation in arthritis.

Heterogeneous effects of IL-2 on collagen-induced arthritis

IL-2 is generally considered a pro-inflammatory cytokine that exacerbates Th1-mediated disease states, such as autoimmune arthritis. Consistent with this role for IL-2, recent studies from our laboratory demonstrate that IL-2 mRNA is markedly increased during the acute stage of collagen-induced arthritis (CIA), an animal model of rheumatoid arthritis. To further define the role of IL-2 in CIA, the levels of IL-2 protein and its receptor and the effects of IL-2 administration were analyzed during CIA. IL-2 protein and IL-2R were preferentially expressed at disease onset, compared with later stages of disease. Administration of recombinant human IL-2 (rhIL-2) at, or just before, disease onset exacerbated disease; surprisingly, rhIL-2 given before disease onset inhibited CIA, associated with reduced cellular and humoral responses to type II collagen. Determination of in vivo serum levels of Th1 and Th2 cytokines in response to rhIL-2 treatment demonstrated that IFN-gamma, but not IL-4, was markedly up-regulated in response to IL-2. In mice treated with anti-IFN-gamma Ab, both early and late IL-2 administration exacerbated CIA. Thus, IL-2 can have two opposite effects on autoimmune arthritis, a direct stimulatory effect and an indirect suppressive effect that is mediated by IFN-gamma.

Amelioration of established collagen induced arthritis by systemic IL-10 gene delivery

A novel formulation of cationic liposomes containing the novel cytofectin ACHx was used for delivery of an anti-inflammatory cytokine gene, IL-10, to mice with established collagen induced arthritis. A single intraperitoneal injection of human IL-10 expression plasmid complexed with liposomes 2 to 4 days after the onset of arthritis was sufficient to give significant and prolonged amelioration of arthritis for 30 days. Preliminary experiments suggested that the therapeutic effect was IL-10 dose-dependent. The distribution of the human IL-10 DNA after injection was widespread, including the inflamed paws. Human IL-10 mRNA was also detected in the paws 24 h after injection. IL-10 protein was below the level of detection in paws and serum but was detected in some tissues up to 10 days after injection. The target cell of transfection was demonstrated to be the macrophage. These results suggest that systemic therapy with plasmid DNA complexed with cationic liposomes merits further development as an alternative method for anti-inflammatory treatment of arthritis.