Type II Collagen Autoimmunity in Rheumatoid Arthritis

Mesenchymal stem cells in autoimmune disease: A systematic review and meta-analysis of pre-clinical studies

Mesenchymal Stem Cells (MSCs) are of interest in the clinic because of their immunomodulation capabilities, capacity to act upstream of inflammation, and ability to sense metabolic environments. In standard physiologic conditions, they play a role in maintaining the homeostasis of tissues and organs; however, there is evidence that they can contribute to some autoimmune diseases. Gaining a deeper understanding of the factors that transition MSCs from their physiological function to a pathological role in their native environment, and elucidating mechanisms that reduce their therapeutic relevance in regenerative medicine, is essential. We conducted a Systematic Review and Meta-Analysis of human MSCs in preclinical studies of autoimmune disease, evaluating 60 studies that included 845 patient samples and 571 control samples. MSCs from any tissue source were included, and the study was limited to four autoimmune diseases: multiple sclerosis, rheumatoid arthritis, systemic sclerosis, and lupus. We developed a novel Risk of Bias tool to determine study quality for in vitro studies. Using the International Society for Cell & Gene Therapy's criteria to define an MSC, most studies reported no difference in morphology, adhesion, cell surface markers, or differentiation into bone, fat, or cartilage when comparing control and autoimmune MSCs. However, there were reported differences in proliferation. Additionally, 308 biomolecules were differentially expressed, and the abilities to migrate, invade, and form capillaries were decreased. The findings from this study could help to explain the pathogenic mechanisms of autoimmune disease and potentially lead to improved MSC-based therapeutic applications.

NIH/3T3 Fibroblasts Selectively Activate T Cells Specific for Posttranslationally Modified Collagen Type II

It has been shown that synovial fibroblasts (SF) play a key role in the initiation of inflammation and joint destruction, leading to arthritis progression. Fibroblasts may express major histocompatibility complex class II region (MHCII) molecules, and thus, they could be able to process and present antigens to immunocompetent cells. Here we examine whether different types of fibroblasts (synovial, dermal, and thymic murine fibroblasts, destructive LS48 fibroblasts, and noninvasive NIH/3T3 fibroblasts) may be involved in the initiation of rheumatoid arthritis (RA) pathogenesis and can process and present type II collagen (COL2)-an autoantigen associated with RA. Using a panel of MHCII/Aq-restricted T-cell hybridoma lines that specifically recognize an immunodominant COL2 epitope (COL2_259-273), we found that NIH/3T3 fibroblasts activate several T-cell clones that recognize the posttranslationally glycosylated or hydroxylated COL2_259-273 epitope. The HCQ.3 hybridoma, which is specific for the glycosylated immunodominant COL2 epitope 259-273 (Gal264), showed the strongest response. Interestingly, NIH/3T3 cells, but not destructive LS48 fibroblasts, synovial, dermal, or thymic fibroblasts, were able to stimulate the HCQ.3 hybridoma and other COL2-specific T-cell hybridomas. Our experiments revealed that NIH/3T3 fibroblasts are able to activate COL2-specific T-cell hybridomas even in the absence of COL2 or a posttranslationally modified COL2 peptide. The mechanism of this unusual activation is contact-dependent and involves the T-cell receptor (TCR) complex.

Citrullination of C1-inhibitor as a mechanism of impaired complement regulation in rheumatoid arthritis

Background

Dysregulated complement activation, increased protein citrullination, and production of autoantibodies against citrullinated proteins are hallmarks of rheumatoid arthritis (RA). Citrullination is induced by immune cell-derived peptidyl-Arg deiminases (PADs), which are overactivated in the inflamed synovium. We characterized the effect of PAD2- and PAD4-induced citrullination on the ability of the plasma-derived serpin C1-inhibitor (C1-INH) to inhibit complement and contact system activation.

Methods

Citrullination of the C1-INH was confirmed by ELISA and Western blotting using a biotinylated phenylglyoxal probe. C1-INH-mediated inhibition of complement activation was analyzed by C1-esterase activity assay. Downstream inhibition of complement was studied by C4b deposition on heat-aggregated IgGs by ELISA, using pooled normal human serum as a complement source. Inhibition of the contact system was investigated by chromogenic activity assays for factor XIIa, plasma kallikrein, and factor XIa. In addition, autoantibody reactivity to native and citrullinated C1-INH was measured by ELISA in 101 RA patient samples.

Results

C1-INH was efficiently citrullinated by PAD2 and PAD4. Citrullinated C1-INH was not able to bind the serine protease C1s and inhibit its activity. Citrullination of the C1-INH abrogated its ability to dissociate the C1-complex and thus inhibit complement activation. Consequently, citrullinated C1-INH had a decreased capacity to inhibit C4b deposition via the classical and lectin pathways. The inhibitory effect of C1-INH on the contact system components factor XIIa, plasma kallikrein, and factor XIa was also strongly reduced by citrullination. In RA patient samples, autoantibody binding to PAD2- and PAD4-citrullinated C1-INH was detected. Significantly more binding was observed in anti-citrullinated protein antibody (ACPA)-positive than in ACPA-negative samples.

Conclusion

Citrullination of the C1-INH by recombinant human PAD2 and PAD4 enzymes impaired its ability to inhibit the complement and contact systems in vitro. Citrullination seems to render C1-INH more immunogenic, and citrullinated C1-INH might thus be an additional target of the autoantibody response observed in RA patients.

Significance of Type II Collagen Posttranslational Modifications: From Autoantigenesis to Improved Diagnosis and Treatment of Rheumatoid Arthritis

Collagen type II (COL2), the main structural protein of hyaline cartilage, is considerably affected by autoimmune responses associated with the pathogenesis of rheumatoid arthritis (RA). Posttranslational modifications (PTMs) play a significant role in the formation of the COL2 molecule and supramolecular fibril organization, and thus, support COL2 function, which is crucial for normal cartilage structure and physiology. Conversely, the specific PTMs of the protein (carbamylation, glycosylation, citrullination, oxidative modifications and others) have been implicated in RA autoimmunity. The discovery of the anti-citrullinated protein response in RA, which includes anti-citrullinated COL2 reactivity, has led to the development of improved diagnostic assays and classification criteria for the disease. The induction of immunological tolerance using modified COL2 peptides has been highlighted as a potentially effective strategy for RA therapy. Therefore, the aim of this review is to summarize the recent knowledge on COL2 posttranslational modifications with relevance to RA pathophysiology, diagnosis and treatment. The significance of COL2 PTMs as a source of neo-antigens that activate immunity leading to or sustaining RA autoimmunity is discussed.

PLGA Particles in Immunotherapy

Poly(lactic-co-glycolic acid) (PLGA) particles are a widely used and extensively studied drug delivery system. The favorable properties of PLGA such as good bioavailability, controlled release, and an excellent safety profile due to the biodegradable polymer backbone qualified PLGA particles for approval by the authorities for the application as a drug delivery platform in humas. In recent years, immunotherapy has been established as a potent treatment option for a variety of diseases. However, immunomodulating drugs rely on targeted delivery to specific immune cell subsets and are often rapidly eliminated from the system. Loading of PLGA particles with drugs for immunotherapy can protect the therapeutic compounds from premature degradation, direct the drug delivery to specific tissues or cells, and ensure sustained and controlled drug release. These properties present PLGA particles as an ideal platform for immunotherapy. Here, we review recent advances of particulate PLGA delivery systems in the application for immunotherapy in the fields of allergy, autoimmunity, infectious diseases, and cancer.

Therapeutic Effect of Nile Tilapia Type II Collagen on Rigidity in CD8+ Cells by Alleviating Inflammation and Rheumatoid Arthritis in Rats by Oral Tolerance

Fibrillins are microfibril-associated macro glycoproteins found in connective tissues and structurally related to latent TGF-β-binding proteins (LTBPs). The special cellular immunity and blocking glycoprotein receptors IIb and IIIa of fibrillins are emerging topics in recent years. In this study, Nile Tilapia type IIcollagen (NTCII) was extracted and purified from the skull cartilages by a pepsin-soluble method. Amino acid analysis indicated that NTCII consisted of 315/1000 glycine residues, 72/1000 hydroxyproline residues and 108/1000 proline residues. SDS-PAGE analysis showed that NTCII was composed of three identical 130 kDa α-chains. The results of glycoprotein/carbohydrate assay indicated that the total polysaccharide content of NTCII was 5.6–19.0%. The IR spectrum of NTCII displayed five characteristic peaks of amide I, II, III, A, B. NTCII at 10–100 μg/mL concentration downregulated the content of cytokines in the presence or absence of LPS, especially the secretion of cytokines IL-6, IL-1β and TNF-α. Interestingly, NTCII promoted the secretion of Fas/Apo-1 compared to the control group and 25 μg/mL of NTCII resulted in a higher Fas/Apo-1 secretion level in CD8⁺ T cells. FITC-TCII fluorescence images confirmed that NTCII could bind to the membrane surface of CD8⁺ T cells, leading to the induction of rigidity. NTCII could bind to the membrane surface of CD8⁺ T cells that leads to the induction of rigidity, as evidenced by the FITC-NTCII fluorescence images. The qRT-PCR gene expression analysis of caspase-8 collected with Fas/Apo-1 was upregulated significantly in the 1 and 50 μg/mL NTCII-treated groups compared with the control group. Overall, the results conclude that the rigidity did not lead to an increase in inflammatory factors in CD8⁺ T cells treated with NTCII. The oral administration of NTCII 3 mg/kg dosage caused more prominent repair of damaged ankle cartilage than the 1 mg/kg dosage in Freund’s adjuvant-induced model of arthritis in rats. Therefore, this study disclosed the immunological and anti-arthritic effect of fibrillar collagen, which could be a potential biomaterial for practical applications with lower toxicity.

Nucleic Acids for Potential Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a common systemic inflammatory autoimmune disease that severely affects the life quality of patients. Current therapeutics in clinic mainly focus on alleviating the development of RA or relieving the pain of patients. The emerging biological disease-modifying antirheumatic drugs (DMARDs) require long-term treatment to achieve the expected efficacy. With the development of bionanotechnology, nucleic acids fulfill characters as therapeutics or nanocarriers and can therefore be alternatives to combat RA. This review summarizes the therapeutic RNAs developed through RNA interference (RNAi), nucleic acid aptamers, DNA nanostructures-based drug delivery systems, and nucleic acid vaccines for the applications in RA therapy and diagnosis. Furthermore, prospects of nucleic acids for RA therapy are intensively discussed as well.

Role of oxidative stress in pathophysiology of rheumatoid arthritis: insights into NRF2-KEAP1 signalling

Rheumatoid arthritis is one of the most prevalent, chronic, inflammatory disorders involving multiple articular and extra-articular complications. Immune deregulation owing to a combinatorial network of cells, inflammatory components, degrading enzymes, angiogenetic factors, exhibiting pleiotropy, synergy, or redundancy, is a critical hallmark for synovial inflammatory milieu reasoning clinical heterogeneity and variability of the disease. As a prototype of autoimmune disease, the pathophysiology of rheumatoid arthritis has been linked to oxidative stress. However, the exact mechanism for these potential driving factors contributing to disease inception and perpetuation is yet elusive. Nuclear factor erythroid 2-related factor 2 - Kelch ECH associating protein 1 (Nrf2-Keap1) pathway, controlled via multifactorial regulation, functions as a ubiquitous, evolutionarily conserved intracellular defense mechanism. Nrf2-Keap1 signalling maintains homeostatic responses against a plethora of environmental or endogenous deviations in cellular growth, death, redox metabolism, inflammation, bone remodelling, detoxification, etc. Administration of antioxidants as an add-on pharmacotherapy along with conventional drugs has been elucidated as a better measure for disease management. Some of the most promising natural and synthetic redox-based therapeutic compounds function as either scavengers of reactive species, or inhibitors of their sources, or activators of an endogenous antioxidant system (Nrf2-Keap1). The present review focuses on the binomial "rheumatoid arthritis-oxidative stress", bringing insights into their pathophysiological interrelationships and Nrf2 signalling, as well as the implications of potential diagnostic oxidative stress biomarkers and therapeutic interventions directed for disease management in patients with rheumatoid arthritis.Highlights:RA has complex etiopathogenesis, evolving from multiple endogenous and exogenous factors with oxidative stress as a critical pathogenic signature.Oxidative damage and damaged compounds could serve as potent biomarkers for disease diagnosis, therapeutic response, and prognosis.One of the supreme cytoprotective signalling cascades, the Nrf2-Keap1 pathway has been known to elicit a protective effect against RA and various other autoimmune, inflammatory, degenerative disorders.Inclusion of natural and synthetic antioxidants has been encouraged by various studies for additional therapy to conventional drugs for better management of the disease.

Hyaluronic Acid Synthesis Contributes to Tissue Damage in Systemic Lupus Erythematosus

Hyaluronic acid (HA), a component of the extracellular matrix, is the ligand for CD44 and has been implicated in the pathogenesis of kidney inflammation in patients with systemic lupus erythematosus (SLE), but its direct role and mechanism of action have not been studied. Here we show that administration of hymecromone (4-Methylumbelliferone, 4-MU), an HA synthesis inhibitor, to lupus-prone mice suppressed dramatically lupus-related pathology. Interestingly, 4-MU stopped the appearance of disease when administered prior to its onset and inhibited the progression of disease when administered after its appearance. Inhibition of HA synthesis in vivo reduced tissue damage and the number of intrarenal lymphoid cell infiltrates including double negative CD3+CD4-CD8- T cells which are known to be involved in the pathogenesis of SLE. Exposure of human peripheral blood mononuclear cells to HA in vitro increased the generation of CD3+CD4-CD8- T cells through a mechanism involving Rho-associated kinase. Our results signify the importance of the HA-rich tissue microenvironment in the activation of lymphocytes to cause tissue damage in SLE and suggest the consideration of inhibition of HA synthesis to treat patients.

Dynamic profiles, biodistribution and integration evaluation after intramuscular/intravenous delivery of a novel therapeutic DNA vaccine encoding chicken type II collagen for rheumatoid arthritis in vaccinated normal rodent

BACKGROUND

The persistence, biodistribution, and risk of integration into the host genome of any new therapeutic DNA vaccine must be established in preclinical studies. We previously developed the DNA vaccine pcDNA-CCOL2A1 encoding chicken type II collagen (CCII) for the treatment of rheumatoid arthritis (RA). In the present study, we characterized its dynamic profile, biodistribution, and potential for genomic DNA integration in normal vaccinated rodent.

RESULTS

A real-time quantitative PCR analysis (RT-qPCR) of animals administered a single dose of pcDNA-CCOL2A1 (300 μg/kg by intramuscular injection) showed that CCOL2A1 mRNA level in the blood peaked between 2 and 6 h post-immunization and then rapidly declined, and was undetectable between day 1-42. CCOL2A1 transcript was detected at the muscle injection site on days 3-14 post-immunization. Starting from day 14, the transcript was detected in the heart, liver, lung, and kidney but not in the spleen or thymus, and was expressed only in the lung on day 28. There was no CCOL2A1 mRNA present in the testes or ovaries at any time point. Non-invasive in vivo fluorescence imaging revealed CCII protein expression from 2 h up to day 10 and from 2 h up to day 35 after administration of pcDNA-CCOL2A1 via the intravenous and intramuscular routes, respectively; the protein had disappeared by day 42. Importantly, CCOL2A1 was not integrated into the host genome.

CONCLUSIONS

These results indicate that pcDNA-CCOL2A1 vaccine is rapidly cleared within a short period of time and is therefore safe, and merits further development as a therapeutic vaccine for RA treatment.

Exploiting PLGA-Based Biocompatible Nanoparticles for Next-Generation Tolerogenic Vaccines against Autoimmune Disease

Tolerogenic vaccines are aimed at inhibiting antigen-specific immune responses. Antigen-loaded nanoparticles (NPs) have been recently emerged as ideal tools for tolerogenic vaccination because their composition, size, and capability of loading immunomodulatory molecules can be readily exploited to induce peripheral tolerance. Among polymeric NPs, poly(lactic-co-glycolic acid) (PLGA) NPs have the advantage of currently holding approval for several applications in drug delivery, diagnostics, and other clinical uses by the Food and Drug Administration (FDA). PLGA-NPs are non-toxic and display excellent biocompatibility and biodegradability properties. Moreover, surface functionalization may improve their interaction with biological materials, thereby optimizing targeting and performance. PLGA-NPs are the most extensively studied in pre-clinical model in the field of tolerogenic vaccination. Thus, this review describes their potential applications in the treatment of autoimmune diseases.

Oxidative stress in autoimmune rheumatic diseases

The management of patients with autoimmune rheumatic diseases such as rheumatoid arthritis (RA) remains a significant challenge. Often the rheumatologist is restricted to treating and relieving the symptoms and consequences and not the underlying cause of the disease. Oxidative stress occurs in many autoimmune diseases, along with the excess production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The sources of such reactive species include NADPH oxidases (NOXs), the mitochondrial electron transport chain, nitric oxide synthases, nitrite reductases, and the hydrogen sulfide producing enzymes cystathionine-β synthase and cystathionine-γ lyase. Superoxide undergoes a dismutation reaction to generate hydrogen peroxide which, in the presence of transition metal ions (e.g. ferrous ions), forms the hydroxyl radical. The enzyme myeloperoxidase, present in inflammatory cells, produces hypochlorous acid, and in healthy individuals ROS and RNS production by phagocytic cells is important in microbial killing. Both low molecular weight antioxidant molecules and antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, and peroxiredoxin remove ROS. However, when ROS production exceeds the antioxidant protection, oxidative stress occurs. Oxidative post-translational modifications of proteins then occur. Sometimes protein modifications may give rise to neoepitopes that are recognized by the immune system as 'non-self' and result in the formation of autoantibodies. The detection of autoantibodies against specific antigens, might improve both early diagnosis and monitoring of disease activity. Promising diagnostic autoantibodies include anti-carbamylated proteins and anti-oxidized type II collagen antibodies. Some of the most promising future strategies for redox-based therapeutic compounds are the activation of endogenous cellular antioxidant systems (e.g. Nrf2-dependent pathways), inhibition of disease-relevant sources of ROS/RNS (e.g. isoform-specific NOX inhibitors), or perhaps specifically scavenging disease-related ROS/RNS via site-specific antioxidants.

Hyaluronan in immune dysregulation and autoimmune diseases

The tissue microenvironment contributes to local immunity and to the pathogenesis of autoimmune diseases - a diverse set of conditions characterized by sterile inflammation, immunity against self-antigens, and destruction of tissues. However, the specific factors within the tissue microenvironment that contribute to local immune dysregulation in autoimmunity are poorly understood. One particular tissue component implicated in multiple autoimmune diseases is hyaluronan (HA), an extracellular matrix (ECM) polymer. HA is abundant in settings of chronic inflammation and contributes to lymphocyte activation, polarization, and migration. Here, we first describe what is known about the size, amount, and distribution of HA at sites of autoimmunity and in associated lymphoid structures in type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. Next, we examine the recent literature on HA and its impact on adaptive immunity, particularly in regards to the biology of lymphocytes and Foxp3+ regulatory T-cells (Treg), a T-cell subset that maintains immune tolerance in healthy individuals. We propose that HA accumulation at sites of chronic inflammation creates a permissive environment for autoimmunity, characterized by CD44-mediated inhibition of Treg expansion. Finally, we address potential tools and strategies for targeting HA and its receptor CD44 in chronic inflammation and autoimmunity.

Juvenile porcine temporomandibular joint: Three different cartilaginous structures?

OBJECTIVE

The temporomandibular joint (TMJ) consists of three cartilaginous structures: the fossa, disc, and condyle. In juvenile idiopathic arthritis (JIA), inflammation of the TMJ leads to destruction of the condyle, but not of the fossa or the disc. Such a different effect of inflammation might be related to differences in matrix composition of the cartilaginous structures.

METHODS

The matrix composition of the three TMJ structures was analyzed in juvenile porcine samples and in an in vitro system of cells isolated from each anatomical structure embedded in 3% agarose gels.

RESULTS

The matrix of all three anatomical structures of the TMJ contained collagen type I and its gene expression was maintained after isolation. The condyle and the fossa stained positive for collagen type II and proteoglycans, but the condyle contained considerably more collagen type II and proteoglycans than the fossa. The disc contained neither collagen type II protein nor expression of its gene, and the disc did not stain positive for proteoglycans. Aggrecan gene expression was lower in the disc compared to condyle and fossa cell-isolates. In general, the cell-isolates in vitro closely mimicked the characteristic features found in the tissue.

CONCLUSION

The collagen type II content of the condyle clearly distinguished this cartilaginous structure from the disc and fossa. Since autoimmunity against collagen type II is associated with JIA, the relatively abundant presence of this type of collagen in the condyle might provide an explanation why primarily this cartilaginous structure of the TMJ is affected in JIA patients.

Basement membranes and autoimmune diseases

Basement membrane components are targets of autoimmune attack in diverse diseases that destroy kidneys, lungs, skin, mucous membranes, joints, and other organs in man. Epitopes on collagen and laminin, in particular, are targeted by autoantibodies and T cells in anti-glomerular basement membrane glomerulonephritis, Goodpasture's disease, rheumatoid arthritis, post-lung transplant bronchiolitis obliterans syndrome, and multiple autoimmune dermatoses. This review examines major diseases linked to basement membrane autoreactivity, with a focus on investigations in patients and animal models that advance our understanding of disease pathogenesis. Autoimmunity to glomerular basement membrane type IV is discussed in depth as a prototypic organ-specific autoimmune disease yielding novel insights into the complexity of anti-basement membrane immunity and the roles of genetic and environmental susceptibility.

Expression of tyrosine hydroxylase in CD4+ T cells contributes to alleviation of Th17/Treg imbalance in collagen-induced arthritis

Tyrosine hydroxylase (TH), a rate-limiting enzyme for the synthesis of catecholamines, is expressed in T lymphocytes. However, the role of T cell-expressed TH in rheumatoid arthritis (RA) is less clear. Herein, we aimed to show the contribution of TH expression by CD4⁺ T cells to alleviation of helper T (Th)17/regulatory T (Treg) imbalance in collagen-induced arthritis (CIA), a mouse model of RA. CIA was prepared by intradermal injection of collagen type II (CII) at tail base of DBA1/J mice. Expression of TH in the spleen and the ankle joints was measured by real-time polymerase chain reaction and Western blot analysis. Percentages of TH-expressing Th17 and Treg cells in splenic CD4⁺ T cells were determined by flow cytometry. Overexpression and knockdown of TH gene in CD4⁺ T cells were taken to evaluate effects of TH on Th17 and Treg cells in CIA. TH expression was upregulated in both the inflamed tissues (spleen and ankle joints) and the CD4⁺ T cells of CIA mice. In splenic CD4⁺ T cells, the cells expressing TH were increased during CIA. These cells that expressed more TH in CIA were mainly Th17 cells rather than Treg cells. TH gene overexpression in CD4⁺ T cells from CIA mice reduced Th17 cell percentage as well as Th17-related transcription factor and cytokine expression and secretion, whereas TH gene knockdown enhanced the Th17 cell activity. In contrast, TH gene overexpression increased Treg-related cytokine expression and secretion in CD4⁺ T cells of CIA mice, while TH gene knockdown decreased the Treg cell changes. Collectively, these findings show that CIA induces TH expression in CD4⁺ T cells, particularly in Th17 cells, and suggest that the increased TH expression during CIA represents an anti-inflammatory mechanism.

Evaluation of humoral and cellular immune responses to a DNA vaccine encoding chicken type II collagen for rheumatoid arthritis in normal rats

A major challenge in the development of effective therapies for rheumatoid arthritis (RA) is finding a method for the specific inhibition of the inflammatory disease processes without the induction of generalized immunosuppression. Of note, the development of therapeutic DNA vaccines and boosters that may restore immunological tolerance remains a high priority. pcDNA-CCOL2A1 is a therapeutic DNA vaccine encoding chicken type II collagen(CCII). This vaccine was developed by our laboratory and has been shown to exhibit efficacy comparable to that of the current "gold standard" treatment, methotrexate (MTX). Here, we used enzyme-linked immunosorbent assays with anti-CII IgG antibodies, quantified the expression levels of Th1, Th2, and Th3 cytokines, and performed flow cytometric analyses of different T-cell subsets, including Th1, Th2, Th17, Tc, Ts, Treg, and CD4(+)CD29(+)T cells to systemically evaluate humoral and cellular immune responses to pcDNA-CCOL2A1 vaccine in normal rats. Similar to our observations at maximum dosage of 3 mg/kg, vaccination of normal rats with 300 μg/kg pcDNA-CCOL2A1 vaccine did not induce the production of anti-CII IgG. Furthermore, no significant changes were observed in the expression levels of pro-inflammatory cytokines interleukin (IL)-1α, IL-5, IL-6, IL-12(IL-23p40), monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, regulated on activation in normal T-cell expressed and secreted (RANTES), receptor activator for nuclear factor-κB ligand (RANKL), and granulocyte colony-stimulating factor (G-CSF) or anti-inflammatory cytokines IL-4 and IL-10 in vaccinated normal rats relative to that in controls(P > 0.05). However, transforming growth factor (TGF)-β levels were significantly increased on days 10 and 14, while interferon (IFN)-γ and tumor necrosis factor (TNF)-α levels were significantly decreased on days 28 and 35 after vaccination(P < 0.05). Similarly, there were no significant differences in the percentages of Tc, Ts, Th1/Th2, and Th17 cells between the 2 groups(P > 0.05), with the exception of Treg cells, which were significantly reduced on days 14 and 21 after vaccination (P < 0.05), and CD4(+)CD29(+)T cells, which were significantly increased on days 7 and 14 after vaccination(P < 0.05).Taken together, these results suggested that pcDNA-CCOL2A1 vaccine did not markedly affect the balance of immune system components in vaccinated normal rats, indicating that this DNA vaccine may have clinical applications in the treatment of RA.

Clinical efficacy of a new CD28-targeting antagonist of T cell co-stimulation in a non-human primate model of collagen-induced arthritis

T cells have a central pathogenic role in the aetiopathogenesis of rheumatoid arthritis (RA), and are therefore a favoured target of immunotherapy aiming at physical or functional elimination. Here we report an efficacy test of FR104, a new co-stimulation inhibitor directly targeting CD28 on T cells, in a translationally relevant model, the rhesus monkey model of collagen-induced arthritis (CIA). As a relevant comparator we used abatacept [cytotoxic T lymphocyte antigen immunoglobulin (CTLA Ig)], an antagonist of CTLA-4 binding to CD80/86 clinically approved for treatment of RA. Treatment with either compound was started at the day of CIA induction. Although FR104 previously demonstrated a higher control of T cell responses in vitro than abatacept, both compounds were equally potent in the suppression of CIA symptoms and biomarkers, such as the production of C-reactive protein (CRP) and interleukin (IL)-6 and anti-collagen type II (CII) serum antibody (IgM/IgG). However, in contrast to abatacept, FR104 showed effective suppression of CII-induced peripheral blood mononuclear cell (PBMC) proliferation. The current study demonstrates a strong potential of the new selective CD28 antagonist FR104 for treatment of RA.

MicroRNA-663 activates the canonical Wnt signaling through the adenomatous polyposis coli suppression

Rheumatoid arthritis (RA) is a symmetrical polyarticular autoimmune disease of unknown etiology. In this present study, we observed that the adenomatous polyposis coli (APC) expression is down-regulated and the expression of microRNA (miR)-663 increased significantly in synovium from RA patients compared with control. Target gene prediction for miR-663 revealed that the mRNA of APC gene, which is a member of the canonical Wnt signaling pathway, has a miR-663 binding site in its 3'-untranslated region (3'UTR). The result showed that increased miR-663 suppressed the APC expression significantly, and this down-regulation of APC expression triggered the activation of canonical Wnt signaling through accumulation of β-catenin in fibroblast-like synoviocytes (FLS). In addition, increased miR-663 induced the FLS proliferation and the expression MMP3 and fibronectin during disease development. Therefore, miR-663 can be considered as a critical regulator of RA pathogenesis and can be utilized for developing miRNA-based therapeutic agents for RA patients.

Prohibitin as a novel autoantigen in rheumatoid arthritis

The aim of this study

The aim of this study was to verify whether prohibitin is a novel autoantigen in rheumatoid arthritis.

Material and methods

First, recombinant human prohibitin (rhPHB) protein was cloned, expressed, and purified. Then the anti-prohibitin autoantibodies were detected by western blotting by using rhPHB protein to incubate sera from patients with rheumatoid arthritis (RA). Next, immunoprecipitation was employed to further illustrate whether anti-prohibitin antibodies exist in RA patients. And finally, autoantibodies against the rhPHB protein were investigated using a homemade ELISA kit through the assessment of 258 real clinical samples.

Results

It was revealed that anti-prohibitin antibodies existed in the sera of patients with RA. Reactivity of serum IgG against rhPHB was detected in 26 of 86 RA patients (30.3%), 7 of 86 systemic lupus erythematosus (SLE) patients (8.1%), and 1 of 86 apparently healthy donors (HC) (1.2%).

Conclusions

Prohibitin was proved to be a novel autoantigen and the corresponding anti-prohibitin autoantibodies were present in the RA patients' blood circulation.

Autoantibodies to posttranslational modifications in rheumatoid arthritis

Autoantibodies have been associated with human pathologies for a long time, particularly with autoimmune diseases (AIDs). Rheumatoid factor (RF) is known since the late 1930s to be associated with rheumatoid arthritis (RA). The discovery of anticitrullinated protein antibodies in the last century has changed this and other posttranslational modifications (PTM) relevant to RA have since been described. Such PTM introduce neoepitopes in proteins that can generate novel autoantibody specificities. The recent recognition of these novel specificities in RA provides a unique opportunity to understand human B-cell development in vivo. In this paper, we will review the three of the main classes of PTMs already associated with RA: citrullination, carbamylation, and oxidation. With the advancement of research methodologies it should be expected that other autoantibodies against PTM proteins could be discovered in patients with autoimmune diseases. Many of such autoantibodies may provide significant biomarker potential.

Autoantibodies to posttranslationally modified type II collagen as potential biomarkers for rheumatoid arthritis

OBJECTIVE

Type II collagen (CII) posttranslationally modified by reactive oxygen species (ROS-CII) that are present in the inflamed joint is an autoantigen in rheumatoid arthritis (RA). The aim of this study was to investigate the potential use of anti-ROS-CII autoantibodies as a biomarker of RA.

METHODS

CII was exposed to oxidants that are present in the rheumatoid joint. Autoreactivity to ROS-CII was assessed by enzyme-linked immunosorbent assays in synovial fluid (SF) and serum samples obtained from patients during various phases of RA. This group included disease-modifying antirheumatic drug (DMARD)-naive patients with early RA (n = 85 serum samples) and patients with established RA (n = 80 serum and 50 SF samples), who were categorized as either DMARD responders or DMARD nonresponders. Control subjects included anti-citrullinated protein antibody (ACPA)-positive patients with arthralgia (n = 58 serum samples), patients with osteoarthritis (OA; n = 49 serum and 52 SF samples), and healthy individuals (n = 51 serum samples).

RESULTS

Reactivity to ROS-CII among DMARD-naive patients with early RA was significantly higher than that among patients with ACPA-positive arthralgia, patients with OA, and healthy control subjects (P < 0.0001), with 92.9% of serum samples from the patients with early RA binding to anti-ROS-II. There was no significant difference in anti-ROS-CII reactivity between ACPA-positive and ACPA-negative patients with RA, with 93.8% and 91.6% of serum samples, respectively, binding to ROS-CII. The sensitivity and specificity of binding to ROS-CII in patients with early RA were 92% and 98%, respectively. Among patients with established RA, serum reactivity in DMARD nonresponders was significantly higher than that in DMARD responders (P < 0.01); 58.3% of serum samples from nonresponders and 7.6% of serum samples from responders bound to HOCl-ROS, while the respective values for SF were 70% and 60%. In patients with longstanding RA, autoreactivity to ROS-CII changed longitudinally.

CONCLUSION

Autoantibodies to ROS-CII have the potential to become diagnostic biomarkers of RA.

Current therapeutic leads for the treatment of autoimmune diseases: stem cell transplantation and inhibition of post-translational modifications of autoantigens

BACKGROUND

The complexity of autoimmune diseases is reflected on their clinicopathological heterogeneity and the failure to find treatments that cure them after over a century of research. Conventional treatments help ameliorate disease activity but they treat the symptoms whereas the diseases remain incurable in the vast majority of patients.

OBJECTIVE

To confront diseases of such nature it is essential to discover therapeutics that will lead to the induction of tolerance or the specific deletion of autoreactive lymphocytes. Current basic and clinical research strategies focus on the better identification of self-antigens, the induction of T regulatory cells that can suppress autoreactive cell activities or, more radically, the 'reformatting' of the immune system through hematopoietic stem cell transplantation (HSCT).

METHODS

We analyzed literature on autoimmune disease therapeutics, focusing on new antigens that may arise from post-translational modifications of common proteins and, also, the area of HSCT.

RESULTS/CONCLUSIONS

With the recent discovery that citrullination of self-epitopes may be a major pathogenic mechanism for, at least, certain types of autoimmune diseases, it becomes apparent that potentially any self-antigen in the body can be a target of an autoimmune attack. In addition, although the available data on HSCT applied to patients suffering from severe refractory autoimmune diseases do not allow for the determination of the efficacy of the various methods employed to re-educate the immune system, they contribute to our understanding of disease pathogenesis and the improvement on the therapeutic approaches.

HLA-dependent autoantibodies against post-translationally modified collagen type II in type 1 diabetes mellitus

AIMS/HYPOTHESIS

In this study the involvement of oxidative stress in type 1 diabetes mellitus autoimmunity and the possible association with rheumatoid arthritis (RA) was investigated. We tested the hypothesis that oxidative stress induced by chronic hyperglycaemia triggers post-translational modifications and thus the formation of neo-antigens in type 1 diabetes, similar to the ones found in RA.

METHODS

Collagen type II (CII), a known autoantigen in RA, was treated with ribose and various reactive oxygen species (ROS). Levels of antibodies specific to native and ROS-modified CII (ROS-CII) were compared in type 1 diabetes, type 2 diabetes and healthy controls, and related to the HLA genotype.

RESULTS

Significantly higher binding to ROS-CII vs native CII was observed in type 1 diabetic patients possessing the HLA-DRB1*04 allele irrespective of variables of glucose control (blood glucose or HbA(1c)). Type 1 diabetic patients carrying a DRB1*04 allele with the shared epitope showed the highest risk for ROS-CII autoimmunity, while the DRB1*0301 allele was protective. Conversely, native CII autoimmunity was not associated with any specific DRB1 allele. Positive and inverse seroconversion rates of response to ROS-CII were high in DRB1*04-positive type 1 diabetic patients.

CONCLUSION

Hyperglycaemia and oxidative stress may trigger genetically controlled autoimmunity to ROS-CII and may explain the association between type 1 diabetes mellitus and RA.

New advances of microRNAs in the pathogenesis of rheumatoid arthritis, with a focus on the crosstalk between DNA methylation and the microRNA machinery

Rheumatoid arthritis (RA) is a symmetrical polyarticular disease of unknown aetiology that affects primarily the articular cartilage and bone. Characteristic features of RA pathogenesis are persistent inflammation, synovium hyperplasia and cartilage erosion accompanied by joint swelling and joint destruction. Several lines of evidence have showed a crucial role of activated fibroblast-like synoviocytes (FLS) in the pathogenesis of RA. MicroRNAs (miRNAs) are endogenous, single-stranded, non-coding RNAs with about 21 nucleotides in length and have been detected in a variety of sources, including tissues, serum, and other body fluids, such as saliva. In light of key roles of miRNAs in the regulation of gene expression, miRNAs influence a wide range of physiological and pathological processes. For example, miRNAs are evident in various malignant and nonmalignant diseases, and accumulating evidence also shows that miRNAs have important roles in the pathogenesis of RA. It has been demonstrated that miRNAs can be aberrantly expressed even in the different stages of RA progression, allowing miRNAs to help understand the pathogenesis of the disease, to act as important biomarkers, and to monitor the disease severity and the effects of drug treatment. In addition, miRNAs are emerging as potential targets for new therapeutic strategies of this kind of autoimmune disorders. The ultimate goal is the identification of miRNA targets that could be manipulated through specific therapies, aiming at activation or inhibition of specific miRNAs responsible for the RA development. In this review, the importance of miRNAs in the pathogenesis of RA is discussed systematically, with particular emphasis on the role of the crosstalk between DNA methylation and the microRNA machinery.

Antigen-specific blocking of CD4-specific immunological synapse formation using BPI and current therapies for autoimmune diseases

In this review, we discuss T-cell activation, etiology, and the current therapies of autoimmune diseases (i.e., MS, T1D, and RA). T-cells are activated upon interaction with antigen-presenting cells (APC) followed by a "bull's eye"-like formation of the immunological synapse (IS) at the T-cell-APC interface. Although the various disease-modifying therapies developed so far have been shown to modulate the IS and thus help in the management of these diseases, they are also known to present some undesirable side effects. In this study, we describe a novel and selective way to suppress autoimmunity by using a bifunctional peptide inhibitor (BPI). BPI uses an intercellular adhesion molecule-1 (ICAM-1)-binding peptide to target antigenic peptides (e.g., proteolipid peptide, glutamic acid decarboxylase, and type II collagen) to the APC and therefore modulate the immune response. The central hypothesis is that BPI blocks the IS formation by simultaneously binding to major histocompatibility complex-II and ICAM-1 on the APC and selectively alters the activation of T cells from T(H)1 to T(reg) and/or T(H)2 phenotypes, leading to tolerance.

Hydroxyl radical modification of collagen type II increases its arthritogenicity and immunogenicity

Background

The oxidation of proteins by endogenously generated free radicals causes structural modifications in the molecules that lead to generation of neo-antigenic epitopes that have implications in various autoimmune disorders, including rheumatoid arthritis (RA). Collagen induced arthritis (CIA) in rodents (rats and mice) is an accepted experimental model for RA.

Methodology/Principal Findings

Hydroxyl radicals were generated by the Fenton reaction. Collagen type II (CII) was modified by ^•OH radical (CII-OH) and analysed by ultraviolet-visible (UV-VIS), fluorescence and circular dichroism (CD) spectroscopy. The immunogenicity of native and modified CII was checked in female Lewis rats and specificity of the induced antibodies was ascertained by enzyme linked immunosorbent assay (ELISA). The extent of CIA was evaluated by visual inspection. We also estimated the oxidative and inflammatory markers in the sera of immunized rats. A slight change in the triple helical structure of CII as well as fragmentation was observed after hydroxyl radical modification. The modified CII was found to be highly arthritogenic and immunogenic as compared to the native form. The CII-OH immunized rats exhibited increased oxidative stress and inflammation as compared to the CII immunized rats in the control group.

Conclusions/Significance

Neo-antigenic epitopes were generated on ^•OH modified CII which rendered it highly immunogenic and arthritogenic as compared to the unmodified form. Since the rodent CIA model shares many features with human RA, these results illuminate the role of free radicals in human RA.

Collagen induced arthritis (CIA) in mice features regulatory transcriptional network connecting major histocompatibility complex (MHC H2) with autoantigen genes in the thymus

Considering that imbalance of central tolerance in the thymus contributes to aggressive autoimmunity, we compared the expression of peripheral tissue autoantigens (PTA) genes, which are involved in self-representation in the thymic stroma, of two mouse strains; DBA-1/J (MHC-H2(q)) susceptible and DBA-2/J (MHC-H2(d)) resistant to collagen induced arthritis (CIA). We evaluate whether these strains differ in their thymic gene expression, allowing identification of genes that might play a role in susceptibility/resistance to CIA. Microarray profiling showed that 1093 PTA genes were differentially modulated between collagen immunized DBA-1/J and DBA-2/J mice. These genes were assigned to 17 different tissues/organs, including joints/bone, characterizing the promiscuous gene expression (PGE), which is implicated in self-representation. Hierarchical clustering of microarray data and quantitative RT-PCR analysis showed that Aire (autoimmune regulator), an important regulator of the PGE process, Aire-dependent (insulin), Aire-independent (Col2A1 and Gad67), and other 22 joint/bone autoantigen genes were down-regulated in DBA-1/J compared with DBA-2/J in the thymus. Considering the importance of MHC-H2 in peptide-self presentation and autoimmunity susceptibility, we reconstructed transcriptional networks of both strains based on actual microarray data. The networks clearly demonstrated different MHC-H2 transcriptional interactions with PTAs genes. DBA-1/J strain featured MHC-H2 as a node influencing downstream genes. Differently, in DBA-2/J strain network MHC-H2 was exclusively self-regulated and does not control other genes. These findings provide evidence that CIA susceptibility in mice may be a reflex of a cascade-like transcriptional control connecting different genes to MHC-H2 in the thymus.

Cell carriers as the next generation of cell therapy for cartilage repair: a review of the matrix-induced autologous chondrocyte implantation procedure

BACKGROUND

Since the first patient was implanted with autologous cultured chondrocytes more than 20 years ago, new variations of cell therapies for cartilage repair have appeared. Autologous chondrocyte implantation, a first-generation cell therapy, uses suspended autologous cultured chondrocytes in combination with a periosteal patch. Collagen-covered autologous cultured chondrocyte implantation, a second-generation cell therapy, uses suspended cultured chondrocytes with a collagen type I/III membrane. Today's demand for transarthroscopic procedures has resulted in the development of third-generation cell therapies that deliver autologous cultured chondrocytes using cell carriers or cell-seeded scaffolds.

PURPOSE

To review the current evidence of the matrix-induced autologous chondrocyte implantation procedure, the most widely used carrier system to date. Also discussed are the characteristics of type I/III collagen membranes, behavior of cells associated with the membrane, surgical technique, rehabilitation, clinical outcomes, and quality of repair tissue.

STUDY DESIGN

Systematic review.

METHODS

Relevant publications were identified by searching Medline from its inception (1949) to December 2007; peer-reviewed publications of preclinical and clinical cell behavior, manufacturing process, surgical technique, and rehabilitation protocols were identified. Preclinical and clinical studies were included if they contained primary data and used a type I/III collagen membrane.

RESULTS

Data from these studies demonstrate that patients treated with matrix-induced autologous chondrocyte implantation have an overall improvement in clinical outcomes. Reduced visual analog scale pain levels (range, 1.7-5.32 points) and improvements in the modified Cincinnati (range, 3.8-34.2 points), Lysholm-Gillquist (range, 23.09-47.6 points), Tegner-Lysholm (range, 1.39-3.9 points), and International Knee Documentation Classification scale (P <.05) were observed. Patients had good-quality (hyaline-like) repair tissue as assessed by arthroscopic evaluation (including International Cartilage Repair Society score), magnetic resonance imaging, and histology, as well as a low incidence of postoperative complications.

CONCLUSION

The findings suggest that matrix-induced autologous chondrocyte implantation is a promising third-generation cell therapy for the repair of symptomatic, full-thickness articular cartilage defects.

Treatment of collagen-induced arthritis by Natura-alpha via regulation of Th-1/Th-17 responses

Cytokines and CD4(+) Th cells play a crucial role in the pathogenesis of rheumatoid arthritis. Among the Th populations, Th-1 and Th-17 have been described as pathogenic in collagen-induced arthritis (CIA) whereas Th-2 and Treg were found to have protective effects. The objective of this study was to examine the affect of Natura-alpha, a newly developed cytokine regulator, on CIA and on Th cell development. Natura-alpha treatment was administered before or during arthritis induction. Anti-type II collagen antibodies and cytokine expression were evaluated by ELISA. Emergence of CD4(+)CD25(+)Foxp3(+) T cells was assessed by flow cytometry. Th-17 differentiation of naive CD4 T cells was assessed in cultures with anti-CD3 and anti-CD28. We showed that Natura-alpha both prevented and treated CIA. We further demonstrated that in vivo treatment with Natura-alpha inhibited IL-17 production and anti-type II collagen IgG development. We showed in vitro, using an APC-free system, that Natura-alpha acted directly on differentiating T cells and inhibiting the formation of Th-1 and Th-17 cells but did not affect Th-2 cells. Since Natura-alpha inhibits a large spectrum of important pathogenic factors in CIA, it may provide a new and powerful approach to the treatment of rheumatoid arthritis and other inflammatory diseases.

Tolerance induction using lentiviral gene delivery delays onset and severity of collagen II arthritis

The treatment of rheumatoid arthritis remains suboptimal; thus there is considerable interest in the development of strategies that mediate tolerance to autoantigens. Using lentiviral gene transfer in vivo, we expressed the immunodominant epitope of collagen type II (CII) on major histocompatibility complex class II molecules (MHC II) in a mouse model of destructive arthritis. A sequence corresponding to amino acids 259-270 of CII was fused into the class II-associated invariant chain peptide (CLIP) position of the invariant chain to achieve efficient binding to MHC II. Transduction of cloned cells and primary antigen-presenting cells (APCs) in vitro demonstrated successful presentation of the peptide on MHC II, and a physiological glycosylation pattern. Compared with controls, mice intravenously injected with lentiviral vectors encoding this epitope displayed significantly less frequent, less severe, and less destructive arthritis, decreased lymphocyte proliferation in response to restimulation with CII, and lower CII-specific antibody levels. This was associated with an increased production of transforming growth factor-beta (TGF-beta) in vitro. We suggest that overexpression of the immunodominant CII epitope on MHC II induces T cell production of TGF-beta and leads to inhibition of arthritis by means of both antigen-specific and bystander mechanisms. Thus, antigen-specific tolerance induction using lentiviral gene delivery can ameliorate arthritis.

Construction and characterization of a novel DNA vaccine that is potent antigen-specific tolerizing therapy for experimental arthritis by increasing CD4+CD25+Treg cells and inducing Th1 to Th2 shift in both cells and cytokines

Currently available treatments for rheumatoid arthritis (RA) are often ineffective in ameliorating the progression of disease, particularly the invasive destruction of articular cartilage and bone, and RA remains incurable. Therefore, vaccinotherapy of RA with an antigen-specific tolerizing DNA vaccine may offer new promise for overcoming this difficulty. Using recombinant technology, the DNA sequences encoding chicken type II collagen (CCOL2A1) with deleted N-propeptides were obtained from the plasmid pPIC9K/pCalpha(1)(II), and then cloned into pcDNA3.1(+). The resulting recombinant plasmid pcDNA-CCOL2A1 was produced in Escherichia coli, purified, characterized and used as a tolerizing DNA vaccine for the treatment of collagen-induced arthritis (CIA). Therapeutic efficacy and potential action mechanisms of pcDNA-CCOL2A1 tolerizing DNA vaccine against CIA were studied. Here we demonstrate that a single intravenous treatment with novel tolerizing DNA vaccine pcDNA-CCOL2A1 can induce potent immune tolerance against CIA. The efficacy of this therapy was verified by clinical visual scoring, radiographic X-ray, histopathological examination, and anti-CII IgG levels. Furthermore, the action mechanism behind this efficacy can be at least partially attributed to increased CD4(+)CD25(+) T regulatory cells, which specifically down-modulate the T lymphocyte proliferative response to CCII, induce a shift of Th1 to Th2 cells, as well as down-regulate Th1-cytokine TNF-alpha, while up-regulating both Th2-cytokine IL-10 and Th3-cytokine TGF-beta. More importantly, pcDNA-CCOL2A1 alone seems to be as effective as the current "golden standard" treatment, methotrexate (MTX). Taken together, these results suggest that we have successfully developed a novel tolerizing DNA vaccine encoding CCII, which is the first description of a tolerizing DNA vaccine encoding CCII for antigen-specific tolerizing therapy but not prophylactic against CIA.

A novel recombinant peptide containing only two T-cell tolerance epitopes of chicken type II collagen that suppresses collagen-induced arthritis

Immunotherapy of rheumatoid arthritis (RA) using oral-dosed native chicken or bovine type II collagen (nCII) to induce specific immune tolerance is an attractive strategy. However, the majority of clinical trials of oral tolerance in human diseases including RA in recent years have been disappointing. Here, we describe a novel recombinant peptide rcCTE1-2 which contains only two tolerogenic epitopes (CTE1 and CTE2) of chicken type II collagen (cCII). These are the critical T-cell determinants for suppression of RA that were first developed and used to compare its suppressive effects with ncCII on the collagen-induced arthritis (CIA) model. The rcCTE1-2 was produced using the prokaryotic pET expression system and purified by Ni-NTA His affinity chromatography. Strikingly, our results showed clearly that rcCTE1-2 was as efficacious as ncCII at the dose of 50 microg/kg/d. This dose significantly reduced footpad swelling, arthritic incidence and scores, and deferred the onset of disease. Furthermore, rcCTE1-2 of 50 microg/kg/d could lower the level of anti-nCII antibody in the serum of CIA animals, decrease Th1-cytokine INF-gamma level, and increase Th3-cytokine TGF-beta(1) produced level by spleen cells from CIA mice after in vivo stimulation with ncCII. Importantly, rcCTE1-2 was even more potent than native cCII, which was used in the clinic for RA. Equally importantly, the findings that the major T-cell determinants of cCII that are also recognized by H-2(b) MHC-restricted T cells have not previously been reported. Taken together, these results suggest that we have successfully developed a novel recombinant peptide rcCTE1-2 that can induce a potent tolerogenic response in CIA.

Interactions of T cells with fibroblast-like synoviocytes: role of the B7 family costimulatory ligand B7-H3

Fibroblast-like synoviocytes (FLS) and T cells can activate each other in vitro, and in vivo interactions between these cells may be important in rheumatoid arthritis (RA), yet FLS lack significant expression of CD28 ligands. We sought to identify molecules homologous to CD28 ligands that are strongly expressed by FLS, and documented strong B7-H3 expression on FLS and by fibroblasts of other tissues, which was unaffected by a variety of cytokines. Western blot analysis of FLS lysates showed predominant expression of the larger, four Ig-like domain isoform of B7-H3. Immunohistological sections of RA synovial tissue showed strong staining for B7-H3 on FLS. Cells expressing B7-H3 were distinct from but in close proximity to cells that expressed CD45, CD20, and CD3. Confocal microscopy of FLS and T cell cocultures showed localization of B7-H3 in the region of the T cell-FLS contact point, but distinct from the localization of T cell CD11a/CD18 (LFA-1) and FLS CD54 (ICAM-1). Reduction of B7-H3 expression on FLS by RNA interference affected interactions of FLS with resting T cells or cytokine-activated T cells. Resting T cells showed increased production of TNF-alpha, IFN-gamma, and IL-2, whereas cytokine-activated T cells showed reduced cytokine production relative to control. However, cytokine production by T cells activated through their TCR was not notably altered by knock down of B7-H3. These observations suggest that B7-H3 may be important for the interactions between FLS and T cells in RA, as well as other diseases, and the outcome of such interactions depends on the activation state of the T cell.

Insights into spatial configuration of a galactosylated epitope required to trigger arthritogenic T-cell receptors specific for the sugar moiety

The immunodominant epitope of bovine type II collagen (CII256–270) in A^q mice carries a hydroxylysine-264 linked galactose (Gal-Hyl²⁶⁴), the recognition of which is central to the development of collagen-induced arthritis. This study explores the molecular interactions involved in the engagement of T-cell receptors (TCRs) with such epitopes. Responses of three anti-CII T-cell hybridomas and clone A9.2 (all sharing close TCR sequences) to a panel of CII256–270 analogues incorporating Gal-Hyl²⁶⁴ with a modified side chain were determined. Recognition of naturally occurring CII256–270 peptides by either group of T cells depended strictly upon the presence of the carbohydrate and, more precisely, its intact HO-4 group. Modifications of primary amino group on the hydroxylysine side chain eliminated T-cell reactivity, notwithstanding the presence of the galactosyl moiety. Moderate stereochemical changes, such as altered sugar orientation and methylation at the galactose anchor position, were still permissive. Conversely, robust transformations affecting the relative positions of the key elements were detrimental to TCR recognition. To conclude, these data provide strong new experimental evidence that integrity of both galactose HO-4 and hydroxylysine side chain primary amino groups are mandatory for activation of anti-Gal-Hyl²⁶⁴ TCRs. They also indicate that there is a certain degree of TCR plasticity in peptide-TCR interactions.

MHC class II derived recombinant T cell receptor ligands protect DBA/1LacJ mice from collagen-induced arthritis

We previously demonstrated the therapeutic effects of MHC class II derived recombinant T cell receptor ligands (RTL), single-chain two domain complexes of the alpha1 and beta1 domains of MHC class II molecules genetically linked with an immunodominant peptide, in experimental autoimmune encephalomyelitis. In the current study, we produced a monomeric murine I-Aq-derived RTL construct covalently linked with bovine collagen type II peptide (bCII257-270) suitable for use in DBA/1LacJ mice that develop collagen-induced arthritis (CIA), an animal model of human rheumatoid arthritis, after immunization with bCII protein in CFA. In this study, we demonstrate that the I-Aq-derived RTLs reduced the incidence of the disease, suppressed the clinical and histological signs of CIA and induced long-term modulation of T cells specific for arthritogenic Ags. Our results showed that the I-Aq/bCII257-270 molecule could systemically reduce proinflammatory IL-17 and IFN-gamma production and significantly increase anti-inflammatory IL-10, IL-13, and FoxP3 gene expression in splenocytes. Moreover, I-Aq/bCII257-270 molecule could also selectively inhibit IL-1beta, IL-6, and IL-23 expression in local joint tissue. This is the first report demonstrating effective prevention of joint inflammation and clinical signs of CIA with an I-Aq-derived RTL, thus supporting the possible clinical use of this approach for treating rheumatoid arthritis in humans.

Antigen-specific therapy of rheumatoid arthritis

BACKGROUND

Immunotherapy offers the promise of antigen-specific suppression of pathological immune responses in conditions such as autoimmunity and organ transplantation. Substantial advances have been made in recent years in terms of understanding basic immunological mechanisms of autoreactivity, as well as clinically implementing immune-based therapies that are antigen nonspecific.

OBJECTIVE

To provide an integrated overview of the current state of the art in terms of antigen-specific tolerance induction, as well as to predict future directions for the field.

METHODS

Examples of successes and failures of antigen-specific immunotherapy were sought. Particular attention was paid to the well-established collagen II-induced model of arthritis.

RESULTS/CONCLUSIONS

Previous failures of antigen-specific immunotherapy were associated with lack of identification of clinically relevant antigens, as well as inappropriate tolerogenic methodologies. The advances in proteomics combined with novel gene-specific immune modulatory techniques place today's translational researchers in a unique position to tackle the problem of antigen-specific immunotherapeutic protocols.

Molecular interactions between T cells and fibroblast-like synoviocytes: role of membrane tumor necrosis factor-alpha on cytokine-activated T cells

The mechanism of fibroblast-like synoviocyte (FLS) transformation into an inflammatory phenotype in rheumatoid arthritis (RA) is not fully understood. FLS interactions with invading leukocytes, particularly T cells, are thought to be a critical component of this pathological process. Resting T cells and T cells activated through the T-cell receptor have previously been shown to induce inflammatory cytokine production by FLS. More recently, a distinct population of T cells has been identified in RA synovium that phenotypically resembles cytokine-activated T (Tck) cells. Using time lapse microscopy, the interactions of resting, superantigen-activated, and cytokine-activated T cells with FLS were visualized. Rapid and robust adhesion of Tck and superantigen-activated T cells to FLS was observed that resulted in flattening of the T cells and a crawling movement on the FLS surface. Tck also readily activated FLS to produce interleukin IL-6 and IL-8 in a cell contact-dependent manner that was enhanced by exogenous IL-17. Although LFA-1 and ICAM-1 co-localized at the Tck-FLS synapse, blocking the LFA-1/ICAM-1 interaction did not substantially inhibit Tck effector function. However, antibody blocking of membrane tumor necrosis factor (TNF)-alpha on the Tck surface did inhibit FLS cytokine production, thus illustrating a novel mechanism for involvement of TNF-alpha in cell-cell interactions in RA synovium and for the effectiveness of TNF-alpha blockade in the treatment of RA.

Type II collagen autoimmunity in a mouse model of human rheumatoid arthritis

Type II collagen (CII) is expressed exclusively in the joint articular. Although the relationship between anti-CII immunity and human rheumatoid arthritis (RA) has been studied for a long time, definitive conclusions have not been reached. CII, as an autoantigen, has been studied extensively in small animal models, such as mice, and the collagen-induced arthritis (CIA) model has increased our understanding of the pathogenesis of human RA. In the present report, we summarize the available information on anti-CII immunity and discuss recent updates regarding pathogenesis in the CIA model, including the role of Th17 cells.

Presentation of arthritogenic peptide to antigen-specific T cells by fibroblast-like synoviocytes

OBJECTIVE

To assess the ability of rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) to function as antigen-presenting cells (APCs) for arthritogenic autoantigens found within inflamed joint tissues.

METHODS

Human class II major histocompatibility complex (MHC)-typed FLS were used as APCs for murine class II MHC-restricted CD4 T cell hybridomas. Interferon-gamma (IFNgamma)-treated, antigen-loaded FLS were cocultured with T cell hybridomas specific for immunodominant portions of human cartilage gp-39 (HC gp-39) or human type II collagen (CII). T cell hybridoma activation was measured by enzyme-linked immunosorbent assay of culture supernatants for interleukin-2. Both synthetic peptide and synovial fluid (SF) were used as sources of antigen. APC function in cocultures was inhibited by using blocking antibodies to human class II MHC, CD54, or CD58, or to murine CD4, CD11a, or CD2.

RESULTS

Human FLS could present peptides from the autoantigens HC gp-39 and human CII to antigen-specific MHC-restricted T cell hybridomas. This response required pretreatment of FLS with IFNgamma, showed MHC restriction, and was dependent on human class II MHC and murine CD4 for effective antigen presentation. Furthermore, FLS were able to extract and present antigens found within human SF to both the HC gp-39 and human CII T cell hybridomas in an IFNgamma-dependent and MHC-restricted manner.

CONCLUSION

RA FLS can function as APCs and are able to present peptides derived from autoantigens found within joint tissues to activated T cells in vitro. In the context of inflamed synovial tissues, FLS may be an important and hitherto overlooked subset of APCs that could contribute to autoreactive immune responses.

A mechanistic approach to understanding conjugated linoleic acid's role in inflammation using murine models of rheumatoid arthritis

A naturally occurring fatty acid, conjugated linoleic acid (CLA), reduces immune-induced TNF and inducible cyclooxygenase (COX-2) expression; key mediators of inflammation in rheumatoid arthritis (RA). On the basis of previous work, it was hypothesized that dietary CLA would act as an anti-inflammatory agent in select animal models of RA. In the collagen antibody-induced arthritis (CAIA) model, mice fed CLA (mixed isomers of c9, t11, and t10, c12-CLA) for 3 wk before anticollagen antibody injection had reduced lipopolysaccharide-induced plasma TNF levels and had arthritic scores that were 60% of mice fed corn oil (CO). In the collagen-induced arthritis (CIA) model, mice fed mixed isomers of CLA for 21 days before immunization had lower IgG(1) titers, earlier signs of joint inflammation, but similar arthritis scores compared with CO fed mice during the remaining 70-day post-injection period. Beginning on day 80 to 133, CLA-fed mice had arthritic scores 70% that of the CO-fed mice. In a second CIA experiment, CLA was fed only after the booster injection. Plasma IgG(1) levels were not reduced and arthritis onset was delayed 4 days in CLA-fed mice compared with the CO-fed mice. Peak arthritis score was similar between CLA and CO-fed mice from day 35 to 56. Because CLA reduced inflammation in the CAIA model, delayed onset of arthritis in the CIA model (CIA experiment 2) and reduced arthritis score after day 80 in the CIA model (CIA experiment 1), we concluded that dietary CLA exhibited anti-inflammatory activity that was dependent on antibody.

Identification of novel citrullinated autoantigens of synovium in rheumatoid arthritis using a proteomic approach

Recently, autoantibodies to some citrullinated autoantigens have been reported to be specific for rheumatoid arthritis (RA). However, an entire profile of and autoimmunity of the citrullinated proteins have been poorly understood. To understand the profile, we examined citrullinated autoantigens by a proteomic approach and further investigated the significance of citrullination in antigenicity of one of the autoantigens. Specifically, we detected citrullinated autoantigens in synovial tissue of a patient with RA by two-dimensional electrophoresis and Western blotting by using pooled sera from five patients with RA and anti-citrulline antibodies. After identifying the detected autoantigens by mass spectrometry, we investigated the contribution of citrullination to autoantigenicity by using a recombinant protein with or without citrullination on one of the identified novel citrullinated autoantigens. As a result, we found 51 citrullinated protein spots. Thirty (58.8%) of these spots were autoantigenic. We identified 13 out of the 30 detected citrullinated autoantigenic proteins. They contained three fibrinogen derivatives and several novel citrullinated autoantigens (for example, asporin and F-actin capping protein α-1 subunit [CapZα-1]). We further analyzed the contribution of citrullination to autoantigenicity in one of the detected citrullinated autoantigens, CapZα-1. As a result, frequencies of autoantibodies to non-citrullinated CapZα-1 were 36.7% in the RA group tested, 10.7% in the osteoarthritis (OA) group, and 6.5% in healthy donors. On the other hand, those to citrullinated CapZα-1 were 53.3% in the RA group, 7.1% in the OA group, and 6.5% in the healthy donors. This shows that autoantigenicity of citrullinated or non-citrullinated CapZα-1 is relevant to RA. The antibody titers to the citrullinated CapZα-1 were significantly higher than those to the non-citrullinated CapZα-1 in 36.7% of patients; however, the other patients showed almost equal antibody titers to both citrullinated and non-citrullinated CapZα-1. Therefore, the autoantibodies would target citrulline-related and/or citrulline-unrelated epitope(s) of CapZα-1. In conclusion, we report a profile of citrullinated autoantigens for the first time. Even though citrullination is closely related to autoantigenicity, citrullination would not always produce autoantigenicity in RA. Citrullinated and non-citrullinated autoantigens/autoepitopes would have different pathological roles in RA.

Inhibition of macropinocytosis blocks antigen presentation of type II collagen in vitro and in vivo in HLA-DR1 transgenic mice

Professional antigen-presenting cells, such as dendritic cells, macrophages and B cells have been implicated in the pathogenesis of rheumatoid arthritis, constituting a possible target for antigen-specific immunotherapy. We addressed the possibility of blocking antigen presentation of the type II collagen (CII)-derived immunodominant arthritogenic epitope CII_259–273 to specific CD4 T cells by inhibition of antigen uptake in HLA-DR1-transgenic mice in vitro and in vivo. Electron microscopy, confocal microscopy, subcellular fractionation and antigen presentation assays were used to establish the mechanisms of uptake, intracellular localization and antigen presentation of CII by dendritic cells and macrophages. We show that CII accumulated in membrane fractions of intermediate density corresponding to late endosomes. Treatment of dendritic cells and macrophages with cytochalasin D or amiloride prevented the intracellular appearance of CII and blocked antigen presentation of CII_259–273 to HLA-DR1-restricted T cell hybridomas. The data suggest that CII was taken up by dendritic cells and macrophages predominantly via macropinocytosis. Administration of amiloride in vivo prevented activation of CII-specific polyclonal T cells in the draining popliteal lymph nodes. This study suggests that selective targeting of CII internalization in professional antigen-presenting cells prevents activation of autoimmune T cells, constituting a novel therapeutic strategy for the immunotherapy of rheumatoid arthritis.

Surface-bound anti-type II collagen-containing immune complexes induce production of tumor necrosis factor alpha, interleukin-1beta, and interleukin-8 from peripheral blood monocytes via Fc gamma receptor IIA: a potential pathophysiologic mechanism for humoral anti-type II collagen immunity in arthritis

OBJECTIVE

Type II collagen (CII) is a major component of hyaline cartilage, and antibodies against CII are found in a subgroup of patients with rheumatoid arthritis. We undertook this study to investigate whether and how antibodies directed against CII can form solid-phase immune complexes (ICs) with cytokine-inducing properties in a model theoretically resembling the situation in the inflamed joint, in which CII is exposed for interaction with anti-CII antibodies during periods of inflammation.

METHODS

Sixty-five arthritis patients with varying levels of anti-native CII antibodies and 10 healthy controls were evaluated concerning anti-CII and cytokines induced in a solid-phase IC model. Monocytes were either depleted or enriched to define responder cells. Antibodies blocking Fc gamma receptors (Fc gammaR) were used to define the responsible T cell surface receptors.

RESULTS

ICs containing anti-CII from arthritis patients induced the production of tumor necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), and IL-8. We found a close correlation between enzyme-linked immunosorbent assay optical density values and induction of TNFalpha (r = 0.862, P < 0.0001), IL-1beta (r = 0.839, P < 0.0001), and IL-8 (r = 0.547, P < 0.0001). The anti-CII-containing IC density threshold needed for cytokine induction differed among peripheral blood mononuclear cell donors. Anti-CII-containing IC-induced cytokine production was almost totally abolished (>99%) after monocyte depletion, and receptor blocking studies showed significant decreases in the production of TNFalpha, IL-1beta, and IL-8 after blocking Fc gammaRIIa, but not after blocking Fc gammaRIII.

CONCLUSION

These findings represent a possible mechanism for perpetuation of joint inflammation in the subgroup of arthritis patients with high levels of anti-CII. Blockade of Fc gammaRIIa and suppression of synovial macrophages are conceivable treatment options in such patients.

Generation of neoantigenic epitopes after posttranslational modification of type II collagen by factors present within the inflamed joint

OBJECTIVE

Collagen-induced arthritis is a commonly accepted model of rheumatoid arthritis (RA). However, it has been difficult to substantiate the involvement of autoimmunity to type II collagen (CII) in the pathogenesis of RA. The aim of this investigation was to determine if CII, modified by reactive oxidant species present within the inflamed joint, could generate neoantigenic epitopes.

METHODS

Oxidants that play a role in acute and chronic inflammation and are present in the rheumatoid joint (hydroxyl radical, hypochlorous acid, and peroxynitrite) were used for modification of native CII. In addition, CII was glycated with ribose, since nonenzymatic oxidative reactions by glycation are evident in RA. Modifications were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 3-dimensional fluorescence followed by enzyme-linked immunosorbent assay (ELISA) and Western blotting, using, as probes, sera from patients with RA and from patients with other inflammatory and noninflammatory joint diseases.

RESULTS

Only 1 RA serum sample showed strong binding to native CII. In contrast, binding to modified CII was increased in 14 of 31 RA sera, of which 7 were strong binders and 7 were moderate binders. Among the non-RA serum samples, only 1 yielded a strong reaction to modified CII and 5 of 41 were moderate binders. Samples that showed the strongest binding to modified CII in ELISA also showed strong binding to various fragmented or aggregated forms of CII in Western blots, as well as strong binding to fragmented CII present in RA synovial fluid.

CONCLUSION

When modified by conditions found within the inflamed joint, CII acts as an autoantigen in RA.