Characterization of recombinant type II collagen: arthritogenicity and tolerogenicity in DBA/1 mice

Green biomanufacturing in recombinant collagen biosynthesis: trends and selection in various expression systems

Collagen, classically derived from animal tissue, is an all-important protein material widely used in biomedical materials, cosmetics, fodder, food, etc. The production of recombinant collagen through different biological expression systems using bioengineering techniques has attracted significant interest in consideration of increasing market demand and the process complexity of extraction. Green biomanufacturing of recombinant collagen has become one of the focus topics. While the bioproduction of recombinant collagens (type I, II, III, etc.) has been commercialized in recent years, the biosynthesis of recombinant collagen is extremely challenging due to protein immunogenicity, yield, degradation, and other issues. The rapid development of synthetic biology allows us to perform a heterologous expression of proteins in diverse expression systems, thus optimizing the production and bioactivities of recombinant collagen. This review describes the research progress in the bioproduction of recombinant collagen over the past two decades, focusing on different expression systems (prokaryotic organisms, yeasts, plants, insects, mammalian and human cells, etc.). We also discuss the challenges and future trends in developing market-competitive recombinant collagens.

Role of Citrullinated Collagen in Autoimmune Arthritis

Citrullination of proteins plays an important role in protein function and it has recently become clear that citrullinated proteins play a role in immune responses. In this study we examined how citrullinated collagen, an extracellular matrix protein, affects T-cell function during the development of autoimmune arthritis. Using an HLA-DR1 transgenic mouse model of rheumatoid arthritis, mice were treated intraperitoneally with either native type I collagen (CI), citrullinated CI (cit-CI), or phosphate buffered saline (PBS) prior to induction of autoimmune arthritis. While the mice given native CI had significantly less severe arthritis than controls administered PBS, mice receiving cit-CI had no decrease in the severity of autoimmune arthritis. Using Jurkat cells expressing the inhibitory receptor leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1), Western blot analysis indicated that while CI and cit-CI bound to LAIR-1 with similar affinity, only CI induced phosphorylation of the LAIR ITIM tyrosines; cit-CI was ineffective. These data suggest that cit-CI acts as an antagonist of LAIR-1 signaling, and that the severity of autoimmune arthritis can effectively be altered by targeting T cells with citrullinated collagen.

Safety and immunogenicity of a novel therapeutic DNA vaccine encoding chicken type II collagen for rheumatoid arthritis in normal rats

Current clinically available treatments for rheumatoid arthritis (RA) fail to cure the disease or unsatisfactorily halt disease progression. To overcome these limitations, the development of therapeutic DNA vaccines and boosters may offer new promising strategies. Because type II collagen (CII) as a critical autoantigen in RA and native chicken type II collagen (nCCII) has been used to effectively treat RA, we previously developed a novel therapeutic DNA vaccine encoding CCII (pcDNA-CCOL2A1) with efficacy comparable to that of the current "gold standard", methotrexate(MTX). Here, we systemically evaluated the safety and immunogenicity of the pcDNA-CCOL2A1 vaccine in normal Wistar rats. Group 1 received only a single intramuscular injection into the hind leg with pcDNA-CCOL2A1 at the maximum dosage of 3 mg/kg on day 0; Group 2 was injected with normal saline (NS) as a negative control. All rats were monitored daily for any systemic adverse events, reactions at the injection site, and changes in body weights. Plasma and tissues from all experimental rats were collected on day 14 for routine examinations of hematology and biochemistry parameters, anti-CII IgG antibody reactivity, and histopathology. Our results indicated clearly that at the maximum dosage of 3 mg/kg, the pcDNA-CCOL2A1 vaccine was safe and well-tolerated. No abnormal clinical signs or deaths occurred in the pcDNA-CCOL2A1 group compared with the NS group. Furthermore, no major alterations were observed in hematology, biochemistry, and histopathology, even at the maximum dose. In particularly, no anti-CII IgG antibodies were detected in vaccinated normal rats at 14 d after vaccination; this was relevant because we previously demonstrated that the pcDNA-CCOL2A1 vaccine, when administered at the therapeutic dosage of 300 μg/kg alone, did not induce anti-CII IgG antibody production and significantly reduced levels of anti-CII IgG antibodies in the plasma of rats with established collagen-induced arthritis (CIA). This is the first study demonstrating the safety and immunogenicity of a DNA vaccine encoding CCII for treating RA in normal rats. These results may support the use of this novel therapeutic DNA vaccine for the treatment of RA in the future.

Gene Therapy Induces Antigen-Specific Tolerance in Experimental Collagen-Induced Arthritis

Here, we investigate induction of immunological tolerance by lentiviral based gene therapy in a mouse model of rheumatoid arthritis, collagen II-induced arthritis (CIA). Targeting the expression of the collagen type II (CII) to antigen presenting cells (APCs) induced antigen-specific tolerance, where only 5% of the mice developed arthritis as compared with 95% of the control mice. In the CII-tolerized mice, the proportion of Tregs as well as mRNA expression of SOCS1 (suppressors of cytokine signaling 1) increased at day 3 after CII immunization. Transfer of B cells or non-B cell APC, as well as T cells, from tolerized to naïve mice all mediated a certain degree of tolerance. Thus, sustainable tolerance is established very early during the course of arthritis and is mediated by both B and non-B cells as APCs. This novel approach for inducing tolerance to disease specific antigens can be used for studying tolerance mechanisms, not only in CIA but also in other autoimmune diseases.

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.

Plant-made pharmaceuticals for the prevention and treatment of autoimmune diseases: where are we?

Molecular farming in plants or plant cell cultures represents a viable alternative technology that holds great promise for the low-cost and large-scale production of recombinant proteins. The particular case of plant-based vaccines for the prevention of autoimmune diseases is addressed here, presenting a comprehensive overview of the different molecules and expression technologies that have been investigated so far in both academia and industry. The potential of plants not only as bioreactors but also as delivery systems for pharmaceuticals is discussed, and the advantages of oral delivery of autoantigens for the induction of immune tolerance are highlighted.

Visualization and phenotyping of proinflammatory antigen-specific T cells during collagen-induced arthritis in a mouse with a fixed collagen type II-specific transgenic T-cell receptor β-chain

INTRODUCTION

The Vβ12-transgenic mouse was previously generated to investigate the role of antigen-specific T cells in collagen-induced arthritis (CIA), an animal model for rheumatoid arthritis. This mouse expresses a transgenic collagen type II (CII)-specific T-cell receptor (TCR) β-chain and consequently displays an increased immunity to CII and increased susceptibility to CIA. However, while the transgenic Vβ12 chain recombines with endogenous α-chains, the frequency and distribution of CII-specific T cells in the Vβ12-transgenic mouse has not been determined. The aim of the present report was to establish a system enabling identification of CII-specific T cells in the Vβ12-transgenic mouse in order to determine to what extent the transgenic expression of the CII-specific β-chain would skew the response towards the immunodominant galactosylated T-cell epitope and to use this system to monitor these cells throughout development of CIA.

METHODS

We have generated and thoroughly characterized a clonotypic antibody, which recognizes a TCR specific for the galactosylated CII(260-270) peptide in the Vβ12-transgenic mouse. Hereby, CII-specific T cells could be quantified and followed throughout development of CIA, and their phenotype was determined by combinatorial analysis with the early activation marker CD154 (CD40L) and production of cytokines.

RESULTS

The Vβ12-transgenic mouse expresses several related but distinct T-cell clones specific for the galactosylated CII peptide. The clonotypic antibody could specifically recognize the majority (80%) of these. Clonotypic T cells occurred at low levels in the naïve mouse, but rapidly expanded to around 4% of the CD4+ T cells, whereupon the frequency declined with developing disease. Analysis of the cytokine profile revealed an early Th1-biased response in the draining lymph nodes that would shift to also include Th17 around the onset of arthritis. Data showed that Th1 and Th17 constitute a minority among the CII-specific population, however, indicating that additional subpopulations of antigen-specific T cells regulate the development of CIA.

CONCLUSIONS

The established system enables the detection and detailed phenotyping of T cells specific for the galactosylated CII peptide and constitutes a powerful tool for analysis of the importance of these cells and their effector functions throughout the different phases of arthritis.

Type II collagen oral tolerance; mechanism and role in collagen-induced arthritis and rheumatoid arthritis

Oral tolerance means a diminished immune response to previously fed antigens. Repeated oral administrations of type II collagen (CII) induce oral tolerance and inhibit the development of collagen-induced arthritis (CIA). Dendritic cells (DCs) in the gut-associated lymphoid tissue (GALT) take up the CII and then present it to T cells to generate regulatory T cells (Tregs), which induce systemic immune tolerance to CII. Inhibitory cytokines, such as transforming growth factor (TGF)-beta and interleukin (IL)-10, and several immune regulatory molecules, including indoleamine 2,3-dioxygenase (IDO) and retinoic acid, play an important role in Treg generation. Each DC subset may play different roles, and CD11c+CD11b+DCs and IDO+DCs are important in the generation of antigen-inducible Tregs in CII oral tolerance. Upon stimulation with the antigen involved in its generation, Treg is activated and regulates the immune response through inhibitory cytokine production, cell-to-cell contact-dependent mechanisms, DC modification, and bystander suppression. The DCs and Tregs are deeply involved in oral tolerance through reciprocal interactions. Several clinical trials have been conducted in RA patients to examine the efficacy of CII oral tolerance. An understanding the mechanism of oral tolerance to CII would give clinicians new insights into the development of natural immune tolerance and new therapeutic approaches for the treatment of autoimmune diseases.

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.

Development and evaluation of transgenic rice seeds accumulating a type II-collagen tolerogenic peptide

Type II collagen (CII) in joint cartilage is known to be a major auto-antigen in human rheumatoid arthritis. Several animal model- and clinical-studies on tolerance-based immunotherapy for the arthritis have been conducted by administrating synthetic immunodominant peptides through an oral route. In the present study, to produce a tolerogenic peptide with therapeutic potential in transgenic rice plants, a gene construct producing glutelin fusion protein with tandem four repeats of a CII(250-270) peptide (residues 250-270) (GluA-4XCII(250-270)) containing a human T-cell epitope was introduced with a selection marker, hygromycin phosphotransferase gene (hygromycin-resistance gene) (hph), by co-transformation. Several transgenic plants with high and stable expression of gluA-4XCII ( 250-270 ), but no hph, were selected based on both DNA and protein analyses. The GluA-4XCII(250-270) fusion proteins were detected as both precursor and processed forms mainly in a glutelin fraction of rice endosperm protein extracts and in protein-body rich fractions prepared by density gradient ultracentrifugation. The amount of accumulated CII(250-270) peptide was immunochemically estimated to be about 1 microg per seed. Feeding DBA/1 mice the transgenic rice seeds (25 microg of the peptide per mouse a day) for 2 weeks showed tendencies lowering and delaying serum specific-IgG2a response against subsequent and repeated intraperitoneal-injection of type II collagen. Taken these together, the CII-immunodominant peptide could effectively be produced and accumulated as a glutelin-fusion protein in the transgenic rice seeds, which might be useful as pharmaceutical materials and functional food for prevention and therapy for anti-CII autoimmune diseases like human rheumatoid arthritis.

Oral administration of type-II collagen peptide 250-270 suppresses specific cellular and humoral immune response in collagen-induced arthritis

Oral antigen is an attractive approach for the treatment of autoimmune and inflammatory diseases. Establishment of immune markers and methods in evaluating the effects of antigen-specific cellular and humoral immune responses will help the application of oral tolerance in the treatment of human diseases. The present article observed the effects of chicken collagen II (CII), the recombinant polymerized human collagen II 250-270 (rhCII 250-270) peptide and synthesized human CII 250-270 (syCII 250-270) peptide on the induction of antigen-specific autoimmune response in rheumatoid arthritis (RA) peripheral blood mononuclear cells (PBMC) and on the specific cellular and humoral immune response in collagen-induced arthritis (CIA) and mice fed with CII (250-270) prior to immunization with CII. In the study, proliferation, activation and intracellular cytokine production of antigen-specific T lymphocytes were simultaneously analyzed by bromodeoxyuridine (BrdU) incorporation and flow cytometry at the single-cell level. The antigen-specific antibody and antibody-forming cells were detected by ELISA and ELISPOT, respectively. CII (250-270) was found to have stimulated the response of specific lymphocytes in PBMC from RA patients, including the increase expression of surface activation antigen marker CD69 and CD25, and DNA synthesis. Mice, fed with CII (250-270) before CII immunization, had significantly lower arthritic scores than the mice immunized with CII alone, and the body weight of the former increased during the study period. Furthermore, the specific T cell activity, proliferation and secretion of interferon (IFN)-gamma in spleen cells were actively suppressed in CII (250-270)-fed mice, and the serum anti-CII, anti-CII (250-270) antibody activities and the frequency of specific antibody-forming spleen cells were significantly lower in CII (250-270)-fed mice than in mice immunized with CII alone. These observations suggest that oral administration of CII (250-270) can suppress the cellular and humoral immune response in collagen-induced arthritis, and the simultaneous analysis of antigen-specific cellular and humoral immune responses at single-cell level will help the understanding of the oral tolerance mechanisms in CIA and the development of innovative therapeutic intervention for RA.

Therapeutic vaccination of active arthritis with a glycosylated collagen type II peptide in complex with MHC class II molecules

In both collagen-induced arthritis (CIA) and rheumatoid arthritis, T cells recognize a galactosylated peptide from type II collagen (CII). In this study, we demonstrate that the CII259-273 peptide, galactosylated at lysine 264, in complex with Aq molecules prevented development of CIA in mice and ameliorated chronic relapsing disease. In contrast, nonglycosylated CII259-273/Aq complexes had no such effect. CIA dependent on other MHC class II molecules (Ar/Er) was also down-regulated, indicating a bystander vaccination effect. T cells could transfer the amelioration of CIA, showing that the protection is an active process. Thus, a complex between MHC class II molecules and a posttranslationally modified peptide offers a new possibility for treatment of chronically active autoimmune inflammation such as rheumatoid arthritis.

Oral tolerance

Multiple mechanisms of tolerance are induced by oral antigen. Low doses favor active suppression, whereas higher doses favor clonal anergy/deletion. Oral antigen induces T-helper 2 [interleukin (IL)-4/IL-10] and Th3 [transforming growth factor (TGF)-beta] T cells plus CD4+CD25+ regulatory cells and latency-associated peptide+ T cells. Induction of oral tolerance is enhanced by IL-4, IL-10, anti-IL-12, TGF-beta, cholera toxin B subunit, Flt-3 ligand, and anti-CD40 ligand. Oral (and nasal) antigen administration suppresses animal models of autoimmune diseases including experimental autoimmune encephalitis, uveitis, thyroiditis, myasthenia, arthritis, and diabetes in the non-obese diabetic (NOD) mouse, plus non-autoimmune diseases such as asthma, atherosclerosis, graft rejection, allergy, colitis, stroke, and models of Alzheimer's disease. Oral tolerance has been tested in human autoimmune diseases including multiple sclerosis (MS), arthritis, uveitis, and diabetes and in allergy, contact sensitivity to dinitrochlorobenzene (DNCB), and nickel allergy. Although positive results have been observed in phase II trials, no effect was observed in phase III trials of CII in rheumatoid arthritis or oral myelin and glatiramer acetate (GA) in MS. Large placebo effects were observed, and new trials of oral GA are underway. Oral insulin has recently been shown to delay onset of diabetes in at-risk populations, and confirmatory trials of oral insulin are being planned. Mucosal tolerance is an attractive approach for treatment of autoimmune and inflammatory diseases because of lack of toxicity, ease of administration over time, and antigen-specific mechanisms of action. The successful application of oral tolerance for the treatment of human diseases will depend on dose, developing immune markers to assess immunologic effects, route (nasal versus oral), formulation, mucosal adjuvants, combination therapy, and early therapy.

Pathogenesis of collagen-induced arthritis: modulation of disease by arthritogenic T-cell epitope location

Collagen-induced arthritis (CIA) is an animal model of human rheumatoid arthritis that can be induced in susceptible mice by immunization with type II collagen (CII) or with collagen fragments, including cyanogen bromide (CB) peptides. One susceptible mouse strain, B10.RIII (I-Ar), has previously been found to respond to two major T-cell determinants, namely CII 610-618 (GPAGTAGAR) within CB10 and CII 445-453 (GPAGPAGER) within CB8. Although CB10 contains the immunodominant determinant, it is not arthritogenic. Using recombinant techniques, the determinant within CB10 was mutated to rCB10(T614P,A617E), generating a recombinant CB10 that in effect contained the arthritogenic epitope. When used for immunization, rCB10(T614P,A617E) was arthritogenic. This suggested that the arthritogenic property was intrinsic to the epitope and unrelated to its position within the CII molecule. To test this hypothesis, additional mutants were generated. The wild-type T-cell epitope of CB10 was deleted from its natural position, and the 'arthritogenic' GPAGPAGER T-cell epitope was inserted into the C-terminal portion of the CB10 peptide. The resulting peptide induced arthritis in B10.RIII mice. Adding a second copy of the T-cell determinant to other sites within CB10, however, had varying results. A second T-cell epitope located at the C-terminus of rCB10 significantly increased the incidence and severity of arthritis, while determinants placed in other positions had little effect. These data indicate that the T-cell epitope has intrinsic arthritogenic properties, but there are positional and structural constraints that affect its arthritogenicity. Enhanced arthritis was associated with an increased T-cell proliferation to the peptides, an increase in the level of inflammatory cytokines, and higher levels of anti-CII immunoglobulin. These data suggest that the position and copy number of T-cell determinants also affect the overall immune T-cell responses.

Efficacy of modified recombinant type II collagen in modulating autoimmune arthritis

OBJECTIVE

Previous studies have shown that an analog peptide of the immunodominant T cell determinant of type II collagen (CII), i.e., CII(256-276)(N(263), D(266)), was able to suppress the immune response to CII and the development of arthritis in DR1-transgenic mice. The present study tested the hypothesis that introduction of the same amino acid substitutions into full-length CII might improve the efficacy of the mutant collagen in achieving suppression of autoimmune arthritis.

METHODS

Using recombinant technology, full-length CII was modified, while the native conformation was retained. Two point mutations were introduced within the immunodominant T cell determinant to convert the F(263) to N and E(266) to D, using a baculovirus expression system that has previously been utilized in the production of recombinant CII (rCII).

RESULTS

The mutant rCII(N(263), D(266)) was capable of reducing the incidence and severity of arthritis as well as the antibody response to CII when administered to DR1-transgenic mice that display susceptibility to collagen-induced arthritis. More importantly, it was significantly more effective than the synthetic analog peptide, CII(256-276)(N(263), D(266)). Its mechanism of suppression may be explained by the secretion of predominantly Th2 cytokines by the T cells immunized with rCII(N(263), D(266)). Administration of rCII(N(263), D(266)) was ineffective in suppressing arthritis in IL4(-/-) mice, suggesting that the profound suppressive effects of rCII(N(263), D(266)) were mediated through the production of interleukin-4.

CONCLUSION

These findings describe a promising specific immunotherapy for patients with DR1-mediated autoimmunity to CII.

Glycosylation of type II collagen is of major importance for T cell tolerance and pathology in collagen-induced arthritis

Type II collagen (CII) is a candidate cartilage-specific autoantigen, which can become post-translationally modified by hydroxylation and glycosylation. T cell recognition of CII is essential for the development of murine collagen-induced arthritis (CIA) and also occurs in rheumatoid arthritis (RA). The common denominator of murine CIA and human RA is the presentation of an immunodominant CII-derived glycosylated peptide on murine Aq and human DR4 molecules, respectively. To investigate the importance of T cell recognition of glycosylated CII in CIA development after immunization with heterologous CII, we treated neonatal mice with different heterologous CII-peptides (non-modified, hydroxylated and galactosylated). Treatment with the galactosylated peptide (galactose at position 264) was superior in protecting mice from CIA. Protection was accompanied by a reduced antibody response to CII and by an impaired T cell response to the glycopeptide. To investigate the importance of glycopeptide recognition in an autologous CIA model, we treated MMC-transgenic mice, which express the heterologous CII epitope with a glutamic acid in position 266 in cartilage, with CII-peptides. Again, a strong vaccination potential of the glycopeptide was seen. Hence CII-glycopeptides may be the optimal choice of vaccination target in RA, since humans share the same epitope as the MMC mouse.

Immunogenicity of recombinant type IX collagen in murine collagen-induced arthritis

OBJECTIVE

Past attempts to isolate type IX collagen (CIX) from cartilage using limited proteolysis yielded partially degraded material. Recent application of recombinant technology, however, has allowed the preparation of intact native CIX. We used the murine collagen-induced arthritis model to characterize the immunologic properties of recombinant human CIX (rCIX) produced using a baculovirus expression system.

METHODS

A panel of B10 congenic mice was immunized with rCIX emulsified with Freund's complete adjuvant (CFA). The ability of the rCIX to induce tolerance and suppress arthritis was determined by administration intravenously or orally before challenge with CII/CFA.

RESULTS

None of the mice immunized with rCIX developed overt arthritis, although 2 of 5 HLA-DR1 transgenic mice developed limited digital erythema and swelling. Recombinant CIX administered by either route effectively induced suppression of arthritis, although the suppression was less pronounced than that induced with CII. Immune responses to CIX and CII were specific, suggesting that bystander suppression, rather than cross-reactivity with CII, was instrumental in suppressing arthritis.

CONCLUSION

These data show that CIX down-regulates arthritis in mice while having no associated risk of inducing arthritis.

Genetic ablation of interferon-gamma up-regulates interleukin-1beta expression and enables the elicitation of collagen-induced arthritis in a nonsusceptible mouse strain

OBJECTIVE

To determine whether the lack of interferon-gamma (IFNgamma) alters resistance to collagen-induced arthritis (CIA) in a nonsusceptible mouse strain, and if so, to identify changes in the antibody, cellular type II collagen (CII)-specific immune responses, and cytokine gene expression that might account for the altered susceptibility.

METHODS

CIA-resistant C57BL/6 and C57BL/6 IFNgamma-/- mice were immunized with bovine CII in Freund's complete adjuvant (CFA) or in CFA alone. Animals were monitored for signs of arthritis for up to 80 days; arthritis severity was assessed visually and histologically. Sera were collected at various time points after immunization for measurement of anti-CII antibody levels. T cell responses to bovine CII were assessed in proliferation assays. Cytokine messenger RNA (mRNA) expression in lymph node cells and in synovial cells from arthritic paws was measured by RNase protection assays, and levels of cytokine protein production were determined by enzyme-linked immunosorbent assay.

RESULTS

IFNgamma-/- mice developed a severe autoimmune arthritis that was dependent on immunization with CII. IFNgamma-/- mice produced significantly higher amounts of IgG1 and IgG2b antibody to the autoantigen, murine CII, compared with wild-type C57BL/6 mice and had an enhanced T cell proliferative response to bovine CII. Enhanced production of mature interleukin-1/beta (IL-1beta) protein was observed, but no significant changes in Th1 or Th2 cytokines. Although IL-6 and tumor necrosis factor alpha transcripts were clearly evident in the synovial cells from the arthritic paws of IFNgamma-/- mice, neither message was elevated to the levels measured for IL-1beta expression. Treatment of IFNgamma-/- mice with anti-IL-1beta significantly reduced the incidence and severity of the inflammation.

CONCLUSION

Endogenous IFNgamma plays a role in the regulation of IL-1beta, in this model of autoimmune arthritis.

Molecular definition and characterization of recombinant bovine CB8 and CB10: immunogenicity and arthritogenicity

Theoretically, the ability to produce recombinant type II collagen (CII) peptide fragments in a prokaryotic expression system would be extremely useful for preparing adequate amounts of CII peptides suitable for therapeutic uses. Bacteria do not contain the enzymes involved in the extensive posttranslational modifications that occur during the biosynthesis of CII, such as the hydroxylation of prolyl and lysyl residues and glycosylation of hydroxylysyl residues. As these posttranslational modifications may play a role in the immune and arthritogenic response to CII, it was unclear whether collagen expressed in Escherichia coli would be immunologically comparable to tissue-derived CII. Therefore, we prepared recombinant proteins for CB8 and CB10 by cloning CB8 (CII 403-551) and CB10 (CII 552-897) genes from bovine chondrocytes by RT-PCR technique and expressing them in an E. coli expression system. Characterization of these recombinant proteins revealed that both rCB8 and rCB10 stimulated T cell proliferation in a T cell determinant-specific manner. The T cells from mice immunized with rCB8 respond specifically to a synthetic peptide, CII 445-453, the CB8 T cell determinant. Conversely, rCB10-primed T cells respond strongly to CII 610-618, the CB10 T cell determinant. Recombinant CB8-induced autoantibodies that bound to mouse CB8 as effectively and in the same topographic distribution as tissue-derived CB8. Finally, when rCB8 and rCB10 proteins were used to immunize B10.RIII (H-2(r)) mice, rCB8 induced arthritis in 33% of the mice, very similar to the incidence induced by tissue-derived CB8 peptide. As was found to be the case with tissue-derived CB10, rCB10 was completely ineffective in inducing arthritis. Pathological changes of arthritic joints in the mice immunized with rCB8 were similar to those observed in mice immunized with tissue-derived CB8. Thus, these recombinant CII peptides expressed in E. coli can induce an effective immunologic response and suggest that functionally useful CII peptides can be generated by the prokaryotic expression system.

Transgenic mouse models of rheumatoid arthritis

A combined analysis of data available in the literature has demonstrated that the strongest association in rheumatoid arthritis (RA) is with DR genes rather than DQ or DP genes. Functional and structural data of RA-associated DR molecules suggest that selective binding of peptides is the molecular basis for this association. The establishment of functional transgenic mice expressing RA-associated HLA class II molecules has proven to be useful in the delineation of the role of these molecules in immune responses possibly related to RA and in the development of humanized models for this disease. Such humanized mice develop arthritis upon immunization with type II collagen (CII), which shows similarities with RA. Interestingly, the immunodominant T-cell determinant in CII is derived from positions 261-273, which overlap with a previously identified CII T-cell epitope restricted by the mouse Aq molecule, which is associated with collagen-induced arthritis. Studies in collagen transgenic mice have shown that recognition of this peptide may lead either to T-cell tolerance or to an arthritogenic response. It is therefore proposed that the T-cell recognition of the CII peptide bound by DR molecules is one of the molecular interactions of critical importance in the development of RA and accordingly also an important target for prevention and treatment of this disease.