Mucosal tolerance and suppression of collagen-induced arthritis (CIA) induced by nasal inhalation of synthetic peptide 184-198 of bovine type II collagen (CII) expressing a dominant T cell epitope

A fructosylated peptide derived from a collagen II T cell epitope for long-term treatment of arthritis (FIA-CIA) in mice

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease which affects primarily the joints. Peptides of several proteins have shown an effect in some experimental animal models of RA. We investigated arthritis development in male DBA/1 mice which were injected with bovine collagen II (bCII) and human fibrinogen (hFib) on days 0 and 21, leading to stable and reproducible disease induction in 100% of immunized mice (FIA-CIA). In a second study, two bCII-derived peptides were given three times in the course of 6 weeks after FIA-CIA induction to test for impact on arthritis. Mice were scored weekly for arthritis and anti-citrullinated peptide antibodies (ACPAs) were determined in the sera taken on days 0, 14, 35, 56 and 84. Histology of the hind paws was performed at the end of the experiment. Intravenous administration of peptide 90578, a novel fructosylated peptide derived from the immunodominant T cell epitope of bCII, at a dosage of 1 mg/kg resulted in significant beneficial effects on clinical outcome parameters and on the arthritis histology scores which was sustained over 12 weeks. Survival tended to be improved in peptide 90578-treated mice. Intravenous administration of pure soluble peptide 90578 without adjuvants is a promising approach to treat RA, with treatment starting at a time when ACPAs are already present. The results complement existing data on peptide "vaccination" of healthy animals, or on treatment using recombinant peptide expressing virus or complex biological compounds.

Antigen-specific tolerance approach for rheumatoid arthritis: Past, present and future

Rheumatoid arthritis is a chronic systemic autoimmune disease, affecting mainly the joints. It is caused by an adaptive immune reaction against self-antigens, leading to the over production of inflammatory cytokines and autoantibodies, mainly mediated by autoreactive CD4+ T cells and pathological B cell clones. The treatment options currently available rely on palliative global immunosuppression and do not restore tolerance to self-components. Here, we review antigen-specific tolerance approaches that have been developed to inhibit or delete autoreactive clones, while maintaining a potent immune system for rheumatoid arthritis. The first attempts relied on the oral ingestion of self-reactive peptides, with lukewarm results in human clinical trials. To enhance treatment efficacy, self-peptides have been engineered and combined with immunosuppressive molecules. In addition, several routes of delivery have been tested, in particular, nanoparticles carrying self-antigens and immunomodulatory molecules. More recently, transfer of immune cells, such as tolerogenic dendritic cells or regulatory T cells, has been considered to restore tolerance. Although promising results have been obtained in mouse models, the translation to humans remains highly challenging, mainly because the disease is already well developed when treatments start and because patient's specific self-antigens are often unknown. Nevertheless, these approaches hold great promises for long-term RA treatment.

Peptide-Based Vaccination Therapy for Rheumatic Diseases

Rheumatic diseases are extremely heterogeneous diseases with substantial risks of morbidity and mortality, and there is a pressing need in developing more safe and cost-effective treatment strategies. Peptide-based vaccination is a highly desirable strategy in treating noninfection diseases, such as cancer and autoimmune diseases, and has gained increasing attentions. This review is aimed at providing a brief overview of the recent advances in peptide-based vaccination therapy for rheumatic diseases. Tremendous efforts have been made to develop effective peptide-based vaccinations against rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), while studies in other rheumatic diseases are still limited. Peptide-based active vaccination against pathogenic cytokines such as TNF-α and interferon-α (IFN-α) is shown to be promising in treating RA or SLE. Moreover, peptide-based tolerogenic vaccinations also have encouraging results in treating RA or SLE. However, most studies available now have been mainly based on animal models, while evidence from clinical studies is still lacking. The translation of these advances from experimental studies into clinical therapy remains impeded by some obstacles such as species difference in immunity, disease heterogeneity, and lack of safe delivery carriers or adjuvants. Nevertheless, advances in high-throughput technology, bioinformatics, and nanotechnology may help overcome these impediments and facilitate the successful development of peptide-based vaccination therapy for rheumatic diseases.

Administration of donor splenocytes via the respiratory tract generates CD8α+ regulatory dendritic cells and induces hyporesponsiveness to fully allogeneic cardiac grafts

BACKGROUND

We previously showed that pretreatment with intratracheal delivery (ITD) of alloantigen induced prolonged cardiac allograft survival and generated regulatory T cells (Tregs) in mice. In this study, we examined the role of splenic dendritic cells (DCs) in the ITD model.

METHODS

CBA mice were treated with ITD from C57BL/10 splenocytes and 7 days later received transplantation of C57BL/10 hearts. In adoptive transfer studies, splenic DCs from ITD-treated mice were transferred into naïve CBA recipients that received C57BL/10 hearts immediately after the transfer. In addition, to determine the role of splenic DCs isolated from ITD-treated mice, the cells were incubated under stimulation with lipopolysaccharide (LPS).

RESULTS

ITD-treated CBA recipients had markedly prolonged allograft survival (median survival time [MST], 67 days) while naïve recipients rejected allografts acutely (MST, 8 days). In adoptive transfer studies, CBA recipients of the transfer of splenic DCs from ITD-treated mice had prolonged allograft survival (MST, 85 days), while CBA recipients of the transfer of splenic DCs from naïve mice did not have prolonged allograft survival (MST, 8 days). In another transfer study, CBA recipients of the transfer of splenic CD8α⁺ DCs from ITD-treated mice had prolonged allograft survival (MST, 79 days), while those receiving splenic CD8α^- DCs from ITD-treated mice did not have prolonged allograft survival (MST, 8 days). In vitro studies showed that ITD-treated splenic DCs produced more IL-10 and less IL-12 than naïve splenic DCs under stimulation with LPS.

CONCLUSIONS

ITD pretreatment induces regulatory DCs, which produce high amounts of IL-10 resulting in the prolongation of graft survival in our model.

Mesenchymal stem cells alleviate experimental rheumatoid arthritis through microRNA-regulated IκB expression

Previous studies have demonstrated that mesenchymal stem cell (MSC) transplantation reduces the severity of collagen-induced arthritis (CIA) in mice, which is a model for rheumatoid arthritis (RA) in humans. However, the underlying molecular mechanisms remain ill-defined. Here, we showed that MSC transplantation reduced the activities of NF-κB signaling and decreased microRNA-548e (miR-548e) levels in the joint tissue in CIA-mice, seemingly through activation of transforming growth factor β receptor signaling. Bioinformatics analyses revealed that miR-548e inhibited protein translation of the NF-κB inhibitor, IκB, through binding to the 3′-UTR of the IκB mRNA. MSCs co-transplanted with adeno-associated virus (AAV) carrying miR-548e abolished the therapeutic effects of MSCs on CIA. On the other hand, transplantation of AAV carrying antisense of miR-548e (as-miR-548e) partially mimicked the effects of MSC transplantation on CIA. Together, these data suggest that MSC transplantation may alleviate experimental RA partially through suppressing miR-548e-mediated IκB inhibition.

Combination peptide immunotherapy suppresses antibody and helper T-cell responses to the RhD protein in HLA-transgenic mice

The offspring from pregnancies of women who have developed anti-D blood group antibodies are at risk of hemolytic disease of the newborn. We have previously mapped four peptides containing immunodominant T-helper cell epitopes from the RhD protein and the purpose of the work was to develop these into a product for suppression of established anti-D responses. A panel of each of the four immunodominant RhD peptides was synthesized with modifications to improve manufacturability and solubility, and screened for retention of recognition by human T-helper cells. A selected version of each sequence was combined in a mixture (RhDPmix), which was tested for suppressive ability in a humanized murine model of established immune responses to RhD protein. After HLA-DR15 transgenic mice had been immunized with RhD protein, a single dose of RhDPmix, given either intranasally (P=0.008, Mann-Whitney rank sum test) or subcutaneously (P=0.043), rapidly and significantly suppressed the ongoing antibody response. This was accompanied by reduced T-helper cell responsiveness, although this change was less marked for subcutaneous RhDPmix delivery, and by the recruitment of cells with a regulatory T-cell phenotype. The results support human trials of RhDPmix peptide immunotherapy in women with established antibody responses to the RhD blood group.

Antigen-specific gene therapy after immunisation reduces the severity of collagen-induced arthritis

Reestablishment of tolerance induction in rheumatoid arthritis (RA) would be an optimal treatment with few, if any, side effects. However, to develop such a treatment further insights in the immunological mechanisms governing tolerance are needed. We have developed a model of antigen-specific tolerance in collagen type II (CII) induced arthritis (CIA) using lentivirus-based gene therapy. The immunodominant epitope of CII was inserted into a lentivirus vector to achieve expression on the MHC class II molecule and the lentiviral particles were subsequently intravenously injected at different time points during CIA. Injection of lentiviral particles in early phases of CIA, that is, at day 7 or day 26 after CII immunisation, partially prevented development of arthritis, decreased the serum levels of CII-specific IgG antibodies, and enhanced the suppressive function of CII-specific T regulatory cells. When lentiviral particles were injected during manifest arthritis, that is, at day 31 after CII immunisation, the severity of arthritis progression was ameliorated, the levels of CII-specific IgG antibodies decreased and the proportion of T regulatory cells increased. Thus, antigen-specific gene therapy is effective when administered throughout the inflammatory course of arthritis and offers a good model for investigation of the basic mechanisms during tolerance in CIA.

Evaluation of TLR agonists as potential mucosal adjuvants for HIV gp140 and tetanus toxoid in mice

In the present study we investigate the impact of a range of TLR ligands and chitosan as potential adjuvants for different routes of mucosal immunisation (sublingual (SL), intranasal (IN), intravaginal (IVag) and a parenteral route (subcutaneous (SC)) in the murine model. We assess their ability to enhance antibody responses to HIV-1 CN54gp140 (gp140) and Tetanus toxoid (TT) in systemic and vaginal compartments. A number of trends were observed by route of administration. For non-adjuvanted antigen, SC>SL>IN immunisation with respect to systemic IgG responses, where endpoint titres were greater for TT than for gp140. In general, co-administration with adjuvants increased specific IgG responses where IN = SC>SL, while in the vaginal compartment IN>SL>SC for specific IgA. In contrast, for systemic and mucosal IgA responses to antigen alone SL>IN = SC. A number of adjuvants increased specific systemic IgA responses where in general IN>SL>SC immunisation, while for mucosal responses IN = SL>SC. In contrast, direct intravaginal immunisation failed to induce any detectable systemic or mucosal responses to gp140 even in the presence of adjuvant. However, significant systemic IgG responses to TT were induced by intravaginal immunisation with or without adjuvant, and detectable mucosal responses IgG and IgA were observed when TT was administered with FSL-1 or Poly I∶C. Interestingly some TLRs displayed differential activity dependent upon the route of administration. MPLA (TLR4) suppressed systemic responses to SL immunisation while enhancing responses to IN or SC immunisation. CpG B enhanced SL and IN responses, while having little or no impact on SC immunisation. These data demonstrate important route, antigen and adjuvant effects that need to be considered in the design of mucosal vaccine strategies.

Mapping the T helper cell response to acid α-glucosidase in Pompe mice

Pompe disease is a neuromuscular disease caused by an inherited deficiency of the lysosomal enzyme acid α-glucosidase (GAA). The resulting accumulation of glycogen causes muscle weakness with the severe form of the disease resulting in death by cardiorespiratory failure in the first year of life. The only available treatment, enzyme replacement therapy (ERT) with recombinant GAA (rhGAA), is severely hampered by antibody responses that reduce efficacy and cause immunotoxicities. Currently, Pompe mice represent the only pre-clinical model for development of new treatments and for immunological studies. While antibody formation following ERT in this model has been described, the underlying T cell response has not been studied. In order to define the T helper response to rhGAA in Pompe mice, immunodominant CD4(+) T cell epitopes were mapped in GAA(-/-) 129SVE mice using ELISpot. Additionally, cytokine responses and antibody formation against rhGAA during ERT were measured. Among the three CD4(+) T cell epitopes identified, only epitope IFLGPEPKSVVQ, predicted to be the strongest MHC II binder, consistently contributed to IL-4 production. Frequencies of IL-4 producing T cells were considerably higher than those of IL-17 or IFN-γ producing cells, suggesting a predominantly Th2 cell mediated response. This is further supported by IgG1 being the prevalent antibody subclass against rhGAA during ERT and consistent with prior reports on IgE formation and anaphylaxis in this model. These results will facilitate mechanistic studies of the immune response to rhGAA in Pompe mice during development of new therapies and tolerance protocols.

Immunotherapy with peptides

Specific allergen immunotherapy is clinically effective and disease modifying. It has a duration of effect that exceeds the treatment period and prevents both the progression of allergic rhinitis to asthma and the acquisition of new allergic sensitizations. However, immunotherapy is associated with a high frequency of adverse events related to the allergenicity of vaccines. Allergenicity is conferred by the presence of intact B-cell epitopes that crosslink allergen-specific IgE on effector cells. The use of linear peptide sequences representing fragments of the native allergen is one approach to reduce allergenicity. Preclinical models of peptide immunotherapy have demonstrated efficacy in both autoimmunity and allergy. Translation of this technology into the clinic has gained momentum in recent years based on encouraging results from early clinical trials. To date, efforts have focused on two major allergens, but vaccines to a broader range of molecules are currently in clinical development. Mechanistically, peptide immunotherapy appears to work through the induction of adaptive, allergen-specific regulatory T cells that secrete the immunoregulatory cytokine IL-10. There is also evidence that peptide immunotherapy targeting allergen-specific T cells can indirectly modulate allergen-specific B-cell responses. Peptide immunotherapy may provide a safe and efficacious alternative to conventional subcutaneous and/or sublingual approaches using native allergen preparations.

T cell epitope-based allergy vaccines

Specific immunotherapy (SIT) with extracts containing intact allergen molecules is clinically efficacious, but associated with frequent adverse events related to the allergic sensitization of the patient. As a result, treatment is initiated in an incremental dose fashion which ultimately achieves a plateau (maintenance dose) that may be continued for several years. Reduction of allergic adverse events may allow safer and more rapid treatment Thus, many groups have developed and evaluated strategies to reduce allergenicity whilst maintaining immunogenicity, the latter being required to achieve specific modulation of the immune response. Peptide immunotherapy can be used to target T and/or B cells in an antigen-specific manner. To date, only approaches that target T cells have been clinically evaluated. Short, synthetic peptides representing immunodominant T cell epitopes of major allergens are able to modulate allergen-specific T cell responses in the absence of IgE cross linking and activation of effector cells. Here we review clinical and mechanistic studies associated with peptide immunotherapy targeting allergy to cats or to bee venom. 

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.

Effective induction of protective systemic immunity with nasally administered vaccines adjuvanted with IL-1

IL-1α and IL-1β were evaluated for their ability to provide adjuvant activity for the induction of serum antibody responses when nasally administered with protein antigens in mice and rabbits. In mice, intranasal (i.n.) immunization with pneumococcal surface protein A (PspA) or tetanus toxoid (TT) combined with IL-1β induced protective immunity that was equivalent to that induced by parenteral immunization. Nasal immunization of awake (i.e., not anesthetized) rabbits with IL-1-adjuvanted vaccines induced highly variable serum antibody responses and was not as effective as parenteral immunization for the induction of antigen-specific serum IgG. However, i.n. immunization of deeply anesthetized rabbits with rPA+IL-1α consistently induced rPA-specific serum IgG ELISA titers that were not significantly different than those induced by intramuscular (IM) immunization with rPA+alum although lethal toxin-neutralizing titers induced by nasal immunization were lower than those induced by IM immunization. Gamma scintigraphy demonstrated that the enhanced immunogenicity of nasal immunization in anesthetized rabbits correlated with an increased nasal retention of i.n. delivered non-permeable radio-labeled colloidal particles. Our results demonstrate that, in mice, IL-1 is an effective adjuvant for nasally administered vaccines for the induction of protective systemic immunity and that in non-rodent species, effective induction of systemic immunity with nasally administered vaccines may require formulations that ensure adequate retention of the vaccine within the nasal cavity.

Treating arthritis by immunomodulation: is there a role for regulatory T cells?

The discovery of regulatory T cells almost 15 years ago initiated a new and exciting research area. The growing evidence for a critical role of these cells in controlling autoimmune responses has raised expectations for therapeutic application of regulatory T cells in patients with autoimmune arthritis. Here, we review recent studies investigating the presence, phenotype and function of these cells in patients with RA and juvenile idiopathic arthritis (JIA) and consider their therapeutic potential. Both direct and indirect methods to target these cells will be discussed. Arguably, a therapeutic approach that combines multiple regulatory T-cell-enhancing strategies could be most successful for clinical application.

Antigenic strength controls the generation of antigen-specific IL-10-secreting T regulatory cells

Administration of peptides i.n. induces peripheral tolerance in Tg4 myelin basic protein-specific TCR-Tg mice. This is characterized by the generation of anergic, IL-10-secreting CD4+ T cells with regulatory function (IL-10 Treg). Myelin basic protein Ac1-9 peptide analogs, displaying a hierarchy of affinities for H-2 A(u) (Ac1-9[4K]<<[4A]<[4Y]), were used to investigate the mechanisms of tolerance induction, focusing on IL-10 Treg generation. Repeated i.n. administration of the highest affinity peptide, Ac1-9[4Y], provided complete protection against EAE, while i.n. Ac1-9[4A] and Ac1-9[4K] treatment resulted in only partial protection. Ac1-9[4Y] was also the most potent stimulus for IL-10 Treg generation. Although i.n. treatment with Ac1-9[4A] gave rise to IL-10-secreting CD4+ T cells, the population as a whole was also capable of secreting IFN-gamma after an in vitro recall response to Ac1-9[4A] or [4Y]. In addition to IL-10 production, other facets of tolerance, namely, anergy and suppression (both in vitro and in vivo), were affinity dependent, with i.n. Ac1-9[4Y]-, [4A]- or [4K]-treated CD4+ T cells being the most, intermediate and least anergic/suppressive, respectively. These findings demonstrate that the generation of IL-10 Treg in vivo is driven by high signal strength.

Negative feedback control of the autoimmune response through antigen-induced differentiation of IL-10-secreting Th1 cells

Regulation of the immune response to self- and foreign antigens is vitally important for limiting immune pathology associated with both infections and hypersensitivity conditions. Control of autoimmune conditions can be reinforced by tolerance induction with peptide epitopes, but the mechanism is not currently understood. Repetitive intranasal administration of soluble peptide induces peripheral tolerance in myelin basic protein (MBP)–specific TCR transgenic mice. This is characterized by the presence of anergic, interleukin (IL)-10–secreting CD4⁺ T cells with regulatory function (IL-10 T reg cells). The differentiation pathway of peptide-induced IL-10 T reg cells was investigated. CD4⁺ T cells became anergic after their second encounter with a high-affinity MBP peptide analogue. Loss of proliferative capacity correlated with a switch from the Th1-associated cytokines IL-2 and interferon (IFN)-γ to the regulatory cytokine IL-10. Nevertheless, IL-10 T reg cells retained the capacity to produce IFN-γ and concomitantly expressed T-bet, demonstrating their Th1 origin. IL-10 T reg cells suppressed dendritic cell maturation, prevented Th1 cell differentiation, and thereby created a negative feedback loop for Th1-driven immune pathology. These findings demonstrate that Th1 responses can be self-limiting in the context of peripheral tolerance to a self-antigen.

Mucosal tolerance induced by an immunodominant peptide from rat alpha3(IV)NC1 in established experimental autoimmune glomerulonephritis

Experimental autoimmune glomerulonephritis (EAG), an animal model of Goodpasture's disease, can be induced in Wistar Kyoto (WKY) rats by immunization with the noncollagenous domain of the alpha 3 chain of type IV collagen, alpha3(IV)NC1. Recent studies have identified an immunodominant peptide, pCol (24-38), from the N-terminus of rat alpha3(IV)NC1; this peptide contains the major B- and T-cell epitopes in EAG and can induce crescentic nephritis. In this study, we investigated the mechanisms of mucosal tolerance in EAG by examining the effects of the nasal administration of this peptide after the onset of disease. A dose-dependent effect was observed: a dose of 300 microg had no effect, a dose of 1000 microg resulted in a moderate reduction in EAG severity, and a dose of 3000 microg produced a marked reduction in EAG severity accompanied by diminished antigen-specific, T-cell proliferative responses. These results demonstrate that mucosal tolerance in EAG can be induced by nasal administration of an immunodominant peptide from the N-terminus of alpha3(IV)NC1 and should be of value in designing new therapeutic strategies for patients with Goodpasture's disease and other autoimmune disorders.

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.

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.

Enhancement of experimental Graves' disease by intranasal administration of a T cell epitope of the thyrotropin receptor

We previously showed that immunization of mice with murine fibroblasts transfected with the thyrotropin receptor (TSHR) and a murine major histocompatibility complex (MHC) class II molecule induces immune thyroid disease with the humoral and histological features of human Graves' disease in about 20% of mice. In this model, based on the proliferative response of T cells from hyperthyroid mice to a panel of overlapping TSHR peptides, we now demonstrate that TSHR 121-140 peptide contains an immunodominant T cell epitope. Supporting this conclusion, spleen cells from mice immunized with TSHR 121-140 peptide showed a strong proliferative response to fibroblasts transfected with the TSHR and a murine I-A(k) molecule, but not either alone. Also, intranasal administration of 100 mug of TSHR 121-140 peptide led to suppressed proliferative response of lymph node cells to the peptide. Interestingly, however, administration of this peptide enhanced, rather than suppressed, the frequency and severity of Graves' disease induced by the immunization of the fibroblasts transfected with the TSHR and a murine I-A(k) molecule. Spleen cells from hyperthyroid mice that were pretreated with intranasal peptide tended to produce lesser amounts of IL-4, IL-10 and IFN-gamma than those from normothyroid control mice. Although precise mechanisms of this enhancement remain to be determined, the results suggest that attempts to treat Graves' disease by intranasal administration of an immunodominant TSHR T cell epitope may aggravate, not prevent, the disease.

Immunotherapy with allergen peptides

Specific allergen immunotherapy (SIT) is disease-modifying and efficacious. However, the use of whole allergen preparations is associated with frequent allergic adverse events during treatment. Many novel approaches are being designed to reduce the allergenicity of immunotherapy preparations whilst maintaining immunogenicity. One approach is the use of short synthetic peptides which representing dominant T cell epitopes of the allergen. Short peptides exhibit markedly reduced capacity to cross link IgE and activate mast cells and basophils, due to lack of tertiary structure. Murine pre-clinical studies have established the feasibility of this approach and clinical studies are currently in progress in both allergic and autoimmune diseases.

Peptide immunotherapy for allergic diseases

Specific allergen immunotherapy has been widely practised for almost 100 years. Whilst this approach is disease-modifying and efficacious, the use of whole allergen preparations is associated with an unacceptably high prevalence of allergic adverse events during treatment. Many approaches to reduce the allergenicity of immunotherapy preparations whilst maintaining immunogenicity are under development. One such approach is the use of short synthetic peptides which represent major T-cell epitopes of the allergen. Major potential advantages of this approach include markedly reduced capacity to cross-link immunoglobulin-E and activate mast cells and basophils, and ease of manufacture and standardization. Promising results in preclinical studies have led to the translation of this approach to clinical studies in humans. Peptide immunotherapy is currently under development for allergic and autoimmune diseases.

Oral tolerance: therapeutic implications for autoimmune diseases

Oral tolerance is classically defined as the suppression of immune responses to antigens (Ag) that have been administered previously by the oral route. Multiple mechanisms of tolerance are induced by oral Ag. Low doses favor active suppression, whereas higher doses favor clonal anergy/deletion. Oral Ag induces Th2 (IL-4/IL-10) and Th3 (TGF-β) regulatory T cells (Tregs) plus CD4+CD25+ regulatory cells and LAP+T cells. Induction of oral tolerance is enhanced by IL-4, IL-10, anti-IL-12, TGF-β, cholera toxin B subunit (CTB), Flt-3 ligand, anti-CD40 ligand and continuous feeding of Ag. In addition to oral tolerance, nasal tolerance has also been shown to be effective in suppressing inflammatory conditions with the advantage of a lower dose requirement. Oral and nasal tolerance suppress several animal models of autoimmune diseases including experimental allergic encephalomyelitis (EAE), uveitis, thyroiditis, myasthenia, arthritis and diabetes in the nonobese diabetic (NOD) mouse, plus non-autoimmune diseases such as asthma, atherosclerosis, colitis and stroke. Oral tolerance has been tested in human autoimmune diseases including MS, arthritis, uveitis and diabetes and in allergy, contact sensitivity to DNCB, nickel allergy. Positive results have been observed in phase II trials and new trials for arthritis, MS and diabetes are underway. Mucosal tolerance is an attractive approach for treatment of autoimmune and inflammatory diseases because of lack of toxicity, ease of administration over time and Ag-specific mechanism 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.

Peptide Immunotherapy

Synthetic peptides representing T-cell epitopes of allergens and autoantigens have been employed to induce antigen-specific tolerance in vivo in experimental models and the clinical setting. Delivery of peptides orally or by injection leads to reduced reactivity to antigen accompanied by the induction of T cells with a regulatory phenotype. Peptide therapy may provide a safe, effective, and economically viable approach for disease-modifying therapy in autoimmune and allergic diseases.

Peptide therapy for allergic diseases: basic mechanisms and new clinical approaches

Desensitising allergen immunotherapy has been practised for many decades. Although time consuming, this form of therapy is antigen-specific and disease-modifying, in contrast to palliative pharmacotherapy. However, the use of allergen extracts containing native allergen molecules frequently results in allergic adverse reactions to treatment. Several strategies to reduce the allergenicity of therapeutic preparations, while maintaining their therapeutic benefit, are being developed. Peptide immunotherapy is one such approach. Short synthetic peptides, comprising T cell epitopes of major allergens, were unable to crosslink allergen-specific IgE molecules on basophils in vitro. Treatment of allergic volunteers with allergen peptides resulted in reduced skin, lung and nasal sensitivity to allergen challenge and improved their subjective ability to tolerate allergen exposure. Peptides reduced pro-inflammatory cytokine secretion from peripheral blood cells, whilst increasing the immunosuppressive cytokine IL-10. Furthermore, peptide therapy was associated with the induction of a population of CD4+ T cells with a suppressive functional phenotype. Thus, peptide therapy may be suitable for the antigen-specific treatment of allergic diseases.

Peptide-based therapeutic vaccines for allergic and autoimmune diseases

Allergic and autoimmune diseases are forms of immune hypersensitivity that increasingly cause chronic ill health. Most current therapies treat symptoms rather than addressing underlying immunological mechanisms. The ability to modify antigen-specific pathogenic responses by therapeutic vaccination offers the prospect of targeted therapy resulting in long-term clinical improvement without nonspecific immune suppression. Examples of specific immune modulation can be found in nature and in established forms of immune desensitization. Understanding and exploiting common mechanisms such as the ability to induce antigen-specific regulatory cells should allow the development of effective therapeutic strategies for both forms of immunopathology. Targeting pathogenic T cells using vaccines consisting of synthetic peptides representing T cell epitopes is one such strategy that is currently being evaluated with encouraging results. Future challenges in the development of therapeutic vaccines include selection of appropriate antigens and peptides, optimization of peptide dose and route of administration and identifying strategies to induce bystander suppression.

Constraints on the efficacy of mucosal tolerance in treatment of human and animal arthritic diseases

Mucosal administration of an autoantigen has been shown to be a powerful way of inducing tolerance in both animal and human arthritis clinical trials. Bovine or chicken type II collagen has been administered orally to rheumatoid arthritis patients, resulting in some, although in many cases rather limited, clinical improvement. Animal studies have revealed that the mechanisms that underlie induction of mucosal tolerance include clonal deletion, suppression of the proinflammatory Th1 cells, and the induction of regulatory T cells. These cells, defined as a persistently CD25-expressing subset of CD4(+) cells, are frequently anergic, may produce anti-inflammatory cytokines such as IL-10 and TGF-beta, and are likely to be agents of bystander suppression. A key feature that may affect the induction of these cells and other suppressive mechanisms is the dose of antigen administered. The results from human clinical trials suggest a daily dose of significantly less than 1 mg is optimal. Similarly data from collagen-induced arthritis studies reveal an optimal dose above and below which there is little or no immune suppression. Indeed, the incorrect dose can prime the immune response and aggravate disease. The timing and frequency of administration is also vital to the level of immune tolerance induced and the control of the pathological process. This and other findings derived from animal studies are discussed here in relation to the results from human clinical trials.

Interleukin-10 but not Transforming Growth Factor-β is Essential for Generation and Suppressor Function of Regulatory Cells Induced by Intratracheal Delivery of Alloantigen

BACKGROUND

We previously reported that intratracheal delivery of alloantigen-induced regulatory cells in mouse heart-transplantation model. Here, we investigated roles of interleukin (IL)-10 and transforming growth factor (TGF)-beta in induction and effector phases of the regulatory cells.

METHODS

CBA mice were pretreated with intratracheal delivery of C57BL/10 splenocytes and administration of neutralizing anti-IL-10 or anti-TGF-beta monoclonal antibody (mAb). Seven days after the pretreatment, naive CBA mice (secondary recipients) were given adoptive transfer of splenocytes from the pretreated mice and underwent heart grafting from C57BL/10 mice. To determine roles of these cytokines in the effector phase of the regulatory cells, anti-IL-10 or anti-TGF-beta mAb was administered weekly into the secondary recipients after the adoptive transfer.

RESULTS

Adoptive transfer of splenocytes from CBA mice that had been pretreated with intratracheal delivery of C57BL/10 splenocytes significantly prolonged the survival of C57BL/10 allograft (median survival time [MST] 68 days) as compared with adoptive transfer from untreated CBA mice (MST 12 days). In the induction phase, anti-IL-10 mAb abrogated development of the regulatory cells that afforded prolonged allograft survival in the secondary recipients (MST 20 days), whereas anti-TGF-beta mAb did not abrogate it (MST 88 days). In the effector phase, anti-IL-10 mAb abrogated prolonged allograft survival afforded by adoptive transfer of the regulatory cells in the secondary recipients (MST 27 days), whereas anti-TGF-beta mAb did not abrogate suppressor function of the regulatory cells (MST 53 days).

CONCLUSION

IL-10 but not TGF-beta was required for generation and suppressor function of the regulatory cells induced by intratracheal delivery of alloantigen.

Programmed death-1-programmed death-L1 interaction is essential for induction of regulatory cells by intratracheal delivery of alloantigen

BACKGROUND

Programmed death (PD)-1 has been implicated in peripheral tolerance. The authors investigated the roles of PD-1 and its ligands, PD-L1 and PD-L2, in the induction of regulatory cells by intratracheal delivery of alloantigen.

METHODS

CBA (H-2k) mice were pretreated with intratracheal delivery of C57BL/10 (H-2b) splenocytes and administration of monoclonal antibody (mAb) specific for PD-1, PD-L1, or PD-L2. Seven days later, C57BL/10 hearts were transplanted into the pretreated CBA mice. Some naive CBA mice underwent adoptive transfer of splenocytes from the pretreated CBA mice and transplantation of C57BL/10 heart.

RESULTS

Untreated CBA mice rejected C57BL/10 cardiac grafts acutely (median survival time [MST], 7 days). Pretreatment with intratracheal delivery of C57BL/10 splenocytes prolonged graft survival significantly (MST, 65 days). Administration of control immunoglobulin (Ig) G or anti-PD-L2 mAb did not significantly affect the prolongation (MST, 72 and 68 days, respectively). In contrast, anti-PD-1 or anti-PD-L1 mAb abrogated the prolongation (MST, 18 and 17 days, respectively). Adoptive transfer from mice pretreated with intratracheal delivery of alloantigen plus control IgG or anti-PD-L2 mAb prolonged survival of C57BL/10 grafts in secondary CBA recipients (MST, 72 and 56 days, respectively). However, concurrent administration of anti-PD-1 or anti-PD-L1 mAb abrogated prolonged survival after the adoptive transfer (MST, 14 and 20 days, respectively).

CONCLUSIONS

PD-1-PD-L1 interaction was essential for induction of regulatory cells by intratracheal delivery of alloantigen.

Oral tolerance

Autoimmune conditions caused by injurious immune responses against self-antigens can be ameliorated if the inappropriate responses to self-components that cause tissue injury can be modulated by regulatory cells or shut off via the induction of anergy or via deletion of pathogenic immune responses. Antigen encounter at the gut mucosa can lead to suppression of injurious immune responses to self-antigen via these mechanisms. This type of immunological event is termed oral tolerance. In this review, we examine the mechanisms behind the induction of oral tolerance and provide findings from its use as a form of treatment for autoimmune diseases.

Reduced experimental autoimmune encephalomyelitis after intranasal and oral administration of recombinant lactobacilli expressing myelin antigens

Oral administration of autoantigens is a safe and convenient way to induce peripheral T-cell tolerance in autoimmune diseases like multiple sclerosis (MS). To increase the efficacy of oral tolerance induction and obviate the need for large-scale purification of human myelin proteins, we use genetically modified lactobacilli expressing myelin antigens. A panel of recombinant lactobacilli was constructed producing myelin proteins and peptides, including human and guinea pig myelin basic protein (MBP) and proteolipid protein peptide 139-151 (PLP(139-151)). In this study we examined whether these Lactobacillus recombinants are able to induce oral and intranasal tolerance in an animal model for multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). Lewis rats received soluble cell extracts of Lactobacillus transformants intranasally three times prior to induction of EAE. For the induction of oral tolerance, rats were fed live transformed lactobacilli for 20 days. Ten days after the first oral administration EAE was induced. Intranasal administration of extracts containing guinea pig MBP (gpMBP) or MBP(72-85) significantly inhibited EAE in Lewis rats. Extracts of control transformants did not reduce EAE. Live lactobacilli expressing guinea pig MBP(72-85) fused to the marker enzyme beta-glucuronidase (beta-gluc) were also able to significantly reduce disease when administered orally. In conclusion, these experiments provide proof of principle that lactobacilli expressing myelin antigens reduce EAE after mucosal (intranasal and oral) administration. This novel method of mucosal tolerance induction by mucosal administration of recombinant lactobacilli expressing relevant autoantigens could find applications in autoimmune disease in general, such as multiple sclerosis, rheumatoid arthritis and uveitis.

Late asthmatic reactions induced by inhalation of allergen-derived T cell peptides

In individuals with atopy and asthma, allergen-derived T cell peptides injected intradermally induce isolated late asthmatic reactions (LARs) followed by bronchial hyporesponsiveness to peptide, inhibition of the allergen-induced cutaneous late-phase reaction, and altered T cell function in vitro. Laboratory animal data indicate that "activation" and "tolerance" also occur if peptides are inhaled. In this study, we show that inhalation of Fel d 1-derived peptides induced isolated LAR in individuals with asthma sensitive to cat allergen comparable with that previously demonstrated using intradermal injection. LARs were accompanied by eosinophilia and nonsignificant elevations of total cysteinyl leukotrienes in the sputum. Unlike the intradermal route, repeated inhalation of peptides was not associated with abrogation of the LAR and produced a sputum eosinophilia comparable with the first exposure. In addition, there was no inhibition of the cutaneous late-phase reaction to whole cat dander. Thus, isolated LAR induced by inhaled, allergen-derived peptides represent a novel model of provoked asthma and are not associated with the induction of hyporesponsiveness ("tolerance") in the skin or lung.

CD27/CD70, CD134/CD134 ligand, and CD30/CD153 pathways are independently essential for generation of regulatory cells after intratracheal delivery of alloantigen

BACKGROUND

We investigated whether blockade of tumor necrosis factor receptor-ligand pathways could generate regulatory cells induced by intratracheal delivery of alloantigen.

METHODS

CBA (H-2k) mice were pretreated with intratracheal delivery of splenocytes (1x10(7)) from C57BL/10 (H-2b) mice and intraperitoneal administration of monoclonal antibody (mAb) specific for CD70, CD134 ligand (CD134L), CD153, or CD137L. Seven days later, C57BL/10 hearts were transplanted into pretreated CBA mice. Some naive CBA mice underwent adoptive transfer of splenocytes (5x10(7)) from pretreated CBA mice and transplantation of a C57BL/10 heart on the same day.

RESULTS

Untreated CBA mice rejected C57BL/10 cardiac grafts acutely (median survival time [MST] 12 days). Pretreatment with intratracheal delivery of C57BL/10 donor splenocytes prolonged graft survival significantly (MST 84 days). Mice given intratracheal delivery of alloantigen plus anti-CD70, anti-CD134L, or anti-CD153 mAb, but not those given intratracheal delivery of alloantigen plus anti-CD137L mAb, rejected their graft acutely (MST 16, 14, 10, and 65 days, respectively). Adoptive transfer of splenocytes from mice pretreated with intratracheal delivery of alloantigen plus anti-CD70, CD134L, or CD153 mAb did not prolong survival of C57BL/10 cardiac grafts in naive secondary CBA recipients (MST 14, 11, and 11 days, respectively), whereas adoptive transfer of splenocytes from mice given intratracheal delivery of alloantigen plus anti-CD137L mAb did (MST 75 days).

CONCLUSION

The CD27/CD70, CD134/CD134L, and CD30/CD153 pathways are independently required for generation of regulatory cells in our model.

Induction of indefinite survival of fully allogeneic cardiac grafts and generation of regulatory cells by intratracheal delivery of alloantigens under blockade of the CD40 pathway

BACKGROUND

The authors previously showed that intratracheal delivery (ITD) of donor splenocytes induced prolonged survival of fully allogeneic cardiac grafts in mice. In this study, this treatment protocol was combined with blockade of the CD40 pathway in an attempt to induce operational tolerance.

METHODS

CBA mice were given donor splenocytes (1x107) or Kb peptide (100 microg) by ITD with or without antibody specific for mouse CD40 ligand (MR1, 200 microg) 7 days before transplantation of a C57BL/10 heart. Also, splenocyte (5 x 107) from primary recipient CBA mice given ITD of donor splenocytes or Kb peptide plus MR1 were adoptively transferred into naive CBA secondary recipients 7 days after the pretreatment and C57BL/10 hearts were transplanted into those recipients the same day.

RESULTS

ITD of donor splenocytes and Kb peptide induced prolonged survival of cardiac grafts (median survival time [MST], 74 and 56 days, respectively), whereas naive control mice and mice pretreated with syngeneic splenocytes had acute graft rejection (MST in both groups, 7 days). When MR1 was included, all grafts survived indefinitely (>200 days), but mice pretreated with MR1 alone had graft rejection (MST, 54 days). Mice bearing cardiac grafts had acceptance of skin grafts from C57BL/10 but not BALB/c mice, demonstrating that operational tolerance was induced. Secondary recipients given adoptive transfer of splenocytes from primary recipients of the combined treatment had acceptance of C57BL/10 grafts, suggesting that regulatory cells were generated within 7 days of pretreatment.

CONCLUSIONS

ITD of donor splenocytes or Kb peptide under blockade of the CD40 pathway induced operational tolerance and generated regulatory cells.

Anti-T-cell strategies in the treatment of allergic disease

Specific allergen immunotherapy (SIT) has been shown to be effective in modulating allergic responses in diseases such as rhinitis and asthma. However, the ability of whole allergen to cross link mast cell bound IgE, resulting in release of mediators such as histamine, has limited the application of this therapy to carefully selected patients who have failed conventional pharmacotherapy. The use of peptide sequences corresponding to T cell epitopes of the allergen has been postulated as an alternative to SIT in which high molar doses of T cell epitope can be delivered over a shorter time period and with improved safety. Using peptides from the sequence of the major cat allergen, Fel d 1, we have demonstrated the ability to induce transient T cell activation, resulting in isolated late asthmatic reactions, which are followed by prolonged periods of allergen-specific hyporesponsiveness, both to peptide re-challenge and to cutaneous challenge with whole allergen. Thus, peptide therapy may prove safe and efficacious in the treatment of allergic diseases.

Intranasal peptide-induced peripheral tolerance: the role of IL-10 in regulatory T cell function within the context of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated autoimmune disease commonly employed as a model for multiple sclerosis. Extensive studies have demonstrated that EAE may be prevented or ameliorated by the intranasal administration of soluble peptides representing encephalitogenic epitopes. There is increasing evidence that this peptide administration may function via the generation of regulatory cells. The mechanism of action of these cells remains controversial and it seems likely that it may vary between experimental models. At present the majority of work on regulatory cells has centred on characterising naturally occurring regulators, or those generated artificially ex vivo, and less is known about induced regulatory cells produced following peptide administration. This report aims to briefly outline the evidence for the existence of natural regulatory T cells and to introduce the sub-types of induced regulatory T cells now recognised. In several of these regulatory cell systems investigated to date, interleukin-10 (IL-10) has been shown to be important in cell function. This has not been directly investigated in a model employing peptide therapy to induce peripheral tolerance, hence the purpose of this study was to investigate the role of IL-10 in the generation of these regulatory cells. This work has employed both a TCR transgenic mouse system, for predominantly in vitro studies of cell function, and an IL-10 knock-out mouse strain to investigate in vivo disease protection. The results summarised in this report demonstrate that IL-10 is fundamentally important in the generation of disease protection following intranasal peptide therapy.

Inhibition of adjuvant-induced arthritis by interleukin-10-driven regulatory cells induced via nasal administration of a peptide analog of an arthritis-related heat-shock protein 60 T cell epitope

OBJECTIVE

To prevent and treat experimental arthritis via nasal administration of an altered peptide ligand (APL) from the major arthritogenic epitope in adjuvant-induced arthritis (AIA) and to explore the mechanisms involved.

METHODS

Peptides were administered nasally before and after induction of arthritis. Splenocytes and lymph node cells draining both the site of inflammation and the site of tolerance induction were used for cell transfer and were studied for antigen-specific T cell characteristics. In addition, attempts were made to stop T cell tolerance in vitro, using anticytokine antibodies.

RESULTS

Nasal administration of a modulatory APL of the heat-shock protein 60 (Hsp60) 180-188 T cell epitope, alanine 183, had a suppressive effect in AIA that far exceeded that of the wild-type epitope. In addition to its effectiveness in preventing AIA, alanine 183 may be effective in the treatment of ongoing AIA. The protective effect of alanine 183 can be passively transferred using activated splenocytes. Nasal administration of alanine 183 did not lead to detectable T cell proliferation or interleukin-2 (IL-2) production in mandibular lymph node cells, while transforming growth factor beta (TGF beta), IL-10, and IL-4 were readily produced. Likewise, after nasally induced tolerance, followed by induction of arthritis, inguinal lymph node cells produced IL-4, TGF beta, and IL-10. After neutralizing in vitro the individual cytokines with anticytokine antibodies, only blocking of IL-10 production led to reversal of tolerance, at the site of tolerance induction and the site of inflammation.

CONCLUSION

Nasal administration of an APL of Hsp60 180-188 induces highly effective protection against AIA through generation of regulatory cells that produce IL-4, TGF beta, and IL-10, whereas the induced tolerance is driven mainly by production of IL-10.

Autoreactivity in collagen-induced arthritis of rats: a potential role for T cell responses to self MHC peptides

Collagen-induced arthritis (CIA) is a chronic inflammatory arthropathy of rats which follows immunization with bovine type II collagen (bCII). T cell lines generated from arthritic rats have been shown to be self-reactive and proliferate in an autologous MLR, which is MHC-dependent. However, the peptides which drive this autoreactive response remain to be elucidated. T cell lines, generated initially to bCII, were cultured with synthetic peptides representing potential autoreactive self epitopes. C1q-c(50-64) peptide, which demonstrates sequence homology to the bCII(184-198) peptide, failed to stimulate T cell proliferation suggesting that the autologous MLR was not due to antigen cross-reactivity with this self peptide. In contrast, several peptides from the amino-terminal region of the RT1D(u) MHC class II molecule stimulated proliferative responses. These results suggest that immunization with bCII leads to activation of a population of autoreactive T cells which respond in an autologous MLR, and that this response could be due, in part, to T cell reactivity to self MHC peptides.

Zonula occludens toxin (Zot) interferes with the induction of nasal tolerance to gliadin

Both nasal and oral administration of soluble protein antigens (Ags) induce tolerance, a phenomenon that has hampered mucosal vaccine design. To produce active immunity the use of adjuvants co-administered with soluble Ags is required. Cholera toxin (CT) and Escherichia coli heat-labile enterotoxin (LT) were found to be powerful mucosal adjuvants, but they are not suitable for clinical use because of their associated toxicity. Therefore, there is the need to develop alternative strategies to deliver Ag in order to induce immunoprotection. Among these innovative tools, a new toxin, Zonula occludens toxin (Zot), produced by phages in toxigenic strains of Vibrio cholerae, has been recently exploited for its adjuvant activity at the mucosal level. The present study was undertaken to further highlight the adjuvant properties of Zot. The ability of Zot to induce a mucosal response to gliadin was demonstrated per serum antibody production. In our established model of systemic tolerance to gliadin, induced by its nasal administration, we found a reduced production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) upon administration of gliadin alone. This immune suppression was reverted in mice receiving gliadin together with Zot. As previously shown, the down-regulation of Th1-like cytokines was found to be associated to a suppression of the T-cell proliferation, while such a suppression was completely reverted by Zot co-administration. In conclusion, these data confirm Zot as a good mucosal adjuvant, considering its ability to interfere with the suppression of specific cell mediated immunity, probably as a result of the increased dose and/or altered processing of Ag at mucosal level.

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.

Preventive administration of Mycobacterium tuberculosis 10-kDa heat shock protein (hsp10) suppresses adjuvant arthritis in Lewis rats

Adjuvant arthritis (AA) can be induced in Lewis rats by immunization with Mycobacterium tuberculosis (Mt) in oil. We have investigated the modulation of AA by mycobacterial 10-kDa heat shock protein (hsp10), administered according to several protocols known to induce immune tolerance and immune deviation. Subcutaneous immunization with hsp10 in aqueous solution did not induce a cellular immune response, evaluated as delayed-type hypersensitivity (DTH) reaction, although anti-hsp10 antibodies, mainly of the IgG2a isotype, were detected in serum of treated animals. When rats were pretreated with hsp10 in aqueous solution before AA induction, no effects were seen on arthritis-induced joint swelling, although osteolysis and lymphocyte infiltration were slightly decreased. When other routes of administration were attempted, the strongest suppression was seen in the group of animals which received four intranasal (i.n.) administrations of protein and a subsequent challenge of hsp10 in incomplete Freund's adjuvant (IFA). We also found that the extent of disease suppression among the different groups of animals correlated with serum anti-hsp10 antibody levels. These antibodies mostly belonged to the IgG2a subtype, suggesting that immune deviation may play a role in the mechanism of disease suppression by hsp10.

Successful immunotherapy with matrix metalloproteinase-derived peptides in adjuvant arthritis depends on the timing of peptide administration

We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development of such therapies.

Induction of tolerance and cross-tolerance to methacrylate contact sensitizers

Induction of immunological tolerance to contact allergens might prevent undesired sensitization, in particular to occupational sensitizers, e.g., methacrylates (MA). Here, using a guinea pig model, we studied to which extent tolerance to one methacrylate might result in cross-tolerance to other congeners. Strong tolerance to the monomethacrylates hydroxy-ethyl MA (HEMA) and methyl MA, but not to the dimethacrylate ethylene-glycol MA (EGDMA) could be induced. The induced tolerance was stable, could not be broken by repeated sensitization attempts, and was mediated by specific suppressor cells, as demonstrated in T cell transfer experiments. In HEMA-tolerized animals, strong cross-tolerance to methacrylate congeners, including EGDMA, itself being nontolerogenic and showing the lowest cross-reactivity to HEMA, was found. Thus, oral application of contact allergens, to which skin contact cannot be avoided, e.g., in occupational settings, can induce broad cross-tolerance to related substances and might offer a promising preventive approach.

T cell lines generated with type II collagen proliferate in an autologous mixed lymphocyte response

Collagen-induced arthritis (CIA) is a T cell-dependent disease induced in susceptible rodents by immunizing with bovine type II collagen (bCII). In order to study T cell responses, a programme to generate bCII-specific T cell lines from arthritic rats was initiated. Lymph node cells from bCII-immune WA/KIR/kcl rats were cultured with bCII in vitro, and the T cells were isolated and restimulated with bCII-pulsed antigen presenting cells (APC) (thymus cells or splenic low density cells). However, T cells, generated initially to bCII, subsequently proliferated upon co-culture with syngeneic APC even in the absence of bCII. This suggests that exposure to bCII resulted in the activation of a population of self-reactive T cells which proliferate in an autologous mixed lymphocyte response. In contrast, short-term T cell lines generated to ovalbumin, heat-denatured bCII and the collagen peptide bCII(184-198) proliferated in response to specific antigen-pulsed APC without demonstrating self-reactivity. Since denatured bCII and bCII(184-198) peptide are not arthritogenic and failed to generate self reactivity in vitro, this suggests that the native triple helical conformation of bCII is required for stimulating autoreactive T cell responses.