Continuous nasal administration of antigen is critical to maintain tolerance in adoptively transferred autoimmune arthritis in SCID mice

Immune tolerance induction with multiepitope peptide derived from citrullinated autoantigens attenuates arthritis manifestations in adjuvant arthritis rats

Citrullinated peptides are major targets of disease-specific autoantibodies in rheumatoid arthritis. Currently, citrullinated peptides are used as biomarkers for diagnosing rheumatoid arthritis by measuring anti-citrullinated protein Ab (ACPA) titers in patients' sera. The accumulation of citrullinated proteins at synovial inflammation sites suggests that they are possible targets for tolerance induction. The objective of the present study was to determine whether citrullinated peptides could induce tolerance in an experimental arthritis model in rats. In view of the multiplicity of target citrullinated autoantigens described for ACPA, we generated a multiepitope citrullinated peptide (Cit-ME), derived from major prevalent citrullinated autoantigens (citrullinated filaggrin, fibrinogen, vimentin, and collagen type II), and studied its effects on arthritic rats. Adjuvant-induced arthritis was induced in Lewis rats. Beginning at day 7 after disease induction, the rats received eight s.c. injections of Cit-ME on alternate days. Differences in clinical status and modulation of T cell populations were analyzed. In adjuvant-induced arthritis rats treated with Cit-ME, disease severity was significantly reduced compared with that of untreated rats. Moreover, amelioration of disease manifestations was related to an increased regulatory T cell subset and an elevated apoptosis rate of T cells associated with reduced Th17 cells. Thus, the use of citrullinated peptides-based immunotherapy may be a promising approach for tolerance induction in experimental arthritis and perhaps even in susceptible individuals that are ACPA-seropositive in human arthritis.

Long term immunologic consequences of experimental stroke and mucosal tolerance

Background

An inflammatory insult following middle cerebral artery occlusion (MCAO) is associated with a predisposition to develop a deleterious autoimmune response to the brain antigen myelin basic protein (MBP). Induction of immunologic tolerance to brain antigens prior to MCAO prevents this deleterious autoimmune response and is associated with better functional outcome early after stroke. In this study, we sought to determine the long term immunologic consequences of experimental stroke and induction of mucosal tolerance.

Methods

Male Lewis rats were tolerized to MBP or ovalbumin (OVA) by intranasal administration prior to MCAO and administration of lipopolysaccharide (LPS). Neurological outcome was assessed at set points after MCAO and animals sacrificed at 3 months; the immune response to MBP in brain and spleen was determined using ELISPOT assay and degree of cellular inflammatory brain infiltrate assessed by immunocytochemistry.

Results

Animals that developed a pro-inflammatory (TH1) response to MBP experienced worse outcome, while those that developed a regulatory response (TREG) experienced better outcome. A TREG response in spleen was also associated with decreased inflammation and an increase in the number of FoxP3 positive cells in brain. In this study, tolerization to MBP prior to MCAO was associated with a tendency to develop a TH1 response to MBP by 3 months after MCAO.

Conclusion

These data show that induction of immunological tolerance to MBP is associated with improved outcome after stroke. This study, however, raises concern about the potential for inadvertent induction of detrimental autoimmunity through mucosal administration of antigen.

Tolerization with Hsp65 induces protection against adjuvant-induced arthritis by modulating the antigen-directed interferon-gamma, interleukin-17, and antibody responses

OBJECTIVE

Pretreatment of Lewis rats with soluble mycobacterial Hsp65 affords protection against subsequent adjuvant-induced arthritis (AIA). This study was aimed at unraveling the mechanisms underlying mycobacterial Hsp65-induced protection against arthritis, using contemporary parameters of immunity.

METHODS

Lewis rats were given 3 intraperitoneal injections of mycobacterial Hsp65 in solution prior to the initiation of AIA with heat-killed Mycobacterium tuberculosis. Thereafter, mycobacterial Hsp65-specific T cell proliferative, cytokine, and antibody responses were tested in tolerized rats. The roles of anergy and the indoleamine 2,3 dioxygenase (IDO)-tryptophan pathway in tolerance induction were assessed, and the frequency and suppressive function of CD4+FoxP3+ Treg cells were monitored. Also tested was the effect of mycobacterial Hsp65 tolerization on T cell responses to AIA-related mycobacterial Hsp70, mycobacterial Hsp10, and rat Hsp65.

RESULTS

The AIA-protective effect of mycobacterial Hsp65-induced tolerance was associated with a significantly reduced T cell proliferative response to mycobacterial Hsp65, which was reversed by interleukin-2 (IL-2), indicating anergy induction. The production of interferon-gamma (but not IL-4/IL-10) was increased, with concurrent down-regulation of IL-17 expression by mycobacterial Hsp65-primed T cells. Neither the frequency nor the suppressive activity of CD4+FoxP3+ T cells changed following tolerization, but the serum level of anti-mycobacterial Hsp65 antibodies was increased. However, no evidence was observed for a role of IDO or cross-tolerance to mycobacterial Hsp70, mycobacterial Hsp10, or rat Hsp65.

CONCLUSION

Tolerization with soluble mycobacterial Hsp65 leads to suppression of IL-17, anergy induction, and enhanced production of anti-mycobacterial Hsp65 antibodies, which play a role in protection against AIA. These results are relevant to the development of effective immunotherapeutic approaches for autoimmune arthritis.

Mucosal administration of alpha-fodrin inhibits experimental Sjögren's syndrome autoimmunity

Introduction

α-Fodrin is an autoantigen in Sjögren's syndrome. We hypothesized that mucosal administration of α-fodrin might prevent the disease.

Methods

Four-week-old NOD mice were immunized (intranasal) with a 1 μg or 10 μg dose of α-fodrin every other day. PBS 10 μl/dose and Glutathione transferase (GST 10 μg/dose (control mice) were intranasally administrated by the same procedure. The salivary flow was maintained in immunized animals. The animals were analyzed for the presence of anti-Sjögren's syndrome A, anti-Sjögren's syndrome B, rheumatoid factor and antinuclear, anti-α-fodrin, and anti-type 3 muscarinic acetylcholine receptor polypeptide (anti-M3RP) by immunofluorescence or ELISA. The cytokines IFNγ and IL-10 were measured by ELISA. Salivary glands were examined by H&E staining and immunohistochemical analysis. The water-volume intake was calculated for each group. The induction of regulatory T cells was assessed by fluorescence-activated cell sorting analysis for the frequency of Foxp3⁺ cells among peripheral CD4⁺CD25⁺ T cells.

Results

The appearance of anti-α-fodrin and anti-M3RP antibodies was delayed in mice immunized with α-fodrin. The titers of anti-α-fodrin and anti-M3RP antibodies were lower in immunized mice (P < 0.05), but there was no significant difference between the low-dose or high-dose immunization groups. Five out of eight mice in the GST group, five of eight mice in the PBS group, two of eight mice in the α-fodrin 1 μg/dose group, and three out of eight mice in the α-fodrin 10 μg/dose were positive for antinuclear antibodies. The levels of serum IFNγ in mice immunized with 1 μg/dose or 10 μg/dose α-fodrin, with PBS, and with GST were 41.9 ± 16.2 pg/ml, 37.1 ± 15.4 pg/ml, 86.8 ± 17.8 pg/ml and 71.6 ± 11.1 pg/ml, respectively, while we found no difference in the levels of serum IL-10 among the groups. The number of Foxp3⁺ CD4⁺CD25⁺ regulatory T cells was higher in the α-fodrin groups compared with the PBS and GST control groups (P < 0.05). Lymphocytic infiltration and expression of α-fodrin in the salivary glands was decreased in α-fodrin-treated groups. The fluid intake of mice in the 1 μg/dose α-fodrin, 10 μg/dose α-fodrin, PBS, and GST groups was 39.2 ± 2.1 ml, 40.4 ± 2.5 ml, 49.3 ± 3.1 ml and 51.6 ± 2.8 ml, respectively.

Conclusion

Mucosal administration of α-fodrin effectively inhibited the progression of experimental Sjögren's syndrome autoimmunity.

Diet and rheumatoid arthritis: a review of the literature

INTRODUCTION

Rheumatoid arthritis is a common inflammatory condition. A large number of patients seek alternative or complementary therapies of which diet is an important component. This article reviews the evidence for diet in rheumatoid arthritis along with the associated concept of oral tolerization.

METHODS

References were taken from Medline from 1966 to September 2004. The keywords, rheumatoid arthritis, diet, n-3 fatty acids, vitamins, and oral tolerization, were used.

RESULTS

Randomized controlled trials (RCTs) indicate that dietary supplementation with n-3 fatty acids provides modest symptomatic benefit in groups of patients with rheumatoid arthritis. Epidemiological studies and RCTs show cardiovascular benefits in the broader population and patients with ischemic heart disease. A number of mechanisms through which n-3 fats may reduce inflammation have been identified. In a small number of patients with rheumatoid arthritis, other dietary manipulation such as fasting, vegan, and elimination diets may have some benefit. However, many of these diets are impractical or difficult to sustain long term.

CONCLUSIONS

Dietary manipulation provides a means by which patients can a regain a sense of control over their disease. Dietary n-3 supplementation is practical and can be easily achieved with encapsulated or, less expensively, bottled fish oil.

Molecular manipulation with the arthritogenic epitopes of the G1 domain of human cartilage proteoglycan aggrecan

Systemic immunization of BALB/c mice with human cartilage proteoglycan (PG) aggrecan induces progressive polyarthritis. The G1 domain of the PG aggrecan molecule contains most of the T cell epitopes, including three immunodominant ('arthritogenic') and at least six subdominant T cell epitopes. The three dominant T cell epitopes (P49, P70 and P155) were deleted individually or in combination by site directed mutagenesis, and the recombinant human G1 (rhG1) domain (wild type and mutated) proteins were used for immunization. Close to 100% of BALB/c mice immunized with the wild-type (nonmutated) rhG1 domain developed severe arthritis, which was 75% in the absence of P70 (5/4E8) epitope, and very low (< 10% incidence) when all three dominant T cell epitopes were deleted. The onset was delayed and the severity of arthritis reduced in animals when dominant T cell epitopes were missing from the immunizing rhG1 domain. The lack of T cell response to the deleted epitope(s) was specific, but the overall immune response against the wild-type rhG1 domain of human PG was not significantly affected. This study helped us to understand the dynamics and immune-regulatory mechanisms of arthritis, and supported the hypothesis that the development of autoimmune arthritis requires a concerted T cell response to multiple epitopes, rather than the immune response to a single arthritogenic structure.

Naive transgenic T cells expressing cartilage proteoglycan-specific TCR induce arthritis upon in vivo activation

Proteoglycan (PG)-induced arthritis (PGIA), a murine model for rheumatoid arthritis (RA), is driven by antigen (PG)-specific T and B cell activation. In order to analyze the pathogenic role of antigen-specific T cells in the development of autoimmune arthritis, we have generated a transgenic (Tg) mouse. The CD4(+) T cells of this TCR-5/4E8-Tg line express a functional T cell receptor (TCR) composed of the Valpha1.1 and Vbeta4 chains with specificity for the dominant arthritogenic T cell epitope of human cartilage PG. Adoptive transfer of naive TCR-5/4E8-Tg cells induced arthritis with severe clinical symptoms in syngeneic immunodeficient BALB/c.RAG2(-/-) mice. In vivo activation of TCR-5/4E8-Tg CD4(+)Vbeta4(+) cells with cartilage PG seemed to be critical for arthritis induction. Arthritis never developed after transfer of naive wild-type cells. The arthritis was characterized as a chronic progressive disease with intermittent spontaneous exacerbations and remissions. Inflamed joints showed extensive cartilage damage and bone erosions leading to massive ankylosis in peripheral joints. These PG epitope-specific TCR-5/4E8-Tg mice can be valuable research tools for studying antigen-driven T cell regulation in arthritis, and migration of T cells to the joints. In addition the model may be used for the development of immune modulating strategies in T cell-mediated autoimmune diseases.

Oral and nasal administration of chicken type II collagen suppresses adjuvant arthritis in rats with intestinal lesions induced by meloxicam

AIM

To investigate the curative effects of oral and nasal administration of chicken type II collagen (CII) on adjuvant arthritis (AA) in rats with meloxicam-induced intestinal lesions.

METHODS

AA model in Sprague-Dawley (SD) rats with or without intestinal lesions induced by meloxicam was established and those rats were divided randomly into six groups which included AA model, AA model+meloxicam, AA model+oral CII, AA model+nasal CII, AA model+ meloxicam+oral C II and AA model+meloxicam+nasal CII (n = 12). Rats was treated with meloxicam intragastrically for 7 d from d 14 after immunization with complete Freund's adjuvant (CFA), and then treated with chicken CII intragastrically or nasally for 7 d. Histological changes of right hind knees were examined. Hind paw secondary swelling and intestinal lesions were evaluated. Synoviocyte proliferation was measured by 3-(4,5-dimethylthiazol-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) method. Activities of myeloperoxidase (MPO) and diamine oxidase (DAO) from supernatants of intestinal homogenates were assayed by spectrophotometric analysis.

RESULTS

Intragastrical administration of meloxicam (1.5 mg/kg) induced multiple intestinal lesions in AA rats. There was a significant decrease of intestinal DAO activities in AA+meloxicam group (P<0.01) and AA model group (P<0.01) compared with normal group. DAO activities of intestinal homogenates in AA+meloxicam group were significantly less than those in AA rats (P<0.01). There was a significant increase of intestinal MPO activities in AA+meloxicam group compared with normal control (P<0.01). Oral or nasal administration of CII (20 microg/kg) could suppress the secondary hind paw swelling(P<0.05 for oral CII; P<0.01 for nasal CII), synoviocyte proliferation (P<0.01) and histopathological degradation in AA rats, but they had no significant effects on DAO and MPO changes. However, oral administration of CII (20 microg/kg) showed the limited efficacy on arthritis in AA+meloxicam model and the curative effects of nasal CII (20 microg/kg) were shown to be more efficient than that of oral CII (20 microg/kg) both in AA model and in AA+meloxicam model (P<0.05).

CONCLUSION

Oral administration of CII shows the limited efficacy on arthritis in AA rats with intestinal lesions, and nasal administration of CII is more efficient than oral administration of CII to induce mucosal tolerance in AA rats.

Induction of arthritis in SCID mice by T cells specific for the “shared epitope” sequence in the G3 domain of human cartilage proteoglycan

OBJECTIVE

To study the immunologic function and determine the fine epitope structure of a synthetic peptide p135H ((2373)TTYKRRLQKRSSRHP) of the G3 domain of human cartilage proteoglycan (aggrecan), which contains a highly homologous sequence motif of the shared epitope (QKRAA), the most common sequence motif in HLA-DR4 alleles, which predispose humans to the development of rheumatoid arthritis (RA).

METHODS

Synthetic p135 peptides with altered sequences were used for (hyper)immunization of arthritis-susceptible BALB/c mice and then challenged with a single dose of cartilage proteoglycan. Human p135 (p135H) and mouse p135 (p135M) synthetic peptides of the G3 domain of aggrecan were used to prime lymphocytes, which were then used for adoptive transfer of arthritis into "presensitized" SCID mice, determining cross-reactivity among p135 peptides and their analogous sequences, and generating T cell hybridomas. T cell hybridomas were also used for arthritis transfer into SCID mice and for characterizing the fine epitope structure of T cell receptor (TCR) and major histo-compatibility complex (MHC) binding sites of the immunogenic/arthritogenic p135H sequence.

RESULTS

While p135H peptide-(hyper)immunized mice became sensitized, they developed arthritis only after injection of a single dose of cartilage proteoglycan aggrecan. An altered peptide sequence (p135H-AA) carrying the shared epitope motif (QKRAA) was as effective as the natural peptide p135H sequence for inducing arthritis. Mouse p135M-specific lymphocytes induced arthritis with a lower incidence, but synthetic peptides to Escherichia coli heat-shock protein (DnaJ) or HLA-DR4 allele (both having the shared epitope sequence with different flanking regions) were also positive. Fine epitope sequence recognition of an arthritogenic T cell hybridoma derived from p135H-primed lymphocyte population was determined. Interestingly, in the most central position, a basic amino acid triplet of p135H peptide was found to be the MHC-binding motif, whereas the flanking amino acids bound to the TCR.

CONCLUSION

Peptide p135H, corresponding to the peptide sequence in the G3 domain of human cartilage proteoglycan aggrecan, is immunogenic/arthritogenic in BALB/c mice. Peptide p135H includes a highly homologous motif of the shared epitope, a sequence that is overrepresented in bacterial heat-shock proteins, envelope protein of human JC polyomavirus, and numerous HLA-DR4 alleles. Since the G3 domain of cartilage proteoglycan aggrecan with the p135 sequence is "lost" during the normal metabolic turnover of cartilage proteoglycan or in pathologic conditions, an antigenoriented T cell migration into joints of presensitized (susceptible) individuals may contribute to the organ-specificity of RA.