Identification of an immunodominant type-II collagen peptide recognized by T cells in H-2q mice: self tolerance at the level of determinant selection.
ABSTRACT The T cell recognition of type-II collagen (CII) in H-2q mice, susceptible to CII-induced arthritis, was analyzed. With the use of T cell hybridomas derived from rat CII-immunized mice, a peptide corresponding to amino acids 245-270 on chick CII was found to harbor a T cell epitope which is present on heterologous CII (chick, rat, human, and bovine CII) but not on autologous CII. It was shown that this epitope was located within amino acids 260-270, although flanking regions in either direction were necessary for proper recognition. A peptide corresponding to human CII (256-270) was used for further studies. A single amino acid difference at position 266 between mouse CII (aspartic acid) and heterologous CII (glutamic acid) strongly influenced recognition of this peptide. No response towards the mouse peptide was seen with any of the T cell hybridomas. Inhibition studies revealed that the mouse peptide did not bind as well to major histocompatibility complex as the corresponding heterologous peptide. Both peptides gave rise to a T cell response after immunization. However, immunization with the heterologous peptide resulted in a response strictly directed to rat CII and the immunogen while immunization with the autologous peptide elicited T cells which reacted in a heteroclitic fashion, with a stronger response to the heterologous peptide than to the autologous peptide, and did respond to rat CII but not to mouse CII. We suggest that aspartic acid in position 266 results in a cryptic determinant in mouse CII which is neither recognized after CII immunization nor capable of tolerance induction. A glutamic acid at position 266, however, gives rise to an immunodominant epitope which is recognized by a large proportion of the T cells activated after immunization with heterologous CII.
Article: Cystatin C influences the autoimmune but not inflammatory response to cartilage type II collagen leading to chronic arthritis development.[show abstract] [hide abstract]
ABSTRACT: Collagen-induced arthritis (CIA) is a mouse model for rheumatoid arthritis (RA) and is induced after immunization with type II collagen (CII). CIA, like RA, is an autoimmune disease leading to destruction of cartilage and joints, and both the priming and inflammatory phases have been suggested to be dependent on proteases. In particular, the cysteine proteases have been proposed to be detrimental to the arthritic process and even immunomodulatory. A natural inhibitor of cysteine proteases is cystatin C. Cystatin C-deficient, sufficient and heterozygous mice were tested for onset, incidence and severity of CIA. The effect of cystatin C-deficiency was further dissected by testing the inflammatory effector phase of CIA; that is, collagen antibody-induced arthritis model and priming phase, that is, T cell response both in vivo and in vitro. In addition, in order to determine the importance of T cells and antigen-presenting cells (APCs), these cell populations were separated and in vitro T cell responses determined in a mixed co-culture system. Finally, flow cytometry was used in order to further characterize cell populations in cystatin C-deficient mice. Here, we show that mice lacking cystatin C, develop arthritis at a higher incidence and an earlier onset than wild-type controls. Interestingly, when the inflammatory phase of CIA was examined independently from immune priming then cystatin C-deficiency did not enhance the arthritis profile. However, in line with the enhanced CIA, there was an increased T cell and B cell response as delayed-type hypersensitivity reaction and anti-CII antibody titers were elevated in the cystatin C-deficient mice after immunization. In addition, the ex vivo naïve APCs from cystatin C-deficient mice had a greater capacity to stimulate T cells. Interestingly, dendritic cells had a more activated phenotype in naïve cystatin C-deficient mice. The lack of cystatin C enhances CIA and primarily affects in vivo priming of the immune system. Although the mechanism of this is still unknown, we show evidence for a more activated APC compartment, which would elevate the autoimmune response towards CII, thus resulting in an enhanced development of chronic arthritis.Arthritis research & therapy 03/2011; 13(2):R54. · 4.27 Impact Factor
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ABSTRACT: Previously we established that a cocoa-enriched diet in young rats reduces specific antibody production and the T helper (Th) lymphocyte proportion in lymphoid tissues. The aim of the present study was to ascertain the modulatory ability of a cocoa flavonoid-enriched diet on collagen-induced arthritis (CIA), which is mediated by anti-collagen autoantibody response and Th lymphocyte activation. Female Louvain (LOU) rats were fed with a cocoa-enriched diet, beginning 2 weeks before CIA induction. Hind-paw swelling and serum cytokine and anti-collagen antibody concentrations were determined. Anti-collagen antibody-secreting cell counts and lymphocyte subset proportions were established in inguinal lymph nodes (ILN). Reactive oxygen species (ROS), nitric oxide (NO) and TNFα produced by peritoneal macrophages were determined. Although arthritic cocoa-fed rats showed a similar hind-paw swelling time course as the arthritic animals fed a standard diet, the cocoa intake was able to decrease specific IgG2a, IgG2b and IgG2c titres. Moreover, cocoa intake in CIA rats reduced ROS production, TNFα and NO release from peritoneal macrophages, and decreased the Th:cytotoxic T cell ratio in ILN. In conclusion, a cocoa flavonoid-enriched diet in LOU rats with CIA produced no effect on hind-paw swelling but was able to modulate the specific antibody response and also the Th lymphocyte proportion, as well as the synthesis of pro-inflammatory mediators from peritoneal macrophages. Therefore, a cocoa-enriched diet could be a good adjuvant therapy in disorders with oxidative stress or autoimmune pathogenesis.The British journal of nutrition 07/2011; 107(4):523-32. · 3.45 Impact Factor
Article: Collagen type II and a thermo-responsive polymer of N-isopropylacrylamide induce arthritis independent of Toll-like receptors: a strong influence by major histocompatibility complex class II and Ncf1 genes.[show abstract] [hide abstract]
ABSTRACT: We established and characterized an arthritis mouse model using collagen type II (CII) and a thermo-responsive polymer, poly(N-isopropylacrylamide) (PNiPAAm). The new PNiPAAm adjuvant is TLR-independent, as all immunized TLR including MyD88-deficient mice developed an anti-CII response. Unlike other adjuvants, PNiPPAm did not skew the cytokine response (IL-1β, IFN-γ, IL-4, and IL-17), as there was no immune deviation towards any one type of immune spectrum after immunization with CII/PNiPPAm. Hence, using PNiPAAm, we studied the actual immune response to the self-protein, CII. We observed arthritis and autoimmunity development in several murine strains having different major histocompatibility complex (MHC) haplotypes after CII/PNiPAAm immunization but with a clear MHC association pattern. Interestingly, C57Bl/6 mice did not develop CII-induced arthritis, with PNiPAAm demonstrating absolute requirement for a classical adjuvant. Presence of a gene (Ncf1) mutation in the NADPH oxidation complex has a profound influence in arthritis and using PNiPAAm we could show that the high CIA severity in Ncf1 mutated mice is independent of any classical adjuvant. Macrophages, neutrophils, eosinophils, and osteoclasts but not mast cells dominated the inflamed joints. Furthermore, arthritis induction in the adjuvant-free, eosinophil-dependent Vβ12 DBA/1 mice could be shown to develop arthritis independent of eosinophils using CII/PNiPAAm. Thus, biocompatible and biodegradable PNiPAAm offers unique opportunities to study actual autoimmunity independent of TLR and a particular cytokine phenotype profile.American Journal Of Pathology 09/2011; 179(5):2490-500. · 4.89 Impact Factor