Luthra, Harvinder S.

Abstract DRB1*0401 has been associated with predisposition to rheumatoid arthritis while DRB1*0402 is associated with resistance. We have generated transgenic mice lacking endogenous H2-A and E molecules (AEo) but expressing DRB1*0401 or DRB1*0402 molecules. All transgenic mice expressed functional DR molecules which could positively and negatively select various Vβ T cell repertoire profile. Transgenic mice were studied in vivo for induction of arthritis following immunization with type II collagen. DRB1*0401 mice are susceptible to collagen-induced arthritis while DRB1*0402 mice are resistant. Presence of DR4 leads to arthritis predominantly in female mice. CIA susceptible AEo.DQ8 mice have been shown to develop arthritis without a gender bias. However, AEo mice expressing DRB1*0401.DQ8 develop arthritis in female mice with a ratio of 3F:1M, similar to that in humans. DRB1*0402 mice did not show any defect in humoral response though they demonstrated a lower cellular response to CII and an increased activation-induced cell death compared to susceptible mice. In vitro T cell response with superantigen staphylococcal enterotoxin B and Concovalin A showed that DRB1*0402 mice are not defective in generating T cell response. The resistant mice showed an increased cell death in thymus suggesting deletion of autoreactive T cells at thymic level might be one reason for protection. The data suggest that DRB1 polymorphism lead to selection of TCR in thymus thus controlling the selection of autoreactive T cells available in periphery. Thus these transgenic mice may be useful to study the reasons for gender-bias observed in human patients develop therapeutic strategies.

Abstract Although association of HLA-B27 with human spondyloarthropathies has been known for several years, its role in disease pathogenesis is not understood. Recently, a few investigators have proposed that presentation of B27-derived peptides by MHC class II molecules may be the underlying mechanism. HLA-B27 transgenic rat and mouse models have provided a new tool for understanding the exact role of B27 in disease pathogenesis. HLA-B27 mice lacking endogenous β2-microglobulin (B27+β2mo) develop disease after they are transferred from the barrier facility to the conventional colony. This model was utilized to test the hypothesis that B27-derived peptide presented by MHC class II molecules is the cause of the disease. The MHC class II knockout gene, Aβo, was bred into our B27+β2mo mice, and disease manifestation was monitored. These mice develop spontaneous disease, demonstrating that MHC class II molecules do not play a major role in B27-related disease. Thus, the disease is not manifested by presentation of B27-derived peptides by class II molecules, since these mice are devoid of H2-A and H2-E molecules. Furthermore, in vivo treatment with mAb against the heavy chain of B27 reduced the incidence of disease in B27+β2mo mice. Our results clearly demonstrate that B27 heavy chains are directly involved in the disease process.

Abstract HLA-DRB1*0401 has been associated with predisposition to develop rheumatoid arthritis (RA) while *0402 has been linked with resistance to develop RA. Using transgenic mice, we showed that *0401 mice are susceptible to develop collagen-induced arthritis (CIA) that mimics human disease in histopathology, production of autoantibodies and sex-bias while *0402 mice are not susceptible. In this study, we determined if *0401 mice have CD4 T cell repertoire that is predetermined to produce proinflammatory cytokines. The data shown here supports that both *0401 and *0402 mice can produce Th1/TH17 cytokines although conditions required for production of Th17 cytokines differ between the 2 strains. In context of CIA, *0402 mice generate a Th2 response that may explain its resistance to develop CIA. Further, our data supports that a significant subset of naïve CD4 T cells when activated in polarizing conditions can generate T regulatory cells in *0402 but not *0401 mice. We hypothesize that *0401 has been evolutionarily selected due to its ability to clear infection. Our data suggests that *0401 generates a storm of cytokines in response to bacterial products and may be more efficient in clearing infection than *0402. Autoimmunity is a bystander effect of the cytokine storm ensuing immune dysregulation along with the presence of lower number of T regulatory cells in *0401 mice.

Abstract We have generated transgenic (tg) mice expressing HLA-DQ8αβ (DQA1*0301/DQB*0302) or HLA-DQ6αβ (DQA1*0103/DQB1*0601) molecules lacking endogenous murine class II expression (Aβ0) to investigate the ability of these HLA class II to present type II collagen (CII) and induce collagen-induced arthritis. The DQ8αβ tg mice responded strongly to CII, developing severe arthritis, while DQ6αβ tg mice were nonresponsive to CII. The addition of the mixed haplotype DQ8α6β molecule did not significantly influence CII reactivity. To examine the interaction of DQ6αβ and DQ8αβ molecules in vivo, we generated double tg DQ6αβ/8αβ (Aβ0) mice expressing both the α- and β-chains of DQ6 and DQ8 molecules by mating DQ6αβ (Aβ0) and DQ8αβ (Aβ0) tg mice. CII-immunized DQ6αβ/8αβ tg mice developed severe experimental polychondritis, exhibiting both polyarthritis and auricular chondritis. The clinical, serologic, and histologic manifestations of experimental polychondritis are similar to those symptoms in human relapsing polychondritis. The susceptibility of DQ6αβ/8αβ tg mice compared with resistance in the parental strains suggests that expression of both the DQ6αβ and DQ8αβ tgs, unique to the DQ6αβ8αβ tg strain, is important in susceptibility to experimental polychondritis. The DQ6αβ/8αβ tg mice provide a model to investigate putative autoantigens and the mechanisms of pathogenesis involved in relapsing polychondritis as well as the influence of the expression of multiple HLA class II molecules on the disease process.

Abstract HLA-DQA1*0301 and HLA-DQB1*0302 genes encoding the HLA-DQ8 molecule and HLA-DQA1*0103 and HLA-DQB1*0601 genes encoding the HLA-DQ6 molecule were introduced into H-2Aβo knockout mice. Three lines of transgenic mice were established: HLA-DQ8, HLA-DQ6, and HLA-DQ8β6α. HLA-DQ8 mice are susceptible to collagen-induced arthritis, while HLA-DQ6 mice are resistant. HLA-DQ8β6α mice develop polychrondritis in addition to arthritis. Transgenic mice were primed and challenged with individual synthetic peptides representing human type II collagen. A total of 101 synthetic peptides were tested in each transgenic line of mice. HLA-DQ8 mice responded to 15 synthetic peptides representing all cyanogen bromide fragments. In contrast, HLA-DQ6 mice responded to a subset of the peptides recognized by HLA-DQ8 T cells. HLA-DQ8β6α mice, although exhibiting diminished responses to the majority of HLA-DQ8-restricted determinants, elicited enhanced responses to two peptides. In addition, HLA-DQ8β6α mice respond to two unique peptide determinants contained within cyanogen bromide fragments CB10 and CB11 showing the significance of mixed isotype dimers in the immune response. The determinants recognized by the HLA-DQ transgenic mice are distinct from those previously identified using conventional laboratory mice. These results suggest that human class II transgenic mice offer a means of identifying human class II-restricted epitopes associated with potential human autoantigens.

Abstract SWR/J mice are resistant to collagen-induced arthritis (CIA) despite having a susceptible H-2q haplotype. We have earlier demonstrated the possible role of the V beta TCR mutation of SWR in the resistance to CIA. To investigate the influence of the C5 deficiency of SWR in this resistance, crosses were made between SWR and A/J (C5 deficient, TCRwild, H-2a), and between SWR and C3H.A (C5 sufficient, TCRwild, H-2a). Upon immunization with bovine type II collagen in adjuvant, there was a similar incidence and severity of arthritis in H-2q-bearing mice in the back-crosses A x (SWR x A) ad C3H.A x (SWR x C3H.A). The absence of hemolytic complement was confirmed in the arthritic A x (SWR x A) back-cross mice by standard SRBC hemolytic assays. In addition C57L (H-2b) mice, which were C5 sufficient but had a V beta TCR deletion mutation similar to SWR, could not complement for CIA susceptibility in H-2q-bearing C57L x (SWR x C57L) back-crosses and in (C57L x SWR)F2 hybrids. These studies show that complement C5 does not play a significant role in CIA susceptibility, and further implicate the V beta TCR mutation in the resistance to CIA in SWR mice.

Abstract B10.Ek alpha transgenic mice were mated with H2-E B10.Q and SWR mice. F1 and F1 x parental strain backcross progeny were tested for arthritis and autoimmune reactivity to mouse type II collagen (MII) after immunization with bovine, chick, deer, or human type II collagen. The results were correlated with the H-2 haplotype (b/q vs q/q) and the TCR V beta profile of peripheral blood T cells in each mouse. Hybrid progeny expressed TCR profiles different from either parent because of the TCR V beta genomic deletions of SWR mice (V beta a), the wild-type TCR allele of C57Bl/10 (B10) mice (V beta b), and the intrathymic negative selection processes resulting from cell surface expression of Ek alpha-A q beta or Eb beta-Ek alpha, together with the integrated retroviral genes Mtv-9 originating in B10 mice and Mtv-7 (Mls-1a) from SWR mice. (B10.Ek alpha x SWR)F1 mice developed higher IgG anti-MII Ab titers, but much milder arthritis than (B10.E x B10.Q)F1 mice. Expression of Ek alpha did not change the level of IgG anti-MII Ab nor the degree of susceptibility to collagen-induced arthritis (CIA) in the H-2q/q and H-2b/q progeny of (B10.Ek alpha x B10.Q)F1 x B10.Q matings, indicating that the Mtv-9-reactive, TCR V beta 5+, and V beta 11+ T cells are not critical to CIA. Among bovine type II collagen-immunized (B10.Ek alpha x SWR)F1 x SWR backcross mice: 1) arthritis severity is associated with the presence of V beta b (p < or = 0.01) and expression of Ek alpha (p < or = 0.05), but not with the MHC haplotype (b/q vs q/q); 2) regression analysis showed a significant association (R = 0.99) between IgG anti-MII Ab titers and the level of Mtv-7-reactive V beta 6+ T cells that was detectable in the IgG1, but not the IgG2a subclass. The data prompt the speculation that Mtv-7-reactive V beta 6+ (or V beta 7+) T cells in (B10.EK alpha x SWR)F1 x SWR mice express Th2-type properties, and thus contribute to the combination of mild arthritis but high anti-MII Ab titers that characterize mice of SWR heritage.

Abstract Type II collagen from six mammalian species was investigated for the capacity to induce an immune response and collagen-induced arthritis (CIA) in C57/B10 congenic mouse strains. H-2q haplotype mice were susceptible to chick, bovine, deer, rat, and human type II collagen, but were resistant to arthritis induced by porcine type II collagen. H-2r haplotype mice only developed CIA in response to bovine, deer, and porcine collagen. High antibody responses in the absence of disease, directed against a specific type II collagen, were observed in many independent haplotypes. The cross-reactive capacity of different antisera to the various collagen species was studied. The data support the existence of two arthritogenic and multiple nonarthritogenic epitopes on the type II collagen molecule.

Abstract The use of an anti-IL-2R antibody, 7D4, was investigated in vivo in the suppression of collagen-induced arthritis in mice. 7D4 was shown to reduce the incidence of arthritis in a group of mice immunized with type II collagen as compared with a group similarly immunized with collagen and treated with a control isotype matched anti-Forsmann antibody. 7D4 was also shown to reduce the severity of arthritis in the treated mice as compared to the mice in the group treated with the control antibody. Anti-IL-2R antibodies may be useful in the treatment of autoimmune diseases by selectively suppressing activated T cells.