The role of leukocyte function-associated antigen-1 in animal models of inflammation.

Both preclinical and clinical data have identified leukocyte function-associated antigen-1 (LFA-1) as an important component of inflammatory disease states. We evaluated small molecule inhibitors of this glycoprotein in several animal models in which the inflammatory process is dependent on human or non-human primate LFA-1. (R)-5(4-bromobenzyl)-3(3,5-dichlorophenyl)-1,5-dimethylimidazolidine-2,4-dione, BIRT 377, effectively suppressed the production of human immunoglobulin (IgG) following reconstitution of severe combined immunodeficient (SCID) mice with human peripheral blood mononuclear cells. The BIRT 377 analog, BIX 642, inhibited the cellular infiltrate and increase in skin thickness associated with the delayed-type hypersensitivity reaction in previously immunized squirrel monkeys challenged with antigen. BIX 642 also inhibited the trans-vivo delayed-type hypersensitivity response in the footpads of SCID mice injected with human peripheral blood mononuclear cells and donor-sensitive antigen. These results demonstrate the efficacy of small molecule inhibitors of LFA-1 in preclinical models of inflammation dependent on human or non-human primate LFA-1.

V(beta)8(+) T cells protect from demyelinating disease in a viral model of multiple sclerosis.

Previous studies illustrated the influence of T cell subsets on susceptibility or resistance to demyelination in the Theiler's murine encephalomyelitis virus (TMEV) model of multiple sclerosis. Genetic segregation analysis showed a correlation with disease phenotype in this model with particular V(beta) genes. In this study we investigated the contribution of specific V(beta) TCR to the pathogenesis of virus-induced demyelinating disease. Spectratype analysis of cells infiltrating the CNS early in infection demonstrated an over-representation of V(beta)8(+) T cells in mice expressing a susceptible H-2 haplotype. We infected transgenic mice expressing the V(beta)8.2 TCR directed against a non-TMEV antigen and found an increase in demyelinating disease in mice of either susceptible or resistant background compared with littermate controls. In addition, depletion studies with an anti-V(beta)8-specific antibody in both susceptible (B10.Q) and resistant (C57BL/6) mice resulted in increased demyelination. TCR analysis of VP2-specific cytotoxic T cell clones from mice with a resistant genotype identified only the V(beta)8.1 TCR, suggesting that limited T cell diversity is critical to TMEV clearance. Together, these results support a protective role for V(beta)8(+) T cells in virus-induced demyelinating disease.

Cutting edge: a small molecule antagonist of LFA-1-mediated cell adhesion.

LFA-1 (CD18,CD11a) is a cell-adhesion molecule that mediates critical immunological processes. In this paper we report the discovery and characterization of (R)-5-(4-bromobenzyl)-3-(3, 5-dichlorophenyl)-1,5-dimethylimidazolidine-2,4-dione (BIRT 377), an orally bioavailable small molecule that interacts specifically with LFA-1 via noncovalent binding to the CD11a chain and prevents LFA-1 from binding to its ligand, ICAM-1. BIRT 377 inhibits lymphocyte activity both in vitro and in vivo, in functional assays that require LFA-1-mediated cell adhesion. These results demonstrate that LFA-1-mediated leukocyte adhesion can be antagonized with noncharged, low m.w. molecules and suggest that the potential therapeutic value of adhesion inhibitors can be attained with a small, orally bioavailable compound.

Essential role of T cell NF-kappa B activation in collagen-induced arthritis.

NF-kappa B/Rel proteins are ubiquitous transcription factors that are activated by proinflammatory signals or engagement of Ag receptors. To study the role of NF-kappa B/Rel signaling in T lymphocytes during autoimmune disease, we investigated type II collagen-induced arthritis (CIA) in transgenic mice expressing a constitutive inhibitor of NF-kappa B/Rel (I kappa B alpha(Delta N)) in the T lineage. Expression of the I kappa B alpha(Delta N) transgene was persistently high in adult peripheral lymphoid organs and undetectable in T cell-depleted splenocytes, suggesting the expression of the transgene is restricted to the T lineage. The incidence and severity of CIA were decreased significantly in these I kappa B alpha(Delta N) transgenic mice compared with nontransgenic littermates. Inhibition of CIA was not due solely to a decrease in their CD8+ population because transfer of wild-type CD8+ cells into transgenic mice failed to restore disease susceptibility. Protection against disease was associated with a moderate decrease in clonal expansion and a profound and persistent decrease in Ag-induced IFN-gamma production in vivo. Consistent with decreased level of anti-type II collagen-specific Abs and IFN-gamma, serum levels of IgG2a anti-CII Abs were significantly reduced. However, anti-CII-specific IgG1 levels were normal, indicating that some aspects of T cell help were unaffected. Taken together, these results suggest that inhibition of NF-kappa B in T cells impairs CIA development in vivo through decreases in type 1 T cell-dependent responses.

Short ragweed allergen induces eosinophilic lung disease in HLA-DQ transgenic mice.

The human leukocyte antigen (HLA) restriction of the IgE response to different allergens in humans has been a subject of numerous published studies. However, the role and contribution of specific HLA class II molecules in the pathogenesis of allergic airway inflammation are unknown and difficult to assess. HLA-DQ6 and HLA-DQ8 transgenic mice lacking endogenous mouse class II gene expression were actively immunized and later challenged intranasally with short ragweed (SRW) allergenic extract. The HLA-DQ transgenic mice developed pulmonary eosinophilia and lung tissue damage. We also found an increase in total protein (TP) level and IL-5 production in bronchoalveolar lavage (BAL) fluid and an increase in SRW-specific Th2-type immunoglobulins (IgG1, IgG2b) and total serum IgE levels. Under similar treatment, DQ-negative full-sib control mice were normal. The allergic response could be significantly inhibited or abrogated in HLA-DQ mice by systemic treatment with anti-DQ mAb. The in vivo responses of HLA-DQ6 and HLA-DQ8 mice showed differences in terms of levels of eosinophilia, BAL protein, IL-5 concentration, and lung hyperreactivity to inhaled methacholine. These findings demonstrate the crucial role for specific HLA-DQ molecules in SRW-specific CD4(+) T-cell activation and resulting recruitment of eosinophils into the airways.

Reduction of antigen-induced airway hyperreactivity and eosinophilia in ICAM-1-deficient mice.

A murine model of asthma is described in which we examined the role of intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of airway reactivity, pulmonary eosinophilia, and inflammation. We sensitized wild-type control [C57BL/6J, (+/+)] and ICAM-1 knockout [C57BL/6J-ICAM-1, (-/-)] mice to ovalbumin (OVA), and challenged them with OVA delivered by aerosol (OVA-OVA) to induce a phenotype consistent with an asthmatic response. Bronchial responsiveness to methacholine and counts of cell numbers and measurements of eosinophil content and cytokine levels in bronchoalveolar lavage fluid (BALF) were significantly attenuated in ICAM-1(-/-) mice as compared with (+/+) mice. We also showed that the absence of ICAM-1 had no significant affects on the production of serum IgE antibody, but did have an effect on ex vivo lymphocyte proliferation. Additionally, immunohistochemistry: (1) revealed increased staining for vascular cell adhesion molecule-1 (VCAM-1) after antigen challenge in the ICAM-1(-/-) mice but not in the ICAM-1(+/+) controls; and (2) confirmed the presence of alternatively spliced forms of ICAM-1 in the lungs of ICAM-1(-/-) mice. Thus, despite the availability of alternate adhesion pathways in ICAM-1(-/-) mice, the absence of ICAM-1 prevented eosinophils from entering the airways. In summary, we found that the ICAM-1 knockout mice exhibited a significantly inhibited response to aerosol antigen challenge for most of the parameters examined, and conclude that ICAM-1 is an important ligand mediating T-cell proliferation in response to antigen, eosinophil migration into the airways, and the development of airway hyperreactivity (AHR) in allergen-sensitized and -challenged mice.

HLA-DQB1 polymorphism determines incidence, onset, and severity of collagen-induced arthritis in transgenic mice. Implications in human rheumatoid arthritis.

Certain HLA-DR alleles have been associated with predisposition to human rheumatoid arthritis (RA). There is also evidence that certain HLA-DQ alleles may also be important in determining susceptibility to RA. We have previously demonstrated that mice transgenic for HLA-DQ8, a DQ allele associated with susceptibility to RA, develop severe arthritis after type II collagen immunization. To investigate the influence of polymorphic difference at the DQ loci on susceptibility to arthritis, we generated mice transgenic for HLA-DQ6, an allele associated with a nonsusceptible haplotype. The DQ6 mice were found to be resistant to collagen-induced arthritis. We also assessed the combined effect of an RA-susceptible and an RA nonassociated DQ allele by producing double-transgenic mice expressing DQ6 and DQ8 molecules, representing the more prevalent condition found in humans where heterozygosity at the DQ allele is common. The double-transgenic mice developed moderate CIA when immunized with CII when compared with the severe arthritis observed in DQ8 transgenic mice, much like RA patients bearing both susceptible and nonsusceptible HLA haplotypes. These studies support a role for HLA-DQ polymorphism in human RA.

Experimental autoimmune myasthenia gravis in B10.BV8S2 transgenic mice: preferential usage of TCRAV1 gene by lymphocytes responding to acetylcholine receptor.

Multiple TCRBV genes have been implicated in experimental autoimmune myasthenia gravis (EAMG) pathogenesis in susceptible H-2(b) strains of mice. We studied the contribution of specific TCRBV and AV genes in EAMG pathogenesis using B10.BV8S2 transgenic mice (H-2[b]). The TCR transgenic mice predominantly have TCRBV8S2 transgene, but can use any of the endogenous AV gene repertoire. The transgenic mice were immunized with acetylcholine receptor (AChR) in CFA and evaluated for EAMG pathogenesis. Although the lymphocyte responses to AChR in B10.BV8S2 transgenic and nontransgenic TCR wild-type mice were equivalent, a marked reduction in lymphocyte response to the dominant AChR alpha chain peptide 146-162 was observed in the TCR transgenic mice. After boosting with AChR in CFA, anti-AChR Abs were detected in the serum, and 14 of 42 (33%) of the TCR transgenic mice developed clinical EAMG. Furthermore, EAMG in TCR transgenic mice was prevented by treatment with mAb to TCRBV8, which depleted BV8-expressing T cells. Cloning and sequencing of TCRAV genes from AChR-reactive T cells from B10.BV8S2 transgenic mice revealed a pattern of restricted TCRAV gene usage. The majority (60%) of the clones sequenced showed a sequence identical with that of the TCRAV1S8 gene. In the normal spleen cells of TCR transgenic mice, AV gene usage was more random. Thus, despite the presence of a complete endogenous TCRAV repertoire in B10.BV8S2 transgenic mice, T cells responding to AChR preferentially used a single endogenous TCRAV gene, thus implicating the involvement of the TCRAV1S8 gene in EAMG pathogenesis.

V beta 8.2 transgene expression interferes with development of experimental autoimmune thyroiditis in CBA k/q but not k/k mice.

The thyroiditogenic T cell receptor (TCR) repertoire is not yet well defined in murine experimental autoimmune thyroiditis (EAT). Our recent work has shown that, while V beta 8+ T cells have no major role in EAT induction with mouse thyroglobulin (MTg), V beta 13 may be involved. To examine the effect of skewing the TCR repertoire on EAT development, CBA (H2k) mice were mated with B10.Q mice harboring an ovalbumin-specific V beta 8.2 TCR transgene (trg), and the trg+ mice were backcrossed to CBA. FACS analysis showed that peripheral blood T cells from trg+ mice had about 76 and 90% V beta 8.2+ cells in the CD4+ and CD8+ subsets, respectively, compared with about 15 and 11% in trg- sibs. The transgenic CBA k/k and k/q mice were immunized with MTg and sacrificed 28 days later. In all trg+ mice, anti-MTg titers and T cell proliferative responses to MTg were significantly lowered. However, thyroid infiltration was distinctly different in the two strains of transgenic mice; a significant decrease was seen primarily in k/q, but not k/k, trg+ mice. Thus, skewing the TCR repertoire to overexpress an irrelevant TCR revealed the possession of a less flexible thyroiditogenic TCR repertoire in k/q, but not k/k, mice.

HLA-DQ8 transgenic mice are highly susceptible to collagen-induced arthritis: a novel model for human polyarthritis.

Genetic studies have indicated that susceptibility to rheumatoid arthritis (RA) maps to the HLA-DR locus of the major histocompatibility complex. Strong linkage disequilibrium between certain HLA-DQ genes and HLA-DR genes associated with RA, however, suggests that HLA-DQ molecules may also play a role in RA susceptibility. To examine the role of HLA-DQ molecules in arthritis, we generated transgenic mice expressing the DQA1*0301 and DQB1*0302 genes from an RA predisposing haplotype (DQ8/DR4Dw4). The transgenes were introduced into mouse class II-deficient H-2Ab0 mice, and their susceptibility to experimental collagen-induced arthritis was evaluated. The HLA-DQ8+,H-2Ab0 mice displayed good expression of the DQ8 molecule, while no surface expression of endogenous murine class II molecules could be detected. The DQ8 molecule also induced the selection of CD4+ T cells expressing a normal repertoire of V beta T cell receptors. Immunization of HLA-DQ8+,H-2Ab0 mice with bovine type II collagen (CII) induced a strong antibody response that was cross-reactive to homologous mouse CII. Also, in vitro proliferative responses against bovine CII, which were blocked in the presence of an antibody specific for HLA-DQ and mouse CD4, were detected. Finally, a severe polyarthritis developed in a majority of HLA-DQ8+,H-2Ab0 mice, which was indistinguishable from the disease observed in arthritis susceptible B10.T(6R) (H-2Aq) controls. In contrast, HLA-DQ8-,H-2Ab0 fullsibs did not generate CII antibody and were completely resistant to arthritis. Therefore, these results strongly suggest that HLA-DQ8 molecules contribute to genetic susceptibility to arthritis and also establish a novel animal model for the study of human arthritis.

Expression of an ovalbumin-specific V beta 8.2 TCR transgene inhibits collagen arthritis in B10.Q mice.

Previous studies have illustrated the importance of T cells bearing alpha beta TCRs in the induction and development of collagen induced arthritis (CIA) in mice. However, the scope of TCR usage in CIA has yet to be clearly defined. Given the inherent diversity of the TCR repertoire, the relative flexibility of the arthritogenic TCR repertoire specific for type II collagen (CII) is not clear. Therefore, we chose to examine the influence of a highly skewed TCR repertoire on CIA. Arthritis susceptible B10.Q (H-2q) mice were mated with C57L (H-2b) animals expressing an ovalbumin-specific V beta 8.2 TCR transgene (Tg) and Tg+ offspring were further backcrossed to B10.Q. Homozygous H-2q/q, V beta 8.2 Tg+ mice displayed a high level of V beta 8.2+ T cells in peripheral blood. However, expression of some endogenous V beta TCR, such as V beta 14, was still detected. Upon immunization with bovine CII in adjuvant, V beta 8.2 Tg+ mice were highly resistant to CIA when compared with Tg- littermates. Analysis of sera demonstrated a marked reduction in antibody specific for homologous mouse CII as well as heterologous bovine CII in Tg+ animals. Interestingly, V beta 8.2 Tg+ mice still mounted good antibody responses following immunization with human thyroglobulin, indicating that the skewed TCR repertoire affected anti-CII but not antithyroglobulin responses. Thus, our findings show that constraints placed on the TCR repertoire inhibit pathogenic responses against CII and suggest that in H-2q mice the arthritogenic TCR repertoire bears only limited flexibility.

Polymorphism of the MHC class II Eb gene determines the protection against collagen-induced arthritis.

Collagen-induced arthritis (CIA) is an animal model of auto immune polyarthritis, sharing similarities with rheumatoid arthritis (RA). Paradoxally, susceptibility to mouse CIA is controlled by the H2A loci (DQ homologous) while RA is linked to HLA.DR genes (H2E homologous). We recently showed that the E beta d molecule prevents CIA development in susceptible H2q mice. We addressed the question of whether H2Eb polymorphism will influence CIA incidence as HLA.DRB1 polymorphism does in RA. In F1 mice, only H2Ebd and H2Ebs molecules showed protection. Using recombinant B10.RDD (Ebd/b) mice, we found that CIA protection was mediated by the first domain of the E beta d molecule. Using peptides covering the third hypervariable region of the E beta chain, we found a perfect correlation between presentation of E beta peptides by the H2Aq molecule and protection on CIA. Therefore, the mechanism by which H2Eb protects against CIA seems to rely on the affinity of E beta peptides for the H2Aq molecule.

Identification of a cyanogen bromide fragment of porcine type II collagen capable of modulating collagen arthritis in B10.RIII (H-2r) mice.

Previous studies directed towards identifying epitopes on type II collagen (CII) important in collagen induced arthritis (CIA) in mice have focused primarily on responses mounted in susceptible H-2q strains. However, the nature of T and B cell responses against CII in susceptible H-2r strains remains ill-defined. In an effort to identify regions on CII important in CIA in H-2r mice, we examined the cellular and humoral response of susceptible B10.RIII (H-2r) mice against cyanogen bromide (CB)-cleaved fragments of porcine CII. Following immunization with native porcine CII, LNC from B10.RIII mice mounted proliferative responses predominantly to peptide CB10, while negligible proliferation was detected against fragment CB9, 7, CB8, CB11 or CB12. In contrast, sera from arthritic B10.RIII mice displayed a heterogeneous pattern of reactivity against porcine CII, with strong antibody binding measured against the major fragments CB11, CB8 and CB10. To determine the in vivo significance of the dominant cellular response to CB10, B10.RIII mice received an i.v. injection of soluble CB10 seven days before immunization with native porcine CII. Mice pretreated with CB10 were highly resistant to CIA compared to control animals. Interestingly, B10.RIII mice pretreated with fragment CB11, a region of CII implicated in H-2q restricted CIA, remained susceptible to arthritis induction. Collectively, our findings indicate that the CB10 region of porcine C11 bears determinants which may be important in the induction and/or regulation of CIA in the H-2r haplotype.

Altered development of collagen induced arthritis in T cell receptor V beta congenic B10.RIII mice.

Analysis of the mouse T cell receptor (TCR) V beta genome has revealed the existence of two distinct genotypes which bear deletions of certain V beta genes. Mice bearing the V beta a genotype lack approximately 50% of the V beta genome while V beta c mice lack 70% of the known V beta genes. Studies of the experimental model collagen induced arthritis (CIA) have indirectly suggested that the presence of truncated V beta genotypes may influence susceptibility to this autoimmune disease. In order to confirm the influence of V beta a and V beta c genotypes on CIA, we derived mice congenic for the known V beta haplotypes in the CIA susceptible B10.RIII (H-2r) background. Flow cytometric analysis of splenic lymphocytes revealed normal T cell levels in both B10.RIII-V beta congenic lines. Expectedly, a generalized increase in the expression of some non-deleted V beta genes was detected. In addition, the mice were immunized with porcine type II collagen and monitored for CIA. B10.RIII-V beta a mice showed little difference in arthritis incidence or severity versus B10.RIII, but a significant delay in the onset of CIA was seen. In contrast, B10.RIII-V beta c mice showed a marked decrease in arthritis incidence versus B10.RIII and the severity of CIA in arthritic mice was also significantly lower (p < 0.01). Thus, in the B10.RIII strain, the presence of truncated TCR V beta genotypes alters the development of CIA. These findings may shed light on the influence of TCR genotypes in the induction and development of human rheumatoid arthritis.

Noninvolvement of V beta 8+ T cells in murine thyroglobulin-induced experimental autoimmune thyroiditis.

In experimental autoimmune thyroiditis (EAT) induced with mouse thyroglobulin (MTg), T cell receptor (TCR) V beta gene usage in the pathogenesis of disease is unknown. We report here studies evaluating V beta 8 gene usage in EAT, as V beta 8+ T cells are reportedly involved in some experimental autoimmune diseases. Spleen cells (SC) from MTg-immunized CBA/J (H-2k) mice were activated in vitro for adoptive transfer into syngeneic recipients. Elimination of V beta 8+ T cells by treating recipients with V beta 8 monoclonal antibody (mAb) following transfer of MTg-activated SC did not reduce disease severity. Conversely. MTg-primed SC were stimulated in vitro with V beta 8 mAb or staphylococcal enterotoxin B, which activates V beta 8+ T cells in CBA/J mice. Neither activated population transferred disease, in contrast to cells activated with MTg. Thus, in MTg-induced EAT, V beta 8+ T cells do not play a major role in pathogenesis.

Protective role of major histocompatibility complex class II Ebd transgene on collagen-induced arthritis.

Collagen-induced arthritis (CIA) is an animal model of autoimmune inflammatory polyarthritis that has features similar to rheumatoid arthritis (RA). Much like RA, susceptibility to mouse CIA is influenced by the major histocompatibility complex (MHC), H-2, and restricted to the H-2q and H-2r haplotypes. Whereas the role of the H-2A molecule in susceptibility to CIA is well established, little is known about the role of H-2E molecule in the disease. In this study, we analyzed the effect of a transgenic E beta d molecule on CIA susceptibility in a recombinant mouse B10.RQB3, which expresses the CIA susceptible Aq genes and an Eak gene, but does not produce an E molecule since Ebq is nonfunctional. In the presence of an Ebd transgene, a viable E molecule is generated. Whereas B10.RQB3 were susceptible to CIA, B10.RQB3-E beta d+ showed a dramatic reduction in the incidence of arthritis as well as a decrease in the level of anti-mouse and anti-bovine CII antibodies in their serum. No clear cut differences in the expression of T cell receptor (TCR) V beta was observed between E beta d+ and E beta d- transgenic mice. Mechanisms underlying the protective effect of E beta d transgenic molecule on CIA may shed light on how HLA-DR molecules influence human RA.

Collagen-induced arthritis and TCRs in SWR and B10.Q mice expressing an Ek alpha transgene.

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.