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Biomedical subjects

C S David

Publications and source records attributed to C S David.

At least 91 records · Page 5Linked to original sources
PubMed1996

HLA-B27 heavy chains contribute to spontaneous inflammatory disease in B27/human beta2-microglobulin (beta2m) double transgenic mice with disrupted mouse beta2m.

MHC class I allele, HLA-B27, is strongly associated with a group of human diseases called spondyloarthropathies. Some of these diseases have an onset after an enteric or genitourinary infection. In the present study, we describe spontaneous disease in HLA-B27 transgenic mice where endogenous beta2-microglobulin (beta2m) gene was replaced with transgenic human beta2m gene. These mice showed cell surface expression of HLA-B27 similar to that of human peripheral blood mononuclear cells. In addition, free heavy chains (HCs) of HLA-B27 were also expressed on thymic epithelium and on a subpopulation of B27-expressing PBLs. These mice developed spontaneous arthritis and nail changes in the rear paws. Arthritis occurred primarily in male animals and only when mice were transferred from the pathogen-free barrier facility to the conventional area. Transgenic mice expressing HLA-B27 with mouse beta2m have undetectable levels of free HCs on the cell surface and do not develop arthritis. In vivo treatment with anti-HC-specific antibody delayed the onset of disease. Our data demonstrate specific involvement of HLA-B27 'free' HCs in the disease process.

Animals↗
PubMed1996

Human leukocyte antigen-DRB1*1502 (DR2Dw12) transgene reduces incidence and severity of arthritis in mice.

A strong correlation exists between susceptibility to RA in humans and some DRB1 alleles of the MHC region, such as DRB1*0401 and DRB1*0101. Meanwhile, incidences of other DR specificities, such as DR2, DR5, or DR7 have often been found reduced among RA patients. Like RA, susceptibility to mouse CIA is influenced by the MHC class II loci. To analyze the effect of a DRB1 molecule associated with low incidence of RA on mouse CIA, a human DRB1*1502 (DR2Dw12) transgene was introduced into CIA-susceptible B10.RQB3 (H2Aq) mice. Transgene-positive DRB1*1502 mice showed a significant reduction in the incidence and severity of arthritis. Moreover, the clinical reduction of arthritis correlated with the T-cell proliferative response of B10.RQB3-DRB1*1502 mice against a self-derived DRB1 peptide from the third hypervariable region. Our results suggest that the DRB1*1502-mediated protection against CIA can be explained by the DRB1 molecule acting as a source of self-antigenic peptide which interferes with the T-cell response against immunodominant regions(s) of the arthritogenic type II collagen molecule. By analogy, a similar mechanism might play a critical role in influencing the class II-associated predisposition to RA.

Animals↗
PubMed1996

HLA-DRB1 polymorphism determines susceptibility to autoimmune thyroiditis in transgenic mice: definitive association with HLA-DRB1*0301 (DR3) gene.

Familial clustering of autoimmune thyroid diseases has led to studies of their association with human major histocompatibility complex (MHC) class II genes. One such gene implicated in Hashimoto's thyroiditis (HT) is HLA-DR3, but the association is weak and is contradicted by other reports. On the other hand, murine experimental autoimmune thyroiditis (EAT), a model for HT, presents a clear linkage with MHC class II. Moreover, it is inducible with thyroglobulin (Tg), the common autoantigen in either species. Immunization of HLA-DRB1* 0301 (DR3) transgenic mice with mouse or human Tg resulted in severe thyroiditis. In contrast, transgenic mice expressing the HLA-DRB1*1502 (DR2) gene were resistant to EAT. Our studies show that HLA-DRB1 polymorphism determines susceptibility to autoimmune thyroiditis and implicate Tg as an important autoantigen.

Animals↗
PubMed1996

HLA-DQ8 transgenic mice lacking endogenous class II molecules respond to house dust allergens: identification of antigenic epitopes.

We have introduced HLA-DQ8 (HLADQB*0302 and HLA-DQA*0301) genes into A beta 0 knockout mice. Transgenic animals were immunized with a whole body extract of Dermatophagoides pteronyssinus (Der p), one of the causative agents of house dust mite allergy. Transgenic mice expressing HLA-DQ8 genes elicited HLA-DQ8-restricted responses driven by CD4+ T cells. Synthetic-overlapping peptides representing a major allergen of house dust mite (Der p 2) were synthesized and used as immunogens. HLA-DQ8+ mice responded to three peptides: 8 (residues 61-80), 11 (residues 91-110), and 13 (residues 111-129). The mice produced IL-2, IL-4, and IL-6 response to Der p challenge, suggesting a mixed Th1/Th2 response. These mice represent a new model for studies of the immune basis of allergy.

Allergens↗
PubMed1996

Characterization of the antigenic structure of human type II collagen.

A series of 101 peptides each 20 amino acids in length (10-residue overlap) spanning the helical portion of the mature alpha-chain of human type II collagen (CII) was synthesized. DBA/1 (H-2q) mice were immunized with individual peptides, and draining lymph node cells were challenged in vitro. Strong responses were measured to three peptides: peptide I (residues 74-93), peptide 14 (residues 254-273), and peptide 81 (residues 924-943). B10.Q (H-2q) mice were responsive to peptides I and 81 but not to peptide 14. B10.RIII (H-2r) mice, which are resistant to arthritis induction following immunization with human CII, were unresponsive to peptides I, 14, and 81. Using single amino acid truncated peptides, we determined minimal immunostimulatory lengths for peptides I and 81. Residues critical to antigenicity were identified by introducing alanine and glycine substitutions into minimal length immunostimulatory peptides. The determinants within peptides I and 81 are 100% homologous to mouse CII and are autoantigens. Peptide 81 has homology to viral proteins. Peptide 14 is 90% homologous to mouse CII and has homology to heat shock proteins.

Adjuvants, Immunologic↗
PubMed1996

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.

Animals↗
PubMed1996

Immune response of HLA-DQ8 transgenic mice to peptides from the third hypervariable region of HLA-DRB1 correlates with predisposition to rheumatoid arthritis.

The major histocompatibility complex class II genes play an important role in the genetic predisposition to many autoimmune diseases. In the case of rheumatoid arthritis (RA), the human leukocyte antigen (HLA)-DRB1 locus has been implicated in the disease predisposition. The "shared epitope" hypothesis predicts that similar motifs within the third hypervariable (HV3) regions of some HLA-DRB1 alleles are responsible for the class II-associated predisposition to RA. Using a line of transgenic mice expressing the DQB1*0302/DQA1*0301 (DQ8) genes in the absence of endogenous mouse class II molecules, we have analyzed the antigenicity of peptides covering the HV3 regions of RA-associated and nonassociated DRB1 molecules. Our results show that a correlation exists between proliferative response to peptides derived from the HV3 regions of DRB1 chains and nonassociation of the corresponding alleles with RA predisposition. While HV3 peptides derived from nonassociated DRB1 molecules are highly immunogenic in DQ8 transgenic mice, all the HV3 peptides derived from RA-associated DRB1 alleles fail to induce a DQ8-restricted T-cell response. These data suggest that the role of the "shared epitope" in RA predisposition may be through the shaping of the T-cell repertoire.

Amino Acid Sequence↗
PubMed1996

Transcription factor B cell lineage-specific activator protein regulates the gene for human X-box binding protein 1.

The transcription factor human X-box binding protein 1 (hXBP-1) is a basic region-leucine zipper protein implicated in the regulation of major histocompatibility complex class II gene expression as well as in exocrine gland and skeletal development. Multiple regulatory elements in the hXBP-1 promoter lie 3' to the transcription start site, including the hX2 site, whose core sequence is an AP-1-like element identical to the hXBP-1 target sequence in the HLA-DRA promoter. One complex identified by electrophoretic mobility shift assay (EMSA), complex 3, was previously shown to protect the hX2 site and more 3' bases. Sequence analysis now shows that this region contains a consensus binding site for transcription factor BSAP (B cell lineage-specific activator protein). Complex 3 and BSAP have identical cell-type specificities, as they are found only in pre-B and mature B cell lines. In EMSAs, BSAP antibody specifically recognized complex 3, and in vitro translated BSAP could bind to an hXBP promoter fragment. Cotransfections using an hXBP-1 reporter construct indicated that BSAP downregulates the hXBP-1 promoter. The highest levels of hXBP-1 mRNA were found when BSAP was not expressed, in pre-Pro-B cells and in plasma cell lines. In addition, hXBP-1 and BSAP levels were inversely correlated along the early stages of B cell development. In the regulation of the hXBP-1 promoter, a strong positive transcriptional influence at the hX2 site is opposed by the downregulatory actions of BSAP.

Antibody Specificity↗
PubMed1996

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.

Animals↗
PubMed1996

Regulation of the E beta gene in vivo: lessons from E beta d transgenic mice.

We have examined the expression and regulation of the MHC class II E beta d gene in both cell lines and in transgenic mice. In transient transfection assays, as little as 192 bp of the E beta d proximal promoter was sufficient to direct constitutive expression of a reporter gene in a B cell line and to confer inducibility by IFN-gamma in a macrophage cell line. To determine if the same E beta d promoter sequences were also sufficient to direct correct expression in vivo, E beta d transgenes bearing either 4.1 or 0.2 kb of upstream sequence were introduced into an inbred mouse strain with a non-expressed endogenous E beta gene. Expression of both transgenes mirrored the expression of the endogenous I-A protein in thymus, B cells and macrophages with regard to both constitutive and cytokine-inducible expression. These results indicate that for the E beta gene only 200 bp of proximal promoter sequence are required to achieve tissue-specific and cytokine-inducible expression. This is in striking contrast to the E alpha gene, the only other murine class II gene whose promoter has been analyzed in vivo, which has been shown to require 2.0 kb of upstream sequence for appropriate expression. These data demonstrate, therefore, that the location of critical regulatory elements for the E beta and E alpha genes may differ.

Animals↗
PubMed1996

Genetic control of immunity to Heligmosomoides polygyrus: presentation of promiscuous antigens to parasite-specific T cell hybridomas.

The role of MHC class II in the presentation of Heligmosomoides polygyrus antigens has been investigated, using a number of T cell hybridomas produced in A and E positive and negative mice. By using fixed and irradiated antigen presenting cells (APC), further evidence has emerged, to support earlier data, that there can be differential processing requirements during the presentation of H. polygyrus antigens by A and E molecules. In concordance with these earlier observations, this work provides further evidence than individual T cells can respond to antigen when presented by more than one MHC molecule. Previously, this evidence has been restricted to individual MHC molecules of the same haplotype, but these data show that H. polygyrus produces antigens which can be presented by both syngeneic and allogeneic MHC molecules. These antigens do not appear to be synonymous with the previously described H. polygyrus superantigen, as presentation is restricted to specific MHC haplotypes. It is proposed that H. polygyrus may produce these antigenic molecules as part of its strategy to manipulate the host immune system.

Animals↗
PubMed1996

H2-A polymorphism contributes to H2-Ebeta-mediated protection in collagen-induced arthritis.

Collagen-induced arthritis (CIA) is an animal model of auto-immune inflammatory polyarthritis which has features similar to rheumatoid arthritis (RA). Much like RA, susceptibility to mouse CIA is influenced by the major histocompatibility complex (MHC) and is restricted to the H2 haplotypes q and r. In previous experiments, we have found that the introduction of an H2-Ebd transgene in H2-Aq CIA-susceptible mice was able to protect these mice against disease development. More recently, we have proposed that the polymorphism of the first domain of the Ebeta molecule modulates this protection, and that the presentation of a peptide from the third hypervariable region of the Ebeta chain by the H2-Aq molecule plays an important role in this mechanism. In the present report, we investigated whether the H2-E-mediated protection is H2-Aq-specific and whether the source of collagen has any influence. While the source of collagen had no effect on the protection, our results showed that the H2-E molecule failed to protect B10.RIII (H2(r)) mice against CIA. Further, the H2 haplotype r exerted a negative effect on the Ebetad-mediated protection in H2-Aq-restricted disease. Our results provide additional proof that self-MHC-derived peptides, such as Ebeta peptides, may play an important role in the T-cell repertoire education and/or modulation of the T-cell response in the periphery.

Amino Acid Sequence↗
PubMed1995

Primary hormonogenic sites as conserved autoepitopes on thyroglobulin in murine autoimmune thyroiditis. Secondary role of iodination.

We hypothesized earlier that conserved T cell epitopes and those unique to mouse thyroglobulin (MTg) contributed to its total thyroiditogenicity in murine autoimmune thyroiditis. Recent studies of synthetic peptides from human Tg (HTg) revealed no immunodominant epitopes. The role of iodine residues, considered by some to render Tg immunogenic, became unclear, since only one 12-mer peptide contained thyroxine (T4) positioned at hormonogenic site 2553. It primed T cells for thyroiditis transfer, but noniodinated peptide containing thyronine (T0) was not compared. To determine 1) whether other primary hormonogenic sites were likewise immunogenic and 2) whether iodination was requisite for this and other sites to be an autoepitope, we derivatized three pairs of 12-mer peptides, 1-12, 2549-2560, 2559-2570, containing T0 or T4 at positions 5, 2553, or 2567, respectively. The six peptides were used to stimulate MTg-primed cells in vitro and to immunize mice. None directly induced thyroiditis; peptide Abs were the lowest in mice given hT0(2567) or hT4(2567). Of the three T4-containing peptides, hT4(5) and hT4(2553), but not hT4(2567), stimulated MTg-primed or HTg-primed T cells in vitro, with hT4(2553) being the stronger. Comparing hT0(2553) with hT4(2553), both activated MTg-primed, or peptide-primed, T cells to transfer thyroiditis. The marked immunogenicity of noniodinated hT0(2553) and the poor antigenicity of hT4(5) and hT4(2567) demonstrate that immunogenicity of a conserved hormonogenic site is dependent more on its amino acid sequence than on T4 substitution. Iodination may enhance antigenicity and/or binding affinity, but it is not required for a Tg hormonogenic site to be an autoepitope.

Amino Acid Sequence↗
PubMed1995

Spontaneous inflammatory arthritis in HLA-B27 transgenic mice lacking beta 2-microglobulin: a model of human spondyloarthropathies.

Human class I major histocompatibility complex allele HLA-B27 is associated with a group of human diseases called "spondyloarthropathies." Studies on transgenic rats expressing HLA-B27 and human beta 2-microglobulin have confirmed the role of HLA-B27 in disease pathogenesis. Here we report spontaneous inflammatory arthritis in HLA-B27 transgenic mice lacking beta 2-microglobulin (B27+ beta 2m-/-). In the absence of beta 2-microglobulin, B27+ beta 2m-/- animals do not express the HLA-B27 transgene on the cell surface and have a very low level of CD8+ T cells. Most of the B27+ beta 2m-/- male mice showed nail changes, hair loss, and swelling in paws, which leads to ankylosis. The symptoms occur only after the B27+ beta 2m-/- mice are transferred from the specific pathogen-free mouse colony. These results suggest that aberrant assembly, transport, and expression of the HLA-B27 molecule may predispose an individual for development of the disease when exposed to an appropriate environmental trigger.

Animals↗
PubMed1995

Oral administration of an immunodominant human collagen peptide modulates collagen-induced arthritis.

Human type II collagen (HuCII) may be one of the autoantigens involved in human rheumatoid arthritis (RA). By using over-lapping peptides, we have previously described an immunodominant region (HuCII.250-270) on HuCII. In the present study, this 21-mer HuCII.250-270 peptide was used as tolerogen, and its effect on both early and effector phase of collagen-induced arthritis (CIA) was examined. Upon immunization with HuCII-derived peptide 250-270, HuCII.250-270-tolerized mice showed diminished T cell proliferation that was mediated by Th1 cytokine, IL-2. More interestingly, oral tolerance with HuCII.250-270 peptide diminishes primarily a Th1 type of immune response. Arthritis severity was reduced markedly in mice orally tolerized with HuCII.250-270 peptide both at early and effector phases. Suppression of CIA at the effector phase by oral administration of HuCII peptide suggests a potential immunotherapeutic use of collagen II peptide in the treatment of human RA.

Administration, Oral↗