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Chella S David

Publications and source records attributed to Chella S David.

At least 19 recordsLinked to original sources
PubMed2007

New humanized HLA-DR4-transgenic mice that mimic the sex bias of rheumatoid arthritis.

OBJECTIVE: To generate a mouse model that can mimic human rheumatoid arthritis (RA). A major difference between RA in humans and collagen-induced arthritis (CIA) in mice is the lack of sex bias and autoantibodies in the animal model. We used DRB1*0401-transgenic mice to understand the role of DR4 in susceptibility and sex bias in RA. METHODS: A transgenic mouse was generated that lacked all endogenous mouse class II genes (AE(o)) and expressed the RA susceptibility allele HLA-DRB1*0401. These transgenic mice were tested for incidence, severity, and sex distribution of CIA. RESULTS: DRB1*0401.AE(o) mice developed CIA predominantly in females and produced rheumatoid factors, similar to the features of human RA. Another feature similar to human RA is the expression of class II molecules on antigen-presenting cells as well as T cells. Activated and sorted CD4(+) T cells can present DR4-restricted type II collagen (CII)-derived peptide in vitro, but cannot process the antigen. This suggests a role for these cells in epitope presentation locally in joints, which affects disease severity. After challenge with CII, female mice had higher cellularity and increased T cell proliferation and produced higher levels of proinflammatory cytokines than did the male mice. CONCLUSION: DR4.AE(o) mice expressed HLA similar to humans and displayed increased arthritis susceptibility in females, thus mimicking RA in humans. This model may be valuable for studying sex differences observed in humans and for understanding why autoimmunity is increased in women. These mice may also be useful for developing future therapeutic strategies.

Animals↗
PubMed2006

Acute systemic immune activation following vaginal exposure to staphylococcal enterotoxin B--implications for menstrual shock.

Menstrual toxic shock syndrome (mTSS) is an acute systemic inflammatory disease associated with the superantigenic exotoxin, toxic shock syndrome toxin (TSST)-1, produced by Staphylococcus aureus and the use of high absorbency tampons. Even though S. aureus is capable of elaborating several other superantigenic exotoxins, only TSST-1 has been implicated in the pathogenesis of mTSS possibly because most other superantigenic exotoxins are known enterotoxins. Nonetheless, we have shown recently that one of the enterotoxigenic staphylococcal superantigens, staphylococcal enterotoxin B (SEB), can cause robust systemic immune activation following exposure through non-enteric mucosa, including nasal or conjunctival routes. In a similar manner, we show here that vaginal administration of SEB in HLA class II transgenic mice can cause robust systemic immune activation characterized by profound elevation of proinflammatory cytokines in the serum, activation and expansion of SEB-reactive CD4(+) and CD8(+) T cells in peripheral lymphoid organs and SEB-induced deletion of immature thymocytes. Vaginal administration of SEB also caused leukocytic infiltration in major organs, such as liver and lung, reminiscent of human toxic shock syndrome. Systemic immune activation following vaginal superantigen delivery was independent of the stage of the estrus cycle in the mouse. Using HLA class II transgenic mice, we have shown that exposure to SEB through the vaginal canal can cause robust systemic immune activation. SEB could thus play a role in the pathogenesis of mTSS.

Animals↗
PubMed2006

IL-10-deficiency unmasks unique immune system defects and reveals differential regulation of organ-specific autoimmunity in non-obese diabetic mice.

Interleukin (IL)-10 is a potent anti-inflammatory cytokine and ablation of IL-10 exacerbates Th1-type autoimmune diseases. Even though type 1 diabetes (T1D) in NOD mice is believed to be Th1-mediated, the incidence and severity of T1D is unaltered in IL-10-deficient NOD mice raised under pathogen-free conditions. We describe for the first time, the outcome of IL-10 deficiency on islet and other organ-specific autoimmunity in NOD mice raised in a conventional facility. IL-10-deficient NOD mice under such conditions were protected from spontaneous as well as cyclophosphamide-induced diabetes, but were susceptible to diabetes induced by adoptive transfer of splenocytes from spontaneously diabetic NOD mice. Whereas the incidence of rectal prolapse was very high in this NOD.IL-10(-/-) mouse colony, IL-10-deficient C57Bl/6 mice raised under similar conditions seldom developed rectal prolapse. While injection of complete Freund's adjuvant (CFA) significantly reduced insulitis, it did not ameliorate colitis in IL-10-deficient NOD mice indicating differential regulation of organ-specific autoimmunity by CFA. Phenotypic characterization of IL-10(-/-) mice revealed a significant increase in splenic macrophage numbers in NOD but not on the B6 background. This was accompanied by a heightened systemic inflammatory cytokine response and mortality following in vivo challenge with a toll-like receptor 9 agonist, CpG-containing DNA.

Animals↗
PubMed2006

HLA-DR3 transgenic mice immunized with adenovirus encoding the thyrotropin receptor: T cell epitopes and functional analysis of the CD40 Graves' polymorphism.

The major histocompatibility (MHC) molecule HLA-DR3 is a susceptibility gene for Graves' disease (GD) in Caucasians. Mice lacking murine MHC and expressing human HLA-DR3 develop thyrotropin receptor (TSHR) antibodies and sometimes hyperthyroidism after vaccination with TSHR-DNA. MHC molecules present peptides processed from antigens to T cells. Therefore, we used DR3-transgenic mice to investigate recognition of TSHR ectodomain peptides. After immunization with TSHR A-subunit adenovirus (A-subunit-Ad) but not control-adenovirus (Control-Ad), splenocytes from DR3 mice responded to A-subunit protein in culture by producing interferon-gamma (IFN-gamma). When challenged with 29 overlapping TSHR peptides, splenocytes from A-subunit-Ad- or Control-Ad-immunized mice responded to several peptides. However, in splenocytes from A-subunit-Ad but not Control-Ad mice, a peptide containing TSHR residues 142-161 induced significantly more IFN-gamma than the same splenocytes in medium alone. Immunized DR3 mice also permitted testing the TSHR-specific function of the CD40 single nucleotide polymorphism (C vs. T) associated with GD. Of three human DR3 human Epstein-Barr virus lines (EBVL), two had C in both alleles (CC) and one was CT. However, these EBVL presented peptides poorly and there was no difference between CC vs. CT EBVL in peptide presentation to splenocytes from immunized mice. A peptide corresponding to residues 145-163 is one of seven suggested to be important in GD based on HLA-binding affinities, T-epitope algorithms, and human studies. Consequently, as in human GD, TSHR amino acids 142-161 appear to include a major T cell epitope in HLA-DR3 transgenic mice immunized with A-subunit-Ad.

Adenoviridae↗
PubMed2006

Intranasal exposure to staphylococcal enterotoxin B elicits an acute systemic inflammatory response.

Staphylococcus aureus produces a variety of superantigen exotoxins, including staphylococcal enterotoxin B (SEB). Little is known regarding the pathogenesis of SEB entering through the intranasal route. Intranasal exposure to SEB might occur because of nasal packing following surgical procedure, biologic warfare, or even S. aureus colonization. We evaluated the local and systemic effects of intranasally delivered SEB using a series of human leukocyte antigen (HLA) class II transgenic mice as conventional mice expressing endogenous class II molecules mount a poor immune response to SEB. Gene expression profiling using microarrays showed robust up-regulation of genes involved in several proinflammatory pathways as early as 3 h post-intranasal challenge with SEB in HLA class II transgenic mice. This was accompanied by a several hundred-fold increase in serum levels of pro-inflammatory cytokines such as IL-12, IL-6, TNF-alpha, IFN-gamma, as well as MCP-1 in HLA class II transgenic mice but not in C57BL/6 mice; CD4 or CD8 T-cells independently contributed to the systemic cytokine response. Defective IL-12 or IL-4 receptor signaling significantly decreased or increased serum IFN-gamma, respectively. Intranasal exposure to SEB resulted in neutrophil influx into bronchoalveolar lavage fluid and caused expansion of both CD4 and CD8 T-cells expressing TCR V beta 8 in the spleen. This was accompanied by mononuclear cell infiltration in the liver reminiscent of the systemic inflammatory response syndrome. Thus, we have shown, for the first time, that intranasal administration of SEB can cause systemic immune activation.

Administration, Intranasal↗
PubMed2006

Intranasal exposure to bacterial superantigens induces airway inflammation in HLA class II transgenic mice.

Staphylococcus aureus is widely prevalent in the nasopharynges of healthy individuals (carriers) but can also cause serious infections. S. aureus can elaborate a variety of superantigen exotoxins in "carrier" or "pathogenic" states. Streptococcus pyogenes can also colonize the nasopharynx and elaborate superantigens. Unlike the acute effects of superantigen exotoxins absorbed through the gut or vaginal mucosa, little is known regarding the pathogenesis of superantigens entering through the intranasal route. In the current study, we evaluated the local and systemic effects of staphylococcal enterotoxin B (SEB) and streptococcal pyrogenic exotoxin A (SPEA) delivered through the intranasal route. Superantigens were administered intranasally on multiple occasions, and experimental animals were sacrificed on day 8 for experimental analyses. SEB-induced airway inflammation was more pronounced for HLA-DR3 transgenic mice than for BALB/c mice, consistent with bacterial superantigens binding more efficiently to human than murine major histocompatibility complex class II. The nature of the airway inflammation in HLA-DR3 mice was determined by the concentration of SEB applied intranasally. Low concentrations (20 ng) induced eosinophilic airway inflammation as well as eosinophil degranulation, whereas intranasal exposure to higher concentrations (2,000 ng) resulted in neutrophilic airway inflammation, permanent airway destruction, toxic shock, and mortality. SEB-induced eosinophilic inflammatory response was enhanced in signal transducer and activator of transcription (STAT)-4-deficient HLA-DQ8 transgenic mice with defective interleukin-12 signaling. Intranasal administration of SPEA induced airway inflammation and systemic immune activation in HLA-DQ8 transgenic mice. In conclusion, repeated chronic intranasal exposure to bacterial superantigens causes airway inflammation and systemic immune activation.

Administration, Intranasal↗
PubMed2006

Mice expressing HLA-DQ6alpha8beta transgenes develop polychondritis spontaneously.

Relapsing polychondritis (RP) is a human autoimmune disease of unknown etiology in which cartilaginous sites are destroyed by cyclic inflammatory episodes beginning, most commonly, during the fourth or fifth decade of life. We have previously described collagen-induced polychondritis that closely mirrors RP occurring in young (6-8 weeks old) HLA-DQ6alphabeta 8alphabeta transgenic Abeta0 mice, following immunization with heterologous type II collagen (CII). We present evidence here that transgenic strains expressing the DQ6alpha8beta transgene develop spontaneous polychondritis (SP) at the mouse equivalent of human middle age (4.5-6 months and 40-50 years old, respectively) and display polyarthritis, auricular chondritis and nasal chondritis--three of the most common sites affected in RP. Auricular chondritis in SP, like RP but unlike CII-induced polychondritis, exhibited a relapsing/remitting phenotype, requiring several inflammatory cycles before the cartilage is destroyed. Elevated serum levels of total IgG corresponded with the onset of disease in SP, as in RP and CII-induced polychondritis. No CII-specific immune response was detected in SP, however--more closely mirroring RP, in which as few as 30% of RP patients have been reported to have CII-specific IgG. CII-induced polychondritis displays a strong CII-specific immune response. SP also demonstrated a strong female preponderance, as some workers have reported in RP but has not observed in CII-induced polychondritis. These characteristics of SP allow for the examination of the immunopathogenesis of polychondritis in the absence of an overwhelming CII-specific immune response and the strong adjuvant-induced immunostimulatory influence in CII-induced polychondritis. This spontaneous model of polychondritis provides a new and unique tool to investigate both the initiatory events as well as the immunopathogenic mechanisms occurring at cartilaginous sites during the cyclic inflammatory assaults of polychondritis.

Animals↗
PubMed2005

Identification of immunodominant epitopes of alpha-gliadin in HLA-DQ8 transgenic mice following oral immunization.

Celiac disease, triggered by wheat gliadin and related prolamins from barley and rye, is characterized by a strong association with HLA-DQ2 and HLA-DQ8 genes. Gliadin is a mixture of many proteins that makes difficult the identification of major immunodominant epitopes. To address this issue, we expressed in Escherichia coli a recombinant alpha-gliadin (r-alpha-gliadin) showing the most conserved sequence among the fraction of alpha-gliadins. HLA-DQ8 mice, on a gluten-free diet, were intragastrically immunized with a chymotryptic digest of r-alpha-gliadin along with cholera toxin as adjuvant. Spleen and mesenteric lymph node T cell responses were analyzed for in vitro proliferative assay using a panel of synthetic peptides encompassing the entire sequence of r-alpha-gliadin. Two immunodominant epitopes corresponding to peptide p13 (aa 120-139) and p23 (aa 220-239) were identified. The response was restricted to DQ and mediated by CD4+ T cells. In vitro tissue transglutaminase deamidation of both peptides did not increase the response; furthermore, tissue transglutaminase catalyzed extensive deamidation in vitro along the entire r-alpha-gliadin molecule, but failed to elicit new immunogenic determinants. Surprisingly, the analysis of the cytokine profile showed that both deamidated and native peptides induced preferentially IFN-gamma secretion, despite the use of cholera toxin, a mucosal adjuvant that normally induces a Th2 response to bystander Ags. Taken together, these data suggest that, in this model of gluten hypersensitivity, deamidation is not a prerequisite for the initiation of gluten responses.

Amino Acid Sequence↗
PubMed2005

STAT4- and STAT6-signaling molecules in a murine model of multiple sclerosis.

Epidemiological studies suggest that an environmental factor (possibly a virus) acquired early in life may trigger multiple sclerosis (MS). The virus may remain dormant in the central nervous system but then becomes activated in adulthood. All existing models of MS are characterized by inflammation or demyelination that follows days after virus infection or antigen inoculation. While investigating the role of CD4+ T cell responses following Theiler's virus infection in mice deficient in STAT4 or STAT6, we discovered a model in which virus infection was followed by demyelination after a very prolonged incubation period. STAT4-/- mice were resistant to demyelination for 180 days after infection, but developed severe demyelination after this time point. Inflammatory cells and up-regulation of Class I and Class II MHC antigens characterized these lesions. Virus antigen was partially controlled during the early chronic phase of the infection even though viral RNA levels remained high throughout infection. Demyelination correlated with the appearance of virus antigen expression. Bone marrow reconstitution experiments indicated that the mechanism of the late onset demyelination was the result of the STAT4-/- immune system. Thus, virus infection of STAT4-/- mice results in a model that may allow for dissection of the immune events predisposing to late-onset demyelination in MS.

Animals↗
PubMed2005

Toxic oil syndrome: genetic restriction and immunomodulatory effects due to adulterated oils in a model of HLA transgenic mice.

Toxic oil syndrome (TOS) was described in Spain in 1981, due to the ingestion of contaminated rapeseed oil denatured with 2% aniline. More than 20,000 persons were affected, causing over 2500 deaths. Immunological findings were: eosinophilia, mRNA for Th2 cytokines (IL-4 and IL-5) in lungs, elevated total IgE and sIL-2R and increase of DR2 HLA class II phenotypic frequency in patients died by TOS. Our objective is to test the genetic restriction found in humans using HLA transgenic mice. Results show that mice expressing human DR2 and DQ6 (both in linkage disequilibrium), had higher percentage of eosinophils (DQ6) and IgE (DR2) than other transgenic mice tested (DR3 and DR4). Also, a Th2 shift was found in DR2 transgenic mice when toxic oil was administered with OVA. This has been corroborated by the IL-5 mRNA expression in 4 out of 6 lung tissues from TOS oil treated BALB/c mice. These data indicate that an immunological response was induced as consequence of the toxic administration. These results correlate with those found in TOS patients and reinforce the implication of genetic restrictions in the acquisition of toxic-mediated disease.

Aniline Compounds↗
PubMed2005

HLA DR and DQ interaction in myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis in HLA class II transgenic mice.

Multiple sclerosis (MS) is shown to be associated with the HLA class II genes. The presence of strong linkage disequilibrium between HLA DR and DQ molecules in humans makes it difficult to identify the individual roles of HLA DR and HLA DQ molecule in MS pathogenesis. To address this problem, we used HLA class II transgenic mice and the experimental autoimmune encephalitis (EAE) model. Administration of recombinant MOG (rMOG) induced severe inflammation and demyelination in the central nervous system (CNS) of HLA DRB1*1502 mice (60%), whereas no disease was observed in HLA DQB1*0601(0%) and mild disease was observed in DQB1*0302 mice (13%). Lymphocyte proliferation was blocked by anti HLA antibodies, confirming that the rMOG was functionally presented by the HLA molecules. Introduction of DQB1*0302 into DRB1*1502 mice resulted in the development of chronic progressive clinical disease characterized by severe inflammation and demyelination (90%) in response to immunization with rMOG, whereas mild disease was observed when DQB1*0601 was introduced in DRB1*1502 mice (30%). This would suggest that the presence of more than one susceptible allele, namely HLA DRB1*1502 and DQB1*0302 resulted in enhanced severity of disease in the DRB1*1502/DQB1*0302 mice, possibly due to the additional selection and expansion of potential autoreactive T cells. The use of defined single and double HLA transgenic mice may reveal the intricate interactions between class II molecules in human disease.

Animals↗
PubMed2005

HLA-DQ8 is a predisposing molecule for detergent enzyme subtilisin BPN'-induced hypersensitivity.

Several million individuals are exposed to agents in the workplace associated with atopy and asthma. Detergent enzymes have been implicated in occupationally induced hypersensitivity. However, the genetic susceptibility and T cell responses to detergent enzymes are undefined. We generated and used HLA-DQ6, -DQ8, -DR2, -DR3, and -DR4 transgenic mice to examine the immune and inflammatory components involved in the response to the detergent enzyme subtilisin BPN'. Based on in vitro and in vivo studies, for the first time, we present evidence that DQ8 is a strong susceptibility marker for BPN'-induced hypersensitivity. Only DQ8 mice showed consistent T cell responses to five immunodominant regions of BPN' comprising peptides #14 to 16, 36-37, 42-43, 62-63, and 80-81. The DQ8 mice also developed allergic eosinophilic inflammatory reactions in the airways following intranasal instillations of this enzyme. The DQ8 mice also responded to BPN' with a significant IgG1 and IgE production. We propose that the HLA Class II tg mice are useful for understanding allergenic responses to enzymes in humans, screening of allergenic and immunogenic properties of detergent enzymes, and for the development of modified enzymes to maintain efficient detergent qualities without allergic properties.

Animals↗
PubMed2005

Relationship between thyroid peroxidase T cell epitope restriction and antibody recognition of the autoantibody immunodominant region in human leukocyte antigen DR3 transgenic mice.

We investigated the relationship between thyroid peroxidase (TPO) antibody and T lymphocyte epitopes in TPO-adenovirus (TPO-Ad) immunized BALB/c mice and mice transgenic for the human class II molecule DR3 associated with human thyroid autoimmunity. TPO autoantibodies are largely restricted to an immunodominant region (IDR). BALB/c mice immunized with fewer (10(7) vs. 10(9)) TPO-Ad particles developed TPO antibodies with lower titers that displayed greater restriction to the IDR. However, as with higher-dose TPO-Ad immunization, T cell epitopes (assessed by splenocyte interferon-gamma response to TPO in vitro) were highly diverse and variable in different animals. In contrast, DR3 mice immunized the higher TPO-Ad dose (10(9) particles) had high TPO antibody levels that showed relative focus on the IDR. Moreover, T cell epitopes recognized by splenocytes from DR3 mice showed greater restriction than BALB/c mice. Antibody affinities for TPO were higher in DR3 than in BALB/c mice. The present study indicates that weak TPO-Ad immunization of BALB/c mice (with consequent low TPO antibody titers) is required for enhanced IDR focus yet is not associated with T cell epitopic restriction. Humanized DR3 transgenic mice, despite stronger TPO-Ad immunization, develop higher titer TPO antibodies that do focus on the autoantibody IDR with T cells that recognize a more limited range of TPO peptides. These data suggest a relationship between major histocompatibility complex class II molecules and the development of antibodies to the IDR, a feature of human thyroid autoimmunity.

Adenoviridae↗
PubMed2005

H2A- and H2E-derived CD4+CD25+ regulatory T cells: a potential role in reciprocal inhibition by class II genes in autoimmune thyroiditis.

We recently described a novel H2E class II-transgenic model (A(-)E(+)) of experimental autoimmune thyroiditis (EAT) that permits disease induction with heterologous thyroglobulin (Tg), but unlike conventional susceptible strains, precludes self-reactivity to autologous mouse Tg. In transgenic E(+)B10 (A(+)E(+)) mice, the presence of endogenous H2A genes is protective against H2E-mediated thyroiditis, inhibiting EAT development. The suppressive effect of H2A genes on H2E-mediated thyroiditis mirrors previous reports of H2E suppression on H2A-mediated autoimmune diseases, including EAT. The mechanism of the reciprocal-suppressive effect between class II genes is unclear, although the involvement of regulatory T cells has been proposed. We have recently reported that CD4(+)CD25(+) regulatory T cells mediate peripheral tolerance induced with mouse Tg in CBA mice. To determine whether these cells play a role in our E(+)-transgenic model, we first confirmed the existence of CD4(+)CD25(+) T cells regulating thyroiditis in E(+)B10.Ab(0) (A(-)E(+)) and B10 (A(+)E(-)) mice by i.v. administration of CD25 mAb before EAT induction. The depletion of CD4(+)CD25(+) T cells enhanced thyroiditis induction in the context of either H2E or H2A. Moreover, reconstitution of CD4(+)CD25(+) T cells from naive B10 mice restored resistance to EAT. E(+)B10 (A(+)E(+)) mice were also depleted of CD4(+)CD25(+) T cells before the challenge to determine their role in thyroiditis in the presence of both H2A and H2E genes. Depletion of CD4(+)CD25(+) regulatory T cells offset the suppression of H2E-mediated thyroiditis by H2A. Thus, these regulatory T cells may be involved in the reciprocal-suppressive effect between class II genes.

Adoptive Transfer↗
PubMed2005

Requirement for CD28 may not be absolute for collagen-induced arthritis: study with HLA-DQ8 transgenic mice.

CD28 is required to achieve optimal T cell activation to an Ag. To determine the role CD28 costimulation plays in collagen-induced arthritis, we have generated DQ8 transgenic, CD28-deficient mice. DQ8 mice deficient for CD28 had comparable numbers of CD4 and CD8 T cells as DQ8.CD28(+/+) mice. DQ8.CD28(-/-) mice develop collagen-induced arthritis with delayed onset and less severity than DQ8.CD28(+/+) mice. T cells from DQ8.CD28(-/-) mice did not respond to type II collagen efficiently in vitro, although the response to DQ8-restricted peptides was similar to that in the parent mice. There was no functional defect in T cells as observed by proliferation with Con A. Cytokine analysis from in vitro study showed the production of high levels of the inflammatory cytokine, IFN-gamma, in response to type II collagen. We observed an increase in CD4(+)CD28(-)NKG2D(+) cells after immunization, suggesting an important role for cells bearing this receptor in the disease process. CD28(-/-) mice also have an increased number of DX5(+) cells compared with CD28(+/+) mice, which can lead to the production of high levels of IFN-gamma. DQ8.CD28(-/-) mice had an increased number of cells bearing other costimulatory markers. Cells from DQ8.CD28(-/-) mice exhibited a lower proliferation rate and were resistant to activation-induced cell death compared with DQ8.CD28(+/+) mice. This study supports the idea that CD28 plays a crucial role in the regulation of arthritis. However, in the absence of CD28 signaling, other costimulatory molecules can lead to the development of disease, thus indicating that the requirement for CD28 may not be absolute in the development of arthritis.

Animals↗
PubMed2005

Delineation of the minimal encephalitogenic epitope of proteolipid protein peptide(91-110) and critical residues required for induction of EAE in HLA-DR3 transgenic mice.

Previously, we have reported that proteolipid protein (PLP) peptide 91-110 can induce experimental autoimmune encephalomyelitis (EAE) in HLA-DR3 transgenic (tg) mice. Here we, report that residues spanning 97-108 are the minimal epitope required for induction of EAE in DR3 mice. Utilizing a series of alanine-substituted peptides, positions 99, 101, 102, 103, 104, and 106 are identified as residues necessary for an immune response. Further analysis indicated that amino acid isoleucine (99), aspartate (102) and lysine (104) are anchor residues facilitating binding to HLA-DR3 molecules. These results may have applications in the future design of peptide based immunotherapy.

Alanine↗