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Biomedical subjects

D H Kono

Publications and source records attributed to D H Kono.

At least 37 records · Page 2Linked to original sources
PubMed1998

The prototypic Th2 autoimmunity induced by mercury is dependent on IFN-gamma and not Th1/Th2 imbalance.

Imbalances of Th1- and Th2-type responses have been postulated to be a predisposing factor for both humoral and cellular mediated autoimmune diseases. To further define their roles in systemic autoimmunity, IL-4 and IFN-gamma gene knockout mice were studied for susceptibility to the prototypic Th2-mediated mercury-induced autoimmunity. A predominant Th2-type response following HgCl2 treatment of wild-type B10.S mice was confirmed by the findings of a significant increase in splenic IL-4 and hypergammaglobulinemia primarily of the IgG1 isotype, without an increase in IFN-gamma levels. Paradoxically, IL-4-deficient mice developed the characteristic anti-nucleolar autoantibodies and tissue deposition of immune complexes, while IFN-gamma-deficient mice had very low autoantibody levels and essentially normal immunohistology. Studies to define defects in Ab responses of IFN-gamma-deficient mice, using the T-dependent Ag (4-hydroxy-3-nitrophenyl)acetyl, revealed an attenuated IgG response to low and to a lesser extent high doses of (4-hydroxy-3-nitrophenyl)acetyl-hemocyanin, but maintenance of affinity maturation. These results indicate that Th1/Th2 imbalance does not directly play a role in susceptibility to mercury-induced autoimmunity, and suggest that the dependence on Th1-type responses in certain autoimmune diseases is due to the requirement for IFN-gamma for Ab production to weakly antigenic self molecules.

Animals↗
PubMed1998

Loci predisposing to autoimmunity in MRL-Fas lpr and C57BL/6-Faslpr mice.

Background genes determine the incidence and severity of lymphoaccumulation and histopathologic manifestations of systemic autoimmunity in mice homozygous for the apoptosis-defective Faslpr mutation. By interval mapping of 274 F2 mice intercrossed between MRL-Faslpr (severe disease) and C57BL/6-Faslpr (minimal disease), four loci were identified with significant linkage to lymphadenopathy and/ or splenomegaly on chromosomes 4, 5, 7, and 10, which were named lupus in (MRL-Faslpr x B6-Faslpr)F2 cross1-4 (Lmb1-4), respectively. Lmb1, -2, and -3 were also linked to the production of anti-dsDNA antibodies, but not glomerulonephritis, whereas Lmb4 was associated with glomerulonephritis. Lmb2, -3, and -4 were inherited from the MRL background, but interestingly, Lmb1 was derived from the C57BL16-Faslpr. Nevertheless, each locus, regardless of the strain of origin, appeared to act in an additive manner, although certain combinations were more effective. Only a single suggestive locus on chromosome 1 could be correlated with arthritis. The identification of loci with highly significant linkage to disease manifestations in Faslpr strains will make it possible to map and clone new genetic defects contributing to autoimmunity.

Animals↗
PubMed1997

Expression of protein-tyrosine phosphatases in the major insulin target tissues.

Protein-tyrosine phosphatases (PTPs) are key regulators of the insulin receptor signal transduction pathway. We have performed a detailed analysis of PTP expression in the major human insulin target tissues or cells (liver, adipose tissue, skeletal muscle and endothelial cells). To obtain a representative picture, all tissues were analyzed by PCR using three different primer sets corresponding to conserved regions of known PTPs. A total of 24 different PTPs were identified. A multiprobe RNase protection assay was developed to obtain a semiquantitative measure of the expression levels of selected PTPs. Surprisingly, PTP-LAR, previously suggested to be a major regulator of the insulin receptor tyrosine kinase, was expressed in extremely low levels in skeletal muscle, whereas the related receptor-type PTP-sigma and PTP-alpha were expressed in relatively high levels in all four tissues. The low levels of LAR PTP mRNA in skeletal muscle were further confirmed by Northern blot analysis.

Adipose Tissue↗
PubMed1997

Induction of the early growth response (Egr) family of transcription factors during thymic selection.

There is little known about the regulation of gene expression during TCR-mediated differentiation of immature CD4+8+ (double positive) thymocytes into mature T cells. Using the DPK CD4+8+ thymocyte precursor cell line, we demonstrate that the early growth response-1 gene (Erg-1), encoding a zinc finger transcription factor, is rapidly upregulated after TCR stimulation. We also report that Egr-1 is expressed by a subset of normal double positive thymocytes in the thymic cortex, as well by a majority of medullary single positive thymocytes. Expression of Egr-1 is dramatically reduced in the thymus of major histocompatibility complex knockout mice, but can be induced by anti-CD3 antibody stimulation of isolated thymocytes from these animals. These and other data suggest that high level expression of Egr-1 in the thymus is a consequence of selection. A similar pattern of expression is found for family members Egr-2 and Egr-3. Using the DPK cell line, we also demonstrate that expression of Egr-1, 2, and 3 is dependent upon ras activation, as is the initiation of differentiation to a single positive cell. In contrast, the calcineurin inhibitor cyclosporin A, which inhibits DPK cell differentiation as well as positive selection, inhibits expression of Egr-2 and Egr-3, but not Egr-1. The identification of the Egr family in this context represents the first report of a link between the two known signaling pathways involved in positive selection and downstream transcriptional regulators.

Animals↗
PubMed1997

G1 arrest and high expression of cyclin kinase and apoptosis inhibitors in accumulated activated/memory phenotype CD4+ cells of older lupus mice.

A general characteristic of lupus-prone mice (and humans) is the expedited accumulation of large numbers of presumably self-reactive activated/memory phenotype T cells. The mechanism by which these cells escape apoptosis has not been defined. We used activated/memory phenotype CD4+ cells from male BXSB mice with early-life severe lupus-like disease to investigate cell cycle status and apoptosis susceptibility, and to determine the role of corresponding genes in survival of these cells. In vitro acridine orange staining indicated that most of the rapidly accumulating memory phenotype CD4+ T cells of 4-month-old male BXSB mice are G1 arrested. Long-term bromodeoxyuridine in vivo labeling also showed that with advanced age, there was a shift of the CD4+ CD44(hi) male cells from predominantly cycling to predominantly noncycling. Moreover, the CD4+ CD44(hi) cells of older males were refractory to anti-CD3-induced proliferation and apoptosis. Using a multiprobe RNase protection assay encompassing riboprobe panels for cell cycle and apoptosis-related genes, we found that these cells exhibited high expression of certain members of the Ink4 (p18Ink4C) and Cip/Kip (p21Cip1) families of cyclin kinase inhibitors as well as of the apoptosis-inhibiting Bcl-xL gene. Western blot analysis confirmed increased levels of Bcl-xL and p21Cip1, and also identified increases in another cyclin kinase inhibitor, p27Kip1. We propose that in autoimmunity, self-reactive CD4+ cells are subjected to successive rounds of activation/division that eventually lead to a build-up in cyclin-dependent kinase inhibitors. Once high levels of such inhibitors are reached, they cause refractoriness to further activation, impaired cell cycle entry and resistance to apoptosis, a situation akin to replicative senescence.

Aging↗
PubMed1996

T cell receptor biases and clonal proliferations among lung transplant recipients with obliterative bronchiolitis.

Obliterative bronchiolitis (OB) is the most serious late complication of lung transplantation, but the pathogenesis of this disorder has not been elucidated. We sought evidence that OB is mediated by a cellular immunologic response by characterizing T cell antigen receptor beta-chain variable gene (TCRBV) repertoires in lung allograft recipients. Expression levels of 27 TCRBV among recipients were determined by multiprobe RNase protection assay after PCR amplification. In comparison to recipients with no evidence of rejection (n = 9), the PBL TCRBV repertoires of OB subjects (n = 16) exhibited more frequent expansions (16 vs. 9% of all measured TCRBV, P < 0.02), and the magnitudes of these abnormalities were greater (8.2 +/- 0.8 vs. 4.5 +/- 0.3 SD from mean normal values, P < 0.01). TCRBV sequencing showed these expansions were composed of clonal or oligoclonal populations. Thus, T cell responses in the recipients are marked by highly selective clonal expansions, presumably driven by indirect recognition of a limited number of immunodominant alloantigens. These processes are exaggerated among allograft recipients with OB, implying that cognate immune mechanisms are important in the pathogenesis of the disorder. Furthermore, the prominence of finite, distinct TCR phenotypes raise possibilities for development of novel diagnostic modalities and targeted immunotherapies for OB and other manifestations of chronic allograft rejection.

Adult↗
PubMed1995

Incomplete T cell receptor V beta allelic exclusion and dual V beta-expressing cells.

Recent studies have documented incomplete TCR V alpha-chain allelic exclusion and dual V alpha-bearing T cells. Herein, we show that V beta allelic exclusion is also incomplete, since a significant proportion of peripheral T cells express dual V beta in both TCR transgenic and normal mice. Studies in TCR transgenic mice indicated that although a small proportion of T cells escaped allelic exclusion in the thymus, dual V beta-expressing cells expanded dramatically in the periphery with age, and such expanded cells had an activated phenotype. Although not as pronounced, age-related increases in dual V beta-bearing cells were also observed in normal mice. These findings may have important implications for TCR selection and specificity, age-related repertoire changes, and autoimmune disease pathogenesis.

Alleles↗
PubMed1995

Human T helper cells specific for HIV reverse transcriptase: possible role in intrastructural help for HIV envelope-specific antibodies.

Cooperation between B cells specific for an antigen exposed on a viral structure and T helper (Th) cells specific for an internal antigen, as demonstrated with influenza, hepatitis B and rabies viruses, has been termed intrastructural help. Th cells specific for internal proteins of HIV, which are much less mutated than its exposed antigens, may be valuable in vaccine design against this virus. We investigated the human Th repertoire specific for the core HIV antigen reverse transcriptase (p66), and determined whether these cells could be candidate intrastructural T helpers. CD4+ T lines and clones were generated from non-immune individuals by stimulation with p66-pulsed antigen-presenting cells (APC). Specific lines were obtained with p66 from 19 out of 21 (90%) of these individuals, vs. 7 out of 29 (24%) with gp120. Diverse epitopes were recognized by different individuals, and various V beta genes were used by these clones. Clones using the same V beta genes were of diverse origin, according to VDJ region sequence. Of these lines 45% responded to p66 in the context of HIV virions. Moreover, p66-specific clones could respond to APC that had internalized HIV complexed with envelope-specific monoclonal antibodies, suggesting that p66-specific Th cells may participate in intrastructural help. These studies indicate that p66-specific Th cells are detectable in vitro in most naive individuals and exhibit clonal heterogeneity, and that the majority recognize an HIV conserved antigen. They respond to p66 following processing of whole virions and are clearly candidates for intrastructural help. If confirmed in vivo, p66 should be included among vaccine candidates investigated to optimize the anti-HIV Th response.

Amino Acid Sequence↗
PubMed1995

Quantitative polymerase chain reaction analysis reveals marked overexpression of interleukin-1 beta, interleukin-1 and interferon-gamma mRNA in the lymph nodes of lupus-prone mice.

The nature of the stimuli driving autoantibody production in systemic lupus erythematosus (SLE) is unclear, but cytokines are believed to play an important role. Since cytokines primarily appear to act locally at the tissue level, we analysed mRNA expression of several cytokines (IL-1 alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IL-10, IFN gamma, TNF alpha, TNF beta and TGF beta 1) in the lymph nodes of lupus-prone mice, in models of early onset disease. We constructed a multispecific competitor fragment that allowed quantification of these cytokine transcripts by competitive PCR assay. The results reveal considerable overexpression of IL-1 beta, IL-10 and IFN gamma transcripts in SLE-prone MRL-lpr/lpr (MRL/l) and BXSB male (BXSBm) mice, but with some strain differences. IFN gamma was most markedly augmented in MRL/l mice (in some cases over 100-fold greater than control mice), IL-1 beta was most severely overexpressed in BXSBm mice while IL-10 was equally increased in both strains. In addition, TGF beta 1 expression was moderately elevated in the lymph nodes of BXSBm (but not MRL/l) mice. We found no abnormality in the expression of the other cytokines. Cytokine transcript levels were only slightly altered at 4 weeks of age, but were elevated from 10 to 22 weeks of age. The latter phase corresponds to a period where lupus-like disease escalates, resulting in frequent mortality. Interestingly, our results do not reveal a clear Th1 or Th2 cytokine expression pattern in these lupus-prone mice. IL-1 beta, IFN gamma and IL-10 are pleiotropic cytokines with pro-inflammatory and B-cell stimulatory effects. These results point to certain cytokines as potential targets for immunotherapy in lupus.

Age Factors↗
PubMed1994

Lupus susceptibility loci in New Zealand mice.

Susceptibility to systemic lupus erythematosus has been unequivocally established to be an inherited trait, but the exact genes and how they confer susceptibility remain largely unknown. In this study of (NZB x NZW)F2 intercross mice, we used linkage analysis of markers covering > 90% of the autosomal genome and identified eight susceptibility loci (Lbw1 to -8, chromosomes 17, 4-7, 18, 1, 11, respectively) associated with antichromatin autoantibody production, glomerulonephritis, and/or mortality. Only one locus, the major histocompatibility complex, was linked to all three traits. Two other loci were associated with both glomerulonephritis and mortality, whereas the remaining loci were linked to one of the above traits. Two additional loci (Sbw1 and -2) that contributed to splenomegaly were also identified. The Sbw2 locus mapped to the identical region as Lbw2, a locus on chromosome 4 linked to glomerulonephritis and mortality, suggesting a single locus with pleiotropic effects. The results indicate that the immunopathologic features of lupus are affected by distinct, but additive, genetic contributions. Studies to determine the nature of the genes associated with these loci should help define the genetic mechanisms involved in this systemic autoimmune disease.

Animals↗
PubMed1994

Crystal structure of a peptide complex of anti-influenza peptide antibody Fab 26/9. Comparison of two different antibodies bound to the same peptide antigen.

The three-dimensional structure of the complex of a second anti-peptide antibody (Fab 26/9) that recognizes the same six-residue epitope of an immunogenic peptide from influenza virus hemagglutinin (HA1; 75-110) as Fab 17/9 with the peptide has been determined at 2.8 A resolution. The amino acid sequence of the variable region of the 26/9 antibody differs in 24 positions from that of 17/9, the first antibody in this series for which several ligand-bound and free structures have been determined and refined. Comparison of the 26/9-peptide with the 17/9-peptide complex structures shows that the two Fabs are very similar (r.m.s.d. 0.5 to 0.8 A) and that the peptide antigen (101-107) has virtually the same conformation (r.m.s.d. 0.3 to 0.8 A) when bound to both antibodies. A sequence difference in the 26/9 binding pocket (L94; His in 26/9, Asn in 17/9) results in an interaction with a bound water molecule that is not seen in the 17/9 structures. Epitope mapping shows that the relative specificity of 26/9 and 17/9 antibodies for individual positions of the peptide antigen are slightly different. Amino acid substitutions in the peptide, particularly at position SerP107, are tolerated to different extents by 17/9 and 26/9. Structural and sequence analysis suggests that amino acid differences near the peptide-binding site are responsible for altering slightly the specificity of 26/9 for three peptide residues and illustrates how amino acid substitutions can modify antibody-antigen interactions and thereby modulate antibody specificity.

Amino Acid Sequence↗
PubMed1994

V beta repertoire of murine hepatic T cells. Implication for selection of double negative alpha beta + T cells.

To further define the origin, selection, and diversity of hepatic T cells, we have determined V beta gene expression profiles in double negative (DN, CD4-8-) and single positive (SP, CD4+8- or CD8+4-) alpha beta + liver T cells of DBA/2 mice. These I-E+ mice express mouse mammary tumor (Mtv) provirus-encoded endogenous superantigens of the Mlsa,c type, and thus display deletions/depletions of several V beta-bearing SP cells. Total liver alpha beta + T cells of these mice exhibited an overall V beta expression profile similar to splenic T cells, with the notable exception of high V beta 7 and V beta 8.1 expression. As previously reported, DN alpha beta + T cells were enriched highly in the liver. This subset exhibited a V beta expression profile similar to thymic DN alpha beta + cells with deletions/depletions in several V beta s, but high V beta 7 expression in both populations. Surprisingly, hepatic CD4+ cells also displayed high V beta 7 expression compared with splenic T cells, suggesting that hepatic DN alpha beta + and CD4+ T cells are selected via a common pathway. The V beta 7-expressing DN alpha beta + and CD4+ liver T cell populations were polyclonal, as evidenced by cloning and sequencing. High V beta 7 expression in these cells was undiminished with age. On the basis of V beta repertoire and surface phenotype, DN alpha beta + and/or certain CD4+ T cells seem to constitute a distinct population primarily found in the liver, thymus, and bone marrow. These cells may originate from SP T cells that have down-regulated their accessory molecules under certain activation conditions and, because of the accompanying expression of particular adhesion molecules, they accumulate in tissues such as the liver and thymus.

Amino Acid Sequence↗
PubMed1994

T cell receptor V beta 15 dominates the antiacetylcholine receptor response in Lewis rat T cell lines.

Ten Lewis rat T cell lines responsive to Torpedo californica acetylcholine receptor (AChR) were assayed for TCR V beta usage. All lines were CD4+, OX-22-, and exhibited reactivity to one or more AChR chains. Several different V beta s were expressed by these lines, but V beta 15 was dominant in 5 of 10 lines. Unique CDR3 sequences were observed among the 10 lines, although three of the V beta 15 rearrangements used J beta 1.4. These data suggest that V beta 15+ T cells are selected in the in vitro response to the antigenically complex AChR in the Lewis rat.

Amino Acid Sequence↗