Biomedical subjects

Hidemi Takahashi

Publications and source records attributed to Hidemi Takahashi.

At least 19 recordsLinked to original sources

PubMed2005

Temperature-dependent biosynthesis of glucose monomycolate and its recognition by CD1-restricted T cells.

Mycolic acids are long chain fatty acids that constitute the lipid-rich cell wall framework of mycobacteria. Upon infection, mycobacteria begin to synthesize glucose monomycolate (GMM), a glucosylated species of mycolic acids, by utilizing host-derived glucose as sugar source. Accordingly, GMM production serves as a good indicator for local invasion of mycobacteria, and its detection by the host immune system would favor efficient monitoring of mycobacterial infection. Here, we found that GMM was produced abundantly at 30 degrees C rather than at 37 degrees C and recognized by a GMM-specific, CD1-restricted T cell line that was isolated from mycobacteria-infected human skin. Since the common portal sites for mycobacterial infection include ventilating alveoli of the lung and the externally exposed skin that often render invading microbes survive at reduced temperature, sampling GMM by CD1 lipid antigen-presenting molecules may allow the host to detect mycobacterial infection at its early phases.

Antigens, CD1↗

PubMed2005

Langerhans cells stimulated by mechanical stress are susceptible to measles virus infection.

OBJECTIVE: Measles virus (MV) first infects the human respiratory tract, but the initial target cells are unknown. We examined whether MV infects Langerhans cell-like dendritic cells (LCs) generated from CD14(+) monocytes in the presence of GM-CSF, IL-4, and TGF-beta1. METHODS: Cultured LCs were established as described recently [Biochem Biophys Res Commun 2003;306:674-679]. The expression of immunological markers was detected by FACScan. Infection with MV was assessed by syncytia formation, viral-specific fluorescence, and Western blotting. RESULTS: MV did not infect and replicate the freshly established, unstimulated LCs expressing CD1a, E-cadherin and Langerin but not CD83. Also, CD150, a receptor for MV was not expressed on the surface of the LCs. However, LCs stimulated by mechanical stress such as washing and centrifugation became susceptible to MV infection. CONCLUSION: A subset of mechanically stimulated LCs but not unstimulated immature ones became susceptible to MV. The actual role of Langerhans cells in local immunity seems to be to suppress unfavorable reactions initiated by virus intrusion.

Antigens, CD↗

PubMed2005

Augmentation of Helicobacter pylori urease activity by its specific IgG antibody: implications for bacterial colonization enhancement.

Gastric colonization of Helicobacter pylori (H. pylori) occurs in a very early age via infected mothers having H. pylori-specific IgG antibodies that would be transplacentally transferred to infants. In addition, H. pylori urease-specific IgG was associated with chronic gastric atrophy and post-immunization gastritis is usually correlated with a strong local IgG response. These findings indicate that H. pylori-specific IgG antibodies, in particular its urease-specific IgG, may induce unfavorable influence on host resistance against H. pylori. Here, we show that we have found a unique H. pylori urease-specific IgG monoclonal antibody (MAb), termed S3, recognizing the conformational structure of the small subunit Ure-A, which enhanced the urease enzymatic activity. Such enhancement of the H. pylori urease activity induced by 1 microg of S3 was almost completely cancelled by simultaneously added the same amount of L2 MAb, which has a strong and specific inhibitory activity against H. pylori urease and recognizes a liner epitope of 8-mer peptide (F8: SIKEDVQF) within its large subunit Ure-B (Infect. Immun. 69: 6597, 2001). Intravenous pre-administration of purified S3 into BALB/c mice showed significant augmentation for gastric colonization with the susceptible strain Sydney Strain-1 (SS-1). To our knowledge, this is the first demonstration that a H. pylori urease-specific IgG MAb induced an augmentation of their gastric colonization in vivo.

Amino Acid Sequence↗

PubMed2004

Transmission of macrophage-tropic HIV-1 by breast-milk macrophages via DC-SIGN.

Recent findings suggest that macrophage-tropic human immunodeficiency virus type 1 (HIV-1) produced in colostrum/early breast milk may hold a clue to determine the mechanisms of transmission of HIV-1 via breast-feeding. Here, we show that the majority of CD4(+) cells in the colostrum are CD14(+) macrophages expressing both chemokine receptors and DC-SIGN, a dendritic cell-specific receptor for HIV-1. The R5-type macrophage-tropic HIV-1 isolate NL(AD8) infected such breast-milk macrophages and caused them to secrete virus particles efficiently; however, the secreted virions showed only a weak transmissibility to their susceptible target, MAGIC-5 cells. When stimulated with interleukin-4, the breast-milk macrophages demonstrated a striking enhancement of expression of DC-SIGN and showed a strong capacity to transmit NL(AD8) virions to MAGIC-5 cells, which was specifically blocked by anti-DC-SIGN-specific antibody. These results suggest that HIV-1 virions captured by DC-SIGN, but not secreted cell-free virions, may be more efficiently transmitted to other compartments, such as the gastrointestinal tract, through acidic gastric juice.

Adult↗

PubMed2004

Endogenously expressed HIV-1 nef down-regulates antigen-presenting molecules, not only class I MHC but also CD1a, in immature dendritic cells.

The effects of Nef molecules on immature dendritic cells (iDCs) were analyzed using recombinant human immunodeficiency virus type 1 (HIV-1) with intact nef gene, pseudotyped with vesicular stomatitis virus glycoprotein, HIV/VSV-G/+Nef. When iDCs were infected with HIV/VSV-G/+Nef, the surface expression of CD1a, a molecule for presenting glycolipid/lipid antigens, was selectively down-regulated among CD1 molecules (CD1a, -b, -c, and -d) as well as class I MHC. Moreover, the CD1a molecules were also down-modulated and co-localized with DsRed2-tagged-Nef in CD1a-transfected cells. Their co-localization was dependent upon CD1a cytoplasmic tail and the CD1a was redistributed from cell surface to LAMP-1+ late endosomal/lysosomal compartment. These findings reveal that the HIV-1-Nef interferes with the intracellular trafficking of CD1a, and suggest the involvement of CD1a-restricted immune effectors in the protective immunity against HIV-1 infection, which implicates the feasibility of virus-derived glycolipid/lipid antigens together with epitope peptides for the vaccine development.

Antigens, CD↗

PubMed2004

Resistance to viral infection by intraepithelial lymphocytes in HIV-1 P18-I10-specific T-cell receptor transgenic mice.

For the analysis of mucosal immunity to HIV-1, we have recently established a line of transgenic (Tg) mice expressing the TCRalpha and TCRbeta genes of the murine CTL clone RT1 specific for P18-I10 (RGPGRAFVTI), an immunodominant gp160 envelope-derived epitope of IIIB isolate, restricted by the H-2D(d) MHC-I molecule. Here we examine those cells bearing specific TCR among the intraepithelial lymphocytes (IELs), with flow cytometric analysis using H-2D(d)/P18-I10 tetramers. We observed three distinct CD3(+), tetramer positive populations among the IELs: extra-thymic CD8alphabeta(+), alphabetaTCR T-cells; CD8 alphaalpha+, gammadeltaTCR T-cells; and thymus-derived CD8alphabeta+, alphabetaTCR T-cells. Challenge of these Tg mice with P18-I10 encoded by a vaccinia virus vector, either intrarectally (i.r.) or intraperitoneally (i.p.), revealed that the intraepithelial compartment seems to be a major site for prevention of the spread of viral infection. Such immunity appears due to the thymus-derived, CD8alphabeta+ antigen-specific CTLs together with CD8alphaalpha+ gammadelta cells, which regulate virus spread. This model system for studying CTL based immunity at mucosal sites should prove helpful in developing rational approaches for HIV control.

Animals↗

PubMed2004

Major histocompatibility complex class-I presentation impaired in transgenic mice expressing hepatitis C virus structural proteins during dendritic cell maturation.

Hepatitis C virus (HCV) infection is often persistent, but its mechanism and pathogenesis remain unclear. One mechanism through which HCV escapes systemic immunosurveillance might be via impaired dendritic cells (DCs), which are the most potent type of antigen-presenting cells. We examined whether HCV causes immunosuppression in DCs during maturation. We isolated immature DCs from the bone marrow of two founder lineages of transgenic mice harboring HCV cDNA expressing HCV structural proteins (nucleotides 294-3435), and studied how DC function is modified by HCV expression. Our data showed that the capacity of DCs expressing HCV structural proteins to stimulate T-cells was significantly impaired. Moreover, the surface expression of major histocompatibility complex (MHC) class-I molecules was significantly impaired on infected DC, especially with respect to H-2D. The transportation of H-2D to the cell surface during DC maturation was inhibited by HCV expression. However, the total amount of H-2D molecules produced by DC expressing HCV was not impaired. These results indicated that the immune response of DC infected with HCV is diminished and might be associated with the mechanism of persistent HCV infection.

Adenoviridae↗

PubMed2004

Age-dependent decrease of polymeric Ig receptor expression and IgA elevation in ddY mice: a possible cause of IgA nephropathy.

Individual animals in the closed colony population of ddY mice were analyzed to clarify the major cause of age-dependent elevation of serum IgA and the appearance of human IgA nephropathy (IgAN)-like symptoms. Based on the serum IgA levels, the mice were classified into two subgroups. One was a high serum IgA group with some manifestations of IgAN through aging (ddY(High)), and the other was a normal serum IgA group without IgAN (ddY(Norm)). The ratio of urinary IgA to serum IgA was significantly reduced in ddY(High) mice, suggesting an impaired IgA clearance via secretion through the epithelial barrier. The actual clearance rate of the intravenously injected dimeric IgA in ddY(High) mice was found to be slower than that in ddY(Norm) mice. Furthermore, we found that the polymeric Ig receptors (pIgRs) that mediate transcytosis of IgA were poorly expressed in the glomeruli as well as in the intestine of ddY(High) mice, whereas the pIgRs were more abundantly expressed in ddY(Norm) mice. In addition, the comparative study using polymerase chain reaction showed that decreased pIgR expression occurred at the transcriptional level in the ddY(High) population. Taken together, these results suggest that a systemic defect in pIgR expression may result in impaired IgA secretion and accumulation of IgA in the serum of ddY(High) mice. The age-dependent changes of pIgR expression in the dimeric IgA secretion sites of ddY(High) mice suggest a possible cause for the elevation of serum IgA level and the pathogenesis of IgAN-like disease.

Aging↗

PubMed2004

Polyriboinosinic polyribocytidylic acid [poly(I:C)]/TLR3 signaling allows class I processing of exogenous protein and induction of HIV-specific CD8+ cytotoxic T lymphocytes.

In the case of viral infection, various viral proteins and genetic components are disseminated in the body. The former viral proteins may be captured by immature dendritic cells (DC) and the latter genetic components may stimulate the antigen-loading DC to maturate via specific Toll-like receptors (TLR), leading to the establishment of virus-specific cellular immunity; in particular, cytotoxic T lymphocytes (CTL) that control intracellular virions. Polyriboinosinic polyribocytidylic acid [poly(I:C)], which might reflect a natural genetic product from a variety of viruses during replication, has recently been identified as one of the critical stimuli for TLR3. Based on these observations, we speculated that stimulation of TLR3 with poly(I:C) might drive the direction of acquired/adaptive immunity to the cellular arm. Indeed, when BALB/c mice were immunized with purified recombinant HIV-1 envelope gp120 or influenza hemagglutinin (HA) protein together with poly(I:C), epitope-specific CD8(+) class I MHC molecule-restricted CTL were primed from naive CD8(+) T cells in vivo. In contrast, when the same proteins were immunized with lipopolysaccharide, a stimulant of TLR4, specific CTL were not primed at all. Moreover, we show here that immature DC could present processed antigen from captured purified protein in association with class I MHC molecules in the presence of poly(I:C), but not of LPS. These results indicate that we are able to manipulate the direction of acquired/adaptive effector immune responses using an appropriate stimuli and the findings presented in this paper will offer a new therapeutic strategy using poly(I:C) administration for priming antigen-specific CD8(+) CTL with purified viral protein in vivo.

Animals↗

PubMed2004

Studies of recombinant streptococcal pyrogenic exotoxin B/cysteine protease (rSPE B/SCP) in the skin of guinea pigs & the release of histamine from cultured mast cells & basophilic leukocytes.

BACKGROUND & OBJECTIVES: Streptococcal pyrogenic exotoxin B/streptococcal cysteine protease (SPE B/SCP) is considered to be one of the virulence factors of Streptococcus pyogenes (S. pyogenes) which causes serious diseases such as severe invasive infections and streptococcal toxic shock syndrome (STSS). There are no reports on the histamine releasing activity of SPE B/SCP from mast cells, although several biological activities have been studied. It is not clear whether SPE B/SCP have the superantigenic activity. We studied whether SPE B/SCP plays as a pathogenic factor in streptococcal infections and STSS through a histamine releasing activity. METHODS: Human mast cells and basophils were generated from CD34 positive cells isolated from cord blood and cultured in the presence of rIL-6, stem cell factor and/or rIL-3. The capacity of increasing capillary permeability of recombinant SPE B/SCP (rSPE B/SCP) was studied by using the skin of guinea pigs. Mitogenic activity to human T-cells of rSPE B/SCP was studied by incorporation of (3)Hthymidine. The levels of histamine in the plasma of patients with STSS and controls were measured by ELISA kit. RESULTS: rSPE B/SCP induced increased capillary permeability in the skin of guinea pigs, but both SPE A and SPE C did not exhibit such activity. Histamine was released from cultured human mast cells stimulated with rSPE B/SCP. The rSPE B/SCP did not exhibit mitogenic activity to human T-cells. Three of the 7 patients with STSS showed higher levels of plasma histamine than those of normal subjects. INTERPRETATION & CONCLUSION: The results suggested that increased capillary permeability and histamine release from mast cells induced by rSPE B/SCP might be involved in STSS and/or streptococcal infection of skin and mucous membrane.

Animals↗

PubMed2003

In vivo priming of natural killer T cells by dendritic cells pulsed with hepatoma-derived acid-eluted substances.

Many murine tumor cells express not only individual haplotype-matched class I MHC molecules, but also species-specific CD1d molecules. The former class I MHC molecules generally present internally synthesized tumor-derived peptide antigens to highly specific CD8(+) cytotoxic T lymphocytes (CTLs) in acquired immunity. In contrast, the latter CD1d molecules may present tumor-associated glycolipid antigens to broadly crossreactive natural killer T (NKT) cells, which might correlate with controlling tumor metastasis. Here, we showed that murine hepatoma cell line Hepa1-6-derived acid-eluted substances might contain both D(b) class I MHC-restricted antigens and CD1d-restricted substances, which could sensitize not only syngeneic bone marrow-derived DCs (BM-DCs), but also allogeneic BM-DCs expressing haplotype-mismatched class I MHC and species-specific CD1d molecules. To our surprise, intravenous (i.v.) immunization of C57BL/6 mice with the former syngeneic BM-DCs carrying acid-eluted materials primed both CD4(-)CD8(-) and CD8(+) NKT cells in the spleen, whereas immunization with the latter allogeneic BM-DCs loaded the tumor-derived substances primed CD4(-)CD8(-), but not CD8(+) NKT cells. The findings shown in the present study will open a new area for cancer immunotherapy using allogeneic DCs and tumor-derived acid-eluted substances.

Acids↗

PubMed2003

Down-regulation of Toll-like receptor expression in monocyte-derived Langerhans cell-like cells: implications of low-responsiveness to bacterial components in the epidermal Langerhans cells.

In the skin, there are unique dendritic cells called Langerhans cells, however, it remains unclear why this particular type of dendritic cell resides in the epidermis. Langerhans cell-like dendritic cells (LCs) can be generated from CD14(+) monocytes in the presence of GM-CSF, IL-4, and TGF-beta1. We compared LCs with monocyte-derived dendritic cells (DCs) generated from CD14(+) monocytes in the presence of GM-CSF and IL-4 and examined the effect of exposure to two distinct bacterial stimuli via Toll-like receptors (TLRs), such as peptidoglycan (PGN) and lipopolysaccharide (LPS) on LCs and DCs. Although stimulation with both ligands induced a marked up-regulation of CD83 expression on DCs, PGN but not LPS elicited up-regulation of expression CD83 on LCs. Consistent with these results, TLR2 and TLR4 were expressed on DCs, whereas only TLR2 was weakly detected on LCs. These findings suggest the actual feature of epidermal Langerhans cells with low-responsiveness to skin commensals.

Bacteria↗

PubMed2003

Cutting edge: major CD8 T cell response to live bacillus Calmette-Guérin is mediated by CD1 molecules.

MHC class I-restricted CD8(+) T cells are a crucial component of the host defense against mycobacterial infection in mice, but it has often proved very difficult to identify the CD8 T cell response in humans. Human group 1 CD1 molecules (CD1a, -b, -c) mediate MHC-independent presentation of mycobacteria-derived lipid and glycolipid Ags to CD8(+) T cells, and their intracellular localization to the endocytic system may favor efficient monitoring of phagosome-resident mycobacteria. Here, we show that bacillus Calmette-Guérin (BCG)-immunized subjects contain a significant circulating pool of CD8(+) T cells that recognize BCG-infected DCs in a CD1-dependent, but MHC-independent, manner. These CD1-restricted T cells efficiently detected live, rather than dead, BCG and produced IFN-gamma, an important cytokine for protection against mycobacterial infection. These results emphasize that lipid-reactive CD8(+) T cells may contribute to host defense against mycobacterial infection.

Adult↗

PubMed2003

Perforin-dependent killing of tumor cells by Vgamma1Vdelta1-bearing T-cells.

The T-cell subset expressing Vdelta2 paired primarily with Vgamma2 comprises a majority of gammadelta T-cells in human adult peripheral blood and expands significantly during a variety of infectious diseases. In contrast, the other subset of gammadelta T-cells that express Vdelta1 is rare among circulating T-cells and its function is poorly understood. Here, we show that a Vgamma1Vdelta1(+) T-cell line, 3-D, established from human peripheral blood by immortalization with Herpesvirus saimiri was able to specifically recognize tumor cells, such as K562 cells, and release cytotoxic granules containing perforin for target cell killing. Some tumor cells, including Daudi cells that are known to be susceptible to killing by Vdelta2(+) T-cells, were resistant to 3-D killing, implicating distinct pathways for tumor cell control by Vdelta1(+) and Vdelta2(+) T-cells. The 3-D T-cell receptor (TCR):CD3 complex reconstituted in TCR-deficient Jurkat cells was capable of transmitting signals, evidenced by activation of the interleukin 2 (IL-2) gene following ligation with anti-CD3 antibody, yet the TCR-reconstituted cells failed to produce IL-2 in response to the target cells. Thus, these results raise the possibility that some Vgamma1Vdelta1(+) T-cells could potentially be stimulated and lyse tumor cells via ligation of TCR/CD3-unassociated molecules.

Amino Acid Sequence↗

PubMed2003

Induction of hepatic injury by hepatitis C virus-specific CD8+ murine cytotoxic T lymphocytes in transgenic mice expressing the viral structural genes.

In the present study, we generated killer cells specific for hepatitis C virus (HCV) structural protein by re-stimulation of immune spleen cells from H-2(d) haplotype transgenic (Tg) mice, expressing the core, E1, E2, and NS2 genes of HCV regulated by the Cre/loxP switching system. The generated killer cells were conventional CD8(+)L(d) class-I MHC molecule-restricted cytotoxic T lymphocytes (CTLs) and specific for the HCV E1 structural protein. Because the CTLs could also kill hepatocytes from the Tg mice expressing HCV structural proteins in vitro, we attempted to transfer those CTLs intravenously into interferon regulatory factor-1 (IRF-1) negative, CD8-deficient Tg mice representing the HCV structural genes on hepatocytes to examine whether the inoculated CD8(+) CTLs can eliminate hepatocytes expressing the HCV genes in vivo. We observed an elevation of serum ALT level as well as damage of the liver tissue histologically. To our knowledge, this is the first demonstration to show that HCV-specific CD8(+) CTLs specifically attack hepatocytes expressing the HCV structural proteins both in vitro and in vivo.

Adenoviridae↗

PubMed2003

HIV mucosal vaccine: nasal immunization with gp160-encapsulated hemagglutinating virus of Japan-liposome induces antigen-specific CTLs and neutralizing antibody responses.

Nasal immunization of normal mice with HIVgp160-encapsulated hemagglutinating virus of Japan (HVJ)-liposome induced high titers of gp160-specific neutralizing IgG in serum and IgA in nasal wash, saliva, fecal extract, and vaginal wash, along with both Th1- and Th2-type responses. HIVgp160-specific IgG- and IgA-producing cells were also detected in mononuclear cells isolated from spleen, nasal cavity, salivary gland, intestinal lamina propria, and vaginal tissue of nasally immunized mice. In addition, CD8(+) CTLs were induced in mice nasally immunized with gp160-HVJ-liposome. These findings suggest that two layers of effective HIV-specific humoral and cellular immunity, in mucosal and systemic sites, were induced by this nasal vaccine. In immunodeficient mice, nasal immunization with gp160-HVJ-liposome induced Ag-specific immune responses for the systemic and mucosal compartments of both Th1 (IFN-gamma(-/-)) and Th2 (IL-4(-/-)). In vitro Ag-specific serum IgG Ab and vaginal wash samples possessing IgA and IgG Abs that had been induced by nasal immunization with gp160-HVJ-liposome were able to neutralize a clinically isolated strain of HIV-MN strain isolated from Japanese hemophiliac patients. Taken together, these results suggest that, for the prevention and control of AIDS, nasally administered gp160-HVJ-liposome is a powerful immunization tool that induces necessary Ag-specific immune responses at different stages of HIV infection.

AIDS Vaccines↗

PubMed2003

Induction of CD4+ murine natural killer T-like cells by immunization with syngeneic thymoma expressing embryonic alpha-fetoprotein.

In embryo, before the establishment of acquired immunity, a variety of embryonic antigens like alpha-fetoprotein (AFP) are produced and secreted in the sera, which rapidly disappear after the birth. Such embryonic antigens sometimes reappear from various tumor cells and decrease in the case of remission, indicating embryonic antigens may alert immune system to control tumors. In the present study, to examine the evoked immune responses against the tumors expressing embryonic antigen, we administered AFP-gene-transfected EL4 cells into syngeneic C57BL/6 mice and established a killer line against the tumor cells. To our surprise, the killer line was CD4+ NK1.1+, natural killer T (NKT)-like cells and eliminated not only AFP-expressing EL4 but YAC-1 cells. Moreover, the established line uniformly expressed Vbeta11 and secreted IL-4, IL-10, IL-13, and IFN-gamma. In vivo inoculation of the line markedly reduced the tumor growth in SCID mice, suggesting novelty of the NKT-like line for tumor surveillance.

Animals↗

PubMed2003

Antigen presentation in vaccine development.

A variety of microorganisms, nutrients or toxins are generally intrude our body through mucosal tissues or skin, where equipment for both preventing their invasions and catching their information to activate internal immune systems for adapting surroundings is arranged. Among the equipment, cells in charge of innate immunity, particularly dendritic cells (DCs), having an excellent capacity for prompt recognition of invaded pathogens via toll-like receptors (TLRs) to alert B and T cells for establishing aquired/adaptive immunity by presenting their processed antigenic fragments, have been paid great attention. These TLR-activated, antigen captured DCs are divided into two groups; one is pathogen-retaining unit and the other is pathogen-controlling unit. The latter DCs present processed antigenic molecules from the pathogens to competent alphabeta T cells together with special containers, such as class I, class II MHC and CD1 to generate specific cellular immunity. The former two MHC molecules can present processed peptide antigens, whereas the last CD1 molecule can present glycolipid/lipid antigens. In contrast, B lymphocytes that captured antigens via their specific immunoglobulin (Ig) receptors present digested peptide fragments with their class II MHC to stimulate suitable CD4(+) helper T cells which in turn secrete various cytokines to efficiently expand and maintain antibody production from that partner B cells to establish humoral immunity. These alphabeta T cells and antibodies, recognize either processed antigenic peptide or glycolipid fragments, and thus, identification of these epitopes enables us to generate artificial pathogen-specific vaccines. Based on the recent findings about precise mechanisms of antigen processing and presentation orchestrated at the surface compartment, future development of vaccines against various pathogens are discussed.

Animals↗