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Biomedical subjects

A Koito

Publications and source records attributed to A Koito.

At least 19 recordsLinked to original sources
PubMed2001

[Perspectives on postgenome medicine: Gene therapy for AIDS].

Following the introduction of HAART(highly active anti-retroviral therapy) marked decreases in AIDS-related morbidity and mortality have been observed. Despite of the clinical success, recent work suggests that there are persistent viral replication in whom plasma HIV-RNA is consistently below detectable level. Furthermore, some experts even suggest that it will be difficult for many of the patients to continue the HAART because of the long-term side effects and drug resistance. Recent studies that supported the correlation of HIV-specific CD4-T cell(helper) response with the control of viral replication in vivo have promoted the development gene-based immunotherapy. However, further elucidation of viral pathogenesis in the patient under HAART will be required to develop the immunotherapeutic interventions.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Coreceptor function of mutant human CD4 molecules without affinity to gp120 of human immunodeficiency virus.

Despite extensive mutational studies on the human CD4 molecule and its affinity to human immunodeficiency virus (HIV) envelope glycoprotein gp120, coreceptor functions of such mutant molecules have only been examined by indirect measurement of their affinity to class II major histocompatibility complex (MHC) molecules. In this report, coreceptor functions of mutant human CD4 molecules, which have no or reduced affinity to an HIV envelope protein, gp120, were assessed in a murine T cell receptor/class II MHC recognition system. The substitution of human C" beta strand with the murine homologous segment resulted in the loss of the coreceptor function as well as in the complete loss of gp120 binding capacity, corroborating the consensus that Phe-43 in C" beta strand plays crucial roles in both situations. However, simultaneous replacement of the C'-C" loop along with the C" beta strand by homologous murine segments rescued the coreceptor function, whereas gp120 binding capacity remained negative. Further analysis indicated that insertion of lysine between Gly-41 and Ser-42 can partially compensate for the coreceptor function lost by the Phe-43 --> Val mutation. Although the coreceptor function of these mutant CD4 molecules in a human T cell recognition system is yet to be determined, these observations necessitate a re-evaluation of the role played by Phe-43 in coreceptor function. Examination of the sensitivities of the mutant CD4 molecules expressed on HeLa cells to infection by a T cell-tropic HIV-1 strain indicated that only those mutants that had completely lost gp120 binding capacity were resistant to the infection. All mutants having whole C" substitution, irrespective of additional substitutions or their coreceptor functions, were resistant to the infection.

Amino Acid Sequence↗
PubMed2000

Differential level in co-down-modulation of CD4 and CXCR4 primed by HIV-1 gp120 in response to phorbol ester, PMA, among HIV-1 isolates.

HIV-1 enters cells through interacting with cell surface molecules such as CD4 and chemokine receptors. We generated recombinant soluble gp120s derived from T-cell line-tropic (T-tropic) and macrophage-tropic (M-tropic) HIV-1 strains using a baculovirus expression system and investigated the association of CD4-gp120 complex with the chemokine receptor and/or other surface molecule(s). For monitoring the co-down-modulations of the CD4-gp120 complex, a cytoplasmic domain deletion mutant (tailless CD4), which is not capable of undergoing down-modulation by itself in response to phorbol ester PMA, was used. Our studies revealed both cell-type and HIV-1 strain-specific differences. We found that T-tropic gp120s were capable of priming co-down-modulation with tailless CD4 by interacting with CXCR4, whereas M-tropic SF162 gp120 could not after PMA treatment even in the presence of CCR5. Among the T-tropic HIV-1 envelopes, IIIB gp120 was the most potent. Furthermore, the ability of gp120 to prime the PMA induced co-down-modulation of tailless CD4 appeared to be dependent on the concentration of the principal coreceptor CXCR4. Nevertheless, the observation that IIIB gp120 strongly primed tailless CD4 co-down-modulation on human osteosarcoma HOS cells that express undetectable levels of surface CXCR4 raised the possibility that membrane component(s) other than those recently identified can be involved in down-modulation of the CD4/gp120 complexes.

3T3 Cells↗
PubMed1999

Human immunodeficiency virus type 1 Vpr modifies cell proliferation via multiple pathways.

Vpr, one of the accessory molecules of HIV-1, has been demonstrated to arrest the cell cycle at the G2 phase. This Vpr-mediated cell cycle arrest is implicated to have an important role in the viral life cycle. In the present study, we quantitate the extent of Vpr-mediated cell cycle arrest with the use of a bicistronic vector consisting of a vpr gene and a green fluorescence protein sequence. Using this system, we examined the effect of several Vprs on cell cycle progression and growth of cells from different species quantitatively. We found that Vpr from the T-cell line-adapted HIV-1SF2 strain (Vpr2) could not significantly induce G2 arrest in HeLa cells but was able to induce it in 293T cells. However, strong inhibition of cell proliferation in HeLa cells as well as in 293T cells was observed by Vpr2. This ability of Vpr2 to inhibit cell proliferation without G2 arrest was also observed when expressed in monkey cell line. Analyses of chimeric Vprs revealed that this species-non-specific growth inhibitory activity of Vpr was not mediated solely by the C-terminal region of Vpr. These results indicated that the growth inhibitory activity of Vpr is independent of its G2 arresting activity. In addition, the species-non-specific nature of this activity suggests that Vpr has a novel mechanism to retard cell proliferation by influencing basic cellular functions.

Adaptation, Biological↗
PubMed1998

Disturbed CD4+ T cell homeostasis and in vitro HIV-1 susceptibility in transgenic mice expressing T cell line-tropic HIV-1 receptors.

T cell line-tropic (T-tropic) HIV type 1 strains enter cells by interacting with the cell-surface molecules CD4 and CXCR4. We have generated transgenic mice predominantly expressing human CD4 and CXCR4 on their CD4-positive T lymphocytes (CD4+ T cells). Their primary thymocytes are susceptible to T-tropic but not to macrophage-tropic HIV-1 infection in vitro, albeit with a viral antigen production less efficient than human peripheral blood mononuclear cells. Interestingly, even without HIV infection, transgenic mice display a CD4+ T cell depletion profile of peripheral blood reminiscent of that seen in AIDS patients. We demonstrate that CD4+ T cell trafficking in transgenic mice is biased toward bone marrow essentially due to CXCR4 overexpression, resulting in the severe loss of CD4+ T cells from circulating blood. Our data suggest that CXCR4 plays an important role in lymphocyte trafficking through tissues, especially between peripheral blood and bone marrow, participating in the regulation of lymphocyte homeostasis in these compartments. Based on these findings, we propose a hypothetical model in which the dual function of CXCR4 in HIV-1 infection and in lymphocyte trafficking may cooperatively induce progressive HIV-1 infection and CD4+ T cell decline in patients.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Phosphorothioate hammerhead ribozymes targeting a conserved sequence in the V3 loop region inhibit HIV-1 entry.

Seven different phosphorothioate DNA-RNA chimeric hammerhead ribozymes (RzV3-nT, n = 1-7) targeted against the V3 loop region of HIV-1 were synthesized. Two of these, RzV3-1T and RzV3-3T, efficiently cleaved transcribed envelope RNA of HXB2 in vitro. The target sequence of RzV3-1T belongs to a conserved region and is completely identical in the HIV-1 HXB2, NL432, and ADA strains. Furthermore, RzV3-1T cleaved the envelope RNA of HIV-1 SF162 with a single base substitution in the distal site. U87 cells expressing CD4 and coreceptors were used as target cells for infections with the SF162 and NL432 strains. Replication of both the NL432 and SF162 strains in RzV3-1T-treated cells was significantly lower than that in control cultures. Envelope gene product formation was measured quantitatively with a single-cycle infection assay using pseudovirus generated from cotransfection with one vector containing a luciferase reporter gene and one vector containing the envelope gene of HXB2, SF162, or ADA. Production of pseudovirus in RzV3-1T-treated cells led to a marked (93% or 87%) inhibition of envelope-mediated entry of resultant HXB2-derived or ADA-derived pseudotype virions, respectively, and a moderate (44%) inhibition was seen for SF162-derived pseudotype virions. Thus, an efficient, stable ribozyme against a functionally important region of HIV-1 was identified by evaluating its activities in vitro and in vivo. This ribozyme may be useful for control of HIV-1 infection.

Animals↗
PubMed1995

Small amino acid sequence changes within the V2 domain can affect the function of a T-cell line-tropic human immunodeficiency virus type 1 envelope gp120.

Prior studies with recombinant viruses constructed in vitro showed that the V2 domain of envelope gp120, in addition to the required V3 domain, enhances the efficiency of infection of primary macrophages by HIV-1. Present structural studies on the gp120s of these recombinant viruses using three human monoclonal antibodies directed to the V3 loop indicate that the V2 domain affects cell tropism by modulating the conformation of the V3 loop. Additional mutational analyses of the V2 domain of the T-cell line-tropic virus HIV-1SF2 reveal that single amino acid sequence changes, mainly those affecting the location of potential N-linked glycosylation sites and the positive charge of this region, can also alter tropism. These amino acid substitutions in the V2 domain, however, do not appear to alter the conformation of the V3 loop. Thus, the V2 domain of gp120 can influence cell tropism through both an effect on V3 as well as via a V3-independent mechanism.

Amino Acid Sequence↗
PubMed1994

Functional role of the V1/V2 region of human immunodeficiency virus type 1 envelope glycoprotein gp120 in infection of primary macrophages and soluble CD4 neutralization.

We have examined the influence of the V1/V2 region of the human immunodeficiency virus type 1 (HIV-1) gp120 on certain biologic properties of the virus. We observed that on the genomic background of the T-cell-line-tropic strain, HIV-1SF2mc, both the V1 and V2 domains of the macrophage-tropic strain, HIV-1SF162mc, in addition to the required V3 domain, are necessary to attain full macrophage tropism. Furthermore, the V2 domain modulates the sensitivity of HIV-1 to soluble CD4 neutralization. Structural studies of recombinant and mutant envelope glycoproteins suggest that the function of the V1/V2 region is to interact with the V3 domain and confer on the envelope gp120 of HIV-1SF2mc a conformation more similar to that of the macrophage-tropic strain HIV-1SF162mc. The conformation of the envelope gp120 appears to be strain specific and plays an important role in determining HIV-1 tissue tropism and sensitivity to soluble CD4 neutralization.

Amino Acid Sequence↗
PubMed1992

Dysregulation of adult T-cell leukemia-derived factor (ADF)/thioredoxin in HIV infection: loss of ADF high-producer cells in lymphoid tissues of AIDS patients.

Adult T-cell leukemia (ATL)-derived factor (ADF) is a multifunctional protein homologous to thioredoxin (TRX) with co-cytokine and thiol-dependent reducing activities. ADF/thioredoxin production is enhanced in T cells transformed by HTLV-I. We have examined the effect of HIV-1 infection on ADF/TRX expression using specific antibody against ADF/TRX. Lymph nodes from 5 AIDS and 1 AIDS-related complex (ARC) patients were examined. As a control, 8 HIV noninfected lymph nodes, including 3 cases with hyperplasia, were also examined. Immunohistopathological studies using normal HIV noninfected lymph nodes showed that ADF/TRX high-producer (ADFh) cells were macrophages and cells with dendritic morphology in the paracortical area. Abundant ADFh cells were observed in HIV noninfected hyperplastic lymph nodes. The number of ADFh cells was low in hyperplastic lymph nodes from an ARC patient. All of the lymph nodes of 5 AIDS cases were atrophic and the number of ADFh cells were extremely low. To verify these histochemical studies, we examined the effect of in vitro HIV infection on ADF/TRX expression in HTLV-I (+) T-cell lines. Western blot analysis showed that a reduction of ADF/TRX in HIV-1-infected SKT-1B and MT-2 cells, and the reduction inversely correlated with p24 antigen level. On the basis of the above in vivo and in vitro findings, we imply that the levels of ADF/TRX were down-regulated by HIV-1 infection and that the down-regulation may play a role for pathophysiology of HIV-infected individuals.

AIDS-Related Complex↗
PubMed1990

Selective killing of HIV-infected cells by anti-gp120 immunotoxins.

Either ricin A chain (RAC) or Pseudomonas exotoxin (PE) was conjugated with a murine monoclonal antibody (0.5 beta) directed against an external envelope glycoprotein (gp120) of human immunodeficiency virus (HIV). Effects of the immunotoxins produced against infected cells were evaluated. Selective inhibition of the proliferation and killing of chronically HIV infected cells were observed in the presence of the immunotoxins. To determine the feasibility of the immunotoxins against the infected cells in seropositive subjects, we attempted to detect gp120-bearing cells in peripheral blood mononuclear cells (PBM) by cytofluorography. Cells in the monocyte/macrophage region of 2 of 10 PBM samples from HIV-infected individuals were found to react with 0.5 beta (18.1% and 12.8%). Furthermore, the cell population which was reactive with 0.5 beta was also susceptible to RAC conjugated with 0.5 beta. These results suggest that the strategy of using anti-gp120 immunotoxin to eliminate HIV-infected cells may be feasible in infected individuals.

Amino Acid Sequence↗
PubMed1990

Paroxysmal nocturnal haemoglobinuria with coexisting deficiency of the ninth component of complement: lack of massive haemolytic attack.

A 47-year-old woman with paroxysmal nocturnal haemoglobinuria (PNH) was found to have an inherited deficiency in the ninth complement component (C9). In complement-sensitivity lysis tests, 80% of her erythrocytes were markedly complement-sensitive (PNH-III). Laser cytofluorimetry with a monoclonal antibody against decay-accelerating factor (DAF) revealed that 95% of her erythrocytes were DAF-negative. Surprisingly, she has suffered only mild haemolysis and has never experienced massive spontaneous haemolysis. Gross haemoglobinuria and jaundice occurred only after receiving postoperative transfusion of whole blood. In her serum, C9 was not detectable either by immunological or by functional assays. Both the Ham test and the sugar water test using normal human serum or plasma yielded marked haemolysis of the patient's erythrocytes. When the patient's serum or plasma was used, only a trace of lysis was detected. Addition of purified human C9 to her plasma fully restored haemolysis. These observations indicated that C9 may play a critical role in haemolytic attacks in patients with PNH and that characteristic haemolysis in PNH may be tempered by coexisting C9 deficiency.

Complement C9↗
PubMed1989

Involvement of tryptase-related cellular protease(s) in human immunodeficiency virus type 1 infection.

Trypstatin, a new cellular Kunitz-type protease inhibitor purified from rat mast cells, inhibited syncytium formation in human immunodeficiency virus type 1 (HIV-1)-infected CCRF-CEM and uninfected Molt-4 clone 8 at a concentration of 1 microM. Anti-rat tongue mast cell tryptase antibodies reacted with Molt-4 clone 8 cells, as determined by Western blot and by immunofluorescence. In addition, the antibody inhibited syncytium formation. These findings along with homologous sequences with trypstatin and a neutralizing epitope of gp120 of HIV-1 suggest that a tryptase-like cellular enzyme(s) is involved in HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1989

A neutralizing epitope of human immunodeficiency virus type 1 has homologous amino acid sequences with the active site of inter-alpha-trypsin inhibitor.

A neutralizing epitope (epitope beta) of the HTLV-IIIB strain of HIV-1 was mapped to 24 amino acids of an external envelope glycoprotein (gp120) using a neutralizing monoclonal antibody (0.5 beta) and hetero-antisera against synthetic peptides encoding gp120. Proteins that have homologous sequences with epitope beta were sought from a databank of protein sequences to assess biological features of epitope beta. The results showed that epitope beta was found to have homologous sequences to inter-alpha-trypsin inhibitor (ITI). The homologous region of ITI included the active site of the protein. Synthesized peptides including epitope beta were good substrates for trypsin, because these peptides inhibited trypsin activities in a competitive manner (Ki = 24.5 microM). Human urinary trypsin inhibitor (UTI), a protein indistinguishable from ITI, as well as synthetic peptides including epitope beta inhibited syncytium formation caused by the LAV-1-infected CCRF-CEM and uninfected Molt-4 cells in a dose-dependent manner (0.1-1 mM). These findings suggest that epitope beta of HIV-1 could be substrate of protease upon HIV-1 infection and also suggest that protease inhibitory activity of epitope beta may play a role in the pathophysiology of HIV-1-infected individuals.

Alpha-Globulins↗
PubMed1989

Inhibition of human immunodeficiency virus infection of human lymphocytes by gangliosides.

As the first step in human immunodeficiency virus (HIV) infection, HIV binds to CD4 molecules on the surface of human T lymphocytes. Expression of CD4 by the cells is remarkably modulated by exogenously added gangliosides, which are normal components of the surface of animal cells. We report here that these physiological molecules also clearly inhibited HIV infection of lymphocytes in vitro in a dose-dependent manner through the selective modulation of CD4 from the cell surface. This raises the possibility of in vivo application of gangliosides as a new strategy for treating acquired immunodeficiency syndrome.

Antibodies, Monoclonal↗
PubMed1989

Frequent infection with human T-cell lymphotropic virus type I in patients with AIDS but not in carriers of human immunodeficiency virus type 1.

Antibody to human T-cell lymphotropic virus type I (HTLV-I) was measured in 49 Japanese patients (48 with hemophilia) infected with human immunodeficiency virus type 1 (HIV-1) and in 18 hemophiliacs who were not infected with HIV-1, by use of an enzyme-linked immunosorbent assay (ELISA). The antigen used was a gag-env hybrid protein constructed in vitro and expressed in Escherichia coli. This assay detected a specific antibody against HTLV-I. Four of the 18 HIV-1-negative hemophiliacs (22%) were positive for anti-HTLV-I antibody; their geometric mean titer was 951 U/ml. Seven of the 12 patients (58%) with acquired immune deficiency syndrome (AIDS) were positive for anti-HTLV-I antibody, and 8 of 35 HIV-1 + AIDS-free carriers (23%) were positive. The difference between the prevalence of HTLV-I infection in the two groups was statistically significant (p less than 0.0297). The geometric mean titer of antibody in the patients with AIDS was 318 U/ml and that for the HIV-1 + AIDS-free carriers was 1,496 U/ml. These findings suggest that HTLV-I infection could be one of the factors in the development of AIDS in individuals infected with HIV-I.

AIDS-Related Complex↗
PubMed1988

Conserved immunogenic region of a major core protein (p24) of human and simian immunodeficiency viruses.

A murine monoclonal antibody (MoAb), VAK 4, has been known to specifically react with a major core protein (p24) as well as with its precursor (p55-57) and intermediate precursor (p40) of human immunodeficiency virus strain IIIB (HTLV-IIIB). Radioimmunoprecipitation assays revealed that VAK 4 MoAb precipitated a major core protein and its precursors from a variety of strains of HIV and also from simian immunodeficiency virus (SIV), although the molecular weights of the precursor proteins in each viral strain were slightly different. A protein synthesized by transfected Escherichia coli containing amino acid sequences corresponding to residues 121-436 of the HTLV-IIIB gag gene was reactive with VAK 4 MoAb, but the protein carrying only residues 121-309 was not reactive, suggesting that the epitope recognized by VAK 4 MoAb resides at the carboxyl terminus of p24 protein. A competitive enzyme-linked immunosorbent assay showed that patient sera containing anticore protein antibody inhibited the binding of VAK 4 to HTLV-IIIB. These findings suggested that VAK 4 MoAb recognized an immunogenic and conserved epitope belonging to a major core protein of HIV-related viruses.

Antigens, Viral↗
PubMed1988

Histo- and immunopathological features of terminal AIDS. An autopsy case of a Japanese man with neurological signs as initial symptoms.

An autopsy case of a 37-year-old Japanese man, confirmed as an AIDS patient infected by an undetermined route of transmission, is presented. The initial symptoms of full-blown AIDS in this case were neurological, and the patient died of severe pneumonia 9 months after onset. The main histo- and immunopathological features were a marked depletion of helper-inducer T cells and dendritic reticulum cells in the lymphoid tissues, opportunistic infections, and some neuropathologic changes. Very few cells, possibly macrophages, immunoreactive with a monoclonal antibody (VAK-5) against HIV-gag protein P24 were found in the mediastinal lymph nodes. Numerous pathogens had induced opportunistic infections in many organs: severe and generalized cytomegalovirus infection, Pneumocystis carinii pneumonia, bronchopneumonia (possibly due to Pseudomonas aeruginosa), candidiasis in the tongue and oral cavity, and atypical mycobacteriosis in the pulmonic hilar lymph nodes. Vascular proliferation was found in the perinodal regions of some lymph nodes, but this was not neoplastic vascular proliferation compatible with that of localized Kaposi's sarcoma.

Acquired Immunodeficiency Syndrome↗