Biomedical subjects

H Nagafuchi

Publications and source records attributed to H Nagafuchi.

25 records · Page 2Linked to original sources

PubMed1997

Mechanisms of KE298, 2-acetylthiomethyl-3-(4-methylbenzoyl) propionic acid, to suppress abnormal synovial cell functions in patients with rheumatoid arthritis.

OBJECTIVE: 2-Acetylthiomethyl-3-(4-methylbenzoyl) propionic acid, KE298, a derivative or propionic acid developed in Japan has been shown to be effective for suppressing disease activity of rheumatoid arthritis (RA) in clinical trials in Japan. It is thus a candidate as a new disease modifying antirheumatic drug (DMARD). We analyzed effects of KE298 on synovial fibroblast-like cells in patients with RA to obtain insight into the clinical application of this medication. METHODS: RA synovial fibroblast-like cells were co-cultured with KE298 at 10(-4)-10(-5) M in the presence or absence of tumor necrosis factor-alpha 2 ng/ml, and their subsequent proliferative responses and proinflammatory cytokine and matrix metalloproteinase (MMP) production at the mRNA and protein levels were measured. Effects of KE298 on MMP-1 gene transcription and AP-1 transcription factor expression of RA synovial cells were studied by chloramphenicol acetyltransferase assay and gel shift assay, respectively. RESULTS: KE298 inhibited proliferation of RA synovial cells, proinflammatory cytokine production, and MMP-1 production mainly by reducing their transcription via downmodulation of AP-1 transcription factor. CONCLUSION: KE298 inhibits aberrant synovial cell functions of patients with RA by downregulating gene transcription, suggesting clinical application and usefulness of this new DMARD.

Antirheumatic Agents↗

PubMed1994

Fine antigen specificity of human gamma delta T cell lines (V gamma 9+) established by repetitive stimulation with a serotype (KTH-1) of a gram-positive bacterium, Streptococcus sanguis.

We have established human gamma delta T cell lines specific for Streptococcus sanguis (S. sanguis) KTH-1 present in normal oral cavity flora. The CD4-CD8-CD3+V gamma 9+V delta 1-CD45RO+ CD25+ T cell lines showed a proliferative response to the streptococcal antigen (Ag) in the presence of autologous antigen-presenting cells without apparent evidence of HLA restriction. The proliferative response of the gamma delta T cell lines was completely blocked by anti-TcR gamma delta monoclonal antibody (mAb) and anti-HLA class I mAb (W6/32), whereas anti-HLA classical class Ia mAb (B-H9; anti-HLA-A,B,C), anti-HLA class II mAb (anti-DR, anti-DQ, and anti-DP) and anti-CD4 mAb did not have any inhibitory effects. Surprisingly, the gamma delta T cell lines showed the proliferative response against the original bacterial Ag KTH-1 exclusively, and exhibited no cross-reactivity with nominal Ag such as purified protein derivative of tuberculin, tetanus toxoid and Mycobacterium tuberculosis, or the same species but different strain of S. sanguis, American Type Culture Collection (ATCC) standard strain (10556), or even with the same strain but different serotype of S. sanguis, KTH-3. Moreover, cytokine production of the gamma delta T cell lines was similar to the Th1 pattern [interferon-gamma, tumor necrosis factor (TNF)-alpha and TNF-beta]. They also produced interleukin-8 that functions as one of chemoattractants for polymorphonuclear cells. Using direct sequencing technique of the polymerase chain reaction products, we found that junctional diversity of the T cell receptor (TcR) used by the parental KTH-1 specific gamma delta T cell line and its subclones is rather limited. It is suggested that gamma delta T cells with canonical TcR could preferentially respond to KTH-1 Ag. Thus, in addition to a broad or cross-reactivity of gamma delta T cells against phylogenetically conserved stress/heat-shock protein, which is well characterized by others, some peripheral blood gamma delta T cells could recognize and kill exogenous agents with fine antigenic specificity to protect the body against them.

Antigens, Bacterial↗

PubMed1993

Constitutive expression of IL-6 receptors and their role in the excessive B cell function in patients with systemic lupus erythematosus.

Excessive B cell function including autoantibody production is a common feature of SLE and considered to be intimately associated with spontaneous lymphokine secretion by themselves. To clarify roles of IL-6/IL-6 receptor autocrine activation pathway in autoantibody production observed in patients with SLE, we studied expression and function of IL-6 receptors in comparison with those of IL-2 receptors, Tac on SLE B cells. IL-6 receptors and IL-2 receptors have been detected on B cells in the blood without any in vitro stimuli in most patients with SLE. The introduction of anti-IL-6 receptor antibody, which inhibits binding to the receptors of IL-6, and anti-IL-2 receptor antibody, anti-Tac to the cultures of SLE B cells resulted in potent inhibition of spontaneous production of polyclonal Ig and anti-DNA autoantibodies. In addition, fresh SLE B cells secreted high levels of IL-6 without any in vitro stimuli. These results indicate that constitutive expression of IL-6 receptors on B cells in conjunction with spontaneous IL-6 production by B cells induces autocrine B cell activation, which may lead to B cell hyperactivity and autoantibody secretion in SLE patients. Dysregulation of B cell activity observed in patients with SLE could thus be, at least in part, independent of T cell help.

Adolescent↗

PubMed1991

T cell interactions in active rheumatoid arthritis: insights from the human autologous mixed lymphocyte reaction as a model of T cell activation cascade.

The autologous mixed lymphocyte reaction (AMLR) represents the activation, proliferation and differentiation of T cells in response to signals from autologous non-T cells. Using monoclonal anti-Leu8 antibody to isolate subpopulations of human CD4+ and CD8+ T cells, we have investigated the role of these subpopulations in the T cell activation cascade during the course of AMLR. In normal subjects, CD4+Leu8+ cells are necessary for the initiation of the AMLR response, and sequentially lead to activation and proliferation of both CD4+Leu8- cells and CD8+Leu8+ cells. The activated CD8+Leu8+ cells, in turn, induce CD8+Leu8- cells to generate proliferation of the latter cells. Soluble mediators could be involved in the T cell activation cascade induced by the AMLR. Patients with active rheumatoid arthritis have a profound defect in the AMLR. Further analysis indicates that rheumatoid arthritis CD8+ T cells are markedly defective as responding cells in the AMLR. The impaired AMLR response by CD8+ cells cannot be reconstituted with AMLR-derived supernatants from normal T cells. The data suggest that the defective CD8+ T cell function may contribute to the pathogenesis of the disease.

Adult↗

PubMedDate not supplied

Aberrant expression of Fas ligand on anti-DNA autoantibody secreting B lymphocytes in patients with systemic lupus erythematosus: "immune privilege"-like state of the autoreactive B cells.

BACKGROUND: Fas/Fas ligand (FasL) system has been assigned a pivotal role in the development and maintenance of peripheral tolerance, and mice with defects in their Fas/FasL system develop lupus-like symptoms. In this study we examined FasL expression of peripheral blood lymphocytes in patients with systemic lupus erythematosus (SLE). METHODS: We assessed FasL mRNA and protein expression by reverse transcription (RT)-PCR and immunoblotting and immunocytochemical staining, respectively, in patients with SLE. Anti-DNA antibody secreting B cells were purified using biotin labeled DNA and streptavidin-bead. RESULTS: Expression of FasL protein was not or very weakly detected in freshly isolated PBMC in normal individuals. In contrast, freshly isolated SLE PBMC exhibited the enhanced expression of FasL protein without in vitro stimulation. Not only purified T cells but also purified B cells expressed FasL on their cell surface spontaneously. In addition, freshly isolated anti-DNA autoantibody secreting B cells express FasL without in vitro stimulation. CONCLUSION: The results suggest that autoreactive B lymphocytes which aberrantly express FasL may kill Fas+ immunoregulatory T lymphocytes. Thus aberrantly expressed FasL may facilitate escape of the autoreactive B cells from the immune tolerance system, and may contribute to the sustained secretion of autoantibodies in patients with SLE.

Adolescent↗

PubMedDate not supplied

Preferential expression of B7.2 (CD86), but not B7.1 (CD80), on B cells induced by CD40/CD40L interaction is essential for anti-DNA autoantibody production in patients with systemic lupus erythematosus.

OBJECTIVE: B7 (CD80/CD86) molecules are over-expressed in patients with SLE. However, it is not clear whether CD80/CD86 molecules are involved in the pathogenic autoantibody production specifically or in the polyclonal antibody production in human SLE. The present study was carried out to characterize B7 molecules on B cells in autoantibody production. METHODS: Expression of costimulatory molecules was analyzed by RT-PCR and two-color immunofluorescence staining. Purified B cells were co-cultured with T cells in the presence of anti-costimulatory molecule antibody. RESULTS: Excessive expression of CD86 and CD80 molecules was evident on freshly isolated B cells in patients with SLE. Normal B cells did not express CD86 molecules spontaneously and expressed it after co-culture with activated T cells. CD86 expression on normal and SLE B cells induced by the activated T cells was inhibited by the addition of anti-CD40L into the cell culture. Furthermore, CD40L expression on T cells upon activation was enhanced in SLE patients. Anti-DNA antibody production by SLE B cells in the presence of activated T cells was markedly inhibited by anti-CD86, but not anti-CD80. Anti-CD86 treatment inhibited polyclonal Ig and anti-SS-A antibody production of SLE B cells, suggesting the preferential involvement of CD86 in polyclonal antibody production. CONCLUSION: SLET T cells express CD40L excessively, and the CD40/CD40L pathway is involved in the CD86 over-expression of SLE B cells; thus T cell abnormality is at least partially involved in B cell hyperactivity. Enhanced CD86 expression of B cells by CD40L is essential for polyclonal antibody production.

Adolescent↗

PubMedDate not supplied

Selective suppression of resting B cell function in patients with systemic lupus erythematosus treated with cyclophosphamide.

The immunological function of patients with inactive systemic lupus erythematosus (SLE) receiving chronically administered, low-dose cyclophosphamide (CY) together with prednisolone (PSL) was compared with that of inactive patients receiving PSL alone. A striking selective suppression of "genuine" resting, but not "partially" or "fully" activated, B cell function was noted in the patients receiving PSL + CY as measured by Staphylococcus aureus Cowan I (SAC)-induced proliferative responses by Percoll-separated small resting B cells of high density; the small resting B cells sedimenting in a high density fraction were more responsive to SAC in patients treated with PSL alone than those in normal controls. However, the spontaneous proliferation and spontaneous secretion of immunoglobulins by peripheral blood B cells were elevated in both the patient groups. The proliferative responses to phytohaemagglutinin and concanavalin A by T cells were not significantly different between both patient groups. The data indicate that the genuine resting B cells may be the major target for the CY effect in SLE, and thus such selective suppression may help explain the efficacy of CY and PSL together in treating SLE.

Adult↗