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J Faust

Publications and source records attributed to J Faust.

At least 37 records · Page 2Linked to original sources
PubMed1999

Osteoclast markers accumulate on cells developing from human peripheral blood mononuclear precursors.

Recent studies show that human osteoclasts develop in vitro from hematopoietic cells; however, special cultures conditions and/or cytokine mobilized peripheral blood are apparently required. Here, we report that cells expressing osteoclast markers differentiate from precursors present in nonmobilized peripheral blood mononuclear cells (PBMC), without the addition of stromal cells, growth factors, cytokines or steroids; and characterize their phenotype. Three days after establishing high-density PBMC cultures (1.5 x 10(6) cells/cm2), in serum-containing medium, small adherent colonies of tartrate resistant acid phosphatase positive (TRAP+) cells emerge, amidst massive monocyte cell death. These adherent cells have an eccentrically placed, round nucleus, and express low levels of TRAP and sodium fluoride-resistant- alpha-naphthyl-acetate-esterase (NaF-R-NSE). Over the next week, this cell population accumulates phenotypic markers of osteoclasts (vitronectin receptor [VR], calcitonin receptor, TRAP, cathepsin K protein, and mRNA) with increased nuclearity, covering the entire surface by 15 days. When cultured on bone, VR+, TRAP+ cells of low multinuclearity appear and cover up to 50% of the surface. Resorption lacunae can be observed by day 22. Although these pits are not nearly as numerous as the cells of preosteoclast phenotype, they do represent the activity of a subset of osteoclast-like cells that has achieved osteoclastic maturity under these culture conditions. Transcripts for osteoprotegerin ligand (OPGL), an osteoclast differentiation factor (also known as RANKL and TRANCE) are expressed, likely by adherent cells. Thus, an adherent population of cells, with preosteoclast/osteoclast phenotypic properties, arises selectively under simple culture conditions from normal PBMC. Further characterization of these cells should identify factors involved in the growth, terminal differentiation and activation of osteoclasts.

Acid Phosphatase↗
PubMed1998

Multiple myeloma cells and cells of the human osteoclast lineage share morphological and cell surface markers.

This study demonstrates that the multiple myeloma cell (MMC) in its plasma cell form is morphologically indistinguishable from human osteoclast-like cells that form in culture when peripheral blood mononuclear cells (PBMCs) are plated at high density in serum containing medium. MM has been described as a disease of B-cell lineage, monoclonal immunoglobulin (Ig) producing cells with unique properties: MM precursor cells lodge in bone, where they proliferate and differentiate into plasma cell tumors. Then, by some mechanism, presumably involving cytokines, these cells mediate an increase in neighboring osteoclast numbers and activity, leading to excessive bone erosion and hypercalcemia. Three days after plating PBMCs, tartrate resistant acid phosphatase- (TRAP-) blasts as well as TRAP+ cells, each with an eccentric nucleus, appear in culture. By day 10, TRAP+, vitronectin+ (VR+) cells, appear to be morphologically indistinguishable from multiple myeloma plasma cells (MMPCs) on cytocentrifuge preparations. These cells are CD19- and CD38++, as are MMCs reported by others. Other surface markers are also shared. Furthermore, Ig mRNA is demonstrated in the cytoplasm of cells at 8 days by in situ hybridization with the IgG FcA3 sequence. This novel finding is not unusual, in light of reports, demonstrating non-B-lineage Ig-producing cells. Thus, this study raises some serious questions about the true nature of MMCs.

ADP-ribosyl Cyclase↗
PubMed1998

Early phosphorylation events induced by DPIV/CD26-specific inhibitors.

Dipeptidyl peptidase IV (DPIV, CD26) is known to be involved in the regulation of T lymphocyte and NK cell activation and proliferation in vitro. The molecular events of lymphocyte activation mediated by this ectopeptidase as well as their physiological ligands are only partly established. Particularly, the necessity of catalytic dipeptidase activity for the costimulatory function of this molecule has been controversial. Here we provide evidence for a direct involvement of DPIV/CD26 in early phosphorylation mechanisms which are known to be essential in the signal transduction cascade of human T lymphocytes. We have found that DPIV-specific inhibitors (Lys[Z(NO2)]-thiazolidide and -piperidide) are capable of inducing intracellular tyrosine phosphorylation in resting human T cells. On the other hand, both inhibitors decreased the PMA-induced tyrosine phosphorylation in human T cells in a dose-dependent manner. Furthermore, a linkage between CD26 and the tyrosine kinase p56(lck) was shown by inhibition of PMA-induced hyperphosphorylation of p56(lck) by means of DPIV-specific inhibitors. The data presented here suggest that the inhibition of DPIV enzymatic activity induces a inhibitory signal transmitted by tyrosine kinases which leads to a block in a PMA-induced downstream pathway. These results support the assumption that DPIV/CD26 is directly involved in early processes of T cell activation via its enzymatic activity.

CD3 Complex↗
PubMed1998

Inhibitors of dipeptidyl peptidase IV/CD26 suppress activation of human MBP-specific CD4+ T cell clones.

The ectoenzyme dipeptidyl peptidase IV (DP IV, EC 3.4.14.5, CD26) has been shown to play a crucial role in T cell activation. Specific inhibitors of DP IV suppress DNA synthesis as well as cytokine production (IL-2, IL-10, IL-12, IFN-gamma) of stimulated human and mouse T cells suggesting a potential application of these effectors in transplantations and autoimmune diseases. In the present study, we have examined the expression of DP IV/CD26 on six myelin basic protein (MBP)(87-99)-specific, CD4+ T cell clones (TCC) derived from patients with multiple sclerosis (MS) as well as the biological effects of the two synthetic DP IV inhibitors Lys[Z(NO2)]-thiazolidide and Lys[Z(NO2)]-pyrrolidide on the function of these cells. All TCC expressed high levels of DP IV/CD26, as shown by flow cytometry and by enzymatic DP IV assay. Enzymatic activity of resting TCC was found to be three to fourfold higher than on resting peripheral blood T cells and close to that of T cells 48 h after PHA stimulation. The DP IV inhibitors suppress DNA synthesis and IFN-gamma, IL-4, and TNF-alpha production of the antigen-stimulated TCC. These data suggest that CD26 plays a role in regulation of activation of autoreactive TCC. Further in-vivo investigations, first in experimental models, will clarify, whether the inhibition of the enzymatic activity of DP IV could be a useful tool for therapeutic interventions in MS or other autoimmune diseases.

CD4 Antigens↗
PubMed1998

Dipeptidyl peptidase IV (DP IV, CD26) is involved in regulation of DNA synthesis in human keratinocytes.

Various studies have shown that the membrane ectoenzyme dipeptidyl peptidase IV (DP IV, CD26), expressed on T, NK, and B cells in the human immune system, is involved in the regulation of DNA synthesis and cytokine production. Here, we clearly demonstrate that this enzyme is highly expressed also on human epidermal foreskin and split-skin keratinocytes and that the specific DP IV inhibitors Lys[Z(NO2)]-thiazolidide, Lys[Z(NO2)]-pyrrolidide inhibit the enzymatic activity as well as the DNA synthesis of these cells. These data demonstrate that CD26 plays a role also in regulation of DNA synthesis of epidermal keratinocytes and that the enzymatic activity is required for mediating these effects.

Adult↗
PubMed1998

1H NMR conformational study on N-terminal nonapeptide sequences of HIV-1 Tat protein: a contribution to structure-activity relationships.

On the basis of our recent results, the N-terminal sequence of HIV-1 Tat protein as a natural competitive inhibitor of dipeptidyl peptidase IV (DP IV) is supposed to interact directly with the active site of DP IV hence mediating its immunosuppressive effects via specific DP IV interactions. Of special interest is the finding that amino acid substitutions of the Tat(1-9) peptide (MDPVDPNIE) in position 5 with S-isoleucine and in position 6 with S-leucine led to peptides with strongly reduced inhibitory activity suggesting differences in the solution conformation of the three analogues. Therefore, 1H NMR techniques in conjunction with molecular modelling have been used here to determine the solution structure of Tat(1-9), I5-Tat(1-9) and L6-Tat(1-9) and to examine the influence of amino acid exchanges on structural features of these peptides. The defined structures revealed differences in the conformations what might be the reason for different interactions of these Tat(1-9) analogues with certain amino acids of the active site of DP IV.

Amides↗
PubMed1998

Reduction of distress in children undergoing sexual abuse medical examination.

A participant modeling film to reduce distress in children (5 to 13 years old) undergoing sexual abuse medical examination was tested. Twenty-one children viewing the participant modeling film reported less fear after film viewing and were behaviorally less distressed and more compliant, as rated by nurses and mothers, during gynecological examination than 21 children viewing a nonrelevant film.

Adolescent↗
PubMed1998

Identification and characterization of autoantibodies against catalase and alpha-enolase in patients with primary sclerosing cholangitis.

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown aetiology. Recent studies have shown that genetic factors and both cellular and humoral immunological abnormalities are important in the pathogenesis of PSC. The most prominent autoantibodies in PSC are anti-neutrophil cytoplasmic antibodies (ANCA). The autoepitopes of ANCA in PSC are not well defined. The aim of this study was to identify corresponding ANCA autoantigens in patients with PSC. A biochemical approach with enrichment and partial purification of soluble neutrophil proteins, detection of autoantibodies by Western blot and partial amino acid sequencing were used. Two new autoantigen/autoantibody systems in patients with PSC were detected: catalase and alpha-enolase. The presence of catalase autoantibodies in 9/15 (60%) and alpha-enolase autoantibodies in 4/15 (27%) was confirmed by ELISA and Western blot. Furthermore, we showed immunoreactions of PSC sera with human biliary epithelial cells, showed the reduction of fluorescence in anti-catalase absorption experiments and observed partial co-localization of anti-catalase antibodies and PSC sera in double-staining experiments on biliary epithelial cells. The anti-catalase antibody-positive PSC patients had a more severe course of disease with a significantly higher alkaline phosphatase compared with the anti-catalase-negative PSC patients (P < 0.06). All ulcerative colitis control sera were anti-catalase antibody-negative. The identified antigens catalase and alpha-enolase can partly explain the ANCA fluorescence on ethanol-fixed and formaldehyde-fixed granulocytes in patients with PSC. Catalase is an important anti-oxidant enzyme and prevents cell damage from highly reactive oxygen-derived free radicals. Catalase autoantibodies might play a pathogenic role in patients with PSC. Our findings support the hypothesis that oxidative stress is one of the pathogenic mechanisms in patients with PSC.

Amino Acid Sequence↗
PubMed1998

Snapshot of a large dynamic replicon in a halophilic archaeon: megaplasmid or minichromosome?

Extremely halophilic archaea, which flourish in hypersaline environments, are known to contain a variety of large dynamic replicons. Previously, the analysis of one such replicon, pNRC100, in Halobacterium sp. strain NRC-1, showed that it undergoes high-frequency insertion sequence (IS) element-mediated insertions and deletions, as well as inversions via recombination between 39-kb-long inverted repeats (IRs). Now, the complete sequencing of pNRC100, a 191,346-bp circle, has shown the presence of 27 IS elements representing eight families. A total of 176 ORFs or likely genes of 850-bp average size were found, 39 of which were repeated within the large IRs. More than one-half of the ORFs are likely to represent novel genes that have no known homologs in the databases. Among ORFs with previously characterized homologs, three different copies of putative plasmid replication and four copies of partitioning genes were found, suggesting that pNRC100 evolved from IS element-mediated fusions of several smaller plasmids. Consistent with this idea, putative genes typically found on plasmids, including those encoding a restriction-modification system and arsenic resistance, as well as buoyant gas-filled vesicles and a two-component regulatory system, were found on pNRC100. However, additional putative genes not expected on an extrachromosomal element, such as those encoding an electron transport chain cytochrome d oxidase, DNA nucleotide synthesis enzymes thioredoxin and thioredoxin reductase, and eukaryotic-like TATA-binding protein transcription factors and a chromosomal replication initiator protein were also found. A multi-step IS element-mediated process is proposed to account for the acquisition of these chromosomal genes. The finding of essential genes on pNRC100 and its property of resistance to curing suggest that this replicon may be evolving into a new chromosome.

Chromosome Mapping↗
PubMed1997

The N-terminal structure of HIV-1 Tat is required for suppression of CD26-dependent T cell growth.

Evidence exists that the human immunodeficiency virus-1 (HIV-1) transactivator Tat occurs extracellularly and is involved in the immunosuppression of non-HIV-1-infected T cells of acquired immunodeficiency syndrome (AIDS) patients. The mechanism of this immunosuppressive activity of Tat has been controversially discussed. Interestingly, Tat binds to the T cell activation marker CD26, which has been shown to play a key role in the regulation of growth of lymphocytes and to inhibit its dipeptidyl peptidase IV (DP IV) activity. Here we show that the N-terminal nonapeptide MDPVDPNIE of Tat is a competitive inhibitor of DP IV and suppresses DNA synthesis of tetanus toxoid-stimulated peripheral blood mononuclear cells. Amino acid exchanges at positions 5 and 6 strongly weaken these effects. 1H nuclear magnetic resonance and molecular dynamics simulations of Tat(1-9), I5-Tat(1-9), and L6-Tat(1-9) suggest a similar backbone conformation for Tat(1-9) and L6-Tat(1-9). The solution conformation of I5-Tat(1-9) considerably differs from the other two. However, Tat(1-9) fits into our previously proposed active site model of DP IV in contrast to I5-Tat(1-9) and L6-Tat(1-9). Conformational alterations with regard to the parent peptide and spatial hindrances between these both compounds and DP IV can explain the loss of inhibitory activity. Our data suggest that the N-terminal residues of HIV-1 Tat do interact directly with the active site of DP IV and that DP IV does mediate Tat's immunosuppressive effects.

Amino Acid Substitution↗
PubMed1997

Inhibitors of dipeptidyl peptidase IV (DP IV, CD26) induces secretion of transforming growth factor-beta 1 (TGF-beta 1) in stimulated mouse splenocytes and thymocytes.

Various studies have shown that the ectoenzyme dipeptidyl peptidase IV (DP IV, CD26), expressed on T, NK and B cells in the human immune system, is involved in the regulation of DNA synthesis and cytokine production. The DP IV/CD26 was found also on mouse splenocytes and thymocytes. Here, we show that the specific DP IV inhibitors Lys[Z(NO2)]-thiazolidide, Lys[Z(NO2)]-pyrrolidide inhibit DNA synthesis as well as production of IL-2, IL-6 and IL-10 of PHA-stimulated mouse splenocytes and Con A-stimulated mouse thymocytes. Most importantly, these inhibitors induce a three to fourfold increased secretion of latent transforming growth factor beta 1 (TGF-beta 1) by mitogen-stimulated mouse immune cells, as measured with a specific TGF-beta 1 enzyme-linked immunosorbent assay (ELISA). These data demonstrate that CD26 plays a role also in regulation of DNA synthesis and cytokine production by murine immune cells, that the enzymatic activity is required for mediating these effects, and that TGF-beta 1 might have key functions in these processes.

Animals↗
PubMed1997

Inhibitors of dipeptidyl peptidase IV induce secretion of transforming growth factor-beta 1 in PWM-stimulated PBMC and T cells.

Various studies have shown that the membrane ectoenzyme dipeptidyl peptidase IV (DP IV; CD26), expressed on T, natural killer (NK) and B cells in the immune system, is involved in the regulation of DNA synthesis and cytokine production. We show that the specific DP IV inhibitors Lys[Z(NO2)]-thiazolidide, Lys[Z(NO2)]-piperidide, and Lys[Z(NO2)]-pyrrolidide inhibit DNA synthesis as well as production of interleukin-2 (IL-2), IL-10, IL-12, and interferon-gamma (IFN-gamma) of pokeweed mitogen (PWM)-stimulated purified T cells. Most importantly, these inhibitors induce a three- to fourfold increased secretion of latent transforming growth factor-beta 1 (TGF-beta 1) by PWM-stimulated peripheral blood mononuclear cells (PBMC) and T cells, as measured with a specific TGF-beta 1 enzyme-linked immunosorbent assay and in the Mv1Lu bioassay. As we could demonstrate previously, TGF-beta 1 exhibits the same inhibitory effects as DP IV inhibitors on DNA synthesis and cytokine production (Cytokine 1994, 6, 382-8; J Interferon Cytokine Res 1995, 15, 685-90). A neutralizing chicken anti-TGF-beta 1 antibody was capable of abolishing the DP IV inhibitor-induced suppression of DNA synthesis of PWM-stimulated PBMC and T cells. These data suggest that TGF-beta 1 might have key functions in the molecular action of DP IV/CD26 in regulation of DNA synthesis and cytokine production.

Cells, Cultured↗
PubMed1996

Induction of the membrane alanyl aminopeptidase gene and surface expression in human T-cells by mitogenic activation.

The metal-dependent membrane alanyl aminopeptidase (amino-peptidase N, APN, CD13; EC 3.4.11.2) is a well-established marker of normal and malignant cells of the myelo-monocytic lineage. It is also expressed by leukaemic blasts of a small group of patients suffering from acute or chronic lymphoid leukaemia. CD13-specific monoclonal antibodies do not bind to the surface of normal B lymphocytes, and APN mRNA was not detectable by Northern analysis in normal lymphocytes or in T-cell lines. Recently the expression of the APN gene in T-cell lines as well as the ability of these cells to cleave chromogenic substrates preferred by APN have been demonstrated [Lendeckel, Wex, Kähne, Frank, Reinhold and Ansorge (1994) Cell. Immunol. 153, 214-226]. Here, by means of dot-blot hybridization and RNase protection assay, evidence is provided that human peripheral T-cells as well as derived cell lines contain significant amounts of APN mRNA, comparable to that in the promyeloic cell line U937, and that mitogenic activation of peripheral human T-cells leads to a more than 4-fold increase in their APN mRNA content. In the course of activation, T-cells increase their total alanine p-nitroanilide-hydrolysing activity to approx. 7-fold that of resting cells. Furthermore these cells become immunoreactive towards CD13 to a significant extent (up to 51%) as shown by surface staining and confirmed by activity staining and immunostaining after isoelectric focusing (pI of T-cell APN = 4.6). In addition it is demonstrated by fluorescence microscopy that viable, activated T-cells effectively cleave the fluorogenic aminopeptidase substrate bis-glycyl-rhodamine 110 and that the corresponding aminopeptidase activity is associated with the cell surface. We show that specific inhibitors of APN, probestin and actinonin, strongly decrease DNA synthesis in phytohaemagglutinin (PHA)-stimulated T-cells. In summary, evidence is presented that in the course of mitogenic activation human peripheral T-cells increase the expression of APN both at the transcriptional level and at the cell surface. This has been demonstrated both at the APN mRNA level and at the protein level with respect to aminopeptidase enzymic activity and CD13 immunoreactivity.

CD13 Antigens↗
PubMed1996

The N-terminal X-X-Pro sequence of the HIV-1 Tat protein is important for the inhibition of dipeptidyl peptidase IV (DP IV/CD26) and the suppression of mitogen-induced proliferation of human T cells.

Recent data in the literature suggest that the HIV-1 Tat(1-86) protein exhibits immunosuppressive effects. Moreover, Tat was found to interact with dipeptidyl peptidase IV (DP IV), which is identical to the T cell activation marker CD26. Here we show that the N-terminal amino acid sequence of Tat is essential for the inhibition of DP IV-catalyzed IL-2(1-12) degradation. N-terminal modification of Tat with rhodamine prevented inhibition of enzymatic activity of DP IV as well as suppression of DNA synthesis of mitogen-stimulated human T cells. Moreover, natural peptides containing the X-X-Pro N-terminal motif of Tat also inhibited DP IV activity. These data suggest the existence of endogenous immunomodulatory oligopeptides which influence immune cell proliferation and differentiation via DP IV as does HIV-1 Tat.

Amino Acid Sequence↗
PubMed1996

The role of megakaryocyte growth and development factor in terminal stages of thrombopoiesis.

Thrombopoietin (TPO), the ligand for the c-Mpl cytokine receptor, is a recently identified cytokine with potent effects on platelet production. The receptor-binding portion of c-Mpl ligand is encompassed in another molecule known as megakaryocyte growth and development factor, or MGDF. Although it is clear that the administration of TPO or MGDF to animals dramatically increases the platelet count, the specific stage(s) of thrombopoiesis during which these molecules are principally active have not been unambiguously determined. Pharmacology studies administering MGDF at doses ranging from 0.1 to 630 micrograms/kg/d to mice revealed a biphasic response in platelet production. Administration of the drug at concentrations from 6 to 60 micrograms/kg/d resulted in platelet counts 5-fold above normal. However, doses > 60 micrograms/kg/d resulted in less-than-optimal platelet production. This phenomenon was investigated in vitro. Using an established culture system for the generation of human megakaryocytes and platelets, MGDF was shown to be optimally and equivalently active in the generation of mature megakaryocytes at concentrations from 10 to 1000 ng/ml. However, the cytokine was not required for proplatelet formation and in fact was inhibitory to that process in a dose-dependent manner. When MGDF was added to human megakaryocytes at concentrations of 200 ng/ml or greater, proplatelet formation was inhibited to 30% of control values. MGDF-mediated inhibition was specific, since the addition of the truncated form of the c-Mpl receptor reversed the inhibition in a dose-dependent manner. Other recombinant factors, interleukin-6, interleukin-11 and erythropoietin had no significant positive or negative effects in this human proplatelet assay. Together, these data suggest that although TPO and MGDF promote the full spectrum of megakaryocyte growth and development, they are not necessary for proplatelet formation, and may in part regulate platelet shedding by their absence.

Animals↗