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Biomedical subjects

S Ansorge

Publications and source records attributed to S Ansorge.

At least 37 records · Page 2Linked to original sources
PubMed2000

MRP8/MRP14, CD11b and HLA-DR expression of alveolar macrophages in pneumonia.

Activation of alveolar macrophages is characterised by specific alterations to the expression pattern of surface markers under certain pathological conditions. MRP8/MRP14 and CD11b are involved in the regulation of macrophage migration and adhesion. HLA-DR regulates the antigen presentation by alveolar macrophages. The aim of this study was to investigate the phenotype of alveolar macrophages in pneumonia particularly in relationship to the changes in concentrations of TGF-beta1 and IL-8. Using cytofluorimetry, we analysed the surface expression of MRP8/MRP14, CD11b, and HLA-DR on alveolar macrophages of 42 pneumonia (PN) patients, 14 patients with interstitial lung diseases (ILD), five patients with chronic obstructive lung disease (COPD), and 58 patients without lung disease. Phenotypic characteristics were correlated to the concentration of TGF-beta1 and IL-8 in the bronchoalveolar lavage fluid (BALF) of the same patients. The direct influence of TGF-beta1 and IL-8 on expression of MRP8/MRP14, CD11b and HLA-DR of cultured monocytes and MonoMac cells was analysed. Significantly more MRP8/MRP14 and CD11b positive macrophages and less HLA-DR-positive macrophages were found in PN but not in ILD or COPD. The percentage of CD11b-positive macrophages correlated with the TGF-beta1 as well as the IL-8 concentrations. The amount of HLA-DR-positive macrophages correlated negatively to the concentration of TGF-beta1 and IL-8. These findings document a significant activation of alveolar macrophages during pneumonia. TGF-beta1 led to a modulation of HLA-DR and MRP8/MRP14-antigen expression in vitro. In conclusion, it was shown that in pneumonia but not in ILD or COPD alveolar macrophages were characterised by an increased MRP8/MRP14 and CD11b expression and a diminished HLA-DR expression. The characterisation of subpopulations within the alveolar macrophages may be a useful tool for the monitoring of disease progression.

Antigens, Differentiation↗
PubMed2000

Amino-terminal truncation of procalcitonin, a marker for systemic bacterial infections, by dipeptidyl peptidase IV (DP IV).

Increased concentrations of procalcitonin (PCT) are found in the plasma of patients with thermal injury and in patients with sepsis and severe infection, making this molecule important as a diagnostic and prognostic marker in these diseases. Interestingly, only the truncated form of PCT, PCT(3-116), is present in the plasma of these patients. The enzyme responsible for this truncation is unknown as yet. Here, using capillary zone electrophoresis, mass spectrometry and Edman sequence analysis, we demonstrate that dipeptidyl peptidase IV (DP IV, EC 3.4.14.5) is capable of catalyzing the hydrolysis of PCT(1-116), releasing the N-terminal dipeptide Ala-Pro. We hypothesize that PCT(3-116) is the result of the hydrolysis of PCT(1-116) by soluble DP IV of the blood plasma or by DP IV expressed on the surface of cells.

Bacterial Infections↗
PubMed2000

A new type of fluorogenic substrates for determination of cellular dipeptidyl peptidase IV (DP IV/CD26) activity.

The stability of cell associated fluorescence is an essential requirement for measurements of cellular enzymatic activity via enzyme catalyzed liberation of fluorophores. Rhodamine 110 (R110), a highly fluorescent xanthene dye, was used to synthesize nonfluorescent dipeptidyl peptidase IV (DP IV) substrates Xaa-Pro-R110-Y allowing the stable covalent binding of the enzymatically released fluorescent R110-Y on cells. All compounds have been characterized as substrates of isolated DP IV with kcat/Km values of about 10(6) M-1.s-1. The hydrophobicity of the residue Y affects the affinity of the substrate to the catalytic site of DP IV. The compounds are characterized as sensitive substrates of cell surface associated DP IV of DP IV rich U-937 cells. The binding of the enzymatically released R110-Y on cells results in a stable cellular fluorescence. This way, the quantitative determination of cell surface associated DP IV activity is possible.

Amino Acids↗
PubMed2000

N-terminal HIV-1 Tat nonapeptides as inhibitors of dipeptidyl peptidase IV. Conformational characterization.

Compared to the N-terminal nonapeptide of the HIV-1 Tat protein as inhibitor of activity of DP IV which is supposed to mediate the immunosuppressive effects of HIV-1 Tat, the Ile5 and Leu6 analogues showed strongly reduced inhibitory activity. Interestingly, replacement of Asp2 with Gly or Lys led to compounds with considerably enhanced inhibition. Therefore, we have applied 1H NMR spectroscopy and restrained molecular dynamics calculations to elucidate the molecular conformation of a series of Tat nonapeptides. Conformational backbone differences of these peptides as well as the nature and the arrangement of the side chains per se at significant positions preventing effective binding to DP IV might explain their different inhibitory activity on DP IV.

Amino Acid Substitution↗
PubMed2000

Signal transduction events induced or affected by inhibition of the catalytic activity of dipeptidyl peptidase IV (DP IV, CD26).

DP IV (CD26) represents an accessory surface molecule playing an important role in the process of activation and proliferation of human lymphocytes. The molecular events mediated by this ectoenzyme are only partly established and the necessity of DP IV enzymatic activity for its signalling capacity has been discussed controversial. Focusing on the putative role of the catalytic domain of this peptidase, it could be shown that inhibition of the catalytic activity can provoke many cellular effects, including induction of tyrosine phosphorylations and p38 MAP kinase activation as well as suppression of DNA synthesis and reduced production of various cytokines. TGF-beta 1, the production and secretion of which is increased after DP IV inhibition, supposedly mediates the observed suppressive effects by maintaining p27kip expression levels which leads to a cell cycle arrest in G1. Moreover, anti-CD3-induced signalling pathways, including Ca2+ mobilisation, MEK1-, Erk1/2- and PKB-activation, can be strongly affected by DP IV inhibition. Thus, the enzymatic activity or at least the interaction of effectors with the catalytic domain of CD26 seems to be important for crucial functions of this cell surface antigen.

Calcium Signaling↗
PubMed2000

Specific inhibitors of dipeptidyl peptidase IV suppress mRNA expression of DP IV/CD26 and cytokines.

The dipeptidyl peptidase IV is an activation marker on T, B and NK cells. Specific inhibitors of DP IV suppress DNA synthesis, as well as cytokine protein production. Here, we describe for the first time the quantitative changes of mRNA expression of IFN-gamma, IL-2, IL-12 and DP IV after inhibition of DP IV. Due to the stimulation of human peripheral blood mononuclear cells (PBMC) with pokeweed mitogen (PWM) both cytokine as well as DP IV mRNA expression is increased significantly. Treatment with DP IV inhibitor suppresses dose-dependently these changes. Importantly, mRNA expression of DP IV itself was inhibited. The presented data are fully compatible with our hypothesis that inhibition of DP IV leads to cell cycle arrest in late G1 due to enhanced TGF-beta 1 expression.

Autocrine Communication↗
PubMed2000

Dipeptidyl peptidase IV in inflammatory CNS disease.

Current pathogenic concepts of inflammatory demyelinating disorders such as multiple sclerosis (MS) are based on the hypothesis that a T cell-mediated autoimmune response is involved in the disease process. One of the primary goals in the in the development of immunotherapies for autoimmune diseases has been to achieve inactivation of disease-inducing lymphocytes either by direct inhibition or suppression through regulatory cells and/or cytokines. The CD26 antigen is identical with the cell surface ectopeptidase dipeptidyl peptidase IV (DP IV, EC 3.4.14.5) which is involved in regulating T cell activation and growth. Activated T cells, including those specific for myelin antigens, express high levels of CD26/DP IV. In vitro, reversible DP IV inhibitors suppress T cell proliferation and pro-inflammatory cytokine production in response to myelin antigens. Further studies will evaluate the role of DP IV inhibition in T cell-mediated inflammatory disease of the central nervous system.

Animals↗
PubMed2000

Dipeptidyl peptidase IV (CD26): role in T cell activation and autoimmune disease.

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. In the present study, we show by flow cytometry and by enzymatic DP IV assay that myelin basic protein (MBP)-specific, CD4+ T cell clones (TCC) derived from patients with multiple sclerosis (MS) express high levels of DP IV/CD26. The 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 hours after PHA stimulation. The DP IV inhibitors Lys[Z(NO2)]-thiazolidide and Lys[Z(NO2)]-pyrrolidide suppress in a dose-dependent manner 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 regulating activation of autoreactive TCC. Further in vivo investigations will clarify, whether the inhibition of the enzymatic activity of DP IV could be a useful tool for therapeutic interventions in MS and/or other autoimmune diseases.

Autoimmune Diseases↗
PubMed2000

Effects of nonapeptides derived from the N-terminal structure of human immunodeficiency virus-1 (HIV-1) Tat on suppression of CD26-dependent T cell growth.

The human immunodeficiency virus-1 (HIV-1) transactivator Tat occurs extracellularly and exerts immunosuppressive effects. Interestingly, Tat inhibits dipeptidyl peptidase IV (DP IV) activity of the T cell activation marker CD26. The short N-terminal nonapeptide Tat(1-9), MDPVDPNIE, also inhibits DP IV activity and suppresses DNA synthesis of tetanus toxoid-stimulated peripheral blood mononuclear cells (PBMC). Here, we present the influence of amino acid exchanges in the first three positions of Tat(1-9). For instance, the replacement of D2 of Tat(1-9) by G or K generated peptides, which inhibit DP IV-catalyzed IL-2(1-12) cleavage nearly threefold stronger. Similar effects were observed on the suppression of DNA synthesis of Tetanus toxoid-stimulated PBMC. This correlation suggests that Tat(1-9)-deduced peptides mediate antiproliferative effects at least in part via specific DP IV interactions and supports the hypothesis that CD26 plays a key role in the regulation of lymphocyte growth.

Acetylation↗
PubMed2000

DNA synthesis in cultured human keratinocytes and HaCaT keratinocytes is reduced by specific inhibition of dipeptidyl peptidase IV (CD26) enzymatic activity.

The ectopeptidase dipeptidyl peptidase IV (DP IV, CD26, EC 3.4.14.5) is present on most mammalian cells. Using specific inhibitors of DP IV, it has been shown that this enzyme is involved in the regulation of DNA synthesis and in production of various cytokines in lymphocytes. The aim of the present work was to investigate the expression of DP IV/CD26 on human keratinocytes and to answer the question, whether the proliferation (DNA synthesis) of human keratinocytes is influenced by inhibition of the enzymatic activity of DP IV. Using flow cytometry, RT-PCR, and specific enzymatic activity assays, expression of DP IV-mRNA and CD26 antigen were shown on primary keratinocyte strains and on the HaCaT keratinocyte cell line. The synthetic DP IV inhibitors Lys[Z(NO2)]-thiazolidide and -pyrrolidide suppress the DNA-synthesis of these cells in a dose-dependent manner. These data demonstrate that CD26 is also involved in the regulation of DNA synthesis of keratinocytes and that the enzymatic activity is required for mediating these effects.

Adult↗
PubMed2000

Modulation of WNT-5A expression by actinonin: linkage of APN to the WNT-pathway?

Inhibition of alanyl-aminopeptidase gene expression or enzymatic activity compromises T cell proliferation and function. Molecular mechanisms mediating these effects are not known as yet. Applying the cDNA array technique we identified the proto-oncogen Wnt-5a strongly affected by APN-inhibition. Wnt-5a and other members of the Wnt family of secreted factors are implicated in cell growth and differentiation. Wnt-5a was moderately expressed in resting T cells, but strongly down-regulated in response to activation by OKT3/IL-4/IL-9. Actinonin increased Wnt-5a-mRNA contents as confirmed by RT-PCR. In addition, expression of GSK-3 beta, an inherent component of the Wnt-pathway, was found to be increased in response to activation, but suppressed by actinonin at both the mRNA and protein level. These findings may provide a rationale for the strong growth inhibitory effects resulting from an inhibition of alanyl aminopeptidase expression or activity.

CD13 Antigens↗
PubMed2000

Cathepsin K expression in human lung.

Tissue remodeling is crucial in different lung diseases, in the embryonal development as well as in bronchial carcinoma. Cathepsins were proposed to be involved in the degradation of matrix proteins. Cathepsin K is one of the most potent matrix-degrading cysteine proteinases known as yet. The elastinolytic and collagenolytic activity of this papain-like protease is comparable with that of neutrophil elastase. We have investigated the cathepsin K expression in normal adult lung tissues, in embryonal lung tissue and in bronchial carcinoma. With help of specific anti-cathepsin K antibodies it could be shown that cathepsin K was expressed in bronchial epithelial cells. These data could be confirmed at mRNA level using a quantitative RT-PCR as well as by visualisation of the specific enzymatic activity in epithelial cell lines. During the embryonal development cathepsin K was expressed in the epithelial cells of the developing bronchi. The expression seemed to be upregulated in parallel with the development of the bronchial and alveolar lumen. In the later phase of lung development the cathepsin K expression was restricted to bronchial epithelial cells. Furthermore, using quantitative RT-PCR it could be shown that cathepsin K-mRNA was upregulated in lung tumor tissues in comparison to normal tissues from the same patients. These data suggest that cathepsin K may play an important role in matrix remodeling of the lung under physiological and pathological conditions.

Bronchi↗
PubMed2000

Expression of cathepsins B and L in human lung epithelial cells is regulated by cytokines.

The cathepsins B, L, and H are expressed ubiquitously and represent the major proportion of lysosomal enzymes. They are involved in bulk proteolysis in the lysosomes, processing of proteins and matrix degradation. Under pathological conditions the participation of cathepsins, especially their secreted forms, was observed in inflammation, tumor progression and metastasis. The enzymatic activity of cathepsins is regulated by posttranslational modification, localization, maturation, changes in pH, and their interaction with inhibitors. Regulation at the level of transcription is not well elucidated. The aim of this study was to investigate the effect of IL-1 beta, IL-6, IL-10, TGF-beta 1, and HGF on mRNA expression and protein level in human lung epithelial cell lines A-549 and BEAS-2B. IL-6 leads to a twofold increase in cathepsin L mRNA expression, whereas TGF-beta 1 decreases the amount of cathepsin L mRNA. At protein level, using enzyme immunoassay, it was shown that IL-6 induced increased amounts of cathepsin L but not cathepsin B. In contrast, after incubation of bronchial epithelial cells with TGF-beta 1 the cathepsin L concentration was decreased. In conclusion, gene expression of cathepsins B and L is variable. The cytokines IL-6 and TGF-beta 1 modulate cathepsin gene expression.

Carcinoma↗
PubMed2000

Inactivation of interleukin-6 by neutrophil proteases at sites of inflammation. Protective effects of soluble IL-6 receptor chains.

In contrast to the excessively elevated immunochemically detectable concentrations of interleukin-6 (IL-6) in inflammatory exudates, the IL-6 bioactivities are significantly reduced, suggesting an inactivation of IL-6 at sites of inflammation. Since high amounts of proteases are released by invading neutrophils (PMN) in close temporal correlation to elevated IL-6 concentrations at sites of inflammation, this study focused on effects of the PMN-derived proteases elastase (NE), proteinase 3 (PR 3) and cathepsin G (Cat G) on the bioactivity and molecular integrity of IL-6. Here, we demonstrate that these enzymes play a crucial role in the initiation of the degradation and subsequent inactivation of IL-6 at sites of inflammation. Soluble IL-6 receptor subunits elicit a protective effect against the IL-6 inactivation by Cat G, only. Possible consequences of the proteolytical IL-6 inactivation for local inflammatory processes will be discussed.

Acute Disease↗
PubMed2000

Matrix metalloproteinases and TACE play a role in the pathogenesis of endometriosis.

Endometriosis, a benign gynecologic disorder, occurs in about 10% of women in reproductive age and in up to 50% of women with infertility. The basic etiologic factors causing this disease are unknown as yet. Matrix metalloproteinases (MMP) are involved in degradation of the extracellular matrix (ECM). Their proteolytic activity is regulated by tissue inhibitors of metalloproteinases (TIMPs). Tumor necrosis factor-alpha converting enzyme (TACE) is a membrane-bound disintegrin metalloproteinase that processes the membrane-associated cytokine proTNF-alpha to its mature soluble form. TNF-alpha induces the secretion of several MMPs. In order to study the expression of MMP-1, -2, -3 and -9, TIMP-1 and -2, TACE and TNF-alpha in endometrium and endometriotic tissue, we investigated formalin-fixed paraffin sections of endometriotic tissues and normal endometrium with immunohistochemical techniques and in situ hybridisation. Furthermore, quantitative PCR was used for quantification of TACE-mRNA in fresh tissue. We found in this study significant higher protein expression of MMP-1 and TACE and significant lower protein expression of TMP-1 and -2 in endometriotic tissue compared to endometrium. This data may suggest that high TACE expression causes the increased conversion of membrane-bound proTNF-alpha into its soluble form, which stimulates the increased secretion of MMP-1. The simultaneous deficiency of TIMP-1 and -2 in endometriotic tissue suppose an additional proteinase inhibitor imbalance in endometriosis.

ADAM Proteins↗
PubMed2000

Increased expression of extracellular signal-regulated kinase and angiotensin-converting enzyme in human atria during atrial fibrillation.

OBJECTIVES: The purpose of this study was to determine whether atrial expression of the extracellular signal-regulated kinases Erk1/Erk2 and of the angiotensin-converting enzyme (ACE) is altered in patients with atrial fibrillation (AF). BACKGROUND: Recent studies have demonstrated that atrial fibrosis can provide a pathophysiologic substrate for AF. However, the molecular mechanisms responsible for the development of atrial fibrosis are unclear. METHODS: Atrial tissue samples of 43 patients undergoing open heart surgery were examined. Seventeen patients had chronic persistent AF (> or =6 months; CAF), 8 patients had paroxysmal AF (PAF) and 18 patients had no history of AF. Erk expression was analyzed at the mRNA (quantitative reverse transcription polymerase chain reaction), the protein (immunoblot techniques) and atrial tissue (immunohistochemistry) levels. Erk-activating kinases (MEK1/2) and ACE were analyzed by immunoblot techniques. RESULTS: Increased amounts of Erk2-mRNA were found in patients with CAF (75 +/- 20 U vs. sinus rhythm: 31 +/- 25 U; p < 0.05). Activated Erk1/Erk2 and MEK1/2 were increased to more than 150% in patients with AF compared to patients with sinus rhythm. No differences between CAF and PAF were found. The expression of ACE was three-fold increased during CAF. Amounts of activated Erk1/Erk2 were reduced in patients treated with ACE inhibitors. Patients with AF showed an increased expression of Erk1/Erk2 in interstitial cells and marked atrial fibrosis. CONCLUSIONS: An ACE-dependent increase in the amounts of activated Erk1/Erk2 in atrial interstitial cells may contribute as a molecular mechanism for the development of atrial fibrosis in patients with AF. These findings may have important impact on the treatment of AF.

Aged↗