The activation-dependent induction of APN-(CD13) in T-cells is controlled at different levels of gene expression.

Recently, it was shown that aminopeptidase N (E.C. 3.4.11.2, CD13) is up-regulated during mitogenic stimulation of peripheral T-cells. In this study, we demonstrate that the half-life of APN mRNA was considerably prolonged in these cells leading to a 2.7-fold increase of APN transcript level. The apparent half-life time of the APN transcript was investigated by the RNA synthesis inhibitor-chase method using actinomycin D. The steady-state APN mRNA levels was determined by a competitive RT-PCR. The half-lives estimated in resting T-cells, natural killer cells and permanently growing tumour cells varied between 3.5 and 6 h. Finally, nuclear run-on assays revealed that the APN gene expression of stimulated T-cells is controlled by increased promoter activity as well. These studies suggest a control of APN gene expression at the post-transcriptional level in addition to promoter-mediated regulation.

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.

Interleukin-6 and transforming growth factor-beta 1 control expression of cathepsins B and L in human lung epithelial cells.

Cathepsins B and L are commonly expressed cysteine proteinases that play a major role in lysosomal bulk proteolysis, protein processing, matrix degradation, and tissue remodeling. Cathepsins are also implicated in tumor progression and metastasis, tissue injury, and inflammation. Cells at sites of inflammation often show upregulation and secretion of cathepsins. The regulation of cathepsin expression by inflammatory mediators is not well understood. The aims of this study were to investigate the effect of the cytokines interleukin-1 beta (IL-1 beta), IL-6, IL-10, transforming growth factor-beta 1 (TGF-beta 1), and hepatocyte growth factor (HGF) on expression of cathepsin B and cathepsin L mRNA (quantitative RT-PCR), on protein expression (ELISA, Western blot), and also on enzymatic activity of cathepsins B and L. Investigations were performed using the human lung epithelial cell line A-549. IL-6 was found to induce a concentration-dependent increase in mRNA expression, protein concentration, and enzymatic activity of cathepsin L. Cathepsin B mRNA and protein expression were not affected by IL-6. In contrast, TGF-beta 1 decreased the amount of cathepsin L mRNA and cathepsin B mRNA. At protein level, it was shown that TGF-beta 1 clearly reduced the concentration of cathepsin L but not cathepsin B. The cytokines IL-1 beta, IL-10, and HGF were found to exert no effect on cathepsin B and L expression. In conclusion, these results are the first to show that IL-6 and TGF-beta 1 have opposite effects on the regulation of expression of cathepsins B and L in A-549 human lung epithelial cells. The proinflammatory cytokine IL-6 induced an upregulation of cathepsin L, whereas TGF-beta 1 suppressed cathepsin B and L expression. Further studies are needed to clarify the mechanism that affects cathepsin B and L expression.

Transforming growth factor beta 1 inhibits interleukin-10 mRNA expression and production in pokeweed mitogen-stimulated peripheral blood mononuclear cells and T cells.

The multifunctional cytokine transforming growth factor-beta 1 (TGF-beta 1) is known to inhibit the proliferation of lymphocytes. Whether this effect is a result of a direct action of TGF-beta 1 or an involvement of other "immunoinhibitory" cytokines is not yet clear. Here we have analyzed the effects of TGF-beta 1 on IL-10 and IL-1RA production in pokeweed mitogen-stimulated peripheral blood mononuclear cells (PBMC) and purified T lymphocytes. We show in these systems that TGF-beta 1 at a concentration of 10 ng/ml significantly suppresses both IL-10 mRNA expression and IL-10 production. IL-2 and IL-6 were capable of abolishing the effect of TGF-beta 1 on DNA synthesis and production of IL-10 by T lymphocytes in an additive manner. However, TGF-beta 1 did not influence IL-1RA production in PWM-stimulated PBMC. The present data show that the inhibitory effect of TGF-beta 1 on mitogen-activated immune cells is not the consequence of induction of the inhibitory cytokines IL-10 or IL-1RA but rather an inhibitory action on the production of IL-2 and/or IL-6.

Increased release of transforming growth factor (TGF)-beta1, TGF-beta2, and chemoattractant mediators in pneumonia.

Transforming growth factor-beta (TGF-beta), interleukin-8 (IL-8), and leukotrienes are potent neutrophil chemoattractants that are released in several lung diseases. There is limited information about the release of TGF-beta in bronchoalveolar lavage fluid (BALF) of patients with pneumonia. Furthermore, it is not clear if TGF-beta is differentially expressed in different lung diseases. The aim of our study was to compare the concentrations of TGF-beta1 and TGF-beta2 in the BALF of patients with pneumonia and other lung diseases. Furthermore, correlation of the TGF-beta levels with the concentration of chemoattractant mediators as well as with indicators of macrophage and granulocyte activation should be investigated. Patients with pneumonia, interstitial lung disease (ILD), or chronic obstructive pulmonary diseases (COPD) were included. Patients with ischemic heart disease without pulmonary involvement served as controls. The concentrations of TGF-beta1 and TGF-beta2, of the chemoattractant cytokine IL-8, of leukotriene B4, and of the leukotrienes C4, D4, and E4 were measured. Neutrophil elastase and granulocyte content (PMN) were used as markers for granulocyte activation, and neopterin was used as a marker for the activation of macrophages. Significantly elevated levels of TGF-beta1 (mean = 0.216 ng/ml, p < 0.01) were found in patients with microbiologically positive pneumonia but not in patients with ILD or COPD. A significant (p < 0.001) correlation was found between the TGF-beta1 concentrations and the IL-8 levels and the percentage of granulocytes (r = 0.76, and r = 0.44, respectively). Elevated TGF-beta2 concentrations were measured in the BALF of patients with pneumonia (mean = 1.4 ng/ml, p < 0.01) and with ILD. Pneumonia was also associated with increased concentrations of leukotrienes C4, D4, and E4 (mean = 91.61 pg/ml, p < 0.05) and leukotriene B4 (mean = 203.9 pg/ml, p < 0.01), significantly elevated levels of PMN elastase (mean = 2958.26 ng/ml, p < 0.01), and neopterin (mean = 0.42 nmol/L). Our results strongly suggest that different lung diseases do differ with regard to the released cytokines. TGF-beta1 probably plays a key role in regulation of pulmonary inflammation, particularly in pneumonia.

A detailed protocol for the measurement of TGF-beta1 in human blood samples.

Quantification of the multifunctional cytokine Transforming Growth Factor-beta1 (TGF-beta1) in blood samples has aroused increasing interest in recent years, since an abnormal regulation of this cytokine appears to play a key role in the pathogenesis of different diseases, such as autoimmundiseases or malignant tumors. The measurement of TGF-beta1 is complicated by a lot of problems concerning the collection, preparation and handling of blood samples, the platelet contamination, and the TGF-beta1 activation procedure. Here, we recommend detailed instructions for measurement of TGF-beta1 in blood plasma samples which should be followed to exclude the determination of false positive or negative results.

Functional role of CD26 on human B lymphocytes.

CD26 is a well-known activation marker on T cells and natural killer (NK) cells [1]. It is identical with the ectopeptidase dipeptidyl peptidase IV (DP IV). The expression of CD26 on B cells has been discussed controversially [2,3]. We have studied the expression of this enzyme on B cells from the peripheral blood of healthy donors and of CVID patients, on cells of the Daudi Burkitt line and the EBV-transformed B-cell lines Jojo and Laz509. DP IV was detected by using anti-CD26 monoclonal antibodies and with help of specific enzyme substrates. Further the influence of specific synthetic DP IV inhibitors on mitogenic activation of purified B cells and DNA synthesis of cell lines was studied. We could show that in both groups 0-5% of freshly isolated CD20-positive B cells do express the CD26 antigen. After stimulation with pokeweed mitogen or St. aureus protein, the fraction of CD26-positive cells was enhanced up to 51% and 36%, respectively. Interestingly, induction of CD26 expression on B cells from CVID patients occurs in a manner similar to the B cells from healthy donors. Treatment of peripheral blood B cells and B-cell lines with highly specific competitive DP IV inhibitors leads to a significant inhibition of DNA synthesis in a dose-dependent manner. These data show that CD26 can be considered to be an activation marker not only of T- and NK cells but also of a main population of B cells, suggesting an involvement of CD26 in B-cell activation.

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.

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.

Inhibitors of dipeptidyl peptidase IV (DP IV, CD26) specifically suppress proliferation and modulate cytokine production of strongly CD26 expressing U937 cells.

Various studies from different laboratories have shown that the membrane ectoenzyme dipeptidyl peptidase IV (DP IV, CD26) expressed in T and NK cells is involved in the regulation of DNA synthesis and cytokine production. In this paper, we performed a biochemical and functional characterization of dipeptidyl peptidase IV on the human histiocytic lymphoma cell line U937. Using U937 clones expressing low to high levels of membrane localized CD26, we found that the synthetic reversible inhibitors of DP IV, Lys-[Z(NO2)]-thiazolidide and Lys-[Z(NO2)]-piperidide, have different effects on all functions. In U937-H cells that strongly express high levels of CD26, DP IV inhibitors were shown to suppress DNA synthesis and production of IL-1 beta, but stimulate the secretion of the IL-1 receptor antagonist (IL-1RA) and of TNF-alpha. In contrast, both inhibitors did not influence the cytokine production and DNA synthesis in U937-L cells exhibiting low level CD26 expression. These data support the hypothesis that CD26 plays a crucial role in proliferation and cytokine production, not only in T cells, but also in other cell systems, and that enzymatic activity is essential for its function.

Dipeptidyl peptidase IV (CD26) on human lymphocytes. Synthetic inhibitors of and antibodies against dipeptidyl peptidase IV suppress the proliferation of pokeweed mitogen-stimulated peripheral blood mononuclear cells, and IL-2 and IL-6 production.

In the present report, we describe that synthetic inhibitors of and polyclonal and monoclonal antibodies against the membrane ectoenzyme dipeptidyl peptidase IV (DP IV, CD26) inhibit the production of IL-2 and IL-6 and, concomitantly, DNA synthesis of pokeweed mitogen-stimulated peripheral blood mononuclear cells (PBMC). The release of IL-1 and TNF-alpha, was not influenced under these conditions. The data support the hypothesis that DP IV, possibly in conjunction with other peptidase, is involved in the regulation of activation and proliferation of T lymphocytes.

CD26 mediates the action of HIV-1 Tat protein on DNA synthesis and cytokine production in U937 cells.

The human immunodeficiency virus 1 (HIV-1) Tat protein is known to be capable of suppressing antigen- and CD3-induced activation of human T cells. Previously, it was shown that Tat can bind to the dipeptidyl peptidase IV (DP IV, CD26) and inhibit the degradation of the chromogenic substrate Gly-Pro-p-nitroanilide. Using the method of free zone capillary electrophoresis, here we have shown that the DP IV-catalyzed hydrolysis of the NH2-X-Pro-containing cytokine peptides IL-2(1-12), IL-1 beta(1-6), and IL-6(1-12) was also significantly inhibited by the Tat protein. Moreover, HIV-1 Tat at a concentration of 10 micrograms/ml was found to have a strong suppressive effect on DNA synthesis and IL-1 beta production, but stimulates secretion of IL-1 receptor antagonist (IL-1RA) and TNF-alpha of CD26-expressing U937-H cells. It did not impair neither DNA synthesis nor cytokine production of low CD26-expressing U937-L cells. Similar results have been found with synthetic DP IV/CD26 inhibitors (Immunobiol., 1994, vol. 192, pp. 121-136). These data strongly suggest that Tat protein is a potent "natural" inhibitor of DP IV/CD26, and they support the hypothesis that DPIV plays a role in Tat's immunosuppressive activity.

Antioxidant and antiprotease status in peripheral blood and BAL fluid after cardiopulmonary bypass.

OBJECTIVE: Cardiopulmonary bypass (CPB) triggers systemic inflammation. Recent evidence suggests that metabolic and oxygenation management can affect the outcome of patients after cardiac surgery. We investigated the influence of oxidant/antioxidant and protease/antiprotease imbalance during the course of systemic and pulmonary inflammation. METHODS: In a study of 61 patients, we measured the intracellular thiol concentration, the intracellular activity of cathepsins and elastase, and the concentrations of secreted elastase, soluble alpha(1)-proteinase inhibitor (alpha(1)-PI), and secretory leukoprotease inhibitor (SLPI). Peripheral blood and BAL fluid (BALF) were obtained preoperatively and 2 h after CPB. RESULTS: A post-CPB depletion of thiol was found in blood granulocytes, lymphocytes, and monocytes, as well as BALF lymphocytes and macrophages. The degree of postoperative depletion correlated with PO(2) and blood glucose levels during CPB. Concomitant reduction of FEV(1) showed positive correlation with thiol depletion of blood monocytes and granulocytes. Elastase and cathepsin activities were increased in blood cells but not in lymphocytes or macrophages from BALF. The concentrations of secreted elastase were significantly increased in blood plasma but not in BALF. Enhanced antiprotease (alpha(1)-PI, SLPI) concentrations were measured in BALF but not in peripheral blood. CONCLUSIONS: The inflammatory response of the intra-alveolar compartment is clearly distinguishable from systemic inflammation. CPB causes a differentiated impairment of the antioxidant defense system as well as a protease/antiprotease imbalance in blood and BALF. Oxygenation under circumstances of CPB and concomitant pulmonary disease, as well as blood glucose metabolism, influence the antioxidative defense. Individual perioperative management of blood glucose and oxygenation could improve cellular defense systems in the peripheral blood and BALF and therefore result in a more favorable patient outcome.

Disposable TSM-biosensor based on viscosity changes of the contacting medium.

The thickness shear mode (TSM)-sensor responds to changes of mechanical properties of the material contacting the surface of the sensor. One of the material properties is the viscosity of a liquid. Abiosensor based on the TSM-resonator for the detection of endotoxin has been developed. It exploits the viscosity-density change during the reaction of endotoxin with limulus amebocyte lysate (LAL). The effect of surface properties of the sensor has been investigated to achieve better output signals. It is shown that the sensor requires a hydrophilic surface to get a better coupling between the sensor and the LAL-endotoxin solution. The TSM biosensor is able to detect an endotoxin concentration as low as 100 fg/ml by using only 50-microl standard LAL solution. The disadvantages of reusable sensors, such as the contamination from previous measurement of endotoxin and the cost of the regeneration or reclining processes of the sensor, have been eliminated by using a cost effective disposable TSM-sensor.

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.

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.

CD26/dipeptidyl peptidase IV in lymphocyte growth regulation.

DP IV/CD26 is involved in regulation of DNA synthesis and proliferation as well as production of cytokines of hematopoietic cells under various conditions. Inhibition of DNA synthesis in T lymphocytes, B lymphocytes, NK cells and myelomonocytic cells as well as of the production of IL-2, IL-6 TNF alpha, IL-1, IL-10, IL-12, IL-13, IFN-gamma, GM-CSF are not due to apoptosis of these cells. DP IV/CD26 inhibitors induce TGF-beta 1 mRNA synthesis and latent protein release demonstrating a crucial role of TGF-beta 1 in mediating CD26 function. X-X-Pro peptides as HIV-Tat protein strongly inhibit DP IV enzymatic activity and suppress DNA synthesis. This group of peptides may represent a class of natural DP IV/CD26 ligands and effectors, respectively. Hyperphosphorylation of p56lck as well as protein tyrosine phosphorylation of a number of proteins in T lymphocytes can be modulated by DP IV inhibitors. These data suggest that enzymatic activity or, at least in part, the active site of DP IV are both essential for its regulatory function in lymphocytes. Further work is required to determine the natural ligands, i.e. substrates and effectors, which are play the central role in DP IV/CD26 action in T cell growth and to understand the molecular mechanism of the early steps of this fundamental process.

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.

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.