Biomedical subjects

S Ansorge

Publications and source records attributed to S Ansorge.

At least 19 recordsLinked to original sources

PubMed2005

Effects of different anaesthetic agents on immune cell function in vitro.

BACKGROUND AND OBJECTIVE: Anaesthesia may affect the regulatory balance of postoperative immune response. The aim of this study was to investigate the effects of different volatile and non-volatile anaesthetic agents and particularly of clinically used agent combinations on the proliferation capacity and cytokine production of immune cells. METHODS: Peripheral blood mononuclear cells from healthy donors were PHA-activated in the presence or absence of various concentrations of thiopental, propofol, fentanyl, sufentanil, sevoflurane, nitrous oxide and combinations of these anaesthetics. Cell proliferation was assessed by tritiated thymidine uptake. Interleukin-2 production and release of the soluble IL-2 receptor were determined by enzyme immunoassays and used as measures of lymphocyte activation. RESULTS: Thiopental inhibited cell proliferation in a dose dependent manner (P < 0.001) and reduced sIL-2R release (2090-970 microg mL(-1); P < 0.05). Propofol reduced sIL-2R release at the high concentration of 10 microg mL(-1) (2220 pg mL(-1) 1780 microg mL(-1); p < 0.05). Fentanyl and sufentanil did not compensate for or enhance the inhibitory effects of thiopental. Nitrous oxide, but not sevoflurane, reduced the proliferation of human peripheral blood mononuclear cells (P < 0.05). In combinations with thiopental or nitrous oxide, sevoflurane compensated the inhibitory effects of these two agents. Fentanyl, sufentanil, sevoflurane and nitrous oxide did not affect PHA-induced IL-2 and sIL-2 receptor release by human peripheral blood mononuclear cells. CONCLUSION: Thiopental and nitrous oxide have immunosuppressive activity. In contrast, sevoflurane may have a beneficial effect by alleviating the immunosuppressive effects of both substances.

Adult↗

PubMed2004

Simultaneous detection and differentiation of anti-Helicobacter pylori antibodies by flow microparticle immunofluorescence assay.

Helicobacter pylori is the key pathogen for gastroduodenal diseases. The clinical outcome of H. pylori infection is influenced by the presence of strain-specific virulence factors that are usually detected by the presence of specific anti-H. pylori antibodies in serum. Apart from the detection of these antibodies by enzyme-linked immunosorbent assay (ELISA), it is desirable to obtain additional information concerning the presence of certain virulence factors of H. pylori that are currently detected by immunoblot analysis. At present, the immunodiagnosis of an H. pylori infection includes two separate methods: ELISA and immunoblot analysis. Here, we report the development and evaluation of a new rapid flow microparticle immunofluorescence assay (FMIA) for detection of anti-H. pylori antibodies in human serum. The assay allows rapid qualitative and quantitative detection of anti-H. pylori antibodies by using crude antigen preparations as well as single recombinant antigens (urease A, urease B, CagA, and alkylhydroxy peroxide reductase) in the same sample with one measurement, and thus it combines the advantages of enzyme immunoassay and Western blot analysis. Seventy-five patient samples were analyzed by FMIA, ELISA, and Western blotting with respect to their immunoreactivity against crude H. pylori extracts and individual H. pylori antigens. Statistical analyses revealed an overall similarity of more than 90% among the results for FMIA, ELISA, and Western blot. Therefore, we conclude that FMIA is a powerful and time- and cost-saving assay system for the detection of antimicrobial antibodies, with higher sensitivity and a larger measurement range than ELISA.

Antibodies, Bacterial↗

PubMed2003

Pretreatment with interleukin-2 modulates perioperative immunodysfunction in patients with renal cell carcinoma.

Complex perioperative immunodysfunction occurs in patients with renal cell carcinoma undergoing nephrectomy. Here, the effect of pretreatment with IL-2 is addressed. Of 63 patients who underwent tumour nephrectomy, 26 patients received four doses of 10 Mio IE/m2 IL-2 b.d. s.c. (i.e. a total of 40 Mio IE/m2) a week before operation, 37 did not. Parameters of cellular and humoral immunity (differential blood count, T-cell markers CD2, CD3, CD4, and CD8, B-cell markers CD19 and CD20, monocyte markers CD13 and CD14, NK-cell marker CD16, activation markers CD25, CD26, CD69 and HLA-DR, and cytokines IL-1-receptor antagonist (IL-1RA), IL-2, soluble IL-2-receptor (sIL-2R), IL-6, IL-10, and TGFbeta) were measured in peripheral venous blood. Blood was drawn before IL-2, one day before and immediately after the operation, and on the 1st, 3rd, 5th, and 10th postoperative day. All patients showed postoperatively elevated leukocyte and granulocyte counts, and elevated serum levels of cytokines IL-6 and IL-10. T-cell and activation markers were decreased. However, all these alterations were less accentuated in patients who had been pretreated with IL-2. Monocyte counts and IL-2 and TGFbeta levels were decreased, but IL-1RA and sIL-2R levels were elevated in pretreated patients. IL-2-related toxicity was WHO grade I-II in all patients, grade III in one patient. The anaesthetic regimen had no measurable effect. IL-6 concentrations were higher in renal venous than in venous pool blood, indicating IL-6 production in the tumour in vivo. Tumour-specific survival was better in pretreated patients with tumours extending beyond the kidney. Pretreatment with IL-2 modulates perioperative immunodysfunction in patients undergoing tumour nephrectomy. This affects in particular T-cell-mediated immunity and levels of cytokines IL-10 and IL-6. The IL-2 application scheme used here was followed by distinct counter regulation including monocytes, IL-2, sIL-2R, IL-1RA and TGFbeta. Taken together, pretreatment with IL-2 may complement surgery in the treatment of patients with renal cell carcinoma, and may help close the therapeutic gap between neo-adjuvant and adjuvant immunotherapy.

Adult↗

PubMed2002

Pretreatment with interleukin-2 modulates peri-operative immuno-dysfunction in patients with renal cell carcinoma.

OBJECTIVE: Complex peri-operative immuno-dysfunction occurs in patients with renal cell carcinoma undergoing nephrectomy. Here, the effect of pretreatment with interleukin-2 (IL-2) is addressed. METHODS: Of 63 patients who underwent tumor nephrectomy, 26 patients received 4 doses of 10 Mio IE/m(2) IL-2 b.d. s.c. (i.e. a total of 40 Mio IE/m(2)) a week before operation, 37 did not. Parameters of cellular and humoral immunity (differential blood count, T-cell markers CD2, CD3, CD4, and CD8, B-cell markers CD19 and CD20, monocyte markers CD13 and CD14, NK (natural killer)-cell marker CD16, activation markers CD25, CD26, CD69, and HLA-DR, and cytokines IL-1-receptor antagonist (IL-1RA), IL-2, soluble IL-2-receptor (sIL-2R), IL-6, IL-10, and TGFbeta) were measured in venous blood. Blood was drawn before IL-2, 1 day before and immediately after the operation, and on the 1st, 3rd, 5th, and 10th postoperative day. RESULTS: All patients showed postoperatively elevated leukocyte and granulocyte counts, and elevated serum levels of cytokines IL-6 and IL-10. T-cell and activation markers were decreased. However, all these alterations were less accentuated in patients who had been pretreated with IL-2. Monocyte counts and IL-2 and TGFbeta levels were decreased, but IL-1RA and sIL-2R levels were elevated in pretreated patients. IL-2 related toxicity was WHO grades I-II in all patients, grade III in one patient. The anesthetic regimen had no measurable effect. IL-6 concentrations were higher in renal venous than in venous pool blood, indicating IL-6 production in the tumor in vivo. CONCLUSIONS: Pretreatment with IL-2 modulates peri-operative immuno-dysfunction in patients undergoing tumor nephrectomy. This affects in particular T-cell-mediated immunity and levels of cytokines IL-10 and IL-6. The IL-2 administration scheme used here was followed by distinct counter-regulation including monocytes, IL-2, sIL-2R, IL-1RA and TGFbeta.

Adult↗

PubMed2001

Targeting dipeptidyl peptidase IV (CD26) suppresses autoimmune encephalomyelitis and up-regulates TGF-beta 1 secretion in vivo.

CD26 or dipeptidyl peptidase IV (DP IV) is expressed on various cell types, including T cells. Although T cells can receive activating signals via CD26, the physiological role of CD26/DP IV is largely unknown. We used the reversible DP IV inhibitor Lys[Z(NO(2))]-pyrrolidide (I40) to dissect the role of DP IV in experimental autoimmune encephalomyelitis (EAE) and to explore the therapeutic potential of DP IV inhibition for autoimmunity. I40 administration in vivo decreased and delayed clinical and neuropathological signs of adoptive transfer EAE. I40 blocked DP IV activity in vivo and increased the secretion of the immunosuppressive cytokine TGF-beta1 in spinal cord tissue and plasma during acute EAE. In vitro, while suppressing autoreactive T cell proliferation and TNF-alpha production, I40 consistently up-regulated TGF-beta1 secretion. A neutralizing anti-TGF-beta1 Ab blocked the inhibitory effect of I40 on T cell proliferation to myelin Ag. DP IV inhibition in vivo was not generally immunosuppressive, neither eliminating encephalitogenic T cells nor inhibiting T cell priming. These data suggest that DP IV inhibition represents a novel and specific therapeutic approach protecting from autoimmune disease by a mechanism that includes an active TGF-beta1-mediated antiinflammatory effect at the site of pathology.

Animals↗

PubMed2001

Cathepsin K--a marker of macrophage differentiation?

Cathepsin K is a cysteine protease with high matrix-degrading activity. Initially, cathepsin K was described as being expressed exclusively by osteoclasts. It was suggested that cathepsin K expression is a specific feature of cells involved in bone remodelling. The aim of this study was to investigate the hypothesis that cathepsin K is expressed not only in bone-resorbing macrophages, but also more generally in specifically differentiated macrophages, such as epithelioid cells and multinucleated giant cells in soft tissues. Specimens obtained from different organs and anatomical locations of patients suffering from sarcoidosis, tuberculosis, granulomas caused by foreign materials, and sarcoid-like lesions were investigated for the expression of cathepsins B, K, and L. Immunohistochemistry and in situ hybridization showed cathepsin K in epithelioid cells and multinucleated giant cells irrespective of the pathological condition and anatomical location, but not in normal resident macrophages. By immunoelectron microscopy, cathepsin K was discovered in cytoplasmic granules of multinucleated giant cells. In contrast, cathepsin B and cathepsin L were expressed ubiquitously in CD68-positive tissue macrophages, epithelioid cells, and multinucleated giant cells. The results demonstrate that cathepsin K, but not cathepsin B or cathepsin L, differentiates specific phenotypes of macrophages independently of the anatomical site. Its enzymatic characteristics, particularly its high matrix-degrading activity, suggest that cathepsin K-positive epithelioid cells and multinucleated giant cells are characterized by an enhanced specific proteolytic capability.

Adult↗

PubMed2001

Expression and activity of ectopeptidases in fibrillating human atria.

Recent studies have demonstrated that atrial fibrillation (AF) occurs in the presence of degenerative changes of atrial tissue. In contrast, bradykinin (BK) appears to have cardioprotective effects diminishing myocardial hypertrophy and fibrosis. It is unknown, however, whether AF has direct effects on BK metabolism. Therefore, the purpose of this study was to determine the atrial expression of the membrane-bound peptidases, also referred to as ectopeptidases, carboxypeptidase M (CPM), dipeptidyl peptidase IV (DPIV), and alanyl-aminopeptidase (APN) in patients with and without AF. Atrial tissue samples of 35 patients undergoing open heart surgery were examined. Seventeen patients had chronic persistent AF (> or = 6 months; CAF), the remaining 18 patients (controls) had no history of AF. Peptidase expression was analyzed at the mRNA (quantitative RT-PCR) level and apparent changes were confirmed at the protein level. In case of unaltered mRNA levels, enzyme activity was determined. Reduced amounts of CPM-mRNA were found in patients with CAF (41.3+/-9.7 U nu controls: 86.1+/-17.5 U P<0.05). CPM protein was decreased to 47.5% in patients with CAF compared with controls (P<0.01). DPIV and APN mRNA amounts were similar in both groups. DPIV activity, however, was increased during CAF (219.6+/-30 pkat/mg protein v controls: 195.8+/-21.8 pkat/mg P<0.05). APN activity was unchanged. In conclusion, atrial bradykinin metabolizing activities are significantly altered during AF in humans. The observed alterations in ectopeptidase expression/activity may play a role in the structural remodeling of fibrillating atria.

Atrial Fibrillation↗

PubMed2001

A putative role for cathepsin K in degradation of AA and AL amyloidosis.

The aims of this study were to investigate the role of cathepsin K in the pathology of amyloidosis by demonstrating its presence in multinucleated giant cells (MGCs) adjacent to amyloid deposits, and determining its ability to degrade amyloid fibril proteins in vitro. The study was performed using autopsy and biopsy specimens from patients with AA or AL amyloidosis. In six (55%) patients with AA amyloidosis and seven (58%) patients with AL amyloidosis, variable numbers of CD68-immunoreactive MGCs were found adjacent to amyloid deposits. In each case strong cytoplasmic immunostaining for cathepsin K was found in MGCs; immunostaining of amyloid deposits was present in five (45%) patients with AA amyloidosis and three (25%) patients with AL amyloidosis. In vitro degradation experiments showed that recombinant cathepsin K completely degraded AA amyloid fibril proteins at pH 5.5 as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. Less effective degradation took place at pH 7.4 and there was no degradation in the presence of a general cysteine protease inhibitor (E64) or in the absence of cathepsin K. This is the first study to show that cathepsin K is expressed in MGCs adjacent to amyloid deposits and to demonstrate its ability to degrade amyloid fibril proteins.

Adult↗

PubMed2001

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.

Animals↗

PubMed2001

Restoration of the cellular thiol status of peritoneal macrophages from CAPD patients by the flavonoids silibinin and silymarin.

During continuous ambulatory peritoneal dialysis (CAPD) the peritoneal immune cells, mainly macrophages, are highly compromised by multiple factors including oxidative stress, resulting in a loss of functional activity. One reason for the increase of inflammatory reactions could be an imbalance in the thiol-disulfide status. Here, the possible protective effects of the antioxidant flavonoid complex silymarin and its major component silibinin on the cellular thiol status were investigated. Peritoneal macrophages from dialysis fluid of 30 CAPD patients were treated with silymarin or silibinin up to 35 days. A time-dependent increase of intracellular thiols was observed with a nearly linear increment up to 2.5-fold after 96 hours, reaching a maximum of 3.5-fold after 20 days of culture. Surface-located thiols were also elevated. The stabilization of the cellular thiol status was followed by an improvement of phagocytosis and the degree of maturation as well as significant changes in the synthesis of IL-6 and IL-1ra. Furthermore, the treatment of peritoneal macrophages with flavonoids in combination with cysteine donors resulted in a shortened and more efficient time course of thiol normalization as well as in a further increased phagocytosis. In addition, GSH-depletion in thiol-deficient media simulating CAPD procedures led to intracellular thiol deficiency similar to the in vivo situation. It is concluded that treatment with milk thistle extracts silymarin and silibinin alone or, more effectively in combination with cysteine donors, provide a benefit for peritoneal macrophages of CAPD-patients due to a normalization and activation of the cellular thiol status followed by a restoration of specific functional capabilities.

Acetylcysteine↗

PubMed2001

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.

Cathepsin B↗

PubMed2001

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.

Antioxidants↗

PubMed2001

More than destructive: neutrophil-derived serine proteases in cytokine bioactivity control.

In addition to the mechanisms inducing the expression and secretion of cytokines under distinct pathophysiological conditions, the fate of cytokines after secretion at sites of inflammation is a field of growing interest. Proteolysis has been suggested to be a fundamental mechanism of regulating the activities of various components of the cytokine network. Evidence grows that besides highly specific cytokine converting proteases such as interleukin-1beta-converting enzyme or tumor necrosis factor-converting enzyme, neutrophil-derived serine proteases are intimately involved in the modulation of the activities of cytokines and their receptors. Particularly at sites of inflammation, high amounts of the active serine proteases elastase, cathepsin G, and proteinase 3 are released from infiltrating polymorphonuclear cells in close temporal correlation to elevated levels of inflammatory cytokines, strongly indicating that these proteases are involved in the control of cytokine bioactivity and availability.

Cytokines↗

PubMed2001

Complex perioperative immuno-dysfunction in patients with renal cell carcinoma.

PURPOSE: Patients with renal cell carcinoma have an impaired function of the immune system, which is the basis for different approaches of immunotherapy. We address perioperative changes of several parameters of the immune system in these patients. MATERIALS AND METHODS: Parameters of cellular and humoral immunity, including differential blood count, T cell markers CD2, 3, 4 and 8, B cell markers CD19 and 20, monocyte markers CD13 and 14, natural killer cell marker CD16, activation markers CD25, CD26 and HLA-DR, and cytokines interleukin-1 (IL-1) receptor antagonist, IL-2, soluble IL-2 receptor, IL-6, IL-10 and transforming growth factor-beta, were measured in the venous blood of patients who underwent renal surgery extracorporeal shock wave lithotripsy (ESWL, Dornier Medical Systems, Inc., Marietta, Georgia). Patients were grouped and age matched, and 37 underwent tumor nephrectomy, 20 open renal surgery for nonmalignant reasons and 24 ESWL. A group consisting of 39 controls received no treatment. RESULTS: Little change was detected in controls and those patients who received ESWL. Patients who underwent open renal surgery had increased leukocyte and granulocyte counts until postoperative day 3 but had low T cell counts. The postoperative decrease in CD25 expressing cells corresponded to an increase in the soluble IL-2-receptor. Cytokines IL-6 and 10, which also have immunosuppressive properties, were markedly increased postoperatively. These changes were more noted (p <0.01) in those patients who underwent tumor nephrectomy than open renal surgery for nonmalignant reasons and remained detectable when paired patients with similar surgical trauma were compared. In tumor nephrectomy cases renal venous IL-6 was higher than peripheral venous levels. CONCLUSIONS: Patients with renal cell carcinoma suffer from selective immuno-dysfunction, indicating a rationale for perioperative immunomodulation.

Adult↗

PubMed2000

Dipeptidyl peptidase IV (DP IV/CD26) mRNA expression in PWM-stimulated T-cells is suppressed by specific DP IV inhibition, an effect mediated by TGF-beta(1).

Stimulation of human T-cells by pokeweed mitogen (PWM) results in a significant increase of IL-2, IFN-gamma, and DP IV mRNA expression as analyzed by quantitative RT-PCR. Here we show for the first time that the changes observed in cytokine mRNA expression are dose-dependently suppressed by the specific dipeptidyl peptidase IV inhibitor Lys[Z(NO(2))]-thiazolidide. Most interestingly, the inhibition of DP IV activity leads to a decrease in mRNA expression of the enzyme itself. Furthermore, evidence is provided that this suppression is mediated by TGF-beta(1). The presented data fit into the hypothesis that inhibition of DP IV leads to the induction of TGF-beta(1), which in turn provokes an arrest of cell cycle in late G(1).

Antibodies↗

PubMed2000

Down-regulation of T cell activation following inhibition of dipeptidyl peptidase IV/CD26 by the N-terminal part of the thromboxane A2 receptor.

Using synthetic inhibitors, it has been shown that the ectopeptidase dipeptidyl peptidase IV (DP IV) (CD26) plays an important role in the activation and proliferation of T lymphocytes. The human immunodeficiency virus-1 Tat protein, as well as the N-terminal nonapeptide Tat(1-9) and other peptides containing the N-terminal sequence XXP, also inhibit DP IV and therefore T cell activation. Studying the effect of amino acid exchanges in the N-terminal three positions of the Tat(1-9) sequence, we found that tryptophan in position 2 strongly improves DP IV inhibition. NMR spectroscopy and molecular modeling show that the effect of Trp(2)-Tat(1-9) could not be explained by significant alterations in the backbone structure and suggest that tryptophan enters favorable interactions with DP IV. Data base searches revealed the thromboxane A2 receptor (TXA2-R) as a membrane protein extracellularly exposing N-terminal MWP. TXA2-R is expressed within the immune system on antigen-presenting cells, namely monocytes. The N-terminal nonapeptide of TXA2-R, TXA2-R(1-9), inhibits DP IV and DNA synthesis and IL-2 production of tetanus toxoid-stimulated peripheral blood mononuclear cells. Moreover, TXA2-R(1-9) induces the production of the immunosuppressive cytokine transforming growth factor-beta1. These data suggest that the N-terminal part of TXA2-R is an endogenous inhibitory ligand of DP IV and may modulate T cell activation via DP IV/CD26 inhibition.

Dipeptidyl Peptidase 4↗

PubMed2000

Inhibition of alanyl-aminopeptidase suppresses the activation-dependent induction of glycogen synthase kinase-3beta (GSK-3beta) in human T cells.

Inhibition of alanyl-aminopeptidase (APN, CD13) gene expression or enzymatic activity compromises T cell proliferation and function. Molecular mechanisms mediating these effects are not known as yet. Recently, we found the expression of the proto-oncogen Wnt-5a to be strongly affected by APN-inhibition. Wnt-5a and other members of the Wnt family of secreted factors are implicated in cell growth and differentiation. Here, we analyzed by quantitative RT-PCR and immunoblotting the expression in mitogen-activated T cells of a major constituent of the Wnt-5a pathway, glycogen synthase kinase-3beta (GSK-3beta). T cell activation by phytohaemagglutinin or pokeweed mitogen results in a strong increase of GSK-3beta mRNA amounts. At the protein level, we observed an up-regulation of both GSK-3beta and phosphorylated GSK-3beta. This induction-dependent increase of GSK-3beta is markedly reduced in response to inhibitors of alanyl-aminopeptidase, actinonin, leuhistin, and RB3014. These findings may provide a rational for the growth inhibition resulting from a diminished expression or activity of alanyl aminopeptidase.

Amino Acids↗

PubMed2000

Regulation of angiotensin II receptor subtypes during atrial fibrillation in humans.

BACKGROUND: Previous studies have suggested that atrial fibrillation (AF) is associated with the activation of the atrial angiotensin system. However, it is not known whether the expression of angiotensin II receptors changes during AF. The purpose of this study was to determine the atrial expression of angiotensin II type 1 and type 2 receptors (AT(1)-R and AT(2)-R) in patients with AF. METHODS AND RESULTS: Atrial tissue samples from 30 patients undergoing open heart surgery were examined. Eleven patients had chronic persistent AF (> or =6 months; cAF), 8 patients had paroxysmal AF (pAF), and 11 patients were in sinus rhythm. AT(1)-R and AT(2)-R were localized in the atrial tissue by immunohistochemistry and quantified at the protein and mRNA level by Western blotting and quantitative polymerase chain reaction. Both types of AT-R were predominantly expressed in atrial myocytes in all groups. The amount of AT(1)-R was reduced to 34.9% during cAF (P<0.01) and to 51.7% during pAF (P<0.05) compared with patients in sinus rhythm. In contrast, AT(2)-R was increased during cAF (246%; P=NS) and pAF (505%; P<0.01). AT(1)-R/AT(2)-R mRNA content was similar in all groups. CONCLUSIONS: AF is associated with the down-regulation of atrial AT(1)-R and the up-regulation of AT(2)-R proteins. These findings may help define the pathophysiological role of the angiotensin system in the structural remodeling of the fibrillating atria.

Adult↗