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C J Wiedermann

Publications and source records attributed to C J Wiedermann.

At least 55 records · Page 3Linked to original sources
PubMed1999

A soluble gradient of the neuropeptide secretoneurin promotes the transendothelial migration of monocytes in vitro.

Secretoneurin, derived from the chromogranin secretogranin II, triggers the selective migration of human monocytes, eosinophils, fibroblasts, endothelial and smooth muscle cells. More recently, we located specific binding sites on the human monocytic cell line MonoMac-6. Differentiated U937 transendothelial diapedesis was evaluated using an in vitro model of the vascular wall and specific monoclonal antibodies against CD11/CD18 and the alpha-chains of the very late activation antigen (VLA)-4 were used to evaluate involved adhesion molecules. Results showed a significant migratory response to secretoneurin between 10(-8) to 10(-10) M. Migration was comparable to a maximal effect induced by the monocyte chemotactic agent N-formyl-Met-Leu-Phe (fMLP, 10(-8) M). Rabbit anti-secretoneurin antibodies were able to block the neuropeptide effect but not of fMLP and a trypsinized secretoneurin preparation as well as the secretogranin II-fragment EL-17 were ineffective in eliciting migration. Transmigration of U937 across endothelial-layers toward secretoneurin is inhibited by antibodies to CD11/CD18 adhesion molecules. The novel neuropeptide secretoneurin may play a role in regulating migration of monocytes into the subendothelial space, supposing a role in inflammatory responses.

Animals↗
PubMed1999

Mediator-dependent effects of pentoxifylline on endothelium for transmigration of neutrophils.

In the present study, we investigated the effects of the anti-inflammatory drug pentoxifylline (PTX) on activation of endothelial cells for enhanced adhesion and transmigration of neutrophils by lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF), interleukin-1 (IL-1) and granulocyte colony-stimulating factor (G-CSF). To evaluate the mechanism by which PTX exerts its effect, human umbilical vein endothelial cells (HUVEC) were pretreated with theophylline, 2'-O-dibutyryl-3', 5'-cyclic adenosine monophosphate (db cAMP), and 3-isobutyl-1-methylxanthine, respectively, prior to stimulation. Pretreatment of HUVEC with PTX significantly antagonized TNF-, IL-1-, and G-CSF-activated transmigration of neutrophils. Additive stimulatory effects of PTX were seen with LPS. With the exception of theophylline, all other test cAMP-raising agents stimulated transmigration in similar fashion to PTX. Upon stimulation with TNF or LPS, HUVEC produced IL-8 and PTX affected this process in opposing fashions, with inhibition of the effects of TNF and augmentation of those of LPS. These results demonstrate that PTX differentially affects mediator-induced activation of HUVEC. The present IL-8 dependent and cAMP-regulated augmentation of LPS-induced stimulation of transmigration is the first description of an additive effect of PTX with a pro-inflammatory agent.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Inducer-specific bidirectional regulation of endothelial interleukin-8 production by thalidomide.

Interleukin-8 (IL-8) is a potent neutrophil chemotaxin, which can also be produced by endothelial cells to facilitate leukocyte emigration. The aim of this study was to determine the effects of the anti-inflammatory drug thalidomide (THD) on chemotaxin release from endothelial cells. Human umbilical vein endothelial cells (HUVEC) were stimulated with tumor necrosis factor alpha (TNFalpha) or endotoxin (LPS) in the presence or absence of various concentrations of THD. Endothelium-derived interleukin-8 (eIL-8) in supernatants was measured using an enzyme-linked immunosorbent assay (ELISA) and biological activity of the harvested eIL-8 was tested in Boyden chamber chemotaxis assays on PMNL. THD itself had no effect on eIL-8 release. Upon stimulation with TNFalpha or LPS, HUVEC produced increased amounts of eIL-8 and THD affected this process in a bidirectional manner, with augmentation of TNFalpha- and inhibition of LPS-effects. Functionality of eIL-8 was confirmed in chemotaxis experiments and by inhibition of chemotactic effects of supernatants with anti-human IL-8 monoclonal antibodies. Results explain and emphasize immunomodulatory properties of THD in cytokine- and endotoxin-induced inflammation and regulation of transendothelial migration.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Association of endotoxemia with carotid atherosclerosis and cardiovascular disease: prospective results from the Bruneck Study.

OBJECTIVES: Focus of the current study was on the significance of bacterial endotoxin, which shows a variety of pro-atherogenic properties and may occur at high concentration in the circulation of infected subjects. BACKGROUND: The possibility of an infectious risk factor in atherogenesis and cardiovascular disease has stimulated research interest, but the nature of such process remains obscure. METHODS: We measured plasma endotoxin levels (LAL assay) in a random population of 516 men and women 50 to 79 years old at the 1990 baseline evaluation (Bruneck Study). End points of this prospective survey were incident (early) atherosclerosis in the carotid arteries as assessed with high-resolution Duplex ultrasound (five-year follow-up rate, 98%) and incident cardiovascular disease (follow-up rate, 100%). RESULTS: Median endotoxin concentration amounted to 14.3 pg/ml (range, 6.0 to 209.2 pg/ml). Subjects with levels beyond 50 pg/ml (90th percentile) faced a threefold risk of incident atherosclerosis (odds ratio [95% confidence interval] 2.9 [1.4-6.3]; p < 0.01). The risk associated with high endotoxin was most pronounced in subjects with chronic infections and in current and ex-smokers. Notably, smokers with low endotoxin levels and nonsmokers did not differ in their atherosclerosis risk, whereas smokers with high levels almost invariably developed new lesions. All findings emerged as independent of vascular risk factors. Similar results were obtained for incident cardiovascular disease. CONCLUSIONS: The current study yields first epidemiologic evidence that endotoxemia constitutes a strong risk factor of early atherogenesis in subjects with chronic or recurrent bacterial infections and a link in the association between cigarette smoking and atherosclerotic disease.

Aged↗
PubMed1999

Protein kinase C-dependent effects on leukocyte migration of thalidomide.

Thalidomide is effective in the treatment of some tumor necrosis factor-related diseases, but its cellular target is not known. Effects of thalidomide were investigated on lymphocytes and monocytes. Cell migration was examined in a Boyden chamber. Effects on protein kinase C (PKC) were investigated functionally by use of PKC inhibitor and in purified enzyme preparations. Thalidomide itself showed no direct chemotactic effect on lymphocytes or monocytes. Preincubation with the drug significantly enhanced random migration of both cell types. This effect was bisindolylmaleimide-reversible, suggesting involvement of PKC. Preincubation with thalidomide diminished the chemotactic response of monocytes towards formyl peptide but failed to influence lymphocyte chemotaxis towards RANTES or interleukin-8. In a cell-free assay, inhibition of PKC activation by bisindolylmaleimide could be reversed by thalidomide, indicating direct interactions of thalidomide with PKC. Results suggest that effects of thalidomide in chronic inflammation may be related to actions on leukocyte functions.

Adjuvants, Immunologic↗
PubMed1999

Secretoneurin and neurogenic inflammation.

AIM: Review of evidence that the 33-amino-acid polypeptide secretoneurin, which is generated by proteolytic cleavage of secretogranin II, plays a role in neurogenic inflammation. METHODS: Survey of the literature using a MEDLINE search database. RESULTS: Secretoneurin is synthesized in spinal ganglia, transported through the dorsal roots and stored in the axon terminals of primary afferent neurons. Investigations using capsaicin suggest that secretoneurin functions as an excitatory transmitter. Secretoneurin specifically activates various cell functions including the chemotactic migration of monocytes, eosinophils, fibroblasts, smooth muscle cells, and endothelial cells, which suggests that the peptide may modulate inflammatory reactions. Secretoneurin receptors have been functionally characterized. They are G-proteins linked and effects are abrogated by inhibition of protein kinase C. CONCLUSION: With actions as diverse as those seen with other mediators such as tachykinins, secretoneurin may be considered another sensory neuropeptide with modulatory potential in neurogenic inflammation.

Animals↗
PubMed1998

Similar involvement of VIP receptor type I and type II in lymphocyte chemotaxis.

Effects of vasoactive intestinal peptide (VIP) on T cell migration are mediated by structurally distinct types I (VIPR1) and II (VIPR2) G protein-associated receptors. The two receptor types were proposed to transduce opposite effects on human T cells, since cytokine-induced chemotaxis of VIPR1-bearing HuT 78 human T cells, in contrast to T cells that express VIPR2, was inhibited by VIP. We studied chemotactic effects of VIP and related agonists with different affinities for VIP- and peptide histidine-isoleucine (PHI)-related receptors. All, VIP, secretin (SEC), a specific ligand for VIPR1, helodermin (HEL), an activator of helodermin-preferring VIPR2, as well as PHI, stimulated chemotaxis into micropore filters of both normal human peripheral blood T and B cells. Involvement of VIPRs was supported by inhibition of VIP-related agonist-induced migration of T and B cells with a VIPR antagonist. Peripheral blood lymphocyte (PBL) chemotaxis to VIP, SEC, HEL and PHI was reduced by inhibition of tyrosine kinase and pertussis or cholera toxin, whereas inhibition of protein kinase C only affected SEC-induced chemotaxis of PBL significantly. VIP-related agonists induced deactivation of migration at high concentrations. Findings in PBL suggest that VIPR1 activation can stimulate normal T and B cell chemotaxis. Different signaling mechanisms may be involved in mediating chemotactic activation of VIPRs and PHIRs, which may allow further exploration of receptor-dependent mechanisms and signaling pathways of VIP as mediator of PBL functions.

Cell Movement↗
PubMed1998

Specific binding of a 125I-secretoneurin analogue to a human monocytic cell line.

Secretoneurin (SN) is a novel neuropeptide expressed in the central and peripheral nervous system as well as in various endocrine tissues. SN inhibits growth of aortic pulmonary and endothelial cells and is a potent chemoattractant for endothelial cells, skin fibroblasts and monocytes. We investigated here the presence of specific high affinity binding sites for SN on a target tissue. SN was iodinated with the Bolton-Hunter (BH) reagent and purified by isocratic reversed phase chromatography. Specific binding sites for 125I-BHSN were identified on human Mono Mac 6 cells, a monocytic cell line. Scatchard analysis revealed a single class of binding sites with a Kd value of 7.3 nM and a Bmax of 322 (fmol/mg protein). Competition studies demonstrated that the 15 C-terminal amino acids of SN could displace authentic SN, whereas shorter fragments were inactive. Other sensory neuropeptides like substance P, calcitonin gene-related peptide or galanin as well as the chemokine receptor ligand Rantes or the typical chemoattractant FMLP could not displace SN. Our studies demonstrate specific high affinity binding sites for SN on a monocytic cell line. Since SN exerts a potent chemotactic activity towards monocytes and increases cytosolic calcium in these cells, these binding sites might well represent a putative functional plasma membrane receptor for SN.

Animals↗
PubMed1998

Secretoneurin, a novel neuropeptide, is a potent chemoattractant for human eosinophils.

Secretoneurin (SN), a 33-amino acid neuropeptide, is derived from secretogranin II that is released from sensory afferent C-fibers by capsaicin. Described functions of secretoneurin include chemotaxis of monocytes and endothelial cells, and inhibition of endothelial cell proliferation. Inhibition of monocyte chemotaxis by staurosporine indicated involvement of specific signaling pathways. We have tested effects of SN, substance P (SP), and interleukin-8 (IL-8) on eosinophil migration in modified Boyden chambers including signaling mechanisms of neuropeptide and cytokine stimulation of human eosinophils. Experiments showed SN as eosinophil chemoattractant comparable in its potency to IL-8. Checkerboard analysis, usage of a specific anti-SN-antibody, and receptor desensitization experiments confirmed the chemotactic activity. Preincubation of the cells with effective concentrations of staurosporine or tyrphostin-23 showed no effect, whereas treatment with wortmannin (WTN) or 3-isobutyl-1-methylxantin (IBMX) completely blocked SN-induced migration. Additionally, experiments ruled out tyrphostin-23- and WTN-sensitive signaling pathways for SP-induced chemotaxis of eosinophils. We conclude that SN-stimulated human eosinophil chemotaxis is mediated via a unique and specific signal transduction pathway that involves activation of phosphodiesterases and WTN-sensitive enzymes, ie, phospholipase D and phosphatidylinositol-3-kinase. In contrast, we report that activation of the latter and tyrosine kinases is required for SP-induced chemotaxis of eosinophils.

1-Methyl-3-isobutylxanthine↗
PubMed1998

The acute-phase protein alpha 1-antitrypsin inhibits transferrin-receptor binding and proliferation of human skin fibroblasts.

Transferrin (Tf) is required for proliferation of most cells, because cellular iron uptake is mainly mediated by binding of Tf to its specific cell surface receptors (TfR). The acute-phase protein alpha 1-antitrypsin (alpha 1-AT) completely inhibits binding of diferric Tf to TfRs on human skin fibroblasts in a dose-dependent fashion. The inhibition is competitive as proved in equilibrium saturation binding and kinetic studies. In saturation binding experiments alpha 1-AT apparently increased the dissociation constant (KD), but did not change the maximal density of binding sites (Bmax). As shown in kinetic studies, this reduction of the affinity of Tf to its receptor caused by alpha 1-AT was due to a decrease of the association rate constant (k + 1), whereas the dissociation rate constant (k - 1) remained unchanged. Furthermore, alpha 1-AT almost completely prevented internalization of the Tf-TfR complex. These interactions demonstrated biological implication, as alpha 1-AT reduced the proliferation of human fibroblasts up to maximal 30% of control. The inhibitory potency of alpha 1-AT was already seen in physiologic concentrations; the maximal effect, however, was achieved at concentrations above the normal range, which are attained in the course of inflammation and infection. Therefore, we suppose that alpha 1-AT as an endogenous factor modulates the complex mechanism of fibrogenesis not only by its known antiproteolytic function but also by inhibiting the proliferation of fibroblasts.

Acute-Phase Proteins↗
PubMed1998

Induction of arachidonic acid metabolite release by human fibroblasts in proliferative vitreoretinopathy.

Proliferative vitreoretinopathy is a severe ocular disorder characterized by unwanted proliferation of cells and excessive production of fibrous tissue, which leads to the formation of cellular membranes on the surface of the retina and in the vitreous. Proliferative vitreoretinopathy is the most common cause of failure in retinal reattachment surgery, approximately occurring in one out of ten operated eyes. Proliferation of retinal pigment epithelial cells and fibroblasts is a cornerstone in the pathogenesis of proliferative vitreoretinopathy. An in vitro-proliferation assay showed previously that intraocular fluid from patients with proliferative vitreoretinopathy is potently effective in stimulating proliferation of human fibroblasts. Here we show that exposure of human fibroblasts to vitreous fluids from patients with proliferative vitreoretinopathy causes a rapid and sustained increase in arachidonic acid metabolite release as measured by competitive enzyme-immunoassay. The findings implicate prostaglandin E2 as a contributor to enhanced intraocular fibrosis in proliferative vitreoretinopathy. As prostaglandin E2 is a mediator of continuous aqueous-blood retinal barrier breakdown in this severe disease, cycclooxygenase inhibitors such as acetylsalicylic acid, which was successfully used in this study for blocking the effect of intraocular fluid, may be useful agents in targeting the progression of intraocular fibrosis.

Adult↗
PubMed1998

Signaling in neuropeptide-induced migration of human eosinophils.

At inflammatory sites, leukocytes may confront multiple, competing chemoattractive signals. We compared the chemotactic potencies of several sensory neuropeptides with regard to signal transduction pathways in eosinophils. Eosinophils were enriched using magnetic cell sorting and migration was assayed in a Boyden microchemotaxis chamber. We found stimulatory effects of substance P, calcitonin gene-related peptide (CGRP), secretoneurin, vasoactive intestinal peptide (VIP), and secretin on eosinophil migration. Actions of VIP are predominantly mediated via VIP receptor type I. Migration toward secretoneurin, VIP, and secretin was blocked by a phosphodiesterase inhibitor, which, in contrast failed to affect substance P- and CGRP-induced eosinophil chemotaxis. Wortmannin blunted the migratory responses induced by all neuropeptides tested and substance P-induced effects on eosinophils were tyrphostin-23-sensitive. We conclude that substance P, CGRP, secretoneurin, and VIP/secretin stimulate eosinophil migration involving wortmannin-sensitive enzymes. Moreover, secretoneurin and VIP/secretin require additional activation of phosphodiesterases to stimulate eosinophil migration.

Calcitonin Gene-Related Peptide↗
PubMed1998

Release of chemoattractants for human monocytes from endothelial cells by interaction with neutrophils.

OBJECTIVE: The release of monocyte chemoattractant protein-1 (MCP-1) in the vessel wall may lead to accumulation of monocytes in the subendothelial space. The role of neutrophils (PMNL) in the initiation of this process is unknown. We tested whether PMNL are able to induce the production and release of MCP-1 in endothelial cells. METHODS: PMNL were allowed to interact with human umbilical vein endothelial cell (HUVEC) monolayers in culture. Culture media were collected and assessed for chemotactic activity on mononuclear leukocytes (MNC) or purified monocytes in a modified Boyden chamber assay. Additionally, MCP-1 levels in supernatants were quantified by ELISA. RESULTS: Media from unstimulated HUVEC culture supernatants induced a slight increase (1.2-fold) of MNC and purified monocyte chemotaxis, which was significantly augmented by addition of PMNL for 1 h (1.4-fold; P < 0.05). The increase in chemotaxis was time- and dose-dependent and could be blocked by an anti-MCP-1 monoclonal antibody. Media obtained after coculture of PMNL and HUVEC for 1-5 h contained increased amounts of MCP-1 as measured by ELISA; addition of cycloheximide abolished this response. CONCLUSIONS: Interaction of PMNL with endothelium induces the release of functionally active MCP-1 suggesting that in the vascular wall, PMNL may play a role in the recruitment of MNC.

Arteriosclerosis↗
PubMed1998

Effect of inhibitors of Na+/H+-exchange and gastric H+/K+ ATPase on cell volume, intracellular pH and migration of human polymorphonuclear leucocytes.

1. Stimulation of chemotaxis of human polymorphonuclear leucocytes (PMNs) with the chemoattractive peptide fMLP (N-formyl-Met-Leu-Phe) is paralleled by profound morphological and metabolic alterations like changes of intracellular pH (pHi) and cell shape. The present study was performed to investigate the interrelation of cell volume (CV) regulatory ion transport, pHi and migration of fMLP stimulated PMNs. 2. Addition of fMLP to PMNs stimulated directed migration in Boyden chamber assays and was accompanied by rapid initial intracellular acidification and cell swelling. 3. Inhibition of the Na+/H+ exchanger suppressed fMLP stimulated cell migration, accelerated the intracellular acidification and inhibited the fMLP-induced cell swelling. 4. Step omission of extracellular Na+ caused intracellular acidification, which was accelerated by subsequent addition of gastric H+/K+ ATPase inhibitor SCH 28080, or by omission of extracellular K+ ions. In addition Na+ removal caused cell swelling, which was further enhanced by fMLP. 5. H+/K+ATPase inhibitors omeprazole and SCH 28080 inhibited stimulated migration and blunted the fMLP-induced increase in CV. 6. Increasing extracellular osmolarity by addition of mannitol to the extracellular solution caused cell shrinkage followed by regulatory volume increase, partially due to activation of the Na+/H+ exchanger. In fMLP-stimulated cells the CV increase was counteracted by simultaneous addition of mannitol. Under these conditions the fMLP stimulated migration was inhibited. 7. The antibacterial activity of PMNs was not modified by Hoe 694 or omeprazole. 8. Western analysis with a monoclonal anti gastric H+/K+ ATPase beta-subunit antibody detected a glycosylated 35 kD core protein in lysates of mouse and human gastric mucosa as well as in human PMNs. 9. The results indicate that fMLP leads to cell swelling of PMNs due to activation of the Na+/H+ exchanger and a K+-dependent H+-extruding mechanism, presumably an H+/K+ ATPase. Inhibition of these ion transporters suppresses the increase in CV and precludes PMNs from stimulated migration.

Animals↗
PubMed1998

Association of high plasma antioxidant capacity with new lesion formation in carotid atherosclerosis: a prospective study.

BACKGROUND: In atherosclerosis, both reductions and elevations in plasma levels of antioxidants have been reported. This study investigated total antioxidant capacity of plasma from subjects with atherosclerotic disease. MATERIALS AND METHODS: The study population consisted of 48 men with or without carotid atherosclerosis. At baseline (1990) carotid arteries were evaluated by duplex sonography and plasma samples were obtained for testing antioxidant capacity by two different test systems. One assay system used neutrophils from healthy volunteers as a source of oxygen free radicals activating the non-fluorescent dichlorofluorescin diacetate in the presence of antioxidant containing plasma from study subjects. In the other test system, total plasma antioxidants were detected colorimetrically by using 2,2'-azino-di-(3-ethylbenzthiazoline sulphonate), metmyoglobin and superoxide in the presence of plasma. Carotid arteries were re-evaluated for the development of new plaques 5 years later (1995). RESULTS: Increased baseline total antioxidant capacity of plasma was significantly associated with the development of new atherosclerotic lesions during a period of 5 years. CONCLUSIONS: Endogenous antioxidant capacity of plasma is increased in patients with active atherosclerotic disease. As scavenging of oxygen free radicals is thought to protect from atherogenesis, elevated antioxidative capacity may represent an adaptive mechanism.

Adult↗