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Werner Seeger

Publications and source records attributed to Werner Seeger.

136 records · Page 8Linked to original sources
PubMed2002

Role of resident alveolar macrophages in leukocyte traffic into the alveolar air space of intact mice.

Intratracheal instillation of the monocyte chemoattractant JE/monocyte chemoattractant protein (MCP)-1 in mice was recently shown to cause increased alveolar monocyte accumulation in the absence of lung inflammation, whereas combined JE/MCP-1/lipopolysaccharide (LPS) challenge provoked acute lung inflammation with early alveolar neutrophil and delayed alveolar monocyte influx. We evaluated the role of resident alveolar macrophages (rAM) in these leukocyte recruitment events and related phenomena of lung inflammation. Depletion of rAM by pretreatment of mice with liposomal clodronate did not affect the JE/MCP-1-driven alveolar monocyte accumulation, despite the observation that rAM constitutively expressed the JE/MCP-1 receptor CCR2, as analyzed by flow cytometry and immunohistochemistry. In contrast, depletion of rAM largely suppressed alveolar cytokine release as well as neutrophil and monocyte recruitment profiles upon combined JE/MCP-1/LPS treatment. Despite this strongly attenuated alveolar inflammatory response, increased lung permeability was still observed in rAM-depleted mice undergoing JE/MCP-1/LPS challenge. Lung leakage was abrogated by codepletion of circulating neutrophils or administration of anti-CD18. Collectively, rAM are not involved in JE/MCP-1-driven alveolar monocyte recruitment in noninflamed lungs but largely contribute to the alveolar cytokine response and enhanced early neutrophil and delayed monocyte influx under inflammatory conditions (JE/MCP-1/LPS deposition). Loss of lung barrier function observed under these conditions is rAM independent but involves circulating neutrophils via beta(2)-integrin engagement.

Animals↗
PubMed2002

In vitro mimicry of essential fatty acid deficiency in human endothelial cells by TNFalpha impact of omega-3 versus omega-6 fatty acids.

Severe endothelial abnormalities are a prominent feature in sepsis with cytokines such as tumor necrosis factor (TNF)alpha being implicated in the pathogenesis. As mimic to inflammation, human umbilical vascular endothelial cells (HUVEC) were incubated with TNFalpha for 22 h, in the absence or presence of the omega-6 fatty acid (FA), arachidonic acid (AA), or the alternative omega-3 FA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). TNFalpha caused marked alterations in the PUFA profile and long chain PUFA content of total phospholipids (PL) decreased. In contrast, there was a compensatory increase in mead acid [MA, 20:3(omega-9)], the hallmark acid of the essential fatty acid deficiency (EFAD) syndrome. Corresponding changes were noted in phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol, but not in the sphingomyelin fraction. Supplementation with AA, EPA, or DHA markedly increased the respective FA contents in the PL pools, suppressed the increase in MA, and resulted in a shift either toward further predominance of omega-6 or predominance of omega-3 FA. We conclude that short-term TNFalpha incubation of HUVEC causes an EFAD state hitherto only described for long-term malnutrition, and that endothelial cells are susceptible to differential influence by omega-3 versus omega-6 FA supplementation under these conditions.

Cells, Cultured↗
PubMed2002

Wegener's granulomatosis: antiproteinase 3 antibodies induce monocyte cytokine and prostanoid release-role of autocrine cell activation.

Antineutrophil cytoplasmic antibodies (ANCA) targeting proteinase 3 [PR3; cytoplasmic ANCA (c-ANCA)], a leukocyte serine protease, are highly specific for Wegener's Granulomatosis (WG). A pathogenetic role for c-ANCA has been proposed as a result of their ability of activating neutrophils, whereas their interaction with monocytes is less well characterized. We investigated the influence of monoclonal anti-PR3 antibodies (anti-PR3) and c-ANCA from WG sera on monocyte cytokine and prostanoid release. We found that PR3 was expressed on the surface of isolated monocytes. Anti-PR3 challenge provoked a pronounced release of cytokines with early appearance of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-1beta and delayed release of IL-6, IL-8, and thromboxane A2 (TxA2). The secretory response was reproduced by c-ANCA but not by human and murine control IgG and anti-CD14 antibodies. Because F(ab)2 fragments of anti-PR3 were ineffective, coligation of Fc gamma receptors (FcgammaR) was apparently mandatory for monocyte activation. Using soluble receptors for TNF-alpha and IL-1beta and a Tx receptor antagonist, we noted that the "early" cytokines functioned as inducers of TxA2, which then activated IL-8 release. In contrast, IL-6 formation was an independent event. We concluded that anti-PR3 antibodies are potent inducers of monocyte cytokine and prostanoid release, and TNF-alpha, IL-1beta, and TxA2 function as facilitators of the secretory response. These mechanisms may contribute to inflammatory tissue injury in WG.

Antibodies, Antineutrophil Cytoplasmic↗
PubMedDate not supplied

Chemical coupling of a monoclonal antisurfactant protein-B antibody to human urokinase for targeting surfactant-incorporating alveolar fibrin.

Intraalveolar fibrin formation is a common histopathological finding in acute inflammatory and chronic interstitial lung diseases. Incorporation of hydrophobic surfactant components into polymerizing fibrin results in a severe loss of surface activity, altered mechanical and structural clot properties, and a reduced susceptibility toward fibrinolytic degradation. Such events have been implicated in atelectasis formation, impairment of gas exchange, and provocation of fibroproliferative changes. In an effort to address the unique features of alveolar fibrin, we designed a hybrid molecule consisting of a monoclonal antibody against surfactant protein SP-B (8B5E) and the catalytic domain of urokinase (B-chain), which was termed MABUC. The urokinase B-chain was prepared by limited reduction of human two-chain-urokinase and subsequent affinity purification and coupled to the antibody using a heterobifunctional cross-linker. Purification of the chimeric protein included gel filtration chromatography and affinity chromatography. An ELISA-like microtiter plate assay, based on the immunological detection of the SP-B moiety and the fibrinolytic activity of the u-PA domain, was developed for the detection of the hybrid molecule. Chromogenic substrate assays, (125)I-based fibrin plate assays, and active site titration were performed to analyze the specific fibrinolytic activity of the conjugate. MABUC was found to fully retain the ability of SP-B binding and the fibrinolytic activity of u-PA. In addition, MABUC was noted to be 1.5-2-fold more effective in the dissolution of surfactant embedding clots and to be approximately 3-fold more resistant against PAI-1, the predominant fibrinolysis inhibitor in the alveolar compartment, as compared to the native u-PA. The superiority of MABUC was particularly prominent (>5-fold efficacy) when investigating clot material incorporating both PAI-1 and surfactant, as a mimicry of alveolar fibrin. We conclude that urokinase and 8B5E can be cross-linked chemically, thus yielding a fibrinolytic enzyme with enhanced substrate specifity for surfactant-containing clots and higher PAI-1 resistance as compared to native u-PA.

Animals↗
PubMedDate not supplied

DNA transfer into human lung cells is improved with Tat-RGD peptide by caveoli-mediated endocytosis.

Cell lines and primary cells exhibit varying degrees of resistance to DNA transfection strategies. In this study, we employed the synthetic peptide Tat-RGD (TR), composed of the HIV-1 derived translocation peptide Tat fused to the integrin binding RGD motif, as a tool for improving DNA transfer into pulmonary cells. Binding experiments between DNA and TR and cytotoxicity measurements of TR treated cells were undertaken to optimize DNA and TR concentrations for transfection. Addition of a complex of TR and DNA (TRD) to A549 cells yielded significant transgene expression. When TRD was combined with Lipofectamine (TRDL), the expression was increased by 5-fold over Lipofectamine (DL) and by approximately 30-fold over TRD-mediated transfections. Also, in primary smooth muscle cells (SMC) and fibroblasts (FB) derived from pulmonary arteries, an increase in TRDL-mediated transfection efficiency was observed by a factor of approximately 2 and approximately 3 over that of DL. Laser scanning confocal microscopy for visualizing TR-dependent DNA uptake demonstrated that the internalization of TRDL complexes is linked to caveoli in the plasma membrane. Interfering with caveoli formation by methyl-b-cyclo-dextrin drastically decreased the transfection efficiency by TR. In conclusion, the Tat-RGD peptide mediates efficient gene delivery in human pulmonary cells, in particular when combined with a standard cationic lipid based transfection reagent. The enhancement of DNA uptake by Tat-RGD is suggested to be mediated by caveoli-dependent endocytosis.

Animals↗
PubMedDate not supplied

Hybrid-primed lymphocytes and hybrid vaccination prevent tumor growth of lewis lung carcinoma in mice.

Dendritic cell (DC)-tumor cell hybrids are currently being evaluated as a novel antitumor vaccination strategy. We have explored in an animal model whether administration of DCs fused with poorly immunogenic carcinoma cells could elicit an antitumor response. Fusion of C57/BL6 mice bone marrow-derived DCs with Lewis lung carcinoma (LLC1) cells resulted in approximately 50% fusion efficiency. Hybrid cells (HCs) were used to explore 3 potential tumor therapy strategies: protective immunization, vaccination, and adoptive cellular therapy. Immunization with HCs induced activation of proliferating cytotoxic T cells, upregulation of distinct cytokines genes, and a significant retardation of tumor growth. Similar results were observed by vaccination with HCs in the tumor-bearing host. Finally, when T cells from HC-vaccinated mice were transferred into naive tumor-bearing mice, tumor growth was strongly retarded and an efficient proliferative and cytotoxic T-cell response was observed. Tumor growth was reduced by more than 50%, and tumor development was significantly delayed. Taken together, we demonstrate that HCs offer effective immunotherapy of poorly immunogenic carcinomas. This is independent of whether the HCs are taken for adoptive transfer or as a vaccine.

Adoptive Transfer↗
PubMedDate not supplied

Effect of PEGylation on the stability of liposomes during nebulisation and in lung surfactant.

Oral inhalation of anticancer drugs or drug delivery system is a novel therapeutic approach in the treatment of lung cancer and requires formulations which are sufficiently stabile during nebulisation and subsequent interaction with the surfactant lining of the lungs. In this study, we assessed the stability of plain and PEGylated transferrin-conjugated liposomes after nebulisation using two different nebulisers (i.e., air-jet and ultrasonic type). Furthermore, the integrity of the liposomal membranes was assessed after incubation in commercial lung surfactant solutions (Alveofact). All liposomal formulations showed no significant changes in their size after nebulisation, independent of the type of nebuliser or the liposomal formulation, respectively. However, PEGylation was of advantage when it came to interactions between liposomes and the surfactant lining of the lungs. PEGylated liposomes were significantly more stable and retained > 80% of their drug load over 48 h, which is more than sufficient time for the drug carriers to be taken up by transferrin receptor over-expressing cancer cells in the lung. In conclusion, PEGylated and plain Tf-conjugated liposomes are stable enough to undergo nebulisation in the course of an inhalational therapy, but PEG-stabilisation results in a higher degree of membrane integrity in lung surfactant.

Drug Carriers↗
PubMedDate not supplied

A double-blind, randomized, placebo-controlled trial of n-3 versus n-6 fatty acid-based lipid infusion in atopic dermatitis.

BACKGROUND: In the involved epidermis of patients with atopic dermatitis, changes in the metabolism of eicosanoids with increased quantities of the arachidonic acid (AA)-derived lipoxygenase products have been observed. Free eicosapentaenoic acid (EPA), a fish oil-derived alternative (n-3) fatty acid, may compete with AA, resulting in an anti-inflammatory effect. METHODS: In a 10-day double-blind, randomized, placebo-controlled trial, 22 patients hospitalized for moderate-to-severe atopic dermatitis were randomly assigned to receive daily infusions of either a n-3 fatty acid-based lipid emulsion (fish oil, 10%; 200 mL/d) or a conventional n-6-lipid emulsion (soybean oil, 10%; 200 mL/d). Topical treatment was restricted to emollients. The severity of disease was evaluated daily with scoring of erythema, infiltration, and desquamation and by subjective patient scoring of clinical manifestations. In addition, plasma-free and total-bound fatty acids and the composition of membrane fatty acids in blood cells (thrombocytes, granulocytes, and erythrocytes), lipid mediators from isolated neutrophils and platelets, and lymphocyte-activation parameters were determined. RESULTS: Twenty patients completed the trial. Marked improvement from baseline was seen in both groups. On days 6, 7, 8, and 10, disease severity score-defined as the sum of all scores-was more pronounced (p < .05) in the n-3 group compared with the n-6 group. Free arachidonic acid in plasma did not change substantially in both groups, whereas plasma-free EPA, total-bound EPA, and the membrane EPA/AA ratio markedly increased in response to n-3-lipid infusion. In parallel, EPA-derived lipid mediators appeared, whereas lymphocyte functions were unaffected. In the post-treatment period (2/4 weeks), relapse was observed in some patients after n-3 psoralene-ultraviolet A (PUVA) infusion, whereas there was a marked long-term improvement in the n-6 group. CONCLUSIONS: IV n-3-fatty acid administration is effective in acutely improving the severity of atopic dermatitis, paralleled by changes in plasma and membrane fatty acid composition and lipid mediator synthesis. The long-term beneficial effects of IV n-6 fatty acids should be evaluated further.

Adolescent↗
PubMedDate not supplied

Measurement of exhaled hydrogen peroxide from rabbit lungs.

Exhaled H2O2 is considered an indicator of lung inflammatory and oxidative stress. Moreover, H2O2 may be involved in signal transduction processes. It is not fully elucidated to what extent (i) H2O2 escapes from the intravascular compartment, and (ii) pulmonary H2O2 generation and nasopharyngeal H2O2 generation contribute to exhaled H2O2. We investigated H2O2 concentrations in breath condensate from isolated buffer-perfused and ventilated rabbit lungs, and from both intubated and spontaneously breathing rabbits with a horseradish peroxidase/2',7'dichlorofluorescin assay. For the perfused lungs, a H2O2 concentration of 58 +/- 19 nM was found. Addition of H2O2 to the buffer fluid resulted in only minute appearance in the exhaled air (<0.001%). Levels of exhaled H2O2 in intubated rabbits and perfused lungs were virtually identical. Nearly ten-fold higher levels were detected in spontaneously breathing rabbits. Decreasing the inspired oxygen concentration from 21% to 1% resulted in a tendency toward decreased H2O2 exhalation in perfused lungs. In contrast, phorbol-12-myristate-13-acetate (PMA) prompted a approximately 4-fold increase in H2O2 exhalation. We conclude that the horseradish peroxidase/2',7'dichlorofluorescin assay is a feasible technique to measure H2O2 in exhaled breath condensate in rabbits. When collecting exhaled air via the tracheal tube, the signal represents pulmonary H2O2 generation with the contribution of the remaining body being negligible.

Animals↗