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Biomedical subjects

H Kähler

Publications and source records attributed to H Kähler.

15 recordsLinked to original sources
PubMed2001

Perfluorochemical liquids modulate cell-mediated inflammatory responses.

OBJECTIVE: To examine whether chemically different perfluorochemical liquids (PFC) (perfluorodecalin [PFD]; perflubron [PFB]) induce inflammatory responses in blood leukocytes. SETTING: University research laboratory. DESIGN: Whole blood from 12 healthy adults was incubated with increasing PFC concentrations and/or bacterial lipopolysaccharide. MEASUREMENTS AND MAIN RESULTS: Adhesion molecules (CD62L, CD11b), reactive oxygen species, and cytokine responses in resting and activated leukocyte subtypes were studied. Scanning and transmission electron microscopies were performed. At the highest concentrations, PFB stimulated a significant increase in resting monocytic reactive oxygen species production; all types of blood leukocytes were unresponsive to PFD. Neither PFB nor PFD changed CD62L expression; PFB increased CD11b expression in monocytes and granulocytes. PFD induced a small though significant increase in interleukin-8 secretion. When simulating a condition in which patients with severe lung disease or sepsis would be ventilated with PFC, neither PFB nor PFD plus lipopolysaccharide stimulated tumor necrosis-alpha or interleukin-8 production above levels induced by lipopolysaccharide alone, but rather demonstrated a trend for decreased tumor necrosis factor-alpha production. Expression of CD11b and CD62L and the production of reactive oxygen species were not changed beyond the levels induced by lipopolysaccharide alone. As a morphologic correlate to the above proinflammatory changes, surface-bound blebs and intracellular vacuoles were seen by electron microscopy. CONCLUSIONS: At PFC concentrations comparable with those in blood during liquid ventilation, PFC liquids did not induce variables associated with inflammation. In the presence of high PFC concentrations, simulating the condition in which bronchoalveolar cells are exposed to PFC, monocytes may be induced by PFB to produce reactive oxygen species, and blood leukocytes induced by PFB to express CD11b and by PFD to secrete interleukin-8; the presence of either PFC attenuated tumor necrosis factor-alpha production after lipopolysaccharide stimulation.

Adult↗
PubMed2001

Aminoethyl-isothiourea inhibits leukocyte production of reactive oxygen species and proinflammatory cytokines induced by streptococcal cell wall components in human whole blood.

The incidence of severe invasive disease caused by serogroup A streptococci (GAS) is increasing, and to elucidate the role of streptococcal cell wall components in the inflammatory response, human whole blood was stimulated with lipoteichoic acid (LTA, 0.005-50 microg/mL) and peptidoglycan (10 and 100 microg/ml) from Streptococcus pyogenes. Both stimulants increased dose dependently the leukocyte release of cytokines many thousand fold: tumor necrosis factor alpha (0 to 158,000+/-4,900 pg/mL), interleukin (IL)-1beta (85+/-56 to 31,000+/-4,600 pg/mL), IL-6 (30+/-11 to 34,800+/-15,000 pg/mL), and IL-8 (300+/-150 to 29,000+/-14,000 pg/mL). Intracellular leukocyte levels of reactive oxygen species (ROS) as measured by flow cytometry increased 15-20 fold, from 25 to 400-500 mean fluorescence intensity. Aminoethyl-isothiourea (AE-ITU), a relatively selective inhibitor of the inducible nitric oxide synthase (iNOS) and a ROS scavenger, reduced the cytokine production by 70-100%, and intracellular leukocyte ROS levels by 50-70% (all P < 0.05). The non-selective NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME) did not affect intracellular ROS levels, but it caused a moderate selective inhibition of IL-8 production. Leukocyte NO production (measured up to 36 h) was not enhanced by LTA, peptidoglycan, inactivated streptococci, or cytokine combinations. The mechanisms for the anti-inflammatory effects of AE-ITU may be through a reduction of intracellular ROS levels, or through a direct effect on signal transduction, whereas NO modulation is an unlikely mechanism.

Cell Survival↗
PubMed2001

Proteome analysis of interleukin-1beta--induced changes in protein expression in rat islets of Langerhans.

The intracellular molecular events involved in the beta-cell death process are complex but poorly understood. Cytokines, e.g., interleukin (IL)-1beta, may play a crucial role in inducing this process. Protein synthesis is necessary for the deleterious effect of IL-1, and induction of both protective and deleterious proteins has been described. To characterize the rather complex pattern of islet protein expression in rat islets in response to IL-1, we have attempted to identify proteins of altered expression level after IL-1 exposure by 2D gel electrophoresis and mass spectrometry. Of 105 significantly changed (i.e., up- or downregulated or de novo-induced) protein spots, we obtained positive protein identification for 60 protein spots. The 60 identifications corresponded to 57 different proteins. Of these, 10 proteins were present in two to four spots, suggesting that posttranslatory modifications had occurred. In addition, 11 spots contained more than one protein. The proteins could be classified according to their function into the following groups: 1) energy transduction; 2) glycolytic pathway; 3) protein synthesis, chaperones, and protein folding; and 4) signal transduction, regulation, differentiation, and apoptosis. In conclusion, valuable information about the molecular mechanisms involved in cytokine-mediated beta-cell destruction was obtained by this approach.

Animals↗
PubMed2000

Changes in plasma IL-1beta, TNF-alpha and IL-6 after total hip replacement surgery in general or regional anaesthesia.

Different anaesthetic methods influence the neuro-immuno-endocrine biologic responses to surgery and may thus possibly interfere with the postoperative course and development of complications. The neuroendocrine system is closely related to the cytokine network. In this study, the effects of general anaesthesia (n=6) and regional spinal/epidural anaesthesia (n=6) on the cytokine response (IL-1beta, TNFalpha, IL-6) to uncemented total hip replacement surgery were evaluated. The postoperative clinical course was uneventful in every case. In both groups, only very low values of plasma IL-beta were measured perioperatively, whereas plasma IL-6 increased postoperatively with peak values 4 h after surgery. The changes in plasma TNF-alpha were not significant. No significant differences in plasma TNF-alpha or IL-6 were found between patients operated in general or in regional anaesthesia. This suggests minor influence of plasma cytokines on the possible beneficial effects of regional anaesthesia on the clinical course after surgery in low risk patients. There were slightly higher TNF-alpha and IL-6 levels after the operation and significantly lower cortisol levels during the operation in the regional anaesthesia group compared to the general anaesthesia group, giving rise to a significant inverse correlation between peak values of IL-6 and peak values of cortisol. This supports the theory that after surgery the inhibitory effect of cortisol on monocyte cytokine production overrides adrenergic stimulation.

Anesthesia, General↗
PubMed2000

Changed expression of leukocyte adhesion molecules and increased production of reactive oxygen species caused by Streptococcus pyogenes in human whole blood.

To elucidate the innate immune responses to group A streptococci (GAS) important in the pathophysiology of sepsis, flow cytometric techniques were applied to study the effects of live and heat-inactivated GAS, including their particulate and soluble components, on the expression of leukocyte adhesion molecules CD11b (Mac-1) and CD62L (L-selectin), and leukocyte production of reactive oxygen species (ROS) in human whole blood. GAS caused marked time- and concentration-dependent increases in CD11b and ROS, while CD62L was downregulated. Live and heat-inactivated GAS induced similar changes in leukocyte adhesion molecules, whereas ROS production induced by heat-inactivated GAS (and its particulate fraction) was 4 (2.5)-fold higher than with live GAS. Leukocyte nitric oxide production (24 h) was not enhanced. Although GAS proved a more potent inducer of ROS production, leukocyte responses to GAS were similar to those reported for lipolysaccharides, indicating that Gram-positive and Gram-negative bacteria activate common pathways in the inflammatory response. High ROS production may contribute to tissue damage caused by GAS.

Arginine↗
PubMed2000

Peptidoglycan and lipoteichoic acid, components of the streptococcal cell wall, have marked and differential effects on adhesion molecule expression and the production of reactive oxygen species in human whole blood leukocytes.

UNLABELLED: To elucidate the pathophysiology of infections with Streptococcus pyogenes we applied flow cytometric techniques to study dose-response and time-related effects of the streptococcal cell-wall-derived components lipoteichoic acid (LTA 0.005 to 50 microg/ml) and peptidoglycan (10 and 100 microg/ml) on the expression of leukocyte adhesion molecules, the CD14 receptor, and the production of leukocyte reactive oxygen species (ROS). LTA (50 microg/ml, 1-2 h) markedly increased the expression of CD11b (approximately 5-fold), CD11c (approximately 2-fold) and CD11a. Concomitantly, CD62L was downregulated (60%). Peptidoglycan alone or in combination with LTA had little effect on adhesion molecules, except for an amplification of the downregulation of CD62L to 90%. Monocyte CD14 expression was doubled by LTA. Leukocyte ROS production was 10-fold and 5-fold increased by peptidoglycan in granulocytes and monocytes, respectively. LTA alone had no effect, while the combination of peptidoglycan with LTA doubled the increase in ROS caused by peptidoglycan. CONCLUSION: LTA and peptidoglycan had marked and differential effects: LTA caused mainly adhesion molecule modulation, whereas peptidoglycan mainly increased ROS production. These changes are important in inflammatory cell activation and recruitment, intracellular microbial killing and adverse tissue injury.

Cell Adhesion Molecules↗
PubMed1999

Allergen-stimulated expression of CD154 (CD40 ligand) on CD3+ lymphocytes in atopic, but not in nonatopic individuals. Modulation by bacterial lipopolysaccharide.

The intention of this study was to mimic a naturally occurring stimulation by allergens and bacterial infection in order to determine whether specific allergen-induced, inflammatory responses may be changed or modified by bacterial products. Blood leukocytes from six atopic and six nonatopic individuals were examined for their surface expression of CD154, CD11a, and HLA-DR molecules and for secretion of IgE, eosinophil cationic protein (ECP), and the cytokines interleukin (IL)-4 and IL-5. Signals through CD154 are required for activation and proliferation of effector cells associated with the allergic, inflammatory response. HLA-DR and CD11a/CD18-mediated interactions are also involved in T- and B-cell functions. Birch-pollen (BP) allergens induced CD154 expression on CD3-positive lymphocytes only in atopic individuals. In nonatopics, the expression of CD154 could be induced only after exposure to BP and subsequent lipopolysaccharide (LPS) stimulation. Levels of CD154 expression were always higher in atopics than nonatopics. CD11a and HLA-DR expressions were upregulated, irrespective of atopic state, after BP and/or LPS stimulation. The increased secretion of IL-5 and total IgE in BP-supplemented cell cultures indicated that an allergic response had occurred. In conclusion, the results of this report do not support the hypothesis of a changed inflammatory response stimulated by the combined action of bacteria and allergens, as compared to allergen provocation alone.

Adult↗
PubMed1999

LPS from Actinobacillus actinomycetemcomitans and the expression of beta2 integrins and L-selectin in an ex vivo human whole blood system.

Actinobacillus actinomycetemcomitans is assumed to be an important etiological agent in localized juvenile periodontitis (LJP) and to have the ability to invade periodontal tissues. This bacterium has also been noted for its potential to cause serious extraoral infections. In this study, the effect of lipopolysaccharides (LPS) extracted from A. actinomycetemcomitans on the expression of the leukocyte adhesion molecules CD11a/CD18, CD11b/CD18, CD11c/CD18 and L-selectin (CD 62L) were measured in an ex vivo whole blood system by use of fluorescent antibodies followed by flow cytometry. LPS from Escherichia coli, which is known to elicit a strong inflammatory response was used as a reference. The expression of the beta2 integrins CD11a/CD18, CD11b/CD18, and CD11c/CD18 were significantly upregulated in granulocytes and monocytes. This expression was dose-dependent. The baseline levels of L-selectin was high on all three types of leukocytes, but on granulocytes and monocytes it decreased dramatically after stimulation with LPS. The LPS from A. actinomycetemcomitans was equally potent as LPS from E. coli in its ability to affect the expression of the leukocyte integrins and L-selectin.

Aggregatibacter actinomycetemcomitans↗
PubMed1999

Production of oxidants in alveolar macrophages and blood leukocytes.

Increased production of oxidants subsequent to phagocyte stimulation has been associated with tissue damage in lung inflammatory disorders. The overall oxidative burden of the lung may vary with inflammatory cell composition. Flow cytometry using three different dyes, dihydroethidium (DHE), dichlorofluorescein diacetate (DCFH-DA) and dihydrorhodamine 123 (DHR), all compounds that by interaction with oxidants are transformed to fluorescent products, was used to examine the production of intracellular oxidants in alveolar macrophages (AMs), including size-defined subpopulations, monocytes (Ms) and polymorphonuclear neutrophils (PMNs) during in vitro incubation in the presence or absence of phorbol myristate acetate (PMA). PMA stimulation led to slightly increased (two-fold) (p<0.05) DHE-induced fluorescence in AMs, whereas it was greatly increased in Ms and PMNs (13-fold and 113-fold, respectively). The levels of DCFH-DA- and DHR-induced fluorescence were significantly (p<0.05) increased (four-fold and 110-fold, respectively) by PMA stimulation of PMNs, but not of AMs and Ms. Significant differences (p<0.05) in the levels of DHE- and DCFH-DA-induced fluorescence in small and large AMs were also demonstrated. The results show that the potential to increase the generation of various oxidants upon stimulation was: PMNs> Ms>AMs, suggesting that the total oxidative burden of the lungs is dependent on the type of inflammatory cells present, as well as on their state of activation.

Adult↗
PubMed1997

A new method for isolation of smooth muscle cells from human umbilical cord arteries.

A simple method is described for obtaining a large number of single smooth muscle cells by enzymatic digestion of heparin-perfused human umbilical cord arteries. The smooth muscle cell cultures exhibited the characteristic "hill and valley" growth pattern as seen by phase contrast and scanning electron microscopy. By using indirect immunofluorescence or alkaline phosphatase-anti-alkaline phosphatase techniques the cells were identified as smooth muscle cells by the presence of alpha smooth muscle actin and vimentin. The cultures were not contaminated by endothelial cells as demonstrated by the lack of von Willebrand factor immunoreactivity. This method makes it possible to study smooth muscle cells in primary cultures.

Cell Separation↗
PubMed1996

Expression of beta-2-integrins and L-selectin by leukocytes and changes in acute-phase reactants in total hip replacement surgery.

The aim of this study was to characterize the changes in the quantitative expression of beta 2-integrins and L-selectin detected by means of fluorochrome-conjugated monoclonal antibodies and flow cytometry on leukocytes in the systemic circulation after a major musculoskeletal trauma, i.e. hip replacement surgery, and to relate these changes to parameters of the acute-phase response [plasma acute-phase reactants (C-reactive protein, CRP, and interleukin-6, IL-6) and parameters of coagulation activation (thrombin-antithrombin III complexes, TAT)]. Eight patients with either primary or secondary osteoarthritis of the hip received uncemented total hip prostheses. LFA-1 (CD11a/CD18) was upregulated on granulocytes during the operation. MAC-1 (CD11b/CD18) expression on monocytes increased to peak levels 20 h after surgery, whereas the L-selectin (CD62L) expression on monocytes and granulocytes reached peak values at the end of surgery. The changes in expression of LFA-1 on monocytes, MAC-1 on granulocytes and p150,95 (CD11c/CD18) on monocytes and granulocytes during and after the operation did not reach statistical significance. TAT and IL-6 increased during surgery and reached peak values at the end of the operation and 20 h after surgery, respectively. In contrast, CPR concentrations increased after surgery with peak levels 44 h postoperatively. Significant upregulation of LFA-1 on granulocytes and L-selectin on monocytes and granulocytes preceded the increase in IL-6 which again preceded the increase in CRP. However, the up- or downregulation of leukocyte beta 2-integrins and L-selectin during and after surgery was not significantly correlated with the increase in IL-6. The increases in TAT correlated well with the upregulation of L-selectin on monocytes, but not with the beta 2-integrins known to participate in the coagulation process in vitro. The rise in CRP was inversely correlated with the maximal increase in expression of MAC-1 on monocytes. In conclusion, the changes in leukocyte adhesion molecules during and after surgery indicate changes in critical leukocyte functions. The lack of correlation between quantitative up- and downregulation of leukocyte beta 2-integrins and parameters of the acute phase response suggests that these processes are regulated through independent pathways or that functional up- and downregulation of adhesion molecules, shedding, leukocyte-endothelial adhesion and mobilization of new unactivated cells may result in a net estimate of leukocyte activation not suspected to be positively correlated to acute-phase reactants.

Acute-Phase Proteins↗
PubMed1995

Alterations in mucosal morphology and permeability, but no bacterial or endotoxin translocation takes place after intestinal ischemia and early reperfusion in pigs.

Ischemia and reperfusion of the gut may be an important etiological factor in the development of multiple organ failure. We have used a hemorrhagic and a superior mesenteric artery (SMA) occlusion shock model in pigs to estimate the effect of ischemia and reperfusion on intestinal morphology, mucosal permeability, and the occurrence of bacterial or endotoxin translocation. Mucosal ulceration and necrosis were found in the SMA shock model, while the morphological changes were less pronounced in the hemorrhagic shock model. Scanning electron microscopy showed shrinkage of the villi and plugging of the colonic crypts in both shock models. Enterocyte cell kinetics was investigated using 5-bromo-2'-deoksyuridine (BrdU) incorporation and immunovisualization by anti-BrdU antibodies. Cell renewal was almost completely lost from the jejunum to the rectum in both shock models. Intramucosal pH was measured using a tonometer placed in the terminal ileum. Segments of intestinal mucosa were mounted in Ussing chambers, and permeability was measured using radiolabeled probe molecules of differing molecular weights. Augmented molecular flux of inulin (M(r) 5.000) and mannitol (M(r) 182) and loss of short circuit current (Isc) and transepithelial potential difference (PD) were found in mucosae from both shock models. Endotoxin was demonstrated in the ascitic fluid in both shock models; 9.5 (2.7-14.3) (median and 95% confidence interval) EU/mL in the SMA occlusion model and 16.0 (4.9-29.4) EU/mL in the hemorrhagic shock model), but the levels were not significantly higher than in the control model 6.5 (4.3-34.0) EU/mL.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗