Search PubMed⌕ Search

Biomedical subjects

K F Rabe

Publications and source records attributed to K F Rabe.

At least 73 records · Page 4Linked to original sources
PubMed2000

The role of leukotrienes in the regulation of tone and responsiveness in isolated human airways.

Cysteinyl-leukotrienes and histamine are the major determinants of inherent tone in isolated human bronchi, which is mainly the result of a balance of continual production and release of contractile mediator, in particular cysteinyl-leukotrienes and to a lesser extent histamine, and on the other side bronchodilating prostanoids. Cysteinyl-leukotrienes are also powerful constrictors of isolated human airways through direct interaction with Cys-LT1 receptors on airway smooth muscle, and with a potency 1,000-fold higher than histamine. On stimulation inflammatory cells such as eosinophils and mst cells produce and release significantly increased amounts of leukotrienes leading to smooth muscle contration in vitro. In isolated human airways, leukotrienes are the most important mediators of allergen and adenosine-induced contractile responses. The induction of allergen responses in passively sensitized airways is not only related to an increased release of leukotrienes and histamines, but also to an enhanced responsiveness of the airway smooth muscle, particularly to LTC4. Studies in isolated human airways in vitro have demonstrated that understanding the regulation of human airway tone and airway reactivity are closely linked to the understanding of baseline and stimulated production of and smooth muscle responsiveness to leukotrienes in vitro and in vivo.

Airway Resistance↗
PubMed2000

Clinical management of asthma in 1999: the Asthma Insights and Reality in Europe (AIRE) study.

Asthma management guidelines provide recommendations for the optimum control of asthma. This survey assessed the current levels of asthma control as reported by patients, which partly reflect the extent to which guideline recommendations are implemented. Current asthma patients were identified by telephone by screening 73,880 households in seven European countries. Designated respondents were interviewed on healthcare utilization, symptom severity, activity limitations and asthma control. Current asthma patients were identified in 3,488 households, and 2,803 patients (80.4%) completed the survey. Forty-six per cent of patients reported daytime symptoms and 30% reported asthma-related sleep disturbances, at least once a week. In the past 12 months, 25% of patients reported an unscheduled urgent care visit, 10% reported one or more emergency room visits and 7% reported overnight hospitalization due to asthma. In the past 4 weeks, more patients had used prescription quick-relief medication (63%) than inhaled corticosteroids (23%). Patient perception of asthma control did not match their symptom severity; approximately 50% of patients reporting severe persistent symptoms also considered their asthma to be completely or well controlled. The current level of asthma control in Europe falls far short of the goals for long-term asthma management. Patients' perception of asthma control is different from their actual asthma control.

Adult↗
PubMed2000

Regulation of secretory leukocyte proteinase inhibitor (SLPI) production by human bronchial epithelial cells: increase of cell-associated SLPI by neutrophil elastase.

BACKGROUND: To protect against the extracellular activity of serine proteinases, the lung is equipped with serine proteinase inhibitors including secretory leukocyte proteinase inhibitor (SLPI) and elafin. Both SLPI and elafin are locally produced by airway epithelial cells, but the mechanisms that regulate the expression of these proteinase inhibitors are relatively unknown. Previous studies using airway epithelial cell lines indicated that neutrophil elastase (NE) increases SLPI mRNA transcripts while decreasing SLPI protein release. Similar results were observed for elafin. The aim of the present study was to investigate the effect of NE on SLPI and elafin synthesis in cultures of human primary bronchial epithelial cells (PBEC). METHODS: Subcultures of human PBEC were incubated with NE, followed by preparation of cell-free supernatants and cellular lysates and determination of SLPI and elafin protein levels by enzyme-linked immunoadsorbent assay. The effect of NE on SLPI mRNA transcripts was determined by Northern blot analysis. RESULTS: The results showed that NE increased SLPI mRNA expression while decreasing SLPI protein release. This NE-induced decrease was associated with an increase in cell-associated SLPI, providing an explanation for the apparent paradox of increased SLPI mRNA transcripts and decreased SLPI protein levels present in supernatants. In addition, NE had a stimulatory effect on the release of elafin by airway epithelial cells, whereas no increase in cell-associated elafin was observed. CONCLUSIONS: The results from the present study indicate that NE may play a role in the regulation of the antiproteinase screen in the lung and the formation of a protective surface at the epithelial site.

Blotting, Northern↗
PubMed2000

Effect of proinflammatory cytokines on interleukin-8 mRNA expression and protein production by isolated human alveolar epithelial cells type II in primary culture.

Alveolar epithelial cells type II (AEC-II) are ideally situated to regulate the recruitment and activation of different types of cells through the production of chemokines in response to inflammatory stimulation from the alveolar space. We hypothesized that these cells are important producers of interleukin-8 (IL-8) in the lung. This lead us to investigate the capacity of isolated human AEC-II cells to release IL-8 and whether this IL-8 release is regulated by proinflammatory cytokines, i.e. IL-1 beta, TNF-alpha and IFN-gamma. We isolated AEC-II from tumor-free sections of human lungs obtained by pneumectomy and purified the cells by magnetic activated cell sorting. For control experiments the AEC-II-like cell line A549 was used. IL-8 concentration was measured by ELISA in supernatants of unstimulated and LPS-, IL-1 beta-, TNF-alpha- and IFN-gamma- stimulated cells. IL-8 mRNA expression was evaluated by RT-PCR. Spontaneous IL-8 mRNA expression and protein secretion by AEC-II were significantly higher in comparison with A549 cells. TNF-alpha increased both IL-8 mRNA expression and protein production, whereas IL-1 beta slightly increased IL-8 release but did not change mRNA expression in AEC-II. LPS and IFN-gamma did not influence IL-8 expression in AEC-II and A549 cells. These results show considerable differences between A549 cell and AEC-II. The latter are capable of producing IL-8 under the control of proinflammatory cytokines. Our findings demonstrate that the modulation of IL-8 release in AEC-II may have an important impact on the immunoreactivity of these cells during pulmonary inflammation in vivo.

Cells, Cultured↗
PubMed1999

Defensins: key players or bystanders in infection, injury, and repair in the lung?

Antimicrobial peptides have been identified as key elements in the innate host defense against infection. Recent studies have indicated that the activity of antimicrobial peptides may be decreased in cystic fibrosis, suggesting a major role for these peptides in host defense against infection. One of the most intensively studied classes of antimicrobial peptides are defensins. Defensins comprise a family of cationic peptides that in human subjects can be divided into the alpha- and beta-defensin subfamilies. The alpha-defensins are produced by neutrophils and intestinal Paneth's cells, whereas beta-defensins are mainly produced by epithelial cells. Although studies on beta-defensins have so far focused on their antimicrobial activity, studies on alpha-defensins have suggested a role of these peptides in inflammation, wound repair, and specific immune responses. alpha-Defensins, which accumulate in airway secretions of patients with various chronic inflammatory lung disorders, were shown to be cytotoxic toward airway epithelial cells and to induce chemokine secretion in several cell types. Furthermore, the capacity of alpha-defensins to promote bacterial adherence to epithelial cells in vitro further supports a role for these peptides in the pathogenesis of chronic obstructive pulmonary disease and cystic fibrosis. Increased numbers of neutrophils are also present in the airways of patients with asthma, suggesting that neutrophils are involved in the pathogenesis of this disease. Because defensins are able to induce histamine release by mast cells and increase the airway hyperresponsiveness to histamine, it is tempting to speculate that defensins may also contribute to the inflammatory processes in asthma. Besides these proinflammatory effects, alpha-defensins may also display anti-inflammatory activities, including regulation of complement activation and proteinase inhibitor secretion. Finally, defensins may be involved in wound repair because defensins increase epithelial cell proliferation. Thus recent defensin research has revealed potential links between the innate and acquired immune system.

Anti-Infective Agents↗
PubMed1999

Characterization of cell surface lectin-binding patterns of human airway epithelium.

Glycosylated structures on the cell surface have a role in cell adhesion, migration, and proliferation. Repair of the airway epithelium after injury requires each of these processes, but the normal cell surface glycosylation of non-mucin producing airway epithelial cells is unknown. We examined cell surface glycosylation in human airway epithelial cells in tissue sections and in human airway epithelial cell lines in culture. Thirty-eight lectin probes were used to determine specific carbohydrate residues by lectin-histochemistry. Galactose or galactosamine-specific lectins labeled basal epithelial cells, lectins specific for several different carbohydrate structures bound columnar epithelial cells, and fucose-specific lectins labeled all airway epithelial cells. The epithelial cell lines 1HAEo- and 16HBE14o- bound lectins that were specific to basal epithelial cells. Flow cytometry of these cell lines with selected lectins demonstrated that lectin binding was to cell surface carbohydrates, and revealed possible hidden tissue antigens on dispersed cultured cells. We demonstrate specific lectin-binding patterns on the surface of normal human airway epithelial cells. The expression of specific carbohydrate residues may be useful to type epithelial cells and as a tool to examine cell events involved in epithelial repair.

Cell Line, Transformed↗
PubMed1999

Passive sensitization of human airways increases responsiveness to leukotriene C4.

Passive sensitization of human airways in vitro causes increased responsiveness to histamine and induces specific immunoglobulin (Ig)E-dependent contractile responsiveness to allergen. Leukotrienes (LTs) and, to a lesser extent, histamine are the major mediators of allergen-induced contraction. Since it is unclear whether passively sensitized airways are also hyperresponsive to cysteinyl leukotrienes, this study investigated the effect of passive sensitization on LTC4-, in addition to histamine- and allergen-induced contractions in vitro. Bronchial rings from nine nonatopic patients were sensitized overnight with serum containing high levels of total IgE (>250 U x mL(-1)) and allergen-specific IgE against Dermatophagoides farinae (fluorescence allergosorbent test) (FAST class > or =3). The potency (-log10 of the mediator concentration causing a half maximal response (pEC50) of histamine was significantly increased in serum-sensitized tissues compared to nonsensitized controls ((mean+/-SEM) pEC50 5.20+/-0.27 versus 5.64+/-0.18; p=0.02) and maximal contractions were enhanced (877+/-47 versus 543+/-51 mg; p<0.0001). Similarly, the potency of LTC4 was significantly increased in sensitized compared to nonsensitized bronchial rings (pEC50 9.37+/-0.20 versus 8.66+/-0.26; p=0.004); maximal contractions were also enhanced (811+/-57 versus 361+/-86 mg; p<0.0001). These data demonstrate that passive sensitization of human airways induces an increase not only in histamine but also in leukotriene responsiveness. Therefore, it might be speculated that allergen responses in sensitized airways are effected through a combination of increased mediator release from inflammatory cells and increased responsiveness of airway smooth muscle.

Adult↗
PubMed1999

Selective phosphodiesterase inhibitors for the treatment of bronchial asthma and chronic obstructive pulmonary disease.

Theophylline is commonly used in the treatment of obstructive airway diseases. The identification and functional characterization of different phosphodiesterase (PDE) isoenzymes has led to the development of various isoenzyme-selective inhibitors as potential anti-asthma drugs. Considering the distribution of isoenzymes in target tissues, with high activity of PDE3 and PDE4 in airway smooth muscle and inflammatory cells, selective inhibitors of these isoenzymes may add to the therapy of chronic airflow obstruction. However, initial data from clinical trials with selective PDE3 and PDE4 inhibitors have been somewhat disappointing and have tempered the expectations considerably since these drugs had limited efficacy and their use was clinically limited through side effects. The improved understanding of the molecular biology of PDEs enabled the synthesis of novel drugs with an improved risk/benefit ratio. These 'second generation' selective drugs have produced more promising clinical results not only for the treatment of bronchial asthma but also for the treatment of chronic obstructive pulmonary disease.

Asthma↗
PubMed1999

Augmentation of eosinophil degranulation and LTC(4) secretion by integrin-mediated endothelial cell adhesion.

We examined the effect of eosinophil ligation to cultured human umbilical vein endothelial cells (HUVECs) in augmenting the stimulated secretion of leukotriene (LT) C(4) and eosinophil peroxidase (EPO). The effects of adhesion were compared before and after specific blockade with monoclonal antibodies directed against eosinophil surface integrins or endothelial counterligands. Adhesion to HUVECs augmented EPO release caused by formyl-methionyl-leucyl-phenylalanine plus cytochalasin B from 403 +/- 15.3 (BSA control) to 778 +/- 225 ng/10(6) cells for eosinophils exposed to interleukin-1alpha-treated HUVECs (P < 0.05) and also caused a twofold increase in stimulated LTC(4) secretion (P < 0.05). To determine whether augmented secretion resulted directly from adhesive ligation, studies were also performed with paraformaldehyde-treated HUVECs; stimulated secretion of LTC(4) from eosinophils was comparable to that for living HUVECs. Our study is the first demonstration that adhesion to HUVECs through ligation to alpha(4)- or beta(2)-integrin on the eosinophil surface causes augmentation of stimulated secretion of both EPO and LTC(4) and that blockade of adhesion molecules on either eosinophils or HUVECs prevents the priming effect on eosinophil secretion.

Antibodies, Monoclonal↗
PubMed1999

Role of very late adhesion integrins in mediating repair of human airway epithelial cell monolayers after mechanical injury.

Repair of the airway epithelium after injury requires that processes such as adhesion and cell migration occur in a defined order. Both of these processes depend on interactions between extracellular matrix (ECM) proteins and appropriate integrins. To study these interactions, we examined monolayer wound repair in a cultured human airway epithelial cell line, 16HBE14o-. Wounds created in confluent monolayers grown on either collagen-IV, laminin-1, or laminin-2 matrix closed quickly in response to 15 ng/ml epidermal growth factor (EGF). Concurrent treatment of cells grown on each matrix protein with EGF and a monoclonal antibody (mAb) to beta1-integrin inhibited wound closure. Treatment with a mAb to alpha2-, alpha3-, and alpha6-integrin blocked wound repair in monolayers grown on collagen-IV but did not do so in monolayers grown either on laminin-1 or laminin-2. Inhibition was not due to cell detachment or apoptosis. These data demonstrate that integrins expressed by airway epithelial cells mediate wound closure on different constitutive ECM proteins. These data suggest that beta1-integrin subunit function is required to permit migration and spreading of epithelial cells, and that alpha-integrin subunits alone do not mediate migration of epithelial cells grown on either laminin-1 or laminin-2. These differences may become important if the matrix protein composition of airway basement membrane changes in disease states such as asthma.

Antibodies, Monoclonal↗
PubMed1998

Effects of a selective PDE4 inhibitor, D-22888, on human airways and eosinophils in vitro and late phase allergic pulmonary eosinophilia in guinea pigs.

The actions of a novel selective inhibitor of type 4 cyclic nucleotide phosphodiesterase (PDE4), D-22888, on human airway smooth muscle tone and human eosinophil respiratory burst in vitro and bronchoalveolar eosinophilia in allergen-challenged sensitized guinea pigs in vivo were assessed. D-22888 was a selective inhibitor of PDE4, exhibiting an IC50 against human neutrophil PDE4 of 0.15 microM, compared to IC 50 values of 4.4 microM and 1.1 microM for human platelet PDE3 and PDE5, respectively. D-22888 relaxed inherent tone in human bronchial rings in a concentration-dependent manner with an IC50 of 5.0 microM (geometric mean, 95% ci 3.0-8.4 microM) and also caused a concentration-dependent inhibition of opsonized zymosan-induced superoxide anion generation by human eosinophils with an IC50 of 3.1 microM (1.0-9.2 microM). Treatment of actively sensitized guinea pigs with single oral doses of D-22888 2 h before or 4 h after challenge reduced bronchoalveolar lavage (BAL) eosinophil numbers, 24 h after aerosol allergen challenge, by 48% and 73% at 10 mg/kg and 30 mg/kg, respectively, 2 h pre-challenge and 68% at 30 mg/kg 4 h post-challenge. Chronic twice-daily oral dosing with D-22888 for three days caused inhibition of 24 h post-challenge BAL eosinophilia, amounting to 88% at 30 mg/kg. These in vivo actions were comparable with those achieved with other selective PDE4 inhibitors and with the corticosteroid, dexamethasone. We conclude that D-22888 exerts actions on airway smooth muscle and eosinophil recruitment and activation that suggest that D-22888 may be a promising new drug for use in the treatment of allergic obstructive airways>> diseases such as bronchial asthma.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

Cyclic nucleotide phosphodiesterase in human bronchial epithelial cells: characterization of isoenzymes and functional effects of PDE inhibitors.

Cyclic AMP (adenosine 3':5'-cyclic monophosphate, cAMP) is an intracellular second messenger that mediates the actions of endogenous hormones and neurotransmitters and also of drugs such as beta-adrenoceptor agonists. The presence of functional beta-adrenoceptors on human airway epithelial cells has been demonstrated but the expression of the cAMP-metabolizing enzyme, cyclic nucleotide phosphodiesterase (PDE) in these cells has not been studied. We investigated the profile of activity of the different PDE isoenzymes in lysates of a pulmonary epithelial cell line, A549, and of human bronchial epithelial (HBE) cells grown in primary culture. The effects of non-selective and isoenzyme-selective PDE inhibitors on beta-agonist-induced elevations in intracellular cAMP concentrations and the production of interleukin (IL) 8 and prostaglandin (PG) E2 was also investigated. A549 cells expressed a high level of PDE4, lower levels of PDE1 and PDE3, and minor PDE5 activity. Primary HBE cultures expressed PDE4 and PDE1 activity at approximately equal levels with small additional PDE3 and PDE5 activities. The total PDE activity of the HBE cells was approximately nine-fold lower than that of A549 cells. The beta-adrenoceptor agonist salbutamol, caused a slow, concentration-dependent increase in intracellular cAMP levels in HBE cells which was not affected by a non-selective PDE inhibitor, IBMX (100 microM), or by a selective PDE4 inhibitor, rolipram (100 microM). Zardaverine, a dual-selective PDE3/PDE4 inhibitor, had no effect on cAMP levels at 10 microM but did cause a significant enhancement of salbutamol-induced elevations at 100 microM (150+/-36 pmol/10(5) cells at 10 microM salbutamol vs. 64+/-25 pmol/10(5) cells in the absence of zardaverine; n=3,P<0.01). Neither basal nor tumour necrosis factor alpha (10 ng/ml)-induced IL8 secretion was affected by salbutamol (10 microM) in the absence or presence of IBMX (100 microM). Salbutamol (10 microM), alone or in the presence of IBMX (100 microM) or rolipram (100 microM), also failed to affect basal or bradykinin (1 microM)-induced PGE2 release. Zardaverine (100 microM) caused a significant increase in basal PGE2 release but this was not enhanced in the presence of salbutamol (10 microM) and was not related to changes in cAMP levels. We conclude that HBE cells express a low total PDE activity, made up predominantly of PDE1 and PDE4 isoenzymes, and that intracellular cAMP levels in HBE cells are not related to the production of IL8 or PGE2.

Arachidonic Acid↗
PubMed1998

The relevance of resting tension to responsiveness and inherent tone of human bronchial smooth muscle.

1. In the present study the effects of resting tension on isometric responses of human airway smooth muscle to contractile and relaxant stimuli were investigated. Also, its effects on inherent smooth muscle tone were examined, in an effort to determine a pre-defined resting tension which can be considered optimal for in vitro studies. 2. Bronchial ring preparations (2-4 mm internal diameter) were suspended in tissue baths at a range of levels of resting tension (200-1600 mg). The responses to electrical field stimulation (EFS, 30 V, 0.2 ms, 8-30 Hz), carbachol (3 microM), isoprenaline (1 microM) and the 5-lipoxygenase inhibitor, zileuton (10 microM) were investigated along with the ability of the preparations to recover stable resting tension after 60 min of washing post challenge. 3. EFS induced monophasic contractions at low stimulation frequency (8 Hz). However, with increasing frequency and tension (15 and 30 Hz; > 400 mg) contractile responses were accompanied by a relaxant component. The magnitude of contractile responses increased with increasing resting tension to a plateau at between 500 and 700 mg. Relaxant responses when present, increased in magnitude with increasing resting tension. 4. The level of resting tension did not significantly alter responses to carbachol, but tissues at tensions > or = 1000 mg showed poor tension recovery after washing. Isoprenaline-induced relaxations increased with increasing resting tension (P<0.05) and tension recovery after washing was complete. The 5-lipoxygenase sensitive portion of the tension (33+/-4%) was not altered by the level of resting tension. 5 These results suggest that in human bronchial ring preparations of 2-4 mm internal diameter, resting tensions within the range 400-1000 mg could be considered optimal for isometric tension recordings of protocols involving both contraction and relaxation procedures.

Adult↗
PubMed1998

Histamine hypersensitivity induced by passive sensitization of human bronchus: effect of serum IgE depletion.

BACKGROUND: Sensitivity to specific allergens and increased sensitivity to common spasmogens are characteristic features of allergic asthma and are also features demonstrated by tissues passively sensitized with serum from atopic donors, displaying high levels of IgE. It is evident that the specific response to allergen is related to circulating levels of allergen-specific IgE, but it is unclear whether the histamine hypersensitivity is also related to this immunoglobulin. OBJECTIVE: The objective was to deplete IgE in the serum of a donor with high levels of total and allergen-specific IgE and compare specific-allergen sensitivity and sensitivity to histamine in tissues passively sensitized with either the whole serum or the IgE-depleted serum. METHODS: Serum from a Dermatophagoides farinae-sensitive asthmatic (total IgE = 1047 U/mL, D. farinae-specific IgE > 17.5 U/mL) was subjected to an immunomagnetic separation technique to reduce the levels of IgE (total and specific) to below 10 U/mL. Bronchial tissue from six non-atopic donors was then passively sensitized overnight with either the whole serum or IgE-depleted serum and D. farinae and histamine sensitivity were evaluated the next day using standard organ bath techniques. RESULTS: Passive sensitization with the whole serum resulted in the development of sensitivity to D. farinae and increased sensitivity to histamine (750+/-169 mg contraction to 10 U/mL D. farinae, histamine pEC50 5.64+/-0.16 and max. 813+/-109 mg in sensitized vs 37+/-34 mg contraction to 10 U/mL D. farinae histamine pEC50 5.05+/-0.23 and max. 490+/-84 in non-sensitized tissues, P>0.05). Incubation with IgE-depleted serum still produced histamine hypersensitivity (histamine pEC50 5.57+/-0.16 and max. 737+/-70 mg P>0.05), but no significant response to allergen was detected (20+/-13 mg contraction to 10 U/mL D. farinae). CONCLUSION: These results demonstrate, that increased reactivity to histamine and airway contraction to allergen induced by passive sensitization, occur through independent mechanisms and that, unlike allergen-sensitivity, histamine hypersensitivity is caused by a serum factor other than IgE.

Adolescent↗
PubMed1998

Inhibition of human airway sensitization by a novel monoclonal anti-IgE antibody, 17-9.

We investigated the effect of a novel mouse IgG2b nonanaphylactogenic anti-human IgE antibody, 17-9, on allergen and histamine responses in passively sensitized human airways in vitro to determine the specific contribution of IgE to the sensitization process. Bronchial rings were sensitized with serum containing high levels of allergen-specific IgE (Dermatophagoides farinae), or with a hapten-specific chimeric humanized IgE (JW8). There was a concentration-dependent contraction of serum-sensitized bronchial rings to D. farinae (517 +/- 188 mg tension at 10 U/ml, n = 8) that was not observed in nonsensitized controls. This response was practically abolished when tissues were sensitized in the presence of 100 microg/ml anti-IgE antibody 17-9 (54 +/- 20 mg). In tissues sensitized with the anti-NIP IgE, JW8, there was a concentration-dependent contraction to the specific antigen NIP-BSA (560 +/- 154 mg at 0.3 microg/ml, n = 5) that was not observed in nonsensitized control subjects and that was substantially inhibited when 17-9 was present in the sensitization buffer (124 +/- 109 mg). The inhibition with 17-9 was specific, as pretreatment with a non-IgE-specific IgG2b antibody did not affect allergen responses. Potency and maximal contractions to histamine in serum-sensitized tissues were significantly elevated compared with nonsensitized controls; this was not affected by the presence of 17-9 during sensitization (pEC50 = 5.1 +/- 0.2 versus 5.0 +/- 0.3 in tissues sensitized in the absence of 17-9). In tissues sensitized with JW8 there was no significant increase in responsiveness to histamine. We conclude that allergen responses in sensitized human airways are dependent on IgE levels in the sensitizing serum while nonspecific (hyper)responsiveness depends on serum factors other than IgE. Nonanaphylactogenic anti-human IgE antibodies effectively inhibit allergen responses of human airways in vitro but may not affect other factors inducing hyperresponsiveness.

Aged↗