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Biomedical subjects

S I Rennard

Publications and source records attributed to S I Rennard.

At least 19 recordsLinked to original sources
PubMed1995

NIH conference. Airway inflammation.

Diseases characterized by airway inflammation, excessive airway secretion, and airway obstruction affect a substantial proportion of the population. These diseases include asthma, chronic bronchitis, bronchiectasis, and cystic fibrosis. Asthma and chronic bronchitis may affect 25 million persons in the United States. Much progress has been made in the last decade toward an understanding of the mechanisms underlying chronic airway inflammation; recent work has resulted in several new concepts of the initiation and maintenance of airway inflammation. Airway production of chemokines, cytokines, and growth factors in response to irritants, infectious agents, and inflammatory mediators may play an important role in the modulation of acute and chronic airway inflammation. Lipid mediators may be produced by resident airway cells and by inflammatory cells; production of these mediators may also be altered by inflammatory cytokines. Increased airway obstruction may be related to intercurrent viral respiratory infection and to the induction of airway inflammation and airway hyperreactivity that results from such infection. Furthermore, several models exist to explain the processes by which airway inflammation is perpetuated in diseases such as asthma and chronic bronchitis. These include neurogenic inflammation, the perpetuation of the acute inflammatory response, and cycles of airway epithelial cell-mediated and inflammatory cell-mediated recruitment and activation of inflammatory cells. An understanding of these mechanisms of airway inflammation may provide the clinician with new therapeutic approaches to the treatment of these common and chronic diseases.

Bronchi↗
PubMed1995

Induction of bovine bronchial epithelial cell filopodia by tetradecanoyl phorbol acetate, calcium ionophore, and lysophosphatidic acid.

The morphological responses of primary bovine bronchial epithelial cells (BBECs) cultured in serum-free medium to protein activators have been examined. When attached to type I collagen-coated tissue culture dishes, the cells responded to tetradecanoyl phorbol acetate (TPA), calcium ionophore A23187, and lysophosphatidic acid (LPA) by extruding filopodia. In contrast, no morphological changes were elicited by exposures to either epinephrine or dibutyryl-cAMP. Formation of filopodia was accompanied by actin filament reorganization as demonstrated by staining with labeled phalloidin. Exposures to varied TPA concentrations for 2 h showed maximal stimulation of filopodial extrusions at 10 nM TPA with half-maximal stimulation at 1 nM. Time-course measurements with 10 nM TPA showed filopodia formation within 30 min of exposure, with 85% of the BBECs being filopodia positive after 5 h. Filopodia induction in 20-30% of the cells could be achieved by 1-100 microM LPA concentrations. BBECs acquired increasing resistance to TPA-induced filopodia during the initial 5 days in culture; however, responsiveness to TPA was regenerated by mild treatment with trypsin. Inclusion of fibronectin or vitronectin into the attachment matrix had no effects on the rates or extent of TPA-induced filopodia formation.

Actins↗
PubMed1995

Cigarette smoke stimulates release of neutrophil chemotactic activity from cultured bovine bronchial epithelial cells.

1. Recruitment of neutrophils into the airway is a prominent feature of chronic bronchitis, a syndrome often associated with exposure to cigarette smoke. Since bronchial epithelial cells are the 'first' lung cells to come into contact with smoke, these cells may be responsible for neutrophil recruitment into the airway by release of neutrophil chemotactic activity in response to cigarette smoke. 2. To evaluate this hypothesis, we prepared bovine bronchial epithelial cells and measured their ability to release neutrophil chemotactic activity following exposure to cigarette smoke. Bronchial epithelial cells were prepared by overnight digestion with protease, filtered through 100-microns Nitex mesh and resuspended in Dulbecco's modified Eagle medium supplemented with 10% fetal calf serum and antibiotics and cultured at 2 x 10(6) cells in 2 ml of medium in 35-mm culture dishes. After 4 days, dishes were rinsed and refed with medium without fetal calf serum and incubated with and without 1:10 diluted smoke extract for 6 h at 37 degrees C. The neutrophil chemotactic activity of the supernatant fluids was measured by the blindwell chamber technique. 3. Cigarette smoke itself added to medium did not stimulate chemotaxis. In contrast, cigarette smoke did stimulate the release of neutrophil chemotactic activity from bovine bronchial epithelial cells [15 +/- 3 (control) versus 74 +/- 5 (smoke), P < 0.01]. 4. This neutrophil chemotactic activity was dialysable, pepsin and acid stable, heat sensitive and lipid extractable. Sephadex G-75 column chromatography demonstrated two peaks of neutrophil chemotactic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Bovine herpesvirus-1 infection reduces bronchial epithelial cell migration to extracellular matrix proteins.

Repair of airway epithelium after viral infection involves migration of epithelial cells to cover injured, denuded areas. We determined whether viral infection reduces the capability of bronchial epithelial cells to migrate and to attach to extracellular matrix proteins. Inoculation of bovine bronchial epithelial cells in vitro with bovine herpesvirus-1 reduced their ability to migrate in two different assays of cell migration. When attachment assays were performed, fewer cells attached to both control wells and matrix protein-precoated wells, suggesting that general mechanisms of adherence to substrates were altered by viral infection. Focal contact points of epithelial cells with the underlying matrix were evaluated with epifluorescence microscopy and monoclonal antibodies to vinculin and alpha v, an integrin chain. Disruption of focal contact points was seen early after infection and was prevented by an inhibitor of viral DNA polymerase, phosphonoacetic acid. Cycloheximide did not cause similar disruptions of focal contacts at early time points. Viral infection thus has marked effects on the interactions of bronchial epithelial cells with extracellular matrix and the organization of matrix to cytoskeleton links. The effects appear to be dependent in part on viral replication in the cells and are not simply due to reductions in host cell protein synthesis.

Animals↗
PubMed1995

Insulin modulation of bronchial epithelial cell fibronectin in vitro.

Fibronectin (Fn) is involved in the migration of epithelial cells in re-epithelialization of wounds. Epithelial cell-derived Fn is particularly potent as a chemotactic factor for bronchial epithelial cells (BECs) in vitro. Thus modulation of airway epithelial cell Fn may be a key aspect of airway repair. Insulin is both an important growth factor and known chemotactic factor for cultured BECs. We postulated that insulin may modulate Fn production of cultured BECs. We examined this hypothesis utilizing bovine BECs in culture with serum-free media with and without insulin. BECs grown in media without insulin released more Fn into culture supernatants and contained more Fn in cell layers than cells grown with insulin. Labeling of cells with [35S]methionine demonstrated an increase in new protein production and Fn mRNA expression was increased. Increased Fn in BEC cultures without insulin was associated with an increase in active transforming growth factor-beta (TGF-beta) release as measured by a standard bioassay. Increased BEC Fn in cultures without insulin was partially inhibited by exposure of cultures to TGF-beta antibody. Thus insulin appears to modulate BEC Fn production in vitro in part through a TGF-beta-dependent mechanism. Insulin may be involved in airway repair mechanisms through modulation of epithelial cell Fn production.

Animals↗
PubMed1995

Effects of cigarette smoke extract on bovine bronchial epithelial cell attachment and migration.

The repair of injured epithelium involves a complex interaction between epithelial cells and the underlying extracellular matrix. We studied the effects of sublethal concentrations of cigarette smoke extract (CSE) and two volatile components of cigarette smoke, acetaldehyde and acrolein, on bovine bronchial epithelial cell (BBEC) attachment and migration in vitro. After short-term exposure (2 and 6 h) to CSE, BBEC attachment to fibronectin-coated dishes was decreased, and migration to fibronectin was unchanged. After a longer period of exposure, 24 h, attachment was increased and migration was unchanged. Exposure to a peptide containing the amino acid sequence arginine-glycine-aspartic acid (RGD) reduced attachment equally well for control and smoke-exposed cells. BBEC sheet migration was reduced over 72 h after exposure to CSE. Acrolein reduced BBEC migration to fibronectin but had no effect on attachment. Acetaldehyde had no effect on either attachment or migration. We conclude that exposure to CSE has important effects on bronchial epithelial cell migration and attachment, and that these effects change over time.

Acetaldehyde↗
PubMed1995

Bradykinin stimulates bronchial epithelial cells to release neutrophil and monocyte chemotactic activity.

In the present investigation, we evaluated the potential of bradykinin (BK), histamine, and serotonin to induce the release of neutrophil and monocyte chemotactic activity (NCA and MCA) from bronchial epithelial cells (BEC). BK significantly stimulated BEC to release NCA and MCA in a dose- and time-dependent manner. Histamine weakly but significantly induced the release of both NCA and MCA in a similar fashion. Serotonin did not stimulate BEC. Checkerboard analysis showed that the NCA and MCA released in response to BK were chemotactic. Molecular-sieve column chromatography by Sephadex G-75 revealed that BK induced a single low-molecular-weight peak (approximately 400 Da) for both NCA and MCA. The releases of NCA and MCA in response to BK and histamine were inhibited by lipoxygenase inhibitors (P < 0.01). The released NCA was inhibited by leukotriene B4 (LTB4) receptor antagonist (P < 0.01) and was slightly inhibited by platelet-activating factor receptor antagonist. LTB4 was increased in BK-stimulated BEC supernatant (P < 0.01). BK B2-receptor antagonist attenuated the release of NCA and MCA. These data suggest that BK and histamine may stimulate BEC to release NCA and MCA and may modulate neutrophil and monocyte recruitment into the airways in patients with asthma.

Animals↗
PubMed1995

Cigarette smoke inhibits lung fibroblast proliferation and chemotaxis.

Cigarette smoking is the most clearly recognized cause of pulmonary emphysema. Since loss of lung tissue, which characterizes emphysema, represents a balance between injury and repair, we hypothesized that cigarette smoke might contribute to the development of emphysema by inhibiting fibroblast proliferation and migration. To evaluate this, we examined the effect of cigarette smoke extract (CSE) on the proliferation and migration of human lung fibroblasts in vitro. CSE inhibited fibroblast proliferation and migration at noncytotoxic concentrations. When CSE was treated to remove volatile components, it showed less inhibitory activity on fibroblast proliferation. Therefore, we also examined acrolein and acetaldehyde, which are volatile components of cigarette smoke, Micromolar concentrations of acrolein and millimolar concentrations of acetaldehyde induced significant inhibition of fibroblast proliferation. In contrast, removal of volatile components did not eliminate the inhibitory activity of CSE for fibroblast migration, although acetaldehyde and acrolein alone were also capable of inhibiting chemotaxis. Cigarette smoke-induced inhibition of fibroblast proliferation and migration may impair lung repair following lung injury, and may thus contribute to the development of pulmonary emphysema.

Acetaldehyde↗
PubMed1995

Modulation of fibroblast type I collagen and fibronectin production by bovine bronchial epithelial cells.

To elucidate bronchial epithelial cell (BEC)-fibroblast interactions with regard to extracellular matrix production, bovine BECs were cultured, and conditioned media were assayed for their effects on fibroblast extracellular matrix production. Bovine BECs were prepared by protease digestion and grown in serum-free medium. When confluent, 48-h conditioned medium (CM) was collected and added to confluent human fetal lung fibroblasts (HFL-1) with 10 micrograms/ml ascorbic acid every other day. Type I collagen and fibronectin production from fibroblasts were quantified by enzyme-linked immunosorbent assay. Fifty percent BEC CM caused an increase in type I collagen (582 +/- 92 pg/10(3) cells/h versus 220 +/- 42, P < 0.001) and in fibronectin (1,422 +/- 60 pg/10(3) cells/h versus 360 +/- 24, P < 0.001) production after 4 days. These observations were confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography in HFL-1 cultures labeled with [14C]proline. Dose-dependent stimulation was observed in response to BEC CM. Stimulation of macromolecule release was accompanied by increased steady-state fibronectin and alpha 1 (I) collagen mRNA levels. Sephadex G-150 column chromatography of BEC CM revealed two distinct peaks of activity at approximate molecular weights of 25 kD and > 66 kD. Transforming growth factor beta (TGF-beta)-neutralizing antibody blocked the activity of both peaks, suggesting that TGF-beta produced by the epithelial cells may drive fibroblast matrix production and that a TGF-beta binding substance may be present, or that TGF-beta aggregation may occur. Because some partially purified preparations had increased stimulatory activity compared to crude supernatants, potential inhibitors of matrix production were also sought.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Calcium and protein kinase C dependency of lipoxygenase-derived neutrophil chemotactic activity release from bronchial epithelial cells.

In the present investigation, we evaluated the roles of calcium, calcium-calmodulin, inositol turnover, and protein kinase C in the release of lipoxygenase-derived metabolites with neutrophil chemotactic activity (NCA) from bronchial epithelial cells (BECs) in response to endotoxin (ETX) and opsonized zymosan (OZ). Both ETX and OZ stimulated BECs to release NCA [56.9 +/- 5.1 (ETX), 65.2 +/- 5.1 (OZ) versus 15.2 +/- 3.0 (controls) cells/high power field, P < 0.001]. The lipoxygenase inhibitors, nordihydroguaiaretic acid and diethylcarbamazine, and phospholipase A2 inhibitors, mepacrine and dibucaine, blocked the release of NCA in response to ETX, OZ, calcium ionophore A23187 (A23187), and phorbol myristate acetate (PMA). The calcium channel blockers, nifedipine and verapamil, and two putative inhibitors of calcium release from intracellular storage sites, 8-(N,N-diethylamine)-octyl-3,4,5-trimethoxybenzoate hydrochloride and ruthenium red, inhibited the release of NCA induced by ETX but had little effect on the release of NCA induced by OZ. However, depletion of extracellular calcium inhibited the release of NCA in response to both ETX and OZ. Calmodulin inhibitors, compound 48/80 and N-(6-aminohexyl)-1 naphthalenesulfonamide (W-7), inhibited the release of NCA in response to a variety of endotoxin concentrations. Lithium chloride, an inositol turnover inhibitor, inhibited the release of NCA in response to both ETX and OZ, but less attenuation was observed in the response to OZ. A protein kinase C inhibitor, dihydrosphingosine, inhibited the release of NCA in response to both ETX and OZ. Finally, A23187 and PMA stimulated the release of NCA and [3H]arachidonic acid independently and additively. These data suggest that the release of NCA from BECs in response to OZ may be predominantly mediated by inositol turnover and protein kinase C and that the release of NCA in response to ETX may be regulated by calcium influx and calcium release from intracellular storage sites, calcium-calmodulin activation, inositol turnover, and protein kinase C activation. Protein kinase C augmented the release of NCA and [3H]arachidonic acid independent of and in combination with calcium. These results may suggest the calcium and protein kinase C dependency of the release of NCA from BECs.

Animals↗
PubMed1995

Immunological functions of the pulmonary epithelium.

The mature pulmonary epithelium forms a continuous lining to the airspace. Recent data suggest that this specialized epithelium may also contribute to host defence via interactions with inflammatory cells. Pulmonary epithelial cells can serve as part of the local immune system, providing structures and functions crucial for the maintenance of normal pulmonary function. This article will briefly review the morphology and development of the pulmonary epithelial cells, their function with regard to host defence, alterations of the pulmonary epithelium associated with airway diseases, and potential therapeutic implications for the treatment of respiratory diseases.

Epithelium↗
PubMed1995

Combined occurrence of chyloperitoneum and chylothorax after retroperitoneal surgery.

Chyloperitoneum is a rare complication of abdominal or retroperitoneal surgery, and the combined occurrence of chylothorax and chyloperitoneum has been reported in only a few cases. We describe a case of this complication, which became clinically apparent 20 days after a Warren shunt operation. The large chylous effusion compromised breathing and required chest tube drainage, pleurodesis, medium chain triglyceride (MCT) diet, and, later, total parenteral nutrition (TPN). The patient made a full recovery on TPN for 5 weeks.

Adult↗
PubMed1995

Neutrophilic respiratory tract inflammation and peripheral blood neutrophilia after grain sorghum dust extract challenge.

STUDY OBJECTIVE: To determine if inhalation of grain sorghum dust in the laboratory would cause neutrophilic upper and lower respiratory tract inflammation in human volunteers, as well as systemic signs of illness. DESIGN: Prospective. SETTING: University of Nebraska Medical Center. PARTICIPANTS: Thirty normal volunteers. INTERVENTIONS: Inhalation challenge with 20 mL of a nebulized solution of filter-sterilized grain sorghum dust extract (GSDE). One group received prednisone, 20 mg for 2 days, prior to the challenge. MEASUREMENTS AND RESULTS: Bronchoscopy with bronchoalveolar lavage (BAL) was performed 24 h after challenge, with samples collected as bronchial and alveolar fractions. Findings included visible signs of airways inflammation, quantified as the bronchitis index. The percentage of bronchial neutrophils was significantly increased in those challenged with GSDE vs the control solution, Hanks' balanced salt solution (40.3 +/- 4.5% vs 14.3 +/- 5.1%, p < or = .01). Similar findings were seen in the alveolar fraction. Pretreatment with corticosteroids did not prevent the rise in neutrophils recovered by BAL. Peripheral blood neutrophils were also increased in volunteers challenged with the grain dust extract. To explain the increase in peripheral blood neutrophil counts, the capacity of the peripheral blood neutrophils to migrate in chemotaxis experiments was examined. The results demonstrate an increase in peripheral blood neutrophils and an increase in chemotactic responsiveness. CONCLUSIONS: Inhalation challenge with a grain dust extract causes respiratory tract inflammation and a peripheral blood neutrophilia. One reason for this may be an increase in activated peripheral blood neutrophils.

Adult↗
PubMed1995

Conversion from twice- to once-daily extended-release theophylline treatment in patients with reversible airway obstruction.

This multicenter, randomized, investigator-blinded, parallel group study compared the effects of converting patients from a q12h extended-release theophylline preparation (Theo-Dur) to a q24h extended-release product (Uni-Dur). Patients (n = 133) first received open-label Theo-Dur treatment with dosage titrated to achieve peak serum theophylline concentrations of 10-20 micrograms/ml. Patients then were randomized to continue Theo-Dur (n = 64) or to convert to Uni-Dur (n = 60) with peak serum theophylline concentrations maintained in the desired range. Pulmonary function tests were performed during the open-label and blinded periods; patients maintained diaries and performed peak flow measurements before each dose of study treatment. Adverse events were recorded throughout the study. Respiratory status during blinded treatment was rated as the same or improved compared with open-label treatment by > 87% of evaluable patients and physicians, regardless of treatment group. There were no significant differences in mean peak serum theophylline concentrations at baseline, at the final evaluation, or at any point during the study. Few dosage adjustments were necessary (5/52, Uni-Dur; 9/57, Theo-Dur). There were no significant changes in pulmonary function test results or patient diary entries between the open-label and blinded periods. Headache and nausea were the most commonly reported adverse events. In conclusion, converting patients from twice- to once-daily theophylline treatment resulted in no significant changes in any measures of pulmonary function, and there were no significant differences between the groups during the blinded treatment period.

Adult↗
PubMed1995

Lysophosphatidic acid regulation of cyclic AMP accumulation in cultured human airway smooth muscle cells.

The effects of the simple bioactive lipid mediator lysophosphatidic acid (LPA) on cAMP accumulation were investigated in cultured human airway smooth muscle cells (ASMC). Pretreatment of cells with LPA induced an increase in subsequent stimulation of cAMP accumulation by forskolin and by isoproterenol. When included during the assay of cAMP accumulation rather than as a pretreatment, LPA inhibited forskolin stimulation but enhanced isoproterenol stimulation. Both effects of LPA on forskolin stimulation were completely blocked by pertussis toxin treatment, whereas the effects on isoproterenol stimulation appeared relatively insensitive to pertussis toxin. The protein kinase C activator phorbol-12-myristate-13-acetate (PMA) sensitized forskolin stimulation to a similar extent as did LPA, and the combination of LPA plus PMA caused markedly more sensitization than either agent alone. In contrast, PMA inhibited isoproterenol stimulation and markedly decreased the sensitization induced by LPA. Serum also induced sensitization, and sensitization by LPA plus serum was no greater than that with LPA alone. LPA-induced sensitization appeared to be independent of protein kinase C activation because it was unchanged in cells treated to down-regulate protein kinase C. LPA also stimulated polyphosphoinositide hydrolysis, and this stimulation was partially inhibited by pertussis toxin treatment. These results suggest that LPA activates receptors coupled to both the pertussis toxin-sensitive G protein Gi and the pertussis toxin-insensitive G protein Gq. The complex effects of LPA, PMA, and pertussis toxin on cAMP accumulation in these cells are consistent with the expression of the type 2 isozyme of adenylyl cyclase in these cells.

Cells, Cultured↗