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Biomedical subjects

J R Spurzem

Publications and source records attributed to J R Spurzem.

At least 37 records · Page 2Linked to original sources
PubMed1998

Human bronchial epithelial cells modulate collagen gel contraction by fibroblasts.

Connective tissue contraction is an important aspect of both normal wound healing and fibrosis. This process may contribute to small airway narrowing associated with certain airway diseases. Fibroblast-mediated contraction of a three-dimensional collagen gel has been considered a model of tissue contraction. In this study, the ability of primary cultured human bronchial epithelial cells (HBEC) obtained by bronchial brushings to modulate fibroblast gel contraction was evaluated. Human lung fibroblasts (HFL1) were cast into type I collagen gels. The gels were floated both in dishes containing a monolayer of HBEC or in dishes without HBEC. Contraction assessed by measuring the area of gels was increased at all time points from 24 h up to 96 h of coculture. At 48 h, coculture of HBEC with fibroblasts resulted in significantly more contraction than fibroblasts alone (36.6 +/- 1.2 vs. 20.4 +/- 1.7%, P < 0.05). Lipopolysaccharide (LPS, 10 micrograms/ml) stimulation of the HBEC augmented the contraction (44.9 +/- 1.0%, P < 0.05 vs. HBEC). In the presence of indomethacin, the augmentation by LPS was increased further (52.2 +/- 4.3%, P < 0.05 vs. HBEC with LPS), suggesting that prostaglandins (PGs) are present and may inhibit contraction. Consistent with this, PGE was present in HBEC-conditioned medium. Bronchial epithelial cell conditioned medium had an effect similar to coculturing. SG-150 column chromatography revealed augmentive activity between 20 and 30 kDa and inhibitory activity between 10 and 20 kDa. Measurement by enzyme-linked immunosorbent assay confirmed the presence of the active form of transforming growth factor (TGF)-beta 2. The stimulatory activity of conditioned medium was blocked by adding anti-TGF-beta antibody. These data demonstrate that, through the release of factors including TGF-beta 2 which can augment and PGE which can inhibit, HBEC can modulate fibroblast-mediated collagen gel contraction. In this manner, HBEC may modulate fibroblast activities that determine the architecture of bronchial tissue.

Animals↗
PubMed1998

Cigarette smoke extract inhibits fibroblast-mediated collagen gel contraction.

Cigarette smoking, the major cause of pulmonary emphysema, is characterized by destruction of alveolar walls. Because tissue destruction represents a balance between injury and repair, we hypothesized that cigarette smoke exposure may contribute to the development of emphysema through the inhibition of tissue contraction during the repair process. To partially evaluate this hypothesis, we investigated the effects of cigarette smoke extract (CSE) on the ability of cultured fibroblasts to mediate collagen gel contraction in vitro: CSE inhibited fibroblast-mediated gel contraction in a concentration-dependent manner (P < 0.01). Production of prostaglandin E2, a known inhibitor of fibroblast contraction, was unchanged by CSE as was cell surface integrin expression. In contrast, fibronectin production by fibroblasts was inhibited (P < 0.01), and addition of exogenous fibronectin partially restored the contractile activity, thus suggesting at least one mechanism to explain inhibition of gel contraction by CSE. When CSE was treated to remove volatile components, it showed less inhibitory activity on fibroblast-mediated gel contraction. Therefore, we also examined the effects of acrolein and acetaldehyde, two volatile components of cigarette smoke. Inhibition of contraction was observed at 5 microM acrolein and at 0.5 mM acetaldehyde. In conclusion, cigarette smoke inhibited fibroblast-mediated gel contraction, and this inhibition was due, at least in part, to the volatile components of cigarette smoke and may be mediated, at least in part, by a decrease in fibroblast fibronectin production. By inhibition of repair, these smoke components may contribute to the development of pulmonary emphysema.

Cell Survival↗
PubMed1998

Regulation of ciliary beat frequency by both PKA and PKG in bovine airway epithelial cells.

Ciliary beating is required for the maintenance of lung mucociliary transport. We investigated the role of cyclic nucleotide-dependent protein kinases in stimulating ciliary beat frequency (CBF) in bovine bronchial epithelial cells (BBECs). cAMP-dependent protein kinase (PKA) activity and cGMP-dependent protein kinase (PKG) activity were distinguished after DEAE-Sephacel chromatography of BBEC extracts. cAMP levels and PKA activity are increased in BBECs stimulated with 0.01-1 mM isoproterenol, with a corresponding increase in CBF. cGMP levels and PKG activity are increased in BBECs stimulated with 0.1-10 microM sodium nitroprusside, with a corresponding increase in CBF. Direct protein kinase-activating analogs of cAMP and cGMP (dibutyryl cAMP and 8-bromo-cGMP, respectively) also activate their specific kinases and stimulate CBF. Preincubation of BBECs with inhibitors of PKA or PKG [KT-5720 or Rp-8-(p-chlorophenylthio)-guanosine 3',5'-cyclic monophosphothioate] results in the inhibition of specific kinase activity as well as in the inhibition of CBF. These studies suggest that the activation of either PKA or PKG can lead to the stimulation of CBF in bovine airway epithelium.

Animals↗
PubMed1997

Selective migration of alpha-smooth muscle actin-positive myofibroblasts toward fibronectin in the Boyden's blindwell chamber.

1. In order to address the hypothesis that migrating fibroblasts have a different phenotype, human fetal lung fibroblasts (HFL-1) cells were evaluated in the Boyden blindwell chamber migration assay followed by immunoelectron microscopy. 2. HFL-1 cells were placed on nucleopore filters and incubated for 2 h using purified human plasma fibronectin (pFn) as a chemoattractant. Filters were then processed for immunoelectron microscopy using antibodies for alpha-smooth muscle (alpha-SM) actin as a marker for myofibroblasts, cellular fibronectin (cFn) and VLA-5. 3. Cells which had migrated to the bottom side of the filter were more likely to express alpha-SM actin, 29.1 +/- 3.4% of cells, compared with cells which did not migrate through the filter, 12.4 +/- 1.3% (P < 0.05). The total proportion of alpha-SM-actin-positive cells located on both sides of the filter showed no difference between those which had migrated toward pFn and controls (17.7 +/- 1.0% compared with 20.2 +/- 2.5%). 4. cFn-positive cells showed minimal differences compared with control cells, while perinuclear and endoplasmic reticulum staining of VLA-5 was observed only in the cells treated with pFn. 5. The results show that HFL-1 cells are heterogenous for alpha-SM actin expression. Short-term incubation with pFn did not change the proportion of alpha-SM-actin-positive HFL-1 cells. Cells which migrate, however, are enriched for alpha-SM actin expression. pFn-induced fibroblast chemotaxis can selectively recruit myofibroblasts with increased alpha-SM actin expression, a feature which may contribute to the altered population of cells at sites of fibrosis.

Actins↗
PubMed1997

Cell-matrix and cell-cell interactions modulate apoptosis of bronchial epithelial cells.

Apoptosis is an important process maintaining cell number and tissue structure. To determine whether cell-extracellular matrix (ECM) and cell-cell interactions modulate apoptosis in bronchial epithelium, we cultured human bronchial epithelial cells in different conditions and evaluated the cells for apoptosis. We found that plating cells in conditions that prevent cell-ECM adhesion induced apoptosis. Plating cells on type I collagen, fibronectin, and biosynthesized matrix prevented apoptosis, due at least in part to integrin-mediated adhesion. When cells were cultured at high density but under conditions preventing cell-substratum adhesion, aggregation occurred. Apoptosis was inversely correlated with aggregation. Cell-cell adhesion in these conditions was mediated at least partly by integrins containing alpha v. Cell aggregation was not associated with activation of a signaling pathway that is usually activated by cell-ECM adhesion, phosphorylation of focal adhesion kinase, but was associated with Bcl-2 protein expression, consistent with the concept that Bcl-2 protects against apoptosis. We conclude that both cell-ECM and cell-cell interactions, likely mediated in part by integrins, modulate apoptosis in bronchial epithelium.

Antigens, CD↗
PubMed1997

Fibronectin supports bronchial epithelial cell adhesion and survival in the absence of growth factors.

Cell-extracellular matrix interactions support the ability of cells to migrate into areas of inflammation and injury. The present study evaluated the ability of different matrix proteins to support bronchial epithelial cell attachment and survival. Collagens were able to support attachment and survival of normal cultured human bronchial epithelial cells but only in the presence of added soluble growth factors such as insulin, epidermal growth factor, platelet-derived growth factor, and bovine pituitary extract. In contrast, fibronectin was able to support attachment and survival of normal human bronchial epithelial cells in growth factor-deficient medium. In addition, fibronectin, in the absence of added growth factors, was able to induce integrin clustering, focal adhesion formation, and phosphorylation of focal adhesion kinase. A 120-kDa chymotryptic fragment of fibronectin containing the Arg-Gly-Asp peptide sequence was able to reproduce the effects of the whole fibronectin molecule. This study supports the concept that fibronectin has specialized roles in injury and repair.

Animals↗
PubMed1997

Mutual inhibition by TGF-beta and IL-4 in cultured human bronchial epithelial cells.

The airway epithelial cell may play a role as an effector cell, releasing various cytokines and extracellular matrix components in immune responses, inflammation, and wound repair processes, thus contributing to cytokine "networks." The cytokines transforming growth factor (TGF)-beta and interleukin (IL)-4 are though to have pivotal roles in airway diseases, with IL-4 having proinflammatory actions and TGF-beta generally regarded to mediate repair and to attenuate immune responses. In asthma, where IL-4 and TGF-beta are thought to contribute to the inflammatory process and repair, respectively, interactions between these cytokines are likely to be of importance. Therefore, we studied the potential interaction of both cytokines by measuring IL-8 and fibronectin release by cultured human bronchial epithelial cells (HBECs). IL-4 is capable of inducing IL-8 release from HBECs. This effect of IL-4 can be blocked by the concurrent presence of the cytokine TGF-beta. In contrast, TGF-beta had a modest inconsistent stimulatory effect on IL-8 release by itself and had no effect on the IL-8 release induced by tumor necrosis factor (TNF)-alpha. An antagonistic effect of IL-4 and TGF-beta was also observed on HBEC fibronectin release. TGF-beta stimulated fibronectin release, and IL-4 was able to inhibit this. This effect was not due to a redistribution of fibronectin but appeared to be due to a true reduction in synthesis. Consistent with this, IL-4 and TGF-beta effects on IL-8 and fibronectin release were paralleled by changes in mRNA levels. The ability of TGF-beta to block IL-4-induced IL-8 release is certainly not the only mechanism to inhibit IL-8 release because dexamethasone was capable of inhibiting both TNF-alpha- and IL-4-induced release of IL-8. These results indicate that TGF-beta and IL-4 can have mutually inhibitory effects. The balance determined by this reciprocal inhibition may play an important role in regulating inflammation repair and in diseases such as asthma.

Adult↗
PubMed1997

Stimulation of protein kinase C activity by tumor necrosis factor-alpha in bovine bronchial epithelial cells.

Bronchial epithelial cell migration, attachment, and proliferation are important processes in response to airway injury. We have shown that tumor necrosis factor (TNF)-alpha stimulates the migration of bovine bronchial epithelial cells (BBEC) in vitro. We hypothesized that protein kinase C (PKC) may be one of the intracellular signaling mediators of TNF-alpha in BBEC. In this study, we have identified multiple PKC isoforms in BBEC and measured total cellular PKC activity. Polyclonal antibodies to the PKC-alpha, -beta 2, -delta, and -epsilon isoforms recognized protein bands around 80-90 kDa. BBEC primary cultures treated with either 500 U/ml TNF-alpha for 2-4 h or 100 ng/ml 12-O-tetradecanoylphorbol 13-acetate for 15 min resulted in three-to fivefold increases in PKC activity in the particulate fractions of crude cell lysates. This activity was inhibited by 1 microM calphostin C or 10 microM H-7. Similarly, TNF-alpha-stimulated BBEC migration was reduced at least twofold in the presence of H-7 or calphostin C. These studies suggest that the activation of PKC is necessary for TNF-alpha-stimulated BBEC migration.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1996

Lipopolysaccharide increases fibronectin production and release from cultured lung fibroblasts partially through proteolytic activity.

Fibronectin is a major product of fibroblasts and can mediate diverse functions including wound healing. Chronic bacterial infections are generally associated with a marked decreased in the ability to repair. We therefore hypothesized that bacterial endotoxin, lipopolysaccharide (LPS), might alter fibroblast fibronectin production. LPS augmented fibronectin production by fibroblasts and also stimulated the release of fibronectin from cell layers. An increase in new protein synthesis appeared to account for part of the increased fibronectin, because the inhibitor of protein synthesis, cycloheximide, inhibited the increase in total production of fibronectin. Cycloheximide did not attenuate the increased release of fibronectin into the culture medium. This increased release appeared to be caused, at least in part, by fragmentation of fibronectin by proteases contained in LPS preparations. In this regard all preparations of LPS tested were found to cleave fibronectin. Finally, zymograms indicated that LPS could also cleave gelatin with at least two bands of proteolytic activity but that it did not cleave bovine serum albumin or ovalbumin. These results indicate that the ability of bacterial products to alter fibronectin production and to degrade this macromolecule may account for altered wound repair that occurs with chronic bacterial infection.

Cell Line↗
PubMed1996

Mononuclear cell conditioned medium enhances bronchial epithelial cell migration but inhibits attachment to fibronectin.

The attachment and migration of bronchial epithelial cells are important features in re-epithelialization after tissue injury. We hypothesized that inflammatory cytokines might alter bronchial epithelial cell attachment and migration. To test this hypothesis, we evaluated the effects of mononuclear cell conditioned medium (MNCCM) on attachment and migration of bronchial epithelial cells to fibronectin in vitro. MNCCM was prepared from bovine blood mononuclear cells that were stimulated with concanavalin A. MNCCM stimulated bronchial epithelial cell migration and spreading. Sephadex G-75 column chromatography of MNCCM found two peaks of migration-stimulatory activity. Activity in the higher molecular weight peak was partially inhibited by anti-tumor necrosis factor-alpha antibodies. Activity in the low-molecular-weight peak was lipid-extractable, suggesting the possibility that the activity was an arachidonate metabolite. We evaluated the effects of protein kinase C (PKC) inhibitors on enhancement of bronchial epithelial cell migration by MNCCM under the hypothesis that stimulated bronchial epithelial cell migration by MNCCM was elicited through PKC-dependent signaling pathways. PKC inhibitors, calphostin and H-7, inhibited the effect of MNCCM on bronchial epithelial cell migration. In addition, MNCCM stimulated PKC translocation and activity in these cells. Thus mononuclear cells produce inflammatory cytokines with important effects on bronchial epithelial cell migration and spreading. The stimulatory effect may be mediated in part through PKC signaling pathways.

Actins↗
PubMed1996

Function at the junction: dynamic interactions between lung cells and extracellular matrix.

Recent advances are elucidating the mechanisms by which cells communicate with the surrounding matrix. Cells have specific receptors for matrix proteins. A number of intracellular molecules with signalling functions aggregate at specialised focal adhesion points and facilitate transfer of information both into and out of cells. The importance of these signaling processes to cell biology makes it likely that manipulation of these processes will allow innovative therapeutic approaches to lung disease.

Cell Communication↗
PubMed1996

Beta-adrenergic agonists attenuate fibroblast-mediated contraction of released collagen gels.

The effects of beta-adrenergic agonists on fibroblast-mediated collagen gel contraction were investigated. beta-Agonists isoproterenol and epinephrine significantly attenuated fibroblast-mediated gel contraction in a concentration-dependent manner, whereas alpha-agonist norepinephrine had no effect. The biologically active form of isoproterenol, (-)-isoproterenol, was 10-fold more effective than the optical isoform, (+)-isoproterenol. beta-Antagonists sotalol and propranolol reversed the attenuation caused by 10(-7) M isoproterenol or epinephrine at the concentration of 10(-7) M or 10(-6) M, but the alpha-antagonist phentolamine did not. However, beta1- or beta2-specificity of these effects is not clear. Isobutyl methylxanthine augmented the effect of isoproterenol and also prolonged the duration. Two reagents which are known to increase intracellular adenosine 3',5'-cyclic monophosphate (cAMP), prostaglandin E2 and dibutyryl adenosine 3',5'-cyclic monophosphate, attenuated gel contraction in a concentration-dependent manner. These data suggest that the fibroblast-mediated collagen gel contraction can be modulated by beta-adrenergic agonists and that the effect depends on cAMP.

1-Methyl-3-isobutylxanthine↗
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

Aprotinin and methylprednisolone equally blunt cardiopulmonary bypass-induced inflammation in humans.

Cardiopulmonary bypass induces an inflammatory state characterized by tumor necrosis factor-alpha release. Integrin CD11b is a neutrophil surface adhesive glycoprotein integrin that is rapidly and permanently unregulated by tumor necrosis factor-alpha exposure. The CD11b integrin is known to be the primary neutrophil integrin responsible for neutrophil lung and myocardial entrapment after cardiopulmonary bypass and subsequent reperfusion injury. Twenty-four adults admitted to the hospital for myocardial revascularization were equally randomized to one of three groups: group A (control), group B (methylprednisolone before cardiopulmonary bypass), and group C (low-dose aprotinin protocol). Blood was collected at three times: (1) baseline, (2) 50 minutes of cardiopulmonary bypass duration, and (3) 30 minutes after cardiopulmonary bypass termination. Neutrophil CD11b integrin expression was measured by fluorescence-activated cell sorter analysis and plasma tumor necrosis factor-alpha levels measured by enzyme-linked immunosorbent assay. Group A demonstrated significant (p < 0.05) increases in CD11b expression at times 2 and 3 when results were compared with those of the same group baseline and with those of groups B and C at similar times. No significant changes were noted between groups B and C at any time. Group A demonstrated a significant (p < 0.05) increase in levels of tumor necrosis factor-alpha at time 3 when results were compared with those of the same group baseline and of groups B and C at the same time. No significant changes were noted between B and C at any time. These results demonstrate low-dose aprotinin has a similar antiinflammatory effect to that of methylprednisolone in blunting cardiopulmonary bypass-induced systemic tumor necrosis factor-alpha release and neutrophil integrin CD11b upregulation.

Aged↗
PubMed1995

Supraceliac, but not infrarenal, aortic cross-clamping upregulates neutrophil integrin CD11b.

OBJECTIVE: To evaluate the effects of supraceliac and infrarenal aortic cross-clamping on the expression of neutrophil integrin in CD11b (a marker of systemic cytokine release). DESIGN: Two groups, determined by anatomic placement of aortic cross-clamp. Laboratory personnel were blinded as to group assignment. SETTING: University teaching and community hospitals. Laboratory facilities used were university and Veteran's Affairs medical centers. PARTICIPANTS: Patients scheduled for aortic surgery. INTERVENTIONS: Blood sampling was performed at baseline, after 30 minutes of aortic cross-clamp duration, 30 and 90 minutes after reperfusion (for tumor necrosis factor-alpha plasma levels in infrarenal cross-clamp group), and at baseline and 90 minutes reperfusion (for neutrophil CD11b expression quantification) in both groups. MEASUREMENTS AND MAIN RESULTS: Tumor necrosis factor-alpha measured by ELISA technique did not change at any time period in the infrarenal clamping group. Neutrophil CD11b expression, measured by double antibody staining and FACScan analysis, did not change significantly at 90 minutes of reperfusion in the infrarenal group, but increased significantly (p < 0.05) in the supraceliac aortic cross-clamp group. CONCLUSION: Neutrophil integrin CD11b has been demonstrated to be the primary adhesive glycoprotein responsible for neutrophil organ entrapment and subsequent neutrophil-mediated reperfusion injury. These results suggest that upregulation of neutrophil integrin CD11b after supraceliac aortic clamping may in part be responsible for the higher incidence of acute lung injury after thoracic aortic aneurysm repair requiring supraceliac clamping when compared with infrarenal aneurysm surgery.

Aged↗
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↗