Biomedical subjects

D W Kamp

Publications and source records attributed to D W Kamp.

26 records · Page 2Linked to original sources

PubMed1990

Polymorphonuclear leukocyte- and Pseudomonas aeruginosa-induced damage to a human pulmonary epithelial cell line.

Polymorphonuclear leukocytes (PMNL) or Pseudomonas aeruginosa can damage the lung, but the manner in which they interact to induce toxicity is unclear. An in vitro model of the pulmonary epithelium was used to investigate interactions of PMNL and P. aeruginosa on epithelial cytotoxicity. A low inoculum of P. aeruginosa (10(7) bacteria) was minimally toxic to the epithelial cells (lysis = 9.0 +/- 2.9, detachment = 3.5 +/- 1.4). The addition of PMNL to the low inoculum markedly increased damage to the epithelial cells (lysis = 18.1 +/- 3.9, detachment = 17.6 +/- 3.6). Both the bacterium and a low-molecular-weight exoproduct were able to induce PMNL-mediated damage to epithelial cells. The damage was inhibited by serum or the addition of alpha 1 antiprotease but not by antioxidants. A larger inoculum of P. aeruginosa (10(9) bacteria) was directly toxic to the pulmonary cells (lysis = 44.8 +/- 4.1, detachment = 7.6 +/- 0.7). The damage was mediated by a heat-labile bacterial exoproduct. Pulmonary epithelial damage following pseudomonal infections may be related to either neutrophil or bacterial activity depending on the bacterial inoculum.

Cell Line↗

PubMed1990

Serum promotes asbestos-induced injury to human pulmonary epithelial cells.

Asbestos exposure causes chronic interstitial pulmonary fibrosis. Injury to human pulmonary epithelial cells (HPEC) is speculated to precede the fibrotic response. We investigated whether asbestos, either alone or in conjunction with serum, injured cultured HPEC as assessed in a standard chromium 51 release assay. Amosite asbestos in serum-free media induced modest HPEC injury (9.4% +/- 3.3% Cr release), which was significantly enhanced (2.7-fold) in the presence of serum (25.5% +/- 4% Cr release). HPEC cytotoxicity was both asbestos and serum dose-dependent. Additionally, we demonstrated that, compared with HPEC injury induced by asbestos plus serum, (1) heat-decomplemented serum or serum fractions of a wide range of molecular weights were equipotent to fresh serum, (2) catalase, superoxide dismutase, or dimethylthiourea was not protective, (3) 3-aminobenzamide, which prevents oxidant-induced adenosine triphosphate depletion by inhibiting poly-adenosine diphosphate-ribose polymerase, afforded significant protection (32% decrease in HPEC injury), and (4) deferoxamine-treated asbestos was significantly less toxic to HPEC compared with untreated asbestos, causing a 57% decrease in HPEC cytotoxicity. Electron microscopic studies revealed that, compared with buffer, serum increased the amount of amosite asbestos along the surface and inside HPEC. Thus, amosite asbestos is cytotoxic to cultured HPEC and serum promotes this injurious effect by augmenting the interaction of asbestos with HPEC. These data suggest that this effect may occur by increasing intracellular oxidant stress mediated in part by the iron in asbestos.

Asbestos↗

PubMed1989

Tumor-promoting phorbol esters inhibit monocyte adherence to endothelial cells.

Monocyte adherence to endothelial cells (EC) is an important event in the development of a monocytic inflammatory response, yet the effects of inflammatory mediators on monocyte adherence to EC are not well described. We compared the effects of phorbol esters known to activate protein kinase C, including phorbol myristate acetate (PMA) and phorbol 12,13-dibutyrate (PDA), on monocyte adherence to bovine aortic EC. Human monocytes (purity 90 +/- 1% SE) were isolated by centrifugal elutriation to obtain monocytes not previously exposed to a surface. Kinetic studies revealed that 51Cr-labeled monocyte adherence to EC reached a plateau after a 45-min incubation. Concentrations of PMA between 10 and 1,000 ng/ml significantly decreased monocyte adherence to EC (26 +/- 10 and 35 +/- 8% decrease compared with control, respectively). Concentrations of PDA of 100 and 1,000 ng/ml had a similar inhibitory effect. In contrast, the chemotactic stimulus, zymosan-activated serum, significantly increased monocyte adherence (40 +/- 14% increase compared with control). Thus inflammatory stimuli have different effects on the adhesive interaction of monocytes to EC. This may provide a mechanism to selectively modulate monocyte egress from the circulation into extravascular inflammatory sites.

Animals↗

PubMed1989

Contrasting effects of inflammatory stimuli on neutrophil and monocyte adherence to endothelial cells.

Leukocyte adherence to endothelial cells (EC) is an important early event in inflammatory responses, which are often characterized by a predominance of either neutrophils (PMN) or monocytes. However, there is little information concerning the molecular events important in leukocyte adherence to EC. Intracellular activation of protein kinase C and the calcium-second messenger system leads to the stimulation of a number of important functions in PMN and monocytes. We compared the effects of members of these pathways on human PMN and monocyte adherence to cultured bovine aortic EC. We observed that phorbol myristate acetate, phorbol, 12,13-dibutyrate, L-alpha-1-oleoyl-2-acetoyl-sn-3-glycerol, and ionomycin each induced significant dose-dependent increases in PMN adherence to EC monolayers. In contrast, similar concentrations of each of these agents induced significant decreases in EC adherence of monocytes enriched by countercurrent centrifugal elutriation. Separate experiments determined that the differences in PMN and monocyte adherence to EC were not related to differences in oxidant production because 1) phorbol myristate acetate and L-alpha-1-oleoyl-2-acetoyl-sn-3-glycerol caused similar marked increases in both PMN and monocyte superoxide anion and hydrogen peroxide production and 2) ionomycin, which had opposing effects on PMN and monocyte adherence, had no effect on PMN and monocyte superoxide anion or hydrogen peroxide release. We conclude that activators of protein kinase C and the Ca-second messenger pathway have opposite effects on PMN and monocyte adherence to EC and that these effects are mediated by O2 radical-independent mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

The interaction of asbestos and neutrophils injures cultured human pulmonary epithelial cells: role of hydrogen peroxide.

Asbestos exposure causes diffuse interstitial pulmonary fibrosis. Since alveolar epithelial cell injury is hypothesized to precede the fibrotic response in asbestosis, we investigated whether asbestos, either alone or in conjunction with neutrophils (PMNs), injured cultured human pulmonary epithelial cells (HPECs). HPEC cytotoxicity was assessed with a standard 51chromium release assay after a 16-hour incubation with asbestos and PMNs. Negligible HPEC cytotoxicity was observed after incubation with either amosite asbestos (500 micrograms/ml) or PMNs alone in serum-free media. However, incubation with both asbestos and PMNs caused significant HPEC injury, which was asbestos dose-dependent; causing 25% +/- 4% detachment and 52% +/- 8% 51chromium release with 500 micrograms/ml asbestos. The cytotoxic effects of asbestos plus PMNs were nearly completely attenuated with serum (20%) or catalase (100 micrograms/ml) but were not prevented with scavengers of superoxide anion, hydroxyl radical, or hypochlorous acid. A role for hydrogen peroxide (H2O2) in mediating HPEC injury was also suggested by the demonstration of asbestos-induced generation of H2O2 by PMNs. Furthermore, H2O2 alone (10(-4)mol/L) caused significant HPEC damage. Intimate contact between asbestos-activated PMNs and HPECs was a necessary requirement for PMN-mediated HPEC cytotoxicity. These data suggest that pulmonary epithelial cell injury is mediated in part by H2O2 release from asbestos-activated PMNs as well as intimate contact between the epithelial cell, PMNs, and asbestos.

Asbestos↗

PubMed1988

Transforming growth factor-beta (TGF beta) is chemotactic for human monocytes and induces their expression of angiogenic activity.

TGF beta stimulates human blood monocyte migration, with peak migratory response occurring consistently at a concentration of 16-100 fg/ml. Checkerboard analysis revealed both chemotactic and chemokinetic components to this response. At higher concentrations (10-100 pg/ml), TGF beta stimulated expression of angiogenic activity by monocytes. While mRNA for TNF alpha was undetectable in resting monocytes, high steady state levels of TNF alpha mRNA were rapidly induced in TGF beta-treated monocytes. TGF beta is secreted by a number of neoplastic cells as well as normal cells such as platelets and lymphocytes. TGF beta may recruit monocytes from the circulation, and subsequently activate them to express angiogenic activities such as TNF alpha, thus playing an important role in wound repair, inflammation and tumor growth.

Chemotaxis, Leukocyte↗

PubMed1987

Pulmonary clearance of Pseudomonas aeruginosa in neutropenic mice. Effects of systemic immunization.

Systemic immunization with killed Pseudomonas improves pulmonary clearance of these bacteria in normal mice. To test the effects of active systemic immunization on early pulmonary clearance of Pseudomonas in neutropenic mice, Balb/c mice were intraperitoneally immunized with 10(8) Pseudomonas or injected with saline twice weekly for 2 wk. Ten days after the last immunization, immunized and control mice received tail vein injections with either nitrogen mustard or saline daily for 3 days. Two days after the last nitrogen mustard injection, mice were intrabronchially challenged with 10(6) or 10(4) live Pseudomonas and clearance was assessed 4 h later. With the higher inoculum, immunization (neutrophil-replete and neutropenic mice) augmented pulmonary clearance. The improvement in clearance with the higher inoculum was associated with a marked increase in bronchoalveolar lavage anti-Pseudomonas IgG. However, bacteria grew in the lungs of all neutropenic mice. Immunization did not alter pulmonary clearance of the lower inoculum of Pseudomonas, and bacterial growth occurred in the neutropenic mice. Gentamicin was administered to mice 2 h after intrabronchial challenge with 10(6) Pseudomonas to determine whether its effects were additive to immunization. Gentamicin improved pulmonary clearance effected by immunization only in the neutrophil-replete mice; immunization provided no additional benefit to gentamicin in the neutropenic mice. These data show that both neutrophils and immunization contribute to Pseudomonas clearance. Immunization improves pulmonary clearance of Pseudomonas in neutropenic mice with a sufficiently high inoculum, but bacterial growth still occurs. Gentamicin treatment is effective in eliminating bacteria in this model and immunization has no additional benefit.

Agranulocytosis↗

PubMedDate not supplied

Phytic acid, an iron chelator, attenuates pulmonary inflammation and fibrosis in rats after intratracheal instillation of asbestos.

Reactive oxygen species, especially iron-catalyzed hydroxyl radicals (.OH) are implicated in the pathogenesis of asbestos-induced pulmonary toxicity. We previously demonstrated that phytic acid, an iron chelator, reduces amosite asbestos-induced .OH generation, DNA strand break formation, and injury to cultured pulmonary epithelial cells (268[1995, Am. J. Physiol.(Lung Cell. Mol. Physiol.) 12:L471-480]). To determine whether phytic acid diminishes pulmonary inflammation and fibrosis in rats after a single intratracheal (it) instillation of amosite asbestos, Sprague-Dawley rats were given either saline (1 ml), amosite asbestos (5 mg; 1 ml saline), or amosite treated with phytic acid (500 microM) for 24 hr and then instilled. At various times after asbestos exposure, the rats were euthanized and the lungs were lavaged and examined histologically. A fibrosis score was determined from trichrome-stained specimens. As compared to controls, asbestos elicited a significant pulmonary inflammatory response, as evidence by an increase (approximately 2-fold) in bronchoalveolar lavage (BAL) cell counts at 1 wk and the percentage of BAL neutrophils (PMNs) and giant cells at 2 wk (0.1 vs 6.5% and 1.3 vs 6.1%, respectively; p < 0.05). Asbestos significantly increased the fibrosis score at 2 wk (0 +/- 0 vs 5 +/- 1; p < 0.05). The inflammatory and fibrotic changes were, as expected, observed in the respiratory bronchioles and terminal alveolar duct bifurcations. The increased percentage of BAl PMNs and giant cells persisted at 4 wk, as did the fibrotic changes. Compared to asbestos alone, phytic acid-treated asbestos elicited significantly less BAL PMNs (6.5 vs 1.0%; p < 0.05) and giant cells (6.1 vs 0.2%; p < 0.05) and caused significantly less fibrosis (5 vs 0.8; p < 0.05) 2 wk after exposure. We conclude that asbestos causes pulmonary inflammation and fibrosis in rats after it instillation and that phytic acid reduces these effects. These data support the role of iron-catalyzed free radicals in causing pulmonary toxicity from asbestos in vivo.

Animals↗