PubMed Health⌕ Search

Biomedical subjects

A J Ghio

Publications and source records attributed to A J Ghio.

At least 19 recordsLinked to original sources
PubMed2001

Coagulation blockade prevents sepsis-induced respiratory and renal failure in baboons.

Sepsis-induced tissue factor (TF) expression activates coagulation in the lung and leads to a procoagulant environment, which results in fibrin deposition and potentiates inflammation. We hypothesized that preventing initiation of coagulation at TF-Factor VIIa (FVIIa) complex would block fibrin deposition and control inflammation in sepsis, thereby limiting acute lung injury (ALI) and other organ damage in baboons. A model of ALI was used in which adult baboons were primed with killed Escherichia coli (1 x 10(9) CFU/kg), and bacteremic sepsis was induced 12 h later by infusion of live E. coli at 1 x 10(10) CFU/kg. Animals in the treatment group were given a competitive inhibitor of TF, site-inactivated FVIIa (FVIIai), intravenously at the time of the infusion of live bacteria and monitored physiologically for another 36 h. FVIIai dramatically protected gas exchange and lung compliance, prevented lung edema and pulmonary hypertension, and preserved renal function relative to vehicle (all p < 0.05). Treatment attenuated sepsis-induced fibrinogen depletion (p < 0.01) and decreased systemic proinflammatory cytokine responses, for example, interleukin 6 (p < 0.01). The protective effects of TF blockade in sepsis-induced ALI were confirmed by using tissue factor pathway inhibitor. The results show that TF-FVIIa complex contributes to organ injury in septic primates in part through selective stimulation of proinflammatory cytokine release and fibrin deposition.

Acute Kidney Injury↗
PubMed2001

Diffuse alveolar damage after exposure to an oil fly ash.

Epidemiological investigation has established an association between exposure to particulate matter (PM) and both human mortality and diverse indices of human morbidity. However, attributing adverse health effects of specific individuals to PM exposure in these studies is not possible. Consequently, their clinical presentation remains ill-defined. We describe a 42-yr-old male with both respiratory damage, abnormal blood end points, and cardiac effects following an exposure to an emission source air pollution particle aerosolized during the cleaning of his domestic oil-burning stove. Early symptoms of shortness of breath and wheezing progressed over 2 wk to hypoxic respiratory failure necessitating mechanical ventilation. Blood indices were abnormal. Thoracoscopic biopsy demonstrated particle-laden macrophages and diffuse alveolar damage. Symptomatic and objective improvement rapidly followed initiation of corticosteroids. He developed typical anginal symptoms within 2 wk of discharge; however, coronary angiography did not identify any significant narrowing of the epicardial coronary arteries. This patient presents with the aggregate of potential injuries described by epidemiological methods to be associated with air pollution particle exposure.

Adult↗
PubMed2001

Inflammatory lung injury after bronchial instillation of air pollution particles.

Epidemiologic investigation has established an association between exposure to particulate matter (PM) and human health in the Utah Valley. Reduction of particle mass during the temporary closure of a local steel mill was associated with diminished morbidity and mortality. We tested the hypothesis that the biologic effect of PM would reflect findings of epidemiology with a greater injury after exposure to an equal mass of particles from those years in which the mill was in operation. Filters containing PM were collected prior to closure of the steel mill, during the closure, and after its reopening. Aqueous extracts of the filters were prepared. One of three extracts (500 microg) was instilled through the bronchoscope into the lungs of nonsmoking volunteers. Twenty-four hours later, the same subsegment was lavaged. Exposure to aqueous extracts of PM collected before closure and after reopening of the steel mill provoked a greater inflammatory response relative to PM extract acquired during the plant shutdown. This is the first demonstration that pulmonary effects after experimental exposure of humans to PM can correlate with health outcomes observed in epidemiologic studies of the same material under normal exposure conditions. Findings suggest that mass may not be the most appropriate metric to use in assessing health effects after PM exposure but rather specific components must be identified and assessed.

Adult↗
PubMed2001

Air pollution particles mediated oxidative DNA base damage in a cell free system and in human airway epithelial cells in relation to particulate metal content and bioreactivity.

Epidemiological studies demonstrate an association between increased human morbidity and mortality with exposure to air pollution particulate matter. We hypothesized that such effects may be associated with the ability of the particles to mediate generation of reactive oxygen species (ROS), either directly, via interaction with ambient oxygen or indirectly through initiation of an oxidative burst in phagocytes. To test this hypothesis, we determined 8-oxo-dG formation as a measure of direct generation of ROS, in response to particulate exposures to 2'-deoxyguanosine (dG), free and in calf thymus DNA in aerated solutions as the target molecule and cell culture, to assess the relationship between induction of oxidative damage, particulate metal content and metal bioreactivity. The HPLC-ECD technique was employed for separation and quantification of 8-oxo-dG, the most widely recognized marker of DNA oxidation. Particles used in this study include: Arizona desert dust (AZDD), coal fly ash (CFA and ECFA), oil fly ash (OFA and ROFA), and ambient air [SRM 1649 and Dusseldorf (DUSS), Germany]. The major difference between these particles is the concentration of water-soluble metals. The fly ash particulates OFA and ROFA showed a significant dose-dependent increase in dG hydroxylation to 8-oxo-dG formation over the control dG (p < 0.05), with yields 0.03 and 1.25% at the highest particulate concentration (1 mg/mL). Metal ion chelators and DMSO, a hydroxyl radical scavenger, inhibited this hydroxylation. In contrast, desert dust, coal fly ash and urban air particles induced 8-oxo-dG with yields ranging from 0.003 to 0.006%, respectively, with levels unaffected by pretreatment of the particles with metal ion chelators or addition of DMSO to the incubation mixture. When calf thymus DNA was used as a substrate, all the particles induced 8-oxo-dG in a pattern similar to that observed for dG hydroxylation, but with relatively less yield. Treatment of the particles with metal ion chelator before reacting with DNA or addition of catalase in the incubation mixture, suppressed 8-oxo-dG formation significantly (p < 0.05) in oil-derived fly ash particles only. To determine whether the oxidative responses of these particulates as shown in cell-free systems were consistent with responses using a more biologically relevant environment, human airway epithelial cells were treated with the particulates and induction of 8-oxo-dG was determined. All particles induced 8-oxo-dG in the DNA of cells above culture control, except CFA. Cells exposed to 10-400 mg/mL of ROFA for 2 h induced a dose-dependent increase in 8-oxo-dG formation. Treatment of ROFA with metal ion chelator attenuated these effects. Overall, damage enhancement by particulates in dG, calf thymus, and cellular DNA as determined by 8-oxo-dG formation under aerobic conditions is consistent with the concentration of water-soluble, not the total metal content of the particle.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

Effects of inhaled iron oxide particles on alveolar epithelial permeability in normal subjects.

Pulmonary inflammation secondary to oxidant generation catalyzed by transition metals associated with inhaled particles is one factor postulated to underlie the acute health effects of particulate air pollution. We postulated that inhaled iron oxide particles with associated amounts of soluble iron should induce mild pulmonary inflammation and lead to altered alveolar epithelial integrity and altered gas exchange. To test this hypothesis we examined the effects of inhaled iron oxide particles on alveolar epithelial permeability. Sixteen healthy subjects inhaled aerosols of iron oxide particles (1.5 microm mass median aerodynamic diameter) having either high or low water-soluble iron content [3.26 +/- 0.25 (SE) and 0.14 +/- 0.04 microg soluble iron/mg of particles, respectively] for 30 min at an average mass concentration of 12.7 mg/m(3). Alveolar epithelial permeability was assessed by measuring the pulmonary clearance of an inhaled radiolabeled tracer molecule ((99m)Tc-DTPA, diethylene triamine pentaacetic acid) using a gamma camera at 1/2 h and 24 h post particle exposure. Carbon monoxide lung diffusing capacity (DL(CO)) and spirometry were also performed before and after breathing the iron oxide. As a control, on a separate day, the procedures were duplicated except that the subject breathed particle-free air. For those subjects breathing aerosols with high soluble iron, we found no significant difference in DTPA clearance half-times after breathing particles versus particle-free air either at 1/2 h (97.4 +/- 15.4 vs. 116.1 +/- 15.5 min, respectively) or 24 h postinhalation (105.1 +/- 13.8 vs. 106.9 +/- 12.9 min, respectively). Likewise, for those subjects breathing aerosols with low soluble iron content we found no significant difference in DTPA clearance half-times after breathing particles versus particle-free air either at 1/2 h (108.6 +/- 31.9 vs. 95.6 +/- 10.8 min, respectively) or 24 h postinhalation (130.0 +/- 18.0 vs. 105.8 +/- 13.7 min, respectively). We found no significant differences in DL(CO) between particle exposures and air exposures. Minor differences in spirometric measurements were noted but were not statistically significant. We conclude that inhalation of iron oxide particles did not cause an appreciable alteration of alveolar epithelial permeability, lung diffusing capacity, or pulmonary function in healthy subjects under the studied conditions.

Administration, Inhalation↗
PubMed2001

Reactive oxygen species from NAD(P)H:quinone oxidoreductase constitutively activate NF-kappaB in malignant melanoma cells.

The transcription factor nuclear factor-kappaB (NF-kappaB) is constitutively activated in malignancies from enhanced activity of inhibitor of NF-kappaB (IkappaB) kinase, with accelerated IkappaBalpha degradation. We studied whether redox signaling might stimulate these events. Cultured melanoma cells generated superoxide anions (O(2)(-)) without serum stimulation. O(2)(-) generation was reduced by the NAD(P)H:quinone oxidoreductase (NQO) inhibitor dicumarol and the quinone analog capsaicin, suggesting that electron transfer from NQO through a quinone-mediated pathway may be an important source of endogenous reactive oxygen species (ROS) in tumor cells. Treatment of malignant melanoma cells with the H(2)O(2) scavenger catalase, the sulfhydryl donor N-acetylcysteine, the glutathione peroxidase mimetic ebselen, or dicumarol decreased NF-kappaB activation. Catalase, N-acetylcysteine, ebselen, dicumarol, and capsaicin also inhibited growth of melanoma and other malignant cell lines. These results raise the possibility that ROS produced endogenously by mechanisms involving NQO can constitutively activate NF-kappaB in an autocrine fashion and suggest the potential for new antioxidant strategies for interruption of oxidant signaling of melanoma cell growth.

Antioxidants↗
PubMed2001

Vascular release of nonheme iron in perfused rabbit lungs.

In this study, we hypothesized that the lung actively releases excess iron into the circulation to regulate iron homeostasis. We measured nonheme iron (NHFe) in the perfusate of control isolated perfused rabbit lungs and lungs with ischemia-reperfusion (I/R) ventilated with normoxic (21% O(2)) or hypoxic (95% N(2)) gas mixtures. Some were perfused with bicarbonate-free (HEPES) buffer or treated with the anion exchange inhibitor DIDS. The control lungs released approximately 0.25 microg/ml of NHFe or 20% of the total lung NHFe into the vascular space that was not complexed with ferritin, transferrin, or lactoferrin or bleomycin reactive. The I/R lungs released a similar amount of NHFe during ischemia and some bleomycin-detectable iron during reperfusion. NHFe release was attenuated by approximately 50% in both control and ischemic lungs by hypoxia and by >90% in control lungs and approximately 60% in ischemic lungs by DIDS and HEPES. Reperfusion injury was not affected by DIDS or HEPES but was attenuated by hypoxia. These results indicate that biologically nonreactive nonheme iron is released rapidly by the lung into the vascular space via mechanisms that are linked to bicarbonate exchange. During prolonged ischemia, redox-active iron is also released into the vascular compartment by other mechanisms and may contribute to lung injury.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2001

Activation of the EGF receptor signaling pathway in airway epithelial cells exposed to Utah Valley PM.

Exposure to ambient particulate matter (PM) in the Utah Valley has previously been associated with a variety of adverse health effects. To investigate intracellular signaling mechanisms for pulmonary responses to Utah Valley PM inhalation, human primary airway epithelial cells were exposed to aqueous extracts of PM collected from the year before (Y1), during (Y2), and after (Y3) the closure of a local steel mill located in the Utah Valley in this study. Transfection with kinase-deficient extracellular signal-regulated kinase (ERK) 1 constructs partially blocked Utah Valley PM-induced interleukin (IL)-8 promoter reporter activity. The mitogen-activated protein kinase/ERK kinase (MEK) activity inhibitor PD-98059 significantly abolished IL-8 released in response to Utah Valley PM, as did the epidermal growth factor (EGF) receptor kinase inhibitor AG-1478. Western blotting showed that Utah Valley PM induced phosphorylation of EGF receptor tyrosine, MEK1/2, and ERK1/2, which could be ablated with AG-1478 or PD-98059. For all findings, the potency of Utah Valley PM collected during Y2 was found to be lower relative to that of Y1 and Y3. These data demonstrate that Utah Valley PM can induce IL-8 expression partially through the activation of the EGF receptor signaling.

Air Pollutants, Occupational↗
PubMed2001

Haptoglobin in lung defence.

Haptoglobin (Hp) has been known to be associated with the host defence response to infection and inflammation. The biological functions of Hp can be related to its ability to bind haemoglobin or to modulate immune response. Hp is expressed at a high level in lung cells, yet its protective role(s) in the lung is not known. Using transgenic mice overexpressing Hp, we demonstrated that Hp can reduce blood-induced lung injury. Hp-mediated haemoglobin catabolism in lung cells appears to be linked to iron mobilization, and may be an efficient mechanism to reduce oxidative damage associated with haemolysis.

Animals↗
PubMed2001

Acute pulmonary toxicity of particulate matter filter extracts in rats: coherence with epidemiologic studies in Utah Valley residents.

Epidemiologic reports by C.A. Pope III et. al. demonstrated that in the Utah Valley, closure of an open-hearth steel mill over the winter of 1987 was associated with reductions in respiratory disease and related hospital admissions in valley residents. To better examine the relationship between plant-associated changes in ambient particulate matter (PM) and respiratory health effects, we obtained total suspended particulate filters originally collected near the steel mill during the winter of 1986 (before closure), 1987 (during closure), and 1988 (after plant reopening). PM subcomponents were water-extracted from these filters and Sprague-Dawley rats were intratracheally instilled with equivalent masses of extract. Data indicated that 24 hr later, rats exposed to 1986 or 1988 extracts developed significant pulmonary injury and neutrophilic inflammation. Additionally, 50% of rats exposed to 1986 or 1988 extracts had increased airway responsiveness to acetylcholine, compared to 17 and 25% of rats exposed to saline or the 1987 extract, respectively. By 96 hr, these effects were largely resolved except for increases in lung lavage fluid neutrophils and lymphocytes in 1986 extract-exposed rats. Analogous effects were observed with lung histologic assessment. Extract analysis using inductively coupled plasma-mass spectroscopy demonstrated in all three extracts nearly 70% of the mass appeared to be sodium-based salts derived from the glass filter matrix. Interestingly, relative to the 1987 extract, the 1986/1988 extracts contained more sulfate, cationic salts (i.e., calcium, potassium, magnesium), and certain metals (i.e., copper, zinc, iron, lead, strontium, arsenic, manganese, nickel). Although total metal content was (3/4) 1% of the extracts by mass, the greater quantity detected in the 1986 and 1988 extracts suggests metals may be important determinants of the pulmonary toxicity observed. In conclusion, the pulmonary effects induced by exposure of rats to water-based extracts of local ambient PM filters were in good accord with the cross-sectional epidemiologic reports of adverse respiratory health effects in Utah Valley residents.

Air Pollution↗
PubMed2001

Inhalation of PM2.5 does not modulate host defense or immune parameters in blood or lung of normal human subjects.

We tested the hypothesis that exposure of healthy volunteers to concentrated ambient air particles (CAPS) between 0.1 and 2.5 microm in diameter is associated with modulation of human alveolar macrophage (AM) function, cytokine production, and immune phenotype in both blood and lung. Thirty-eight volunteers were exposed to either filtered air or CAPS from the immediate environment of the U.S. Environmental Protection Agency human studies facility in Chapel Hill, North Carolina, USA. Particle concentrations in the chamber during the exposures ranged from 23.1 to 311.1 microg/m3. No symptoms were noted by volunteers after the exposure. Eighteen hours after exposure, analysis of cells obtained by bronchoalveolar lavage (BAL) showed a mild increase in neutrophils in both the bronchial (8.4 +/- 2%) and alveolar fractions (4.2 +/- 1.7%) in subjects exposed to the highest concentration of CAPS compared to neutrophils in the fluids of those exposed to filtered air (bronchial fraction 2.7 +/- 0.6%; alveolar fraction 0.8 +/- 0.3%). There was no change in the percentage of lymphocytes or AMs recovered in the lavage after inhalation of the highest particle levels (mean 207 microg/m3). There was also no change in the proportion of lymphocytes in the BAL expressing CD3, CD4, CD8, CD19, nor activation markers CD25 or CD69. Particle inhalation did not affect the expression of CD11b, CD64, CD16, CD14, CD71 on AM, nor was there an effect on phagocytosis or oxidant generation following stimulation with zymosan A. IL-6 and IL-8 levels detected by enzyme-linked immunoabsorbent assay in the BAL were unrelated to inhaled particle levels. The distribution of lymphocyte subsets in blood obtained 18 hr after exposure to CAPS did not differ from that found before exposure. We conclude that ambient air particles are capable of inducing a mild inflammation in the lower respiratory tract but have no effect on immune phenotype or macrophage function under the conditions tested.

Administration, Inhalation↗
PubMed2000

Effect of ozone on diesel exhaust particle toxicity in rat lung.

Ambient particulate matter (PM) concentrations have been associated with mortality and morbidity. Diesel exhaust particles (DEP) are present in ambient urban air PM. Coexisting with DEP (and PM) is ozone (O(3)), which has the potential to react with some components of DEP. Some reports have shown increased lung injury in rats coexposed to PM and O(3), but it is unclear whether this increased injury was due to direct interaction between the pollutants or via other mechanisms. To examine whether O(3) can directly react with and affect PM bioactivity, we exposed DEP to O(3) in a cell-free in vitro system and then examined the bioactivity of the resultant DEP in a rat model of lung injury. Standard Reference Material 2975 (diesel exhaust PM) was initially exposed to 0.1 ppm O(3) for 48 h and then instilled intratracheally in Sprague-Dawley rats. Rat lung inflammation and injury was examined 24 h after instillation by lung lavage. The DEP exposed to 0.1 ppm O(3) was more potent in increasing neutrophilia, lavage total protein, and LDH activity compared to unexposed DEP. The increased DEP activity induced by the O(3) exposure was not attributable to alteration by air that was also present during the O(3) exposure. Exposure of DEP to a higher O(3) concentration (1.0 ppm) led to a decreased bioactivity of the particles. In contrast, carbon black particles, low in organic content relative to DEP, did not exhibit an increase in any of the bioactivities examined after exposure to 0.1 ppm O(3). DEP incorporated O(3) (labeled with (18)O) in a linear fashion. These data suggest that ambient concentrations of O(3) can increase the biological potency of DEP. The ozonized DEP may play a role in the induction of lung responses by ambient PM.

Adolescent↗
PubMed2000

Enhancement of 2'-deoxyguanosine hydroxylation and DNA damage by coal and oil fly ash in relation to particulate metal content and availability.

Epidemiologic studies have shown causal relationships between air pollution particles and adverse health effects in susceptible subpopulations. Fly ash particles (containing water-soluble and insoluble metals) are a component of ambient air particulate pollution and may contribute to particulate-induced health effects. Some of the pathological effects after inhalation of the particles may be due to reactive oxygen species (ROS) produced by metal-catalyzed reactions. In this investigation, we analyzed emission source particulates oil fly ash (OFA) and coal fly ash (CFA) for metal content and solubility in relation to their ability to induce 2'-deoxyguanosine (dG) hydroxylation and DNA damage as measured by 8-oxo-dG formation by HPLC/UV-electrochemical detection (ECD). Water-soluble vanadium and nickel were present at the highest concentrations, and iron was present in trace amounts in OFA (5.1% V, 1.0% Ni, and 0.4% Fe by weight). In contrast, CFA comprised mostly of water-insoluble aluminosilicates and iron (9.2% Al, 12.2% Si, and 2.8% Fe by weight). As a first approach to gain insight into the mode of action of these particulates, we examined metal species-catalyzed kinetics of dG hydroxylation. Metal species at a concentration of 0.1 mM in the incubation mixture containing 0.1 mM dG under ambient air at room temperature catalyzed maximum 8-oxo-dG formation at 15 min with yields ranging from 0.05 to 0.17%, decreasing in the following order: vanadium(IV) > iron(II) > vanadium(V) > iron(III) > or = nickel(II). Insoluble Fe(III) oxide (Fe(2)O(3)) under similar conditions had no effect. Consistent with these results, OFA rich in vanadium and nickel concentrations showed a dose-dependent increase in the level of dG hydroxylation to 8-oxo-dG formation at particulate concentrations of 0.1-1 mg/mL (p < 0.05). In contrast, CFA with high concentrations of aluminosilicates and iron did not result in a significant increase in the level of 8-oxo-dG over that of the control, i.e., dG (p > 0.05). DMSO, a (*)OH scavenger, inhibited OFA-induced 8-oxo-dG formation, and metal ion chelators, deferoxamine (DFX), DTPA, and ferrozine blocked OFA-induced 8-oxo-dG formation. OFA and CFA induced 8-oxo-dG formation in a pattern similar to that observed for dG hydroxylation when calf thymus DNA was used as a substrate. Treatment of OFA particles with DFX before reacting with DNA or addition of a catalase in the incubation mixture significantly suppressed 8-oxo-dG formation (p < 0.05). These results suggest that metal availability, but not the concentration of metals present in CFA and OFA, is critical in mediating molecular oxygen-dependent dG hydroxylation and DNA base damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Soluble components of Utah Valley particulate pollution alter alveolar macrophage function in vivo and in vitro.

Water-soluble extracts of Utah Valley dust (UVD) have been found to cause inflammatory injury of the lung in both humans and rodents. The degree of lung damage found correlated with the metal content in the extracts. In the present study, extracts of a set of UVD PM(10) filters collected over a 3-yr span, varying in total metal content with yr 1 = yr 3 > yr 2, were used to assess effects on human alveolar macrophage (AM) function. The phagocytic activity and oxidative response of AM was investigated 24 h after segmental instillation of UVD, or after overnight in vitro culture of the extracts with AM. Using flow cytometry analysis, AM phagocytosis of fluorescently (FITC)-labeled Saccharomyces cerevisiae was inhibited following instillation of UVD1 (61%) but not by yr 2 and 3. Neither baseline oxidant activity nor phorbol ester-induced oxidant generation was affected by the dust extracts in vivo. Overnight culture of AM with UVD1 resulted in a significant decrease in the percentage of AM phagocytizing particles (30%), while no significant effect on this function was found with the other two extracts. Furthermore, only UVD1 caused an immediate oxidative response in AM, although both UVD1 and UVD3 inhibited oxidant activity in AM when the cells were incubated with the extracts overnight. The detrimental effects on AM host defenses could be due to apoptosis, which was evident in cells exposed to the UVD1 and to a much lesser extent with AM exposed to yr 2 and 3. The component(s) responsible for the toxic effects on AM in vitro were removed by pretreatment of the UVD extracts with a polycation chelating resin, chelex-100. However, since yr 1 and 3 are similar in their soluble metal content, but differ in their effects on AM phagocytosis, it is possible that the metals may not be the culprit in effects of particulate matter on AM host defense.

Adolescent↗
PubMed2000

In vivo and in vitro correlation of pulmonary MAP kinase activation following metallic exposure.

Residual oil fly ash (ROFA) is a particulate pollutant produced in the combustion of fuel oil. Exposure to ROFA is associated with adverse respiratory effects in humans, induces lung inflammation in animals, and induces inflammatory mediator expression in cultured human airway epithelial cells (HAEC). ROFA has a high content of transition metals, including vanadium, a potent tyrosine phosphatase inhibitor that we have previously shown to disregulate phosphotyrosine metabolism and activate mitogen-activated protein kinase (MAPK) signaling cascades in HAEC. In order to study MAPK activation in response to in vivo metal exposure, we used immunohistochemical methods to detect levels of phosphorylated protein tyrosines (P-Tyr) and the MAPKs ERK1/2, JNK, and P38 in lung sections from rats intratracheally exposed to ROFA. After a 1-h exposure to 500 microg ROFA, rat lungs showed no histological changes and no significant increases in immunostaining for either P-Tyr or phospho-(P-) MAPKs compared to saline-instilled controls. At 4 h of exposure, there was mild and variable inflammation in the lung, which was accompanied by an increase in specific immunostaining for P-Tyr and P-MAPKs in airway and alveolar epithelial cells and resident macrophages. By 24 h of exposure, there was a pronounced inflammatory response to ROFA instillation and a marked increase in levels of P-Tyr and P-MAPKs present within the alveolar epithelium and in the inflammatory cells, while the airway epithelium showed a continued increase in the expression of P-ERK1/2. By comparison, HAEC cultures exposed to 100 microg/ml ROFA for 20 min resulted in marked increases in P-Tyr and P-MAPKs, which persisted after 24 h of exposure. P-Tyr levels continued to accumulate for up to 24 h in HAEC exposed to ROFA. These results demonstrate in vivo activation in cell signaling pathways in response to pulmonary exposure to particulate matter, and support the relevance of in vitro studies in the identification of mechanisms of lung injury induced by pollutant inhalation.

Air Pollutants↗
PubMed2000

Expression of heme oxygenase-1 in the lung in chronic hypoxia.

Heme oxygenase (HO)-1 is an oxygen-dependent enzyme that may regulate vascular tone and cell proliferation through the production of carbon monoxide (CO). We tested the hypothesis that HO-1 is upregulated in the lung in chronic hypoxia by exposing male Sprague-Dawley rats to 17,000 feet (395 Torr) for 0, 1, 3, 7, 14, or 21 days. After exposure, blood gases, carboxyhemoglobin (COHb) levels, and hematocrit were measured, and the lungs were either inflation fixed for immunohistochemistry or frozen for later measurement of HO enzyme activity, Western blot for HO-1 protein, and RT-PCR for HO-1 mRNA. The heart was excised and weighed, and the right-to-left heart weight ratio was determined. During hypoxia, the hematocrit increased progressively, reaching significantly higher values than the control value after 3 days. COHb levels increased above the control value after 1 day of hypoxia and increased progressively between 14 and 21 days, whereas arterial PO(2) and arterial PCO(2) did not vary significantly. HO-1 protein determined by Western blot increased for the first 7 days and declined thereafter; however, enzyme activity was elevated only after 1 day. Changes in HO-1 during hypoxia were localized by immunohistochemistry to inflammatory cells (early) and newly muscularized arterioles (later). Lung HO-1 mRNA normalized to glyceraldehyde-3-phosphate dehydrogenase was increased after 1 and 21 days. The data indicate that lung HO-1 protein and activity are upregulated only during early chronic hypoxia, whereas persistent COHb elevations indicate high endogenous CO production rates at nonpulmonary sites. If CO has antiproliferative properties, the lack of HO enzyme activity in the lung may be permissive for pulmonary vascular proliferation in hypoxia.

Animals↗
PubMed2000

Diminished injury in hypotransferrinemic mice after exposure to a metal-rich particle.

Using the hypotransferrinemic (Hp) mouse model, we studied the effect of altered iron homeostasis on the defense of the lung against a catalytically active metal. The homozygotic (hpx/hpx) Hp mice had greatly diminished concentrations of both serum and lavage fluid transferrin relative to wild-type mice and heterozygotes. Fifty micrograms of a particle containing abundant concentrations of metals (a residual oil fly ash) was instilled into wild-type mice and heterozygotic and homozygotic Hp animals. There was an oxidative stress associated with particle exposure as manifested by decreased lavage fluid concentrations of ascorbate. However, rather than an increase in lung injury, diminished transferrin concentrations in homozygotic Hp mice were associated with decreased indexes of damage, including concentrations of relevant cytokines, inflammatory cell influx, lavage fluid protein, and lavage fluid lactate dehydrogenase. Comparable to other organs in the homozygotic Hp mouse, siderosis of the lung was evident, with elevated concentrations of lavage fluid and tissue iron. Consequent to these increased concentrations of iron, proteins to store and transport iron, ferritin, and lactoferrin, respectively, were increased when assayed by immunoprecipitation and immunohistochemistry. We conclude that the lack of transferrin in Hp mice did not predispose the animals to lung injury after exposure to a particle abundant in metals. Rather, these mice demonstrated a diminished injury that was associated with an increase in the metal storage and transport proteins.

Air Pollution↗