Interstrain variation in murine susceptibility to inhaled acid-coated particles.

Epidemiologic studies have demonstrated a positive correlation between concentration of acid aerosol and increased morbidity and mortality in many urban environments. To determine whether genetic background is an important risk factor for susceptibility to the toxic effects of inhaled particles, we studied the interstrain (genetic) and intrastrain (environmental) variance of lung responses to acid-coated particle (ACP) aerosol in nine strains of inbred mice. A flow-past nose-only inhalation system was used to expose mice to ACPs produced by the cogeneration of a carbon black aerosol-sulfur dioxide (SO(2)) mixture at high humidity. Three days after a single 4-h exposure to ACPs or filtered air, mice underwent bronchoalveolar lavage, and cell differentials and total protein were determined as indexes of inflammation and epithelial permeability, respectively. To determine the effect of ACPs on alveolar macrophage (AM) function, lavaged AMs were isolated from exposed animals and Fc receptor-mediated phagocytosis was evaluated. Compared with air-exposed animals, there was a slight but significant exposure effect of ACPs on the mean number of lavageable polymorphonuclear leukocytes in C3H/HeJ and C3H/HeOuJ mice. ACP exposure also caused a significant decrease in AM phagocytosis. Relative to respective air-exposed animals, Fc receptor-mediated phagocytosis was suppressed in eight of nine strains. The order of strain-specific effect of ACPs on phagocytosis was C57BL/6J > 129/J > SJL/J > BALB/cJ > C3H/HeOuJ > A/J > SWR/J > AKR/J. There was no effect of ACP exposure on AM phagocytosis in C3H/HeJ mice. The significant interstrain variation in AM response to particle challenge indicates that genetic background has an important role in susceptibility. The effects of ACPs on AM function, inflammation, and epithelial hyperpermeability were not correlated (i.e., no cosegregation). This model may have important implications concerning interindividual variation in particle-induced compromise of host defense.

Inhaled particle-bound sulfate: effects on pulmonary inflammatory responses and alveolar macrophage function.

Acid sulfate-coated solid particles are a significant environmental hazard produced primarily by the combustion of fossil fuels. We have previously described a system for the nascent generation of carbonaceous particles surface coated with approximately 140 microg/m(3) acid sulfate [cpSO(4)(2-); 10 mg/m(3) carbon black (CB) and 10 ppm sulfur dioxide (SO(2)) at 85% relative humidity (RH)]. The effects of inhaled cpSO(4)(2-) on pulmonary host defenses are assessed in the present work. Mice were acutely exposed (4 h) to either 10 mg/m(3) CB, 10 ppm SO(2), or their combination at 10% or 85% RH in a nose-only inhalation chamber. No evidence of an inflammatory response was found following any of the exposures as assessed by total cell counts and differential cell counts from bronchoalveolar lavage fluid. However, alveolar macrophage Fc receptor-mediated phagocytosis decreased only following exposure to 140 microg cpSO(4)(2-), significant suppression occurred after 24 h, maximal suppression occurred at 3 days postexposure, and recovery to preexposure levels required 7-14 days. Intrapulmonary bactericidal activity (IBA) was also suppressed only after exposure to 140 microg cpSO(4)(2-); suppression was maximal at 1 day postexposure and recovered by day 7. To assess the effects of lower cpSO(4)(2-) concentrations, mice were repeatedly exposed to 1 mg/m(3) CB and 1 ppm SO(2) at 85% RH ( approximately 20 microg/m(3) cpSO(4)(2-) for 4 h/day) for up to 6 days. A significant decrement in IBA was observed following 5 and 6 days of exposure. These studies indicated that acute or repeated exposure to cpSO(4)(2-) could alter pulmonary host defense mechanisms.

Genetic modeling of susceptibility to nitrogen dioxide-induced lung injury in mice.

We investigated the mode of inheritance of susceptibility to nitrogen dioxide (NO2)-induced lung injury in inbred mice. Susceptible C57BL/6J (B6) and resistant C3H/HeJ (C3) mice, as well as F1, F2, and backcross (BX) populations derived from them, were exposed to 15 parts per million NO2 for 3 h. Six hours after exposure, animals were lavaged, and differential cell counts and cell viability (cytotoxicity) were measured. Statistically significant (P < 0.05) differences in numbers of lavageable macrophages, epithelial cells, and dead cells were found between inbred strains. Distributions of cellular responses in F1 progeny overlapped both progenitors, and mean responses were intermediate. In C3:BX progeny, ranges of responses to NO2 closely resembled C3 mice, and means were not significantly different between populations. Ranges of cellular responses to NO2 in B6:BX and intercross progeny overlapped both progenitors; mean responses of both populations were intermediate to progenitors. Segregation analyses tested goodness of fit of phenotyping data with various inheritance models, and the highest likelihood for each cell response to NO2 was for the hypothesis two-unlinked loci general. We conclude that there are likely two major unlinked genes that account for differential susceptibility to acute NO2 exposure. The chromosomal location of the genes is not known.

Inhalation of acid coated carbon black particles impairs alveolar macrophage phagocytosis.

A flow-past nose-only inhalation system was used for the co-exposure of mice to carbon black aerosols (CBA) and sulfur dioxide (SO2) at varying relative humidities (RH). The conversion of SO2 to sulfate (SO4(-2)) on the CBA, at a fixed aerosol concentration, was dependent on RH and SO2 concentration. The effect of the aerosol-gas mixture on alveolar macrophage (AM) phagocytosis was assessed three days following exposure for 4 h. Exposure to 10 mg/m3 CBA alone at low RH (10%) and high RH (85%), to 10 ppm SO2 alone at both RH, and to the mixture at low RH had no effect on AM phagocytosis. In contrast, AM phagocytosis was significantly suppressed following co-exposure at 85% RH, the only circumstance in which significant chemisorption of the gas by the aerosol and oxidation to SO4(-2) occurred. The results suggest that fine carbon particles can be an effective vector for the delivery of toxic amounts of SO4(-2) to the periphery of the lung.

The effects of ozone on immune function.

A review of the literature reveals that ozone (O3) exposure can either suppress or enhance immune responsiveness. These disparate effects elicited by O3 exposure depend, in large part, on the experimental design used, the immune parameters examined as well as the animal species studied. Despite the apparent contradictions, a general pattern of response to O3 exposure can be recognized. Most studies indicate that continuous O3 exposure leads to an early (days 0-3) impairment of immune responsiveness followed, with continued exposures, by a form of adaptation to O3 that results in a re-establishment of the immune response. The effects of O3 exposure on the response to antigenic stimulation also depend on the time at which O3 exposure occurred. Whereas O3 exposure prior to immunization is without effect on the response to antigen, O3 exposure subsequent to immunization suppresses the response to antigen. Although most studies have focused on immune responses in the lung, numerous investigators have provided functional and anatomical evidence to support the hypothesis that O3 exposure can have profound effects on systemic immunity.

Respiratory aflatoxicosis: suppression of pulmonary and systemic host defenses in rats and mice.

Dietary aflatoxin B1 (AFB1) exposure impairs innate and acquired host defenses resulting in increased susceptibility to infections in domesticated animals. Experimental studies have confirmed this observation by demonstrating the immunosuppressive effects of AFB1 ingestion. In addition to being present in dietary components, AFB1 is also found in significant amounts in respirable particles of grain dust. To determine the effect of respiratory tract exposure to AFB1 on host defenses, rats and mice were exposed either by aerosol inhalation or intratracheal instillation to AFB1. Nose-only inhalation exposure of rats to AFB1 aerosols suppressed alveolar macrophage (AM) phagocytosis at an estimated dose of 16.8 micrograms/kg with the effect persisting for approximately 2 weeks. To determine whether another mode of respiratory tract exposure, intratracheal instillation, reflected inhalation exposure, animals were treated with increasing concentrations of AFB1 which also suppressed AM phagocytosis in a dose-related manner albeit at doses at least an order of magnitude more than that obtained by aerosol inhalation. Intratracheal administration of AFB1 also suppressed the release of tumor necrosis factor-alpha from AMs and impaired systemic innate and acquired immune defenses as shown, respectively, by suppression of peritoneal macrophage phagocytosis and the primary splenic antibody response. These findings demonstrate that experimental respiratory tract exposure to AFB1 suppresses pulmonary and systemic host defenses and indicates that inhalation exposure to AFB1 is an occupational hazard where exposure to AFB1-laden dust is common.

Concomitant exposure to carbon black particulates enhances ozone-induced lung inflammation and suppression of alveolar macrophage phagocytosis.

The goal of this study was to investigate whether coexposures to carbon black and O3 result in a toxicologic interaction in the lungs as quantitated by the inflammatory response and alveolar macrophage (AM) phagocytosis. This aim was accomplished through inhalation coexposures of Swiss mice for 4 h to target concentrations of 10 mg/m3 of carbon black and 1.5 ppm O3, or exposure to either agent alone. As a control for the coexposure experiments, mice were also exposed for 4 h to carbon black, followed immediately thereafter by exposure for 4 h to O3, or vice versa. At 24 h after exposure, the lungs of the animals were lavaged for quantitation of total and differential cell counts and assessment of AM Fc-receptor-mediated phagocytosis. Exposure to carbon black did not result in an inflammatory response, nor had it any effect on AM phagocytosis. Ozone exposure resulted in an inflammatory response in the lungs and suppression of AM phagocytosis. Both biologic parameters were significantly enhanced following combined exposure to the particle and the gas. Carbon black exposure either before or after O3 had no significant effect on AM phagocytosis as compared to O3 exposure alone. These data demonstrate the toxicologic interaction of coexposures to an inert particle and O3 on well-accepted biologic markers pulmonary toxicity. The mechanism for the enhanced biologic effect may be that the carbon black particle acts as a carrier mechanism for O3 to areas in the distal lung not accessible to O3 in the gaseous phase or that O3 alters the physicochemistry of the particulate from a nontoxic to a toxic form.

The toxicologic interactions resulting from inhalation of carbon black and acrolein on pulmonary antibacterial and antiviral defenses.

The goal of this study was to investigate whether coexposures to carbon black and acrolein result in a toxicologic interaction having effects on lung defenses against infectious agents. This aim was accomplished through in vivo studies with inhalation challenges of infectious agents that probe the functional integrity of the multicomponent system that comprises the integrated defenses of the lungs. Staphylococcus aureus was used for the alveolar macrophage (AM) surveillance phagocytic system, Proteus mirabilis for the dual phagocytic system composed of AMs and inflammatory polymorphonuclear leukocytes (PMNs), Listeria monocytogenes for the lymphokine-mediated arm of the acquired cellular immune response, and influenza A virus for the cytotoxic T-cell-mediated effector mechanism of cellular immunity. Exposures of Swiss mice to target concentrations of 10 mg/m3 of carbon black and 2.5 ppm acrolein for 4 hr/day for 4 days suppressed the intrapulmonary killing of S. aureus a day after exposure with a return to control levels by Day 7. In contrast, the coexposure enhanced the intrapulmonary killing of P. mirabilis which correlated with a significant increase in accessory phagocytic PMNs recovered from the lungs. Combined exposure to carbon black and acrolein also resulted in impaired elimination of L. monocytogenes and influenza A virus from the lungs. Neither exposure to carbon black alone nor exposure to acrolein alone had any effect on the functional integrity of lung defenses against the four infectious agents. These data demonstrate the effects of the toxicologic interaction of coexposures to an inert particle and acrolein on innate and acquired defenses of the lungs. The mechanism for the enhanced biologic effect may be that the carbon black particle acts as a carrier mechanism for acrolein to the deep lung.

Use of physical chemistry and in vivo exposure to investigate the toxicity of formaldehyde bound to carbonaceous particles in the murine lung.

Knowledge about the health effects of exposure to formaldehyde associated with automotive emissions is of pivotal importance in the risk assessment of this agent. Mobile sources emit many combustion-derived pollutants, including formaldehyde, in association with respirable carbon particles. Because it is hydrophilic, most of the inhaled formaldehyde is absorbed in the upper respiratory tract. However, if the organic vapor is adsorbed on respirable particles, formaldehyde may be deposited in the deep lung with the inhaled particles and may be available to interact adversely with cells along the lung parenchyma. On the respiratory surface, the alveolar macrophage phagocytic system plays the pivotal role in defending the lung against infectious agents. Susceptibility to respiratory infections is a relevant and sensitive indicator of the adverse effects of air pollution because acute and chronic exposures to a variety of air pollutants have been shown to decrease pulmonary antibacterial defenses. The goal of this research was to investigate whether exposure to formaldehyde decreases resistance to respiratory infections through dysfunctions of the alveolar macrophage phagocytic system. The study also explored whether interactions between formaldehyde and respirable carbon black particles alter susceptibility to respiratory infections and impairment of alveolar macrophage phagocytosis by delivering adsorbed formaldehyde to the deep lung with the inhaled particles. A carbon black, Regal GR, was used in these studies as a surrogate for the carbonaceous core of Diesel particulate matter. This material was selected to represent the worst-case scenario because the carbon black was expected to adsorb formaldehyde strongly. To accomplish this goal, mice were exposed to formaldehyde and to carbon black and formaldehyde combinations; increased susceptibility to respiratory infections was quantified by alveolar macrophage-dependent intrapulmonary killing of Staphylococcus aureus after an inhalation challenge with the bacterium. The salient findings of the bactericidal studies are as follows: Fifteen parts per million (ppm)* formaldehyde impaired the intrapulmonary killing of S. aureus when exposure followed the bacterial challenge. One ppm formaldehyde impaired the intrapulmonary killing of S. aureus when exposure preceded and was continued after the bacterial challenge. Coexposures to target concentrations of 3.5 mg/m3 carbon black and 2.5 ppm formaldehyde, or 10 mg/m3 carbon black and 5 ppm formaldehyde after the bacterial challenge had no effect on the intrapulmonary killing of S. aureus. Preexposure for four hours per day for four days to target concentrations of 3.5 mg/m3 carbon black and 2.5 ppm formaldehyde had no effect on the intrapulmonary killing of S. aureus when the assay was performed one day after the cessation of exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Experimental influenza virus infection, silicon dioxide polymorphs, and pulmonary fibrogenesis.

Inhalation exposure to silicon dioxide is known to result in acute lung injury followed by pulmonary fibrosis. Recently it has been shown that the acute lung damage during influenza virus infection is also followed by a fibrogenic process. To investigate the interaction between silicon dioxide and influenza virus infection, mice were intratracheally instilled with either alpha-quartz or cristobalite and 3 d later infected by aerosol inhalation with influenza A/PR8/34 virus. At 30, 60, and 90 d after infection, groups of virus infected and noninfected mice were sacrificed and their lungs assessed for total and differential lavage cell counts, lung hydroxyproline content, and morphometric analysis. The silica polymorphs did not alter the proliferation of virus in the lungs as quantitated by infectious virus titers of lung homogenates at 1, 5, 7, 10, and 13 d after infection. In noninfected animals, cristobalite was more reactive than alpha-quartz. The virus infection, in all parameters measured at all time intervals, enhanced the overall fibrogenic response of the lungs to the mineral dusts, suggestive of an additive fibrogenic model. The data demonstrate that virus infection following silicon dioxide exposure results in an interaction that leads to an enhanced fibrogenic response.

Myeloperoxidase-enhanced formation of (+-)-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene-DNA adducts in lung tissue in vitro: a role of pulmonary inflammation in the bioactivation of a procarcinogen.

Several studies have indicated a correlation between the presence of inflammation and the development of cancer. The aim of our study was to determine if pulmonary neutrophils could transform the proximate respiratory carcinogen (+-)-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (B[a]P-7,8-diol), to an ultimate carcinogenic metabolite via myeloperoxidase (MPO). To test this hypothesis, virus-free male DBA/2 mice were exposed by inhalation to the Gram-negative bacteria Proteus mirabilis for 1 h. For various time points post-exposure, bronchoalveolar lavage (BAL) was performed to determine total and differential cell counts, cellular MPO activity and production of superoxide. Twelve hours after the exposure, cellular activity of MPO as well as percentage and total number of polymorphonuclear leukocytes peaked and declined thereafter. At this same time point, cells from BAL exhibited increased release of superoxide, as measured by reduction of cytochrome c, after addition of soluble or particulate stimuli, 12-O-tetradecanoylphorbol-13-acetate (TPA) or opsonized zymosan respectively. These cells also elicited biotransformation of B[a]P-7,8-diol as evidenced by enhanced B[a]P-7,8-diol-derived chemiluminescence, tetraol formation and covalently bound adduct formation to exogenous DNA upon addition of TPA or opsonized zymosan. Moreover, the cell-free BAL fluid of infected mice contained substantial MPO activity in comparison to that of uninfected animals. Also, MPO enhanced the binding of B[a]P-7,8-diol to lung DNA in vitro. Unlike previous work emphasizing the potential roles of oxygen free radicals in tumor promotion, our results indicate a role of neutrophilic MPO in the initiation of carcinogenesis.

Aflatoxin B1--DNA adduct formation in rat liver following exposure by aerosol inhalation.

There is growing concern that human exposure to respirable grain dust contaminated with aflatoxin B1 (AFB1), a potent hepatocarcinogen, may be a risk factor for a number of human diseases. The objective of this study was to determine if liver DNA adduct formation occurs in rats following either intratracheal injection or nose-only aerosol inhalation exposure to AFB1. Male Fischer 344 rats were exposed by both routes of administration, and in preliminary data using intratracheal instillation, up to 2% of the administered dose became bound to liver DNA. In the nose-only aerosol inhalation experiments, rats were exposed for up to 120 min. Immediately after exposure, four animals were killed at each time point and their livers removed, DNA isolated and purified and analyzed for aflatoxin-DNA adducts by HPLC. A linear dose-response relationship was observed with a correlation coefficient of 0.96 between increasing length of exposure, and the amount of aflatoxin-N7-guanine adducts formed per mg DNA, the mean values and standard errors were 4.2 +/- 0.18, 15.3 +/- 4.3, 21.6 +/- 2.8 and 56.8 +/- 4.6 pmol aflatoxin-DNA adducts per mg DNA for the 20, 40, 60 and 120 min exposures respectively. The amounts of aflatoxin-DNA adducts formed were statistically significantly different (P less than 0.01) among the treated groups. These results indicate that aerosol inhalation is an effective route of exposure to AFB1 in rats that results in genotoxic damage in the liver.

Ozone reduces murine alveolar and peritoneal macrophage phagocytosis: the role of prostanoids.

Continuous ozone exposure (0.5 ppm, 1-14 days) reduced the phagocytic activity of murine alveolar and peritoneal macrophages. The response of peritoneal macrophages to ozone was virtually indistinguishable from the response of alveolar macrophages. When added exogenously, prostaglandin E2 (PGE2) inhibited alveolar and peritoneal macrophage phagocytosis. To test the hypothesis that prostanoids mediated the effects of ozone on macrophages, PGE levels of bronchoalveolar lavage fluid (BALF) and the phagocytic activity of macrophages from ozone-exposed mice pretreated with cyclooxygenase inhibitors were measured. PGE levels in BALF were increased following ozone exposure, with high levels of PGE associated with large decreases in phagocytic activity. Pretreatment with indomethacin and d-naproxen completely inhibited ozone-induced increases in PGE recovered by BAL and the suppression of peritoneal macrophage phagocytic activity. The inactive enantiomer of naproxen, l-naproxen, was without effect. Indomethacin partially inhibited ozone-induced suppression of alveolar macrophage phagocytic activity. These observations suggest that prostanoids play a key role in the response to ozone.

Suppression and recovery of the alveolar macrophage phagocytic system during continuous exposure to 0.5 ppm ozone.

Short-term exposures to ozone (O3) are known to impair pulmonary antibacterial defenses and alveolar macrophage (AM) phagocytosis in a dose-related manner. To determine the effect of prolonged O3 exposure, Swiss mice were exposed continuously to 0.5 ppm O3. At 1, 3, 7, and 14 days, intrapulmonary killing was assessed by inhalation challenge with Staphylococcus aureus or Proteus mirabilis and by comparing the number of viable bacteria remaining in the lungs at 4 h between O3-exposed and control animals. To evaluate the effects of O3 on the functional capacity of the AMs, Fc-receptor mediated phagocytosis was assessed. Ozone exposure impaired the intrapulmonary killing of S. aureus at 1 and 3 days; however, with prolonged exposure, the bactericidal capacity of the lungs returned to normal. This trend of an initial suppression followed by recovery was reflected in the phagocytic capacity of the AMs. In contrast to S. aureus, when P. mirabilis was used as the challenge organism, O3 exposure had no suppressive effect on pulmonary bactericidal activity, which correlated with an increase in the phagocytic cell population in the lungs. Morphologic examination of the lavaged macrophages showed that after 1 day of O3 exposure, the AMs were more foamy, and contained significantly more vacuoles. There was also a significant increase in binucleated cells at 3 days. These studies demonstrate that continuous exposure to O3 modulates AM-dependent lung defenses and points to the importance of the challenge organism and exposure protocol in establishing the adverse effect of O3.

Suppression of alveolar macrophage membrane-receptor-mediated phagocytosis by model particle-adsorbate complexes: physicochemical moderators of uptake.

In order to assess the abilities of alveolar macrophages (AMs) to phagocytize adsorbent-adsorbate complexes, rat AMs were incubated in vitro with two carbon blacks that have 15-fold differences in specific surface areas (ASTM classification N339 less than Black Pearls 2000) sorbed with 0.5 and 1.0 monolayer coverages of a polar and semi-polar adsorbate (acrolein and benzofuran, respectively). One-half monolayer coverages of N339 with either adsorbates significantly suppressed the phagocytosis of the carbon black, whereas one monolayer coverage did not. Neither adsorbate at either coverages affected the phagocytosis of Black Pearls 2000. The capacity of macrophages to phagocytize a subsequent particle challenge via the Fc-membrane receptor was quantified following treatment of the macrophages with the carbon black-adsorbate complexes. Treatment of the macrophages with carbon black N339-adsorbates complexes at both coverages impaired Fc-receptor-mediated phagocytosis, whereas no effect was observed when the carbon black was Black Pearls 2000. The results of this study indicate that the surface properties of the particles, the chemical properties of the chemical pollutants, and the interactions between particles and pollutants play a major role in defining the biological effect of particle-pollutant complexes.

Pulmonary antibacterial defenses during mild and severe influenza virus infection.

Severe influenza virus infections with pneumonic involvement are known to predispose the lungs to bacterial superinfections due to dysfunctions in the alveolar macrophage (AM) phagocytic system. To determine whether milder forms of influenza without pneumonic involvement have a similar outcome, pulmonary antibacterial defenses and AM phagocytosis were compared in murine models of mild and severe influenza virus A/HK/68 infections. Bactericidal activity was quantitated by the intrapulmonary killing of Staphylococcus aureus following aerosol challenge, whereas the functional capacity of the AMs was determined by Fc-receptor-mediated phagocytosis. With the severe virus infection, maximal suppression of bactericidal activity occurred on day 8 of infection and correlated with impairment of AM phagocytosis. A lesser but significant degree of suppression of pulmonary antibacterial defenses and AM phagocytosis was observed on the third day of the mild virus infection. The data demonstrate that mild influenza virus infections that are limited to the upper respiratory tract also impair pulmonary antibacterial defenses and may predispose the lungs to bacterial superinfections.

Sequential virus infections, bacterial superinfections, and fibrogenesis.

Parainfluenza 1 (Sendai) and influenza A virus pneumonitis cause severe lung damage, which, upon resolution, is followed by persistent alveolitis and parenchymal changes characterized by patchy consolidation and collagen deposition in the affected areas. To determine whether these long-term sequelae of the virus pneumonias are cumulative, mice were infected by aerosol inhalation with Sendai virus, influenza A virus, or Sendai followed 30 days later by influenza virus infection. At 90 days after the initial infection, mice were killed for assay of long-term parenchymal changes as quantitated lung hydroxyproline (Hpr) content, morphometric analysis, and total and differential lavage cell counts. Sendai virus infection did not alter the proliferation of influenza virus in the lungs as quantitated by infectious virus titers on Day 1, 3, 5, 7, 9, and 11 of influenza infection. At Day 90, lung Hpr content was cumulative in dual-infected mice, with a concomitant increase in the persistent alveolitis. To determine whether bacterial infections played a similar role in these long-term pulmonary sequelae, mice were infected by aerosol inhalation with either Staphylococcus aureus or Klebsiella pneumoniae or, during the course of influenza virus infection, superinfected with each of the bacteria. Sixty days after infection with K. pneumoniae alone, lung Hpr levels were significantly increased over those in noninfected control mice. Infection with S. aureus had no effect on the quantitated parameters of long-term lung damage. In influenza-infected mice superinfected with K. pneumoniae, lung Hpr content was significantly increased over that of S. aureus did not elevate any quantitated parameter of lung damage when compared with the virus alone.(ABSTRACT TRUNCATED AT 250 WORDS)

A genetic model for evaluation of susceptibility to ozone-induced inflammation.

We examined ozone-induced airway inflammatory responses in inbred mice, and progeny of crosses between them, to investigate genetic susceptibility to ozone. Nine strains of male mice (18-23 g, 5-7 wk) were exposed for 3 h to 2 ppm ozone (O3) or filtered air (control), and pulmonary inflammation was assessed 2, 6, and 24 h after exposure by inflammatory cell counts and total protein content in bronchoalveolar lavage (BAL). The time course of the response to O3 was consistent between the strains. The maximum change in polymorphonuclear leukocytes (PMNs) was detected 6 h after O3, and the maximum increase in BAL protein occurred 24 h postexposure. Air controls exhibited no detectable changes in the parameters of inflammation at any time. The phenotypes of the C57BL/6J (B6, termed susceptible) and C3H/HeJ (C3, termed resistant) strains were easily distinguished by the magnitude of their inflammatory responses to O3. A 22-fold difference in PMNs was detected between the two strains 2 h after O3 (P less than 0.001), and a sixfold difference was found 6 h after O3 (P less than 0.001). Total BAL proteins were also significantly different between the B6 and C3 strains 6 h (P less than 0.01) and 24 h after O3 (P less than 0.001). To further evaluate the potential genetic contribution to the inflammatory response, the F1, F2, and backcross progeny from crosses between B6 and C3 strains were examined. The phenotypes of these progeny were consistent with the hypothesis that a single autosomal recessive gene at the Inf locus confers susceptibility to acute O3-induced influx of PMNs, but the genetic control of altered permeability is not clear.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression of alveolar macrophage membrane receptor-mediated phagocytosis by model and actual particle-adsorbate complexes. Initial contact with the alveolar macrophage membrane.

Alveolar macrophages were treated with carbon blacks and adsorbates in order to evaluate the biologic effect of adsorbate, adsorbent and adsorbate-adsorbent complexes. Their capacity to phagocytize a subsequent challenge via the Fc-membrane receptor was quantified. Phagocytosis was suppressed in a dose-related manner with increasing concentrations of both carbon blacks and adsorbates. Carbon black N339 covered with 0.5 monolayers of the adsorbates suppressed phagocytosis more than N339 without the adsorbates. Increasing the adsorbate acrolein coverage from 0.5 to greater than 2.0 monolayers suppressed phagocytosis in a dose-related manner. Finally, samples of diesel particulate matter collected from an engine operated on a pure hydrocarbon fuel with various oxidizers, air (PSU #1) and an oxidizer free of nitrogen (N-free) were tested. Treatment of the macrophages with PSU #1 had a negligible effect on phagocytosis whereas the N-free sample suppressed phagocytosis in a dose-related manner. The data show that alveolar macrophage Fc-receptor-mediated phagocytosis is affected by: carbon black and adsorbate identity and concentration, coverage of the carbon black with adsorbates, and the oxidizer used in the generation of particles emitted by a diesel engine.

Influenza virus infection, ozone exposure, and fibrogenesis.

Oxidant exposure following chemically induced lung injury exacerbates the tendency to develop pulmonary fibrosis. Influenza virus pneumonitis causes severe acute lung damage that, upon resolution, is followed by a persistent alveolitis and parenchymal changes characterized by patchy interstitial pneumonia and collagen deposition in the affected areas. To determine whether oxidant exposure exacerbates the virus-induced alveolitis and residual lung damage, mice were infected by aerosol inhalation with influenza A virus and continuously exposed to 0.5 ppm ozone or ambient air. Noninfected control mice were exposed to either ambient air or ozone. On various days during the first month after infection, groups of mice were sacrificed and their lungs assessed for acute injury (lung lavage albumin, total and differential cell counts, wet/dry ratios, and morphometry). At 30, 60, 90, and 120 days after infection, groups of mice were sacrificed for total and differential lavage cell counts, lung hydroxyproline content, and morphometric analysis. Ozone exposure did not alter the proliferation of virus in the lungs as quantitated by infectious virus titers of lung homogenates at 1, 4, 7, 10, and 15 days after virus infection but mitigated the virus-induced acute lung injury by approximately 50%. After Day 30 a shift in the character of the pulmonary lesions was observed in that continuous exposure to ozone potentiated the postinfluenzal alveolitis and structural changes in the lung parenchyma. Additional studies suggest that the mechanism for the enhanced postinfluenzal lung damage may be related to the oxidant impairing the repair process of the acute influenzal lung damage. These data demonstrate that ozone exposure mitigates acute virus-induced lung injury and potentiates residual lung damage.