Pulmonary Inflammation in Mice Exposed to Mainstream Cigarette Smoke

Male C57Bl/6 (C57) and ICR mice were exposed by nose-only inhalation to mainstream cigarette smoke (MS) from 2R4F reference cigarettes, at concentrations of 75, 250, and 600 μ g of total particulate matter (TPM) per liter, for up to 6 mo. Respiratory-tract tissue (nose, larynx, and lung), blood, and bronchoalveolar lavage fluid (BALF) samples were collected and analyzed at several time points. Blood samples were analyzed for biomarkers of exposure (COHb and nicotine). BALF was analyzed for biomarkers of cell injury, inflammation, oxidative stress, enzyme activity, and cytokines. Blood COHb and plasma nicotine concentrations increased in a dose-dependent manner, confirming smoke exposure. Mild emphysema was observed following 28 wk of exposure. Macrophage accumulation and inflammatory infiltrates were observed around the alveolar ducts and adjacent vasculature. There was a ～ 13% increase in mean linear intercept (L_m) only in ICR mice exposed to 600 μ g/L TPM. There were no significant changes in biomarkers of oxidative stress secondary to smoke exposures; however, 8-isoprostane significantly increased following the 13-wk post-inhalation period. BALF macrophage and neutrophil counts were rapidly and consistently elevated, while lymphocyte counts gradually increased over time. MS-induced inflammatory responses observed in this study are comparable to changes reported in chronic smokers, supporting the role of chronic inflammation in the pathogenesis of emphysema. However, mild emphysema in minimal numbers of mice suggests that MS exposure concentration and/or duration in the current study were not sufficient to induce a definitive emphysema phenotype.     

Restraint of Animals Required for Nose-Only Inhalation Toxicologic Studies Suppresses Pulmonary Antibacterial Defenses

Abstract

This study was designed to determine whether immobilization of animals in restraint holders, commonly used for nose-only inhalation toxicologic studies, alters the antibacterial defenses of the lungs. A second objective was to investigate if the stress-induced impairment of lung defenses could be reduced or eliminated either by allowing a suitable time to elapse (recovery) after restraint or by conditioning (training). Restraint of animals for 4 h before bacterial challenge suppressed the bactericidal activity of murine lungs for at least 12 h; by 20 h the antibacterial defenses were restored to normal. Training the animals in the restraint holders for 4 h/day for 2 days eliminated the bactericidal dysfunction. Restraining the animals after bacterial challenge also suppressed the bactericidal activity of the lungs, which took 4 days of training to abrogate. These data demonstrate that immobilization of animals impairs pulmonary antibacterial defenses and raises questions whether other pulmonary biologic responses assessed in nose-only exposure toxicologic studies may also be effected by restraint stress.     

Alteration in Cellular and Biochemical Markers of Pulmonary Toxicity in Rat Lung Exposed to Carpet Dusts

Epidemiological studies of workers in weaving units in carpet industries have shown relationships between the airborne dust concentrations and pulmonary ill health. Therefore, to predict the health risk of carpet weavers, this preliminary experiment was conducted to evaluate the effect of carpet dust (knotted, tufted) on cellular and biochemical mediators considered as potential biological markers of lung injury. Lung cytoplasmic (lactate dehydrogenase, LDH), lysosomal (acid phosphatase, ACP), type II (alkaline phoshatase, ALP) and Clara-cell marker enzymes (gamma-glutamyl transferase, GGT) were monitored in rat cell-free lung lavage (BAL) during postexposure days 1, 4, 8, and 16. Furthermore, lung microsomal cytochrome P-450 (CYP450) and Clara-cell secretory protein (CC16) content in BAL was also evaluated. These pulmonary marker enzymes were significantly elevated during the postexposure period over the respective untreated control; however, tufted carpet dust shows more responses than knotted carpet dust. Lung CYP450 content was reduced significantly at early days; the pattern shows the reoccurrence of CYP450 content in the later stage of postexposure to carpet dust. Clara-cell secretory protein in BAL shows decline in the carpet-treated group; however, tufted carpet shows more decline than knotted carpet. Thus, reduction in CC16 level may have important implication in the development of chronic lung inflammation and diseases. Present investigation found that modulation of these cellular marker enzymes is clear evidence of pulmonary damage caused by exposure to carpet dust.     

Reduced Fluoride Sensitivity of Liver Cells from Rats Chronically Exposed to Fluoride

Abstract: The fluoride sensitivity, determined as effect on protein synthesis (incorporation of ¹⁴C-leucine), of liver and kidney cells in suspension culture was explored. The cells were freshly prepared by collagenase perfusion from rats given drinking water with or without addition of 100 p.p.m. (5.26 mM) fluoride for 9–28 weeks. The fluoride sensitivity of the liver cells from rats given fluoridated water for more than 9 weeks was decreased compared to cells from control rats, whereas the fluoride sensitivity of the kidney cells from fluoride exposed and control rats appeared similar. Fluoride resistance (i.e. decreased sensitivity) may thus develop also in cells in vivo. When exposed to 3 mM NaF for 1 hour the intracellular concentration of fluoride in liver cells from fluoride exposed and control animals was similar.     

Lung Tumor Response in Strain a Mice Exposed to Tobacco Smoke: Some Dose-Effect Relationships

Male strain A/J mice were exposed for 5 mo in a whole-body inhalation chamber to 3 different concentrations of a mixture of cigarette sidestream and mainstream smoke (99, 120, and 176 mg/m³ of total suspended particulate material, TSP). After an additional 4-mo recovery period in air, lung tumor multiplicities and incidences were determined. The two highest smoke concentrations produced significantly more lung tumors than did the low dose and control groups, although the response to the high was slightly less than to the medium dose. Lung tumor incidences were in all three groups significantly higher than in controls. Lung displacement volume was increased in a dose-dependent manner, but morphometric analysis of the tissues failed to provide evidence for airspace enlargement. Plasma cotinine levels were dose-dependent and similar after 1-day and 5-day exposure. The shape of the dose-response curve and a comparison with previous data suggest that cigarette smoke is only a comparatively weak mouse lung carcinogen.     

Lack of Lung Damage in Mice Following Administration of Tertiary Butylhydroquinone

ABSTRACT

Tertiary butylhydroquinone (TBHQ), a phenolic antioxidant used in foods, was tested for its potential to produce lung damage in mice similar to that seen following administration of butylated hydroxytoluene (BHT). Male mice (CRL:CD-1) were given single intraperitoneal injections of 62.5, 125, 250 or 500 mg/kg TBHQ or 300, 625 or 1230 mg/kg BHT in corn oil. Survivors were killed five days after treatment and the lungs were removed, weighed, and processed for histologic examination. Lung weights of the TBHQ treated animals were comparable to the controls, while BHT produced a statistically significant increase in lung weight. Histologically, BHT produced hyperplasia of pulmonary pneumocytes as previously reported. No treatment-related lung lesions were seen in the TBHQ mice. The results of this study indicate that TBHQ does not produce pulmonary lesions in mice.     

Pulmonary Host Defenses and Resistance to Infection Following Subchronic Exposure to Phosgene

Abstract

Acute exposure to phosgene, a toxic gas widely used in industrial processes, decreases resistance to bacteria in mice and rats and enhances susceptibility to B16 tumor cell challenge in mice. These effects appear to be due to impaired alveolar macrophage and natural killer (NK) cell activity, respectively. In this study effects of repeated phosgene exposures on bacterial infection and NK activity were determined. Rats were exposed for 4 or 12 wk, 6 h/day, 5 days/wk, to 0.1 or 0.2 ppm phosgene or 2 days/wk to 0.5 ppm and infected by aerosol with Streptococcus zooepidemicus immediately after the last exposure. An additional group was also infected after 4 wk of recovery following the 12-wk exposure regimens. Bronchoalveolar lavage (BAL) fluid was assessed 0, 6, and 24 h postinfection for bacteria and inflammatory cells. Differential cell counts in BAL and pulmonary NK activity were also determined in uninfected rats 18 Is after the last exposure. All phosgene exposures impaired clearance of bacteria from the lungs and caused an increase in polymorphonuclear leukocytes (PMNs) in BAL of infected rats. Effects in the 0.5 ppm exposure group were greatest, and were significantly different from those in the 0.2 ppm exposure group, although the product of concentration × time was the same. BAL cell counts and bacterial clearance were normal in rats assessed 4 wk after the 12-wk phosgene exposures. Bacterial clearance and the PMN response to infection following repeated exposure were similar to those observed after a single exposure; that is, for these endpoints, effects due to repetitive exposure were neither additive nor attenuated. In contrast, NK activity was suppressed only at the 0.5 ppm level, and the magnitude of suppression was much less than that following acute exposure, suggesting that attenuation of this effect did occur with repeated exposure. The data indicate that susceptibility to streptococcal infection is a sensitive endpoint for phosgene toxicity following subchronic exposure.     

茶多酚对博莱霉素导致的小鼠肺纤维化模型的干预作用及其机制

目的:研究茶多酚(简称TP)对博莱霉素(bleomycin,BLM)所致肺纤维化动物模型的干预作用,并探讨其作用机制。方法:将昆明种小鼠随机分为假手术组、模型组、醋酸泼尼松组、TP(大、中、小剂量)组。经气管内1次性灌注BLM复制肺纤维化动物模型,造模后第2天起各给药组给予相应药物灌服给药,药物干预后第7,14,28天分别处死动物,观察肺系数、肺组织羟脯氨酸(HYP)、谷胱甘肽(GSH)含质量和总抗氧化能力(T-Aoc)的变化;取固定部位肺组织作病理切片观察其病理形态;免疫组织化学技术测定肺组织中α-平滑肌肌动蛋白(α-SMA)、转化生长因子β1(TGF-β1)和I型胶原(Col-I)蛋白的表达。结果:TP可显著降低肺纤维化小鼠的肺系数、肺组织中HYP的质量,显著提高肺组织的T-Aoc和GSH质量(P<0.01,P<0.05);光镜观察显示,给予TP干预的小鼠的肺泡炎程度与肺纤维化程度明显减轻(P<0.01,P<0.05);免疫组织化学结果显示TP能显著抑制肺组织中α-SMA、TGF-β1和Col-I蛋白的表达(P<0.01,P<0.05)。结论:TP对博莱霉素所致小鼠肺纤维化具有一定的干预作用,其作用机制可能与下调TGF-β1蛋白的表达和抑制肺肌成纤维细胞的活化以及下调其下游靶基因Col-I蛋白,从而抑制细胞外基质的过度生成以及增加机体的抗氧化能力有关。     

Characterization of Lung Injury following Abrin Pulmonary Intoxication in Mice: Comparison to Ricin Poisoning

Abrin is a highly toxic protein obtained from the seeds of the rosary pea plant Abrus precatorius, and it is closely related to ricin in terms of its structure and chemical properties. Both toxins inhibit ribosomal function, halt protein synthesis and lead to cellular death. The major clinical manifestations following pulmonary exposure to these toxins consist of severe lung inflammation and consequent respiratory insufficiency. Despite the high similarity between abrin and ricin in terms of disease progression, the ability to protect mice against these toxins by postexposure antibody-mediated treatment differs significantly, with a markedly higher level of protection achieved against abrin intoxication. In this study, we conducted an in-depth comparison between the kinetics of in vivo abrin and ricin intoxication in a murine model. The data demonstrated differential binding of abrin and ricin to the parenchymal cells of the lungs. Accordingly, toxin-mediated injury to the nonhematopoietic compartment was shown to be markedly lower in the case of abrin intoxication. Thus, profiling of alveolar epithelial cells demonstrated that although toxin-induced damage was restricted to alveolar epithelial type II cells following abrin intoxication, as previously reported for ricin, it was less pronounced. Furthermore, unlike following ricin intoxication, no direct damage was detected in the lung endothelial cell population following abrin exposure. Reduced impairment of intercellular junction molecules following abrin intoxication was detected as well. In contrast, similar damage to the endothelial surface glycocalyx layer was observed for the two toxins. We assume that the reduced damage to the lung stroma, which maintains a higher level of tissue integrity following pulmonary exposure to abrin compared to ricin, contributes to the high efficiency of the anti-abrin antibody treatment at late time points after exposure.     

氯化镉对大鼠子宫内膜细胞的增殖作用

目的研究氯化镉对去卵巢大鼠子宫内膜细胞的增殖作用。方法将成年雌性大鼠去卵巢后,给予不同剂量的CdClz（0．08mg,／kg、0．40mg／kg和2．00mg／kg）连续3d,观察子宫内膜细胞有丝分裂指数和嗜银染色颗粒数。结果氯化镉中、高荆量组有丝分裂指数分别为0．81％,0．97％,均高于阴性对照组,差异有显著性（P〈0．05）。同时氯化镉高剂量组嗜银染色颗粒数为1．36～1．53,与阴性对照组相比,差异有显著性（P〈0．05）。结论氯化镉能加速细胞的分裂和增殖,因此,推断它在大鼠体内可能具有雌激素样作用。     

Incapacitation and Treatment of Rats Exposed to a Lethal Dose of Sulfuryl Fluoride

Incapacitation and Treatment of Rats Exposed to a Lethal Doseof Sulfuryl Fluoride. NIT-SCHKE, K., D., ALBEE, R.R., MATTSSON,J.L., AND MILLER, R.R. (1986). Fundam. Appl. Toxicol. 7, 664–670.Rats exposed to 4000 ppm sulfuryl fluoride (VIKANE^* gas fumigant,SO₂F₄) were incapacitated within 45 min and died within severalhours after exposure. Exposure to higher concentrations resultedin a shorter time to incapacitation and death occurred withinminutes. Treatment with calcium gluconate before exposure to4000 ppm SO2F2 for 45 min resulted in 80%survival. However,calcium gluconate did not alleviate SO₂F₄-induced convulsions.Administration of phenobarbital before or after exposure to4000 ppm SO₂F₄ for 45 min effectively reduced the frequencyand severity of convulsions and resulted in survival of allanimals. Exposure of rats to 10,000 ppm SO₂F₄ for 15 min followedby treatment with phenobarbital reduced the frequency of convulsionsand delayed death, but did not prevent death. Diazepam was lesseffective than phenobarbital while diphenylhydantoin had nobeneficial effect and, in fact, made the convulsions more severeand longer in duration. The results of this study indicate thatphenobarbital was effective in ameliorating the acute toxiceffects of an overexposure to SO₂F₄ in rats.     

Diesel Exhaust Is Not a Pulmonary Carcinogen in CD-1 Mice Exposed under Conditions Carcinogenic to F344 Rats

Differences among laboratory animal species in the pulmonarycarcinogenicity of chronic inhalation exposure to diesel exhausthave raised several important interpretive issues. Under similarheavy exposure conditions, it is clear that diesel exhaust isa pulmonary carcinogen in rats, but not in Syrian hamsters.Previous reports give conflicting views of the response of mice,which is presently considered equivocal. This report describescarcinogenicity results from a bioassay of CD-1 mice conductedin parallel with a previously reported bioassay of F344 rats(Mauderly et al. (1987) Fundam. Appl. Toxicol. 9, 208–221).Exposure to whole diesel exhaust 7 hr/day, 5 days/week for 24months at soot concen trations of 0.35, 3.5, or 7.1 mg/m³ causedaccumulations of soot in mouse lungs similar to those in lungsof rats and, like the results from rats, did not significantlyaffect survival or body weight. In contrast to the dose-relatedneoplastic response of rats, however, the exposures of micedid not increase the incidence of lung neoplasms. This findingis consistent with other data showing that mice, as well asSyrian hamsters, differ from rats in their lung neoplastic andnonneoplastic responses to heavy, chronic inhalation exposureto diesel exhaust soot and several other particles. Althoughrodents serve as useful indicators of potential human carcinogenichazards, it is not yet clear which, if any, rodent species havelung neoplastic responses that are useful for quantitative predictionsof human lung cancer risk from chronic inhalation of poorlysoluble, respirable particles.     

Neurotransmitter Metabolizing Enzymes and Plasma Butyrylcholinesterase in Mice Exposed to Trichloroethylene

Abstract: Acetylcholinesterase, glutamine synthetase, acid phosphatase and glutamate dehydrogenase activity in brain and cholinesterase activity in blood were investigated in mice exposed to 170 p.p.m. trichloroethylene (TCE) during 30 days. The neuronal enzymes remained unaffected which suggests that no general damage occurred to either the glia or the nerve cell populations. In accordance with this no effect was seen on acid phosphatase. In contrast, plasma butyrylcholinesterase increased twofold in exposed male mice while it was unaffected in females. Liver weight in males and females increased with a factor of 1.5 and 1.9, respectively.     

Ovalbumin-Induced Airway Inflammation and Fibrosis in Mice Also Exposed to Ozone

A murine model of allergen-induced airway inflammation was used to examine the effects of exposure to ozone on airway inflammation and remodeling. Sensitized BALB/c mice were exposed to ovalbumin aerosol for 4 wk before and after 2 wk of exposure to either 0.2 ppm or 0.5 ppm ozone. Other groups of mice were exposed to ovalbumin aerosol for 6 wk with continuous concurrent exposure to ozone during wk 1–6, or during intermittent concurrent exposure to ozone. Lung inflammation was measured by quantitative differential evaluation of lung lavage cells and by histological evaluation of stained lung sections. Alterations in lung structure (airway fibrosis) were evaluated by quantitative biochemical analysis of microdissected airways. The same total number of cells was observed in lavage fluid from animals exposed for 4 wk to ovalbumin alone or to ovalbumin for 4 wk immediately before or after exposure to 2 wk of 0.2 or 0.5 ppm ozone. Mice exposed to ovalbumin for 6 wk with concurrent exposure to either 0.2 ppm or 0.5 ppm ozone during wk 3–6 had a significant decrease in the total number of cells recovered by lavage. Values as low as 7% of the cell number found in mice exposed to ovalbumin aerosol alone were observed in the mice exposed to ovalbumin plus 0.2 ppm ozone during wk 3–6. There were significant differences in the cell differential counts in the lavage fluid from mice exposed to ovalbumin alone as compared with values from mice exposed to ovalbumin and ozone under all of the protocols studied. When ozone was given for 2 wk prior to ovalbumin exposure (Experiment 1), there were a high percentage of macrophages and low percentages of lymphocytes and eosinophils in the lung lavage. When ozone was given for 2 wk after ovalbumin exposure (Experiment 2), there were a moderate percentage of macrophages, a low percentage of eosinophils, and a high percentage of lymphocytes in the lung lavage. When ozone and ovalbumin were given simultaneously (Experiments 3 and 4), there were a high percentage of macrophages in the lavage with 0.2 ppm ozone and a high percentage of eosinophils. Ozone appears to antagonize the specific inflammatory effects of ovalbumin exposure, especially when given before or during exposure to ovalbumin. Airway remodeling was examined by two different quantitative methods. None of the groups exposed concurrently to ovalbumin and ozone had a significant increase in airway collagen content as compared to the matched groups of mice exposed to ovalbumin alone. The findings were consistent with an additive response of mice to simultaneous exposure to ovalbumin and ozone. Ozone exposure alone for 6 wk did not affect the number of goblet cells in the airways, while mice exposed to ovalbumin aerosol alone for 6 wk had about 25% goblet cells in their conducting airways. Concurrent exposure to ovalbumin and 0.2 ppm ozone caused significant increases in goblet cells (to 43% of total cells) in the conducting airways of the exposed mice. We conclude that when mice with allergen-induced airway inflammation induced by ovalbumin are also exposed to ozone, the lung inflammatory response may be modified, but that this altered response is dependent on the sequence of exposure and the concentration of ozone to which they are exposed. At the concentrations of ozone tested, we did not see changes in airway fibrosis. However, goblet-cell hyperplasia appeared to be increased in mice exposed concurrently to ovalbumin and 0.2 ppm ozone.     

Pulmonary Effects to Repeated Exposures to Paraquat Aerosol in Guinea Pigs

Pulmonary Effects of Repeated Exposures to Paraquat Aerosolin Guinea Pigs. BURLEIGH-FLAYER, H. AND ALARIE, Y. (1988). Fundam.Appl. Toxicol 10, 717–729. Exposure to paraquat, a widelyused herbicide, has been shown to produce a concentration dependentrapid, shallow breathing pattern in guinea pigs 18 hr followingexposure (H. Burleigh-Flayer and Y. Alarie, 1987, Arch Toxicol.59(6), 391–396). To further explore the pulmonary effectsfollowing exposure to paraquat, two experiments were carriedout. The first experiment consisted of exposing a group of guineapigs for a period of 4 hr to 0.7 mg/m³ paraquat aerosol andmonitoring respiratory variables for 2 weeks following the exposure.In the second experiment, three groups of guinea pigs were repeatedlyexposed to three concentrations of paraquat aerosol (0.1,0.4,and 0.8 mg/m³) for 6 hr a day, 5 days a week for 3 weeks. Respiratoryvariables were measured each day of these 3-week experiments.The respiratory variables evaluated in both experiments weretidal volume (VT) and respiratory frequency (/). These variableswere monitored during air breathing and upon challenge with10% CO₂ in 20% O₂ and 70% N₂ in order to evaluate the pulmonaryeffects of exposure to paraquat. Following a single exposureto 0.7 mg/m³ paraquat aerosol, a decrease in VT and increasein f were seen during air and 10% CO₂ challenge which reacheda maximum several days following exposure. After reaching maximalchanges, the respiratory variables returned to control values.With repeated 6-hr exposures to paraquat aerosol, guinea pigsexposed to 0.4 and 0.8 mg/m³ also displayed a rapid, shallowbreathing pattern. Adaptation to the exposures for these twoconcentration groups was evidenced by a return of the respiratoryvariables toward control levels. This adaptation typically occurredduring the first 7 days of exposures. A cumulative effect wastherefore not detected with repeated exposures to paraquat aerosols.     

Oxidative DNA Damage and Cell Proliferation in the Livers of B6C3F1 Mice Exposed to Pentachlorophenol in Their Diet

Pentachlorophenol (PCP), which has been used as a wood preservative,was reported to be a liver carcinogen in mice. To investigatethe initial effects of PCP administration under the same conditionsof exposure as in the carcinogenic study, we examined oxidativestress and cell proliferation, along with other hepatotoxicologicalparameters, in the livers of B6C3F1 mice fed PCP in their dietat doses of 0.03, 0.06, and 0.12% for up to 4 weeks. We observedsignificant increases of 8-OHdG levels in hepatic nuclear DNAat doses of 0.03% and above at 2 and 4 weeks. Likewise, dose-dependentincreases in the labeling index of cells were detected by countingthose that had incorporated 5-bromo-2'-deoxyuridine throughoutthe experimental period. Also, we found significant elevationsof the liver weights, concurrent with increases in hepatic DNAcontent in the treated mice, which again were dose-related.Serum aspartic transferase activity at doses of 0.06% and abovewere significantly increased despite these changes being slight.Also, histopathological examination provided no evidence ofnecrotic changes, but severe hepatocyte swelling in the treatedmouse livers. These data indicate that PCP might be able toinduce cell proliferation in the mouse liver, as well as induceoxidative DNA damage, suggesting both changes may play an importantrole in hepatocarcinogenesis.     

Modulation of Immune Function in Mice Exposed to 0.8 PPM Ozone

Abstract

Ozone has been shown to both enhance and suppress local and systemic immune responses, depending upon the experimental conditions and the immune parameters under investigation. To gain insight into this apparent immunomodulation, mice were continuously exposed to 0.8 ppm of 0, for 1, 3, 7, and 74 days prior to assessment of their immune function. Lymphocytes from the mediastinal lymph nodes (MLN) and the spleen were examined in order to distinguish local and systemic immune compartments, respectively. Ozone exposure resulted in an initial decrease in MLN cell numbers and spleenlbody weight ratios, which then returned to normal and increased above control values following more prolonged exposure. SirnilarlF the lymphocyte responses to mitogen and the splenocyte tumoricidal activity were initially decreased by exposure to 0.8 ppm ozone but later returned to control levels. To evaluate the effect of O₃ on the specific immune response, mice were immunized parenterally with ovalbumin (OA) followed by an aerosol boost with OA at 14 days. A week later the animals were assessed for specific immune responses. Exposure to 0.8 ppm O₃ for 14 days prior to assay resulted in an increased MLN lymphocyte response to specific antigen, while the splenic (systemic) response was decreased. Specific IgG and IgA antibody titers to the antigen in the bronchoalveolar lavage fluid were significantly suppressed following 7 and 14 days of exposure to O₃ but were unaltered in serum. These data, in part, explain the divergent responses observed by others. Ozone exposure initially suppresses local and systemic aspects of innate immunity, which recover or adapt over more prolonged exposure. Specific immune responses, however, can be either suppressed or enhanced following long-term exposure, depending upon the anatomical site and biological end point measured.     

Humoral and Cell-Mediated Immune Status of Mice Exposed to 1,1,2-Trichloroethane

ABSTRACT

The purpose of this study was to assess the immunological effects of 1,1,2-trichloroethane (TCE) on random-bred CD-I mice following 14 and 90 days of oral exposure. A toxicological evaluation conducted at the same time revealed the target organs to be the liver of both sexes and the erythroid elements of the females. The 14-day immunological range-finding study in males exposed to doses 1/10 and 1/100 the LD50 (38 and 3.8 mg/kg) revealed no alterations in either humoral or cell-mediated immune status. Following 90 days of exposure in the drinking water (4.4., 46, and 305 mg/kg for males and 3.9, 44, and 384 mg/kg for females), a more detailed series of immunological parameters was assessed. Cell-mediated immunity was unaltered in both sexes, while humoral immune status was depressed in both sexes, particularly when determined by hemagglutination titers. Macrophage function was depressed only in the males as indicated by the ability of thioglycolate-recruited peritoneal exudate cells (PEC) to phagocytize sheep erythrocytes (sRBC).     

Ovalbumin-Induced Airway Inflammation and Fibrosis in Mice Also Exposed to Ultrafine Particles

A murine model of allergen-induced airway inflammation was used to examine the effects of exposure to ultrafine particles (PM_2.5) on airway inflammation and remodeling. Lung inflammation was measured by quantitative differential evaluation of lung lavage cells. Alterations in lung structure (airway remodeling and fibrosis) were evaluated by quantitative biochemical analysis of microdissected airways and by histological evaluation of stained lung sections. The same total number of cells was observed in lavage fluid from animals exposed for 4 wk to ovalbumin alone or to ovalbumin for 4 wk immediately before or after 6 exposures over a period of 2 wk to 235 ug/m³ of PM_2.5. Mice exposed to ovalbumin for 6 wk with concurrent exposure to PM_2.5 during wk 5–6 had a significant decrease in the total number of cells recovered by lavage as compared with the group exposed to ovalbumin alone. There were no significant differences in the cell differential counts in the lavage fluid from mice exposed to ovalbumin alone as compared with values from mice exposed to ovalbumin and PM_2.5 under the protocols studied. Airway structural changes (remodeling) were examined by three different quantitative methods. None of the groups exposed to ovalbumin and PM had a significant increase in airway collagen content evaluated biochemically (i.e., total airway collagen) as compared to the matched groups of mice exposed to ovalbumin alone. Airway collagen content evaluated histologically by sirius red staining showed significant increases in all of the animals exposed to ovalbumin, with or without PM, and no apparent difference between the ovalbumin group and mice exposed to PM with ovalbumin. The findings were consistent with an additive, or less than additive, response of mice to exposure to PM and ovalbumin. Air or PM exposure alone for 2 wk did not result in observable goblet cells in the airways, while mice exposed to ovalbumin aerosol alone for 4 wk had about 20–25% goblet cells in their conducting airways. Sequential exposure to ovalbumin and PM (or vice versa) caused significant increases in goblet cells (to about 35% of total cells) in the conducting airways of the exposed mice. We conclude that when mice with allergen-induced airway inflammation induced by ovalbumin are also exposed to PM_2.5, the lung inflammatory response and airway remodeling may be modified, but that this altered response is dependent upon the sequence of exposure and the duration of exposure to ovalbumin aerosol. At the concentrations of PM tested, we did not see changes in airway fibrosis or airway reactivity for animals exposed to ovalbumin and PM_2.5 as compared with animals exposed only to ovalbumin aerosol. However, goblet-cell hyperplasia was significantly increased in mice exposed concurrently to ovalbumin and PM_2.5 as compared with mice exposed to ovalbumin alone.