Differential inflammatory potential of particulate matter (PM) size fractions from Imperial Valley, CA.

Particulate matter (PM) in Imperial Valley originates from a variety of sources such as agriculture, traffic at the border crossing, emissions from the cross-border city of Mexicali, and the drying lakebed of the Salton Sea. Dust storms in Imperial Valley, California regularly lead to exceedances of the federal air quality standards for PM10 (diameter less than 10 microns). To determine if there are differences in the composition and biological response to Imperial County PM by size, ambient PM samples were collected from a sampling unit stationed in the northern-most part of the valley, South of the Salton Sea. Ultrafine, fine, and coarse PM samples were collected and extracted separately. Chemical composition of each size fraction was obtained after extraction by using several analytical techniques, and biological response was measured by exposing a cell line of macrophages to particles and quantifying subsequent gene expression. Biological measurements demonstrated coarse PM induced an inflammatory response in macrophages measured in increases of inflammatory markers IL-1ß, IL-6, IL-8 and CXCL2 expression, whereas ultrafine and fine PM only demonstrated significant increases in expression of CYP1a1. These differential responses were due not only to particle size, but to the distinct chemical profiles of each size faction as well. Community groups in Imperial Valley have already completed several projects to learn more about local air quality, giving residents access to data that provides real-time levels of PM2.5 and PM10 as well as recommendations on health-based practices dependent on the current AQI (air quality index). However, to date there is no information on the composition or toxicity of ambient PM from the region. The data presented here could provide more definitive information on the toxicity of PM by size, and further inform the community on local air quality.

Wooden hutch space allowance influences male Holstein calf health, performance, daily lying time, and respiratory immunity.

Dairy calves in the western United States are commonly raised individually in wooden hutches with a space allowance of 1.23m(2)/calf. Recent legislative initiatives in California and across the United States were passed regarding concern over space allowance for farm animals. The objective of this study was to determine if rearing male Holstein calves in wooden hutches modified to increase space allowance would influence measures of performance, lying time per day, health, and respiratory immunocompetence. At 4d of age, 60 calves were randomly assigned to 1 of 3housing treatments: (1) conventional housing (CONV; 1.23m(2)/calf), (2) 1.5 × CONV (MOD; 1.85m(2)/calf), or (3) 3 × CONV (MAX; 3.71m(2)/calf). Intakes of milk and solid feed were recorded daily and body weight was measured at 0, 3, 6, 10, and 12 wk of age. For the first 3 wk of the trial, calves were scored daily for fecal consistency, hydration, and hide cleanliness. In addition, calves were scored for respiratory health (i.e., nasal and eye discharge, ear position) until 7 wk of age. The total lying duration per day was recorded using data loggers at 3, 6, and 10 wk of age. Eight clinically healthy calves from each treatment were sensitized with subcutaneous ovalbumin (OVA) and then challenged with aerosolized OVA to assess calf respiratory immunity at 11 wk of age. Bronchoalveolar lavage fluid (BALF) was collected 4d after the OVA challenge and analyzed for leukocyte differentials and OVA-specific IgG, IgG1, IgA, and IgE. Calf average daily gain and body weight were positively associated with space allowance at approximately 3 wk before weaning and throughout postweaning, respectively. A greater space allowance decreased lying time after 46d. Space allowance did not influence fecal consistency, but there was a tendency for MAX calves to take 1d longer to recover from loose feces than MOD calves. The MAX calves had the fewest (%) observations with feces on their body compared with CONV or MOD. At 3 wk of age, peripheral eosinophil concentrations decreased with increased space allowance. However, observations (%) of eye discharge increased with greater space allowance. Among calves challenged with OVA, MOD calves had the least BALF OVA-IgE, and the percent of BALF eosinophils decreased with increased space allowance. Increased space allowance for calves raised in wooden hutches may improve some measures of calf performance, health, and respiratory immunocompetence.

Cardiac Ischemia Reperfusion Injury Following Instillation of 20 nm Citrate-capped Nanosilver.

BACKGROUND: Silver nanoparticles (AgNP) have garnered much interest due to their antimicrobial properties, becoming one of the most utilized nano-scale materials. However, any potential evocable cardiovascular injury associated with exposure has not been reported to date. We have previously demonstrated expansion of myocardial infarction after intratracheal (IT) instillation of carbon-based nanomaterials. We hypothesized pulmonary exposure to Ag core AgNP induces a measureable increase in circulating cytokines, expansion of cardiac ischemia-reperfusion (I/R) injury and is associated with depressed coronary constrictor and relaxation responses. Secondarily, we addressed the potential contribution of silver ion release on AgNP toxicity. METHODS: Male Sprague-Dawley rats were exposed to 200 µl of 1 mg/ml of 20 nm citrate-capped Ag core AgNP, 0.01, 0.1, 1 mg/ml Silver Acetate (AgAc), or a citrate vehicle by intratracheal (IT) instillation. One and 7 days following IT instillation the lungs were evaluated for inflammation and the presence of silver; serum was analyzed for concentrations of selected cytokines; cardiac I/R injury and coronary artery reactivity were assessed. RESULTS: AgNP instillation resulted in modest pulmonary inflammation with detection of silver in lung tissue and alveolar macrophages, elevation of serum cytokines: G-CSF, MIP-1α, IL-1ß, IL-2, IL-6, IL-13, IL-10, IL-18, IL-17α, TNFα, and RANTES, expansion of I/R injury and depression of the coronary vessel reactivity at 1 day post IT compared to vehicle treated rats. Silver within lung tissue was persistent at 7 days post IT instillation and was associated with an elevation in cytokines: IL-2, IL-13, and TNFα and expansion of I/R injury. AgAc resulted in a concentration dependent infarct expansion and depressed vascular reactivity without marked pulmonary inflammation or serum cytokine response. CONCLUSIONS: Based on these data, IT instillation of AgNP increases circulating levels of several key cytokines, which may contribute to persistent expansion of I/R injury possibly through an impaired vascular responsiveness.

Lung effects of inhaled corticosteroids in a rhesus monkey model of childhood asthma.

BACKGROUND: The risks for infants and young children receiving inhaled corticosteroid (ICS) therapy are largely unknown. Recent clinical studies indicate that ICS therapy in pre-school children with symptoms of asthma result in decreased symptoms without influencing the clinical disease course, but potentially affect postnatal growth and development. The current study employs a primate experimental model to identify the risks posed by ICS therapy. OBJECTIVE: To (1) establish whether ICS therapy in developing primate lungs reverses pulmonary pathobiology associated with allergic airway disease (AAD) and (2) define the impact of ICS on postnatal lung growth and development in primates. METHODS: Infant rhesus monkeys were exposed, from 1 through 6 months, to filtered air (FA) with house dust mite allergen and ozone using a protocol that produces AAD (AAD monkeys), or to FA alone (Control monkeys). From three through 6 months, the monkeys were treated daily with ICS (budesonide) or saline. RESULTS: Several AAD manifestations (airflow restrictions, lavage eosinophilia, basement membrane zone thickening, epithelial mucin composition) were reduced with ICS treatment, without adverse effects on body growth or adrenal function; however, airway branching abnormalities and intraepithelial innervation were not reduced. In addition, several indicators of postnatal lung growth and differentiation: vital capacity, inspiratory capacity, compliance, non-parenchymal lung volume and alveolarization, were increased in both AAD and Control monkeys that received ICS treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Incomplete prevention of pathobiological changes in the airways and disruption of postnatal growth and differentiation of airways and lung parenchyma in response to ICS pose risks for developing primate lungs. These responses also represent two mechanisms that could compromise ICS therapy's ability to alter clinical disease course in young children.

Applying definitions of "asbestos" to environmental and "low-dose" exposure levels and health effects, particularly malignant mesothelioma.

Although asbestos research has been ongoing for decades, this increased knowledge has not led to consensus in many areas of the field. Two such areas of controversy include the specific definitions of asbestos, and limitations in understanding exposure-response relationships for various asbestos types and exposure levels and disease. This document reviews the current regulatory and mineralogical definitions and how variability in these definitions has led to difficulties in the discussion and comparison of both experimental laboratory and human epidemiological studies for asbestos. This review also examines the issues of exposure measurement in both animal and human studies, and discusses the impact of these issues on determination of cause for asbestos-related diseases. Limitations include the lack of detailed characterization and limited quantification of the fibers in most studies. Associated data gaps and research needs are also enumerated in this review.

Exposure of mice to concentrated ambient particulate matter results in platelet and systemic cytokine activation.

Increasingly, evidence suggests a role for a systemic procoagulant state in the pathogenesis of cardiac dysfunction subsequent to inhalation of airborne particulate matter. The authors evaluated blood cell parameters and markers of platelet activation in mice exposed to concentrated ambient particulate matter (CAPs) from the San Joaquin Valley of California, a region with severe particulate matter (PM) pollution episodes. The authors exposed mice to an average of 88.5 microg/m(3) of CAPs in a size range less than 2.5 microm for 6 h/day for 5 days per week for 2 weeks. Platelets were analyzed by flow cytometry for relative size, shape, aggregation, fibrinogen binding, P-selectin, and lysosomal-associated membrane protein-1 (LAMP-1) expression. Serum cytokines were analyzed by bead-based immunologic assays. CAPs-exposed mice had elevations in macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, interleukin (IL)-6, IL-10, tumor necrosis factor alpha (TNFalpha), macrophage colony-stimulating factor (M-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), platelet-derived growth factor (PDGF)-bb, and RANTES (regulated upon activation, normally T-expressed, and presumably secreted). Platelets were the only peripheral blood cells that were significantly elevated in number in CAPs-exposed mice. Flow cytometric analysis of unstimulated platelets from CAPs-exposed mice indicated size and shape changes, and platelets from CAPs-exposed animals had a 54% increase in fibrinogen binding indicative of platelet priming. Stimulation of platelets by thrombin resulted in up-regulation of LAMP-1 expression in CAPs-exposed animals and an increased microparticle population relative to control animals. These findings demonstrate a systemic proinflammatory and procoagulant response to inhalation of environmentally derived fine and ultrafine PM and suggests a role for platelet activation in the cardiovascular and respiratory effects of particulate air pollution.

Alveolar macrophage from cigarette smoke-exposed mice inhibits B lymphocyte proliferation stimulated with LPS.

BACKGROUND: Smokers have higher incidences of pulmonary diseases. This increased susceptibility may result from cigarette smoke (CS)-induced impairment of the pulmonary immune system. However, the mechanism(s) is not fully understood. OBJECTIVE: The aim of this study was to investigate the mechanism of the effect of alveolar macrophages (AM) from CS-exposed mice on B lymphocyte proliferation stimulated with bacterial lipopolysaccharide (LPS). METHODS: Mice were exposed to CS using a Hamburg smoking machine, and AM were obtained by bronchoalveolar lavage. Lymphocytes were harvested from spleen in normal mice. AM-mediated B lymphocyte proliferation stimulated with LPS was assessed by the (3)H-thymidine method, using lymphocytes as responding cells and AM from CS-exposed or non-CS-exposed mice. Generations of superoxide and hydrogen peroxide were analyzed by flow cytometry, using hydroethidine and dichlorofluorescein diacetate. RESULTS: AM from CS-exposed mice significantly inhibited B lymphocyte proliferation stimulated with LPS compared with AM from non-CS-exposed mice. Generations of superoxide and hydrogen peroxide were significantly increased in CS-exposed AM compared with non-CS-exposed AM. Inhibition of B lymphocyte proliferation stimulated with LPS by AM from CS-exposed mice was clearly recovered by superoxide dismutase and catalase. CONCLUSIONS: These results suggest that the inhibition by CS-exposed AM of LPS-induced B lymphocyte proliferation may be caused by the increased superoxide and hydrogen peroxide generation of CS. Therefore, these immunological inhibitions by CS could be associated with increased risk of pulmonary diseases.

Concordance between in vitro and in vivo dosimetry in the proinflammatory effects of low-toxicity, low-solubility particles: the key role of the proximal alveolar region.

We previously demonstrated the importance of the surface area burden as the key dose metric in the elicitation of inflammation in rat lungs by low-solubility, low-toxicity particles (LSLTP). We have now explored the dosimetry of LSLTP in vitro using epithelial cell interleukin (IL)-8 gene expression as a surrogate for potential of particles to cause inflammation. The proximal alveolar region (PAR) of the lung has been identified as a key site for the retention of respirable particles, as it receives high deposition but has slow clearance compared to the larger airways. For these reasons, a few days after exposure to particles the residual dose is concentrated in the PAR region. Re-expressing our rat lung data as particle surface area burden per unit of PAR surface area we obtained a threshold value for onset of inflammation of 1 cm(2)/cm(2). We carried out dose responses in vitro for onset of IL-8 gene expression with the same particles as we had used in vivo. When we expressed the in vitro dose as surface area dose per unit A549cell culture surface area, we obtained a threshold of 1 cm(2)/cm(2). This concordance between proinflammatory effects in vivo (PMN in BAL) and in vitro (epithelial IL-8 gene expression) confirms and supports the utility of the particle surface area metric and the importance of the PAR. These studies also open the way for future in vitro approaches to studying proinflammatory effects of a range of toxic particles based on sound dosimetry that complements animal use in particle toxicology.

Workshop summary: phosgene-induced pulmonary toxicity revisited: appraisal of early and late markers of pulmonary injury from animal models with emphasis on human significance.

A workshop was held February 14, 2007, in Arlington, VA, under the auspices of the Phosgene Panel of the American Chemistry Council. The objective of this workshop was to convene inhalation toxicologists and medical experts from academia, industry and regulatory authorities to critically discuss past and recent inhalation studies of phosgene in controlled animal models. This included presentations addressing the benefits and limitations of rodent (mice, rats) and nonrodent (dogs) species to study concentration x time (C x t) relationships of acute and chronic types of pulmonary changes. Toxicological endpoints focused on the primary pulmonary effects associated with the acute inhalation exposure to phosgene gas and responses secondary to injury. A consensus was reached that the phosgene-induced increased pulmonary extravasation of fluid and protein can suitably be probed by bronchoalveolar lavage (BAL) techniques. BAL fluid analyses rank among the most sensitive methods to detect phosgene-induced noncardiogenic, pulmonary high-permeability edema following acute inhalation exposure. Maximum protein concentrations in BAL fluid occurred within 1 day after exposure, typically followed by a latency period up to about 15 h, which is reciprocal to the C x t exposure relationship. The C x t relationship was constant over a wide range of concentrations and single exposure durations. Following intermittent, repeated exposures of fixed duration, increased tolerance to recurrent exposures occurred. For such exposure regimens, chronic effects appear to be clearly dependent on the concentration rather than the cumulative concentration x time relationship. The threshold C x t product based on an increased BAL fluid protein following single exposure was essentially identical to the respective C x t product following subchronic exposure of rats based on increased pulmonary collagen and influx of inflammatory cells. Thus, the chronic outcome appears to be contingent upon the acute pulmonary threshold dose. Exposure concentrations high enough to elicit an increased acute extravasation of plasma constituents into the alveolus may also be associated with surfactant dysfunction, intra-alveolar accumulation of fibrin and collagen, and increased recruitment and activation of inflammatory cells. Although the exact mechanisms of toxicity have not yet been completely elucidated, consensus was reached that the acute pulmonary toxicity of phosgene gas is consistent with a simple, irritant mode of action at the site of its initial deposition/retention. The acute concentration x time mortality relationship of phosgene gas in rats is extremely steep, which is typical for a local, directly acting pulmonary irritant gas. Due to the high lipophilicity of phosgene gas, it efficiently penetrates the lower respiratory tract. Indeed, more recent published evidence from animals or humans has not revealed appreciable irritant responses in central and upper airways, unless exposure was to almost lethal concentrations. The comparison of acute inhalation studies in rats and dogs with focus on changes in BAL fluid constituents demonstrates that dogs are approximately three to four times less susceptible to phosgene than rats under methodologically similar conditions. There are data to suggest that the dog may be useful particularly for the study of mechanisms associated with the acute extravasation of plasma constituents because of its size and general morphology and physiology of the lung as well as its oronasal breathing patterns. However, the study of the long-term sequelae of acute effects is experimentally markedly more demanding in dogs as compared to rats, precluding the dog model to be applied on a routine base. The striking similarity of threshold concentrations from single exposure (increased protein in BAL fluid) and repeated-exposure 3-mo inhalation studies (increased pulmonary collagen deposition) in rats supports the notion that chronic changes depend on acute threshold mechanisms.

Biodegradability of inhaled p-aramid respirable fiber-shaped particulates (RFP): mechanisms of RFP shortening and evidence of reversibility of pulmonary lesions.

These studies elucidated mechanisms of inhaled p-aramid respirable fiber-shaped particulates (RFP) biodegradation in the lungs of exposed rats and hamsters. We postulate that lung fluids coat/activate inhaled p-aramid RFP which deposits in the lung and promote enzymatic attack and consequent shortening. p-Aramid or cellulose (biopersistent control) RFP were instilled into the lungs of rats and the lungs digested 24 h later using two different (KOH or enzymatic) digestion techniques. In vivo, the enzyme but not the KOH solution produced shortening of p-aramid but not cellulose RFP recovered from the lungs. For in vitro studies, the two RFP-types were incubated with BAL fluids and underwent simulated digestions; also rat lung epithelial cells, macrophages or co-cultures were incubated with p-aramid and digested at 1, 24, or 168 h postexposure. The results of in vitro acellular studies demonstrated that only p-aramid RFP incubated in BAL fluids and digested by the enzyme method were shortened. In vitro cellular studies demonstrated a shortening of p-aramid RFP in macrophages and co-cultures but not in lung epithelial cells at 24 h and 1 week postexposure. These results demonstrate that lung fluids coat and catalyze the p-aramid RFP as a prelude for shortening and describe a likely mechanism for the biodegradability of inhaled p-aramid RFP in the lungs of exposed animals.

Perinatal exposure to environmental tobacco smoke upregulates nicotinic cholinergic receptors in monkey brain.

In humans, perinatal exposure to environmental tobacco smoke (ETS) is associated with neurobehavioral deficits. In the current study, we exposed Rhesus monkeys to ETS in late gestation and in the early neonatal period, and examined changes in neurotransmitter receptors in the brainstem and caudal portion of the cerebral cortex. Nicotinic acetylcholine receptors were markedly upregulated and the effect was selective in that there were no changes in m(2)-muscarinic acetylcholine receptors or in beta-adrenergic receptors. Nicotinic receptor upregulation is indicative of chronic cell stimulation by nicotine, and is a hallmark of nicotine-induced neuroteratogenesis. These results indicate that perinatal ETS exposes the fetus and neonate to quantities of nicotine that are sufficient to alter brain development.

A receptor-mediated mechanism of nicotine toxicity in oral keratinocytes.

Smoking and smokeless tobacco cause morbidity that originates from the epithelium lining of the skin and upper digestive tract. Oral keratinocytes (OKC) express nicotinic acetylcholine receptors (nAChRs) that bind nicotine (Nic). We studied the mechanism of the receptor-mediated toxicity of tobacco products on OKC. Preincubation of normal human OKC with Nic altered the ligand-binding kinetics of their nAChRs, suggesting that the nAChRs underwent structural changes. This hypothesis was confirmed by the finding that exposure of OKC to Nic causes transcriptional and translational changes. Through RT-PCR and immunoblotting, we found a 1.5- to 2.9-fold increase in the mRNA and protein levels of alpha3, alpha5, alpha7, beta2, and beta4 nAChR subunits. Exposure of OKC to Nic also changed the mRNA and protein levels of the cell cycle and cell differentiation markers Ki-67, PCNA, p21, cyclin D1, p53, filaggrin, loricrin, and cytokeratins 1 and 10. The nicotinic antagonist mecamylamine prevented these changes, which indicates that the Nic-induced changes in the expression of both the nAChR and the cell cycle and cell differentiation genes resulted from pharmacologic stimulation of nAChRs with Nic. To establish the relevance of these findings to the pathobiologic effects of tobacco products in vivo, we studied the above parameters in the oral tissue of rats and mice after their exposure for 3 weeks to environmental cigarette smoke or drinking water containing equivalent concentrations of Nic that are pathophysiologically relevant. The changes of the nAChRs and the cell cycle and cell differentiation genes were similar to those found in vitro. The results of indirect immunofluorescence assay of tissue specimens validated these findings. Thus, some pathobiologic effects of tobacco products in oral tissues may stem from Nic-induced alterations of the structure and function of keratinocyte nAChRs responsible for the physiologic regulation of the cell cycle by the cytotransmitter acetylcholine.

Perinatal exposure to environmental tobacco smoke induces adenylyl cyclase and alters receptor-mediated cell signaling in brain and heart of neonatal rats.

Perinatal exposure to environmental tobacco smoke (ETS) has adverse effects on neurobehavioral development. In the current study, rats were exposed to ETS during gestation, during the early neonatal period, or both. Brains and hearts were examined for alterations in adenylyl cyclase (AC) activity and for changes in beta-adrenergic and m2-muscarinic cholinergic receptors and their linkage to AC. ETS exposure elicited induction of total AC activity as monitored with the direct enzymatic stimulant, forskolin. In the brain, the specific coupling of beta-adrenergic receptors to AC was inhibited in the ETS groups, despite a normal complement of beta-receptor binding sites. In the heart, ETS evoked a decrease in m2-receptor expression. In both tissues, the effects of postnatal ETS, mimicking passive smoking, were equivalent to (AC) or greater than (m2-receptors) those seen with prenatal ETS mimicking active smoking; the effects of combined prenatal and postnatal exposure were equivalent to those seen with postnatal exposure alone. These data indicate that ETS exposure evokes changes in cell signaling that recapitulate those caused by developmental nicotine treatment. Since alterations in AC signaling are known to affect cardiorespiratory function, the present results provide a mechanistic link reinforcing the participation of ETS exposure, including postnatal ETS, in disturbances culminating in events like Sudden Infant Death Syndrome.

Prior exposure to aged and diluted sidestream cigarette smoke impairs bronchiolar injury and repair.

The bronchiolar injury/repair response to naphthalene (NA) in mice includes acute distal airway epithelial injury that is followed by epithelial proliferation and redifferentiation, which result in repair of the epithelium within 14 days. To test whether prior exposure to aged and diluted sidestream cigarette smoke (TS) would alter the injury/repair response of the airway epithelium, adult mice were exposed to either filtered air (FA) or smoke for 5 days before injection with either corn oil carrier (CO) or naphthalene. Mice were killed 1 and 14 days after naphthalene injury. Lung and lobar bronchus were examined and measured using high-resolution epoxyresin sections. The control group (FACOFA) that was exposed to filtered air/corn oil/filtered air contained airway epithelium similar to untreated controls at all airway levels. The group exposed to tobacco smoke/corn oil/filtered air (TSCOFA) contained some rounded cells in the small airways and some expansion of the lateral intercellular space in the larger airways. Necrotic or vacuolated cells were not observed. As expected, the epithelium in the group exposed to filtered air/naphthalene/filtered air (FANAFA) contained many light-staining vacuolated Clara cells and squamated ciliated cells within distal bronchioles during the acute injury phase. Repair (including redifferentiation of epithelial cells and restoration of epithelial thickness) was nearly complete 14 days after injury. The extent of Clara cell injury, as assessed in lobar bronchi, was not different between the four groups. Although the FANAFA group contained greater initial injury in the distal airways at 1 day, the group exposed to tobacco smoke/naphthalene/filtered air (TSNAFA) had the least amount of epithelial repair at 14 days after naphthalene treatment; many terminal bronchioles contained abundant squamated undifferentiated epithelium. We conclude that tobacco smoke exposure prior to injury (1) does not change the target site or target cell type of naphthalene injury, since Clara cells in terminal bronchioles are still selectively injured; (2) results in slightly diminished acute injury from naphthalene in distal bronchioles; and (3) delays bronchiolar epithelial repair.

Allergic asthma induced in rhesus monkeys by house dust mite (Dermatophagoides farinae).

To establish whether allergic asthma could be induced experimentally in a nonhuman primate using a common human allergen, three female rhesus monkeys (Macaca mulatta) were sensitized with house dust mite (Dermatophagoides farinae) allergen (HDMA) by subcutaneous injection, followed by four intranasal sensitizations, and exposure to allergen aerosol 3 hours per day, 3 days per week for up to 13 weeks. Before aerosol challenge, all three monkeys skin-tested positive for HDMA. During aerosol challenge with HDMA, sensitized monkeys exhibited cough and rapid shallow breathing and increased airway resistance, which was reversed by albuterol aerosol treatment. Compared to nonsensitized monkeys, there was a fourfold reduction in the dose of histamine aerosol necessary to produce a 150% increase in airway resistance in sensitized monkeys. After aerosol challenge, serum levels of histamine were elevated in sensitized monkeys. Sensitized monkeys exhibited increased levels of HDMA-specific IgE in serum, numbers of eosinophils and exfoliated cells within lavage, and elevated CD25 expression on circulating CD4(+) lymphocytes. Intrapulmonary bronchi of sensitized monkeys had focal mucus cell hyperplasia, interstitial infiltrates of eosinophils, and thickening of the basement membrane zone. We conclude that a model of allergic asthma can be induced in rhesus monkeys using a protocol consisting of subcutaneous injection, intranasal instillation, and aerosol challenge with HDMA.

Distribution of particulate matter and tissue remodeling in the human lung.

We examined the relationship between intrapulmonary particle distribution of carbonaceous and mineral dusts and remodeling of the airways along anatomically distinct airway paths in the lungs of Hispanic males from the central valley of California. Lung autopsy specimens from the Fresno County Coroner's Office were prepared by intratracheal instillation of 2% glutaraldehyde at 30 cm H(2)O pressure. Two distinct airway paths into the apico-posterior and apico-anterior portions of the left upper lung lobe were followed. Tissue samples for histologic analysis were generally taken from the intrapulmonary second, fourth, sixth, and ninth airway generations. Parenchymal tissues beyond the 12th airway generation of each airway path were also analyzed. There was little evidence of visible particle accumulation in the larger conducting airways (generations 2-6), except in bronchial-associated lymphoid tissues and within peribronchial connective tissue. In contrast, terminal and respiratory bronchioles arising from each pathway revealed varying degrees of wall thickening and remodeling. Walls with marked thickening contained moderate to heavy amounts of carbonaceous and mineral dusts. Wall thickening was associated with increases in collagen and interstitial inflammatory cells, including dust-laden macrophages. These changes were significantly greater in first-generation respiratory bronchioles compared to second- and third-generation respiratory bronchioles. These findings suggest that accumulation of carbonaceous and mineral dust in the lungs is significantly affected by lung anatomy with the greatest retention in centers of lung acini. Furthermore, there is significant remodeling of this transitional zone in humans exposed to ambient particulate matter.

Perinatal exposure to environmental tobacco smoke alters cell signaling in a primate model: autonomic receptors and the control of adenylyl cyclase activity in heart and lung.

Perinatal exposure to environmental tobacco smoke (ETS) is known to have adverse effects on respiratory function in conjunction with changes in autonomic responses. In the current study, Rhesus monkeys were exposed to ETS during late gestation and in the early neonatal period. Hearts and lungs were examined for changes in beta-adrenergic and m2-muscarinic cholinergic receptors, and for alterations in adenylyl cyclase activity. Whereas there were no changes in the heart, there was robust induction of adenylyl cyclase in the lung; previous work with prenatal nicotine exposure in rodent models has shown that adenylyl cyclase induction is associated with a shift towards predominance of cholinergic over adrenergic responses. These data indicate that perinatal ETS exposure evokes changes in cells signaling that they are selective for the lung and that may ultimately reflect adverse effects at the level of physiological function.

Surfactant treatment effects on lung structure and type II cells of preterm ventilated lambs.

We evaluated surfactant treatment effects on lung morphology and alveolar type II cells of preterm ventilated lambs. Lambs were ventilated for 10 h following treatment of the right lung with natural surfactant. Lung parenchyma from the surfactant-treated right and the untreated left lung was compared morphometrically. Mechanical ventilation without surfactant resulted in distention of alveolar ducts accompanied by shallowing and loss of well-defined alveoli without disruption of collagen or elastin fibers. Surfactant treatment almost completely prevented these changes. The percent of normal parenchyma was 82 +/- 7% in surfactant-treated lobes and 26 +/- 5% in the nontreated lobes (p < 0.05). Type II cells became flatter in lungs ventilated without surfactant, and cell shape was preserved by surfactant treatment. The volume densities of lamellar bodies and multivesicular bodies in alveolar type II cells were not changed by surfactant treatment. With or without surfactant treatment, mechanical ventilation was associated with a shift in lamellar body distribution to a smaller size and a decrease in glycogen content of type II cells. Surfactant treatment of the preterm lung prevents alveolar distortion and atelectasis, but does not result in changes in subcellular organelles in immature type II cells.

The mammalian respiratory system and critical windows of exposure for children's health.

The respiratory system is a complex organ system composed of multiple cell types involved in a variety of functions. The development of the respiratory system occurs from embryogenesis to adult life, passing through several distinct stages of maturation and growth. We review embryonic, fetal, and postnatal phases of lung development. We also discuss branching morphogenesis and cellular differentiation of the respiratory system, as well as the postnatal development of xenobiotic metabolizing systems within the lungs. Exposure of the respiratory system to a wide range of chemicals and environmental toxicants during perinatal life has the potential to significantly affect the maturation, growth, and function of this organ system. Although the potential targets for exposure to toxic factors are currently not known, they are likely to affect critical molecular signals expressed during distinct stages of lung development. The effects of exposure to environmental tobacco smoke during critical windows of perinatal growth are provided as an example leading to altered cellular and physiological function of the lungs. An understanding of critical windows of exposure of the respiratory system on children's health requires consideration that lung development is a multistep process and cannot be based on studies in adults.

Workshop to identify critical windows of exposure for children's health: immune and respiratory systems work group summary.

Fetuses, infants, and juveniles (preadults) should not be considered simply "small adults" when it comes to toxicological risk. We present specific examples of developmental toxicants that are more toxic to children than to adults, focusing on effects on the immune and respiratory systems. We describe differences in both the pharmacokinetics of the developing immune and respiratory systems as well as changes in target organ sensitivities to toxicants. Differential windows of vulnerability during development are identified in the context of available animal models. We provide specific approaches to directly investigate differential windows of vulnerability. These approaches are based on fundamental developmental biology and the existence of discrete developmental processes within the immune and respiratory systems. The processes are likely to influence differential developmental susceptibility to toxicants, resulting in lifelong toxicological changes. We also provide a template for comparative research. Finally, we discuss the application of these data to risk assessment.