Janice L. Peake

Alteration of Pulmonary Neuroendocrine Cells during Epithelial Repair of Naphthalene-Induced Airway Injury

Whole-mount airway preparations isolated from the lungs of mice treated by intraperitoneal injection of naphthalene and allowed to recover for 5 days were examined for the distribution and abundance of solitary pulmonary neuroendocrine cells (PNECs) and neuroepithelial bodies (NEBs) along the main axial pathway of the right middle lobe. Sham mice treated with corn oil vehicle were examined in a similar manner. An antibody to calcitonin gene-related peptide, a neuroendocrine cell marker, was used to identify the location, size, and number of PNECs and NEBs in the airways. After naphthalene treatment and epithelial repair, NEBs were significantly increased along the walls of the airways as well as on branch point ridges. The surface area covered by NEBs composed of 20 or fewer PNECs was significantly enlarged after naphthalene treatment compared with control NEBs of an equivalent cell number. The PNEC number per square millimeter was also increased more than threefold above control values after naphthalene treatment. These findings provide further support for a key role of neuroendocrine cells in the reparative process of airway epithelial cell renewal after injury.

Deltamethrin-induced thymus atrophy in male Balb/c mice

The action of deltamethrin, a potent type II synthetic pyrethroid insecticide, on the thymus of the Balb/c mouse was studied in vivo and in vitro. We found that deltamethrin produced atrophy in the thymus in a dose- and time-dependent fashion. The lowest effective dose was found to be 6 mg/kg, 24 hr after a single intraperitoneal treatment. Treated animals did not recover during the time-course of the experiment (365 days after treatment); however, deltamethrin did not affect the body weight of the treated animals during the course of the study. To determine if deltamethrin-induced [Ca2+]i signaling could lead to thymic atrophy via programmed cell death, mice were treated with 25 mg deltamethrin/kg for 24 hr or the isolated thymocyte suspension was treated with 50 microM deltamethrin. A significant stimulation of inositol 1,4,5-triphosphate (IP3) and inositol 1,4-diphosphate (IP2) production was found after 24 hr of deltamethrin-1R (active isomer) treatment. An inactive stereoisomer of deltamethrin (i.e. 1S) did not cause a significant rise in the production of 1P3 and 1P2. In addition, deltamethrin-1R induced a transient increase of [Ca2+]i mobilization in the thymocyte suspension after 10 min of in vitro treatment, and substantially reduced the rate of calcium-calmodulin (Ca/CaM)-dependent protein dephosphorylation in in vivo treated animals (25 mg deltamethrin/kg for 24 hr). The in vivo effects of deltamethrin treatment demonstrated induction of DNA fragmentation and cell death in thymocytes. Moreover, using a histochemical approach, it was evident that deltamethrin at 25 mg/kg was able to produce cell death in the thymus of treated animals 72 hr after treatment. In the present work, we found that cell death was apoptotic in nature as noted first by the inhibition of deltamethrin-induced cell death by aurintricarboxylic acid, an inhibitor of apoptosis, and second, by internucleosomal DNA fragmentation, a hallmark of apoptosis, produced by deltamethrin in treated animals as well in thymocyte suspensions. In addition, the involvement of the Ca/CaM-dependent protein phosphorylation-dephosphorylation cascade in the induction of apoptosis by deltamethrin was supported by the protective role of the calmodulin inhibitor trifluoperazine against the apoptotic effect of deltamethrin on thymocyte suspension. Our results suggest that deltamethrin induced thymus atrophy and altered the Ca/CaM-dependent protein kinase-phosphatase cascade, which might induce programmed cell death.

Perinatal environmental tobacco smoke exposure alters the immune response and airway innervation in infant primates

BACKGROUND Epidemiologic studies associate environmental tobacco smoke (ETS) exposure with childhood asthma. OBJECTIVE To investigate whether specific pathophysiological alterations that contribute to asthma development in human beings can be induced in infant monkeys after perinatal ETS exposure. METHODS Rhesus macaque fetuses/infants were exposed to ETS at 1 mg/m(3) of total suspended particulate matter from 50 days gestational age to 2.5 months postnatal age. Inflammatory and neural responses to ETS exposure were measured in the infant monkeys. RESULTS Perinatal ETS exposure could induce systemic and local responses, which include significant elevation of plasma levels of C5a and brain-derived neurotrophic factor, as well as significant increases in pulmonary expression of proinflammatory cytokine TNF-alpha and T(H)2 cytokine IL-5, chemokine monocyte chemoattractant protein 1, and the density of substance P-positive nerves along the bronchial epithelium. Perinatal ETS exposure also significantly increased the numbers of mast cells, eosinophils, monocytes, and lymphocytes in the lungs of infant monkeys. In addition, ex vivo measurements showed significantly increased levels of IL-4 and brain-derived neurotrophic factor in the culture supernatant of PBMCs. Interestingly, as an important component of cigarette smoke, LPS was detected in the plasma of infant monkeys subjected to perinatal exposure to ETS. In contrast, an inhibitory effect of perinatal ETS exposure was also observed, which is associated with decreased phagocytic activity of alveolar macrophages and a significantly decreased level of nerve growth factor in the bronchoalveolar lavage fluid. CONCLUSION Perinatal ETS exposure can induce a T(H)2-biased inflammatory response and alter airway innervation in infant monkeys.

Reduced Lung Cell Proliferation Following Short-Term Exposure to Ultrafine Soot and Iron Particles in Neonatal Rats: Key to Impaired Lung Growth?

Particulate matter (PM) has been associated with a variety of negative health outcomes in children involving the respiratory system and early development. However, the precise mechanisms to explain how exposure to airborne particles may cause adverse effects in children are unknown. To study their influence on early postnatal development, a simple, laminar diffusion flame was used to generate an aerosol of soot and iron particles in the size range of 10 to 50 nm. Exposure of 10-day-old rat pups to soot and iron particles was for 6 h/day for 3 days. The lungs were examined following a single injection of bromodeoxyuridine (BrdU) 2 h prior to necropsy. Neonatal rats exposed to these particles demonstrated no effect on the rate of cell proliferation within terminal bronchioles or the general lung parenchyma. In contrast, within those regions arising immediately beyond the terminal bronchioles (defined as the proximal alveolar region), the rate of cell proliferation was significantly reduced compared with filtered air controls. These findings strongly suggest exposure to airborne particles during early neonatal life has significant direct effects on lung growth by altering cell division within critical sites of the respiratory tract during periods of rapid postnatal development. Such effects may result in altered growth in the respiratory system that may be associated with lifelong consequences.

Altered in vivo toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in C-SRC deficient mice

Administration of a single i.p. dose of 115 microg/kg of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to homozygous and heterozygous c-src deficient mice (i.e. c-src -/- and -/+ mice) and their wild-type littermates (c-src +/+ mice) induced differential toxic responses. In c-src +/+ mice, there were clear-cut signs of the toxicity of TCDD, such as the loss of weight in the body, thymus and adipose tissue, whereas in c-src -/+ mice these effects were modest and were not statistically significant. Yet, hepatomegaly, a characteristic effect of TCDD, took place in all three strains of mice. Histological examination of liver samples from control mice and from mice treated with TCDD for 10 days showed that there are qualitative differences in the expression of the effects of TCDD between control and treated mice as well as between c-src -/+ and +/+ mice. In the case of c-src +/+ mice, the predominant lesions were lipid accumulation, glycogen depletion, edema formation and necrosis, as shown by the presence of large areas of ballooning degeneration, and cellular influx of fluid. These changes were demonstrated only marginally in c-src -/+ mice. The predominant effect in -/+ mice was edema formation. At a high dose of TCDD (345 microg/kg), all of the +/+ mice died within 34 days, whereas none of the c-src -/+ mice died. Together these results clearly indicate that some of the toxic effects of TCDD are not fully expressed in c-src deficient mice.

Gross and Subgross Anatomy of Lungs, Pleura, Connective Tissue Septa, Distal Airways, and Structural Units

Abstract In the lung, there is much anatomical diversity between species, which may affect how the animal responds to disease. To correlate animal studies to human disease, we need to understand what these differences are. These differences include the branching geometry of the airways, variations in breathing rate and depth, and the subgross architecture of the lungs. The purpose of this chapter is to examine the basic anatomical units of the lungs in a variety of mammalian species and discuss their functional significance.

QUANTITATIVE HISTOLOGY AND CYTOCHROME P-450 IMMUNOCYTOCHEMISTRY OF THE LUNG PARENCHYMA FOLLOWING 6 MONTHS OF EXPOSURE OF STRAIN A/J MICE TO CIGARETTE SIDESTREAM SMOKE

AbstractMale strain A/J mice were exposed for 6 h/day, 5 days/wk to aged and diluted cigarette sidestream smoke (ADSS) at a chamber concentration of 4 mg/m3 of total suspended particulate matter (TSP). After 6 mo, the lungs were examined for altered expression of cytochrome P-450 isozymes and for differences in total alveolar tissue volume or surface area, as well as changes in the numbers of epithelial type II cells and alveolar macrophages. Morphologic measurements showed no statistically significant differences for the air, alveolar tissue, or capillary volumes of the lungs or changes in the total number of epithelial type II cells or alveolar macrophages. In contrast, cytochrome P-4501A1 was elevated in the lungs of ADSS-exposed animals and localized in capillary endothelial cells. CYP2B1 was present in airway epithelial cells as well as in epithelial cells throughout the lung parenchyma, but its distribution was not changed by ADSS exposure. Isozyme CYP2E1 was also found in airway epithelial cells, b...

Aerosolized Silver Nanoparticles in the Rat Lung and Pulmonary Responses over Time

Silver nanoparticle (Ag NP) production methods are being developed and refined to produce more uniform Ag NPs through chemical reactions involving silver salt solutions, solvents, and capping agents to control particle formation. These chemical reactants are often present as contaminants and/or coatings on the Ag NPs, which could alter their interactions in vivo. To determine pulmonary effects of citrate-coated Ag NPs, Sprague-Dawley rats were exposed once nose-only to aerosolized Ag NPs (20 nm [C20] or 110 nm [C110] Ag NPs) for 6 hr. Bronchoalveolar lavage fluid (BALF) and lung tissues were obtained at 1, 7, 21, and 56 days postexposure for analyses. Inhalation of Ag NPs, versus citrate buffer control, produced significant inflammatory and cytotoxic responses that were measured in BALF cells and supernatant. At day 7, total cells, protein, and lactate dehydrogenase were significantly elevated in BALF, and peak histopathology was noted after C20 or C110 exposure versus control. At day 21, BALF polymorphonuclear cells and tissue inflammation were significantly greater after C20 versus C110 exposure. By day 56, inflammation was resolved in Ag NP–exposed animals. Overall, results suggest delayed, short-lived inflammatory and cytotoxic effects following C20 or C110 inhalation and potential for greater responses following C20 exposure.

Effect of Perinatal secondhand tobacco smoke exposure on in vivo and intrinsic airway structure/function in non-human primates

Infants exposed to second hand smoke (SHS) experience more problems with wheezing. This study was designed to determine if perinatal SHS exposure increases intrinsic and/or in vivo airway responsiveness to methacholine and whether potential structural/cellular alterations in the airway might explain the change in responsiveness. Pregnant rhesus monkeys were exposed to filtered air (FA) or SHS (1 mg/m(3) total suspended particulates) for 6 h/day, 5 days/week starting at 50 days gestational age. The mother/infant pairs continued the SHS exposures postnatally. At 3 months of age each infant: 1) had in vivo lung function measurements in response to inhaled methacholine, or 2) the right accessory lobe filled with agarose, precision-cut to 600 mum slices, and bathed in increasing concentrations of methacholine. The lumenal area of the central airway was determined using videomicrometry followed by fixation and histology with morphometry. In vivo tests showed that perinatal SHS increases baseline respiratory rate and decreases responsiveness to methacholine. Perinatal SHS did not alter intrinsic airway responsiveness in the bronchi. However in respiratory bronchioles, SHS exposure increased airway responsiveness at lower methacholine concentrations but decreased it at higher concentrations. Perinatal SHS did not change eosinophil profiles, epithelial volume, smooth muscle volume, or mucin volume. However it did increase the number of alveolar attachments in bronchi and respiratory bronchioles. In general, as mucin increased, airway responsiveness decreased. We conclude that perinatal SHS exposure alters in vivo and intrinsic airway responsiveness, and alveolar attachments.

Second-hand Smoke Increases Nitric Oxide and Alters the IgE Response in a Murine Model of Allergic Aspergillosis

This study was performed to determine the effects of environmental tobacco smoke (ETS) on nitric oxide (NO) and immunoglobulin (Ig) production in a murine model of allergic bronchopulmonary aspergillosis (ABPA). Adult BALB/c mice were exposed to aged and diluted sidestream cigarette smoke from day 0 through day 43 to simulate “second-hand smoke”. During exposure, mice were sensitized to soluble Aspergillus fumigatus (Af) antigen intranasally between day 14 and 24. All Af sensitized mice in ambient air (Af + AIR) made elevated levels of IgE, IgG1, IgM, IgG2a and IgA. Af sensitized mice housed in ETS (Af + ETS) made similar levels of immunoglobulins except for IgE that was significantly reduced in the serum and bronchoalveolar lavage (BAL). However, immunohistochemical evaluation of the lung revealed a marked accumulation of IgE positive cells in the lung parenchyma of these Af + ETS mice. LPS stimulation of BAL cells revealed elevated levels of NO in the Af + AIR group, which was further enhanced in the Af+ETS group. In vitro restimulation of the BAL cells on day 45 showed a TH0 response with elevated levels of IL3, 4, 5, 10 and IFN-γ. However, by day 28 the response shifted such that TH2 cytokines increased while IFN-γ decreased. The Af + ETS group showed markedly reduced levels in all cytokines tested, including the inflammatory cytokine IL6, when compared to the Af+AIR group. These results demonstrate that ETS affects ABPA by further enhancing the NO production and reduces the TH2 and the inflammatory cytokines while altering the pattern of IgE responses.