Biomedical subjects

Vincent Castranova

Publications and source records attributed to Vincent Castranova.

At least 37 records · Page 2Linked to original sources

PubMed2004

Signaling pathways controlling the production of inflammatory mediators in response to crystalline silica exposure: role of reactive oxygen/nitrogen species.

Occupational exposure to crystalline silica has been linked to pulmonary fibrosis and lung cancer. Surface properties of crystalline silica are critical to the production of oxidant species, chemokines, inflammatory cytokines, and proliferative factors involved in the initiation and progression of silica-induced damage, inflammation, alveolar type II cell hyperplasia, fibroblast activation, and disease. The transcription factors nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1) have been shown to play key roles in gene promotion for inflammatory mediators, oncogenes, and growth factors. This review summarizes evidence that in vitro and in vivo exposure to crystalline silica results in activation of NF-kappaB and AP-1. Signaling pathways for activation of these transcription factors are described. In addition, the role of silica-induced reactive oxygen species and nitric oxide in the activation of these signaling events is presented. Last, the generalizability of mechanisms regulating silica-induced pulmonary responses to pulmonary reactions to other occupational particles is discussed.

Animals↗

PubMed2004

Roles of reactive oxygen species and heme oxygenase-1 in modulation of alveolar macrophage-mediated pulmonary immune responses to Listeria monocytogenes by diesel exhaust particles.

Diesel exhaust particles (DEP) have been shown to suppress alveolar macrophage (AM)-mediated pulmonary immune responses to Listeria monocytogenes in vivo. In this study, effects of DEP-derived reactive oxygen species (ROS) and heme oxygenase (HO)-1 on AM-mediated immune responses to L. monocytogenes were investigated. Brown Norway rats were intratracheally inoculated with 100,000 L. monocytogenes, and AM were isolated at 7 days post-infection. Exposure to DEP or their organic extract (eDEP), but not the washed DEP (wDEP) or carbon black, increased intracellular ROS and HO-1 expression in AM. Induction of ROS and HO-1 by eDEP was partially reversed by alpha-naphthoflavone, a cytochrome P450 1A1 inhibitor, and totally blocked by N-acetylcysteine. In addition, exposure to eDEP, but not wDEP, inhibited lipopolysacchride-stimulated secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-12 (IL-12), but augmented production of IL-10 by AM. Kinetic studies showed that modulation of cytokines by eDEP was preceded by ROS and HO-1 induction. Furthermore, pretreatment of AM with superoxide dismutase (SOD) or zinc protoporphrin IX (Znpp), which attenuated eDEP-induced HO-1 expression/activity, substantially inhibited eDEP effect on IL-10. Finally, direct stimulation with pyrogallol (PYR), a superoxide donor, upregulated HO-1 and IL-10 but decreased secretion of IL-12 in L. monocytogenes-infected AM. These results show that DEP, through eDEP-mediated ROS, induce HO-1 expression and IL-10 production and at the same time inhibit AM production of TNF-alpha and IL-12 to dampen the host immune responses. The results also suggest that HO-1 may play an important role in regulating production of IL-10 by DEP-exposed and L. monocytogenes-infected AM.

Acetylcysteine↗

PubMed2004

Role of inducible nitric oxide synthase-derived nitric oxide in silica-induced pulmonary inflammation and fibrosis.

Inhalation of crystalline silica can produce lung inflammation and fibrosis. Inducible nitric oxide synthase (iNOS)-derived nitric oxide (NO) is believed to be involved in silica-induced lung disease. To investigate the role of iNOS-derived NO in this disease, the responses of iNOS knockout (KO) versus C57Bl/6J wild-type (WT) mice to silica were compared. Male mice (8-10 wk old, mean body weight 24.0 g) were anesthetized and exposed, by aspiration, to silica (40 mg/kg) or saline. At 24 h and 42 d postexposure, lungs were lavaged with saline. The first bronchoalveolar lavage (BAL) fluid supernatant was analyzed for lactate dehydrogenase (LDH) activity, levels of albumin, tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2), as well as total antioxidant capacity (TAC). The cellular fraction of the total BAL was used to determine alveolar macrophage (AM) and polymorphonuclear leukocyte (PMN) counts, and zymosanstimulated AM chemiluminescence (AM-CL). In separate mice, lung histopathological changes were evaluated 42 d postexposure. Acute (24-h) silica exposure decreased AMs, increased PMNs, increased LDH activity and levels of albumin, TNF-alpha, and MIP-2 in BAL fluid, and enhanced AM-CL in both iNOS KO and WT mice. However, iNOS KO mice exhibited less AM activation (defined as increased AM-CL and decreased AM yield) than WT. Furthermore, TAC following acute silica decreased in WT but was maintained in iNOS KO mice. Pulmonary reactions to subchronic (42 d) silica exposure were similar to acute. However, histopathological and BAL fluid indices of lung damage and inflammation, AM activation, and lung hydroxyproline levels were significantly less in iNOS KO compared to WT mice. These results suggest that iNOS-derived NO contributes to the pathogenesis of silica-induced lung disease in this mouse model.

Animals↗

PubMed2004

Respirable coal dust particles modify cytochrome P4501A1 (CYP1A1) expression in rat alveolar cells.

Cytochrome P4501A1 (CYP1A1) metabolizes polycyclic aromatic hydrocarbons in cigarette smoke to DNA-binding reactive intermediates associated with carcinogenesis. Epidemiologic studies indicate that the majority of coal miners are smokers but have a lower risk of lung cancer than other smokers. We hypothesized that coal dust (CD) exposure modifies pulmonary carcinogenesis by altering CYP1A1 induction. Therefore, male Sprague Dawley rats were intratracheally instilled with 2.5, 10, 20, or 40 mg CD/rat or vehicle (saline); and 11 d later, pulmonary CYP1A1 was induced by intraperitoneal injection of beta-naphthoflavone (BNF; 50 mg/kg). Fourteen days after CD exposure, CYP1A1 protein and activity were measured by Western blot and 7-ethoxyresorufin-O-deethylase activity, respectively. CYP1A1 and the alveolar type II markers, cytokeratins 8/18, were localized and quantified in lung sections by dual immunofluorescence with morphometry. The area of CYP1A1 expression in alveolar septa and alveolar type II cells in response to BNF was reduced by exposure to 20 or 40 mg CD compared with BNF alone. CD exposure significantly inhibited BNF-induced 7-ethoxyresorufin-O-deethylase activity in a dose-responsive manner. By Western blot, induction of CYP1A1 protein by BNF was significantly reduced by 40 mg CD compared with BNF alone. These findings indicate that CD decreases BNF-induced CYP1A1 protein expression and activity in the lung.

Animals↗

PubMed2004

Progression of lung inflammation and damage in rats after cessation of silica inhalation.

Human epidemiologic studies have found that silicosis may develop or progress even after occupational exposure has ended, suggesting that there is a threshold lung burden above which silica-induced pulmonary disease progresses without further exposure. We previously described the time course of rat pulmonary responses to silica inhalation as biphasic, the initial phase characterized by increased but controlled pulmonary inflammation and damage. However, after a threshold lung burden was exceeded, rapid progression of silica-induced pulmonary disease occurred. To test the hypothesis that there is a threshold lung burden above which silica-induced pulmonary disease progresses without further exposure we initiated a study to investigate the relationship between silica exposure, the initiation and progression of silica-induced pulmonary disease, and recovery. Rats were exposed to silica (15 mg/m(3), 6 h/day) for either 20, 40, or 60 days. A portion of the rats from each exposure were maintained without further exposure for 36 days to examine recovery. The major findings of this study are: (1) silica-exposed rats were not in pulmonary overload, and lung silica burden decreased with recovery; (2) pulmonary inflammation, damage and lipidosis increased with recovery for rats exposed to silica for 40 and 60 days, but not 20 days; (3) histopathology revealed changes in silica-induced alveolitis, epithelial hypertrophy and hyperplasia, and alveolar lipoproteinosis consistent with bronchoalveolar lavage (BAL) endpoints; and (4) pulmonary fibrosis developed even when exposure was stopped prior to its initial development.

Animals↗

PubMed2004

Role of inducible nitric oxide synthase-derived nitric oxide in lipopolysaccharide plus interferon-gamma-induced pulmonary inflammation.

Exposure of mice to lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma) increases nitric oxide (NO) production, which is proposed to play a role in the resulting pulmonary damage and inflammation. To determine the role of inducible nitric oxide synthase (iNOS)-induced NO in this lung reaction, the responses of inducible nitric oxide synthase knockout (iNOS KO) versus C57BL/6J wild-type (WT) mice to aspirated LPS + IFN-gamma were compared. Male mice (8-10 weeks) were exposed to LPS (1.2 mg/kg) + IFN-gamma (5000 U/mouse) or saline. At 24 or 72 h postexposure, lungs were lavaged with saline and the acellular fluid from the first bronchoalveolar lavage (BAL) was analyzed for total antioxidant capacity (TAC), lactate dehydrogenase (LDH) activity, albumin, tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2). The cellular fraction of the total BAL was used to determine alveolar macrophage (AM) and polymorphonuclear leukocyte (PMN) counts, and AM zymosan-stimulated chemiluminescence (AM-CL). Pulmonary responses 24 h postexposure to LPS + IFN-gamma were characterized by significantly decreased TAC, increased BAL AMs and PMNs, LDH, albumin, TNF-alpha, and MIP-2, and enhanced AM-CL to the same extent in both WT and iNOS KO mice. Responses 72 h postexposure were similar; however, significant differences were found between WT and iNOS KO mice. iNOS KO mice demonstrated a greater decline in total antioxidant capacity, greater BAL PMNs, LDH, albumin, TNF-alpha, and MIP-2, and an enhanced AM-CL compared to the WT. These data suggest that the role of iNOS-derived NO in the pulmonary response to LPS + IFN-gamma is anti-inflammatory, and this becomes evident over time.

Albumins↗

PubMed2004

Effect of diesel exhaust particulate (DEP) on immune responses: contributions of particulate versus organic soluble components.

The effect of diesel exhaust particulate (DEP) exposure on innate, cellular and humoral pulmonary immunity was studied using high-dose, acute-exposure rat, mouse, and cell culture models. DEP consists of a complex mixture of petrochemical-derived organics adsorbed onto elemental carbon particles. DEP is a major component of particulate urban air pollution and a health concern in both urban and occupational environments. The alveolar macrophage is considered a key cellular component in pulmonary innate immunity. DEP and DEP organic extracts have been found to suppress alveolar macrophage function as demonstrated by reduced production of cytokines (interleukin-1 [IL-1], tumor necrosis factor- alpha [TNF- alpha]) and reactive oxygen species (ROS) in response to a variety of agents, including lipopolysaccharide (LPS), interferon- gamma (IFN- gamma), and bacteria. Fractionation of DEP organic extract suggests that this activity was predominately in polyaromatic-containing and more polar (resin) fractions. Organic-stripped DEP did not alter these innate pulmonary immune responses. DEP also depressed pulmonary clearance of Listeria monocytogenes and Bacillus Calmette-Guerin (BCG). The contribution of the organic component of DEP is less well defined with respect to acquired and humoral immunity. Indeed, both DEP and carbon black enhanced humoral immune responses (specific immunoglobulin [Ig] E and IgG) in an ovalbumin-sensitized rat model. It is concluded that both the particulate and adsorbed organics may contribute to DEP-mediated immune alterations.

Acute Disease↗

PubMed2004

Soluble metals associated with residual oil fly ash increase morbidity and lung injury after bacterial infection in rats.

Inhalation of residual oil fly ash (ROFA) has been shown to impair lung defense mechanisms in laboratory animals and susceptible populations. Bioavailability of soluble transition metals has been shown to play a key role in lung injury caused by ROFA exposure. The goal of this study was to evaluate the effect of soluble metals on lung defense and injury in animals preexposed to ROFA followed by pulmonary challenge with a bacterial pathogen. ROFA was suspended in saline (ROFA-TOTAL), incubated overnight at 37 degrees C, and separated by centrifugation into soluble (ROFA-SOL) and insoluble (ROFA-INSOL) fractions. A portion of the soluble sample was treated with the metal-binding resin Chelex for 24 h at 37 degrees C. Sprague-Dawley rats were intratracheally dosed at d 0 with ROFA-TOTAL (1.0 mg/100 g body weight), ROFA-INSOL, ROFA-SOL, saline, saline + Chelex, or ROFA-SOL + Chelex. At d 3, 5 x 10(5) Listeria monocytogenes were intratracheally instilled into rats from each treatment group. At d 6, 8, and 10, left lungs were removed, homogenized, and cultured to assess bacterial clearance. Histopathological analysis was performed on the right lungs. Pulmonary exposure of ROFA-TOTAL or ROFA-SOL before infection led to a marked increase in lung injury and inflammation at all three time points after inoculation, and an increase in morbidity in comparison to saline control rats. Treatment with ROFA-INSOL, saline + Chelex, or ROFA-SOL + Chelex caused no significant increases in lung damage and morbidity when compared to control. By d 10, the ROFA-SOL and ROFA-TOTAL groups had approximately 200-fold more bacteria in the lung than saline control, indicating the inability of these groups to effectively respond to the infection. None of the other treatment groups had significant impairments in bacterial clearance when compared to saline. In conclusion, exposure to ROFA-TOTAL and ROFA-SOL significantly suppressed the lung response to infection. These results suggest that soluble metals present in ROFA may play a key role in increased susceptibility to pulmonary infection in exposed populations.

Air Pollutants↗

PubMed2004

Exposure to carbon nanotube material: aerosol release during the handling of unrefined single-walled carbon nanotube material.

Carbon nanotubes represent a relatively recently discovered allotrope of carbon that exhibits unique properties. While commercial interest in the material is leading to the development of mass production and handling facilities, little is known of the risk associated with exposure. In a two-part study, preliminary investigations have been carried out into the potential exposure routes and toxicity of single-walled carbon nanotube material (SWCNT)--a specific form of the allotrope. The material is characterized by bundles of fibrous carbon molecules that may be a few nanometers in diameter, but micrometers in length. The two production processes investigated use-transition metal catalysts, leading to the inclusion of nanometer-scale metallic particles within unrefined SWCNT material. A laboratory-based study was undertaken to evaluate the physical nature of the aerosol formed from SWCNT during mechanical agitation. This was complemented by a field study in which airborne and dermal exposure to SWCNT was investigated while handling unrefined material. Although laboratory studies indicated that with sufficient agitation, unrefined SWCNT material can release fine particles into the air, concentrations generated while handling material in the field were very low. Estimates of the airborne concentration of nanotube material generated during handling suggest that concentrations were lower than 53 microg/m(3) in all cases. Glove deposits of SWCNT during handling were estimated at between 0.2 mg and 6 mg per hand.

Aerosols↗

PubMed2004

Activation of aPKC is required for vanadate-induced phosphorylation of protein kinase B (Akt), but not p70S6k in mouse epidermal JB6 cells.

Vanadium is a metal widely distributed in the environment. Although vanadate-containing compounds exert potent toxic effects on a wide variety of biological systems, the mechanisms by which vanadate mediates adverse effects are not well understood. The present study investigated the vanadate-induced phosphorylation of Akt and p70S6K, two kinases known to be vital for cell survival, growth, transformation, and transition of the cell cycle in mammals. Exposure of mouse epidermal JB6 cells to vanadium led to phosphorylation of Akt and p70S6K in a time- and dose-dependent manner. Vanadium exposure also caused translocation of atypical isoforms of PKC (lambda, zeta) from the cytosol to the membrane, but had no effect on PKCalpha translocation, suggesting that the atypical PKCs (aPKC) were specifically involved in vanadium-induced cellular response. Importantly, overexpression of a dominant negative mutant PKClambda blocked Akt phosphorylation at Ser473 and Thr308, whereas it did not inhibit p70S6k phosphorylation at Thr389 and Thr421/Ser424, suggesting that aPKC activation is specifically involved in vanadium-induced activation of Akt, but not in activation of p70S6k. Furthermore, vanadium-induced p70S6k phosphorylation at Thr389 and Thr421/Ser424 and Akt phosphorylation at Thr308 occurred through a PI-3K-dependent pathway because a PI-3K dominant negative mutant inhibited induction as compared with vector control cells. These results indicate that there was a differential role of aPKC in vanadate-induced phosphorylation of Akt and p70S6k, suggesting that signal transduction pathways leading to the activation of Akt and p70S6k were different.

Animals↗

PubMed2004

Role of nitric oxide in pathological responses of the lung to exposure to environmental/occupational agents.

Conflicting evidence exists as to whether nitric oxide expresses damaging/inflammatory or antioxidant/anti-inflammatory properties. Data presented in this review indicate that in vitro or in vivo exposure to selected environmental or occupational agents, such as asbestos, silica, ozone or lipopolysaccharide, can result in up-regulation of inducible nitric oxide synthase by alveolar macrophages and pulmonary epithelial cells. In the case of silica exposure, evidence consistently supports a damaging/inflammatory role of nitric oxide and/or peroxynitrite in the pathogenesis of lung disease. Although conflicting data have been reported, the majority of published studies suggest that nitric oxide plays a damaging role in pulmonary injury resulting from exposure to ozone or asbestos. In contrast, most information supports an anti-inflammatory role of nitric oxide following exposure to lipopolysaccharide. Further investigation is required to elucidate fully the mechanisms involved in determining the role of nitric oxide in the initiation and progression of various pulmonary diseases.

Animals↗

PubMed2004

Particulate matter exposure impairs systemic microvascular endothelium-dependent dilation.

Acute exposure to airborne pollutants, such as solid particulate matter (PM), increases the risk of cardiovascular dysfunction, but the mechanisms by which PM evokes systemic effects remain to be identified. The purpose of this study was to determine if pulmonary exposure to a PM surrogate, such as residual oil fly ash (ROFA), affects endothelium-dependent dilation in the systemic microcirculation. Rats were intratracheally instilled with ROFA at 0.1, 0.25, 1 or 2 mg/rat 24 hr before experimental measurements. Rats intratracheally instilled with saline or titanium dioxide (0.25 mg/rat) served as vehicle or particle control groups, respectively. In vivo microscopy of the spinotrapezius muscle was used to study systemic arteriolar dilator responses to the Ca2+ ionophore A23187, administered by ejection via pressurized micropipette into the arteriolar lumen. We used analysis of bronchoalveolar lavage (BAL) samples to monitor identified pulmonary inflammation and damage. To determine if ROFA exposure affected arteriolar nitric oxide sensitivity, sodium nitroprusside was iontophoretically applied to arterioles of rats exposed to ROFA. In saline-treated rats, A23187 dilated arterioles up to 72 +/- 7% of maximum. In ROFA- and TiO2-exposed rats, A23187-induced dilation was significantly attenuated. BAL fluid analysis revealed measurable pulmonary inflammation and damage after exposure to 1 and 2 mg ROFA (but not TiO2 or < 1 mg ROFA), as evidenced by significantly higher polymorphonuclear leukocyte cell counts, enhanced BAL albumin levels, and increased lactate dehydrogenase activity in BAL fluid. The sensitivity of arteriolar smooth muscle to NO was similar in saline-treated and ROFA-exposed rats, suggesting that pulmonary exposure to ROFA affected endothelial rather than smooth muscle function. A significant increase in venular leukocyte adhesion and rolling was observed in ROFA-exposed rats, suggesting local inflammation at the systemic microvascular level. These results indicate that pulmonary PM exposure impairs systemic endothelium-dependent arteriolar dilation. Moreover, because rats exposed to < 1 mg ROFA or TiO2 did not exhibit BAL signs of pulmonary damage or inflammation, it appears that PM exposure can impair systemic microvascular function independently of detectable pulmonary inflammation.

Air Pollutants↗

PubMed2003

Exposure to carbon nanotube material: assessment of nanotube cytotoxicity using human keratinocyte cells.

Carbon nanotubes are new members of carbon allotropes similar to fullerenes and graphite. Because of their unique electrical, mechanical, and thermal properties, carbon nanotubes are important for novel applications in the electronics, aerospace, and computer industries. Exposure to graphite and carbon materials has been associated with increased incidence of skin diseases, such as carbon fiber dermatitis, hyperkeratosis, and naevi. We investigated adverse effects of single-wall carbon nanotubes (SWCNT) using a cell culture of immortalized human epidermal keratinocytes (HaCaT). After 18 h of exposure of HaCaT to SWCNT, oxidative stress and cellular toxicity were indicated by formation of free radicals, accumulation of peroxidative products, antioxidant depletion, and loss of cell viability. Exposure to SWCNT also resulted in ultrastructural and morphological changes in cultured skin cells. These data indicate that dermal exposure to unrefined SWCNT may lead to dermal toxicity due to accelerated oxidative stress in the skin of exposed workers.

Cells, Cultured↗

PubMed2003

Asphalt exposure enhances neuropeptide levels in sensory neurons projecting to the rat nasal epithelium.

Asphalt fumes have been reported to produce nasal irritation in road workers. Since inhaled irritants can increase substance P (SP) production in airway neurons, the effects of asphalt fumes on SP production in trigeminal ganglia (TG) sensory neurons innervating the nasal mucosa were investigated. The effects of asphalt fumes on nasal mucosal innervation were examined by measuring SP and calcitonin-gene-related peptide (CGRP) levels in rat TG neurons projecting to the nasal epithelium. Female Sprague-Dawley rats were exposed to asphalt fumes at 16.0 +/- 8.1mg /m3 for 5 consecutive days, 3.5 h/d. Inflammatory cells were measured in nasal cavity lavage fluid. SP and CGRP immunoreactivity (IR) was measured in the cell bodies of trigeminal ganglion sensory neurons projecting to the nasal cavity. A significant increase in neutrophils and macrophages was observed after asphalt fume exposure indicating an inflammatory response in the nasal cavity. The percentage of SP-IR neurons increased significantly in the asphalt-exposed rats, and the proportion of CGRP-IR neurons was also elevated following asphalt exposure. These results indicate that exposure to asphalt fumes produces inflammation and increases the levels of SP and CGRP in TG neurons projecting to the nasal epithelium. The findings are consistent with asphalt-induced activation of sensory C-fibers in the nasal cavity. Enhanced sensory neuropeptide release from nerve terminals in the nasal cavity may produce neurogenic inflammation associated with nasal irritation following exposure to asphalt fumes.

Animals↗

PubMed2003

Response of alveolar macrophages from inducible nitric oxide synthase knockout or wild-type mice to an in vitro lipopolysaccharide or silica exposure.

The role of nitric oxide (NO) in pulmonary disease has been controversial with both antiinflammatory (scavenging radicals and inhibiting NF-êB activation) and proinflammatory (forming highly reactive peroxynitrite and augmenting NF-êB activation by inflammatory agents) actions reported. Therefore, a study has been initiated to determine whether deletion of the inducible nitric oxide synthase (iNOS) gene in the C57BL/6J mouse alters the pulmonary macrophage response to lipopolysaccharide (LPS) or silica. The objective of the initial phase of this study was to determine the difference in responsiveness of alveolar macrophages (AMs), harvested from naive wild-type (WT) or iNOS knockout (iNOS KO) mice, to an in vitro LPS or silica exposure. Primary AMs were obtained by bronchoalveolar lavage (BAL) from age- and weight-matched iNOS KO and WT mice. The cells were treated with interferon-gamma (IFN-ã) (50 U/ml), IFN-ã (50 U/ml) + LPS (1 microg/ml), LPS (0.01-100 microg/ml), or silica (25-250 microg/ml). The following parameters were measured: nitrate and nitrite (NOx), tumor necrosis factor-á (TNF-á), macrophage inflammatory protein-2 (MIP-2), intracellular generation of the reactive oxygen species (ROS) hydrogen peroxide (H(2)O(2) and superoxide (O(*-2)), and basal (unstimulated) total antioxidant capacity. Data show a significant increase in NOx production upon exposure to IFN-ã +/- LPS in the WT but not iNOS KO AMs. NOx production by iNOS KO or WT AMs was not altered by in vitro exposure to LPS or silica alone. LPS, but not silica, induced TNF-á and MIP-2 production in both iNOS KO and WT AMs. Statistical analysis of concentration response curves found a significant tendency for greater mediator production in the iNOS KO versus WT AMs. Basal intracellular production of H(2)O(2) and O(*- 2) was significantly greater in the iNOS KO compared to WT AMs. In contrast, LPS- (10 microg/ml) or silica- (100 microg/ml) stimulated intracellular oxidant production was lower in iNOS KO AMs, but overall (basal + stimulated) inflammatory capacity was similar between the cell types. The basal total antioxidant production of the iNOS KO AMs was approximately twofold higher than the WT AMs. In conclusion, certain compensatory changes appear to occur in AMs from iNOS KO mice. In response to the inability to induce NO production, iNOS KO AMs exhibit significantly higher basal generation of H(2)O(2) and (O(*- 2)) as well as higher total antioxidant levels. In addition, LPS induced TNF-á and MIP-2 production tend to be higher in AMs from iNOS KO mice. Such compensatory changes in the AM response may affect the response of iNOS KO mice to inflammatory exposures.

Animals↗

PubMed2003

Partially opened triple helix is the biologically active conformation of 1-->3-beta-glucans that induces pulmonary inflammation in rats.

1-->3-beta-Glucans produce pulmonary inflammation in rats and are commonly found in indoor air dust samples. Conformation is an important factor determining the biological activity of 1-->3-beta-glucans. The partially opened triple-helix conformation induced by NaOH treatment and the annealed triple-helix conformation have been identified by fluorescence resonance energy transfer spectroscopy in our previous study. The objective of this study was to examine the role of these conformations of 1-->3-beta-glucans in the induction of pulmonary inflammation in rats. A partially opened triple-helix conformation of the known inflammatory 1-->3-beta-glucan zymosan was prepared by treating zymosan with NaOH followed by neutralization and dialysis. The annealed triple-helix conformation was prepared by allowing the partially opened triple-helix conformation to anneal for 9 d at room temperature. Rats were exposed to fresh or annealed NaOH-treated zymosan via intratracheal instillation. The results show that the zymosan-induced pulmonary inflammatory responses were significantly reduced after the 9-d annealing period, which suggests that this inflammatory response was dependent on the conformation of zymosan. Freezing NaOH-treated zymosan (for 7 d) inhibited the annealing process. Exposure of rats to thawed preparations of zymosan resulted in the same inflammatory responses as the freshly prepared partially opened triple-helix zymosan. In contrast, the potency of untreated zymosan did not change significantly following a 7-d annealing period, indicating that annealing occurs only after the conformation has been modified by NaOH treatment. This study indicates that the partially opened triple helix of 1-->3-beta-glucans is more active than the closed conformation in inducing pulmonary inflammation in rats.

Animals↗

PubMed2003

Exposure to particulate 1-->3-beta-glucans induces greater pulmonary toxicity than soluble 1-->3-beta-glucans in rats.

1-->3-beta-Glucans, derived from the inner cell wall of yeasts and fungi, are commonly found in indoor air dust samples and have been implicated in organic dust toxic syndrome. In a previous study, it was reported that 1-->3-beta-glucan (zymosan A) induced acute pulmonary inflammation in rats. This study investigates which form of 1-->3-beta-glucans, particulate or soluble, is more potent in inducing pulmonary inflammation. Zymosan A was suspended in 0.25 N NaOH for 30 min, neutralized, dialyzed for 2 d using deionized water, and particulate and soluble fractions were collected. Male Sprague-Dawley rats were exposed via intratracheal instillation to NaOH-soluble or NaOH-insoluble zymosan A. At 18 h postexposure, various indicators of pulmonary response were monitored, including indicators of lung damage, such as serum albumin concentration and lactate dehydrogenase (LDH) activity in acellular bronchoalveolar lavage fluid. Inflammation was characterized by an increase in lavageable polymorphonuclear leukocytes (PMN). Pulmonary irritation (breathing frequency increase) and oxidant production (nitric oxide and chemiluminescence, CL) were also monitored. Exposure to the particulate form of NaOH-treated zymosan produced a significant increase in all these indicators. In contrast, rats exposed to the NaOH-soluble fraction were not markedly affected except for LDH, PMN, and CL. However, these increases were significantly less than with exposure to NaOH-insoluble zymosan. Therefore, results demonstrate that particulate zymosan A is more potent in inducing pulmonary inflammation and damage in rats than the soluble form of this beta-glucan.

Analysis of Variance↗

PubMed2003

Potential role of apoptotic macrophages in pulmonary inflammation and fibrosis.

Induction of apoptosis has been associated with a variety of exposures which result in inflammatory and fibrotic lung disorders. Macrophages are key regulatory cells in the lung; however, the role of apoptotic macrophages in those pulmonary disorders is not well characterized. In the present investigation, apoptotic macrophages were instilled into the lungs of rats to study directly the pulmonary responses to apoptotic cells. The effects of apoptotic macrophages on lung inflammation and fibrosis, as well as associated protein expression of TNF-alpha, TGF-beta, and matrix metalloproteinases (MMPs) were examined. Induction of macrophage apoptosis was carried out in vitro using a variety of known apoptosis inducers. Intratracheal administration of apoptotic macrophages (5 x 10(6) cells/rat) into the lung of rats caused an increase in pulmonary infiltration of macrophages and lung cell apoptosis 4 weeks after the treatment as indicated by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. In contrast, pulmonary instillation of saline or normal control macrophages had no effect. Histological analysis of lung sections showed collagen deposition and fibrotic lesions after apoptotic cell treatment but not in control groups. Immunohistochemical studies revealed increased expression of TNF-alpha, TGF-beta, MMP2, and MMP9 in the treatment group 4 weeks after the treatment. These results suggest a role for macrophage apoptosis in the initiation of these lung disorders. This study provides direct evidence that apoptotic macrophages can induce lung inflammation and fibrosis and that this induction may be associated with increased expression of TNF-alpha, TGF-beta, MMP2, and MMP9. Published 2002 Wiley-Liss, Inc.

Animals↗