Biomedical subjects

Vincent Castranova

Publications and source records attributed to Vincent Castranova.

At least 55 records · Page 3Linked to original sources

PubMed2003

Vanadium-induced apoptosis and pulmonary inflammation in mice: Role of reactive oxygen species.

Pulmonary exposure to metals and metal-containing compounds is associated with pulmonary inflammation, cell death, and tissue injury. The present study uses a mouse model to investigate vanadium-induced apoptosis and lung inflammation, and the role of reactive oxygen species (ROS) in this process. Aspiration of the pentavalent form of vanadium, V (V), caused a rapid influx of polymorphonuclear leukocytes into the pulmonary airspace with a peak inflammatory response at 6 h post-exposure and resolution by 72 h. During this period, the number of apoptotic lung cells which were predominantly neutrophils increased considerably with a peak response at 24 h accompanied by no or minimum necrosis. After 24 h when the V (V)-induced inflammation was in the resolution phase, an increased influx of macrophages and engulfment of apoptotic bodies by these phagocytes was observed, supporting the role of macrophages in apoptotic cell clearance and resolution of V (V)-induced lung inflammation. Electron spin resonance (ESR) studies using lavaged alveolar macrophages showed the formation of ROS, including O(2)(*-), H(2)O(2), and (*)OH radicals which were confirmed by inhibition with free radical scavengers. The mechanism of ROS generation induced by V (V) involved the activation of an NADPH oxidase complex and the mitochondrial electron transport chain. The ROS scavenger, catalase (H(2)O(2) scavenger), effectively inhibited both lung cell apoptosis and the inflammatory response, whereas superoxide dismutase (SOD) (O(2)(*-) scavenger) and the metal chelator, deferoxamine (inhibitor of (*)OH generation by Fenton-like reactions) had lesser effects. These results indicate that multiple oxidative species are involved in V (V)-induced lung inflammation and apoptosis, and that H(2)O(2) plays a major role in this process.

Administration, Inhalation↗

PubMed2003

Phosphoinositide 3-kinase activity leads to silica-induced NF-kappaB activation through interacting with tyrosine-phosphorylated I(kappa)B-alpha and contributing to tyrosine phosphorylation of p65 NF-kappaB.

The role of the subunits of phosphoinositide (PI) 3-kinase in NF-kappaB activation in silica-stimulated RAW 264.7 cells was investigated. Results indicate that PI3-kinase activity was increased in response to silica. The p85alpha subunit of PI3-kinase interacted with tyrosine-phosphorylated I(kappa)B-alpha in silica-stimulated cells. PI3-kinase specific inhibitors, such as wortmannin and LY294003, substantially blocked both silica-induced PI3-kinase and NF-kappaB activation. The inhibition of NF-KB activation by PI3-kinase inhibitors was also observed in pervanadate-stimulated but not in LPS-stimulated cells. Furthermore, tyrosine phosphorylation of NF-kappaB p65 was enhanced in cells stimulated with silica, pervanadate or LPS, and wortmannin substantially inhibited the phosphorylation event induced by the first two stimulants but not LPS. Antioxidants, such as superoxide dismutase (SOD), N-acetylcysteine (NAC) and pyrrolidine dithiocarbamate (PDTC), blocked silica-induced PI3-kinase activation, suggesting that reactive oxygen species may be important regulatory molecules in NF-kappaB activation by mediating PI3-kinase activation. Our data suggest that p85 and p110 subunits of PI3-kinase play a role in NF-kappaB activation through interaction with tyrosine-phosphorylated I(kappa)B-alpha and contributing to tyrosine phosphorylation of p65 NF-kappaB.

Acetylcysteine↗

PubMed2003

Effect of asphalt fume inhalation exposure at simulated road paving conditions prior to bacterial infection on lung defense responses in rats.

Asphalt fume inhalation has been suspected of affecting immune function in exposed workers. The objective of this study was to evaluate the effect of asphalt exposure on lung immune responses in rats using a bacterial infectivity model. Pathogen-free male Sprague-Dawley rats were exposed by inhalation to asphalt fumes (72.6 +/- 4.95 mg/m3) or filtered air for 6 h/day for 5 days. One day after the final asphalt exposure, rats were intratracheally inoculated with 5 x 10(5) Listeria monocytogenes. At 0 (prior to bacterial inoculation), 3, and 7 days after L. monocytogenes instillation, the lungs of each animal were divided. Bronchoalveolar lavage (BAL) was performed on right lungs. The recovered BAL cells were then differentiated and counted, and alveolar macrophage (AM) function was determined. Albumin and lactate dehydrogenase (LDH), two indices of lung injury, were measured in the acellular BAL fluid. To assess bacterial clearance, the left lungs were removed, homogenized, and bacterial colony-forming units (CFUs) were counted. In addition, lung-draining lymph nodes were removed, and lymphocyte phenotype and lymphocyte-induced cytokine production were examined. Asphalt fume exposure did not cause lung injury or inflammation in rats in the absence of infection. Infection induced elevations in AMs, neutrophils (PMNs), albumin, and LDH. Importantly, no significant differences were seen when comparing the asphalt group with the air and nonexposed naive groups at any time before or after infection. Also, asphalt fume inhalation exposure did not affect the rate of pulmonary clearance of L. monocytogenes or AM production of reactive oxygen and nitrogen species. However, asphalt-related increases in lymphocyte secretion of interferon (IFN)-gamma, interleukin (IL)-6, and IL-10 were observed at different times after bacterial infection, whereas the total number of lymph-node cells and the percentage of CD4+ and CD8+ cells were not significantly different among the treatment groups. Despite the asphalt-induced changes observed in lymphokine secretion, adaptive immune function seemed to function properly in lung defense against bacterial infection. Because innate nonspecific lung responses and pulmonary clearance of L. monocytogenes were unaffected by asphalt fume exposure, lung defenses were sufficient to control the infection. It was concluded that acute inhalation of asphalt fumes at a high concentration had a minimal effect on lung immune responses to infection in rats.

Animals↗

PubMed2003

Time course for inhibition of lipopolysaccharide-induced lung injury by genistein: relationship to alteration in nuclear factor-kappaB activity and inflammatory agents.

OBJECTIVE: This study determined the time course for inhibition of lipopolysaccharide-induced acute lung injury following a single dose of genistein. In addition, the study investigated whether a multiple dosing schedule with genistein retained the inhibitory effects on acute lung injury, nuclear factor-kappaB activation, and production of nuclear factor-kappaB-dependent inflammatory agents, such as matrix metalloproteinase-9 and nitric oxide. DESIGN: Prospective, randomized, laboratory study. SETTING: Experimental laboratory at a university. SUBJECTS: Rats weighing 280-300 g. INTERVENTIONS: Saline or lipopolysaccharide (6 mg/kg of body weight) administered intratracheally with a single dose of genistein (50 mg/kg) or a multiple dosing schedule with genistein (16 mg/kg every 6 hrs for 2 days with lipopolysaccharide treatment at 24 hrs after the first administration of genistein). MEASUREMENTS AND MAIN RESULTS: A 2-hr pretreatment with genistein (a single dose) inhibited biochemical lung injury variables as well as neutrophil infiltration with a maximal inhibition at 4 hrs after lipopolysaccharide treatment. These inhibitory effects of genistein declined with time and were no longer significant by 14-24 hrs after lipopolysaccharide treatment. The multiple dosing schedule with genistein retained significant inhibitory effects on biochemical lung injury variables and the number of neutrophils in the bronchoalveolar lavage fluid at 24 hrs after lipopolysaccharide treatment compared with a single pretreatment with genistein. The multiple dosing schedule with genistein also enhanced the inhibition of induced nuclear factor-kappaB activity as well as matrix metalloproteinase-9 activity and nitric oxide production at 24 hrs after lipopolysaccharide treatment. CONCLUSIONS: This study reports the time course of the inhibitory effects of a single genistein pretreatment on acute lung injury with the maximal effects at 4 hrs after lipopolysaccharide treatment. However, a multiple dosing schedule with genistein retained the inhibitory effect on acute lung injury at 24 hrs after lipopolysaccharide treatment. The mechanisms by which genistein exerts an inhibitory effect on acute lung injury may involve the suppression of nuclear factor-kappaB activation, matrix metalloproteinase-9 activity, and NO production.

Animals↗

PubMed2003

Pharmacologic effects of tobacco dust extract on isolated Guinea pig trachea.

STUDY OBJECTIVE: To determine the effects of tobacco dust extract (TDE) on isolated guinea pig tracheal smooth muscle. DESIGN: A controlled, in vitro smooth-muscle study of the effect of pharmacologic agents on TDE. METHODS: The effect of TDE on isolated guinea pig tracheal smooth muscle was tested using water-soluble extracts of dust obtained from machines in a cigarette manufacturing plant. Dose-related contractions of nonsensitized guinea pig trachea were demonstrated using these extracts. The dust extracts contained significant quantities of bacterial components (eg, endotoxin). Pharmacologic studies were performed by pretreating guinea pig tracheal tissue with drugs known to modulate smooth-muscle contraction: atropine, indomethacin, pyrilamine, nordihydroguaretic acid, acivicin, bromophenacyl bromide, 3,4,5-trimethoxybenzoic acid-8-(diethylamino)octyl ester, captopril, and capsaicin. RESULTS: Atropine strikingly reduced the contractile effects of these extracts. Inhibition of contraction by blocking other mediators was less complete. There was no inhibition of contraction by hexamethonium (10(-4) mol/L, 10(-5) mol/L, 10(-6) mol/L), suggesting that nicotine was not the major contractile mediator of TDE. A separate analysis using different molecular weight fractions of TDE indicated that the constrictor activity appears to be primarily in the fraction with a molecular weight < 10 kd. Additionally, the constrictor effect resided entirely in the nonlipid fraction of the extract. We suggest that TDE causes dose-related airway smooth-muscle constriction by nonimmunologic mechanisms involving a variety of airway mediators and possibly cholinergic receptors. CONCLUSIONS: The bronchoconstrictor activity of TDE resides primarily in its low molecular weight, nonlipid fraction, and hexamethonium studies suggest that this agent is not nicotine.

Air Pollutants, Occupational↗

PubMed2002

Ultraviolet-induced phosphorylation of p70(S6K) at Thr(389) and Thr(421)/Ser(424) involves hydrogen peroxide and mammalian target of rapamycin but not Akt and atypical protein kinase C.

The p70 S6 kinase (p70(S6k)) is a Ser/Thr kinase that plays an important role in cell growth, transformation, and the transition of the cell cycle in mammalian cells. Because UV radiation has been reported to induce activation of p70(S6k), which is believed to play some role in the carcinogenic effects of sun exposure, the present study investigated the signaling pathways involved in this activation induced by UV radiation in mouse epidermal JB6 Cl41 cells. Exposure of cells to UV radiation led to marked increases in p70(S6k) activity and phosphorylation at Thr(389) and Thr(421)/Ser(424). UV radiation also generated reactive oxygen species as measured by electron spin resonance and by H(2)O(2) and O( minus sign, dot below )(2) fluorescence staining assays in JB6 Cl 41 cells. The scavenging of UV-generated H(2)O(2) by N-acety-L-cyteine (a general antioxidant) or catalase (a specific H(2)O(2) scavenger) inhibited p70(S6k) phosphorylation at Thr(389) and Thr(421)/Ser(424), whereas pretreatment of cells with sodium formate (an.OH radical scavenger) or superoxide dismutase (an O( minus sign, dot below )(2) radical scavenger) did not show any inhibitory effects. Importantly, UV-induced increases in p70(S6k) phosphorylation at Thr(389) and Thr(421)/Ser(424) were dramatically inhibited by pretreatment of cells with rapamycin, LY294002, or PD98059, whereas overexpression of dominant-negative mutants of PKClambda/iota and Akt1 did not inhibit p70(S6k) phosphorylation at Thr(389) and Thr(421)/Ser(424). These results demonstrated that H(2)O(2), phosphatidylinositol 3-kinase, and mammalian target of rapamycin were important players for UV-induced p70(S6k) phosphorylation at Thr(389) and Thr(421)/Ser(424), whereas Akt and atypical protein kinase C were not involved in this activation. The role of H(2)O(2) in p70(S6k) phosphorylation at Thr(389) and Thr(421)/Ser(424) was further supported by the findings that treatment of cells with H(2)O(2) also caused p70(S6k) phosphorylation at Thr(389) and Thr(421)/Ser(424).

Animals↗

PubMed2002

Comparative pulmonary toxicity of blasting sand and five substitute abrasive blasting agents.

Blasting sand is used for abrasive blasting, but its inhalation is associated with pulmonary inflammation and fibrosis. Consequently, safer substitute materials for blasting sand are needed. In a previous study from this laboratory, the comparative pulmonary toxicity of five abrasive blasting substitutes and blasting sand was reported. In this study, the pulmonary toxicity of blasting sand was compared to five additional abrasive blasting substitutes: steel grit, copper slag, nickel slag, crushed glass, and olivine. Exposed rats received by intratracheal instillation 10 mg of respirable-size particles of blasting sand or an abrasive blasting substitute, while controls were instilled with vehicle. Pulmonary inflammation, damage, and fibrosis were examined 28 d postexposure. Pulmonary inflammation was monitored by determining bronchoalveolar lavage polymorphonuclear cell counts and alveolar macrophage activation by chemiluminescence. Pulmonary damage was assessed by acellular bronchoalveolar (BAL) fluid serum albumin concentrations and lactate dehydrogenase activities. Histological examination of lung tissue samples was made to assess the severity and distribution of pulmonary fibrosis, alveolitis, and alveolar epithelial cell hypertrophy and hyperplasia. In comparison to blasting sand, olivine exposed rats had higher levels of pulmonary inflammation and damage with a similar level of fibrosis. Steel grit-exposed rats had lower levels of pulmonary inflammation and damage, and did not develop fibrosis. However, steel grit-exposed rats had a level of epithelial cell hypertrophy and hyperplasia similar to blasting sand. The other abrasive blasting substitutes gave a mixed profile of toxicity. The data demonstrate that steel grit produced less acute pulmonary toxicity than blasting sand or any of the other abrasive blasting substitutes. Notwithstanding, the data also suggest that chronic exposure to steel grit may pose a health risk due to its effects on epithelial cell proliferation in the lung.

Administration, Inhalation↗

PubMed2002

Metal working fluids: sub-chronic effects on pulmonary functions in B6C3F1 mice given vitamin E deficient and sufficient diets.

Metal working fluids (MWFs) have been widely known to cause asthma and neoplasia of the larynx, pancreas, rectum, skin and urinary bladder (Textbook of Clinical Occupational and Environmental Medicine (1994) 814; Am. J. Ind. Med. 32 (1997) 240; Am. J. Ind. Med. 33 (1997) 282; Am. J. Ind. Med. 22 (1994) 185). Other non-neoplastic respiratory effects in industrial workers attributed to MWFs include increased rates of cough, phlegm production, wheeze, chronic bronchitis and chest tightness (Eur. J. Resir. Dis. 63(118) (1982), 79; J. Occup. Med. 24 (1982) 473; Am. J. Ind. Med. 32 (1997) 450). The epidemic and endemic nature of immune mediated lung morbidity commonly known as hypersensitivity pneumonitis in workers from several different industries using MWFs has been well documented (J. Allergy clin. Immunol. 91 (1993) 311; Chest 108 (1995) 636; MMWR45 (1996) 606; Am. J. Ind. Med. 32 (1997) 423). We studied morphological/functional and antioxidant outcomes in lungs after inhalation exposure of vitamin E deficient mice to MWF (27 mg m(-3) 17 weeks, 5 days a week, 6 h a day). Mice were given vitamin E deficient (<10 IU kg(-1) vitamin E) or basal diets (50 IU kg(-1) vitamin E) for 35 weeks. Inhalation exposure to MWF started after 18 weeks on diet. Microscopic observation of lungs from mice given vitamin E deficient or sufficient diets revealed no inflammation or morphological alteration after exposure to MWF. Mice given vitamin E deficient diet exhibited a significant decrease (P<0.05) in breathing rate, peak inspiratory/expiratory flow, minute ventilation, and tidal volume compared with sufficient controls. However, no differences were found after exposure to MWF in pulmonary function, with the exception of tidal volume which also significantly decreased (P<0.05). Exposure to MWF reduced vitamin E, protein thiol and ascorbate level in lungs. Exposure to MWF in combination with a vitamin E deficient diet resulted in significantly enhanced accumulation of peroxidative products compared with vitamin E deficient controls. This is the first report that describes the increase of oxidative stress in the lungs after MWF exposure.

Animals↗

PubMed2002

Enhanced oxidative stress in the skin of vitamin E deficient mice exposed to semisynthetic metal working fluids.

Metal working fluids (MWFs) are widely used in industry for metal cutting, drilling, shaping, lubricating, and milling. Many occupational health concerns have arisen for workers exposed to MWFs. It has been reported earlier that occupational exposure to MWFs causes allergic and irritant contact dermatitis. Previously, we have shown that dermal exposure of female and male B6C3F1 mice to 5% MWFs for 3 months resulted in accumulation of mast cells and elevation of histamine in the skin. Topical exposure to MWFs also resulted in elevated oxidative stress in the liver of both sexes and the testes in males. The goal of this study was to evaluate whether preexisting oxidative stress in the skin exacerbated mast cell influx after MWFs treatment. Oxidative stress in the skin of B6C3F1 mice was generated by dietary vitamin E deprivation. Mice were given vitamin E deficient (5-10 i.v./kg of vitamin E) or basal (50 i.v./kg of vitamin E) diets for 34 weeks. Topical treatment with MWFs (100 microl, 30%) started after 18 weeks of alimentary vitamin E deprivation. Histology of the skin after 16 weeks of exposure to MWFs revealed a 53% increase in mast cell accumulation in vitamin E deficient diets compared to mice given a vitamin E sufficient diet. Total antioxidant reserve in skin of vitamin E deprived mice treated with MWFs was decreased by 66% as compared to those mice given a vitamin E sufficient diet. GSH and protein thiols in the dermis of vitamin E deprived mice exposed to MWFs were also decreased 39 and 42%, respectively, as compared to mice given basal diet. This study clearly delineates the role of oxidative stress in enhancing mast cell accumulation caused by topical exposure to MWFs.

Administration, Topical↗

PubMed2002

Comparison of low doses of aged and freshly fractured silica on pulmonary inflammation and damage in the rat.

Most previous studies of silica toxicity have used relatively high exposure doses of silica. In this study, male rats received by intratracheal instillation either vehicle, aged or freshly fractured silica at a dose of either 5 microg/rat once a week for 12 weeks (total dose=60 microg) or 20 microg/rat once a week for 12 weeks (total dose=240 microg). One week after the last exposure, bronchoalveolar lavage (BAL) was conducted and markers of pulmonary inflammation, alveolar macrophage (AM) activation and pulmonary damage were examined. For rats exposed to a total of 60 microg silica, both aged and freshly fractured silica increased polymorphonuclear leukocytes (PMN) yield and AM activation above control to a similar degree, but no evidence of pulmonary damage, as measured by BAL fluid lactate dehydrogenase activity or albumin concentration, was detected. For rats exposed to 240 microg silica, aged or freshly fractured silica increased PMN yield and AM activation above control. However, zymosan-stimulated and L-NAME sensitive AM chemiluminescence was greater for rats exposed to freshly fractured silica compared to aged silica. Exposure to 240 microg aged or freshly fractured silica also resulted in pulmonary damage, but the extent of this damage did not differ between the two types of silica. The results suggest that exposure of rats to silica levels far lower than those previously examined can cause pulmonary inflammation. In addition, exposure to freshly fractured silica causes greater generation of reactive oxygen species from AM, measured as AM chemiluminescence, in comparison to aged silica, but there is an apparent threshold below which this difference does not occur.

Albumins↗

PubMed2002

Modified endotoxin responses in rats pretreated with 1-->3-beta-glucan (zymosan A).

The present study investigates whether 1-->3-beta-glucans (zymosan particles) modify the pulmonary response of rats to endotoxin (lipopolysaccharide, LPS). Initial experiments were conducted to establish appropriate doses of LPS and regimens for exposure to zymosan and LPS. Interaction between zymosan and LPS exposures was determined to be the deviation from the sum of the individual effects of these agents. Treatment with zymosan on Day 1 and LPS on Day 2 modified several indices of pulmonary responsiveness, including tumor necrosis factor-alpha, albumin, and lactate dehydrogenase activity (LDH) in first acellular lavage fluid as well as the levels of chemiluminescence (CL), NO-dependent CL, and nitric oxide production in cultured lavaged alveolar macrophage cells determined 1 day after exposure. No significant deviation from additivity was found for breathing rate increase and polymorphonuclear leukocytes infiltration. Simultaneous administration of zymosan and LPS or administration of LPS before zymosan did not change these indices of pulmonary responsiveness. These data suggest that the inhibitory effect of 1-->3-beta-glucans on pulmonary responsiveness to endotoxin exposure was apparent only when rats were pretreated with 1-->3-beta-glucan. These results suggest that complex interaction of components may exist in exposure to organic dusts. Therefore, hazard may not be defined by measuring endotoxin or 1-->3-beta-glucans alone.

Animals↗

PubMed2002

Induction of neutrophil apoptosis and secondary necrosis during endotoxin-induced pulmonary inflammation in mice.

The present study investigated the relationship between apoptotic and necrotic cell death and their role in pulmonary inflammatory response to endotoxin. Pulmonary administration of lipopolysaccharide (LPS) caused a rapid increase in the levels of pro-inflammatory cytokine TNF-alpha and inflammatory cell influx in the bronchoalveolar lavage (BAL) fluids. Control mice showed only resident alveolar macrophages with no apoptosis, whereas LPS-treated mice showed clear apoptosis of BAL cells. Microscopic studies confirmed the presence of apoptotic neutrophils and macrophages ingesting apoptotic bodies. The number of apoptotic neutrophils increased concomitantly with the increase in neutrophil influx which peaked 1 day after the treatment. However, necrosis was not detected at this early time, but increased subsequently and peaked at day 3. The levels of necrosis and apoptosis were both elevated and prolonged at high LPS doses. Treatment of mice with phosphatidylserine (PS)-containing liposome, known to inhibit macrophage phagocytosis of apoptotic cells, increased the level of apoptosis and necrosis caused by LPS, whereas control non-PS liposome or saline treatment had no effects. We conclude that necrosis occurs secondary to apoptosis in LPS-treated lung model and that this development is not the result of direct insult by LPS. Instead, our results and previous studies suggest that inefficient clearance of apoptotic cells by macrophages contributes, at least in part, to the levels of apoptosis and necrosis induced by LPS. Because necrosis is associated with cell damage and release of histotoxic contents, this development is likely to play a role in determining the severity and duration of lung toxicity induced by endotoxin.

Animals↗

PubMed2002

Selective peroxidation and externalization of phosphatidylserine in normal human epidermal keratinocytes during oxidative stress induced by cumene hydroperoxide.

Reactive oxygen species not only modulate important signal transduction pathways, but also induce DNA damage and cytotoxicity in keratinocytes. Hydrogen peroxide and organic peroxides are particularly important as these chemicals are widely used in dermally applied cosmetics and pharmaceuticals, and also represent endogenous metabolic intermediates. Lipid peroxidation is of fundamental interest in the cellular response to peroxides, as lipids are extremely sensitive to oxidation and lipid-based signaling systems have been implicated in a number of cellular processes, including apoptosis. Oxidation of specific phospholipid classes was measured in normal human epidermal keratinocytes exposed to cumene hydroperoxide after metabolic incorporation of the fluorescent oxidation-sensitive fatty acid, cis-parinaric acid, using a fluorescence high-performance liquid chromatography assay. In addition, lipid oxidation was correlated with changes in membrane phospholipid asymmetry and other markers of apoptosis. Although cumene hydroperoxide produced significant oxidation of cis-parinaric acid in all phospholipid classes, one phospholipid, phosphatidylserine, appeared to be preferentially oxidized above all other species. Using fluorescamine derivatization and annexin V binding it was observed that specific oxidation of phosphatidylserine was accompanied by phosphatidylserine translocation from the inner to the outer plasma membrane surface where it may serve as a recognition signal for interaction with phagocytic macrophages. These effects occurred much earlier than any detectable changes in other apoptotic markers such as caspase-3 activation, DNA fragmentation, or changes in nuclear morphology. Thus, normal human epidermal keratinocytes undergo profound lipid oxidation with preference for phosphatidylserine followed by phosphatidylserine externalization upon exposure to cumene hydroperoxide. It is therefore likely that normal human epidermal keratinocytes exposed to similar oxidative stress in vivo would under go phosphatidylserine oxidation/translocation. This would make them targets for macrophage recognition and phagocytosis, and thus limit their potential to invoke inflammation or give rise to neoplastic transformations.

Adult↗

PubMed2002

Time course of pulmonary response of rats to inhalation of crystalline silica: NF-kappa B activation, inflammation, cytokine production, and damage.

In vitro studies suggest that silica-induced lung disease may be linked to processes regulated by nuclear factor-kappa B (NF-kappa B) activation, but this has not been examined in vivo. Rats were exposed to a silica aerosol of 15 mg/m(3) (6 h/day, 5 days/wk) for 116 days, and bronchoalveolar lavage (BAL) was conducted at various times during the exposure. Silica-induced pulmonary inflammation and damage were determined by measuring BAL cell differentials and first BAL fluid lactate dehydrogenase (LDH) activity and serum albumin concentrations, respectively. NF-kappa B activation and production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) by BAL cells were also measured. The results demonstrate that NF-kappa B activation occurred after 5 days exposure, and continued to increase thereafter. BAL cell production of IL-1 and TNF-alpha had increased incrementally by 10 and 30 days of exposure, respectively. This elevation continued through 79 days of exposure before further increasing at 116 days of exposure. Pulmonary inflammation and damage in silica-exposed rats were also significantly elevated at 5 days of exposure, further increased at a slow rate through 41 days of exposure, and dramatically increased thereafter. Taken together, the results indicate that the initial molecular response of NF-kappa B activation in BAL cells occurs in response to low levels of silica deposition in the lung and increases more rapidly versus exposure duration than silica-induced pulmonary inflammation, cellular damage, and cytokine production by BAL cells. This suggests that NF-kappa B activation in BAL cells may play an important role in the initiation and progression of silica-induced pulmonary inflammation, cellular damage, and fibrosis.

Animals↗

PubMed2002

Inhibition of mitogenic stimulant-induced activation of thymocytes with zinc tetrakis-(N-methyl-4'-pyridyl) porphyrinato.

Zinc porphyrins have anti-inflammatory and anti-allergic properties. The objective of the present study was to characterize the mechanism of zinc tetrakis-(N-methyl-4'-pyridyl) porphyrinato (ZnTMPyP) immune modulation by investigating its effects on the proliferative activity during thymocyte stimulation with mitogenic factors and the molecular events mediating thymocyte proliferation. The results indicate that ZnTMPyP inhibited thymocyte proliferation stimulated with various mitogenic factors, such as concanavalin A (Con A), interleukin (IL)-1beta, and lipopolysaccharide-exposed macrophage supernatant, in a concentration-dependent manner. ZnTMPyP was also effective in preventing DNA binding activity of nuclear factor kappaB (NF-kappaB) and IL-2 production by thymocytes in response to Con A or IL-1beta. Inhibition of p38 mitogen-activated protein kinase (MAPK) with SB203580 substantially inhibited Con A- or IL-1beta-induced DNA binding activity of NF-kappaB, whereas ZnTMPyP inhibited the activation of p38 MAPK. ZnTMPyP also inhibited Con A-induced chemiluminescence and tyrosine phosphorylation by thymocytes. In conclusion, our findings suggest that the antiproliferative effect of ZnTMPyP may be mediated by effective inhibition of the production of reactive oxygen species, tyrosine phosphorylation, p38 MAPK activation, NF-kappaB activation, and IL-2 production during mitogenic stimulation of thymocytes.

Animals↗

PubMed2002

Enhanced nitric oxide and reactive oxygen species production and damage after inhalation of silica.

In previous reports from this study, measurements of pulmonary inflammation, bronchoalveolar lavage cell cytokine production and nuclear factor-kappa B activation, cytotoxic damage, and fibrosis were detailed. In this study, we investigated the temporal relationship between silica inhalation, nitric oxide (NO), and reactive oxygen species (ROS) production, and damage mediated by these radicals in the rat. Rats were exposed to a silica aerosol (15 mg/m(3) silica, 6 h/day, 5 days/wk) for 116 days. We report time-dependent changes in 1) activation of alveolar macrophages and concomitant production of NO and ROS, 2) immunohistochemical localization of inducible NO synthase and the NO-induced damage product nitrotyrosine, 3) bronchoalveolar lavage fluid NO(x) and superoxide dismutase concentrations, and 4) lung lipid peroxidation levels. The major observations made in this study are as follows: 1) NO and ROS production and resultant damage increased during silica exposure, and 2) the sites of inducible NO synthase activation and NO-mediated damage are associated anatomically with pathological lesions in the lungs.

Administration, Inhalation↗

PubMed2002

Antioxidant properties of fruit and vegetable juices: more to the story than ascorbic acid.

Dietary supplements such as vitamin C have become popular for their perceived ability to enhance the body's antioxidant defenses. Reactive oxygen species (ROS) have been shown to cause a broad spectrum of damage to biological systems. Scavenging of ROS is part of a healthy, well-balanced, antioxidant defense system. The present study used the Fenton reaction as a source of hydroxyl radicals and xanthine/xanthine oxidase as a source of superoxide radicals to investigate the scavenging capabilities of various fruit and vegetable juices against these radicals. Electron spin resonance (ESR) spin trapping was used for free radical detection and measurement. Using a colormetric assay, the present study also investigated the protective effects of fruit and vegetable juices against lipid peroxidation induced in cell membranes by hydroxyl radicals. The present study showed that the free radical scavenging capability of each individual juice, but not its ascorbic acid content, is correlated with its protective effect on free radical induced lipid peroxidation. The results indicate that ascorbic acid is only one facet of the protective effect of fruit and vegetable juices. It appears that consumption of whole fruits and vegetables would be superior to an ascorbic acid supplement for antioxidant effectiveness.

Antioxidants↗

PubMed2002

Role of neutrophil apoptosis in vanadium-induced pulmonary inflammation in mice.

Pulmonary exposure to airborne vanadium and vanadium-containing compounds is associated with acute pulmonary inflammation, characterized by a rapid influx of neutrophilic polymorphonuclear leukocytes with a peak response at 6 hours and resolution by 3 days. We hypothesized that neutrophil apoptosis is involved in the resolution of vanadium-induced lung inflammation. To test this hypothesis, mice were exposed to inspired vanadium or saline control and the bronchoalveolar lavage (BAL) cells were examined at various times for apoptosis using terminal deoxyribonucleotidyl transferase-mediated nick end labeling (TUNEL). Control mice showed only resident alveolar macrophages in the BAL with no evidence of apoptosis. In contrast, vanadium-treated mice showed clear apoptosis of BAL cells, which were predominantly neutrophils. The number of apoptotic cells gradually increased and reached a maximal level by 24 hours with subsequent decline. After 24 hours, when the vanadium-induced lung inflammation was in the resolution phase, we observed an increased number of alveolar macrophages in BAL and the engulfment of apoptotic bodies by these macrophages. At 72 hours, the total number of neutrophils in BAL fell to the baseline level, and the number of apoptotic cells was reduced. Clearance of the apoptotic product was demonstrated by the presence of apoptotic bodies in the cytoplasm of alveolar macrophages. We conclude that apoptosis of neutrophils and clearance by alveolar macrophages are important mechanisms in the resolution of vanadium-induced lung inflammation.

Animals↗