1 Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262; and 2 Service d'Anesthesie-Réanimation et Unité Propre de Recherche ...de l'Enseignement Superieur-Equipe d'Accueil (UPRES-EA 392), Hopital de Bicêtre, Le Kremlin Bicêtre, France 94275
Submitted 11 July 2003
; accepted in final form 12 November 2003
Reactive oxygen species (ROS), including hydrogen peroxide (H 2 O 2 ), are generated in increased amounts in pathological, biological processes and can play a role in signal transduction. Neutrophils often accumulate in acute inflammatory reactions, at sites where elevated concentrations of ROS are present. ROS have been demonstrated to participate in the activation of intracellular signaling pathways, including those involved in modulating nuclear accumulation and transcriptional activity of NF- B. However, the role of ROS in affecting such events in neutrophils has not been examined. Using exposure of murine bone marrow neutrophils to H 2 O 2 as a model of oxidative stress, we found both strong and persistent activation of ERK1/2, p38, JNK, and PKB, but not the p21-activated kinase. Stimulating the bone marrow-derived neutrophils with H 2 O 2 did not affect nuclear translocation of NF- B. However, production and secretion of the proinflammatory cytokine TNF- in LPS-stimulated neutrophils were inhibited by H 2 O 2 . Exposure of LPS- or TNF- -stimulated neutrophils to H 2 O 2 decreased nuclear translocation of NF- B. LPS-induced activation of the transcriptional factor AP-1 was also inhibited by H 2 O 2 . This inhibition of nuclear accumulation of NF- B by H 2 O 2 was not caused by an impaired capacity of LPS to stimulate the IKK pathway or to direct oxidative effects on NF- B but rather reflected diminished degradation of I B- . These results indicate that oxidative stress, despite being able to selectively activate intracellular kinases in bone marrow-derived neutrophils, also inhibits NF- B activation and associated TNF- expression. Such inhibitory effects on neutrophil activation may limit tissue damage produced by oxidative stress.
oxidative stress; reactive oxygen species; tumor necrosis factor-
Address for reprint requests and other correspondence: D. Strassheim, Division of Pulmonary Sciences and Critical Care Medicine, Univ. of Colorado Health Sciences Center, Box C272, 4200 East 9th Ave., Denver, CO 80262 (E-mail: derek.strassheim{at}uchsc.edu ).
Reactive oxygen species (ROS), including hydrogen peroxide (H 2 O 2 ), are generated in increased amounts in pathological, biological processes and can play a role in signal transduction. Neutrophils ...often accumulate in acute inflammatory reactions, at sites where elevated concentrations of ROS are present. ROS have been demonstrated to participate in the activation of intracellular signaling pathways, including those involved in modulating nuclear accumulation and transcriptional activity of NF-κB. However, the role of ROS in affecting such events in neutrophils has not been examined. Using exposure of murine bone marrow neutrophils to H 2 O 2 as a model of oxidative stress, we found both strong and persistent activation of ERK1/2, p38, JNK, and PKB, but not the p21-activated kinase. Stimulating the bone marrow-derived neutrophils with H 2 O 2 did not affect nuclear translocation of NF-κB. However, production and secretion of the proinflammatory cytokine TNF-α in LPS-stimulated neutrophils were inhibited by H 2 O 2 . Exposure of LPS- or TNF-α-stimulated neutrophils to H 2 O 2 decreased nuclear translocation of NF-κB. LPS-induced activation of the transcriptional factor AP-1 was also inhibited by H 2 O 2 . This inhibition of nuclear accumulation of NF-κB by H 2 O 2 was not caused by an impaired capacity of LPS to stimulate the IKK pathway or to direct oxidative effects on NF-κB but rather reflected diminished degradation of IκB-α. These results indicate that oxidative stress, despite being able to selectively activate intracellular kinases in bone marrow-derived neutrophils, also inhibits NF-κB activation and associated TNF-α expression. Such inhibitory effects on neutrophil activation may limit tissue damage produced by oxidative stress.
Reactive oxygen species (ROS), including hydrogen peroxide (H2O2), are generated in increased amounts in pathological, biological processes and can play a role in signal transduction. Neutrophils ...often accumulate in acute inflammatory reactions, at sites where elevated concentrations of ROS are present. ROS have been demonstrated to participate in the activation of intracellular signaling pathways, including those involved in modulating nuclear accumulation and transcriptional activity of NF-kappaB. However, the role of ROS in affecting such events in neutrophils has not been examined. Using exposure of murine bone marrow neutrophils to H2O2 as a model of oxidative stress, we found both strong and persistent activation of ERK1/2, p38, JNK, and PKB, but not the p21-activated kinase. Stimulating the bone marrow-derived neutrophils with H2O2 did not affect nuclear translocation of NF-kappaB. However, production and secretion of the proinflammatory cytokine TNF-alpha in LPS-stimulated neutrophils were inhibited by H2O2. Exposure of LPS- or TNF-alpha-stimulated neutrophils to H2O2 decreased nuclear translocation of NF-kappaB. LPS-induced activation of the transcriptional factor AP-1 was also inhibited by H2O2. This inhibition of nuclear accumulation of NF-kappaB by H2O2 was not caused by an impaired capacity of LPS to stimulate the IKK pathway or to direct oxidative effects on NF-kappaB but rather reflected diminished degradation of IkappaB-alpha. These results indicate that oxidative stress, despite being able to selectively activate intracellular kinases in bone marrow-derived neutrophils, also inhibits NF-kappaB activation and associated TNF-alpha expression. Such inhibitory effects on neutrophil activation may limit tissue damage produced by oxidative stress.
Livestock workers experience an increased burden of bioaerosol-induced respiratory disease including a high prevalence of rhinosinusitis. Dairy operations generate bioaerosols spanning the inhalable ...size fraction (0-100 μm) containing bacterial constituents such as endotoxin. Particles with an aerodynamic diameter between 10 and 100 μm are known to deposit in the nasopharyngeal region and likely affect the upper respiratory tract. We evaluated the effectiveness of a hypertonic saline nasal lavage in reducing inflammatory responses in dairy workers from a high-volume dairy operation. Inhalable personal breathing zone samples and pre-/post-shift nasal lavage samples from each participant over five consecutive days were collected. The treatment group (n = 5) received hypertonic saline while the control group (n = 5) received normotonic saline. Personal breathing zone samples were analyzed for particulate concentrations and endotoxin using gravimetric and enzymatic methods, respectively. Pro- and anti-inflammatory cytokines (i.e., IL-8, IL-10, and TNF-α) were measured from nasal lavage samples using a multiplex assay. Inhalable dust concentrations ranged from 0.15 to 1.9 mg/m
3
. Concentrations of both pro- and anti-inflammatory cytokines, specifically IL-6, IL-8, and IL-10, were significantly higher in the treatment group compared to the control group (p < 0.02, p < 0.04, and p < 0.01, respectively). Further analysis of IL-10 anti-inflammatory indicates a positive association between hypertonic saline administration and IL-10 production. This pilot study demonstrates that hypertonic saline nasal lavages were successful in upregulating anti-inflammatory cytokines to support larger interventional studies.
