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Initiation and Tolerance to Acute Lung Injury
(with relevant controls), and light microscopic densitometry to compare the distribution of each mediator between the two groups. For light microscopic densitometry, five random fields each were drawn across pulmonary arterial endothelial and smooth muscle cells, airway epithelial cells, and alveolar macrophages. Nuclei were excluded. The image analysis system automatically determined the brown immunostain density. This procedure was repeated for at least 10 vessels, airways, and alveolar macrophages per subject. The eNOS immunostaining of pulmonary arterial endothelial cells was consistently less in the subjects who died with ARDS (relative densitometry units of 21 6 7; mean 6 SD) compared to subjects who died without ARDS (59 6 10). We saw little immunostaining of alveolar wall microvessels. The ARDS subjects also consistently had less immunostaining for eNOS in airway epithelial cells (16 6 7) compared to subjects without ARDS (29 6 9). Immunostaining for iNOS was restricted to alveolar macrophages (79 6 11) and airway epithelial cells (31 6 10) in subjects who died with ARDS. In subjects without ARDS, alveolar macrophages and airway epithelial cells expressed very little iNOS (9 6 3 and 8 6 4, respectively). ET-1 expression was observed in vascular endothelial cells (64 6 8) and smooth muscle cells (25 6 11), airway epithelial cells (19 6 7), distal airspace epithelial cells (21 6 5), and alveolar macrophages (52 6 6) of subjects with ARDS. Their airspace contents, including hyaline membranes, were ET-1 immunopositive. In contrast, subjects who died without ARDS had very little ET-1 expression (, 10 densitometry units among the cell types). These results provide cellular identification of the sources of eNOS, iNOS, and ET-1 in the lungs of subjects who died with ARDS, as well as demonstrating striking differences in the phenotypic expression patterns of these inflammatory mediators compared to subjects who died without ARDS.
A persistent concept in the sought-after understanding of the pathogenesis of ARDS has been that an exaggerated systemic inflammatory process contributes to the pulmonary dysfunction and the multiorgan failure that subsequently characterize the syndrome. This inflammatory process is in part reflected by the increased numbers of neutrophils and increased levels of cytokines in the lung lavages of affected ARDS patients compared with control subjects. Moreover, numerous in vitro and animal studies have provided extensive evidence that suggests that neutrophils and cytokines can cause endothelial cell damage and produce lung leak abnormalities that are consistent with the lung abnormalities that occur in ARDS patients. We became interested in determining the significance of the elevated interleukin-1 (IL-1) levels that are manifest in the lungs of ARDS patients compared with control subjects. Although the sources of the increased IL-1 levels are unclear, alveolar macrophages recovered from ARDS patients and then cultured in vitro secrete more IL-1 than alveolar macrophages recovered from control subjects. To determine the importance of elevated IL-1 levels in the lung, we instilled IL-1 into the trachea of healthy rats.1 We found that lungs of rats given IL-1 (50 ng) intratracheally promptly (5 h) became edematous and that IL-1-induced lung leak was associated with increases in lung nuclear factor-kappa B (NF-kB) activity, neutrophils, tumor necrosis factor (TNF), cytokine-induced neutrophil chemoattractant, and oxidative stress that was reflected by enhanced exhalation of H2O2 and increased lung oxidized glutathione levels. Treatment with vinblastine (neutrophil depletion), TNF binding protein, anticytokine-induced neutrophil chemoattractant antibodies, or various agents with antioxidant properties (superoxide dismutase, dimethylsulfoxide, aerosolized vitamin E, N-acetylcysteine or IL-1-receptor antagonist) decreased lung leak and indicated that IL-1 caused a neutrophil-dependent, oxidative lung leak.2 Figure 1 shows possible relationships of the
Initiation and Tolerance to Acute Lung Injury* Yin-Yang Mechanisms Involving Interleukin-1 Rosa Faust-Chan; Brooks Hybertson, PhD; Sonia C. Flores, PhD; Richard M. Wright, PhD; and John E. Repine, MD
(CHEST 1999; 116:102S–103S) RDS remains a medical problem of considerable importance. Recent clinical trials, unfortunately, have failed to identify any therapeutic agent that has the potential of reducing the consequences of this devastating condition.
A
*From the Webb-Waring Institute for Cancer, Aging, and Antioxidant Research at the University of Colorado Health Sciences Center, Denver, CO. Correspondence to: John E. Repine, MD, 4200 E Ninth Ave, Box C322, Denver, CO
Figure 1. Possible relationships of the findings that occur in both ARDS patients and rats given IL-1 intratracheally.
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Thomas L. Petty 41st Annual Aspen Lung Conference: Acute Lung Injury
findings that occur in both ARDS patients and rats given IL-1 intratracheally. The cyclical diagram (Fig 1) implies that the “wheel” can be started at various points–a proposition that is consistent with the diverse precipitating events and various predisposing factors that initiate the syndrome. The central role for oxidative stress is emphasized based on knowledge of the numerous interactions caused by these highly reactive molecules that are increased in ARDS patients. While it is clear that a neutrophil-mediated oxidative insult can contribute to lung injury, it is becoming evident that these processes may also participate in responses that may protect the lung against neutrophil and oxidative damage. We and other investigators have also pursued a number of experiments that indicate that a prior oxidative stress can confer resistance or tolerance to a subsequent oxidative stress.3– 6 One pertinent example is the observation that exposure of rats to sublethal concentrations of oxygen (approximately 85% O2) produces resistance to the usually fatal event that occurs following continuous exposure to 100% O2. Pretreatment with endotoxin, TNF, and/or IL-1 also produces resistance to pulmonary oxygen toxicity in rats and ischemia reperfusion-related abnormalities in isolated rat hearts. With respect to IL-1, we found that following instillation of IL-1 intratracheally, lungs of rats that had been pretreated with IL-1 had the same numbers of neutrophils, but developed less leak than lungs of rats that had been pretreated with saline solution. Similarly, following perfusion with neutrophils and IL-1 instillation intratracheally, lungs isolated from rats that had been pretreated with IL-1 also developed less leak than lungs isolated from rats that had been pretreated with saline solution. In parallel, rat lung microvascular endothelial cells (RLMECs) that had been pretreated with IL-1 in vitro resisted injury from neutrophils stimulated by phorbol myristate acetate better than saline solution pretreated RLMECs. IL-1-pretreated RLMECs had increased NF-kB activation compared with saline solution pretreated RLMECs, and overexpression of the mutant forms of IkBa (S32/36A) or IkBb (S19/23A) decreased both NF-kB activation and tolerance in the IL-1 pretreated RLMECs. Therefore, in three systems, IL-1 pretreatment increased resistance to a neutrophil-mediated, oxidantdependent insult. Recognizing that IL-1 can both cause and prevent neutrophil-mediated lung injury raises concerns about the design and interpretation of approaches that directly or indirectly alter IL-1 levels in these circumstances. We are attempting to decipher the mechanisms responsible for these “yin-yang” responses to IL-1 with the hope that this new information will produce insights in the treatment and prevention of ARDS (Fig 2).
References 1 Leff JA, Baer JW, Bodman ME, et al. Interleukin-1a-induced lung neutrophil accumulation and oxygen metabolite mediated lung leak in rats. Am J Physiol (Lung Cell Mol Physiol) 1994; 266:2– 8
Figure 2. “Yin-yang” of IL-1 and ARDS.
2 Leff JA, Bodman ME, Cho OJ, et al. Post-insult treatment with interleukin-1 receptor antagonist decreases oxidative lung injury in rats given intratracheal interleukin-1. Am J Respir Crit Care Med 1994; 150:109 –112 3 Leff JA, Wilke CP, Furman MJ, et al. Interleukin-1 pretreatment prevents interleukin-1-induced lung leak in rats. Am J Physiol: Lung Cell Mol Physiol 1995; 268:12–16 4 Repine JE. Interleukin-1-mediated acute lung injury and tolerance to oxidative injury. Environmental Health Perspectives 1994; 102:75–78. 5 Brown JM, White CW, Terada LS, et al. Interleukin-1 pretreatment decreases ischemia-reperfusion injury. Proc Natl Acad Sci USA 1990; 87:5026 –5030 6 White CW, Ghezzi P, Dinarello CA, et al. Recombinant tumor necrosis factor/cachectin and interleukin-1 pretreatment decreases lung oxidized glutathione accumulation, lung injury and mortality in rats exposed to hyperoxia. J Clin Invest 1987; 79:1868 –1873
Chemokines in Lung Injury* Thomas A. Neff Lecture Robert M. Strieter, MD, FCCP; Steven L. Kunkel, MD; Michael P. Keane, MBBCh; and Theodore J. Standiford, MD
(CHEST 1999; 116:103S–110S) CHEST / 116 / 1 / JULY, 1999 SUPPLEMENT
103S
A persistent concept in the sought-after understanding of the pathogenesis of ARDS has been that an exaggerated systemic inflammatory process contributes to the pulmonary dysfunction and the multiorgan failure that subsequently characterize the syndrome. This inflammatory process is in part reflected by the increased numbers of neutrophils and increased levels of cytokines in the lung lavages of affected ARDS patients compared with control subjects. Moreover, numerous in vitro and animal studies have provided extensive evidence that suggests that neutrophils and cytokines can cause endothelial cell damage and produce lung leak abnormalities that are consistent with the lung abnormalities that occur in ARDS patients. We became interested in determining the significance of the elevated interleukin-1 (IL-1) levels that are manifest in the lungs of ARDS patients compared with control subjects. Although the sources of the increased IL-1 levels are unclear, alveolar macrophages recovered from ARDS patients and then cultured in vitro secrete more IL-1 than alveolar macrophages recovered from control subjects. To determine the importance of elevated IL-1 levels in the lung, we instilled IL-1 into the trachea of healthy rats.1 We found that lungs of rats given IL-1 (50 ng) intratracheally promptly (5 h) became edematous and that IL-1-induced lung leak was associated with increases in lung nuclear factor-kappa B (NF-kB) activity, neutrophils, tumor necrosis factor (TNF), cytokine-induced neutrophil chemoattractant, and oxidative stress that was reflected by enhanced exhalation of H2O2 and increased lung oxidized glutathione levels. Treatment with vinblastine (neutrophil depletion), TNF binding protein, anticytokine-induced neutrophil chemoattractant antibodies, or various agents with antioxidant properties (superoxide dismutase, dimethylsulfoxide, aerosolized vitamin E, N-acetylcysteine or IL-1-receptor antagonist) decreased lung leak and indicated that IL-1 caused a neutrophil-dependent, oxidative lung leak.2 Figure 1 shows possible relationships of the
Initiation and Tolerance to Acute Lung Injury* Yin-Yang Mechanisms Involving Interleukin-1 Rosa Faust-Chan; Brooks Hybertson, PhD; Sonia C. Flores, PhD; Richard M. Wright, PhD; and John E. Repine, MD
(CHEST 1999; 116:102S–103S) RDS remains a medical problem of considerable importance. Recent clinical trials, unfortunately, have failed to identify any therapeutic agent that has the potential of reducing the consequences of this devastating condition.
A
*From the Webb-Waring Institute for Cancer, Aging, and Antioxidant Research at the University of Colorado Health Sciences Center, Denver, CO. Correspondence to: John E. Repine, MD, 4200 E Ninth Ave, Box C322, Denver, CO
Figure 1. Possible relationships of the findings that occur in both ARDS patients and rats given IL-1 intratracheally.
102S
Thomas L. Petty 41st Annual Aspen Lung Conference: Acute Lung Injury
findings that occur in both ARDS patients and rats given IL-1 intratracheally. The cyclical diagram (Fig 1) implies that the “wheel” can be started at various points–a proposition that is consistent with the diverse precipitating events and various predisposing factors that initiate the syndrome. The central role for oxidative stress is emphasized based on knowledge of the numerous interactions caused by these highly reactive molecules that are increased in ARDS patients. While it is clear that a neutrophil-mediated oxidative insult can contribute to lung injury, it is becoming evident that these processes may also participate in responses that may protect the lung against neutrophil and oxidative damage. We and other investigators have also pursued a number of experiments that indicate that a prior oxidative stress can confer resistance or tolerance to a subsequent oxidative stress.3– 6 One pertinent example is the observation that exposure of rats to sublethal concentrations of oxygen (approximately 85% O2) produces resistance to the usually fatal event that occurs following continuous exposure to 100% O2. Pretreatment with endotoxin, TNF, and/or IL-1 also produces resistance to pulmonary oxygen toxicity in rats and ischemia reperfusion-related abnormalities in isolated rat hearts. With respect to IL-1, we found that following instillation of IL-1 intratracheally, lungs of rats that had been pretreated with IL-1 had the same numbers of neutrophils, but developed less leak than lungs of rats that had been pretreated with saline solution. Similarly, following perfusion with neutrophils and IL-1 instillation intratracheally, lungs isolated from rats that had been pretreated with IL-1 also developed less leak than lungs isolated from rats that had been pretreated with saline solution. In parallel, rat lung microvascular endothelial cells (RLMECs) that had been pretreated with IL-1 in vitro resisted injury from neutrophils stimulated by phorbol myristate acetate better than saline solution pretreated RLMECs. IL-1-pretreated RLMECs had increased NF-kB activation compared with saline solution pretreated RLMECs, and overexpression of the mutant forms of IkBa (S32/36A) or IkBb (S19/23A) decreased both NF-kB activation and tolerance in the IL-1 pretreated RLMECs. Therefore, in three systems, IL-1 pretreatment increased resistance to a neutrophil-mediated, oxidantdependent insult. Recognizing that IL-1 can both cause and prevent neutrophil-mediated lung injury raises concerns about the design and interpretation of approaches that directly or indirectly alter IL-1 levels in these circumstances. We are attempting to decipher the mechanisms responsible for these “yin-yang” responses to IL-1 with the hope that this new information will produce insights in the treatment and prevention of ARDS (Fig 2).
References 1 Leff JA, Baer JW, Bodman ME, et al. Interleukin-1a-induced lung neutrophil accumulation and oxygen metabolite mediated lung leak in rats. Am J Physiol (Lung Cell Mol Physiol) 1994; 266:2– 8
Figure 2. “Yin-yang” of IL-1 and ARDS.
2 Leff JA, Bodman ME, Cho OJ, et al. Post-insult treatment with interleukin-1 receptor antagonist decreases oxidative lung injury in rats given intratracheal interleukin-1. Am J Respir Crit Care Med 1994; 150:109 –112 3 Leff JA, Wilke CP, Furman MJ, et al. Interleukin-1 pretreatment prevents interleukin-1-induced lung leak in rats. Am J Physiol: Lung Cell Mol Physiol 1995; 268:12–16 4 Repine JE. Interleukin-1-mediated acute lung injury and tolerance to oxidative injury. Environmental Health Perspectives 1994; 102:75–78. 5 Brown JM, White CW, Terada LS, et al. Interleukin-1 pretreatment decreases ischemia-reperfusion injury. Proc Natl Acad Sci USA 1990; 87:5026 –5030 6 White CW, Ghezzi P, Dinarello CA, et al. Recombinant tumor necrosis factor/cachectin and interleukin-1 pretreatment decreases lung oxidized glutathione accumulation, lung injury and mortality in rats exposed to hyperoxia. J Clin Invest 1987; 79:1868 –1873
Chemokines in Lung Injury* Thomas A. Neff Lecture Robert M. Strieter, MD, FCCP; Steven L. Kunkel, MD; Michael P. Keane, MBBCh; and Theodore J. Standiford, MD
(CHEST 1999; 116:103S–110S) CHEST / 116 / 1 / JULY, 1999 SUPPLEMENT
103S