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Diesel Exhaust
Because short-term increases in particulate air pollution are associated with cardiovascular events and because the intratracheal instillation of diesel exhaust particles are prothrombotic, Nemmar and coworkers
studied the time course of the prothrombotic effect and its relationship to lung inflammation. Instillation of 50 µg of diesel exhaust particles in hamsters induced increases in venous thrombosis of 480% at 1 hour, 770% at 6 hours, and 460% at 24 hours. Levels of neutrophils and histamine were increased at all times in bronchoalveolar lavage. In plasma, histamine was increased at 6 and 24 hours but not at 1 and 3 hours. Pretreatment with a histamine H1–receptor antagonist (diphenhydramine) abolished the influx of neutrophils in bronchoalveolar lavage at all time points. The histamine antagonist did not affect the thrombosis or platelet activation induced by the diesel exhaust particles at 1 hour, but it markedly decreased both actions at 6 and 24 hours. The authors conclude that intratracheal instillation of diesel exhaust particles induces peripheral venous thrombosis that is correlated with pulmonary inflammation at 6 and 24 hours but not at 1 hour (at this point, the prothrombotic action may result from penetration of the particles or associated components into the bloodstream).
Senechal and coworkers
investigated whether diesel exhausts favor type 2 helper T cell (Th2)–associated allergic reactions either by increasing production of Th2-associated chemokines and their associated receptors or by decreasing type 1 helper T cell (Th1)–attracting chemokines and chemokine receptors. Exposure of peripheral blood mononuclear cells from patients with asthma to diesel induced release of I-309; this effect did not occur with allergen exposure. Both diesel and Der p 1 induced early but transient release of monokine induced by interferon- and late release of pulmonary- and activation-regulated chemokine. Both Th1- and Th2-attracting chemokines were induced, but the resulting effect was increased chemotactic activity of Th2 cells and not of Th1 cells. Diesel induced a late increase in the expression of the Th1-associated CXC receptor 3 and CC receptor 5. Upregulation of T cell CXC receptor 3 was not associated with increased migration to its ligands. The authors conclude that diesel, even in the absence of allergen, amplifies Th2 immune response and that it also increases late Th1-associated chemoreceptor expression.
Takano and coworkers
determined whether diesel exhaust particles enhance lung inflammation caused by endotoxin in mice. Instillation of diesel exhaust particles into the trachea of mice synergistically enhanced the lung inflammation caused by endotoxin, which was characterized by neutrophil sequestration, interstitial edema, and alveolar hemorrhage. Given alone, diesel exhaust particles increased the lung expression of Toll-like receptor 4 and nuclear localization of the p50 subunit of nuclear factor- B. In the presence of endotoxin, diesel exhaust particles further activated the nuclear translocation of the p65 subunit of nuclear factor-B in the lung, and increased the lung expression of intercellular adhesion molecule-1, interleukin-1ß, macrophage chemoattractant protein-1, keratinocyte chemoattractant, macrophage inflammatory protein-1 , and Toll-like receptors. The combined exposure to diesel exhaust particles and endotoxin decreased the nuclear localization of CCAAT/enhancer binding protein B. The authors conclude that diesel exhaust particles enhance neutrophilic lung inflammation related to endotoxin and that the enhancement is mediated through the induction of proinflammatory molecules, such as expression of Toll-like receptors and activation of p65-containing dimers of nuclear factor-B.
Citations 1-2 of 2 total displayed.
Pulmonary Inflammation and Thrombogenicity Caused by Diesel Particles in Hamsters: Role of Histamine
- Abderrahim Nemmar, Benoit Nemery, Peter H. M. Hoet, Jos Vermylen, and Marc F. Hoylaerts
Am. J. Respir. Crit. Care Med. 168: 1366 -1372. First published online as doi:10.1164/rccm.200306-801OC
[Abstract]
[Full text]
Effect of Diesel on Chemokines and Chemokine Receptors Involved in Helper T Cell Type 1/Type 2 Recruitment in Patients with Asthma
- Stéphanie Sénéchal, Patricia de Nadai, Natacha Ralainirina, Arnaud Scherpereel, Han Vorng, Philippe Lassalle, André-Bernard Tonnel, Anne Tsicopoulos, and Benoît Wallaert
Am. J. Respir. Crit. Care Med. 168: 215 -221. First published online as doi:10.1164/rccm.200211-1289OC
[Abstract]
[Full text]
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