Context: Cigarette smoke is known to be associated with pulmonary hypertension in humans and in animal models. Although the etiology of pulmonary hypertension in smokers is not understood, recent work has suggested a role for inducible nitric oxide synthase (iNOS) in inducing oxidative stress.Objective and Methods: To further evaluate this question, we assessed eNOS(-/-) mice exposed to air or cigarette smoke for the presence of pulmonary hypertension and examined vascular remodeling and expression of nitrotyrosine, a marker of reactive nitrogen species-induced oxidative damage, using immunohistochemistry. To ascertain whether oxidants may play a role in humans, we also examined lung tissue from nonsmokers, and patients with chronic obstructive pulmonary disease (COPD) with and without pulmonary hypertension.Results: We found that eNOS(-/-) mice developed increased pulmonary arterial pressure after six months cigarette smoke exposure, and this was associated with vascular remodeling and increased vascular nitrotyrosine staining. iNOS gene expression was decreased in the pulmonary arteries of the smoke exposed animals, and no protein was detectable by immunohistochemistry. In humans, vascular nitrotyrosine staining intensity was increased in smokers with COPD compared to nonsmokers, and further increased in smokers with combined COPD and pulmonary hypertension.Conclusions: We conclude that cigarette smoke-induced pulmonary hypertension is associated with evidence of oxidative vascular damage by reactive nitrogen species, but that iNOS does not appear to be the major contributor to such damage. Most likely the source of reactive nitrogen species is the cigarette smoke itself.

N-{[5-(methanesulfonyl)pyridin-2-yl]methyl}-6-methyl-5-(1-methyl-1H-pyrazol-5-yl)-2-oxo-1-[3-(trifluoromethyl)phenyl]-1,2-dihydropyridine-3-carboxamide (AZD9668) is a novel, oral inhibitor of neutrophil elastase (NE), an enzyme implicated in the signs, symptoms, and disease progression in NE-driven respiratory diseases such as bronchiectasis and chronic obstructive pulmonary disease via its role in the inflammatory process, mucus overproduction, and lung tissue damage. In vitro and in vivo experiments were done to evaluate the binding kinetics, potency, and selectivity of AZD9668, its effects in whole-blood and cell-based assays, and its efficacy in models of lung inflammation and damage. In contrast to earlier NE inhibitors, the interaction between AZD9668 and NE was rapidly reversible. AZD9668 was also highly selective for NE over other neutrophil-derived serine proteases. In cell-based assays, AZD9668 inhibited plasma NE activity in zymosan-stimulated whole blood. In isolated human polymorphonuclear cells, AZD9668 inhibited NE activity on the surface of stimulated cells and in the supernatant of primed, stimulated cells. AZD9668 showed good crossover potency to NE from other species. Oral administration of AZD9668 to mice or rats prevented human NE-induced lung injury, measured by lung hemorrhage, and an increase in matrix protein degradation products in bronchoalveolar lavage (BAL) fluid. In an acute smoke model, AZD9668 reduced the inflammatory response to cigarette smoke as indicated by a reduction in BAL neutrophils and interleukin-1β. Finally, AZD9668 prevented airspace enlargement and small airway wall remodeling in guinea pigs in response to chronic tobacco smoke exposure whether dosed therapeutically or prophylactically. In summary, AZD9668 has the potential to reduce lung inflammation and the associated structural and functional changes in human diseases.

The pathogenesis of cigarette smoke-induced pulmonary hypertension is not understood. We have previously shown that smoke rapidly and persistently, but discoordinately, upregulates gene expression of mediators that control vasoconstriction, vasoproliferation, and vasorelaxation in small intrapulmonary arteries. To investigate the possibility that smoke also induces endothelial dysfunction, a finding common to other forms of pulmonary hypertension, we exposed guinea pigs to smoke or air (control) daily for 2 wk and then prepared precision-cut lung slices. After exposure to endothelin-1, a vasoconstrictor, intra-acinar arteries in lung slices derived from smoke-exposed animals constricted more rapidly (greater constriction at a given concentration of endothelin) than did vessels from air-exposed animals. To examine relaxation responses, arteries were constricted with the vasconstrictor U-46619 and then relaxed with progressively increasing doses of acetylcholine. Vessels from smokers had a delayed response to acetylcholine compared with vessels from controls. The NO synthase inhibitor NG-nitro-l-arginine methyl ester reduced relaxation in both control and smoke-exposed arteries, whereas the NO donor sodium nitroprusside increased relaxation of the smoke-exposed arteries, confirming that endothelial dysfunction with decreased effective NO production is present. These findings show that precision cut lung slices can be used to examine the physiological effects of cigarette smoke on intra-acinar pulmonary arteries and indicate that even relatively short-term exposure to smoke produces endothelial dysfunction with a resulting tendency to earlier constriction and later relaxation in cigarette smokers. These changes may be important in the development of pulmonary hypertension.

There has been a resurgence of interest in the pathophysiological mechanisms involved in chronic obstructive pulmonary disease since the early 1990s. The present chapter presents an overview of new information in two important areas in human disease, namely the role of the lymphocyte and exacerbations. The role of the extracellular matrix is much more important, and more complicated, than early work suggested. This is followed by an analysis of new data in both humans and animals. Finally, new information gleaned from animal studies is described and discussed.

Over the last 10 years, there has been a remarkable degree of progress in our understanding of the pathophysiological mechanisms involved in the genesis of emphysema. This review attempts to summarize these data.

Chronic hypersensitivity pneumonitis (HP) is defined as HP with radiological evidence of fibrosis. Pathologically a variety of patterns are seen, including those which resemble usual interstitial pneumonia (UIP), fibrotic nonspecific interstitial pneumonia (NSIP) and peribronchiolar fibrosis. Cases of chronic HP typically show poorly formed granulomas, individual giant cells or Schaumann bodies, which are all crucial clues to the correct diagnosis. Areas of subacute HP (purely cellular infiltrates, usually in a centrilobular pattern) are also frequently present. It is unknown what proportions of chronic HP cases do not show any of these identifying features and, thus, are pathologically indistinguishable from UIP or fibrotic NSIP. Chronic HP has a distinctly worse prognosis than subacute HP, but whether the specific patterns of fibrosis impact on survival is not yet known.

Although small airway remodeling (SAR) leading to airflow obstruction is a common consequence of human cigarette smoking, the airways have been largely ignored in animal models of chronic obstructive pulmonary disease (COPD). We examined lung structure in a guinea pig model of chronic cigarette smoke exposure to ascertain whether smoke induced SAR, and to evaluate how these anatomic lesions correlate with physiologic changes. We used tissue from guinea pigs exposed to cigarette smoke or air for 6 mo. Pulmonary function tests were performed, and histologic sections were prepared. Airspace size (Lm) and changes in the structure of the small airways were evaluated by morphometric analysis. Chronic smoke exposure was associated with increased airway wall thickness and increased amounts of thick collagen fibers in the walls of the small airways, as well as with increased Lm. The increase in thick collagen fibers related negatively to peak expiratory volume (PEF) and the ratio of forced expiratory volume in 1 s to forced ventilatory capacity (FEV0.1/FVC), and positively to airway resistance. Physiologic lung volumes were predicted by airspace size, but residual volume (RV) and total lung capacity (TLC) also were related to airway wall thickness. Amounts of smooth muscle were not changed and did not predict any physiologic abnormalities. We conclude that cigarette smoke exposure results in SAR in the guinea pig, alterations that are reflected in increased airways resistance with diminished airflow and air trapping, mimicking human disease. This model should prove useful in further investigations into the mechanisms of airway remodeling.