Cigarette smoking, the major cause of pulmonary emphysema, is characterized by destruction of alveolar walls. Because tissue destruction represents a balance between injury and repair, we hypothesized that cigarette smoke exposure may contribute to the development of emphysema through the inhibition of tissue contraction during the repair process. To partially evaluate this hypothesis, we investigated the effects of cigarette smoke extract (CSE) on the ability of cultured fibroblasts to mediate collagen gel contraction in vitro: CSE inhibited fibroblast-mediated gel contraction in a concentration-dependent manner ( P < 0.01). Production of prostaglandin E2, a known inhibitor of fibroblast contraction, was unchanged by CSE as was cell surface integrin expression. In contrast, fibronectin production by fibroblasts was inhibited ( P < 0.01), and addition of exogenous fibronectin partially restored the contractile activity, thus suggesting at least one mechanism to explain inhibition of gel contraction by CSE. When CSE was treated to remove volatile components, it showed less inhibitory activity on fibroblast-mediated gel contraction. Therefore, we also examined the effects of acrolein and acetaldehyde, two volatile components of cigarette smoke. Inhibition of contraction was observed at 5 μM acrolein and at 0.5 mM acetaldehyde. In conclusion, cigarette smoke inhibited fibroblast-mediated gel contraction, and this inhibition was due, at least in part, to the volatile components of cigarette smoke and may be mediated, at least in part, by a decrease in fibroblast fibronectin production. By inhibition of repair, these smoke components may contribute to the development of pulmonary emphysema.

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In vivo, fibroblasts are distributed in a three-dimensional (3-D) connective tissue matrix. Fibronectin is a major product of fibroblasts in routine cell culture and is thought to regulate many aspects of fibroblast biology. In this context, we sought to determine if the interaction of fibroblasts with a 3-D matrix might affect fibronectin production. To examine this hypothesis, fibronectin production by fibroblasts cultured in a 3-D collagen gel or on plastic dishes was measured by ELISA. Fibroblasts in 3-D gel culture produced more fibronectin than those in monolayer culture. Fibroblasts in 3-D culture produced increasing amounts of fibronectin when the collagen concentration of the gel was increased. The 3-D nature of the matrix appeared to be crucial because plating the fibroblasts on the surface of a plastic dish underneath a collagen gel was not different from plating them on a plastic dish in the absence of collagen. In addition to increased fibronectin production, the distribution of the fibronectin produced in 3-D culture was different from that of monolayer culture. In monolayer culture, more than half of the fibronectin was released into the culture medium. In 3-D culture, however, approximately two-thirds remained in the collagen gel. In summary, the presence of a 3-D collagen matrix increases fibroblast fibronectin production and results in greater retention of fibronectin in the vicinity of the producing cells.

Glucocorticoids are currently regarded as the drug of choice in the treatment of inflammatory airway and lung diseases, however, they are not routinely effective in fibrotic phases of inflammation. In the current study, glucocorticoids were investigated for their ability to affect fibroblast mediated contraction of a three dimensional collagen gel, a measure of one aspect of tissue remodeling. Dexamethasone, budesonide, hydrocortisone and fluticasone propionate were all able to significantly augment fibroblast contractility in a concentration dependent manner. Glucocorticoids also had an augmentative effect on collagen gel contraction mediated by fibroblasts from bronchi, skin and bone marrow. The increased contractility was not due to cell proliferation or to collagen degradation, since the glucocorticoids did not alter the amounts of DNA and hydroxyproline in the gels. The concentration of prostaglandin E2 (PGE2) in supernatant media was lower from glucocorticoid-treated gels compared to control gels. Consistent with this, addition of exogenous PGE2 to the culture system restored the contractile properties and indomethacin augmented contraction similar to the glucocorticoids suggesting that inhibition of prostaglandins or related eicosanoids may be the mechanism by which the increased contractility occurs. DBcAMP, forskolin and the long lasting beta2-agonist formoterol were able to reverse the effect of the glucocorticoids on fibroblast mediated collagen gel contraction suggesting that enhancers of cAMP can counteract the effect of glucocorticoids. Thus, we provide evidence that glucocorticoids have the ability to directly augment fibroblast contractility by inhibiting fibroblast endogenous PGE synthesis. The findings could be one possible mechanism to explain the poor therapeutic response to glucocorticoids on the later stages of fibrotic diseases.

From May 1990 to August 1991, 36 patients admitted to the Department of Internal Medicine in a medical school hospital with hematological malignancies or solid tumors, developed respiratory tract colonization with Pseudomonas cepacia. Sixteen (44.4%) of these patients developed pneumonia, and four (11.1%) died of respiratory failure due to P. cepacia pneumonia. Extensive survey of the hospital environment as well as equipment showed that nebulizer devices used by the patients for inhalation were contaminated with P. cepacia. Phenotypic characteristics, (production of hemolysin and extracelluler enzymes [lipase, lecithinase and protease]), the Analytical Profile Index 20 NE pattern, and the pattern of DNA fingerprinting by pulse-field gel electrophoresis in clinically isolated strains and strains derived from nebulizer devices were compared. The strains of P. cepacia obtained from patients in the Department of Internal Medicine were indistinguishable from each other and also from those isolated from nebulizer devices, but were different from those isolated from patients in other departments at the same time. These results demonstrated that the outbreak of P. cepacia respiratory colonization in immunocompromised patients was a nosocomial acquisition, and probably occurred by transmission through contaminated nebulizer devices.