Goblet-cell hyperplasia is a critical pathological feature in hypersecretory diseases of airways. However, the underlying mechanisms are unknown, and no effective therapy exists. Here we show that stimulation of epidermal growth factor receptors (EGF-R) by its ligands, EGF and transforming growth factor ␣ (TGF␣), causes MUC5AC expression in airway epithelial cells both in in vitro and in vivo. We found that a MUC5AC-inducing epithelial cell line, NCI-H292, expresses EGF-R constitutively; EGF-R gene expression was stimulated further by tumor necrosis factor ␣ (TNF␣). EGF-R ligands increased the expression of MUC5AC at both gene and protein levels, and this effect was potentiated by TNF␣. Selective EGF-R tyrosine kinase inhibitors blocked MUC5AC expression induced by EGF-R ligands. Pathogenfree rats expressed little EGF-R protein in airway epithelial cells; intratracheal instillation of TNF␣ induced EGF-R in airway epithelial cells, and subsequent instillation of EGF-R ligands increased the number of goblet cells, Alcian blueperiodic acid-Schiff staining (ref lecting mucous glycoconjugates), and MUC5AC gene expression, whereas TNF␣, EGF, or TGF␣ alone was without effect. In sensitized rats, three intratracheal instillations of ovalbumin resulted in EGF-R expression and goblet-cell production in airway epithelium. Pretreatment with EGF-R tyrosine kinase inhibitor, BIBX1522, prevented goblet-cell production both in rats stimulated by TNF␣-EGF-R ligands and in an asthma model. These findings suggest potential roles for inhibitors of the EGF-R cascade in hypersecretory diseases of airways.

Neutrophils may play important roles in chronic airway diseases. Pseudomonas is a common pathogen in some chronic airway diseases, and expression of the neutrophil chemoattractant interleukin-8 (IL-8) is induced by Pseudomonas in various cells in vitro. Here we examine the localization of IL-8 mRNA expression after incubating human and dog bronchi with Pseudomonas supernatant in vitro. To examine IL-8 expression in recruited neutrophils, we also superfused the dog bypassed tracheal segment with Pseudomonas supernatant in vivo and measured neutrophil number and IL-8 concentration in luminal fluid; simultaneously, we introduced Pseudomonas supernatant by catheter in a peripheral airway. After 6 h, we analyzed IL-8 mRNA expression and localization in removed tissue. Unincubated bronchi showed no IL-8 mRNA expression, but incubation with Pseudomonas supernatant in vitro resulted in IL-8 mRNA expression in surface epithelial, gland duct, and a subpopulation of serous gland cells. In vivo, introduction of Pseudomonas supernatant into dog trachea and peripheral airways caused IL-8 mRNA expression in epithelial and gland duct cells but also in the recruited neutrophils. Pseudomonas lipopolysaccharide alone was without effect in vitro and in vivo. We conclude that Pseudomonas products, but not lipopolysaccharide, stimulate IL-8 expression in airways and that this expression occurs primarily in surface epithelial and gland duct cells, thus bringing the chemoattractant to the bacterial site. Furthermore, IL-8 expression in recruited neutrophils provides a potential mechanism for positive feedback of this protective antibacterial response.

In patients dying from asthma, extensive mucous plugging occurs in the airways, associated with goblet cell hyperplasia. In this study, we examined the hypothesis that platelet-activating factor (PAF) induces goblet cell hyperplasia and mucin gene expression. After instilling PAF into the airways of guinea pigs and rats, we stained airway goblet cells with Alcian blue/periodic acid-Schiff and determined the number of goblet cells and percentage of stained area within the epithelium. In guinea pigs, one instillation of PAF (10(-)5 M, 100 microl) increased the goblet cell-stained area time-dependently, beginning at 24 h, maximum at 72 h. PAF also caused tracheal recruitment of eosinophils by 24 h, maximum at 48 h. In rats, which have few goblet cells in airways, PAF (3 instillations, 10(-)5 M, 200 microl) caused striking goblet cell hyperplasia, greatest in peripheral airways. Tumor necrosis factor alpha (TNFalpha) alone had no significant effect on goblet cells, but together with PAF, it caused exaggerated goblet cell hyperplasia. In rat tracheas studied by in situ hybridization, PAF induced mucin MUC5 gene expression in epithelial cells that stained for mucosubstances. In summary, PAF induces goblet cell hyperplasia and TNFalpha potentiates this effect.

In this study, we investigated the role of dimethyl sulfoxide (DMSO) in inhibiting interleukin-8 (IL-8)-mediated neutrophil recruitment induced by Pseudomonas aeruginosa (PA) bacterial supernatant. First, we tested whether DMSO could inhibit IL-8 production induced by PA in human bronchial epithelial (16-HBE) cells in vitro. In these cells, exposure to PA or H2O2 induced IL-8 production dose dependently, an effect that was inhibited by 1% DMSO at both the protein and RNA level. Second, we tested whether DMSO could block the recruitment of neutrophils induced by PA in a bypassed segment of dog trachea in vivo. PA supernatant was placed in the tracheal segment for 6 h in four dogs, and neutrophil recruitment and IL-8 concentrations were measured in the superfusate. DMSO prevented the recruitment of neutrophils and IL-8 production induced by PA time dependently. The results suggest that DMSO may play an anti-inflammatory role in the airway by inhibiting IL-8 production in epithelial cells.

Multisource surveillance enhanced our ability to document work-related amputations in Massachusetts. While not feasible to implement for work-related conditions nationwide, it is useful in states. Better understanding of potential biases in SOII is needed.