We have studied the effect of salmeterol on both P. aeruginosa interactions with the mucosa of nasal turbinate organ cultures and on pyocyanin-induced (20 microg/ml) and elastase-induced (100 microg/ml) damage to nasal epithelial cells. Organ cultures were exposed to salmeterol either by preincubation with 4 x 10(-7) M salmeterol for 30 min or by pipetting 20 microl of 4 x 10(-7) M salmeterol onto the organ culture surface immediately prior to bacterial inoculation. Infected organ cultures (8 h) had significantly (p < or = 0.01) increased epithelial damage, and P. aeruginosa was predominantly associated with damaged epithelium and mucus. Salmeterol significantly (p < or = 0.02) reduced epithelial damage caused by infection and the total number of adherent bacteria (p < or = 0.05), but bacterial distribution on the mucosa was unchanged. Nasal epithelial cells incubated with pyocyanin (20 microg/ml) or elastase (100 microg/ml) for 3 h had significantly (p < or = 0.05) increased cytoplasmic blebbing and mitochondrial damage versus control values. Elastase also significantly (p < or = 0.05) increased cell projection and reduced the level of ciliation. Cells preincubated with salmeterol (2 x 10(-7) M) showed a significant reduction in some features of cell damage caused by both toxins, which was inhibited by the beta2-adrenoceptor antagonist propranolol. Our results indicate that salmeterol reduces P. aeruginosa-induced damage to both organ culture and nasal epithelium.

Pyocyanin is a blue redox active pigment produced by Pseudomonas aeruginosa. It is present at concentrations of up to 10-4 M in sputa from patients with cystic fibrosis and bronchiectasis who are heavily colonized with this organism. Pyocyanin, at physiologically relevant concentrations, slows human nasal ciliary beat frequency (CBF) in vitro and leads to disruption of the epithelium. Pyocyanin-induced slowing of CBF after 2 h was associated with a significant fall in intracellular cyclic AMP (cAMP) (90%) and ATP (66%) and was reversible after the pyocyanin was removed by washing. These effects were not mediated through interaction with neutrophils. The pyocyanin-induced fall in CBF was not affected by EGTA [ethylene glycol-bis(13-* Corresponding author.

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We examined the effects of 0.25 and 0.5 minimal inhibitory concentrations (MIC) of amoxicillin, loracarbef, and ciprofloxacin on the interaction of a clinical isolate of nontypable Haemophilus influenzae (NTHi) with human adenoid organ culture. Adenoid tissue was embedded in agar so that only the mucosal surface was exposed. Minimum essential medium containing NTHi with or without antibiotics was added to the organ culture and incubated with 5% CO2 at 37 degrees C for 24 h. The organ cultures (n = 6) were assessed for several parameters by light microscopy (LM) and transmission electron microscopy (TEM). Bacterial viable counts after 24 h were not significantly different in all organ cultures. Compared with uninfected controls at 24 h, infection with NTHi caused significant (p < 0.05) damage to epithelium as assessed by LM: reduced ciliary beat frequency (CBF), disruption of epithelium integrity, and reduced number of ciliated sites. TEM showed extrusion of cells from the epithelial surface, loss of cilia from ciliated cells, cytoplasmic blebbing, and mitochondrial damage. In the presence of 0.25 and 0.5 MIC of all three antibiotics, the mucosal damage was significantly less (p < 0.05). We conclude that in the presence of sub-MIC levels of amoxicillin, loracarbef, and ciprofloxacin, NTHi infection causes less functional (CBF) and structural damage.

Patients with airway infection by Pseudomonas aeruginosa have impaired mucociliary clearance. Pyocyanin is a phenazine pigment produced by P. aeruginosa which is present in the sputum of colonized patients, slows human ciliary beat frequency (CBF) in vitro and slows mucociliary transport in vivo in the guinea‐pig. We have investigated the effect of salmeterol, a long‐acting β2‐adrenoceptor agonist, on pyocyanin‐induced slowing of human CBF in vitro. Salmeterol (2 × 10−7 m) was found to reduce pyocycanin (20 μg ml−1)‐induced slowing of CBF by 53% and the fall in intracellular adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) by 26% and ATP by 29%. Another β2‐adrenoceptor agonist, isoprenaline (2 × 10−7 m), also inhibited pyocyanin‐induced slowing of CBF by 39%. The effects of salmeterol (30 min preincubation) persisted after washing the cells. Propranolol (10−7 m) and the β2‐specific antagonist, ICI 118551 (10−6 m) blocked the protective effects of salmeterol completely, but atenolol (10−6 m) was less effective. These results suggested that the effects of salmeterol on pyocyanin‐induced effects were mediated primarily via the stimulation of β2‐adrenoceptors. Pyocyanin‐induced ciliary slowing is associated with a substantial fall in intracellular cyclic AMP and ATP. Salmeterol reversed the effects of pyocyanin on cyclic AMP and ATP. Mucociliary clearance is an important defence mechanism of the airways against bacterial infection. Salmeterol may benefit patients colonized by P. aeruginosa, not only by its bronchodilator action, but also by protecting epithelial cells from pyocyanin‐induced slowing of CBF.