Effect of salmeterol on human nasal epithelial cell ciliary beating: inhibition of the ciliotoxin, pyocyanin

Abstract

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.

The biology of bacterial colonization and invasion of the respiratory mucosa

“…The long-acting β 2 -agonist salmeterol raises the level of cAMP in epithelial cells [48], and partially inhibits the action of pyocyanin in vitro [49]. Therefore, salmeterol may benefit patients colonized by P. aeruginosa not only by its bronchodilating action but also by protecting cilia from the cAMPdependent effects of pyocyanin.…”

Effect of salmeterol on Haemophilus influenzae infection of respiratory mucosa in vitro

“…Maintenance of ciliary beating of infected organ cultures in the presence of salmeterol could protect the epithelium against H. influenzae-induced damage by reducing the concentration of toxins in the microenvironment of the mucosal surface. However, the concentration of salmeterol (4×10 -7 M) used in these experiments has previously been shown not to affect ciliary beat frequency of epithelial cell monolayers [13] or nasal epithelial cells [17]. Salmeterol also increases intracellular cAMP [13].…”

“…We have previously shown that P. aeruginosa and its toxins pyocyanin and elastase damage human epithelial cells and that this damage is reduced by salmeterol [16]. Pyocyanin is a toxin whose effect is mediated via cAMP and we have previously shown that salmeterol attenuates pyocyanin-induced decreases in intracellular cAMP [17]. However, salmeterol also protected human nasal epithelial cells against P. aeruginosa elastase-induced damage, where the activity of the enzyme is not mediated via cAMP [16].…”

“…We have recently shown that salmeterol (4×10 -7 M) reduced the damage that occurred to respiratory epithelium during Pseudomonas aeruginosa infection of nasal turbinate organ cultures, and decreased ultrastructural damage to epithelial cells caused by the P. aeruginosa toxins pyocyanin and elastase [16]. In separate experiments [17,18] it was observed, using light microscopy, that the disruption of epithelial integrity caused by pyocyanin was delayed in the presence of salmeterol (2×10 -7 M) and other agents that increased intracellular cyclic adenosine monophosphate (cAMP). Selective antagonists were used to demonstrate that salmeterol reduced epithelial damage via stimulation of β 2 -adrenoceptors.…”

Non Invasive Delivery of Protein and Peptide Drugs: A Review

“…Antihistaminic drugs, beta blockers, general anesthetics, cocaine, etc., arrest the mucociliary clearance. Thus, NMC reduces the nasal bioavailability of drugs [21][22][23][24][25][26][27][28][29]. Various approaches for nasal delivery have been given in Table 3.…”