Characterization of phospholipase A2 activity in rat RPAR-induced pleurisy

Long-acting beta2-agonists: comparative pharmacology and clinical outcomes

Salmeterol and formoterol are both long-acting beta(2)-adrenoceptor agonists (beta(2)-agonists). They both provide excellent bronchodilating and bronchoprotective effects in patients with asthma but their are some differences between these two long-acting beta(2)-agonists in vitro and in vivo. Formoterol has a greater potency and intrinsic activity than salmeterol, which can become especially apparent at higher doses than that clinically recommended, and in contracted bronchi. Long-term use of long-acting beta(2)-agonists can induce tolerance, which can be partially reversed with corticosteroids. Long-acting beta(2)-agonists have some anti-inflammatory effects in vitro, but data in vivo are less convincing. Compared with doubling the dose of inhaled corticosteroids, the addition of inhaled long-acting beta(2)-agonists to inhaled corticosteroids improves symptom control in patients with asthma and reduces both the exacerbation rate of asthma and hospital admission rate. No enhanced airway responsiveness or loss of perception of dyspnea has been observed with the use of inhaled long-acting beta(2)-agonists. Monotherapy with long-acting beta(2)-agonists is not recommended.

Effects of beta2-agonists and budesonide on interleukin-1beta and leukotriene B4 secretion: studies of human monocytes and alveolar macrophages

The aims of the present study were to determine whether beta2-agonists (short- and long-acting) and a glucocorticoid (budesonide) influence the secretion of a pro-inflammatory cytokine (interleukin-1, [IL-1]) and a granulocyte attractant (leukotriene B4 [LTB4]) and to compare these effects on blood monocyte and alveolar macrophages. Alveolar macrophages (obtained by bronchoalveolar lavage) and blood monocytes from 26 healthy nonsmokers were stimulated with lipopolysaccharide or human serum opsonized zymosan. The influence of four beta2-agonists (salbutamol, terbutaline, formoterol, and salmeterol) and a corticosteroid (budesonide) on the release of interleukin-1beta (IL-1beta) and LTB4 was studied in a dose-response manner (10(-8)-10(-5) mol/L for beta2-agonists and 10(-10)-10(-6) mol/ L for budesonide). The stimulated IL-1beta secretion was significantly greater in blood monocytes than in alveolar macrophages (p < 0.05), but alveolar macrophages were much more capable of secreting LTB4 than were blood monocytes (p < 0.001). Budesonide significantly inhibited the release of IL-1beta from blood monocytes (p < 0.001), but no such effect was observed in alveolar macrophages. Budesonide did not influence the release of LTB4 in either cell type. The beta2-agonists neither influenced the LTB4 nor the IL-beta secretion in either cell type with the exception of formoterol, which stimulated IL-1beta secretion at the highest concentration (10(-5) mol/L, p < 0.05). In conclusion, beta2-agonists exhibited only minor effects on IL-1beta secretion from blood monocytes and no effect on LTB4-secretion from either cell type, and budesonide effectively inhibited the IL-1beta release in blood monocytes, but not in alveolar macrophages. Thus, induced secretion of LTB4 and IL-1beta , and the sensitivity to corticosteroids with regard to IL-1beta secretion, change during the transformation from blood monocytes to alveolar macrophages.

Time-course of phospholipase A2, eicosanoid release and cellular accumulation in rat immunological air pouch inflammation

Phospholipase A2 activity in the rat air pouch cavity was determined after induction of a reverse passive Arthus reaction. Time-course of phospholipase A2 activity appeared to correlate with increased prostaglandin E2 levels in inflammatory exudate and with the influx of mononuclear inflammatory cells. Local administration of anti-inflammatory drugs such as dexamethasone, indomethacin, or a PLA2 inhibitor such as p-bromophenacyl bromide significantly inhibited exudate volume, cellular influx, granuloma formation, exudate PGE2 levels and PLA2 activity, to varying degrees. Dexamethasone treatment significantly reduced all parameters determined, whereas p-bromophenacyl bromide had a significant inhibitory effect on PLA2 activity and PGE2 release, and indomethacin only restored PGE2 levels. These results show that PLA2 is neither the only nor the most important factor involved in the development of subchronic inflammation.