Effects of Anti-Asthma Agents on Cytokine and Prostaglandin Production in Ovalbumin-Sensitized Splenocytes

The cytokines which is produced by allergen-specific T helper (Th) cells play a pivotal role in the pathogenesis of asthma. Asthma is caused by exaggerated T-helper 2 (Th2)-based immune responses. It is suggested that controlling such Th2-based response is necessary for asthma therapy. The current therapies for asthma focus primarily on control of symptoms and suppression of inflammation, without affecting the underlying cause. So, we examined that anti-asthmatic drugs might have play a certain role in Th2/Th1 balance. Splenocytes isolated from ovalbumin (OVA)-sensitized mice cultured with anti-asthmatic drugs. It is well known that Th2 and Th1 immune responses can balance one another, as Th2 mediators suppress Th1 responses and Th1 mediators similarly inhibit Th2 responses. But salmeterol inhibits both of Th1 and Th2 mediators, which salmeterol is a suppressor of immune responses not only a suppressor of Th2-based immune responses. Aminophylline is a weak suppressor of immune responses. But ipratropium and cromoglycate don't have any suppressor effect to Th2-driven responses. They only have suppressor effect to Th1 immune responses. Salmeterol, ipratropium, aminophylline, and cromoglycate augmented mRNA levels of CRTH2, EP2, and IP2 receptors in OVA-sensitized splenocytes. It is well known that the up-regulation of CRTH2 - $PGD_2$ receptor - results in restraint of eosinophil recruitment and that the increment of IP and EP2 - $PGI_2$ and $PGE_2$ receptor, respectively - may induce the accumulation of cAMP that decrease the effector function of T cells. Moreover salmeterol and cromoglycate increase the mRNA expression of $PGD_2$ synthase. These findings indicate that anti-asthma agents may alleviate the immunological responses that cause the asthmatic diseases.