Inhibition of interleukin 5 production with no influence on interleukin 4 production by an anti-allergic drug, tranilast, in Toxocara canis-infected mice

Abstract

Tranilast is well-known as a useful drug for allergic diseases. This drug is believed to exhibit its therapeutic effects by inhibiting the release of chemical mediators from mast cells and basophils. Effects of tranilast on T helper type 2 (Th2) cytokine production were investigated in mice infected with Toxocara canis (Tc). Tranilast reduced interleukin (IL)-5 production in a dose-dependent manner but not IL-4 production at all in lung and spleen cells from Tc-infected mice cultured under stimulation with excretory–secretory antigen. Obvious IL-5 mRNA expression was observed at week 1 in the lung alone, and IL-4 mRNA expression was detected at similar levels at weeks 1–6 of infection in both lung and spleen. IL-5 but not IL-4 mRNA expression in the lung was significantly inhibited by daily administration of 100 mg/kg of tranilast for 1 week. This treatment also reduced the serum IL-5 level. Thus, tranilast inhibited IL-5 but not IL-4 production either in vitro or in vivo. The results imply that IL-5 and IL-4 production by Th2 cells may be controlled through different mechanisms.