Objective: Suplatast tosilate is an anti-allergic agent that inhibits IgE antibody production. It appears to have an inhibitory effect on the production of Th2 cytokines (interleukin (IL)-4, IL-5) in vitro. In the present study, we investigated the effects of suplatast on eosinophil infiltration and cytokine mRNA expression in bronchoalveolar lavage (BAL) fluid in a Brown Norway (BN) rat model of bronchial asthma.
Methodology: Suplatast (50 mg/kg per day) was administered intraperitoneally for 15 consecutive days to 8-week-old male BN rats that had been actively sensitized to ovalbumin (OA) and alum and rats were challenged with OA aerosol to induce allergic bronchial inflammation. The control group was examined 48 h after antigen inhalation to measure the cell count and cell fraction in BAL fluid. Reverse transcription-polymerase chain reaction using primers for IL-4, IL-5, interferon (IFN)-gamma and beta-actin was used to semiquantitatively measure mRNA expression in BAL cells 24 h after antigen inhalation.
Results: Suplatast was found to decrease the total cell count and the eosinophil count. The mean total cell count in BAL in the suplatast-treated group was 18.8 x 10(5) and the mean eosinophil count was 7.8 x 10(5) compared with 73.0 x 10(5) and 48.9 x 10(5), respectively, in the control group. Suplatast also suppressed expression of IL-4 and IL-5 mRNA in BAL cells. However, there were no significant changes in IFN-gamma expression.
Conclusions: Suplatast was found to have an inhibitory effect on eosinophil infiltration in a rat model of bronchial asthma. It also appeared to inhibit allergic inflammation by altering the cytokine profile.