The Effects of Alismatis Rhizoma Extract on Allergic Inflammation in RBL-2H3 Mast Cells and OVA/alum-Sensitized Mice

Objectives Alismatis Rhizoma has been known to suppress inflammation and allergic reaction. However, the cellular target of Alismatis Rhizoma and its mechanism of action remain unclear. This study was designed to examine the effect of Alismatis Rhizoma extract (ALC) on the RBL-2H3 mast cells in vitro and on the OVA/alum sensitized mice ex vivo. Methods In the study, RBL-2H3 mast cells were cultured in minimal essential medium (MEM) for 24 hours, and treated separately with cyclosporin A and varying doses of ALC, and then stimulated with Phorbol 12-myristate 13-acetate (PMA) (50 ng/ml) and Ionomycin ($0.5{\mu}M$). The levels of IL-13, IL-4 were measured by ELISA analysis. The mRNA levels of IL-4, IL-5, IL-6, IL-13, GM-CSF, $TNF-{\alpha}$ were analyzed with Real-time PCR. Also, manifestations of MAPKs transcription factors and $NF-{\kappa}B$ p65 translocation were analyzed by western blotting in vitro. Subsequently, for ex vivo experiment, we induced allergic inflammation on Balb/c mice by OVA/alum and administered ALC orally. And we measured serum OVA-specific IgE level and IL-4, IL-13 in the splenocyte culture supernatant by ELISA analysis. Results ALC was shown to suppress mRNA expression of IL-4, IL-5, IL-6, IL-13, GM-CSF, $TNF-{\alpha}$, and to inhibit the IL-13, IL-4 production. Also ALC reduced an activation of mast cells specific signal MAPKs transcription factors and $NF-{\kappa}B$ p65 from the western blot analysis in in vitro experiment. In ex vivo, ALC oral adminstration decreased the level of OVA-specific IgE in serum, and IL-4, IL-13 in the splenocyte culture supernatant. Conclusions ALC is shown to reduce inflammation and allergic response by suppressing Th2 cytokines through the regulation of transcription factors MAPKs and $NF-{\kappa}B$ p65 in mast cells. Administration of ALC suppressed OVA-specific IgE in ovalbumin allergy model through the inhibition of Th2 cytokine. In conclusion, ALC can be considered as an effective treatment for allergic diseases such as atopic dermatitis.

택사 (澤瀉, Alismatis Rhizoma) 추출물이 RBL-2H3 비만세포와 OVA/alum 감작 생쥐의 알레르기 염증 반응에 미치는 영향