Experimental Study On The Effect Of Chitin On Atopic Dermatitis In Mice

Objective: To investigate the effects of chitin on atopic dermatitis in an OVA induced AD murine model.Methods: Twenty-eight BALB/c mice were randomly divided into three groups: the normal control group(N)(8 mice), the chitin group(E)(10 mice) and the AD model group(M)(10 mice). The murine model of atopic dermatitis was established through intraperitoneal injection of OVA followed by repeated epicutaneous application of OVA on mice back skin(AD model group). During the set up of AD murine model, mice of the chitin group were given intragastric gavage of chitin(3mg/d) for 4 weeks. At the end of the experiment, the mice were sacrificed and skin leisions were biopsied for histological study. HE and O-toluidin stained paraffin sections were observed under microscope. The spleen cells were cultured and challenged with OVA and chitin, respectively, the supernatant was obtained for cytokine determination. Serum levels of total and OVA-specific Ig E and total Ig G2 a were determined with ELISA. The skin m RNA expression of cytokines were determined with RT-PCR. Results: Chitin significantly inhibited skin inflammation induced by OVA. Compared with the AD model group, the thickness of the epidermis and dermis in the chitin group were obviously decreased. The numbers of dermal infiltrated total inflammatory cells, eosinophils and mast cells were significantly decreased in the chitin group compared with the AD model group( P <0.05~0.001). The serum level of total Ig E and OVA-specific Ig E were significantly lower in the chitin group than in the AD model group(P<0.05~0.001), while the serum level of Ig G2 a in the chitin group was significantly higher than that of the AD model group(P<0.001). The cultured spleen cells and lymph node cells of the chitin group produced significantly higher levels of IL-12 and INF-γ, but lower level of IL-4 compared with those of the AD model group after OVA challenge(P<0.05). m RNA expression of Th1-type cytokines were greatly increased in dermatitis skin leisions in chitin group.Conclusion: Chitin can improve the clinical and pathological inflammatory changes of AD skin leisions, as well as decease the seum level of Ig E in the murine AD model. The antiallergic effect of chitin is associated with its regulating effect on Th1/Th2 immune balance shifting towards Th1/Th2 balance toward Th1 direction.