Effects of korean red ginseng extract for the treatment of atopic dermatitis-like skin lesions in mice

Abstract

Atopic dermatitis (AD) is an allergic, inflammatory skin disease characterized by chronic eczema and mechanical injury to the skin, caused by scratching. Korean red ginseng (RG) has diverse biological activities, but the molecular effects of RG on allergic diseases, like AD, are unclear. The present study was designed to investigate whether RG inhibits 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD in a mouse model. DNCB was applied topically on the dorsal surface of Balb/c mice to induce AD-like skin lesions. We observed the scratching behavior and examined the serum IgE level and interleukin (IL)-4 and IL-10 in splenocytes compared with dexamethasone. We also evaluated the DNCB-induced mitogen-activated protein kinases (MAPKs), NF-κB, and Ikaros activities after RG treatment using reverse transcriptase-polymerase chain reaction, Western blotting, and ELISA. Our data showed that the topical application of RG significantly improved the AD-like skin lesions and scratching behavior. RG decreased not only the mRNA expression of IL-4 and IL-10, but also the secretion of IL-4 protein and serum IgE in mice. Additionally, RG treatment decreased the DNCB-induced MAPKs activity and subsequent Ikaros translocation irrespective of NF-κB. We suggest that RG may be useful as a therapeutic nutrition for the treatment of AD.

Keywords: Atopic dermatitis; Ikaros; Panax ginseng; Red ginseng.

Fig. 1.. Atopic dermatitis (AD)-like skin lesion and improvement of skin condition after treatment with Korean red ginseng (RG). AD-like skin lesion were induced by topical application of 1% 1-chloro-2,4-dinitrobenzene (DNCB) for four times in twice a week, and RG application on the skin lesions improved the skin condition. Dex, dexamethasone.

Fig. 2.. Inhibitory effect of Korean red ginseng (RG) on 1-chloro-2,4-dinitrobenzene (DNCB)-induced scratching behavior. Scratching behavior was observed after completion of all treatments. In brief, the number of scratching behaviors was counted for 10 min. Measurement was repeated for five times (50 min in total). Each bar shows the mean±SEM of three independent experiments. Dex, dexamethasone. ^##p<0.01, significantly different from control group; **p<0.01, significantly different from DNCB-alone.

Fig. 3.. Effect of Korean red ginseng (RG) on level of IgE in serum. After completion of all treatments, blood samples were collected from the inferior vena cava and serum was separated. Level of serum IgE was measured by ELISA. The data are presented as the mean±SEM of a representative experiment of triplicates. Dex, dexamethasone. ^##p<0.01, significantly different from control group; **p<0.01, significantly different from 1-chloro-2,4-dinitrobenzene (DNCB)-alone.

Fig. 4.. Inhibitory effect of Korean red ginseng (RG) on 1-chloro-2,4-dinitrobenzene (DNCB)-induced interleukin (IL)-4 secretion in splenocytes. After completion of all treatments, splenocytes (5×10⁵ cells/well) were incubated for 24 h. Culture supernatants were collected and level of secreted IL-4 was determined using ELISA. The data are presented as the mean±SEM of a representative experiment of triplicates. Dex, dexamethasone. ^##p<0.01, significantly different from control group; **p<0.01, significantly different from DNCB-alone.

Fig. 5.. Suppressive effect of Korean red ginseng (RG) on mRNA expressions of interleukin (IL)-4, IL-10. After completion of all treatments, total RNA was extracted from splenocytes. Reverse transcriptase-polymerase chain reaction analysis was performed to measure mRNA levels of IL-4, IL-10, respectively. The results illustrated are from a single experiment, and are representative of three separate experiments. Dex, dexamethasone. ^##p<0.01, significantly different from control group; **p<0.01, significantly different from 1-chloro-2,4-dinitrobenzene (DNCB)-alone.

Fig. 6.. Effect of Korean red ginseng (RG) on activated mitogen-activated protein kinases (MAPKs) and translocation of Ikaros. (A) Suppressive effect of RG on activated MAPKs. RG were treated to splenocytes with or without 1-chloro-2,4-dinitrobenzene (DNCB). The phosphorylations of MAPKs such as p38, JNK and ERK1/2 were assessed by western blotting described in methods. (B) Suppressive effect of RG on Ikaros translocation. After isolation of cytosolic and nuclear fractions, the translocation of NF-kB (p65), casein kinase 2 (CK2) and Ikaros were assessed by western blotting described in methods respectively. The results illustrated are from a single experiment, and are representative of three separate experiments. ^#p<0.05, significantly different from control group; *p<0.05, significantly different from DNCB-alone.