Chamaejasmine Isolated from Wikstroemia dolichantha Diels Suppresses 2,4-Dinitrofluoro-benzene-Induced Atopic Dermatitis in SKH-1 Hairless Mice

Abstract

Plants of the genus Wikstroemia have long been used as traditional medicines to treat diseases like pneumonia, rheumatism, and bronchitis. This study was designed to determine the effect of chamaejasmine, a biflavonoid present in W. dolichantha, on atopic dermatitis (AD)-like skin lesions in a 2,4-dinitrochlorobenzene (DNCB)-induced murine model of AD. Initially, we examined the anti-allergic activities of ten flavonoids from W. dolichantha by measuring β-hexosaminidase release from RBL-2H3 cells. Subsequently, an SKH-1 hairless mouse model of AD was developed based on the topical application of DNCB. Chamaejasmine (0.5%) or pimecrolimus (1%, positive control) were applied to dorsal skins of DNCB-sensitized AD mice for two weeks. Serum IL-4 and IgE levels were determined using enzyme-linked immunosorbent assay kits and transepidermal water loss (TEWL) and skin hydration were measured using a Tewameter TM210 and a SKIN-O-MAT, respectively. Of the ten flavonoids isolated from W. dolichantha, chamaejasmine most potently inhibited DNP-specific IgE-induced degranulation in RBL-2H3 cells. Topical administration of chamaejasmine attenuated the clinical symptoms of DNCB-induced dermatitis (i.e., itching, dryness, erythema, and edema). Histological analyses demonstrated that dermal thickness and mast cell infiltration in dermis were significantly reduced by chamaejasmine. In addition, 0.5% chamaejasmine inhibited DNCB-induced increases in total IL-4 and IgE levels in serum, improved skin barrier function, and increased epidermis moisture. Our findings suggest chamaejasmine might be an effective therapeutic agent for the treatment of atopic diseases.

Keywords: 2,4-dinitrochlorobenzene; Wikstroemia dolichantha; atopic dermatitis; chamaejasmine; interleukin 4; skin barrier function.

Figure 1

Anti-allergic effects of Wikstroemia dolichantha total extract (WDE) and fractions (n-hexane, EtOAc, n-BuOH, and water fraction) on β-hexosaminidase release from IgE-mediated RBL-2H3 cells. Results are expressed as the means ± SDs of two independent experiments. ^# p < 0.05 vs. vehicle control; * p < 0.05 vs. IgE + DNP-BSA treated cells. IgE = vehicle control, IgE + BSA = IgE + DNP-BSA treated cells, keto = 30 μM ketotifene.

Figure 2

Structures of the ten flavonoids isolated from Wikstroemia dolichantha 95% ethanol extract. 1: padmatin, 2: aromadendrin, 3: apigenin, 4: wikstaiwanone C, 5: taxifolin, 6: neochamaejasmine B, 7: chamaejasmine, 8: naringenin, 9: afzelechin, 10: catechin.

Figure 3

Anti-allergic effects of the ten flavonoids isolated from W. dolichantha on β-hexosaminidase release from IgE-mediated RBL-2H3 cells. Results are expressed as the means ± SDs of two independent experiments. ^# p < 0.05 vs. vehicle control; * p < 0.05 vs. IgE + DNP-BSA treated cells. IgE = vehicle control, IgE + BSA = IgE + DNP-BSA treated cells, keto = 30 μM ketotifene.

Figure 4

Effects of chamaejasmine on the development of DNCB-induced AD-like skin lesions in SKH-1 hairless mice. (a) Schematic representation of the experiment and (b) clinical features of DNCB-induced AD-like skin symptoms. CON: vehicle control group, DNCB: DNCB-treated control group, DNCB-chamaejasmine: DNCB and 0.5% chamaejasmine-treated group, DNCB-Elidel: DNCB and 1% pimecrolimus cream-treated group.

Figure 4

Effects of chamaejasmine on the development of DNCB-induced AD-like skin lesions in SKH-1 hairless mice. (a) Schematic representation of the experiment and (b) clinical features of DNCB-induced AD-like skin symptoms. CON: vehicle control group, DNCB: DNCB-treated control group, DNCB-chamaejasmine: DNCB and 0.5% chamaejasmine-treated group, DNCB-Elidel: DNCB and 1% pimecrolimus cream-treated group.

Figure 5

Effects of chamaejasmine on histopathological changes, epidermal thicknesses, and mast cell numbers in DNCB-induced AD-like skin lesions in SKH-1 hairless mice. (a) H&E staining, (b) toluidine blue staining, (c) epidermal thicknesses and (d) mast cell numbers. Results are expressed as the means ± SEMs of two independent experiments. ^# P < 0.05 vs. the CON group; * P < 0.05 vs. the DNCB group. CON: vehicle control group, DNCB: DNCB-treated control group, DNCB-chamaejasmine: DNCB and 0.5% chamaejasmine-treated group, DNCB-Elidel: DNCB and 1% pimecrolimus cream-treated group.

Figure 5

Effects of chamaejasmine on histopathological changes, epidermal thicknesses, and mast cell numbers in DNCB-induced AD-like skin lesions in SKH-1 hairless mice. (a) H&E staining, (b) toluidine blue staining, (c) epidermal thicknesses and (d) mast cell numbers. Results are expressed as the means ± SEMs of two independent experiments. ^# P < 0.05 vs. the CON group; * P < 0.05 vs. the DNCB group. CON: vehicle control group, DNCB: DNCB-treated control group, DNCB-chamaejasmine: DNCB and 0.5% chamaejasmine-treated group, DNCB-Elidel: DNCB and 1% pimecrolimus cream-treated group.

Figure 6

Effects of chamaejasmine on serum IgE and IL-4 levels in DNCB-sensitized SKH-1 hairless mice. (a) Serum total IgE levels, (b) serum total IL-4 levels. Serum samples were collected and tested for IgE and IL-4 concentrations on the last day of the experiment (experimental day 21). Results are expressed as the means ± SEMs (n = 7) of two independent experiments. ^# P < 0.05 vs. the CON group; * P < 0.05 vs. the DNCB group. EtOH extract of Wikstroemia dolichantha, CON: vehicle control group, DNCB: DNCB-treated control group, DNCB-chamaejasmine: DNCB and 0.5% chamaejasmine-treated group, DNCB-Elidel: DNCB and 1% pimecrolimus cream-treated group.

Figure 7

Effects of chamaejasmine on skin barrier function in DNCB-sensitized SKH-1 hairless mice. (a) Transepidermal water loss (TEWL) and (b) skin hydration values Results are expressed as the means ± SEMs (n = 7) of two independent experiments. ^# P < 0.05 vs. the CON group; * P < 0.05 vs. the DNCB group. EtOH extract of Wikstroemia dolichantha, CON: vehicle control group, DNCB: DNCB-treated control group, DNCB-chamaejasmine: DNCB and 0.5% chamaejasmine-treated group, DNCB-Elidel: DNCB and 1% pimecrolimus cream-treated group.