Protective effect of Lycium barbarum leaf extracts on atopic dermatitis: in vitro and in vivo studies

Atopic dermatitis (AD) is a chronic disease with an increasing incidence globally; therefore, there is a growing demand for natural compounds effective in treating dermatitis. In this study, the protective effects of Lycium barbarum leaves with and without chlorophyll (LLE and LLE[Ch-]) on AD were investigated in animal models of AD and HaCaT cells. Further, we investigated whether LLE and LLE(Ch-) show any differences in physiological activity.

AD was induced by 2,4-dinitrochlorobenzene (DNCB) for three weeks, while NC/Nga mice were fed LLE or LLE(Ch-) extracts for 7 weeks. Serum immunoglobulin E (IgE) and cytokine (tumor necrosis factor [TNF]-α, interleukin [IL]-6, and IL-4) concentrations and the degree of DNA fragmentation in lymphocytes were examined. A histopathological examination (haematoxylin & eosin staining and blue spots of toluidine) of the dorsal skin of mice was performed. To elucidate the mechanism of action, the expression of the thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) were measured in HaCaT cells.

Serum IgE and cytokines (TNF-α and IL-6) levels as well as DNA fragmentation of lymphocytes were significantly decreased in AD-induced mice treated with LLE or LLE(Ch-) compared to those of the control group. The epidermal thickness of the dorsal skin and mast cell infiltration in the LLE group significantly reduced compared to that in the control group. The LLE extracts showed no cytotoxicity up to 1,000 µg/mL in HaCaT cells. LLE or LLE(Ch-)-treated group showed a reduction of TARC and MDC in TNF-α-and IFN-γ-stimulated HaCaT cells.

These results suggest that LLE potentially improves inflammation by reducing the expression of chemokines that inhibit T helper 2 cell migration. LLE(Ch-) showed similar effects to LLE on blood levels of IgE, TNF-α and IL-6 and protein expression in HaCat cells, but the ultimate effect of skin improvement was not statistically significant. Therefore, both LLE and LLE(Ch-) can be used as functional materials to alleviate AD, but LLE(Ch-) appears to require more research to improve inflammation.