Photoprotective and immunoregulatory capacity of ginsenoside Rg1 in chronic ultraviolet B-irradiated BALB/c mouse skin

Abstract

The aim of this study was to investigate the photoprotective and immunoregulatory capacities of ginsenoside Rg1 in skin irradiated by chronic ultraviolet B (UVB) and to verify the potential mechanisms of action. BALB/c mice were pretreated with a topical application of ginsenoside Rg1 and irradiated with different doses of UVB daily for 30 consecutive days. Following chronic UVB irradiation, there were significant pathological changes in the skin of the BALB/c mice, including hyperkeratosis, acanthosis, sponge-like edematization and sunburn occurring in the epidermis, while edema, telangiectasis and inflammatory cell infiltration were observed in the papillary layer of the dermis. Treatment with ginsenoside Rg1 was able to reduce such changes induced by UVB irradiation. The number of p53 protein-positive stained cells following UVB irradiation was also observed by immunohistochemical analysis. Ginsenoside Rg1 downregulated the p53 protein expression induced by UVB irradiation, leading to reductions of 69.50, 23.53 and 12.93% at doses of 30, 60 and 120 mJ/cm2, respectively. Using reverse transcription polymerase chain reaction (RT-PCR), reductions in the levels of interferon (IFN)-γ mRNA expression were detected following UVB exposure; reductions of 19.6, 36.3 and 39.6% were observed following UVB irradiation at doses of 30, 60 and 120 mJ/cm2, respectively. The interleukin (IL)-10 mRNA expression levels increased by 40.1, 71.0 and 89.4% and the tumor necrosis factor (TNF)-α mRNA expression levels increased by 36.4, 18.4 and 8.6% following UVB irradiation at doses of 30, 60 and 120 mJ/cm2, respectively. However, pretreatment with ginsenoside Rg1 was observed to markedly attenuate the UVB irradiation-induced effects on the mRNA expression levels of the three cytokines. The topical application of ginsenoside Rg1 was able to protect the irradiated skin from UVB injury and reduce UVB-induced p53 protein expression. Ginsenoside Rg1 also demonstrated a potential regulatory effect on the UVB-induced local expression of the mRNA of the cytokines IFN-γ, IL-10 and TNF-α, which may be important in its immunoregulatory and inflammatory mechanisms.