Depilatory creams increase the number of hair follicles, and dermal fibroblasts expressing interleukin-6, tumor necrosis factor-α, and tumor necrosis factor-ß in mouse skin.

Besides using for hair removal, depilatory agents have been considered to be used as a penetration enhancer for transepidermal drug delivery. To examine the effect in hair follicles (HFs), two commercially available depilatory creams were tested on the dorsal skin of mice to monitor the effect deep into the skin structure. Fifteen male BALB/c mice were used in this study. Depilatory creams were applied to the dorsal skin of the same animal using shaved and untouched treatments as controls to minimize individual differences. Skin samples were collected at three days, one week and two weeks (n = 5 for each) after the treatment, and subjected for hematoxylin-eosin staining, and immunohistochemical analysis for proinflammatory cytokines. The morphological examination showed an increase in the thickness of epidermal layer of the depilatory cream-treated skin at early time points and in the subcutis at two weeks. Depilatory cream promoted entry of anagen phase and increased the number of hair follicles in the subcutis at one and two weeks. Immunohistochemistry showed elevated percentages of dermal fibroblasts expressing interleukin-6, tumor necrosis factor-α, and tumor necrosis factor-ß. Shaving process increased the thickness of epidermis and dermis as depilatory creams did, but did neither induce the expression of proinflammatory cytokines in the dermal fibroblasts nor the number of HFs. The results suggested that the commercially available depilatory creams caused a transient minor inflammatory response of the skin and increased the levels of cytokines that might subsequently affect hair growth.

Shielding response of rodent skin to water soluble ambient air pollutants.

Given the increasing levels of air pollution, understanding the direct shielding response of the skin to air pollutants as a whole under exclusion of the influence from the inside of body is important. We applied topically the water soluble ambient air pollutants to the mouse skin and observed the histological response using 0.3 mM of H2SO3 as a positive control. Water soluble air pollutants samples, WSAP24h and WSA72h, were collected by pumping the outdoor air into ddH2O for 24 and 72 h respectively during two periods with different air quality index (AQI). Morphological examination showed apparent thickening of the epidermal layer in the H2SO3 skin section and in the sections applied with WSAP24h and WSAP72h without significant difference in the extent of epidermal hyperplasia among three groups. The cell viability assay showed no cytotoxic effect by the treatment of H2SO3 and WSAP24h in human skin fibroblast WS-1 cells. WSAP72h sample revealed a dose-dependent cytotoxicity to skin fibroblasts at 48 hr. The evidences indicated that the barrier function of the skin by epidermis hyperplasia could be activated by the insult of a component of air pollution, and the protection could be hold against a more complex and concentrated ambient air pollutants.

Perspiration promotes the effect of sulphite on the shielding response of rodent skin.

Perspiration and environmental chemicals, such as air pollutants, are two of the complicating factors of skin disease. It has not been studied how perspiration affect the skin responding to air pollutants. We applied topically artificial eccrine perspiration, sulphite or both to the mouse skin for one and two weeks to examine the influence of both factors on the shielding ability of healthy skin. Morphological examination showed apparent thickening of the epidermal layer in the skin samples with combined treatment at 1 week, and in the sections applied with sulphite and combined treatment at 2 weeks without significant difference in the extent of epidermal hyperplasia between two groups. The outcomes of immunohistochemical (IHC) analysis showed elevated percentages of dermal fibroblasts expressing interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), tumor necrosis factor ß (TNF-ß) and cyclooxygenase-2 (Cox-2). Results of two-way repeated measured analysis of variance (two-way RMANOVA) showed that both perspiration and sulphite, but not the interaction between them, were significant factors affecting the expression of proinflammatory cytokines. The evidences indicated that perspiration induced cytokines expressions in the dermal fibroblasts and promoted the effect of sulphite on the shielding response of the skin by inducing epidermis hyperplasia.