Effects of Photocatalytic Agent on DS-<i>Nh</i> Mice, Developing Atopic Dermatitis-Like Eruption with an Increase of <i>Staphylococcus aureus</i>

Abstract

Background:Staphylococcus aureus(S. aureus) is thought to play a significant role in the exacerbation of atopic dermatitis (AD). DS-Nh mice, a non-hair-bearing mouse model of AD, spontaneously develop dermatitis under conventional conditions. A remarkable increase in S. aureus is considered to strongly relate to the induction and aggravation of this dermatitis. A topical use of anatase-type titanium dioxide (TiO₂) followed by UV irradiation, acting as photocatalyst, is believed to have antibacterial activity. We investigated the bactericidal effect of TiO₂ with UV irradiation on DS-Nh mice to prevent the aggravation of the dermatitis. Methods: Ten-week-old DS-Nh mice were treated with TiO₂ in petrolatum on the back, followed by UVA irradiation, for 11 weeks. The severity of dermatitis was assessed by evaluating individual lesions using a 4-grade scale and expressed as the total skin score. S. aureus colonizing the mouse skin was counted after isolation and incubation with agar medium. The skin barrier dysfunction was evaluated by measuring transepidermal water loss (TEWL). Results:The mice treated with TiO₂ and UV irradiation showed a significant increase in total skin scores, the number of S. aureus and TEWL values, compared with non-treated mice. In contrast, these parameters were significantly lower in the mice treated with petrolatum and UV irradiation. Conclusions: A significant increase in S. aureus was recognized on the skin together with the aggravation of AD-like dermatitis in our mice model. Skin barrier dysfunction induced by TiO₂ and UV irradiation seems to facilitate the increase in S. aureus.

Nano-titanium dioxide modulates the dermal sensitization potency of DNCB

“…For example, a sub-erythemal dose ultraviolet radiation exposure (UVB 270 mJ/cm 2 ) in mice has been shown to allow the penetration of 45 nm quantum dot NPs to deep dermis [27]. In another study, it has been observed that 7 nm TiO 2 NP exposure with UV irradiation can lead to increased skin barrier dysfunction and possible aggravation of contact dermatitis due to increased invasion of Staphylococcus aureus [28]. Interestingly, people tend to apply more sun screens containing NPs in case they have damaged skin (sunburns, burns) when the barrier function of skin is already impaired.…”

Titanium Dioxide Nanoparticles Aggravate Atopic Dermatitis-Like Skin Lesions in NC/Nga Mice

“…On the other hand, once TiO 2 nanoparticles penetrate into the skin, they can affect the cutaneous function. Kambara et al reported that anatasetyped TiO 2 nanoparticles can accelerate skin barrier dysfunction/defect induced by UV irradiation in mice (32). Additionally, fluoresceinated quantum dots following intradermal injection (15-20 nm) have been shown to migrate to local lymph nodes in mice and pigs (43).…”

Expression of IL-22 in the Skin Causes Th2-Biased Immunity, Epidermal Barrier Dysfunction, and Pruritus via Stimulating Epithelial Th2 Cytokines and the GRP Pathway

“…Then the plates were incubated at 37°C for 24 hrs. After incubation, the number of colonies was counted and identification of the bacteria was done according to the manufacturer’s instructions (20). Serum samples for SEB-specific IgE were measured using ELISA Plates coated with SEB (1 μg/ml, Toxin Technology, Inc.) in 0.1 M carbonate-bicarbonate buffer (pH 9.5) overnight at 4°C, as described previously (21).…”