Shielding response of rodent skin to water soluble ambient air pollutants

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

“…The dosage of sulphite used in this study resulted in the initiation of epidermal hyperplasia in 10 days; furthermore, the extent of the epidermal hyperplasia was comparable to the protection induced by the more complex and concentrated ambient air pollutants that we explored in our previous study ( Chiu et al., 2020 ). Although epidermal hyperplasia is a key feature for diseases, such as atopic dermatitis and psoriasis, the pathological change of the skin is a manifestation caused by inflammatory stimuli originating from inside the body ( Tamagawa-Mineoka and Katoh, 2020 ).…”

“…After one week of adaptation, freely given standard rat chow (Purina Laboratory Chow obtained from Purina Mills, Inc., St. Louis, MO, USA) and drinking water, animals (n = 5) were shaved and the exposed dorsal skin was cleaned with ddH 2 O and divided into 4 parts (1 cm 2 each) receiving topical application of the followings once daily for 1 and 2 weeks: 100 μL ddH 2 O, 100 μL H 2 SO 3 (0.3 mM), 100 μL perspiration and 100 μL H 2 SO 3 (0.3 mM) followed by 100 μL perspiration ( Figure 1 S for the scheme of treatments). The dosage of sulphite used in this study was relatively equivalent to the one when atmospheric SO 2 was pumped and fully solubilized in 1 L of water for 24 h to mimic a prolonged and repetitive exposure of solubilized environmental SO 2 in our previous study ( Chiu et al., 2020 ). At the end of the experiment, mice were euthanized by carbon-dioxide asphyxiation followed by exsanguination.…”

“…Evidence from our previous study indicated that the skin, as part of its role as a barrier, may undergo increased epidermal hyperplasia when it is exposed to sulphite, and this protection is effective against a more complex and concentrated mixture of air pollutants ( Chiu et al., 2020 ). Taiwan has a hot and humid climate and a large population of people riding motorcycles.…”