Yiying Wanga, Qiangen Wub, Levan Muskhelishvilic, Kelly Davisc, Matthew Bryantb, Xuefei Caoa
a Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, United States of America
b Division of Biochemistry Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, United States of America
c Toxicologic Pathology Associates, Jefferson, AR 72079, United States of America
Unintentional exposure of respiratory mucosal surfaces to DHA aerosols is highly possible during sunless tanning sessions, a possibility for which it is not approved. In this study, the potential respiratory toxicity of DHA using the ALI airway tissue model is evaluated. To mimic in vivo exposure conditions, a liquid aerosol generation and exposure system was used and exposed ALI cultures to a range of non-cytotoxic doses of DHA aerosols at the air-liquid interface.
A B S T R A C T
Dihydroxyacetone (DHA) is an approved color additive used in sunless tanning lotions. Recently, there has been an increased use of DHA in sunless tanning booths in a manner that could result in its inhalation during application. In the present study, we have evaluated the potential for DHA causing toxicity via inhalation using a human air-liquid-interface (ALI) in vitro airway epithelial tissue model. ALI airway models have a close structural and functional resemblance to the in vivo airway epithelium, and thus data generated in these models may have relevance for predicting human responses. To simulate in vivo exposure conditions, we employed a method for liquid aerosol generation that mimics the physical form of inhaled chemicals and used doses of DHA and an exposure frequency reflecting human respiratory exposures during tanning sessions. Compared to the vehicle control, cilia beating frequency (CBF) and MUC5AC secretion were significantly decreased after each exposure. However, time-course studies indicated that both CBF and MUC5AC secretion returned to normal levels within 3 days after the treatment. Matrix metalloproteinase (MMP) release, on the other hand, was decreased 24 h after the first exposure and its level returned to baseline after 5 exposures. No significant morphological changes occurred in the DHA-treated cultures after 5 weekly exposures. Our findings indicate that DHA, at concentrations likely to be experienced by humans, has transient toxic effects on human airway ALI cultures.