Abstract
Purpose :
Cosmetics such as mascara, eye shadow and eyeliner are used extensively to highlight the eyes, and typically contain preservatives to prevent microbial growth. These preservatives include benzalkonium chloride (BAK) and formaldehyde (FA)-releasing compounds, such as quaternium 15, hydantoin, imidazolidinyl urea, diazolidinyl urea and 2-bromo-2-nitropropane-l,3-diol. We hypothesize that these preservatives, at concentrations (BAK = 1 mg/ml; FA = 0.74 mg/ml) approved for consumer use, are toxic to human ocular surface and adnexal cells. Accordingly, we tested the influence of BAK and FA on the morphology, proliferation and signaling ability of immortalized human meibomian gland (iHMGECs), corneal (iHCECs) and conjunctival (iHConjECs) epithelial cells.
Methods :
iHMGECs, iHCECs and iHConjECs were cultured with different concentrations of BAK (5 µg/ml to 0.005 µg/ml) or FA (1mg/ml to 1 µg/ml) under proliferating (keratinocyte serum-free medium, with or without epidermal growth factor and bovine pituitary extract), or differentiating (DMEM/F12 plus 10% fetal bovine serum) conditions for up to 7 days. We used low BAK levels, because we found that 0.5 mg/ml and 50 µg/ml BAK killed iHMGECs after 15 minutes exposure. Experimental procedures included analyses of cell appearance, cell number and Akt signaling in all 3 cell types.
Results :
Our results demonstrate that BAK and FA cause dose-dependent changes in the morphology, proliferation and Akt signaling of iHMGECs, iHCECs and iHConjECs. Many of the concentrations tested induced cell atrophy, poor adherence and death, as well as decreased proliferation, after 5 days of exposure. Cellular signaling, as indicated the levels of p-Akt after 15 (FA) or 30 (BAK) minutes of treatment, was also reduced in a dose-dependent fashion in all 3 cell types, irrespective of whether cells had been cultured under proliferating or differentiating conditions.
Conclusions :
Our results support our hypothesis and demonstrate that the cosmetic preservatives, BAK and FA, exert many toxic effects on cells of the ocular surface and adnexa.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.