Alteration in MUC2 and OCLN Protein Expression in Lung Epithelial Cells After E‐Cigarette Chemical Exposure

Abstract

Electronic cigarettes (e‐cigarettes) have become increasingly popular, especially among young adults, and are marketed as a safer and healthier alternative to traditional tobacco cigarettes (t‐cigarettes). There has not been sufficient time since their introduction into the US market in 2006 for long‐term studies looking at the possible side effects of e‐cigarettes. However, various short‐term studies have pointed to possible health risks. To further investigate these effects, this study looked at the mucus membrane and tight junction disruption in A549 cells by focusing on the alteration of mucin 2 (MUC2) protein and occludin (OCLN) protein expression after exposure to formaldehyde (one chemical in e‐cigarettes). Immunohistochemistry was used to visualize the expression of these proteins. As hypothesized, an alteration in MUC2 and OCLN protein expression was found after exposure to the formaldehyde. For the 12‐hour treatment, a shift in MUC2 expression from nuclear to cytoplasmic and a downregulation of OCLN expression were observed. For the 24‐hour treatment, an upregulation in both MUC2 and OCLN expression around the cell nuclei was observed.