Evaluating the comparative MT1B, MT1F, MT1G, and MT1H expression in human pulmonary alveolar epithelial cells treated with polyhexamethylene guanidine-phosphate, chloromethylisothiazolinone/methylisothiazolinone, oligo(2-(2-ethoxy)ethoxyethyl guanidinium chloride, benzalkonium chloride, and sodium dichloroisocyanurate

Background We previously reported the increase in expression of metallothionein1 (MT1) B, MT1F, MT1G, and MT1H after exposure to polyhexamethylene guanidine phosphate (PHMG-p), a humidifier disinfectant, in human pulmonary alveolar epithelial cells (HPAEpiCs). However, to date, no study has reported the comparative expression of MT1B, MT1F, MT1G, and MT1H in pulmonary cells upon exposure to humidifier disinfectants such as 5-Chloro-2-methyl-3(2H)-isothiazolone with 2-methyl-3(2H)-isothiazolone (CMIT/MIT), oligo(2-(2-ethoxy)ethoxyethyl guanidine chloride) (PGH), benzalkonium chloride (BKC), and sodium dichloroisocyanurate (NaDCC). Objective The present study aimed to evaluate the expression of MT1B, MT1F, MT1G, and MT1H in HPAEpiCs treated with PHMG-p, CMIT/MIT, PGH, BKC, and NaDCC. Results Unlike CMIT/MIT, PGH, BKC, and NaDCC, PHMG-p-treated HPAEpiCs showed increased expression of MT1B, MT1F, MT1G, and MT1H. Similarly, exposure to PHMG and PHMG-HCl also induced the expression of MT1B, MT1F, MT1G, and MT1H. Moreover, polyhexamethylene biguanide hydrochloride, a guanidine structure-based chemical, induced the expression of MT1B, MT1F, MT1G, and MT1H. In contrast, polyhexamethylene diisocyanate hydrochloride and guanidine hydrochloride did not induce MT1B, MT1F, MT1G and MT1H. Conclusion The upregulation of MT1B, MT1F, MT1G, and MT1H in HPAEpiCs is a PHMG-p-specific response in pulmonary cells, and is not induced by CMIT/MIT, PGH, BKC, and NaDCC exposure.