Eye Washing Downregulated Angiotensin-Converting Enzyme 2 in Conjunctival Tissue Samples from Smokers

• Published in: International journal of molecular sciences 2023-12, Vol.24 (24), p.17526
• Main Authors: Fujishima, Hiroshi, Yazu, Hiroyuki, Shimizu, Eisuke, Okada, Naoko, Fukagawa, Kazumi
• Format: Article
• Language: English
• Subjects: angiotensin-converting enzyme 2 (ACE2); Angiotensin-Converting Enzyme 2 - genetics; Angiotensin-Converting Enzyme 2 - metabolism; Conjunctiva - metabolism; COVID-19; COVID-19 - metabolism; COVID-19 - prevention & control; Disease transmission; Electronic cigarettes; Enzymes; Eye - metabolism; eye rinsing; Humans; Infections; Infectious diseases; Nicotine; Prospective Studies; Protein expression; Proteins; Risk factors; RNA - metabolism; SARS-CoV-2 - metabolism; SARS-CoV-2 infection; Severe acute respiratory syndrome coronavirus 2; Smokers; Smoking; Tobacco; transmembrane protease serine 2 (TMPRSS2)
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms242417526

This study aimed to (1) determine whether the expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 is increased in tobacco smokers, which potentially increases their susceptibility to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and (2) assess whether eye rinsing can reduce susceptibility. This prospective study included 20 eyes of 10 smokers and 18 eyes of nine healthy non-smokers (control) for reverse-transcription polymerase chain reaction. This study also included 28 eyes of 14 smokers and 16 eyes of eight healthy non-smokers (control) for enzyme-linked immunosorbent assay. Tear and impression cytology samples were collected from the right eye of each patient. The left eye was then rinsed for 30 s, and after 5 min, the tear and impression cytology samples were collected in the same manner. The expression of the gene was significantly higher in the conjunctiva of smokers ( = 17; median 3.07 copies/ng of total RNA) than in those of non-smokers ( = 17; median 1.92 copies/ng of total RNA, = 0.003). Further, mRNA expression and protein levels of ACE2 were weakly correlated in smokers (r = 0.49). ACE2 protein levels in Schirmer's strip samples were significantly reduced from 5051 to 3202 pg/mL after eye washing ( = 10; = 0.001). Ocular surface cells are susceptible to SARS-CoV-2 infection. Smoking may be a risk factor for SARS-CoV-2 infection, and eye rinsing may reduce the risk of infection.