{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:46:06Z","timestamp":1760150766049,"version":"build-2065373602"},"reference-count":21,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2023,12,15]],"date-time":"2023-12-15T00:00:00Z","timestamp":1702598400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Tsurumi University","award":["#6203"],"award-info":[{"award-number":["#6203"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>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 ACE2 gene was significantly higher in the conjunctiva of smokers (n = 17; median 3.07 copies\/ng of total RNA) than in those of non-smokers (n = 17; median 1.92 copies\/ng of total RNA, p = 0.003). Further, mRNA expression and protein levels of ACE2 were weakly correlated in smokers (r = 0.49). ACE2 protein levels in Schirmer\u2019s strip samples were significantly reduced from 5051 to 3202 pg\/mL after eye washing (n = 10; p = 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.<\/jats:p>","DOI":"10.3390\/ijms242417526","type":"journal-article","created":{"date-parts":[[2023,12,15]],"date-time":"2023-12-15T11:26:52Z","timestamp":1702639612000},"page":"17526","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Eye Washing Downregulated Angiotensin-Converting Enzyme 2 in Conjunctival Tissue Samples from Smokers"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5926-5826","authenticated-orcid":false,"given":"Hiroshi","family":"Fujishima","sequence":"first","affiliation":[{"name":"Department of Ophthalmology, Tsurumi University School of Dental Medicine, Yokohama 230-8501, Japan"},{"name":"Keio Allergy Center, Keio University School of Medicine, Tokyo 160-8582, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7371-6558","authenticated-orcid":false,"given":"Hiroyuki","family":"Yazu","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Tsurumi University School of Dental Medicine, Yokohama 230-8501, Japan"},{"name":"Keio Allergy Center, Keio University School of Medicine, Tokyo 160-8582, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3422-8578","authenticated-orcid":false,"given":"Eisuke","family":"Shimizu","sequence":"additional","affiliation":[{"name":"Keio Allergy Center, Keio University School of Medicine, Tokyo 160-8582, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Naoko","family":"Okada","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Tsurumi University School of Dental Medicine, Yokohama 230-8501, Japan"},{"name":"Department of Pharmaceutical Sciences, Nihon Pharmaceutical Hospital, Saitama 362-0806, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kazumi","family":"Fukagawa","sequence":"additional","affiliation":[{"name":"Keio Allergy Center, Keio University School of Medicine, Tokyo 160-8582, Japan"},{"name":"Ryogoku Eye Clinic, Tokyo 130-0026, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,12,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e00072020","DOI":"10.1590\/0102-311x00072020","article-title":"COVID-19 and smoking: A high-risk association","volume":"36","author":"Silva","year":"2020","journal-title":"Cad. 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