{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T20:13:30Z","timestamp":1787170410704,"version":"build-2736575974"},"reference-count":300,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2022,6,6]],"date-time":"2022-06-06T00:00:00Z","timestamp":1654473600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomedicines"],"abstract":"<jats:p>Despite intense investigation, the pathogenesis of COVID-19 and the newly defined long COVID-19 syndrome are not fully understood. Increasing evidence has been provided of metabolic alterations characterizing this group of disorders, with particular relevance of an activated tryptophan\/kynurenine pathway as described in this review. Recent histological studies have documented that, in COVID-19 patients, indoleamine 2,3-dioxygenase (IDO) enzymes are differentially expressed in the pulmonary blood vessels, i.e., IDO1 prevails in early\/mild pneumonia and in lung tissues from patients suffering from long COVID-19, whereas IDO2 is predominant in severe\/fatal cases. We hypothesize that IDO1 is necessary for a correct control of the vascular tone of pulmonary vessels, and its deficiency in COVID-19 might be related to the syndrome\u2019s evolution toward vascular dysfunction. The complexity of this scenario is discussed in light of possible therapeutic manipulations of the tryptophan\/kynurenine pathway in COVID-19 and post-acute COVID-19 syndromes.<\/jats:p>","DOI":"10.3390\/biomedicines10061332","type":"journal-article","created":{"date-parts":[[2022,6,6]],"date-time":"2022-06-06T10:08:24Z","timestamp":1654510104000},"page":"1332","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Unbalanced IDO1\/IDO2 Endothelial Expression and Skewed Keynurenine Pathway in the Pathogenesis of COVID-19 and Post-COVID-19 Pneumonia"],"prefix":"10.3390","volume":"10","author":[{"given":"Marco","family":"Chilosi","sequence":"first","affiliation":[{"name":"Department of Pathology, Pederzoli Hospital, 37019 Peschiera del Garda, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4969-5216","authenticated-orcid":false,"given":"Claudio","family":"Doglioni","sequence":"additional","affiliation":[{"name":"Department of Pathology, San Raffaele Scientific Institute, 20132 Milan, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claudia","family":"Ravaglia","sequence":"additional","affiliation":[{"name":"Department of Diseases of the Thorax, Ospedale GB Morgagni, University of Bologna, 47121 Forl\u00ec, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guido","family":"Martignoni","sequence":"additional","affiliation":[{"name":"Department of Pathology, Pederzoli Hospital, 37019 Peschiera del Garda, Italy"},{"name":"Department of Pathology and Diagnostics, University of Verona, 37134 Verona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gian Luca","family":"Salvagno","sequence":"additional","affiliation":[{"name":"Section of Clinical Biochemistry, University of Verona, 37134 Verona, Italy"},{"name":"Service of Laboratory Medicine, Pederzoli Hospital, 37019 Peschiera del Garda, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Giovanni","family":"Pizzolo","sequence":"additional","affiliation":[{"name":"Department of Medicine, Section of Hematology, University of Verona, 37134 Verona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vincenzo","family":"Bronte","sequence":"additional","affiliation":[{"name":"Istituto Oncologico Veneto, IOV-IRCCS, 35100 Padova, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Venerino","family":"Poletti","sequence":"additional","affiliation":[{"name":"Department of Diseases of the Thorax, Ospedale GB Morgagni, University of Bologna, 47121 Forl\u00ec, Italy"},{"name":"Department of Respiratory Diseases and Allergy, Aarhus University Hospital, 8200 Aarhus, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,6,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1016\/S0140-6736(20)30183-5","article-title":"Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China","volume":"395","author":"Huang","year":"2020","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e210830","DOI":"10.1001\/jamanetworkopen.2021.0830","article-title":"Sequelae in Adults at 6 Months after COVID-19 Infection","volume":"4","author":"Logue","year":"2021","journal-title":"JAMA Netw. 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