{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T15:43:24Z","timestamp":1790091804990,"version":"4.0.1"},"reference-count":44,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2022,9,23]],"date-time":"2022-09-23T00:00:00Z","timestamp":1663891200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>In patients with SARS-CoV-2, innate immunity is playing a central role, depicted by hyperinflammation and longer lasting inflammatory response. Reliable inflammatory markers that cover both acute and long-lasting COVID-19 monitoring are still lacking. Thus, we investigated one specific inflammatory marker involved as one key player of the immune system, kynurenine (Kyn), and its use for diagnosis\/detection of the Long-\/Post-COVID syndrome in comparison to currently used markers in both serum and saliva samples.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Material and methods<\/jats:title>\n                    <jats:p>The study compromised in total 151 inpatients with a SARS-CoV-2 infection hospitalized between 03\/2020 and 09\/2021. The group NC (normal controls) included blood bank donors (n=302, 144f\/158m, mean age 47.1 \u00b1 18.3 years (range 18-75)). Two further groups were generated based on Group A (n=85, 27f\/58m, mean age 63.1 \u00b1 18.3 years (range 19-90), acute admission to the hospital) and Group B (n=66, 22f\/44m, mean age 66.6 \u00b1 17.6 years (range 17-90), admitted either for weaning or for rehabilitation period due to Long-COVID symptoms\/syndrome). Plasma concentrations of Kyn, C-Reactive Protein (CRP) and interleukin-6 (IL-6) were measured on admission. In Group B we determined Kyn 4 weeks after the negative PCR-test. In a subset of patients (n=11) concentrations of Kyn and CRP were measured in sera and saliva two, three and four months after dismission. We identified 12 patients with Post-COVID symptoms &amp;gt;20 weeks with still significant elevated Kyn-levels.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Mean values for NC used as reference were 2.79 \u00b1 0.61 \u00b5M, range 1.2-4.1 \u00b5M. On admission, patients showed significantly higher concentrations of Kyn compared to NC (p-values &amp;lt; 0.001). Kyn significantly correlated with IL-6 peak-values (r=0.411; p-values &amp;lt;0.001) and CRP (r=0.488, p-values&amp;lt;0.001). Kyn values in Group B (Long-\/Post-COVID) showed still significant higher values (8.77 \u00b1 1.72 \u00b5M, range 5.5-16.6 \u00b5M), whereas CRP values in Group B were in the normal range.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Serum and saliva Kyn are reflecting the acute and long-term pathophysiology of the SARS-CoV-2 disease concerning the innate immune response and thus may serve a useful biomarker for diagnosis and monitoring both Long- and Post-COVID syndrome and its therapy.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2022.1004545","type":"journal-article","created":{"date-parts":[[2022,9,23]],"date-time":"2022-09-23T04:51:31Z","timestamp":1663908691000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":61,"title":["Kynurenine serves as useful biomarker in acute, Long- and Post-COVID-19 diagnostics"],"prefix":"10.3389","volume":"13","author":[{"given":"Daniel Alexander","family":"Bizjak","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manfred","family":"Stangl","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nikolaus","family":"B\u00f6rner","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Florian","family":"B\u00f6sch","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joachim","family":"Durner","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gergana","family":"Drunin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jasmine-Leonike","family":"Buhl","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dietmar","family":"Abendroth","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2022,9,23]]},"reference":[{"key":"B1","volume-title":"Innate alloimmunity. 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