{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T17:42:33Z","timestamp":1792604553416,"version":"4.5.0"},"reference-count":31,"publisher":"Public Library of Science (PLoS)","issue":"10","license":[{"start":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T00:00:00Z","timestamp":1792540800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec001\">\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Long COVID is a complex pathophysiological condition linked to a heterogenous symptom profile. Dysregulation of 1) immunological and inflammatory responses, 2) endothelial\/vascular function, and 3) metabolic and clotting processes have been identified; however, there remains a lack of clinically validated diagnostic biomarkers. The study aim was to investigate dysregulation of cytokines, chemokines and growth factors in confirmed Long COVID cases grouped by disease severity.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec002\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>One-hundred-and-twenty-seven participants provided venous blood samples for cytokine profiling utilising Luminex assays. Participants were grouped into those with no knowledge of SARS-CoV-2 infection (n\u2009=\u200921), acute infection within 3-months (n\u2009=\u200922), spontaneous resolvers (&gt;3-months, n\u2009=\u200921) and those with confirmed Long COVID (n\u2009=\u200963). Long COVID severity was grouped according to the post-COVID-19 functional status (PCFS) and defined as those with negligible (4A; n\u2009=\u20099), mild (4B; n\u2009=\u200920), moderate (4C; n\u2009=\u200924), and severe limitations (4D; n\u2009=\u200910). Cytokines were assessed for normality using Shapiro-Wilk tests and differences measured between groups using Kruskal-Wallis tests. Pairwise correlation and principal component analysis were performed.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec003\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Interleukin-12 (p40\/p70) was 22% greater in the Long COVID group (Median [IQR]: 58 [49] pg\/mL, p\u2009=\u20090.046) and 30% greater in the acutely infected group (64 [36] pg\/mL; p\u2009=\u20090.039) against non-infected controls (45 [25] pg\/mL). Following PCFS classification, fibroblast growth factor-basic was 25% lower in Long COVID 4B versus spontaneous resolvers (24 [7] vs. 32 [24] pg\/mL; p\u2009=\u20090.025). Pairwise correlation differences demonstrated that three Long COVID subgroups had strong, positive associations between cytokines when compared to non-infected controls; however, PCA was unable to determine any coordinated cytokine variation that was group specific.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec004\">\n                    <jats:title>Discussion and conclusions<\/jats:title>\n                    <jats:p>Elevated interleukin-12 (p40\/p70) and reduced basic fibroblast growth factor suggest persistent immune activation and possible subgroup-specific Long COVID; however, these findings were marginally significant and exploratory. A coordinated but partial immunological\/inflammatory profile may exist in some of those with Long COVID, suggesting a rationale for subgrouping upon a biological, rather than self-report basis but larger longitudinal studies are required to confirm this hypothesis.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pone.0360525","type":"journal-article","created":{"date-parts":[[2026,10,21]],"date-time":"2026-10-21T17:27:07Z","timestamp":1792603627000},"page":"e0360525","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Blood biomarkers of long COVID: A cross-sectional evaluation of key cytokines and the coordination of inflammation"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8608-8231","authenticated-orcid":true,"given":"Callum","family":"Thomas","sequence":"first","affiliation":[{"name":"University of Derby","place":["Derby, United 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Humanities"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Corinna","family":"Chidley","sequence":"additional","affiliation":[{"name":"University of Derby","place":["Derby, United Kingdom"],"department":["School of Health, Sport and Rehabilitation, College of Health and Humanities"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8163-7032","authenticated-orcid":true,"given":"Mark A.","family":"Faghy","sequence":"additional","affiliation":[{"name":"Loughborough University","place":["Loughborough, United Kingdom"],"department":["School of Sport, Exercise and Health Sciences"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,10,21]]},"reference":[{"issue":"18","key":"pone.0360525.ref001","doi-asserted-by":"crossref","first-page":"1746","DOI":"10.1056\/NEJMsb2408466","article-title":"Long covid defined","volume":"391","author":"EW 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