{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T20:01:22Z","timestamp":1768507282392,"version":"3.49.0"},"reference-count":55,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T00:00:00Z","timestamp":1768435200000},"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. Endocrinol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Skeletal muscles secrete myokines, including irisin and myostatin, which regulate inflammation and metabolism and may influence the severity of SARS-CoV-2 infection. This study investigated the associations between serum irisin and myostatin levels and COVID-19 severity.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Ninety-nine adult patients hospitalized with PCR-confirmed COVID-19 were included. Serum irisin and myostatin concentrations were measured by ELISA at admission and discharge. Disease severity was evaluated using a four-point clinical scale, the RALE score for lung involvement, oxygenation indices (PaO\n                      <jats:sub>2<\/jats:sub>\n                      \/FiO\n                      <jats:sub>2<\/jats:sub>\n                      and SaO\n                      <jats:sub>2<\/jats:sub>\n                      \/FiO\n                      <jats:sub>2<\/jats:sub>\n                      ), and inflammatory markers (MMP-9, ferritin, S100B, CRP, D-dimers, NLR, PLR, and SII).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Higher irisin concentrations at admission were associated with more severe clinical condition, increased systemic inflammation, impaired oxygenation, and greater lung involvement. Elevated irisin levels were linked to an increased risk of progression to critical illness, although they were not independent predictors. During hospitalization, irisin levels declined in most patients, in parallel with clinical improvement and reductions in inflammatory markers. Myostatin concentrations at admission correlated with ferritin and D-dimer levels. Higher myostatin levels were associated with severe disease and poorer oxygenation at discharge. Myostatin concentrations remained stable in most patients. Those with declining levels had higher inflammatory markers at baseline but did not differ clinically from others.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>These findings suggest that, through the release of bioactive myokines, skeletal muscles contribute to the regulation of systemic inflammation and oxygenation, thereby influencing the clinical course of SARSCoV-2 infection. Elevated irisin reflects heightened inflammation, severe hypoxemia, and extensive lung involvement, whereas increased myostatin is associated with severe inflammation and critical illness.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fendo.2025.1668035","type":"journal-article","created":{"date-parts":[[2026,1,15]],"date-time":"2026-01-15T05:16:21Z","timestamp":1768454181000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Association of circulating muscle-derived myokines irisin and myostatin with COVID-19 severity"],"prefix":"10.3389","volume":"16","author":[{"given":"Cyryl","family":"Daroszewski","sequence":"first","affiliation":[{"name":"Department of Pulmonology and Lung Cancers, Wroc\u0142aw Medical University","place":["Wroc\u0142aw, Poland"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J\u0119drzej","family":"Grzegrz\u00f3\u0142ka","sequence":"additional","affiliation":[{"name":"Department of Histology and Cytophysiology, Wroc\u0142aw Medical University","place":["Wroc\u0142aw, Poland"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Monika","family":"Kosacka","sequence":"additional","affiliation":[{"name":"Department of Pulmonology and Lung Cancers, Wroc\u0142aw Medical University","place":["Wroc\u0142aw, Poland"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anna","family":"Brzecka-Bonnaud","sequence":"additional","affiliation":[{"name":"Department of Pulmonology and Lung Cancers, Wroc\u0142aw Medical University","place":["Wroc\u0142aw, Poland"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,1,15]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"2639","DOI":"10.3390\/ijms22052639","article-title":"Adipokines, myokines, and hepatokines: crosstalk and metabolic repercussions","volume":"22","author":"de Oliveira Dos Santos","year":"2021","journal-title":"Int J Mol Sci"},{"key":"B2","doi-asserted-by":"publisher","first-page":"6278","DOI":"10.3390\/ijms22126278","article-title":"Movement as a positive modulator of aging","volume":"22","author":"Bi\u010d\u00edkov\u00e1","year":"2021","journal-title":"Int J Mol Sci"},{"key":"B3","doi-asserted-by":"publisher","first-page":"795","DOI":"10.1007\/s41999-022-00635-3","article-title":"The relationship between sarcopenia detected in newly diagnosed colorectal cancer patients and FGF21, irisin and CRP levels","volume":"13","author":"Oflazoglu","year":"2022","journal-title":"Eur Geriatr Med"},{"key":"B4","doi-asserted-by":"publisher","first-page":"1327332","DOI":"10.1155\/2022\/1327332","article-title":"Association between sarcopenia and insulin-like growth factor-1, myostatin, and insulin resistance in elderly patients undergoing hemodialysis","volume":"2022","author":"Widajanti","year":"2022","journal-title":"J Aging Res"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1055\/a-1500-4605","article-title":"Association of serum myostatin with body weight, visceral fat volume, and high sensitivity C-reactive protein but not with muscle mass and physical fitness in premenopausal women","volume":"130","author":"Kern-Matschilles","year":"2022","journal-title":"Exp Clin Endocrinol Diabetes Off J Ger Soc Endocrinol Ger Diabetes Assoc"},{"key":"B6","article-title":"Molecular mechanism of -acute sarcopenia in elderly patient with COVID - 19","volume":"53","author":"Aryana","year":"2021","journal-title":"Acta Med Indones"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1016\/j.lfs.2017.03.011","article-title":"Irisin acts as a regulator of macrophages host defense","volume":"176","author":"Mazur-Bialy","year":"2017","journal-title":"Life Sci"},{"key":"B8","doi-asserted-by":"publisher","first-page":"598","DOI":"10.1016\/j.bbrc.2016.12.084","article-title":"Irisin suppresses the migration, proliferation, and invasion of lung cancer cells via inhibition of epithelial-to-mesenchymal transition","volume":"485","author":"Shao","year":"2017","journal-title":"Biochem Biophys Res Commun"},{"key":"B9","doi-asserted-by":"publisher","DOI":"10.26402\/jpp.2018.1.13","article-title":"Myokine irisin-induced protection against oxidative stress in vitro. 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