biostudies-literatureIwasaki-Hozumi HJapan Society for the Promotion of Science3591https://www.ebi.ac.uk/biostudies/studies/S-EPMC9964849biostudies-literatureUnknown24(4)Galectin-9 (Gal-9) is known to contribute to antiviral responses in coronavirus disease 2019 (COVID-19). Increased circulating Gal-9 in COVID-19 is associated with COVID-19 severity. In a while, the linker-peptide of Gal-9 is susceptible to proteolysis that can cause the change or loss of Gal-9 activity. Here, we measured plasma levels of N-cleaved-Gal9, which is Gal9 carbohydrate-recognition domain at the N-terminus (NCRD) with attached truncated linker peptide that differs in length depending on the type of proteases, in COVID-19. We also investigated the time course of plasma N-cleaved-Gal9 levels in severe COVID-19 treated with tocilizumab (TCZ). As a result, we observed an increase in plasma N-cleaved-Gal9 levels in COVID-19 and its higher levels in COVID-19 with pneumonia compared toInternational journal of molecular sciencesPlasma N-Cleaved Galectin-9 Is a Surrogate Marker for Determining the Severity of COVID-19 and Monitoring the Therapeutic Effects of Tocilizumab.PMC9964849JP17H01690Iwasaki-Hozumi HFurushima DAshino YMaeda YMatsuba TChagan-Yasutan HHattori TNiki TBai GfalsePlasma N-Cleaved Galectin-9 Is a Surrogate Marker for Determining the Severity of COVID-19 and Monitoring the Therapeutic Effects of Tocilizumab.Galectin-9 (Gal-9) is known to contribute to antiviral responses in coronavirus disease 2019 (COVID-19). Increased circulating Gal-9 in COVID-19 is associated with COVID-19 severity. In a while, the linker-peptide of Gal-9 is susceptible to proteolysis that can cause the change or loss of Gal-9 activity. Here, we measured plasma levels of N-cleaved-Gal9, which is Gal9 carbohydrate-recognition domain at the N-terminus (NCRD) with attached truncated linker peptide that differs in length depending on the type of proteases, in COVID-19. We also investigated the time course of plasma N-cleaved-Gal9 levels in severe COVID-19 treated with tocilizumab (TCZ). As a result, we observed an increase in plasma N-cleaved-Gal9 levels in COVID-19 and its higher levels in COVID-19 with pneumonia compared to2023-01-01T00:00:00Z2023 Feb2025-04-18T14:21:37.664Z2025-04-07T00:29:45.651ZS-EPMC99648493683500010.3390/ijms24043591