biostudies-literatureMistegard CEGraduate School of HEALTH, Aarhus UniversityAase and Ejnar Danielsen FoundationThe Danish National Research Foundation through the Center for Cellular Signal PatternsDanish Rheumatism Associatione004127https://www.ebi.ac.uk/biostudies/studies/S-EPMC11328660biostudies-literatureUnknown10(2)<h4>Objectives</h4>To investigate lectin pathway proteins (LPPs) as biomarkers for axial spondyloarthritis (axSpA) in a cross-sectional cohort with a suspicion of axSpA, comprising newly diagnosed axSpA and chronic low back pain (cLBP) individuals.<h4>Methods</h4>Serum samples from 515 participants within the OptiRef cohort, including 151 axSpA patients and 364 cLBP patients, were measured using immunoassays for LPPs (mannan-binding lectin (MBL), collectin liver-1 (CL-L1), M-ficolin, H-ficolin and L-ficolin, MBL-associated serine proteases (MASP)-1, -2 and -3, MBL-associated proteins (MAp19 and MAp44) and the complement activation product C3dg).<h4>Results</h4>Serum levels of L-ficolin, MASP-2 and C3dg were elevated in axSpA patients, whereas levels of MASP-3 and CL-L1 were decreased, and RMD openExploring complement biomarkers in suspected axial spondyloarthritis.PMC11328660DNRF135A6093 and A6462Mistegard CELoft AGLuders SProft FProtopopov MTroldborg ASpiller LRios Rodriguez VMuche BWeber AKRademacher JThiel SSieper JPoddubnyy DfalseExploring complement biomarkers in suspected axial spondyloarthritis.<h4>Objectives</h4>To investigate lectin pathway proteins (LPPs) as biomarkers for axial spondyloarthritis (axSpA) in a cross-sectional cohort with a suspicion of axSpA, comprising newly diagnosed axSpA and chronic low back pain (cLBP) individuals.<h4>Methods</h4>Serum samples from 515 participants within the OptiRef cohort, including 151 axSpA patients and 364 cLBP patients, were measured using immunoassays for LPPs (mannan-binding lectin (MBL), collectin liver-1 (CL-L1), M-ficolin, H-ficolin and L-ficolin, MBL-associated serine proteases (MASP)-1, -2 and -3, MBL-associated proteins (MAp19 and MAp44) and the complement activation product C3dg).<h4>Results</h4>Serum levels of L-ficolin, MASP-2 and C3dg were elevated in axSpA patients, whereas levels of MASP-3 and CL-L1 were decreased, and 2024-01-01T00:00:00Z2024 May2025-04-19T20:41:35.466Z2025-04-19T20:41:35.466ZS-EPMC113286603874953210.1136/rmdopen-2024-004127