“This current study illustrates the potential of serological metabolites of tissue destruction as novel disease activity biomarkers in axSpA,” wrote Markéta Hušáková, PhD, of the Institute of Rheumatology and Department of Rheumatology at First Faculty of Medicine Charles University in Prague and coauthors. The study was published in Scientific Reports.
To determine if certain collagen metabolites could indicate axSpA disease activity and distinguish nonradiographic axial spondyloarthritis (nr-axSpA) from ankylosing spondylitis (AS), the researchers examined 193 recently diagnosed axSpA patients and 100 asymptomatic controls. Of the 193 patients, 121 had nr-axSpA and 72 had AS.
The researchers found that four collagen metabolites occurred at significantly higher serum levels in both subtypes of axSpA patients, compared with controls: for C1M, a mean of 43.4 ng/mL for AS and 34.6 ng/mL for nr-axSpA versus 24.5 ng/mL for controls; for C2M, 0.35 and 0.36 versus 0.26; for C3M, 15.4 and 12.8 versus 7.8; and for C4M2, 27.8 and 22.4 versus 15.2. Mean serum levels of C1M, C3M, and C4M2 were significantly higher in AS patients when compared with nr-axSpA patients. Of the four collagen metabolites, C3M was the best for differentiating between axSpA patients and asymptomatic controls (area under receiver operator characteristics curve, 0.95; specificity, 92.0; sensitivity, 83.4) and between nr-axSpA patients and controls (AUC, 0.93; specificity, 80.0; sensitivity, 92.6) and AS patients (AUC, 0.98; specificity, 92.0; sensitivity, 91.7).
The authors acknowledged their study’s limitations, including the inability to investigate changes in biomarker levels and disease activity over time. In addition, there was a lack of clinical information about cardiovascular or other systemic complications, as well as no clinical or radiographic examination of the asymptomatic individuals, which could have revealed factors influencing their metabolite levels.
Two of the authors acknowledged being employees of fibrosis biomarker developer Nordic Bioscience; another researcher acknowledged being a stockholder. No additional conflicts of interest were reported.
SOURCE: Hušáková M et al. Sci Rep. 2019 Aug 2. doi: 10.1038/s41598-019-47502-z.