The IgG galactosylation ratio is higher in spondyloarthritis patients and associated with the MRI score.

OBJECTIVES

MRI is an important tool for evaluating inflammation levels and assessing treatment response in patients with ankylosing spondylitis (AS). However, it is expensive and requires experienced physicians. The goal of this study was to identify a biomarker correlated with the MRI score.

METHODS

A total of 558 spondyloarthritis (SpA) patients including 527 AS patients, 10 psoriasis (PsA) patients, and 21 non-radiographic SpA (nr-SpA) patients and 725 controls were enrolled for the studies. Plasma IgG galactosylation (IgG-Gal) level was measured by mass spectrometry. Clinical indexes such as Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and C-reactive protein (CRP) were measured in all AS patients. MRIs and X-rays were obtained from 65 AS patients who were followed up for 6 months.

RESULTS

The IgG-Gal ratio was twice as high in the AS patients compared with the controls. It correlated with inflammation indices which is evaluated by MRI according to SPARCC. (Pearson coefficient/p value was 0.6/7E10-6). In addition, AS patients with a higher IgG-Gal ratio at baseline tended to show greater improvement in inflammation scores by MRI both in 3-month follow-up and 6-month follow-up.

CONCLUSION

The IgG-Gal ratio was significantly increased in AS patients. In clinical care, it may be used as a potential biomarker for diagnosis in the future. Key Points • IgG galactosylation level was abnormal in SpA patients. • IgG galactosylation level was associated with MRI indices.