Abstract
OBJECTIVE: To investigate serum CXCL6 as a biomarker at diagnosis and predict progression of interstitial lung disease (ILD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS: Baseline serum CXCL6 levels were measured in 292 AAV patients and 82 healthy controls. Correlations with clinical parameters and disease activity were examined. To assess its role in ILD progression, the association between baseline CXCL6 levels and ILD progression during follow up was evaluated using univariable and multivariable analyses. RESULTS: Serum CXCL6 levels were significantly elevated in AAV patients compared to healthy controls, and were markedly higher in those with ILD than without ILD. The frequency of ILD in AAV patients with high serum CXCL6 levels was significantly higher compared with low levels group (54% vs. 36%, P = 0.002). Serum CXCL6 levels at baseline correlated positively with disease activity of AAV, and acute-phase reactants (ESR and CRP). Among AAV-ILD patients, high serum CXCL6 levels were associated with a significantly higher frequency of ILD progression during follow-up compared to low levels (53.8% vs. 30.0%, P = 0.023). Critically, high baseline CXCL6 level was independently associated with ILD progression in multivariate regression analysis. CONCLUSIONS: This exploratory study suggests that elevated serum CXCL6 levels are associated with greater frequency and disease progression of ILD in AAV patients. Serum CXCL6 may represent a promising serological biomarker for identifying AAV-ILD and monitoring its progression.