Background/Purpose: IgG4-related disease (IgG4-RD) is a systemic disorder characterized by severe fibrosis in lesions. In previous reports, CC-chemokine ligand 18 (CCL18) level is a substantial biomarker for fibrotic diseases such as idiopathic pulmonary fibrosis and systemic sclerosis. However, the possible involvement of CCL18 in fibrotic pathogenesis of IgG4-RD remains unknown. The objective of this study was to investigate association between serum CCL18 levels and clinical and laboratory findings including treatment response in patients with IgG4-RD.

Methods: Twenty-eight consecutive treatment-naïve patients with IgG4-RD and 16 healthy volunteers were enrolled. The patients were diagnosed as IgG4-RD according to the 2011 comprehensive IgG4-RD diagnostic criteria. Disease activity of the patients was assessed based on the IgG4-RD responder index (IgG4-RD RI). Serum concentration of CCL18 was measured by using human CCL18/PARC Quantikine ELISA Kit (R&D Systems Inc., Minneapolis, MN, USA). The correlation between serum CCL18 levels and clinical and laboratory parameters were examined by Spearman correlation coefficient.

Results: The mean age of patients with IgG4-RD was 59.7 years, and the proportion of female was 50% (14/28). The involved organs of the patients were lacrimal gland and orbits (22 cases, 78.6%), salivary gland (19 cases, 67.9%), lymph node (11 cases, 39.3%), lung (7 cases, 25%), pancreas (7 cases, 25%), kidney (5 cases, 17.9%), retroperitoneum (3 cases, 10.7%), aorta (2 cases, 7.1%), skin (2 cases, 7.1%), breast (1 case, 3.6%) and paravertebral mass (1 case, 3.6%). Serum concentration of CCL18 in patients with IgG4-RD (mean 44.7 ng/mL, range 3.6–120.9 ng/mL) was significantly higher than that of healthy volunteers (mean 18.5 ng/mL, range 0.1–63.8 ng/mL; P = 0.01). Of note, serum CCL18 concentrations positively correlated with IgG4-RD RI scores (ρ = 0.54, P < 0.005), number of affected organs (ρ = 0.56, P < 0.005), or serum levels of IgG4 (ρ = 0.50, P < 0.01), but not serum IgE levels (ρ = -0.05, P = 0.79) or blood eosinophil counts (ρ = 0.18, P = 0.38), suggesting that serum CCL18 concentrations reflect IgG4-RD state rather than allergic condition. Moreover, serum CCL18 concentrations significantly decreased after glucocorticoid treatment in patients with IgG4-RD (44.7 ng/mL vs. 12.7 ng/mL, P < 0.01), which were paralleled with disease improvement.

Conclusion: Serum CCL18 concentration is a novel biomarker potentially valuable for evaluating disease activity and treatment response in IgG4-RD. Our results suggest that CCL18 contribute to the fibrotic process in IgG4-RD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/serum-cc-chemokine-ligand-18-level-is-a-potential-biomarker-of-disease-activity-in-igg4-related-disease/