Soluble triggering receptor expressed on myeloid cell-1 reflects the cross-sectional activity of microscopic polyangiitis and granulomatosis with polyangiitis.

Objectives: We investigated whether soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) reflects cross-sectional activity of microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA). Methods: Forty-seven MPA and 32 GPA patients with well-documented clinical records and stored sera were enrolled. sTREM-1 levels were evaluated using Magnetic Luminex® assay, and disease activity was assessed using Birmingham vasculitis activity score (BVAS). Patients were divided into two groups according to the upper and lower halves of BVAS. Receiver operator characteristic (ROC) curve analysis was used to identify cut-off for determining upper half of BVAS. Linear and binary logistic regression was performed to evaluate the association between sTREM-1 and disease activity and status. Results: The median age of patients was 67.0 years, and 58.2 % were women. The median BVAS and sTREM-1 were 12.0 and 467.1 pg/mL. sTREM-1 was significantly correlated with BVAS along with five-factor score, Short-Form 36-Item Health Surveys, and C-reactive protein. In multivariable linear regression analysis, erythrocyte sedimentation rate (standardised β 0.241), and sTREM-1 (standardised β 0.288) were correlated with BVAS. ROC analysis revealed that the cut-off of sTREM-1 for the upper half of BVAS was 474.1 pg/mL. MPA and GPA patients with sTREM-1 ≥474.1 pg/mL exhibited a significantly higher risk for the upper half of BVAS than those without (relative risk 5.932). Multivariable logistic regression analysis demonstrated sTREM-1 ≥474.1 pg/mL (odds ratio 5.662) was associated with the upper half of BVAS. Conclusion: sTREM-1 reflects the activity of MPA and GPA, suggesting its role as a potential biomarker for assessing disease severity.