Trans-omics landscape of systemic vasculitis identified matrix metalloproteinase 12 as a novel signature molecule.

OBJECTIVES: To identify key molecules involved in the disease pathophysiology of systemic vasculitis through trans-omics analysis, with a specific focus on demonstrating matrix metalloproteinase (MMP) 12 as a potential biomarker in rheumatic entities. METHODS: Patients with newly diagnosed or relapsed rheumatic and musculoskeletal diseases from June 2013 until September 2022 were enrolled. We screened vasculitis-specific molecules by combining findings from serum proteome analysis and whole-blood RNA sequencing. We further validated the identified molecules using immunohistochemical staining and spatial transcriptome analysis. RESULTS: Serum proteome and RNA sequencing identified MMP12 as a significant molecule for systemic vasculitis; it distinguished vasculitis from other rheumatic and musculoskeletal diseases, reflected disease activity along with longitudinal change, and predicted relapse in patients with large-vessel vasculitis. MMP12 could also be used to detect insidious disease activity even under treatment with IL-6 inhibition. Immunohistochemical staining of the affected tissues demonstrated that MMP12 was specifically expressed in tissue-infiltrating CD206-positive macrophages. Spatial transcriptome analysis revealed the characteristic phenotype of MMP12-positive macrophages and its association with macrophage maturation and formation of multinucleated giant cells. CONCLUSION: MMP12 is a disease-specific molecule that is associated with macrophage maturation and the formation of multinucleated giant cells and reflects disease activity independently of the IL-6 pathway in systemic vasculitis.