Serum lysosomal-associated membrane protein-2 levels are increased in small and medium-vessel vasculitis, especially in polyarteritis nodosa.

OBJECTIVES: Lysosomal-associated membrane protein-2 (LAMP-2) is a highly glycosylated type I glycoprotein ex- pressed on the membranes of neutrophils, endothelial cells and other cells, which are closely linked to subsets of systematic vasculitis. The aim of this study was to investigate whether serum LAMP-2 can be used as a biomarker in small and medium vessel vasculitis (SMVV).

METHODS: Serum samples from 39 patients with SMVV (including ANCA-associated vasculitis (AAV) and polyarteritis nodosa (PAN)) confirmed by angiography and/or biopsy and 78 healthy controls (HC) were collected. Serum LAMP-2 levels were determined by enzyme-linked immunosorbent assay.

RESULTS: Serum LAMP-2 levels in SMVV patients were increased compared with HC (p<0.001). Serum LAMP-2 levels were significantly different between patients with active stage and those with inactive stage (p=0.024). Patients with renal involvement had higher LAMP-2 levels than patients with non-renal involvement at presentation (p=0.022). Furthermore, serum LAMP-2 levels were correlated with Birmingham Vasculitis Activity Score (BVAS), C-reactive protein (CRP), hypersensitive CRP (Hs-CRP), serum creatinine (Scr) and 24-hour proteinuria (all p<0.05). Among SMVV subsets, serum LAMP-2 levels were signi cantly higher in PAN compared with AAV (p=0.003). In PAN patients, serum LAMP-2 levels were correlated with BVAS and Hs-CRP (all p<0.05).

CONCLUSIONS: Serum LAMP-2 levels can reflect the disease activity and renal involvement of SMVV. Furthermore, serum LAMP-2 levels were significantly higher in PAN compared with AAV, and associated with disease activity. LAMP-2 might be a potential biomarker for SMVV, especially in PAN.