High mobility group box 1 (HMGB-1), a kind of proinflammatory mediator, is associated with inflammatory conditions and tissue damage. Previous studies have reported that circulating HMGB-1 levels in patients with active antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) were associated with renal manifestations and burdens of granulomatous inflammation. The current study aimed to investigate whether circulating HMGB-1 levels were associated with disease activity in AAV.
Plasma samples from 74 patients with AAV in active stage and 65 patients with AAV in remission were collected. The plasma levels of HMGB-1 were determined by enzyme-linked immunosorbent assay. Associations between plasma levels of HMGB-1 with clinical and pathologic parameters were analyzed.
Plasma levels of HMGB-1 in active AAV patients were significantly higher than those in normal controls and AAV patients in remission (median 6.11 [interquartile range (IQR) 3.25-12.79] ng/ml versus median 1.12 [IQR 0.53-1.39] ng/ml, P< 0.001; median 6.11 [IQR 3.25-12.79] ng/ml versus median 3.04 [IQR 1.97-4.63] ng/ml, P < 0.001, respectively). Correlation analysis showed that plasma levels of HMGB-1 correlated with initial serum creatinine (r = 0.275, P = 0.018), estimated glomerular filtration rate (r = -0.277, P = 0.017), the Birmingham Vasculitis Activity Score (r = 0.308, P = 0.008), and C-reactive protein level (r = 0.309, P = 0.008). Among the patients with myeloperoxidase (MPO)-ANCA, those within the first quartile of plasma HMGB-1 levels had a significantly lower level of MPO-ANCA than those within the other 3 quartiles.
Circulating HMGB-1 levels might reflect the disease activity and renal involvement of AAV vasculitis.