Mitochrondrial DNA Identified as Novel Biomarker in ANCA-Associated Vasculitis

Mitochondrial DNA (mtDNA), but not nuclear DNA (nDNA), is elevated in the plasma of patients with ANCA-associated vasculitis (AAV) and is a novel indicator of disease activity, investigators reported in Rheumatology.

Stavros Giaglis, MD, of the University of Basel and University Hospital Basel in Switzerland, and colleagues compared 101 patients with AAV (80 granulomatosis with polyangiitis and 21 with microscopic polyangiitis) and 92 healthy individuals serving as a control group. The median number of mtDNA copies were 13-fold higher in the AAV group compared with the control group, whereas the nDNA concentrations did not differ between the groups. In addition, patients with active AAV (Birmingham Vasculitis Activity Score [BVAS] > 0) had a significant 4-fold higher median number of mtDNA copies compared with those in remission. Unlike nDNA, mtDNA correlated significantly with BVAS and was associated with AAV activity on multivariable analysis, according to the investigators.

Receiver operating characteristic curve analyses indicated that mtDNA quantification differentiates patients with active AAV (BVAS > 0) from healthy patients with 96.1% sensitivity and 98.9% specificity (area under the curve = 0.99). In 27 patients with AAV who had follow-up, changes in mtDNA but not C-reactive protein (CRP) or ANCA titers correlated significantly with BVAS changes.

“In summary, we demonstrate that circulating mtDNA copy numbers are vastly elevated in AAV patient plasma. Even more importantly, plasma mtDNA copy numbers are associated with vasculitis activity,” Dr Giaglis and colleagues wrote.

In contrast, they pointed out, other indicators of disease activity, such as CRP and PR3-ANCA levels, either have a weaker or no correlation with BVAS.

“Despite the limitation of our study due to the small sample size, circulating mtDNA concentrations distinguish AAV patients from non-inflammatory controls with high sensitivity and represent a novel independent biomarker of AAV activity,” the authors concluded.

This article originally appeared on Renal and Urology News