Superoxide Dismutase Levels Correlated With Disease Activity, May Serve As a Potential Biomarker for AAV

Serum superoxide dismutase (SOD) levels may potentially serve as a proxy for disease activity among patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), according to study results published in Advances in Rheumatology.

Disease activity of AAV is typically evaluated using Erythrocyte sedimentation rate (ESR), C reactive protein (CRP) levels, and the Birmingham Vasculitis Activity Score (BVAS). With BVAS considered an inconvenient assessment tool and the nonspecific nature of the current biomarkers used, the need for a simple and effective method of disease severity assessment for AAV is paramount. Investigators assessed the clinical utility of SOD for management of AAV.

The investigators conducted a retrospective analysis of patients with AAV from the Second Affiliated Hospital of Chongqing Medical University. A control group comprised of 150 healthy patients free from disease or any comorbidities that may influence oxidative state were used for comparison.

Data on disease activity according to BVAS scores as well as serum SOD levels, ESR, CRP, ANCA, organ involvement, and survival and mortality rates were analyzed. 

A total of 152 patients with AAV with an average age of 64.07 years were included in the analysis.

Pulmonary (76.32%) and renal (55.92%) involvement were among the most common organs affected.

Myeloperoxidase (MPO)-ANCA and protease-3 (PR3)-ANCA positivity were present in 127 and 25 patients, respectively. In addition, 23 (15.13%) patients with AAV died.

Serum SOD levels were significantly lower among patients with AAV (78.97 U/ml) compared with the healthy control group (131.03 U/ml; P <.001). Serum SOD levels were also found to be negatively associated with ESR (rho, -0.367), CRP (rho, -0.590) and BVAS (rho, -0.488; all P <.001).

In relation to ANCA serology, a statistically significant difference in SOD levels was noted between MPO-ANCA and PR3-ANCA (72.20 U/ml vs 89.40 U/ml; P =.045).

Of note, SOD levels in relation to AAV-specific organ involvement were lower among patients with pulmonary (70.35 U/ml vs 89.65 U/ml; P =.006) and renal (65.10 U/ml vs 85.50 U/ml; P <.001) involvement, compared with their non-affected peers, respectively.

When SOD levels were stratified to compare survival (n=129) and death (n=23), SOD levels were significantly lower among patients that died vs those in the survival group (P =.001).

Lower SOD levels were found to be an independent risk factor for poor outcomes among patients with AAV (P=0.03).

The investigators cited selection and recall bias as potential study limitations.

The study authors concluded, “Our research shows that the lower level of SOD among AAV patients, reflect a higher oxidative stress state compared to healthy controls. Therefore, SOD levels in AAV patients may be a valuable index for rheumatologists.”