Novel biomarkers of disease activity identified in various forms of vasculitis

Several serum biomarkers of disease activity have been recognized in giant cell arteritis (GCA) and eosinophilic granulomatosis with polyangiitis (EGPA), according to a study. Moreover, differences in biomarker levels between diseases are more evident than those related to disease activity.

Twenty-two serum proteins were tested in patients enrolled in the Vasculitis Clinical Research Consortium Longitudinal studies of GCA, Takayasu arteritis (TA), polyarteritis nodosa (PAN), and EGPA. The authors used mixed models for most analyses and a J48 classification tree method to find the most relevant markers to differentiate between active and inactive GCA.

A total of 418 samples from 152 patients (60 GCA, 29 TA, 26 PAN, and 37 EGPA) were tested during both active vasculitis and remission.

B cell-attracting chemokine 1 (BCA-1)/CXC motif ligand 13 (CXCL13), erythrocyte sedimentation rate (ESR), interferon-γ—induced protein 10/CXC motif chemokine 10, soluble interleukin 2 receptor α (sIL-2Rα), and tissue inhibitor of metalloproteinase-1 (TIMP-1) showed significant differences between disease states in GCA (p<0.05).

In EGPA, the following biomarkers demonstrated significant increases during active disease: granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage—CSF, interleukin (IL)-6, IL-15, and sIL-2Rα. BCA-1/CXCL13 also showed increases, but only after adjustment for treatment. Additionally, ESR and matrix metalloprotease 3 (MMP-3) displayed significant differences between disease states in PAN.

Significant differences in biomarker levels were noted for 11 markers and were more prominent (p_all<0.01) than those associated with disease activity.

Eighty-seven percent of samples with inactive GCA were classified accurately by a combination of lower values of TIMP-1, IL-6, interferon-γ, and MMP-3.

“Further studies are needed to determine whether these serum proteins have potential for clinical use in distinguishing active disease from remission or in predicting longer-term outcomes,” the authors said.