Evaluation of Potential Serum Biomarkers of Disease Activity in Diverse Forms of Vasculitis
Abstract
Objective We evaluated potential circulating biomarkers of disease activity in giant cell arteritis (GCA), Takayasu’s arteritis (TAK), polyarteritis nodosa (PAN), and eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss).
Methods A panel of 22 serum proteins was tested in patients enrolled in the Vasculitis Clinical Research Consortium Longitudinal Studies of GCA, TAK, PAN, or EGPA. Mixed models were used for most analyses. A J48 classification tree method was used to find the most relevant markers to differentiate between active and inactive GCA.
Results 418 samples from 152 patients (60 GCA, 29 TAK, 26 PAN, 37 EGPA), during both active vasculitis and remission, were tested. In GCA, BCA-1/CXCL13, ESR, IP-10/CXCL10, sIL-2Rα, and TIMP-1 showed significant (P<0.05) differences between disease states. In EGPA, G-CSF, GM-CSF, IL-6, IL-15, and sIL-2Rα showed significant increases during active disease, as did BCA-1/CXCL13 but only after adjustment for treatment. In PAN, ESR and MMP-3 showed significant differences between disease states. Differences in biomarker levels between diseases were significant for 11 markers and were more striking (all P<0.01) than differences related to disease activity. A combination of lower values of TIMP-1, IL-6, INFɣ, and MMP-3 correctly classified 87% of samples with inactive GCA.
Conclusion We identified novel biomarkers of disease activity in GCA and EGPA. Differences of biomarker levels between diseases, independent of disease activity, were more apparent than differences related to disease activity. 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.