Study of serial serum myeloid-related protein 8/14 as a sensitive biomarker in Takayasu arteritis: a single centre study.

The aim of the study was to explore utility of serial serum myeloid-related protein 8/14 (MRP8/14) as a biomarker of clinical disease activity and angiographic progression in Takayasu arteritis (TA). Serum MRP8/14 levels were assayed by commercial ELISA for 85 TA patients and 24 healthy controls at baseline, and for 56 and 21 TA patients during follow-up visits R1 and R2, respectively. Disease was categorised as active, indeterminate and stable according to Indian Takayasu Arteritis score (ITAS 2010), ITAS-A(CRP) and angiography. Patients were divided into responders and non-responders/relapsers based on treatment response. Non-parametric tests were used for inter-group comparisons at baseline and during follow-up time points. Generalised Estimating Equation was used to study association between changes in serial MRP8/14 levels and disease activity. At baseline, median MRP8/14 levels were higher in patients with TA than healthy controls [7353 (4524 to11283) vs 4896 (3194 to 8474.5) ng/ml, p = 0.011]. Patients with active disease had higher levels [8552 (5463-12488)] than stable disease [5292.5 (3140.5-7310)], p = 0.002, and healthy controls [4896 (3194-8474.5)], p = 0.001. Changes in serial MRP8/14 level were associated with changes in disease activity, independent of steroid dose, p = 0.000. At R1, MRP 8/14 levels were lower than baseline in responders (n = 38) [9146.0 (6296.8-13693.8) vs 6501 (4314.8-8304.5), p = 0.004], but did not change in non-responders/relapsers (n = 14) [6693.5(4210.8-10516.3) vs 7755.0(5342-10741.0), p = 0.42]. Similar trend was observed at R2. MRP8/14 levels increased during follow-up in 66% and 26.3% of angiographic progressors and non-progressors, respectively. MRP8/14 in TA may act as a novel biomarker with prognostic implications.