A group of Korean and British researchers has found a useful biomarker for evaluating ANCA-associated vasculitis’s activity, Yonsei Hospital said. 

The researchers, led by Professors Lee Sang-won and Ahn Sung-soo, and Ph. D. candidate Yoon Tae-jun at Yonsei Severance Hospital and Professor McAdoo’ of the Imperial College London, jointly conducted the analysis using the serums of 60 patients registered with the ANCA vasculitis prospective cohort at the Severance Hospital’s Rheumatoid Internal Medicine Department. 

They confirmed that the YKL-40 levels in serum showed high correlations with the five-factor score (FFS) and Birmingham vasculitis activity score (BVAS) -- two indicators that reflect disease activity and prognosis in ANCA-related vasculitis -- and they significantly increased in patients with severe conditions and high FFS.

The team observed a similar phenomenon by evaluating the YKL-40 levels of British patients and found the increase of their expression in immune staining using kidney tissue. 

Likewise, they found the rise in YKL-40 levels could independently reflect the disease’s severity, and confirmed that when patients’ disease activity decreased after treatment, YKL-40 in the serum also fell significantly. 

ANCA-related vasculitis causes necrosis in small-sized vessels and can be distinguished by clinical, blood and historical findings, including Baccalaureate Vascularitis and eosinophilic polyangiitis. 

“We confirmed the YKL-40 levels reflect the disease activity of ANCA-associated vasculitis. And their increased expression in kidney tissue seems to back up our finding,” Professor Lee said. “Similarly, when the disease’s activity dropped, the YKL-40 within serum also fell. 

Lee added that the study is significant because checking YKL-40 levels in ANCA-associated vasculitis patient’s serum can be a promising biomarker for evaluating the disease activity.  

The study results were published in the March issue of Arthritis Research & Therapy.