PLATELET FACTOR 4 AS A BIOMARKER IN KOREAN PATIENTS WITH SYSTEMIC SCLEROSIS

초록

Background: Systemic sclerosis (SSc) is a complex multi-organ autoimmune disease with chronic and heterogeneous clinical manifestations. There is an unmet need for a new biomarker for early diagnosis and classification of SSc. Recent technical advancements have indicated several biomarkers for SSc; among these, platelet factor 4 (PF4), also known as CXCL4, was suggested by a large-cohort proteomic study 1. PF4 is a chemokine released from activated platelets and is involved in coagulation, inflammation, and angiogenesis, which are influential in SSc pathogenesis. Therefore, PF4 may be an effective biomarker for SSc. Objectives: To investigate the efficacy of PF4 as a biomarker for the diagnosis, activity and severity of patients with SSc. Methods: Thirty-nine SSc patients (36 female and 3 male; mean age, 58.8±10.42 years; mean disease duration, 7.15±3.92 years; 11 diffuse cutaneous SSc cases and 28 limited cutaneous SSc cases) and 30 healthy controls (HC; 25 female and 5 male; mean age, 46.43±14.43 years) were enrolled. To estimate the circulating PF4 level, levels of platelet poor plasma (PPP) PF4 as well as serum PF4 were measured using an ELISA kit (R&D, Minneapolis, USA). SSc patients were divided into 2 subgroups according to disease activity and based on the presence/absence of interstitial lung disease (ILD), pulmonary hypertension, digital ulcers, and autoantibodies (anti-centromere Ab and anti- Scl70 Ab). Differences between SSc and HC groups were compared by Student’s t-test, and the subgroups were compared using the Mann-Whitney test. Predictive values of serum PF4 and PPP PF4 for SSc diagnosis were evaluated by the area under the receiver operating characteristic curve (AUROC). Results: Serum PF4 levels of SSc were lower than those of HC (SSc, 5143.3±1777.5 ng/mL; HC, 5927.4±1348.5 ng/mL; p =0.048) but no significant differences were observed PPP PF4 levels (SSc, 407.2±486.6 ng/mL; HC, 297.3±141.5 ng/mL; p =0.187) betwee