A study on the serum levels of angiopoietin-like protein 2 and vascular endothelial growth factor in rheumatoid arthritis patients and their correlations

Abstract

Objective To detect the serum levels of angiopoietin-like protein 2 (ANGPTL 2) and vascular endothelial growth factor (VEGF) in patients with rheumatoid arthritis (RA), and to analyze their value in the differential diagnosis of RA in order to clarify whether they are synergetic in the pathogenesis of RA. Methods Seventy-seven patients with RA and 25 subjects for heath check-up in the same period were selected. According to the relevant clinical information, the RA patients were divided into three subgroups: high disease activity group [(DAS28) >5.1], moderate disease activity group(3.2<DAS28≤5.1), low disease activity group (DAS28≤3.2). Enzyme-linked immunosorbent assay (ELISA) was used to masure the levls of ANGPTL2 and VEGF of those groups. The data were analyzed by t test, Mann-Whitney U test, Kruskal-Wallis H test and Speraman correlation analysis. Results ① The serum levels of ANGPTL2 and VEGF in RA patients were significantly higher than those in control group [(5.3±1.1) ng/ml vs(3.3±0.9) ng/ml, Z=-6.644; (106±30) pg/ml vs (93±12) pg/ml, Z=-4.4115, P<0.05]. ② Serum level of ANGPTL2 in RA patients with high disease activity was higher than low disease group and healthy control group {[5.7(1.3)] ng/ml vs [4.5(0.3)] ng/ml, H=4.257, P<0.05; [5.7(1.3)] ng/ml vs [3.3(0.9)] ng/ml, H=7.639, P<0.05}. Serum level of VEGF in RA patients with high disease activity was higher than low disease group and healthy control group {[116(37)] pg/ml vs [96(8)] pg/ml, H=3.579, P<0.05; [116(37)] pg/ml vs [92.90(12.24)] pg/ml, H=5.698, P<0.05]. ③ There was a positive correlation between the serum level of ANGPTL2 and DAS28 score, erythrocyte sedimentation rate, swollen joint count and tender joint count (rDAS28=0.703, rESR=0.311, rSJC=0.503, rTJC=0.670, P<0.05), so was VEGF (rDAS28=0.553, rESR=0.260, rSJC=0.399, rTJC=0.538, P<0.05). ④ In RA patients, there was a positive correlation between ANGPTL2 and VEGF (r=0.853, P<0.05). Conclusion ANGPTL2 might coordinate with VEGF and be involved in the immune process of RA, and it might be regarded as one of the reference indexes of RA activity, so that it may contribute to access and monitor the condition of RA. Key words: Arthritis, rheumatoid; Vascular endothelial growth factors; Angiopoietin-like protein 2