Objective To explore the clinical significance and expression levels of angiogenin protein 4(ANGPTL4), interleukin-17(IL-17) and receptor activator of nuclear factor-kappa B ligand (RANKL) in serum and joint fluid of patients with rheumatoid arthritis.

Methods A total of 165 patients with rheumatoid arthritis were selected as observation group, 165 patients with osteoarthritis during the same period were selected as disease control group, and another 165 healthy physical examination subjects as normal control group. The expressions of ANGPTL4, IL-17 and RANKL in serum and(or) joint fluid of the observation group, normal control group and disease control group were detected by enzyme linked immunosorbent assay. The correlations of the levels of ANGPTL4, IL-17 and RANKL in serum of the observation group with disease activity were analyzed.

Results The serum levels of ANGPTL4, IL-17 and RANKL in the observation group were higher than those of the disease control group and the normal control group, while the ANGPTL4, IL-17 and RANKL in the disease control group were higher than the normal control group (P < 0.05). There was no significant difference in the expression levels of ANGPTL4, IL-17 and RANKL in the joint fluid between the observation group and the disease control group (P > 0.05). The expression levels of ANGPTL4, IL-17 and RANKL in the joint fluid of the observation group and the disease control group were lower than those in the serum, and the differences were statistically significant (P < 0.05). In patients with different disease activity degree in the observation group, the serum levels of ANGPTL4, IL-17 and RANKL in the highly active patients were higher than those in the low and moderate activity degree patients, and were higher in the moderate activity degree patients than those in the low activity degree patients, and the differences were statistically significant (P < 0.05). Pearson correlation analysis showed that serum ANGPTL4, IL-17 and RANKL levels were positively correlated with Disease Activity Score in 28 joints (DAS28) score, erythrocyte sedimentation rate(ESR) and C-reactive protein(CRP) levels(P < 0.001). Receiver operating characteristic curve showed that the area under the curve of ANGPTL4, IL-17 and RANKL in combination in predicting the 1-year joint imaging progression in patients with rheumatoid arthritis was 0.910.

Conclusion Serum levels of ANGPTL4, IL-17 and RANKL are significantly positively correlated with disease activity degree in patients with rheumatoid arthritis, their combined prediction of 1-year joint imaging progression has better efficacy, providing a new way to monitor the changes of rheumatoid arthritis.