[Correlation between serum CCL20 level and disease severity in patients with rheumatoid arthritis].

Objective: To investigate the correlation between serum CCL20 level and disease severity in patients with rheumatoid arthritis (RA). Methods: From July 2018 to July 2019, a cross-sectional study was conducted in the Department of Rheumatology and Immunology, the Third Affiliated Hospital of Southern Medical University. The observation group consisted of 105 outpatients and inpatients diagnosed with RA, while the control group was 90 healthy people with age and gender matched physical examination in the Third Affiliated Hospital of Southern Medical University. According to Steinbroker classification, RA patients were divided into Steinbroker grade 2 group (n=35), Steinbroker grade 3 group (n=38) and steinbroker grade 4 group (n=32); according to DAS28 score, RA patients were divided into remission group (DAS28<2.6)(n=39), mild active group (DAS28 2.6-3.2)(n=25), moderate active stage group (DAS28 3.2-5.1)(n=20) and severe active stage group (DAS28 ≥ 5.1)(n=21). The levels of chemokine ligand 20 (CCL20), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were detected by ELISA. The levels of CCL20 in each group were compared, and the correlation between CCL20 and other indicators was analyzed. The receiver operating characteristic (ROC) curve of CCL20 in diagnosis of RA was analyzed to explore the correlation between CCL20 and disease severity of RA patients. Results: Compared with the normal control group, the serum CCL20 level in RA patients was significantly increased [(48.1±16.7) pg/ml vs (17.6±5.9) pg/ml, t=19.39, P<0.001]. In addition, serum CCL20 in steinbroker grade 4 group was significantly higher than that in Steinbroker grade 3 group [(59.5±10.1) pg/ml vs (47.4±17.5) pg/ml, t=3.472, P<0.001], and the serum CCL20 level in steinbroker grade 3 group was significantly higher than that in steinbroker grade 2 group [(47.4±17.5) pg/ml vs (38.4±14.6) pg/ml, t=2.370, P<0.001], CCL20 level in steinbroker grade 2 group was significantly higher than that in normal control group [(38.4±14.6) pg/ml vs (17.6±5.9) pg/ml, t=7.738, P<0.001]. In addition, serum CCL20 level was significantly positively correlated with steinbroker score (r=0.505, P<0.001); CCL20 level in active RA patients was significantly higher than that in remission RA patients [(57.2±13.2) pg/ml vs (32.7±8.9) pg/ml, t=10.31, P<0.001]. The serum CCL20 level in severe activity group was significantly higher than that in moderate activity group [(60.6±10.9) pg/ml vs (51.7±16.2) pg/ml, t=0.212, P=0.040], and the serum CCL20 level in moderate activity group was significantly higher than that in mild activity group [(51.7±16.2) pg/ml vs (40.5±18.6) pg/ml, t=0.217, P=0.037]. In addition, there was a significant positive correlation between serum CCL20 level and DAS28 score (r=0.451, P<0.001). In addition, serum CCL20 level was positively correlated with serum CRP (r=0.332, P<0.001). According to the ROC curve, the specificity of steinbroker grade 2 group was 0.53, and the sensitivity was 0.74, AUC was 0.659; the sensitivity of steinbroker grade 3 group was 0.78, and the specificity was 0.69, AUC was 0.734; the sensitivity of mild vs medium stage was 0.64, and the specificity was 0.70, AUC was 0.699; the sensitivity of medium stage vs severe stage was 0.57, and the specificity was 0.68,AUC was 0.678. Conclusion: Serum CCL20 level in RA patients is significantly increased and positively correlated with disease severity, which may be used as a marker to observe and evaluate the progression of RA.