ABSTRACT
Objective:To investigate the changes of intestinal mucosal barrier function related indexes [diamine oxidase and secretory immunoglobulin A (sIgA)] in peripheral blood of patients with rheumatoid arthritis (RA) and their correlation with peripheral immune function.Methods:A total of 40 patients with RA who admitted to the Rheumatology and Immunology department of the Second Hospital of the Shanxi Medical University were enrolled. We collected their clinical and laboratory data, and selected 20 age and gender matched people as the control group. Enzyme-linked immunosorbnent assay (ELISA) was used to detect the level of DAO and sIgA in the peripheral blood, the lymphocytes and CD4 + T subsets were detected by flow cytometry. Then t-test, rank sum test and correlation analysis were conducted for statistical analysis. Results:① The level of DAO in patients with RA was higher than that of healthy controls [205(164, 251) ng/ml vs 364 (276, 483) ng/ml, Z=-4.48, P<0.001], while the level of sIgA was decreased [3.64 (2.76, 4.83)×10 5 ng/ml vs 6.83 (4.80, 9.44)×10 5, Z=-3.84, P<0.001]. ② The absolute number of B and CD4 + T cells were increased in RA, the difference were statistically significant, but the absolute number of T, natural killer cells (NK) and CD8 + T cells were not significantly different between the two groups. For CD4 + T subsets, the absolute number of T helper cells (Th)1 and Treg cells in RA group were significantly decreased than healthy controls, but there were no statistical significant difference in the number of Th2 and Th17 cells. ③ The level of DAO was positively correlated with absolute number of Th17 cells in patients with RA ( r=0.36 P=0.038), and positively correlated with age and white blood cell count ( r=0.40, P=0.021; r=0.40, P=0.020), but no significant correlation among other indicators were found. ④ The serum sIgA level of RA patients in antimutated citrullinated vimentin antibody (MCV), antiperinuclear factor (APF) and antikeratin antibody (AKA) positive group were higher than those in the negative group [3.99(2.99, 5.58)×10 5 ng/ml vs 2.73(2.29, 3.05)×10 5 ng/ml, Z=-2.55, P=0.011; 5.49 (3.26, 5.70)×10 5 ng/ml vs 3.12 (2.29, 4.04)×10 5 ng/ml, Z=-2.28, P=0.023; 4.07 (3.19, 5.65)×10 5 ng/ml vs 2.88 (2.24, 3.86)×10 5 ng/ml, Z=-2.42, P=0.016], while there was no significant difference in DAO level between groups. ⑤ The DAO level of RA patients with pulmonary interstitial fibrosis was significantly higher than that in the group without pulmonary interstitial fibrosis [421 (216, 528) ng/ml vs 191 (150, 223) ng/ml, Z=-2.81, P=0.005], while there were no significant differences in DAO and sIgA levels among other groups. Conclusion:In RA patients with inte-stinal mucosal barrier impairment, the DAO level is increased, while the sIgA is decreased, and in addition, elevated peripheral blood Th17 may be involved in the process of intestinal mucosal barrier impairment.