To explore the significance and evaluate the early structural erosion through the expressions of Th17 cells in peripheral blood of patients with rheumatoid arthritis (RA) in clinical remission.
A total of 41 active RA patients without structural erosion were selected. Intracelluar flow cytometric detection of Th17 cells in peripheral blood was performed. And the supernatant level of interleukin (IL)-17A was determined simultaneously in RA patients and control groups at baseline and endpoint of 24-month therapy. The correlations were analyzed between Th17 cells and RA disease activity index DAS28. They were classified into radiographic progression (P, n = 10) and radiographic non-progression groups (NP, n = 26) by the Sharp/van der Heijde score (SHS) at the endpoint. The differences of Th17 cells and IL-17A levels were analyzed between P (SHS > 0.5) and NP groups (SHS ≤ 0.5).
The expression of Th17 cells in active RA patients was significantly higher than that of controls [(1.63 ± 0.45)% vs (0.91 ± 0.26)%, P < 0.01]. And the results of IL-17A level were similar [1510 ± 280) vs (320 ± 31) ng/L, P < 0.05]. The expression of Th17 cells was positively correlated with DAS28 score (r = 0.87, P < 0.01). Thirty-six RA patients were followed up at the endpoint and all of them stayed in clinical remission (DAS28 < 2.6). The peripheral blood expressions of Th17 cells of P group were significantly higher than those of NP group . At the same time, no differences of IL-17A levels existed between two groups.
Structural erosion still progresses in some RA patients despite an apparent clinic remission. And a high-level peripheral expression of Th17 hints at structural erosion.