[Expression of plasma Dickkopf-1 in patients with rheumatoid arthritis and its correlation with peripheral blood T cell subsets].

Objective: To detect the levels of Dickkopf-1 (DKK-1) in the plasma of patients with rheumatoid arthritis (RA), and to analyze their correlation with peripheral blood T cell subsets and clinical indicators.
Methods: Enzyme-linked immunosorbent assay (ELISA) was used to detect plasma DKK-1 levels in 32 RA patients and 20 healthy controls, and to record the various clinical manifestations and laboratory indicators of the RA patients, and flow cytometry to detect peripheral blood T cell subsets in the RA patients (Including Treg, nTreg, aTreg, sTreg, Teff, Tfh, CD4 ⁺ CD161 ⁺ T, CD8 ⁺ T, CD8 ⁺ CD161 ⁺ T cells). The plasma DKK-1 levels between the two groups were ompared, and its correlation with peripheral blood T cell subsets and clinical indicators analyzed.
Results: (1) The plasma DKK-1 concentration of the RA patients was (124.97±64.98) ng/L. The plasma DKK-1 concentration of the healthy control group was (84.95±13.74) ng/L. The plasma DKK-1 level of the RA patients was significantly higher than that of the healthy control group ( P < 0.05), and the percentage of CD8 ⁺ CD161 ⁺ T cells in the peripheral blood of the RA patients was significantly higher than that of the healthy control group ( P < 0.05). (2) The plasma DKK-1 level was positively correlated with erythrocyte sedimentation rate ( r =0.406, P =0.021), DAS28 score ( r =0.372, P =0.036), immunoglobulin G( r =0.362, P =0.042), immunoglobulin A( r =0.377, P =0.033); it had no correlation with age, course of disease, C-reactive protein, rheumatoid factor, anti-cyclic citrullinated peptide antibody, immunoglobulin M, complement C3, complement C4, white blood cell, neutrophil ratio. (3) The plasma DKK-1 level in the RA patients was positively correlated with the percentage of peripheral blood CD161 ⁺ CD8 ⁺ T cells ( r =0.413, P =0.019);it had no correlation with Treg, nTreg, aTreg, sTreg, Teff, Tfh, CD4 ⁺ CD161 ⁺ T, CD8 ⁺ T cells. (4) The percentage of CD161 ⁺ CD8 ⁺ T cells was negatively correlated with erythrocyte sedimentation rate ( r =-0.415, P =0.004), C-reactive protein ( r =-0.393, P =0.007), DAS28 score( r =-0.392, P =0.007), rheumatoid factor ( r =-0.535, P < 0.001), anti-citrullinated protein antibody ( r =-0.589, P < 0.001), immunoglobulin G( r =-0.368, P =0.012) immunoglobulin M ( r =-0.311, P =0.035); it had no correlation with age, disease course, immunoglobulin A, complement C3, complement C4, white blood cell, and neutrophil ratio.
Conclusion: RA patients' plasma DKK-1 levels and the percentage of CD8 ⁺ CD161 ⁺ T cells in T cell subsets in peripheral blood increase, which may be related to the secretion of proinflammatory cytokines in patients; DKK-1 is involved in the regulation of bone homeostasis and can be used as a marker of bone destruction in RA.