Background: T-regulatory cells (Tregs) play important role in rheumatoid arthritis (RA). The level of expression of type 1 and 2 receptors to TNF-alpha (TNFR1/2) (as TNF-alpha is a key mediator in RA) and their co-expression on certain subpopulations are shown to be one of the mechanisms regulating functional activity of cells and may influence course of pathological process. Thus, the aim was to study the changes in expression of TNFRs on T-cells subsets in RA.
Methods: Flow cytometry was used to analyze co-expression of TNFRs among different subsets of T-cells in RA patients (n=12) and healthy donors (HD, n=15). Tregs were identified as CD4+CD25hiCD27low population. To determine receptor number on the cells QuantibritePE Beads (BD) were used.
Results: Tregs differed by co-expression of TNFR1/2 compared to the general CD4+CD25+ cell pool in both RA patients and HD. Among Tregs, almost all cells expressed at least one of the TNFRs (5% of double negative cells in HD and 4% in RA patients) compared to the other CD4+CD25+ cells (44% and 34%, respectively). Tregs were characterized by higher percentage of TNFR1+TNFR2+ cells (20% in HD and 31% in RA patients) compared to other T-cells (6% and 13%, respectively). In addition, Tregs were characterized by a higher density of TNFR1 compared with other T-cells (1.3 times in HD and 1.7 times in RA patients). After methyl-prednisolone pulse-therapy and decrease of RA activity (by the DAS-28), the percentage of cells expressing each type of TNFRs and the number of TNFR1 per cells on Treg decreased compared to those in the acute stage of RA.
Conclusion: Tregs differ in the expression of TNF-alpha receptors compared to other T-cells subpopulations. Co-expression of TNFR1/2 and the amount of TNFR1 per cell differ in RA compared to health and may change significantly under the influence of treatment.