To investigate CD25(-)FOXP3(+) cells in RA patients and their possible relationship with disease features and response to glucocorticoids (GCs).
Peripheral blood mononuclear cells were collected from 147 RA patients, 29 healthy controls and 75 SLE patients as disease controls. The proportion of CD4(+)FOXP3(+) cells with negative, low or high CD25 expression and the levels of IL-10-, TNF-α-, IL-17- and IFNγ-producing cells were assessed by flow cytometry. The presence of the high IL-10 genotype (-1082GG), associated with good response to GC, was determined by PCR amplification and hybridization with allele-specific fluorescently labelled probes. Data were related to treatment and clinical parameters.
The CD25(-)FOXP3(+) population was significantly increased in RA patients and negatively correlated with DAS-28 and other disease parameters. The IL-10 genotype did not influence the frequency of these cells in controls or the entire RA group; however, GC-treated patient carriers of the high IL-10 genotype presented significantly higher levels of this population in addition to an increased percentage of IL-10-secreting cells and relatively low amounts of TNF-α-, IFN-γ- and IL-17-positive cells. Finally, a prospective study confirmed that genetically high IL-10 producers significantly increase CD25(-)FOXP3(+) cells after 6 months of GC treatment.
The present study provides the first evidence of increased CD25(-)FOXP3(+) cells in RA patients, which were associated with disease activity and with GC treatment in carriers of the high IL-10 genotype, suggesting that this population plays a role in the clinical response to prednisone in RA.