Circulating CD4+CD25brightFOXP3+ T Cells Are Up-Regulated by Biological Therapies and Correlate with the Clinical Response in Psoriasis Patients

Background: Regulatory T-cell (T reg ) modulation is one of the potential mechanisms of anti-tumour-necrosis-factor biological agents. However, literature data on psoriasis patients are lacking. Objective: To analyse the circulating CD4+CD25 bright FOXP3+ subset in 30 patients with psoriasis vulgaris/arthropathic psoriasis treated with biologicals and to investigate its relationship with the clinical response. Methods: The CD25 bright FOXP3+ expression within the CD4+ subset was determined by multi-parameter flow cytometry at baseline and during treatment. FOXP3 mRNA expression was analysed by real-time reverse transcription PCR. Results: A response was obtained in 16/17 patients (91.1%) with increased CD25 bright FOXP3+ values and in only 3/11 patients (27.3%) who showed a CD25 bright FOXP3+ decrease during biological treatment (p = 0.0001). Responders showed significantly higher values than did non-responders as from the first 2 months of treatment (p = 0.0032). A significantly higher posttreatment expression of mRNA FOXP3 was observed in responders compared to non-responders. Conclusion: Biological drugs induce a circulating T reg up-regulation in a significant percentage of patients; such an increase is an early predictive marker of response.