Role of CD4+CD25high+FOXP3+Regulatory T Cells in Psoriasis

Abstract

CD4(+)CD25(high+)regulatory T cells (Tregs) are considered to be of vital importance for maintaining immunologic self-tolerance and preventing autoimmune diseases. These cells have been found to be deficient in skin lesions and in the peripheral blood of patients with psoriasis. To investigate the role of Tregs in the pathogenesis of psoriasis and to evaluate the changes in Tregs in relation to the severity and the clinical course of psoriasis. Immunohistochemistry (CD3, 4, 8, 79 and FOXP3) was performed in 22 psoriatic patients compared to 5 normal controls. Flow cytometry (CD3, 4, 8, 25 and FOXP3) was performed in 18 psoriatic patients and 8 normal volunteers and reverse transcriptase polymerase chain reaction (foxp3 mRNA) was performed in 8 psoriasis patients. An increase in the FOXP3(+) cell fraction was detected in the lesional psoriatic skin irrespective of the severity of psoriasis as compared with the normal skin. However, a decrease in FOXP3(+) cells was observed in the samples obtained from psoriasis of 'acute course'. FOXP3(+) Treg populations in the blood of the 'acute course' psoriasis was not different compared to that of 'chronic course' psoriasis and normal controls. The deficiency of FOXP3(+) Tregs in the lesional psoriatic skin might be responsible for the exacerbation of psoriasis.