Interleukin (IL)-13/IL-22/IL-31 skewing within the skin-homing T-cell population in papuloerythroderma

Papuloerythroderma (PEO) is a representative form of senile erythroderma with an unclear pathogenesis. This study aimed to characterize the T-cell phenotypes responsible for the pathogenesis of PEO. Cytokine profiles and cutaneous lymphocyte antigen (CLA) expression on circulating T lymphocytes in patients with PEO were simultaneously analyzed using flow cytometry. The patients with PEO showed significantly higher circulating interleukin (IL)-4-, IL-13-, IL-22-, and IL-31-producing CD4⁺ and CD8⁺ T-cell levels than healthy subjects. However, their levels significantly decreased after remission of PEO. No difference was observed in the proportions of circulating interferon (IFN)-γ- and IL-17-producing CD4⁺ and CD8⁺ T cells between the patients with PEO and healthy subjects. In particular, the proportion of circulating IL-4-, IL-13-, IL-22-, and IL-31-producing CD4⁺ and CD8⁺ T cells was much higher in the CLA⁺ subset than in the CLA^– subset. There was a positive correlation between IL-13-, IL-22-, and IL-31-producing CD4⁺ T cells and the disease severity score of PEO. Moreover, a positive correlation was also observed between the proportion of IL-22- or IL-31-producing cells and circulating IL-13-producing cells in both CD4⁺ and CD8⁺ T cells, and approximately 50% of both IL-22- and IL-31-producing CD4⁺ and CD8⁺ T cells coproduced IL-13. IL-13/IL-22/IL-31 skewing within the skin-homing T-cell population may be involved in the pathogenesis of PEO.