Skin-homing T-cell responses associated with Demodex infestation and rosacea

Aims Our aim was to investigate the skin-homing T-cell immune responses triggered in patients with Demodex infestation and/or rosacea. Methods Collected whole blood samples were divided into four groups: control subjects; nonrosacea patients with Demodex infestation (Demodex group); papulopustular rosacea (PPR) patients without Demodex infestation (Rosacea group); and PPR patients with Demodex infestation (Rosacea/Demodex group). Following ex vivo activation, skin-homing CLA+CD4+ T-cell subset levels were monitored by flow cytometry. Results When compared with control subjects, among skin-homing CD4+ T-cell subsets analysed, Demodex patients had higher T(H)9 and T-reg cell levels; Rosacea subjects displayed elevated T(H)1 cell levels; and Rosacea/Demodex patients exhibited increased frequencies of T(H)9 and T(H)22 cells. In contrast to Rosacea subjects, Rosacea/Demodex group members displayed higher T(H)2 cell levels; and when compared with Demodex groups, they had higher T(H)1 and T(H)2 but lower T-reg cell levels. Demodex group members also exhibited higher T-reg but lower T(H)1 and T(H)22 levels than Rosacea/Demodex group subjects. Conclusions The skin-homing T-cell responses associated with Demodex infestation and rosacea formation seem to influence each other. The present as well as future studies could contribute to the development of effective treatment strategies for demodicosis and rosacea.