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 TH 9 and Treg cell levels; Rosacea subjects displayed elevated TH 1 cell levels; and Rosacea/Demodex patients exhibited increased frequencies of TH 9 and TH 22 cells. In contrast to Rosacea subjects, Rosacea/Demodex group members displayed higher TH 2 cell levels; and when compared with Demodex groups, they had higher TH 1 and TH 2 but lower Treg cell levels. Demodex group members also exhibited higher Treg but lower TH 1 and TH 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.