Tear cytokines and chemokines in patients with Demodex blepharitis

The purpose of the study is to evaluate the causes of inflammation in Demodex-induced blepharitis by analyzing cytokine levels in lacrimal fluid.

Fifteen Demodex blepharitis patients were selected for assessment of tear cytokine concentrations. Fifteen Demodex-free blepharitis patients and 15 subjects with no ocular symptoms were selected as control groups. Minimally stimulated tear samples (20μl) were collected from each eye and analyzed using a Luminex® 200™ Total System for detection of IL-1β, IL-5, IL-7, IL-12, IL-13, IL-17, granulocyte colony-stimulating factor (G-CSF), and macrophage inflammatory protein-1 beta (MIP-1β).

The concentration of IL-17 in tears was significantly higher in the Demodex blepharitis group than in the Demodex-free blepharitis group. Tear IL-7 and IL-12 levels show serial increases for these three groups (p<0.05). There were no significant differences in the other cytokines levels between both blepharitis groups. We confirmed that elevated cytokines normalized after treatments.

Infestation of Demodex mites induces change of tear cytokine levels, IL-17 especially, which cause inflammation of the lid margin and ocular surface. These findings might increase our understanding of the mechanism of ocular discomfort and telangiectasias frequently found in Demodex blepharitis patients.