Evaluation of Lipid Oxidative Stress Status in Atopic Ocular Surface Disease

Abstract

Purpose: : Atopic dermatitis is characterized by presence of inflammatory cell infiltrates which release proinflammatory cytokines and reactive oxygen species. Although the oxidative stress in atopic skin disease has been reported to be elevated, there are still no studies related to the status of oxidative stress in atopic ocular surface disease. The purpose of this study was to evaluate the ocular surface lipid oxidative stress status and inflammation in Atopic Keratoconjunctivitis(AKC) patients and normal subjects.

Methods: : Twenty six eyes of 14 patients (9 males, 5 females) with AKC and 18 eyes of 9 age and sex matched (4 males and 5 females) normal healthy controls were examined in this prospective study. All subjects underwent Schirmer test, tear film break up time, fluorescein / Rose Bengal stainings, tear collection and brush cytology from the upper palpebral conjunctiva. The brush cytology samples were stained with Diff-Quik for differentiation of inflammatory cells and immunohistochemistry (IHC) staining with HEL (hexanoyl-lysine) and 4HNE (4-hydroxy-2-nonenal) to study lipid oxidation. HEL and cytokine (IL-4, IL-5, IL-10, TNF-α, IFN-γ) levels were measured by ELISA from tear samples of AKC patients and control subjects. Toluidine Blue and IHC staining with HEL, 4HNE and CD45 were performed on papillary samples of AKC patients. This study was conducted in compliance with the "Declaration of Helsinki".

Results: : The tear stability and vital staining scores were significantly worse in eyes with AKC patients (p<0.01) compared to the controls. Inflammatory cells and positively stained conjunctival epithelial cells for HEL and 4HNE showed a significant elevation in brush cytology of AKC patients. Significantly higher levels of HEL and cytokines were detected in tears of AKC patients compared to controls. Papillary specimens also revealed many positively stained cells for inflammatory markers as well as HEL and 4HNE in the IHC stainings. A significant linear positive correlation between conjunctival inflammation and epithelial lipid oxidative stress status was observed. Conjunctival lipid oxidative stress also correlated strongly with tear HEL levels and epithelial damage scores.

Conclusions: : The ocular surface disease in AKC was characterized by marked tear instability, ocular surface epithelial damage, increases in inflammatory infiltrates and presence of increased lipid oxidation.

Keywords: conjunctivitis • oxidation/oxidative or free radical damage • cornea: tears/tear film/dry eye