Evaluation of Conventional and Hyaluronic Acid-Coated Thymoquinone Liposomes in an In Vitro Model of Dry Eye

Dry eye disease (DED) is a common ocular disorder characterized by an inadequate lubrication of the eye by tears leading to inflammation and the alteration of the ocular surface. Current treatments are often limited due to their side effects and ineffectiveness. Thymoquinone (TQ) is a natural compound present in the essential oil of Nigella sativa L., with anti-inflammatory and antioxidant activities. In this study, conventional and hyaluronic acid-coated liposomes were developed to improve TQ activity at ocular level. In the present study, the cytoprotective effects of TQ or TQ liposomes were assessed against oxidative and inflammatory processes in human corneal epithelial cells (HCE-2). Hyperosmolarity conditions (450 mOsm) were used as a model of DED. Interleukin-1 beta (IL-1 beta), Interleukin-6 (IL-6) and tumor necrosis factor (TNF alpha) were quantified by quantitative real-time polymerase chain reaction (RT-qPCR); COX-2 and Phospho-NF-kappa B p65 (p-p65) by Western blotting (WB). Moreover, the mitochondrial reactive oxygen species (mtROS) levels were measured by MitoSOX assay. The hyperosmotic treatment induced a significant increase of the proinflammatory genes and proteins expression that were significantly decreased in the liposomes-treated cells. The coincubation with hyaluronic acid-coated liposomes significantly reverted the increase of mtROS production, evidently stimulated by the hyperosmotic stress. Our data suggest that TQ-loaded liposomes have potential as a therapeutic agent in dry eye disease, improving the TQ efficacy.