[Hyperosmolarity: Intracellular effects and implication in dry eye disease].

Dry eye disease is a multifactorial disease affecting the lacrimal functional unit and which has a significant impact on the quality of life of patients. This pathology works as a vicious circle at the ocular surface in which hyperosmolarity of the tear film plays a key role. This review intends to describe the different reported intracellular effects induced by hyperosmolarity in cells: alteration of cytoskeleton, cell cycle slowdown, adaptation mechanisms triggered as restoration of cell volume and accumulation of compatible osmolytes, the crucial role of the osmoprotectant factor Nuclear Factor of the Activated T cells-5 (NFAT5), apoptosis, as well as oxidative stress and inflammatory responses caused by this particular condition. Reported effects of hyperosmolarity in the experimental studies specific of dry eye disease concerning ocular surface cells will be described in parallel. Indeed, these data allow to understand a part of the pathophysiology of the disease, and specially the links between tear hyperosmolarity and inflammation of the ocular surface, the second key of the pathology phenomenon.