Balanced Activation of Nrf-2/ARE Mediates Sulforaphane's Protective Effect on Keratoconus in Cell Mechanical Microenvironment

Abstract

Abstract Keratoconus (KC) is a progressive degenerative disease that usually occurs bilaterally and is characterized by corneal thinning and the apical protrusion of the cornea. Oxidative stress is an indication of the accumulation of reactive oxygen species (ROS), and KC keratocytes exhibit increased ROS production compared with normal keratocytes. Therefore, oxidative stress in KC keratocytes may play a major role in the development and progression of KC. Here, we investigated the protective effect of the antioxidant sulforaphane (SF) using a hydrogel-simulated model of the cell mechanical microenvironment of KC. The stiffness of the KC matrix microenvironment in vitro was 16.70 kPa and the stiffness of the normal microenvironment was 34.88 kPa. Human keratocytes (HKs) were cultured for 24 h before observation or drug treatment with H2O2 in the presence or absence of SF. The levels of oxidative stress, nuclear factor E2-related factor 2 (Nrf-2) and antioxidant response element (ARE) were detected. The high-stress state of HKs in the KC cell mechanical microenvironment compensates for activation of the Nrf-2/ARE signaling pathway. H2O2 leads to increased oxidative stress and decreased levels of antioxidant proteins in KC. In summary, SF can reduce endogenous and exogenous oxidative stress and increase the antioxidant capacity of cells.