Celastrol nanomedicine eye drops restore redox homeostasis and prevents keratoconus progression via PI3K/AKT/AP-1 signaling.

Abstract

Keratoconus (KC) is a progressive corneal disorder primarily driven by oxidative stress, though its precise molecular mechanisms remain incompletely understood, and effective pharmacological treatments are currently lacking. Our proteomic analysis of human KC tissues identified significant oxidative stress signatures and potential PI3K pathway in disease pathogenesis. Subsequent immunohistochemical and Western blot analyses confirmed a pronounced Nox/Nrf-2 redox imbalance - characterized by elevated Nox-4 and Nox-2 and suppressed Nrf-2 - along with activation of the PI3K/AKT/AP-1 signaling axis in KC corneas compared to normal corneas. To model KC-associated oxidative damage in vitro, hydrogen peroxide was used to stimulate rabbit corneal stromal cells. We developed cationic polymeric nanomicelles loaded celastrol (CPNM) to enhance corneal permeability and achieve sustain drug release. In a rabbit KC model, CPNM treatment attenuated corneal curvature progression, increased stromal thickness, and reduced reactive oxygen species (ROS) levels, as assessed by slit-lamp examination, histology, pachymetry, curvature measurements, and biochemical assays. Immunohistochemistry and immunofluorescence further demonstrated that CPNM downregulated PI3K/AKT/AP-1 pathway and restored Nox/Nrf-2 balance in corneal tissues. In vitro, CPNM suppressed ROS, rebalanced the Nox/Nrf-2 system, inhibited PI3K/AKT/AP-1 activation, and reduced matrix metalloproteinase activity. Our findings indicate that CPNM prevents KC progression by concurrently inhibiting oxidative stress via Nox/Nrf-2 balance and suppressing extracellular matrix degradation via PI3K/AKT/AP-1 signaling axis, positioning it as a promising clinical treatment strategy to halt KC progression.