Determination of a Novel Drug Mechanism for Lifitegrast

Abstract

Purpose : Lifitegrast is an immunomodulator that functions by inhibiting the interaction between intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function associated antigen 1 (LFA-1). Exposure of lifitegrast to immortalized human corneal epithelial cells (HCEC) under hyperosmolar stress in the absence of immune cells resulted in reduced IL-1β expression. This suggests that lifitegrast potentially acts on an upstream inflammatory regulator that is independent of lymphocyte activity, potentially caspase-1. The purpose of this work was to predict and validate the ability of lifitegrast to inhibit caspase-1.

Methods : The structure of caspase-1 (1RWX) was obtained from Protein Data Bank and the 3D structure of lifitegrast was obtained from PubChem. The structures were cleaned and energy-minimized prior to performing molecular docking. A caspase-1 inhibitor screening kit was used to quantify the inhibitory activity of several lifitegrast concentrations (vehicle control (0%), 1%, 3%, 5%) against caspase-1. Immortalized HCEC were exposed to hyperosmotic stress for 6 hours in the presence or absence of 3% lifitegrast or a known caspase-1 inhibitor, Z-YVAD-FMK; cytokine concentrations for IL-1β, IL-6, and IL-8 were measured using an electrochemiluminescent multiplex assay.

Results : Molecular docking predicted that lifitegrast occupy the catalytic site of caspase-1 with a binding affinity of -8.7 kcal/mol, directly obstructing the catalytic residues Cys285 and Asp288. The concentration of lifitegrast and relative caspase-1 activity were 1%: 54.2%, 3%: 12.4%, and 5%: 4.4% (all p<0.01 compared to control), demonstrating a dose-dependent reduction of caspase-1 activity with increasing lifitegrast concentration. Both Z-YVAD-FMK and lifitegrast each significantly suppressed the relative expression of IL-1β, IL-6, and IL-8 compared to the vehicle control, in HCEC under hyperosmolar stress (p<0.01 for all cytokines for both compounds).

Conclusions : Lifitegrast potentially acts as a caspase-1 inhibitor, providing an alternative immunomodulatory function in addition to the known inhibition of LFA-1/ICAM-1.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.