Self-assembled non-steroidal anti-inflammatory drug-peptide hydrogel to effectively mitigate ocular inflammation

Pranoprofen (Pra) eye drop has been widely used in clinical practice for the efficient mitigation of ocular inflammation, but it often suffers from poor bioavailability owing to the existence of various ocular barriers (i.e. tear barrier and corneal epithelial barrier). In this study, we rationally designed and synthesized a Pra-peptide conjugate using a D-form tripeptide (i.e. phenylalanine-phenylalanine-aspartic acid; ffd) motif, and the resulting conjugate (i.e. Pra-ffd) spontaneously self-assembled into single-component supramolecular hydrogel for efficient mitigation of ocular inflammation. The generated hydrogel was thoroughly characterized using a rheometer and transmission electron microscopy (TEM). The proposed Pra-ffd hardly caused cytotoxicity in RAW 264.7, L929, and human corneal epithelial cells (HCEC). The Pra-ffd hydrogel dose-dependently reduced the levels of proinflammatory cytokines (e.g. PGE₂, TNF-α, and IL-6) and intracellular reactive oxygen species (ROS) accumulation in lipopolysaccharide (LPS)-activated RAW 264.7 macrophage. In addition, topical instillation of the Pra-ffd hydrogel exhibited good ocular tolerance and prolonged precorneal retention (>20 min), resulting in higher bioavailability compared with the Pra solution. Using an endotoxin-induced uveitis (EIU) rabbit model, we demonstrated that topical instillation of Pra-ffd hydrogel effectively mitigated the inflammatory response in the anterior chamber and significantly reduced the entry of inflammatory cells from the circulation by preserving the integrity of the blood-aqueous humor barrier. Overall, the Pra-ffd hydrogel represents a promising ocular drug delivery platform for the treatment of inflammatory ocular disorders.