Short peptide sequence enhances epithelial permeability through interaction with protein kinase C

Area of Science:

• Pharmacology
• Biotechnology
• Cell Biology

Background:

• Intracellular protein kinase C plays a role in regulating epithelial barrier function.
• Enhancing drug permeation across epithelial layers is crucial for effective drug delivery.
• Developing safe and reversible permeation enhancers is a significant challenge in pharmaceutical research.

Purpose of the Study:

• To identify and characterize a novel peptide, L-R5, as a partial inhibitor of protein kinase C.
• To evaluate the potential of L-R5 in modulating epithelial tight junctions for enhanced drug permeation.
• To assess the safety and stability of L-R5 for in vitro and potential in vivo applications.

Main Methods:

• Synthesis and characterization of the pentapeptide L-R5 (myristoyl-ARRWR).
• In vitro assessment of L-R5's effect on epithelial permeability using 4-kDa dextran and naloxone.
• Cytotoxicity evaluation using LDH release assay and ciliary beating frequency tests on primary human nasal epithelial cells.
• Stability testing at 37°C over 24 hours.

Main Results:

• L-R5 application rapidly and transiently increased epithelial permeability in vitro.
• Enhanced apical-to-basolateral (AB) transport of a 4-kDa dextran and a BCS class III drug (naloxone) was observed.
• L-R5 demonstrated stability at 37°C for 24 hours and was non-cytotoxic to primary human nasal epithelial cells.
• Minimal diffusion of L-R5 across epithelial monolayers suggests low systemic bioavailability.

Conclusions:

• L-R5 is a potent, reversible, and non-toxic enhancer of epithelial paracellular permeability.
• The peptide's mechanism involves partial inhibition of protein kinase C and tight junction modulation.
• L-R5 shows significant potential for improving drug delivery across epithelial barriers with a favorable safety profile.