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. 2023 Jan 14;13(2):349.
doi: 10.3390/nano13020349.

Effect of Deposition and Protease Digestion on the Ex Vivo Activity of Antimicrobial Peptide-Coated Contact Lenses

Parthasarathi Kalaiselvan  1 , Debarun Dutta  1   2 , Nagaraju V Konda  1   3 , Savitri Sharma  4 , Naresh Kumar  5 , Fiona Stapleton  1 , Mark D P Willcox  1
Affiliations

Effect of Deposition and Protease Digestion on the Ex Vivo Activity of Antimicrobial Peptide-Coated Contact Lenses

Parthasarathi Kalaiselvan et al. Nanomaterials (Basel). .

Abstract

A clinical study of antimicrobial contact lenses containing the cationic peptide Mel4 was conducted. The few adverse events that occurred with this lens occurred on or after 13 nights of wear. The current study examined whether the Mel4 contact lenses lost activity during wear and the mechanism of this loss. Participants wore contact lenses for up to 13 nights. Lenses were tested for their ability to reduce the adhesion of Pseudomonas aeruginosa and Staphylococcus aureus. The amount of protein and lipid extracted from lenses was measured. The ability of trypsin to affect the antimicrobial activity of Mel4-coated contact lenses was measured. Mel4-coated contact lenses lost their antimicrobial activity at six nights of wear for both bacteria. The amount of lipids (13 ± 11 vs. 21 ± 14 μg/lens at 13 nights wear) and proteins (8 ± 4 vs. 10 ± 3 mg/lens at 13 nights of wear) extracted from lenses was not different between Mel4-coated and uncoated lenses, and was not different after three nights when antimicrobial activity was maintained and thirteen nights when they had lost activity (lipid: 25 ± 17 vs. 13 ± 11, p = 0.2; protein: 8 ± 1 vs. 8 ± 4 mg/lens, p = 0.4). Trypsin digestion eliminated the antimicrobial activity of Mel4-coated lenses. In summary, Mel4-coated contact lenses lost antibacterial activity at six nights of wear, and the most likely reason was proteolytic digestion of the peptide. Future studies will design and test proteolytically stable peptide mimics as coatings for contact lenses.

Keywords: Mel4; antimicrobial activity; antimicrobial contact lens; cationic peptide; clinical trial; deposition; protease digestion.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study, collection, analyses, or interpretation of data, writing of the manuscript, or decision to publish the results.

Figures

Figure 1
Figure 1
Bacterial adhesion to Mel4-coated and control contact lenses worn for up to 13 nights for (A) P. aeruginosa and (B) S. aureus.
Figure 2
Figure 2
Amount of protein (A) and lipid (B) deposited on Mel4-coated and control lenses during wear.
Figure 3
Figure 3
SDS-PAGE of extracts from worn etafilcon A contact lenses. C = control lenses; M = Mel4-coated lenses; numbers on the x-axis denote different patients. S = standards of known molecular mass.
Figure 4
Figure 4
Effect of trypsin treatment on the numbers of S. aureus cells adhering to contact lenses coated with Mel4.
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