Abstract
Purpose :
Previously we have shown that contact lens wear can induce corneal para-inflammation, involving several types of immune cells: e.g. CD11c+, Lyz2+ and γδ-T cells after 24 h of wear, γδ-T cells, Lyz2+ cells and Ly6G+ cells (neutrophils) after 6-7 days wear. Here, we tested the hypothesis that contact lens wear protects corneas against adhesion by commensal bacteria.
Methods :
LysMcre mice were used to image corneal Lyz2+-GFP cells (myeloid-derived). One eye of each mouse was fitted with a custom-made contact lens (CL); contralateral eyes did not wear lenses (NCL). After 4-6 days lens wear, mice were anesthetized and corneas superficially-injured by tissue paper blot to promote bacterial adhesion. Eyes were inoculated with 5 μl of ~1011 CFU/mL Macrococcus spp. (a murine eyelid commensal) each hour for 4 h. Mice were euthanized and enucleated eyes fixed in 2% paraformaldehyde overnight and a universal bacterial 16S rRNA FISH probe used to label adherent bacteria. Confocal microscopy was used to quantify bacterial adhesion, epithelial traversal and Lyz2+ cells using Imaris software. Student’s t-test was used for statistical analysis. P < 0.05 was considered significant.
Results :
Contact lens wear increased corneal Lyz2+ cell numbers compared to no lens wear: CL 58.6 ± 7.3 vs. NCL 36 ± 4.6 cells/field of view (mean ± SEM, P < 0.05). Moreover, more Lyz2+ cells were found within the corneal epithelium or extending processes into the epithelium: CL 3.7 ± 0.5 vs. NCL 1.6 ± 0.5 cells/field of view (P < 0.05). Lens-wearing corneas showed significantly fewer adherent bacteria than no lens wear: CL 175.7 ± 59.3 vs. NCL 454 ± 190.7 bacteria/field of view (P < 0.05). However, adherent bacteria traversed further into the epithelium with lens wear: CL 4.5 ± 0.5 vs NCL 2.2 ± 0.2 μm (P < 0.0001).
Conclusions :
Contact lens wear induces corneal parainflammation and also protects superficially-injured corneas against adhesion of commensal bacteria. The role of lens-induced parainflammation in protecting against bacterial colonization remains to be determined, as does the significance of deeper epithelial penetration by colonizing bacteria in lens-wearing corneas.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.