Abstract
Purpose :
Glycoprotein 340 and its first scavenger receptor cysteine-rich (SRCR1) promote the pathogenesis of microbial infections when they immobilize on mucosal surfaces. Preliminary studies also show Gp340/SRCR1 immobilizes on soft contact lens polymers. This study thus aimed at investigating the effect of immobilized Gp340’s SRCR1 domain on bacterial adhesion of soft contact lens polymers.
Methods :
Briefly, three lenses each of etafilcon A and lotrafilcon B were soaked/incubated in 1.2 mL of purified SRCR1 at the following concentrations: 5000, 500 and 50 pg/µL for 12 h. 500 pg/µL is within the physiological range of tear Gp340 concentration. As a control, an equal number of lenses was soaked in 1.2 mL of PBS (n = 12 lenses/polymer). After incubation, each lens was rinsed three times with PBS to remove any unbound SRCR1. Subsequently, each lens was placed in 1.2 mL of bacterial suspension in PBS (optical density of 0.1 at 660 nm) containing either P. aeruginosa 6206 or S. aureus 31 and incubated at 37°C for 24 h. Thereafter, each lens was rinsed three times in PBS and shaken for 30 s to remove loosely adhered bacteria. To detach the adhered bacteria, each lens was resuspended in 1.5 mL and after the addition of 200 uL of 0.25% Trypsin-EDTA and a magnetic stir bar, it was vortexed for 1 min. The total amounts of adherent bacteria were measured using the bacterial viability assay kit (Abcam, Cambridge, MA, USA) following the manufacturer’s protocol.
Results :
Across the two lens polymers, the amount of adherent bacteria was higher for SRCR1-coated lenses compared to the uncoated lenses, for both bacterial species (Mann-Whitney U test, p < 0.05). For both polymers, the amount of bacterial adhesion differed significantly amongst the various concentrations of the coating SRCR1 solution (Kruskal-Wallis H test, p < 0.05). The amount of bacterial adhesion on SRCR1-coated lens was higher for lotrafilcon B compared with etafilcon A (680487 versus 595081 count/lens for S. aureus, 692048 versus 582506 count/lens for P. aeruginosa; Mann-Whitney U test, p < 0.05).
Conclusions :
Gp340’s SRCR1 domain promotes the adhesion of S. aureus andP. aeruginosa on lotrafilcon B and etafilcon A. Further investigations are needed to elucidate the role of Gp340/SRCR in the pathogenesis of contact-lens related microbial infections.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.