Abstract
Purpose :
Our previous work has shown that topical adjunctive Tβ4 + ciprofloxacin treatment reduces inflammatory mediators, while enhancing bacterial killing in Pseudomonas-infected corneas. The goal of this study was to examine how Tβ4 influences PMN and macrophage effector cell function, leading to enhanced host defense.
Methods :
This work uses an experimental model of bacterial keratitis carried out in 8-week-old, female C57BL/6J (B6) mice. The left eye of each mouse was infected with P. aeruginosa 19660 and after 24 hours animals were randomized to 4 different groups, which included Tβ4, ciprofloxacin, Tβ4 + ciprofloxacin and PBS (control) administered as a topical eye drop 3x per day. Flow cytometry was initially carried out to determine the phenotype of infiltrating PMN and macrophage in the cornea. Generation of ROS/RNS, proteases, markers of NETosis, SPM and efferocytosis were determined through immunostaining, ELISA, Western blot and real-time RT-PCR to assess the influence of Tβ4 on PMN and macrophage cellular function. PMN and macrophage were isolated, cultured, stimulated and treated with corresponding reagents for in vitro analysis. Cell lysates were collected and analyzed to confirm the influence of Tβ4 on PMN and macrophage cellular function.
Results :
Tβ4 treated animals displayed a similar disease response to PBS controls. However, mice treated with the adjunctive Tβ4 treatment displayed a significant improvement in disease outcome compared to PBS, Tβ4, and most remarkably ciprofloxacin. Flow cytometry data indicates that the Tβ4 + ciprofloxacin mice have decreased PMN and macrophage with a distinct phenotypic profile compared to all other treatment groups. These results correlated with functional differences as observed from changes in ROS/RNS production, NETosis and activation of SPM pathways.
Conclusions :
Collectively, these data provide further evidence that use of adjunctive Tβ4 + ciprofloxacin treatment provides a more efficacious option for treating bacterial keratitis. Not only does the adjunctive therapy address both the infectious pathogen and corneal wound healing response, but it also influences inflammatory cell function as indicated by the current study. Tβ4 stimulates the switch from an inflammatory phenotype to a resolution phenotype in PMN and macrophage, which contributes to an enhanced host defense and improved tissue repair.
This is a 2020 ARVO Annual Meeting abstract.