Abstract
Purpose :
To elucidate the role of IL-1Ra and IL-36Ra in controlling corneal inflammation and innate immunity in C47BL/6 mouse model of Pseudomonas aeruginosa keratitis.
Methods :
Scarified B6 mouse corneas inoculated with 104 P. aeruginosa. At 6 hpi, epithelial cells were scraped off the cornea and IL-36α, β, γ, and IL36Ra expressions were detected by PCR. To determine the role of IL-1 and IL-36 signaling in P. aeruginosa keratitis, the corneas of B6 mouse corneas were treated with siRNA of IL-1Ra or IL-36Ra or recombinant IL-36γ, followed by P. aeruginosa inoculation. Disease progress was monitored by digital photograph, clinical scoring, and MPO measurement for PMN infiltration. The expressions of various pro-inflammatory and innate defense gene were determined by real-time PCR.
Results :
P. aeruginosa infection induced the expressions of IL-1β, IL-1Ra, IL-36α and IL-36γ, but not IL-36β and IL-36Ra in mouse CECs. While downregulation of IL-1Ra greatly increased severity of keratitis, IL-36Ra siRNA treatment protected B6 mouse corneas from P. aeruginosa infection, including markedly decreases in bacterial burden and PMN infiltration. Knockdown IL-36Ra induce upregulation AMPs while IL-1RA Knockdown downregulate the expression of AMPs. Topical application of IL-36γ ameliorated P. aeruginosa keratitis, downregulate and up-regulated defensing-3, s100a8 and ISG15 expression in the cornea.
Conclusions :
IL-36 is induced during infection in the cornea, where it promotes bacterial clearance and regulates the appropriateness and intensity of innate immune responses. Topical IL-36 + IL-1Ra may be used prophylactically post ocular surgery or as an adjunctive therapy to treat microbial keratitis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.