Abstract
Purpose :
There are no effective therapies to alleviate corneal injury from chloropicrin (CCl3NO2, trichloronitromethane, CP) exposure, a broad spectrum fumigant and pesticide which has been employed as a warfare agent. CP exposure-induced eye injury is associated with lacrimation and inflammation which involves corneal edema and damage. Based on completed mechanistic studies, we tested the efficacy of beta-glucogallin (BGG), a natural antioxidant and anti-inflammatory agent with anti-lipid peroxidation and carbonyl scavenger properties, hypothesized as an effective therapy against CP-induced corneal injury.
Methods :
Efficacy studies were carried out in primary human corneal epithelial (HCE) cells following 30 min exposure to 50 µM CP with and without treatment with either 50 µM BGG or a perfluorocarbon oxygen emulsion. Western blot analysis was assessed 24 h post exposure to determine the CP-induced effects on various molecular markers. CP injury was induced in ex vivo rabbit corneas by exposing the corneas to 200 nmol CP for 2 h, followed by washing and treatment with 10 µl of 500 µM BGG and thereafter every 6 h for 24 h. Corneal tissue was prepared for subsequent histological (H&E staining), immunohistochemical, and western blot analyses.
Results :
In primary HCE cells, BGG treatment reduced CP-induced increases in cleaved PARP by 35%, H2A.X phosphorylation by 40%, MAPK-JNK phosphorylation by 43%, protein carbonylation (biotin hydrazide) by 56%, and a complete reversal in lipid peroxidation (4-hydroxynonenal, 4-HNE). Preliminary studies in HCE cells indicate that application of the oxygen emulsion reduced CP-induced phosphophorylated-p53 and cleaved PARP. In ex vivo rabbit corneas, BGG treatment resulted in a 31% reversal in CP-induced epithelial degradation and complete reversal in CP-induced COX-2 expression and protein carbonylation.
Conclusions :
These data suggest strong potential for BGG in reversing CP-induced lipid peroxidation and protein carbonylation as well as reducing epithelial degradation and inflammation in rabbit cornea when given 2 h after CP exposure. Further studies expanding the examination of BGG alone or in combination with oxygen emulsion in alleviating CP- and other chemical agents-induced ocular injury, and delineation of its targets and pathways is justified.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.