Abstract
Purpose :
We have recently identified a novel role for the insulin-like growth factor binding protein-3 (IGFBP-3) in the mitoprotection of corneal epithelial cells subject to hyperosmolar stress, a key underlying event in the pathophysiology of dry eye disease (DED). In non-ocular tissues, mtDNA that is released by damaged mitochondria has been linked to NLRP3 inflammasome activation. The purpose of this study was to investigate the effects of IGFBP-3 on the NLRP3 inflammasome in the corneal epithelium in vivo using a botox-induced aqueous deficient dry eye mouse model.
Methods :
Male and female C57BL6/N mice aged 6-8 weeks of age were used in this study. To induce DED, botulinum toxin was injected into the exorbital lacrimal gland of one eye. Saline was used as a vehicle in control mice. The reduction in aqueous tear production was confirmed using a phenol red thread test. Animals were subject to aqueous deficient DED for 4 weeks. During the final week, corneas were treated topically with exogenous recombinant IGFBP-3. Corneal staining with fluorescein was imaged using a slit lamp biomicroscope equipped with a digital camera. Staining was quantified in all five quadrants of the cornea using the NEI grading scale. Corneas were visualized by hematoxylin and eosin staining and immunofluorescence (IF). Ki-67 was used to measure proliferation. Expression and activation of the NLRP3 inflammasome and inflammatory cytokines were further assessed by western blot and enzyme linked immunoassays.
Results :
Corneal staining was increased in aqueous deficient corneas. This was associated with an increase in expression of the NLRP3 inflammasome and IL-1b. There was also a corresponding increase in the number of Ki67-positive cells in the basal layer of the corneal epithelium. These effects were all attenuated by topical treatment with exogenous IGFBP-3. Interestingly, exogenous IGFBP-3 had no effect on expression of IL-6.
Conclusions :
Taken together, these findings suggest that IGFBP-3 may play a key role in modulating the NLRP3 inflammasome in DED. Further studies are needed to investigate this mechanism.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.