Abstract
Purpose :
PAX6 haploinsufficiency has a pivotal role in the chronic development of Aniridia Related Keratopathy, a rare congenital eye condition leading to vision loss. The serotonin reuptake inhibitor Duloxetine has been recently identified among a variety of tested compounds as potent in upregulating PAX6 gene and protein expression in vitro. This study focused on confirming this result in vivo in the wild-type mouse cornea and exploring the outcome of duloxetine administration in a mouse model of LPS-induced corneal inflammation.
Methods :
Male C57Bl6/J mice aged 5-7 weeks were treated with Duloxetine after LPS stimulation. The drug delivery schemes evaluated were i) intrastromal injection; ii) subconjuctival injection; and iii) eyedrop delivery, twice or four times daily for 2 or 7 days. The evaluated dosage ranges were from 1μM to 50μΜ. We scored corneal opacification and haze with slit lamp microscopy, assessed inflammatory cell infiltration into the cornea with in vivo confocal microscopy, and measured PAX6 and inflammatory protein concentration by Western blot. In selected experiments we performed transcriptome analysis with the GeneChip Mouse Gene technology for the in-depth evaluation of differential inflammatory signaling.
Results :
Duloxetine administration consistently upregulated PAX6 within the corneal tissue at concentrations of 1μΜ when injected and 10μΜ when administered as eye drops. Interestingly, Duloxetine also had in some setups a moderate effect of inflammatory infiltration enhancement in quantitative cell counts, and inflammatory cytokine increase was also observed. Qualitatively, Duloxetine groups tended to have larger round cell infiltration, in contrast to controls with smaller invading cells that in many cases defined the outer shape of stromal keratocytes. Our transcriptomic analysis identified the differential expression of inflammatory and other key pathways and transcripts.
Conclusions :
Duloxetine is a promising pharmacological intervention for the in vivo upregulation of corneal PAX6 expression. Given its status as an approved and generic drug, it could be a promising therapy in the treatment of PAX6-related deficiency like in aniridia. More in vivo studies are required, however, for a detailed understanding of its interaction with inflammatory pathways, and the evaluation of its effects in PAX6 insufficient models relative to a model where PAX6 is overexpressed.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.