Abstract
Purpose :
Cataract has historically been the leading cause of human blindness worldwide. The success of cataract surgery (CS) is markedly compromised by acute postoperative inflammation and the later development of posterior capsular opacification. Previously we have shown that the lens epithelium drastically remodels its transcriptome by 6H post CS. Notably, the genes upregulated at 6H post CS were highly enriched in immediate early transcription factors (IETF) like FosB and Egr1 and numerous proinflammatory cytokines, although fibrotic genes were not yet induced. However, the molecular mechanisms by which CS acutely induces an upregulation in IETFs in lens epithelial cells (LECs) is not known.
Methods :
Wildtype mice were subjected to lens fiber cell removal to model CS; immunostaining and image analysis were assessed at 6H post CS. ERK inhibitor, U0126, was introduced via intraocular injections immediately following lens fiber cell removal to assess effect of ERK/MAPK signaling on IETF expression in wildtype mice. Subsequent IETF changes were confirmed by immunostaining WT LECs post CS. Dual GFP-luc NFkappaB reporter mouse [FVB.Cg-Tg(HIV-EGFP,luc)8Tsb/J] were subjected to lipopolysaccharide (LPS) tail-vein injections to assess LEC responsiveness to PAMP signaling; changes were validated via luciferase assay and immunostaining LECs post CS.
Results :
While LECs did activate NFkappaB signaling in response to LPS, damage associated molecular pattern (DAMP) or pattern association recognition pattern (PAMP) pathways are unlikely to drive the initial response of LECs to injury since the reporter was only intermittently activated prior to 72H post CS. In contrast, immunostaining revealed that ERK/MAPK signaling, which is known to induce IETF expression in other systems, upregulates rapidly in LECs post CS. Furthermore, treatment of mice with the ERK inhibitor, U0126, at the time of lens fiber removal prevented the upregulation of FosB and Egr1 protein expression at 6H post CS.
Conclusions :
Acute activation of ERK post CS may be a major mediator of IETF upregulation in remnant LECs after CS. As IETFs can regulate the expression of inflammatory and fibrotic genes, this may explain how LECs remodel their transcriptome post CS. Work to assess how lens injury triggers acute ERK activation and/or the inflammatory response is currently under investigation.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.