Abstract
Purpose :
While surgical treatment of cataract is highly effective, it also results in ocular inflammation which has the potential to exacerbate other ocular diseases while also contributing to posterior capsular opacification (PCO). Though the pathogenesis of post surgical inflammation is unclear, we discovered that the lens epithelial cells (LECs) remaining behind post cataract surgery (PCS) rapidly upregulate inflammatory cytokine expression. While the mechanisms underlying this upregulation are unknown, NFkB signaling pathways regulate cytokine expression in other systems. Further, Alexander et al. 2003 showed that the lens rapidly elicited NFkB signaling when treated with known inducer, lipopolysaccharide (LPS). The objective of this study is to investigate the dynamics of NFkB pathway activation post lens injury and to elucidate its potential role in inflammation and PCO.
Methods :
The Lens Injury Response Time Course (LIRTS), a database of mouse LEC transcriptome profiles generated from multiple time points post lens fiber cell removal, was used to reveal expression dynamics of NFkB signaling components in naive and injured mouse lenses. NFkB signaling was studied by subjecting a dual GFP-luciferase NFkB reporter mouse [FVB.Cg-Tg(HIV-EGFP, luc)8Tsb/J] to lens fiber cell removal surgery.
Results :
LIRTS analyses revealed that several components of the NFkB signaling pathway, RelA, RelB, NFkBia, and Map3k8 upregulate their mRNA levels in LECs at 6 hours post injury, trend down at 24 hours and reach baseline by post 5 days. In contrast, the NFkB target gene, Il1b, first upregulates at 24 hours PCS. Little to no NFkB reporter activity was observed in naive adult mouse lenses; however, LECs remaining behind following fiber cell removal exhibited significant reporter gene activity at 6, 24 and 48 hours PCS, with maximal activity at 48 hours PCS which trended down by 72 hours.
Conclusions :
The observation that components of the NFkB signaling pathway are expressed at the mRNA level in naive LECs is consistent with prior reports finding that the lens is responsive to LPS induction of the NFkB pathway. The further upregulation of the mRNA levels of NFkB pathway components PCS and the induction of NFkB reporter activity PCS suggests that this pathway may play important roles in post surgical inflammation and PCO pathogenesis. Future work will test the function of the NFkB pathway in the lens injury response.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.