Human lens epithelial cells induce the inflammatory response when placed into the lens capsular bag model of posterior capsular opacification

Abstract

Purpose: Cataracts are typically treated by phacoemulsification followed by intraocular lens implantation. Studies of mouse models of cataract surgery have revealed that lens epithelial cells rapidly remodel their transcriptome to express proinflammatory cytokines after lens fiber cell removal, but it is currently unknown whether this response is conserved in human lenses. This study seeks to fill this knowledge gap.

Methods: Human cadaver eyes from 70 to 89 year old individuals were prepared for the human capsular bag model of cataract surgery. The central epithelium was preserved in RNAlater during culture preparation, then the equatorial epithelium was either immediately preserved in RNAlater after the culture was created, or 24 h later. Gene expression profiles were generated by bulk sequencing of RNA isolated from these tissue samples. The transcriptomic response of human cadaver-derived lens epithelial cells to culture in this "capsular bag" model was characterized by bioinformatic analysis. The human response was directly compared to that of 24-month-old mouse lens epithelial cells subjected to fiber cell removal surgery.

Results: Human lens epithelial cells remodel approximately a third of their transcriptome by 24 h after surgery, and like mice, this response consists of induction of proinflammatory cytokine genes, upregulation of fibrotic markers and downregulation of genes controlling the lens epithelial phenotype.

Conclusions: These observations demonstrate that humans and mice have similar responses to cataract surgery and support the use of mice to study the response of lens epithelial cells to cataract surgery, suggesting that identified injury response mechanisms can be leveraged to elucidate new approaches to improve the outcomes of cataract surgery.

Figure 1

Principal component analysis (PCA) for the human central epithelial cells at 0H and equatorial epithelial cells at 0H and 24H culture. The circles represent the central epithelial cells while the triangles represent the equatorial epithelial cells. The color red represents the 0H culture time point and blue represents the 24H culture time point. Note that two of the 24H equatorial LECs samples (right most triangles) are nearly entirely overlapping. y/o (years old) signifies the age of each donor. Additional details can be found in Appendix 1.

Figure 2

Advaita iPathway analysis of differentially expressed pathways/genes between central lens epithelial compared to equatorial epithelial. A: Bar graph showing the “differentially expressed pathway genes on calcium signaling pathway (p-value 1.65E-6) expressed more highly in the 0H human equatorial LECs. B: Bar graph showing the “differentially expressed genes annotated to epithelial cell proliferation” (p value 3.600E-4) expressed more highly in the 0H human equatorial LECs. C: Bar graph showing the “differentially expressed genes annotated with cell adhesion” (p value 4.400E-18) expressed more highly in the 0H human equatorial LECs. D: Bar graph showing the “differentially expressed genes annotated with cell junction assembly” (p value 8.700E-8) expressed more highly in the 0H human equatorial LECs. E: Bar graph showing the “differentially expressed genes annotated with cation transport” (p value 2.500E-8) expressed more highly in the 0H human equatorial LECs. Red bars are genes that are expressed more highly in the equatorial lens epithelial cells compared to central lens epithelial cells. Blue bars are genes that are expressed more highly in central lens epithelial cells compared to equatorial lens epithelial cells.

Figure 3

Advaita iPathway analysis of differentially expressed pathways/genes between 0H and 24H human equatorial lens epithelial cells. A: Impact analysis of the DEGs suggest that the KEGG pathway map “cytokine-cytokine receptor interaction” (yellow dot) is likely to be the most significantly impacted pathway in the 24H human equatorial LECs. B: Bar graph showing the cytokine-cytokine receptor interaction genes that are differentially expressed in the 24H human equatorial LECs. C: Impact analysis showing that the second most significant pathway in the 24H human equatorial LECs represent genes involved in the “neuroactive ligand-receptor interaction” pathway (yellow dot). D: Bar graph showing the “neuroactive ligand-receptor interaction” pathway genes differentially expressed in the 24H human equatorial LECs. E) Bar graph showing the “epithelial to mesenchymal transition” pathway genes differentially expressed in the 24H human equatorial LECs.