RNA-Seq Analysis Reveals an Essential Role of the Tyrosine Metabolic Pathway and Inflammation in Myopia-Induced Retinal Degeneration in Guinea Pigs

Abstract

Myopia is the second leading cause of visual impairment globally. Myopia can induce sight-threatening retinal degeneration and the underlying mechanism remains poorly defined. We generated a model of myopia-induced early-stage retinal degeneration in guinea pigs and investigated the mechanism of action. Methods: The form-deprivation-induced myopia (FDM) was induced in the right eyes of 2~3-week-old guinea pigs using a translucent balloon for 15 weeks. The left eye remained untreated and served as a self-control. Another group of untreated age-matched animals was used as naïve controls. The refractive error and ocular biometrics were measured at 3, 7, 9, 12 and 15 weeks post-FDM induction. Visual function was evaluated by electroretinography. Retinal neurons and synaptic structures were examined by confocal microscopy of immunolabelled retinal sections. The total RNAs were extracted from the retinas and processed for RNA sequencing analysis. Results: The FDM eyes presented a progressive axial length elongation and refractive error development. After 15 weeks of intervention, the average refractive power was −3.40 ± 1.85 D in the FDM eyes, +2.94 ± 0.59 D and +2.69 ± 0.56 D in the self-control and naïve control eyes, respectively. The a-wave amplitude was significantly lower in FDM eyes and these eyes had a significantly lower number of rods, secretagogin+ bipolar cells, and GABAergic amacrine cells in selected retinal areas. RNA-seq analysis showed that 288 genes were upregulated and 119 genes were downregulated in FDM retinas compared to naïve control retinas. In addition, 152 genes were upregulated and 12 were downregulated in FDM retinas compared to self-control retinas. The KEGG enrichment analysis showed that tyrosine metabolism, ABC transporters and inflammatory pathways were upregulated, whereas tight junction, lipid and glycosaminoglycan biosynthesis were downregulated in FDM eyes. Conclusions: The long-term (15-week) FDM in the guinea pig models induced an early-stage retinal degeneration. The dysregulation of the tyrosine metabolism and inflammatory pathways may contribute to the pathogenesis of myopia-induced retinal degeneration.

RNA-sequencing analysis reveals the long noncoding RNA profile in the mouse myopic retina

“…Similarly, four sclerae were pooled to form one sample in the bulk transcriptome sequencing ( Zhao et al, 2021 ). Vocale et al identified ligand-gated chloride efflux channels as a major pathway contributing to chick FDM using RNA-seq and gene set enrichment analysis, with four replicates (4 chicks) per condition ( Vocale et al, 2021 ); and sample size of three or four replicates (3 or 4 guinea pig eyes) in the RNA-seq study to investigate the gene expression and pathways in sclera was also reported ( Srinivasalu et al, 2018 ; Zeng et al, 2021 ). The current study included six replicates per experimental condition (FDM or contralateral control, with 3 retinas pooled per replicate), much more than the previous reported RNA-seq datasets, hoping to increase the confidence of our RNA-seq data.…”

“…After the induction of FDM, the refractive error was measured by cycloplegic streak retinoscopy in the current study, which would possibly produce measurement error. Refraction in previous study was assessed by various methods, including automated eccentric infrared photorefractor ( Schaeffel et al, 2004 ; Wu et al, 2018 ) and streak retinoscopy by optometrist ( Huang et al, 2019 ; Zeng et al, 2021 ). In our study, the optometrist and the researchers who bled and built the model were different, and optometrist was masked to the treatment status of the eyes during measurements of refractive errors.…”

LncRNA-XR_002792574.1-mediated ceRNA network reveals potential biomarkers in myopia-induced retinal ganglion cell damage

“…All eyes in the NCG were untreated. The right eyes in the FDM group were occluded with latex balloons as translucent masks for 8 weeks as previously described [ 23 ], and the fellow eyes remained unoccluded. Throughout the entire experiment, care was taken to ensure that the right eye remained completely covered but that the animal could blink freely.…”

Exploring the relationship between intestinal flora and the pathological mechanism of myopia in adolescents from the perspective of Chinese and Western medicine: A review

“…Dysregulation of inflammatory pathways may contribute to the pathogenesis of myopic retinal degeneration, specifically including upregulation of the AGE-RAGE signaling pathway, complement cascade, NOD-like receptor signaling pathway, IL-17 signaling pathway, and TNF signaling pathway, while downregulation of antigen processing and cell adhesion pathways. [ 19 ] In addition, CCL2, [ 20 ] IL-6, matrix metalloproteinase-2, and angiopoietin-1 levels are higher in highly myopic eyes. [ 21 , 22 ] It can be seen that the inflammatory response may be involved in the development and progression of myopia through altered signaling pathways and the production of inflammatory factors, but it is unclear whether the inflammatory response is a consequence or a cause of myopic retinal degeneration.…”