Project description:Retinal metabolic changes have been suggested to be associated with myopia development. However, little is known about either their identity or time dependent behavior during this sight compromising process. To address these questions, gas chromatography time-of-flight mass spectrometry (GC-TOF/MS) was applied to compare guinea pig retinal metabolite levels in form deprivation (FD) eyes at 3 days and 2 weeks post FD with normal control (NC) eyes. Orthogonal partial least squares (OPLS) models discriminated between time dependent retinal metabolic profiles in the presence and absence of FD. Myopia severity was associated with more metabolic pattern differences in the FD than in the NC eyes. After 3 days of FD, 11 metabolite levels changed and after 2 weeks the number of differences increased to 16. Five metabolites continuously decreased during two weeks of FD. Two-way ANOVA of the changes identified by OPLS indicates that 15 out of the 22 metabolites differences were significant. Taken together, these results suggest that myopia progression is associated with an inverse relationship between increases in glucose accumulation and lipid level decreases in form-deprived guinea pig eyes. Such changes indicate that metabolomic studies are an informative approach to identify time dependent retinal metabolic alterations associated with this disease.
Project description:Myopia has become the major cause of visual impairment worldwide. Although the pathogenesis of myopia remains controversial, proteomic studies suggest that dysregulation of retinal metabolism is potentially involved in the pathology of myopia. Lysine acetylation of proteins plays a key role in regulating cellular metabolism, but little is known about its role in the form-deprived myopic retina. Hence, a comprehensive analysis of proteomic and acetylomic changes in the retinas of guinea pigs with form-deprivation myopia was performed. In total, 85 significantly differential proteins and 314 significantly differentially acetylated proteins were identified. Notably, the differentially acetylated proteins were markedly enriched in metabolic pathways such as glycolysis/gluconeogenesis, the pentose phosphate pathway, retinol metabolism, and the HIF-1 signaling pathway. HK2, HKDC1, PKM, LDH, GAPDH, and ENO1 were the key enzymes in these metabolic pathways with decreased acetylation levels in the form-deprivation myopia group. Altered lysine acetylation of key enzymes in the form-deprived myopic retina might affect the dynamic balance of metabolism in the retinal microenvironment by altering their activity. In conclusion, as the first report on the myopic retinal acetylome, this study provides a reliable basis for further studies on myopic retinal acetylation.
Project description:Myopia has become the major cause of visual impairment worldwide. Although the pathogenesis of myopia remains controversial, proteomics studies suggest that dysregulation of retinal metabolism is potentially involved in the pathology of myopia. Lysine acetylation of proteins plays a key role in regulating cellular metabolism, but little is known about its role in the form-deprived myopic retina. In this study, we performed acetylation proteomic analysis of the retinas of form-deprived myopic guinea pigs and found downregulated levels of acetylation of metabolism-critical enzymes in the retina. As the first report on retinal acetylation in myopic eyes, this study provides a reliable basis for further studies on retinal acetylation in myopic eyes
Project description:BackgroundThe use of ocular hypotensive drugs has been reported to attenuate myopia progression. This study explores whether brimonidine can slow myopia progression in the guinea pig form-deprivation (FD) model.MethodsThree-week-old pigmented male guinea pigs (Cavia porcellus) underwent monocular FD and were treated with 3 different methods of brimonidine administration (eye drops, subconjunctival or intravitreal injections). Four different concentrations of brimonidine were tested for intravitreal injection (2 μg/μL, 4 μg/μL, 20 μg/μL, 40 μg/μL). All treatments continued for a period of 21 days. Tonometry, retinoscopy, and A-scan ultrasonography were used to monitor intraocular pressure (IOP), refractive error and axial length (AL), respectively. On day 21, guinea pigs were sacrificed for RNA sequencing (RNA-seq) to screen for associated transcriptomic changes.ResultsThe myopia model was successfully established in FD animals (control eye vs. FD eye, respectively: refraction at day 20, 0.97 ± 0.18 D vs. - 0.13 ± 0.38 D, F = 6.921, P = 0.02; AL difference between day 0 and day 21, 0.29 ± 0.04 mm vs. 0.45 ± 0.03 mm, F = 11.655, P = 0.004). Among the 3 different brimonidine administration methods, intravitreal injection was the most effective in slowing myopia progression, and 4 μg/μL was the most effective among the four different concentrations of brimonidine intravitreal injection tested. The AL and the refraction of the brimonidine intravitreal injection group was significantly shorter or more hyperopic than those of other 2 groups. Four μg/μL produced the smallest difference in AL and spherical equivalent difference values. FD treatment significantly increased the IOP. IOP was significantly lower at 1 day after intravitreal injections which was the lowest in FD eye of intravitreal injection of brimonidine. At day 21, gene expression analyses using RNA-seq showed upregulation of Col1a1 and Mmp2 expression levels by intravitreal brimonidine.ConclusionsAmong the 3 different administration methods, intravitreal injection of brimonidine was the most effective in slowing myopia progression in the FD guinea pig model. Intravitreal brimonidine at 4 μg/μL significantly reduced the development of FD myopia in guinea pigs. Expression levels of the Col1a1 and Mmp2 genes were significantly increased in the retinal tissues of the FD-Inj-Br group.
Project description:PurposeThe development of myopia in guinea pigs can be inhibited by attenuating scleral hypoxia by increasing choroidal blood perfusion (ChBP). In this study, we reduced ChBP through surgical and pharmacological methods to determine the effect on myopia development. We also determined whether ChBP was reduced by quinpirole, a drug that enhances form-deprivation myopia (FDM).MethodsChBP was reduced in the right eyes of guinea pigs via transection of the temporal ciliary arteries or daily injections of phenylephrine into the inferior peribulbar space for one week during normal ocular growth. Other guinea pigs were subjected to two weeks of monocular FDM-with facemasks, along with daily injections of quinpirole, a dopamine D2 receptor agonist, to enhance the FDM. Changes in refraction, axial length, ChBP, and choroidal thickness (ChT) were measured in both treated and fellow eyes of the treatment and control groups. Scleral hypoxia labeling with pimonidazole adducts and α-smooth muscle actin (α-SMA) protein were also measured.ResultsSurgical and pharmacological reduction of ChBP induced myopia development in the treated eyes. These treatments rendered the scleral hypoxia and increased scleral α-SMA expression. Furthermore, quinpirole injections, which increased the magnitude of myopia, augmented the FDM-associated reductions in ChBP and ChT and increased the levels of scleral hypoxia and α-SMA protein.ConclusionsDecreased ChBP in guinea pigs leads to scleral hypoxia and scleral myofibroblast transdifferentiation with increased α-SMA expression, ultimately resulting in myopia development. In future clinical trials, ChBP reduction can serve as a potential biomarker for early detection of myopia development.
Project description:The sclera is the target organ of axial elongation during myopia onset and progression. Visualizing the sclera in-vivo is important for monitoring the dynamic changes of the sclera remodeling in experimental myopia. In the present study, three-week-old tricolor guinea pigs were subjected to negative controls (n = 8), monocular negative lens-induced myopia (LIM, n = 10), or combining monocular LIM and intravitreally mTORC1 agonist (MHY1485, 4 µg) injection for inducing high myopia (LIM + MHY1485 group, n = 10) for four weeks. Serial biometric measurements were performed to monitor experimental myopia onset and progression. Swept-source optical coherence tomography (SS-OCT) was performed to measure sclera thickness at the beginning and end of study. The results showed four weeks of LIM and LIM + MHY1485 induced a significant degree of myopia shift, compared to the negative control (Control, -2.04 ± 0.60; LIM - 6.21 ± 0.55; LIM + MHY1485, -9.14 ± 1.11, diopters, P < 0.0001). The cross-sectional SS-OCT showed clear boundaries of the inner and outer boundaries of the sclera. At baseline, the mean sclera thickness was 105.05 ± 5.41 μm. At the end of the study, sclera thickness significantly correlated with axial length (coefficient = -4.49 μm for every 0.1 mm axial length increase, 95%CI: -3.56 to -5.83 μm, P < 0.001) and refractive error (coefficient = -2.77 μm for every 1 diopter myopic shift, 95%CI: -2.06 to -3.47 μm, P < 0.001) among all guinea pigs. Sclera thickness also significantly correlates with choroidal thickness and choroidal vascularity index (%). In conclusion, the present study shows SS-OCT can be used as a non-invasive method to evaluate sclera thickness and monitor myopia progression in the guinea pig model of LIM.
Project description:Myopia has become the major cause of visual impairment worldwide. However, its retina-related pathogenesis remains unclear. In recent years, proteomics has become a high-throughput tool to explain biological mechanisms. In this study, we examined the retinas of guinea pigs with form deprivation myopia using 4D label-free proteomics and found disorders of retinal metabolism in experimental myopia.
Project description: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.
Project description:PurposeBright light conditions are supposed to curb eye growth in animals with experimental myopia. Here we investigated the effects of temporal bright light at very low frequencies exposures on lens-induced myopia (LIM) progression.MethodsMyopia was induced by application of -6.00 D lenses over the right eye of guinea pigs. They were randomly divided into four groups based on exposure to different lighting conditions: constant low illumination (CLI; 300 lux), constant high illumination (CHI; 8,000 lux), very low frequency light (vLFL; 300/8,000 lux, 10 min/c), and low frequency light (LFL; 300/8,000 lux, 20 s/c). Refraction and ocular dimensions were measured per week. Changes in ocular dimensions and refractions were analyzed by paired t-tests, and differences among the groups were analyzed by one-way ANOVA.ResultsSignificant myopic shifts in refractive error were induced in lens-treated eyes compared with contralateral eyes in all groups after 3 weeks (all P < 0.05). Both CHI and LFL conditions exhibited a significantly less refractive shift of LIM eyes than CLI and vLFL conditions (P < 0.05). However, only LFL conditions showed significantly less overall myopic shift and axial elongation than CLI and vLFL conditions (both P < 0.05). The decrease in refractive error of both eyes correlated significantly with axial elongation in all groups (P < 0.001), except contralateral eyes in the CHI group (P = 0.231). LFL condition significantly slacked lens thickening in the contralateral eyes.ConclusionsTemporal bright light at low temporal frequency (0.05 Hz) appears to effectively inhibit LIM progression. Further research is needed to determine the safety and the potential mechanism of temporal bright light in myopic progression.
Project description:Visual environment plays an important role in the occurrence of myopia. We previously showed that the different flashing lights could result in distinct effects on the ocular growth and development of myopia. CCN2 has been reported to regulate various cellular functions and biological processes. However, whether CCN2 signaling was involved in the red flashing light-induced myopia still remains unknown. In the present study, we investigated the effects of the red flashing lights exposure on the refraction and axial length of the eyes in vivo and then evaluated their effects on the expression of CCN2 and TGF- β in sclera tissues. Our data showed that the eyes exposed to the red flashing light became more myopic with a significant increase of the axial length and decrease of the refraction. Both CCN2 and TGF- β , as well as p38 MAPK and PI3K, were highly expressed in the sclera tissues exposed to the red flashing light. Both CCN2 and TGF- β were found to have the same gene expression profile in vivo. In conclusion, our findings found that CCN2 signaling pathway plays an important role in the red flashing light-induced myopia in vivo. Moreover, our study establishes a useful animal model for experimental myopia research.