Melatonin prevents EAAC1 deletion-induced retinal ganglion cell degeneration by inhibiting apoptosis and senescence.

Normal tension glaucoma (NTG) is referred to as a progressive degenerative disorder of the retinal ganglion cells (RGCs), resulting in nonreversible visual defects, despite intraocular pressure levels within the statistically normal range. Current therapeutic strategies for NTG yield limited benefits. Excitatory amino acid carrier 1 (EAAC1) knockout (EAAC1-/- ) in mice has been shown to induce RGC degeneration without elevating intraocular pressure, mimicking pathological characteristics of NTG. In this study, we explored whether daily oral administration of melatonin could block RGCs loss and prevent retinal morphology and function defects associated with EAAC1 deletion. We also explored the molecular mechanisms underlying EAAC1 deletion-induced RGC degeneration and the neuroprotective effects of melatonin. Our RNA sequencing and in vivo data indicated EAAC1 deletion caused elevated oxidative stress, activation of apoptosis and cellular senescence pathways, and neuroinflammation in RGCs. However, melatonin administration efficiently prevented these detrimental effects. Furthermore, we investigated the potential role of apoptosis- and senescence-related redox-sensitive factors in EAAC1 deletion-induced RGCs degeneration and the neuroprotective effects of melatonin administration. We observed remarkable upregulation of p53, whereas NRF2 and Sirt1 expression were significantly decreased in EAAC1-/- mice, which were prevented by melatonin treatment, suggesting that melatonin exerted its neuroprotective effects possibly through modulating NRF2/p53/Sirt1 redox-sensitive signaling pathways. Overall, our study provided a solid foundation for the application of melatonin in the management of NTG.

GSK840 Alleviates Retinal Neuronal Injury by Inhibiting RIPK3/MLKL-Mediated RGC Necroptosis After Ischemia/Reperfusion.

Purpose: This study aimed to explore the impact of GSK840 on retinal neuronal injury after retinal ischemia/reperfusion (IR) and its associated mechanism. Methods: We established an in vivo mouse model of IR and an in vitro model of oxygen and glucose deprivation/reoxygenation (OGDR) in primary mouse retinal ganglion cells (RGCs). GSK840, a small-molecule compound, was used to specifically inhibit RIPK3/MLKL-dependent necroptosis. Retinal structure and function evaluation was performed by using hematoxylin and eosin staining, optical coherence tomography, and electroretinography. Propidium Iodide (PI) staining was used for detection of necroptotic cell death, whereas Western blot analysis and immunofluorescence were used to assess necroptosis-related proteins and inner retinal neurons. Results: RIPK3/MLKL-dependent necroptosis was rapidly activated in RGCs following retinal IR or OGDR. GSK840 helped maintain relatively normal inner retinal structure and thickness by preserving inner retinal neurons, particularly RGCs. Meanwhile, GSK840 ameliorated IR-induced visual dysfunction, as evidenced by the improved amplitudes of photopic negative response, a-wave, b-wave, and oscillatory potentials. And GSK840 treatment significantly reduced the population of PI+ RGCs after injury. Mechanistically, GSK840 ameliorated RGC necroptosis by inhibiting the RIPK3/MLKL pathway. Conclusions: GSK840 exerts protective effects against retinal neuronal injury after IR by inhibiting RIPK3/MLKL-mediated RGC necroptosis. GSK840 may represent a protective strategy for RGC degeneration in ischemic retinopathy.

Metabolomic Profile in the Aqueous Humor of Congenital Ectopia Lentis.

PURPOSE: To explore the metabolic profiles in the aqueous humor (AH) of patients with congenital ectopia lentis (CEL). METHODS: We conducted a comprehensive analysis of the metabolites of AH samples of patients with CEL (n = 22) and age-matched patients (n = 22) with congenital cataract by ultra-high performance liquid chromatography tandem-mass spectrometry. The metabolomic characteristics were visualized by principal component analysis, orthogonal partial least squares discriminant analysis and heat map. The levels of the differential metabolites were also compared between CEL patients with and without FBN1 mutations. Pathway enrichment analysis was performed by using Kyoto Encyclopedia of Genes and Genomes. Receiver operating characteristic analysis was performed to select potential biomarkers. RESULTS: There were 175 differential metabolites identified between the two groups. Eight metabolites were found to be potential biomarkers in AH of CEL patients. The CEL group showed a significant increase in α-ketoglutarate and decrease in citrate, suggesting that the tricarboxylic acid (TCA) cycle was disturbed. l-proline, prolyl-hydroxyproline, and l-histidine were reduced, which prompted enhanced degradation of microfibrils and collagen. Insidious retinal nerve damage was implied because N-Acetyl-aspartylglutamic acid and N-Acetyl-l-aspartic acid were found to be significantly increased. Pathway enrichment analysis indicated that disturbances in amino acid metabolism and carbohydrate metabolism were the key processes in the pathogenesis of CEL and that TCA cycle disorder may be the driving force behind disease occurrence. CONCLUSION: These data reveal the characteristics in the metabolomic profiles of the AH of CEL patients, which help provide insights into the pathogenesis of this rare disease.

Evaluation of Intraocular Lens Tilt and Decentration in Congenital Ectopia Lentis by the Pentacam Scheimpflug System.

Purpose: The purpose of this study was to quantify the characteristics of the tilt and decentration of the IOL after trans-scleral suture fixation surgery in congenital ectopia lentis (CEL) patients. Methods: The clinical characteristics of 70 CEL patients at Zhongshan Ophthalmic Center in China were retrospectively analyzed. The tilt and decentration of intraocular lens (IOL) were measured by using a Pentacam and compared between different axial length (AL) subgroups. The correlation between IOL tilt, decentration, and ocular characteristics was investigated using Spearman's correlation analysis. Results: The postoperative IOL position of CEL patients was mainly located nasally inferiorly. The average tilt of the IOL in CEL patients was less than 7° (for temporal: 2.21 ± 1.53°, for nasal: -1.84 ± 2.04°, for superior: 2.22 ± 2.18°, and for inferior: -1.70 ± 1.62°), and the average decentration of the IOL in CEL patients was larger than 0.4 mm (for temporal: 0.49 ± 0.38 mm, for nasal: -0.69 ± 0.46 mm, for superior: 0.72 ± 0.58 mm, and for inferior: -0.68 ± 0.54 mm). The decentration of CEL patients in the AL ≥ 26 subgroup was greater than those with AL < 24 mm and AL 24 to 26 mm subgroups (for superior: 0.72 ± 0.28 mm vs. 0.46 ± 0.25 mm and 0.48 ± 0.22 mm, all P < 0.05; for inferior: -0.94 ± 0.56 mm vs. -0.44 ± 0.26 mm and -0.44 ± 0.46 mm, all P < 0.05). IOL decentration was positively correlated with AL (for superior: r = 0.44, P=0.019; for inferior: r = 0.54, P=0.006). IOL tilt was positively correlated with AL on the superior side (r = 0.38, P=0.041). Conclusions: The extent of IOL decentration after trans-scleral suture fixation was great in CEL patients, and the IOL decentration in CEL patients was significantly associated with AL.

Characteristics of Corneal Higher-Order Aberrations in Congenital Ectopia Lentis Patients.

Purpose: The purpose of this study was to investigate the characteristics of corneal higher-order aberrations (HOAs) in patients with congenital ectopia lentis (CEL). Methods: Clinical characteristics and HOAs of 60 patients with CEL and 75 healthy controls at Zhongshan Ophthalmic Center in China were retrospectively analyzed. The Q value and the corneal HOAs in the CEL group and the controls were measured by using Pentacam and compared value between the CEL and control groups. The correlation between HOAs and age was investigated using the Pearson correlation analysis. Results: The Q value of anterior corneal surface in the CEL group was larger than that in the controls (-0.41 ± 0.17 vs. -0.32 ± 0.13, P = 0.001); the total corneal horizontal coma in the CEL group were larger than that in the controls (0.24 ± 0.18 vs. -0.05 ± 0.14, P < 0.001); both the primary spherical aberrations of the anterior and total corneal surface were lower in the CEL group than that in the controls (for anterior corneal surface: 0.15 ± 0.08 vs. 0.27 ± 0.08 µm, P < 0.001; for total corneal surface: 0.10 ± 0.09 vs. 0.23 ± 0.09 µm, P < 0.001), the anterior and total corneal horizontal coma were negatively associated with age, whereas the anterior and total corneal spherical aberrations were positively associated with age in patients with CEL. Conclusions: Patients with CEL had higher corneal horizontal coma and lower corneal vertical coma primary spherical aberrations than healthy controls. Translational Relevance: These findings are informative for the clinical managements in patients with CEL.