bims-mideyd 2024-12-08 papers

Sci Rep. 2024 12 03. 14(1): 30012

Multi-spectral autofluorescence variability of the individual retinal pigmented epithelial cells in healthy aging eyes.

Daniel M W Lee, Min Zhang, Valerie C Snyder, Ethan A Rossi.

The retinal pigment epithelium (RPE) is vital for the healthy function of the retina. Cellular level changes in the RPE are not visualized with current clinical techniques due to a lack of spatial resolution. Fluorescence adaptive optics scanning light ophthalmoscopy (AOSLO) can image RPE cells by utilizing their intrinsic autofluorescence (AF). The RPE AF has been imaged with only a few discrete excitation and emission bands and the multi-spectral AF has not been interrogated systematically at the level of single cells. In this study, we imaged 16 healthy eyes (ages 20-75) with AOSLO to investigate the multi-spectral AF as a function of age and wavelength with excitation from 650 - 805 nm. Quantitative analysis showed that 720 nm light produced images with the highest SNR (65.0 dB). Spatial AF variability showed a trend to increase with aging, suggesting increased heterogeneity in RPE AF with age. Spatial variability in the multi-spectral fluorescence of RPE cells with age may be a consequence of normal age-related loss of RPE cells. Multi-spectral fluorescence AOSLO provides new insight into aging related changes to RPE cells and may be a useful tool for studying diseases that affect the RPE, such as age-related macular degeneration (AMD).

DOI: https://doi.org/10.1038/s41598-024-81433-8

J Mol Histol. 2024 Dec 04. 56(1): 25

Protective effect of Apelin-13 on oxygen and glucose deprivation induced-damage in retinal ganglion cells cultured in vitro.

Li Dai, Linlin Luo, Ya Zhang, Min Fu, Ling Yu.

Ischemic-anoxic injury plays an important role in the pathophysiology of diabetes retinopathy, optic neuropathy, even glaucoma and other ocular diseases. It may ultimately cause damage to neuronal death like retinal ganglion cells (RGCs) and subsequent visual loss. RGCs are essential elements of the retina and optic nerve that are crucial to visual formation. Ischemic-anoxic injury, inflammation, and oxidative stress are vital causes of RGC death. Thus, neuroprotection is essential for the treatment of these ocular diseases. Recent studies have shown the neuroprotective property of apelin-13 in many disease models. In this study, we isolated RGCs and found that apelin-13 promoted the viability of RGCs and increased the phosphorylation of Protein kinase B (PKB, Akt) in an in vitro oxygen-glucose deprivation model. Moreover, apelin-13 increased the expressions of glucose-6-phosphate dehydrogenase (G6PD) and nicotinamide adenine dinucleotide phosphate (NADPH) and reduced the level of reactive oxygen species (ROS). And, we also found that apelin-13 could promote the expressions of glucose transporter-1 (GLUT1) and adenosine triphosphate (ATP). These results indicated that apelin-13 could delay or stop RGC death, which might be as potential therapeutic targets for treatment of diseases mediated by ischemic-anoxic damage like diabetes retinopathy, optic neuropathy, even glaucoma.

Keywords: Apelin-13; OGD; PI3K/Akt; Retinal ganglion cells

DOI: https://doi.org/10.1007/s10735-024-10279-1

Invest Ophthalmol Vis Sci. 2024 Dec 02. 65(14): 1

Design and Characterization of a Novel Intravitreal Dual-Transgene Genetic Medicine for Neovascular Retinopathies.

Purpose: Intravitreal delivery of therapeutic transgenes to the retina via engineered viral vectors can provide sustained local concentrations of therapeutic proteins and thus potentially reduce the treatment burden and improve long-term vision outcomes for patients with neovascular (wet) age-related macular degeneration (AMD), diabetic macular edema (DME), and diabetic retinopathy.
Methods: We performed directed evolution in nonhuman primates (NHP) to invent an adeno-associated viral (AAV) variant (R100) with the capacity to cross vitreoretinal barriers and transduce all regions and layers of the retina following intravitreal injection. We then engineered 4D-150, an R100-based genetic medicine carrying 2 therapeutic transgenes: a codon-optimized sequence encoding aflibercept, a recombinant protein that inhibits VEGF-A, VEGF-B, and PlGF, and a microRNA sequence that inhibits expression of VEGF-C. Transduction, transgene expression, and biological activity were characterized in human retinal cells in vitro and in NHPs.
Results: R100 demonstrated superior retinal cell transduction in vitro and in vivo compared to AAV2, a commonly used wild-type AAV serotype in retinal gene therapies. Transduction of human retinal pigment epithelial cells in vitro by 4D-150 resulted in dose-dependent transgene expression and corresponding reductions in VEGF-A and VEGF-C. Intravitreal administration of 4D-150 to NHPs was well tolerated and led to robust retinal expression of both transgenes. In a primate model of laser-induced choroidal neovascularization, 4D-150 completely prevented clinically relevant angiogenic lesions at all tested doses.
Conclusions: These findings support further development of 4D-150. Clinical trials are underway to establish the safety and efficacy of 4D-150 in individuals with wet AMD and DME.

DOI: https://doi.org/10.1167/iovs.65.14.1

Front Pharmacol. 2024 ;15 1490443

Dipeptide alanine-glutamine ameliorates retinal neurodegeneration in an STZ-induced rat model.

Yuhan Zhang, Mingyan Wei, Xin Wang, Yuan Xu, Rongrong Zong, Xiang Lin, Shiying Li, Wensheng Chen, Zuguo Liu, Qian Chen.

Introduction: Diabetic retinopathy (DR) is a common complication of diabetes. Retinal neuronal degeneration is an early event in DR, indicated by the declined electroretinogram (ERG). Dipeptide alanine-glutamine (Ala-Gln) is widely used as a nutritional supplement in the clinic and has anti-inflammatory effects on the gastrointestinal system. Studies also reported that glutamine has beneficial effects on diabetes. This study aimed to investigate the possible therapeutic effects of Ala-Gln in diabetic retinal neurodegeneration and to delineate its mechanism of action.
Methods: The Streptozotocin (STZ)-induced rat model was used as a DR model. ERG was used to measure the neuronal function of the retina. Western blot analysis was performed to test the expression of proteins. Immunofluorescence staining was used for the detection and localization of proteins.
Results: In diabetic rats, the amplitudes of ERG were declined, while Ala-Gln restored the declined ERG. Retinal levels of inflammatory factors were significantly decreased in Ala-Gln-treated diabetic rats. Ala-Gln mitigated the declined levels of glutamine synthetase and ameliorated the upregulated levels of glial fibrillary acidic protein (GFAP) in diabetic retinas. Moreover, Ala-Gln upregulated the glycolytic enzymes pyruvate kinase isozymes 2 (PKM2), lactate dehydrogenase A (LDHA) and LDHB and stimulated the mTOR signaling pathway in diabetic retinas. The mitochondrial function was improved after the treatment of Ala-Gln in diabetic retinas.
Discussion: Ala-Gln ameliorates retinal neurodegeneration by reducing inflammation and enhancing glucose metabolism and mitochondrial function in DR. Therefore, manipulation of metabolism by Ala-Gln may be a novel therapeutic avenue for retinal neurodegeneration in DR.

Keywords: alanine-glutamine; diabetic retinopathy; glucose metabolism; mTOR; retinal neurodegeneration

DOI: https://doi.org/10.3389/fphar.2024.1490443