Retinal Tissue Research Articles

Podcast on Identifying and Understanding Barriers to Care in Underserved Populations With MS in the United States.

Multiple sclerosis (MS) can affect people from all racial and ethnic backgrounds, but, historically, the incidence of MS in the United States was thought to be highest in White individuals. More recent data suggest that the incidence of MS in Black or African American individuals is comparable to that in White individuals. In Hispanic or Latino individuals, incidence of MS is lower, but age of onset may be earlier compared with White individuals. Additionally, there are important differences in MS disease severity, disease progression, and mortality in Black or African American and Hispanic or Latino populations. Compared with their White counterparts, individuals from these underrepresented groups are more likely to be affected by MS in specific areas of the nervous system, such as accelerated loss of retinal and brain tissue in Black or African American individuals and optic neuritis in Hispanic individuals. Additionally, Black or African American individuals with MS tend to have an aggressive disease course, earlier disability, and higher risk of requiring ambulatory assistance. Although these differences may be attributed to genetic factors, systemic racism and biases and barriers to accessing care may perpetuate health disparities. Moreover, non-White communities remain broadly underrepresented in clinical trials; however, it is vital that these populations are appropriately represented so that any potential differences in drug efficacy or safety implications are detected. Thus, it is important to increase awareness of MS in these populations. In this podcast, the authors discuss characteristics of MS in Black or African American and Hispanic or Latino populations, identify barriers to care, and propose solutions to improve access to MS care in these populations. MP4 (358385 KB).

Optical coherence tomography angiography of choroidal neovascularization in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD)

PurposeTo report the clinical utility of optical coherence tomography angiography (OCTA) for demonstrating choroidal neovascularization (CNV) associated with Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency (LCHADD) retinopathy. MethodsThirty-three participants with LCHADD (age 7–36 years; median 17) were imaged with OCTA and the Center for Ophthalmic Optics & Lasers Angiography Reading Toolkit (COOL-ART) software was implemented to process OCTA scans. ResultsSeven participants (21 %; age 17–36 years; median 25) with LCHADD retinopathy demonstrated evidence of CNV by retinal examination or presence of CNV within outer retinal tissue on OCTA scans covering 3 × 3 and/or 6 × 6-mm. These sub-clinical CNVs are adjacent to hyperpigmented areas in the posterior pole. CNV presented at stage 2 or later of LCHADD retinopathy prior to the disappearance of RPE pigment in the macula. ConclusionOCTA can be applied as a non-invasive method to evaluate the retinal and choroidal microvasculature. OCTA can reveal CNV in LCHADD even when the clinical exam is inconclusive. These data suggest that the incidence of CNV is greater than expected and can occur even in the early stages of LCHADD retinopathy.

Therapeutic effect of folic acid combined with decitabine on diabetic mice.

To evaluate the therapeutic effect of folic acid combined with decitabine on diabetic mice. The diabetic model of db/db mice were randomly divided into model group, folic acid group, decitabine group, folic acid combined with decitabine group, and C57 mice as normal control group. The density of retinal blood vessels and retinal thickness were detected by fundus photography and optical coherence tomography, respectively. Pathological changes of retina were observed by hematoxylin-eosin (HE) staining. The homocysteine (Hcy) in serum was detected by enzyme linked immunosorbent assay (ELISA). TdT-mediated dUTP nick-end labeling (TUNEL) was used to detect apoptosis in retinal tissue. Evans blue dye was used to detect the permeability of retinal blood vessels. The platelet endothelial cell adhesion molecule-1 (CD31) and vascular endothelial growth factor receptor (VEGFR) protein were detected by Western blot. The 3-nitrotyrosine (3-NT) and 4-hydroxynonanine (4-HNE) were detected by immunohistochemistry. The density of retinal blood vessels, retinal thickness, retinal vascular permeability and the proportion of apoptotic cells of retinal tissue in the model group increased significantly than control group (P<0.05). The Hcy in serum and the levels of CD31, VEGFR, 3-NT, and 4-HNE in retinal tissue increased significantly in the model group (P<0.01). Folic acid and decitabine both reversed these changes significantly, and the combination of the folic acid and decitabine worked best. The combination of folic acid and decitabine has a more significant protective effect on the retina in diabetic mice.

Systemic Evidence for Mitochondrial Dysfunction in Age-Related Macular Degeneration as Revealed by mtDNA Copy Number Measurements in Peripheral Blood.

Mitochondrial dysfunction is a common occurrence in the aging process and is observed in diseases such as age-related macular degeneration (AMD). Increased levels of reactive oxygen species lead to damaged mitochondrial DNA (mtDNA), resulting in dysfunctional mitochondria, and, consequently, mtDNA causes further harm in the retinal tissue. However, it is unclear whether the effects are locally restricted to the high-energy-demanding retinal pigment epithelium or are also systematically present. Therefore, we measured mtDNA copy number (mtDNA-CN) in peripheral blood using a qPCR approach with plasmid normalization in elderly participants with and without AMD from the AugUR study (n = 2262). We found significantly lower mtDNA-CN in the blood of participants with early (n = 453) and late (n = 170) AMD compared to AMD-free participants (n = 1630). In regression analyses, we found lower mtDNA-CN to be associated with late AMD when compared with AMD-free participants. Each reduction of mtDNA-CN by one standard deviation increased the risk for late AMD by 24%. This association was most pronounced in geographic atrophy (OR = 1.76, 95% CI 1.19-2.60, p = 0.004), which has limited treatment options. These findings provide new insights into the relationship between mtDNA-CN in blood and AMD, suggesting that it may serve as a more accessible biomarker than mtDNA-CN in the retina.

Combination Therapy with N-Acetylserotonin and Aflibercept Activated the Akt/Nrf2 Pathway to Inhibit Apoptosis and Oxidative Stress in Rats with Retinal Ischemia–Reperfusion Injury

Purpose N-acetylserotonin (NAS) can reduce retinal ischemia–reperfusion injury (RIRI) by inhibiting the TLR4/NF-κB/NLRP3 signaling pathway. Aflibercept is an anti-VEGF drug used to treat a variety of eye diseases. This study was performed to investigate the effect of combination therapy with N-acetylserotonin and aflibercept on RIRI and its mechanism. Methods The RIRI model was established by elevating the intraocular pressure. H&E staining was used to observe the pathological changes in the retinal tissue. Cell apoptosis was evaluated by TUNEL. The expression of cleaved caspase-3 in the retina was detected by immunofluorescence and western blotting. The levels of SOD, GSH-Px, and MDA in retinal tissue were measured by ELISA. The protein expression of cytoplasmic Nrf2, nuclear Nrf2, HO-1, Akt, and p-Akt was determined by western blotting. Results The results showed that combination therapy with NAS and aflibercept significantly alleviated retinal histopathological damage, decreased retinal thickness (from 335.49 ± 30.50 µm to 226.16 ± 17.20 µm, p < 0.001) and the rate of retinal apoptosis (from 28.27 ± 0.39% to 7.87 ± 0.19%, p < 0.001), and downregulated protein expression (from 2.42 ± 0.03 to 1.39 ± 0.03, p < 0.001) and positive expression (from 31.88 ± 0.52 to 25.36 ± 0.58, p < 0.001) of cleaved caspase-3. In addition, combination therapy with NAS and aflibercept also upregulated the levels of SOD (from 20.31 ± 0.18 to 29.66 ± 0.83, p < 0.001) and GSH-Px (from 13.62 ± 0.36 to 19.31 ± 0.82, p < 0.001) and downregulated the level of MDA (from 0.51 ± 0.01 to 0.41 ± 0.01, p < 0.001) to inhibit oxidative stress. Finally, combination therapy with NAS and aflibercept increased the protein expression of cytoplasmic Nrf2 (from 0.10 ± 0.002 to 0.85 ± 0.01, p < 0.001), nuclear Nrf2 (from 0.43 ± 0.01 to 0.88 ± 0.04, p < 0.001), and HO-1 (from 0.45 ± 0.03 to 0.91 ± 0.04, p < 0.001) and the p-Akt/Akt ratio (from 0.45 ± 0.02 to 0.81 ± 0.07, p < 0.001). Conclusions Overall, combination therapy with NAS and aflibercept attenuated RIRI, and its mechanism may be related to inhibiting apoptosis and oxidative stress and activating the Akt/Nrf2 pathway.

Effect of IP-10/CXCR3 signaling pathway on rats with diabetic retinopathy.

This study aimed to investigate the effect of the interferon-inducible protein-10 (IP-10)/C-X-C motif chemokine receptor 3 (CXCR3) signaling pathway on rats with diabetic retinopathy. A total of 21 Sprague-Dawley rats were selected as the objects and divided into control (n=7), model (n=7) and inhibitor (n=7) groups. The rats in control group did not receive any treatment. The diabetic retinopathy model was established using streptozotocin and vascular endothelial growth factor in model group, while the rats in inhibitor group were treated with AMG 487, an inhibitor of the IP-10/CXCR3 signaling pathway, based on the treatment in model group. The changes in gene expression patterns in rats with diabetic retinopathy were screened by sequencing. After the differential genes were determined, the pathways mainly related to the complication were obtained via enrichment analysis. The expression of the IP-10/CXCR3 signaling pathway, the apoptotic cells and the expression of inflammatory molecules (IL-6, IL-12, TNF-α and IL-1β) in each group of rats were detected. It was shown in volcano plot that there were some differentially expressed genes (fold change >1.2, P<0.01) in retinal tissues of rats in control and model groups. Meanwhile, the heatmap displayed that there were great differences in the gene expression patterns between control and model groups, and the gene expressions of IP-10 and CXCR3 in model group were higher than those in control group (P<0.05). The differential genes in control and model groupwere enriched in such processes as the cAMP metabolic regulatory pathway, chemotaxis of immunocytes, proliferation of endothelial cells, response of cytokine receptors, apoptosis, mTOR signaling pathway and TGF-β-related signaling pathway. The mRNA expressions of IP-10 and CXCR3 in model group were higher than those in control group (P<0.05), while they were notably lower in inhibitor group than those in model group (P<0.05). Besides, the protein levels of IP-10 and CXCR3 were identical to the mRNA levels. The apoptotic cells were increased markedly in model group compared with those in control group (P<0.05) and inhibitor group (P<0.05). Model group exhibited higher expression levels of IL-6, TNF-α and IL-1β in retinal tissues than control group (P<0.05), while inhibitor group had distinctly lower expression levels of IL-6, TNF-α and IL-1β in retinal tissues than model group (P<0.05). The IP-10/CXCR3 signaling pathway can affect rats with diabetic retinopathy.

Linking Adiponectin and Its Receptors to Age-Related Macular Degeneration (AMD).

In recent years, there has been a captivating focus of interest in elucidating the intricate crosstalk between adiponectin (APN), a versatile fat-associated adipokine and ocular pathologies. Unveiling the intricate relationship between adipocytokine APN and its receptors (AdipoRs) with aging eye disorders has emerged as a fascinating frontier in medical research. This review article delves into this connection, illuminating the hidden influence of APN on retinal health. This comprehensive review critically examines the latest findings and breakthroughs that underscore the pivotal roles of APN/AdipoRs signaling in maintaining ocular homeostasis and protecting against eye ailments. Here, we meticulously explore the intriguing mechanisms by which APN protein influences retinal function and overall visual acuity. Drawing from an extensive array of cutting-edge studies, the article highlights APN's multifaceted functions, ranging from anti-inflammatory properties and oxidative stress reduction to angiogenic regulation within retinal and macula tissues. The involvement of APN/AdipoRs in mediating these effects opens up novel avenues for potential therapeutic interventions targeting prevalent aging eye conditions. Moreover, this review unravels the interplay between APN signaling pathways and age-related macular degeneration (AMD). The single-cell RNA-seq results validate the expression of both the receptor isoforms (AdipoR1/R2) in retinal cells. The transcriptomic analysis showed lower expression of AdipoR1/2 in dry AMD pathogenesis compared to healthy subjects. The inhibitory adiponectin peptide (APN1) demonstrated over 75% suppression of CNV, whereas the control peptide did not exert any inhibitory effect on choroidal neovascularization (CNV). The elucidation of these relationships fosters a deeper understanding of adipose tissue's profound influence on ocular health, presenting new prospects for personalized treatments and preventative measures. Because APN1 inhibits CNV and leakage, it can be used to treat human AMD, although the possibility to treat human AMD is in the early stage and more clinical research is needed. In conclusion, this review provides a captivating journey into the enthralling world of APN, intertwining the realms of adipose biology and ophthalmology in aging.

ScAAV2-Mediated Expression of Thioredoxin 2 and C3 Transferase Prevents Retinal Ganglion Cell Death and Lowers Intraocular Pressure in a Mouse Model of Glaucoma.

Elevated intraocular pressure (IOP) in glaucoma causes retinal ganglion cell (RGC) loss and damage to the optic nerve. Although IOP is controlled pharmacologically, no treatment is available to restore retinal and optic nerve function. In this paper, we aimed to develop a novel gene therapy for glaucoma using an AAV2-based thioredoxin 2 (Trx2)-exoenzyme C3 transferase (C3) fusion protein expression vector (scAAV2-Trx2-C3). We evaluated the therapeutic effects of this vector in vitro and in vivo using dexamethasone (DEX)-induced glaucoma models. We found that scAAV2-Trx2-C3-treated HeLa cells had significantly reduced GTP-bound active RhoA and increased phosphor-cofilin Ser3 protein expression levels. scAAV2-Trx2-C3 was also shown to inhibit oxidative stress, fibronectin expression, and alpha-SMA expression in DEX-treated HeLa cells. NeuN immunostaining and TUNEL assay in mouse retinal tissues was performed to evaluate its neuroprotective effect upon RGCs, whereas changes in mouse IOP were monitored via rebound tonometer. The present study showed that scAAV2-Trx2-C3 can protect RGCs from degeneration and reduce IOP in a DEX-induced mouse model of glaucoma, while immunohistochemistry revealed that the expression of fibronectin and alpha-SMA was decreased after the transduction of scAAV2-Trx2-C3 in murine eye tissues. Our results suggest that AAV2-Trx2-C3 modulates the outflow resistance of the trabecular meshwork, protects retinal and other ocular tissues from oxidative damage, and may lead to the development of a gene therapeutic for glaucoma.

Experimental study on the therapeutic effect and mechanism of erlotinib on non-proliferative diabetic retinopathy

Experimental study on the therapeutic effect and mechanism of erlotinib on non-proliferative diabetic retinopathy

Retinal ischemia-reperfusion injury induces intense lipid synthesis and remodeling

The retina is a high-metabolism tissue composed of various cell types with complex functions that relies heavily on the blood supply to maintain homeostasis. Retinal ischemia-reperfusion injury is a critical pathogenic mechanism in glaucoma, and changes in lipid molecules may lead to retinal tissue damage. However, retinal lipid profile alterations caused by this mechanism remain unclear. Thus, this study employed a retinal ischemia-reperfusion model to analyze changes in the lipid profile between sham-operated and ischemia-reperfusion groups. We discovered that ischemia-reperfusion injury-induced alterations in 338 lipid molecules, which potentially caused lipid droplet formation and mitochondrial damage. Notably, we identified characteristic changes in various lipids, including cholesterol esters, cardiolipin, and ceramide, which may serve as potential biomarkers for assessing the severity of retinal injury and therapeutic interventions. The ischemia-reperfusion-specific features identified in this study provide a more comprehensive understanding of the pathophysiological mechanisms underlying this condition.

Вплив бензодіазепінових рецепторів на стан глії при розвитку діабетичної ретинопатії

Diabetic retinopathy is a progressive tissue-specific neurovascular complication of diabetes with a multifactorial pathogenesis, in which microvascular disorders are preceded by damage to nerve elements. The latter begin with the early involvement of glia, including astrocytes and Müller cells. Taking into account the establishment of GABA-ergic deficiency, the use of modulators of the GABA-benzodiazepine receptor complex, for example, Carbacetam, which has shown satisfactory neuroprotective properties, seems promising. Diabetes mellitus was modeled by a single administration of streptozotocin (50 mg/kg; “Sigma-Aldrich”, China) to threemonth-old male Wistar rats. Already after 7 days, according to immunohistochemical detection of glial fibrillary acidic protein (GFAP), reactive gliosis of astrocytes of the inner retina layers was detected, to which Müller cells joined from the 14th day. The content of GFAP in retinal tissues increased significantly. GFAP-positive cells were in close contact with foci of pathological angiogenesis in the inner layers of the retina and also took part in the formation of fibrous proliferates in the outer layers. Detection of caspase-3 showed the activation of apoptosis in astrocytes and radial processes of Müller cells in the inner plexiform layer. Carbacetam in combination with insulin reduced the expression of GFAP and caspase-3 in the retina and prevented the development of reactive gliosis, angiogenesis, and the formation of fibrous proliferates, which makes it a candidate for further studies in the treatment of diabetic retinopathy.

Homer1a reduces inflammatory response after retinal ischemia/reperfusion injury.

Abstract JOURNAL/nrgr/04.03/01300535-202407000-00042/figure1/v/2023-11-20T171125Z/r/image-tiff Elevated intraocular pressure (IOP) is one of the causes of retinal ischemia/reperfusion injury, which results in NLRP3 inflammasome activation and leads to visual damage. Homer1a is reported to play a protective role in neuroinflammation in the cerebrum. However, the effects of Homer1a on NLRP3 inflammasomes in retinal ischemia/reperfusion injury caused by elevated IOP remain unknown. In our study, animal models were constructed using C57BL/6J and Homer1flox/ –/Homer1a+/ –/Nestin-Cre+/ – mice with elevated IOP-induced retinal ischemia/reperfusion injury. For in vitro experiments, the oxygen-glucose deprivation/reperfusion injury model was constructed with Müller cells. We found that Homer1a overexpression ameliorated the decreases in retinal thickness and Müller cell viability after ischemia/reperfusion injury. Furthermore, Homer1a knockdown promoted NF-κB P65Ser536 activation via caspase-8, NF-κB P65 nuclear translocation, NLRP3 inflammasome formation, and the production and processing of interleukin-1β and interleukin-18. The opposite results were observed with Homer1a overexpression. Finally, the combined administration of Homer1a protein and JSH-23 significantly inhibited the reduction in retinal thickness in Homer1flox/ –/Homer1a+/ –/Nestin-Cre+/ – mice and apoptosis in Müller cells after ischemia/reperfusion injury. Taken together, these studies demonstrate that Homer1a exerts protective effects on retinal tissue and Müller cells via the caspase-8/NF-κB P65/NLRP3 pathway after I/R injury.

Retina pathology as a target for biomarkers for Alzheimer's disease: Current status, ophthalmopathological background, challenges, and future directions.

There is emerging evidence that amyloid beta protein (Aβ) and tau-related lesions in the retina are associated with Alzheimer's disease (AD). Aβ and hyperphosphorylated (p)-tau deposits have been described in the retina and were associated with small amyloid spots visualized by in vivo imaging techniques as well as degeneration of the retina. These changes correlate with brain amyloid deposition as determined by histological quantification,positron emission tomography (PET) or clinical diagnosis of AD. However, the literature is not coherent on these histopathological and in vivo imaging findings. One important reason for this is the variability in the methods and the interpretation of findings across different studies. In this perspective, we indicate the critical methodological deviations among different groups and suggest a roadmap moving forward on how to harmonize (i) histopathologic examination of retinal tissue; (ii) in vivo imaging among different methods, devices, and interpretation algorithms; and (iii) inclusion/exclusion criteria for studies aiming at retinal biomarker validation.

The Involvement of Unfolded Protein Response in the Mechanism of Nitrogen Mustard-Induced Ocular Toxicity.

Nitrogen mustard (NM) is a known surrogate of sulfur mustard, a chemical-warfare agent that causes a wide range of ocular symptoms, from a permanent reduction in visual acuity to blindness upon exposure. Although it has been proposed that the two blistering agents have a similar mechanism of toxicity, the mode of NM-induced cell death in ocular tissue has not been fully explored. Therefore, we hypothesized that direct ocular exposure to NM in mice leads to retinal tissue injury through chronic activation of the unfolded protein response (UPR) PERK arm in corneal cells and VEGF secretion, eventually causing cell death. We topically applied NM directly to mice to analyze ocular and retinal tissues at 2 weeks postexposure. A dramatic decline in retinal function, measured by scotopic and photopic electroretinogram responses, was detected in the mice. This decline was associated with enhanced TUNEL staining in both corneal and retinal tissues. In addition, exposure of corneal cells to NM revealed 228 differentially and exclusively expressed proteins primarily associated with the UPR, ferroptosis, and necroptosis. Moreover, these cells exhibited activation of the UPR PERK arm and an increase in VEGF secretion. Enhancement of VEGF staining was later observed in the corneas of the exposed mice. Therefore, our data indicated that the mechanism of NM-induced ocular toxicity should be carefully examined and that future research should identify a signaling molecule transmitted via a prodeath pathway from the cornea to the retina. SIGNIFICANCE STATEMENT: This study demonstrated that NM topical exposure in mice results in dramatic decline in retinal function associated with enhanced TUNEL staining in both corneal and retinal tissues. We also found that the NM treatment of corneal cells resulted in 228 differentially and exclusively expressed proteins primarily associated with ferroptosis. Moreover, these cells manifest the UPR PERK activation and an increase in VEGF secretion. The latter was also found in the corneas of the cexposed mice.

Episodic live imaging of cone photoreceptor maturation in GNAT2-EGFP retinal organoids.

Fluorescent reporter pluripotent stem cell-derived retinal organoids are powerful tools to investigate cell type-specific development and disease phenotypes. When combined with live imaging, they enable direct and repeated observation of cell behaviors within a developing retinal tissue. Here, we generated a human cone photoreceptor reporter line by CRISPR/Cas9 genome editing of WTC11-mTagRFPT-LMNB1 human induced pluripotent stem cells (iPSCs) by inserting enhanced green fluorescent protein (EGFP) coding sequences and a 2A self-cleaving peptide at the N-terminus of guanine nucleotide-binding protein subunit alpha transducin 2 (GNAT2). In retinal organoids generated from these iPSCs, the GNAT2-EGFP alleles robustly and exclusively labeled immature and mature cones. Episodic confocal live imaging of hydrogel immobilized retinal organoids allowed tracking of the morphological maturation of individual cones for >18 weeks and revealed inner segment accumulation of mitochondria and growth at 12.2 μm3 per day from day 126 to day 153. Immobilized GNAT2-EGFP cone reporter organoids provide a valuable tool for investigating human cone development and disease.

MicroRNA-93 promotes the pathogenesis of glaucoma by inhibiting matrix metalloproteinases as well as up-regulating extracellular matrix and Rho/ROCK signaling pathways

ObjectiveTo investigate the effect and potential molecular mechanism of microRNA-93 (miR-93) on retinal ganglion cells (RGCs) apoptosis as well as retinal damage in acute glaucoma mice. MethodsRGCs apoptosis were induced by oxygen-glucose deprivation and reperfusion (OGD/R). The pro-apoptotic effect of miR-93 was evaluated by transfecting miR-93 mimics or miR-93 inhibitor into OGD/R-induced RGCs. The viability and apoptosis of RGCs were determined by MTT assay and flow cytometry. Mouse model of acute glaucoma were successfully induced via high intraocular pressure (IOP), and then these model animals were randomly divided into vehicle group, miR-93 mimics group or miR-93 inhibitor group (n = 10), using healthy mice as normal control. Histopathologic changes of retinal tissue were evaluated by Hematoxylin and Eosin (H&E) staining method. Moreover, cell counts of retinal ganglion cell layer and mean thickness of different layers were also determined. Quantitative real-time PCR (qPCR) and western blotting analysis were used to detect the mRNA and protein expression levels of extracellular matrix (ECM), matrix metalloproteinases (MMPs) and Rho/ROCK signaling pathway. ResultsmiR-93 mimics significantly decreased or promoted the viability and apoptosis of OGD/R-induced RGCs, respectively. In addition, miR-93 mimics significantly exacerbated the degree of retinal tissue damage in mice with acute glaucoma, which was accompanied by a decrease in the number of ganglion cell layer (GCL) cells and the thickness of different tissue layers. Moreover, miR-93 mimics significantly increased IOP in mice with acute glaucoma. Significantly, miR-93 inhibitors significantly reversed the above changes. In addition, results of Western blot analysis showed that miR-93 mimics increased and decreased the expression of ECM-associated and MMP-associated proteins, respectively, by activating the Rho/ROCK signaling pathway. In contrast, miR-93 significantly decreased and increased the expression of ECM-associated and MMP-associated proteins, and suppressed the expression of Rho/ROCK signaling pathway-related proteins. ConclusionmiR-93 can promote the development of glaucoma by activating Rho/ROCK signaling pathway to mediate the accumulation of ECM-related proteins as well as the down-regulation of MMP-related proteins.

Qi-Shen-Tang alleviates retinitis pigmentosa by inhibiting ferroptotic features via the NRF2/GPX4 signaling pathway

Ferroptosis has been observed during retinal photoreceptor cell death, suggesting that it plays a role in retinitis pigmentosa (RP) pathogenesis. Qi-Shen-Tang (QST) is a combination of two traditional Chinese medicines used for the treatment of ophthalmic diseases; however, its mechanism of action in RP and ferroptosis remains unclear. Therefore, this study aimed to explore the effect and potential molecular mechanisms of QST on RP. QST significantly improved tissue morphology and function of the retina in the RP model mice. A significant increase in retinal blood flow and normalization of the fundus structure were observed in mice in the treatment group. After QST treatment, the level of iron and the production of malondialdehyde decreased significantly; the levels of superoxide dismutase and glutathione increased significantly; and the protein expression of glutathione peroxidase 4 (GPX4), glutathione synthetase, solute carrier family 7 member 11, and nuclear factor erythroid 2-related factor 2 (NRF2) increased significantly. The molecular docking results demonstrated potential interactions between the small molecules of QST and the key proteins of NRF2/GPX4 signaling pathway. Our results indicate that QST may inhibit ferroptosis by inhibiting the NRF2/GPX4 signaling pathway, thereby reducing RP-induced damage to retinal tissue.

Linking Cognitive Impairment with Amyloid-β Accumulation in Alzheimer's Disease: Insights from Behavioral Tests and FTIR Spectroscopy.

Alzheimer's disease (AD) is a neurodegenerative disorder that progresses over time. Fourier Transform Infrared Spectroscopy (FTIR) analysis gives identification of the main metabolic changes that happen during neurodegeneration, by monitoring biochemical and molecular structure alterations that can help in AD diagnosis or treatment approach. The aim of the present work is to assess AD hallmarks in molecular structure of retina and monitor accumulation of amyloid beta42(Aβ42) in brain and retina during disease progression. AD induced in rats by Aluminum Chloride (AlCl3). Retinal molecular structure during disease progression for 2,4,6 and 8 weeks was assessed by Fourier-transform infrared spectroscopy (FTIR) and the incidence of the disease was confirmed by a behavioural assessment; the Morris Water Maze test. Aβ42 levels in the brain and retina were also measured. The results indicated that cognitive impairment starting from 6 weeks of AlCl3 administration. Retinal concentration of Aβ42 was significant increase (p < 0.05) from 2 weeks that precedes the observed increase of Aβ42 in the brain which appeared after 4 weeks of AlCl3 administration. Multivariate principal component analysis discovers that the variance noticed in the infrared spectra due to AD condition and it is time dependent for progression of the disease. The accumulation of Aβ42 is a sensitive early biomarker in retina for AD. FTIR analysis of the retina revealed changes in hydrogen bond formation or destruction, alterations in lipid chain length and branching accompanied by depleted lipid content and carbonization, as well as degeneration of the retinal tissue due to AD.

Role of Intravitreal Triamcinolone Acetonide and Bevacizumab in Expression of Matrix Metalloproteinase and Inhibitor in Rabbit Penetrating Injury Model

Aims: To assess the effects of intravitreal triamcinolone acetonide and bevacizumab on the expression of matrix metalloproteinase MMP-2 and its inhibitor TIMP-1 in an experimental rabbit model of penetrating injury. Settings and Design: An accurate experimental study of five left eyes as negative control and 27 eyes with penetrating injury with or without treatment from 27 rabbits. Methods and Material: A total of 30 New Zealand rabbits were recruited, and penetrating injury was performed in the superotemporal quadrant of the right eye by making incisions 5 mm horizontally and 6 mm behind the limbus. The rabbits were split into five groups: OGI, intravitreal triamcinolone acetonide, and bevacizumab, with varying injection timings (n = 6 per group). All eyes were inspected and analyzed by assessing the expression of MMP-2 and TIMP-1. Statistical analysis used: Statistical analysis was performed using the Prism GraphPad 9. Statistical calculations were made by ANOVA test. All descriptive data are presented as mean+standard deviation. P value less than 0.05 was considered significant statistically. Results: The expression of MMP-2 in the treatment group was considerably lower than in control penetrating injury group (8,36±1,699, p&lt;0,0001), conversely TIMP-1 expression was higher in the treatment group (4,72±1,026, P 0,0593). Fibrosis was assessed with HE staining and primarily detected in positive control groups. Conclusions: TA and bevacizumab treatments after penetrating injury effectively inhibited the elevation of MMP-2 and decreased the expression of TIMP-1 in the retina and wound site tissue, respectively. It reduces the possibility of acquiring posttraumatic PVR.

Beta-mannosidosis in a domestic cat associated with a missense variant in MANBA

A 6-month-old cat of unknown ancestry presented for a neurologic evaluation due to progressive motor impairment. Complete physical and neurologic examinations suggested the disorder was likely to be hereditary, although the signs were not consistent with any previously described inherited disorders in cats. Due to the progression of disease signs including severely impaired motor function and cognitive decline, the cat was euthanized at approximately 10.5 months of age. Whole genome sequence analysis identified a homozygous missense variant c.2506G > A in MANBA that predicts a p.Gly836Arg alteration in the encoded lysosomal enzyme β -mannosidase. This variant was not present in the whole genome or whole exome sequences of any of the 424 cats represented in the 99 Lives Cat Genome dataset. β -Mannosidase enzyme activity was undetectable in brain tissue homogenates from the affected cat, whereas α-mannosidase enzyme activities were elevated compared to an unaffected cat. Postmortem examination of brain and retinal tissues revealed massive accumulations of vacuolar inclusions in most cells, similar to those reported in animals of other species with hereditary β -mannosidosis. Based on these findings, the cat likely suffered from β -mannosidosis due to the abolition of β -mannosidase activity associated with the p.Gly836Arg amino acid substitution. p.Gly836 is located in the C-terminal region of the protein and was not previously known to be involved in modulating enzyme activity. In addition to the vacuolar inclusions, some cells in the brain of the affected cat contained inclusions that exhibited lipofuscin-like autofluorescence. Electron microscopic examinations suggested these inclusions formed via an autophagy-like process.