Investigating Müller glia reprogramming in mice: a retrospective of the last decade, and a look to the future

Müller glia, as prominent glial cells within the retina, plays a significant role in maintaining retinal homeostasis in both healthy and diseased states. In lower vertebrates like zebrafish, these cells assume responsibility for spontaneous retinal regeneration, wherein endogenous Müller glia undergo proliferation, transform into Müller glia-derived progenitor cells, and subsequently regenerate the entire retina with restored functionality. Conversely, Müller glia in the mouse and human retina exhibit limited neural reprogramming. Müller glia reprogramming is thus a promising strategy for treating neurodegenerative ocular disorders. Müller glia reprogramming in mice has been accomplished with remarkable success, through various technologies. Advancements in molecular, genetic, epigenetic, morphological, and physiological evaluations have made it easier to document and investigate the Müller glia programming process in mice. Nevertheless, there remain issues that hinder improving reprogramming efficiency and maturity. Thus, understanding the reprogramming mechanism is crucial toward exploring factors that will improve Müller glia reprogramming efficiency, and for developing novel Müller glia reprogramming strategies. This review describes recent progress in relatively successful Müller glia reprogramming strategies. It also provides a basis for developing new Müller glia reprogramming strategies in mice, including epigenetic remodeling, metabolic modulation, immune regulation, chemical small-molecules regulation, extracellular matrix remodeling, and cell-cell fusion, to achieve Müller glia reprogramming in mice.

Postnatal development of rat retina: a continuous observation and comparison between the organotypic retinal explant model and in vivo development

JOURNAL/nrgr/04.03/01300535-202503000-00033/figure1/v/2024-06-17T092413Z/r/image-tiff The organotypic retinal explant culture has been established for more than a decade and offers a range of unique advantages compared with in vivo experiments and cell cultures. However, the lack of systematic and continuous comparison between in vivo retinal development and the organotypic retinal explant culture makes this model controversial in postnatal retinal development studies. Thus, we aimed to verify the feasibility of using this model for postnatal retinal development studies by comparing it with the in vivo retina. In this study, we showed that postnatal retinal explants undergo normal development, and exhibit a consistent structure and timeline with retinas in vivo. Initially, we used SOX2 and PAX6 immunostaining to identify retinal progenitor cells. We then examined cell proliferation and migration by immunostaining with Ki-67 and doublecortin, respectively. Ki-67- and doublecortin-positive cells decreased in both in vivo and explants during postnatal retinogenesis, and exhibited a high degree of similarity in abundance and distribution between groups. Additionally, we used Ceh-10 homeodomain-containing homolog, glutamate-ammonia ligase (glutamine synthetase), neuronal nuclei, and ionized calcium-binding adapter molecule 1 immunostaining to examine the emergence of bipolar cells, Müller glia, mature neurons, and microglia, respectively. The timing and spatial patterns of the emergence of these cell types were remarkably consistent between in vivo and explant retinas. Our study showed that the organotypic retinal explant culture model had a high degree of consistency with the progression of in vivo early postnatal retina development. The findings confirm the accuracy and credibility of this model and support its use for long-term, systematic, and continuous observation.

Subretinal fibrosis secondary to neovascular age-related macular degeneration: mechanisms and potential therapeutic targets

Subretinal fibrosis is the end-stage sequelae of neovascular age-related macular degeneration. It causes local damage to photoreceptors, retinal pigment epithelium, and choroidal vessels, which leads to permanent central vision loss of patients with neovascular age-related macular degeneration. The pathogenesis of subretinal fibrosis is complex, and the underlying mechanisms are largely unknown. Therefore, there are no effective treatment options. A thorough understanding of the pathogenesis of subretinal fibrosis and its related mechanisms is important to elucidate its complications and explore potential treatments. The current article reviews several aspects of subretinal fibrosis, including the current understanding on the relationship between neovascular age-related macular degeneration and subretinal fibrosis; multimodal imaging techniques for subretinal fibrosis; animal models for studying subretinal fibrosis; cellular and non-cellular constituents of subretinal fibrosis; pathophysiological mechanisms involved in subretinal fibrosis, such as aging, infiltration of macrophages, different sources of mesenchymal transition to myofibroblast, and activation of complement system and immune cells; and several key molecules and signaling pathways participating in the pathogenesis of subretinal fibrosis, such as vascular endothelial growth factor, connective tissue growth factor, fibroblast growth factor 2, platelet-derived growth factor and platelet-derived growth factor receptor-β, transforming growth factor-β signaling pathway, Wnt signaling pathway, and the axis of heat shock protein 70-Toll-like receptors 2/4-interleukin-10. This review will improve the understanding of the pathogenesis of subretinal fibrosis, allow the discovery of molecular targets, and explore potential treatments for the management of subretinal fibrosis.

Age-related driving mechanisms of retinal diseases and neuroprotection by transcription factor EB-targeted therapy

Retinal aging has been recognized as a significant risk factor for various retinal disorders, including diabetic retinopathy, age-related macular degeneration, and glaucoma, following a growing understanding of the molecular underpinnings of their development. This comprehensive review explores the mechanisms of retinal aging and investigates potential neuroprotective approaches, focusing on the activation of transcription factor EB. Recent meta-analyses have demonstrated promising outcomes of transcription factor EB-targeted strategies, such as exercise, calorie restriction, rapamycin, and metformin, in patients and animal models of these common retinal diseases. The review critically assesses the role of transcription factor EB in retinal biology during aging, its neuroprotective effects, and its therapeutic potential for retinal disorders. The impact of transcription factor EB on retinal aging is cell-specific, influencing metabolic reprogramming and energy homeostasis in retinal neurons through the regulation of mitochondrial quality control and nutrient-sensing pathways. In vascular endothelial cells, transcription factor EB controls important processes, including endothelial cell proliferation, endothelial tube formation, and nitric oxide levels, thereby influencing the inner blood-retinal barrier, angiogenesis, and retinal microvasculature. Additionally, transcription factor EB affects vascular smooth muscle cells, inhibiting vascular calcification and atherogenesis. In retinal pigment epithelial cells, transcription factor EB modulates functions such as autophagy, lysosomal dynamics, and clearance of the aging pigment lipofuscin, thereby promoting photoreceptor survival and regulating vascular endothelial growth factor A expression involved in neovascularization. These cell-specific functions of transcription factor EB significantly impact retinal aging mechanisms encompassing proteostasis, neuronal synapse plasticity, energy metabolism, microvasculature, and inflammation, ultimately offering protection against retinal aging and diseases. The review emphasizes transcription factor EB as a potential therapeutic target for retinal diseases. Therefore, it is imperative to obtain well-controlled direct experimental evidence to confirm the efficacy of transcription factor EB modulation in retinal diseases while minimizing its risk of adverse effects.

Small extracellular vesicles derived from human induced pluripotent stem cell-differentiated neural progenitor cells mitigate retinal ganglion cell degeneration in a mouse model of optic nerve injury

JOURNAL/nrgr/04.03/01300535-202502000-00034/figure1/v/2024-05-28T214302Z/r/image-tiff Several studies have found that transplantation of neural progenitor cells (NPCs) promotes the survival of injured neurons. However, a poor integration rate and high risk of tumorigenicity after cell transplantation limits their clinical application. Small extracellular vesicles (sEVs) contain bioactive molecules for neuronal protection and regeneration. Previous studies have shown that stem/progenitor cell-derived sEVs can promote neuronal survival and recovery of neurological function in neurodegenerative eye diseases and other eye diseases. In this study, we intravitreally transplanted sEVs derived from human induced pluripotent stem cells (hiPSCs) and hiPSCs-differentiated NPCs (hiPSC-NPC) in a mouse model of optic nerve crush. Our results show that these intravitreally injected sEVs were ingested by retinal cells, especially those localized in the ganglion cell layer. Treatment with hiPSC-NPC-derived sEVs mitigated optic nerve crush-induced retinal ganglion cell degeneration, and regulated the retinal microenvironment by inhibiting excessive activation of microglia. Component analysis further revealed that hiPSC-NPC derived sEVs transported neuroprotective and anti-inflammatory miRNA cargos to target cells, which had protective effects on RGCs after optic nerve injury. These findings suggest that sEVs derived from hiPSC-NPC are a promising cell-free therapeutic strategy for optic neuropathy.

Diabetic retinopathy: A review on its pathophysiology and novel treatment modalities

Diabetes mellitus (DM) is a chronic metabolic non-communicable disease with the ability to cause serious microvascular and macrovascular complications throughout the body, including in the eye. Diabetic retinopathy (DR), present in one-third of patients with diabetes, is a vision-threatening complication caused by uncontrolled diabetes, which greatly affects the retinal blood vessels and the light-sensitive inner retina, eventually leading to blindness. Several epidemiological studies elucidate that DR can vary by age of onset, duration, types of diabetes, and ethnicity. Recent studies show that the pathogenesis of diabetic retinopathy has spread its roots beyond merely being the result of hyperglycemia. The complexity of its etiopathology and diagnosis makes therapeutic intervention challenging. This review throws light on the pathological processes behind DR, the cascade of events that follow it, as well as the available and emerging treatment options.

Postnatal weight gain and retinopathy of prematurity in preterm infants: a population-based retrospective cohort study

OBJECTIVE

Infants who meet the screening guidelines for retinopathy of prematurity (ROP) based on birth weight and gestational age undergo serial ophthalmological examinations for its detection and treatment. However, <10% of patients require treatment, and less than half develop ROP. Poor postnatal weight gain has been reported to be a strong indicator of ROP development; however, the information regarding this is unclear. Therefore, this study aimed to determine the relationship between postnatal weight gain and ROP development in preterm infants.

METHODS

The data of 675 preterm infants with gestational age ≤32 weeks, who were hospitalized in our neonatal intensive care unit, were obtained retrospectively from file records. The infants' demographic characteristics, clinical findings, and weekly weight gain (g/kg/day) during the first 8 weeks were recorded. The univariate was used to examine the risk factors for ROP followed by multivariate regression.

RESULTS

The incidence of ROP in the infants included in the study was 41% (n = 278) and 13.3% (n = 37) of them required treatment. In the infants of the group that developed ROP, the mean birth weight and gestational age were significantly lower than those in the group that did not develop ROP (973 ± 288 and 1301 ± 349 g, p = 0.001 and 28.48 ± 1.95 and 30.08 ± 1.60 weeks, p = 0.001, respectively). As the gestational week and birth weight decreased, ROP development and the risk of ROP-requiring treatment increased. In the infants of the group that developed ROP, the mean weight gain in the postnatal third week was detected as significantly lower compared to those in the group that did not develop ROP (13.9 ± 8.2 and 15.4 ± 6.8 g, p = 0.034). On multiple logistic regression analysis, birth weight (<750 g) (odds ratio [OR], 8.67; 95% confidence interval [CI], 3.99-18.82, p = 0.001), blood transfusion (OR, 2.39; 95% CI, 1.34-4.24, p = 0.003), necrotizing enterocolitis (OR, 4.79; 95% CI, 1.05-26.85, p = 0.045), bronchopulmonary dysplasia (OR, 2.03; 95% CI, 1.22-3.36, p = 0.006), antenatal steroid therapy (OR, 1.60; 95% CI, 1.05-2.43, p = 0.028), surfactant administration (OR, 2.06; 95% CI, 1.32-3.2, p = 0.001) were independent risk factors for ROP development.

CONCLUSION

Postnatal weight gain may not be an accurate predictor of ROP development after adjusting for confounding factors. However, the analysis of independent risk factors that influenced the development of ROP revealed a statistically significant effect in cases of low birth weight, blood transfusion, necrotizing enterocolitis, bronchopulmonary dysplasia, and antenatal steroid and surfactant therapies. These findings may help ophthalmologists and neonatologists to pay special attention to this patient group during ROP scanning.

A GUCY2D variant associated cone-rod dystrophy with electronegative ERG: A case report and review

Purpose

Cone-rod dystrophies (CORD) are inherited retinal dystrophies characterized by primary cone degeneration with secondary rod involvement. We report two patients from the same family with a dominant variant in the guanylate cyclase 2D (GUCY2D) gene with different phenotypes in the electroretinogram (ERG).

Observations

A 21-year-old lady (Patient 1) was referred due to experiencing blurry vision and color vision impairment. Visual field testing revealed a central scotoma. Spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) documented macula dysfunction. Reduced amplitude was observed in the photopic responses of ERG. Her 54-year-old father (Patient 2) had similar issues with blurry vision. A dilated fundus examination displayed bilateral macular atrophy. Loss of the ellipsoid zone line and collapse of the outer nuclear segment were noted on the SD-OCT. Photopic ERG responses were extinguished, and an electronegative ERG was observed in the dark-adapted 3.0 ERG. The gene report revealed a c.2512C > T (p.Arg838Cys) variant in GUCY2D for both patients. They were respectively diagnosed as cone dystrophy (COD) and cone-rod dystrophy (CORD).

Conclusions

We report two different clinical phenotypes in GUCY2D-associated COD despite sharing the same variant. A dysfunction in the synaptic junction between the photoreceptor and the secondary neuron was proposed to explain the electronegative ERG. This explanation might extend to other gene-related cases of CORD with electronegative ERG.

Exploring and identifying the imaging biomarkers for predicting anti-VEGF treatment response in polypoidal choroidal vasculopathy: a prospective multicenter study

BACKGROUND

Polypoidal choroidal vasculopathy (PCV) is a hemorrhagic fundus disease that can lead to permanent vision loss. Predicting the treatment response to anti-VEGF monotherapy in PCV is consistently challenging. We aimed to conduct a prospective multicenter study to explore and identify the imaging biomarkers for predicting the anti-VEGF treatment response in PCV patients, establish predictive model, and undergo multicenter validation.

METHODS

This prospective multicenter study utilized clinical characteristics and images of treatment naïve PCV patients from 15 ophthalmic centers nationwide to screen biomarkers, develop model, and validate its performance. Patients from Peking Union Medical College Hospital were randomly divided into a training set and an internal validation set. A nomogram was established by univariate, LASSO regression, and multivariate regression analysis. Patients from the other 14 centers served as an external test set. Area under the curve (AUC), sensitivity, specificity, and accuracy were calculated. Decision curve analysis (DCA) and clinical impact curve (CIC) were utilized to evaluate the practical utility in clinical decision-making.

FINDINGS

The eye distribution for the training set, internal validation set, and external test set were 66, 31, and 71, respectively. The 'Good responder' exhibited a thinner subfoveal choroidal thickness (SFCT) (230.67 ± 61.96 vs. 314.42 ± 88.00 μm, p < 0.001), lower choroidal vascularity index (CVI) (0.31 ± 0.08 vs. 0.36 ± 0.05, p = 0.006), fewer choroidal vascular hyperpermeability (CVH) (31.0 vs. 62.2%, p = 0.012), and more intraretinal fluid (IRF) (58.6 vs. 29.7%, p = 0.018). SFCT (OR 0.990; 95% CI 0.981-0.999; p = 0.033) and CVI (OR 0.844; 95% CI 0.732-0.971; p = 0.018) were ultimately included as the optimal predictive biomarkers and presented in the form of a nomogram. The model demonstrated AUC of 0.837 (95% CI 0.738-0.936), 0.891 (95% CI 0.765-1.000), and 0.901 (95% CI 0.824-0.978) for predicting 'Good responder' in the training set, internal validation set, and external test set, respectively, with excellent sensitivity, specificity, and practical utility.

INTERPRETATION

Thinner SFCT and lower CVI can serve as imaging biomarkers for predicting good treatment response to anti-VEGF monotherapy in PCV patients. The nomogram based on these biomarkers exhibited satisfactory performances.

The use of artificial intelligence to assess diabetic eye disease among the Greenlandic population

Background: Retina fundus images conducted in Greenland are telemedically assessed for diabetic retinopathy by ophthalmological nurses in Denmark. Applying an AI grading solution, in a Greenlandic setting, could potentially improve the efficiency and cost-effectiveness of DR screening.Method: We developed an AI model using retina fundus photos, performed on persons registered with diabetes in Greenland and Denmark, using Optos® ultra wide-field scanning laser ophthalmoscope, graded according to ICDR.Using the ResNet50 network we compared the model's ability to distinguish between different images of ICDR severity levels in a confusion matrix.Results: Comparing images with ICDR level 0 to images of ICDR level 4 resulted in an accuracy of 0.9655, AUC of 0.9905, sensitivity and specificity of 96.6%.Comparing ICDR levels 0,1,2 with ICDR levels 3,4, we achieved a performance with an accuracy of 0.8077, an AUC of 0.8728, a sensitivity of 84.6% and a specificity of 78.8%. For the other comparisons, we achieved a modest performance.Conclusion: We developed an AI model using Greenlandic data, to automatically detect DR on Optos retina fundus images. The sensitivity and specificity were too low for our model to be applied directly in a clinical setting, thus optimising the model should be prioritised.

Longitudinal SS-OCT choroidal imaging following thrombosis of the superior ophthalmic vein

Purpose

To report longitudinal changes in choroidal thickness and the choroidal vasculature using SS-OCT imaging in a patient with superior ophthalmic vein thrombosis (SOVT).

Observations

In a 93-year-old woman with a left-sided SOVT, the choroid in the left eye was thickened and the choroidal vessels were dilated both superiorly and inferiorly, with greater changes evident in the inferotemporal region of the choroid. After the superior ophthalmic vein was decompressed, a decrease in the choroidal thickness and choroidal vessel dilatation was observed both superiorly and inferiorly.

Conclusions and importance

In an eye with thrombosis of the superior ophthalmic vein, longitudinal SS-OCT choroidal imaging showed a greater increase in choroidal thickness and choroidal vessel dilation away from the obstructed quadrant, which improved after treatment. These observations associated with outflow obstruction may be applicable to other choroidal diseases characterized by venous overload.

Branch retinal artery occlusion from laser pointer misuse

Purpose

To report a case of branch retinal artery occlusion (BRAO) following exposure to a blue laser pointer in a healthy 22-year-old male.

Observations

A 22-year-old healthy male presented with sudden visual field impairment in his right eye, occurring 18 hours after exposure to a blue laser pointer. He complained of an immediate persistent curtain-like obstruction in the upper visual field of the affected eye. Clinical examinations revealed BRAO in the inferior half of the retina, confirmed by Optical coherence tomography (OCT) showing edema. Fluorescein angiography indicated delayed filling and a focal hyperfluorescence area, consistent with a leak. Due to a lack of established management, the patient was offered follow-up care. Though reperfusion was observed on fluorescein angiography one month later, thinning of the retinal layers was evident on OCT, and there was no visual recovery.

Conclusions and Importance

In conclusion, laser pointers, though often considered innocuous, can lead to serious ocular damage. The clinical implications of laser-induced retinal injury are severe and sometimes irreversible, warranting special attention. The observed clinical course underscores the complex nature of such injuries and emphasizes the importance of awareness and caution regarding laser pointer use.

Periocular granulomatous inflammatory lesions mimicking conjunctival melanoma recurrence in the setting of systemic nivolumab treatment

Purpose

Conjunctival melanoma is a rare neoplasm with high rates of recurrence and metastasis. Traditional management includes surgical excision and cryotherapy, followed by adjuvant therapy as needed. Immune checkpoint inhibitors, including nivolumab, are a targeted treatment option with improved survival rates. However, various immune-related adverse effects have been reported with these drugs. While systemic granulomatous inflammation is a documented systemic side effect, it has rarely been reported in the conjunctiva and ocular adnexa.

Observation

A patient with a history of recurrent metastatic conjunctival melanoma presented with both a left sub-conjunctival and upper eyelid lesion after the commencement of treatment with nivolumab. The lesions were excised with a clinical suspicion for metastasis and consisted of noncaseating granulomatous inflammation with no evidence of malignancy on histopathologic examination. Infectious and primary autoimmune etiologies were ruled out.

Conclusion and importance

This is a biopsy-proven case of periocular immune checkpoint inhibitor-associated granulomatous inflammation.

Improvement in signs and symptoms of severe dry eye disease after dual therapy with high-potency steroids and 0.05% cyclosporine

OBJECTIVE

To evaluate the effectiveness and safety of combining 0.05% cyclosporine A (CsA) with high-potency steroids for treating severe dry eye disease (DED).

MATERIALS AND METHODS

This retrospective comparative case series included 93 patients treated with 0.05% CsA for severe DED. Among them, we included data from 54 eyes of 27 patients who received high-potency steroids in the study group and from 132 eyes of 66 patients who did not receive high-potency steroids in the control group. Data on demographic characteristics, comorbidities, medications and intraocular pressure (IOP) were recorded. The primary outcomes were changes in symptom and sign scores. The ocular surface disease index was used as the symptom score, whereas tear break-up time, Schirmer I test without anaesthesia, ocular surface staining scores and presence of meibomian gland dysfunction were considered as sign scores. Repeated one-way ANOVA and generalized linear mixed models were used to evaluate differences.

RESULTS

In the control group, symptom scores decreased from 1 to 2 months and from 2 to 3 months after treatment (p = .002 and .049). In the high-potency steroid group, symptom scores improved during these intervals (p = .003 and .005). The sign score in the control group remained unchanged (all p > .05), while the high-potency steroid group exhibited progressive improvement in sign scores (all p < .05). The high-potency steroid group had more favourable symptom (p = .035) and sign (p < .001) scores than did the control group. However, multiple systemic diseases were associated with poor symptom (p = .025) and sign (p = .014) scores. The risks for glaucoma and cataract formation were similar between the two groups (all p > .05).

CONCLUSIONS

Dual therapy combining high-potency steroids and 0.05% CsA significantly improved the signs and symptoms of severe DED compared with 0.05% CsA monotherapy, without severe complications.

Advances in the study of tissue-engineered retinal pigment epithelial cell sheets

Regarded as the most promising treatment modality for retinal degenerative diseases, retinal pigment epithelium cell replacement therapy holds significant potential. Common retinal degenerative diseases, including Age-related Macular Degeneration, are frequently characterized by damage to the unit comprising photoreceptors, retinal pigment epithelium, and Bruch's membrane. The selection of appropriate tissue engineering materials, in conjunction with retinal pigment epithelial cells, for graft preparation, can offer an effective treatment for retinal degenerative diseases. This article presents an overview of the research conducted on retinal pigment epithelial cell tissue engineering, outlining the challenges and future prospects.

Emerging role and the signaling pathways of uncoupling protein 2 in kidney diseases

OBJECTIVES

Uncoupling protein 2 (UCP2) was involved in the pathogenesis and development of kidney diseases. Many signaling pathways and factors regulate the expression of UCP2. We aimed to investigate the precise role of UCP2 and its signaling pathways in kidney diseases.

METHODS

We summarized the available evidence to yield a more detailed conclusion of the signal transduction pathways of UCP2 and its role in the development and progression of kidney diseases.

RESULTS

UCP2 could interact with 14.3.3 family proteins, mitochondrial phospholipase iPLA2γ, NMDAR, glucokinase, PPARγ2. There existed a signaling pathway between UCP2 and NMDAR, PPARγ. UCP2 can inhibit the ROS production, inflammatory response, and apoptosis, which may protect against renal injury, particularly AKI. Meanwhile UCP2 can decrease ATP production and inhibit the secretion of insulin, which may alleviate chronic renal damages, such as diabetic nephropathy and kidney fibrosis.

CONCLUSIONS

Homeostasis of UCP2 is helpful for kidney health. UCP2 may play different roles in different kinds of renal injury.

Hyperglycemia-induced oxidative stress exacerbates mitochondrial apoptosis damage to cochlear stria vascularis pericytes via the ROS-mediated Bcl-2/CytC/AIF pathway

OBJECTIVES

Diabetes is closely linked to hearing loss, yet the exact mechanisms remain unclear. Cochlear stria vascularis and pericytes (PCs) are crucial for hearing. This study investigates whether high glucose induces apoptosis in the cochlear stria vascularis and pericytes via elevated ROS levels due to oxidative stress, impacting hearing loss.

METHODS

We established a type II diabetes model in C57BL/6J mice and used auditory brainstem response (ABR), Evans blue staining, HE staining, immunohistochemistry, and immunofluorescence to observe changes in hearing, blood-labyrinth barrier (BLB) permeability, stria vascularis morphology, and apoptosis protein expression. Primary cultured stria vascularis pericytes were subjected to high glucose, and apoptosis levels were assessed using flow cytometry, Annexin V-FITC, Hoechst 33342 staining, Western blot, Mitosox, and JC-1 probes.

RESULTS

Diabetic mice showed decreased hearing thresholds, reduced stria vascularis density, increased oxidative stress, cell apoptosis, and decreased antioxidant levels. High glucose exposure increased apoptosis and ROS content in pericytes, while mitochondrial membrane potential decreased, with AIF and cytochrome C (CytC) released from mitochondria to the cytoplasm. Adding oxidative scavengers reduced AIF and CytC release, decreasing pericyte apoptosis.

DISCUSSION

Hyperglycemia may induce mitochondrial apoptosis of cochlear stria vascularis pericytes through oxidative stress.

M2 macrophages promote subconjunctival fibrosis through YAP/TAZ signalling

PURPOSE

To evaluate the role of M2 macrophages in subconjunctival fibrosis after silicone implantation (SI) and investigate the underlying mechanisms.

MATERIALS AND METHODS

A model of subconjunctival fibrosis was established by SI surgery in rabbit eyes. M2 distribution and collagen deposition were evaluated by histopathology. The effects of M2 cells on the migration (using wound-scratch assay) and activation (by immunofluorescence and western blotting) of human Tenon's fibroblasts (HTFs) were investigated.

RESULTS

There were more M2 macrophages (CD68+/CD206+ cells) occurring in tissue samples around silicone implant at 2 weeks postoperatively. Dense collagen deposition was observed at 8 weeks after SI. In vitro experiment showed M2 expressed high level of CD206 and transforming growth factor-β1 (TGF-β1). The M2-conditioned medium promoted HTFs migration and the synthesis of collagen I and fibronectin. Meanwhile, M2-conditioned medium increased the protein levels of TGF-β1, TGF-βR II, p-Smad2/3, yes-associated protein (YAP), and transcriptional coactivator with PDZ-binding motif (TAZ). Verteporfin, a YAP inhibitor, suppressedTGF-β1/Smad2/3-YAP/TAZ pathway and attenuated M2-induced extracellular matrix deposition by HTFs.

CONCLUSIONS

TGF-β1/Smad2/3-YAP/TAZ signalling may be involved in M2-induced fibrotic activities in HTFs. M2 plays a key role in promoting subconjunctival fibrosis and can serve as an attractive target for anti-fibrotic therapeutics.

Biomaterial engineering strategies for modeling the Bruch's membrane in age-related macular degeneration

Age-related macular degeneration, a multifactorial inflammatory degenerative retinal disease, ranks as the leading cause of blindness in the elderly. Strikingly, there is a scarcity of curative therapies, especially for the atrophic advanced form of age-related macular degeneration, likely due to the lack of models able to fully recapitulate the native structure of the outer blood retinal barrier, the prime target tissue of age-related macular degeneration. Standard in vitro systems rely on 2D monocultures unable to adequately reproduce the structure and function of the outer blood retinal barrier, integrated by the dynamic interaction of the retinal pigment epithelium, the Bruch's membrane, and the underlying choriocapillaris. The Bruch's membrane provides structural and mechanical support and regulates the molecular trafficking in the outer blood retinal barrier, and therefore adequate Bruch's membrane-mimics are key for the development of physiologically relevant models of the outer blood retinal barrier. In the last years, advances in the field of biomaterial engineering have provided novel approaches to mimic the Bruch's membrane from a variety of materials. This review provides a discussion of the integrated properties and function of outer blood retinal barrier components in healthy and age-related macular degeneration status to understand the requirements to adequately fabricate Bruch's membrane biomimetic systems. Then, we discuss novel materials and techniques to fabricate Bruch's membrane-like scaffolds for age-related macular degeneration in vitro modeling, discussing their advantages and challenges with a special focus on the potential of Bruch's membrane-like mimics based on decellularized tissue.

Development of a novel SupraChoroidal-to-Optic-NervE (SCONE) drug delivery system

PURPOSE

Targeted drug delivery to the optic nerve head may be useful in the preclinical study and later clinical management of optic neuropathies, however, there are no FDA-approved drug delivery systems to achieve this. The purpose of this work was to develop an optic nerve head drug delivery technique.

METHODS

Different strategies to approach the optic nerve head were investigated, including standard intravitreal and retroorbital injections. A novel SupraChoroidal-to-Optic-NervE (SCONE) delivery was optimized by creating a sclerotomy and introducing a catheter into the suprachoroidal space. Under direct visualization, the catheter was guided to the optic nerve head. India ink was injected. The suprachoroidal approach was performed in New Zealand White rabbit eyes in vivo (25 animals total). Parameters, including microneedle size and design, catheter design, and catheter tip angle, were optimized ex vivo and in vivo.

RESULTS

Out of the candidate optic nerve head approaches, intravitreal, retroorbital, and suprachoroidal approaches were able to localize India ink to within 2 mm of the optic nerve. The suprachoroidal approach was further investigated, and after optimization, was able to deposit India ink directly within the optic nerve head in up to 80% of attempts. In eyes with successful SCONE delivery, latency and amplitude of visual evoked potentials was not different than the naïve untreated eye.

CONCLUSIONS

SCONE delivery can be used for targeted drug delivery to the optic nerve head of rabbits without measurable toxicity measured anatomically or functionally. Successful development of this system may yield novel opportunities to study optic nerve head-specific drug delivery in animal models, and paradigm-shifting management strategies for treating optic neuropathies.

TRANSLATIONAL RELEVANCE

Here we demonstrate data on a new method for targeted delivery to the optic nerve head, addressing a significant unmet need in therapeutics for optic neuropathies.

Causal relationship between 731 immune cells and the risk of diabetic nephropathy: a two‑sample bidirectional Mendelian randomization study

OBJECTIVE

Previous observational studies have indicated associations between various immune cells and diabetic nephropathy (DN). However, the causality remains unclear. We aimed to further evaluate the causal association between immune cells and DN using bidirectional two-sample Mendelian randomization (MR) analysis.

METHOD

The DN data were retrieved from the IEU OpenGWAS Project database, while the data for 731 immune cells were sourced from GWAS summary statistics by Orru ̀ et al. The investigation into the causal relationship between immune cells and DN employed the inverse variance weighted (IVW), weighted median (WME), and MR-Egger methods. The stability and reliability of the findings underwent evaluation through Cochran's Q test, MR-Egger intercept's P-value, MR-PRESSO, and Leave-One-Out (LOO) method.

RESULT

The IVW estimates suggested a positive causal effect of CD25 on IgD-CD38dim B cell, CD25 on naive-mature B cell, CD127 on granulocyte, SSC-A on HLA DR + Natural Killer, HLA DR on plasmacytoid Dendritic Cell, and HLA DR on Dendritic Cell on DN. Conversely, the abundance of Myeloid Dendritic Cell, CD62L- Dendritic Cell %Dendritic Cell, CD86+ myeloid Dendritic Cell %Dendritic Cell, CD14- CD16-, CX3CR1 on CD14- CD16-, and SSC-A on CD4+ T cell had negative causal effects on DN. However, after correcting the P value for significant causality results using the FDR method, it was concluded that only Myeloid Dendritic Cells had a causal relationship with DN (FDR-p = 0.041), while the other immune cells showed no significant association with DN, so their relationship was suggestive. The results were stable with no observed horizontal pleiotropy and heterogeneity. Reverse MR analysis indicated no causal relationship between DN and the increased risk of positively identified immune cells.

CONCLUSION

This study provides an initial insight into the genetic perspective of the causal relationship between immune cells and DN. It establishes a crucial theoretical foundation for future endeavors in precision medicine and individualized treatment.

An in vitro 3-dimensional Collagen-based Corneal Construct with Innervation Using Human Corneal Cell Lines

Purpose

To develop a 3-dimensional corneal construct suitable for in vitro studies of disease conditions and therapies.

Design

In vitro human corneal constructs were created using chemically crosslinked collagen and chondroitin sulfate extracellular matrix and seeded with 3 human corneal cell types (epithelial, stromal, and endothelial) together with neural cells. The neural cells were derived from hybrid neuroblastoma cells and the other cells used from immortalized human corneal cell lines. To check the feasibility and characterize the constructs, cytotoxicity, cell proliferation, histology, and protein expression studies were performed.

Results

Optimized culture condition permitted synchronized viability across the cell types within the construct. The construct showed a typical appearance for different cellular layers, including healthy appearing, phenotypically differentiated neurons. The expected protein expression profiles for specific cell types within the construct were confirmed with western blotting.

Conclusions

An in vitro corneal construct was successfully developed with maintenance of individual cell phenotypes with anatomically correct cellular loci. The construct may be useful in evaluation of specific corneal disorders and in developing different corneal disease models. Additionally, the construct can be used in evaluating drug targeting and/or penetration to individual corneal layers, testing novel therapeutics for corneal diseases, and potentially reducing the necessity for animals in corneal research at the early stages of investigation.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Reticular Pseudodrusen: Impact of Their Presence and Extent on Local Rod Function in Age-Related Macular Degeneration

Purpose

To understand the spatial relationship between local rod-mediated visual function and reticular pseudodrusen (RPD) in eyes with large drusen.

Design

Retrospective cross-sectional study.

Participants

One eye with large drusen (>125 μm) each from 91 individuals with intermediate age-related macular degeneration, with and without RPD.

Methods

All participants underwent dark adaptation testing using a dark-adapted chromatic perimeter, where visual sensitivities were measured over 30 minutes of dark adaptation after photobleach. The rod intercept time (RIT; a measure of dynamic rod function) and pointwise sensitivity difference (PWSD; a relative measure of rod- compared with cone-mediated function) was determined at multiple retinal locations, and their association with the overall (central 20° × 20° region) and local (2° diameter region centered on the location tested) extent of RPD and drusen (quantified using multimodal imaging) was examined.

Main Outcome Measures

Association between overall and local extent of RPD and drusen with RIT and PWSD at each retinal location tested.

Results

In a multivariable analysis, delayed RIT was associated with an increasing overall (P < 0.001), but not local (P = 0.884), extent of RPD. In contrast, the increasing local (P < 0.001), but not overall (P = 0.475), extent of drusen was associated with delayed RIT. Furthermore, only an increasing overall extent of RPD (P < 0.001) was associated with reduced PWSD (or worse rod compared with cone function), but not the local extent of RPD and drusen, or overall extent of drusen (P ≥ 0.344).

Conclusions

Local rod-mediated function was associated with the overall, rather than local, extent of RPD in eyes with large drusen, suggesting that there may be widespread pathologic changes in eyes with RPD that account for this.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Characterization of Retinal Microvascular Abnormalities in Birdshot Chorioretinopathy Using OCT Angiography

Objective

To characterize changes in the retinal microvasculature in eyes with birdshot chorioretinopathy (BCR) using OCT angiography (OCTA).

Design

Retrospective, observational, single center.

Subjects

Twenty-eight patients (53 eyes) with BCR and 59 age-matched controls (110 eyes).

Methods

En face OCTA images of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) of each eye were assessed for the presence of microvascular abnormalities and used to measure the vessel and foveal avascular zone (FAZ) areas. A longitudinal analysis was performed with a representative cohort of 23 BCR eyes (16 patients) at baseline and at a 2-year time point.

Main Outcome Measures

Whole-image vessel density (VD, %), extrafoveal avascular zone (extra-FAZ) VD (%), and FAZ area (%) were calculated and compared between control and BCR eyes. The frequency of microvascular abnormalities in BCR eyes was recorded.

Results

In the SCP, increased intercapillary space and capillary loops were common features present on OCTA images. Whole-image and extra-FAZ VD were lower in the BCR group compared with controls (P < 0.0001 [SCP and DCP]). Foveal avascular zone area was enlarged in BCR eyes (P = 0.0008 [DCP]). Worsening best-corrected visual acuity was associated with a decrease in whole-image and extra-FAZ VD in the SCP (P < 0.0001 for both) and the DCP (P < 0.005 for both). Multivariable analysis, with vessel analysis parameters as outcomes, demonstrated that increasing age, increasing disease duration, lower central subfield thickness, and treatment-naive eyes (compared with those on only biologics) were associated with a significant decrease in both DCP whole-image and extra-FAZ VD. Increasing disease duration was associated with a significant decrease in both SCP whole-image and extra-FAZ VD. Longitudinal analysis demonstrated no significant difference in any vessel analysis parameters except for an increase in DCP FAZ area.

Conclusions

Our results demonstrate a significant a decrease in VD in BCR eyes and an association on multivariable analysis with disease duration. Quantifying VD in the retinal microvasculature may be a useful biomarker for monitoring disease severity and progression in patients with BCR. Further studies with extended longitudinal follow-up are needed to characterize its utility in monitoring disease progression and treatment response.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Risk Factors for Focal Choroidal Excavation Concurrent with Chorioretinal Disease: Evaluated by Spectral-Domain OCT

Purpose

To investigate the risk factors for patients with focal choroidal excavation (FCE) and their correlation with chorioretinal diseases.

Design

Retrospective cross-sectional study.

Subjects

Patients with FCE were enrolled, while healthy subjects were recruited for the control group.

Methods

The study collected demographic information, clinical features, and multimodal images. Parameters of FCE identified using spectral-domain OCT (SD-OCT) were manually measured using built-in software and subsequently analyzed statistically.

Main Outcome Measures

Subfoveal choroidal thickness (SFCT), subexcavation choroidal thickness (SECT), and the greatest depth and width of each excavation were manually measured using built-in calipers in OCT software.

Results

Twenty-one patients (13/8, male/female) with FCE were included in this study. The average age was 45.2 years, and their best-corrected visual acuity (BCVA) was 0.4 logarithm of the minimum angle of resolution (Snellen equivalent, 20/50). Focal choroidal excavation was present in 28 eyes of 21 patients, including isolated FCE (12 eyes) and complicated FCE (16 eyes) with choroidal neovascularization (sCNV), central serous chorioretinopathy, and other conditions. Patients with complicated FCE were significantly older than those isolated FCE (P = 0.015). The SFCT of the healthy subjects was significantly less than that of the fellow eyes of the patients with FCE (P < 0.01), as was that of the eyes with isolated FCE (P < 0.001) and complicated FCE (P < 0.001). The width of excavation was wider in eyes with complicated FCE than in those with isolated FCE (P = 0.001). Hypertransmission defect (HD) was found beneath 15 excavations and was more prevalent in the complicated FCE group than the isolated FCE group (P = 0.023).

Conclusions

Focal choroidal excavation appears to be closely related to chorioretinal disorders, and the width of the excavation is a significant indicator for evaluating the risk of chorioretinal diseases.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Deep Learning-Based Clustering of OCT Images for Biomarker Discovery in Age-Related Macular Degeneration (PINNACLE Study Report 4)

Purpose

We introduce a deep learning-based biomarker proposal system for the purpose of accelerating biomarker discovery in age-related macular degeneration (AMD).

Design

Retrospective analysis of a large data set of retinal OCT images.

Participants

A total of 3456 adults aged between 51 and 102 years whose OCT images were collected under the PINNACLE project.

Methods

Our system proposes candidates for novel AMD imaging biomarkers in OCT. It works by first training a neural network using self-supervised contrastive learning to discover, without any clinical annotations, features relating to both known and unknown AMD biomarkers present in 46 496 retinal OCT images. To interpret the learned biomarkers, we partition the images into 30 subsets, termed clusters, that contain similar features. We conduct 2 parallel 1.5-hour semistructured interviews with 2 independent teams of retinal specialists to assign descriptions in clinical language to each cluster. Descriptions of clusters achieving consensus can potentially inform new biomarker candidates.

Main Outcome Measures

We checked if each cluster showed clear features comprehensible to retinal specialists, if they related to AMD, and how many described established biomarkers used in grading systems as opposed to recently proposed or potentially new biomarkers. We also compared their prognostic value for late-stage wet and dry AMD against an established clinical grading system and a demographic baseline model.

Results

Overall, both teams independently identified clearly distinct characteristics in 27 of 30 clusters, of which 23 were related to AMD. Seven were recognized as known biomarkers used in established grading systems, and 16 depicted biomarker combinations or subtypes that are either not yet used in grading systems, were only recently proposed, or were unknown. Clusters separated incomplete from complete retinal atrophy, intraretinal from subretinal fluid, and thick from thin choroids, and, in simulation, outperformed clinically used grading systems in prognostic value.

Conclusions

Using self-supervised deep learning, we were able to automatically propose AMD biomarkers going beyond the set used in clinically established grading systems. Without any clinical annotations, contrastive learning discovered subtle differences between fine-grained biomarkers. Ultimately, we envision that equipping clinicians with discovery-oriented deep learning tools can accelerate the discovery of novel prognostic biomarkers.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Developmental Changes in How Head Orientation Structures Infants' Visual Attention

Most studies of developing visual attention are conducted using screen-based tasks in which infants move their eyes to select where to look. However, real-world visual exploration entails active movements of both eyes and head to bring relevant areas in view. Thus, relatively little is known about how infants coordinate their eyes and heads to structure their visual experiences. Infants were tested every 3 months from 9 to 24 months while they played with their caregiver and three toys while sitting in a highchair at a table. Infants wore a head-mounted eye tracker that measured eye movement toward each of the visual targets (caregiver's face and toys) and how targets were oriented within the head-centered field of view (FOV). With age, infants increasingly aligned novel toys in the center of their head-centered FOV at the expense of their caregiver's face. Both faces and toys were better centered in view during longer looking events, suggesting that infants of all ages aligned their eyes and head to sustain attention. The bias in infants' head-centered FOV could not be accounted for by manual action: Held toys were more poorly centered compared with non-held toys. We discuss developmental factors-attentional, motoric, cognitive, and social-that may explain why infants increasingly adopted biased viewpoints with age.

Single-cell RNA sequencing analysis of the retina under acute high intraocular pressure

JOURNAL/nrgr/04.03/01300535-202419110-00032/figure1/v/2024-03-08T184507Z/r/image-tiff High intraocular pressure causes retinal ganglion cell injury in primary and secondary glaucoma diseases, yet the molecular landscape characteristics of retinal cells under high intraocular pressure remain unknown. Rat models of acute hypertension ocular pressure were established by injection of cross-linked hyaluronic acid hydrogel (Healaflow®). Single-cell RNA sequencing was then used to describe the cellular composition and molecular profile of the retina following high intraocular pressure. Our results identified a total of 12 cell types, namely retinal pigment epithelial cells, rod-photoreceptor cells, bipolar cells, Müller cells, microglia, cone-photoreceptor cells, retinal ganglion cells, endothelial cells, retinal progenitor cells, oligodendrocytes, pericytes, and fibroblasts. The single-cell RNA sequencing analysis of the retina under acute high intraocular pressure revealed obvious changes in the proportions of various retinal cells, with ganglion cells decreased by 23%. Hematoxylin and eosin staining and TUNEL staining confirmed the damage to retinal ganglion cells under high intraocular pressure. We extracted data from retinal ganglion cells and analyzed the retinal ganglion cell cluster with the most distinct expression. We found upregulation of the B3gat2 gene, which is associated with neuronal migration and adhesion, and downregulation of the Tsc22d gene, which participates in inhibition of inflammation. This study is the first to reveal molecular changes and intercellular interactions in the retina under high intraocular pressure. These data contribute to understanding of the molecular mechanism of retinal injury induced by high intraocular pressure and will benefit the development of novel therapies.

Retinal Microvasculature Causally Affects the Brain Cortical Structure: A Mendelian Randomization Study

Purpose

To reveal the causality between retinal vascular density (VD), fractal dimension (FD), and brain cortex structure using Mendelian randomization (MR).

Design

Cross-sectional study.

Participants

Genome-wide association studies of VD and FD involving 54 813 participants from the United Kingdom Biobank were used. The brain cortical features, including the cortical thickness (TH) and surface area (SA), were extracted from 51 665 patients across 60 cohorts. Surface area and TH were measured globally and in 34 functional regions using magnetic resonance imaging.

Methods

Bidirectional univariable MR (UVMR) was used to detect the causality between FD, VD, and brain cortex structure. Multivariable MR (MVMR) was used to adjust for confounding factors, including body mass index and blood pressure.

Main Outcome Measures

The global and regional measurements of brain cortical SA and TH.

Results

At the global level, higher VD is related to decreased TH (β = -0.0140 mm, 95% confidence interval: -0.0269 mm to -0.0011 mm, P = 0.0339). At the functional level, retinal FD is related to the TH of banks of the superior temporal sulcus and transverse temporal region without global weighted, as well as the SA of the posterior cingulate after adjustment. Vascular density is correlated with the SA of subregions of the frontal lobe and temporal lobe, in addition to the TH of the inferior temporal, entorhinal, and pars opercularis regions in both UVMR and MVMR. Bidirectional MR studies showed a causation between the SA of the parahippocampal and cauda middle frontal gyrus and retinal VD. No pleiotropy was detected.

Conclusions

Fractal dimension and VD causally influence the cortical structure and vice versa, indicating that the retinal microvasculature may serve as a biomarker for cortex structural changes. Our study provides insights into utilizing noninvasive fundus images to predict cortical structural deteriorations and neuropsychiatric disorders.

Financial Disclosures

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Extraction, physicochemical properties, bioactivities and application of natural sweeteners: A review

Natural sweeteners generally refer to a sweet chemical component directly extracted from nature or obtained through appropriate modifications, mainly secondary metabolites of plants. Compared to the first-generation sweeteners represented by sucrose and the second-generation sweeteners represented by sodium cyclamate, natural sweeteners usually have high sweetness, low-calorie content, good solubility, high stability, and rarely toxic side effects. Historically, researchers mainly focus on the function of natural sweeteners as substitutes for sugars in the food industry. This paper reviews the bioactivities of several typical natural sweeteners, including anti-cancer, anti-inflammatory, antioxidant, anti-bacterial, and anti-hyperglycemic activities. In addition, we have summarized the extraction, physicochemical properties, and application of natural sweeteners. The article aimed to comprehensively collate vital information about natural sweeteners and review the potentiality of tapping bioactive compounds from natural products. Hopefully, this review provides insights into the further development of natural sweeteners as therapeutic agents and functional foods.

Systemic Oxidative Stress Level as a Pathological and Prognostic Factor in Myopic Choroidal Neovascularization

Purpose

To investigate the association of systemic oxidative stress level with myopic choroidal neovascularization (mCNV) and its clinical outcomes.

Design

Retrospective case-control study.

Participants

This retrospective study included 52 eyes of 52 healthy participants (mean age: 62.5 years), 30 eyes of 30 patients (mean age: 59.6 years) with high myopia (HM) but without mCNV, and 23 eyes of 23 patients (mean age: 61.8 years) with HM and mCNV who received intravitreal anti-VEGF antibody injections (IVIs) using a pro re nata regimen during the 6-month follow-up after the first IVI.

Methods

Clinical findings, including oxidative stress parameters, such as diacron reactive oxygen metabolites (dROMs), biological antioxidant potential (BAP), and the BAP/dROM ratio (B/d ratio), were analyzed.

Main Outcome Measures

Clinical features and oxidative stress parameters.

Results

Both BAP and the B/d ratio were significantly lower in the HM/mCNV group than in the HM/no mCNV group (P = 0.002 and P = 0.012, respectively) and than in the control group (P = 0.001 and P = 0.026, respectively). In a multiple logistic regression analysis, axial length (odds ratio 1.878, P = 0.042) and the B/d ratio (odds ratio 0.470, P = 0.026) were significantly associated with mCNV. Dividing the patients into high and low B/d ratio groups (with a cutoff of 5.2) showed that subfoveal choroidal thickness (SFCT) was lower (P = 0.002) and the number of IVI treatments was higher (P = 0.029) in the low B/d ratio group than in the high B/d ratio group. In multiple regression analyses, only the B/d ratio was significantly associated with SFCT (β = 0.684, P = 0.006).

Conclusions

The oxidative stress level in eyes with HM differed according to mCNV, SFCT, and the number of IVI treatments. Measuring oxidative stress parameters might be useful in eyes with HM both for assessing the risk of developing mCNV and determining disease activity.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

UPLC-MS/MS reveals the differences in lipids composition of Camellia oleifera from northern margin distribution area

The lipids accumulation characteristics in 23Camellia oleifera lines from northern margin distribution area were investigated through quantitative lipidomics. Combined lipids content-function analysis indicated that NQ1, HT1, HT2, ZA2, ZB1, ZB2, and SN2 lines had potential to develop functional foods due to abundant glycerolipids (GLs), glycerophospholipids (GPs), fatty acids (FAs), and prenol lipids (PRs). 673 lipids components were detected, and 293 differential components were identified in NQ1, ZA2, HB1, and HT1. 4 kinds free fatty acids (FFAs) were higher in NQ1, 5 triglycerides (TGs) were higher in HT1, and 2 phosphatidyl serines (PSs) and 1 phosphatidyl glycerol (PG) were higher in ZA2. GLs, GPs, and FFAs had strong relation at intra- and inter-category level. Glycerolipid metabolism, glycerophospholipid metabolism, and fatty acid biosynthesis were the significantly differential lipids pathways. Our study elucidated lipids differences of 23 C. oleifera lines, and offered valuable references for lipids biosynthesis, directional breeding, and lipids utilization.

Comprehensive genetic analysis uncovers the mutational spectrum of MFRP and its genotype-phenotype correlation in a large cohort of Chinese microphthalmia patients

PURPOSE

Microphthalmia is a severe congenital ocular disease featured by abnormal ocular development. The aim of this study was to detail the genetic and clinical characteristics of a large cohort of Chinese patients with microphthalmia related to MFRP variants, focusing on uncovering genotype-phenotype correlations.

METHODS

Fifty microphthalmia patients from 44 unrelated Chinese families were recruited. Whole-exome sequencing (WES) was conducted to analyze the coding regions and adjacent intronic regions of MFRP. Axial lengths (AL) were measured for all probands and available family members. Protein structures of mutations with high frequency in our cohort were predicted. The genotype-phenotype correlations were explored by statistical analysis.

RESULTS

Sixteen MFRP variants were detected in 17 families, accounting for 38.64 % of all microphthalmia families. There were 9 novel mutations (c.427+1G>C, c.428-2A>C, c.561_575del:p.A188_E192del, c.836G>A:p.C279Y, c.1010_1021del:p.H337_E340del:p.Y479*, c.1516_1517del:p.S506Pfs*66, c.1561T>G:p.C521G, c.1616G>A:p.R539H, and c.1735C>T:p.P579S) and six previously reported variants in MFRP, with p.E496K and p.H337_E340del being highly frequent, found in eight (47.06 %) and two families (11.76 %), respectively. Seven variants (43.75 %) were located in the C-terminal cysteine-rich frizzled-related domain (CRD) (7/16, 43.75 %). Protein prediction implicated p.E496K and p.H337_E340del mutations might lead to a destabilization of the MFRP protein. The average AL of all 42 eyes was 16.02 ± 1.05 mm, and 78.36 % of eyes with AL < 16 mm harbored p.E496K variant. Twenty-six eyes with variant variant had shorter AL than that of the other 16 eyes without this variant (p = 0.006), highlighting a novel genotype-phenotype correlation.

CONCLUSIONS

In this largest cohort of Chinese patients with microphthalmia, the 9 novel variants, high frequency of p.E496W, and mutation hotspots in CRD reveals unique insights into the MFRP mutation spectrum among Chinese patients, indicating ethnic variability. A new genotype-phenotype correlation that p.E496K variant associated with a shorter AL is unveiled. Our findings enhance the current knowledge of MFRP-associated microphthalmia and provide valuable information for prenatal diagnosis as well as future therapy.

Genotype-phenotype profile of global ASPH-associated ectopia lentis and clinical findings from a Chinese cohort

BACKGROUND

Traboulsi syndrome is an under-recognized syndromic form of ectopia lentis (EL) caused by the aspartate beta-Hydroxylase (ASPH) variant. The genotype-phenotype profile of ASPH-associated disease is poorly understood due to the rarity of the condition.

METHODS

We conducted targeted next-generation sequencing and bioinformatics analysis to identify potentially pathogenic ASPH variants in the cohort. Furthermore, we characterized the expression pattern of ASPH and major components of the zonules using single-cell RNA-sequencing (scRNA-seq) and evaluated the genotype-phenotype correlations by combining our data and those from the literature.

RESULTS

We identified a novel missense variant c.2075G > A (p.G692D) and a recurrent nonsense variant c.1126C > G (p.R376*) of ASPH in two pedigrees from a Chinese cohort of EL. Both probands were 5-year-old boys with canonical facial dysmorphisms and bilateral anteriorly-dislocated lenses. Other ocular comorbidities included microspherophakia, shallow anterior chamber, and narrow chamber angel. No cardiac involvements or filtering blebs were identified. The single-cell expression atlas of ciliary epithelium demonstrated the coexpression of ASPH with FBN1, FBN2, and LTBP2 in the non-pigmented ciliary epithelium cells. Furthermore, molecular modeling simulation of p.G692D revealed increased affinity to the cb EGF-like domain and a subsequent destabilized calcium-binding motif. The genotype-phenotype analysis demonstrated that patients with cardiac involvements all harbored biallelic truncation variants.

CONCLUSIONS

The data from this study provide new insights into the genotype-phenotype profile of ASPH-associated disease and implicate the potential role of ASPH in the pathogenesis of EL.

p38 MAPK inhibitor SB202190 suppresses ferroptosis in the glutamate-induced retinal excitotoxicity glaucoma model

JOURNAL/nrgr/04.03/01300535-202410000-00031/figure1/v/2024-02-06T055622Z/r/image-tiff Glutamate excitotoxicity has been shown to play an important role in glaucoma, and glutamate can induce ferroptosis. The p38 mitogen-activated protein kinase (MAPK) pathway inhibitor SB202190 has a potential ability to suppress ferroptosis, and its downstream targets, such as p53, have been shown to be associated with ferroptosis. However, whether ferroptosis also occurs in retinal ganglion cells in response to glutamate excitotoxicity and whether inhibition of ferroptosis reduces the loss of retinal ganglion cells induced by glutamate excitotoxicity remain unclear. This study investigated ferroptosis in a glutamate-induced glaucoma rat model and explored the effects and molecular mechanisms of SB202190 on retinal ganglion cells. A glutamate-induced excitotoxicity model in R28 cells and an N-methyl-D-aspartate-induced glaucoma model in rats were used. In vitro experiments showed that glutamate induced the accumulation of iron and lipid peroxide and morphological changes of mitochondria in R28 cells, and SB202190 inhibited these changes. Glutamate induced the levels of p-p38 MAPK/p38 MAPK and SAT1 and decreased the expression levels of ferritin light chain, SLC7A11, and GPX4. SB202190 inhibited the expression of iron death-related proteins induced by glutamate. In vivo experiments showed that SB202190 attenuated N-methyl-D-aspartate-induced damage to rat retinal ganglion cells and improved visual function. These results suggest that SB202190 can inhibit ferroptosis and protect retinal ganglion cells by regulating ferritin light chain, SAT1, and SLC7A11/Gpx4 pathways and may represent a potential retina protectant.

Molecular Mechanisms of Glaucoma Pathogenesis with Implications to Caveolin Adaptor Protein and Caveolin-Shp2 Axis

Glaucoma is a common retinal disorder characterized by progressive optic nerve damage, resulting in visual impairment and potential blindness. Elevated intraocular pressure (IOP) is a major risk factor, but some patients still experience disease progression despite IOP-lowering treatments. Genome-wide association studies have linked variations in the Caveolin1/2 (CAV-1/2) gene loci to glaucoma risk. Cav-1, a key protein in caveolae membrane invaginations, is involved in signaling pathways and its absence impairs retinal function. Recent research suggests that Cav-1 is implicated in modulating the BDNF/TrkB signaling pathway in retinal ganglion cells, which plays a critical role in retinal ganglion cell (RGC) health and protection against apoptosis. Understanding the interplay between these proteins could shed light on glaucoma pathogenesis and provide potential therapeutic targets.

Novel therapeutic receptor agonists and antagonists in allergic conjunctivitis

PURPOSE OF REVIEW

Allergic conjunctivitis is characterized by the development of pathophysiological changes to the ocular surface, which occurs when pro-allergic and pro-inflammatory mediators interact with their cognate receptors expressed on immune and nonimmune cells. Traditional treatments with antihistamines and corticosteroids provide relief, but there is a need for more efficacious and tolerable long-term therapy with a better safety profile. This article aims to provide an overview of the mode of action and clinical application of agonist therapies targeting glucocorticoid, melanocortin, and toll-like receptors, as well as antagonist therapies targeting cytokine, chemokine, integrin, and histamine receptors.

RECENT FINDINGS

There has been considerable advancement in immunology and pharmacology, as well as a greater understanding of the cellular and molecular mechanisms of allergic conjunctivitis. Recent research advancing therapy for allergic conjunctivitis has focused on developing synthetic molecules and biologics that can interfere with the process of the allergic immune reaction.

SUMMARY

This review discusses novel therapeutic receptors being explored agonistically or antagonistically to develop alternative treatment options for allergic conjunctivitis. These novel approaches hold promise for improving the management of allergic eye diseases, offering patients hope for more effective and safer treatment options in the future.

PL3 CendR peptide shows specific uptake in cultured Y79 retinoblastoma cells with nucleolar accumulation

Retinoblastoma is the most common pediatric intraocular malignant tumor affecting 1:15 000-1:20 000 live births. Even though the survival rate in developed countries is over 90 %, more efficient treatment options are needed for better vision salvage and reduction of the adverse effects. Therefore, we investigated fluorescein-labeled PL3 peptide targeting properties towards the Y79 retinoblastoma cell line in vitro. Through the application of cellular imaging and flow cytometry techniques, the PL3 peptide exhibited a rapid and specific internalization within Y79 cells, with subsequent translocation to the cell nuclei, showcasing notable accumulation in the nucleoli. This phenomenon was not present in other investigated cell lines and was not observable with similarly charged and length control peptide. However, the exact mechanism behind this Y79 cell line-specific nuclear and nucleolar targeting pattern remains elusive. In the future, this targeting process could facilitate specific treatment modalities of retinoblastoma with PL3 peptide-coupled drug delivery technologies.

Photoactivated growth factor release from bio-orthogonally crosslinked hydrogels for the regeneration of corneal defects

In situ-forming hydrogels are an attractive option for corneal regeneration, and the delivery of growth factors from such constructs have the potential to improve re-epithelialization and stromal remodeling. However, challenges persist in controlling the release of therapeutic molecules from hydrogels. Here, an in situ-forming bio-orthogonally crosslinked hydrogel containing growth factors tethered via photocleavable linkages (PC-HACol hydrogel) was developed to accelerate corneal regeneration. Epidermal growth factor (EGF) was conjugated to the hydrogel backbone through photo-cleavable (PC) spacer arms and was released when exposed to mild intensity ultraviolet (UV) light (2-5 mW/cm2, 365 nm). The PC-HACol hydrogel rapidly gelled within a few minutes when applied to corneal defects, with excellent transparency and biocompatibility. After subsequent exposure to UV irradiation, the hydrogel promoted the proliferation and migration of corneal epithelial cells in vitro. The rate of re-epithelialization was positively correlated to the frequency of irradiation, verified through ex vivo rabbit cornea organ culture studies. In an in vivo rat corneal wound healing study, the PC-HACol hydrogel exposed to UV light significantly promoted re-epithelialization, the remodeling of stromal layers, and exhibited significant anti-scarring effects, with minimal α-SMA and robust ALDH3A1 expression. Normal differentiation of the regenerated epithelia after healing was evaluated by expression of the corneal epithelial biomarker, CK12. The remodeled cornea exhibited full recovery of corneal thickness and layer number without hyperplasia of the epithelium.

Aryl hydrocarbon receptor (AhR)-mediated immune responses to degeneration of the retinal pigment epithelium

Injuries to the retinal pigment epithelium (RPE) trigger immune responses, orchestrating interactions within the innate and adaptive immune systems in the outer retina and choroid. We previously reported that interleukin 17 (IL-17) is a pivotal signaling molecule originating from choroidal γδ T cells, exerting protective effects by mediating functional connections between the RPE and subretinal microglia. In this current study, we generated mice with aryl hydrocarbon receptor (AhR) knockout specifically in IL-17-producing cells. These animals had deficiency in IL-17 production from γδ T cells, and exhibited increased sensitivity to both acute and chronic insults targeting the RPE. These findings imply that IL-17 plays a crucial role as a signaling cytokine in preserving the homeostasis of the outer retina and choroid.

Approaches based on miRNAs in Behçet's Disease: Unveiling pathogenic mechanisms, diagnostic strategies, and therapeutic applications

Behçet's Disease (BD) is an intricate medical puzzle, captivating researchers with its enigmatic pathogenesis. This complex ailment, distinguished by recurrent mouth and genital lesions, eye irritation, and skin injuries, presents a substantial obstacle to therapeutic research. This review explores the complex interaction of microRNAs (miRNAs) with BD, highlighting their crucial involvement in the disease's pathophysiology. miRNAs, recognized for regulatory influence in diverse biological processes, hold a pivotal position in the molecular mechanisms of autoimmune diseases, such as BD. The exploration begins with examining miRNA biogenic pathways and functions, establishing a foundational understanding of their regulatory mechanisms. Shifting to the molecular landscape governing BD, the review highlights miRNA-mediated impacts on critical signaling pathways like Notch, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and protein kinase B (AKT)/mammalian target of rapamycin (mTOR), offering insights into intricate pathophysiological mechanisms. Dissecting the immunological landscape reveals the profound influence of miRNAs on BD, shedding light on the intricate modulation of immune responses and offering novel perspectives on disease etiology and progression. Beyond molecular intricacies, the review explores the clinical relevance of miRNAs in BD, emphasizing their potential as diagnostic and prognostic indicators. The discussion extends to the promising realm of miRNA-based therapeutic interventions, highlighting their potential in alleviating symptoms and altering disease progression. This comprehensive review, serving as a valuable resource for researchers, clinicians, and stakeholders, aims to decipher the intricate molecular tapestry of BD and explore the therapeutic potential of miRNAs.

Multifunctional nanomaterials for smart wearable diabetic healthcare devices

Wearable diabetic healthcare devices have attracted great attention for real-time continuous glucose monitoring (CGM) using biofluids such as tears, sweat, saliva, and interstitial fluid via noninvasive ways. In response to the escalating global demand for CGM, these devices enable proactive management and intervention of diabetic patients with incorporated drug delivery systems (DDSs). In this context, multifunctional nanomaterials can trigger the development of innovative sensing and management platforms to facilitate real-time selective glucose monitoring with remarkable sensitivity, on-demand drug delivery, and wireless power and data transmission. The seamless integration into wearable devices ensures patient's compliance. This comprehensive review evaluates the multifaceted roles of these materials in wearable diabetic healthcare devices, comparing their glucose sensing capabilities with conventionally available glucometers and CGM devices, and finally outlines the merits, limitations, and prospects of these devices. This review would serve as a valuable resource, elucidating the intricate functions of nanomaterials for the successful development of advanced wearable devices in diabetes management.

Atherosclerotic burden and cerebral small vessel disease: exploring the link through microvascular aging and cerebral microhemorrhages

Cerebral microhemorrhages (CMHs, also known as cerebral microbleeds) are a critical but frequently underestimated aspect of cerebral small vessel disease (CSVD), bearing substantial clinical consequences. Detectable through sensitive neuroimaging techniques, CMHs reveal an extensive pathological landscape. They are prevalent in the aging population, with multiple CMHs often being observed in a given individual. CMHs are closely associated with accelerated cognitive decline and are increasingly recognized as key contributors to the pathogenesis of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD). This review paper delves into the hypothesis that atherosclerosis, a prevalent age-related large vessel disease, extends its pathological influence into the cerebral microcirculation, thereby contributing to the development and progression of CSVD, with a specific focus on CMHs. We explore the concept of vascular aging as a continuum, bridging macrovascular pathologies like atherosclerosis with microvascular abnormalities characteristic of CSVD. We posit that the same risk factors precipitating accelerated aging in large vessels (i.e., atherogenesis), primarily through oxidative stress and inflammatory pathways, similarly instigate accelerated microvascular aging. Accelerated microvascular aging leads to increased microvascular fragility, which in turn predisposes to the formation of CMHs. The presence of hypertension and amyloid pathology further intensifies this process. We comprehensively overview the current body of evidence supporting this interconnected vascular hypothesis. Our review includes an examination of epidemiological data, which provides insights into the prevalence and impact of CMHs in the context of atherosclerosis and CSVD. Furthermore, we explore the shared mechanisms between large vessel aging, atherogenesis, microvascular aging, and CSVD, particularly focusing on how these intertwined processes contribute to the genesis of CMHs. By highlighting the role of vascular aging in the pathophysiology of CMHs, this review seeks to enhance the understanding of CSVD and its links to systemic vascular disorders. Our aim is to provide insights that could inform future therapeutic approaches and research directions in the realm of neurovascular health.

Genetic Risk, Inflammation, and Therapeutics: An Editorial Overview of Recent Advances in Aging Brains and Neurodegeneration

Neurodegenerative disorders, including Dementia, Parkinson's disease, various Vision disorders, Multiple sclerosis, and transsynaptic degenerative changes represent a significant challenge in aging populations. This editorial synthesizes and discusses recent advancements in understanding the genetic and environmental factors contributing to these diseases. Central to these advancements is the role of neuroinflammation and oxidative stress, which exacerbate neuronal damage and accelerate disease progression. Emerging research underscores the significance of mitochondrial dysfunction and protein aggregation in neurodegenerative pathology, highlighting shared mechanisms across various disorders. Innovative therapeutic strategies, including gene therapy, CRISPR-Cas technology, and the use of naturally occurring antioxidant molecules, are being investigated to target and manage these conditions. Additionally, lifestyle interventions such as exercise and healthy diet have shown promise in enhancing brain plasticity and reducing neuroinflammation. Advances in neuroimaging and biomarker discovery are necessary to improve early diagnosis, while clinical and preclinical studies are essential for the translation of these novel treatments. This edition aims to bridge the gap between molecular mechanisms and therapeutic applications, offering insights into potential interventions to mitigate the impact of neurodegenerative diseases. By establishing a deeper understanding of these complex processes, we aim to move closer to effective prevention and treatment strategies, ultimately improving the quality of life for those affected by neurodegenerative disorders.

Lycium barbarum glycopeptide (wolfberry extract) slows N-methyl-N-nitrosourea-induced degradation of photoreceptors

JOURNAL/nrgr/04.03/01300535-202410000-00030/figure1/v/2024-02-06T055622Z/r/image-tiff Photoreceptor cell degeneration leads to blindness, for which there is currently no effective treatment. Our previous studies have shown that Lycium barbarum (L. barbarum) polysaccharide (LBP) protects degenerated photoreceptors in rd1, a transgenic mouse model of retinitis pigmentosa. L. barbarum glycopeptide (LbGP) is an immunoreactive glycoprotein extracted from LBP. In this study, we investigated the potential protective effect of LbGP on a chemically induced photoreceptor-degenerative mouse model. Wild-type mice received the following: oral administration of LbGP as a protective pre-treatment on days 1-7; intraperitoneal administration of 40 mg/kg N-methyl-N-nitrosourea to induce photoreceptor injury on day 7; and continuation of orally administered LbGP on days 8-14. Treatment with LbGP increased photoreceptor survival and improved the structure of photoreceptors, retinal photoresponse, and visual behaviors of mice with photoreceptor degeneration. LbGP was also found to partially inhibit the activation of microglia in N-methyl-N-nitrosourea-injured retinas and significantly decreased the expression of two pro-inflammatory cytokines. In conclusion, LbGP effectively slowed the rate of photoreceptor degeneration in N-methyl-N-nitrosourea-injured mice, possibly through an anti-inflammatory mechanism, and has potential as a candidate drug for the clinical treatment of photoreceptor degeneration.

Glaucoma and the ocular renin-angiotensin-aldosterone system: Update on molecular signalling and treatment perspectives

Glaucoma, a leading cause of blindness worldwide, encompasses a group of pathological conditions affecting the optic nerve and is characterized by progressive retinal ganglion cell loss, cupping of the optic nerve head, and distinct visual field defects. While elevated intraocular pressure (IOP) is the main risk factor for glaucoma, many patients do not have elevated IOP. Consequently, other risk factors, such as ocular blood flow abnormalities and immunological factors, have been implicated in its pathophysiology. Traditional therapeutic strategies primarily aim to reduce IOP, but there is growing interest in developing novel treatment approaches to improve disease management and reduce the high rates of severe visual impairment. In this context, targeting the ocular renin-angiotensin-aldosterone system (RAAS) has been found as a potential curative strategy. The RAAS contributes to glaucoma development through key effectors such as prorenin, angiotensin II, and aldosterone. Recent evidence has highlighted the potential of using RAAS modulators to combat glaucoma, yielding encouraging results. Our study aims to explore the molecular pathways linking the ocular RAAS and glaucoma, summarizing recent advances that elucidate the role of the RAAS in triggering oxidative stress, inflammation, and remodelling in the pathogenesis of glaucoma. Additionally, we will present emerging therapeutic approaches that utilize RAAS modulators and antioxidants to slow the progression of glaucoma.

Light sensitivity in Beroidae ctenophores: Insights from laboratory studies and genomics

Light detection underlies a variety of animal behaviors, including those related to spatial orientation, feeding, avoidance of predators, and reproduction. Ctenophores are likely the oldest animal group in which light sensitivity based on opsins evolved, so they may still have the ancestral molecular mechanisms for photoreception. However, knowledge about ctenophore photosensitivity, associated morphological structures, molecular mechanisms involved, and behavioral reactions is limited and fragmented. We present the initial experiments on the responses of adult Beroe ovata to high-intensity light exposure with different spectra and photosensitivity in various parts of the animal's body. Ctenophores have shown a consistent behavioral response when their aboral organ is exposed to a household-grade laser in the violet spectrum. To investigate the genes responsible for the photosensitivity of Beroidae, we have analyzed transcriptome and genome-wide datasets. We identified three opsins in Beroe that are homologous to those found in Mnemiopsis leidyi (Lobata) and Pleurobrachia bachei (Cydippida). These opsins form clades Ctenopsin1, 2, and 3, respectively. Ctenopsin3 is significantly distinct from other ctenophore opsins and clustered outside the main animal opsin groups. The Ctenopsin1 and Ctenopsin2 groups are sister clusters within the canonical animal opsin tree. These two groups could have originated from gene duplication in the common ancestor of the species we studied and then developed independently in different lineages of Ctenophores. So far, there is no evidence of additional expansion of the opsin family in ctenophore evolution. The involvement of ctenophore opsins in photoreception is discussed by analyzing their protein structures.

Ocular delivery of Pigment Epithelium-Derived Factor (PEDF) as a neuroprotectant for Geographic Atrophy

Geographic atrophy (GA) is an advanced form of age-related macular degeneration (AMD), that starts with atrophic lesions in the outer retina that expand to cover the macula and fovea, leading to severe vision loss over time. Pigment Epithelium-Derived Factor (PEDF) has a diverse-range of properties, including its ability to promote cell survival, reduce inflammation, inhibit angiogenesis, combat oxidative stress, regulate autophagy, and stimulate anti-apoptotic pathways, making it a promising therapeutic candidate for GA. However, the relatively short half-life of PEDF protein has precluded its potential as a clinical therapy for GA since it would require frequent injections. Therefore, we describe administration of a PEDF gene, comparing and contrasting delivery routes, viral and non-viral vectors, and consider the critical challenges for PEDF as a neuroprotectant for GA.

Global trends in diabetic eye disease research from 2012 to 2021

JOURNAL/nrgr/04.03/01300535-202410000-00032/figure1/v/2024-02-06T055622Z/r/image-tiff Diabetic eye disease refers to a group of eye complications that occur in diabetic patients and include diabetic retinopathy, diabetic macular edema, diabetic cataracts, and diabetic glaucoma. However, the global epidemiology of these conditions has not been well characterized. In this study, we collected information on diabetic eye disease-related research grants from seven representative countries--the United States, China, Japan, the United Kingdom, Spain, Germany, and France--by searching for all global diabetic eye disease journal articles in the Web of Science and PubMed databases, all global registered clinical trials in the ClinicalTrials database, and new drugs approved by the United States, China, Japan, and EU agencies from 2012 to 2021. During this time period, diabetic retinopathy accounted for the vast majority (89.53%) of the 2288 government research grants that were funded to investigate diabetic eye disease, followed by diabetic macular edema (9.27%). The United States granted the most research funding for diabetic eye disease out of the seven countries assessed. The research objectives of grants focusing on diabetic retinopathy and diabetic macular edema differed by country. Additionally, the United States was dominant in terms of research output, publishing 17.53% of global papers about diabetic eye disease and receiving 22.58% of total citations. The United States and the United Kingdom led international collaborations in research into diabetic eye disease. Of the 415 clinical trials that we identified, diabetic macular edema was the major disease that was targeted for drug development (58.19%). Approximately half of the trials (49.13%) pertained to angiogenesis. However, few drugs were approved for ophthalmic (40 out of 1830; 2.19%) and diabetic eye disease (3 out of 1830; 0.02%) applications. Our findings show that basic and translational research related to diabetic eye disease in the past decade has not been highly active, and has yielded few new treatment methods and newly approved drugs.

Truncation mutations of CRYGD gene in congenital cataracts cause protein aggregation by disrupting the structural stability of γD-crystallin

Congenital cataracts, a prevalent cause of blindness in children, are associated with protein aggregation. γD-crystallin, essential for sustaining lens transparency, exists as a monomer and exhibits excellent structural stability. In our cohort, we identified a nonsense mutation (c.451_452insGACT, p.Y151X) in the CRYGD gene. To explore the effect of truncation mutations on the structure of γD-crystallin, we examined the Y151X and T160RfsX8 mutations, both located in the Greek key motif 4 at the cellular and protein level in this study. Both truncation mutations induced protein misfolding and resulted in the formation of insoluble aggregates when overexpressed in HLE B3 and HEK 293T cells. Moreover, heat, UV irradiation, and oxidative stress increased the proportion of aggregates of mutants in the cells. We next purified γD-crystallin to estimate its structural changes. Truncation mutations led to conformational disruption and a concomitant decrease in protein solubility. Molecular dynamics simulations further demonstrated that partial deletion of the conserved domain within the Greek key motif 4 markedly compromised the overall stability of the protein structure. Finally, co-expression of α-crystallins facilitated the proper folding of truncated mutants and mitigated protein aggregation. In summary, the structural integrity of the Greek key motif 4 in γD-crystallin is crucial for overall structural stability.