RNA sequencing reveals BMP4 as a basis for the dual-target treatment of diabetic retinopathy

The gut-eye axis: the retinal/ocular degenerative diseases and the emergent therapeutic strategies

The interplay between human microbiota and various physiological systems has garnered significant attention in recent years. The gut microbiota plays a critical role in maintaining physiological homeostasis and influences various aspects of human health, particularly via the gut brain axis. Since 2017, the challenging concept of the gut-retina axis has emerged thanks to a network analysis emphasizing the potential role of the gut microbiota disruption in the development of the age-related macular degeneration and further retinal damages. Many other ocular disorders have been linked to the dysbiosis of the gut microbiota, including uveitis and glaucoma. It has been shown that age related macular degeneration can be prevented or reversed using a diet that induces changes in the gut microbiota. The potential link between the gut microbiota as well as others types of microbiota such as the ocular surface microbiota and the development/progression of age related as well as inherited retinal degenerations and other degenerative eye diseases, has recently been broadened. Therefore, the pathogenesis of several eye diseases has recently been associated with a larger perception called the gut eye axis. This mini-review examines the potential mechanisms underlying the gut eye axis and suggests implications for the management of eye diseases. By understanding the modulation of the gut microbiota and its impact on eye disease, this mini-review provides insight into potential therapeutic interventions and avenues for future research.

Microvascular destabilization and intricated network of the cytokines in diabetic retinopathy: from the perspective of cellular and molecular components

Microvascular destabilization is the primary cause of the inner blood-retinal barrier (iBRB) breakdown and increased vascular leakage in diabetic retinopathy (DR). Microvascular destabilization results from the combinational effects of increased levels of growth factors and cytokines, involvement of inflammation, and the changed cell-to-cell interactions, especially the loss of endothelial cells and pericytes, due to hyperglycemia and hypoxia. As the manifestation of microvascular destabilization, the fluid transports via paracellular and transcellular routes increase due to the disruption of endothelial intercellular junctional complexes and/or the altered caveolar transcellular transport across the retinal vascular endothelium. With diabetes progression, the functional and the structural changes of the iBRB components, including the cellular and noncellular components, further facilitate and aggravate microvascular destabilization, resulting in macular edema, the neuroretinal damage and the dysfunction of retinal inner neurovascular unit (iNVU). Although there have been considerable recent advances towards a better understanding of the complex cellular and molecular network underlying the microvascular destabilization, some still remain to be fully elucidated. Recent data indicate that targeting the intricate signaling pathways may allow to against the microvascular destabilization. Therefore, efforts have been made to better clarify the cellular and molecular mechanisms that are involved in the microvascular destabilization in DR. In this review, we discuss: (1) the brief introduction of DR and microvascular destabilization; (2) the cellular and molecular components of iBRB and iNVU, and the breakdown of iBRB; (3) the matrix and cell-to-cell contacts to maintain microvascular stabilization, including the endothelial glycocalyx, basement membrane, and various cell-cell interactions; (4) the molecular mechanisms mediated cell-cell contacts and vascular cell death; (5) the altered cytokines and signaling pathways as well as the intricate network of the cytokines involved in microvascular destabilization. This comprehensive review aimed to provide the insights for microvascular destabilization by targeting the key molecules or specific iBRB cells, thus restoring the function and structure of iBRB and iNVU, to treat DR.

A Nucleic Acid-Based LYTAC Plus Platform to Simultaneously Mediate Disease-Driven Protein Downregulation

Protein degradation techniques, such as proteolysis-targeting chimeras (PROTACs) and lysosome-targeting chimeras (LYTACs), have emerged as promising therapeutic strategies for the treatment of diseases. However, the efficacy of current protein degradation methods still needs to be improved to address the complex mechanisms underlying diseases. Herein, a LYTAC Plus hydrogel engineered is proposed by nucleic acid self-assembly, which integrates a gene silencing motif into a LYTAC construct to enhance its therapeutic potential. As a proof-of-concept study, vascular endothelial growth factor receptor (VEGFR)-binding peptides and mannose-6 phosphate (M6P) moieties into a self-assembled nucleic acid hydrogel are introduced, enabling its LYTAC capability. Small interference RNAs (siRNAs) is then employed that target the angiopoietin-2 (ANG-2) gene as cross-linkers for hydrogel formation, giving the final LYTAC Plus hydrogel gene silencing ability. With dual functionalities, the LYTAC Plus hydrogel demonstrated effectiveness in simultaneously reducing the levels of VEGFR-2 and ANG-2 both in vitro and in vivo, as well as in improving therapeutic outcomes in treating neovascular age-related macular degeneration in a mouse model. As a general material platform, the LYTAC Plus hydrogel may possess great potential for the treatment of various diseases and warrant further investigation.

Effects of a fortified balanced salt solution and Ringer's lactate solution on anterior chamber inflammation after phacoemulsification in diabetes

PURPOSE

To compare the effects of a fortified balanced salt solution (fSS) and Ringer's lactate solution (Ringer) on anterior chamber (AC) inflammation in patients undergoing phacoemulsification.

SETTING

Tianjin Medical University Eye Hospital, Tianjin, China.

DESIGN

Prospective masked controlled trial.

METHODS

80 patients (40 patients with regular cataract and 40 cataract patients with diabetes mellitus [DM]) were randomized to receive either fSS (n = 40) or Ringer's solution (n = 40). Anterior-segment optical coherence tomography was used to evaluate AC cells and flare. Transepithelial electrical resistance (TEER) and zonula occludens-1 (ZO-1) immunofluorescence were used for tight junction examination. Monocytic leukemia cell line (Tohoku Hospital Pediatrics-1 [THP-1]) transmigration assay was performed to observe the effects of the 2 perfusates on the inflammatory response in vitro.

RESULTS

In patients with regular cataracts, postoperative AC cells and flare on the 1st and 7th days were not significantly different between the Ringer and fSS groups. However, in cataract patients with DM, AC cells were higher in the Ringer group than in the fSS group ( P = .003) on postoperative day 1. The AC flare was also significantly higher in the Ringer group than in the fSS group ( P < .0001). No significant differences between the groups were observed on day 7. Compared with Ringer, fSS increased the TEER value and ZO-1 content and reduced the adhesion of THP-1 cells.

CONCLUSIONS

The results of this study indicated that early postoperative AC inflammation is more severe in patients with cataracts and DM. In addition, fSS attenuates inflammation by protecting the blood-aqueous barrier and inhibiting the exudation of inflammatory cells.

Single-cell RNA-seq and bulk-seq identify RAB17 as a potential regulator of angiogenesis by human dermal microvascular endothelial cells in diabetic foot ulcers

Background

Angiogenesis is crucial in diabetic wound healing and is often impaired in diabetic foot ulcers (DFUs). Human dermal microvascular endothelial cells (HDMECs) are vital components in dermal angiogenesis; however, their functional and transcriptomic characteristics in DFU patients are not well understood. This study aimed to comprehensively analyse HDMECs from DFU patients and healthy controls and find the potential regulator of angiogenesis in DFUs.

Methods

HDMECs were isolated from skin specimens of DFU patients and healthy controls via magnetic-activated cell sorting. The proliferation, migration and tube-formation abilities of the cells were then compared between the experimental groups. Both bulk RNA sequencing (bulk-seq) and single-cell RNA-seq (scRNA-seq) were used to identify RAB17 as a potential marker of angiogenesis, which was further confirmed via weighted gene co-expression network analysis (WGCNA) and least absolute shrink and selection operator (LASSO) regression. The role of RAB17 in angiogenesis was examined through in vitro and in vivo experiments.

Results

The isolated HDMECs displayed typical markers of endothelial cells. HDMECs isolated from DFU patients showed considerably impaired tube formation, rather than proliferation or migration, compared to those from healthy controls. Gene set enrichment analysis (GSEA), fGSEA, and gene set variation analysis (GSVA) of bulk-seq and scRNA-seq indicated that angiogenesis was downregulated in DFU-HDMECs. LASSO regression identified two genes, RAB17 and CD200, as characteristic of DFU-HDMECs; additionally, the expression of RAB17 was found to be significantly reduced in DFU-HDMECs compared to that in the HDMECs of healthy controls. Overexpression of RAB17 was found to enhance angiogenesis, the expression of hypoxia inducible factor-1α and vascular endothelial growth factor A, and diabetic wound healing, partially through the mitogen-activated protein kinase/extracellular signal-regulated kinase signalling pathway.

Conclusions

Our findings suggest that the impaired angiogenic capacity in DFUs may be related to the dysregulated expression of RAB17 in HDMECs. The identification of RAB17 as a potential molecular target provides a potential avenue for the treatment of impaired angiogenesis in DFUs.

The gut-retina axis: a new perspective in the prevention and treatment of diabetic retinopathy

Diabetic retinopathy (DR) is a microvascular lesion that occurs as a complication of diabetes mellitus. Many studies reveal that retinal neurodegeneration occurs early in its pathogenesis, and abnormal retinal function can occur in patients without any signs of microvascular abnormalities. The gut microbiota is a large, diverse colony of microorganisms that colonize the human intestine. Studies indicated that the gut microbiota is involved in the pathophysiological processes of DR and plays an important role in its development. On the one hand, numerous studies demonstrated the involvement of gut microbiota in retinal neurodegeneration. On the other hand, alterations in gut bacteria in RD patients can cause or exacerbate DR. The present review aims to underline the critical relationship between gut microbiota and DR. After a brief overview of the composition, function, and essential role of the gut microbiota in ocular health, and the review explores the concept of the gut-retina axis and the conditions of the gut-retina axis crosstalk. Because gut dysbiosis has been associated with DR, the review intends to determine changes in the gut microbiome in DR, the hypothesized mechanisms linking to the gut-retina axis, and its predictive potential.

Bone Morphogenetic Protein-4 Impairs Retinal Endothelial Cell Barrier, a Potential Role in Diabetic Retinopathy

Bone Morphogenetic Protein 4 (BMP4) is a secreted growth factor of the Transforming Growth Factor beta (TGFβ) superfamily. The goal of this study was to test whether BMP4 contributes to the pathogenesis of diabetic retinopathy (DR). Immunofluorescence of BMP4 and the vascular marker isolectin-B4 was conducted on retinal sections of diabetic and non-diabetic human and experimental mice. We used Akita mice as a model for type-1 diabetes. Proteins were extracted from the retina of postmortem human eyes and 6-month diabetic Akita mice and age-matched control. BMP4 levels were measured by Western blot (WB). Human retinal endothelial cells (HRECs) were used as an in vitro model. HRECs were treated with BMP4 (50 ng/mL) for 48 h. The levels of phospho-smad 1/5/9 and phospho-p38 were measured by WB. BMP4-treated and control HRECs were also immunostained with anti-Zo-1. We also used electric cell-substrate impedance sensing (ECIS) to calculate the transcellular electrical resistance (TER) under BMP4 treatment in the presence and absence of noggin (200 ng/mL), LDN193189 (200 nM), LDN212854 (200 nM) or inhibitors of vascular endothelial growth factor receptor 2 (VEGFR2; SU5416, 10 μM), p38 (SB202190, 10 μM), ERK (U0126, 10 μM) and ER stress (Phenylbutyric acid or PBA, 30 μmol/L). The impact of BMP4 on matrix metalloproteinases (MMP2 and MMP9) was also evaluated using specific ELISA kits. Immunofluorescence of human and mouse eyes showed increased BMP4 immunoreactivity, mainly localized in the retinal vessels of diabetic humans and mice compared to the control. Western blots of retinal proteins showed a significant increase in BMP4 expression in diabetic humans and mice compared to the control groups (p < 0.05). HRECs treated with BMP4 showed a marked increase in phospho-smad 1/5/9 (p = 0.039) and phospho-p38 (p = 0.013). Immunofluorescence of Zo-1 showed that BMP4-treated cells exhibited significant barrier disruption. ECIS also showed a marked decrease in TER of HRECs by BMP4 treatment compared to vehicle-treated HRECs (p < 0.001). Noggin, LDN193189, LDN212854, and inhibitors of p38 and VEGFR2 significantly mitigated the effects of BMP4 on the TER of HRECs. Our finding provides important insights regarding the role of BMP4 as a potential player in retinal endothelial cell dysfunction in diabetic retinopathy and could be a novel target to preserve the blood-retinal barrier during diabetes.

BMP4 aggravates mitochondrial dysfunction of HRMECs

Mitochondria are important places for the oxidative phosphorylation of glucose and the maintenance of cell oxidation and antioxidant stability. However, mitochondrial dysfunction causes cell dysfunction. Meanwhile, retinal vascular endothelial cell dysfunction may cause vascular inflammation, hemorrhage, angiogenesis, and other manifestations. Our previous studies have shown that Bone morphogenetic protein 4 (BMP4) is an important target for the treatment of retinal neovascularization, but the mechanism remains unclear. Therefore, our study aims to observe the effects of BMP4 on vascular endothelial cells and hopes to provide a new target for diabetic retinopathy. 4-Hydroxynonenal (4HNE), a kind of lipid peroxide, was used to induce the oxidative stress model. Human retinal microvascular endothelial cells (HRMECs) were randomly divided into control, 4HNE, negative control, and siBMP4 groups. Si-BMP4 significantly reduced leukocyte adhesion and 4HNE-induced high ROS level and restored the mitochondrial membrane potential and OCR. This indicates that BMP4 plays an important role in inducing leukocyte adhesion, oxidative stress, and mitochondrial dysfunction. The relationship between BMP4 and retinal vascular endothelial cell dysfunction is preliminarily confirmed by this study. Mitochondrial dysfunction and oxidative stress may be involved in BMP4-mediated retinal vascular endothelial cell dysfunction.

Low expression of RBP4 in the vitreous humour of patients with proliferative diabetic retinopathy who underwent Conbercept intravitreal injection

Intravitreal injection of anti-VEGF antibodies has been widely used in the treatment of proliferative diabetic retinopathy (PDR). However, anti-VEGF drugs can exacerbate fibrosis and eventually lead to retinal detachment. To explore proteins closely related to fibrosis, we conducted proteomic analysis of human vitreous humour collected from PDR patients who have or have not intravitreal Conbercept (IVC) injection. Sixteen vitreous humour samples from PDR patients with preoperative IVC and 20 samples from those without preoperative IVC were examined. An immunodepletion kit was used to remove high-abundance vitreous proteins. Conbercept-induced changes were determined using a tandem mass tag-based quantitative proteomic strategy. Enzyme-linked immunosorbent assays were performed to confirm the concentrations of selected proteins and validate the proteomic results. Based on a false discovery rate between 0.05% and -0.05% and a fold-change > 1.5, 97 proteins were altered (49 higher levels and 48 lower levels) in response to IVC. Differentially expressed proteins were found in the extracellular and intracellular regions and were found to be involved in VEGF binding and VEGF-activated receptor activity. Protein-protein interactions indicated associations with fibrosis, neovascularisation and inflammatory signalling pathways. We found the low levels of RBP4 in the vitreous humour of PDR patients with IVC injection, as revealed by ELISA and proteomic profiling. Moreover, RBP4 significantly restored the mitochondrial function of HRMECs induced by AGEs and down regulated the level of glycolysis. Our study is the first to report that RBP4 decreases in the vitreous humour of PDR patients who underwent Conbercept treatment, thereby verifying the role of RBP4 in glucose metabolism. Results provide evidence for the potential mechanism underlying Conbercept-related fibrosis.

Suppression of EZH2 inhibits TGF-β1-induced EMT in human retinal pigment epithelial cells

Epithelial-mesenchymal transition (EMT) of retinal pigment epithelium (RPE) cells is critically involved in the occurrence of subretinal fibrosis. This study aimed to investigate the role of enhancer of zeste homolog 2 (EZH2) in EMT of human primary RPE cells and the underlying mechanisms of the anti-fibrotic effect of EZH2 suppression. Primary cultures of human RPE cells were treated with TGF-β1 for EMT induction. EZH2 was silenced by siRNA to assess the expression levels of epithelial and fibrotic markers using qRT-PCR, western blot, and immunofluorescence staining assay. Furthermore, the cellular migration, proliferation and barrier function of RPE cells were evaluated. RNA-sequencing analyses were performed to investigate the underlying mechanisms of EZH2 inhibition. Herein, EZH2 silencing up-regulated epithelial marker ZO-1 and downregulated fibrotic ones including α-SMA, fibronectin, and collagen 1, alleviating EMT induced by TGF-β1 in RPE cells. Moreover, silencing EZH2 inhibited cellular migration and proliferation, but didn't affect cell apoptosis. Additionally, EZH2 suppression contributed to improved barrier functions after TGF-β1 stimulation. The results from RNA sequencing suggested that the anti-fibrotic effect of EZH2 inhibition was associated with the MAPK signaling pathway, cytokine-cytokine receptor interaction, and the TGF-beta signaling pathway. Our findings provide evidence that the suppression of EZH2 might reverse EMT and maintain the functions of RPE cells. EZH2 could be a potential therapeutic avenue for subretinal fibrosis.

Application Progress of High-Throughput Sequencing in Ocular Diseases

Ocular diseases affect multiple eye parts and can be caused by pathogenic infections, complications of systemic diseases, genetics, environment, and old age. Understanding the etiology and pathogenesis of eye diseases and improving their diagnosis and treatment are critical for preventing any adverse consequences of these diseases. Recently, the advancement of high-throughput sequencing (HTS) technology has paved wide prospects for identifying the pathogenesis, signaling pathways, and biomarkers involved in eye diseases. Due to the advantages of HTS in nucleic acid sequence recognition, HTS has not only identified several normal ocular surface microorganisms but has also discovered many pathogenic bacteria, fungi, parasites, and viruses associated with eye diseases, including rare pathogens that were previously difficult to identify. At present, HTS can directly sequence RNA, which will promote research on the occurrence, development, and underlying mechanism of eye diseases. Although HTS has certain limitations, including low effectiveness, contamination, and high cost, it is still superior to traditional diagnostic methods for its efficient and comprehensive diagnosis of ocular diseases. This review summarizes the progress of the application of HTS in ocular diseases, intending to explore the pathogenesis of eye diseases and improve their diagnosis.

Senescence marker protein30 protects lens epithelial cells against oxidative damage by restoring mitochondrial function

Etiology and pathogenesis of age-related cataract is not entirely clear till now. Senescence marker protein 30 (SMP30) is a newly discovered anti-aging factor, which plays an important role in preventing apoptosis and reducing oxidative stress damage. Mitochondria are located at the intersection of key cellular pathways, such as energy substrate metabolism, reactive oxygen species (ROS) production and apoptosis. Oxidative stress induced by 4-hydroxynonenal (4-HNE) is closely related to neurodegenerative diseases and aging. Our study focused on the effect of SMP30 on mitochondrial homeostasis of human lens epithelial cells (HLECs) induced by 4-HNE. Western blots and qPCR were used to compare the expression of SMP30 protein in the residual lens epithelial cells in the lens capsule of age-related cataract (ARC) patients and the donated transparent lens capsule. On this basis, SMP30 overexpression plasmid and SMP30 shRNA interference plasmid were introduced to explore the effect of SMP30 on the biological behavior in HLECs under the condition of oxidative stress induced by 4-HNE through immunohistochemistry, ROS evaluation, metabolic spectrum analysis and JC-1 fluorescence measurement. Given that Nuclear Factor erythroid 2-Related Factor 2 (Nrf2)/Kelch Like ECH Associated Protein 1 (KEAP1) signaling pathway is the most important antioxidant stress pathway, we further analyzed the regulatory effect of SMP30 by WB to explore its molecular mechanism. Our study indicated that SMP30 may inhibit ROS accumulation, restore mitochondrial function, activate Nrf2/Keap1 signaling pathway, therefore protecting lens epithelial cells from oxidative stress-induced cell damage.

An integrated RNA sequencing and network pharmacology approach reveals the molecular mechanism of dapagliflozin in the treatment of diabetic nephropathy

Dapagliflozin, an inhibitor of sodium-glucose cotransporter 2 (SGLT2), is a new type of oral hypoglycemic drugs which can promote glucose excretion in the kidney. Studies have shown that dapagliflozin has renoprotective effect in the treatment of type 2 diabetes. However, the underlying mechanism remains unclear. Here, we combined integrated RNA sequencing and network pharmacology approach to investigate the molecular mechanism of dapagliflozin for diabetic nephropathy (DN). Dapagliflozin significantly relieved glucose intolerance, urinary albumin/creatinine ratio (UACR) and renal pathological injuries of db/db mice. The LncRNA and mRNA expression in kidney tissues from control group (CR), db/db group (DN) and dapagliflozin group (DG) were assessed by RNA sequencing. We identified 7 LncRNAs and 64 mRNAs common differentially expressed in CR vs DN and DN vs DG, which were used to construct co-expression network to reveal significantly correlated expression patterns in DN. In addition, network pharmacology was used to predict the therapeutic targets of dapagliflozin and we constructed component-target-pathway network according to the results of RNA sequencing and network pharmacology. We found that SMAD9, PPARG, CD36, CYP4A12A, CYP4A12B, CASP3, H2-DMB2, MAPK1, MAPK3, C3 and IL-10 might be the pivotal targets of dapagliflozin for treating DN and these genes were mainly enriched in pathways including TGF-β signaling pathway, PPAR signaling pathway, Chemokine signaling pathway, etc. Our results have important implication and provide novel insights into the protective mechanism of dapagliflozin for treating DN.

Systems biology of angiogenesis signaling: Computational models and omics

Angiogenesis is a highly regulated multiscale process that involves a plethora of cells, their cellular signal transduction, activation, proliferation, differentiation, as well as their intercellular communication. The coordinated execution and integration of such complex signaling programs is critical for physiological angiogenesis to take place in normal growth, development, exercise, and wound healing, while its dysregulation is critically linked to many major human diseases such as cancer, cardiovascular diseases, and ocular disorders; it is also crucial in regenerative medicine. Although huge efforts have been devoted to drug development for these diseases by investigation of angiogenesis‐targeted therapies, only a few therapeutics and targets have proved effective in humans due to the innate multiscale complexity and nonlinearity in the process of angiogenic signaling. As a promising approach that can help better address this challenge, systems biology modeling allows the integration of knowledge across studies and scales and provides a powerful means to mechanistically elucidate and connect the individual molecular and cellular signaling components that function in concert to regulate angiogenesis. In this review, we summarize and discuss how systems biology modeling studies, at the pathway‐, cell‐, tissue‐, and whole body‐levels, have advanced our understanding of signaling in angiogenesis and thereby delivered new translational insights for human diseases.

This article is categorized under:

Cardiovascular Diseases > Computational Models

Cancer > Computational Models

Antioxidative effects of polypyrimidine tract-binding protein-associated splicing factor against pathological retinal angiogenesis through promotion of mitochondrial function

Reactive oxygen species (ROS), a by-product of oxygen metabolism mainly originating from mitochondria, participate in many pathological processes related to ophthalmopathy. Excessive production of ROS leads to oxidative stress, which influences the permeability, proliferation, migration, and tube formation of human retinal microcapillary endothelial cells (HRMECs). The molecular mechanisms underlying the effects of ROS are not clear. In Vldlr-/- mice, we used fundus fluorescein angiography and retinal flat mount staining to observe the effect of polypyrimidine tract-binding protein-associated splicing factor (PSF) on pathological retinal neovascularization in vivo. Additionally, in human retinal microvascular endothelial cells treated with 4-HNE, cell viability, tube formation, wound healing, and Transwell assays were performed to study the effect of PSF on the proliferation, migration, and tube formation of retinal vascular endothelial cells in vitro. Moreover, reactive oxygen species assay, real-time PCR, and Western blot were included to analyze the potential mechanism of PSF in the above series of effects. PSF ameliorated intraretinal neovascularization (IRNV) in vivo in Vldlr-/- mice. Under 4-hydroxynonenal (4-HNE) conditions in vitro, PSF reprogrammed mitochondrial bioenergetic and glycolytic profiles. It also reduced ROS levels and inhibited 4-HNE-induced angiogenesis, which involves the proliferation, migration, and tube formation of HRMECs. These results suggest that PSF participates in the regulation of HRMECs proliferation and migration during the development of pathological angiogenesis. We demonstrated that PSF enhanced Nrf2 activation and heme oxygenase-1 (HO-1) expression via extracellular signal-regulated kinase (ERK) and Akt signaling in HRMECs, which subsequently resulted in intracellular ROS scavenging. PSF restored endoplasmic reticulum (ER) redox homeostasis, which was indicated by an increase in protein disulfide isomerase (PDI) and Ero-1α and a reduction in GRP78 and C/EBP homologous protein (CHOP). PSF also attenuated ER stress via regulation of the protein kinase R (PKR)-like endoplasmic reticulum kinase PERK/eukaryotic translation factor 2 alpha (eIF2α)/activating transcription factor 4 (ATF4) pathway in 4-HNE-treated HRMECs. Our research shows that PSF may be a potential antioxidant that regulates pathological angiogenesis through ERK-AKT/Nrf2/HO-1 and PERK/eIF2α/ATF4 signal regulation. KEY MESSAGES: Reactive oxygen species (ROS) mainly originating from mitochondria is a by-product of oxygen metabolism in the body and participates in the pathological process related to multiple blindness-related ophthalmopathy. Moreover , excessive production of ROS will lead to oxidative stress. Consequently, oxidative stress influences the permeability, proliferation, migration, and tube formation of human retinal microcapillary endothelial cells (HRMECs). The molecular mechanisms underlying the effects of ROS remain unclear. Here, we reveal that Polypyrimidine tract-binding protein-associated splicing factor (PSF) ameliorates intraretinal neovascularization (IRNV) in vivo in Vldlr-/- mice. Furthermore, under 4-HNE conditions in vitro, PSF reprograms mitochondrial bioenergetic and glycolytic profiles, reduces ROS levels, and inhibits 4-HNE-induced angiogenesis, which involves the proliferation, migration, and tube formation of HRMECs, suggesting that it participates in regulating the proliferation and migration of HRMECs during the development of pathological angiogenesis. Furthermore, PSF enhances Nrf2 activation and HO-1 expression through ERK and AKT signaling in HRMECs, resulting in intracellular ROS scavenging. PSF restores endoplasmic reticulum (ER) redox homeostasis, as indicated by an increase in PDI and Ero-1α and a reduction in GRP78 and CHOP. PSF also attenuates ER stress by regulating the PERK/eIF2α/ATF4 pathway in 4-HNE-treated HRMECs.

Follistatin-like protein 1 functions as a potential target of gene therapy in proliferative diabetic retinopathy

The degree of retinal fibrosis increased in proliferative diabetic retinopathy (PDR) patients after administration of anti-Vascular endothelial growth factor (VEGF) injections. Previous studies showed that the balance between connective tissue growth factor (CTGF) and VEGF plays an important role. Therefore, in a high-glucose state, an anti-VEGF and CTGFshRNA dual-target model was used to simulate clinical dual-target treatment in PDR patients, and RNA sequencing (RNA-Seq) technology was used for whole transcriptome sequencing. A hypoxia model was constructed to verify the sequencing results at the cellular level, and the vitreous humor and proliferative membranes were collected from patients for verification. All sequencing results included Follistatin-like protein 1 (FSTL1) and extracellular matrix (ECM) receptor pathway, indicated that anti-VEGF therapy may upregulate FSTL1 expression, while dual-target treatment downregulated FSTL1. Thus, we further studied the function of FSTL1 on the expression of VEGF and ECM factors by both overexpressing and silencing FSTL1. In conclusion, our results suggested that FSTL1 may be involved in the pathogenesis of PDR and is related to fibrosis caused by the anti-VEGF treatment, thus providing a potential target for gene therapy in PDR.

Low expression of GSTP1 in the aqueous humour of patients with primary open-angle glaucoma

Primary open‐angle glaucoma (POAG) is characterized by irreversible neurodegeneration accompanied by visual field defects and high intraocular pressure. Currently, an effective treatment is not available to prevent the progression of POAG, other than treatments to decrease the high intraocular pressure. We performed proteomic analysis of aqueous humour (AH) samples from patients with POAG combined with cataract and patients with cataract to obtain a better understanding of the pathogenesis of POAG and explore potential treatment targets for this condition. Samples were collected from 10 patients with POAG combined with cataract and 10 patients with cataract. Samples from each group were pooled. A high‐resolution, label‐free, liquid chromatography‐tandem mass spectrometry‐based quantitative proteomic analysis was performed. In total, 610 proteins were identified in human AH samples from the two groups. A total of 48 up‐regulated proteins and 49 down‐regulated proteins were identified in the POAG combined with cataract group compared with the control group. Gene Ontology (GO) analysis revealed key roles for these proteins in inflammation, immune responses, growth and development, cellular movement and vesicle‐mediated transport in the biological process category. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated the down‐regulated expression of glutathione S‐transferase P (GSTP1) in the glutathione metabolism signalling pathway in the POAG combined with cataract group. Additionally, certain significantly differentially expressed proteins in the proteomic profile were verified by enzyme‐linked immunosorbent assay (ELISA). GSTP1 levels were reduced in the human AH samples from the POAG combined with cataract group, based on the results of ELISA and proteomic profiling. Therefore, GSTP1, a redox‐related marker, may be involved in the pathological process of POAG and may become a treatment target in the future.

Protective Effect and Mechanism of Bone Morphogenetic Protein-4 on Apoptosis of Human Lens Epithelium Cells under Oxidative Stress

Bone morphogenetic proteins (BMPs), a member of the transforming growth factor β (TGF-β) superfamily, are abundant in human ocular tissues and play an important role in lens development. Targeted deletion of BMP-4 in mice results in failure of lens placode formation. Following lens maturation, the formation of senile cataracts is demonstrably associated with free radical-related oxidative stress. Previous studies reported that BMPs play an antiapoptotic role in cells under oxidative stress, and the BMP-4 signal is important in inflammation regulation and homeostasis. BMP-4 evidently suppressed the apoptosis of human lens epithelial cells (HLECS) under oxidative stress induced by H₂O₂. This protective antiapoptotic effect is partly due to a decrease in caspase-3 activity and reactive oxygen species (ROS) level. Furthermore, the expression of activating transcription factor- (ATF-) 6 and Krüppel-like factor- (KLF-) 6 increased under oxidative stress and decreased after BMP-4 treatment.