TPTEP1 suppresses high glucose-induced dysfunction in retinal vascular endothelial cells by interacting with STAT3 and targeting VEGFA

Effect of ranibizumab on diabetic retinopathy via the vascular endothelial growth factor/STAT3/glial fibrillary acidic protein pathway

BACKGROUND

Diabetic retinopathy (DR) is the leading cause of vision loss in patients with diabetes. The vascular endothelial growth factor (VEGF) pathway plays a critical role in the pathogenesis of DR, and ranibizumab, an anti-VEGF agent, has shown promise in its treatment. Signal transducer and activator of transcription 3 (STAT3) is involved in inflammatory processes and cellular signaling, while glial fibrillary acidic protein (GFAP) is a marker of glial cell activation, both contributing to retinal damage in DR. However, the mechanisms by which ranibizumab affect early-stage DR through the VEGF/STAT3/GFAP pathway are not fully understood.

AIM

To investigate the role of ranibizumab in early DR via the VEGF/STAT3/GFAP pathway.

METHODS

Adult retinal pigment epithelial 19 (ARPE-19) cells and human retinal microvascular endothelial cells (HRMECs) were cultured under high-glucose conditions to simulate a diabetic environment. The effects of ranibizumab on cytokine mRNA and protein expression were analyzed by quantitative polymerase chain reaction and Western blot analysis. A diabetic rat model was induced with streptozotocin (60 mg/kg). Retinal changes, including retinal ganglion cell (RGC) apoptosis, vascular alterations, and cytokine expression, were evaluated using fundus fluorescein angiography, hematoxylin and eosin and periodic acid Schiff staining, immunofluorescence, confocal imaging, and Western blot analysis.

RESULTS

High-glucose conditions significantly increased the mRNA and protein levels of VEGF, STAT3, GFAP, and other cytokines in ARPE-19 and HRMECs. However, these levels were partially suppressed by ranibizumab. RGC apoptosis, vascular leakage, and elevated cytokine expression were observed during early-stage DR in diabetic rats. Ranibizumab treatment in diabetic rats reduced cytokine expression, restored RGCs, and repaired vascular networks.

CONCLUSION

Intravitreal ranibizumab modulates the VEGF/STAT3/GFAP pathway, suppresses cytokine expression, and promotes retinal repair, effectively delaying or preventing early DR progression.

Roles of noncoding RNAs in diabetic retinopathy: Mechanisms and therapeutic implications

Diabetic retinopathy (DR) is a microvascular complication of diabetes that leads to vision loss. The striking features of DR are hard exudate, cotton-wool spots, hemorrhage, and neovascularization. The dysregulated retinal cells, encompassing microvascular endothelial cells, pericytes, Müller cells, and adjacent retinal pigment epithelial cells, are involved in the pathological processes of DR. According to recent research, oxidative stress, inflammation, ferroptosis, pyroptosis, apoptosis, and angiogenesis contribute to DR. Recent advancements have highlighted that noncoding RNAs could regulate diverse targets in pathological processes that contribute to DR. Noncoding RNAs, including long noncoding RNAs, microRNAs (miRNA), and circular RNAs, are dysregulated in DR, and interact with miRNA, mRNA, or proteins to control the pathological processes of DR. Hence, modulation of noncoding RNAs may have therapeutic effects on DR. Small extracellular vesicles may be valuable tools for transferring noncoding RNAs and regulating the genes involved in progression of DR. However, the roles of noncoding RNA in developing DR are not fully understood; it is critical to summarize the mechanisms for noncoding RNA regulation of pathological processes and pathways related to DR. This review provides a fundamental understanding of the relationship between noncoding RNAs and DR, exploring the mechanism of how noncoding RNA modulates different signaling pathways, and pave the way for finding potential therapeutic strategies for DR.

Classical and Innovative Evidence for Therapeutic Strategies in Retinal Dysfunctions

The human retina is a complex anatomical structure that has no regenerative capacity. The pathogenesis of most retinopathies can be attributed to inflammation, with the activation of the inflammasome protein platform, and to the impact of oxidative stress on the regulation of apoptosis and autophagy/mitophagy in retinal cells. In recent years, new therapeutic approaches to treat retinopathies have been investigated. Experimental data suggest that the secretome of mesenchymal cells could reduce oxidative stress, autophagy, and the apoptosis of retinal cells, and in turn, the secretome of the latter could induce changes in mesenchymal cells. Other studies have evidenced that noncoding (nc)RNAs might be new targets for retinopathy treatment and novel disease biomarkers since a correlation has been found between ncRNA levels and retinopathies. A new field to explore is the interaction observed between the ocular and intestinal microbiota; indeed, recent findings have shown that the alteration of gut microbiota seems to be linked to ocular diseases, suggesting a gut-eye axis. To explore new therapeutical strategies for retinopathies, it is important to use proper models that can mimic the complexity of the retina. In this context, retinal organoids represent a good model for the study of the pathophysiology of the retina.

Non-coding RNAs and exosomal non-coding RNAs in diabetic retinopathy: A narrative review

Diabetic retinopathy (DR) is a devastating complication of diabetes, having extensive and resilient effects on those who suffer from it. As yet, the underlying cell mechanisms of this microvascular disorder are largely unclear. Recently, growing evidence suggests that epigenetic mechanisms can be responsible for gene deregulation leading to the alteration of key processes in the development and progression of DR, in addition to the widely recognized pathological mechanisms. It is noteworthy that seemingly unending epigenetic modifications, caused by a prolonged period of hyperglycemia, may be a prominent factor that leads to metabolic memory, and brings epigenetic entities such as non-coding RNA into the equation. Consequently, further investigation is necessary to truly understand this mechanism. Exosomes are responsible for carrying signals from cells close to the vasculature that are participating in abnormal signal transduction to faraway organs and cells by sailing through the bloodstream. These signs indicate metabolic disorders. With the aid of their encased structure, they can store diverse signaling molecules, which then can be dispersed into the blood, urine, and tears. Herein, we summarized various non-coding RNAs (ncRNAs) that are related to DR pathogenesis. Moreover, we highlighted the role of exosomal ncRNAs in this disease.

Transthyretin-Regulated Diabetic Retinopathy Through the VEGFA/PI3K/AKT Pathway

Purpose

Transthyretin (TTR) plays a regulatory role in a variety of diabetes-related diseases. The objective of this work was to probe whether TTR affects diabetic retinopathy (DR) through the VEGFA/PI3K/AKT pathway.

Methods

High glucose (HG, 25 mM) was used to treat human retinal microvascular endothelial cells (hRMECs) and C57BL/6J mice were intraperitoneally injected with STZ (50 mg/kg) to construct a DR model. In vitro, the effect of TTR on DR was evaluated by measuring hRMEC proliferation, migration, and angiogenesis. The changes in retinal tissue were observed by hematoxylin and eosin staining in vivo. ELISA, immunohistochemistry, and immunofluorescence staining were used to measure VEGFA or CD31 levels. The levels of all proteins were evaluated through Western blot.

Results

The increase of proliferation, migration, and angiogenesis and decrease of apoptosis in hRMECs caused by HG were notably reversed by TTR. TTR greatly impeded HG-raised VEGFA, PI3K p-p85, and p-AKT in hRMECs. Inhibition of TTR further exacerbated the effect of HG-induced hRMECs. Inhibition of VEGFA reversed the effect of HG-induced hRMECs. VEGFA neutralized the function of TTR on cell proliferation, apoptosis, migration, and angiogenesis in HG-triggered hRMECs. It was further confirmed in vivo that TTR can alleviate the occurrence of DR in diabetic mice models.

Conclusions

TTR significantly restrained the progression of DR via molecular modulation of the VEGFA/PI3K/AKT axis.

Roles of long non-coding RNAs in angiogenesis-related diseases: Focusing on non-neoplastic aspects

Angiogenesis is a key process in organ and tissue morphogenesis, as well as growth during human development, and is coordinated by pro- and anti-angiogenic factors. When this balance is affected, the related physiological and pathological changes lead to disease. Long non-coding RNAs (lncRNAs) are an important class of non-coding RNAs that do not encode proteins, but play a dynamic role in regulating gene expression. LncRNAs have been reported to be extensively involved in angiogenesis, particularly tumor angiogenesis. The non-tumor aspects have received relatively little attention and summary, but there is a broad space for research and exploration on lncRNA-targeted angiogenesis in this area. In this review, we focus on lncRNAs in angiogenesis-related diseases other than tumors, such as atherosclerosis, myocardial infarction, stroke, diabetic complications, hypertension, osteoporosis, dermatosis, as well as, endocrine, neurological, and other systemic disorders. Moreover, multiple cell types have been implicated in lncRNA-targeted angiogenesis, but only endothelial cells have attracted widespread attention. Thus, we explore the roles of other cells. Finally, we summarize the potential research directions in the area of lncRNAs and angiogenesis that can be undertaken by combining cutting-edge technology and interdisciplinary research, which will provide new insights into the involvement of lncRNAs in angiogenesis-related diseases.

Role of Lnc-RNAs in the Pathogenesis and Development of Diabetic Retinopathy

Important advances in diabetic retinopathy (DR) research and management have occurred in the last few years. Neurodegenerative changes before the onset of microvascular alterations have been well established. So, new strategies are required for earlier and more effective treatment of DR, which still is the first cause of blindness in working age. We describe herein gene regulation through Lnc-RNAs as an interesting subject related to DR. Long non-coding RNAs (Lnc-RNAs) are non-protein-coding transcripts larger than 200 nucleotides. Lnc-RNAs regulate gene expression and protein formation at the epigenetic, transcriptional, and translational levels and can impact cell proliferation, apoptosis, immune response, and oxidative stress. These changes are known to take part in the mechanism of DR. Recent investigations pointed out that Lnc-RNAs might play a role in retinopathy development as Metastasis-Associated Lung Adenocarcinoma Transcript (Lnc-MALAT1), Maternally expressed gene 3 (Lnc-MEG3), myocardial-infarction-associated transcript (Lnc-MIAT), Lnc-RNA H19, Lnc-RNA HOTAIR, Lnc-RNA ANRIL B-Raf proto-oncogene (Lnc-RNA BANCR), small nucleolar RNA host gene 16 (Lnc-RNA SNHG16) and others. Several molecular pathways are impacted. Some of them play a role in DR pathophysiology, including the PI3K-Akt signaling axis, NAD-dependent deacetylase sirtuin-1 (Sirti1), p38 mitogen-activated protein kinase (P38/mapk), transforming growth factor beta signaling (TGF-β) and nuclear factor erythroid 2-related factor 2 (Nrf2). The way Lnc-RNAs affect diabetic retinopathy is a question of great relevance. Performing a more in-depth analysis seems to be crucial for researchers if they want to target Lnc-RNAs. New knowledge on gene regulation and biomarkers will enable investigators to develop more specialized therapies for diabetic retinopathy, particularly in the current growing context of precision medicine.

circPTPN22 attenuates immune microenvironment of pancreatic cancer via STAT3 acetylation

Accumulating research implicated that circular RNAs exhibited significant roles in cancer development. Nonetheless, the role regarding circPTPN22 in pancreatic cancer remains unclear. Expression of circPTPN22 in pancreatic cancer cell lines and normal cells was determined with quantitative real-time PCR (qRT-PCR). Cell counting kit-8 assay and colony formation assay were used to measure the proliferation of pancreatic cancer cells. RNA immunoprecipitation and Western blot were employed for investigation the binding between circPTPN22 and STAT3. circPTPN22 expression was highly upregulated in pancreatic cancer tissues and cell lines. Knockdown of circPTPN22 inhibited cell proliferation and attenuates pancreatic cancer immune microenvironment. Furthermore, STAT3 acetylation was involved in these effects. circPTPN22 promoted STAT3 acetylation via inhibiting STAT3/SIRT1 interaction. circPTPN22 attenuates pancreatic cancer immune microenvironment by promoting STAT3 acetylation via inhibiting STAT3/SIRT1 interaction.

A Narrative Review of STAT Proteins in Diabetic Retinopathy: From Mechanisms to Therapeutic Prospects

Diabetic retinopathy (DR), a blinding disease, is one of the high-incidence chronic complications of diabetes. However, the current treatment for DR is mainly based on advanced pathological changes, which cannot reverse pre-existing retinal tissue damage and visual impairment. Signal transducer and activator of transcription (STAT) proteins are essential in DR through early and late stages. They participate in the early stage of DR through multiple mechanisms and have a strong proangiogenic effect in the late stage. Inhibiting STAT proteins activity has also achieved a significant effect in reversing the pathological changes of DR. Thus, STAT proteins are expected to be an effective therapeutic target in the early stage of DR and can make up for inadequate late treatment. This review introduces the structure, signal transduction mode, and biological functions of STAT proteins in detail and focuses on their role in the mechanism of DR. We also summarize the current research on STAT-related biological agents in DR, aiming to provide a theoretical basis for the treatment of DR.

MicroRNA-195-5p facilitates endothelial dysfunction by inhibiting vascular endothelial growth factor A in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a common disorder during pregnancy associated with endothelial dysfunction in the placental vasculature. MicroRNAs (miRNAs), which are short noncoding RNAs that modulate post-transcriptional gene expression, affect GDM progression. MiR-195-5p was reported to be a putative biomarker for GDM diagnosis, whose expression was markedly elevated in serum of GDM patients. Therefore, our study intended to explore whether miR-195-5p regulates endothelial cell dysfunction in GDM. Human placental microvascular endothelial cells (hPMECs) were treated with high concentration of glucose to establish an in vitro GDM model. The apoptosis, proliferation and angiogenesis of hPMECs were detected by flow cytometry analysis, CCK-8 assay and tube formation assay. The binding between vascular endothelial growth factor A (VEGFA) and miR-195-5p was verified by luciferase reporter assay. GDM mouse model was established by intraperitoneal injection of streptozocin. Cell apoptosis and the pathological changes in GDM mouse placenta tissues were evaluated by TUNEL staining and HE staining. Gene expression was detected by RT-qPCR. Protein levels were evaluated by western blotting. In this study, miR-195-5p knockdown promoted the proliferation and angiogenesis as well as inhibited the apoptosis of HG-treated hPMECs. MiR-195-5p targeted VEGFA, whose expression was downregulated in HG-treated hPMECs. VEGFA silencing antagonized the influence of miR-195-5p knockdown on the phenotypes of HG-treated hPMECs. Additionally, miR-195-5p inhibition decelerated cell apoptosis and improved pathological changes in GDM mouse placenta tissues. MiR-195-5p level was negatively correlated to VEGFA level in GDM mouse placenta tissues. Overall, miR-195-5p facilitates the endothelial cell dysfunction by inhibiting VEGFA in GDM.

miRNA, lncRNA and circRNA: Targeted Molecules Full of Therapeutic Prospects in the Development of Diabetic Retinopathy

Diabetic retinopathy (DR) is a common diabetic complication and the main cause of blindness worldwide, which seriously affects the quality of life of patients. Studies have shown that noncoding RNA (ncRNA) has distinct differentiated expression in DR and plays an important role in the occurrence and development of DR. ncRNAs represented by microRNAs (miRNAs), lncRNAs (lncRNAs), and circRNAs (circRNAs) have been shown to be widely involved in the regulation of gene expression and affect multiple biological processes of retinopathy. This article will review three RNAs related to the occurrence and development of DR on the basis of previous studies (especially their effects on retinal microangiopathy, retinal pigment epithelial cells, and retinal nerve cells) and discuss their underlying mechanisms and connections. Overall, this review will help us better understand the role of ncRNAs in the occurrence and development of DR and provide ideas for exploring potential therapeutic directions and targets.