Sodium Butyrate Inhibits Neovascularization Partially via TNXIP/VEGFR2 Pathway

Fecal Microbial Profiles and Short-Chain Fatty Acid/Bile Acid Metabolomics in Patients With Age-Related Macular Degeneration: A Pilot Study

Purpose

Age-related macular degeneration (AMD) is a multifactorial disease, and studies have implicated the role of gut microbiota in its pathogenesis. However, characterization of microbiome dysbiosis and associated microbial-derived metabolomic profiles across AMD stages remains unknown. In this pilot study, we explored how gut microbiome composition and gut-derived metabolites differ in AMD.

Methods

Our pilot study analyzed fasted stool samples that were collected from 22 patients at a tertiary academic center. Subjects were classified as control, intermediate AMD, or advanced AMD based on clinical presentation. 16S rRNA amplicon sequencing and standard chromatography-mass spectrometry methods were used to identify bacterial taxonomy composition and abundance of short-chain fatty acids (SCFAs) and bile acids (BAs), respectively. Genetic testing was used to investigate the frequency of 14 high-risk single nucleotide polymorphisms (SNPs) associated with AMD in the AMD cohort.

Results

Forty-three differentially abundant genera were present among the control, intermediate, and advanced groups. Taxa with known roles in immunologic pathways, such as Desulfovibrionales (q = 0.10) and Terrisporobacter (q = 1.16e-03), were in greater abundance in advanced AMD patients compared to intermediate. Advanced AMD patients had decreased abundance of 12 SCFAs, including acetate (P = 0.002), butyrate (P = 0.04), and propionate (P = 0.01), along with 12 BAs, including taurocholic acid (P = 0.02) and tauroursodeoxycholic acid (P = 0.04). Frequencies of high-risk SNPs were not significantly different between the intermediate and advanced AMD groups.

Conclusions

This pilot study identifies distinct gut microbiome compositions and metabolomic profiles associated with AMD and its stages, providing preliminary evidence of a potential link between gut microbiota and AMD pathogenesis. To validate these findings and elucidate the underlying mechanisms, future research with larger cohorts and more comprehensive sampling is strongly recommended.

Sodium butyrate inhibits activation of ROS/NF-κB/NLRP3 signaling pathway and angiogenesis in human retinal microvascular endothelial cells

BACKGROUND

To determine the impact of sodium butyrate on the activation of the reactive oxygen species (ROS)/nuclear factor kappa B (NF-κB)/NLR family pyrin domain containing 3 (NLRP3) signaling pathway and angiogenesis in human retinal microvascular endothelial cells (HRMECs) caused by high glucose (HG).

METHODS

HRMECs were grown for 24 h or 72 h in HG solution (30 mmol/L D-glucose) with 5 mM NaB. Using Cell Counting Kit-8, the effects of HG and NaB levels on the viability of HRMECs were examined. Using various kits, intracellular ROS levels, lactate dehydrogenase (LDH), and Malondialdehyde (MDA) in cell supernatants were measured. Western blot, Immunofluorescence, and Real-time quantitative polymerase chain reaction were employed to quantify protein and messenger RNA expression. Using wound-healing and tube formation tests, the migratory proficiency and angiogenesis of HRMECs were evaluated.

RESULTS

NaB demonstrated a reduction in ROS production, as well as the release of LDH and MDA in HG-induced HRMECs. Additionally, NaB led to a decrease in protein expression of phosphorylation of NF-κB, NLRP3, Caspase 1, interleukin, vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. The impact of HG on zonula occluden-1, a tight junction protein, was attenuated by NaB. Furthermore, NaB inhibited the migration and tube formation of HRMECs partly by ROS/NF-κB/NLRP3 pathway.

CONCLUSION

NaB suppresses the activation of ROS/NF-κB/NLRP3 signaling pathway and angiogenesis in HRMECs induced by HG.

Short-Chain Fatty Acids and the Gut-Retina Connection: A Systematic Review

The interplay between gut microbiota and retinal health, known as the gut--retina axis, has gained increasing attention in recent years. Short-chain fatty acids (SCFAs), metabolites produced by gut microbiota, have been identified as key mediators of gut-retina communication. This systematic review explores the role of SCFAs in retinal health and their potential impact on the development and progression of retinal diseases, such as diabetic retinopathy (DR), age-related macular degeneration (AMD), and glaucoma. A literature search was conducted across multiple databases, including PubMed, Google Scholar, and Science Direct, to identify studies published between 2014 and December 2024. Studies were included if they investigated the effects of SCFAs on retinal structure, function, or disease pathogenesis in animal models or human subjects. The review included 10 original articles spanning both preclinical and clinical studies. Evidence suggests that SCFAs play a crucial role in maintaining retinal homeostasis through anti-inflammatory and neuroprotective mechanisms. Dysbiosis of the gut microbiota, leading to altered SCFA production, was associated with increased retinal inflammation, oxidative stress, and vascular dysfunction. Furthermore, reduced SCFA levels were linked to the progression of retinal diseases, such as diabetic retinopathy and age-related macular degeneration. Modulation of gut microbiota and SCFA levels through dietary interventions or probiotics may represent a novel therapeutic strategy for preventing or managing retinal diseases. Further research is needed to elucidate the precise molecular mechanisms underlying SCFA-mediated retinal protection and to evaluate the efficacy of targeted therapies in clinical settings.

Non-coding RNAs and angiogenesis in cardiovascular diseases: a comprehensive review

Non-coding RNAs (ncRNAs) have key roles in the etiology of many illnesses, including heart failure, myocardial infarction, stroke, and in physiological processes like angiogenesis. In transcriptional regulatory circuits that control heart growth, signaling, and stress response, as well as remodeling in cardiac disease, ncRNAs have become important players. Studies on ncRNAs and cardiovascular disease have made great progress recently. Here, we go through the functions of non-coding RNAs (ncRNAs) like circular RNAs (circRNAs), and microRNAs (miRNAs) as well as long non-coding RNAs (lncRNAs) in modulating cardiovascular disorders.

Unveiling the gut-eye axis: how microbial metabolites influence ocular health and disease

The intricate interplay between the gut microbiota and ocular health has surpassed conventional medical beliefs, fundamentally reshaping our understanding of organ interconnectivity. This review investigates into the intricate relationship between gut microbiota-derived metabolites and their consequential impact on ocular health and disease pathogenesis. By examining the role of specific metabolites, such as short-chain fatty acids (SCFAs) like butyrate and bile acids (BAs), herein we elucidate their significant contributions to ocular pathologies, thought-provoking the traditional belief of organ sterility, particularly in the field of ophthalmology. Highlighting the dynamic nature of the gut microbiota and its profound influence on ocular health, this review underlines the necessity of comprehending the complex workings of the gut-eye axis, an emerging field of science ready for further exploration and scrutiny. While acknowledging the therapeutic promise in manipulating the gut microbiome and its metabolites, the available literature advocates for a targeted, precise approach. Instead of broad interventions, it emphasizes the potential of exploiting specific microbiome-related metabolites as a focused strategy. This targeted approach compared to a precision tool rather than a broad-spectrum solution, aims to explore the therapeutic applications of microbiome-related metabolites in the context of various retinal diseases. By proposing a nuanced strategy targeted at specific microbial metabolites, this review suggests that addressing specific deficiencies or imbalances through microbiome-related metabolites might yield expedited and pronounced outcomes in systemic health, extending to the eye. This focused strategy holds the potential in bypassing the irregularity associated with manipulating microbes themselves, paving a more efficient pathway toward desired outcomes in optimizing gut health and its implications for retinal diseases.

Long-term intake of Lactobacillus helveticus enhances bioavailability of omega-3 fatty acids in the mouse retina

Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA), are required for the structure and function of the retina. Several observational studies indicate that consumption of a diet with relatively high levels of n-3 PUFAs, such as those provided by fish oils, has a protective effect against the development of age-related macular degeneration. Given the accumulating evidence showing the role of gut microbiota in regulating retinal physiology and host lipid metabolism, we evaluated the potential of long-term dietary supplementation with the Gram-positive bacterium Lactobacillus helveticus strain VEL12193 to modulate the retinal n-3 PUFA content. A set of complementary approaches was used to study the impact of such a supplementation on the gut microbiota and host lipid/fatty acid (FA) metabolism. L. helveticus-supplementation was associated with a decrease in retinal saturated FAs (SFAs) and monounsaturated FAs (MUFAs) as well as an increase in retinal n-3 and omega-6 (n-6) PUFAs. Interestingly, supplementation with L. helveticus enriched the retina in C22:5n-3 (docosapentaenoic acid, DPA), C22:6n-3 (DHA), C18:2n-6 (linoleic acid, LA) and C20:3n-6 (dihomo gamma-linolenic acid, DGLA). Long-term consumption of L. helveticus also modulated gut microbiota composition and some changes in OTUs abundance correlated with the retinal FA content. This study provides a proof of concept that targeting the gut microbiota could be an effective strategy to modulate the retinal FA content, including that of protective n-3 PUFAs, thus opening paths for the design of novel preventive and/or therapeutical strategies for retinopathies.

Dysregulation of histone deacetylases in ocular diseases

Ocular diseases are a growing global concern and have a significant impact on the quality of life. Cataracts, glaucoma, age-related macular degeneration, and diabetic retinopathy are the most prevalent ocular diseases. Their prevalence and the global market size are also increasing. However, the available pharmacotherapy is currently limited. These diseases share common pathophysiological features, including neovascularization, inflammation, and/or neurodegeneration. Histone deacetylases (HDACs) are a class of enzymes that catalyze the removal of acetyl groups from lysine residues of histone and nonhistone proteins. HDACs are crucial for regulating various cellular processes, such as gene expression, protein stability, localization, and function. They have also been studied in various research fields, including cancer, inflammatory diseases, neurological disorders, and vascular diseases. Our study aimed to investigate the relationship between HDACs and ocular diseases, to identify a new strategy for pharmacotherapy. This review article explores the role of HDACs in ocular diseases, specifically focusing on diabetic retinopathy, age-related macular degeneration, and retinopathy of prematurity, as well as optic nerve disorders, such as glaucoma and optic neuropathy. Additionally, we explore the interplay between HDACs and key regulators of fibrosis and angiogenesis, such as TGF-β and VEGF, highlighting the potential of targeting HDAC as novel therapeutic strategies for ocular diseases.

Oral Metformin Inhibits Choroidal Neovascularization by Modulating the Gut-Retina Axis

Purpose

Emerging data indicate that metformin may prevent the development of age-related macular degeneration (AMD). Whereas the underlying mechanisms of metformin's anti-aging properties remain undetermined, one proposed avenue is the gut microbiome. Using the laser-induced choroidal neovascularization (CNV) model, we investigate the effects of oral metformin on CNV, retinal pigment epithelium (RPE)/choroid transcriptome, and gut microbiota.

Methods

Specific pathogen free (SPF) male mice were treated via daily oral gavage of metformin 300 mg/kg or vehicle. Male mice were selected to minimize sex-specific differences to laser induction and response to metformin. Laser-induced CNV size and macrophage/microglial infiltration were assessed by isolectin and Iba1 immunostaining. High-throughput RNA-seq of the RPE/choroid was performed using Illumina. Fecal pellets were analyzed for gut microbiota composition/pathways with 16S rRNA sequencing/shotgun metagenomics, as well as microbial-derived metabolites, including small-chain fatty acids and bile acids. Investigation was repeated in metformin-treated germ-free (GF) mice and antibiotic-treated/GF mice receiving fecal microbiota transplantation (FMT) from metformin-treated SPF mice.

Results

Metformin treatment reduced CNV size (P < 0.01) and decreased Iba1+ macrophage/microglial infiltration (P < 0.005). One hundred forty-five differentially expressed genes were identified in the metformin-treated group (P < 0.05) with a downregulation in pro-angiogenic genes Tie1, Pgf, and Gata2. Furthermore, metformin altered the gut microbiome in favor of Bifidobacterium and Akkermansia, with a significant increase in fecal levels of butyrate, succinate, and cholic acid. Metformin did not suppress CNV in GF mice but colonization of microbiome-depleted mice with metformin-derived FMT suppressed CNV.

Conclusions

These data suggest that oral metformin suppresses CNV, the hallmark lesion of advanced neovascular AMD, via gut microbiome modulation.

VR-10 polypeptide interacts with CD36 to induce cell apoptosis and autophagy in choroid-retinal endothelial cells: Identification of VR-10 as putative novel therapeutic agent for choroid neovascularization (CNV) treatment

Choroid neovascularization (CNV) is important adverse pathological changes that contributes to the aggravation of hypoxic-ischemic eye diseases, and our preliminary work evidences that the thrombospondin-1 (TSP-1) synthetic polypeptide VR-10 may be the candidate therapeutic agent for the treatment of CNV, but its detailed effects and molecular mechanisms are not fully delineated. In this study, the CNV models in BN rats were established by using the laser photocoagulation method, which were further subjected to VR-10 peptide treatment. The RNA-seq and bioinformatics analysis suggested that VR-10 peptide significantly altered the expression patterns of genes in the rat ocular tissues, and the changed genes were especially enriched in the CD36-associated signal pathways. Next, by performing the Real-Time qPCR and Western Blot analysis, we expectedly found that VR-10 upregulated the anti-angiogenesis biomarker (PEDF) and downregulated pro-angiogenesis biomarkers (VEGF, HIF-1 and IL-17) in rat tissues. In addition, we evidenced that VR-10 downregulated CDK2, CDK4, CDK6, Cyclin D1 and Cyclin D2 to induce cell cycle arrest, upregulated cleaved Caspase-3, Bax and downregulated Bcl-2 to promote cell apoptosis, and increased LC3B-II/I ratio and facilitate p62 degradation to promote cell autophagy in RF/6A cells, which were all reversed by knocking down CD36. Moreover, VR-10 upregulated PEDF, and decreased the expression levels of VEGF, HIF-1 and IL-17 to block angiogenesis of RF/6A cells in a CD36-dependent manner. Taken together, VR-10 peptide interacts with its receptor CD36 to regulate the biological functions of RF/6A cells, and these data suggest that VR-10 peptide may be the putative therapeutic drug for the treatment of CNV in clinic.

MicroRNA-136-5p from Endothelial Progenitor Cells-released Extracellular Vesicles Mediates TXNIP to Promote the Dissolution of Deep Venous Thrombosis

OBJECTIVE

Endothelial progenitor cells-released extracellular vesicles (EPCs-EVs) have previously been reported to promote the dissolution of deep venous thrombosis (DVT) through delivery of microRNA (miR). Given that, this research was projected to search the relative action of EPCs-EVs transferring of miR-136-5p in DVT.

METHODS

From EPCs transfected with miR-136-5p agomir or antagomir, EVs were extracted and then injected into DVT mice. Meanwhile, based on the treatment with EPCs-EVs loading miR-136-5p antagomir, silenced thioredoxin-interacting protein (TXNIP) lentivirus was injected into DVT mice to perform the rescue experiments. Afterwards, the length and weight of venous thrombosis, EPC apoptosis and inflammatory factors, plasmin, fibrinogen, and thrombin-antithrombin were measured. miR-136-5p and TXNIP expression in DVT mice, and their targeting relationship were evaluated.

RESULTS

miR-136-5p expression was suppressed and TXNIP expression was elevated in DVT mice. EPCs-EV reduced the length and weight of venous thrombosis, suppressed cell apoptosis and inflammatory reaction, as well as elevated level of plasmin, and reduced levels of fibrinogen and thrombin-antithrombin in DVT mice. Restored miR-136-5p loaded by EPCs-EV further attenuated DVT but EPCs-EV transfer of depleted miR-136-5p resulted in the opposite consequences. miR-136-5p targeted TXNIP and silenced TXNIP rescued the effect of EPCs-EV transfer of depleted miR-136-5p on DVT.

CONCLUSION

miR-136-5p from EPCs-EV suppresses TXNIP expression to reduce the thrombus size in DVT, offering a promising treatment target for DVT.

Oxidized low-density lipoprotein contributes to injury of endothelial cells via the circ_0090231/miR-9-5p/TXNIP axis

Atherosclerosis (AS) has been reported to induce severe clinical complications. Circular RNA (circRNA) circ_0090231 was found to be aberrantly overexpressed in oxidized low-density lipoprotein (ox-LDL)-induced endothelial cells. This study was designed to explore the role and mechanism of circ_0090231 in ox-LDL-triggered endothelial cell injury in AS. Circ_0090231, microRNA-9-5p (miR-9-5p), and thioredoxin interacting protein (TXNIP) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell viability, angiogenesis, and apoptosis were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), tube formation, and flow cytometry assay. Bcl-2, Bax, and TXNIP protein levels were gauged by western blot assay. Malondialdehyde (MDA), lactate dehydrogenase (LDH), and superoxide dismutase (SOD) activity were determined by special kits. Tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin 6 (IL-6) levels were analyzed using enzyme-linked immunosorbent assay (ELISA) kits. The binding relationship between miR-9-5p and circ_0090231 or TXNIP was predicted by starBase, and then verified by a dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Circ_0090231 and TXNIP were increased, and miR-9-5p was decreased in ox-LDL-treated HUVECs. Moreover, circ_0090231 knockdown mitigated ox-LDL-induced HUVEC injury by boosting angiogenesis, oxidative stress, and inflammation, and hindering apoptosis. The mechanical analysis revealed that circ_0090231 acted as a sponge of miR-9-5p to regulate TXNIP expression. Circ_0090231 could attenuate ox-LDL-mediated HUVEC damage by the miR-9-5p/TXNIP axis, providing a promising therapeutic strategy for AS treatment.

The Long-Noncoding RNA TUG1 Regulates Oxygen-Induced Retinal Neovascularization in Mice via MiR-299

Purpose

The oxygen-induced retinal neovascularization mouse model closely approximates pathological changes associated with human retinal neovascularization-associated diseases, including retinopathies. We used this model and human retinal endothelial cells (HRECs) under hypoxia to explore the relationship between taurine upregulated gene-1 (TUG1), vascular endothelial growth factor (VEGF), and miR-299-3p on retinopathy of prematurity (ROP).

Methods

An oxygen-induced retinopathy (OIR) mouse model was established; the mice were divided into a normal control group, OIR group, TUG1 control group (lentivirus control), and TUG1-knockdown group. The apoptosis of retinal cells was evaluated using a TUNEL assay. Angiogenic, apoptotic, and inflammatory factors were detected by Western blot, immunohistochemistry, and immunofluorescence analyses. HRECs were cultured under hypoxia and assessed for VEGF expression, apoptosis, tubule formation, and migration ability. The relationship between TUG1, VEGF, and miR-299-3p was detected via a dual luciferase reporter gene assay.

Results

Intravitreal injection of TUG1 lentivirus reduced the inflammatory response in the mouse retinal tissue and markedly reduced pathological changes in the retina. Overexpression of miR-299 in HRECs reduced the apoptosis rate, tube formation, and migration ability of hypoxia-treated cells, thereby inhibiting the formation of new blood vessels. The dual luciferase reporter gene assay suggested that miR-299 has binding sites for TUG1 and VEGF.

Conclusions

TUG1 reduces the expression of VEGFA by competitively adsorbing miR-299-3p and facilitates the regulation of retinal neovascularization, suggesting that it may serve as a new therapeutic target for retinal neovascular diseases.