A Pilot Study on MicroRNA Profile in Tear Fluid to Predict Response to Anti-VEGF Treatments for Diabetic Macular Edema

Tear Protein Markers for Diabetic Retinopathy and Diabetic Macular Edema - Towards an Early Diagnosis and Better Prognosis

BACKGROUND

Diabetic eye disease is a highly prevalent and sight-threatening disorder. It is a disease of neuro-vascular unit of the retina, if left untreated can cause blindness. Therapeutic approaches followed for its treatment can only restrict the progression of the disease with highly variable results. There is no known biomarker for an early diagonsis of this disease, therefore by the time it is detected it goes beyond repair. This creates a massive demand for development of such biomarkers that help detect disease in its earlier stages.

METHODS

PUBMED (https://pubmed.ncbi.nlm.nih.gov/) was searched for articles relevant to the topic published till November 2023. The search was made using keywords such as Diabetic Retinopathy, inflammation, tear, biomarker, proteomics etc. The studies providing relevant information to prove the importance of biomarker discovery were chosen. After compiling the data, the manuscript writing was planned under relevant headings and sub-headings.

RESULTS

The review provides a comprehensive overview of all the tear protein biomarker studies in the field of DR and DME. Briefly, their potential in other diseases is also elucidated. While there are many studies pertaining to DR biomarkers, the identified markers lack validations which has restricted their usage in clinics. In case of DME, there was no such study towards biomarker discovery for its diagnosis and prognosis.

CONCLUSIONS

The review highlights major studies and their lacunae in the field of biomarkers discovery for DR and DME.

Role of Systemic Factors in Improving the Prognosis of Diabetic Retinal Disease and Predicting Response to Diabetic Retinopathy Treatment

Topic

To review clinical evidence on systemic factors that might be relevant to update diabetic retinal disease (DRD) staging systems, including prediction of DRD onset, progression, and response to treatment.

Clinical relevance

Systemic factors may improve new staging systems for DRD to better assess risk of disease worsening and predict response to therapy.

Methods

The Systemic Health Working Group of the Mary Tyler Moore Vision Initiative reviewed systemic factors individually and in multivariate models for prediction of DRD onset or progression (i.e., prognosis) or response to treatments (prediction).

Results

There was consistent evidence for associations of longer diabetes duration, higher glycosylated hemoglobin (HbA1c), and male sex with DRD onset and progression. There is strong trial evidence for the effect of reducing HbA1c and reducing DRD progression. There is strong evidence that higher blood pressure (BP) is a risk factor for DRD incidence and for progression. Pregnancy has been consistently reported to be associated with worsening of DRD but recent studies reflecting modern care standards are lacking. In studies examining multivariate prognostic models of DRD onset, HbA1c and diabetes duration were consistently retained as significant predictors of DRD onset. There was evidence of associations of BP and sex with DRD onset. In multivariate prognostic models examining DRD progression, retinal measures were consistently found to be a significant predictor of DRD with little evidence of any useful marginal increment in prognostic information with the inclusion of systemic risk factor data apart from retinal image data in multivariate models. For predicting the impact of treatment, although there are small studies that quantify prognostic information based on imaging data alone or systemic factors alone, there are currently no large studies that quantify marginal prognostic information within a multivariate model, including both imaging and systemic factors.

Conclusion

With standard imaging techniques and ways of processing images rapidly evolving, an international network of centers is needed to routinely capture systemic health factors simultaneously to retinal images so that gains in prediction increment may be precisely quantified to determine the usefulness of various health factors in the prognosis of DRD and prediction of response to treatment.

Financial Disclosures

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

Global research trends and future directions in diabetic macular edema research: A bibliometric and visualized analysis

BACKGROUND

Diabetic Macular Edema (DME) significantly impairs vision in diabetics, with varied patient responses to current treatments like anti-vascular endothelial growth factor (VEGF) therapy underscoring the necessity for continued research into more effective strategies. This study aims to evaluate global research trends and identify emerging frontiers in DME to guide future research and clinical management.

METHODS

A qualitative and quantitative analysis of publications related to diabetic macular edema retrieved from the Web of Science Core Collection (WoSCC) between its inception and September 4, 2023, was conducted. Microsoft Excel, CiteSpace, VOSviewer, Bibliometrix Package, and Tableau were used for the bibliometric analysis and visualization. This encompasses an examination of the overall distribution of annual output, major countries, regions, institutions, authors, core journals, co-cited references, and keyword analyses.

RESULTS

Overall, 5624 publications were analyzed, indicating an increasing trend in DME research. The United States was identified as the leading country in DME research, with the highest h-index of 135 and 91,841 citations. Francesco Bandello emerged as the most prolific author with 97 publications. Neil M. Bressler has the highest h-index and highest total citation count of 46 and 9692, respectively. The journals "Retina - the Journal of Retinal and Vitreous Diseases" and "Ophthalmology" were highlighted as the most prominent in this field. "Retina" leads with 354 publications, a citation count of 11,872, and an h-index of 59. Meanwhile, "Ophthalmology" stands out with the highest overall citation count of 31,558 and the highest h-index of 90. The primary research focal points in diabetic macular edema included "prevalence and risk factors," "pathological mechanisms," "imaging modalities," "treatment strategies," and "clinical trials." Emerging research areas encompassed "deep learning and artificial intelligence," "novel treatment modalities," and "biomarkers."

CONCLUSION

Our bibliometric analysis delineates the leading role of the United States in DME research. We identified current research hotspots, including epidemiological studies, pathophysiological mechanisms, imaging advancements, and treatment innovations. Emerging trends, such as the integration of artificial intelligence and novel therapeutic approaches, highlight future directions. These insights underscore the importance of collaborative and interdisciplinary approaches in advancing DME research and clinical management.

miR-196b-5p regulates inflammatory process and migration via targeting Nras in trabecular meshwork cells

Glaucoma, an insidious ophthalmic pathology, is typified by an aberrant surge in intraocular pressure (IOP) which culminates in the degeneration of retinal ganglion cells and optical neuropathy. The mitigation of IOP stands as the principal therapeutic strategy to forestall vision loss. The trabecular meshwork's (TM) integrity and functionality are pivotal in modulating aqueous humor egress. Despite their potential significance in glaucomatous pathophysiology, the implications of microRNAs (miRNAs) on TM functionality remain largely enigmatic. Transcriptomic sequencing was employed to delineate the miRNA expression paradigm within the limbal region of rodent glaucoma models, aiming to elucidate miRNA-mediated mechanisms within the glaucomatous milieu. Analytical scrutiny of the sequencing data disclosed 174 miRNAs with altered expression profiles, partitioned into 86 miRNAs with augmented expression and 88 with diminished expression. Notably, miRNAs such as hsa-miR-196b-5p were identified as having substantial expression discrepancies with concomitant statistical robustness, suggesting a potential contributory role in glaucomatous progression. Subsequent in vitro assays affirmed that miR-196b-5p augments the inflammatory cascade within immortalized human TM (iHTM) and glaucoma-induced human TM (GTM3) cells, concurrently attenuating cellular proliferation, motility, and cytoskeletal architecture. Additionally, miR-196b-5p implicates itself in the regulation of IOP and inflammatory processes in rodent models. At a mechanistic level, miR-196b-5p modulates its effects via the targeted repression of Nras (neuroblastoma RAS viral oncogene homolog). Collectively, these transcriptomic investigations furnish a comprehensive vista into the regulatory roles of miRNAs within the glaucomatous framework, and the identification of differentially expressed miRNAs alongside their targets could potentially illuminate novel molecular pathways implicated in glaucoma, thereby aiding in the development of innovative therapeutic avenues.

Tear Film MicroRNAs as Potential Biomarkers: A Review

MicroRNAs are non-coding RNAs that serve as regulatory molecules in a variety of pathways such as inflammation, metabolism, homeostasis, cell machinery, and development. With the progression of sequencing methods and modern bioinformatics tools, novel roles of microRNAs in regulatory mechanisms and pathophysiological states continue to expand. Advances in detection methods have further enabled larger adoption of studies utilizing minimal sample volumes, allowing the analysis of microRNAs in low-volume biofluids, such as the aqueous humor and tear fluid. The reported abundance of extracellular microRNAs in these biofluids has prompted studies to explore their biomarker potential. This review compiles the current literature reporting microRNAs in human tear fluid and their association with ocular diseases including dry eye disease, Sjögren's syndrome, keratitis, vernal keratoconjunctivitis, glaucoma, diabetic macular edema, and diabetic retinopathy, as well as non-ocular diseases, including Alzheimer's and breast cancer. We also summarize the known roles of these microRNAs and shed light on the future progression of this field.

MicroRNA Profiling from Tears as a Potential Non-invasive Method for Early Detection of Diabetic Retinopathy

Diabetic retinopathy (DR) is a vascular complication of diabetes that can lead to partial or complete loss of vision. Early detection and treatment of DR can prevent blindness. Regular clinical examination is recommended for DR diagnosis; however, it is not always possible or feasible due to limited resources, expertise, time, and infrastructure. Several clinical and molecular biomarkers are proposed for the prediction of DR including microRNAs. MicroRNAs are a class of small non-coding RNAs that are found in biofluids and can be measured using reliable and sensitive methods. The most commonly used biofluid for microRNA profiling is plasma or serum; however, tear fluid (tears) is also demonstrated to contain microRNAs. MicroRNAs isolated from tears present a non-invasive source for DR detection. Different methods of microRNA profiling are available including digital PCR-based methods that can detect up to a single copy of microRNA in the biofluids. Here, we describe microRNA isolation from tears using manual method as well as using a high-throughput automated platform followed by microRNA profiling using digital PCR system.

Potential utility of miRNAs for liquid biopsy in breast cancer

Breast cancer (BC) remains the most prevalent malignancy due to its incidence rate, recurrence, and metastasis in women. Conventional strategies of cancer detection– mammography and tissue biopsy lack the capacity to detect the complete cancer genomic landscape. Besides, they often give false- positive or negative results. The presence of this and other disadvantages such as invasiveness, high-cost, and side effects necessitates developing new strategies to overcome the BC burden. Liquid biopsy (LB) has been brought to the fore owing to its early detection, screening, prognosis, simplicity of the technique, and efficient monitoring. Remarkably, microRNAs (miRNAs)– gene expression regulators seem to play a major role as biomarkers detected in the samples of LB. Particularly, miR-21 and miR-155 among other possible candidates seem to serve as favorable biomarkers in the diagnosis and prognosis of BC. Hence, this review will assess the potential utility of miRNAs as biomarkers and will highlight certain promising candidates for the LB approach in the diagnosis and management of BC that may optimize the patient outcome.

Tear miRNA expression analysis reveals miR-203 as a potential regulator of corneal epithelial cells

Background

microRNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression. They are found within cells and in body fluids. Extracellular miRNAs have been shown to associate with the surrounding tissues. Therefore, we predicted that miRNAs in tears may contribute to regulate corneal epithelial cell function. However, information on the miRNA expression profile of tears is limited and the specific functions of tear miRNAs for corneal epithelial cells are still unknown. To study the role of tear miRNAs, we determined which miRNAs are highly expressed in tears and examined the involvement of miRNAs in corneal epithelial cell viability.

Methods

miRNAs extracted from monkey tears and sera were subjected to microarray analysis. miRNAs of which expression levels were higher in tears than in sera were selected, and their expression levels were quantified by quantitative polymerase chain reaction (qPCR). To examine miRNA function, mimics and inhibitors of miRNAs were transfected into human corneal epithelial (HCE-T) cells and incubated for 24 or 48 h. After transfection of miRNA mimics and inhibitors, the viability of HCE-T cells was measured using the water soluble tetrazolium salt (WST) assay, and microarray analysis and qPCR were performed using total RNA extracted from HCE-T cells. siRNAs of the candidate targets for miR-203 were transfected into HCE-T cells and the WST assay was performed. To determine a direct target gene for miR-203, a dual luciferase reporter assay was performed in HCE-T cells using a luciferase reporter plasmid containing 3′-UTR of human IGFBP5.

Results

Microarray and qPCR analyses showed that miR-184 and miR-203 were expressed significantly more highly in tears than in sera (165,542.8- and 567.8-fold, respectively, p < 0.05). Of these two miRNAs, transfection of a miR-203 mimic significantly reduced the viability of HCE-T cells (p < 0.05), while a miR-203 inhibitor significantly increased this viability (p < 0.05). miR-203 mimic downregulated insulin-like growth factor-binding protein 5 (IGFBP5) and nuclear casein kinase and cyclin-dependent kinase substrate 1 (NUCKS1), while miR-203 inhibitor upregulated these two genes. Transfection of IGFBP5-siRNA decreased the viability of HCE-T cells. miR-203 mimic significantly diminished the luciferase reporter activity.

Conclusions

In this study, we identified miRNAs that are highly expressed in tears, and the inhibition of miR-203 increases the viability of corneal epithelial cells. Our results suggest that miR-203 contributes to regulating the homeostasis of corneal epithelial cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02141-9.

Anti-SARS-CoV-2 Strategies and the Potential Role of miRNA in the Assessment of COVID-19 Morbidity, Recurrence, and Therapy

Recently, we have experienced a serious pandemic. Despite significant technological advances in molecular technologies, it is very challenging to slow down the infection spread. It appeared that due to globalization, SARS-CoV-2 spread easily and adapted to new environments or geographical or weather zones. Additionally, new variants are emerging that show different infection potential and clinical outcomes. On the other hand, we have some experience with other pandemics and some solutions in virus elimination that could be adapted. This is of high importance since, as the latest reports demonstrate, vaccine technology might not follow the new, mutated virus outbreaks. Thus, identification of novel strategies and markers or diagnostic methods is highly necessary. For this reason, we present some of the latest views on SARS-CoV-2/COVID-19 therapeutic strategies and raise a solution based on miRNA. We believe that in the face of the rapidly increasing global situation and based on analogical studies of other viruses, the possibility of using the biological potential of miRNA technology is very promising. It could be used as a promising diagnostic and prognostic factor, as well as a therapeutic target and tool.

Expression of microRNA-155-5p in patients with refractory diabetic macular edema and its regulatory mechanism

Diabetic macular edema (DME) is the main cause of visual impairment in diabetic patients, but its pathogenesis remains unclear. The purpose of the present study was to analyze the expression of microRNA (miR)-155-5p in patients with DME and its regulatory mechanism. A total of 72 patients diagnosed with DME and 17 with idiopathic macular hole (MH) were recruited. Among samples from patients with DME, 45 were DME and 27 were refractory DME, whereas patients with idiopathic MH served as the control group. Optical coherence tomography and fundus photograph analysis revealed that part of the retina in the fundus of patients with DME was thickened, with macular edema occurring simultaneously. In refractory patients with DME, macular edema was associated with bleeding and a dark cavity between retinal layers. Through reverse transcription-quantitative PCR analysis, miR-155-5p was highly expressed in the aqueous humor (AH) and plasma of patients with DME compared with that in patients with MH, and this was even higher in the refractory DME group. Upon analyzing patient clinical data, the difference in miR-155-5p expression in the AH and plasma was positively associated with disease course, body mass index, fasting blood-glucose, glycated hemoglobin, proteinuria and glycosuria. The expression of miR-155-5p was not significantly different based on hemoglobin, intraocular pressure and sex. The aforementioned results indicate that miR-155-5p might promote the development of DME. To further study the molecular mechanism, human retinal microvascular endothelial cells (HRMECs) were cultured and treated with high glucose in vitro. The results showed that miR-155-5p expression was significantly upregulated in HRMECs induced by high glucose. After inhibiting the expression of miR-155-5p, cell proliferation, angiogenesis and VEGF protein levels were significantly downregulated, whereas miR-155-5p mimics had the opposite effect. In summary, miR-155-5p is closely associated with DME and is a potential target for refractory DME treatment.

Serum exosomal miR-377-3p inhibits retinal pigment epithelium proliferation and offers a biomarker for diabetic macular edema

Objectives

Diabetic macular edema (DME) is a complication of diabetes mellitus that leads to diabetic retinopathy. Thus far, the role of serum exosomal microRNAs (miRNAs) in DME progression remains elusive. This study investigated serum exosomal miRNAs from patients with type 2 diabetes (T2D) and DME to identify miRNAs associated with expression of vascular endothelial growth factor (VEGF), a pivotal component in DME progression; it also evaluated the diagnostic values of these miRNAs for DME.

Methods

Serum was collected from patients with T2D who did (n = 20) and did not have DME (n = 24). Exosomes were isolated from serum and subjected to real-time polymerase chain reaction, western blotting, luciferase reporter, and miRNA profiling analyses.

Results

VEGF was significantly upregulated in ARPE-19 cells treated with exosomes from patients with T2D and DME, compared with exosomes from patients with T2D alone. Among the top 10 downregulated miRNAs identified during exosomal miRNA profiling, miR-377-3p inhibited the expression of VEGF. Luciferase reporter assays confirmed that miR-377-3p could directly regulate VEGF expression. Receiver operating characteristic analysis identified serum exosomal miR-377-3p as a potential biomarker for DME.

Conclusion

Serum exosomal miR-377-3p inhibits VEGF expression to suppress retinal pigment epithelium proliferation and offers a diagnostic biomarker for DME.

miR-98 Regulates TMPRSS2 Expression in Human Endothelial Cells: Key Implications for COVID-19

The two main co-factors needed by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to enter human cells are angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). Here, we focused on the study of microRNAs that specifically target TMPRSS2. Through a bioinformatic approach, we identified miR-98-5p as a suitable candidate. Since we and others have shown that endothelial cells play a pivotal role in the pathogenesis of the coronavirus disease 2019 (COVID-19), we mechanistically validated miR-98-5p as a regulator of TMPRSS2 transcription in two different human endothelial cell types, derived from the lung and from the umbilical vein. Taken together, our findings indicate that TMPRSS2 represents a valid target in COVID-19 treatment, which may be achieved by specific non-coding-RNA approaches.