MicroRNA-24 protects retina from degeneration in rats by down-regulating chitinase-3-like protein 1

Compounding engineered mesenchymal stem cell-derived exosomes: A potential rescue strategy for retinal degeneration

The prevalence of retinal degenerative diseases, including age-related macular degeneration and retinitis pigmentosa, has been increasing globally and is linked to the aging population and improved life expectancy. These diseases are characterized by chronic, progressive neuronal damage or depletion of the photoreceptor cells in the retina, and limited effective treatment options are currently available. Mesenchymal stem cell-derived exosomes (MSC-EXOs) containing cytokines, growth factors, lipids, mRNA, and miRNA, which act as mediators of intercellular communication transferring bioactive molecules to recipient cells, offer an appealing, non-cellular nanotherapeutic approach for retinal degenerative diseases. However, treatment specificity is compromised due to their high heterogeneity in size, content, functional effects, and parental cellular source. To improve this, engineered MSC-EXOs with increased drug-loading capacity, targeting ability, and resistance to bodily degradation and elimination have been developed. This review summarizes the recent advances in miRNAs of MSC-EXOs as a treatment for retinal degeneration, discussing the strategies and methods for engineering therapeutic MSC-EXOs. Notably, to address the single functional role of engineered MSC-EXOs, we propose a novel concept called "Compound Engineered MSC-EXOs (Co-E-MSC-EXOs)" along with its derived potential therapeutic approaches. The advantages and challenges of employing Co-E-MSC-EXOs for retinal degeneration in clinical applications, as well as the strategies and issues related to them, are also highlighted.

Integrative genomics important to understand host-pathogen interactions

Infectious diseases are the leading cause of morbidity and mortality worldwide. Causative pathogenic microbes readily mutate their genome and lead to outbreaks, challenging the healthcare and the medical support. Understanding how certain symptoms manifest clinically is integral for therapeutic decisions and vaccination efficacy/protection. Notably, the interaction between infecting pathogens, host response and co-presence of microbes influence the trajectories of disease progression and clinical outcome. The spectrum of observed symptomatic patients (mild, moderate and severe) and the asymptomatic infections highlight the challenges and the potential for understanding the factors driving protection/susceptibility. With the increasing repertoire of high-throughput tools, such as cutting-edge multi-omics profiling and next-generation sequencing, genetic drivers of factors linked to heterogeneous disease presentations can be investigated in tandem. However, such strategies are not without limits in terms of effectively integrating host-pathogen interactions. Nonetheless, an integrative genomics method (for example, RNA sequencing data) for exploring multiple layers of complexity in host-pathogen interactions could be another way to incorporate findings from high-throughput data. We further propose that a Holo-transcriptome-based technique to capture transcriptionally active microbial units can be used to elucidate functional microbiomes. Thus, we provide holistic perspective on investigative methodologies that can harness the same genomic data to investigate multiple seemingly independent but deeply interconnected functional domains of host-pathogen interaction that modulate disease severity and clinical outcomes.

Essential Role of Multi-Omics Approaches in the Study of Retinal Vascular Diseases

Retinal vascular disease is a highly prevalent vision-threatening ocular disease in the global population; however, its exact mechanism remains unclear. The expansion of omics technologies has revolutionized a new medical research methodology that combines multiple omics data derived from the same patients to generate multi-dimensional and multi-evidence-supported holistic inferences, providing unprecedented opportunities to elucidate the information flow of complex multi-factorial diseases. In this review, we summarize the applications of multi-omics technology to further elucidate the pathogenesis and complex molecular mechanisms underlying retinal vascular diseases. Moreover, we proposed multi-omics-based biomarker and therapeutic strategy discovery methodologies to optimize clinical and basic medicinal research approaches to retinal vascular diseases. Finally, the opportunities, current challenges, and future prospects of multi-omics analyses in retinal vascular disease studies are discussed in detail.

Genetics behind Cerebral Disease with Ocular Comorbidity: Finding Parallels between the Brain and Eye Molecular Pathology

Cerebral visual impairments (CVIs) is an umbrella term that categorizes miscellaneous visual defects with parallel genetic brain disorders. While the manifestations of CVIs are diverse and ambiguous, molecular diagnostics stand out as a powerful approach for understanding pathomechanisms in CVIs. Nevertheless, the characterization of CVI disease cohorts has been fragmented and lacks integration. By revisiting the genome-wide and phenome-wide association studies (GWAS and PheWAS), we clustered a handful of renowned CVIs into five ontology groups, namely ciliopathies (Joubert syndrome, Bardet–Biedl syndrome, Alstrom syndrome), demyelination diseases (multiple sclerosis, Alexander disease, Pelizaeus–Merzbacher disease), transcriptional deregulation diseases (Mowat–Wilson disease, Pitt–Hopkins disease, Rett syndrome, Cockayne syndrome, X-linked alpha-thalassaemia mental retardation), compromised peroxisome disorders (Zellweger spectrum disorder, Refsum disease), and channelopathies (neuromyelitis optica spectrum disorder), and reviewed several mutation hotspots currently found to be associated with the CVIs. Moreover, we discussed the common manifestations in the brain and the eye, and collated animal study findings to discuss plausible gene editing strategies for future CVI correction.

The Role of Dysregulated miRNAs in the Pathogenesis, Diagnosis and Treatment of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is an eye disease causing damage to the macular region of the retina where most of the photoreceptors responsible for central visual acuity are located. MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules that negatively regulate genes by silent post-transcriptional gene expressions. Previous studies have shown that changes in specific miRNAs are involved in the pathogenesis of eye diseases, including AMD. Altered expressions of miRNAs are related to disturbances of regulating oxidative stress, inflammation, angiogenesis, apoptosis and phagocytosis, which are known factors in the pathogenesis of AMD. Moreover, dysregulation of miRNA is involved in drusen formation. Thus, miRNAs may be used as potential molecular biomarkers for the disease and, furthermore, tailoring therapeutics to particular disturbances in miRNAs may, in the future, offer hope to prevent irreversible vision loss. In this review, we clarify the current state of knowledge about the influence of miRNA on the pathogenesis, diagnosis and treatment of AMD. Our study material consisted of publications, which were found in PubMed, Google Scholar and Embase databases using “Age-related macular degeneration”, “miRNA”, “AMD biomarkers”, “miRNA therapeutics” and “AMD pathogenesis” as keywords. Paper search was limited to articles published from 2011 to date. In the section “Retinal, circulating and vitreous body miRNAs found in human studies”, we limited the search to studies with patients published in 2016–2021.

Mammalian Target of Rapamycin Inhibitor Rapamycin Alleviates 7-Ketocholesterol Induced Inflammatory Responses and Vascular Endothelial Growth Factor Elevation by Regulating MAPK Pathway in Human Retinal Pigment Epithelium Cells

Purpose: To validate the protective effect of a mammalian target of rapamycin (mTOR) inhibitor on human retinal pigment epithelium (RPE) cells challenged with 7-ketocholesterol (7-KC) and explored the underlying mechanisms. Methods: Human primary RPE (hRPE) cells and ARPE-19 cells were cultured with or without 10 nM of rapamycin for 6 h before being exposed to 10 μM of 7-KC for 24 h. The transcriptome of 7-KC challenged ARPE-19 cells was investigated by RNA sequencing (RNA-seq). The effects of 7-KC and rapamycin on the viability of ARPE-19 cells were measured with CCK-8. Gene expression was verified by real-time PCR, and protein levels were determined by ELISA or Western blotting. Results: The expression of IL-6, IL-8, and vascular endothelial growth factor (VEGF) in RPE cells was markedly increased after stimulation with 7-KC for 12/24 h compared with the controls. RNA-seq showed that a total of 10,243 genes were differentially expressed, with 5,518 genes upregulated and 4,725 genes downregulated between the 7-KC treated and the control group. Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that 7-KC stimulation activated mTOR signaling and other pathways, including adherent junction, MAPK, and Wnt signalings. mTOR inhibitor rapamycin significantly suppressed the elevation of IL-6, IL-8, and VEGF stimulated by 7-KC. Rapamycin not only decreased the level of phosphorylated mTOR, P70S6K, 4EBP1 but also inhibited the activation of MAPK pathway. Conclusions: Inhibition of mTOR signaling pathway suppressed the elevation of inflammatory cytokines IL-6, IL-8, and the angiogenic agent VEGF induced by 7-KC. The protective effect of rapamycin was associated with its downregulation on MAPK pathway.

Therapeutic effects of mesenchymal stem cells-derived extracellular vesicles' miRNAs on retinal regeneration: a review

Extracellular vesicles (EVs), which consist of microvesicles and exosomes, are secreted from all cells to transform vital information in the form of lipids, proteins, mRNAs and small RNAs such as microRNAs (miRNAs). Many studies demonstrated that EVs' miRNAs have effects on target cells. Numerous people suffer from the blindness caused by retinal degenerations. The death of retinal neurons is irreversible and creates permanent damage to the retina. In the absence of acceptable cures for retinal degenerative diseases, stem cells and their paracrine agents including EVs have become a promising therapeutic approach. Several studies showed that the therapeutic effects of stem cells are due to the miRNAs of their EVs. Considering the effects of microRNAs in retinal cells development and function and studies which provide the possible roles of mesenchymal stem cells-derived EVs miRNA content on retinal diseases, we focused on the similarities between these two groups of miRNAs that could be helpful for promoting new therapeutic techniques for retinal degenerative diseases.

Subretinal versus intravitreal administration of human CD34+ bone marrow-derived stem cells in a rat model of inherited retinal degeneration

Background

To evaluate whether subretinal or intravitreal injection of human CD34+ bone marrow-derived stem cells (BMSC) can have protective effects on retinal degeneration that may be enhanced by coadministration of exosomes harvested from human bone marrow mesenchymal stem cells (MSCs).

Methods

Human CD34+ cells were harvested from the mononuclear cell fraction of bone marrow using magnetic beads and labeled with EGFP. Exosomes were harvested from cultured human MSCs under hypoxic conditions. Royal College of Surgeons (RCS) 3-weeks-old rats, immunosuppressed with cyclosporine A, received subretinal or intravitreal injection of CD34+ cells (50,000 cells), CD34+ cells with exosomes (50,000 cells+10 µg), exosomes alone (10 µg), or PBS. Retinal function was examined using electroretinography (ERG), and the eyes were harvested for histologic and immunohistochemical analysis.

Results

The b-wave amplitude of ERG at 2 weeks after injection was significantly higher in eyes with subretinal or intravitreal CD34+ BMSC alone or in combination with exosomes when compared to PBS injected eyes or untreated contralateral eyes. At 4 weeks after injection, the ERG signal decreased in all groups but eyes with subretinal CD34+ BMSCs alone or combined with exosomes showed partially preserved ERG signal and preservation of the outer nuclear layer of the retina near the injection site on histology when compared to eyes with PBS injection. Immunohistochemical analysis identified the human cells in the outer retina. Subretinal or intravitreal exosome injection had no effect on retinal degeneration when administered alone or in combination with CD34+ cells.

Conclusions

Both subretinal and intravitreal injection of human CD34+ BMSCs can provide functional rescue of degenerating retina, although the effects were attenuated over time in this rat model. Regional preservation of the outer retina can occur near the subretinal injection site of CD34+ cells. These results suggest that CD34+ cells may have therapeutic potential in retinal degeneration.

Inhibition of miR-665-3p Enhances Autophagy and Alleviates Inflammation in Fusarium solani-Induced Keratitis

Purpose

Accumulated evidence has shown that microRNAs (miRNAs) are closely related with the regulation of autophagy, which plays vital roles in fungal keratitis (FK). Microarray data showed elevated expression of miR-665-3p in mouse corneal tissues after infection with Fusarium solani (F. solani). Here, we investigated the effect of miR-665-3p in regulating autophagy in experimental F. solani keratitis and determined the potential molecular mechanisms involved.

Methods

In this article, we established an in vivo mouse model of FK and an in vitro model of corneal stromal cells by inoculating with F. solani. We divided them into the following six groups: control, chloroquine (CQ), rapamycin (Rapa), miR-665-3p antagomir (ant-665), miR-665-3p agomir (miR-665), and the negative control group (miR-NC). The levels of autophagy were detected by electron microscopy, Western blotting, and immunofluorescence. Then, we used a dual-luciferase reporter assay to determine the binding of miR-665-3p to the autophagy-related gene (ATG)5 3'UTR. Detection of IL-1β protein levels and hematoxylin and eosin (H&E) staining of corneal tissues were used to observe the effect of miR-665-3p on inflammation in FK.

Results

Here, we showed that inhibition of miR-665-3p expression in FK upregulated autophagy and alleviated inflammation. Nevertheless, the opposite results were found by overexpressing miR-665-3p. Additionally, ATG5 was a direct target gene for miR-665-3p.

Conclusions

Together, our data demonstrated that miR-665-3p might be involved in F. solani keratitis of mice by regulating autophagic pathways and inflammation.

Micro-RNAs in the regulation of immune response against SARS CoV-2 and other viral infections

Background

Micro-RNAs (miRNAS) are non-coding, small RNAs that have essential roles in different biological processes through silencing genes, they consist of 18-24 nucleotide length RNA molecules. Recently, miRNAs have been viewed as important modulators of viral infections they can function as suppressors of gene expression by targeting cellular or viral RNAs during infection.

Aim of review

We describe the biological roles and effects of miRNAs on SARS-CoV-2 life-cycle and pathogenicity, and we discuss the modulation of the immune system with micro-RNAs which would serve as a new foundation for the treatment of SARS-CoV-2 and other viral infections.

Key scientific concepts of review

miRNAs are the key players that regulate the expression of the gene in the post-transcriptional phase and have important effects on viral infections, thus are potential targets in the development of novel therapeutics for the treatment of viral infections. Besides, micro-RNAs (miRNAs) modulation of immune-pathogenesis responses to viral infection is one of the most-known indirect effects, which leads to suppressing of the interferon (IFN-α/β) signalling cascade or upregulation of the IFN-α/β production another IFN-stimulated gene (ISGs) that inhibit replication of the virus. These virus-mediated alterations in miRNA levels lead to an environment that might either enhance or inhibit virus replication.

The Impact of miRNAs in Health and Disease of Retinal Pigment Epithelium

MicroRNAs (miRNAs), a class of non-coding RNAs, are essential key players in the control of biological processes in both physiological and pathological conditions. miRNAs play important roles in fine tuning the expression of many genes, which often have roles in common molecular networks. miRNA dysregulation thus renders cells vulnerable to aberrant fluctuations in genes, resulting in degenerative diseases. The retinal pigment epithelium (RPE) is a monolayer of polarized pigmented epithelial cells that resides between the light-sensitive photoreceptors (PR) and the choriocapillaris. The demanding physiological functions of RPE cells require precise gene regulation for the maintenance of retinal homeostasis under stress conditions and the preservation of vision. Thus far, our understanding of how miRNAs function in the homeostasis and maintenance of the RPE has been poorly addressed, and advancing our knowledge is central to harnessing their potential as therapeutic agents to counteract visual impairment. This review focuses on the emerging roles of miRNAs in the function and health of the RPE and on the future exploration of miRNA-based therapeutic approaches to counteract blinding diseases.