Exosomes Released by Corneal Stromal Cells Show Molecular Alterations in Keratoconus Patients and Induce Different Cellular Behavior

Phosphoglycerate mutase and methionine synthase act as adhesins of Candida albicans to the corneal epithelium, altering their expression during the tissue adhesion process

The yeast form of Candida albicans uses glycosaminoglycans (GAGs), primarily heparan sulfate, as adhesion receptors for corneal epithelial cells. However, during the transition to the hyphal form, the fungus shifts to using alternative receptors. This study aims to identify fungal adhesins involved in GAG binding and examine their expression dynamics during tissue adhesion. Using chromatography, three proteins from the C. albicans cell wall with high affinity for heparin were identified: methionine synthase, phosphoglycerate mutase, and cytochrome c. These proteins were overexpressed in Escherichia coli and tested in adhesion assays. Methionine synthase and phosphoglycerate mutase partially inhibited yeast adhesion to corneal epithelial cells in a concentration-dependent manner, while cytochrome c enhanced adhesion. Transcriptional analysis of the genes encoding these proteins (MET6, GMP1, and CYC1), along with other genes related to adhesion and yeast-to-hypha transition (ALS3, HWP1, and INT1), revealed that exposure to exosomes or GAGs increased GMP1, CYC1, and ALS3 expression, while reducing HWP1 and INT1. In contrast, direct contact with epithelial cells decreased MET6 and GMP1 expression, but increased HWP1 expression. These results suggest that methionine synthase and phosphoglycerate mutase act as adhesins for GAGs, with their expression modulated by GAG or exosome interaction to promote adhesion. However, epithelial cell contact alters the expression of adhesins and molecules linked to hyphal formation, highlighting their dynamic role in corneal adhesion.

Application of stem cell-derived exosomes in anterior segment eye diseases: A comprehensive update review

Mesenchymal stem cell (MSC) therapy has emerged as a promising approach for addressing various eye-related conditions. Yet, its clinical application faces challenges due to issues such as limited biocompatibility and difficulties in effectively delivering treatment to specific ocular tissues. Recent studies have shifted attention towards MSC-derived exosomes, which share similar regenerative, reparative, and immunomodulatory capabilities with their origin cells. This review delves into the latest research on the use of MSC-derived exosomes for treating anterior segment diseases of the eye. It explores the exosomes' composition, biological functions, and the methods used for their isolation, as well as their roles in disease progression, diagnosis, and therapy. The review critically assesses the therapeutic advantages and mechanisms of action of MSC-derived exosomes in treating conditions like dry eye disease, Sjogren's syndrome, keratoconus, corneal lesions, and corneal allograft rejection. Additionally, it discusses the obstacles and future prospects of employing MSC-derived exosomes as innovative therapies for anterior segment eye diseases. This comprehensive overview underscores the significant potential of MSC-derived exosomes in transforming the treatment paradigm for anterior segment eye disorders, while also highlighting the necessity for further research to enhance their clinical application.

Silver Nanoparticles: A Versatile Tool Against Infectious and Non-Infectious Diseases

Silver nanoparticles possess remarkable properties that render them highly beneficial for medical applications in both infectious and non-infectious diseases. Among their most renowned attributes is their antimicrobial activity. They have demonstrated efficacy against a wide range of bacteria, fungi, protozoa, and viruses. Additionally, the antitumor and anti-diabetic properties of silver nanoparticles, along with their ability to promote wound healing and their application as biosensors, underscore their therapeutic potential for various non-infectious conditions. As silver nanoparticles are employed for medical purposes, their potential toxicity must be considered. While silver nanoparticles present a promising alternative in the therapeutic domain, further research is needed to elucidate their precise mechanisms of action, optimize their efficacy, and mitigate any potential health risks associated with their use.

Corneal stromal cells from patients with keratoconus exhibit alterations in the ESCRT-dependent machinery responsible for multivesicular body formation

Previous studies have reported that exosomes produced by corneal stromal cells from keratoconus patients exhibit a molecular content distinct from those produced by cells from healthy donors. This study investigates differences in the expression of ESCRT components, regarded as the most critical mechanism in exosome biogenesis. The study included analysis of transcription levels of system-encoding genes using qRT-PCR reactions, as well as semiquantitative protein determination through immunocytochemistry. Of the 34 molecules analyzed, mRNA downregulation was observed in 8 in pathological cells. In keratoconus, genes encoding STAM2 from the ESCRT-0 complex and VPS37A, VPS37C, VPS37D and UBAP1 from the ESCRT-I complex were found to be underexpressed, although VPS37D could not be confirmed at the protein level. Additionally, two other expression alterations affected the ESCRT-III complex, involving the core protein CHMP4C and the regulatory protein CHMP1B. Finally, deregulation of the ubiquitin-specific peptidase UBPY was observed. Most changes identified in this study affected specific isoforms, which could suggest functional diversification and differences in cargo recognition in the context of pathology. Altogether, these findings suggest that the previously reported alteration in the molecular content of exosomes produced by stromal cells in keratoconus may be, at least partially, due to disruptions in the exosome synthesis machinery.

Exosomes in Ocular Health: Recent Insights into Pathology, Diagnostic Applications and Therapeutic Functions

Exosomes are extracellular vesicles ranging from 30 to 150 nm in diameter that contain proteins, nucleic acids and other molecules. Produced by virtually all cell types, they travel throughout the body until they reach their target, where they can trigger a wide variety of effects by transferring the molecular cargo to recipient cells. In the context of ocular physiology, exosomes play a very important role in embryological development, the regulation of homeostasis and the immune system, which is crucial for normal vision. Consequently, in pathological situations, exosomes also undergo modifications in terms of quantity, composition and content, depending on the etiology of the disease. However, the mechanisms by which exosomes contribute to ocular pathology has not yet been studied in depth, and many questions remain unanswered. This review aims to summarize the most recent knowledge on the function of exosomes in the ocular system in healthy individuals and the role they play during pathological processes of a degenerative, infectious, neurodegenerative, vascular and inflammatory nature, such as keratoconus, keratitis, glaucoma, diabetic retinopathy and uveitis. Furthermore, given their unique characteristics, their potential as diagnostic biomarkers or therapeutic agents and their application in clinical ophthalmology are also explored, along with the main limitations that researchers face today in the field.

Challenging corneal diseases and microRNA expression: Focus on rare diseases and new therapeutic frontiers

MicroRNAs (miRNAs) function as posttranscriptional regulators of gene expression by targeting specific messenger RNA (mRNA). This interaction modulates mRNA stability or translational efficiency, ultimately impacting the level of protein production. Emerging evidence suggests that miRNAs act as critical regulators in corneal diseases. These molecules finetune key processes like cell proliferation, differentiation, inflammation, and wound healing. We reviewed the literature to understand the role that miRNAs may play in the development of challenging and poorly understood corneal diseases. We focused on vernal keratoconjunctivitis, neurotrophic keratitis, keratoconus, Fuchs endothelial corneal dystrophy, and limbal stem cell deficiency. Furthermore, we explored currently studied agonists or antagonists of miRNAs that share similar pathways with ocular diseases and could be employed in ophthalmology in the future. The distinct miRNA expression profiles observed in different ocular surface pathologies, combined with the remarkable stability and relatively easy access of miRNA sampling in biofluids, present possibilities for the development of noninvasive and highly accurate diagnostic tools. Furthermore, comprehending miRNA's pathophysiological role could open new frontiers to a more comprehensive understanding of the pathophysiology underlying ocular surface diseases, thereby paving the way for the creation of novel therapeutic strategies.

Interleukin-1β-stimulated macrophage-derived exosomes improve myocardial injury in sepsis via regulation of mitochondrial homeostasis: experimental research

BACKGROUND

The purpose of this study was to investigate the effects of interleukin-1β (IL-1β) stimulation on the protection of macrophage-derived exosomes miR-146a (M-IL-exo-146a) on sepsis-induced myocardial injury (SMI) in vitro and in vivo .

MATERIALS AND METHODS

Macrophage-derived exosomes (M-exo) and IL-1β-stimulated macrophage exosomes (M-IL-exo) were isolated from macrophages of sepsis with or without IL-1β. The expressions of miR-146a in M-exo and M-IL-exo were detected by fluorescence quantitative PCR. Related molecular biology technologies were used to evaluate the role and mechanism of M-exo-146a and M-IL-exo-146a on SMI and the enhancing effect of IL-1β.

RESULTS

Compared with M-exo, the expression of miR-146a in M-IL-exo was significantly increased. M-IL-exo-146a significantly alleviated SMI by decreasing the level of serum myocardial enzymes, serum and myocardial oxidative stress and cytokines, and improved myocardial mitochondrial imbalance. The mechanism responsible for IL-1β enhancing the production of IL-M-exo miR-146a was via JNK-1/2 signal pathway. The mechanism responsible for M-exo-IL-miR-146a protecting SMI was related to miR-146a inhibiting inflammatory response and mitochondrial function via MAPK4/Drp-1 signal pathway.

CONCLUSIONS

This study provides a new strategy for the treatment of SMI by delivering M-IL-exo.

Target specification and therapeutic potential of extracellular vesicles for regulating corneal angiogenesis, lymphangiogenesis, and nerve repair

Extracellular vesicles, including exosomes, are small extracellular vesicles that range in size from 30 nm to 10 μm in diameter and have specific membrane markers. They are naturally secreted and are present in various bodily fluids, including blood, urine, and saliva, and through the variety of their internal cargo, they contribute to both normal physiological and pathological processes. These processes include immune modulation, neuronal synapse formation, cell differentiation, cancer metastasis, angiogenesis, lymphangiogenesis, progression of infectious disease, and neurodegenerative disorders like Alzheimer's and Parkinson's disease. In recent years, interest has grown in the use of exosomes as a potential drug delivery system for various diseases and injuries. Importantly, exosomes originating from a patient's own cells exhibit minimal immunogenicity and possess remarkable stability along with inherent and adjustable targeting capabilities. This review explores the roles of exosomes in angiogenesis, lymphangiogenesis, and nerve repair with a specific emphasis on these processes within the cornea. Furthermore, it examines exosomes derived from specific cell types, discusses the advantages of exosome-based therapies in modulating these processes, and presents some of the most established methods for exosome isolation. Exosome-based treatments are emerging as potential minimally invasive and non-immunogenic therapies that modulate corneal angiogenesis and lymphangiogenesis, as well as enhance and accelerate endogenous corneal nerve repair.

Comprehensive Evaluation of the Genetic Basis of Keratoconus: New Perspectives for Clinical Translation

Purpose

Keratoconus (KC) is a corneal disorder with complex etiology, apparently involving both genetic and environmental factors, characterized by progressive thinning and protrusion of the cornea. We aimed to identify novel genetic regions associated with KC susceptibility, elucidate relevant genes for disease development, and explore the translational implications for therapeutic intervention and risk assessment.

Methods

We conducted a genome-wide association study (GWAS) that integrated previously published data with newly generated genotyping data from an independent European cohort. To evaluate the clinical translation of our results, we performed functional annotation, gene prioritization, polygenic risk score (PRS), and drug repositioning analyses.

Results

We identified two novel genetic loci associated with KC, with rs2806689 and rs807037 emerging as lead variants (P = 1.71E-08, odds ratio [OR] = 0.88; P = 1.93E-08, OR = 1.16, respectively). Most importantly, we identified 315 candidate genes influenced by confirmed KC-associated variants. Among these, MINK1 was found to play a pivotal role in KC pathogenesis through the WNT signaling pathway. Moreover, we developed a PRS model that successfully differentiated KC patients from controls (P = 7.61E-16; area under the curve = 0.713). This model has the potential to identify individuals at high risk for developing KC, which could be instrumental in early diagnosis and management. Additionally, our drug repositioning analysis identified acetylcysteine as a potential treatment option for KC, opening up new avenues for therapeutic intervention.

Conclusions

Our study provides valuable insights into the genetic and molecular basis of KC, offering new targets for therapy and highlighting the clinical utility of PRS models in predicting disease risk.

Identification of Keratoconus-Related Phenotypes in Three Ppip5k2 Mouse Models

Purpose

It is necessary to establish a mouse model of keratoconus (KC) for research and therapy. We aimed to determine corneal phenotypes in 3 Ppip5k2 mouse models.

Methods

Central corneal thickness (CCT) was determined using spectral domain optical coherence tomography (SD-OCT) in Ppip5k2+/K^ (n = 41 eyes), Ppip5k2K^/K^ (n = 17 eyes) and 2 knock-in mice, Ppip5k2S419A/+ (n = 54 eyes) and Ppip5k2S419A/S419A (n = 18 eyes), and Ppip5k2D843S/+ (n = 42 eyes) and Ppip5k2D843S/D843S (n = 44 eyes) at 3 and 6 months. Pachymetry maps were generated using the Mouse Corneal Analysis Program (MCAP) to process OCT images. Slit lamp biomicroscopy was used to determine any corneal abnormalities, and, last, hematoxylin and eosin (H&E) staining using corneal sections from these animals was used to examine morphological changes.

Results

CCT significantly decreased from 3 to 6 months in the Ppip5k2+/K^ and Ppip5k2K^/K^ mice compared to their littermate controls. OCT-based pachymetry maps revealed abnormally localized thinning in all three models compared to their wild-type (WT) controls. Slit lamp examinations revealed corneal abnormalities in the form of bullous keratopathy, stromal edema, stromal scarring, deep corneal neovascularization, and opacities in the heterozygous/homozygous mice of the three models in comparison with their controls. Corneal histological abnormalities, such as epithelial thickening and stromal layer damage, were observed in the heterozygous/homozygous mice of the three models in comparison with the WT controls.

Conclusions

We have identified phenotypic and histological changes in the corneas of three mouse lines that could be relevant in the development of animal models of KC.

Exosomal microRNAs as potential biomarkers and therapeutic targets in corneal diseases

Exosomes are a subtype of extracellular vesicle (EV) that are released and found in almost all body fluids. Exosomes consist of and carry a variety of bioactive molecules, including genetic information in the form of microRNAs (miRNAs). miRNA, a type of small non-coding RNA, plays a key role in regulating genes by suppressing their translation. miRNAs are often disrupted in the pathophysiology of different conditions, including eye disease. The stability and easy detectability of exosomal miRNAs in body fluids make them promising biomarkers for the diagnosis of different diseases. Additionally, due to the natural delivery capabilities of exosomes, they can be modified to transport therapeutic miRNAs to specific recipient cells. Most exosome research has primarily focused on cancer, so there is limited research highlighting the importance of exosomes in ocular biology, particularly in cornea-associated pathologies. This review provides an overview of the existing evidence regarding the primary functions of exosomal miRNAs and their potential role in diagnostic and therapeutic applications in the human cornea.

The Binding of Pseudomonas aeruginosa to Cystic Fibrosis Bronchial Epithelial Model Cells Alters the Composition of the Exosomes They Produce Compared to Healthy Control Cells

Cystic fibrosis (CF) is a genetic disease that causes dehydration of the surface of the airways, increasing lung infections, most frequently caused by Pseudomonas aeruginosa. Exosomes are nanovesicles released by cells that play an essential role in intercellular communication, although their role during bacterial infections is not well understood. In this article, we analyze the alterations in exosomes produced by healthy bronchial epithelial and cystic fibrosis cell lines caused by the interaction with P. aeruginosa. The proteomic study detected alterations in 30% of the species analyzed. In healthy cells, they mainly involve proteins related to the extracellular matrix, cytoskeleton, and various catabolic enzymes. In CF, proteins related to the cytoskeleton and matrix, in addition to the proteasome. These differences could be related to the inflammatory response. A study of miRNAs detected alterations in 18% of the species analyzed. The prediction of their potential biological targets identified 7149 genes, regulated by up to 7 different miRNAs. The identification of their functions showed that they preferentially affected molecules involved in binding and catalytic activities, although with differences between cell types. In conclusion, this study shows differences in exosomes between CF and healthy cells that could be involved in the response to infection.

Animal Models for the Study of Keratoconus

Keratoconus (KC) is characterized by localized, central thinning and cone-like protrusion of the cornea. Its precise etiology remains undetermined, although both genetic and environmental factors are known to contribute to disease susceptibility. Due to KC's complex nature, there is currently no ideal animal model to represent both the corneal phenotype and underlying pathophysiology. Attempts to establish a KC model have involved mice, rats, and rabbits, with some additional novel animals suggested. Genetic animal models have only been attempted in mice. Similarly, spontaneously occurring animal models for KC have only been discovered in mice. Models generated using chemical or environmental treatments have been attempted in mice, rats, and rabbits. Among several methods used to induce KC in animals, ultraviolet radiation exposure and treatment with collagenase are some of the most prevalent. There is a clear need for an experimental model animal to elucidate the underlying mechanisms behind the development and progression of keratoconus. An appropriate animal model could also aid in the development of treatments to slow or arrest the disorder.

Exosomes and their miRNA/protein profile in keratoconus-derived corneal stromal cells

Keratoconus (KC) is a corneal thinning disorder and a leading cause of corneal transplantation worldwide. Exosomes are small, secreted extracellular vesicles (30-150 nm) that mediate cellular communication via their protein, lipid, and nucleic acid content. We aimed to characterize the exosomes secreted by primary corneal fibroblasts from subjects with or without KC. Using human keratoconus stromal fibroblast cells (HKC, n = 4) and healthy stromal fibroblasts (HCF, n = 4), we collected and isolated exosomes using serial ultracentrifugation. Using nanoparticle tracking analysis (NTA) with ZetaView®, we compared the size and concentration of isolated exosomes. Different exosomal markers were identified and quantified using a transmission electron microscope (TEM) (CD81) and Western blot (CD9 and CD63). Exosomal miRNA profiles were determined by qRT-PCR using Exiqon Human panel I miRNA assays of 368 pre-selected miRNAs. Proteomic profiles were determined using a label-free spectral counting method with mass spectrometry. Differential expression analysis for miRNAs and proteins was done using student's t-test with a significance cutoff of p-value ≤0.05. We successfully characterized exosomes isolated from HCFs using several complementary techniques. We found no significant differences in the size, quantity, or morphology between exosomes secreted by HCFs with or without KC. Expression of CD81 was confirmed by immuno-EM, and expression of CD63 and CD9 with western blots in all exosome samples. We detected the expression of 72-144 miRNAs (threshold cycle Ct < 36) in all exosome samples. In HKC-derived exosome samples, miR-328-3p, miR-532-5p, miR-345-5p, and miR-424-5p showed unique expression, while let-7c-5p and miR-665 have increased expression. Protein profiling identified 157 proteins in at least half of the exosome samples, with 38 known exosomal proteins. We identified 12 up- and 2 down-regulated proteins in HKC-derived exosomes. The proteins are involved in membrane-bounded vesicles, cytoskeletal, calcium binding, and nucleotide binding. These proteins are predicted to be regulated by NRF2, miR-205, and TGF-β1, which are involved in KC pathogenesis. We successfully characterized the HKC-derived exosomes and profiled their miRNA and protein contents, suggesting their potential role in KC development. Further studies are necessary to determine if and how these exosomes with differential protein/miRNA profiles contribute to the pathogenesis of KC.

Bioinformatics analysis of key candidate genes and pathways in Chinese patients with keratoconus

Keratoconus (KC) is a multifactorial disease in which genetic factors played important roles in its pathogenesis. The purpose of the current study was to identify the key candidate genes and pathways in Chinese patients with KC through bioinformatics analysis. Totally, we identified 71 candidate genes by analyzing the results of whole exome sequencing on 51 Chinese patients with KC, combining with previous reports on differential expression at transcription and protein levels in KC. Gene enrichment analysis with GeneCodis demonstrated that two significantly enriched terms including 21 genes in biological process (BP) were detected, and six significantly enriched terms containing 14 genes in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were discovered. The STRING was utilized to construct the protein-protein interaction (PPI) network of identified genes. The result showed that a PPI network consisted of 14 nodes with 14 edges was constructed, and two gene modules were obtained. Eight hub genes (LAMB3, LAMA3, LAMA1, ITGA6, ITGA3, COL6A3, COL6A2, and COL6A1) were identified as key candidate genes for KC by cytoHubba in Cytoscape. Functional enrichment analysis with ClueGO and CluePedia indicated that the ECM-receptor interaction was the key pathway accounted for KC. The findings might provide novel insights on the genetic basis of KC.

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.