MicroRNA Expression in Pseudoexfoliation Syndrome with the Use of Next-Generation Sequencing

The identification of biomarkers for Alzheimer's disease using a systems biology approach based on lncRNA-circRNA-miRNA-mRNA ceRNA networks

In addition to being the most prevalent form of neurodegeneration among the elderly, AD is a devastating multifactorial disease. Currently, treatments address only its symptoms. Several clinical studies have shown that the disease begins to manifest decades before the first symptoms appear, indicating that studying early changes is crucial to improving early diagnosis and discovering novel treatments. Our study used bioinformatics and systems biology to identify biomarkers in AD that could be used for diagnosis and prognosis. The procedure was performed on data from the GEO database, and GO and KEGG enrichment analysis were performed. Then, we set up a network of interactions between proteins. Several miRNA prediction tools including miRDB, miRWalk, and TargetScan were used. The ceRNA network led to the identification of eight mRNAs, four circRNAs, seven miRNAs, and seven lncRNAs. Multiple mechanisms, including the cell cycle and DNA replication, have been linked to the promotion of AD development by the ceRNA network. By using the ceRNA network, it should be possible to extract prospective biomarkers and therapeutic targets for the treatment of AD. It is possible that the processes involved in DNA cell cycle and the replication of DNA contribute to the development of Alzheimer's disease.

Exfoliation syndrome and exfoliation glaucoma: Current perspectives and clinical paradigms

Exfoliation syndrome and exfoliation glaucoma comprise a unique age-related ocular aggregopathy characterized by the accumulation of protein complex aggregates in different ocular structures. Recent literature and studies have expanded our knowledge of the clinical characteristic features, phenotypical variations, and molecular pathophysiology associated with disease onset or development of glaucoma. Despite years of studies on the various epidemiological, clinical, and molecular facets of the disease, the exact mechanism of disease onset, formation of aggregates, and the events that trigger the development of glaucoma marking irreversibility in the disease remains elusive. This review elaborates on the existing and new insights that we have gained over the years and highlights gaps in the knowledge about the disease that need future exploration.

Risk factors for exfoliation glaucoma - Current evidence and perspectives

Exfoliation syndrome (XFS) and exfoliation glaucoma (XFG) represent a complex matrix of ocular age-related neurodegenerative changes. Numerous decades of research on this disease entity have highlighted the unique clinical features of ocular protein-complex aggregates, which lead to tissue dysfunction of the ocular outflow channels, leading to irreversible optic nerve damage and glaucoma. While genetic studies have reported several genes associated with XFS and XFG, numerous studies have shown their association with common systemic diseases such as ischemic heart disease, cerebrovascular accidents, and hypertension. Environmental factors are also reported to play a role in the disease pathogenesis by epigenetic control of gene expression and partly explain the difference in the prevalence rates of the disease process. Despite the identification of possible triggers for the disease onset or for the development of glaucoma, the exact mechanisms or the role of several reported risk factors in disease pathogenesis remain a mystery. This review comprehensively evaluated the several risk factors in XFS and XFG while discussing the interactive interplay between the risk factors that determine the disease onset or phenotype in XFS and XFG.

Current understanding of genetics and epigenetics in pseudoexfoliation syndrome and glaucoma

Pseudoexfoliation is a complex, progressive, and systemic age-related disorder. The early stage of deposition of extracellular fibrillar material on ocular and extraocular tissues is termed as pseudoexfoliation syndrome (PEXS). The severe advanced stage is known as pseudoexfoliation glaucoma (PEXG), which involves increased intraocular pressure and optic nerve damage. Through genome-wide association and candidate gene studies, PEX has been associated with numerous genetic risk variants in various gene loci. However, the genetic basis of the disease fails to explain certain features of PEX pathology, such as the progressive nature of the disease, asymmetric ocular manifestation, age-related onset, and only a subset of PEXS individuals developing PEXG. Increasing evidence shows an interplay of genetic and epigenetic factors in the pathology of complex, multifactorial diseases. In this review, we have discussed the genetic basis of the disease and the emerging contribution of epigenetic regulations in PEX pathogenesis, focusing on DNA methylation and non-coding RNAs. Aberrant methylation patterns, histone modifications, and post-transcriptional regulation by microRNAs lead to aberrant gene expression changes. We have reviewed these aberrant epigenetic changes in PEX pathology and their effect on molecular pathways associated with PEX. We have further discussed some possible genetic/epigenetic-based diagnoses and therapeutics for PEX. Although studies to understand the role of epigenetic regulations in PEX are just emerging, epigenetic modifications contribute significantly to PEX pathogenesis and may pave the way for better and targeted therapeutics.

Evaluation of expression pattern of cellular miRNAs (let-7b, miR-29a, miR-126, miR-34a, miR-181a-5p) and IL-6, TNF-α, and TGF-β in patients with pseudoexfoliation syndrome

Pseudoexfoliation syndrome (PEX) is a critical clinical and biological extracellular matrix systemic disorder. Despite the unknown nature of PEX etiopathogenesis, it is proven to be associated with various genes and factors. The present research focused on analyzing the expression of miR and inflammatory cytokines in PEX. Serum and aqueous humor (AH) were collected prior to cataract surgery or trabeculectomy from 99 participants (64 with PEX glaucoma, and 35 controls). Real-time PCR was used for assessing the expression pattern of some miRNAs namely let-7b, miR-29a, miR-126, miR-34a, and miR-181a-5p. ELISA was carried out to explore the transcription of some inflammatory cytokines such as TGF-β, TNF-α, and IL-6. The indication of our results was a significant enhancement in the expression of let-7, miR-34a, and miR-181a-5p in PEX in contrast to the control group. Notwithstanding a significant suppression in miR-29a, and miR-126 expression levels in PEX in contrast to the control group. Analysis of ROC curve revealed that miR-29a and miR-34a are able to act as useful markers in order to discriminate the PEX group from the PEX negative subjects which were determined as the control group. According to the results obtained, the mean levels of TGF-β, TNF-α, and IL-6 upregulated among PEX subjects in contrast to control samples. In conclusion, our findings indicated that the selected cytokines alongside the selected miRNAs could be introduced as a biomarker panel in the diagnosis of PEX.

Twenty Novel MicroRNAs in the Aqueous Humor of Pseudoexfoliation Glaucoma Patients

The microRNAs (miRNAs) are short non-coding RNAs (19-25 nt) that regulate the level of gene expression at the post-transcriptional stage. Altered miRNAs expression can lead to the development of various diseases, e.g., pseudoexfoliation glaucoma (PEXG). In this study, we assessed the levels of miRNA expression in the aqueous humor of PEXG patients using the expression microarray method. Twenty new miRNA molecules have been selected as having the potential to be associated with the development or progression of PEXG. Ten miRNAs were downregulated in PEXG (hsa-miR-95-5p, hsa-miR-515-3p, hsa-mir-802, hsa-miR-1205, hsa-miR-3660, hsa-mir-3683, hsa -mir-3936, hsa-miR-4774-5p, hsa-miR-6509-3p, hsa-miR-7843-3p) and ten miRNAs were upregulated in PEXG (hsa-miR-202 -3p, hsa-miR-3622a-3p, hsa-mir-4329, hsa-miR-4524a-3p, hsa-miR-4655-5p, hsa-mir-6071, hsa-mir-6723-5p, hsa-miR-6847-5p, hsa-miR-8074, and hsa-miR-8083). Functional analysis and enrichment analysis showed that the mechanisms that can be regulated by these miRNAs are: extracellular matrix (ECM) imbalance, cell apoptosis (possibly retinal ganglion cells (RGCs)), autophagy, and elevated calcium cation levels. Nevertheless, the exact molecular basis of PEXG is unknown and further research is required on this topic.

Antioxidant Defense and Pseudoexfoliation Syndrome: An Updated Review

Oxidative stress (OS) affects the anterior ocular tissues, rendering them susceptible to several eye diseases. On the other hand, protection of the eye from harmful factors is achieved by unique defense mechanisms, including enzymatic and non-enzymatic antioxidants. The imbalance between oxidants and antioxidants could be the cause of pseudoexfoliation syndrome (PEXS), a condition of defective extracellular matrix (ECM) remodeling. A systematic English-language literature review was conducted from May 2022 to June 2022. The main antioxidant enzymes protecting the eye from reactive oxygen species (ROS) are superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), which catalyze the reduction of specific types of ROS. Similarly, non-enzymatic antioxidants such as vitamins A, E and C, carotenoids and glutathione (GSH) are involved in removing ROS from the cells. PEXS is a genetic disease, however, environmental and dietary factors also influence its development. Additionally, many OS products disrupting the ECM remodeling process and modifying the antioxidative defense status could lead to PEXS. This review discusses the antioxidative defense of the eye in association with PEXS, and the intricate link between OS and PEXS. Understanding the pathways of PEXS evolution, and developing new methods to reduce OS, are crucial to control and treat this disease. However, further studies are required to elucidate the molecular pathogenesis of PEXS.

A review on the role of miR-671 in human disorders

miR-671 is encoded by a gene on 7q36.1 and contributes to the pathogenesis of a variety of disorders, including diverse types of cancers, atherosclerosis, ischemic stroke, liver fibrosis, osteoarthritis, Parkinson's disease, rheumatoid arthritis, acute myocardial infarction and Crohn's disease. In the context of cancer, different studies have revealed opposite roles for this miRNA. In brief, it has been shown to be down-regulated in pancreatic ductal carcinoma, ovarian cancer, gastric cancer, osteosarcoma, esophageal squamous cell carcinoma and myelodysplastic syndromes. Yet, miR-671 has been up-regulated in glioma, colorectal cancer, prostate cancer and hepatocellular carcinoma. Studies in breast, lung and renal cell carcinoma have reported inconsistent results. The current review aims at summarization of the role of miR-671 in these disorders focusing on its target mRNA in each context and dysregulated signaling pathways. We also provide a summary of the role of this miRNA as a prognostic factor in malignancies.

The Importance of MicroRNA Expression in Pseudoexfoliation Syndrome

Pseudoexfoliation syndrome (PEX) is an important systemic disorder of the extracellular matrix, in which granular amyloid-like protein fibers accumulate in the anterior segment of the eyeball as well as in other organs. PEX is currently considered to be a multifactorial systemic disorder with genetic and environmental risk factors. The aim of this manuscript was to analyze miR expression in PEX. In recent years, an attempt has been made to investigate and describe the level of expression of selected miRs in PEX. Four polymorphisms of genes isolated from the blood that may be related to PEX were identified and miR-122-5p was found to be upregulated in patient blood. Furthermore, 18 miRs were identified with a statistically different expression in the aqueous humor. A significantly elevated expression of miR-125b was found in the anterior lens capsule, and four miRs were described, which may have a significant impact on the development of PEX. Regulatory miR molecules are gaining more and more importance in research aimed at identifying and isolating molecular markers related to the pathogenesis and prognosis of PEX, but further studies are needed.