Twenty Novel MicroRNAs in the Aqueous Humor of Pseudoexfoliation Glaucoma Patients

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.

miR-277 targets the proapoptotic gene-hid to ameliorate Aβ42-mediated neurodegeneration in Alzheimer's model

Alzheimer's disease (AD), an age-related progressive neurodegenerative disorder, exhibits reduced cognitive function with no cure to date. One of the reasons for AD is the accumulation of Amyloid-beta 42 (Aβ42) plaque(s) that trigger aberrant gene expression and signaling, which results in neuronal cell death by an unknown mechanism(s). Misexpression of human Aβ42 in the developing retina of Drosophila exhibits AD-like neuropathology. Small non-coding RNAs, microRNAs (miRNAs), post-transcriptionally regulate the expression of their target genes and thereby regulate different signaling pathways. In a forward genetic screen, we identified miR-277 (human ortholog is hsa-miR-3660) as a genetic modifier of Aβ42-mediated neurodegeneration. Loss-of-function of miR-277 enhances the Aβ42-mediated neurodegeneration. Whereas gain-of-function of miR-277 in the GMR > Aβ42 background downregulates cell death to maintain the number of neurons and thereby restores the retinal axonal targeting defects indicating the functional rescue. In addition, gain-of-function of miR-277 rescues the eclosion- and climbing assays defects observed in GMR > Aβ42 background. Thus, gain-of-function of miR-277 rescues both structurally as well as functionally the Aβ42-mediated neurodegeneration. Furthermore, we identified head involution defective (hid), an evolutionarily conserved proapoptotic gene, as one of the targets of miR-277 and validated these results using luciferase- and qPCR -assays. In the GMR > Aβ42 background, the gain-of-function of miR-277 results in the reduction of hid transcript levels to one-third of its levels as compared to GMR > Aβ42 background alone. Here, we provide a novel molecular mechanism where miR-277 targets and downregulates proapoptotic gene, hid, transcript levels to rescue Aβ42-mediated neurodegeneration by blocking cell death. These studies shed light on molecular mechanism(s) that mediate cell death response following Aβ42 accumulation seen in neurodegenerative disorders in humans and provide new therapeutic targets for neurodegeneration.

Pseudoexfoliative Syndrome in Cataract Surgery-A Quality Register Study and Health Economic Analysis in the Split-Dalmatia County, Croatia

PURPOSE

To investigate the impact of pseudoexfoliation (PEX) syndrome on intraoperative phacoemulsification (PHACO) parameters and assess the economic cost of PHACO surgery for cataracts in patients with and without PEX syndrome.

METHODS

This was a retrospective quality register study on 5889 patients (6236 eyes) who underwent PHACO cataract surgery in the Eye Clinic, Clinical Hospital Centre Split, Croatia, over a 7-year period (May 2015 to December 2022), in accordance with the Guidelines of the Helsinki Declaration and approval from the Research Ethics Committee of the University Hospital Centre Split, Croatia. Inclusion criteria were patients with either presenile or senile cataract or cataract related to PEX syndrome who undertook PHACO procedure by the same experienced surgeon using the same PHACO device (Infiniti Vision System, Alcon Laboratories, Inc., Fort Worth, TX, USA). Eyes were categorized according to PEX presence- (PEX group) or absence (Group without PEX). The following recorded data about intraoperative PHACO parameters were collected: Cumulative Dissipated Energy (CDE), Ultrasound total time, PHACO time, torsional time, aspiration time, estimated fluid used, and duration of the surgical procedure. In the economic analysis, all PHACO parameters were considered, with a specific focus on the duration of the surgical procedure, costs associated with additional medical materials and devices, complications during surgery, and surgery procedure Diagnosis-Related Group (DRG) codes.

RESULTS

A total of 4535 cases were eligible for inclusion in the study, 278 (6.13%) were diagnosed with PEX and 4257 (93.87%) had no PEX. Significantly higher PHACO parameters were observed in the PEX group. Similarly, a statistically significant increase in the values of all PHACO parameters was observed with the increase in nuclear lens density. Intraoperative complications were more frequent in the PEX group. Zonular weakness requiring the use of a capsular tension ring (CTR) and posterior capsular rupture occurred 30 and 13 times more often, respectively, in the PEX group. The expected cost of the PHACO procedure was found to be 1.4 times higher in patients with PEX, compared to those without PEX, for all types of nuclear cataract.

CONCLUSIONS

All PHACO parameters are significantly higher in patients with PEX. The costs associated with PHACO surgery for cataracts are greater for patients with PEX and are not covered by the present DRG codes, which highlights the need to accordingly adjust the DRGs for PHACO procedures in PEX patients, in order to maintain the quality of healthcare provided for these vulnerable patients.

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.

miRNA Studies in Glaucoma: A Comprehensive Review of Current Knowledge and Future Perspectives

Glaucoma, a neurodegenerative disorder that leads to irreversible blindness, remains a challenge because of its complex nature. MicroRNAs (miRNAs) are crucial regulators of gene expression and are associated with glaucoma and other diseases. We aimed to review and discuss the advantages and disadvantages of miRNA-focused molecular studies in glaucoma through discussing their potential as biomarkers for early detection and diagnosis; offering insights into molecular pathways and mechanisms; and discussing their potential utility with respect to personalized medicine, their therapeutic potential, and non-invasive monitoring. Limitations, such as variability, small sample sizes, sample specificity, and limited accessibility to ocular tissues, are also addressed, underscoring the need for robust protocols and collaboration. Reproducibility and validation are crucial to establish the credibility of miRNA research findings, and the integration of bioinformatics tools for miRNA database creation is a valuable component of a comprehensive approach to investigate miRNA aberrations in patients with glaucoma. Overall, miRNA research in glaucoma has provided significant insights into the molecular mechanisms of the disease, offering potential biomarkers, diagnostic tools, and therapeutic targets. However, addressing challenges such as variability and limited tissue accessibility is essential, and further investigations and validation will contribute to a deeper understanding of the functional significance of miRNAs in glaucoma.