Simvastatin Attenuates Glucocorticoid-Induced Human Trabecular Meshwork Cell Dysfunction via YAP/TAZ Inactivation

Protective Effect of Nicotinamide Riboside on Glucocorticoid-Induced Glaucoma: Mitigating Mitochondrial Damage and Extracellular Matrix Deposition

Purpose

Glucocorticoid-induced glaucoma (GIG) is a prevalent complication associated with glucocorticoids (GCs), resulting in irreversible blindness. GIG is characterized by the abnormal deposition of extracellular matrix (ECM) in the trabecular meshwork (TM), elevation of intraocular pressure (IOP), and loss of retinal ganglion cells (RGCs). The objective of this study is to investigate the effects of nicotinamide riboside (NR) on TM in GIG.

Methods

Primary human TM cells (pHTMs) and C57BL/6J mice responsive to GCs were utilized to establish in vitro and in vivo GIG models, respectively. The study assessed the expression of ECM-related proteins in TM and the functions of pHTMs to reflect the effects of NR. Mitochondrial morphology and function were also examined in the GIG cell model. GIG progression was monitored through IOP, RGCs, and mitochondrial morphology. Intracellular nicotinamide adenine dinucleotide (NAD+) levels of pHTMs were enzymatically assayed.

Results

NR significantly prevented the expression of ECM-related proteins and alleviated dysfunction in pHTMs after dexamethasone treatment. Importantly, NR protected damaged ATP synthesis, preventing overexpression of mitochondrial reactive oxygen species (ROS), and also protect against decreased mitochondrial membrane potential induced by GCs in vitro. In the GIG mouse model, NR partially prevented the elevation of IOP and the loss of RGCs. Furthermore, NR effectively suppressed the excessive expression of ECM-associated proteins and mitigated mitochondrial damage in vivo.

Conclusions

Based on the results, NR effectively enhances intracellular levels of NAD+, thereby mitigating abnormal ECM deposition and TM dysfunction in GIG by attenuating mitochondrial damage induced by GCs. Thus, NR has promising potential as a therapeutic candidate for GIG treatment.

YAP in development and disease: Navigating the regulatory landscape from retina to brain

The distinctive role of Yes-associated protein (YAP) in the nervous system has attracted widespread attention. This comprehensive review strategically uses the retina as a vantage point, embarking on an extensive exploration of YAP's multifaceted impact from the retina to the brain in development and pathology. Initially, we explore the crucial roles of YAP in embryonic and cerebral development. Our focus then shifts to retinal development, examining in detail YAP's regulatory influence on the development of retinal pigment epithelium (RPE) and retinal progenitor cells (RPCs), and its significant effects on the hierarchical structure and functionality of the retina. We also investigate the essential contributions of YAP in maintaining retinal homeostasis, highlighting its precise regulation of retinal cell proliferation and survival. In terms of retinal-related diseases, we explore the epigenetic connections and pathophysiological regulation of YAP in diabetic retinopathy (DR), glaucoma, and proliferative vitreoretinopathy (PVR). Lastly, we broaden our exploration from the retina to the brain, emphasizing the research paradigm of "retina: a window to the brain." Special focus is given to the emerging studies on YAP in brain disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD), underlining its potential therapeutic value in neurodegenerative disorders and neuroinflammation.

Management of Cardiovascular Diseases by Short-Chain Fatty Acid Postbiotics

PURPOSE OF REVIEW

Global health concerns persist in the realm of cardiovascular diseases (CVDs), necessitating innovative strategies for both prevention and treatment. This narrative review aims to explore the potential of short-chain fatty acids (SCFAs)-namely, acetate, propionate, and butyrate-as agents in the realm of postbiotics for the management of CVDs.

RECENT FINDINGS

We commence our discussion by elucidating the concept of postbiotics and their pivotal significance in mitigating various aspects of cardiovascular diseases. This review centers on a comprehensive examination of diverse SCFAs and their associated receptors, notably GPR41, GPR43, and GPR109a. In addition, we delve into the intricate cellular and pharmacological mechanisms through which these receptors operate, providing insights into their specific roles in managing cardiovascular conditions such as hypertension, atherosclerosis, heart failure, and stroke. The integration of current information in our analysis highlights the potential of both SCFAs and their receptors as a promising path for innovative therapeutic approaches in the field of cardiovascular health. The idea of postbiotics arises as an optimistic and inventive method, presenting new opportunities for preventing and treating cardiovascular diseases.

To be or not to be - Decoding the Trabecular Meshwork Cell Identity

The trabecular meshwork within the conventional outflow apparatus is critical in maintaining intraocular pressure homeostasis. In vitro studies employing primary cell cultures of the human trabecular meshwork (hTM) have conventionally served as surrogates for investigating the pathobiology of TM dysfunction. Despite its abundant use, translation of outcomes from in vitro studies to ex vivo and/or in vivo studies remains a challenge. Given the cell heterogeneity, performing single-cell RNA sequencing comparing primary hTM cell cultures to hTM tissue may provide important insights on cellular identity and translatability, as such an approach has not been reported before. In this study, we assembled a total of 14 primary hTM in vitro samples across passages 1-4, including 4 samples from individuals diagnosed with glaucoma. This dataset offers a comprehensive transcriptomic resource of primary hTM in vitro scRNA-seq data to study global changes in gene expression in comparison to cells in tissue in situ. We have performed extensive preprocessing and quality control, allowing the research community to access and utilize this public resource.

The Hippo signalling pathway and its impact on eye diseases

The Hippo signalling pathway, an evolutionarily conserved kinase cascade, has been shown to be crucial for cell fate determination, homeostasis and tissue regeneration. Recent experimental and clinical studies have demonstrated that the Hippo signalling pathway is involved in the pathophysiology of ocular diseases. This article provides the first systematic review of studies on the regulatory and functional roles of mammalian Hippo signalling systems in eye diseases. More comprehensive studies on this pathway are required for a better understanding of the pathophysiology of eye diseases and the development of effective therapies.

ECM biomaterials for modeling of outflow cell biology in health and disease

This review highlights the importance of extracellular matrix (ECM) biomaterials in understanding the biology of human trabecular meshwork (TM) and Schlemm's canal (SC) cells under normal and simulated glaucoma-like conditions. We provide an overview of recent progress in the development and application of state-of-the-art 3D ECM biomaterials including cell-derived ECM, ECM scaffolds, Matrigel, and ECM hydrogels for studies of TM and SC cell (patho)biology. Such bioengineered platforms enable accurate and reliable modeling of tissue-like cell-cell and cell-ECM interactions. They bridge the gap between conventional 2D approaches and in vivo/ex vivo models, and have the potential to aid in the identification of the causal mechanism(s) for outflow dysfunction in ocular hypertensive glaucoma. We discuss each model's benefits and limitations, and close with an outlook on future directions.

Glucocorticoid-Induced Ocular Hypertension and Glaucoma

Glucocorticoid (GC) therapy is indicated in many diseases, including ocular diseases. An important side-effect of GC therapy is GC-induced ocular hypertension (GIOHT), which may cause irreversible blindness known as GC-induced glaucoma (GIG). Here, we reviewed the pathological changes that contribute to GIOHT including in the trabecular meshwork and Schlemm's canal at cellular and molecular levels. We also discussed the clinical aspects of GIOHT/GIG including disease prevalence, risk factors, the type of GCs, the route of GC administration, and management strategies.

Targeting YAP/TAZ mechanosignaling to ameliorate stiffness-induced Schlemm's canal cell pathobiology

Pathological alterations in the biomechanical properties of the Schlemm's canal (SC) inner wall endothelium and its immediate vicinity are strongly associated with ocular hypertension in glaucoma due to decreased outflow facility. Specifically, the underlying trabecular meshwork is substantially stiffer in glaucomatous eyes compared with that from normal eyes. This raises the possibility of a critical involvement of mechanotransduction processes in driving SC cell dysfunction. Yes-associated protein (YAP) has emerged as a key contributor to glaucoma pathogenesis. However, the molecular underpinnings of SC cell mechanosignaling via YAP and transcriptional coactivator with PDZ-binding motif (TAZ) in response to glaucomatous extracellular matrix (ECM) stiffening are not well understood. Using a novel biopolymer hydrogel that facilitates dynamic and reversible stiffness tuning, we investigated how ECM stiffening modulates YAP/TAZ activity in primary human SC cells, and whether disruption of YAP/TAZ mechanosignaling attenuates SC cell pathobiology and increases ex vivo outflow facility. We demonstrated that ECM stiffening drives pathologic YAP/TAZ activation and cytoskeletal reorganization in SC cells, which was fully reversible by matrix softening in a distinct time-dependent manner. Furthermore, we showed that pharmacologic or genetic disruption of YAP/TAZ mechanosignaling abrogates stiffness-induced SC cell dysfunction involving altered cytoskeletal and ECM remodeling. Finally, we found that perfusion of the clinically used, small molecule YAP/TAZ inhibitor verteporfin (without light activation) increases ex vivo outflow facility in normal mouse eyes. Collectively, our data provide new evidence for a pathologic role of aberrant YAP/TAZ mechanosignaling in SC cell dysfunction and suggest that YAP/TAZ inhibition has therapeutic value for treating ocular hypertension in glaucoma.NEW & NOTEWORTHY Pathologically altered biomechanical properties of the Schlemm's canal (SC) inner wall microenvironment were recently validated as the cause for increased outflow resistance in ocular hypertensive glaucoma. However, the involvement of specific mechanotransduction pathways in these disease processes is largely unclear. Here, we demonstrate that Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) are central regulators of glaucoma-like SC cell dysfunction in response to extracellular matrix stiffening and that targeted disruption of YAP/TAZ mechanosignaling attenuates SC cell pathobiology and enhances outflow function.