Age-related macular degeneration (AMD) occurs due to an abnormality of retinal pigment epithelium (RPE) cells that leads to gradual degeneration of the macula. Currently, AMD drug pipelines are ...endowed with limited options, and anti-VEGF agents stand as the dominantly employed therapy. Despite the proven efficacy of such agents, the evidenced side effects associated with their use underscore the need to elucidate other mechanisms involved and identify additional molecular targets for the sake of therapy improvement. The previous literature provided us with a solid rationale to preliminarily explore the potential of selective HDAC6 and HSP90 inhibitors to treat wet AMD. Rather than furnishing single-target agents (either HDAC6 or HSP90 inhibitor), this study recruited scaffolds endowed with the ability to concomitantly modulate both targets (HDAC6 and HSP90) for exploration. This plan was anticipated to accomplish the important goal of extracting amplified benefits via dual inhibition (HDAC6/HSP90) in wet AMD. As a result, G570 (indoline-based hydroxamate), a dual selective HDAC6-HSP90 inhibitor exerting its effects at micromolar concentrations, was pinpointed in the present endeavor to attenuate blue light-induced cell migration and retinal neovascularization by inhibiting VEGF production. In addition to the identification of a potential chemical tool (G570), the outcome of this study validates the candidate HDAC6-HSP90 as a compelling target for the development of futuristic therapeutics for wet AMD.
The devastating effects and incurable nature of hereditary and sporadic retinal diseases such as Stargardt disease, age-related macular degeneration or retinitis pigmentosa urgently require the ...development of new therapeutic strategies. Additionally, a high prevalence of retinal toxicities is becoming more and more an issue of novel targeted therapeutic agents. Ophthalmologic drug development, to date, largely relies on animal models, which often do not provide results that are translatable to human patients. Hence, the establishment of sophisticated human tissue-based in vitro models is of upmost importance. The discovery of self-forming retinal organoids (ROs) derived from human embryonic stem cells (hESCs) or human induced pluripotent stem cells (hiPSCs) is a promising approach to model the complex stratified retinal tissue. Yet, ROs lack vascularization and cannot recapitulate the important physiological interactions of matured photoreceptors and the retinal pigment epithelium (RPE). In this study, we present the retina-on-a-chip (RoC), a novel microphysiological model of the human retina integrating more than seven different essential retinal cell types derived from hiPSCs. It provides vasculature-like perfusion and enables, for the first time, the recapitulation of the interaction of mature photoreceptor segments with RPE in vitro. We show that this interaction enhances the formation of outer segment-like structures and the establishment of in vivo-like physiological processes such as outer segment phagocytosis and calcium dynamics. In addition, we demonstrate the applicability of the RoC for drug testing, by reproducing the retinopathic side-effects of the anti-malaria drug chloroquine and the antibiotic gentamicin. The developed hiPSC-based RoC has the potential to promote drug development and provide new insights into the underlying pathology of retinal diseases.
A series of near‐infrared (NIR) organic absorbers, named FNs and FPs, have been obtained with absorption maxima from 870 nm to 1100 nm and thus falling into the attractive second near‐infrared region ...(NIR‐II). The synthesis of their extended aromatic cores utilized an initial aryl‐amination between 4‐aminonaphthalene‐1,8‐dicarboximide (NMI‐NH2) or 9‐aminoperylene‐3,4‐dicarboximide (PMI‐NH2) with chloro‐substituted 9,10‐anthraquinones followed by a novel base‐induced cyclodehydrogenation. A NIR‐II pigment, compound FPP, was obtained through de‐alkylation of a soluble precursor. The synthesis of this photostable pigment is high‐yielding and avoids column chromatographic purification which is important for many applications.
A series of organic near infrared (NIR) absorbers based on rylenecarboximide and anthraquinone were obtained with maximum absorption peaks ranging from 870 nm to 1100 nm. A photostable pigment with NIR‐II absorption was developed through de‐alkylation reaction under formation of intermolecular hydrogen bonds.
Dysfunction and eventual loss of retinal pigment epithelial (RPE) cells is a hallmark of atrophic age-related macular degeneration (AMD), and linked to oxidative and nitrosative damage. Herein, we ...use a high-throughput screen (HTS) to identify compounds that protect human RPE cells from oxidative stress-induced cell death and elucidate the possible mechanism of action. HTS was used to identify compounds that protect RPE cells from oxidative damage. We tested the identified compound(s) in models of RPE stress, including tert-butyl hydroperoxide (TBHP) exposure, ultraviolet-B (UV-B)-mediated light damage and nitrosative stress to the basement membrane using ARPE-19 cells, primary human RPE cells and induced-pluripotent stem cell (iPSC)-derived RPE cells from patients with AMD. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to detect gene expression of oxidative stress- and apoptosis-related genes and mitochondrial function was measured using a Seahorse XF96 analyzer to elucidate possible mechanisms of action. Five thousand and sixty-five compounds were screened, and of these, 12 compounds were active based on their ability to improve cell viability after exposure to TBHP. After chemical structure review, we identified ciclopirox olamine as a potent inhibitor of oxidative damage to RPE cells. Ciclopirox olamine increased cell viability in ARPE-19 cells treated with TBHP, UV-B light or on nitrite-modified extracellular matrix (ECM) by 1.68-fold, 1.54-fold and 4.3-fold, respectively (p < 0.01). Treatment with TBHP altered expression of genes related to oxidative stress and apoptosis, which was reversed by pretreatment with ciclopirox olamine. Ciclopirox olamine improved mitochondrial function in TBHP-exposed ARPE-19 cells and iPSC-derived RPE cells. Ciclopirox olamine protected primary human RPE cells and iPSC-derived RPE cells from the oxidative stress or damaged basement membrane. HTS of bioactive Food and Drug Administration (FDA)-approved libraries and follow-up studies can be used to identify small molecules (including ciclopirox olamine) that protect RPE cells exposed to various stressors associated with disease progression of AMD. This strategy can be used to identify potential compounds for treatment and prevention of AMD.
•A high-throughput screen (HTS) was developed to identify compounds that protect human RPE cells from oxidative damage.•Ciclopirox olamine protects RPE cells from oxidative damage and nitrosative damage to the basement membrane.•This HTS protocol can be used to identify potential compounds that may prevent or delay the progression of atrophic AMD.
There are many conditions that affect the retina. However, diabetic retinopathy (RD) as a complication of Diabetes Mellitus continues to be the leading cause of blindness in working people globally. ...Diabetic retinopathy is an ocular complication of diabetes that is caused by the deterioration of the blood vessels that supply the retina, which has the consequence that the vision deteriorates irreversibly. The retina, and specifically the retinal pigment epithelium (RPE) is the only neural tissue that is exposed directly and frequently to light, which favors the oxidation of lipids that become extremely toxic to the cells of the retina. The RPE is a natural barrier playing an important role in the absorption of light and reduction of light scatter within the eye. In addition, the retina is the tissue that proportionally consumes more oxygen, which generates a high production of reactive oxygen species (ROS). The retina is particularly sensitive to hyperglycemia and oxidative stress. The eye tissues are enriched in certain antioxidants in the form of metabolic enzymes or small molecules. Since selenium is essential for regulating the activity of the enzymes involved in protection against oxidative stress, providing selenium to the ocular tissues could be useful for the treatment of different ocular pathologies. Thus, the aim of this study is to investigate the potential efficacy of selenium in human RPE against glucose-induced oxidative stress and its implications for GPx activity. Chromatographic techniques based on HPLC-ICP-MS will be applied in combination with isotope pattern deconvolution (IPD) to study the effects of selenium supplementation and hyperglycemia in an in vitro model of RPE cells.
Renewal and elimination of the aged photoreceptor outer segment (POS) by RPE cells is a daily rhythmic process that is important for long-term vision. Phagocytic dysfunction results in photoreceptor ...cell death. Tauroursodeoxycholic acid (TUDCA), an endogenous bile acid, is known to show neuroprotective effects in stroke, neurological diseases, and retinal degeneration models. In this study, we investigated the effects of TUDCA on retinal phagocytosis.
We used pHrodo-succinimidyl ester (SE), a pH-sensitive fluorescent dye, to label the POS for monitoring phagocytosis. After ingestion, the intensity of pHrodo fluorescence increases because of the pH changes inside the liposome. An RPE cell line, ARPE-19, and primary human RPE cells were used to investigate the hydrogen peroxide (H2O2)-induced disruption of phagocytosis in the pH-sensitive fluorescence POS phagocytosis assay. Additionally, we examined whether TUDCA could promote phagocytic function.
The intensity of pHrodo light emission increased in a time-dependent manner. Tauroursodeoxycholic acid enhanced phagocytosis of POS and protected against H2O2-induced phagocytic dysfunction. It also promoted phagocytic function via activation of Mer tyrosine kinase receptor (MerTK), which is known to have a key role in the physiological renewal of POS.
These results suggest that TUDCA activates MerTK, which is important for phagocytosis of POS. Tauroursodeoxycholic acid may represent a new therapeutic option for the treatment of retinal diseases.
Age-related macular degeneration (AMD) predominantly affects the retina and retinal pigment epithelium in the posterior eye. While there are numerous studies investigating the non-coding ...transcriptome of retina and RPE, few significant differences between AMD and normal tissues have been reported. Strand specific RNA sequencing of both peripheral retina (PR) and RPE-Choroid-Sclera (PRCS), in both AMD and matched normal controls were generated. The transcriptome analysis reveals a highly significant and consistent impact on anti-sense transcription as well as moderate changes in the regulation of non-coding (sense) RNA. Hundreds of genes that do not express anti-sense transcripts in normal PR and PRCS demonstrate significant anti-sense expression in AMD in all patient samples. Several pathways are highly enriched in the upregulated anti-sense transcripts-in particular the EIF2 signaling pathway. These results call for a deeper exploration into anti-sense and noncoding RNA regulation in AMD and their potential as therapeutic targets.
•HG induced mitochondrial dysfunction and apoptosis in retinal cells.•HG upreuglates Fas and SOCS1 in retinal cells.•HG promotes JAK/STAT signaling.
Diabetic retinopathy (DR) is one of the most ...serious complications of diabetes mellitus (DM), however, the contribution of high glucose (HG) or hyperglycemia to DR is far from fully understanding. In the present study, we examined the expression of Fas/FasL signaling and suppressors of cytokine signaling (SOCS)1 and 3 in HG-induced human retinal pigment epithelium cells (ARPE-19 cells). And then we investigated the regulatory role of both Fas and SOCS1 in HG-induced mitochondrial dysfunction and apoptosis. Results demonstrated that HG with more than 40mM induced mitochondrial dysfunction via reducing mitochondrial membrane potential (MMP) and via inhibiting the Bcl-2 level, which is the upstream signaling of mitochondria in ARPE-19 cells. HG also upreuglated the Fas signaling and SOCS levels probably via promoting JAK/STAT signaling in ARPE-19 cells. Moreover, the exogenous Fas or entogenous overexpressed SOCS1 accentuated the HG-induced mitochondrial dysfunction and apoptosis, whereas the knockdown of either Fas or SOCS1 reduced the HG-induced mitochondria dysfunction and apoptosis. Thus, the present study confirmed that both Fas/FasL signaling and SOCS1 promoted the HG-induced mitochondrial dysfunction and apoptosis. These results implies the key regulatory role of Fas signaling and SOCS in DR.
Animal cells undergo a dramatic series of shape changes as they divide, which depend on re-modeling of cell-substrate adhesions. Here, we show that while focal adhesion complexes are disassembled ...during mitotic rounding, integrins remain in place. These integrin-rich contacts connect mitotic cells to the underlying substrate throughout mitosis, guide polarized cell migration following mitotic exit, and are functionally important, since adherent cells undergo division failure when removed from the substrate. Further, the ability of cells to re-spread along pre-existing adhesive contacts is essential for division in cells compromised in their ability to construct a RhoGEF-dependent (Ect2) actomyosin ring. As a result, following Ect2 depletion, cells fail to divide on small adhesive islands but successfully divide on larger patterns, as the connection between daughter cells narrows and severs as they migrate away from one another. In this way, regulated re-modeling of cell-substrate adhesions during mitotic rounding aids division in animal cells.
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•Cells re-model adhesions as they round up upon entry into mitosis•These cell-substrate adhesions are essential for division in non-transformed cells•Adhesions can guide migration to divide cells with a compromised actomyosin ring
Dix et al. show that the integrin-positive adhesive contacts that remain following mitotic rounding are essential for division in non-transformed adherent cells in culture. Further, these adhesion sites guide polarized daughter cell migration—a process that is sufficient to drive abscission in the absence of a visible contractile actomyosin ring.
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