Browsing by Author "Feris, Sherri"
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Item Pharmacokinetic and Physicochemical Evaluation of Novel Drug Candidates for Retinitis Pigmentosa(2023) Garrett, Meredith; Curry, Stacy; Feris, Sherri; Martin, Stephen; Clark, Abbot; Kastellorizios, MichailPurpose: Retinitis pigmentosa is a set of inherited ocular diseases that affect nearly 3 million people worldwide. The condition is inherited and causes the progressive deterioration of the retina. Retinitis pigmentosa begins with the loss of rod photoreceptors which cause night blindness and a decrease in peripheral vision. After significant loss of rod cells, cone cells also begin to die, decreasing central vision until complete blindness. More than 150 genetic mutations in 80 different genes have thus far been identified to contribute to progression pathways of the condition. Despite ongoing stem cell and gene therapy investigations, thus far there are no curative options. Most existing treatments focus on slowing the progression of retinal deterioration by reducing oxidative stress on the retina. Unfortunately, these treatments only achieve limited success and cannot halt progression. Recently, the sigma 2 receptor (σ2r) was identified to be endoplasmic reticulum membrane protein 97 (TMEM97). This protein (σ2r/TMEM97) has been shown to have neuroprotective effects on retinal cells and is thus of interest as a potential drug target for retinitis pigmentosa. Here we synthesized and tested a series of six compounds which have previously been found to modulate σ2r/TMEM97. To determine which of these compounds is a suitable drug candidate, each underwent in vivo and in vitro testing with the goal of selecting the best candidate for further clinical development. Methods: We tested the compounds in a rat model to determine retinal uptake following intravitreal injection. Each drug was dissolved in dimethyl sulfoxide (DMSO) and injected into the eye. At set time points, animals were sacrificed, and retinas were isolated from harvested eyes. The retina was separated and homogenized using sonication. A small portion was removed and underwent protein precipitation to purify the sample. The samples were then analyzed via liquid chromatography mass spectrometry (LCMS) to find the drug concentration remaining at each timepoint. In addition to obtaining a pharmacokinetic profile, the compounds were physiochemically characterized for chemical stability, solubility, in vitro drug release from vitreous humor, thermal analysis, and surface tension. Conclusion: Our goal is to select those drug candidates with the highest chance of clinical success. The pharmacokinetic profiles as well as physicochemical characteristics and stability of the compounds obtained in this study revealed important differences between the compounds that were used in selecting which to advance to in vivo efficacy testing. Ongoing studies include completion of physicochemical characterization and in vivo efficacy in a retinitis pigmentosa rat model that will be used to identify top candidates for further development.Item Phenotypic and transcriptomic comparison of genetically distinct mouse strains for susceptibility to glucocorticoid-induced ocular hypertension (GC-OHT)(2024-03-21) Patel, Pinkal D.; Millar, J. Cameron; Curry, Stacy; Feris, Sherri; Clark, Abbot F.Purpose: Anti-inflammatory and immunosuppressive glucocorticoids (GCs) are widely prescribed for a variety of conditions and diseases. Unfortunately, a significant number of people experience negative side-effects associated with long term GC therapy and develop GC-induced ocular hypertension (GC-OHT) leading to secondary glaucoma. GC-OHT shares clinical and molecular signatures with primary open angle glaucoma (POAG) making this an appropriate model to study POAG. However, not all humans develop GC-OHT when treated with GCs. The ones that develop GC-OHT are called ‘responders’ whereas the ones that do not respond to GCs are called ‘non-responders’. The purpose of our study is to: (1) determine whether there are mouse strain differences in the development of GC-OHT, (2) whether resistance to develop GC-OHT is correlated with endogenous TM tissue gene expression using transcriptomic analysis. Methods: After measurement of baseline IOP, various mouse strains (B6, D2.gpnmb⁺, BALB/cJ, 129P3/J, C3H/HeJ) were treated with weekly periocular injections of potent GC dexamethasone (DEX; n=5-10) or vehicle (n=5-10) in both eyes for 4-5 weeks. IOPs were measured weekly using a TonoLab rebound tonometer in isoflurane anesthetized mice. “TM ring” tissue and underlying sclera was carefully collected, and mRNA libraries were prepared for sequencing. Differential expression analysis was performed to identify DEX-induced changes within each strain. Furthermore, Ingenuity Pathway Analysis (IPA) was used to identify DEX-altered pathways in each strain and compare differences between responder and non-responder strains. Results: B6 and C3H/HeJ mice robustly and reproducibly develop DEX-OHT with ΔIOP of 5-8 mmHg (P<0.0001). In contrast, D2.gpnmb⁺, 129P3/J, and BALB/cJ mice were resistant to the development of DEX-OHT. Differential analysis of gene expression between mouse strains showed novel DEX-responsive genes in all strains. Moreover, comparison of mouse strains using IPA showed similarities in the pathway and networks of the responder strains (B6 and C3H/HeJ). Conclusions: As observed in humans, we find that there are differences in GC responsiveness and the ability to develop GC-OHT among mouse strains. Transcriptomics evidence suggests that responder strains share common pathways that contribute towards development of GC-OHT. These studies will reveal the molecular mechanisms responsible for GC-OHT as well as provide insights into the pathogenesis of POAG.