Biology subjects

Grossniklaus, H. E.

Publications and source records attributed to Grossniklaus, H. E..

3 recordsLinked to original sources

bioRxiv2025

Long-Term Functional Rescue of Trauma-Induced Vision Loss by a Novel, Small Molecule TrkB Activator

Brain-derived neurotrophic factor (BDNF) signaling through the tropomyosin-related kinase B (TrkB) receptor promotes neuronal growth and survival following an injury. However, its short half-life and pleiotropic effects limit the clinical use of BDNF as a therapy in neurodegenerative disorders. Identification of novel and selective TrkB activators may ameliorate the damage caused to retinal neurons during eye-related injuries, and may reduce adverse visual outcomes associated with visual trauma. We previously described a selective TrkB agonist, N-[2-(5-hydroxy-1H-indol-3-yl) ethyl]-2-oxopiperidine-3-carboxamide (HIOC), that reduces the decline in visual function in a mouse model of ocular trauma (1). Using the lead optimization approach, we subsequently synthesized a fluoropyridine analog of HIOC, 2-fluoro-N-(2-(5-hydroxy-1H-indol-3-yl) ethyl) nicotinamide (HIFN), which also successfully activates TrkB. HIFN is a more potent TrkB activator than the parent compound, HIOC. Further, treatment with HIFN demonstrated neuroprotection in an animal model of overpressure ocular blast injury, ameliorating blast-related visual functional decline. Mice treated with HIFN had better visual acuity, contrast sensitivity, and retinal function supported by enhanced survival of retinal ganglion cells compared to vehicle-treated animals. Moreover, HIFN exhibited better protective effects than HIOC. The therapeutic effects of HIFN were attributed to TrkB activation, as blocking the receptor with a selective receptor antagonist (ANA-12) abrogated the neuroprotection. Together, our results identify HIFN, a novel TrkB receptor activator, as a strategy for decreasing retinal degeneration and progressive vision loss associated with traumatic ocular injury. In addition, this compound may have broader applications treating other diseases with altered TrkB activity.

neuroscience↗

bioRxiv2024

Loss of Pigment Epithelium Derived Factor Sensitizes C57BL/6J Mice to Light-Induced Retinal Damage

5.1PurposePigment epithelium-derived factor (PEDF) is a neurotrophic glycoprotein secreted by the retinal pigment epithelium (RPE) that supports retinal photoreceptor health. Deficits in PEDF are associated with increased inflammation and retinal degeneration in aging and diabetic retinopathy. We hypothesized that light-induced stress in C57BL/6J mice deficient in PEDF would lead to increased retinal neuronal and RPE defects, impaired expression of neurotrophic factor Insulin-like growth factor 1 (IGF-1), and overactivation of Galectin-3-mediated inflammatory signaling. MethodsC57BL/6J mice expressing the RPE65 M450/M450 allele were crossed to PEDF KO/KO and wildtype (PEDF +/+) littermates. Mice were exposed to 50,000 lux light for 5 hours to initiate acute damage. Changes in visual function outcomes were tracked via electroretinogram (ERG), confocal scanning laser ophthalmoscopy(cSLO), and spectral domain optical coherence tomography (SD-OCT) on days 3, 5, and 7 post-light exposure. Gene and protein expression of Galectin-3 were measured by digital drop PCR (ddPCR) and western blot. To further investigate the role of galectin-3 on visual outcomes and PEDF expression after damage, we also used a small-molecule inhibitor to reduce its activity. ResultsFollowing light damage, PEDF KO/KO mice showed more severe retinal thinning, impaired visual function (reduced a-, b-, and c-wave amplitudes), and increased Galectin-3 expressing immune cell infiltration compared to PEDF +/+. PEDF KO/KO mice had suppressed damage-associated increases in IGF-1 expression. Additionally, baseline Galectin-3 mRNA and protein expression were reduced in PEDF KO/KO mice compared to PEDF +/+. However, after light damage, Galectin-3 expression decreases in PEDF +/+ mice but increases in PEDF KO/KO mice without reaching PEDF +/+ levels. Galectin-3 inhibition worsens retinal degeneration, reduces PEDF expression in PEDF +/+ mice, and mimics the effects seen in PEDF knockouts. ConclusionsLoss of PEDF alone does not elicit functional defects in C57BL/6J mice. However, under light stress, PEDF deficiency significantly increases severe retinal degeneration, visual deficits, Galectin-3 expression, and suppression of IGF-1 than PEDF +/+. PEDF deficiency reduced baseline expression of Galectin-3, and pharmacological inhibition of Galectin-3 worsens outcomes and suppresses PEDF expression in PEDF +/+, suggesting a novel co-regulatory relationship between the two proteins in mitigating light-induced retinal damage.

molecular biology↗

bioRxiv2024

Magnetically Steered Cell Therapy For Functional Restoration Of Intraocular Pressure Control In Open-Angle Glaucoma

Trabecular meshwork (TM) cell therapy has been proposed as a next-generation treatment for elevated intraocular pressure (IOP) in glaucoma, the most common cause of irreversible blindness. Using a magnetic cell steering technique with excellent efficiency and tissue-specific targeting, we delivered two types of cells into a mouse model of glaucoma: either human adipose-derived mesenchymal stem cells (hAMSCs) or induced pluripotent cell derivatives (iPSC-TM cells). We observed a 4.5 [3.1, 6.0] mmHg or 27% reduction in intraocular pressure (IOP) for nine months after a single dose of only 1500 magnetically-steered hAMSCs, explained by increased outflow through the conventional pathway and associated with an higher TM cellularity. iPSC-TM cells were also effective, but less so, showing only a 1.9 [0.4, 3.3] mmHg or 13% IOP reduction and increased risk of tumorigenicity. In both cases, injected cells remained detectable in the iridocorneal angle three weeks post-transplantation. Based on the locations of the delivered cells, the mechanism of IOP lowering is most likely paracrine signaling. We conclude that magnetically-steered hAMSC cell therapy has potential for long-term treatment of ocular hypertension in glaucoma. One Sentence SummaryA novel magnetic cell therapy provided effective intraocular pressure reduction in a mouse model, motivating future translational studies.

bioengineering↗