Biology subjects

Diemler, C. A.

Publications and source records attributed to Diemler, C. A..

3 recordsLinked to original sources

bioRxiv2024

Genetic context modulates aging and degeneration in the murine retina

BackgroundAge is the principal risk factor for neurodegeneration in both the retina and brain. The retina and brain share many biological properties; thus, insights into retinal aging and degeneration may shed light onto similar processes in the brain. Genetic makeup strongly influences susceptibility to age-related retinal disease. However, studies investigating retinal aging have not sufficiently accounted for genetic diversity. Therefore, examining molecular aging in the retina across different genetic backgrounds will enhance our understanding of human-relevant aging and degeneration in both the retina and brain--potentially improving therapeutic approaches to these debilitating conditions. MethodsTranscriptomics and proteomics were employed to elucidate retinal aging signatures in nine genetically diverse mouse strains (C57BL/6J, 129S1/SvlmJ, NZO/HlLtJ, WSB/EiJ, CAST/EiJ, PWK/PhK, NOD/ShiLtJ, A/J, and BALB/cJ) across lifespan. These data predicted human disease-relevant changes in WSB and NZO strains. Accordingly, B6, WSB and NZO mice were subjected to human-relevant in vivo examinations at 4, 8, 12, and/or 18M, including: slit lamp, fundus imaging, optical coherence tomography, fluorescein angiography, and pattern/full-field electroretinography. Retinal morphology, vascular structure, and cell counts were assessed ex vivo. ResultsWe identified common molecular aging signatures across the nine mouse strains, which included genes associated with photoreceptor function and immune activation. Genetic background strongly modulated these aging signatures. Analysis of cell type-specific marker genes predicted age-related loss of photoreceptors and retinal ganglion cells (RGCs) in WSB and NZO, respectively. Fundus exams revealed retinitis pigmentosa-relevant pigmentary abnormalities in WSB retinas and diabetic retinopathy (DR)-relevant cotton wool spots and exudates in NZO retinas. Profound photoreceptor dysfunction and loss were confirmed in WSB. Molecular analyses indicated changes in photoreceptor-specific proteins prior to loss, suggesting photoreceptor-intrinsic dysfunction in WSB. In addition, age-associated RGC dysfunction, loss, and concomitant microvascular dysfunction was observed in NZO mice. Proteomic analyses revealed an early reduction in protective antioxidant processes, which may underlie increased susceptibility to DR-relevant pathology in NZO. ConclusionsGenetic context is a strong determinant of retinal aging, and our multi-omics resource can aid in understanding age-related diseases of the eye and brain. Our investigations identified and validated WSB and NZO mice as improved preclinical models relevant to common retinal neurodegenerative diseases.

neuroscience↗

bioRxiv2024

Microglia Depletion leads to Increased Susceptibility to Ocular Hypertension-Dependent Glaucoma

In recent years, microglia have been highlighted for playing integral roles in neurodegenerative diseases, like glaucoma. To better understand the role of microglia during chronic ocular hypertension, we depleted microglia from aged (9-12 months old) DBA/2J (D2) mice, which exhibit age-related increases in intraocular pressure, using a dietary CSF1R antagonist, PLX5622. Retinal ganglion cell (RGC) somas were counted, and optic nerve cross-sections stained and assessed for glaucomatous damage. Sustained administration of dietary PLX5622 significantly reduced the numbers of retinal microglia. Dietary PLX5622 did not lead to changes in intraocular pressure in D2 or normotensive DBA/2J-Gpnmb+ (D2-Gpnmb+) control mice. While PLX5622-treated D2-Gpnmb+ did not develop optic nerve damage, PLX5622-treated D2 mice showed a significant increase in moderate-to-severe optic nerve damage compared to D2 mice fed a control diet. In conclusion, global reduction of microglia exacerbated glaucomatous neurodegeneration in D2 mice suggesting microglia play an overall beneficial role in protecting from ocular hypertension associated RGC loss.

neuroscience↗

bioRxiv2022

APOEϵ4 and exercise interact to influence systemic and cerebral risk factors for dementia

INTRODUCTIONAPOE{varepsilon}4 is the strongest genetic risk factor for Alzheimers disease and related dementias (ADRDs) affecting many different pathways that lead to cognitive decline. Exercise is one of the most widely proposed prevention, and intervention strategies to mitigate risk and symptomology of ADRDs. Importantly, exercise and APOE{varepsilon}4 affect similar processes on the body and brain. While both APOE{varepsilon}4, and exercise have been studied extensively, their interactive effects are not well understood. METHODSTo address this, male and female APOE{varepsilon}3/{varepsilon}3, APOE{varepsilon}3/{varepsilon}4 and APOE{varepsilon}4/{varepsilon}4 mice ran voluntarily from wean (1mo) to midlife (12mo). Longitudinal and cross-sectional phenotyping was performed on the periphery and the brain, on markers of risk for dementia such as weight, body composition, circulating cholesterol composition, activities of daily living, energy expenditure, and cortical and hippocampal transcriptional profiling. RESULTSData revealed chronic running decreased age-dependent weight gain, lean and fat mass, and serum LDL concentration dependent on APOE genotype. Additionally, murine activities of daily living and energy expenditure were significantly influenced by an interaction between APOE genotype and running in both sexes. Transcriptional profiling of the cortex and hippocampus predicted that APOE genotype and running interact to affect numerous biological processes including vascular integrity, synaptic/neuronal health, cell motility, and mitochondrial metabolism, in a sex-specific manner. DISCUSSIONThese data provide compelling evidence that APOE genotype should be considered for population-based strategies that incorporate exercise to prevent ADRDs.

genetics↗