Sterling, J. K. | Search bioRxiv

bioRxiv2026

Retinal scRNAseq reveals cell-type-specific responses to bacterial infection

PurposeEndophthalmitis is a serious complication of intraocular surgery due to the risk of irreversible retinal damage. Because retinal cell populations are highly heterogenous, single-cell resolution is required to uncover the detailed mechanisms of infection response. Using a mouse model of bacterial endophthalmitis, we investigated transcriptional changes across resident and infiltrating cell types in the retina. MethodsA methicillin-sensitive strain of Staphylococcus aureus was isolated from a patient with endophthalmitis. Adult C57Bl/6J mice received an intravitreal injection of phosphate-buffer solution (PBS) with or without 5000 CFU S. aureus (n=3 per group). 24 hours later, retinas were isolated and single-cell suspensions were sent to the Penn Genomic Core for sequencing with an Illumina NovaSeq 6000. After standard pre-processing of the data, differential genes and pathways were identified for each cell type (adjusted p < 0.01, log2FC > 1 or < -1). ResultsOur analysis identified all expected retinal cell types, including a population of infiltrating neutrophils in the infected retinas. We surveyed genes known to be upregulated at the bulk-retina level in this model (e.g. Tlr2, Nlrp3, Il1b), and found that infiltrating cells mainly drove this expression. Several genes were altered across nearly all retinal cell types, including upregulation of Hsph1 and Stat3. Muller glia downregulated Gpx4 while upregulating Acsl4 and iron importers Tfrc, Zip14, and Dmt1. Top pathways for macrophages/microglia included chemotaxis, cell-cell adhesion, and wound healing. Vascular cells upregulated angiogenesis-related genes. Cellular respiration was a commonly affected pathway across several neuronal populations, with most genes decreasing. ConclusionsThis study advances our understanding of the pathobiology of bacterial endophthalmitis. Muller glia appear to be undergoing ferroptosis, potentially while activating a program to sequester iron away from bacteria. Decreased cellular respiration may indicate hypoxia among neurons. Our results reveal several trends in the retinal response to infection, including iron dysregulation and hypoxia. Understanding these cell-type-specific responses to endophthalmitis may help design therapies to combine with antibiotics.

microbiology↗

bioRxiv2020

GLP-1R agonist NLY01 reduces retinal inflammation, astrocyte reactivity, and retinal ganglion cell death secondary to ocular hypertension.

Glaucoma is the leading cause of irreversible blindness worldwide and is characterized by the death of retinal ganglion cells. Reduction of intraocular pressure (IOP) is the only therapeutic mechanism available to slow disease progression. However, glaucoma can continue to progress despite normalization of IOP. New treatments are needed to reduce vision loss and improve outcomes for patients who have exhausted existing therapeutic avenues. Recent studies have implicated neuroinflammation in the pathogenesis of neurodegenerative diseases of both the retina and the brain, including glaucoma and Parkinsons disease. Pro-inflammatory A1 astrocytes contribute to neuronal cell death in multiple disease processes and have been targeted therapeutically in mouse models of Parkinsons disease. Microglial release of pro-inflammatory cytokines C1q, IL-1, and TNF- is sufficient to drive the formation of A1 astrocytes. The role of A1 astrocytes in glaucoma pathogenesis has not been explored. Using a mouse model of glaucoma, we demonstrated that IOP elevation was sufficient to trigger production of C1q, IL-1, and TNF- by infiltrating macrophages followed by resident microglia. These three cytokines drove the formation of A1 astrocytes in the retina. Furthermore, cytokine production and A1 astrocyte transformation persisted following IOP normalization. Ablation of this pathway, by either genetic deletions of C1q, IL-1, and TNF-, or treatment with glucagon-like peptide-1 receptor agonist NLY01, reduced A1 astrocyte transformation and RGC death. Together, these results highlight a new neuroinflammatory mechanism behind glaucomatous neurodegeneration that can be therapeutically targeted by NLY01 administration.

neuroscience↗