Biology subjects

Saban, D. R.

Publications and source records attributed to Saban, D. R..

7 recordsLinked to original sources

bioRxiv2026

Neutrophil remodeling is associated with human meibomian gland dysfunction and enables IFN-γ- and PAD4-dependent gland obstruction in mice

Meibomian gland dysfunction (MGD), a disorder of the eyelid's modified sebaceous glands, is the leading cause of dry eye disease and ocular surface morbidity, yet the immune mechanisms driving gland obstruction remain poorly defined. In a cross-sectional study of 66 patients with ocular surface inflammation, we used meibography and spectral flow cytometry of tear washes to identify a disease-associated, remodeled neutrophil state whose abundance is associated with gland atrophy. Using single-cell transcriptomics in a murine model of immune-mediated MGD, we revealed a disease-associated neutrophil state that exhibited ocular surface-enrichment, CD14 and ICAM-1 expression, and elevated IFN-{gamma} response and inflammatory signatures. Spatial transcriptomics localized IFN-{gamma} signaling and neutrophil migration signatures to the periglandular compartment. The remodeled neutrophils exhibited PAD4-dependent histone citrullination, with Padi4 deletion reducing NET-associated obstructive plugging, thus identifying PAD4-dependent NETotic activity as their disease-producing output. Inhibition of IFN-{gamma} signaling phenocopied Padi4 deficiency, yet combined disruption of these pathways provided no additive protection, indicating that IFN-{gamma} and PAD4 function as separable required inputs. Remodeled neutrophils accumulated under both conditions, uncoupling disease severity from cell abundance alone. Our findings support immune-mediated obstructive MGD as a mechanistic endotype driven by the IFN-{gamma}- and PAD4-dependent effector output of a remodeled neutrophil state.

immunology↗

bioRxiv2025

The Cornea Harbors a Tricellular Neuro-Immune Niche that Underpins Touch Sensation

Piezo2 is a mechanosensitive ion channel essential for touch and proprioception, yet the mechanisms that maintain this sensory modality in adult tissues are unknown. Using multiphoton imaging of the cornea in live mice, we discovered that the Cx3cr1Cre locus targets not only macrophages, but also a distinct subset of nerves. Spatial-RNAseq resolved that Cx3cr1Cre-driven labeling was uniquely enriched in Piezo2-expressing neurons, a result of temporal Cx3cr1 expression during development. Through lineage tracing, scRNAseq, and imaging, we identified a novel tripartite cellular niche at the epithelial basement membrane, comprised of monocyte-derived macrophages, nerves, and Schwann cells. Additional scRNAseq and genetic studies revealed that Schwann cell-derived IL34 maintained corneal macrophages. Through pharmacologic and genetic perturbations, we also demonstrate corneal macrophages selectively maintained the structure-function of Piezo2-enriched nerve endings, with disruption of this niche causing specific deficits in mechanosensation while preserving other sensory modalities. Altogether, we describe a novel tricellular niche in the cornea required for Piezo2-mediated touch sensation, suggesting new directions for investigating mechanosensory circuits including proprioception.

immunology↗

bioRxiv2025

Intracameral Puncture Lowers Intraocular Pressure and Triggers an Immune Response in the Conventional Outflow Tract

PurposeIntracameral injection is an effective delivery method for biomedical agents and therapeutics to conventional outflow tract tissues. However, the effect of intracameral injections on intraocular pressure and aqueous dynamics has not been well characterized, warranting further investigation. MethodsWild type 3-5-month-old C57BL/6 mice were subjected to intracameral puncture (ICP, without injection of any material). Following ICP, intraocular pressure (IOP), outflow facility, aqueous production, episcleral vessel diameter, and macrophage densities were measured. ResultsOn day 1, IOP was significantly reduced by 30% (p < 0.0001; n=25) while outflow facility (p = 0.306; n=15) and aqueous production (p = 0.163; n=9) were unchanged. As well, Schlemms canal filtration area was unchanged, however distal vessels were dilated (p < 0.001) at day 1 post ICP. Correspondingly, macrophage density was significantly increased around episcleral vessels (p < 0.0005) at day 1. Macrophage densities in Schlemms canal and trabecular meshwork, while unchanged at day 1, were significantly increased by day 3 (p < 0.0001). ConclusionsCoincident with significantly reduced IOP one day after ICP, there was an influx of macrophages into the distal portion of the conventional outflow tissues and a dilation of episcleral vessels, likely reducing distal outflow resistance. Our study demonstrates the importance of considering the drug delivery method to the eye due to its effects on the immune response and conventional outflow homeostasis.

physiology↗

bioRxiv2025

Resident Tissue Macrophages Govern Intraocular Pressure Homeostasis

Intraocular pressure is tightly regulated by the conventional outflow tissues, preventing ocular hypertension that leads to neurodegeneration of the optic nerve, or glaucoma. Although macrophages reside throughout the conventional outflow tract, their role in regulating intraocular pressure remains unknown. Using macrophage lineage tracing approaches, we uncovered a dual macrophage ontogeny with distinct spatial organizations across the mouse lifespan. Long-lived, resident tissue macrophages concentrated in the trabecular meshwork and Schlemms canal, whereas short-lived monocyte-derived macrophages, instead, were abundant around distal vessels. Specific depletion of resident tissue macrophages triggered elevated intraocular pressure and outflow resistance, linked to aberrant extracellular matrix turnover in the resistance-generating tissues of the trabecular meshwork. This dysregulated physiology and tissue remodeling were not observed when we depleted monocyte-derived macrophages. Results show ontogeny and tissue-specific macrophage function within the outflow tract, uncovering the integral homeostatic role of resident tissue macrophages in resistance-generating tissues whose dysfunction is responsible for glaucoma.

immunology↗

bioRxiv2024

Chemokine expression profile of an innate granuloma

Granulomas are defined by the presence of organized layers of immune cells that include macrophages. Granulomas are often characterized as a way for the immune system to contain an infection and prevent its dissemination. We recently established a mouse infection model where Chromobacterium violaceum induces the innate immune system to form granulomas in the liver. This response successfully eradicates the bacteria and returns the liver to homeostasis. Here, we sought to characterize the chemokines involved in directing immune cells to form the distinct layers of a granuloma. We use spatial transcriptomics to investigate the spatial and temporal expression of all CC and CXC chemokines and their receptors within this granuloma response. The expression profiles change dynamically over space and time as the granuloma matures and then resolves. To investigate the importance of monocyte-derived macrophages in this immune response, we studied the role of CCR2 during C. violaceum infection. Ccr2-/- mice had negligible numbers of macrophages, but large numbers of neutrophils, in the C. violaceum-infected lesions. In addition, lesions had abnormal architecture resulting in loss of bacterial containment. Without CCR2, bacteria disseminated and the mice succumbed to the infection. This indicates that macrophages are critical to form a successful innate granuloma in response to C. violaceum. Impact statementA successful innate granuloma requires CCR2 to organize the macrophage ring, and without CCR2, mice succumb to Chromobacterium violaceum infection.

immunology↗

bioRxiv2020

Mucosal Associated Invariant T (MAIT) Cell Responses Differ by Sex in COVID-19

Sexual dimorphisms in immune responses contribute to coronavirus disease 2019 (COVID-19) outcomes, yet the mechanisms governing this disparity remain incompletely understood. We carried out sex-balanced sampling of peripheral blood mononuclear cells from confirmed COVID-19 inpatients and outpatients, uninfected close contacts, and healthy controls for 36-color flow cytometry and single cell RNA-sequencing. Our results revealed a pronounced reduction of circulating mucosal associated invariant T (MAIT) cells in infected females. Integration of published COVID-19 airway tissue datasets implicate that this reduction represented a major wave of MAIT cell extravasation during early infection in females. Moreover, female MAIT cells possessed an immunologically active gene signature, whereas male counterparts were pro-apoptotic. Collectively, our findings uncover a female-specific protective MAIT profile, potentially shedding light on reduced COVID-19 susceptibility in females.

immunology↗

bioRxiv2019

Large-scale death of retinal astrocytes duringnormal development mediated by microglia

Naturally-occurring cell death is a fundamental developmental mechanism for regulating cell numbers and sculpting developing organs. This is particularly true in the central nervous system, where large numbers of neurons and oligodendrocytes are eliminated via apoptosis during normal development. Given the profound impact of death upon these two major cell populations, it is surprising that developmental death of another major cell type - the astrocyte - has rarely been studied. It is presently unclear whether astrocytes are subject to significant amounts of developmental death, or how it occurs. Here we address these questions using mouse retinal astrocytes as our model system. We show that the total number of retinal astrocytes declines by over 3-fold during a death period spanning postnatal days 5-14. Surprisingly, these astrocytes do not die by apoptosis, the canonical mechanism underlying the vast majority of developmental cell death. Instead, we find that microglia kill and engulf astrocytes to mediate their developmental removal. Genetic ablation of microglia inhibits astrocyte death, leading to a larger astrocyte population size at the end of the death period. However, astrocyte death is not completely blocked in the absence of microglia, apparently due to the ability of astrocytes to engulf each other. Nevertheless, mice lacking microglia showed significant anatomical changes to the retinal astrocyte network, with functional consequences for the astrocyte-associated vasculature leading to retinal hemorrhage. These results establish a novel modality for naturally-occurring cell death, and demonstrate its importance for formation and integrity of the retinal gliovascular network.

neuroscience↗