Biology subjects

Dana, R.

Publications and source records attributed to Dana, R..

4 recordsLinked to original sources

bioRxiv2024

A limbal stem cell deficiency murine model with residual limbal stem cells

Bilateral limbal stem cell deficiency (LSCD) is a significant cause of corneal blindness and is more difficult to treat, as compared with unilateral LSCD because no source of autologous limbal stem cells (LSCs) remains in these patients. Thus, bilateral patients could be candidates for treatment with allogeneic LSC transplants that require long-term systemic immunosuppression therapy. Thus, if possible, for the correct candidates, using autologous LSCs could be a preferred treatment. Recent in vivo laser confocal microscopic examination of the ocular surface in situ, combined with impression cytology, has indicated that some patients diagnosed with a complete bilateral LSCD possess residual LSCs. However, it remains unknown whether these residual LSCs still have stem cell potential due to the lack of animal models that mimic this pathology. The goal of the current study is to make a complete LSCD model that possesses evidence of residual LSCs. We induced complete LSCD in mice using two methods: (1) removed the corneal epithelium and the epithelial basement membrane using a rotating burr, and (2) removed the corneal epithelium using 20% ethanol but retained an intact epithelial basement membrane. A complete LSCD was defined by a lack of CK12-positive corneal epithelial cells and the presence of infiltrating CK19-positive conjunctival epithelial cells. Corneas were examined for wound closure, corneal opacity, LSC exhaustion, and inflammation. We observed that complete LSCD mice without an intact epithelial basement membrane resulted in few residual LSCs. By contrast, complete LSCD mice that retained the epithelial basement membrane were accompanied by a reduced inflammatory response plus a significant number of residual LSCs. This model will allow future studies to determine the function of residual LSCs in complete LSCD.

cell biology↗

bioRxiv2021

Opposing roles of blood-borne monocytes and tissue-resident macrophages in limbal stem cell damage after ocular injury

Limbal stem cell (LSC) deficiency is a frequent and severe complication after chemical injury to the eye. Previous studies have assumed that this is mediated directly by the caustic agent. Here we show that LSC damage occurs through immune cell mediators, even without direct injury to LSCs. In particular, pH elevation in the anterior chamber (AC) causes acute uveal stress, release of inflammatory cytokines at the basal limbal tissue, and subsequent LSC loss. Peripheral CCR2+ CX3CR1- monocytes are the key mediators of LSC damage, through the upregulation of tumor necrosis factor alpha (TNF-) at the limbus. In contrast to peripherally-derived monocytes, CX3CR1+ CCR2- tissue-resident macrophages have a protective role and their depletion prior to injury exacerbates LSC loss and increases LSC vulnerability to TNF--mediated apoptosis independently of CCR2+ cell infiltration into the tissue. Consistently, repopulation of the tissue by new resident macrophages not only restores the protective M2-like phenotype of macrophages but also suppresses LSC loss after exposure to inflammatory signals. These findings may have clinical implication in patient with chemical burns. SignificanceLimbal stem cell (LSC) loss after chemical burn is a significant clinical problem that has long been thought to be the result of direct chemical injury. This study demonstrates the existence of competing inflammatory mechanism responsible for LSC death, mediated by infiltrating peripheral monocytes that antagonize and overcome the protective role of tissue-resident macrophages. Thus, enhancing the role of tissue-resident macrophages while suppressing that of infiltrating monocytes could be a novel therapeutic strategy for LSC survival.

immunology↗

bioRxiv2018

Neuroglial Remodeling After Various Ocular Injuries is Regulated by Microglia

Reactive microglia and infiltrating peripheral monocytes have been implicated in many neurodegenerative diseases of the retina and central nervous system (CNS). However, their specific contribution in retinal degeneration remains unclear. We recently showed that peripheral monocytes that infiltrate the retina after ocular injury in mice become permanently engrafted into the tissue, establishing a pro-inflammatory phenotype that promotes neurodegeneration. Here, we show in mice that microglia regulate the process of neuroglia remodeling during ocular injury, and their depletion results in marked upregulation of inflammatory markers, such as Il17f, Tnfsf11, Ccl4, Il1a, Ccr2, Il4, Il5, and Csf2 in the retina, abnormal engraftment of peripheral CCR2+ CX3CR1+ monocytes into the retina and is associated with increased retinal ganglion cell (RGC) loss, retinal nerve fiber layer thinning, and RPE65+ cell migration onto the retinal surface. Furthermore, we show that other types of ocular injuries, such as penetrating corneal trauma and ocular hypertension, also cause similar changes. However, optic nerve crush injury mediated RGC loss evokes neither peripheral monocyte response in the retina, nor RPE65+ cell migration, although peripheral CX3CR1+ and CCR2+ monocytes infiltrate the optic nerve injury site and remain present for months. Our study suggests that microglia are key regulators of peripheral monocyte infiltration and RPE migration and their depletion results in abnormal neuroglia remodeling that exacerbates neuroretinal tissue damage. This mechanism of retinal damage through neuroglia remodeling may be clinically important for the treatment of patients with ocular injuries, including surgical traumas.

immunology↗

bioRxiv2018

Permanent neuroglial remodeling of the retina following infiltration of CSF1R-inhibition resistant peripheral monocytes.

Previous studies have demonstrated that ocular injury can lead to prompt infiltration of bone marrow-derived peripheral monocytes into the retina. However, the ability of these cells to integrate into the tissue and become microglia has not been studied. Here we show that such peripheral monocytes not only infiltrate into the retina after ocular injury, but that they engraft permanently, migrate to the three distinct microglia strata, and adopt a microglia-like morphology. However, contrary to the original microglia, after injury the engrafted peripheral monocytes are resistant to depletion by colony stimulating factor 1 receptor (CSF1R) inhibitor and remain pro-inflammatory, expressing high levels of major histocompatibility complex II (MHC-II) for long-term. In the absence of ocular injury, on the other hand, the peripheral monocytes that repopulate the retina after CSF1R inhibition remain sensitive to CSF1R inhibition and can be re-depleted. The observed permanent neuroglia remodeling after injury constitutes a major immunological deviation that may contribute to progressive retinal degeneration. These findings may be relevant also to other degenerative conditions of the retina and central nervous system.

immunology↗