Abstract: Primary vitreoretinal lymphoma (PVRL), as a subset of primary central nervous system lymphoma (PCNSL), is a rare and fatal ocular malignancy. Most PVRL masquerades as chronic posterior uveitis, which makes the clinical diagnosis challenging. Vitreous cells, subretinal lesions and imaging techniques are essential for clinical diagnosis. Importantly, cytopathology/histopathology identification of malignant cells is the gold standard for the diagnosis of PVRL. In addition, molecular detection of immunoglobulin heavy chain (IgH) or T cell receptor (TCR) gene rearrangements, immunophenotyping for cell markers, and cytokine analysis of interleukine-10 elevation are often used as adjunct procedures. Current management of PVRL involves local radiation, intravitreal chemotherapy (methotrexate and rituximab), with or without systemic chemotherapy depending on the involvement of non-ocular tissues. In cases with concomitant PCNSL, systemic high-dose methotrexate/rituximab based therapy in conjunction with local therapy, whole brain radiotherapy and/or autologous stem cell transplantation is considered. Although PVRL normally responds well to initial treatment, high rates of relapse and CNS involvement usually lead to poor prognosis and limited survival. A professional team of medical experts in ophthalmologists, ocular pathologists, neuro-oncologists and hemato-oncologists is essential for optimizing patient management.

Abstract: Dopamine is known as a key molecule in retinal signaling pathways regulating visually guided eye growth, as evidenced by reduced retinal dopamine levels in various species when experimental myopia is generated. However, in C57BL/6 mice our recent work demonstrated that neither retinal dopamine levels, retinal tyrosine hydroxylase (rate-limiting enzyme in dopamine synthesis) levels, nor dopaminergic amacrine cell density/morphology, were altered during the development of form-deprivation myopia (FDM). These results suggest that retinal dopamine is unlikely associated with FDM development in this mouse strain. The role of dopamine in refractive development was further explored in this mouse strain when retinal dopamine levels were reduced by intravitreal injections of 6-OHDA, a neurotoxin that specifically destroys dopaminergic neurons. The dose was so chosen that retinal dopamine levels were reduced, but no significant changes in electroretinographic responses were detected. 6-OHDA induced significant myopic shifts in refraction in a dose-dependent manner, suggesting the involvement of dopamine in normal refractive development. Biometric measurements of ocular dimensions revealed that 6-OHDA resulted in a shorter axial length and a steeper cornea, while form-deprivation led to a longer axial length without changing the corneal radius of curvature. These results strongly suggest that in addition to the dopamine-independent mechanism, a dopamine-dependent mechanism works for refractive development. We have obtained evidence, suggesting that the dopamine-independent mechanism might be related to intrinsically photosensitive retinal ganglion cells (ipRGCs). Firstly, selective ablation of ipRGCs with an immunotoxin resulted in myopic shifts in refraction. Secondly, form-deprivation induced less myopic shifts in animals with ipRGC ablation.

Abstract: Blinding diseases such as photoreceptor degenerations are debilitating conditions that severely impair daily lives of affected patients. This group of diseases are amenable to photoreceptor replacement therapies and recent transplantation studies provided proof-of-principle for functional recovery at the retinal and behavioral level, though the actual mechanism of repair still needs further investigations. The immune system responds in several ways upon photoreceptor engraftment, resulting in T-cell and macrophage infiltrations and, consequently, decrease in graft survival. Most studies on the role of the immune system suggest a detrimental effect in a therapeutic setting. Conversely, the opposite idea wherein the immune system can be activated towards a protective state was also explored in other experimental paradigms. Here, Neves and colleagues explored the potential of cross-species studies and, to a certain extent, the concept of a protective immune system in retinal degeneration and therapy. Mesencephalic astrocyte-derived neurotrophic factor (MANF) was identified in this study as a novel factor that, by modulating the immune system, can slow down photoreceptor degeneration and improve transplantation outcome.

Background: Because of its superficial anatomical localization, the cornea is particularly vulnerable to abrasive forces and various traumas, which can lead to significant visual impairments. Upon injury of the corneal epithelium, there are important changes that occur in the composition of the underlying extracellular matrix (ECM). Those changes are perceived by the integrins that recognize the ECM components as their ligand and activate different intracellular signalling pathways, ultimately leading to reepithelialisation and reorganization of the injured epithelium, both of which are necessary in order to restore the visual properties of the cornea. The goal of this study was to analyse the impact of the pharmacological inhibition of specific signal transduction mediators of integrin-dependant signalling pathways on corneal wound healing using both monolayers of hCECs and tissue-engineered human corneas (hTECs) as in vitro models.

Methods: hTECs were produced by the self-assembly approach and wounded with a 8-mm diameter biopsy punch. Total RNA and proteins were isolated from the wounded and unwounded hTECs to conduct gene profiling analyses and protein kinase arrays. The wounded tissues were then incubated with the WNK1 inhibitor WNK463 and wound healing was monitored over a period of 6 days. Control corneas were incubated with the vehicle alone (DMSO). The impact of WNK1 inhibition on hCECs monolayers was determined using a scratch wound assay.

Results: Gene profiling analyses and protein kinases arrays revealed important alterations in the expression and activity of several mediators from the integrin-dependent signalling pathways in response to the ECM changes taking place during corneal wound healing. Among these, WNK1 is considerably activated through phosphorylation during corneal wound healing. The pharmacological inhibition of WNK1 by WNK463 significantly reduced the dynamic of corneal wound closure in our hTECs and hCECs monolayers compared to their respective negative controls.

Conclusions: These results allowed the identification of WNK1 kinase as an important player for a proper healing of the cornea. Also, these results allowed for a better understanding of the cellular and molecular mechanisms involved in corneal wound healing and they may lead to the identification of new therapeutic targets in the field of corneal wounds.

Background: Pericytes are contractile cells that wrap along the walls of capillaries. In the brain, pericytes play a crucial role in the regulation of capillary diameter and vascular blood flow in response to metabolic demand. During ischemia, it has been suggested that pericytes may constrict capillaries, and that pericytes remain constricted after reperfusion thus resulting in impaired blood flow.

Methods: Here, we used a mouse model of retinal ischemia based on ligation of the central retinal artery to characterize the role of pericytes on capillary constriction. Ischemia was induced in transgenic mice carrying the NG2 promoter driving red fluorescent protein expression to selectively visualize pericytes (line NG2:DsRed).Changes in retinal capillary diameter at 1 hr after ischemia were measured ex vivo in whole-mounted retinas from ischemic and control eyes (n=4–6/group) using a stereological approach. Vessels and pericytes were three-dimensionally reconstructed using IMARIS (Bitplane). Furthermore, we used a novel and minimally invasive two-photon microscopy approach that allowed live imaging of microvasculature changes in the retina.

Results: Our data show a generalized reduction in capillary diameter in ischemic retinas relative to sham-operated controls in all vascular plexus (ischemia: 4.7±0.2 μm, control: 5.2±0.2 μm, student’s t-test, P<0.001). Analysis of the number of capillary constrictions at pericyte locations, visualized in NG2:DsRed mice, demonstrated a substantial increase in ischemic retinas relative to the physiological capillary diameter reductions observed in controls (ischemia: 1,038±277 constrictions at pericyte locations, control: 60±36 constrictions at pericyte locations, student’s t-test, P<0.01). Live imaging using two-photon microscopy confirmed robust capillary constriction at the level of pericytes on retinal capillaries during ischemia (n=6–8/group).

Conclusions: Collectively, our data demonstrate that ischemia promotes rapid pericyte constriction on retinal capillaries causing major microvascular dysfunction in this tissue. To identify the molecular mechanisms underlying the pathological response of pericytes during ischemia, we are currently carrying out experiments in mice and zebrafish to modulate signaling pathways involved in calcium dynamics leading to contractility in these cells.

Abstract: Cornea serves as the partial front barrier and major light reflection organ of the eye. The integrity of corneal surface is essential for ocular function. Injuries or congenital diseases could significantly destruct the homeostasis of the ocular surface, especially the microenvironment of limbal epithelial stem cells (LESCs), and will eventually cause dysfunction of corneal regeneration and diminish of LESCs. The loss of LESCs by different reasons are named limbal stem cell deficiency (LSCD), which is one of the leading cause of vision loss worldwide. To restore the corneal surface, LESC transplantation in the form of tissue or cell cultures is currently a viable and promising method to treat LSCD. In this review, we aim to introduce the characters and niche of LESCs, and discuss different aspects of its application in cornea surface reconstruction.

Abstract: Animal models are crucial for the study of tumorigenesis and therapies in oncology research. Though rare, uveal melanoma (UM) is the most common intraocular tumor and remains one of the most lethal cancers. Given the limitations of studying human UM cells in vitro, animal models have emerged as excellent platforms to investigate disease onset, progression, and metastasis. Since Greene’s initial studies on hamster UM, researchers have dramatically improved the array of animal models. Animals with spontaneous tumors have largely been replaced by engrafted and genetically engineered models. Inoculation techniques continue to be refined and expanded. Newer methods for directed mutagenesis have formed transgenic models to reliably study primary tumorigenesis. Human UM cell lines have been used to generate rapidly growing xenografts. Most recently, patient-derived xenografts have emerged as models that closely mimic the behavior of human UM. Separate animal models to study metastatic UM have also been established. Despite the advancements, the prognosis has only recently improved for UM patients, especially in patients with metastases. There is a need to identify and evaluate new preclinical models. To accomplish this goal, it is important to understand the origin, methods, advantages, and disadvantages of current animal models. In this review, the authors present current and historic animal models for the experimental study of UM. The strengths and shortcomings of each model are discussed and potential future directions are explored.