Astrocytic junctional adhesion molecule-A regulates T-cell entry past the glia limitans to promote central nervous system autoimmune attack.

Contact-mediated interactions between the astrocytic endfeet and infiltrating immune cells within the perivascular space are underexplored, yet represent potential regulatory check-points against CNS autoimmune disease and disability. Reactive astrocytes upregulate junctional adhesion molecule-A, an immunoglobulin-like cell surface receptor that binds to T cells via its ligand, the integrin, lymphocyte function-associated antigen-1. Here, we tested the role of astrocytic junctional adhesion molecule-A in regulating CNS autoinflammatory disease. In cell co-cultures, we found that junctional adhesion molecule-A-mediated signalling between astrocytes and T cells increases levels of matrix metalloproteinase-2, C-C motif chemokine ligand 2 and granulocyte-macrophage colony-stimulating factor, pro-inflammatory factors driving lymphocyte entry and pathogenicity in multiple sclerosis and experimental autoimmune encephalomyelitis, an animal model of CNS autoimmune disease. In experimental autoimmune encephalomyelitis, mice with astrocyte-specific JAM-A deletion (mGFAP:CreJAM-Afl/fl ) exhibit decreased levels of matrix metalloproteinase-2, reduced ability of T cells to infiltrate the CNS parenchyma from the perivascular spaces and a milder histopathological and clinical course of disease compared with wild-type controls (JAM-Afl/fl ). Treatment of wild-type mice with intraperitoneal injection of soluble junctional adhesion molecule-A blocking peptide decreases the severity of experimental autoimmune encephalomyelitis, highlighting the potential of contact-mediated astrocyte-immune cell signalling as a novel translational target against neuroinflammatory disease.

A novel three-dimensional printed device to improve the safety of trocar insertion in hypotonous eyes.

The force required for trocar insertion in hypotonous eyes can cause significant deformation of the globe and result in an iatrogenic injury to the lens, posterior capsule, or retina from the sharp trocar tip. We developed a device designed to stabilize the globe and provide counterpressure without significant globe deformation during trocar insertion. Our novel device was modeled using computer-aided design software, three-dimensional (3D) printed, and validated in an ex vivo porcine model. The risk of trocar-retinal touch was evaluated by comparing the distance between the trocar tip and opposing retina with either a cotton swab or our 3D printed device. We found an increased distance between the retina and trocar tip at the time of trocar insertion using our novel device: 3.3 ± 1.3 mm (P = 0.035), suggesting an improved safety margin. This device has the potential to improve the safety of trocar insertion in eyes at risk of trocar-associated injury, including hypotonous, previously vitrectomized, and nanophthalmic eyes.

Pediatric Vitreoretinal Surgery and Integrated Intraoperative Optical Coherence Tomography.

Intraoperative portable handheld and microscope-integrated OCT enhance the pediatric vitreoretinal surgeon's diagnostic abilities during examination under anesthesia and surgery, particularly in children who are challenging to examine preoperatively due to young age or ocular trauma. Improved OCT-guided visualization of vitreoretinal anatomic relationships has the potential to improve surgical safety and efficiency. In retinopathy of prematurity and other pediatric retinal vascular conditions, intraoperative OCT can be critical for distinguishing between retinoschisis and retinal detachment and highlighting abnormalities of the vitreoretinal interface that may contribute to development of tractional retinal detachments. During retinal detachment repair, intraoperative OCT aids identification of subtle retinal breaks, residual subretinal fluid, retained perfluorocarbon, preretinal membranes, and residual hyaloid, among other findings. In macular surgery, intraoperative OCT has demonstrated value in confirming completion or lack thereof of epiretinal and internal limiting membrane peeling and differentiating between lamellar and full-thickness macular holes. OCT-guided subretinal bleb formation and genetic vector delivery are critical to ensuring accurate localization of subretinal gene delivery for inherited retinal degenerations. Research on development of OCT-compatible surgical instruments, real-time three-dimensional volumetric OCT imaging, and integration with intraoperative OCT angiography are anticipated to further increase the utility of intraoperative OCT in pediatric vitreoretinal surgical decision-making.

Clinicopathologic correlation of aniridia: Optical coherence tomography angiography and histopathologic observations.

PURPOSE: To describe optical coherence tomography angiography (OCTA) findings in a patient with aniridia and correlate with representative histopathology. OBSERVATIONS: OCTA images of the macula of a pediatric aniridic patient, who has nystagmus and impaired vision bilaterally, demonstrate a complete absence of the foveal avascular zone (FAZ) in both the superficial and deep vascular complexes (SVC and DVC). In addition, larger superficial blood vessels were found to be abnormally diving from the SVC into the DVC. Similarly, immunofluorescence with confocal microscopy imaging of a retinal histopathology specimen from a 2 month old aniridic patient demonstrated larger vessels diving in the same manner. CONCLUSIONS AND IMPORTANCE: This study highlights the clinical, imaging and histopathologic findings of aniridia. Supine OCTA imaging, performed during examination under anesthesia, allowed for visualization of retinal microvasculature in eyes with nystagmus. The histopathology images helped validate OCTA findings that, with further investigation, may lead to new information about the development of abnormal retinal microvasculature.

Optical coherence tomography imaging of the pediatric retina.

Optical coherence tomography is an increasingly important part of the retinal specialist's and general ophthalmologist's toolkit for diagnosing and managing retinal disease. This review summarizes the unique considerations and available imaging systems with which pediatric ophthalmologists should be familiar when attempting optical coherence tomography in children. Normal developmental changes in foveal and extrafoveal structure and the need for an established pediatric normative database of retinal thicknesses are reviewed. Finally, applications of optical coherence tomography imaging to selected representative pediatric retinal diseases are introduced as examples of how optical coherence tomography in children is furthering the diagnosis and management of vision-threatening retinal diseases.

Improving Tolerance and Compliance with Topical Immunomodulators Using Micro-Emulsion Lipid Layer Artificial Tears.

PURPOSE: To investigate the efficacy of a micro-emulsion (ME) lipid layer artificial tear in improving tolerance of immunomodulator eye drops for the treatment of dry eye disease. PATIENTS AND METHODS: A total of 33 patients with previously diagnosed dry eye disease were given the micro-emulsion lipid layer artificial tear in conjunction with either lifitegrast or cyclosporine. Patients were queried on their tolerance of the regimen by reporting VAS scores before starting the adjunctive eye drop, immediately after starting, and 2-3 weeks later. Tolerance was statistically compared over time and with respect to previous medication compliance, timing of the adjunctive eye drop, age, gender, and ethnicity. RESULTS: Across all patients, the VAS pre-treatment score (6.8 ± 0.6) was significantly higher than both the VAS 1-day post ME lipid tear instillation time point (3.0 ± 0.7) (post hoc Bonferroni, p < 0.001) and the VAS 2-3-week post instillation time point (1.7 ± 0.7) (post hoc Bonferroni, p < 0.001), with the mean VAS score improving over time (post hoc Bonferroni, p < 0.028). Average VAS scores did not vary with respect to specific medical therapy or the timing of instillation of this artificial tear. Both the "at-risk" and "conversion" groups independently had significant improvements at both 1-day and 2-3-week time points compared to baseline. CONCLUSION: The micro-emulsion lipid layer artificial tear was effective as an adjunctive eye drop to improve tolerance of lifitegrast and cyclosporine for patients with dry eye disease who were at risk of failing or had previously failed immunomodulatory therapy.

Recent developments in pediatric retina.

PURPOSE OF REVIEW: Pediatric retina is an exciting, but also challenging field, where patient age and cooperation can limit ease of diagnosis of a broad range of congenital and acquired diseases, inherited retinal degenerations are mostly untreatable and surgical outcomes can be quite different from those for adults. This review aims to highlight some recent advances and trends that are improving our ability to care for children with retinal conditions. RECENT FINDINGS: Studies have demonstrated the feasibility of multimodal imaging even in nonsedated infants, with portable optical coherence tomography (OCT) and OCT angiography in particular offering structural insights into diverse pediatric retinal conditions. Encouraging long-term outcomes of subretinal voretigene neparvovec-rzyl injection for RPE65 mutation-associated Leber congenital amaurosis have inspired research on the optimization of subretinal gene delivery and gene therapy for other inherited retinal degenerations. In retinopathy of prematurity, machine learning and smartphone-based imaging can facilitate screening, and studies have highlighted favorable outcomes from intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections. A nomogram for pediatric pars plana sclerotomy site placement may improve safety in complex surgeries. SUMMARY: Multimodal imaging, gene therapy, machine learning and surgical innovation have been and will continue to be important to advances in pediatric retina.

Distinct Neuronal Projections From the Hypothalamic Ventromedial Nucleus Mediate Glycemic and Behavioral Effects.

The hypothalamic ventromedial nucleus (VMN) is implicated both in autonomic control of blood glucose and in behaviors including fear and aggression, but whether these divergent effects involve the same or distinct neuronal subsets and their projections is unknown. To address this question, we used an optogenetic approach to selectively activate the subset of VMN neurons that express neuronal nitric oxide synthase 1 (VMNNOS1 neurons) implicated in glucose counterregulation. We found that photoactivation of these neurons elicits 1) robust hyperglycemia achieved by activation of counterregulatory responses usually reserved for the physiological response to hypoglycemia and 2) defensive immobility behavior. Moreover, we show that the glucagon, but not corticosterone, response to insulin-induced hypoglycemia is blunted by photoinhibition of the same neurons. To investigate the neurocircuitry by which VMNNOS1 neurons mediate these effects, and to determine whether these diverse effects are dissociable from one another, we activated downstream VMNNOS1 projections in either the anterior bed nucleus of the stria terminalis (aBNST) or the periaqueductal gray (PAG). Whereas glycemic responses are fully recapitulated by activation of VMNNOS1 projections to the aBNST, freezing immobility occurred only upon activation of VMNNOS1 terminals in the PAG. These findings support previous evidence of a VMN→aBNST neurocircuit involved in glucose counterregulation and demonstrate that activation of VMNNOS1 neuronal projections supplying the PAG robustly elicits defensive behaviors.

Astrocytic tight junctions control inflammatory CNS lesion pathogenesis.

Lesions and neurologic disability in inflammatory CNS diseases such as multiple sclerosis (MS) result from the translocation of leukocytes and humoral factors from the vasculature, first across the endothelial blood-brain barrier (BBB) and then across the astrocytic glia limitans (GL). Factors secreted by reactive astrocytes open the BBB by disrupting endothelial tight junctions (TJs), but the mechanisms that control access across the GL are unknown. Here, we report that in inflammatory lesions, a second barrier composed of reactive astrocyte TJs of claudin 1 (CLDN1), CLDN4, and junctional adhesion molecule A (JAM-A) subunits is induced at the GL. In a human coculture model, CLDN4-deficient astrocytes were unable to control lymphocyte segregation. In models of CNS inflammation and MS, mice with astrocyte-specific Cldn4 deletion displayed exacerbated leukocyte and humoral infiltration, neuropathology, motor disability, and mortality. These findings identify a second inducible barrier to CNS entry at the GL. This barrier may be therapeutically targetable in inflammatory CNS disease.