A novel interaction between RNA m6A methyltransferase METTL3 and RREB1.

Regulation of gene expression is achieved through the modulation of regulatory inputs both pre- and post-transcriptionally. Methyltransferase-like 3 (METTL3) is a key player in pre-mRNA processing, actively catalyzing N6-methyladenosine (m6A). Among the most enriched mRNA targets of METTL3 is the Ras Responsive Element Binding Protein 1 (RREB1), a transcription factor which functions to govern cell fate, proliferation and DNA repair. Here, we show a novel interaction between METTL3 and RREB1. Further examination of this interaction indicates that METTL3's N-terminus is the primary interacting domain. Our findings uncover a novel interacting partner of METTL3, providing further insights into METTL3's regulatory network.

Liquid Biopsy for Proliferative Diabetic Retinopathy: Single-Cell Transcriptomics of Human Vitreous Reveals Inflammatory T-Cell Signature.

Purpose: Current therapies for proliferative diabetic retinopathy (PDR) do not specifically target VEGF-independent, cell-type-specific processes that lead to vision loss, such as inflammatory pathways. This study aimed to identify targetable cell types and corresponding signaling pathways by elucidating the single-cell landscape of the vitreous of patients with PDR. Design: Case series. Subjects: Vitreous and peripheral blood obtained from 5 adult patients (6 eyes) undergoing pars plana vitrectomy for vision-threatening PDR. Methods: Single-cell RNA sequencing (scRNA-seq) was performed on vitreous cells obtained from diluted cassette washings during vitrectomy from 6 eyes and peripheral blood mononuclear cells (PBMCs, n = 5). Droplet-based scRNA-seq was performed using the Chromium 10x platform to obtain single-cell transcriptomes. Differences in tissue compartments were analyzed with gene ontology enrichment of differentially expressed genes and an unbiased ligand-receptor interaction analysis. Main Outcome Measures: Single-cell transcriptomic profiles of vitreous and peripheral blood. Results: Transcriptomes from 13 675 surgically harvested vitreous cells and 22 636 PBMCs were included. Clustering revealed 4 cell states consistently across all eyes with representative transcripts for T cells (CD2, CD3D, CD3E, and GZMA), B cells (CD79A, IGHM, MS4A1 (CD20), and HLA-DRA), myeloid cells (LYZ, CST3, AIF1, and IFI30), and neutrophils (BASP1, CXCR2, S100A8, and S100A9). Most vitreous cells were T cells (91.6%), unlike the peripheral blood (46.2%), whereas neutrophils in the vitreous were essentially absent. The full repertoire of adaptive T cells including CD4+, CD8+ and T regulatory cells (Treg) and innate immune system effectors (i.e., natural killer T cells) was present in the vitreous. Pathway analysis also demonstrated activation of CD4+ and CD8+ memory T cells and ligand-receptor interactions unique to the vitreous. Conclusions: In the first single-cell transcriptomic characterization of human vitreous in a disease state, we show PDR vitreous is primarily composed of T cells, a critical component of adaptive immunity, with activity and proportions distinct from T cells within the peripheral blood, and neutrophils are essentially absent. These results demonstrate the feasibility of liquid vitreous biopsies via collection of otherwise discarded, diluted cassette washings during vitrectomy to gain mechanistic and therapeutic insights into human vitreoretinal disease. Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Posterior Uveitis in Ocular-Involving Chronic Lymphocytic Leukemia and the Utility of Negative MYD88 L265P Testing in the Diagnosis.

Introduction: The aim of this study was to investigate if a negative test result for MYD88 L265P mutation, associated with vitreoretinal lymphoma (VRL) and primary CNS lymphoma, in liquid biopsies from intraocular fluids can be a useful adjuvant test to diagnose chronic lymphocytic leukemia in clinically challenging cases. Case Presentations: We selected patients with a past medical history or examinations findings suspicious for intraocular lymphoma. We evaluated both vitreous and aqueous humor-derived (AHD) MYD88 L265P mutation from patients that had suspected intraocular lymphoma that warranted a liquid biopsy procedure. Gold-standard cytopathology, flow cytometry, and gene rearrangement studies were also performed. All 4 patients had negative AHD MYD88 L265P mutation testing. Gold-standard testing (cytology) either showed paucicellular specimens (1/4) or specimens with high background inflammation (3/4). One case showed a rare B-cell clonal population (CD5+, Kappa-restricted by flow cytometry), but this was not sufficient to make any definitive diagnosis. All patients were subsequently initiated on systemic therapy and had improvement in their disease burden. Conclusions: Negative AHD MYD88 L265P mutation testing can serve as an adjuvant molecular test to diagnose difficult cases of intraocular CLL.

Quiescence enables unrestricted cell fate in naive embryonic stem cells.

Quiescence in stem cells is traditionally considered as a state of inactive dormancy or with poised potential. Naive mouse embryonic stem cells (ESCs) can enter quiescence spontaneously or upon inhibition of MYC or fatty acid oxidation, mimicking embryonic diapause in vivo. The molecular underpinning and developmental potential of quiescent ESCs (qESCs) are relatively unexplored. Here we show that qESCs possess an expanded or unrestricted cell fate, capable of generating both embryonic and extraembryonic cell types (e.g., trophoblast stem cells). These cells have a divergent metabolic landscape comparing to the cycling ESCs, with a notable decrease of the one-carbon metabolite S-adenosylmethionine. The metabolic changes are accompanied by a global reduction of H3K27me3, an increase of chromatin accessibility, as well as the de-repression of endogenous retrovirus MERVL and trophoblast master regulators. Depletion of methionine adenosyltransferase Mat2a or deletion of Eed in the polycomb repressive complex 2 results in removal of the developmental constraints towards the extraembryonic lineages. Our findings suggest that quiescent ESCs are not dormant but rather undergo an active transition towards an unrestricted cell fate.

Cell-Free DNA Extraction of Vitreous and Aqueous Humor Specimens for Diagnosis and Monitoring of Vitreoretinal Lymphoma.

Vitreoretinal lymphoma (VRL) represents an aggressive lymphoma, often categorized as primary central nervous system diffuse large B-cell lymphoma. To diagnose VRL, specimens such as vitreous humor and, more recently, aqueous humor are collected. Diagnostic testing for VRL on these specimens includes cytology, flow cytometry, and molecular testing. However, both cytopathology and flow cytometry, along with molecular testing using cellular DNA, necessitate intact whole cells. The challenge lies in the fact that vitreous and aqueous humor typically have low cellularity, and many cells get destroyed during collection, storage, and processing. Moreover, these specimens pose additional difficulties for molecular testing due to the high viscosity of vitreous humor and the low volume of both vitreous and aqueous humor. This study proposes a method for extracting cell-free DNA from vitreous and aqueous specimens. This approach complements the extraction of cellular DNA or allows the cellular component of these specimens to be utilized for other diagnostic methods, including cytology and flow cytometry.

RHEGMATOGENOUS RETINAL DETACHMENT AFTER INITIATION OF PILOCARPINE HYDROCHLORIDE OPHTHALMIC SOLUTION 1.25% FOR TREATMENT OF PRESBYOPIA.

BACKGROUND/PURPOSE: Retinal detachment has previously been reported in association with topical miotic use for the treatment of glaucoma. Pilocarpine hydrochloride 1.25% was recently approved by the Food and Drug Administration for the treatment of presbyopia, with no reports of associated retinal detachments in the clinical trial data. METHODS: Case report. RESULTS: Two novel cases of unilateral retinal detachment occurring within 10 days of the initiation of pilocarpine 1.25% for the treatment of presbyopia were described. The patients were pseudophakic men in their 60s or 70s with preexisting retinal detachment risk factors, such as high myopia, lattice degeneration, and prior retinal detachment. Both affected eyes were treated with pars plana vitrectomy and gas endotamponade with an uncomplicated postoperative course. CONCLUSION: Retinal detachment may be associated with the use of pilocarpine 1.25%. Caution should be used when considering prescribing this medication in patients with preexisting retinal abnormality.

Molecular Analysis of Liquid Vitreous Biopsy Reveals Occult Lymphoma Following Cytology-Negative Biopsies of the Brain and Vitreous.

PURPOSE: Primary central nervous system lymphoma (PCNSL) is a rare but deadly malignancy that principally affects adults in the fifth and sixth decades of life. Despite diagnostic advances in analyses of cerebral spinal fluid and neuroimaging, definitive diagnosis of PCNSL requires primary brain tissue biopsy. While small neurosurgical biopsy volumes are pursued to minimize removal of normal brain tissue, the spatial margins to precisely biopsy pathologic tissue are narrow and can result in missed diagnoses. Furthermore, prior steroid treatment can significantly reduce tumor burden increasing the likelihood of a non-diagnostic biopsy. METHODS: A retrospective case report from a tertiary referral center using a combination of neuroradiological studies, sterotactic tissue biopsy, and molecular testing for genome mutations. RESULTS: A 72-year-old woman with strong suspicion for PCNSL clinically and radiologically, but cerebral spinal fluid and primary brain tissue biopsy were negative for tumor. However, vitreous liquid biopsy molecular testing for a MYD88 mutation as well as B-cell clonality (IGH/IGK rearrangement) were positive, indicating the presence of secondary vitreoretinal lymphoma from PCNSL. Only after autopsy of her brain was histopathological and immunohistochemical evidence of PCNSL confirmed. CONCLUSION: This case illustrates the unique contribution of liquid biopsy neuropathology-oriented molecular testing in a challenging case with high clinical suspicion of PCNSL in which gold-standard diagnostic testing failed to yield a diagnosis.

The Cost of Standard and Complex Pars Plana Vitrectomy for Retinal Detachment Repair Exceeds Its Reimbursement.

OBJECTIVE: To measure the total costs and reimbursements associated with standard and complex pars plana vitrectomy using time-driven activity-based costing (TDABC). DESIGN: Economic analysis at a single academic institution. SUBJECTS: Patients who underwent standard or complex pars plana vitrectomy (PPV; Current Procedural Terminology codes 67108 and 67113) at the University of Michigan in the calendar year 2021. METHODS: Process flow mapping for standard and complex PPVs was used to determine the operative components. The internal anesthesia record system was used to calculate time estimates, and financial calculations were constructed from published literature and internal sources. A TDABC analysis was used to determine the costs of standard and complex PPVs. Average reimbursement was based on Medicare rates. MAIN OUTCOME MEASURES: The primary outcomes were the total costs for standard and complex PPVs and the resulting net margin at current Medicare reimbursement levels. The secondary outcomes were the differential in surgical times, costs, and margin for standard and complex PPV. RESULTS: Over the 2021 calendar year, a total of 270 standard and 142 complex PPVs were included in the analysis. Complex PPVs were associated with significantly increased anesthesia time (52.28 minutes; P < 0.001), operating room time (51.28 minutes; P < 0.0001), surgery time (43.64 minutes; P < 0.0001), and postoperative time (25.95 minutes; P < 0.0001). The total day-of-surgery costs were $5154.59 and $7852.38 for standard and complex PPVs, respectively. Postoperative visits incurred an additional cost of $327.84 and $353.86 for standard and complex PPV, respectively. The institution-specific facility payments were $4505.50 and $4935.14 for standard and complex PPV, respectively. Standard PPV yielded a net negative margin of -$976.93, whereas complex PPV yielded a net negative margin of -$3271.10. CONCLUSIONS: This analysis demonstrated that Medicare reimbursement is inadequate in covering the costs of PPV for retinal detachment, with a particularly large negative margin for more complex cases. These findings demonstrate that additional steps may be necessary to mitigate adverse economic incentives so that patients continue to have timely access to care to achieve optimal visual outcomes after retinal detachment. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

Patient Perceptions of Retinal Detachment Management and Recovery through Social Media.

PURPOSE: Social media support groups can provide accessibility to advice and emotional regarding medical topics, such as retinal detachment repair, but this is almost universally provided by laypersons. We sought to determine how topics related to retinal detachment repair are associated with various emotional responses and the spread of misinformation, as identified through an online social media support group. METHODS: Retrospective observational study of the largest Facebook support group for retinal detachment from 03/19/2021 to 07/19/2021. Members of the support group that posted during the study period. Comments were coded by content (Pre-procedural, Peri-procedural Post procedural, Repeat procedures) and participant response (Emotional responses, Asking for medical advice, and Misinformation). Associations between content and responses were examined using Pearson's chi-squared test, two-sample t-test, and linear regression. RESULTS: Posts that included written comments from the study period were analyzed. Negative emotional responses appeared in 30% of posts and positive emotional responses were in 16% of posts. Misinformation was more likely to appear in pre-procedure posts (5.3% versus 1.4%, p = .03). Negative emotional responses trended towards being more common in topics related to repeat procedures (40% vs 28%), although this did not reach statistical significance (p = .06). CONCLUSIONS: Surgeons should be aware that patients frequently express negative experiences on this forum, asked for medical advice, even in the post-operative period, and that these posts generated high engagement. Misinformation may be propagated in support groups, though less commonly with regard to post-procedural questions.

Lessons learnt, and still to learn, in first in human stem cell trials.

Developing cellular therapies is not straightforward. This Perspective summarizes the experience of a group of academic stem cell investigators working in different clinical areas and aims to share insight into what we wished we knew before starting. These include (1) choosing the stem cell line and assessing the genome of both the starting and final product, (2) familiarity with GMP manufacturing, reagent validation, and supply chain management, (3) product delivery issues and the additional regulatory challenges, (4) the relationship between clinical trial design and preclinical studies, and (5) the market approval requirements, pathways, and partnerships needed.

Aqueous Humor-Derived MYD88 L265P Mutation Analysis in Vitreoretinal Lymphoma: A Potential Less Invasive Method for Diagnosis and Treatment Response Assessment.

PURPOSE: To investigate whether MYD88 L265P mutation, which is frequently present in vitreoretinal lymphoma, can be detected in aqueous humor, a specimen that can be obtained in a clinic setting, potentially mitigating the need for more invasive vitrectomy procedures, and whether this approach can be used to monitor treatment response. DESIGN: Observational case series. SUBJECTS: Patients who were diagnosed with biopsy-confirmed or clinically diagnosed vitreoretinal lymphoma or biopsy-confirmed vitritis. METHODS: We evaluated aqueous humor-derived (AHD) MYD88 L265P mutation during vitreous biopsy or at the initial presentation in the clinic if vitreous biopsy was not feasible. Demographic or clinical features of patients were retrospectively reviewed. Aqueous humor-derived MYD88 L265P mutation was re-evaluated after patients completed a course of intravitreal methotrexate and rituximab injection therapy. The NM_002468.4: c.794T>C (p.L265P) mutation in the MYD88 gene was evaluated in AHD cellular and cell-free DNA using allele-specific polymerase chain reaction. MAIN OUTCOME MEASURES: Detection of AHD MYD88 L265P mutation at the initial diagnosis and to monitor the treatment response. RESULTS: Aqueous humor from 18 eyes of 14 patients with biopsy-confirmed or clinically diagnosed vitreoretinal lymphoma and 3 eyes of 3 patients with biopsy-confirmed vitritis were evaluated. Aqueous humor-derived MYD88 L265P mutation was detected in cell-based and cell-free DNA from 15 (83%) of 18 eyes with biopsy-confirmed or clinically diagnosed vitreoretinal lymphoma but not identified in any of the 3 eyes with vitritis. The mutation was less readily detectable in cellular DNA (10 of 18) compared with cell-free DNA (15 of 18). Furthermore, aqueous sampling after intravitreal methotrexate and rituximab injection therapy revealed absence of this mutation after complete response in 7 eyes. The mutation was detected in 1 eye that developed recurrence in a posttreatment window of 6 months. After a mean of follow-up of 9 months, there was no clinical evidence of vitreoretinal lymphoma recurrence in the 7 eyes with no detectable AHD MYD88 L265P mutation. CONCLUSIONS: This investigational study suggests that AHD MYD88 L265P can be detected in eyes with lymphoma and may thus serve as a surrogate, less invasive biopsy in the diagnosis and follow-up of vitreoretinal lymphoma, particularly when cell-free DNA is evaluated.

The eyeball's connected to the brain ball.

How does the human eye develop in concert with the brain to create a functioning visual system? In this issue of Cell Stem Cell, Gabriel et al. (2021) report the development of eye-like structures from forebrain organoids with light sensitivity, signal processing, and connectivity, which moves us toward answering this complex question.

Assessing patient perception of risk in ocular stem cell therapies.

A wide variety of stem cell-derived therapies are under development for the treatment of retinal degeneration. In order to better understand patient perspectives about these therapies, we assessed risk tolerance using an in-person survey of 178 patients at an academic eye center. Risk of malignancy served as a hypothetical, readily understood, and serious adverse event to be considered in trade for potential visual improvement from a stem cell-derived treatment. The results indicate that patients were willing to trade visual improvement against a risk of malignancy that far exceeds actual risk. Two novel findings were that older patients and those with an intermediate level of visual loss were particularly risk tolerant. The quantitative survey results provide a step toward understanding patient perspectives that will, over the long term, guide the development of ocular stem cell-derived therapies.

p53 inactivation unmasks histone methylation-independent WDR5 functions that drive self-renewal and differentiation of pluripotent stem cells.

p53 alterations occur during culture of pluripotent stem cells (PSCs), but the significance of these events on epigenetic control of PSC fate determination remains poorly understood. Wdr5 deletion in p53-null (DKO) mouse ESCs (mESCs) leads to impaired self-renewal, defective retinal neuroectoderm differentiation, and de-repression of germ cell/meiosis (GCM)-specific genes. Re-introduction of a WDR5 mutant with defective H3K4 methylation activity into DKO ESCs restored self-renewal and suppressed GCM gene expression but failed to induce retinal neuroectoderm differentiation. Mechanistically, mutant WDR5 targets chromatin that is largely devoid of H3K4me3 and regulates gene expression in p53-null mESCs. Furthermore, MAX and WDR5 co-target lineage-specifying chromatin and regulate chromatin accessibility of GCM-related genes. Importantly, MAX and WDR5 are core subunits of a non-canonical polycomb repressor complex 1 responsible for gene silencing. This function, together with canonical, pro-transcriptional WDR5-dependent MLL complex H3K4 methyltransferase activity, highlight how WDR5 mediates crosstalk between transcription and repression during mESC fate choice.