Honors & Awards
Career-Starter Research Grant, Knights Templar Eye Foundation (2023)
Healthcare 30 Under 30, Forbes (2021)
National Eye Institute T32 Postdoctoral Fellowship, Stanford University (2021)
STAT Wunderkind, STAT News (2020)
Magna Cum Laude, Harvard Medical School (2020)
Research Award, VitreoRetinal Surgery Foundation (2020)
Elizabeth D. Hay Prize for Basic Science Research, Harvard Medical School (2019)
Travel Grant Award, Association for Research in Vision and Ophthalmology (2019)
HHMI Medical Research Fellowship, Howard Hughes Medical Institute (2018)
J.E. Wallace Sterling Award for Scholastic Achievement, Stanford University (2014)
Bachelor of Science, Stanford University, BIO-BSH (2014)
Bachelor of Science, Stanford University, CRWRIT-MIN (2014)
Doctor of Medicine, Harvard University (2020)
Residency, Stanford Ophthalmology Advanced Research Residency (2021-2025)
Internship, Cambridge Health Alliance (2020-2021)
M.D., Harvard Medical School (2015-2020)
B.S., Stanford University (2011-2014)
High temporal frequency light response in mouse retina is mediated by ON and OFF bipolar cells and requires FAT3 signaling.
bioRxiv : the preprint server for biology
Vision is initiated by the reception of light by photoreceptors and subsequent processing via parallel retinal circuits. Proper circuit organization depends on the multi-functional tissue polarity protein FAT3, which is required for amacrine cell connectivity and retinal lamination. Here we investigated the retinal function of Fat3 mutant mice and found decreases in physiological and perceptual responses to high frequency flashes. These defects did not correlate with abnormal amacrine cell wiring, pointing instead to a role in bipolar cell subtypes that also express FAT3. Indeed, similar deficits were observed in mice lacking the bipolar cell glutamate receptors GRIK1 (OFF-bipolar cells) and GRM6 (ON-bipolar cells). Mechanistically, FAT3 binds to the synaptic protein PTPsigma and is required to localize GRIK1 to OFF-cone bipolar cell synapses with cone photoreceptors. How FAT3 impacts ON-cone bipolar cell function at high temporal frequency remains to be uncovered. These findings expand the repertoire of FAT3's functions and reveal the importance of both ON- and OFF-bipolar cells for high frequency light response.
View details for DOI 10.1101/2023.11.02.565326
View details for PubMedID 37961274
Charge-altering releasable transporters enhance mRNA delivery in vitro and exhibit in vivo tropism.
2023; 14 (1): 6983
The introduction of more effective and selective mRNA delivery systems is required for the advancement of many emerging biomedical technologies including the development of prophylactic and therapeutic vaccines, immunotherapies for cancer and strategies for genome editing. While polymers and oligomers have served as promising mRNA delivery systems, their efficacy in hard-to-transfect cells such as primary T lymphocytes is often limited as is their cell and organ tropism. To address these problems, considerable attention has been placed on structural screening of various lipid and cation components of mRNA delivery systems. Here, we disclose a class of charge-altering releasable transporters (CARTs) that differ from previous CARTs based on their beta-amido carbonate backbone (bAC) and side chain spacing. These bAC-CARTs exhibit enhanced mRNA transfection in primary T lymphocytes in vitro and enhanced protein expression in vivo with highly selective spleen tropism, supporting their broader therapeutic use as effective polyanionic delivery systems.
View details for DOI 10.1038/s41467-023-42672-x
View details for PubMedID 37914693
Telemedicine retinopathy of prematurity severity score (TeleROP-SS) versus modified activity score (mROP-ActS) retrospective comparison in SUNDROP cohort.
2023; 13 (1): 15219
Identifying and planning treatment for retinopathy of prematurity (ROP) using telemedicine is becoming increasingly ubiquitous, necessitating a grading system to help caretakers of at-risk infants gauge disease severity. The modified ROP Activity Scale (mROP-ActS) factors zone, stage, and plus disease into its scoring system, addressing the need for assessing ROP's totality of binocular burden via indirect ophthalmoscopy. However, there is an unmet need for an alternative score which could facilitate ROP identification and gauge disease improvement or deterioration specifically on photographic telemedicine exams. Here, we propose such a system (Telemedicine ROP Severity Score [TeleROP-SS]), which we have compared against the mROP-ActS. In our statistical analysis of 1568 exams, we saw that TeleROP-SS was able to return a score in all instances based on the gradings available from the retrospective SUNDROP cohort, while mROP-ActS obtained a score of 80.8% in right eyes and 81.1% in left eyes. For treatment-warranted ROP (TW-ROP), TeleROP-SS obtained a score of 100% and 95% in the right and left eyes respectively, while mROP-ActS obtained a score of 70% and 63% respectively. The TeleROP-SS score can identify disease improvement or deterioration on telemedicine exams, distinguish timepoints at which treatments can be given, and it has the adaptability to be modified as needed.
View details for DOI 10.1038/s41598-023-42150-w
View details for PubMedID 37709791
Chromophore supply modulates cone function and survival in retinitis pigmentosa mouse models.
Proceedings of the National Academy of Sciences of the United States of America
2023; 120 (23): e2217885120
Retinitis pigmentosa (RP) is an ocular disease characterized by the loss of night vision, followed by the loss of daylight vision. Daylight vision is initiated in the retina by cone photoreceptors, which are gradually lost in RP, often as bystanders in a disease process that initiates in their neighboring rod photoreceptors. Using physiological assays, we investigated the timing of cone electroretinogram (ERG) decline in RP mouse models. A correlation between the time of loss of the cone ERG and the loss of rods was found. To investigate a potential role of the visual chromophore supply in this loss, mouse mutants with alterations in the regeneration of the retinal chromophore, 11-cis retinal, were examined. Reducing chromophore supply via mutations in Rlbp1 or Rpe65 resulted in greater cone function and survival in a RP mouse model. Conversely, overexpression of Rpe65 and Lrat, genes that can drive the regeneration of the chromophore, led to greater cone degeneration. These data suggest that abnormally high chromophore supply to cones upon the loss of rods is toxic to cones, and that a potential therapy in at least some forms of RP is to slow the turnover and/or reduce the level of visual chromophore in the retina.
View details for DOI 10.1073/pnas.2217885120
View details for PubMedID 37252956
Single-cell multiomics of human RPE and choroid in health and AMD
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2023
View details for Web of Science ID 001053758305129
Validation of a Photographic Retinopathy of Prematurity Severity Score (ROP-SS) and Comparison to the Modified Activity Score (mROP-ActS) in a Retrospective SUNDROP Cohort
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2023
View details for Web of Science ID 001053795601300
Effective field of view of wide-field fundus photography in the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP).
2022; 12 (1): 19276
Five-field 130° wide-angle imaging is the standard of care for retinopathy of prematurity (ROP) screening with an ideal hypothetical composite field-of-view (FOV) of 180°. We hypothesized that in many real-world scenarios the effective composite FOV is considerably less than ideal. This observational retrospective study analyzed the effective FOV of fundus photos of patients screened for ROP as part of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) initiative. Five fundus photos were selected from each eye per image session. Effective FOV was defined as the largest circular area centered on the optic disc that encompassed retina in each of the four cardinal views. Seventy-three subjects were analyzed, 35 without ROP and 34 with ROP. Mean effective FOV was 144.55±6.62° ranging from 130.00 to 153.71°. Effective FOV was not correlated with the presence or absence of ROP, gestational age, birth weight, or postmenstrual age. Mean effective FOV was wider in males compared to females. Standard five-field 130° fundus photos yielded an average effective FOV of 144.54° in the SUNDROP cohort. This implies that an imaging FOV during ROP screening considerably less than the hypothetical ideal of 180° is sufficient for detecting treatment warranted ROP.
View details for DOI 10.1038/s41598-022-22964-w
View details for PubMedID 36369465
Single-cell multiome of the human retina and deep learning nominate causal variants in complex eye diseases.
2022; 2 (8)
Genome-wide association studies (GWASs) of eye disorders have identified hundreds of genetic variants associated with ocular disease. However, the vast majority of these variants are noncoding, making it challenging to interpret their function. Here we present a joint single-cell atlas of gene expression and chromatin accessibility of the adult human retina with more than 50,000 cells, which we used to analyze single-nucleotide polymorphisms (SNPs) implicated by GWASs of age-related macular degeneration, glaucoma, diabetic retinopathy, myopia, and type 2 macular telangiectasia. We integrate this atlas with a HiChIP enhancer connectome, expression quantitative trait loci (eQTL) data, and base-resolution deep learning models to predict noncoding SNPs with causal roles in eye disease, assess SNP impact on transcription factor binding, and define their known and novel target genes. Our efforts nominate pathogenic SNP-target gene interactions for multiple vision disorders and provide a potentially powerful resource for interpreting noncoding variation in the eye.
View details for DOI 10.1016/j.xgen.2022.100164
View details for PubMedID 36277849
Engineering circular RNA for enhanced protein production.
Circular RNAs (circRNAs) are stable and prevalent RNAs in eukaryotic cells that arise from back-splicing. Synthetic circRNAs and some endogenous circRNAs can encode proteins, raising the promise of circRNA as a platform for gene expression. In this study, we developed a systematic approach for rapid assembly and testing of features that affect protein production from synthetic circRNAs. To maximize circRNA translation, we optimized five elements: vector topology, 5' and 3' untranslated regions, internal ribosome entry sites and synthetic aptamers recruiting translation initiation machinery. Together, these design principles improve circRNA protein yields by several hundred-fold, provide increased translation over messenger RNA in vitro, provide more durable translation in vivo and are generalizable across multiple transgenes.
View details for DOI 10.1038/s41587-022-01393-0
View details for PubMedID 35851375
Modeling absolute zone size in retinopathy of prematurity in relation to axial length.
2022; 12 (1): 4717
Treatment outcomes in retinopathy of prematurity (ROP) are closely correlated with the location (i.e. zone) of disease, with more posterior zones having poorer outcomes. The most posterior zone, Zone I, is defined as a circle centered on the optic nerve with radius twice the distance from nerve to fovea, or subtending an angle of 30 degrees. Because the eye enlarges and undergoes refractive changes during the period of ROP screening, the absolute area of Zone I according to these definitions may likewise change. It is possible that these differences may confound accurate assessment of risk in patients with ROP. In this study, we estimated the area of Zone I in relation to different ocular parameters to determine how variability in the size and refractive power of the eye may affect zoning. Using Gaussian optics, a model was constructed to calculate the absolute area of Zone I as a function of corneal power, anterior chamber depth, lens power, lens thickness, and axial length (AL), with Zone I defined as a circle with radius set by a 30-degree visual angle. Our model predicted Zone I area to be most sensitive to changes in AL; for example, an increase of AL from 14.20 to 16.58mm at postmenstrual age 32weeks was calculated to expand the area of Zone I by up to 72%. These findings motivate several hypotheses which upon future testing may help optimize treatment decisions for ROP.
View details for DOI 10.1038/s41598-022-08680-5
View details for PubMedID 35304549
Targeting Microglia to Treat Degenerative Eye Diseases.
Frontiers in immunology
2022; 13: 843558
Microglia have been implicated in many degenerative eye disorders, including retinitis pigmentosa, age-related macular degeneration, glaucoma, diabetic retinopathy, uveitis, and retinal detachment. While the exact roles of microglia in these conditions are still being discovered, evidence from animal models suggests that they can modulate the course of disease. In this review, we highlight current strategies to target microglia in the eye and their potential as treatments for both rare and common ocular disorders. These approaches include depleting microglia with chemicals or radiation, reprogramming microglia using homeostatic signals or other small molecules, and inhibiting the downstream effects of microglia such as by blocking cytokine activity or phagocytosis. Finally, we describe areas of future research needed to fully exploit the therapeutic value of microglia in eye diseases.
View details for DOI 10.3389/fimmu.2022.843558
View details for PubMedID 35251042
Augmentation of CD47-SIRPalpha signaling protects cones in genetic models of retinal degeneration.
Inherited retinal diseases such as retinitis pigmentosa (RP) can be caused by thousands of different mutations, a small number of which have been successfully treated with gene replacement. However, this approach has yet to scale and may not be feasible in many cases, highlighting the need for interventions that could benefit more patients. Here, we found that microglial phagocytosis is upregulated during cone degeneration in RP, suggesting that expression of "don't eat me" signals such as CD47 might confer protection to cones. To test this, we delivered an adeno-associated viral (AAV) vector expressing CD47 on cones, which promoted cone survival in three mouse models of RP and preserved visual function. Cone rescue with CD47 required a known interacting protein, signal regulatory protein alpha (SIRPalpha), but not an alternative interacting protein, thrombospondin-1 (TSP1). Despite the correlation between increased microglial phagocytosis and cone death, microglia were dispensable for the pro-survival activity of CD47, suggesting that CD47 interacts with SIRPalpha on non-microglial cells to alleviate degeneration. These findings establish augmentation of CD47-SIRPalpha signaling as a potential treatment strategy for RP and possibly other forms of neurodegeneration.
View details for DOI 10.1172/jci.insight.150796
View details for PubMedID 34197341
AAV-Txnip prolongs cone survival and vision in mouse models of retinitis pigmentosa
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2021
View details for Web of Science ID 000690761600297
AAV-Txnip prolongs cone survival and vision in mouse models of retinitis pigmentosa
Retinitis pigmentosa (RP) is an inherited retinal disease affecting >20 million people worldwide. Loss of daylight vision typically occurs due to the dysfunction/loss of cone photoreceptors, the cell type that initiates our color and high-acuity vision. Currently, there is no effective treatment for RP, other than gene therapy for a limited number of specific disease genes. To develop a disease gene-agnostic therapy, we screened 20 genes for their ability to prolong cone photoreceptor survival in vivo. Here, we report an adeno-associated virus vector expressing Txnip, which prolongs the survival of cone photoreceptors and improves visual acuity in RP mouse models. A Txnip allele, C247S, which blocks the association of Txnip with thioredoxin, provides an even greater benefit. Additionally, the rescue effect of Txnip depends on lactate dehydrogenase b (Ldhb) and correlates with the presence of healthier mitochondria, suggesting that Txnip saves RP cones by enhancing their lactate catabolism.
View details for DOI 10.7554/eLife.66240
View details for Web of Science ID 000645438300001
View details for PubMedID 33847261
View details for PubMedCentralID PMC8081528
Engineering adeno-associated viral vectors to evade innate immune and inflammatory responses
SCIENCE TRANSLATIONAL MEDICINE
2021; 13 (580)
Nucleic acids are used in many therapeutic modalities, including gene therapy, but their ability to trigger host immune responses in vivo can lead to decreased safety and efficacy. In the case of adeno-associated viral (AAV) vectors, studies have shown that the genome of the vector activates Toll-like receptor 9 (TLR9), a pattern recognition receptor that senses foreign DNA. Here, we engineered AAV vectors to be intrinsically less immunogenic by incorporating short DNA oligonucleotides that antagonize TLR9 activation directly into the vector genome. The engineered vectors elicited markedly reduced innate immune and T cell responses and enhanced gene expression in clinically relevant mouse and pig models across different tissues, including liver, muscle, and retina. Subretinal administration of higher-dose AAV in pigs resulted in photoreceptor pathology with microglia and T cell infiltration. These adverse findings were avoided in the contralateral eyes of the same animals that were injected with the engineered vectors. However, intravitreal injection of higher-dose AAV in macaques, a more immunogenic route of administration, showed that the engineered vector delayed but did not prevent clinical uveitis, suggesting that other immune factors in addition to TLR9 may contribute to intraocular inflammation in this model. Our results demonstrate that linking specific immunomodulatory noncoding sequences to much longer therapeutic nucleic acids can "cloak" the vector from inducing unwanted immune responses in multiple, but not all, models. This "coupled immunomodulation" strategy may widen the therapeutic window for AAV therapies as well as other DNA-based gene transfer methods.
View details for DOI 10.1126/scitranslmed.abd3438
View details for Web of Science ID 000617688400006
View details for PubMedID 33568518
Nrf2 overexpression rescues the RPE in mouse models of retinitis pigmentosa
2021; 6 (2)
Nrf2, a transcription factor that regulates the response to oxidative stress, has been shown to rescue cone photoreceptors and slow vision loss in mouse models of retinal degeneration (rd). The retinal pigment epithelium (RPE) is damaged in these models, but whether it also could be rescued by Nrf2 has not been previously examined. We used an adeno-associated virus (AAV) with an RPE-specific (Best1) promoter to overexpress Nrf2 in the RPE of rd mice. Control rd mice showed disruption of the regular array of the RPE, as well as loss of RPE cells. Cones were lost in circumscribed regions within the cone photoreceptor layer. Overexpression of Nrf2 specifically in the RPE was sufficient to rescue the RPE, as well as the disruptions in the cone photoreceptor layer. Electron microscopy showed compromised apical microvilli in control rd mice but showed preserved microvilli in Best1-Nrf2-treated mice. The rd mice treated with Best1-Nrf2 had slightly better visual acuity. Transcriptome profiling showed that Nrf2 upregulates multiple oxidative defense pathways, reversing declines seen in the glutathione pathway in control rd mice. In summary, Nrf2 overexpression in the RPE preserves RPE morphology and survival in rd mice, and it is a potential therapeutic for diseases involving RPE degeneration, including age-related macular degeneration (AMD).
View details for DOI 10.1172/jci.insight.145029
View details for Web of Science ID 000613769000020
View details for PubMedID 33491671
View details for PubMedCentralID PMC7934854
In Situ Detection of Adeno-associated Viral Vector Genomes with SABER-FISH
MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT
2020; 19: 376-386
Gene therapy with recombinant adeno-associated viral (AAV) vectors is a promising modality for the treatment of a variety of human diseases. Nonetheless, there remain significant gaps in our understanding of AAV vector biology, due in part to the lack of robust methods to track AAV capsids and genomes. In this study, we describe a novel application of signal amplification by exchange reaction fluorescence in situ hybridization (SABER-FISH) that enabled the visualization and quantification of individual AAV genomes after vector administration in mice. These genomes could be seen in retinal cells within 3 h of subretinal AAV delivery, were roughly full length, and correlated with vector expression in both photoreceptors and the retinal pigment epithelium. SABER-FISH readily detected AAV genomes in the liver and muscle following retro-orbital and intramuscular AAV injections, respectively, demonstrating its utility in different tissues. Using SABER-FISH, we also found that retinal microglia, a cell type deemed refractory to AAV transduction, are in fact efficiently infected by multiple AAV serotypes, but appear to degrade AAV genomes prior to nuclear localization. Our findings show that SABER-FISH can be used to visualize AAV genomes in situ, allowing for studies of AAV vector biology and the tracking of transduced cells following vector administration.
View details for DOI 10.1016/j.omtm.2020.10.003
View details for Web of Science ID 000598181600033
View details for PubMedID 33209963
View details for PubMedCentralID PMC7658570
Microglia modulation by TGF-beta 1 protects cones in mouse models of retinal degeneration
JOURNAL OF CLINICAL INVESTIGATION
2020; 130 (8): 4360-4369
Retinitis pigmentosa (RP) is a genetically heterogenous group of eye diseases in which initial degeneration of rods triggers secondary degeneration of cones, leading to significant loss of daylight, color, and high-acuity vision. Gene complementation with adeno-associated viral (AAV) vectors is one strategy to treat RP. Its implementation faces substantial challenges, however; for example, the tremendous number of loci with causal mutations. Gene therapy targeting secondary cone degeneration is an alternative approach that could provide a much-needed generic treatment for many patients with RP. Here, we show that microglia are required for the upregulation of potentially neurotoxic inflammatory factors during cone degeneration in RP, creating conditions that might contribute to cone dysfunction and death. To ameliorate the effects of such factors, we used AAV vectors to express isoforms of the antiinflammatory cytokine transforming growth factor beta (TGF-β). AAV-mediated delivery of TGF-β1 rescued degenerating cones in 3 mouse models of RP carrying different pathogenic mutations. Treatment with TGF-β1 protected vision, as measured by 2 behavioral assays, and could be pharmacologically disrupted by either depleting microglia or blocking the TGF-β receptors. Our results suggest that TGF-β1 may be broadly beneficial for patients with cone degeneration, and potentially other forms of neurodegeneration, through a pathway dependent upon microglia.
View details for DOI 10.1172/JCI136160
View details for Web of Science ID 000579423900004
View details for PubMedID 32352930
View details for PubMedCentralID PMC7410072
Meeting the need for corrective spectacles in visually impaired Chinese school children: the potential of ready-made spectacles
BRITISH JOURNAL OF OPHTHALMOLOGY
2019; 103 (8): 1106-1111
To assess the potential of ready-made (spherical) spectacles (RMS) in meeting the need for refractive correction in visually impaired children in China.Eligible children aged 5-17 years were identified from the three study sites in China. Distance visual acuity was measured with a retroilluminated logarithm of the minimum angle of resolution chart with tumbling E optotypes. Cycloplegic autorefraction was performed on all children using a handheld autorefractor. If uncorrected visual acuity (UCVA) was ≤20/40 in either eye, best corrected visual acuity was measured with subjective refractive error. RESULTS : A total of 13 702 children were enumerated from the three studies, with 12 334 (90.0%) having both reliable visual acuity measurements and successful cycloplegia. Among the 12 334 study children, the prevalence of UCVA ≤20/40 in the better seeing eye was 16.4% (95% CI 15.0% to 17.8%), with 91.1% (1843) of these improving by ≥3 lines of visual acuity with refractive correction. Prevalence was 12.7% (95% CI 11.5% to 13.9%) for UCVA <20/50 with 97.4% (1521) improving by ≥3 lines, and 9.38% (95% CI 8.39% to 19.4%) for UCVA ≤20/63 with 98.4% (1138) improving by ≥3 lines. Depending on the severity of visual impairment, 62.8%-64.0% of children could be accommodated with RMS if not correcting for astigmatism of ≤0.75 dioptres and anisometropia of ≤0.50 spherical equivalent dioptres. Approximately 87% of children could be accommodated with RMS if astigmatism and anisometropia limits were increased to ≤1.25 and ≤1.50 dioptres, respectively.RMS could substantially alleviate visual morbidity in two-thirds or more of visually impaired schoolchildren in China. This cost-effective approach to refractive correction might also be useful in low/middle-income countries with poor access to optometric services.
View details for DOI 10.1136/bjophthalmol-2018-312262
View details for Web of Science ID 000478915300016
View details for PubMedID 30279277
View details for PubMedCentralID PMC6678143
Circumventing cellular immunity by miR142-mediated regulation sufficiently supports rAAV-delivered OVA expression without activating humoral immunity
2019; 4 (13)
Recombinant adeno-associated virus (rAAV)-mediated gene delivery can efficiently target muscle tissues to serve as "biofactories" for secreted proteins in prophylactic and therapeutic scenarios. Nevertheless, efficient rAAV-mediated gene delivery is often limited by host immune responses against the transgene product. The development of strategies to prevent anti-transgene immunity is therefore crucial. The employment of endogenous microRNA (miRNA)-mediated regulation to detarget transgene expression from antigen presenting cells (APCs) has shown promise for reducing immunogenicity. However, the mechanisms underlying miRNA-mediated modulation of anti-transgene immunity by APC detargeting are not fully understood. Using the highly immunogenic ovalbumin (OVA) protein as a proxy for foreign antigens, we show that rAAV vectors containing miR142 binding sites efficiently repress co-stimulatory signals in dendritic cells, significantly blunt the cytotoxic T cell response, allow for sustained transgene expression in skeletal myoblasts, and attenuate clearance of transduced muscle cells in mice. Furthermore, the blunting of humoral immunity against circulating OVA correlates with detargeting of OVA expression from APCs. This demonstrates that incorporating APC-specific miRNA binding sites into rAAV vectors provides an effective strategy for reducing transgene-specific immune response. This approach holds promise for clinical applications where the safe and efficient delivery of a prophylactic or therapeutic protein is desired.
View details for DOI 10.1172/jci.insight.99052
View details for Web of Science ID 000474918000025
View details for PubMedID 31112525
View details for PubMedCentralID PMC6629123
Soluble CX3CL1 gene therapy improves cone survival and function in mouse models of retinitis pigmentosa
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2019; 116 (20): 10140-10149
Retinitis pigmentosa (RP) is a disease that initially presents as night blindness due to genetic deficits in the rod photoreceptors of the retina. Rods then die, causing dysfunction and death of cone photoreceptors, the cell type that mediates high acuity and color vision, ultimately leading to blindness. We investigated immune responses in mouse models of RP and found evidence of microglia activation throughout the period of cone degeneration. Using adeno-associated vectors (AAVs), delivery of genes encoding microglial regulatory signals led to the identification of AAV serotype 8 (AAV8) soluble CX3CL1 (sCX3CL1) as a promising therapy for degenerating cones. Subretinal injection of AAV8-sCX3CL1 significantly prolonged cone survival in three strains of RP mice. Rescue of cones was accompanied by improvements in visual function. AAV8-sCX3CL1 did not affect rod survival, microglia localization, or inflammatory cytokine levels in the retina. Furthermore, although RNA sequencing of microglia demonstrated marked transcriptional changes with AAV8-sCX3CL1, pharmacological depletion of up to ∼99% of microglia failed to abrogate the effect of AAV8-sCX3CL1 on cone survival. These findings indicate that AAV8-sCX3CL1 can rescue cones in multiple mouse models of RP via a pathway that does not require normal numbers of microglia. Gene therapy with sCX3CL1 is a promising mutation-independent approach to preserve vision in RP and potentially other forms of retinal degeneration.
View details for DOI 10.1073/pnas.1901787116
View details for Web of Science ID 000467804000068
View details for PubMedID 31036641
View details for PubMedCentralID PMC6525490
AAV cis-regulatory sequences are correlated with ocular toxicity
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2019; 116 (12): 5785-5794
Adeno-associated viral vectors (AAVs) have become popular for gene therapy, given their many advantages, including their reduced inflammatory profile compared with that of other viruses. However, even in areas of immune privilege such as the eye, AAV vectors are capable of eliciting host-cell responses. To investigate the effects of such responses on several ocular cell types, we tested multiple AAV genome structures and capsid types using subretinal injections in mice. Assays of morphology, inflammation, and physiology were performed. Pathological effects on photoreceptors and the retinal pigment epithelium (RPE) were observed. Müller glia and microglia were activated, and the proinflammatory cytokines TNF-α and IL-1β were up-regulated. There was a strong correlation between cis-regulatory sequences and toxicity. AAVs with any one of three broadly active promoters, or an RPE-specific promoter, were toxic, while AAVs with four different photoreceptor-specific promoters were not toxic at the highest doses tested. There was little correlation between toxicity and transgene, capsid type, preparation method, or cellular contaminants within a preparation. The toxic effect was dose-dependent, with the RPE being more sensitive than photoreceptors. Our results suggest that ocular AAV toxicity is associated with certain AAV cis-regulatory sequences and/or their activity and that retinal damage occurs due to responses by the RPE and/or microglia. By applying multiple, sensitive assays of toxicity, AAV vectors can be designed so that they can be used safely at high dose, potentially providing greater therapeutic efficacy.
View details for DOI 10.1073/pnas.1821000116
View details for Web of Science ID 000461679000086
View details for PubMedID 30833387
View details for PubMedCentralID PMC6431174
Mineralocorticoid Receptor Antagonists in Central Serous Chorioretinopathy: A Meta-Analysis of Randomized Controlled Trials.
2019; 3 (2): 154-160
TOPIC: A meta-analysis comparing mineralocorticoid receptor (MR) antagonists (eplerenone or spironolactone) versus observation or placebo in the treatment of central serous chorioretinopathy (CSCR) based on best-corrected visual acuity (BCVA) and subretinal fluid (SRF) level data from randomized controlled trials (RCTs).CLINICAL RELEVANCE: Central serous chorioretinopathy patients may demonstrate decreased visual acuity, reduced contrast sensitivity, scotomas, and metamorphopsia. Although multiple treatment options for CSCR have been proposed, compelling evidence for any particular method is still lacking.METHODS: Three databases (PubMed, EMBASE, and BIOSIS) were searched for potentially relevant records as of March 2018. Of 114 unique studies identified, 5 RCTs comparing BCVA with either eplerenone or spironolactone versus observation or placebo were included. The quality of articles was assessed according to the Cochrane Risk of Bias Tool, with any discrepancies resolved by author consensus.RESULTS: A total of 145 eyes of patients with CSCR were included in the meta-analysis. Compared with placebo or observation, MR antagonist treatment showed a significant positive effect on BCVA after both 1 month (weighted mean difference [WMD], -0.05 logarithm of the minimum angle of resolution [logMAR]; 95% confidence interval [CI], -0.07 to -0.02 logMAR; Z= 3.94; P < 0.0001) and 2 months (WMD, -0.10 logMAR; 95% CI, -0.14 to -0.06 logMAR; Z= 4.69; P < 0.00001). Mineralocorticoid receptor antagonist treatment also significantly reduced SRF height in CSCR at 1 month (WMD, -81.15 mum; 95% CI, -148.25 to -14.05 mum; Z= 2.37; P=0.02). However, this effect was no longer significant at 2 months (WMD, -58.63 mum; 95% CI, -155.40 to 38.13 mum; Z= 1.19; P= 0.23). None of the patients in the 5 trials withdrew because of adverse effects, and blood electrolyte levels, including potassium, remained normal in all cases.CONCLUSIONS: Our findings suggest a modest benefit with MR antagonist therapy for CSCR patients in improving BCVA. We anticipate that MR antagonists will be well tolerated by most CSCR patients and that barriers to starting a trial of these medications in nonresolving CSCR should be low.
View details for DOI 10.1016/j.oret.2018.09.003
View details for PubMedID 31014765
Incidence of and Factors Associated With Myopia and High Myopia in Chinese Children, Based on Refraction Without Cycloplegia
2018; 136 (9): 1017-1024
Myopia has reached epidemic levels among children in regions of East and Southeast Asia. High myopia is associated with myopic macular degeneration, glaucoma, and retinal detachment.To determine the incidence of myopia and high myopia based on refraction without cycloplegia among children in primary and junior high schools in China.This observational cohort study was completed in Guangzhou, China. It consisted of a cohort from 19 primary schools, who were followed up from 2010 to 2015, and a cohort from 22 junior high schools, who were followed up from 2010 to 2012. All schools were randomly chosen at rates proportional to the number of schools in each of the city's 11 districts. Students with or without myopia in grade 1 (primary school) or grade 7 (junior high school) were eligible for inclusion. Data analysis occurred from February 2017 to October 2017.Myopia was defined as a spherical equivalent refraction (SER) of -0.50 diopters (D) or less, as measured by subjective refraction without cycloplegia; high myopia was defined as a SER of -6.0 D or less. Annual incidences were defined as the proportion of participants each year found to have myopia or high myopia who did not previously have the condition. Height, weight, axial length (AL), corneal radius of curvature (CRC), and AL/CRC ratio were examined to assess if these measures were associated with future myopia or high myopia.A total of 4741 students with or without myopia in either grade 1 for the primary school cohort (mean [SD] age 7.2 [0.4] years; 932 of 1975 [47.2%] female) or grade 7 for the junior high school cohort (mean [SD] age 13.2 [0.5] years; 1254 of 2670 [47.0%] female) were included. Baseline mean (SD) SER was 0.31 (0.86) D among 1975 students in grade 1 vs -1.60 (2.00) D among 2670 students in grade 7. Baseline prevalence of myopia was 12.0% in grade 1 students (n = 237 of 1969) and 67.4% in grade 7 students (n = 1795 of 2663). The incidence of myopia was 20% to 30% each year throughout both cohorts. The incidence of high myopia was initially less than 1% in the primary school cohort (grade 1: n = 2 of 1825; 0.1% [95% CI, 0.0%-0.3%]), but incidence exceeded 2% in the junior high school cohort (in grade 9: n = 48 of 2044; 2.3% [95% CI, 1.0%-3.7%]).The incidence of myopia among Chinese students based on refraction without cycloplegia is among the highest of any cultural or ethnic group. If confirmed with cycloplegic refraction, interventions to prevent myopia onset in Chinese populations should be initiated in primary schools.
View details for DOI 10.1001/jamaophthalmol.2018.2658
View details for Web of Science ID 000444641800015
View details for PubMedID 29978185
View details for PubMedCentralID PMC6142978
Qualitative and quantitative assessment of posterior segment optical coherence tomography images using standard photos: the Liwan Eye Study
2017; 7 (12): e017923
To develop a standardised grading scheme, using standard photos, for spectral-domain ocular coherence tomography (SD-OCT) images of the posterior eye and evaluate the interobserver agreement among trained ophthalmologists in identifying pathological changes.Subjects were recruited from Liwan District, Guangzhou, with SD-OCT data collection from June 2013 to November 2013 as part of 10-year follow-up visits from the Liwan Eye Study. All subjects underwent SD-OCT imaging of the macula with scanning lines analysed by two ophthalmologists to assess for the presence of 12 different posterior segment lesions. Per cent agreement for each lesion between the graders and quantitative measures of dome-shaped macula (DSM) height and choroidal thickness were calculated.A total of 679 SD-OCT images from 679 subjects were independently evaluated by the two graders. Each of the 12 lesions was successfully graded as present or absent in over 96% of images. For all lesions, per cent agreement between observers was over 90%, ranging from 90.7% for epiretinal membranes and retinal pigment epithelium thickenings to 99.7% for full thickness macular holes and retinal detachments. Quantitative measurements of DSM height and choroidal thickness at three locations of the eye all exhibited intraclass correlation scores between the two graders of greater than 0.9.Our study demonstrates high concordance between graders in characterising posterior segment lesions using SD-OCT images, validating the continued use of this imaging modality in the diagnosis of posterior eye disease.
View details for DOI 10.1136/bmjopen-2017-017923
View details for Web of Science ID 000423826700087
View details for PubMedID 29275341
View details for PubMedCentralID PMC5770917
Trends in Hospitalization and Incidence Rate for Syphilitic Uveitis in the United States from 1998-2009.
American journal of ophthalmology
This study evaluates the annual incidence of syphilitic uveitis in the US and trends in hospital admissions over time.Retrospective, longitudinal incidence rate analysis of the National Inpatient Sample (NIS) data from 1998 to 2009.The NIS is a de-identified, random sample dataset of inpatient hospitalizations from 46 states. The number of cases of syphilitic uveitis was defined by (1) International Classification of Diseases, 9th Revision (ICD-9) code for syphilis and uveitis or (2) ICD-9 code for syphilitic uveitis. Annual case count, incidence rate, and trend over time were calculated. Multivariate logistic regression was used to evaluate associated factors for a syphilitic uveitis diagnosis.The study included 455 310 286 hospitalizations during a 12-year study period with a mean of 37 942 524 patients annually. Syphilis and uveitis was recorded for 1861 patients (155 annually) and syphilitic uveitis was diagnosed in 204 subjects (average of 17 cases annually). There was no change in the incidence of syphilitic uveitis, using either definition, over the study period (P for trend = .46). The mean annual incidence of syphilis and uveitis was 0.0004%, or 4 per million. Syphilitic uveitis had an annual incidence of 0.000045%, or 0.45 per million. The odds of syphilitic uveitis were lower among women (odds ratio [OR] 0.40, CI 0.28-0.57) and increased with comorbid acquired immunodeficiency syndrome (OR 4.52, CI 3.01-6.79).We report the first incidence of syphilitic uveitis in the United States. Fortunately, this remains a rare condition. The results demonstrate no change in the number of inpatient admissions for syphilitic uveitis during the study period.
View details for DOI 10.1016/j.ajo.2017.05.013
View details for PubMedID 28549847
Comparison of Peristat Online Perimetry with the Humphrey Perimetry in a Clinic-Based Setting
TRANSLATIONAL VISION SCIENCE & TECHNOLOGY
2016; 5 (4)
We determined the receiver operating characteristic (ROC) curves for Peristat online perimetry at detecting varying degrees of glaucoma and the correlation between Peristat online perimetry and Humphrey visual field.A prospective, comparative study of Peristat online perimetry (an achromatic static computer threshold testing program) and Humphrey visual field (HVF) 24-2 SITA standard testing was performed by 63 glaucoma patients and 30 healthy controls in random order. The number of total adjacent abnormal test points were identified for each test, and compared with Spearman correlation. Receive operating characteristic curves were generated for Peristat online perimetry detection of mild and moderate-severe glaucoma patients using contrast sensitivity thresholds of -16.7, -21.7, and -26.7 dB.The area under the ROC curve for glaucoma detection ranged from 0.77 to 0.81 for mild disease (mean deviation [MD], >-6 dB on HVF) and 0.85 to 0.87 for moderate to severe disease (MD, <-6 dB on HVF) depending on contrast threshold. Peristat online perimetry and Humphrey visual field abnormal points were highly correlated with Spearman rank correlations ranging from 0.55 to 0.77 (all P < 0.001).Peristat online perimetry exhibits a reasonable ROC curve without specialized equipment and exhibited significant correlation with the conventional 24° Humphrey visual field test.Low cost widely available internet-based visual fields may complement traditional office-based visual field testing.
View details for DOI 10.1167/tvst.5.4.4
View details for Web of Science ID 000388670600004
View details for PubMedID 27486554
View details for PubMedCentralID PMC4959820
Hoxb5 marks long-term haematopoietic stem cells and reveals a homogenous perivascular niche
2016; 530 (7589): 223-?
Haematopoietic stem cells (HSCs) are arguably the most extensively characterized tissue stem cells. Since the identification of HSCs by prospective isolation, complex multi-parameter flow cytometric isolation of phenotypic subsets has facilitated studies on many aspects of HSC biology, including self-renewal, differentiation, ageing, niche, and diversity. Here we demonstrate by unbiased multi-step screening, identification of a single gene, homeobox B5 (Hoxb5, also known as Hox-2.1), with expression in the bone marrow that is limited to long-term (LT)-HSCs in mice. Using a mouse single-colour tri-mCherry reporter driven by endogenous Hoxb5 regulation, we show that only the Hoxb5(+) HSCs exhibit long-term reconstitution capacity after transplantation in primary transplant recipients and, notably, in secondary recipients. Only 7-35% of various previously defined immunophenotypic HSCs are LT-HSCs. Finally, by in situ imaging of mouse bone marrow, we show that >94% of LT-HSCs (Hoxb5(+)) are directly attached to VE-cadherin(+) cells, implicating the perivascular space as a near-homogenous location of LT-HSCs.
View details for DOI 10.1038/nature16943
View details for Web of Science ID 000369916700040
View details for PubMedID 26863982
View details for PubMedCentralID PMC4854608
SUNDROP: six years of screening for retinopathy of prematurity with telemedicine.
Canadian journal of ophthalmology. Journal canadien d'ophtalmologie
2015; 50 (2): 101-106
To report the 6-year results of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) initiative in the context of telemedicine screening initiatives for retinopathy of prematurity (ROP).A retrospective analysis.Premature newborns requiring ROP screening at 6 neonatal intensive care units from December 1, 2005, to November 30, 2011.Infants were evaluated via remote retinal photography by an ROP specialist. A total of 608 preterm infants meeting ROP examination criteria were screened with the RetCam II/III (Clarity Medical Systems, Pleasanton, Calif.). Primary outcomes were treatment-warranted ROP (TW-ROP) and adverse anatomical events.During the 6 years, 1216 total eyes were screened during 2169 examinations, generating 26 970 retinal images, an average of 3.56 examinations and 44.28 images per patient. Twenty-two (3.6%) of the infants screened met criteria for TW-ROP. Compared with bedside binocular ophthalmoscopy, remote interpretation of RetCam II/III images had a sensitivity of 100%, specificity of 99.8%, positive predicative value of 95.5%, and negative predicative value of 100% for the detection of TW-ROP. No adverse anatomical outcomes were observed for any enrolled patient.The 6-year results for the SUNDROP telemedicine initiative were highly favourable with respect to diagnostic accuracy. Telemedicine appears to be a safe, reliable, and cost-effective complement to the efforts of ROP specialists, capable of increasing patient access to screening and focusing the resources of the current ophthalmic community on infants with potentially vision-threatening disease.
View details for DOI 10.1016/j.jcjo.2014.11.005
View details for PubMedID 25863848
Expression of glypican 3 enriches hepatocellular carcinoma development-related genes and associates with carcinogenesis in cirrhotic livers
2015; 36 (2): 232-242
Glypican-3 (GPC3) protein expression was determined by immunohistochemical analysis from 29 normal livers, 80 cirrhotic livers sample taken near hepatocellular carcinoma (HCC), and 87 cirrhotic livers without HCC. The levels for miR-657 and HCC-related gene mRNAs were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Also, a published microarray dataset was used for gene set enrichment analysis (GSEA) to investigate the relationship between GPC3- and HCC-related gene signatures. Kaplan-Meier analysis was used to evaluate the relationship between GPC3 and HCC recurrence. GPC3 protein expression was not detected in any of the 29 (0%) normal livers, but was detected in 32 of 87 (37%) cirrhotic livers without HCC, and 51 of 80 (64%) cirrhotic liver samples taken near HCC sites (P < 0.001). The GPC3-positive rate in cirrhotic livers of viral origin was 68% (27/40), which was significantly higher than for non-viral cirrhotic livers (11%, 5/47) (P < 0.001). Also, GPC3 expression positively correlated with mRNA expression of HCC-related genes in the qRT-PCR and GSEA evaluations. Furthermore, HCC recurrence in cirrhotic liver samples taken near HCC sites was significantly higher in the GPC3-positive group than the GPC3-negative group (Log-rank P = 0.02, HR = 3.26; 95% CI = 1.20-10.29). This study demonstrated that highly expression of GPC3 could enrich HCC-related genes' mRNA expression and positive associate with dysplasia in cirrhotic livers. Therefore, GPC3 may serve as a precancerous biomarker in cirrhotic livers.
View details for DOI 10.1093/carcin/bgu245
View details for Web of Science ID 000350214900007
View details for PubMedID 25542894
- Gender differences in compensation in academic medicine: the results from four neurological specialties within the University of California Healthcare System SCIENTOMETRICS 2014; 100 (1): 297-306
Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP): five years of screening with telemedicine.
Ophthalmic surgery, lasers & imaging retina
2014; 45 (2): 106-113
To report the 5-year results of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) telemedicine initiative.Infants requiring retinopathy of prematurity (ROP) screening at six neonatal intensive care units from December 1, 2005, to November 30, 2010, were evaluated with remote retinal photography by an ROP specialist. Every infant received outpatient binocular indirect ophthalmoscope examinations until termination criteria were achieved or until treatment. Outcomes were treatment-warranted ROP (TW-ROP, ETROP type 1) and adverse anatomical events.Five hundred eleven infants (1,022 eyes) were screened. Fifteen infants had TW-ROP and underwent laser photocoagulation. The TW-ROP cohort had significantly lower birth weight and gestational age (both P < .001). No patient progressed to adverse anatomical outcomes and no case of TW-ROP was missed. Tele-medicine had 100% sensitivity, 99.8% specificity, 93.8% positive predictive value, and 100% negative predictive value for detection of TW-ROP.Telemedicine demonstrates high diagnostic accuracy for detection of TW-ROP and can complement ROP screening. [Ophthalmic Surg Lasers Imaging Retina. 2014;45:106-113.].
View details for DOI 10.3928/23258160-20140122-01
View details for PubMedID 24444469
An emerging treatment option for glaucoma: Rho kinase inhibitors.
Clinical ophthalmology (Auckland, N.Z.)
2014; 8: 883-890
Rho kinase (ROCK) inhibitors are a novel potential class of glaucoma therapeutics with multiple compounds currently in Phase II and III US Food and Drug Administration trials in the United States. These selective agents work by relaxing the trabecular meshwork through inhibition of the actin cytoskeleton contractile tone of smooth muscle. This results in increased aqueous outflow directly through the trabecular meshwork, achieving lower intraocular pressures in a range similar to prostaglandins. There are also animal studies indicating that ROCK inhibitors may improve blood flow to the optic nerve, increase ganglion cell survival, and reduce bleb scarring in glaucoma surgery. Given the multiple beneficial effects for glaucoma patients, ROCK inhibitors are certainly a highly anticipated emerging treatment option for glaucoma.
View details for DOI 10.2147/OPTH.S41000
View details for PubMedID 24872673
View details for PubMedCentralID PMC4025933
Discovery and diagnostic value of a novel oncofetal protein: glypican 3.
Advances in anatomic pathology
2014; 21 (6): 450–60
Glypican 3 is a membrane-bound heparan sulfate proteoglycan, which has recently been identified as a marker for liver cancer and germ cell malignancies. Individuals with loss-of-function mutations for the glypican 3 gene exhibit Simpson-Golabi-Behmel syndrome, a rare X-linked overgrowth disorder. Expression of glypican 3 mRNA and protein is normally silenced in most adult organs and may reappear during malignant transformation. In the past few years, immunohistochemical and molecular characteristics of glypican 3 in hepatocellular carcinoma have been elucidated. More recently, glypican 3 has been emerging as a new diagnostic marker for germ cell tumors and especially testicular and ovarian yolk sac tumors. However, in other tumors such as renal cell carcinomas, squamous cell carcinomas, and melanomas, studies disagree on the level of glypican 3 expression. Finally, there is the controversial notion of glypican 3 as a tumor suppressor gene. In this review article, we update current knowledge on glypican 3 expression in normal and neoplastic tissues, evaluate its utility as a tumor marker in clinical practice, and explore its role as a novel oncofetal protein with clinical implications. Our focus is on the diagnostic value of glypican 3 in germ cell tumors and other neoplasms in addition to hepatocellular carcinoma. In conclusion, glypican 3 has been proven to be a useful immunohistochemical marker in distinguishing yolk sac tumors, choriocarcinomas, and Wilms tumors from other malignancies histologically mimicking these primitive tumors. Clinically, we recommend that glypican 3 be used as part of a panel of markers in subtyping testicular germ cell tumors.
View details for PubMedID 25299314
A new paradigm for incorporating the joint statement screening guidelines for retinopathy of prematurity into clinical practice: outcomes from a quaternary referral program.
Ophthalmic surgery, lasers & imaging retina
2013; 44 (5): 442-447
This study examines patient experience at a quaternary referral pediatric clinic with a retinopathy of prematurity (ROP) screening program that monitors infants at least on a weekly basis for any stage of ROP.Admission records of 399 prematurely born patients treated at the Byers Eye Institute outpatient ROP clinic were retrospectively reviewed. Patients were categorized according to ROP status and whether they completed, canceled, or failed to show up for scheduled examinations. Demographic information was collected from medical records.Of 1,823 scheduled ROP-related visits, 327 (17.9%) resulted in cancellations and 90 (4.9%) in no-shows, with 238 missed visits due to caregiver-related and 149 due to caregiver-unrelated reasons. Of 399 total patients, 142 (35.6%) canceled or failed to show up for at least one appointment because of caregiver-related reasons.More than one-third of patients with ROP canceled or missed appointments. The true risk of delay is difficult to assess because all patients requiring treatment received it prior to discharge from the hospital. To achieve maximal compliance with joint statement guidelines on ROP screening, patients should be scheduled for examination earlier than recommended. [Ophthalmic Surg Lasers Imaging Retina. 2013;44:442-447.].
View details for DOI 10.3928/23258160-20130909-04
View details for PubMedID 24044706
Comparison of Web-based Perimetry and office-based Humphrey Visual Field (HVF) in Patients with Glaucoma
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2013
View details for Web of Science ID 000436232709037
Clinical Utility of Web-based Office and Home Peristat for the Detection of Visual Field Defects in Patients with Glaucoma
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2013
View details for Web of Science ID 000436232709057