Investigating druggable kinases for targeted therapy in retinoblastoma.

Retinoblastoma (RB) is a childhood retinal neoplasm and commonly treated with cytotoxic chemotherapeutic agents. However, these therapeutic approaches often lead to diverse adverse effects. A precise molecular therapy will alleviate these side effects and offer better treatment outcomes. Over the years, kinases have become potential drug targets in cancer therapy. Hence, we aimed to investigate genetic alterations of putative kinase drug targets in RB. Targeted exome sequencing was performed on 35 RB tumors with paired blood samples using a gene panel consisting of 29 FDA-approved kinase genes. Single nucleotide variants were analyzed for pathogenicity using an in-house pipeline and copy number variations (CNVs) were detected by a depth of coverage and CNVPanelizer. The correlation between genetic changes and clinicopathological features was assessed using GraphPad Prism. Three somatic mutations, two in ERBB4 and one in EGFR were identified. Two of these mutations (ERBB4 c.C3836A & EGFR c.A1196T) were not reported earlier. CNV analysis revealed recurrent gains of ALK, MAP2K2, SRC, STK11, and FGFR3 as well as frequent losses of ATM, PI3KCA and ERBB4. Notably, nonresponsive tumors had a higher incidence of amplifications in clinically actionable genes such as ALK. Moreover, ALK gain and ATM loss were strongly correlated with optic nerve head invasion. In conclusion, our study revealed genetic alterations of druggable kinases in RB, providing preliminary insights for the exploration of kinase-targeted therapy in RB.

eyeVarP: A computational framework for the identification of pathogenic variants specific to eye disease.

PURPOSE: Disease-specific pathogenic variant prediction tools that differentiate pathogenic variants from benign have been improved through disease specificity recently. However, they have not been evaluated on disease-specific pathogenic variants compared with other diseases, which would help to prioritize disease-specific variants from several genes or novel genes. Thus, we hypothesize that features of pathogenic variants alone would provide a better model. METHODS: We developed an eye disease-specific variant prioritization tool (eyeVarP), which applied the random forest algorithm to the data set of pathogenic variants of eye diseases and other diseases. We also developed the VarP tool and generalized pipeline to filter missense and insertion-deletion variants and predict their pathogenicity from exome or genome sequencing data, thus we provide a complete computational procedure. RESULTS: eyeVarP outperformed pan disease-specific tools in identifying eye disease-specific pathogenic variants under the top 10. VarP outperformed 12 pathogenicity prediction tools with an accuracy of 95% in correctly identifying the pathogenicity of missense and insertion-deletion variants. The complete pipeline would help to develop disease-specific tools for other genetic disorders. CONCLUSION: eyeVarP performs better in identifying eye disease-specific pathogenic variants using pathogenic variant features and gene features. Implementing such complete computational procedure would significantly improve the clinical variant interpretation for specific diseases.

Detection of microRNAs expression signatures in vitreous humor of intraocular tuberculosis.

BACKGROUND: MicroRNA (miRNA) expression analysis has been shown to provide them as biomarkers in several eye diseases and has a regulatory role in pathogenesis. However, miRNA expression analysis in the vitreous humor (VH) of intraocular tuberculosis (IOTB) is not studied. Thus, we aim to find miRNA expression signatures in the VH of IOTB patients to identify their regulatory role in disease pathogenesis and to find them as potential biomarkers for IOTB. METHODS AND RESULTS: First, we profiled miRNAs in VH of three IOTB and three Macular hole (MH) samples as controls through small-RNA deep sequencing using Illumina Platform. In-house bioinformatics analysis identified 81 dysregulated miRNAs in IOTB. Further validation in VH of IOTB (n = 15) compared to MH (n = 15) using Real-Time quantitative PCR (RT-qPCR) identified three significantly upregulated miRNAs, hsa-miR-150-5p, hsa-miR-26b-5p, and hsa-miR-21-5p. Based on the miRNA target prediction, functional network analysis, and RT-qPCR analysis of target genes, the three miRNAs downregulating WNT5A, PRKCA, MAP3K7, IL7, TGFB2, IL1A, PRKCB, TNFA, and TP53 genes involving MAPK signaling pathway, PI3K-AKT signaling pathway, WNT signaling pathway, Cell cycle, TGF-beta signaling pathway, Long-term potentiation, and Sphingolipid signaling pathways, have a potential role in disease pathogenesis. The ROC analysis of RT-qPCR data showed that hsa-miR-150-5p with AUC = 0.715, hsa-miR-21-5p with AUC = 0.789, and hsa-miR-26b-5p with AUC = 0.738; however, the combination of hsa-miR-21-5p and hsa-miR-26b-5p with AUC = 0.796 could serve as a potential biomarker for IOTB. CONCLUSIONS: This study provides the first report on miRNA expression signatures detected in VH for IOTB pathogenesis and also provides a potential biomarker for IOTB.

Hsa-miR-150-5p inhibits Wnt-ß-catenin signaling in human corneal epithelial stem cells.

Purpose: In our earlier study, we identified hsa-miR-150-5p as a highly expressed miRNA in enriched corneal epithelial stem cells (CESCs). In this study, we aimed to understand the molecular regulatory function of hsa-miR-150-5p in association with the maintenance of stemness in CESCs. Methods: The target mRNAs of hsa-miR-150-5p were predicted and subjected to pathway analysis to identify targets for functional studies. Primary cultured limbal epithelial cells were transfected with hsa-miR-150-5p mimic, inhibitor, or scrambled sequence using Lipofectamine 3000. The transfected cells were analyzed to determine (i) their colony-forming potential; (ii) the expression levels of stem cell (SC) markers/transcription factors (ABCG2, NANOG, OCT4, KLF4, and ΔNp63), the differentiation marker (Cx43), and the hsa-miR-150-5p predicted targets (JARID2, INHBA, AKT3, and CTNNB1) by qPCR; and (iii) the expression levels of ABCG2, p63α, Cx43, JARID2, AKT3, p-AKT3, ß-catenin, and active ß-catenin by immunofluorescence staining and/or western blotting. Results: The ectopic expression level of hsa-miR-150-5p increased the colony-forming potential (8.29% ± 0.47%, p < 0.001) with the ability to form holoclone-like colonies compared with the control (1.8% ± 0.47%). The mimic-treated cells had higher expression levels of the SC markers but reduced expression levels of Cx43 and the targets of hsa-miR-150-5p that are involved in the Wnt-ß-catenin signaling pathway. The expression levels of ß-catenin and active ß-catenin in the inhibitor-transfected cells were higher than those in the control cells, and the localized nuclear expression indicated the activation of Wnt signaling. Conclusions: Our results indicate a regulatory role for hsa-miR-150-5p in the maintenance of CESCs by inhibiting the Wnt signaling pathway.

Dysregulated expression of microRNAs in aqueous humor from intraocular tuberculosis patients.

BACKGROUND: Systemic Mycobacterium tuberculosis (Mtb) infection alters microRNA's expression that controls cellular processes and modulates host defense mechanisms. However, the role of miRNAs in intraocular tuberculosis (IOTB) remains unknown. Therefore, this study aims to identify dysregulated miRNAs in the aqueous humor (AH) of patients with IOTB. METHODS: AH from intraocular tuberculosis patients (n = 2) and cataract controls (n = 2) were used for small RNA deep sequencing using HiSeq Illumina sequencing platform. Differentially expressed miRNAs and their targets were identified by the bioinformatics approach, and their regulatory functions were predicted by pathway enrichment analysis. The expression of selected miRNAs and their binding targets were further validated by real-time quantitative PCR (RT-qPCR). RESULTS: In total, we identified 56 differentially expressed miRNAs in the AH of intraocular tuberculosis (IOTB) patients compared to controls. We selected four significantly dysregulated miRNAs (miR-423-5p, miR-328-3p, miR-21-5p, and miR-16-5p) based on the RT-qPCR validation and predicted their gene targets. We developed a miRNA-targets regulatory network by combining pathways of interest and genes associated with TB. We identified that these four miRNAs might play an important role in IOTB pathogenesis via tuberculosis-associated pathways; PI3K-Akt signaling, autophagy and MAPK pathway. CONCLUSIONS: For the first time, this study identifies the dysregulation of four miRNAs in the AH of IOTB patients using the ultra-low input small-RNA sequencing approach. Further target prediction and validation identify the role of these miRNAs in tuberculosis pathogenesis via tuberculosis-related pathways. This study identifies miRNAs as potentially ideal biomarkers in the aqueous humor of IOTB patients.

Characterization of antibiotic resistance and virulence genes of ocular methicillin-resistant Staphylococcus aureus strains through complete genome analysis.

Virulence-factor encoding genes (VFGs) and antimicrobial resistance genes (ARGs) of ocular Methicillin-Resistant Staphylococcus aureus (MRSA), are the reason behind the common cause of severe and untreatable ocular infection and are largely unknown. The unavailability of the complete genome sequence of ocular MRSA strains hinders the unambiguous determination of ARGs and VRGs role in disease pathogenesis and their genomic location. To fulfill this critical need, we achieved the high-quality complete genome of four ocular MRSA strains (AMRF3 - AMRF6) by combining MinION nanopore sequencing technology, followed by polishing with Illumina sequence reads. We obtained a single chromosome and a plasmid in each strain. Sequence typing revealed that AMRF3 and AMRF5 strains harbored ST772, whereas AMRF4 and AMRF6 harbored ST 2066. All plasmids carried heavy metal cadmium resistance genes cadC and cadD, while cadA was detected only in the plasmid pSaa6159 of AMRF4 and AMRF6 strains. Further, pSaa6159 contains a complete Tn552 transposon with beta-lactamase genes, blaI, blaR1, and blaZ. Interestingly, pSaa6159 in AMRF6 carried five copies of Tn552 transposon. Several exotoxins and enterotoxins were identified across ocular MRSA strains and ST2066 strains found to be not carried any enterotoxins; this finding suggests that these two strains are exotoxigenic. Besides, ST2066 strains carried serine proteases (splA, splB, splD, splE and spIF) and exotoxin (seb and set 21) for their virulence, while ST772 carried antimicrobial resistance genes (blaZ, dfrG, msrA, mphC and fosB) and enterotoxin sec for virulence, suggesting sequence type-specific resistance and virulence. Also, we identified many VFGs and ARGs, that provided multi-drug resistance, enterotoxigenic, exotoxigenic, biofilm-forming, host tissue adhesion and immune response evasion in ocular MRSA strains. Thus, our study provides a better insight into the genomes of ocular MRSA strains that would provide more effective treatment strategies for ocular MRSA infection.

Comparative genomics of ocular Pseudomonas aeruginosa strains from keratitis patients with different clinical outcomes.

The several virulence and drug-resistance mechanisms of Pseudomonas aeruginosa responsible for poor clinical outcomes in keratitis patients remain largely unknown. Here, we investigated the distribution of virulence factors and drug resistance by genes, mutations, efflux-pump systems of P. aeruginosa strains from keratitis patients with different clinical outcomes, included of whole-genome sequenced and annotated our five P. aeruginosa strains. Of the large number of virulence genes detected in all the genomes, MDR/XDR strains carry exoU and non-MDR strains carry exoS exotoxin of the type III secretion system, considered as main contributors of keratitis pathogenesis. However, several strain-specific virulence and resistance genes were detected in keratitis strains with poor outcome. Mainly, the flagellar genes fliC and fliD detected in the exoS carrying strains, reported to alter the host immune response, might impact the clinical outcome. This study may provide new insights into the genome of ocular strains and requires further functional studies.

Performance assessment of variant calling pipelines using human whole exome sequencing and simulated data.

BACKGROUND: Whole exome sequencing (WES) is a cost-effective method that identifies clinical variants but it demands accurate variant caller tools. Currently available tools have variable accuracy in predicting specific clinical variants. But it may be possible to find the best combination of aligner-variant caller tools for detecting accurate single nucleotide variants (SNVs) and small insertion and deletion (InDels) separately. Moreover, many important aspects of InDel detection are overlooked while comparing the performance of tools, particularly its base pair length. RESULTS: We assessed the performance of variant calling pipelines using the combinations of four variant callers and five aligners on human NA12878 and simulated exome data. We used high confidence variant calls from Genome in a Bottle (GiaB) consortium for validation, and GRCh37 and GRCh38 as the human reference genome. Based on the performance metrics, both BWA and Novoalign aligners performed better with DeepVariant and SAMtools callers for detecting SNVs, and with DeepVariant and GATK for InDels. Furthermore, we obtained similar results on human NA24385 and NA24631 exome data from GiaB. CONCLUSION: In this study, DeepVariant with BWA and Novoalign performed best for detecting accurate SNVs and InDels. The accuracy of variant calling was improved by merging the top performing pipelines. The results of our study provide useful recommendations for analysis of WES data in clinical genomics.

A stepwise strategy for rapid and cost-effective RB1 screening in Indian retinoblastoma patients.

India has the highest number of retinoblastoma (RB) patients among the developing countries owing to its increasing population. Of the patients with RB, about 40% have the heritable form of the disease, making genetic analysis of the RB1 gene an integral part of disease management. However, given the large size of the RB1 gene with its widely dispersed exons and no reported hotspots, genetic testing can be cumbersome. To overcome this problem, we have developed a rapid screening strategy by prioritizing the order of exons to be analyzed, based on the frequency of nonsense mutations, deletions and duplications reported in the RB1-Leiden Open Variation Database and published literature on Indian patients. Using this strategy for genetic analysis, mutations were identified in 76% of patients in half the actual time and one third of the cost. This reduction in time and cost will allow for better risk prediction for siblings and offspring, thereby facilitating genetic counseling for families, especially in developing countries.

Targeted next generation sequencing of RB1 gene for the molecular diagnosis of Retinoblastoma.

BACKGROUND: The spectrum of RB1gene mutations in Retinoblastoma (RB) patients and the necessity of multiple traditional methods for complete variant analysis make the molecular diagnosis a cumbersome, labor-intensive and time-consuming process. Here, we have used targeted next generation sequencing (NGS) approach with in-house analysis pipeline to explore its potential for the molecular diagnosis of RB. METHODS: Thirty-three patients with RB and their family members were selected randomly. DNA from patient blood and/or tumor was used for RB1 gene targeted sequencing. The raw reads were obtained from Illumina Miseq. An in-house bioinformatics pipeline was developed to detect both single nucleotide variants (SNVs) and small insertions/deletions (InDels) and to distinguish between somatic and germline mutations. In addition, ExomeCNV and Cn. MOPS were used to detect copy number variations (CNVs). The pathogenic variants were identified with stringent criteria, and were further confirmed by conventional methods and cosegregation in families. RESULTS: Using our approach, an array of pathogenic variants including SNVs, InDels and CNVs were detected in 85% of patients. Among the variants detected, 63% were germline and 37% were somatic. Interestingly, nine novel pathogenic variants (33%) were also detected in our study. CONCLUSIONS: We demonstrated for the first time that targeted NGS is an efficient approach for the identification of wide spectrum of pathogenic variants in RB patients. This study is helpful for the molecular diagnosis of RB in a comprehensive and time-efficient manner.

Myocilin Mutation N480K Leads to Early Onset Juvenile and Adult-onset Primary Open Angle Glaucoma in a Six Generation Family.

PRCIS: A pathogenic autosomal dominant MYOC mutation N480K detected in 6 generations of an Indian family is primarily responsible for juvenile open angle glaucoma (JOAG) and adult-onset primary open angle glaucoma (POAG), emphasizing the importance of screening this mutation at a younger age. PURPOSE: To screen myocilin mutations in a large South Indian family with early-onset JOAG and adult-onset POAG. METHODS: In a large South Indian family with 20 members, 8 members diagnosed as JOAG, 7 members as POAG, 4 members as JOAG suspect, and 1 member as POAG suspect were screened for myocilin ( MYOC) mutations using Sanger sequencing. Whole exome sequencing was performed on clinically suspected JOAG/POAG individuals. RESULTS: Myocilin gene mutation N480K (c.1440C>G) was detected in 20 family members, including proband, of whom 8 were JOAG and 7 were POAG patients, 3 were JOAG suspects, and 2 were unaffected. Among the unaffected carriers, 1 was less than 5 years old, and another was 25 years old. The earliest to develop the disease was a 10-year-old child. The penetrance of the mutation was 95% over 10 years of age. This family had JOAG/POAG suspects with no N480K MYOC mutation, and they were further screened for other mutations using whole-exome sequencing. Polymorphisms CYP1B1 L432V and MYOC R76K were detected in 3 JOAG/POAG suspects, and among these 3, one had another CYP1B1 polymorphic variant R368H. The presence of the CYP1B1 polymorphism along with an MYOC polymorphic variant among the JOAG/POAG suspects needs additional studies to explore their combined role in the onset of glaucoma. CONCLUSIONS: This study reveals that MYOC mutation is primarily responsible for JOAG and adult-onset POAG in a family, emphasizing the importance of screening for this mutation at a younger age for early treatment.

Comparison of gut microbiome profile in patients with schizophrenia and healthy controls - A plausible non-invasive biomarker?

The human gut microbiome regulates brain function through the microbiome-gut-brain axis and is implicated in several neuropsychiatric disorders. However, the relationship between the gut microbiome and the pathogenesis of schizophrenia (SCZ) is poorly defined, and very few studies have examined the effect of antipsychotic treatment response. We aim to study the differences in the gut microbiota among drug-naïve (DN SCZ) and risperidone-treated SCZ patients (RISP SCZ), compared to healthy controls (HCs). We recruited a total of 60 participants, from the clinical services of a large neuropsychiatric hospital, which included DN SCZ, RISP SCZ and HCs (n = 20 each). Fecal samples were analyzed using 16s rRNA sequencing in this cross-sectional study. No significant differences were found in taxa richness (alpha diversity) but microbial composition differed between SCZ patients (both DN and RISP) and HCs (PERMANOVA, p = 0.02). Linear Discriminant Analysis Effect Size (LEfSe) and Random Forest model identified the top six genera, which significantly differed in abundance between the study groups. A specific genus-level microbial panel of Ruminococcus, UCG005, Clostridium_sensu_stricto_1 and Bifidobacterium could discriminate SCZ patients from HCs with an area under the curve (AUC) of 0.79, HCs vs DN SCZ (AUC: 0.68), HCs vs RISP SCZ (AUC: 0.93) and DN SCZ vs RISP SCZ (AUC: 0.87). Our study identified distinct microbial signatures that could aid in the differentiation of DN SCZ, RISP SCZ, and HCs. Our findings contribute to a better understanding of the role of the gut microbiome in SCZ pathophysiology and suggest potential targeted interventions.

Two autonomous structural modules in the fimbrial shaft adhesin FimA mediate Actinomyces interactions with streptococci and host cells during oral biofilm development.

By combining X-ray crystallography and modelling, we describe here the atomic structure of distinct adhesive moieties of FimA, the shaft fimbrillin of Actinomyces type 2 fimbriae, which uniquely mediates the receptor-dependent intercellular interactions between Actinomyces and oral streptococci as well as host cells during the development of oral biofilms. The FimA adhesin is built with three IgG-like domains, each of which harbours an intramolecular isopeptide bond, previously described in several Gram-positive pilins. Genetic and biochemical studies demonstrate that although these isopeptide bonds are dispensable for fimbrial assembly, cell-cell interactions and biofilm formation, they contribute significantly to the proteolytic stability of FimA. Remarkably, FimA harbours two autonomous adhesive modules, which structurally resemble the Staphylococcus aureus Cna B domain. Each isolated module can bind the plasma glycoprotein asialofetuin as well as the polysaccharide receptors present on the surface of oral streptococci and epithelial cells. Thus, FimA should serve as an excellent paradigm for the development of therapeutic strategies and elucidating the precise molecular mechanisms underlying the interactions between cellular receptors and Gram-positive fimbriae.

Hsa-miR-143-3p inhibits Wnt-ß-catenin and MAPK signaling in human corneal epithelial stem cells.

Our previous study demonstrated hsa-miR-143-3p as one of the highly expressed miRNAs in enriched corneal epithelial stem cells (CESCs). Hence this study aims to elucidate the regulatory role of hsa-miR-143-3p in the maintenance of stemness in CESCs. The target genes of hsa-miR-143-3p were predicted and subjected to pathway analysis to select the targets for functional studies. Primary cultured limbal epithelial cells were transfected with hsa-miR-143-3p mimic, inhibitor or scrambled sequence using Lipofectamine 3000. The transfected cells were analysed for (i) colony forming potential, (ii) expression of stem cell (SC) markers/ transcription factors (ABCG2, NANOG, OCT4, KLF4, ΔNp63), (iii) differentiation marker (Cx43), (iv) predicted five targets of hsa-miR-143-3p (DVL3, MAPK1, MAPK14, KRAS and KAT6A), (v) MAPK signaling regulators and (vi) Wnt-ß-catenin signaling regulators by qPCR, immunofluorescence staining and/or Western blotting. High expression of hsa-miR-143-3p increased the colony forming potential (10.04 ± 1.35%, p < 0.001) with the ability to form holoclone-like colonies in comparison to control (3.33 ± 0.71%). The mimic treated cells had increased expression of SC markers but reduced expression of Cx43 and hsa-miR-143-3p targets involved in Wnt-ß-catenin and MAPK signaling pathways. The expression of ß-catenin, active ß-catenin and ERK2 in hsa-miR-143-3p inhibitor transfected cells were higher than the control cells and the localized nuclear expression indicated the activation of Wnt and MAPK signaling. Thus, the probable association of hsa-miR-143-3p in the maintenance of CESCs through inhibition of Wnt and MAPK signaling pathways was thus indicated.

Clinical reassessments and whole-exome sequencing uncover novel BEST1 mutation associated with bestrophinopathy phenotype.

BACKGROUND: The diagnosis of retinal dystrophies can be challenging due to the spectrum of protean phenotypic manifestations. This study employed trio-whole-exome sequencing (trio-WES) to unveil the genetic cause of an inherited retinal disorder in a south Indian family. MATERIALS AND METHODS: Proband's initial ophthalmic examinations was performed in the year 2016. WES was performed on a proband-parent trio to identify causative mutation followed by Sanger validation, segregation analysis, sequence and structure-based computational analysis to assess its pathogenicity. Based on the genetic findings, detailed clinical reassessments were performed in year 2020 for the proband and available family members. RESULTS: WES revealed a novel homozygous BEST1 mutation c.G310A (p.D104N) in the proband and heterozygous for the parents, indicating autosomal recessive inheritance. Segregation analysis showed heterozygous mutation in maternal grandfather and normal genotype for younger brother and maternal grandmother. Moreover, the structure-based analysis revealed the mutation p.D104N in the cytoplasmic domain, causing structural hindrance by altering hydrogen bonds and destabilizing the BEST1 protein structure. Proband's clinical assessments were consistent with autosomal recessive bestrophinopathy (ARB) phenotype. Additionally, characteristic absent light rise and decreased light peak-to-dark trough ratio (LP:DT) was observed bilaterally in EOG. CONCLUSIONS: Our study demonstrates the utility of WES and clinical re-evaluations in establishing the precise diagnosis of autosomal recessive bestrophinopathy associated with a novel mutation, thus expanding the BEST1-related mutation spectrum.

Whole-exome sequencing identifies multiple pathogenic variants in a large South Indian family with primary open-angle glaucoma.

PURPOSE: To identify the pathogenic variants associated with primary open-angle glaucoma (POAG) using whole-exome sequencing (WES) data of a large South Indian family. METHODS: We recruited a large five-generation South Indian family (n = 84) with a positive family history of POAG (n = 19). All study participants had a comprehensive ocular evaluation. We performed WES for 16 samples (nine POAG and seven unaffected controls) since Sanger sequencing of the POAG candidate genes (MYOC, OPTN, and TBK1) showed no genetic variation. We used an in-house pipeline for prioritizing the pathogenic variants based on their segregation among the POAG individual. RESULTS: We identified one novel and five low-frequency pathogenic variants with consistent co-segregation in all affected individuals. The variant c.G3719A in RPGR-interacting domain of RPGRIP1 that segregated heterozygously with the six POAG cases is distinct from variants causing photoreceptor dystrophies, reported affecting the RPGR protein complex signaling in primary cilia. The cilia in trabecular meshwork (TM) cells has been reported to mediate the intraocular pressure (IOP) sensation. Furthermore, we identified a novel c.A1295G variant in Rho guanine nucleotide exchange factors Gene 40 (ARHGEF40) and a likely pathogenic variant in the RPGR gene, suggesting that they may alter the RhoA activity essential for IOP regulation. CONCLUSION: Our study supports that low-frequency pathogenic variants in multiple genes and pathways probably affect Primary Open Angle Glaucoma's pathogenesis in the large South Indian family. Furthermore, it requires larger case-controls to perform family-based association tests and to strengthen our analysis.

MicroRNA Profiling of Highly Enriched Human Corneal Epithelial Stem Cells by Small RNA Sequencing.

The objective of the study was to elucidate the microRNA (miRNA) profile of an enriched human corneal epithelial stem cell (CESC) population in comparison to differentiated central corneal epithelial cells (CCECs) by small RNA sequencing. The CESCs were enriched by differential enzymatic treatment to isolate the basal limbal epithelial cells followed by laser capture microdissection of cells with nucleus to cytoplasm ratio ≥0.7, from donor tissues. Small RNA sequencing was carried out using Illumina NextSeq. 500 platform and the validation of differentially expressed miRNAs by quantitative real-time PCR (qPCR) and locked nucleic acid miRNA in-situ hybridization (LNA-ISH). The sequencing identified 62 miRNAs in CESCs and 611 in CCECs. Six miRNAs: hsa-miR-21-5p, 3168, 143-3p, 10a-5p, 150-5p and 1910-5p were found to be significantly upregulated in enriched CESCs, which was further confirmed by qPCR and LNA-ISH. The expression of hsa-miR-143-3p was exclusive to clusters of limbal basal epithelial cells. The targets of the upregulated miRNAs were predicted to be associated with signaling pathways -Wnt, PI3K-AKT, MAPK and pathways that regulate pluripotency of stem cells, cell migration, growth and proliferation. Further studies are essential to elucidate their functional role in maintenance of stemness. The findings of the study also hypothesize the inherent potential of hsa-miR-143-3p to serve as a biomarker for identifying CESCs.

Genetic characterization of Stargardt clinical phenotype in South Indian patients using sanger and targeted sequencing.

BACKGROUND: Stargardt disease 1 (STGD1; MIM 248200) is a monogenic form of autosomal recessive genetic disease caused by mutation in ABCA4. This gene has a major role in hydrolyzing N-retinylidene-phosphatidylethanolamine to all-trans-retinal and phosphatidylethanolamine. The purpose of this study is to identify the frequency of putative disease-causing mutations associated with Stargardt disease in a South Indian population. METHODS: A total of 28 clinically diagnosed Stargardt-like phenotype patients were recruited from south India. Ophthalmic examination of all patients was carefully carried out by a retina specialist based on the stages of fundus imaging and ERG grouping. Genetic analysis of ABCA4 was performed for all patients using Sanger sequencing and clinical exome sequencing. RESULTS: This study identified disease-causing mutations in ABCA4 in 75% (21/28) of patients, 7% (2/28) exhibited benign variants and 18% (5/28) were negative for the disease-causing mutation. CONCLUSION: This is the first study describing the genetic association of ABCA4 disease-causing mutation in South Indian Stargardt 1 patients (STGD1). Our findings highlighted the presence of two novel missense mutations and an (in/del, single base pair deletion & splice variant) in ABCA4. However, genetic heterogeneity in ABCA4 mutants requires a larger sample size to establish a true correlation with clinical phenotype.

Mechanisms of Fluoroquinolone and Aminoglycoside Resistance in Keratitis-Associated Pseudomonas aeruginosa.

Global emergence of multidrug resistant (MDR) strains limits therapeutic efficacy in Pseudomonas aeruginosa corneal ulcers. Identifying the primary causal factors of resistance shall improve clinical management. In this study, we sought to identify the underlying mechanisms of fluoroquinolone and aminoglycoside resistance in MDR, non-MDR, and drug susceptible P. aeruginosa (n = 19) strains obtained from keratitis patients. Phenotypic assays were performed to study the bacterial growth kinetics, efflux, permeability, and biofilm formation. Mutational alteration of target genes (DNA sequencing), relative expression of efflux system genes (real time PCR), and detection of aminoglycoside modifying enzyme (AME) genes (PCR) were done by molecular methods. We repeatedly found the mutations in quinolone resistance determining region of fluoroquinolone target genes, gyrA and parC, and the presence of AME genes, aph(3″)-I and aph(6)-I, in all MDR isolates. Furthermore, the MDR isolates were largely characterized by slower growth, cytotoxic type III secretion system genotype, better biofilm-forming ability, and the presence of additional AME genes. The non-MDR isolates were resensitized upon inhibition of active efflux or enhancement of membrane permeability. Altogether this study highlights target gene alteration and enzymatic drug modification as the major mechanisms of quinolone and aminoglycoside resistance in P. aeruginosa keratitis isolates.

Smartphone-based application improves the detection of retinoblastoma.

PURPOSE: To improve and validate the smartphone-based leukocoria detection application so that non-ophthalmologists could make use of the smartphone for early detection of Retinoblastoma (RB) in young children without anesthesia and pharmacological dilatation of the pupil. METHODS: Two apps, MDEyeCare and CRADLE, developed for red reflex based leukocoria detection were used in iPhone 6s. MDEyeCare methodology was modified with respect to ambient lighting, the distance between camera and eye and different gazes for better performance. We analyzed totally 34 eyes of 23 RB patients and four normal children. Each of the RB patients was confirmed with clinical examination and radiological investigations. RESULTS: Modification in the methodology of MDEyeCare app could detect the leukocoria in early stages of RB (50% of Group B, 83% of Group C). In late stages (Group D and E), 100% of tumors were detected. The CRADLE app failed to provide adequate leukocoria detection except four late stage RB eyes. Among the 14 normal eyes (6 from unilateral RB and eight from normal children), pseudo-leukocoria was observed in three eyes only at lateral gaze even with MDEyeCare app. CONCLUSION: Improved methodology in smartphone-based app enhanced the detection of RB and this may translate into better outcome after treatment with respect to vision salvage.