Biology subjects

Jhanji, V.

Publications and source records attributed to Jhanji, V..

5 recordsLinked to original sources

bioRxiv2026

Defining the Functional Consequence of the Human Ocular Microbiome

The ocular surface is one of the body's most environmentally exposed mucosal barriers, yet it is considered low biomass and harbors orders of magnitude fewer bacteria than microbe-rich sites like the gut. This has cast doubt on whether a functional core ocular microbiome exists at all. Having previously defined a protective gd T cell and IL-17 axis engaged by the murine commensal Corynebacterium mastitidis, we asked whether human-derived bacteria could do the same. Pairing sequencing and culturomics of healthy human conjunctiva from two geographically distinct cohorts, we define a stable core microbiome and identify Corynebacterium bovis as a consistent eye-resident commensal rather than a transient contaminant. In humans, C. bovis elicits a non-pathogenic response marked by IL-17 secretion by {gamma}{delta} T cells and circulating C. bovis-specific IgG, which suggests commensalism rather than pathology. Colonizing mice with human C. bovis strains from Pittsburgh or Miami reproduced this program and conferred protection against ocular infection with Staphylococcus aureus. Together, these findings identify C. bovis as a human-derived ocular commensal that can drive protective {gamma}{delta} T cell immunity, translating a mechanism previously defined only in mice into human relevance and a rational target against sight-threatening infection.

immunology↗

bioRxiv2023

Rise in frequency of lasR mutant Pseudomonas aeruginosa among keratitis isolates between 1993 and 2021

Pseudomonas aeruginosa causes severe vision threatening keratitis. LasR is a transcription factor that regulates virulence associated genes in response to the quorum sensing molecule N-3-oxo-dodecanoyl-L-homoserine lactone. P. aeruginosa isolates with lasR mutations are characterized by an iridescent high sheen phenotype caused by a build-up of 2-heptyl-4-quinolone. A previous study indicated a high proportion (22 out of 101) of P. aeruginosa keratitis isolates from India between 2010 and 2016 were sheen positive and had mutations in the lasR gene, and the sheen phenotype correlated with worse clinical outcomes for patients. In this study, a longitudinal collection of P. aeruginosa keratitis isolates from Eastern North America were screened for lasR mutations by the sheen phenotype and sequencing of the lasR gene. A significant increase in the frequency of isolates with the sheen positive phenotype was observed in isolates between 1993 and 2021. Extracellular protease activity was lower among the sheen positive isolates and a defined lasR mutant. Cloned lasR alleles from the sheen positive isolates were loss of function or dominant negative and differed in sequence from previously reported ocular lasR mutant alleles. Insertion elements were present in a subset of independent isolates and may represent an endemic source from some of the isolates. Retrospective analysis of patient information suggested significantly better visual outcomes for patients with infected by sheen positive isolates. Together, these results indicate an increasing trend towards lasR mutations among keratitis isolates at a tertiary eye care hospital in the United States.

microbiology↗

bioRxiv2020

Genomic and phenotypic diversity of Enterococcus faecalis isolated from endophthalmitis

Enterococcus faecalis are hospital-associated opportunistic pathogens and also causative agents of post-operative endophthalmitis. Patients with enterococcal endophthalmitis often have poor visual outcomes, despite appropriate antibiotic therapy. Here we investigated the genomic and phenotypic characteristics of E. faecalis isolates collected from 13 patients treated at the University of Pittsburgh Medical Center Eye Center over 19 years. Comparative genomic analysis indicated that patients were infected with E. faecalis of diverse multi-locus sequence types (STs) previously associated with clinical, commensal, and environmental sources. We identified known E. faecalis virulence factors and antibiotic resistance genes in each genome, including genes conferring resistance to aminoglycosides, erythromycin, and tetracyclines. We assessed all isolates for their cytolysin production, biofilm formation, and antibiotic susceptibility, and observed phenotypic differences between isolates. Fluoroquinolone and cephalosporin susceptibilities were particularly variable, as were biofilm formation and cytolysin production. In addition, we found evidence of E. faecalis adaptation during recurrent endophthalmitis by identifying genetic variants that arose in sequential isolates sampled over eight-months from the same patient. We identified a mutation in the DNA mismatch repair gene mutS that was associated with a hypermutator phenotype in the final isolate from the patient, which was also more resistant to ceftazidime. Overall this study documents the genomic and phenotypic variability among E. faecalis causing endophthalmitis, as well as possible adaptive mechanisms underlying bacterial persistence during recurrent ocular infection. IMPORTANCEBacterial endophthalmitis is a sight-threatening infection of the inside of the eye. Enterococcus faecalis cause endophthalmitis occasionally, but when they do the infections are often severe. Here we investigated the genomes, antibiotic susceptibilities, and virulence-associated traits among E. faecalis collected from 13 patients with post-operative endophthalmitis. We wondered whether there were common bacterial factors that might explain why enterococcal endophthalmitis is so destructive to ocular tissues. Instead we found that E. feacalis isolated from endophthalmitis were genetically and phenotypically diverse; isolates belonged to a variety of genetic lineages and showed varying levels of antibiotic resistance and biofilm formation. We also undertook further characterization of three closely related E. faecalis isolates from a patient with recurrent endophthalmitis, and found that a hypermutator strain emerged during persistent infection. Hypermutators have been found in a variety of other infection contexts; here we describe what we believe is the first case of a hypermutator arising during ocular infection.

microbiology↗

bioRxiv2020

KLF4 coordinates corneal epithelial apicobasal polarity and plane of cell division, and is downregulated in ocular surface squamous neoplasia

Apicobasal polarity (ABP) is an important feature of many epithelial cells, including those in the stratified squamous corneal epithelium (CE). Previously, we demonstrated that KLF4 promotes CE homeostasis by suppressing epithelial-mesenchymal transition (EMT) and TGF-{beta} signaling. As dysregulation of TGF-{beta} signaling affects ABP, we investigated the role of KLF4 in regulating cell polarity and plane of division by spatiotemporally regulated ablation of Klf4 in adult ternary transgenic Klf4{Delta}/{Delta}CE (Klf4LoxP/LoxP/Krt12rtTA/rtTA/Tet-O-Cre) mouse CE. Klf4{Delta}/{Delta}CE cells displayed decreased expression and mis-localization of apical polarity markers Pals1 and Crumbs1, apicolateral Par3, and basolateral Scribble. Cdc42 was upregulated, while Rac and Rho were mis-localized in the Klf4{Delta}/{Delta}CE cytoplasm unlike their cortical expression in the control. Phalloidin staining revealed disrupted actin cytoskeleton in the Klf4{Delta}/{Delta}CE cells. Survivin and phospho-histone-H3 immunostaining revealed a tilt in the plane of cell division favoring symmetrical divisions with vertical axis in the Klf4{Delta}/{Delta}CE compared with predominantly asymmetrical divisions with horizontal axis in the control. Human ocular surface squamous neoplasia (OSSN) tissues displayed signs of EMT and loss of ABP markers PAR3, PALS1 and SCRIB, coupled with downregulation of KLF4. By demonstrating that Klf4 ablation affects CE expression of ABP markers and Rho family GTPases, cytoskeletal actin organization and the plane of cell division, and that KLF4 is downregulated in OSSN tissues that display EMT and lack ABP, these results elucidate the key integrative role of KLF4 in coordinating CE cell polarity and plane of division, loss of which results in OSSN.

cell biology↗

bioRxiv2019

Clinical investigation and genetic analysis of a peripheral sclerocornea pedigree

BackgroundSclerocomea is a rare congenital disorder characterized with cornea opacification. We identified a heterozygous missense RAD21 variant in a non-cons anguineous Chinese family with multiple peripheral sclerocomea patients spanning across three generations inherited in an autosomal dominant manner. MethodsComprehensive ophthalmic examinations were conducted on all 14 members. Whole exome sequencing was used to identify the genetic alterations in the affected pedigree members. Lymphoblastoid cell lines (LCLs) were established using blood samples from all members. Cleavage of RAD21 protein was quantified in these cell lines. ResultsAll affected individuals showed features of scleralization over the peripheral cornea of both eyes. Mean horizontal and vertical corneal diameter were significantly decreased in the affected members. Significant differences were also observed on mean apex pachymetry between affected and unaffected subjects. A RAD21C1348T variant was co-segregated with affected members. Both the wild-type allele and the missense variant were expressed at the mRNA level. This variant caused RAD21 R450C substitution at the separase cleavage site, which led to reduced RAD21 cleavage. ConclusionWe believe this is the first report of genetic variant in sclerocornea without other syndromes. Further work is needed to confirm the RAD21R450C variant with sclerocomea.

genetics↗