# Mechanisms for bacterial dissemination in corneal infection

> **NIH NIH F32** · UNIVERSITY OF CALIFORNIA BERKELEY · 2020 · $47,900

## Abstract

Project Summary
Pseudomonas aeruginosa is among the most common causes of blinding corneal disease, while
also being a major cause of life threating nosocomial infections such as pneumonia, bacteremia,
urinary tract infections (UTIs), and cytstic fibrosis (CF), targeting immunocompromised and
critically injured patients. Publications from the Fleiszig lab have shown that twitching motility, a
type of surface associated movement, contributes to the ability of P. aeruginosa to penetrate
human corneal epithelial cell multilayers in vitro and is critical to pathogenesis of P. aeruginosa
corneal infection in a mouse model in vivo. Key to P. aeruginosa pathogenesis in the cornea is
the capacity of the bacteria to invade corneal epithelial cells. While P. aeruginosa mutants that
lack twitching motility can invade epithelial cells, and replicate inside them just as efficiently as
wildtype bacteria, they have reduced capacity for exiting cells they have entered. During my
postdoctoral fellowship in the Fleiszig lab, I used imaging and various other methods to study the
mechanisms by which P. aeruginosa exits epithelial cells. Importantly, my preliminary data show
that exit does not necessarily follow cell death, suggesting active/deliberate mechanisms
contribute. My data further show that when twitching mutants invade and replicate in corneal
epithelial cells, they differ from wildtype P. aeruginosa in being unable to distribute themselves in
the cytoplasm and instead accumulate in aggregates. I have also screened a mutant library for
exit capacity, and have found that mutants in either of two phospholipases, PlcB or PA2155, are
exit defective. In contrast to twitching mutants, the phospholipase mutants spread normally
throughout the host cell cytoplasm. Thus, my data mechanistically separate the exit process into
two stages one dependent on twitching and the other dependent on phospholipases. My
theoretical model for exit is that P. aeruginosa uses twitching motility to avoid forming a biofilm
aggregate inside the cell and to access the host cell plasma membrane, where they use
phospholipase activity (e.g. of PlcB and PA2155) to alter the plasma membrane to provide an exit
route. Thus, in aim 1 I will the identify the genes transcripts that impact twitching mutant
aggregation and exit compared to wildtype, and in aim 2 I will determine if phospholipases
facilitate exit through their enzymatic activity. While contributing to our understanding of P.
aeruginosa pathogenesis, this project could ultimately contribute to development of strategies for
preventing and treating infections that act by preventing bacterial penetration through our
protective surface epithelia.

## Key facts

- **NIH application ID:** 9918910
- **Project number:** 5F32EY029152-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** Vincent Nieto
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $47,900
- **Award type:** 5
- **Project period:** 2018-05-01 → 2020-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9918910

## Citation

> US National Institutes of Health, RePORTER application 9918910, Mechanisms for bacterial dissemination in corneal infection (5F32EY029152-03). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/9918910. Licensed CC0.

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