Infection with Pseudomonas aeruginosa is a major problem for patients in hospital, who are at increased risk of infection because they often have a weakened immune system, as well as individuals with cystic fibrosis. One of the things that makes P. aeruginosa so virulent is the expression of a number of proteins that function as a type III secretion system.
In a study that appears online on January 18 in advance of publication in the February print issue of the Journal of Clinical Investigation, researchers from the University of California at San Francisco, have identified Cbl-b as a protein that helps protect mice from infection with P. aeruginosa by targeting one of the components of the type III secretion system, ExoT.
Joanne Engel and colleagues found that in cultured human cells, ExoT was targeted for destruction by the host protein Cbl-b. More importantly, ExoT was shown to be important for bacterial dissemination in mice infected with P. aeruginosa and mice lacking Cbl-b were more susceptible to both intranasal and systemic infection with P. aeruginosa than wild-type mice.
This study therefore identifies Cbl-b as a component of early host defense against infection with P. aeruginosa, an observation that could help develop new strategies for the treatment of individuals infected with this major opportunistic pathogen.
Reference: The ubiquitin ligase Cbl-b limits Pseudomonas aeruginosa exotoxin T--mediated virulence (https://www.the-jci.org/article.php?id=28792)
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