A team at the La Jolla Institute for Allergy & Immunology in San Diego, US, found the molecule, known as HVEM, which is expressed by the cells lining the surface of the lung and intestine.
It's key to protecting the body from E-coli, pneumococcus and other bacterial infections that enter our bodies through the lining of our respiratory or intestinal tracts, said Prof Mitchell Kronenberg, who led the research.
"HVEM acts in these cells like a border guard that responds to the presence of invasive bacteria and signals the immune system to send in more troops. Without its involvement as part of the epithelial protective barrier, the body could be overrun by certain disease causing bacteria," Kronenberg said in a statement.
He expressed hope that the discovery will advance efforts toward developing new treatments or vaccines against bacterial infections.
"People knew that epithelial cells protect the body's mucosal borders from infection. But what wasn't known was that HVEM is critically important in turning on the epithelial cell anti-bacterial response," he said.
Epithelial cells line the body's mucosal borders, which include the mouth, nose, intestines and lungs and are the most common entry points for infectious pathogens.
In the study, published in the scientific journal Nature, the researchers used mice genetically engineered not to have HVEM. When these mice were exposed to pneumococcus or a mouse pathogen very similar to E-coli, the HVEM deficiency led to a much greater susceptibility to infection, higher bacterial burdens and significantly compromised the mucosal barrier.
"It is striking how similar the responses in the lung and the intestine were," said Dr Kronenberg. "The mice without HVEM were unable to respond effectively at either site, and the deficit was not only major but also nearly immediate, within two days of exposure to the microorganisms." (More)
