Source: Purdue University
Summary: Researchers have found another pathway that Listeria uses to enter the bloodstream, suggesting that forms of the food-borne bacteria considered benign may be more dangerous than once thought.
According to the WHO, about 600 million people around the world contract listeriosis each year, with 420,000 dying. Pregnant women, newborn children, adults 65 and older and people with weakened immune systems are most at risk. The pathogen is found most often in deli meat, hot dogs, dairy products and produce. To infect someone, the Listeria monocytogenes bacteria must cross the epithelial barrier, a wall of cells in the gut that generally protects the bloodstream from harmful pathogens. It has long been believed that a protein called Internalin A, found in many forms of Listeria, is required for breaking through that barrier. Researchers from Purdue University have found another pathway that Listeria uses to enter the bloodstream, suggesting that forms of the food-borne bacteria considered benign may be more dangerous than once thought. The study findings were published in the journal Cell Host & Microbe.
The team findings, show Listeria adhesion protein (LAP) interacts with heat shock protein (HSP) in mice, then the epithelial cells move apart to give the bacterium access to the bloodstream. But that is just one path the bacteria might use to infect a host. Since the Internalin A receptors are sandwiched between epithelial cells in humans, they are inaccessible to the Internalin A protein. The findings are also important because Listeria strains that have the defective or nonfunctional Internalin A protein haven’t been considered dangerous. But if the bacteria have another way through the gut and into the bloodstream regardless of Internalin A, that’s no longer true.
Prof. Arun Bhunia said, “When LAP interacts with HSP, those cells move apart, not only giving the bacterium access to the bloodstream, but also exposing the Internalin A receptors and allowing transport of Listeria monocytogenes into the bloodstream, which likely happens in humans”, “Now that we know the mechanism, we can look at how to block this pathway to prevent the infection.”
More Information: Listeria Adhesion Protein Induces Intestinal Epithelial Barrier Dysfunction for Bacterial Translocation”, Cell Host & Microbe (2018). www.cell.com/cell-host-microbe … 1931-3128(18)30133-1