Whipping up immunity

Immunity illustration

Emory scientists are looking in an unusual place for a way to bulk up the body’s defenses—the tails of bacteria. What they are finding is that flagellin—a building block of the miniature whips that bacteria use to move—may act as a protective agent to strengthen the body’s innate defenses.

“Flagellin activates the body’s own internal defense pathways,” says Emory pathologist Andrew Gewirtz. “It also helps cells survive situations where they’d usually die.”

The immune system evolved to recognize flagellin because so many types of bacteria have it. When cells in the lungs and intestines sense flagellin’s presence, an ensuing flurry of signals strengthens barriers and stimulates immune cells that can go after invaders.

Previously, Gewirtz’s team demonstrated the versatility of flagellin. They found that it has the ability to protect mice against a lethal dose of radiation, a severe intestinal irritant, Salmonella, and rotavirus.

The radio-protective aspects of flagellin suggest that it could be used for civil defense, for example, in mitigating the effects of radiation exposure after a nuclear power plant meltdown or for cancer patients receiving radiation therapy. This property of flagellin has interested both biotech companies and the U.S. military in bacteria’s tiny whips.

At Emory, Gewirtz’s laboratory is concentrating on viral infections. The researchers have found that a flagellin treatment can help prevent and also clear chronic rotavirus infection. The next step is to figure out whether its properties could apply to viruses such as HIV or hepatitis C.

Flagellin also stimulates cells that make up the soft tissues assaulted by the influenza virus, leading Emory microbiologists Ioanna Skountzou and Richard Compans to investigate whether flagellin would make a good component for a flu vaccine. In animal models, Emory hematologist Edmund Waller is testing flagellin’s ability to promote healthy immune reconstitution and prevent graft-versus-host disease after a bone marrow transplant. —Quinn Eastman

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