Specialized Cells in Intestine and Airways Act as First Line of Defense Against Invading Microbes

Researchers led by David Lo from UCR laboratory have found that certain specialized cells of epithelium, or the inner lining of the intestines and airways, act as the first line of defense against microbes and create an electrostatic repulsion field against the invading parasites.

The study is featured on the cover of the July issue of Infection and Immunity, a journal published by the American Society for Microbiology. Co-authors of the study are Kaila M. Bennett, one of Lo's graduate students, and Sharon L. Walker, a UCR professor of chemical and environmental engineering.

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The finding improves scientists' understanding of the densely packed protrusions – resembling a carpet – on the surface of some cells that line the insides of the intestines and respiratory system. The protrusions, which biologists call microvilli, increase the surface area of cells and have a role in absorbing nutrients, for instance.

But Lo's laboratory has found that the microvilli actually repel negatively charged bacteria and viruses, suggesting a protective "shield" akin to the force field that envelops the Enterprise in the plots of many "Star Trek" television episodes and movies.

"This is a whole new way of looking at immune surveillance in the epithelium of the human gut and airway," said Lo, a distinguished professor in the medical school's Division of Biomedical Sciences. "If we can take advantage of this electrostatic repulsion, it could improve the diagnosis and treatment of certain bacterial infections."

A number of bacterial and viral infections can gain a foothold in the human body through adsorption via the intestines and airways, such as Salmonella and the flu.

Lo's laboratory has for more than a dozen years studied immune responses in the gut and airways, focusing particularly on cells which function as an early warning in the immune system. "We study the role of certain epithelial cells in the immune system. By understanding how the immune system is able to capture and carry viruses and bacteria across this barrier to trigger a protective immune, we may be able to design better synthetic vaccines, including needle-free vaccines," Lo said.

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Lo joined UCR in 2006. In addition to his faculty position in the UCR School of Medicine Division of Biomedical Sciences, he is affiliated with the UCR Center for Disease Vector Research and the UC Global Health Institute. He is a fellow of the American Association for the Advancement of Sciences (2007) and a 2005 recipient of a "Grand Challenges in Global Health" award, Bill and Melinda Gates Foundation and the Foundation for the National Institutes of Health.

Source-Eurekalert