Bad Bacteria Use Cheat Code with Electrical Signals to Invade the Gut

Scientists discover how bad bacteria use electrical signals to invade the gut in new study from UC Davis Health.

Researchers wanted to know how bad bacteria like Salmonella invade the gut. How do they know where to go and how to get there. Turns out. They have a cheat code.

They use electrical signals to invade the gut.

Salmonella Is Responsible for Over a Million Illnesses Each Year

According to the Centers for Disease Control and Prevention (CDC) the harmful bacteria, Salmonella, is responsible for around 1.35 million illnesses in the United States each year. An estimated 26,500 hospitalizations and 420 deaths are linked to this bad bug.

Pathogens Are Literally a Drop of Water in the Proverbial Ocean in the Intestines

Our gut contains trillions of helper bacteria that our bodies appreciate in many different ways. And this is not an exaggeration. Scientists estimate that around 100 trillion resident bacteria live in our digestive system.

From helping us to absorb certain nutrients, working with our immune system, to protecting us from bacterial infections. These happy microbes do all of the heavy lifting for us.

When bad bacteria enter the system, they are literally a drop of water in the proverbial ocean in the intestines.

“When ingested, Salmonella find their way to the intestines. There, they are vastly outnumbered by over 100 trillion good bacteria (known as commensals). They are facing the odds of one in a million!” says the study’s lead author Yao-Hui Sun, Research Scientist with UC Davis Departments of Internal Medicine, Ophthalmology and Vision Science, and Dermatology.

While navigating this mass of competitors and assassins, how does a tiny germ like Salmonella leave the intestines and invade the gut?

In a recent paper, Gut Epithelial Electrical Cues Drive Differential Localization of Enterobacteria, published in Nature Microbiology, Sun and other researchers put a literal microscope on this process. Albeit and fancy microscope with some pretty sophisticated features.

They observed both a harmless strain of E. coli bacteria commonly found in the human digestive system alongside Salmonella Typhimurium bacteria to identify how these bacteria overcome those huge obstacles.

Before you can understand how these germs overcome these obstacles, you must first understand what those obstacles are.

The Path to the Gut Is an Obstacle Course

The intestinal lining isn’t a smooth surface. It poses a sort of obstacle course just to find the sides. Certain epithelial structures like the follicle-associated epithelium, along with the protrusions from the enterocytes (absorptive cells) of the villus epithelium create an obstacle course as these pathogens make their way to their intended destination.

Beyond the intestines and into the body. Via the gut.

Do they just float aimlessly through digestive matter and mingle within the trillions of commensal microbes? No. They have a trick up their sleeve. If, harmful, vomiting and diarrhea inducing bacteria worse sleeves.

They use electrical signals to invade the gut.

Electrical signals produced by the follicle associated epithelium.

Intestines Are Full of M Cells – The First Line of Defense Against Invading Germs

The inside of the intestinal lining is made up of “follicle associated epithelium” cells. These are the gate keepers of the digestive system.

This is the target for pathogenic bacteria like Salmonella.

If they make it past that threshold, they can wreak havoc on other parts of the body.

Protecting that line are “microfold” M cells that lay on top of small clusters of lymphatic tissue. M cells have an important job. Antigen sampling.

Antigen sampling helps the body regulate the immune system, responding when a threat is detected. This makes M cells the first line of defense when it comes to invading germs.

To make it past those cell, bad bacteria must first be able to find them.

But how?

Turns out, bacteria use electrical signals to invade those areas.

Salmonella Use Electrical Signal to Invade the Gut Through a Process Called Galvanotaxis

M cells communicate beyond the intestinal wall. Throughout these activities, they produce a small electric field. Salmonella bacteria detect that electrical field and use those electrical signals to navigate to and invade the gut.

“Our study found that this ‘entry point’ has electric fields that the Salmonella bacteria take advantage of to pass,” said senior author Min Zhao, professor of ophthalmology and dermatology and researchers affiliated with the Institute for Regenerative Cures.

Salmonella use these signals as a literal beacon and set course to these vulnerable spots.

Do All Bacteria Use Electrical Signals to Invade the Gut?

As it turns out, not all bacteria use these electrical signals to invade the gut. Harmless bacteria like the non-pathogenic E. coli also observed in the study responded to those electrical beacons totally differently.

When observing the intestinal wall, E. coli are often found clustered next to the villi. While Salmonella bacteria gathered toward follicle associated epithelium targets.

Where Do Scientist Go from Here?

Science is a never-ending string of questions. Get one answer and several more questions are posed. So, where do scientist go from here?

The next logical step to identify if this concept can explain certain diseases like inflammatory bowel disease (IBD). Something Zhao expects is to be related.

“This mechanism represents a new pathogen-human body “arms race” with potential implications for other bacterial infections as well as prevention and treatment possibilities,” says Zhao. “It is believed that the root cause of IBD is an excessive and abnormal immune response against good bacteria.” They wonder if faulty bioelectric activities in gut epithelia could be the reason some patients are more prone to IBD than others. And if so, could this aberrant bioelectric process be amended to cure it?

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By: Heather Van Tassell (contributing writer, non-lawyer)