A Trillion First Responders

To keep us safe, our body coordinates with a vast network of foreign agents that have joined our side.

It’s the largest security force in the world. A teeming network of first responders that live on nearly every surface of your body, inside and out. They’re not part of the body, like your immune system—they’re immigrants—but they’re still naturalized citizens, and without them your world couldn’t function. Since the Human Microbiome Project began in 2008, biologists have begun to uncover just how closely your body relies on these semiautonomous partners in securing your well-being. From the skin to the lining of the intestine, the trillions of bacteria and viruses that make up your own personal microbiome keep you safe from invading diseases. Someday soon, scientists hope to train them for new roles, like fighting cancer and providing early warning of infections.

The body cells in our immune system do a great job of protecting us on the inside, but they provide little to no protection for surfaces like skin and the lining of the intestine. That job is outsourced to the microbiome. The billions of bacteria in the microbiome act like a security force that bars vagrant disease-causing microbes from hanging out in dark alleys. They also alert the immune system when they encounter a threat they aren’t equipped to handle.

Trillions of bacteria and viruses that make up your own personal microbiome keep you safe from invading deseases.

Unlike security patrols, these public servants don’t move around independently. Instead, during a security breach they clone themselves on the spot to form a tight line of newly born, fully armed adult protectors.

Good Cop, Bad Cop

But not every threat comes from the outside. Sometimes, some of these micro-protectors get a little overzealous. They accidentally multiply too much and block absorption of food in the intestine or gum up pores in our skin. At other times, good bacteria go rogue.

In this fallen world, several mishaps can corrupt good bacteria. For instance, Helicobacter pylori are supposed to help control appetite by controlling hormones that make us feel hungry, or so it appears. Sadly, these same bacteria may play a part in causing ulcers in our stomachs when we are under stress.

E. coli is another well-known example. It coats our intestines, helping with digestion and making vitamins. But if a certain virus infects E. coli, it can become deadly.

Riot Control

When good bacteria multiply too much or go bad, elite SWAT teams rush in to control the disturbance. These nano-security forces come in two forms, exploders and vacuumers.

The exploders, called phages (a type of virus that infects bacteria), are the most numerous biological forms on earth. Tens or hundreds of them can live in each bacterial cell. When the bacteria become too rowdy or malicious, the phages can explode them to help control the populations. Then they slough off the skin, along with other debris.

But on internal surfaces, such as the intestine lining, too many exploded bacteria pieces just lying around might cause a panic, and the immune system will swoop in. Such an overreaction can cause inflammation, which may be life-threatening and wipe out good bacteria with the bad.

The vacuumers’ job is to eliminate the threat without causing a mess. One vacuumer, called Bdellovibrio, is a small bacterium that can infiltrate the larger bacteria. Once inside, these tiny commandos use specialized secretion and suction equipment to chop up the bacteria from the inside and vacuum up the pieces so none are left to alert the immune system.

To Serve and Protect

Recent studies have shown that good health requires having enough Bdellovibrio bacteria in our system. Indeed, researchers are testing ways these disrupter and clean-up agents might also be trained to fight cancer. Phages offer another exciting avenue of research. The slightest disruption from infection can cause the microbiome to release phages. A simple test during routine checkups might detect these phages long before you develop other more serious symptoms.

We are learning that our merciful Creator supplied our bodies with a finely balanced, resilient community of protectors that keeps us running well. Rather than competing against each other to survive, these organisms are designed to work together in an intricate web of communication and service for our good and God’s glory.

Dr. Joe Francis, chairperson of the Department of Biological and Physical Sciences and Department of Mathematics at The Master’s University, earned his PhD from Wayne State University and completed a post-doctoral fellowship at the University of Michigan Medical School.

Answers Magazine

October–December 2016

Your irresistible urge to snatch up that cute little puppy and hug it for all youʼre worth isnʼt just a feeling. Itʼs science.

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