Thursday, June 21, 2012

Gut bacteria help us to fight off virus infections

We have a peculiar relationship with bacteria. Some are out there to kill us, but some of them do not harm us at all, and are in fact quite beneficial. Those that live in our intestines help us with food digestion, and their presence makes sure that gut space cannot be taken up by bad bacteria that constantly try to infect us. New research shows that our small friends in the gut do more than just that: they also help us to get rid of viruses. It was already known that having bacteria in our intestines was needed for our survival, but it appears this is true in more ways than previously assumed.

Experiments showed that treating mice with antibiotics reduced the number of bacteria living in our body. Consequently, it made the animals more susceptible to viral infections and increased the death toll resulting from an experimental influenza infection. Mice that did manage to survive with reduced bacterial numbers showed a slower response by the immune system resulting in increased tissue damage due to the infection.

Immune system
Diving into the mechanism behind this form of bacterial protection, the scientists found that bacteria send signals to immune cells that help them mature. Basically, that stimulates the launch of an attack against viruses that managed to invade the body, revealing the importance of bacterial-cellular communication. The scientists found that without bacterial signals, immune cells were unable to produce proteins known as interferons, that help set up an immune response.

Because of the newfound role of native bacteria in the immune response against bacteria, scientists gain new possibilities to develop antiviral drugs. We may be able to harness the power of these friendly bacteria and increase the body's immune response artificially, thereby limiting the effect that viral infections have on patients. More research into the exact mechanism is needed, however, before any new drugs can be developed.

The immune interaction between bacteria and body cells is another interesting example of the symbiosis between microbes that live in our body and ourselves. Previous research revealed that they also play a role in fighting off pathogenic bacteria, that are out there to harm us. Because they help with digesting our food as well, gut bacteria truly are indispensable, and we should be glad to host them.
An inflamed piece of lung tissue in a mouse used in the experiments. The coloured parts represent different types of immune cells.

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