Microbiome – the world within us

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Alain Welter

Did you know that roughly 1.5kg of microbes from more than 1000 different species live in our guts? Not only do they live there, they also have a profound impact on our health. When we are healthy, the different kind of microbes live in balance. However, if certain types of bacteria become more abundant than others, the balance is disturbed and diseases may arise. At the LCSB, we want to find out how such an imbalance can trigger different types of diseases and which microbes are involved.

Who is there and what do they do?

The first step is to see if the composition of bacteria is changed in a given disease. Therefore, the team of Associate Prof. Paul Wilmes collects stool samples from both patients and healthy people. From those they can identify which types of bacteria live in the gut and how many thereof. Recently, they showed striking differences between Caesarean and vaginally born babies: the microbiome of Caesarean born babies develops and stimulates the immune system differently compared to those born vaginally . This demonstrates that the exposure to the mother’s bacteria in the birth canal has an important function for the health of the baby. Hence, people might want to think twice before opting for a Caesarean section without medical indication.

Microbiome dysbiosis / Linda Wampach
© Linda Wampach

The microbial fingerprint of our stool could also serve as a diagnostic marker, even in diseases that seem to occur far away from the gut. In the very early stages of Parkinson’s disease, even before movement problems occur, people show already a different microbiome composition in their gut compared to healthy people.

Similarly, difference have also been found between people with and without type1 diabetes. Here our researchers could show additional functional difference, i.e. what those bacteria do: vitamin B1 synthesis was reduced in the gut of diabetes type 1 patients, in line with the clinical symptoms experienced by the patient.

Microbiome babier / Linda Wampach
© Linda Wampach

Chicken or egg?

The examples above show that different microbes exist in different amounts in patients with different diseases. But did this change in microbes trigger the disease or is it rather a consequence of the disease? To answer this “chicken or egg” problem, our scientists have developed HuMiX, an artificial gut-on-a-chip. In this device, we can culture different types of microbes together with cells of the gut and hence analyse their effect on the health of gut cells in detail.

Using the HuMiX device our scientists could recently show the importance of dietary fiber for colon cancer patients. The right combination of dietary fiber and gut microbes slowed down cancer progression in cell culture models! This confirms earlier work in mice that showed that a low-fibre diet destroys the mucus layer in the gut, thereby increasing the risk for infections. Fibres can be found in fruits, vegetables and grains. A balanced diet rich in fibre will hence not only keep your gut healthy, but can have an important effect on your health in general!