RESEARCH. The podcast Akademiliv is back, and invited guest is Gunnar C Hansson, professor and world-leading researcher in mucin biology. In this podcast, we learn that the ‘C’ in his name stands for Claes, and he tells how his coworkers continue to investigate the thin and invisible mucus layer that protects our intestines from infection. Still, after thirty years of work in the field, we really know quite little about how the complex network of the large molecules that make up the mucus works.
The podcast is in Swedish. Here you can hear the podcast with Gunnar C Hansson: https://soundcloud.com/sahlgrenskaakademin/slemmet-som-skyddar-vara-tarmar-och-luftvagar
The first experiments that suggested that there is something that creates a gap between the intestinal mucosa and the contents of the intestine was made by Lena Holm, now Professor Emerita at the Department of Medical Cell Biology in Uppsala, says Gunnar C Hansson. In her experiment, she released carbon particles onto a gut, and could see that they did not fall all the way down to the mucous membrane, but landed a little bit above. Gunnar C Hansson and his co-workers could then show that this gap is a mucus layer, that is hard to detect but very important for the protection of the gut. In humans, the mucus layer is about 0.2 or 0.3 millimeters thick, and it is systematically created and maintained by cells in the colon.
In our intestines there are as many bacteria as we have cells in the body. Previously, it was the general perception that the human immune systems could distinguish between the bacteria that are good for us and those who are bad, and that was considered the reason why we did not get sick of the bacteria in the intestine.
“The discovery of the mucus layer and the continued mapping of how it works, has changed the perspective and means that the body has a special system that minimizes us the gut’s contact with bacteria, which protects us from infection,” Gunnar says in the podcast.
Research is a very slow process, and it also takes a long time before new discoveries are fully accepted by other researchers.
“Clinicians who work with the intestine understood the importance of the protective mucus layer at once, while biological researchers were more difficult to convince,”
After a few years, the findings by Gunnar and his colleagues about the mucus layer were highlighted in review articles by renowned researchers in the US.
Illustrated in textbooks
“We then began to be invited to present about our findings in the US, and after that also in Europe. Even here in Sweden, researchers eventually understood the significance of the findings. Here in Gothenburg, it took maybe for the longest time before the finding was properly accepted. Perhaps it’s a classic that it’s always hardest at home”, says Gunnar, laughing.
Nowadays, the protecting mucus layer in the gut is fully accepted, and also added in illustrations in textbooks on anatomy.
“That pleases me. Sometimes I look at pictures and I can see that the illustrator has misunderstood some aspects of what we know about how the mucus layer and how it works. For example, the illustrations do not always take into account that the mucus layer functions differently in the colon and the small intestine.
TEXT AND PHOTO: ELIN LINDSTRÖM CLAESSEN