Can you smell germs

Mice avoid sick conspecifics. A special olfactory organ plays a role here, with which they can recognize infected animals. A study has now uncovered a new mechanism that the sense of smell and the immune system use together to detect and prevent infections. But what about us humans? Can we also smell impending infections?

At the Zweibrücken campus of Kaiserslautern University of Applied Sciences , Professor Bernd Bufe from the Chair of Molecular Immunology and Immune Sensing is investigating the role of the sense of smell and taste in the defense against pathogens. He is the first author of a paper on the topic that has just been published in the current issue of Nature Communications. “We have made a surprising discovery,” explains Bufe, “there are receptors that are used jointly by the sense of smell and the immune system to prevent infections . Our new study on the olfactory system, which we conducted in close collaboration with Prof. Coincidence carried out by Saarland University on the Jakobson’s organ of the mouse have shown that mice can perceive and avoid typical metabolic products of highly dangerous bacteria with this organ ” Mice are ideal study subjects for this because they have a very pronounced sense of smell. The Jakobson’s organ is a special olfactory organ of the mouse, which, like the olfactory mucosa, is assigned to the olfactory system. “Various receptors in this olfactory organ control behavior. If the animal is exposed to the smell of a sick conspecific, it will avoid it. If we switch off the receptor responsible for this, the avoidance behavior of the mouse is also eliminated,” says Bufe.

According to the researcher, the animals use this mechanism to protect themselves from bacterial infections. The research group led by Professor Bufe is now asking the question: Do similar receptors also exist in the sensory organs of humans and can they be used to detect diseases? They are not yet precisely known, but there are similar receptors in humans, which could intervene in the invasion of bacteria long before other parts of the immune system become active. For example, olfactory and taste receptors help us to recognize and avoid food that has been spoiled by bacteria. “We know that such receptors are excellent at recognizing complex chemical signatures of pathogens and that some of them are also found in immune cells,” explains Bufe. According to the hypothesis of the working group, these receptors could therefore also help with immune defense. The aim of further research is therefore to find out whether such receptors are involved and what happens after the receptors are activated. To this end, the team is looking at the evolutionary development of the receptors in different animals . “We are investigating the reasons why some animal species are infected by certain bacteria and others are not. This helps us to understand how we can better prevent infections,” says Bufe, describing his work at the university.

In order to investigate the reaction of sensory receptors to different pathogens , the research group uses the latest methods of high-throughput microscopy. Large quantities of samples are processed automatically. The cell fluid to be examined at is applied to special plates with numerous small indentations. Images are then taken automatically under the microscope and the resulting images are read out using software. This allows you to make many attempts at the same time in a very short time. “With normal microscopy, this would take years,” says Professor Bufe, describing the advantages of high-throughput microscopy.

The research group specializes in the study of formyl peptide receptors . Individual representatives of the receptors recognize more than 100,000 extremely different bacterial signal peptides. These signal peptides of the pathogens transport protein molecules to the cell surface. “You can imagine the like a barcode or an address label, and these barcodes can be perceived by the formyl peptide receptors of the immune system ,” says Bufe. Receptors for signal peptides are not only found in immune cells, but also in other places in the body, for example in the intestine. Therefore the research group suspects that the perception of these peptides helps the body in many places in the defense against pathogens. A better understanding of these processes can lead to new therapeutic approaches in the fight against antibiotic-resistant bacteria and help combat certain intestinal diseases.