Can a special diet help against certain cases of asthma? A new study at the University of Bonn at least suggests this conclusion. Accordingly, mice that were switched to a so-called ketogenic diet showed a significantly lower inflammation of the respiratory tract. The results now appear in the renowned specialist journal “Immunity”.
Asthma patients react to low concentrations of some allergens with violent inflammation of the bronchi. These also go hand in hand with increased mucus production, which makes breathing more difficult. Cells of the innate immune system play a central role here, which were only discovered a few years ago and are called Innate Lymphoid Cells (ILC). They take on an important protective function in the lungs by regenerating damaged mucous membranes. For this purpose, they produce inflammatory messengers from the group of cytokines, which stimulate the mucosal cells to divide and promote mucus production.
This mechanism is actually very useful: the body can quickly repair damage caused by pathogens or harmful substances. The mucus then transports the pathogens out of the bronchi and protects the respiratory tract against re-infection. “In asthma, however, the inflammatory response is far stronger and longer than normal,” emphasizes Prof. Dr. Christoph Wilhelm from the Institute of Clinical Chemistry and Pharmacology, who is a member of the Cluster of Excellence ImmunoSensation at the University of Bonn. The result is extreme breathing difficulties, which can even be life-threatening.
The ILC multiply rapidly in this process and produce large amounts of inflammatory cytokines. If you could slow down their division, it would probably be possible to control the excessive reaction, scientists hope. In fact, the results now published point in exactly this direction. “We have investigated which metabolic processes are active in the ILC when they switch to multiplication mode,” explains Wilhelm’s colleague Dr. Fotios Karagiannis. “Then we tried to block these metabolic pathways and reduce the speed at which the cells divide.”
In fact, with ILC dividing, some metabolic pathways were significantly more active. Above all, they ensure that the cells are supplied with energy and with the building blocks that they need for reproduction. The latter include, for example, fatty acids that are used to manufacture the cell membrane. This forms a thin skin with which cells separate themselves from their surroundings. “Activated ILC therefore take up fatty acids from their environment and briefly store them inside in small droplets, an important intermediate step in order to be able to generate membranes from them,” explains Karagiannis.
But what if you force cells to use these fatty acids elsewhere? To answer this question, the researchers put asthma mice on a diet that consisted primarily of fats but hardly any carbohydrates and proteins. With this diet, also known as the ketogenic diet, the metabolism of cells changes: the energy they need is now gained from burning fat. However, they lack the fatty acids they need to form new membranes during cell division.
As a consequence, the division activity of the ILC in the appropriately fed rodents decreased – namely drastically: “Normally, the number of ILC in the bronchial tubes increases fourfold upon contact with allergens,” says Prof. Wilhelm. “In contrast, it remained almost constant in our experimental animals. Accordingly, both mucus production and other asthma symptoms decreased. “
This is not only due to the switch to fats as an alternative energy source and the resulting shortage of fatty acids. Presumably, the lack of glucose also contributes directly to the reduced activity of the ILC. “Asthma has increased significantly in frequency in the past decades. This may also have something to do with the increasingly high sugar and fat diet, ”speculates Wilhelm.
The scientists now want to use patients to investigate whether a ketogenic diet can prevent asthma attacks. However, this is not entirely harmless in the long term and should only be carried out after consultation with a doctor. “We are therefore trying to find out which components of the diet change are responsible for the effect,” explains Wilhelm. “Perhaps this will open the way to the development of new drugs.”
It is known that a ketogenic diet can be an effective therapy for some diseases. For example, patients with certain forms of epilepsy are treated with this method. And the change in diet should also help with some tumors – after all, the cells in them also multiply unusually strongly.
The study was published in University of Bonn