New study Can the innate immune system also be trained?

Also the innate immune system shows "training effects"

The immune system is generally differentiated into the innate immune defense and the acquired immune defense. So far, the assumption was that only the acquired immune system has a kind of memory and can be trained. But recent research suggests that the acquired immune defense is also subject to a training effect. How this works researchers have decrypted in a recent study.

Scientists TU Dresden have now analyzed the training effect of the innate immune system in a recent study. Accordingly, the progenitor cells of the white blood cells can be trained, which leads to a sustained positive reaction of the blood-forming system, reports the TU Dresden. The study results of the international research team led by Professor Triantafyllos Chavakis, Director of the Institute for Clinical Chemistry and Laboratory Medicine of the University Hospital Dresden, were published in the journal "Cell".

Congenital and acquired immune defense

"Two main systems protect us from infections, innate and acquired immunity"; explain the scientists of the TU Dresden. The former form, so to speak, the rapid physical response to infections in order to gain time until the acquired immunity (also adaptive immunity) is activated. The acquired immune defense then identifies and combats the pathogens in a very specific way and is proven to build an immunological memory. If we infect again with the same pathogens, there is therefore some protection. The organism remembers the past challenges and responds faster and stronger, explain the experts.

Responses to repeated infections are trained

Although immunological memory has long been considered an exclusive property of acquired immunity, this doctrine has recently been challenged by several research groups, including the laboratory of Prof. Mihai Netea (Nijmegen, The Netherlands), according to the TU Dresden announcement. In particular, certain microbial infections or vaccines trigger an increased white cell response to subsequent infection with the same or even different pathogens.

Precursor cells of the white blood cells are crucial

The research team led by Prof. Chavakis, together with the group of Prof. George Hajishengallis at the University of Pennsylvania in Philadelphia (USA) and Prof. Mihai Netea of ​​the Radboud University in Nijmegen (Netherlands), proved that the progenitor cells of the white blood cells are a species Have memory. Through appropriate "training" a sustained positive reaction of the hematopoietic system can be achieved and the effect could help, for example, to accelerate the formation of white blood cells after chemotherapy, the scientists report.

Impressive long-term effects

The researchers are talking about a trained innate immunity, since white blood cells with appropriate stimuli (such as beta-glucan, which is located in the cell walls of fungi and plants) can be made to respond faster and stronger against future infections. This shows an "impressive long-term effects, up to several months," the scientists report. This is surprising since white blood cells usually only have a relatively short life in the bloodstream.

Continuing positive reaction of the hematopoietic system

Why such a long-term effect can be achieved, the scientists have found in their current study. For the first time, they were able to show that a trained innate immunity acts on the precursors of circulating white blood cells in the bone marrow, which are known as hematopoietic stem and progenitor cells (HSVZ). Such HSVZs can produce many generations of white blood cells, which explains the long-term effects of trained innate immunity, the researchers report. The immune training of HSVZ by beta-glucan leads to a sustained positive reaction of the hematopoietic system.

New approach to side effects of chemotherapy

The effect could also be used to stimulate the formation of white blood cells after chemotherapy, the scientists hope. Because during chemotherapy this process is slowed down. "We think that the principle of trained immunity could be used to prevent such side effects of chemotherapy"; first author Dr. Ioannis Mitroulis from the Institute of Clinical Chemistry and Laboratory Medicine of the University Hospital Dresden "It is also conceivable that this principle can be used therapeutically in blood cancer," adds Prof. Chavakis. (Fp)