The gut’s microbiome has an impact on the brain’s immune response throughout life, with a possible effect on the course of diseases affecting the brain. Researchers at the University Medical Center Freiburg have uncovered these effects in mice.
The function of brain macrophages is controlled by metabolites of gut bacteria, called short-chain fatty acids. Mice without gut bacteria developed stunted microglia. This study highlights the importance of a balanced diet for the prevention of brain diseases and indicates that there may be a link between gut bacteria and the genesis of neurodegenerative diseases. These findings will be published in the renowned journal Nature Neuroscience.
Microglia are also known as phagocytes of the brain, or brain macrophages. They eliminate invading pathogens and dead brain cells, thus contributing to the brain’s life-long plasticity. Malfunctioning microglia cells play a role in a number of brain diseases. Until now, the maturing and activation of these cells has been unclear.
Without gut bacteria, the brain’s immune cells become stunted
Prof. Dr Marco Prinz, Medical Director at the Institute of Neuropathology at the University Medical Center Freiburg and associated member of the BIOSS Centre for Biological Signalling Studies Freiburg, heads the research group consisting of members from Freiburg, Rehovot (Israel), Munich, Mainz, Cologne and Berne (Switzerland).
Together with the lead authors, Dr Daniel Erny and Anna Lena Hrabě de Angelis he has been able to demonstrate – using different mouse models – that a functioning immune system of the brain depends on healthy gut bacteria. The researchers examined animals that had been raised and kept in a completely sterile environment. The animals’ microglia were stunted and immature, and hardly responded to the brain’s inflammatory signals. “Our results indicate a constant flow of information between gut bacteria and brain macrophages,” so Prof. Prinz.
Animals whose intestinal bacteria had been eliminated by a four-week course of antibiotics also showed an impaired immune response. When put into contact with animals harbouring a normal gut flora, the previously sterile animals quickly developed their own intestinal flora, which had a positive effect on their immune response. According to the neuropathologist, the general outcome was that “the more diverse the gut bacteria, the better developed were the microglia.”
Fermented fibre controls the brain’s immune response
The researchers showed that short-chain fatty acids function as signal between the intestinal flora and the microglia in the brain. Short-chain fatty acids are a product of the bacterial fermentation of fibres, dairy products and other foods. They can travel to the brain via the bloodstream, where they help microglia cells to quickly and efficiently fight any inflammatory reactions. “Our findings show just how important a balanced diet, contributing to bacterial production of short-chained fatty acids, is for mental health,” says Prof. Prinz.
Does intestinal flora also have an effect on Alzheimer’s, Parkinson’s and multiple sclerosis?
The study may well be very relevant for humans. “Our study results are in line with previous clinical studies and investigations by other research groups,” explains Prof. Prinz. Autoimmune disorders of the intestines, such as Crohn’s disease, have been linked with a lack of short-chained fatty acids. There have been investigations into treatment by stool transplantation, meaning that the intestinal flora is transferred from one person to another. How strong the effect of the gut microbiome on the functioning and development of the human brain actually is, remains to be investigated.
Prof. Dr med. Marco Prinz
Institute of Neuropathology
University Medical Center Freiburg
Telephone: +49 (0)761 270-51060
Publication title: Host microbiota constantly control maturation and function of microglia in the CNS
http://www.uniklinik-freiburg.de/neuropathology.html Institute of Neuropathology
http://www.uniklinik-freiburg.de/nc/presse/pressemitteilungen/detailansicht/pres... Press release: Freiburg Neuropathologist receives renowned Award for research on multiple sclerosis (German)
http://www.bioss.uni-freiburg.de BIOSS Centre for Biological Signalling Studies
Benjamin Waschow | idw - Informationsdienst Wissenschaft
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
Colorectal cancer risk factors decrypted
16.07.2018 | Max-Planck-Institut für Stoffwechselforschung
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science