how brain detects, regulates inflammation: Study

A circuit important in sensing and also in the regulation of the anti-inflammatory response organized by many brain regions has been identified by a multidisciplinary team of researchers from the Institut Pasteur, CNRS, and Inserm. This circuit coordinates and controls the immune response while detecting inflammation in the blood. It represents a two-way communication between the immune system and brain.

The findings of the study were published on June 5, 2023 in the journal Neuron.

The immune system is activated whenever an infection or injury occurs in order to combat the infection and restore any tissue damage. Pro-inflammatory mediators are released during this process, which allows the brain to be informed of the body's immunological condition and to coordinate the immune response. This signal causes the brain to launch a complicated process known as "sickness behavior" that reassigns energy to the body's many systems. This condition is characterized by behavioral modifications, such as social withdrawal and lethargy, metabolic changes, such as fever and hunger loss, and the release of hormones like cortisone, which boost infection resistance while simultaneously controlling immunological responses. Researchers from the Institut Pasteur, Inserm, and CNRS who specialize in neurobiology and immunology made a discovery in this study.

The scientists used state-of-the-art neuroscience approaches to identify this circuit, which enabled them to individually observe the neurons involved during inflammation. The experts observed how the activity of specific neurons in the parabrachial nucleus could regulate the production of white blood cells involved in the immune response. "This research demonstrates that neural activity in the brain alone can have a powerful effect on the development of immune responses during infection or injury. It therefore provides a clear example of the powerful two-way connection between the body and brain. It also fuels our ambition to discover the impact of our brain on the way we interact with microbes, fight off pathogens and heal wounds," explains Gérard Eberl, Head of the Institut Pasteur's Microenvironment and Immunity Unit.

The discovery of this circuit opens up new opportunities for research that will jointly contribute to the fields of neurobiology and immunology: "This study gives us additional tools to better understand the impact of systemic inflammation on our brain, mood and on certain neurodegenerative processes," added Gabriel Lepousez, a neurobiologist in the Perception and Memory Unit.