Microbiota, discovered the role of the “gate” protecting the brain from intestinal inflammation

The study, by Humanitas researchers, provides a first-ever description of a new brain vascular barrier: it closes to protect the brain from intestinal inflammation, this generates anxiety-like states. A revolution in the understanding of how gut and brain communicate that opens the way to new therapeutic strategies.

Depression and anxiety are common amongst those who suffer from chronic intestinal diseases, such as ulcerative colitis and Crohn’s disease. A link between the gut and the brain has long been proposed but the players have never been described. A team of researchers from Humanitas, headed by Prof. Maria Rescigno    Head of the Laboratory of Mucosal Immunology and Microbiota at Humanitas Research Hospital and professor of General Pathology at Humanitas University, has published in Science the results of a study that open new scenarios in the knowledge of how the choroid plexus, a barrier (or interface) between the bloodstream and the brain, works.

The study is also signed by Dr. Sara Carloni    microbiologist at Humanitas University, Prof. Michela Matteoli    Professor of Pharmacology at Humanitas University and Director of the CNR Institute of Neuroscience, and Dr. Simona Lodato    Head of the Humanitas Neurodevelopment Laboratory and Professor of Histology and Embryology at Humanitas University.

“We have documented the mechanism that blocks inflammatory signals originating in the gut from entering the brain and propagating inflammation. This phenomenon is associated with an isolation of the brain from the rest of the body, which is responsible for behavioural changes, such as anxiety, and defects in episodic memory” explains Prof. Maria Rescigno, “which means that such conditions of the central nervous system are part of the disease.

The choroid plexus is a structure that normally allows nutrients and immune cells to enter the brain and produces the cerebrospinal fluid. This role as a vascular membrane, able to open and close like a ‘gate’ depending on the surrounding scenario, was unknown. The study shows that such a ‘gate’ closes when faced with the danger of acute intestinal inflammation to prevent the spreading of inflammation to the brain,’ describes Dr. Sara Carloni, ‘resulting in the development of anxiety and depression’.

“Discovering that a vascular barrier in the choroid plexus can reorganise itself and close to block entry of toxic substances, is of enormous interest especially during development of the brain,” specifies Dr. Simona Lodato. “We now have evidence that intestinal-brain communication is the basis of proper brain activity and this opens up important questions for many other pathologies, primarily neurodegenerative ones,’ concludes Prof. Michela Matteoli.

The researchers came to this discovery by studying the vascular, intestinal and cerebral membranes from an immunological and inflammatory perspective.