Our intestinal flora affects the brain. If it is damaged, it can cause diseases such as strokes. Dr. Vikramjeet Singh, a neuroscientist at the University of Duisburg-Essen (German acronym: DUE), is investigating how the interaction of intestinal bacteria and immune cells influences a brain infarction. He is particularly interested in the diversity of microbes in the intestine and neutrophils, which are responsible for the initial defense against pathogens.
Most strokes are ischemic. This means that the brain is not sufficiently supplied with blood and oxygen by a blocked artery; brain cells die. It has been known for some years that the intestinal flora is not fully disconnected from the extent and course of the stroke. Since 2018, Dr. Vikramjeet Singhhe has been researching this issue at the DUE’s Center of Medical Biotechnology (German acronym: ZMB) and at the Institute for Experimental Immunology and Imaging at the University’s Medicine Faculty and University Hospital.
Dr. Singh was one of the first to discover that a stroke triggers an inflammatory reaction in the brain and also throws the intestinal flora out of balance. The latter in turn has considerable consequences for the injured brain tissue.
In healthy people, the intestinal flora consists of about 1,000 different types of bacteria, which regulate the immune system. "If, however, the diversity is significantly lower or the intestine is overpopulated with bacteroidetes, a metabolic bacterium, this activates special defence cells: the neutrophils. These are the most common white blood cells, belong to the innate immune system and fight pathogens," explained Dr. Singh: "After a stroke, neutrophils are the first to reach the injured brain. They produce proteins and enzymes to repair the damaged tissue - and yet they destroy more".
At present, it is not yet fully understood what molecular signals activate neutrophils. There is also a lack of therapies to prevent the immune cells from damaging brain tissue and brain function after a stroke.