The human gut is full of microbes. Indifferently whether they are beneficial or not, they must be prevented from expanding to the rest of the body and causing any problem. Recently, researchers at the Department of Experimental Oncology in the European Institute of Oncology, Milan, Italy, have found a barrier present between the intestine and the blood vessels. This barrier determines the the particles that can pass through in a size-dependent manner. Still, it has been found that Salmonella can disable the barrier´s function, allowing bacteria to pass through.
The intestine is covered by epithelial cells very tightly packed that secrete antimicrobial proteins; that are covered by mucus, which places away the bacteria from the epithelial cells. The epithelial cells also absorb the food molecules and let them pass, to finally reach the liver.
The researchers realized that when bacteria were able to cross this epithelial membrane, they didn’t reach the liver but rather the close lymph nodes, making them question if there was something more than just this epithelial membrane. To investigate this further, they looked for similarities between this barrier and that of the brain. The endothelial cells between the brain and the blood have strong connections, that are essential for the function of the barrier. For example, they describe how intestine cells also have tight junctions like those of the blood brain barrier, and instead of astrocytes they possessed enteric glia cells, which have very similar functions to astrocytes.
The researcher found out that certain bacteria such as Salmonella would be able to cross this gut barrier and infect places such as the liver. Maria Rescigno and her team found out that Salmonella was able to disable the Wnt/ß-catenin signaling pathway in the enteric barrier. They also found out, that if they over expressed ß-catenin in the endothelial cells, Salmonella was not able to cross this gut barrier.
This research is very important since Salmonella infections are acute, and some of them are invasive. Invasive Salmonella treatments could be done to improve this barrier and prevent the bacteria from expanding further into the body.
Lourdes Amieva y Erica Paniagua. Microbiology Group 03. Students of the 2º year of Biotechnology degree.
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