One of the most complex human organs is the digestive tract: Here, the body comes into contact with all manner of diet-derived compounds and with countless bacteria. Scientists from the Luxembourg Centre for Systems Biomedicine (LCSB) of the University of Luxembourg in collaboration with colleagues at the Luxembourg Institute of Health and the University of Arizona in the U.S. have now proven that a model of the human gut they have developed and patented.

The “HuMiX” is representative of the actual conditions and processes that occur within our intestines. With HuMiX, the researchers can analyze the complex interactions among human cells and bacteria, predict their effects on health or disease onset and study the action of probiotics and drugs. The researchers publish their findings in the journal Nature Communications (DOI: 10.1038/NCOMMS11535).

In HuMiX, the “Human Microbial Cross-talk” model, human intestinal cells and bacteria can be cultivated together in a small space under representative conditions. The apparatus, no bigger than a beer mat, consists of three chambers. The top chamber is the supply level, from which nutrients continuously flow down to the cell cultures below. Human cells grow on a thin membrane in the middle chamber, while bacteria grow in the lowest chamber. For their tests confirming the validity of HuMiX experiments, the researchers employed pure cultures of various bacterial strains.

Dr. Pranjul Shah, first author of the publication and co-inventor of the HuMiX device, names one example of a metabolic process the LCSB researchers discovered with HuMiX.

“In a co-culture of intestinal cells and a certain strain of the bacterial species Lactobacillus rhamnosus, we determined that production of a messenger of the nervous system, specifically the neurotransmitter gamma-aminobutyric acid or GABA, is stimulated in intestinal cells, indicating a mechanism by which the intestine may be communicating with the brain,” said Shah.

Scientists had already seen evidence of this effect several years earlier in the brain of mice born with a completely sterile gut (which was devoid of all intestinal flora), when their gut was inoculated with similar lactobacillus strains.

“The ability of HuMiX to provide such responses can be attributed to the unique capability of the HuMiX model to allow cultivation of anaerobic bacteria along with human intestinal cells,” said Shah. In their publication, the scientists present evidence that HuMiX is a suitable tool for understanding a range of molecular processes involved in the interaction among human cells and bacteria.

University of Luxembourg
wwwen.uni.lu

Luxembourg Institute of Health
www.lih.lu

University of Arizona
www.arizona.edu