Worm and Microbe Infection Research
Micro-organisms in the intestine live in symbiosis with humans but can cause illness or even death.
Together with an international team, Nicola Harris, Professor at the Institute of Integrative Biology of ETH Zurich, and specialist in the area of intestinal diseases caused by microbes, researched the factors that make a person immune to worm infections. The knowledge can now be used to develop vaccines.
The intestinal mucosa forms the largest surface area of the human body. Unfolded, it would occupy approximately the area of a tennis court. It represents an interface between the body and the environment, and is therefore vulnerable to pathogens and worm infections.
Harris explains that "As a result of the flimsy barrier between the intestine and the environment, the intestinal mucosa is constantly exposed to foreign substances and must be able to trigger a robust immune response to them."
At the same time, the mucosa must recognise whether harmless so-called commensal germs are involved, which live in symbiosis with humans, or dangerous or even lethal pathogens.
Harris adds, "The intestinal mucosa's immune system is therefore faced with an enormous challenge. It must constantly decide when it must mount a counter-attack against an inflammation that keeps the pathogenic germs in check by means of an activated defence response or when it needs to maintain the status quo in which humans and "useful" probiotic bacteria live in symbiosis." She says that the commonest intestinal microbes in mammalian evolution are symbiotic bacteria and worm infections.
This is why Harris and her team research the different aspects of the immune defence in the intestine to understand the interaction between humans, commensal bacteria and worm infections.
Researchers at McGill University, Canada, have discovered DNA variations in a gene that increases susceptibility to developing Crohn's Disease.
Their study was published in the January issue of the Journal Nature Genetics.
The researchers pinpointed DNA sequence variants in a gene region called NLRP3 that are associated with increased susceptibility to Crohn's Disease.
"Although the exact cause of Crohn's disease is still unknown, both environmental and genetic factors are known to play a critical role in the pathogenesis of the disease," Dr. Franchimont said.
The 400 square metres of the intestinal absorptive area is the largest single surface in or on the human body, and it is covered by billions of bacteria of the intestinal microflora living in the gastrointestinal tract.
"The single layer of cells lining your intestinal digestive tract is thus constantly exposed to high levels of bacteria and pathogens," lead reseracher, Alexandra-Chloé Villani explained.
"These cells must recognize and respond appropriately to the harmful bacteria while maintaining tolerance to the non-pathogenic 'good' (probiotic) bacteria that make up your intestinal microbial flora. This is the central challenge of the digestive immune system, which needs to balance defence versus tolerance."
"The protein encoded by the Crohn's Disease susceptibility gene NLRP3, Cryopyrin, is an intracellular bacteria sensor that plays a key role in initiating immune response," explained Villani.
Based on their results, researchers theorize the bacterial sensor Cryopyrin is probably defective in some patients, and doesn't correctly recognize the presence of harmful bacteria...Read more...
