According to a study published in the journal Cell Reports, any change in a single gene allows dangerous gut bacteria to trigger the inflammation that underlies the progression of Crohn’s disease. The researchers from Weill Cornell Medicine and New York-Presbyterian showed that the gene AGR2 was linked to Crohn’s disease.

The specific host gene, AGR2, encodes a component of the cell’s machinery that aids in the formation of new proteins so that the cell can ward off "bad" bacteria. However, when the cell is stressed due to the disruption in the process caused by microorganisms or inflammation, it can result in extreme situations. Gene expression can be either overactive or completely silent in extreme cases.

The authors of the study revealed that Crohn’s is caused by a concoction of elements, including genetic vulnerability and the presence of specific microorganisms. They linked the inflammation in the gut lining to microbes known as adherent-invasive Escherichia coli (AIEC). The researchers discovered that changes in AGR2 activity levels and increases in the class of bacteria to which AIEC belonged reinforced the disease in Crohns disease patients.

(Source: https://theprint.in/health/researchers-find-how-pathogenic-bacteria-trigger-crohns-disease/1248517/ )