Crohn’s disease is a severe inflammatory bowel disease that is highly spread in developed countries. Amongst its possible causes are genetic predisposition, environment and patients’ lifestyle. The disease is associated with a compromised reaction of the immune system to a person's own gut microbes, as well as an imbalance in gut microbiota. In order to study its development and find the methods of effective diagnostics and treatment, scientists research the role of bacteria in the pathologic process.
Among the most promising approaches is metagenomic analysis of genetic material. A research team composed of scientists from ITMO University and specialists from the Federal Research and Clinical Center of Physical-chemical Medicine in collaboration with doctors from several medical centers have recently studied the gut metagenome of patients with Crohn’s disease. It turned out that the composition of microbiota in such patients is significantly different compared to that of healthy people: as the fraction of normal flora decreases, pathogenic species that almost never exist in humans begin to dominate.
Though these changes differed from patient to patient, all patients showed a several times increase in the number of Escherichia coli. The scientists decided to study the genetic differences between Escherichia coli that develop in patients with Crohn’s disease and regular Escherichia coli that exist in healthy people. The comparison conducted using the Russian population showed no common differences. This was also confirmed by the previously published data on healthy people and patients with Crohn’s disease from other countries.
"Escherichia coli is considered among the most well-studied gut microbes and was also one of the first to be discovered. Its amount increases in people suffering from a particular set of diseases. The metagenomic analysis showed that the genetics of Escherichia coli of patients with Crohn’s disease can be quite different, while many researchers believed that there exist only specific varieties. This supports the concept that Crohn’s disease is a syndrome, i.e., a disease in which similar manifestations in multiple cases are caused by different factors in each case,” comments Alexander Tyakht, a research associate at ITMO University.
The research indicated that several strains of Escherichia coli can coexist in a human's bowel. As strains with different genome can occupy significantly different ecological niches, the same treatment schemes can have a different effect on them. This discovery offers an opportunity to better balance gut microbiota in patients with Crohn’s disease, while individual analysis of the bacteria genotype offers an opportunity to choose appropriate medications, probiotics and even microbiota donors for every patient.
These findings also correspond with the scientists' earlier research that involved genome analysis of particular E. coli strains. The new results help study how microbiota changes in patients with Crohn’s disease, and which species and strains of bacteria take part in its development. This, in turn, can help better understand the causes and progress of the disease, as well as choose more efficient treatment methods.
Reference: Genetic diversity of Escherichia coli in gut microbiota of patients with Crohn’s disease discovered using metagenomic and genomic analyses. A. Tyakht et al. BMC Genomics. 27 December, 2018.
