Dormant Bad Gut Bacteria May Be a Key Participant in Leaky Gut and Autoimmune Disorders

In recent years our understanding of the role of gut health and microbiome has increased tremendously. We have learned that it plays an important role in the pathogenesis of multiple health conditions. 

Studies have revealed that gut microbiota strains can adapt and evolve throughout the lifetime of the host, raising the possibility that changes in individual commensal bacteria may affect their propensity to cause inflammatory disease. 

Recently, a group of researchers from Yale University published a study in the journal Nature, in which they have added another piece to the puzzle by showing that some gut bacteria can evolve and become more harmful than helpful. 

Bacterias Able to Evade the Immune System Hidding Within Intestinal Lining

The team found that bacteria can permeate the intestinal walls to invade other organs causing inflammation and other health problems. 

When the gut microbiome becomes unbalanced, causing an increase in bad bacteria, the immune system can be triggered. This can allow bacteria and toxins in the intestines to breach the intestinal walls and enter the bloodstream. This is known as increased intestinal permeability (IP) or leaky gut. 

This increased permeability has been linked to conditions such as inflammatory bowel disease, diabetes, celiac disease, lupus, multiple sclerosis, and even depression. 

For the study, the team evaluated whether gut bacteria that changed while within the body had a higher IP rate, possibly causing chronic inflammation. 

The researchers used a mouse model to test the bacteria Enterococcus gallinarum, which has been linked to diseases such as urinary tract infections and endocarditis. They found that the bacteria acquired small DNA mutations over time allowing them to live inside the intestinal wall lining, and eventually escape the gut.

They also discovered that the bacteria remain hidden from the immune system for a while and once found caused an inflammatory response outside the gut, in organs such as the liver and lymph nodes. 


Corrie Pelc. (2022, Jul 20). Leaky gut and autoimmune disorders: Dormant ‘bad’ gut bacteria may be key. Medical News Today. Retrieved from:

Yang, Y., Nguyen, M., Khetrapal, V. et al. Within-host evolution of a gut pathobiont facilitates liver translocation. Nature 607, 563–570 (2022). 

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