We know that much of the immune system lives in the gut, along with the trillions of gut bacteria called the gut microbiome. But how do the two interact? This new study explores that question!
It’s known that gut dysbiosis, or an imbalance of the gut microbiota, is one of the factors involved in autoimmunity.
Researchers at Harvard Medical School, led by Professor Dennis Kasper have found an immuno-modulatory effect between specific gut bacteria and host immune cells and genetics.
In the past, research has looked at associations between disease and the presence or absence of certain classes of bacteria in the gut. By contrast, these researchers studied one microbe at a time and its effects on nearly all immune cells and intestinal genes.
This is a new approach.
Looking at Specific Single Bacteria and Effects on Immune Cells and Genes
This particular approach lends a more precise understanding of the reciprocity between individual gut microbes and their hosts.
In this research published February 16, in Cell, the researchers studied 53 individual bacterial species, representing all five of the major phyla. They inoculated sterile mice, with one kind of microbe at a time. The researchers then observed the effect these individual microbes had on the composition and activation of 21 types of immune cells and on intestinal tissue. They compared these results with those of mice who were completely germ-free.
The researchers found that the microbes had several different effects on immune cells:
1- No effect on immune cells (very few)
2- Oppositional or balancing effects
3- Powerful effect on immune cells
Certain strains of bacteria boosted the activity of certain cells, while others suppressed the activity of those very same cells. These neutralizing effects suggest an evolutionary checks-and-balances mechanism to ensure that no single bacterium can overpower the others in its effects on the immune system.
We have come to understand that more diversity is better because of this fluctuating mechanism – where some species balance others.
Interestingly, they also found that bacterial effects on genes that regulate the activity of cytokines (signaling molecules responsible for inducing inflammation) they also observed the same – some bacteria turned up the activity of these genes while others turned it down.
The researchers stated,
These oppositional effects suggest an evolutionary checks-and-balances mechanism to ensure that no single bacterium can over-power the others in its effects on the immune system. Similarly, some bacteria upregulated certain genes, while others downregulated them, indicating that microbes can have balancing effects on intestinal gene expression. (source)
This gives us more information on microbial influencers of the immune system and can lead to very specific targeted treatments for disease.
The researchers are Dennis Kasper, professor of medicine and microbiology and immunobiology at HMS and his team and the immunologists from the HMS lab run by Diane Mathis and Christophe Benoist.
We set out to map out interactions between bacteria and the immune system in the hope that this could eventually lead to the development of an apothecary of agents tailored to modulate the immune system selectively and precisely. (source)
Its a nice combination of experts!
Christophe Benoist said,
Because we observed microbial effects mainly in the gut, we believe that a microbe-based therapy would avoid the collateral damage seen with drugs that wipe out classes of immune cells across the body.
Perfect! I can’t wait to see more therapies geared towards modulating the immune system rather than trying to suppress it or wipe it out. This can be a giant step forward for therapies for autoimmunity!
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