Newly discovered gut organism protects mice from bacterial infections

[adreno]

While bacteria are often stars of the gut microbiome, emerging research depicts a more complex picture, where microorganisms from different kingdoms of life are actively working together or fighting against one another. In a study published October 6 in Cell, scientists reveal one example: a newly discovered protist that protects its host mice from intestinal bacterial infections.


"This was a serendipitous finding, but an important one," says senior author Miriam Merad, a Professor of Oncological Sciences and of Medicine at the Icahn School of Medicine at Mount Sinai. "This study shows how vital it is to go beyond bacteria when studying the microbiome."

http://medicalxpress.com/news/2016-10-newly-gut-mice-bacterial-infections.html

 

[natasa778]

This, or rather its absence, could be why synthetic poo trials are not working as expected/hoped. Still very early days but the effects so far are apparently not nearly as exciting as the real mccoy fecal transplants.

 

[alicec]

How exciting that we now have the tools to fully explore the gut microbiome and its host interactions.

The study reminds me of the people suffering from inflammatory bowel disease who deliberately infected themselves with hookworm in a desperate attempt to relieve the distressing symptoms. It seemed to work.

The parasites managed to control the out of control inflammatory response when nothing else could.

And what of current thinking that D. fragilis (the mouse prolist is an ortholog of this organism) in the gut needs to be wiped out with antibiotics?

 

[adreno]

This, or rather its absence, could be why synthetic poo trials are not working as expected/hoped.

My thoughts exactly. It is also another reminder of how much we need Lipkins research. It could well be found that certain protists are missing in PWME.

 

[adreno]

How exciting that we now have the tools to fully explore the gut microbiome and its host interactions

The tools are there. Now if we could only get the funding...

 

[adreno]

The abstract from the study. It seems there is a downside to this enhanced immunity:

• •A murine commensal protist named T.mu modulates colonic mucosal immunity
• •T.mu reprograms colonic immunity via IRF8- and IRF4-dependent dendritic cells
• •T.mu-driven IL-18 protects against enteric bacteria but promotes CRC progression
• •A T.mu-related protist is highly prevalent in the stools of healthy individuals

Summary
While conventional pathogenic protists have been extensively studied, there is an underappreciated constitutive protist microbiota that is an integral part of the vertebrate microbiome. The impact of these species on the host and their potential contributions to mucosal immune homeostasis remain poorly studied. Here, we show that the protozoan Tritrichomonas musculisactivates the host epithelial inflammasome to induce IL-18 release. Epithelial-derived IL-18 promotes dendritic cell-driven Th1 and Th17 immunity and confers dramatic protection from mucosal bacterial infections. Along with its role as a “protistic” antibiotic, colonization withT. musculis exacerbates the development of T-cell-driven colitis and sporadic colorectal tumors. Our findings demonstrate a novel mutualistic host-protozoan interaction that increases mucosal host defenses at the cost of an increased risk of inflammatory disease.

http://dx.doi.org/10.1016/j.cell.2016.08.076

 

[alicec]

It seems there is a downside to this enhanced immunity:

Yes, as Martin Blaser has pointed out in his studies of the protective role of Helicobacter pylori, this ancient organism which we in the west are losing from the gut (not to mention actively killing off with antibiotics any time it is detected) appears to have protected us from things like asthma and allergies.

The price that a few have paid is increased susceptibility to ulcers and stomach cancer, though this may apply to only a few strains of the organism.