Amazing stuff!
"The human immune system is incredibly versatile. Among its most skilled multitaskers are T cells, known for their role in everything from fighting infection to reining in inflammation to killing nascent tumors.
Now, in a surprising new discovery, ... researchers have found that a class of regulatory T cells (Tregs) made in the gut play a role in repairing injured muscles and mending damaged livers.
In an even more unexpected twist, the researchers found that gut microbes fuel the production of Tregs, which act as immune healers that go on patrol around the body and respond to distress signals from distant sites of injury.
The results ... add to a growing body of evidence showing how important the gut microbiota is in regulating various physiologic functions beyond the gut. Additionally, the findings show that gut immune cells may have a far broader repertoire in taming inflammation and healing damage that extends beyond the intestines. ...
So, when during a routine cataloging of various immune cells in different organs they came across gut Tregs intermingled with muscle cells, the researchers were baffled. These colonic Tregs had been rarely found outside of the small and large intestines. ..."
From the highlights and abstract:
"Highlights
• Muscle injury induces local accumulation of RORγ+ Treg cells emanating from the gut
• The microbiota regulates muscle repair via RORγ+ Treg cells
• Muscle RORγ+ Treg cells shield differentiating muscle stem cells from IL-17A
• RORγ+ Treg cell emissaries play a general role in the homeostasis of extra-gut tissues
Summary
Specific microbial signals induce the differentiation of a distinct pool of RORγ+ regulatory T (Treg) cells crucial for intestinal homeostasis. We discovered highly analogous populations of microbiota-dependent Treg cells that promoted tissue regeneration at extra-gut sites, notably acutely injured skeletal muscle and fatty liver. Inflammatory meditators elicited by tissue damage combined with MHC-class-II-dependent T cell activation to drive the accumulation of gut-derived RORγ+ Treg cells in injured muscle, wherein they regulated the dynamics and tenor of early inflammation and helped balance the proliferation vs. differentiation of local stem cells. Reining in IL-17A-producing T cells was a major mechanism underlying the rheostatic functions of RORγ+ Treg cells in compromised tissues. Our findings highlight the importance of gut-trained Treg cell emissaries in controlling the response to sterile injury of non-mucosal tissues."
The gut microbiota promotes distal tissue regeneration via RORγ+ regulatory T cell emissaries (no public access)
Graphical abstract
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