Does PNAS stress really protect your body?

Inflammatory bowel disease (IBD) symptoms have been reported to worsen
under conditions of psychological stress.
Similarly, more severe inflammation is associated with the third lymphatic organs of the intestine (TLOs), which are immune cells
produced in response to chronic inflammation or injury.
Although the role of TLO and stress in IBD is controversial, the formation of TLO in stress settings has not been explored
.
In this study, a mouse model with Crohn's disease-like ileitis showed a significantly increased immune response
to TLO formation in the colon after 56 days of stress.
However, the pressure did not seriously worsen inflammation
of the small or large intestine.
The composition of the microbiome of stressed mice is the same
as that of control mice.
However, due to inherent flaws in microbiome assessment methods, the researchers opted for fecal microbiome transplantation
.
While mice given the stressed mouse microbiome exhibited the same behavioral characteristics as donors, transplantation did not promote TLO formation
.
Instead, stress was found to increase the production
of the cytokines IL-23 and IL-22.
These two cytokines are part of the
TLO formation pathway.
IL-22 plays a protective role in wound healing and tissue regeneration and has anti-inflammatory and pro-inflammatory responses
.
Stressed mice lacking IL-23 receptors had increased IL-23, but IL-22 did not increase and could not increase TLO formation
.
When IL-22 was used, this effect was reversed
.

Given TLOs' association with other diseases, the researchers reasoned that stressed mice were more susceptible to a "secondary shock"
from the colon.
However, stressed mice actually exhibited less severe inflammation
after a "second impact" than mice without stress.

"Our findings suggest that psychological stress induces the formation of TLOs by increasing the production of IL-23," Cominelli said
.
"In addition, stressed mice were protected after the 'second impact,' suggesting that TLOs may have the function of
improving the mucosal barrier.
"

Often, stress is associated with
more severe inflammation.
However, not all patients who experience stress are more severely
ill.
So the study has translational implications because it demonstrates a situation where stress has beneficial effects, the scientists said
.

"We found that chronic daily stress lasting six weeks helped prevent secondary injury
.
The stressed mouse model was actually protected," Cominelli said
.
"We found that they stimulate the immune system, which prevents inflammation
in the gut.
What needs to be studied is whether this translates into other diseases and injuries
.
So do I want to be stressed? It all depends on the definition of
stress.
It's better
to use the word 'stimulus'.
The message is that in your life, a little stress is good, but you want to feel it
in the right way.
”

Reference: Chronic stress induces colonic tertiary lymphoid organ formation and protection against secondary injury through IL-23/IL-22 signaling