Newly identified gut cells nurture lymph capillaries
Understanding the mechanisms that impair lymphatics growth and fat
digestion in the small intestine

Date:
August 14, 2020
Source:
Institute for Basic Science
Summary:
IBS research team has identified new subsets of gut connective
cells, which are crucial for lymphatic growth.The findings imply
a crucial link between the physiology of intestinal environment
and biological interactions between cell types.



FULL STORY ==========================================================================
You have just enjoyed a delicious summer BBQ. After approximately eight
hours, food molecules reach your small intestine, where specialized
lymph capillaries, called lacteals, absorb fat nutrients. Lacteals are different from other lymphatics, as they continue to regenerate during adulthood, with a slow, but steady pace. Their unique renewal capacity
is still poorly understood.


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A team of scientists led by KOH Gou Young at the Center for Vascular
Research, within the Institute for Basic Science (IBS, South Korea) have identified new subsets of gut connective cells, which are crucial for
lymphatic growth. Their new findings have been reported in the journal
Nature Communications.

The walls of the small intestine are covered with fingerlike projections, called villi. Lining these villi, heterogeneous populations of epithelial, immune, vascular, connective and even neural cells co-exist and help the digestive process. Lacteals and blood capillaries run inside the villi
and take in different food molecules. The gut environment needs to cope
with water secretion and reabsorption (osmotic stress), as well as the repetitive muscular activity that moves food through the intestine. How
all these complex mechanisms are harmonized is still a mystery.

The research team was able to place a new piece towards completing this mysterious puzzle. The researchers found that the regulatory proteins
YAP/TAZ in villi's connective cells, the intestinal stromal cells,
play a role in the growth of nearby lacteals. In mice with an abnormal hyperactivation of YAP/TAZ, the team observed atypical sprouting of
lacteals and impaired dietary fat uptake.

"The lacteals in these mice looked like tridents, which is very
intriguing, since we did not manipulate the lacteals themselves, but
the surrounding cells," says HONG Seon Pyo, first co-author of this study.

The researchers took a step further and discovered that intestinal
stromal cells belong to several subtypes, with distinct gene expression
and localizations within the villi. Among these subsets, three newly
identified populations secrete VEGF-C -- an essential molecule for
lymphatic growth - - upon YAP/TAZ activation. YANG Myung Jin, first
co-author of this study, explains, "We were very surprised to see such heterogeneity in a cell population that was considered homogeneous."
Lastly, researchers showed that mechanical force and osmotic stress
regulate YAP/TAZ activity in stromal cells. In summary, mechanical
stimulation activates YAP/TAZ in the intestinal stromal cells, which in
turn release VEGF-C and can account for lacteal growth. CHO Hyunsoo, first co-author of this study notes, "This result implies a crucial link between
the physiology of intestinal environment and biological interactions
between cell types." "We are interested in investigating how each newly identified cell type works in healthy and diseased conditions," adds Koh.


========================================================================== Story Source: Materials provided by Institute_for_Basic_Science. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Seon Pyo Hong, Myung Jin Yang, Hyunsoo Cho, Intae Park, Hosung Bae,
Kibaek Choe, Sang Heon Suh, Ralf H. Adams, Kari Alitalo, Daesik
Lim, Gou Young Koh. Distinct fibroblast subsets regulate lacteal
integrity through YAP/TAZ-induced VEGF-C in intestinal villi. Nature
Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-17886-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200814101701.htm

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