We carry large quantities of intestinal
bacteria with us. Deficiency in a certain protein in the gastrointestinal tract has
been shown to lead to both inflammation and abdominal fat accumulation
in mice. The discovery provides yet another piece of the puzzle of how
humans are affected - or not - by the intestinal
In the study from Sahlgrenska Academy, researchers have addressed
the key role of the bacteria-binding protein ZG16 in protecting the body
from intestinal bacteria.
‘The protein ZG16 binds and clumps bacteria together and thus works with the protective mucus layer in the intestine to keep bacteria at a safe distance from the intestinal mucosa.’
"The hope is that eventually, we'll be able to administer this
protein to improve protection against bacteria in patients with a
defective barrier," says Joakim Bergström, postdoctoral researcher at
Joakim Bergström is in Professor Gunnar C. Hansson's research group,
which, eight years ago, was first to discover that there is a
protective mucus layer in the intestine that separates intestinal
bacteria from the intestinal surface.
Clumping bacteria together
The thick mucus layer prevents the large quantities of bacteria
people typically have in the gastrointestinal tract, one to two kilos,
from reaching the body's tissues and causing inflammation or other harm.
Structurally, this protective barrier is made of proteins (mucins)
that are formed and secreted by the goblet cells of the gastrointestinal
The discovery has led to a brand new area of research and has been
followed by numerous findings about how the mucus layer is created, is
maintained, moves, and is damaged.
The new research shows that the protein ZG16 binds and clumps
bacteria together and thus works with the protective mucus layer in the
intestine to keep bacteria at a safe distance from the intestinal
Mice that lack the protein develop a mucus layer that is more
permeable to bacteria, allowing more bacteria to cross the intestinal
mucosa into the body. The increased quantity of bacteria that reach the
body's various tissues cause low-grade inflammation.
The bacteria that slip through from the intestine also led to
increased abdominal fat accumulation in the mice that had a defective
mucus barrier due to the lack of the protein.
The research group has previously shown that the mucus layer is
permeable to bacteria in patients with the gastrointestinal disorder
ulcerative colitis and in mouse models of inflammatory bowel disease.
The finding of a specific protein that helps prevent bacteria from
entering the body is important for the understanding of inflammatory
bowel diseases and of the origins of more general diseases such as
obesity and inflammation.
"It's becoming very clear now that a significant amount of bacteria
leaks through the intestine into the body, which plays a role in
inflammatory diseases, and even obesity, at least in mice. This
indicates a principle that is probably quite universally applicable,"
says Gunnar C. Hansson.