Special Bacteria May Curb Bowel Diseases
Genetically Engineered Bacteria and Drink Reduce Colitis in Early Lab Tests; Human Studies Next
WebMD News Archive
Aug. 21, 2009 -- Researchers in England may have found a new way to treat
colitis and other inflammatory bowel diseases.
Those scientists took a bacterium called Bacteroides ovatus, which
people naturally have in their gut, and genetically altered it to secrete a
protein called KGF-2 when exposed to a sugar called xylan.
The point is to bump up the presence of KGF-2, which is a human growth
factor that could help heal damage done by inflammatory bowel diseases.
Why not just give human growth factors directly? Because "they are unstable
when administered orally and systemic administration requires high doses,
increasing the risk of unwanted side effects," the researchers write in the
online edition of the journal Gut.
Their study focused on mice with colitis, a type of inflammatory bowel
disease. The scientists gave the genetically engineered bacteria orally to
some of the mice every other day, and also laced the drinking water of some of
the mice with xylan. For comparison, other mice didn't get the bacteria and/or
the xylan drink.
Compared to the other mice, the mice treated with bacteria and xylan had a
reduction in rectal bleeding, inflammation, and weight loss; they also had
faster healing of colitis-damaged tissue and an improvement in their stool
Tests need to be done in people, and one of the researchers, Simon Carding,
PhD, discussed the treatment with WebMD via email. Carding is a professor
of mucosal immunology at England's University of East Anglia Medical
School and the director of integrated biology of the gastrointestinal
tract research program at the Institute of Food Research in Norwich,
Carding writes that the bacteria used "are present in the gut of everyone,
so patients will be taking something that they already have and the treatment
should be well tolerated. The outstanding questions concern formulation and
dosing protocols, which we plan to address as part of our phase of
It might be possible to do a short, one-time bacteria dosing regimen that
would establish a permanent colony of the genetically engineered bacteria.
Another option would be to establish a temporary colony, repeating those
treatments when the disease flares up.
Carding says natural sources of xylan -- tree bark, rice husks, and oat
kernels -- aren't commonly found in the diet, so patients would need to
supplement their diets with xylan, such as in a drink.
"Animals tolerate high concentrations of xylan [in] their drinking water
very well and have never exhibited any adverse signs from excessive xylan
consumption," Carding writes.
Carding notes that the bacteria strategy could be used to treat various gut
diseases, including delivering agents to interfere with the formation of new
blood vessels that feed intestinal tumors and delivering vaccine antigens to
build the gut's immunity against viruses, bad bacteria, and infection.