Alenghat and her colleagues looked at HDAC3 expression in normal and diseased intestine from both humans and mice, finding that the enzyme is normally expressed throughout the intestinal epithelium, but that expression is reduced in tissues from subjects with inflammatory bowel disease.
The team then developed a mouse model that would mimic that observation. They created transgenic mice that lacked HDAC3 specifically in the intestinal epithelium and found that these animals exhibited altered gene expression in their intestinal epithelial cells.
The mice also showed signs of altered intestinal health. They lacked certain cells, called Paneth cells, that produce antimicrobial peptides. The mouse intestines seemed to be more porous than normal, and they showed signs of chronic intestinal inflammation, exhibiting some of the symptoms observed in patients with IBD.
When the team examined the diversity of the microbial population colonizing the mutant animal intestines, they found they were different from normal animals, with some species being overrepresented in HDAC3-deficient mice. "There's a fundamental change in the relationship between commensal bacteria and their mammalian hosts following deletion of HDAC3 in the intestine," Artis explains.
But, if the mutant animals were grown in the absence of bacteria, their intestinal symptoms largely disappeared, as did many of the observed differences in gene expression. In other words, HDAC3 was influencing the bacterial population, and the bacteria in turn were influencing the cells' behavior.
The implication, Artis says, "is that intestinal expression of HDAC3 is an essential component of how mammals regulate t
|Contact: Karen Kreeger|
University of Pennsylvania School of Medicine