Treatment of colitis with a commensal gut bacterium engineered to secrete human TGF-β1 under the control of dietary xylan 1

Inflamm Bowel Dis. 2011 Sep;17(9):1925-35. doi: 10.1002/ibd.21565. Epub 2010 Dec 17.


Background: While cytokine therapy and the use of immunosuppressive cytokines such as transforming growth factor-β (TGF-β) offer great potential for the treatment of inflammatory bowel disease (IBD), issues concerning formulation, stability in vivo, delivery to target tissues, and potential toxicity need to be addressed. In consideration of these problems we engineered the human commensal bacterium Bacteroides ovatus for the controlled in situ delivery of TGF-β(1) and treatment of colitis.

Methods: Sequence encoding the human tgf-β1 gene was cloned downstream of the xylanase promoter in the xylan operon of B. ovatus by homologous recombination. Resulting recombinants (BO-TGF) were tested for TGF-β production in the presence and absence of polysaccharide xylan in vitro and in vivo, and used to treat experimental murine colitis. Clinical and pathological scores were used to assess the effectiveness of therapy. Colonic inflammatory markers including inflammatory cytokine expression were assessed by colorimetric assay and real-time polymerase chain reaction (PCR).

Results: BO-TGF secreted high levels of biologically active dimeric TGF-β in vitro and in vivo in a xylan-controlled manner. Administration of xylan in drinking water to BO-TGF-treated mice resulted in a significant clinical improvement of colitis, accelerating healing of damaged colonic epithelium, reducing inflammatory cell infiltration, reducing expression of proinflammatory cytokines, and promoting production of mucin-rich goblet cells in colonic crypts. These beneficial effects are comparable and in most cases superior to that achieved by conventional steroid therapy.

Conclusions: This novel drug delivery system has potential for the targeted and controlled delivery of TGF-β(1) and other immunotherapeutic agents for the long-term management of various bowel disorders.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacteroides / genetics*
  • Biological Assay
  • Colitis / chemically induced
  • Colitis / pathology
  • Colitis / therapy*
  • Cytokines / metabolism
  • Dextran Sulfate / toxicity
  • Diet*
  • Disease Models, Animal
  • Drinking Water
  • Drug Delivery Systems
  • Genetic Engineering*
  • Goblet Cells / metabolism
  • Goblet Cells / pathology
  • Homologous Recombination
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Promoter Regions, Genetic / genetics
  • Real-Time Polymerase Chain Reaction
  • Transforming Growth Factor beta1 / genetics
  • Transforming Growth Factor beta1 / metabolism*
  • Xylans / pharmacology*


  • Cytokines
  • Drinking Water
  • Transforming Growth Factor beta1
  • Xylans
  • Dextran Sulfate