Development of a synthetic receptor protein for sensing inflammatory mediators interferon-γ and tumor necrosis factor-α.

Intestinal inflammation has been implicated in a number of diseases, including diabetes, Crohn's disease, and irritable bowel syndrome. Important components of inflammation are interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α), which are elevated both on the luminal and submucosal sides of the intestinal epithelial barrier in several diseases. Here, we developed a novel Escherichia coli based detection system for IFN-γ and TNF-α comprised of a chimeric protein and a simple signal transduction construct, which could be deployed on the luminal side of the intestine. OmpA of E. coli was engineered to detect IFN-γ or TNF-α through the replacement of extracellular loops with peptide fragments from OprF of P. aeruginosa. OmpA/OprF chimeras were developed, capable of binding IFN-γ or TNF-α. The specific peptide fragments that bind IFN-γ were identified. IFN-γ or TNF-α binding the OmpA/OprF chimera induced the pspA promoter, driving β-galactosidase production. The OmpA/OprF chimera had a detection limit of 300 pM for IFN-γ and 150 pM for TNF-α. This work will further the development of bacteria based therapeutics for the treatment of inflammatory diseases of the gut.