4th Annual BMRP Investigator Meeting - Abstract
Clostridium perfringens as a Novel Therapeutic Vehicle in Inflammatory Bowel Disease
Scott Plevy1,2,a, Fengling Li1,2, Yue Chen3, Shaival Dave1,2, Jeremy Tilstra1,2, Paul Robbins4, Albert Baldwin5, Bruce McClane4 and Phalguni Gupta3
1Department of Medicine, 2Department of Immunology, 3Department of Infectious Diseases and Microbiology, Graduate School of Public Health, 4Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine (Pittsburgh, Pennsylvania, U.S.A.); 5Lineberger Cancer Center, The University of North Carolina at Chapel Hill (Chapel Hill, North Carolina, U.S.A.)
The goal of this project is to create a novel biologic therapeutic particularly targeted to Crohn’s disease using a normal constituent of the enteric bacterial flora, Clostridium perfringens (CP). CP is better known as a cause of self-limited food borne disease. In humans, vegetative CP sporulates in the small intestine. In the case of pathogenic strains, spores lyse in the terminal ileum, releasing large amounts of CP enterotoxin (cpe). We have genetically engineered CP, replacing the plasmid-based cpe gene with HIV and SIV peptides. These peptides are delivered directly to the distal small bowel in rodents and generate mucosal immune responses in vivo.
Recombinant CP that express interleukin-10 (IL-10) (IL-10 CP) has been successfully engineered. Sporulating IL-10 CP produce immunoreactive IL-10 detectable by ELISA and Western blot. In vivo studies have been complicated by relative insolubility of the expressed protein leading to the conclusion that CP may in fact be most amenable to the delivery of short anti-inflammatory peptides. One such molecule, an IκB kinase inhibitor NEMO binding domain peptide linked to a cationic peptide transduction domain (PTD-NBD), has become a focus of recent studies. As a therapeutic modality, PTD-NBD has the theoretic advantage of selectively inhibiting activated NF-κB and the potential for local and systemic administration. This 25 amino acid peptide administered (10 mg/kg IP) to IL-10-/- mice for two weeks ameliorates colitis (colitis score 1.6±0.4 vs. 5.4±0.9 with vehicle, p<0.05). Mechanistically, mucosal explants and splenocytes cultured ex vivo for 24 hours demonstrate decreased cytokine expression, suggesting that inhibition is not related to the continued presence of the short-lived PTD-NBD peptide.
CP may pose several significant advantages over other bacteriotherapeutic approaches for inflammatory bowel disease: 1) molecules can be delivered specifically to the distal small bowel; 2) these molecules are produced at extremely high local concentrations, and 3) no significant immune responses occur against CP. These results also demonstrate that inhibitors of IKK, in particular, a PTD-NBD peptide, could be therapeutic in the treatment of colitis.
aPrincipal Investigator