Cholera Toxin B Subunit and Peptide LKEKK Inhibit TNF-α Signaling in Intestinal Epithelial Cells and Reduce Inflammation in a Mouse Model of Colitis

Cholera toxin B subunit (CT-B) and synthetic peptide LKEKK corresponding to the sequence 16-20 of thymosin-α1 and the sequence 131-135 of interferon-α2 (the concentration range of 100-5000 µM) significantly reduced TNF-α-stimulated pro-inflammatory cytokine expression and increases the expression of the anti-inflammatory cytokine IL-10 in human Caco-2 intestinal epithelial cells. In a mouse model of dextran sodium sulfate-induced colitis CT-B and peptide, LKEKK (20 mg/kg body weight orally for 14 days) decreased the production of TNF-α and IL-6, as well as the severity of inflammation. Thus, CT-B and peptide LKEKK are able to suppress inflammation in vitro and in vivo.