Natural molecules induce and synergize to boost expression of the human antimicrobial peptide β-defensin-3.

Proc Natl Acad Sci U S A. 2018 Oct 1. pii: 201805298. doi: 10.1073/pnas.1805298115. [Epub ahead of print] Sechet E1,2, Telford E1,2, Bonamy C1,2, Sansonetti PJ3,2,4, Sperandio B3,2. Author information 1 Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, 75015 Paris, France. 2 Unité INSERM U1202, Institut Pasteur, 75015 Paris, France. 3 Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, 75015 Paris, France; philippe.sansonetti@pasteur.fr brice.sperandio@pasteur.fr. 4 Chaire de Microbiologie et Maladies Infectieuses, Collège de France, 75005 Paris, France. Abstract Antimicrobial peptides (AMPs) are mucosal defense effectors of the human innate immune response. In the intestine, AMPs are produced and secreted by epithelial cells to protect the host against pathogens and to support homeostasis with commensals. The inducible nature of AMPs suggests that potent inducers could be used to increase their endogenous expression for the prevention or treatment of diseases. Here we aimed at identifying molecules from the natural pharmacopoeia that induce expression of human β-defensin-3 (HBD3), one of the most efficient AMPs, without modifying the production of proinflammatory cytokines. By screening, we identified three molecules isolated from medicinal plants, andrographolide, oridonin, and isoliquiritigenin, which induced HBD3 production in human colonic epithelial cells. This effect was observed without activation of the NF-κB pathway or the expression of associated proinflammatory cytokines. We identified the EGF receptor as the target of these compounds and characterized the downstream-activated MAPK pathways. At the chromatin level, molecules increased phosphorylation of histone H3 on serine S10 and recruitment of the c-Fos, c-Jun, and Elk1 or c-Myc transcription factors at the HBD3 promoter. Interestingly, stimulating cells with a combination of andrographolide and isoliquiritigenin synergistically enhanced HBD3 induction 10-fold more than observed with each molecule alone. Finally, we investigated the molecular basis governing the synergistic effect, confirmed our findings in human colonic primary cells, and demonstrated that synergism increased cellular antimicrobial activity. This work shows the capability of small molecules to achieve induction of epithelial antimicrobial defenses while simultaneously avoiding the deleterious risks of an inflammatory response. KEYWORDS: epithelial cell; gene regulation; natural inducer; synergistic effect; β-defensin PMID: 30275324 DOI: 10.1073/pnas.1805298115