Therapeutic Efficacy of Stable Analogues of Vasoactive Intestinal Peptide against Pathogens

• Published in: The Journal of biological chemistry 2014-05, Vol.289 (21), p.14583-14599
• Main Authors: Campos-Salinas, Jenny, Cavazzuti, Antonio, O'Valle, Francisco, Forte-Lago, Irene, Caro, Marta, Beverley, Stephen M., Delgado, Mario, Gonzalez-Rey, Elena
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Antimicrobial Peptides; Bacteria; Cutaneous Leishmaniasis; Endotoxemia - drug therapy; Endotoxemia - microbiology; Female; Gram-Negative Bacteria - drug effects; Gram-Negative Bacteria - genetics; Gram-Positive Bacteria - drug effects; Gram-Positive Bacteria - genetics; Hydrogen Bonding; Leishmania major - drug effects; Leishmania major - genetics; Leishmania major - ultrastructure; Leishmaniasis, Cutaneous - drug therapy; Leishmaniasis, Cutaneous - parasitology; Lipopolysaccharide (LPS); Mice; Mice, Inbred BALB C; Microbial Viability - drug effects; Microbiology; Microscopy, Electron; Models, Molecular; Molecular Sequence Data; Mutation; Neuropeptide; Protein Conformation; Sepsis; Sepsis - drug therapy; Sepsis - microbiology; Survival Analysis; Treatment Outcome; Vasoactive Intestinal Peptide; Vasoactive Intestinal Peptide - analogs & derivatives; Vasoactive Intestinal Peptide - chemistry; Vasoactive Intestinal Peptide - pharmacology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.560573

Vasoactive intestinal peptide (VIP) is an anti-inflammatory neuropeptide recently identified as a potential antimicrobial peptide. To overcome the metabolic limitations of VIP, we modified the native peptide sequence and generated two stable synthetic analogues (VIP51 and VIP51(6–30)) with better antimicrobial profiles. Herein we investigate the effects of both VIP analogues on cell viability, membrane integrity, and ultrastructure of various bacterial strains and Leishmania species. We found that the two VIP derivatives kill various non-pathogenic and pathogenic Gram-positive and Gram-negative bacteria as well as the parasite Leishmania major through a mechanism that depends on the interaction with certain components of the microbial surface, the formation of pores, and the disruption of the surface membrane. The cytotoxicity of the VIP derivatives is specific for pathogens, because they do not affect the viability of mammalian cells. Docking simulations indicate that the chemical changes made in the analogues are critical to increase their antimicrobial activities. Consequently, we found that the native VIP is less potent as an antibacterial and fails as a leishmanicidal. Noteworthy from a therapeutic point of view is that treatment with both derivatives increases the survival and reduces bacterial load and inflammation in mice with polymicrobial sepsis. Moreover, treatment with VIP51(6–30) is very effective at reducing lesion size and parasite burden in a model of cutaneous leishmaniasis. These results indicate that the VIP analogues emerge as attractive alternatives for treating drug-resistant infectious diseases and provide key insights into a rational design of novel agents against these pathogens. Antimicrobial properties of the anti-inflammatory neuropeptide VIP are limited by its unstable nature. The VIP derivatives protected against polymicrobial sepsis and cutaneous leishmaniasis by selectively killing pathogens through membrane-disrupting mechanisms. Modification of critical residues in the native VIP sequence generates stable peptides with potent antimicrobial activities in vitro and in vivo. This work indicates a molecular rationale for designing new agents against drug-resistant infectious diseases.