Human Salivary Protein Histatin 5 Has Potent Bactericidal Activity against ESKAPE Pathogens

Abstract

ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanni, Pseudomonas aeruginosa, and Enterobacter species)pathogens have characteristic multiple-drug resistance and cause an increasing number of nosocomial infections worldwide. Peptide-based therapeutics to treat ESKAPE infections might be an alternative to conventional antibiotics. Histatin 5 (Hst 5) is a salivary cationic histidine-rich peptide produced only in humans and higher primates. It has high antifungal activity against Candida albicans through an energy-dependent, non-lytic process; but its bactericidal effects are less known. We found Hst 5 has bactericidal activity against S. aureus (60-70% killing) and A. baumannii (85-90% killing) in 10 and 100 mM sodium phosphate buffer (NaPB), while killing of >99% of P. aeruginosa, 60-80% E. cloacae and 20-60% of E. faecium was found in 10 mM NaPB. Hst 5 killed 60% of biofilm cells of P. aeruginosa, but had reduced activity against biofilms of S. aureus and A. baumannii. Hst 5 killed 20% of K. pneumonia biofilm cells but not planktonic cells. Binding and uptake studies using FITC-labeled Hst 5 showed E. faecium and E. cloacae killing required Hst 5 internalization and was energy dependent, while bactericidal activity was rapid against P. aeruginosa and A. baumannii suggesting membrane disruption. Hst 5-mediated killing of S. aureus was both non-lytic and energy independent. Additionally, we found that spermidine conjugated Hst 5 (Hst5-Spd) had improved killing activity against E. faecium, E. cloacae, and A. baumannii. Hst 5 or its derivative has antibacterial activity against five out of six ESKAPE pathogens and may be an alternative treatment for these infections.

Human Antimicrobial Peptide Hepcidin 25-Induced Apoptosis in Candida albicans

“…For example, histatin 5 (Hst 5) gains access to the cytosol through It is known that some AMPs can enter cells without damaging the plasma membrane in an energy-dependent manner. For example, histatin 5 (Hst 5) gains access to the cytosol through transporters or receptor-mediated endocytosis [36][37][38], whereas pep-1 translocates through a physical-mediated mechanism [39]. To determine whether hep 25 translocation across the membrane requires energy consumption, cells were pretreated with the metabolic inhibitors sodium azide (NaN 3 ) and carbonyl cyanide m-chlorophenyl hydrazine (CCCP) and then incubated with hep 25.…”

Expression of Cell-Penetrating Peptides Fused to Protein Cargo

“…We selected SynB, Hst5, and MPG as our CPPs, because they were each previously shown to translocate cargo into cells [Alhakamy et al, 2013;Copolovici et al, 2014;Du et al, 2017;Ilsen and Onsan, 1998;Kristensen et al, 2016;Morris et al, 2008;Shin et al, 2014;Temsamani and Laruelle, 2010;Yu et al, 2015] and use varied mechanisms for translocation [Drin et al, 2003;Gong et al, 2018;Gong and Karlsson, 2017;Rajarao et al, 2002Rajarao et al, , 2003Tan et al, 1996;Temsamani and Laruelle, 2010]. SynB (RGGRLSYSRRRFSTSTGR) is from the antimicrobial peptide protegrin 1, an 18-amino acid peptide initially isolated from porcine leukocytes [Temsamani and Laruelle, 2010].…”

Design, Engineering and Discovery of Novel α-Helical and β-Boomerang Antimicrobial Peptides against Drug Resistant Bacteria

“…The human proteome contains bonafide host defence peptides and proteins, which protect against disease. Human AMPs, such as LL37, various defensins (α and β), histatins, and dermcidin, are expressed in skin, eyes, sweat, lungs, intestine lining, and the bladder [147][148][149]. These AMPs can directly kill pathogens or have immunomodulatory activity.…”