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“Background Helicobacter pylori is carried by more than half of the world’s adult population [1]. It can chronically colonize the human gastric mucosa, where it is found in the mucus layer and is adhered to epithelial cells [2]. Although most infected subjects remain asymptomatic, infection with H. pylori can promote severe gastritis [3] and significantly increase the risk of gastric malignancies [4, 5]. In some epidemiological studies, H. pylori eradication was shown to be effective in gastric cancer prevention [6, 7]. Additionally, H. pylori BAY 73-4506 purchase eradication was found to decrease the incidence and the severity of lesions with carcinogenic potential in animal

models [8, 9]. Natural mechanisms that protect the host from H. pylori infections depend on the function of the innate defense system in which antibacterial peptides such as cathelicidin LL-37 [10, 11] and O-glycans in gastric mucin [12] play a key role. LL-37 find more is a proteolytically processed peptide derived from the C-terminal domain of human cathelicidin (hCAP-18/LL-37) that is constitutively released to the extracellular space by phagocytic

granulocytes and epithelial cells [13]. Functions ascribed to LL-37 include prevention of bacterial growth [14], neutralization of bacterial wall molecule bioactivity [15], and activation of host cells by binding specific cell membrane receptors [16–18]. H. pylori upregulates the production of LL-37/hCAP18 by the gastric epithelium, suggesting that cathelicidin or its derivative LL-37 contributes to determining the balance between host mucosal defense and H. pylori survival mechanisms that govern chronic infection with this gastric pathogen [10, 11]. Cationic antibacterial peptides (CAPs) including LL-37 have been extensively investigated as a potential source of new antibacterial molecules. The engineered WLBU2 peptide whose residues are Calpain arranged to form an amphipathic helical structure with optimal charge and hydrophobic density, overcomes some limitations of natural LL-37 such as sensitivity to Mg2+ or Ca2+ and inactivation by blood serum [19]. Therefore

WLBU2 could treat infections where LL-37 is ineffective. In order to generate molecules able to mimic CAPs’ ability to compromise bacterial membrane integrity, non-peptide ceragenins with cationic, facially amphiphilic structures characteristic of most antimicrobial peptides were developed. Ceragenins such as CSA-13 reproduce the required CAP morphology using a bile-acid scaffolding and appended amine groups [20]. They are bactericidal against both Gram-positive and Gram-negative organisms, including drug-resistant bacteria such as clinically relevant methicillin-resistant Staphylococcus aureus (MRSA), and a previous susceptibility study demonstrated that CSA-13 has a MIC50/MBC50 ratio of 1 [21, 22]. In this study we compare the bactericidal potency of LL-37, WLBU2 and CSA-13 against clinical isolates of H. pylori.