Identification of Synthetic and Natural Host Defense Peptides with Leishmanicidal Activity

Abstract

Leishmania parasites are a major public health problem worldwide. Effective treatment of leishmaniasis is hampered by the high incidence of adverse effects to traditional drug therapy and the emergence of resistance to current therapeutics. A vaccine is currently not available. Host defense peptides have been investigated as novel therapeutic agents against a wide range of pathogens. Here we demonstrate that the antimicrobial peptide LL-37 and the three synthetic peptides E6, L-1018, and RI-1018 exhibit leishmanicidal activity against promastigotes and intramacrophage amastigotes of Leishmania donovani and Leishmania major. We also report that the Leishmania protease/virulence factor GP63 confers protection to Leishmania from the cytolytic properties of all L-form peptides (E6, L-1018, and LL-37) but not the D-form peptide RI-1018. The results suggest that RI-1018, E6, and LL-37 are promising peptides to develop further into components for antileishmanial therapy. Protozoan parasites belonging to the genus Leishmania are a global health problem, especially in resource-poor areas of Africa, Asia, the Americas, and Europe. Leishmania parasites cause leishmaniasis, which is classified as a neglected tropical disease. An estimated 20 million people are affected worldwide, with 1.3 million new cases each year and 20,000 to 30,000 deaths occurring annually (1). Transmission of Leishmania to the mammalian host occurs during a blood meal of infected sand flies of the genera Phlebotomus or Lutzomyia (2). Clinical manifestations of leishmaniasis vary depending on the infecting Leishmania strain. Leishmania major primarily causes a cutaneous form, with infected individuals developing characteristic but self-healing open sores. In contrast, Leishmania donovani infection can lead to a more invasive visceral leishmaniasis, also called kala-azar, which is potentially fatal if untreated.Leishmania parasites have a complex, digenetic life cycle, alternating between an extracellular, flagellated promastigote form that develops in the gut of a sand fly, and an intracellular nonmotile amastigote form that replicates in the macrophages of mammalian hosts.To date, no Leishmania vaccine is available, and current therapy is based on traditional pentavalent antimonials with considerable adverse side effects (3). Recently, oral miltefosine was approved by the U.S. Food and Drug Administration, while liposomal amphotericin B is in clinical trials for treatment against cutaneous and visceral leishmaniasis (4, 5). In addition, the increasing incidence of drug resistance in Leishmania renders currently available treatment options ineffective and further drives the need for new therapeutic agents.Cationic host defense (antimicrobial) peptides have been identified as an important part of the host innate immune response in all living species and have broad-spectrum antimicrobial, including antileishmanial, activity (6, 7). The actions of host defense peptides range from direct killing of invading pathogens to immune response modulation (8). A v...

Genome-Wide Discovery of Genes Required for Capsule Production by Uropathogenic Escherichia coli

“…The low GC content of these three genes could explain their absence from identification in the output pool, as the mini-Tn 5 transposon used to create the PA45B mutant library preferentially inserts into GC-rich regions ( 42 ). This has also been observed in another TraDIS study using the mini-Tn 5 transposon, where an overall increased transposon insertion frequency in high-GC versus low-GC regions was observed ( 43 ).…”

“…PA45B was sequenced on a Pacific Biosciences (PacBio) 249 RSII system using the P4 polymerase and C2 sequencing chemistry. The raw sequencing data were assembled as previously described ( 43 ). Annotation of the PA45B genome sequence was performed using PROKKA v1.11 ( 63 ) and the EcoCyc database ( 64 ), and the sequence was visualized in Artemis ( 65 ).…”

“…Genomic DNA from each sample (tests and controls) was subjected to library preparation by using the Nextera DNA library prep kit (Illumina) with slight modification to amplify and sequence Tn 5 insertion sites ( 43 ). Briefly, 50 ng of genomic DNA was fragmented and enzymatically tagged with an adapter sequence (“tagmentation”) and then purified using the Zymo DNA clean and concentrator kit (Zymo Research).…”

Vitamin D increases killing of intracellularLeishmania amazonensis in vitroindependently of macrophage oxidative mechanisms

“…Because of this, sunbathing is recommended for patients with tuberculosis, in order to favour the production of LL-37 and consequently the kill of M. tuberculosis (Rivas-Santiago et al ., 2008). In addition, the LL-37 peptide has been shown to have antileishmanial activity against promastigotes and amastigotes of L. donovani and L. major (Marr et al ., 2016). It also has been shown that cathelicidins interact with membranes of pathogens causing permeation and disintegration of these cell membranes (Kościuczuk et al ., 2012).…”

Efflux pumps and antimicrobial resistance: Paradoxical components in systems genomics

“…In order to combat the resistant strains, various combinatorial therapies have been used. Due to increased drug selectivity, reduced toxicity and compatibility with the target protein structures AMPs, for example, dermaseptins, cecropins, melettin, etc., have been described as a first line of defense against pathogen invasion, including protozoa (Hopkins and Groom, 2002;Lynn et al, 2011;Mangoni et al, 2005;Marr et al, 2016;Toro et al, 2013;Ruiz-Santaquiteria et al, 2017) and are under intense investigation to improve their druggability. Their mode of action involves the perturbation of protozoan homeostasis by directly disrupting the cellular membranes, interaction and interference with key processes in the parasite metabolism (Afacan et al, 2012;Jenssen et al, 2006;Torrent et al, 2012b).…”