Phylloseptin-1 is Leishmanicidal for Amastigotes of Leishmania amazonensis Inside Infected Macrophages

Abstract

<jats:p>Leishmania protozoans are the causal agents of neglected diseases that represent an important public health issue worldwide. The growing occurrence of drug-resistant strains of Leishmania and severe side effects of available treatments represent an important challenge for the leishmaniases treatment. We have previously reported the leishmanicidal activity of phylloseptin-1 (PSN-1), a peptide found in the skin secretion of Phyllomedusa azurea (=Pithecopus azureus), against Leishmania amazonensis promastigotes. However, its impact on the amastigote form of L. amazonensis and its impact on infected macrophages are unknown. In this work, we evaluated the effects of PSN-1 on amastigotes of L. amazonensis inside macrophages infected in vitro. We assessed the production of hydrogen peroxide and nitric oxide, as well as the levels of inflammatory and immunomodulatory markers (TGF-β, TNF-α and IL-12), in infected and non-infected macrophages treated with PSN-1. Treatment with PSN-1 decreased the number of infected cells and the number of ingested amastigotes per cell when compared with the untreated cells. At 32 µM (64 µg/mL), PSN-1 reduced hydrogen peroxide levels in both infected and uninfected macrophages, whereas it had little effect on NO production or TGF-β release. The effect of PSN-1 on IL-12 and TNF-α secretion depended on its concentration, but, in general, their levels tended to increase as PSN-1 concentration increased. Further in vitro and in vivo studies are needed to clarify the mechanisms of action of PSN-1 and its interaction with the immune system aiming to develop pharmacological applications.</jats:p>

Mechanistic Insights into the Leishmanicidal and Bactericidal Activities of Batroxicidin, a Cathelicidin-Related Peptide from a South American Viper (Bothrops atrox)

“…39 Moreover, several cathelicidins increase chemokine expression in RAW 264.7 murine cells. 40 Finally, in recent studies using PSN-1 (phylloseptin, an AMP isolated from amphibian skin secretions), 41 leishmanicidal activity against amastigotes in infected macrophages was related to the modulation of markers such as nitric oxide and TNF-α. Further exploration of these immunomodulatory mechanisms related to BatxC and its synthetic analogues in future studies is needed to better understand the mechanism of intracellular action.…”

ACW-02 an Acridine Triazolidine Derivative Presents Antileishmanial Activity Mediated by DNA Interaction and Immunomodulation

“…The microbicidal effect was evaluated by determining infection in 200 macrophages, being expressed as a product of the mean of phagocyted Leishmanias by the percentage of infected macrophages. To determine the estimated percentage of macrophages adhered to the coverslips, the cells present in 10% of the coverslips were quantified with the assistance of optical microscopy (400×) [ 86 ].…”

“…The fluorescence intensity in each sample was captured on the BD LRS II FORTESSA flow cytometer using the DIVA program version 7 (BD Bioscience), and the fluorescence data were processed using the FCAP array program version 3 (BD Bioscience). The experiments were performed in triplicate [ 86 ].…”

“…The fluorescence intensity in each sample was captured on the BD LRS II FORTESSA flow cytometer using the DIVA program version 7 (BD Bioscience) and the mean fluorescence intensity (MFI) was obtained after processing the data in the FlowJoTM version 10.6.1. The experiment was performed in triplicate and the results were calculated as the difference in MFI in each group [ 86 ].…”

Peptides to Tackle Leishmaniasis: Current Status and Future Directions

“…One approach to improving anti-amastigote activity was advanced by Kückelhaus et al [ 108 ] and relied on the hypothesis that the immune response triggered by the peptide’s interaction with the macrophage could amplify signals that affect the parasite’s survival. These authors evaluated phylloseptin–1 as an inhibitor of the progression of infection by L. amazonensis in macrophages and confirmed that the peptide reduced the number of infected macrophages and the amastigote load, while stimulating the production of signal molecules such as IL–12 and TNF–α, which seemed to enhance the macrophages’ ability to eliminate the parasites.…”