Protective Profile Involving CD23/IgE-mediated NO Release is a Hallmark of Cutaneous Leishmaniasis Patients from the Xakriabá Indigenous Community in Minas Gerais, Brazil

Antileishmanial activity, cytotoxicity and cellular response of amphotericin B in combination with crotamine derived from Crotalus durissus terrificus venom using in vitro and in silico approaches

OBJECTIVE

To investigate the in vitro activity, synergism, cytotoxicity and cellular immunological response, as well as the molecular affinity between amphotericin B (AmB) and crotamine (CTA), derived from Crotalus durissus terrificus venom against Leishmania amazonensis.

METHODS

This study performed the inhibition of promastigotes and amastigotes' growth under different concentrations of the drug and pharmacological combinations (AmB + CTA) based on the Berimbaum method (synergism study). The lactate dehydrogenase (LDH) quantification method was used to determine the cytotoxicity of the drug and combinations employing four cell lines (J774, HepG2, VERO, and C2C12). Following, the levels of Tumour Necrose Factor-alpha (TNF-α) and Interleukin-12 (IL-12) cytokines, using enzyme-linked immunosorbent assay (ELISA) and nitrites, as an indirect measure of Nitric Oxide (NO), using the Griess reaction were assessed in the supernatants of infected macrophages. In silico approach (molecular docking and dynamics) and binding affinity (surface plasmon resonance) between the drug and toxin were also investigated.

RESULTS

CTA enhanced AmB effect against promastigote and amastigote forms of L. amazonensis, decreased the drug toxicity in different cell lines and induced the production of important Th1-like cytokines and NO by infected macrophages. The pharmacological combination also displayed consistent molecular interactions with low energy of coupling and a concentration-dependent profile.

CONCLUSION

Our data suggest that this pharmacological approach is a promising alternative treatment against L. amazonensis infection due to the improved activity (synergistic effect) achieved against the parasites' forms and to the decreased cytotoxic effect.

A natural cell-penetrating nanopeptide combined with pentavalent antimonial as experimental therapy against cutaneous leishmaniasis

The inadequacy of available treatments for leishmaniasis has presented up to 40% therapeutic failure. This fact suggests an urgency in the discovery of new drugs or alternative approaches for treating this disease. The objective of this study was to evaluate the antileishmanial activity of combined therapy between crotamine (CTA) from Crotalus durissus terrificus and the pentavalent antimonial Glucantime® (GLU). The assays were in vitro performed measuring the inhibition of Leishmania amazonensis amastigotes, followed by the evaluation of cellular production of cytokines and nitrites. After that, analytical methods were performed in order to characterize the molecules involved in the study by Mass Spectrometry, molecular affinity through an in silico assay and Surface Plasmon Resonance. In vivo experiments with BALB/c mice were performed by analyzing parasitemia, lesion size and immunological mediators. In the in vitro experiments, the pharmacological association improved the inhibition of the amastigotes, modulated the production of cytokines and nitric oxide. The therapy improved the effectiveness of the GLU, demonstrating a decreased parasitemia in the infected tissues. Altogether, the results suggest that the combined approach with CTA and GLU may be a promising alternative for the treatment of cutaneous leishmaniasis.

Leishmania infantum induces high phagocytic capacity and intracellular nitric oxide production by human proinflammatory monocyte

BACKGROUND

The mechanism of resistance to Sb^III in Leishmania is complex, multifactorial and involves not only biochemical mechanisms, but also other elements, such as the immune system of the host.

OBJECTIVES

In this study, putative changes in the immunological profile of human monocytes infected with wild-type (WT) and antimony (Sb^III)-resistant Leishmania (Viannia) braziliensis and Leishmania (Leishmania) infantum lines were evaluated.

METHODS

Susceptibility assays WT and SbIII-resistant L. braziliensis and L. infantum were performed using lines THP-1 human monocytic lineage. Phagocytic capacity, cytokine profile, intracellular nitric oxide (NO) production and surface carbohydrate residues profile were performed in peripheral blood monocytes by flow cytometry.

FINDINGS

The phagocytic capacity and intracellular NO production by classical (CD14⁺⁺CD16^-) and proinflammatory (CD14⁺⁺CD16⁺) monocytes were higher in the presence of L. infantum lines compared to L. braziliensis lines. The results also highlight proinflammatory monocytes as the cellular subpopulation of major relevance in a phagocytosis event and NO expression. It is important to note that L. infantum induced a proinflammatory cytokine profile characterised by higher levels of TNF-α in culture supernatant than L. braziliensis. Conversely, both Leishmania lines induce high levels of IL-6 in culture supernatant. Analysis of the expression profile of surface carbohydrates showed that L. braziliensis presents 4.3-fold higher expression of galactose(β1,4)N-acetylglucosamine than L. infantum line. Interestingly, the expression level of α-N-acetylgalactosamine residues was 2-fold lower in the Sb^III-resistant L. braziliensis line than its counterpart WT line, indicating differences in surface glycoconjugates between these lines.

MAIN CONCLUSIONS

Our results showed that L. braziliensis and L. infantum induce different innate immune responses and a highly inflammatory profile, which is characteristic of infection by L. infantum, the species associated with visceral disease.

Fcγ-RI, Fcγ-RII and IL-10 as predictive biomarkers for post-therapeutic cicatrization time in monocytes from cutaneous leishmaniasis patients

Cutaneous leishmaniasis (CL) treatment is based on therapy with Glucantime^® , yet, there are few laboratory methods to monitor its success. In this study, ex vivo and in vitro evaluations of peripheral blood monocytes were performed in a longitudinal study to characterize the impact of Glucantime^® on overall phenotypic/functional features of these cells from CL patients to identify predictive biomarkers for post-therapeutic monitoring by flow cytometry. The ex vivo evaluation from CL patients demonstrated a modulatory profile before treatment, with a decrease in TLR-2, FcγRII, HLA-DR, CD86, IFN-γR, TNF, IL-12, NO, and an increase in FcγRIII and IL-10R. Conversely, treatment changes some of these biomarker expressions by decreasing FcγRIII and IL-10R and increasing IFN-γR, IL-12 and NO. Moreover, an in vitro analysis of these patients showed a reduced phagocytic capacity of Leishmania braziliensis and higher levels of IL-10 and TGF-β modulating functional profile. Regardless of the compromised L. braziliensis phagocytic capacity, treatment re-established the production of IL-12, IL-10, TGF-β and NO at the basal level. Notably, monocytes from patients with early cicatrization showed enhanced FcγRI and FcγRII expressions and reduced IL-10, which was further corroborated by a baseline fold change analysis. Finally, the logistic regression model emphasized the performance of FcγRI, FcγRII and IL-10 as robust predictive biomarkers for post-therapeutic cicatrization during cutaneous leishmaniasis.