The leishmanicidal effect of Lucilia sericata larval saliva and hemolymph on in vitro Leishmania tropica

The therapeutic effect of larval saliva and hemolymph of Lucilia sericata on the treatment of Leishmania major lesion in BALB/c mice946

BACKGROUND

Treatment of cutaneous leishmaniasis (CL) remains a major challenge for the public health and medical community. It has been claimed that natural compounds derived from fly larvae have anti-leishmania properties against some species of Leishmania. The present study aimed at assessing the in vitro effects of larval products of Lucilia sericata against the promastigote and intracellular amastigote forms of Leishmania major. Also, the therapeutic effect of larval products on lesions induced by L. major infection was evaluated in BALB/c mice models.

METHODS

Parasite specimens and macrophage cells were exposed to varying concentrations of larval products for 24-120 h. Lesion progression and parasite load were investigated in the models to assess the therapeutic effects of the products.

RESULTS

The larval products displayed more potent cytotoxicity against L. major promastigotes. The IC50 values for larval saliva and hemolymph were 100.6 and 37.96 ug/ml, respectively. The IC50 of glucantime was 9.480 ug/ml. Also, the saliva and hemolymph of L. sericata exhibited higher cytotoxicity against the promastigotes of L. major but were less toxic to the macrophage cells. Treatment with leishmanicidal agents derived from larvae of L. sericata decreased the infection rate and the number of amastigotes per infected host cell at all concentrations. Lesion size was significantly (F (7, 38) = 8.54, P < 0.0001) smaller in the treated mice compared with the untreated control group. The average parasite burden in the treated mice groups (1.81 ± 0.74, 1.03 ± 0.45 and 3.37 ± 0.41) was similar to the group treated with a daily injection of glucantime (1.77 ± 0.99) and significantly lower (F (7, 16) = 66.39, P < 0.0001) than in the untreated control group (6.72 ± 2.37).

CONCLUSIONS

The results suggest that the larval products of L. sericata were effective against L. major parasites both in vivo and in vitro. However, more clinical trial studies are recommended to evaluate the effects of these larval products on human subjects.

Models for cytotoxicity screening of antileishmanial drugs: what has been done so far?

A growing number of studies have demonstrated the in vitro potential of an impressive number of antileishmanial candidates in the past years. However, the lack of uniformity regarding the choice of cell types for cytotoxicity assays may lead to uncomparable and inconclusive data. In vitro assays relying solely on non-phagocytic cell models may not represent a realistic result as the effect of an antileishmanial agent should ideally be presented based on its cytotoxicity profile against reticuloendothelial system cells. In the present review, we have assembled studies published in the scientific literature from 2015 to 2021 that explored leishmanicidal candidates, emphasising the main host cell models used for cytotoxicity assays. The pros and cons of different host cell types as well as primary cells and cell lines are discussed in order to draw attention to the need to establish standardised protocols for preclinical testing when assessing new antileishmanial candidates.

Correction to: The leishmanicidal efect of Lucilia sericata larval saliva and hemolymph on in vitro Leishmania tropica

An amendment to this paper has been published and can be accessed via the original article.