The therapeutic effects of larval excretion/secretion of Lucilia sericata on Leishmania major under in vitro and in vivo conditions

Abstract

Background Leishmaniasis is a neglected infectious disease caused by a kinetoplastid protozoan. The disease generally manifests as characteristic skin lesions. Due to the lack of definitive treatment and drugs without side effects, many studies have focused on natural compounds as promising drugs for its treatment. This study aimed to evaluate the effects of larval excretion/secretion products (ES) of Lucilia sericata in crude and fractionated forms on Leishmania parasites under both in vitro and in vivo conditions. Methods In vitro experiments involved evaluation of ES products on both promastigotes and amastigotes inside infected macrophages, whereas in vivo experiments included comparative treatments of Leishmanial lesions of mice using Eucerin-formulated ES products and glucantime. Results The IC50 values were 38.7 µg/ml, 47.6 µg/ml, 63.3 µg/ml, and 29.1 µg/ml for crude ES, over 10 kDa ES-fraction, under 10 kDa ES-fraction, and glucantime respectively. Significant differences were observed between viability percentages of promastigotes treated with crude ES and its fractions compared to negative control (p < 0.0001). Crude ES was more effective on amastigote than other two ES fractions at 300 µg/ml concentration. Macroscopic measurement of lesion sizes revealed that the reduction of lesion size in mice treated with crude ES followed quicker cascades of healing than in those treated with glucantime and fractionated ES. Conclusion The present study showed that larval ES of Lucilia sericata in both crude and fractionated forms are effective on both intracellular and extracellular forms of L. major. It also provided evidence that the larval ES exerts both topical and systemic therapeutic effects on leishmanial lesions of the model animal.