The in vitro and in vivo effects of Lucilia sericata larval secretions on Leishmania major

The emerging of drug resistant against Leishmania parasites prompts scientists to seek for novel therapeutic strategies against theses infectious protozoan parasites. Among different strategies, the use of larvae secretions could be suggested as a possible therapy with low side effects. Accordingly, the current study evaluated the in vitro and in vivo effects of Lucilia sericata larval secretions on Leishmania major, the causative agent of cutaneous leishmaniasis (CL). After preparation of L. sericata larval stages (L2 and L3) secretions, the potential effects of secretions were evaluated against L. major promastigotes and amastigotes (in vitro) using MTT assay. The cytotoxicity effects of secretions were also checked on uninfected macrophages. In addition, in vivo experiments were also conducted to investigate the effects of larvae’s secretions on the CL lesions induced in the BALB/c mice. Although the increased concentration of larvae secretions exhibited a direct effect on the promastigotes proliferation (viability), contrarily, L2 secretions at a concentration of 96 μg/ml represented the highest inhibitory effect on parasite (amastigotes) burden in infected macrophages. Interestingly, L3 secretions > 60 μg/ml induced inhibitory effects on amastigotes. The results relevant to the cytotoxicity effects of L2 and L3 secretions on uninfected-macrophages showed a dose dependent correlation. In vivo results were also significant, compared to the positive control group. This study suggested the plausible inhibitory effects of L. sericata larvae’s secretions on the L. major amastigotes and CL lesions progression. It seems that the characterization of all effective components/proteins in the larvae secretions and their specific targets in parasite structure or in cell (macrophage) responses could further reveal more details regarding the anti-leishmanial properties of these compounds.