Moroccan strains of Leishmania major and Leishmania tropica differentially impact on nitric oxide production by macrophages

Abstract

BackgroundCutaneous leishmaniasis (CL) is a vector-borne parasitic disease caused by protozoa of the genus Leishmania. In Morocco, CL is a public health problem mainly caused by Leishmania major and Leishmania tropica, which are responsible for zoonotic and anthroponotic CL, respectively. Macrophages are the primary cells infected by Leishmania parasites and their capacity to produce nitric oxide (NO) is of critical importance for parasite elimination. To our knowledge, the role of NO on autochthonous infections has never been investigated before. In this study, we evaluated in vitro the capacity of autochthonous primary dermotropic strains of L. major and L. tropica to modulate NO production by J774-macrophages and determine the sensitivity of both species to exogenous NO.MethodsThe infectivity of the J774 cell line was analyzed by optical microscopy. NO production by macrophages was measured by the Griess method. The sensitivity to NO by the two strains was assessed by the MTT assay using NO donors.ResultsOur results show that the percentage of infected macrophages and the average number of parasites per macrophage were similar for L. major and L. tropica strains. While L. tropica significantly inhibited NO production induced by LPS and IFN-γ stimulation in J774 macrophages, L. major did not affect it. However, soluble Leishmania antigens (SLAs) from both autochthonous primary strains significantly inhibited the production of NO by J774-macrophages in a dose-dependent manner. Finally, our results demonstrated that promastigotes and amastigotes from both strains are sensitive to SNAP NO donor in a dose-dependent manner, although L. tropica demonstrated an increased sensitivity. ConclusionsOur results suggest a differential ability of L. major and L. tropica strains to modulate the capacity of macrophages to produce NO. The increased ability of L. tropica to inhibit NO production by macrophages might come as a necessity due to its higher sensitivity to NO donor. Our results provide one explanation for the tendency of L. tropica to cause chronic lesions and may contribute to the different physiopathology of CL in Morocco.

The Modulation of NADPH Oxidase Activity in Human Neutrophils by Moroccan Strains of Leishmania major and Leishmania tropica Is Not Associated with p47phox Phosphorylation

“…They were infected during a summer stay in a known endemic foci of CL due to L. tropica or L. major. The patients presented with different clinical phenotypes in terms of the number of dermal lesions (simple vs. multiple) and lesion healing time after treatment [ 15 ].…”

“…The lesions due to L. tropica are usually single, and progress slowly to healing, over several months. In contrast, lesions due to L. major are often multiple, and heal after four to six months [ 15 ]. A recent analysis of CL cases diagnosed in Casablanca (Morocco) showed heterogeneity in the appearance of lesions that was not significantly associated with either of the responsible Leishmania species, i.e., L. major and L. tropica [ 46 ].…”

“…The increase in ROS production dampens infection establishment while the impairment in ROS production would favor infection by allowing greater survival of the parasites within neutrophils, thus facilitating their subsequent transfer into macrophages [ 9 ]. Additionally, we have previously reported that L. tropica is able to inhibit NO production by macrophages [ 15 ], therefore suggesting a more global impact of L. tropica on innate immune cells. It seems that L. tropica has developed a more efficient escape mechanism of innate immunity than L. major .…”

“…Pathogens are killed by phagocytes through different mechanisms such as the generation of superoxide anion (O 2 − ), the precursor of other highly toxic reactive oxygen species (ROS) such as hydrogen peroxide (H 2 O 2 ), hydroxyl radical ( • OH) and hypochlorous acid (HOCl). Recently, we reported that L. major and L. tropica modulated the production by macrophages of nitric oxide (NO) in a different manner [ 15 ]. However, controversial results have been reported regarding ROS production by Leishmania -infected PMNs [ 16 , 17 ].…”

Boosting innate immunity:Asaiabacteria expressing a protein fromWolbachiadetermine macrophage activation and killing ofLeishmania

“…The above results encouraged us to investigate whether macrophage activation determined by Asaia WSP could result in the phagocytosis and killing of Leishmania . The anti-leishmanial effect of Asaia WSP was determined by microscopy observation after 24h and 48h of incubation, as reported in Maksouri et al (2017). J774A.1 cells were pretreated with Asaia for 2h and then incubated with L. infantum parasites.…”