The utility of trehalose and niclosamide in modulating autophagy to inhibit Leishmania major infection in macrophage cells in vitro

Abstract

Leishmaniasis is classified as a neglected tropical disease that the available anti-leishmanial medications are limited, often accompanied by side effects, high costs, and the necessity for prolonged treatment. Factors such as the diversity of species, drug resistance of the parasites, and the presence of coexisting diseases significantly influence treatment efficacy. Autophagy is an immune mechanism to eliminates intracellular pathogens, however, many of them impairs autophagy in phagocytes. Given these challenges, the current study aimed to evaluate the antileishmanial properties of niclosamide and trehalose to restrict L. major infection in vitro. According to qPCR and Giemsa staining results, niclosamide exhibited an inhibitory effect on the growth of L. major in macrophages in vitro, but trehalose indicated no significant effect on amastigotes. Niclosamide demonstrated an IC 50 of 479.5, 380.11, and 378.26 µg/ml at 6, 24, and 48 h, respectively, and also showed an EC 50 of 715.23, 708.67 and 690.7 µg/ml at these times, respectively, indicating significant inhibition of L. major promastigotes and amastigotes. Furthermore, niclosamide displayed notable inhibitory effects on the J774.A1 cell line, with CC 50 values of 446.7, 375.9, and 341.4 µg/ml at 6, 24, and 48 h, respectively. The qRT-PCR analysis of autophagy markers revealed a meaningful upregulation of ATG12 and downregulation of mTOR ( p < 0.0001). Niclosamide (400 µg/ml) and trehalose (800 µg/ml) induced apoptosis in 47.87% and 37.97% of infected macrophages, respectively, while in the combination group, the apoptosis rate was 27.65%. This study concluded that, better than combination therapy, niclosamide treatment may offer a promising agent for controlling Leishmaniasis in vivo in future research.