Interferon inducible guanylate binding protein 1 restricts the growth of Leishmania donovani by modulating the level of cytokines/chemokines and MAP kinases.

Visceral Leishmaniasis (VL) is a zoonotic chronic endemic infectious disease caused by Leishmania donovani infection and a well-studied model for intracellular parasitism. Guanylate binding proteins (GBPs) are induced by interferons (IFNs), and play a crucial role in cell autonomous immunity and the regulation of inflammation. Guanylate-binding protein 1 (GBP1) has been shown vital for the host immune response against various pathogens. However, the role of GBP1 during VL is undefined. In the present study, we have investigated the role of GBP1 in Leishmania donovani infection using in vitro model. For that, knock down of the Gbp1 gene was carried out in both PMA differentiated human monocyte cell line THP-1 and mouse macrophages RAW264.7 cell line using siRNA based RNA interference. Infection of these cell lines revealed a high parasite load in knock down cells at 24 and 48h post infection as compared to control cells. A significant increase was observed in the level of different cytokines (IL-4, IL-10, IL-12b, IFN-γ, TNF-α) and chemokines (CXCL9, CXCL 10, and CXCL 11) in GBP1 knock down cell lines after post-infection. In GBP1 knock down cells the expression level of IFN effector molecules (iNOS and PKR) was found to be elevated in THP1 cells and remained almost unchanged in RAW264.7 cells after Leishmania donovani infection as compared to the control cells. Moreover, interestingly, the level of MAPK activated ERK1/2, and p38 MAPK were considerably induced by the parasite in knock down cells as compared to control after 24 h post-infection. This study, first time reported the involvement of GBP1 in Leishmania donovani infection by modulating the level of important cytokines, chemokines, IFN effector molecules, and MAP kinases.