The data indicate that LPG and L. mexicana parasites exert opposing effects on PKCα activity of susceptible and resistant mouse macrophages, which correlate with the magnitude of burst oxidation and with the survival of the parasites within macrophages. Taken together, our data suggest that PKCα plays an important role in the L. mexicana infection outcome in vitro. One of the primary defence mechanisms of macrophages against Leishmania infections is the oxidative metabolism. It has been shown that L. donovani Dabrafenib parasites avoid triggering the oxidative burst by actively inhibiting
PKC in macrophages (30), and the molecule responsible of this inhibition is LPG (20). LPG is a
glycosylinositolphospholipid (GPI)-anchored polymer formed by repeating disaccharide-phosphate units, through which promastigotes interact with both the insect vector and the mammalian host. LPG is essential for infecting macrophages through various mechanisms. It has been shown that LPG alters the organization of lipid microdomains on the phagosome membrane. Additionally, LPG participates in other immune evasion mechanisms such as the efficient of scavenging toxic oxygen metabolites, modulation of inducible nitric oxide synthase (iNOS) and downregulation of PKC activation, required for the assembly of the NADPH oxidase complex (31,32). It has been proposed that Selleck Torin 1 a fraction of LPG intercolates from the lipid bilayer of the parasite to the lipid bilayer of the macrophage (33). PKCα, which is rapidly recruited to the nascent phagosome, is the predominant isoenzyme required for the O2− production and additionally regulates other macrophage functions related to host defence, such as FcγR-mediated phagocytosis and signal transduction leading to activation of ERK1/2 (14,34,35). PKCα is associated with the phagosomal membrane and phosphorylates the
myristoylated alanine-rich C kinase substrate (MARCKS), Carbohydrate a membrane protein associated with actin-based motility and with membrane trafficking. PKC-dependent phosphorylation of phagosome MARCKS leads to the movement of both lysosomes and phagosomes on microtubules, that is required for their interaction. In the J774 cell line, it has been demonstrated that the inhibition of PKCα by L. donovani LPG leads to the inhibition of F-actin depolymerization at the phagosomal membrane, thereby avoiding the fusion events required for the delivery of endosomal contents into parasitophorous vacuoles, thus permitting parasite multiplication (35–37). In this work, we analysed if the modulation of PKCα by LPG of L. mexicana was related to parasite survival in macrophages of susceptible BALB/c mice vs. cells of the more resistant C57BL/6 mice. We found that L.