Cytokine profile and nitric oxide levels in peritoneal macrophages of BALB/c mice exposed to Fucose-Mannose Ligand of Leishmania infantum combined with Glycyrrhizin

Background: The Fucose-Mannose Ligand (FML) of Leishmania infantum is a complex glycoprotein which does not elicit adequate immunogenicity in human. In recent years, adjuvant compounds derived from plants have been used for improving the immunogenicity of the vaccines. Glycyrrhizin (GL) is a natural triterpenoid saponin that has known immunomodulatory activities. In the present study, we investigated the effects of a co-treatment with FML and GL on the production of cytokines and nitric oxide ( NO) by macrophages, in vitro . Methods Lipopolysaccharide (LPS) stimulated murine peritoneal macrophages were treated with FML (5 μg/ml) of Leishmania infantum and various concentrations of GL (1 μg/ml, or 10 μg/ml or 20 μg/ml). After 48h of treatment, cell culture supernatants were recovered and the levels of TNF-α, IL-10, IL-12p70, and IP-10 were measured by sandwich ELISA and NO concentration by Griess reaction. Results Our results indicated that the treatment of activated macrophages with FML plus GL leads to enhanced production of NO, TNF-α, IL-12p70, and reduction of IL-10 levels in comparison with FML treatment alone. Conclusions We, therefore, concluded that GL can improve the immunostimulatory effect of FML on macrophages and leads to polarization of them toward an M1-like phenotype.