Cytokine profile and nitric oxide levels in peritoneal macrophages of BALB/c mice exposed to the fucose-mannose ligand of Leishmania infantum combined with glycyrrhizin

Abstract

Abstract Background The fucose-mannose ligand (FML) of Leishmania infantum is a complex glycoprotein which does not elicit adequate immunogenicity in humans. In recent years, adjuvant compounds derived from plants have been used for improving the immunogenicity of vaccines. Glycyrrhizin (GL) is a natural triterpenoid saponin that has known immunomodulatory activities. In the present study, we investigated the effects of 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 L. infantum and various concentrations of GL (1 μg/ml, 10 μg/ml and 20 μg/ml). After 48 h 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 indicate that the treatment of activated macrophages with FML plus GL leads to enhanced production of NO, TNF-α and IL-12p70, and reduction of IL-10 levels in comparison with FML treatment alone. Conclusions Therefore, we concluded that GL can improve the immunostimulatory effect of FML on macrophages and leads to their polarization towards an M1-like phenotype.

Keywords

• Fucose-mannose ligand
• Glycyrrhizin
• Macrophage
• Nitric oxide
• Visceral leishmaniasis