Natural Products & Medicinal Plants Research Center, North Khorasan University of Medical Sciences, Bojnurd, Iran.
Vector-borne Diseases Research Center, North Khorasan University of Medical Sciences, Bojnurd, Iran.
Parasit Vectors. 2020 Jul 20;13(1):363. doi: 10.1186/s13071-020-04243-7.
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.
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.
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.
Therefore, we concluded that GL can improve the immunostimulatory effect of FML on macrophages and leads to their polarization towards an M1-like phenotype.
利什曼原虫的岩藻糖甘露糖配体（FML）是一种复杂的糖蛋白，在人类中不能引起足够的免疫原性。近年来，植物来源的佐剂化合物已被用于提高疫苗的免疫原性。甘草酸（GL）是一种天然的三萜皂苷，具有已知的免疫调节活性。在本研究中，我们研究了 FML 和 GL 共同处理对体外巨噬细胞细胞因子和一氧化氮（NO）产生的影响。
用脂多糖（LPS）刺激小鼠腹腔巨噬细胞，用利什曼原虫的 FML（5μg/ml）和不同浓度的 GL（1μg/ml、10μg/ml 和 20μg/ml）处理。处理 48 小时后，回收细胞培养上清液，并通过夹心 ELISA 测定 TNF-α、IL-10、IL-12p70 和 IP-10 的水平，通过 Griess 反应测定 NO 浓度。
我们的结果表明，与单独用 FML 处理相比，用 FML 加 GL 处理激活的巨噬细胞导致 NO、TNF-α 和 IL-12p70 的产生增加，IL-10 水平降低。
因此，我们得出结论，GL 可以增强 FML 对巨噬细胞的免疫刺激作用，并导致其向 M1 样表型极化。
