Molecular Cell Biology Laboratory, Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata, India.
J Antimicrob Chemother. 2011 Mar;66(3):618-25. doi: 10.1093/jac/dkq502. Epub 2011 Jan 14.
The aim of this study was to evaluate and characterize the antileishmanial efficacy of fucoidan, a polyanionic sulphated polysaccharide from brown algae, in experimental infections of BALB/c mice with antimony-susceptible (AG83) and -resistant (GE18ER) Leishmania donovani.
The effect of fucoidan was assessed against intracellular parasites in cultured macrophages and in suppressing splenic and liver parasite burdens in a BALB/c mouse model of visceral leishmaniasis by microscopic evaluation of surviving intracellular amastigotes stained with Giemsa. To evaluate the type of immunological responses, real-time PCR and ELISA were performed for various Th1 and Th2 cytokines in both in vitro and in vivo infected conditions. To determine the effector mechanism, reactive oxygen species (ROS) and NO were measured in fucoidan-treated animals by H(2)DCFDA-based fluorometric analysis and Griess reaction, respectively.
In addition to having appreciable inhibitory effect on amastigote multiplication within macrophages (>93% inhibition at 50 μg/mL), complete elimination of liver and spleen parasite burden was achieved by fucoidan at a dose of 200 mg/kg/day given orally, 3 times weekly, in a 6-week mouse model of both antimony-susceptible and -resistant strains. This curative effect is associated with switching of T cell differentiation from Th2 to Th1 mode. Further, splenocytes of fucoidan-treated infected (AG83 and GE18FR) mice generated significantly enhanced levels of superoxide and NO. Not only was this treatment curative when administered orally 15 days post-infection, but it also imparted resistance to reinfection.
These results suggest the effectiveness of fucoidan as potent immunomodulator for controlling both antimony-susceptible and -resistant visceral leishmaniasis.
本研究旨在评估褐藻来源的多阴离子硫酸多糖岩藻聚糖对敏感（AG83）和耐药（GE18ER）利什曼原虫感染 BALB/c 小鼠的抗利什曼原虫疗效，并对其进行特征描述。
通过吉姆萨染色观察存活的细胞内无鞭毛体，评估岩藻聚糖对培养的巨噬细胞内寄生虫和抑制 BALB/c 小鼠内脏利什曼病模型中脾和肝寄生虫负荷的影响。为评估免疫反应类型，在体外和体内感染条件下，通过实时 PCR 和 ELISA 检测各种 Th1 和 Th2 细胞因子。为确定效应机制，通过基于 H2DCFDA 的荧光分析和格里斯反应分别测量岩藻聚糖处理动物中的活性氧（ROS）和 NO。
岩藻聚糖除了对巨噬细胞内无鞭毛体的增殖具有明显的抑制作用（50μg/ml 时抑制率>93%）外，还能通过口服给药，每周 3 次，每次 200mg/kg，在 6 周的敏感和耐药株小鼠模型中完全消除肝和脾的寄生虫负荷。这种疗效与 T 细胞分化从 Th2 向 Th1 模式的转变有关。此外，岩藻聚糖治疗感染（AG83 和 GE18FR）小鼠的脾细胞产生的超氧化物和 NO 水平显著增强。这种治疗不仅在感染后 15 天口服给药时具有疗效，而且还赋予了对再感染的抵抗力。
这些结果表明岩藻聚糖作为一种有效的免疫调节剂，可控制敏感和耐药的内脏利什曼病。
