Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
Malar J. 2013 Aug 27;12:296. doi: 10.1186/1475-2875-12-296.
Malaria anaemia is still a major public health problem and its pathogenesis still unclear. Interestingly, the progression of anaemia is at relatively low parasitaemia with some mortality in the semi-immune individuals in the endemic areas despite adequate erythropoietin (EPO) synthesis. A recent study has shown that treatment with exogenous anti-erythropoietin (anti-EPO) antibodies (Ab) of infected mice gives protection against malaria infection, suggesting an important role for anti-EPO Ab in malaria. The objective of the study was to evaluate anti-EPO antibody levels in anaemic condition of different strains of semi-immune mice with malaria.
Semi-immune status was attained in four mice strains (Balb/c, B6, CBA and NZW) by repeated infections with 10⁴Plasmodium berghei ANKA, and treatment with chloroquine/pyrimethamine. ELISA was used to measure anti-EPO Ab, transferrin and EPO while inflammatory cytokines measurement was done using bead-based multiplex assay kit.
The mean anti-EPO Ab levels in the mice strains [Optical Density (OD) values at 450 nm: Balb/c (2.1); B6 (1.3); CBA (1.4) and NZW (1.7)] differed (p = 0.045), and were significantly higher when compared with uninfected controls, p < 0.0001, and mean anti-EPO Ab levels in the mice strains at recovery [OD values at 450 nm: Balb/c (1.8); B6 (1.1); CBA (1.5) and NZW (1.0) also differed (p = 0.0004). Interestingly, EPO levels were significantly high in NZW and low in Balb/c mice (p < 0.05), with those of B6 and CBA of intermediary values. Again, NZW were highly parasitaemic (20.7%) and the other strains (Balb/c, B6 and CBA) ranged between 2.2-2.8% (p = 0.015). Anti-EPO Ab correlated positively with extent of Hb loss (r = 0.5861; p = 0.003). Correlation of anti-EPO antibody with EPO was significant only in Balb/c mice (r = -0.83; p = 0.01). Significant levels of IL6 and IFNγ (p < 0.0001), both known to be associated with erythropoiesis suppression were observed in the Balb/c. Transferrin was significantly lower in Balb/c (p < 0.0001) when compared with the other mice strains (B6, CBA and NZW).
This is the first ever report in estimating endogenous anti-EPO antibodies in malaria anaemia. The data presented here suggest that anti-EPO Ab is produced at infection and is associated with Hb loss. Host factors appear to influence anti-EPO antibody levels in the different strains of mice.
疟疾性贫血仍然是一个主要的公共卫生问题，其发病机制仍不清楚。有趣的是，尽管内源性促红细胞生成素（EPO）合成充足，但在流行地区的半免疫个体中，贫血的进展与相对较低的寄生虫血症和一些死亡率有关。最近的一项研究表明，用感染小鼠的外源性抗 EPO（抗-EPO）抗体（Ab）治疗可预防疟疾感染，这表明抗 EPO Ab 在疟疾中具有重要作用。本研究的目的是评估不同株半免疫感染疟原虫小鼠贫血状态下的抗 EPO 抗体水平。
通过重复感染 10⁴ 伯氏疟原虫 ANKA 和氯喹/乙嘧啶，使 4 种小鼠品系（Balb/c、B6、CBA 和 NZW）获得半免疫状态，并进行治疗。使用酶联免疫吸附试验（ELISA）测量抗 EPO Ab、转铁蛋白和 EPO，同时使用基于珠子的多重检测试剂盒测量炎症细胞因子。
小鼠品系的平均抗 EPO Ab 水平[450nm 处的光密度（OD）值：Balb/c（2.1）；B6（1.3）；CBA（1.4）和 NZW（1.7）]不同（p=0.045），与未感染对照组相比，差异有统计学意义（p<0.0001），恢复时的平均抗 EPO Ab 水平[450nm 处的 OD 值：Balb/c（1.8）；B6（1.1）；CBA（1.5）和 NZW（1.0）]也不同（p=0.0004）。有趣的是，NZW 中的 EPO 水平显著升高，而 Balb/c 中的 EPO 水平显著降低（p<0.05），B6 和 CBA 的 EPO 水平处于中间值。同样，NZW 的寄生虫血症水平很高（20.7%），而其他品系（Balb/c、B6 和 CBA）的寄生虫血症水平在 2.2-2.8%之间（p=0.015）。抗 EPO Ab 与 Hb 丢失程度呈正相关（r=0.5861；p=0.003）。仅在 Balb/c 小鼠中，抗 EPO 抗体与 EPO 的相关性具有统计学意义（r=-0.83；p=0.01）。在 Balb/c 中观察到显著水平的 IL6 和 IFNγ（p<0.0001），这两种细胞因子都与红细胞生成抑制有关。与其他小鼠品系（B6、CBA 和 NZW）相比，转铁蛋白在 Balb/c 中显著降低（p<0.0001）。
这是首次在疟疾性贫血中估计内源性抗 EPO 抗体。这里提供的数据表明，抗 EPO Ab 在感染时产生，并与 Hb 丢失有关。宿主因素似乎会影响不同小鼠品系的抗 EPO Ab 水平。
