Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
PLoS One. 2012;7(2):e31647. doi: 10.1371/journal.pone.0031647. Epub 2012 Feb 14.
Regulatory T cells (Tregs) suppress host immune responses and participate in immune homeostasis. In co-infection, secondary parasite infections may disrupt the immunologic responses induced by a pre-existing parasitic infection. We previously demonstrated that schistosomiasis-positive (SP) Malian children, aged 4-8 years, are protected against the acquisition of malaria compared to matched schistosomiasis-negative (SN) children.
To determine if Tregs contribute to this protection, we performed immunologic and Treg depletion in vitro studies using PBMC acquired from children with and without S. haematobium infection followed longitudinally for the acquisition of malaria. Levels of Tregs were lower in children with dual infections compared to children with malaria alone (0.49 versus 1.37%, respectively, P = 0.004) but were similar months later, during a period with negligible malaria transmission. The increased levels of Tregs in SN subjects were associated with suppressed serum Th1 cytokine levels, as well as elevated parasitemia compared to co-infected counterparts.
These results suggest that lower levels of Tregs in helminth-infected children correlate with altered circulating cytokine and parasitologic results which may play a partial role in mediating protection against falciparum malaria.
调节性 T 细胞（Tregs）抑制宿主免疫反应并参与免疫稳态。在混合感染中，二次寄生虫感染可能会破坏由先前存在的寄生虫感染引起的免疫反应。我们之前的研究表明，与匹配的无血吸虫感染的儿童相比，年龄在 4-8 岁的阳性血吸虫病（SP）马里儿童对疟疾的获得具有保护作用。
为了确定 Tregs 是否有助于这种保护作用，我们使用从有和没有曼氏血吸虫感染的儿童获得的 PBMC 进行了体外免疫和 Treg 耗竭研究，并对疟疾的获得进行了纵向研究。与仅患有疟疾的儿童相比，双重感染的儿童中 Tregs 的水平较低（分别为 0.49%和 1.37%，P = 0.004），但在数月后，在疟疾传播可忽略不计的时期，Tregs 的水平相似。SN 受试者中 Tregs 水平的升高与血清 Th1 细胞因子水平受到抑制以及与感染对照相比寄生虫血症升高有关。
这些结果表明，感染蠕虫的儿童中 Tregs 水平较低与循环细胞因子和寄生虫学结果的改变相关，这可能在介导对恶性疟原虫疟疾的保护中发挥部分作用。
