Polymorphic variants within the human natural resistance-associated macrophage protein-1 (NRAMP1, also known as SLC11A1) gene have been shown to impact on susceptibility to tuberculosis in different human populations. In the mouse, Nramp1 is expressed at the macrophage phagosomal membrane and its activity can be assayed by the relative acquisition of mannose 6-phosphate receptor (M6PR) in Salmonella-containing vacuoles. Based on this M6PR recruitment assay, we have now developed an assay in primary human macrophages to test the function of human NRAMP1 gene variants. First, we established that M6PR acquisition was significantly higher (P = 0.002) in human U-937 monocytic cell lines transfected with NRAMP1 as compared to untransfected U-937 cells. Second, the M6PR assay was shown to be highly reproducible for NRAMP1 activity in monocyte-derived macrophages (MDM) from healthy volunteers. Finally, the assay was investigated in MDM from pediatric tuberculosis patients and significantly lower NRAMP1 activity was detected in MDM from individuals homozygous for the NRAMP1-274 high-risk allele (CC genotype) in comparison to heterozygous individuals (CT genotype; P=0.013). The present study describes both an assay for human NRAMP1 functional activity and concomitant evidence for reduced NRAMP1 function in the common genetic variant shown to be associated with tuberculosis susceptibility in pediatric patients.

中文翻译：

---

人NRAMP1（SLC11A1）等位基因的体外功能活性降低，易患小儿肺结核疾病。

已显示人类天然抗性相关巨噬细胞蛋白1（NRAMP1，也称为SLC11A1）基因内的多态性变体会影响不同人群中结核病的易感性。在小鼠中，Nramp1在巨噬细胞吞噬体膜上表达，其活性可以通过在含沙门氏菌的液泡中相对获得甘露糖6磷酸受体（M6PR）来测定。基于此M6PR募集试验，我们现在已经开发了一种在主要人类巨噬细胞中的试验，以测试人类NRAMP1基因变异的功能。首先，我们确定，与未转染的U-937细胞相比，在用NRAMP1转染的人U-937单核细胞系中M6PR的获得显着更高（P = 0.002）。第二，M6PR分析显示出健康志愿者单核细胞衍生巨噬细胞（MDM）中NRAMP1活性的高度可重复性。最后，在小儿结核病患者的MDM中研究了该测定法，与杂合子个体（CT基因型； P = 0.013）相比，在纯合子中NRAMP1-274高风险等位基因（CC基因型）的个体的MDM中检测到的NRAMP1活性明显降低。 。本研究描述了一种针对人类NRAMP1功能活性的测定方法，并同时证明了在与儿科患者的结核病易感性相关的常见遗传变异中NRAMP1功能降低的证据。在小儿结核病患者的MDM中研究了该检测方法，与杂合子个体（CT基因型; P = 0.013）相比，NRAMP1-274高风险等位基因（CC基因型）纯合子个体在MDM中检测到的NRAMP1活性显着降低。本研究描述了一种针对人类NRAMP1功能活性的测定方法，并同时证明了在与儿科患者的结核病易感性相关的常见遗传变异中NRAMP1功能降低的证据。在小儿结核病患者的MDM中研究了该检测方法，与杂合子个体（CT基因型; P = 0.013）相比，NRAMP1-274高风险等位基因（CC基因型）纯合子个体在MDM中检测到的NRAMP1活性显着降低。本研究描述了一种针对人类NRAMP1功能活性的测定方法，并同时证明了在与儿科患者结核病易感性相关的常见基因变异中NRAMP1功能降低的证据。