Child undernutrition is a global health issue that is associated with poor sanitation and an altered intestinal microbiota. Immunoglobulin (Ig) A mediates host-microbial homeostasis in the intestine, and acutely undernourished children have been shown to have altered IgA recognition of the fecal microbiota. We sought to determine whether chronic undernutrition (stunting) or intestinal inflammation were associated with antibody recognition of the microbiota using two geographically distinct populations from the Afribiota project. Fecal bacteria from 200 children between 2 and 5 years old in Antananarivo, Madagascar, and Bangui, Central African Republic (CAR), were sorted into IgA-positive (IgA+) and IgA-negative (IgA−) populations by flow cytometry and subsequently characterized by 16S rRNA gene sequencing to determine IgA-bacterial targeting. We additionally measured IgG+ fecal bacteria by flow cytometry in a subset of 75 children. Stunted children (height-for-age z-score ≤ −2) had a greater proportion of IgA+ bacteria in the fecal microbiota compared to non-stunted controls. This trend was consistent in both countries, despite the higher overall IgA-targeting of the microbiota in Madagascar, but lost significance in each country individually. Two of the most highly IgA-recognized bacteria regardless of nutritional status were Campylobacter (in CAR) and Haemophilus (in both countries), both of which were previously shown to be more abundant in stunted children; however, there was no association between IgA-targeting of these bacteria and either stunting or inflammatory markers. IgG-bound intestinal bacteria were rare in both stunted and non-stunted children, similar to levels observed in healthy populations. Undernourished children carry a high load of intestinal pathogens and pathobionts. Our data suggest that stunted children have a greater proportion of IgA-recognized fecal bacteria. We moreover identify two putative pathobionts, Haemophilus and Campylobacter, that are broadly targeted by intestinal IgA. This study furthers our understanding of host-microbiota interactions in undernutrition and identifies immune-recognized microbes for future study.

中文翻译：

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发育迟缓和非惊呆儿童粪便细菌的免疫球蛋白识别：Afribiota研究的发现。

儿童营养不良是一个全球性卫生问题，与卫生条件差和肠道菌群改变有关。免疫球蛋白（Ig）A介导肠道内微生物的体内稳态，并且已显示营养不良的儿童改变了粪便微生物群对IgA的识别。我们试图使用来自非洲裔生物群计划的两个地理上不同的种群来确定慢性营养不良（击昏）或肠道炎症是否与微生物群的抗体识别相关。来自马达加斯加的塔那那利佛和中非共和国班吉（CAR）的200名2至5岁儿童的粪便细菌通过流式细胞术分类为IgA阳性（IgA +）和IgA阴性（IgA-）人群，并随后进行了表征通过16S rRNA基因测序确定IgA-细菌靶向性。我们还通过流式细胞术在75名儿童的子集中测量了IgG +粪便细菌。与未受惊的对照组相比，发育不良的儿童（年龄高度z分数≤-2）在粪便微生物群中具有更大比例的IgA +细菌。尽管马达加斯加的微生物群对IgA的总体靶向水平较高，但两国的趋势都是一致的，但在每个国家中单独失去了意义。无论营养状况如何，IgA识别度最高的细菌中的两个是弯曲杆菌（在CAR中）和嗜血杆菌（在两个国家中），这两个细菌以前在发育不良的儿童中都表现出更高的含量。但是，这些细菌的IgA靶向与发育迟缓或炎症标记之间没有关联。在发育不良和未受惊吓的儿童中，IgG结合的肠道细菌均很少见，与健康人群中观察到的水平相似。营养不良的儿童携带大量肠道病原体和致病菌。我们的数据表明，发育不良的儿童中IgA识别的粪便细菌比例更高。此外，我们确定了肠IgA广泛靶向的两种假定的病原体，嗜血杆菌和弯曲杆菌。这项研究进一步增进了我们对营养不足中宿主-微生物群相互作用的理解，并确定了免疫识别的微生物以供将来研究。