Research press release


Nature Metabolism

Metabolism: Bacteria in human internal organs characterized

ヒトの内臓に細菌DNAがどのように分布するかを詳細に解析した報告が、Nature Metabolism に掲載される。


今回Andre Maretteたちは、減量手術を受けた患者40人から血液、肝臓、3種類の脂肪組織(皮下脂肪、腸間膜脂肪、大網脂肪)のサンプルを集めて、微生物DNAを解析した。すると、各組織サンプルにみられる細菌の種類や細菌DNAの量に、特異的な違いがあることが明らかになった。また、2型糖尿病患者20人の脂肪組織には、特有の微生物DNAシグネチャーがあることが分かった。さらに、組織サンプル中から、腸内細菌由来のDNAだけでなく、土壌中、水中に広く見られる細菌由来のDNAも検出された。これらの知見は、ヒトの内臓が外来の遺伝物質に日常的に曝されていることを示唆している。


A detailed analysis of how bacterial DNA is distributed among human internal organs is described in a paper published in Nature Metabolism.

Bacteria can be found all over the body and inside the gut. Although internal organs are typically sterile, in diseases - such as obesity - fragments of bacteria can move from the gut into the blood and trigger inflammatory responses. However, a detailed understanding of the origin of such bacterial fragments and their distribution among tissues has been lacking, in part because of the difficulty in obtaining clean tissue samples.

Andre Marette and colleagues collected blood, liver and three types of fat tissue samples (subcutaneous, mesenteric and omental fat) from 40 patients as they underwent weight-loss surgery. The authors analysed microbial DNA found within the samples and uncovered specific differences in the type of bacteria and amount of bacterial DNA in each tissue sample. The authors also identified a unique microbial DNA signature in the fat tissue of 20 patients with type 2 diabetes. Furthermore, in the tissue samples, they detected DNA not only from gut bacteria but also from bacteria commonly found in soil or water. This finding suggests that internal organs may be regularly exposed to foreign genetic material.

This study demonstrates how bacteria or bacterial DNA is distributed within the human body outside the gut. Further research is needed to determine whether the bacteria in the samples were alive, and therefore able to form an internal tissue microbiome, or whether tissues contained fragments of bacterial DNA. Future work could help to clarify how microbial DNA reached the tissues - whether it involved transportation out of the gut or occurred with the help of immune cells.

doi: 10.1038/s42255-020-0178-9

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