斯坦福研究表明:人体内超99%的微生物都未曾被科学家发现 [美国媒体]

Stanford study indicates that more than 99 percent of the microbes inside us are unknown to science

斯坦福研究表明人体内超99%的微生物都未曾被科学家发现

A survey of DNA fragments circulating in the blood suggests the microbes living within us are vastly more diverse than previously known. In fact, 99 percent of that DNA has never been seen before.

一项关于人体血液中所存在的DNA碎片的研究表明：我们体内的微生物多样性比之前所知的要多得多。事实上，这些DNA中的99%之前从没被发现过.



BY NATHAN COLLINS

A new survey of DNA fragments circulating in human blood suggests our bodies contain vastly more diverse microbes than anyone previously understood. What’s more, the overwhelming majority of those microbes have never been seen before, let alone classified and named, Stanford researchers?report?August 22 in the?Proceedings of the National Academy of Sciences.

一项关于人体血液中所存在的DNA碎片的研究表明：我们体内的微生物多样性比之前所知的要多得多。斯坦福大学研究者在8月22日的《美国科学院学报》上发布了这一研究结果，称这些海量的微生物此前从来没被发现过，更别说给它们分类和命名了。

“We found the gamut,” said?Stephen Quake, a professor of bioengineering and applied physics, a member ofStanford Bio-X?and the paper’s senior author. “We found things that are related to things people have seen before, we found things that are divergent, and we found things that are completely novel.”

“我们发现了非常多新的微生物”，生物工程和应用医学的教授，同时也是斯坦福大学Bio-X 研究中心的成员和论文的通讯作者的Stephen Quake说道：“我们发现这些微生物和我们之前见过的有很大的关联，它们大不相同，而且非常新奇。”


  
Searching for rejection

寻找排斥反应

The survey was inspired by a curious observation Quake’s lab made while searching for non-invasive ways to predict whether an organ transplant patient’s immune system would recognize the new organ as foreign and attack it, an event known as rejection. Ordinarily, it takes a tissue biopsy –?meaning a large needle jabbed into one’s side and at least an afternoon in a hospital bed for observation –?to detect rejection.

该研究的灵感来自Quake实验室的一次不寻常的观察，他们在找寻非入侵方式来预测病人免疫系统的反应，比如在进行器官移植时，免疫系统是否可以识别出新器官是外来的移植器官从而攻击它，这个反应也称为排斥反应。一般来说，这需要进行组织活检——意味着巨大的针头要刺进某人身体的一侧，而且某人还需一下午时间留院观察——来发现是否有排斥反应。

The lab members figured there was a better way. In theory, they might be able to detect rejection by taking blood samples and looking at the cell-free DNA – bits and pieces of DNA circulating freely in blood plasma – contained therein. Apart from fragments of a patient’s DNA, those samples would contain fragments of the organ donor’s DNA as well as a comprehensive view of the collection of bacteria, viruses and other microbes that make up a person’s microbiome.

实验室的成员发现了更好的办法。理论上，他们可以通过采集血样观察血液中游离的DNA和血浆中游离的DNA片段来发现排斥反应。血样中除了患者的DNA片段，也包含了器官捐献者的DNA片段，这构成了一个人的微生物菌群，包括细菌、病毒和其他微生物，也给我们提供了一个观察的全面视角。

Over the course of several studies, the first of which was published in 2013, Quake, postdoctoral fellow Iwijn De Vlaminck, and others collected samples from 156 heart, lung and bone marrow transplant recipients, along with 32 pregnant women. (Pregnancy, like immunosuppressant drugs taken by transplant patients, also changes the immune system, albeit in ways both more complicated and less well understood.)

在过去的一些研究中，Quake的实验室在2013年发布了Iwijn De Vlaminck博士后的第一篇研究。其中的156份样本分别来自心脏、肺、骨髓移植的接收者，以及32名孕妇。（怀孕也能改变免疫系统，就像移植患者服用的免疫抑制剂一样，尽管它更为复杂也更难理解。）

The results of those earlier studies suggested there were identifiable changes to the microbiomes of people with compromised immune systems and that positive tests for the organ donor’s DNA were a good sign of rejection.

这些早期的研究结果表明，人们缺乏抵抗力的免疫系统对微生物菌群有明显的反应，并且人们对器官捐献者DNA的阳性测试，也是排斥反应存在的很好证明。

Something weirder

奇怪的东西

But there was something else, too –?something weirder. Of all the non-human DNA fragments the team gathered, 99 percent of them failed to match anything in existing genetic databases the researchers examined.

但仍然存在着一些其他东西——一些更奇怪的东西。团队找到的这些东西都不属于人类的DNA片段，这些东西中的99%和目前研究者发现的基因数据库里的基因都不匹配。

With that in mind, Mark Kowarsky, a graduate student in Quake’s lab and the paper’s first author, set about characterizing all of that mystery DNA.

Quake实验室的研究生和论文的第一作者Mark Kowarsky在考虑了这些问题之后，开始着手描述这些神秘的DNA。

The “vast majority” of it belonged to a phylum called proteobacteria, which includes, among many other species, pathogens such as?E. coli?and?Salmonella. Previously unidentified viruses in the torque teno family, generally not associated with disease but often found in immunocompromised patients, made up the largest group of viruses.

这些微生物中的“绝大多数”属于变形菌门，该门包括了很多其他菌种，比如大肠杆菌和沙门氏菌这样的病原体。早前在细环病毒科中未被识别出的病毒，现在则构成了最大的病毒群，它们一般和疾病关联不大，却经常在免疫力低下的患者身上发现。

“We’ve doubled the number of known viruses in that family through this work,” Quake said. Perhaps more important, they’ve found an entirely new group of torque teno viruses. Among the known torque teno viruses, one group infects humans and another infects animals, but many of the ones the researchers found didn’t fit in either group. “We’ve now found a whole new class of human-infecting ones that are closer to the animal class than to the previously known human ones, so quite divergent on the evolutionary scale,” he said.

Quake称：“通过这项研究，我们所发现的属于该科的病毒种类增加了一倍”。更重要的是，他们发现了一组全新的细环病毒。在已知的细环病毒中，其中一类可以感染人类，另一类则会感染动物，但是研究人员发现的新细环病毒却不属于上面任何一类。他说：“我们现在发现了一类全新的感染人类病毒，它们更接近于感染动物的那一类，而不是之前所知的感染人类的那一类，它们在进化范围上非常离散”。

An unsurprising surprise?

不是惊喜的惊喜？

“I’d say it’s not that baffling in some respects because the lens that people examined the microbial universe was one that was very biased,” Quake said, in the sense that narrow studies often miss the bigger picture. For one thing, researchers tend to go deep in the microbiome in only one part of the body, such as the gut or skin, at a time. Blood samples, in contrast, “go deeply everywhere at the same time.”

Quake说：“从某方面来说，这并不难理解，因为人们看微生物世界的眼光通常带有偏见”，所以狭隘的研究也容易忽视更长远的图景。一方面，研究者只从身体的一部分去深入了解微生物，比如肠道或皮肤。与之相反的是血液样本，研究者可以通过它去深入了解人体的各个部分。

For another, researchers often focus their attention on just a few interesting microbes, “and people just don’t look at what the remaining things are,” Kowarsky said. “There probably are some interesting, novel things there, but it’s not relevant to the experiment people want to do at that time.”

另一方面，研究者经常把注意力集中在少数感兴趣的微生物上，“人们也懒得看看剩下其他的微生物是什么”。 Kowarsky说：“存在着一些有趣、新奇的东西，不过它们却与研究者们愿意在当下进行的实验不相关。”

It was by looking at blood samples in an unbiased way, Quake said, that led to the new results and a new appreciation of just how diverse the human microbiome is.

Quake说，研究血液样本是用一种公平的方式，这导致了新的结果的出现以及对人体微生物多样性的一种新的评估。

Going forward, Quake said, the lab hopes to study the microbiomes of other organisms to see what’s there. “There’s all kinds of viruses that jump from other species into humans, a sort of spillover effect, and one of the dreams here is to ‘’discover new viruses that might ultimately become human pandemics.” Understanding what those viruses are could help doctors manage and track outbreaks, he said.

今后，实验室希望能研究其他生物体中的微生物。Quake说：“很多的病毒都是通过其他物种传染给人类的，这是一种溢出效应，我们的目标之一就是找到最终导致人类大流行病的新病毒” ，了解这些病毒有助于医生处理和跟踪疫情。

“What this does is it arms infectious disease doctors with a whole set of new bugs to track and see if they’re associated with disease,” Quake said. “That’s going to be a whole other chapter of work for people to do.”

Quake说道：“它的作用是给传染病医生提供了一系列的窃听器，来进行跟踪，并发现它们是否与疾病有关，而这又是人们要做的另一项工作了”。