首页 - 译文学习区 登录 注册

实验鼠是不是太干净了

  • 11635阅读
  • 0
  • 0评论
译者:arb
发布:2017-04-08 19:25:29 挑错

Dirty secrets

肮脏的秘密

Are laboratory mice too clean?

实验鼠是不是太干净了

The hygiene hypothesis may also apply to animal experiments

这项卫生假说可能也适用动物试验

Mar 23rd 2017

THE hygiene hypothesis posits that certain diseases—notably asthma, eczema and type-1 diabetes—which are becoming more common than they once were, are caused in part by modern environments being too clean. The diseases in question result from misfunctions of the immune system. The hygiene hypothesis suggests such misfunctions are the result of children’s immune systems being unable to learn, by appropriate exposure to viruses, bacteria, fungi and parasitic worms, how to respond properly.

根据这种卫生假说,有些疾病,特别是哮喘、湿疹和I型糖尿病等这些比以往更为常见的疾病的发病原因,在某种程度上是因为现在人们的生存环境太过干净,免疫系统出现问题导致。这项假说认为,免疫系统之所以出现问题,是因为幼儿不能与病毒、细菌、真菌和寄生虫等适当接触,当他们的免疫系统在遇到这类东西侵袭时不知如何恰当应对。

 If modern human homes are unnaturally clean, though, they are as nothing compared with the facilities in which experimental mice are housed. Those are practically sterile. That led Lili Tao and Tiffany Reese, two researchers at the University of Texas Southwestern Medical Centre, in Dallas, to wonder if such mice would display extreme versions of the predictions of the hygiene hypothesis.

如果说现代人的家里太过干净,但与实验室老鼠居住环境比起来,实在算不了什么,后者实际上是一种无菌状况,达拉斯得克萨斯大学西南医学中心的两位研究人员陶丽丽和蒂法尼·里斯因此设想,在这种环境下的老鼠是否可以呈现出前述卫生假设的极端版本。

This would matter, because mice are often used in medical experiments on the assumption that their reactions are similar enough to those of human beings for them to act as stand-ins. Conversely, laboratories’ spotlessness might also mean mice are sometimes too healthy to act as useful models for disease. As they explain in Trends in Immunology, Dr Tao and Dr Reese therefore combed the scientific literature to look for both phenomena.

这很重要,医学试验中,常用老鼠代替人,因为老鼠对实验的反应与人类非常相似。相反,实验室的无尘环境可能也意味着老鼠有时过于健康不能胜任疾病的有效替身。就像他们在《免役学趋势》中所解释的那样,陶和里斯两位博士因此搜集科学文献寻找两种现象。

A nice example which the two researchers found of the hygiene hypothesis at work is that stopping laboratory mice being infected with murine cytomegalovirus, which is common in their wild kin, damages their immune response to a host of other pathogens, bacterial as well as viral. Mice so infected will survive subsequent exposure to otherwise-lethal doses of Listeria monocytogenes (a soil- and food-borne bacterium) and Yersinia pestis (the bacterium that causes plague). These mice are also better able than others to handle retrovirus infections. And the effects on them of multiple sclerosis—an illness the underlying cause of which is suspected to be an inappropriate immune response—are reduced.

两位研究者发现这种卫生假设发生作用的一个很好的事例,野生老鼠常会受到巨细胞病毒的感染,现在不再让实验鼠受到这种感染,这损害了实验鼠对其他大量病原体、细菌及病毒的免疫反应。而那些感染了巨细胞病毒老鼠即便服用本可致命的李斯特菌(一种土壤和食物生出的细菌)和鼠疫杆菌(一种可引起瘟疫的细菌),也能大难不死。这些老鼠比其它老鼠能更好地应对逆转氯酶病毒的感染。多发性硬化症对它们的影响也降低了,人们怀疑这种病的主要病因是不适当的免疫反应。

On the other hand, early infection with a different common pathogen, Yersinia pseudotuberculosis, affects murine immune systems in a way that leaves mice more open to subsequent attack, rather than less so—the reverse of the hygiene hypothesis. By unknown means, such infection permanently diverts immune cells called dendritic cells from their normal homes in lymph nodes and to the wall of the gut, where they cause sustained inflammation. Similarly, early exposure to certain herpes viruses, also common in the wild, can result in latent infections that cause no perceptible symptoms unless a kind of parasitic worm called a helminth also turns up. That reactivates the infection. Anyone attempting to mimic human worm infestations using mice should be aware of this.

但是,如果一开始受到过一种叫做假结核耶尔森菌的常见病原体的感染,受到影响的免疫系统会让老鼠以后得病更多,而不是更少,这与前面所说的卫生假说相悖。这种感染通过一种尚不可知的方式将树突免疫细胞从淋巴节它们正常的位置永久性地转移到肠壁,并引发那里持续性的炎症。与此相类似,如果一开始接触也是在野生状态下比较常见的疱疹菌,可能也会受到感染,没有明显的症状,除非出现一种叫做蛔虫的寄生虫。这又会重新引起感染,使用老鼠模拟人类寄生虫感染的人应该知道这些。

Those studying vaccines, too, need to be aware of the confounding effects of hygiene. Laboratory-bred mice have fewer memory T-cells than those brought up in the outside world. Memory T-cells are the parts of the immune-system that remember prior infections, thus enabling a rapid response if the agent which caused that infection is encountered again. Generating such T-cell memories is a vaccine’s job.

疫苗研究者也需要了解卫生的复杂影响。实验室长大的老鼠比外面的老鼠拥有的记忆T细胞更少,记忆T细胞是免疫系统的组成部分,它能够记住以前受过的感染,如果遇到以前的感染因子就能作出快速反应。制造这样的记忆T细胞是疫苗要做的事情。

Moreover, an experiment done by Dr Reese herself showed that exposing young mice to human pathogens, such as herpes and influenza viruses, altered their subsequent responses to vaccines for other diseases. Animals so exposed produce fewer antibodies against a yellow-fever vaccine than do pathogen-free mice.

然而,里斯博士本人做的一个实验表明,将幼鼠放在疱疹或流感病毒等人类病原体的环境下,改变他们对其他疾病疫苗的后续反应。这样的老鼠比未接触病原体的老鼠产生应对黄肺疫苗的抗体更少。

As is often the case with these sorts of preliminary literature reviews, the outcome is a grab-bag of intriguing results, rather than a coherent hypothesis or prescription for action. But the evidence Dr Tao and Dr Reese have assembled suggests there is something going on here that needs investigating. It seems to be a classic example of the law of unintended consequences. The point of raising mice hygienically is to eliminate as many uncontrolled factors from an experiment as possible. That hygiene itself might be such a factor has not, until now, crossed people’s minds.

进行各种初步文献综述是常有的事情,最后得出的是一堆有趣的结果,而非前后一致的假设和行动处方。但陶和里斯两位博士收集到的证据表明,这里发生的事情需要进一步调查研究。这似乎是意外后果规则的经典案例。在洁净条件下养鼠的目的就是要消除实验中尽可能多的不可控因素。岂不知洁净本身可能就是这样一个因素,而且直到现在,这也没引起人们的注意。

How to respond is unclear. Running trials twice, with “dirty” and “clean” mice, could be one approach. Another might be to agree on a set of bugs to which early exposure is permitted. What this work does show, though, is that in research, cleanliness is not necessarily next to godliness.

怎样应对还不清楚。分别使用“干净”的和“肮脏”的老鼠进行两次实验,可能是一个方法。另外一个可行的办法就是让它们一直和小虫子为伍。但这些工作不折不扣地说明,做科学研究,洁净不一定就是心诚。


相关译文来自无觅插件
共计0条评论
×提示

您已经赞过此文了。

确定