为什么在农场长大对你的免疫系统有好处

Health experts have known for years that kids who grow up on a farm have fewer incidences of allergies and asthma than city kids, but continued research is helping them better understand the connection between the immune system and microbes only found in that setting.

健康专家多年来就知道，在农场长大的孩子比在城市长大的孩子过敏和哮喘的发生率更低，但持续的研究正在帮助他们更好地理解免疫系统和微生物之间的联系，而这种联系只有在农村才能找到。

Researchers may have figured out what it is about life on a farm that protects kids from allergies and boosts their immune systems. (Photo: Andy Dean Photography/Shutterstock)

The Amish children all had a large proportion of neutrophils, white blood cells that are part of the so-called innate immune system. The Amish kids' neutrophils "were newly emerged from their bone marrow, evidence of a continual low-grade reaction to microbial invaders," the Times reported. In contrast, the Hutterite kids had "old" neutrophils, and researchers found their blood was full of another type of immune cell, eosinophils, which provoke allergic reactions.

阿米什儿童都有很大比例的中性粒细胞，即白细胞，是所谓的先天免疫系统的一部分。据《泰晤士报》报道，阿米什儿童的中性粒细胞“是从他们的骨髓中新出现的，这证明他们对微生物入侵者的反应持续低下”。相比之下，赫特人的孩子有“老”中性粒细胞，研究人员发现他们的血液中充满了另一种类型的免疫细胞，嗜酸性粒细胞，会引发过敏反应。

They made this connection with the help of young pigs. They essentially did a fecal transplant, placing the Amish babies' poop into the intestines of newborn pigs, essentially testing the hygiene hypothesis with the help of pigs, which have an immune system more similar to humans. The results were an increased development of immune cells, particularly lymphoid and myeloid cells in the intestines.

他们在小猪的帮助下建立了这种联系。他们进行了粪便移植，将阿米什婴儿的粪便植入新生猪的肠道，在猪的帮助下测试卫生假说，猪的免疫系统与人类更相似。结果是增强了免疫细胞的发育，尤其是肠道内的淋巴细胞和髓细胞。

The research was published in Frontiers in Immunology.

这项研究发表在《免疫学前沿》杂志上。

The Amish babies involved in the experiment all lived in rural homes with farm animals. (Photo: Elizaveta Galitckaia/Shutterstock)

According to the Centers for Disease Control and Prevention, 6.8 million children in the U.S. have been diagnosed with asthma and about 17 percent of kids suffer from respiratory allergies to things like pollen and mold. But over the last few decades, health care providers have observed that kids who grow up on farms are much less likely to be affected by these conditions than their urban-dwelling peers.

根据美国疾病控制和预防中心的数据，美国有680万儿童被诊断出患有哮喘，约17%的儿童对花粉和霉菌等呼吸道过敏。但在过去几十年里，卫生保健提供者发现，在农场长大的孩子比在城市生活的同龄人更不容易受到这些条件的影响。

What's more, researchers found that when the mice were exposed to farm dust, they produced a protein in their lungs called A20. When they deactivated this protein, these mice had a normal allergic response to the dust mites.

更重要的是，研究人员发现，当老鼠暴露在农场的灰尘中时，它们的肺部会产生一种叫做A20的蛋白质。当他们停用这种蛋白质时，这些老鼠对尘螨有正常的过敏反应。

Researchers confirmed these findings with human surveys where they found that people who suffer from allergies and asthma have a deficiency in A20 protein. Finally, they took a look at the kids growing up on farms who develop asthma and allergies. You guessed it — those kids have a mutation in their A20 gene that impedes the production of A20 protein.

研究人员通过人类调查证实了这些发现，他们发现患有过敏和哮喘的人缺乏A20蛋白。最后，他们对在农场长大的孩子进行了调查，这些孩子患有哮喘和过敏症。你猜对了——这些孩子的A20基因发生了突变，阻碍了A20蛋白的产生。

Researchers were especially interested in dust on dairy farms. (Photo: Ewa Studio/Shutterstock)

By narrowing down the mechanisms behind certain asthmatic and allergic reactions, these researchers may have opened the door for the development of vaccines and treatment options for people who suffer from these conditions.

通过缩小某些哮喘和过敏反应背后的机制，这些研究人员可能为开发针对这些疾病患者的疫苗和治疗方案打开了大门。