英中——科学家终于知道为什么人们在冬天更容易得感冒和流感

Scientists finally know why people get more colds and flu in winter科学家终于知道为什么人们在冬天更容易得感冒和流感

A chill is in the air, and you all know what that means — it’s time for cold and flu season, when it seems everyone you know is suddenly sneezing, sniffling or worse. It’s almost as if those pesky cold and flu germs whirl in with the first blast of winter weather.空气中弥漫着寒意，你们都知道这意味着什么——现在是感冒和流感的季节，似乎你认识的每个人都突然打喷嚏、流鼻涕或更糟。这就好像那些讨厌的感冒和流感病菌随着冬天的第一缕寒风而来。

As respiratory viruses strain US health care systems, Biden administration tells states how it's ready to help随着呼吸道病毒给美国医疗系统带来压力，拜登政府告诉各州如何准备好提供帮助

Yet germs are present year-round — just think back to your last summer cold. So why do people get more colds, flu and now Covid-19 when it’s chilly outside?然而细菌一年四季都存在——回想一下你去年夏天的感冒。那么，为什么当外面很冷的时候，人们会更容易得感冒、流感和现在的新冠呢?

In what researchers are calling a scientific breakthrough, scientists behind a new study may have found the biological reason we get more respiratory illnesses in winter. It turns out the cold air itself damages the immune response occurring in the nose.在一项的新研究中，研究人员宣布取得了科学突破，科学家们在其中可能发现了我们在冬季更易患呼吸道疾病的生物学原因。事实证明，冷空气本身会破坏鼻子中的免疫反应。

“This is the first time that we have a biologic, molecular explanation regarding one factor of our innate immune response that appears to be limited by colder temperatures,” said rhinologist Dr. Zara Patel, a professor of otolaryngology and head and neck surgery at Stanford University School of Medicine in California. She was not involved in the new study.加州斯坦福大学医学院耳鼻喉和头颈外科教授、鼻科医生扎拉·帕特尔说:“这是我们第一次从生物学和分子上解释我们先天免疫反应的一个因素，这个因素似乎受到低温的限制。”她没有参与这项新研究。

In fact, reducing the temperature inside the nose by as little as 9 degrees Fahrenheit (5 degrees Celsius) kills nearly 50% of the billions of virus and bacteria-fighting cells in the nostrils, according to the study published Tuesday in The Journal of Allergy and Clinical Immunology过敏与临床免疫学杂志.事实上，根据周二发表在The Journal of Allergy and Clinical Immunology过敏与临床免疫学杂志上的研究，只要把鼻子里的温度降低9华氏度(5摄氏度)，鼻孔里数十亿抵抗病毒和细菌的细胞中的近50%就会死亡。

“Cold air is associated with increased viral infection because you’ve essentially lost half of your immunity just by that small drop in temperature,” said rhinologist Dr. Benjamin Bleier, director of otolaryngology at Massachusetts Eye and Ear and an associate professor at Harvard Medical School in Boston.麻省眼耳医院鼻喉科主任、波士顿哈佛医学院副教授、鼻科医生本杰明·布莱尔说:“冷空气与病毒感染增加有关，因为仅仅是温度的小幅下降，你就已经失去了一半的免疫力。”

“it’s important to remember that these are in vitro studies, meaning that although it is using human tissue in the lab to study this immune response, it is not a study being carried out inside someone’s actual nose,” Patel said in an email. “Often the findings of in vitro studies are confirmed in vivo, but not always.”帕特尔在一封电子邮件中说:“重要的是要记住，这些是体外研究，这意味着尽管它是在实验室中使用人体组织来研究这种免疫反应，但它并不是在人的真实鼻子里进行的研究。”“体外研究的结果通常在体内得到证实，但并不总是如此。”

A hornet’s nest马蜂窝

To understand why this occurs, Bleier and his team and coauthor Mansoor Amiji, who chairs the department of pharmaceutical sciences at Northeastern University in Boston, went on a scientific detective hunt.为了理解为什么会发生这种情况，布莱尔和他的团队以及合著者Mansoor Amiji(波士顿东北大学制药科学系主任)进行了一次科学侦探搜索。

Here's how to know when your child is too sick for school以下是如何知道你的孩子什么时候病得不能上学的方法

A respiratory virus or bacteria invades the nose, the main point of entry into the body. Immediately, the front of the nose detects the germ, well before the back of the nose is aware of the intruder, the team discovered.呼吸道病毒或细菌侵入鼻子，这是进入人体的主要入口。研究小组发现，在鼻子后部意识到细菌之前，鼻子的前部立即检测到这些入侵者。

At that point, cells lining the nose immediately begin creating billions of simple copies of themselves called extracellular vesicles, or EV’s.此时，鼻腔内的细胞立即开始产生数十亿个简单的自身副本，称为细胞外囊泡(EV)。

“EV’s can’t divide like cells can, but they are like little mini versions of cells specifically designed to go and kill these viruses,” Bleier said. “EV’s act as decoys, so now when you inhale a virus, the virus sticks to these decoys instead of sticking to the cells.”“EV不能像细胞那样分裂，但它们就像迷你版本的细胞，专门用来杀死这些病毒，”布莱尔说。“EV就像诱饵一样，所以现在当你吸入病毒时，病毒会粘附在这些诱饵上，而不是粘附在细胞上。”

Those “Mini Me’s” are then expelled by the cells into nasal mucus (yes, snot), where they stop invading germs before they can get to their destinations and multiply.然后，这些“迷你我”被细胞排出到鼻腔粘液(是的，鼻涕)中，在细菌到达目的地并繁殖之前，它们就停止了入侵。

“This is one of, if not the only part of the immune system that leaves your body to go fight the bacteria and viruses before they actually get into your body,” Bleier said.“这是免疫系统的一部分，如果不是唯一的一部分，它会让你的身体在细菌和病毒真正进入你的身体之前去对抗它们，”布莱尔说。

How to use food to boost your immune system如何用食物增强你的免疫系统

Once created and dispersed out into nasal secretions, the billions of EV’s then start to swarm the marauding germs, Bleier said.布莱尔说，一旦产生并分散到鼻腔分泌物中，数十亿个EV就会开始蜂拥而至，攻击细菌。

“It’s like if you kick a hornet’s nest, what happens? You might see a few hornets flying around, but when you kick it, all of them all fly out of the nest to attack before that animal can get into the nest itself,” he said. “That’s the way the body mops up these inhaled viruses so they can never get into the cell in the first place.”“这就像你捅马蜂窝，会发生什么? 你可能会看到几只黄蜂飞来飞去，但当你捅它时，在入侵动物进入巢穴之前，所有的黄蜂都飞出巢穴进行攻击。”“这就是身体清除这些吸入病毒的方式，这样它们就永远无法进入细胞。”