VOA健康报道2024--Autoimmune Diseases Affect More Women than Men

Autoimmune Diseases Affect More Women than Men

Women are much more likely to get autoimmune diseases than men. New research may finally explain why.

Autoimmune diseases happen when the body's natural defenses, or immune system, attack the body's tissues.

Researchers from Stanford University in California say the reason for this may be connected to how the body deals with females' second X chromosome¹.

The finding could help improve doctors' abilities to detect autoimmune diseases.

E. John Wherry is an immunologist at the University of Pennsylvania. He said the new study changes "the way we think about this whole process of autoimmunity."

Between 24 million and 50 million Americans suffer from an autoimmune disorder². Autoimmune disorders³ include lupus, rheumatoid arthritis⁴, multiple sclerosis, and many other diseases.

About four of every five patients with an autoimmune disorder are women. Scientists have tried to find out why for many years.

One theory is that the X chromosome might be the reason. Females have two X chromosomes⁵ while males have one X and one Y.

The new research recently appeared in the publication Cell. The results show that the extra X is involved — but in an unexpected way.

Our DNA⁶ is carried inside each cell in 23 pairs of chromosomes, including the final pair that decides biological sex. The X chromosome is packed with hundreds of genes⁷, far more than males' much smaller Y chromosome.

Every female cell must turn off one of its X chromosome copies to avoid getting a dangerous double amount of all those genes. Scientists call this process X-chromosome inactivation⁸.

A special kind of RNA, called Xist, performs the X-chromosome inactivation. Xist is a long chain of RNA. It gathers in areas along a cell's extra X chromosome and attracts proteins that connect to it in unusual masses. Then it silences the chromosome.

Dr. Howard Chang is a dermatologist⁹ at Stanford University. He was exploring how Xist does its job when his lab found nearly 100 of those attached proteins. Chang saw that many of those proteins were related to skin-related autoimmune disorders. Patients can have "autoantibodies" that mistakenly attack these normal proteins.

Chang told The Associated Press, "That got us thinking: These are the known ones. What about the other proteins in Xist?"

He added that the molecule¹⁰, found only in women, might "somehow organize proteins in such a way as to activate¹¹ the immune system."

If true, Xist by itself could not cause autoimmune disease. If it did, all women would be affected¹². Scientists have long thought it takes a combination of some genes and an environmental event, like an infection or injury, for the immune system to cause problems. For example, the Epstein-Barr virus is linked to multiple sclerosis.

Chang receives financial support from the Howard Hughes Medical Institute, which also supports The Associated Press' Health and Science Department.

Chang's team decided¹³ to produce male lab mice to artificially make Xist — without turning off their only X chromosome — and see what happened. Researchers also specially¹⁴ bred mice susceptible¹⁵ to developing a lupus-like condition. The condition can be set off by a certain chemical.

The Xist formed its usual protein masses. When the chemical was used, the male mice with Xist developed lupus-like autoimmunity at levels similar to females, the team found.

Chang said, "We think that's really important, for Xist RNA to leak out of the cell to where the immune system gets to see it."

But he added that an environmental event is still needed to start the process.

Beyond mice, researchers also looked at blood from 100 patients. They found autoantibodies targeting Xist-related proteins that scientists had not previously¹⁶ linked to autoimmune disorders. Chang said one possible reason was that most tests for autoimmunity were made using male cells.

More research is necessary. But Wherry, the immunologist at Penn, said the findings might give doctors a shorter path to diagnosing patients.

Wherry said one patient may have autoantibodies to Protein A and another patient may have autoantibodies to Proteins C and D. But he said knowing they are all related to Xist RNA can help doctors find diseases more easily.

Words in This Story

detect – v. to discover or notice the presence of (something that is hidden or hard to see, hear, taste, etc.)

dermatologist – n. the scientific study of the skin and its diseases

activate – v. to cause (a chemical reaction or natural process) to begin

susceptible – adj. easily affected, influenced, or harmed by something

1 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

2 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。

3 disorders   

n.混乱( disorder的名词复数 )；凌乱；骚乱；（身心、机能）失调

参考例句：

• Reports of anorexia and other eating disorders are on the increase. 据报告，厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
• The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》

4 arthritis   

n.关节炎

参考例句：

• Rheumatoid arthritis has also been linked with the virus.风湿性关节炎也与这种病毒有关。
• He spent three months in the hospital with acute rheumatic arthritis.他患急性风湿性关节炎，在医院住了三个月。

5 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

6 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

7 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

8 inactivation   

n.灭活，失活，钝化（作用）；减化

参考例句：

• This inactivation may be accomplished in a variety of ways. 这种失去活性作用能以多种方式来实现。 来自辞典例句
• Long sonication periods can lead to some inactivation. 长时间的声波作用可导致某种程度的失活。 来自辞典例句

9 dermatologist   

n.皮肤科医师

参考例句：

• I think you should see a dermatologist first.我想你应当先看皮肤科大夫。
• The general practitioner referred her patient to a dermatologist.家庭医生把她的病人交给了皮肤科医生。

10 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。

11 activate   

vt.使活动起来，使开始起作用

参考例句：

• We must activate the youth to study.我们要激励青年去学习。
• These push buttons can activate the elevator.这些按钮能启动电梯。

12 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

13 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

14 specially   

adv.特定地；特殊地；明确地

参考例句：

• They are specially packaged so that they stack easily.它们经过特别包装以便于堆放。
• The machine was designed specially for demolishing old buildings.这种机器是专为拆毁旧楼房而设计的。

15 susceptible   

adj.过敏的，敏感的；易动感情的，易受感动的

参考例句：

• Children are more susceptible than adults.孩子比成人易受感动。
• We are all susceptible to advertising.我们都易受广告的影响。

16 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。