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HPV是如何引发癌症的?

This Is How HPV Causes Cancer

人乳头状瘤病毒 即HPV 名声怪异
Human papilloma virus, or HPV, has a strange reputation.
也许你知道它通过性传播感染
You might know of it as a sexually transmitted infection
继而引发令人不适的疣 乳头状瘤
that causes uncomfortable warts, the papilloma
也许你也听说它会引发致命癌症
but you also may have heard that it can lead to a deadly form of cancer.
两种说法都正确
Both are actually true,
感染HPV病毒者
as is the possibility that you can have HPV
有可能毫无病症 也是真的
and experience no symptoms whatsoever.
HPV并不单指一种病毒
HPV isn’t just one virus.
事实上 HPV有200多种亚型
There are actually over 200 strains,
不同亚型的HPV引起的临床表现也不同
and the different types of HPV can result in different outcomes
此部分我们稍后探讨
which we’ll get into a little bit later.
但首先 HPV必须找到侵入皮肤的途径
But first, before HPV can do anything,
才能有所作为
it has to find a way into your skin.
大家好 我是Moscicki医生
Hi,I’m Dr. Moscicki
来自加利福尼亚州立大学洛杉矶分校的小儿科
from the University of California Los Angeles, Department of Pediatrics.
是青少年内科主任
I’m chief of adolescent and young adult medicine,
从事研究HPV已逾30年
and I have been studying HPV for over 30 years now.
当你观察皮肤时 可以发现它有好几层
So when you’re looking at skin, you have several layers,
有基底细胞层
and you have the very basal cell layer, that is
这层细胞就位于基膜上方
the layer that sits right on top of the basement membrane,
在基膜下方的我们称之为真皮层
and right under that is what we call the dermis.
在基底层细胞上方的是棘细胞层
and on top of that, you have the spinous,
最后 最上方的是角质层
and eventually, you get the very top cornified cell layers.
HPV由伤口或轻微擦伤处进入体内
HPV first attaches itself to the basement membrane,
并首先附着于基膜
by entering the body through a wound ormicro-abrasion.
这一过程通常通过性交完成
It usually does this through sexual intercourse,
但也有非性交传播的种类
but there are other types of HPV
此类HPV会引发手疣和足疣
that cause hand and foot warts that aren’t sexually transmitted.
HPV到达皮肤基底层是关键的一步
Reaching the basement layer is key
因为基底层有HPV必须先附着的受体
because there is a receptor there that it must attach to first.
这个受体被称为硫酸乙酰肝素受体
It’s referred to as a heparan sulfate receptor.
就是此受体改变病毒
This receptor actually changes the virus
使病毒附着于基底细胞
so that it can then attach to the basal cells.
这一过程一旦完成
Once it does this,
病毒就把它的DNA注入了基底细胞的细胞核
it injects its DNA into the cell’s nucleus.
随着基底细胞的成熟
As the basal cells matures,
受感染细胞一路传染到皮肤表层
the infected cell makes its way to the very top.
这就有点像病毒劫持了基底细胞
…it kind of hijacks the cell.
使受感染细胞开始增殖
And what it does is it makes it start proliferating a lot
以便进行自我复制
so that it can replicate itself.
这个行为不会引起身体对疾病的防御反应
This all happens without your body mounting a real defense against the disease
因为HPV直到生命周期后期
because HPV avoids expressing genes
才会激发免疫应答的表达基因
that would initiate an immune response until later in its lifecycle.
这就像HPV为了生存进化出的一种机制
it looks like it’s a mechanism that HPV has developed in order for its own survival.
但就算HPV找到了巧妙避开免疫系统的方式
But while HPV has found a clever way to avoid the immune system,
机体仍能免受感染
the body can still get rid of the infection.
如你所知 当你洗澡时
Like you know, when you’re taking a shower,
一些表层皮肤会脱落
that top layer of skin kind of comes off.
一旦表皮脱落
once it gets sloughed off,
如果HPV没有其他部位可入侵
if there’s no other place to invade
这种感染很快就会消失
then that infection’s just gonna burn out very quickly.
也就是说HPV找到途径附着于基膜的机会只有一次
That it was a one-time chance that it found access to the basement membrane.
事实上 虽然80%的美国人
In fact, even though 80 % of people in the United States
被认定感染过HPV
are thought to contract HPV,
但是其中90%的感染能自愈
90% of infections are cleared on their own.
所以如果感染期持续不久
So if the infection doesn’t usually last,
又有什么大不了的呢?
what’s the big deal?
好吧 这就是不同亚型的HPV重要之处
Well, that’s where those different types of HPV become really important,
特别是那些会引发癌症的类型
specifically the ones that can cause cancer.
与癌症相关的HPV亚型大约只有13种
There’s only about 13 types that we have associated with cancer,
它们都属于α型
and they all fall into the alpha types.
其中最有名的是HPV-16 HPV-18
The most famous ones are type 16 and 18.
大约70%的宫颈癌由这两种亚型引发
They’re actually responsible for around 70% of cervical cancers.
HPV-16 18与那些虽会引发令人不适的疣
Types 16 and 18 are totally different from the types of HPV that cause warts
但所幸几乎不会癌变的亚型不同
which aren’t pleasant but fortunately do not typically become cancerous.
我们认为 HPV引发癌症的方式是
What we believe the way it causes cancer is that
它可能感染了位于基底细胞层的干细胞
it infects probably a stem cell within the basal cell layer.
因此 这些干细胞 在病毒成熟过程中
Therefore, those stem cells, as it maturates,
是这样的: HPV劫持了宿主细胞机制
what happens is literally HPV hijacks the host cell machinery
说 我要你不断复制
says, I want you to replicate,
因为每次你不阻止我的时候
because every time you don’t stop me,
我都能越来越多地复制我的DNA
I can make more and more of my DNA.
致癌型HPV在干细胞中复制时
While replicating in stem cells,
会表达E6 E7基因
these oncovirus types of HPV will express the genes called E6 and E7
这些癌变蛋白阻止身体杀死或清除受损DNA
These oncoproteins stop the body from killing and clearing out cells with damaged DNA
允许癌细胞继续复制
allowing the cancerous cells to continue replicating.
所以有细胞受损时 就是一场比赛
So when there’s a damaged cell, it’s a race.
这样说吧 免疫系统似乎在尽最大的努力
Like, their immune system is probably trying its best
但HPV病毒真的给免疫系统造成很大压力
but it’s really pushing the system,
其复刻速度要比免疫系统找到机会抑制它快得多
that it’s replicating way faster than the immune system can even access it.
幸运的是 我们有方法阻止HPV到达这一步
Fortunately, we have ways to prevent HPV from getting to this point.
首先 宫颈癌症筛查
First, there are screenings for cervical cancer
能够在癌症前期发现疾病
that can catch the disease when it is still pre-cancerous.
但不幸的是 其他一些由HPV引发的癌症
But there is an unfortunate lack of screening methods
仍缺乏筛查手段
for the other cancers caused by HPV.
自2006年起 有了一种有效的疫苗
For people who are young enough and have not been exposed to HPV,
可供尚未暴露于HPV的年轻人使用
there is also a very effective vaccine has been available since 2006.
有人或许认为疫苗只适用于女性
And while some people might think it’s only given to girls
因为女性有罹患宫颈癌的风险
because of the risk of cervical cancer,
但同样建议男性接种疫苗
It’s recommended for boys as well.
所以我们讨论的是
So the prevention here we are talking
关于肛门癌 阴茎癌 口咽癌的预防
about anal cancers, penile cancers, and oropharyngeal cancers.
接种疫苗 对男性与女性来说同等重要
So it’s equally as important for boys to get this vaccine as it is for girls.
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视频概述

这个视频简单地介绍了HPV病毒感染人体的机制以及预防手段

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视频来源

https://www.youtube.com/watch?v=SPezZ6qKGFw

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