[An Immunologist Explains When Cells Decide To Die With a Bang or
Take Their Quiet Leave]
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SUNDAY SCIENCE: CELL DEATH IS ESSENTIAL TO YOUR HEALTH  
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Zoie Magri
October 4, 2023
The Conversation
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_ An Immunologist Explains When Cells Decide To Die With a Bang or
Take Their Quiet Leave _

Programmed cell death such as apoptosis is a common stage of cellular
life., Nanoclustering/Science Photo Library via Getty Images

 

Living cells work better than dying cells, right? However, this is not
always the case: your cells often sacrifice themselves to keep you
healthy
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The unsung hero of life is death.

While death may seem passive, an unfortunate ending that just
“happens,” the death of your cells is often extremely purposeful
and strategic. The intricate details of how and why cells die can have
significant effects on your overall health.

There are over 10 different ways cells can “decide” to die, each
serving a particular purpose for the organism. My own research
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explores how immune cells switch between different types of programmed
death in scenarios like cancer or injury.

Programmed cell death can be broadly divided into two types
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that are crucial to health: silent and inflammatory.

Quietly exiting: silent cell death

Cells can often become damaged because of age, stress or injury, and
these abnormal cells can make you sick
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Your body runs a tight ship, and when cells step out of line, they
must be quietly eliminated before they overgrow into tumors or cause
unnecessary inflammation
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where your immune system is activated and causes fever, swelling,
redness and pain.

Your body swaps out cells every day
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tissues are made up of healthy, functioning ones. The parts of your
body that are more likely to see damage, like your skin and gut, turn
over cells weekly, while other cell types can take months to years to
recycle. Regardless of the timeline, the death of old and damaged
cells and their replacement with new cells is a normal and important
bodily process.

Silent cell death, or apoptosis
[[link removed]], is described as
silent because these cells die without causing an inflammatory
reaction. Apoptosis is an active process involving many proteins and
switches within the cell. It’s designed to strategically eliminate
cells without alarming the rest of the body.

Sometimes cells can detect that their own functions are failing and
turn on executioner proteins
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DNA, and they quietly die by apoptosis. Alternatively, healthy cells
can order overactive or damaged neighbor cells to activate their
executioner proteins.

Apoptosis is important to maintaining a healthy body. In fact, you can
thank apoptosis for your fingers and toes
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Fetuses initially have webbed fingers until the cells that form the
tissue between them undergo apoptosis and die off.

[Microscopy image of mouse foot at embryonic stage]
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The toes of this embryonic mouse foot are forming through apoptosis.
Michal Maňas/Wikimedia Commons
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CC BY-SA [[link removed]]

Without apoptosis, cells can grow out of control. A well-studied
example of this is cancer. Cancer cells are abnormally good at growing
and dividing, and those that can resist apoptosis
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tumors. Understanding how apoptosis works and why cancer cells can
disrupt it can potentially improve cancer treatments.

Other conditions can benefit from apoptosis research as well. Your
body makes a lot of immune cells that all respond to different
targets, and occasionally one of these cells can accidentally target
your own tissues. Apoptosis is a crucial way your body can eliminate
these immune cells before they cause unnecessary damage. When
apoptosis fails to eliminate these cells, sometimes because of genetic
abnormalities, this can lead to autoimmune diseases
[[link removed]] like lupus.

Another example of the role apoptosis plays in health is endometriosis
[[link removed]], an understudied disease
caused by the overgrowth of tissue in the uterus. It can be extremely
painful and debilitating for patients. Researchers have recently
linked this out-of-control growth in the uterus
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Whether it’s for development or maintenance, your cells are quietly
exiting to keep your body happy and healthy.

Going out with a bang: inflammatory cell death

Sometimes, it is in your body’s best interest for cells to raise an
alarm as they die. This can be beneficial when cells detect the
presence of an infection and need to eliminate themselves as a target
while also alerting the rest of the body. This inflammatory cell death
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is typically triggered by bacteria, viruses or stress.

Rather than quietly shutting down, cells undergoing inflammatory cell
death will make themselves burst, or lyse, killing themselves and
exploding inflammatory messengers as they go. These messengers tell
your immune cells that there is a threat and prompts them to treat and
fight the pathogen.

An inflammatory death would not be healthy for maintenance. If the
normal recycling of your skin or gut cells caused an inflammatory
reaction, you would feel sick a lot. This is why inflammatory death is
tightly controlled [[link removed]] and
requires multiple signals to initiate.

Despite the riskiness of this grenadelike death, many infections would
be impossible to fight without it. Many bacteria and viruses need to
live around or inside your cells to survive. When specialized sensors
on your cells detect these threats, they can simultaneously activate
your immune system and remove themselves as a home for pathogens.
Researchers call this eliminating the niche
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pathogen.

Cells die in many ways, including lysis.

Inflammatory cell death plays a major role in pandemics. _Yersinia
pestis_ [[link removed]], the bacteria
behind the Black Death, has evolved various ways of stopping human
immune cells from mounting a response. However, immune cells developed
the ability to sense this trickery and die an inflammatory death. This
ensures that additional immune cells will infiltrate and eliminate the
bacteria despite the bacteria’s best attempts to prevent a fight.

Although the Black Death is not as common nowadays, close relatives
_Yersinia pseudotuberculosis_ and _Yersinia enterocolitica_ are behind
outbreaks of food-borne illnesses
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rarely fatal because your immune cells can aggressively eliminate the
pathogen’s niche by inducing inflammatory cell death. For this
reason, however, _Yersinia_ infection can be more dangerous in
immunocompromised people.

The virus behind the COVID-19 pandemic
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inflammatory cell death. Studies show that without cell death the
virus would freely live inside your cells and multiply. However, this
inflammatory cell death can sometimes get out of control and
contribute to the lung damage
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seen in COVID-19 patients, which can greatly affect survival.
Researchers are still studying the role of inflammatory cell death in
COVID-19 infection, and understanding this delicate balance can help
improve treatments.

In good times and bad, your cells are always ready to sacrifice
themselves to keep you healthy. You can thank cell death for keeping
you alive.[The Conversation]

Zoie Magri [[link removed]],
Ph.D. Candidate in Immunology, _Tufts University
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This article is republished from The Conversation
[[link removed]] under a Creative Commons license. Read
the original article
[[link removed]].

RAGE AGAINST THE MACHINE OWNERS: BRIAN MERCHANT ON LUDDITE LESSONS FOR
21ST-CENTURY TECHNOLOGY
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By SARA GOUDARZI 
BULLETIN OF THE ATOMIC SCIENTISTS
October 16, 2023

* Science
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* immune system
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* Medicine
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* cells
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