DNA from the heart’s own cells may play a
role in heart failure by mistakenly activating the body’s immune system,
researchers have found.
DNA
from the heart’s own cells may play a role in heart failure by mistakenly
activating the body’s immune system, researchers have found.
Scientists
from King’s College London, U.K., and Osaka University Medical School, Japan,
show that ‘rogue DNA’ can kick start the body’s natural response to infection,
contributing to the process of heart failure.
During
heart failure immune cells invade the heart, a process called inflammation
which is normally caused by bacterial or viral infection. The process makes
heart muscle less efficient, reducing its ability to pump blood around the
body.
The
study, published in the journal Nature, shows in mice that
inflammation in the heart can be caused by the body’s own DNA. The DNA escapes
when a natural process to break down damaged cell components, called autophagy,
becomes less efficient, which sometimes happens when cells are under stress
such as during heart failure.
The
problem DNA comes from mitochondria, energy-generating structures in heart
cells which resemble DNA from bacteria. These DNA trigger a receptor in immune
cells called Toll-like Receptor 9 (TLR9).
Mitochondria
in our cells are believed to have evolved from bacteria more than 1.5 billion
years ago, and this study shows that the human immune system still recognizes
the bacterial fingerprint in mitochondrial DNA, triggering a response from the
immune system.
“When
mitochondria are damaged by stress, such as during heart failure, they become a
problem because their DNA still retains an ancient bacterial fingerprint that
mobilizes the body’s defenses,” said Professor Kinya Otsu who led the study.
As
heart cells are packed with mitochondria, which provide the power the heart
needs to pump blood around the body, understanding how mitochondrial DNA causes
part of the problem during heart failure may lead to future treatments for
heart failure, the authors say.
The
article can be found at: Oka T et al. (2012) Mitochondrial
DNA That Escapes from Autophagy Causes Inflammation and Heart Failure.
Source: British
Heart Foundation.
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