Saturday, 20 April 2013

Eosinophils trigger stem cells to repair damaged muscle tissue

Eosinophil granulocytes, or simply Eosinophils, are white blood cells responsible for combating multicellular parasites and certain infections. However, a new study on mice, by researchers at the University of California, San Francisco (UCSF) suggests that they may also be crucial for muscle regeneration.

In this study, the researchers showed that eosinophils have a double role in muscle tissue repair. Their first role is to take out the garbage, the cellular debris left by damaged tissues.

"Eosinophils are needed for the rapid clearance of necrotic debris, a process that is necessary for timely and complete regeneration of tissues," said Ajay Chawla, who led the research.
Image of an eosinophil
Red blood cells surround an eosinophil, two platelets at the top left corner (400 magnification)

However, Eosinophils are not only responsible for the garbage. They also secrete a protein known as Interleukin 4 (IL-4) which in turn triggers a specific type of stem cells to start replicating.

"Without eosinophils you cannot regenerate muscle," said Chawla

Interleukin 4, computer generated image

These stem cells are known as "fibro/adipogenic cells" (FAP). Up until now, it was believed that FAP cells could only generate adipose (fat) tissue. But when exposed to IL-4, these stem cells begin forming new muscle fibres, making muscle tissue "harder" and not "fatter" as the researchers say.

"They wake up the cells in muscle that divide and form muscle fibres," said Chawla

Now the researchers wish to continue their studies to further expand our current knowledge of eosinophils.

"Bites from venomous animals, many toxicants, and parasitic worms all trigger somewhat similar immune responses that cause injury. We want to know if eosinophils and FAPs are universally employed in these situations as a way to get rid of debris without triggering severe reactions such as anaphylactic shock." said Chawla

Heredia, J., Mukundan, L., Chen, F., Mueller, A., Deo, R., Locksley, R., Rando, T., & Chawla, A. (2013). Type 2 Innate Signals Stimulate Fibro/Adipogenic Progenitors to Facilitate Muscle Regeneration Cell, 153 (2), 376-388 DOI: 10.1016/j.cell.2013.02.053

1 comment:

  1. anonymous monster20 April 2013 at 13:14

    this is very interesting, i wonder what other mysteries the human body has !


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