Featured Research

from universities, journals, and other organizations

Muscle repair after injury helped by fat-forming cells

Date:
April 19, 2013
Source:
University of California - San Francisco
Summary:
Scientists have discovered that muscle repair requires the action of two types of cells better known for causing inflammation and forming fat.

UCSF researchers discovered in mice that immune cells called eosinophils secrete a molecule called IL-4 (dyed red) in injured muscle to drive cells to stimulate muscle regrowth instead of fat formation.
Credit: Image courtesy of Ajay Chawla

UC San Francisco scientists have discovered that muscle repair requires the action of two types of cells better known for causing inflammation and forming fat.

Related Articles


The finding in mice, published in the April 11 issue of Cell, showed that a well-known immune cell called the eosinophil [ee-oh-SIN-oh-fil] carries out the beneficial role in two ways -- by clearing out cellular debris from damaged tissue and teaming up with a type of cell that can make fat to instead trigger muscle regrowth.

The study, led by Ajay Chawla, MD, PhD, an associate professor of medicine at the UCSF Cardiovascular Research Institute, showed that after eosinophils move to the site of injury, they collaborate with a kind of progenitor cell -- immature cells similar to stem cells -- to drive the formation of new muscle fibers. The progenitors, called the fibro/adipogenic cells (FAP), do not spin off muscle cells directly.

"Without eosinophils you cannot regenerate muscle," Chawla said.

FAP cells have been known for their role in making fat, which occurs as the body ages or experiences prolonged immobility. They also have been known to make cells that form connective tissue. But the UCSF study showed that FAP cells also team up with eosinophils to make injured muscles get stronger rather than fatter, at least in mice.

In a kind of cellular chain reaction, Chawla's team found that when eosinophils at the site of muscle injury secrete a molecule called IL-4, FAP cells respond by expanding their numbers. And instead of becoming fat cells, they act on the true muscle stem cells to trigger the regrowth of muscle fibers.

"They wake up the cells in muscle that divide and form muscle fibers," he said.

Eosinophils help fight bacteria and parasites, as do other immune cells, but eosinophils are more often thought of for their maladaptive roles in allergies and other inflammatory reactions. Eosinophils comprise only a few percent of immune cells.

Chawla's team found that, even before active muscle repair, the chain reaction initiated by eosinophils performs another necessary task -- taking out the garbage.

"Eosinophils, acting via FAPs, are needed for the rapid clearance of necrotic debris, a process that is necessary for timely and complete regeneration of tissues," Chawla said.

Bigger and more abundant immune cells called macrophages -- with large appetites and a propensity to gobble up debris in other destructive scenarios -- had often, but erroneously, been credited with cleaning up messes within distressed muscle tissue.

"Bites from venomous animals, many toxicants, and parasitic worms all trigger somewhat similar immune responses that cause injury," Chawla said. "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."

Additional UCSF co-authors include postdoctoral fellow Jose E. Heredia, PhD; specialist Lata Mukundan, PhD; technician Francis Chen; Rahul Deo, MD, PhD, an assistant professor of medicine in residence; and Richard M. Locksley, MD, an immunologist and professor of medicine. Stanford researchers Thomas Rando, MD, PhD, and graduate student Alisa Mueller also were members of the study team.

The National Institutes for Health and the California Institute for Regenerative Medicine funded the research.


Story Source:

The above story is based on materials provided by University of California - San Francisco. The original article was written by Jeffrey Norris. Note: Materials may be edited for content and length.


Journal Reference:

  1. JoseE. Heredia, Lata Mukundan, FrancisM. Chen, AlisaA. Mueller, RahulC. Deo, RichardM. Locksley, ThomasA. Rando, Ajay Chawla. Type 2 Innate Signals Stimulate Fibro/Adipogenic Progenitors to Facilitate Muscle Regeneration. Cell, 2013; 153 (2): 376 DOI: 10.1016/j.cell.2013.02.053

Cite This Page:

University of California - San Francisco. "Muscle repair after injury helped by fat-forming cells." ScienceDaily. ScienceDaily, 19 April 2013. <www.sciencedaily.com/releases/2013/04/130419171649.htm>.
University of California - San Francisco. (2013, April 19). Muscle repair after injury helped by fat-forming cells. ScienceDaily. Retrieved February 28, 2015 from www.sciencedaily.com/releases/2013/04/130419171649.htm
University of California - San Francisco. "Muscle repair after injury helped by fat-forming cells." ScienceDaily. www.sciencedaily.com/releases/2013/04/130419171649.htm (accessed February 28, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Saturday, February 28, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could a $34 Smartphone Device Improve HIV Diagnosis in Africa?

Could a $34 Smartphone Device Improve HIV Diagnosis in Africa?

Reuters - Innovations Video Online (Feb. 27, 2015) A dongle that plugs into a Smartphone mimics a lab-based blood test for HIV and syphilis and can detect the diseases in 15 minutes, say researchers. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Doctor Says Head Transplants Possible Within Two Years

Doctor Says Head Transplants Possible Within Two Years

Buzz60 (Feb. 27, 2015) An Italian doctor is saying he could stick someone&apos;s head onto someone else&apos;s body. Patrick Jones (@Patrick_E_Jones) reports. Video provided by Buzz60
Powered by NewsLook.com
How Your Dentist Could Help Screen You For Diabetes

How Your Dentist Could Help Screen You For Diabetes

Newsy (Feb. 27, 2015) A new study from researchers at New York University suggests dentists could soon use blood samples taken from patients&apos; mouths to test for diabetes. Video provided by Newsy
Powered by NewsLook.com
The Best Tips to Makeover Your Health

The Best Tips to Makeover Your Health

Buzz60 (Feb. 27, 2015) If you&apos;re looking to boost your health this season, there are a few quick and easy steps to prompt you for success. Krystin Goodwin (@Krystingoodwin) has the best tips to give your health a makeover this spring! Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins