A protein produced by human fat cells may explain why overweight people face a higher risk of heart disease and stroke as well as shed new light on the link between inflammation and these disorders.
A new study shows body fat cells produce a protein called C-reactive protein (CRP) in response to inflammatory substances.
Researchers say CRP has previously been found only in the liver or within blood vessel walls where it is produced in response to inflammatory triggers. But these results suggest that body fat may also be capable of producing the protein, which has been linked to an increased risk of heart disease and stroke.
"This study is the first to show how body fat participates in the inflammatory process that leads to cardiovascular disease," says researcher Edward T. H. Yeh, MD, chairman of the department of cardiology at the University of Texas M.D. Anderson Cancer Center, in a news release.
Body Fat’s Role in Heart Disease
Researchers say overweight people generally have elevated CRP levels, but until now it hasn’t been clear why.
In the study, published in the Journal of the American College of Cardiology, researchers looked at whether body fat cells could produce C-reactive protein under a variety of conditions in the lab.
The results showed that the fat cells produced inflammatory substances known as cytokines, which resulted in inflammation and then triggered the production of high levels of C-reactive protein.
In addition, researchers found resistin, a hormone produced by body fat cells associated with diabetes and insulin resistance, also triggered the production of CRP.
"If fat cells by themselves produce inflammatory signals that trigger cells to produce CRPs, and if CRPs also produce biological effects on vascular walls, that could explain the higher risk of cardiovascular disease," says Yeh.
Drugs May Block Fat’s Effect on CRP
Researchers then exposed the body fat cells that were producing C-reactive protein to drugs used to treat heart disease, including aspirin and cholesterol-lowering statins, and the diabetes drug Rezulin.
The results showed that treatment with these drugs significantly reduced the production of C-reactive protein.
"We knew from studying patients that these drugs can reduce C-reactive proteins, but now we have direct proof of their benefit,” says Yeh.
Researchers say it’s still not clear why body fat produces an inflammatory response and what CRP’s role in that process is.
"Inflammation is a very complicated phenomenon, but at least we now have a few more clues as to what it does and how the damage it produces can be prevented."
SOURCES: Calabro, P. Journal of the American College of Cardiology, Sept. 20, 2005; vol 46: pp 1112-1113. News release, University of Texas Health Science Center, Houston; University of Texas M.D. Anderson Cancer Center.