Navigation Links
The missing link between belly fat and heart disease?
Date:1/22/2008

ANN ARBOR, Mich. By now, everyone knows that overweight people have a higher risk of heart attacks, strokes and other problems that arise from clogged, hardened arteries. And people who carry their extra weight around their waist giving them a beer belly or an apple shape -- have the highest risk of all.

But despite the impact on human health, the reasons behind this connection between heart disease and belly fat also known as visceral fat -- have eluded scientists. Now, a new study in mice gives the first direct evidence of why this link might exist and a tantalizing look at how it might be broken.

In a paper that will be published online today in the journal Circulation before print publication in February, a team of University of Michigan Cardiovascular Center scientists reports direct evidence of a link between inflammation around the cells of visceral fat deposits, and the artery-hardening process of atherosclerosis.

The researchers also show that a medication often given to people with diabetes can be used to calm that inflammation, and protect against further artery damage.

Although the scientists caution that its far too early to apply their findings to humans with belly fat, they hope that further research in animals and people will reveal more about how this dangerous link comes about, why it begins, how it can be reversed, and perhaps how it can be diagnosed at an early stage through blood tests.

Until then, the best advice for overweight people who want to reduce their chance of a heart attack or stroke remains the same: Work on losing your belly fat, and your other excess body weight, through a balanced, healthy diet and regular exercise.

The research team is led by Daniel Eitzman, M.D., a cardiologist, laboratory scientist and associate professor in the Division of Cardiovascular Medicine at the U-M Medical School and the VA Ann Arbor Healthcare System.

The discovery came partly by chance. He and his colleagues had been studying mice that lack the gene for leptin, a hormone generated by fat cells that plays a role in appetite and metabolism as well as reproduction. In an effort to get these obese mice to produce some leptin, the team developed a technique to transplant clusters of fat cells from normal mice of the same strain, into the leptin-deficient mice.

The result surprised them. In addition to producing leptin and preventing obesity, the fat transplants became inflamed, attracting immune cells called macrophages, Eitzman explains. Since the mice were genetically identical except for leptin, this shouldnt have happened. But the inflammation was there, and it was chronic.

The inflammation occurred around individual fat cells, or adipocytes. Further tests showed it was regulated by the same factors that regulate the inflammation that other researchers have seen in the naturally occurring fat deposits of obese mice specifically a chemokine called MCP-1.

But because the fat was transplanted, the inflammation could be attributed directly to the fat, and not to overfeeding of the mice, or the metabolic problems that overfeeding and obesity bring, such as diabetes.

Armed with this discovery, the researchers set out to see what was causing inflammation to occur, and what implications it had. The team included postdoctoral fellow Miina hman, M.D., Ph.D., U-M professor Daniel Lawrence, Ph.D., and members of the Eitzman and Lawrence laboratory teams.

They were especially interested to see if there might be any link between the inflammation and atherosclerosis the formal name for the process by which blood vessels become stiff, narrowed and lined with plaque formations that can trigger the development of blood clots.

This process, which occurs throughout the body, sets the stage for most heart attacks and strokes. Scientists and clinicians now realize that it is based on inflammation the abnormal reaction of the bodys immune system to its own tissue and in the damage that immune-system cells and molecules can inflict.

Since normal mice dont develop atherosclerosis, the team had to turn to a strain that had been developed to be especially prone to high cholesterol and hardened arteries. These ApoE-negative mice, as they are called, were divided into three groups: two that received fat transplants from normal mice, and one that did not, but that had the same operation that would be used to implant the fat in other mice.

Some of the fat-transplant ApoE-negative mice received transplants of visceral fat, which forms in the belly around the major organs, while others received transplants of subcutaneous fat the type thats found just under the skin throughout the body.

Sure enough, the mice that received the visceral fat transplants developed atherosclerosis at a much-accelerated rate, and experienced the same type of inflammation as the leptin-deficient mice had. Meanwhile, those that received subcutaneous fat did not experience an increase in atherosclerosis despite having increased inflammation. The mice that had the sham operations developed neither inflammation nor increased atherosclerosis.

There appeared to be an interaction between the macrophages causing the inflammation in the visceral fat, and the process of atherosclerosis, says Eitzman, who notes that blood vessels far from the site of the fat transplant developed increased atherosclerosis.

Finally, the team attempted to calm the inflammation and curb the atherosclerosis by treating the mice with pioglitazone a member of the class of drugs called thiazolidinediones or TZDs that are often used to treat diabetes. While TZD drugs have an impact on metabolism, which makes them useful in diabetes, they also have been discovered to have an anti-inflammatory effect.

And in fact, the drug reduced both the concentration of macrophages and MCP-1, and atherosclerosis, in those mice that received transplants of visceral fat. But the drug had no effect in the other mice.

Now that they have demonstrated the linkage between belly fat, inflammation and hardened arteries, and a potential mechanism for reversing the phenomenon, the team is working on new pieces of the puzzle. Specifically, theyre looking for the factors that might trigger macrophages to invade the area and bring on inflammation, and for blood-borne molecules called biomarkers that might be used as a way to identify early warning signs of atherosclerosis. Theyll also look at other classes of drugs to see if they might have a protective effect, because TZD drugs act on many systems and cause some side effects.


'/>"/>

Contact: Kara Gavin
kegavin@umich.edu
734-764-2220
University of Michigan Health System
Source:Eurekalert

Related medicine news :

1. Some antipsychotic drugs may be missing their mark
2. Justice Department to Hold Media Event to Demonstrate New Database for Matching Unidentified Remains and Missing Persons Information
3. The National Center for Missing & Exploited Children, Wal-Mart, and Abbott Host Child Safety Events
4. Kaiser Permanente study shows link between caffeine and miscarriage
5. Biological Link Between BRCA1 and Breast Cancer Detailed
6. First in Nation: notMYkid Educational Center Is Now a Reality Thanks to a Partnership Between Chrysler, Barrett-Jackson and notMYkid
7. 51st Food and Drug Law Institute Annual Conference Focuses on Relationship Between Scientific Advances and FDA Law & Regulation
8. New Poll Announces Link Between Friends and Family Influence and a Healthy Lifestyle
9. No link between acid reflux and survival
10. Settlement Reached Between Dilon Technologies and Naviscan on Patent Rights
11. Blue Cross Blue Shield of Michigan Foundation Funds Study Exploring Link between Heart Disease and Depression
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/8/2016)... Cincinnati, OH (PRWEB) , ... December 08, 2016 ... ... offering insurance and financial planning services from offices headquartered in Hamilton County, is ... animal rescue LuvFurMutts. , LuvFurMutts specializes in finding new homes for orphaned or ...
(Date:12/8/2016)... ... December 08, 2016 , ... Peter Zipp Insurance, ... and around the greater Phoenix metropolitan region, is announcing a charity event to ... of the Homeless Youth Connection is to promote community awareness of the ongoing ...
(Date:12/8/2016)... Louis, MS (PRWEB) , ... December 08, 2016 , ... ... that serve commercial and residential clients in and around the Hancock County area, is ... for the Hancock County Food Pantry. , The Hancock County Food Pantry has worked ...
(Date:12/8/2016)... ... December 08, 2016 , ... Bill Mull ... business owners in and around central Kansas, is joining the Youth Horizons organization ... the region. , Headquartered in Wichita, Youth Horizons works to empower area children ...
(Date:12/7/2016)... ... December 07, 2016 , ... Students ... have the unique opportunity to get hands-on experience in an emergency medical simulation, ... immersive experience to gain invaluable, real-life medical skills that are critical success in ...
Breaking Medicine News(10 mins):
(Date:12/8/2016)... Texas , Dec. 8, 2016 ... program that brings leading-edge laboratory services and management ... United States , allowing more doctors and ... health care management solutions. Logo - ... Hospital systems, under pressure to contain ...
(Date:12/8/2016)... Mederi Therapeutics Inc . hat die behördliche Zulassung durch die CFDA sowie ... – in China angekündigt. ... ... Live Stretta procedure performed and broadcast during the Chinese Congress ... Union Hospital ...
(Date:12/8/2016)... 8, 2016 Dignitana, a world leader in ... Boa® Technology, creator of the award-winning, patented Boa® system, ... with the DigniCap® scalp cooling system. DigniCap® was cleared ... 2015, and is the first medical scalp cooling device ... cooling system features a patented tight-fitting silicone cooling cap ...
Breaking Medicine Technology: