Navigation Links
Scientists find obesity alone does not cause arthritis in animals
Date:9/28/2009

DURHAM, N.C. The link between obesity and osteoarthritis may be more than just the wear and tear on the skeleton caused by added weight.

A Duke University study has found that the absence of the appetite hormone leptin can determine whether obese mice experience arthritis, no matter how heavy they are.

"We were completely surprised to find that mice that became extremely obese had no arthritis if their bodies didn't have leptin," said Farshid Guilak, Ph.D., director of orthopaedic research in the Duke Department of Surgery. "Although there was some earlier evidence that leptin might be involved in the arthritis disease process, we didn't think that there would be no arthritis at all."

In fact, the joints from the obese mice in the study appearing in the journal Arthritis & Rheumatism looked better than those of the normal control mice, Guilak said. "However, in another study, we found that mice that gained half as much weight on a high-fat diet but processed leptin normally showed significant knee osteoarthritis."

Leptin influences many of the factors involved in osteoarthritis--body weight, inflammation, sex hormone levels, and bone metabolism, said lead author Tim Griffin, Ph.D., who was at Duke Orthopaedic Department and now is an assistant member of the Free Radical Biology and Aging Program at the Oklahoma Medical Research Foundation. "That also makes leptin challenging to study, however, because it's difficult to isolate which pathway is being altered to prevent the development of osteoarthritis."

Leptin is a well-known regulator of appetite, but this is the first time scientists have reported a role for leptin as a metabolic link between obesity and altered cartilage metabolism in joints.

The role of obesity as a risk factor for arthritis is well characterized, but it was thought to be merely a case of overloading joints with extra weight. "It hadn't been studied beyond that," Guilak said. "We knew from other studies that obese people got arthritis in their hands, too, which don't bear weight. This indicated that something besides just body-weight level affected their joints."

The Duke team set out to learn whether the increased body fat of obesity causes an inflammatory response in joints an imbalance of the immune system signaling proteins called cytokines and other chemicals in osteoarthritis.

They studied mice that were leptin-deficient or deficient in leptin receptors mice that didn't have any effective leptin in their bodies. Both types of mice overate and gained weight. Then they compared the study mice with normal mice to document knee osteoarthritis. The measurements included pro- and anti-inflammatory cytokines present in arthritis, and several tests to assess bone changes in the knees of the mice.

The knee bones of the leptin-free, obese mice did change, but without forming osteoarthritis. The levels of inflammatory cytokines, which correlate with arthritis, were largely unchanged in these mice. The results suggested that leptin may have a dual role in the development of osteoarthritis by regulating both the skeletal and immune systems.

What does this mean for people? "Obesity is still the number one preventable risk factor of osteoarthritis, but now it seems body fat by itself is not what is causing it," Guilak said. "If you are obese, there are benefits to losing weight in terms of arthritis. For example, if you are obese and lose just 10 pounds, pain decreases significantly. Pain modulation is another clue it might be a chemical or systemic metabolic effect, rather than just a mechanical effect of less weight on the joints."

As with many studies that yield unanticipated findings, "we have a lot of additional questions and experiments that need to be done to further understand how leptin mediates the development of osteoarthritis," Griffin said.

"With obesity and osteoarthritis, there are good similarities between humans and mice," Guilak said. "If we can find a pathway that links a high-fat diet with arthritis, then we can try to identify and block the inflammatory mediators that are linked with the dietary fat."


'/>"/>

Contact: Mary Jane Gore
mary.gore@duke.edu
919-660-1309
Duke University Medical Center
Source:Eurekalert

Related medicine news :

1. New prion protein discovered by Canadian scientists may offer insight into mad cow disease
2. Scientists Probe Sepsis Deadly Secrets
3. Scientists puzzled by severe allergic reaction to cancer drug in the middle Southern US
4. Scientists Develop Natural Protection for Stored Foods
5. Scientists detect presence of marburg virus in african fruit bats
6. Scientists Spot Brains Free Will Center
7. Scientists ID Likely Culprit in Popcorn Lung
8. Scientists explain how insulin secreting cells maintain their glucose sensitivity
9. Scripps Research scientists shed new light on how antibodies fight HIV
10. Scientists, physicians present latest findings in personalized cancer treatment and prevention
11. Scientists demonstate link between genetic variant and effectiveness of smoking cessation meds
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/24/2017)... ... February 24, 2017 , ... The Radiology Business Management Association ... marketing programs at the annual Building Better Radiology Marketing Programs conference, held ... in Fort Worth, Texas. Nine awards are given out in five categories. They are:, ...
(Date:2/24/2017)... (PRWEB) , ... February 24, 2017 , ... ... in Charlevoix, once again hosted their Military Wedding Giveaway, with the winning couple ... by Castle Farms with services generously donated from local vendors: A Matter of ...
(Date:2/23/2017)... CO (PRWEB) , ... February 23, 2017 , ... The ... announce the winner of the 2016 National Education Policy Center Bunkum Award. We invite ... reviewed in 2016. , This year’s Bunkum winner is the Center for American Progress ...
(Date:2/23/2017)... ... February 23, 2017 , ... The American Cleft Palate-Craniofacial Association (ACPA) is pleased ... KLS is a longtime supporter of the event. , "We are pleased that KLS ... Dr. Bob Havlik, 2017 ACPA President. "KLS Martin has a long track record of ...
(Date:2/23/2017)... ... February 23, 2017 , ... ... , media relations, content marketing, social media management, corporate communications, SEO and cause ... the state and in nearby New Hampshire, Massachusetts and Canada, Rosica will focus ...
Breaking Medicine News(10 mins):
(Date:2/23/2017)... -- Im Rahmen seiner Schlüsselwachstumsstrategie arbeitet die ... chinesischen Provinz Guizhou, 2017 mit dem Angebot von Anreize schaffenden ... Entwicklung einer eingebetteten Hightech-Schlüsselindustrie. Foto - http://mma.prnewswire.com/media/471342/First_CRH__CHina_Railway_High_Speed__Train_Enters_Guian.jpg ... ... ...
(Date:2/23/2017)... Research and Markets has announced the addition ... report to their offering. ... The latest research Fibromyalgia Drugs Price Analysis and ... global Fibromyalgia market. The research answers the following questions: ... Fibromyalgia and their clinical attributes? How are they positioned in the ...
(Date:2/23/2017)... Regulus Therapeutics Inc . (Nasdaq: RGLS), ... innovative medicines targeting microRNAs, today announced it will release ... Thursday, March 2, 2017 after the market closes. ... on March 2, 2017 at 5:00 p.m. Eastern Time ... results and provide a general business update.  A live ...
Breaking Medicine Technology: