Researchers at Duke University were surprised to find a possible link between leptin and osteoarthritis (OA). Leptin is a hormone in the body that regulates appetite; it also influences known OA risk factors, such as body weight, inflammation, sex hormones and bone metabolism.

The study examined leptin-deficient mice in comparison with a healthy control group. These mice ate too much and became obese. However, they showed no indicators of osteoarthritis in their joints, while the mice in the control group did show OA indicators.

The Duke team’s original goal had been to show whether obesity triggers inflammation in the joints, specifically looking for imbalances in proteins called cytokines, a tell-tale sign of OA. They measured pro- and anti-cytokines in the mice’s joints, as well as other orthopedic changes. The leptin-deficient mice showed no change in cytokine levels.

“We were completely surprised to find that mice that became extremely obese had no arthritis if their bodies didn’t have leptin,” said Dr. Farshid Guilak, director of orthopedic research at Duke. “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.

“Obesity is still the number one preventable risk factor of osteoarthritis,” Guilak wanred, “but now it seems body fat by itself is not what is causing it.” He said that additional research is needed to more fully understand the connection between leptin and OA.

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