Clarifying the Role of Fat in Osteoarthritis
In the past, it was thought that obesity, which dramatically increases the risk of osteoarthritis, caused cartilage to break down simply by putting more weight, and thus more force, on the joint.
But excess fat may take a toll in another way, too. Fat is a metabolically active tissue that secretes cytokines, or signaling molecules, that can trigger inflammation.
An increase in cytokines may help to explain why, for example, obesity increases the risk not only for osteoarthritis in the knees, which would be directly impacted by the increased load, but also in the wrist, which is not a weight-bearing joint.
“I think we tend to lump all cases of osteoarthritis as one disease,” Dr. Guilak said. “But we know that the risk of OA is increased by a host of things like injury or joint angle or obesity.”
“If we can find out what it is about being obese that causes joint degeneration, beyond the simple solution of losing weight, then you can target the culprit, and it may not be the weight itself,” he adds.
Experiments in progress include studies testing the effects of exercise and weight loss on knee pain in people and testing the effects of different types of diet and exercise on the joints of mice.
"Excess body fat increases the risk of osteoarthritis. This work is beginning to tell us why.” --John A. Hardin, MD, Chief Scientific Officer of the Arthritis Foundation
Read the other articles in the July/August issue of Research Update: