Phytochemicals May Protect Cartilage, Prevent Pain in Joints

Johns Hopkins researchers have discovered that plant-derived compounds known for their ability to protect tissue also appear to block the activity of an enzyme that triggers inflammation in joints.

Their findings could lead to new arthritis treatments and better methods of making artificial cartilage.

The discovery was detailed in a paper published in the Sept. 27 edition of Proceedings of the National Academy of Sciences.

"The beneficial phase 2 enzymes somehow seemed to prevent the activation of the inflammatory COX-2 enzyme," said Zachary R. Healy, a doctoral student and lead author of the journal paper. "The phase 2 enzymes inhibited the inflammation and the apoptosis -- the cellular suicide we'd observed."

Some prescription drugs like Vioxx keep COX-2 enzyme at bay by temporarily blocking its ability to send the biochemical signals that set off pain and inflammation. When the medication is stopped, however, the stockpiled COX-2 enzyme can resume its damaging ways. Unlike these traditional pain killers, Healy said, the phase 2 enzyme inducers seemed to stop the increasing activity of COX-2 enzyme.

"That means these compounds could be useful as a preventive measure, perhaps before strenuous exercise," Healy said. "This has the potential for stopping pain and inflammation before they start."

Phase 2 enzymes can detoxify certain cancer-causing agents and damaging free radicals in tissue, including cells that line blood vessels. These phytochemicals can be found in cruciferous plants, including broccoli.

By showing a way to ward off inflammation and by providing insights into the effects of shear stress, the new chondrocyte research may also aid tissue engineers who are trying to grow artificial cartilage or seeking to revitalize human cartilage in the lab. This is important because human bodies cannot make new cartilage to replace tissue that's lost to injury or disease.

Funding for the research was provided by a DuPont Young Professor Award, a National Science Foundation Graduate Research Fellowship and an Achievement Reward for College Students Fellowship. Healy's co-authors on the PNAS paper were Talalay, Konstantopoulos, Norman H. Lee of the Institute for Genomic Research, Xiangqun Gao of the Department of Pharmacology and Molecular Sciences at the Johns Hopkins School of Medicine, Mary B. Goldring of the Harvard Institutes of Medicine, and Thomas W. Kensler of the Department of Environmental Health Sciences in the Johns Hopkins Bloomberg School of Public Health.