Study Uncovers Why Some Joints Stiffen With Age

Mechanism behind osteoarthritis could inform new treatments

Caught in the middle of a one-on-one soccer game, a white-haired man stands with his foot on a soccer ball, a small child faces him, poised to take the ball.
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Researchers in the United States and Japan have discovered a new mechanism that links age-related cartilage tissue stiffening with the repression of a key protein associated with longevity. These findings enhance the understanding of mechanisms that lead to the deterioration of joints that causes osteoarthritis, according to the authors of a new study, published Jan. 10 in Nature Communications.

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In the study, researchers showed that increased stiffening of the extracellular matrix — a network of proteins and other molecules that surround and support tissues in the body — led to a decrease in a so-called longevity protein called Klotho (α-Klotho) in knee cartilage, brought about by epigenetic changes, or how DNA is organized and regulated. This Klotho decrease then damaged cells in healthy cartilage called chondrocytes. Conversely, exposing aged chondrocytes to a softer extracellular matrix restored the knee cartilage to a more youthful state.