Medicine & Health
Osteoarthritis: Reimagining the “Wear and Tear” Disease By Henry Bryant
Image by Manuel González Reyes .[CC0]
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lthough rheumatoid arthritis may be more recognizable to many, osteoarthritis actually affects more people; it is the leading cause of pain and disability in older adults.1 Rheumatoid arthritis is an autoimmune disease, meaning the body’s immune system mistakenly tries to destroy healthy tissue. For rheumatoid arthritis, this includes cells in joint tissues. Osteoarthritis, on the other hand, is commonly misidentified as the “wear and tear” arthritis due to the disease’s prevalence in older individuals, especially after joint injury.2 However, recent research has uncovered complex, intertwined molecular signaling pathways and feedback loops involved in osteoarthritis, changing the medical community’s perception of the disease entirely. These pathways, rather than strictly the mechanical erosion of joint tissues, cause the joint pain and disability associated with the disease.
Dr. Richard Loeser Jr., MD
Dr. Richard Loeser, an Eminent Professor of Medicine in the Division of Rheumatology, Allergy, & Immunology at UNC-Chapel Hill and Director of the Thurston Arthritis Research Center, has played a central role in this shift. Dr. Loeser’s lab uses a combination of human joint tissue and mouse models to study osteoarthritis. Joint tissue taken from both healthy young patients and older patients with osteoarthritis facilitate the discovery of physiological processes and potential biomarkers of the disease. Researchers in the Loeser Lab also activate cellsignaling molecules in healthy tissues in an attempt to study relevant pathways when osteoarthritis is induced. Both techniques highlight molecules and pathways of interest that present starting points for further investigation. The researchers then explore the complex interactions of these signaling pathways in mouse models. Mouse models provide a more realistic picture of what happens inside the human body that tissue samples alone cannot emulate, and many mouse pathways mirror pathways found in the human body. Additionally, an array of biochemical techniques elucidate upstream and downstream molecules in the signaling pathways for a more complete biological picture in mice. One of these techniques involves knocking out specific genes in a pathway to see the effects on other molecules downstream. Together, these studies led Loeser and his lab to discover a specific positive feedback loop that contributes to osteoarthritis. First, mechanical trauma, over-
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