EGFR signalling is critical for maintaining the superficial layer of articular cartilage and preventing osteoarthritis progression

摘要

Introduction: Osteoarthritis (OA) is the most common chronic condition of the joints affecting approximately 27 million adults in the United States alone. The superficial layer of mature articular cartilage is the first line of defence against OA initiation. It has 2–4 layers of flat cells expressing unique molecules, such as proteoglycan 4 (Prg4, lubricin) and contains a fine network of collagen fibrils that are oriented horizontally and parallel to the articular surface [1]. Its multifaceted roles include, but are not limited to, producing lubricant proteins, harbouring chondroprogenitors, resisting shear stresses, serving as a gliding surface, and isolating deeper layers from synovial fluid [1]. In OA, degenerative changes initiate with cellular disorganization, gradual stiffening, and irregular surface of this layer [2–4]. Despite the critical role of superficial chondrocytes in maintaining articular cartilage and in preventing OA, its regulation by growth factors and hormones are still largely unknown.