Cartilage secretes a variety of molecules crucial for its structure, function, and interaction with surrounding tissues. These secretions maintain the integrity of the cartilage and contribute to joint health.
Key Secretions from Cartilage
Chondrocytes, the cells within cartilage, are responsible for producing and secreting the extracellular matrix (ECM). This ECM is comprised of several key components:
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Fibrous Proteins:
- Collagen: A strong, fibrous protein providing structural support. [Reference: 05-May-2014]
- Elastin: An elastic protein contributing to the cartilage's flexibility and resilience. [Reference: 05-May-2014]
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Glycoproteins:
- Lubricin: A glycoprotein that protects cartilage surfaces and facilitates smooth joint movement. [References: https://pubmed.ncbi.nlm.nih.gov/15719068/, https://pmc.ncbi.nlm.nih.gov/articles/PMC548698/]
- Cartilage Oligomeric Matrix Protein (COMP)-derived peptides: Secreted into synovial fluid from wounded cartilage areas. [Reference: https://pmc.ncbi.nlm.nih.gov/articles/PMC8721606/]
- Ucma: A cartilage-specific protein secreted into the extracellular matrix. [Reference: https://www.sciencedirect.com/science/article/pii/S0021925820571470]
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Proteases: In cases of cartilage degradation, such as in osteoarthritis, enzymes like ADAMTS5, MMP13, and CMA1 are secreted, contributing to cartilage breakdown. [References: https://pubmed.ncbi.nlm.nih.gov/39293776/, https://www.oarsijournal.com/article/S1063-4584(24)01397-9/abstract] Other proteins released from damaged cartilage can also trigger synovial pathology. [Reference: https://www.nature.com/articles/s41598-023-45472-x] Clusterin, another protein, is involved in cartilage changes during osteoarthritis. [Reference: https://onlinelibrary.wiley.com/doi/10.1002/jor.24814]
The specific composition and amounts of secreted molecules can vary based on factors like age, health, and the presence of disease. The balance of these secreted components plays a vital role in maintaining cartilage health and joint function.
