Endothelin 1 promotes osteoarthritic cartilage degradation via matrix metalloprotease 1 and matrix metalloprotease 13 induction
Bibliographic record
Abstract
OBJECTIVE: Degradation of the collagenous extracellular matrix by metalloproteases (MMPs) plays an important role in the pathogenesis of osteoarthritis (OA). Recently, it was suggested that endothelin 1 (ET-1), a potent vasoconstrictor, may be involved in MMP regulation. This study investigated the role of ET-1 in OA cartilage degradation. METHODS: We explored ET-1 expression and synthesis in normal and OA cartilage and synovial membrane by reverse transcription-polymerase chain reaction and immunohistochemistry. MMP-1 and MMP-13 gene expression and protein synthesis were investigated using Northern blotting and enzyme-linked immunosorbent assays. Additionally, ET-1-induced collagenase activity, type II collagen metabolites, and tissue inhibitor of metalloproteases 1 (TIMP-1) protein were evaluated. RESULTS: We found expression and synthesis of ET-1, in situ, in both normal and OA cartilage and synovial membrane. We demonstrated that ET-1 induced gene expression and protein synthesis of both MMP-1 and MMP-13. These enzymes were produced in OA chondrocyte cultures, and the production increased in a dose-dependent manner in the presence of ET-1. In OA cartilage, ET-1 also induced type II collagen-derived neoepitopes concomitantly with an increase in collagenase activity and a decrease in TIMP-1 protein. CONCLUSION: Our results provide strong evidence of the catabolic role of ET-1 in OA cartilage via MMP-1 and MMP-13 up-regulation. As well, ET-1 increased the net MMP/TIMP balance and secondarily increased collagen degradation. Hence, ET-1 becomes an attractive factor to target in the conception of new therapeutic approaches for OA and other diseases in which MMP-13 and MMP-1 actions are crucial in tissue alteration.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".