F‐spondin, a neuroregulatory protein, is up‐regulated in osteoarthritis and regulates cartilage metabolism <i>via</i> TGF‐β activation
Post-publication record
OpenAlex flags this work as retracted, but it carries no matching Retraction Watch record in this frame.
Bibliographic record
Abstract
In osteoarthritis (OA) articular chondrocytes undergo phenotypic changes culminating in the progressive loss of cartilage from the joint surface. The molecular mechanisms underlying these changes are poorly understood. Here we report enhanced (approximately 7-fold) expression of F-spondin, a neuronal extracellular matrix glycoprotein, in human OA cartilage (P<0.005). OA-specific up-regulation of F-spondin was also demonstrated in rat knee cartilage following surgical menisectomy. F-spondin treatment of OA cartilage explants caused a 2-fold increase in levels of the active form of TGF-beta1 (P<0.01) and a 10-fold induction of PGE2 (P<0.005) in culture supernatants. PGE2 induction was found to be dependent on TGF-beta and the thrombospondin domain of the F-spondin molecule. F-spondin addition to cartilage explant cultures also caused a 4-fold increase in collagen degradation (P<0.05) and a modest reduction in proteoglycan synthesis (approximately 20%; P<0.05), which were both TGF-beta and PGE2 dependent. F-spondin treatment also led to increased secretion and activation of MMP-13 (P<0.05). Together these studies identify F-spondin as a novel protein in OA cartilage, where it may act in situ at lesional areas to activate latent TGF-beta and induce cartilage degradation via pathways that involve production of PGE2.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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 source (direct Gemma or distilled Codex), 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".