Beneficial effect of resveratrol on phenotypic features and activity of osteoarthritic osteoblasts
Bibliographic record
Abstract
BACKGROUND: Osteoarthritis (OA) is a complex disease, which affects multiple tissues, namely the subchondral bone, articular cartilage and synovial membrane. Alterations of the subchondral bone include an increased, yet under mineralized osteoid matrix, abnormal osteoblast cell phenotype including elevated alkaline phosphatase (ALP) activity, increased release of osteocalcin (OC) and transforming growth factor β-1 (TGF-β1). Previous studies have demonstrated an inhibition of the canonical Wnt signaling (cWnt) pathway in OA osteoblasts (Ob). As resveratrol (RSV) has been shown to upregulate the Wnt signaling pathway in different cell systems, we hypothesized that RSV could be beneficial for OA Ob. METHOD: We prepared primary human Ob using the subchondral bone plate of tibial plateaus of OA patients undergoing total knee arthroplasty, or tibial plateaus of normal individuals at autopsy. Sirtuin 1 (Sirt1) expression in normal and OA subchondral bone tissue was evaluated by immunohistochemical analysis. Expression of genes was evaluated by qRT-PCR and protein production by western blot analysis. ALP activity and osteocalcin secretion were evaluated respectively with substrate hydrolysis and enzyme immunoassay. Mineralization levels were evaluated with alizarin red staining. Wnt/β-catenin signaling was evaluated by target gene expression using the TOPflash TCF/lef luciferase reporter assay and intracellular signaling using β-catenin levels in western blot analysis. Extracellular signal-regulated kinase (Erk)1/2 and the Smad1/5/8 pathways were evaluated by western blot analysis. RESULTS: Sirt1 expression and production were reduced in OA subchondral bone tissue compared to normal tissue. RSV upregulated Sirt1 and its activity, and reduced the expression of leptin. RSV increased Erk1/2 phosphorylation in OA Ob; however, it had no effect on Smad 1/5/8 phosphorylation. RSV had little effect on cell proliferation and only slightly affected the Bax/Bcl2 ratio. The expression of Runx2/Cbfa1 and peroxisome proliferator-activated receptor (PPAR)γ were not affected by increasing doses of RSV. The endogenous increased ALP activity and OC release observed in OA Ob compared to normal Ob were partly corrected only for ALP at high RSV levels but not for OC release. In contrast, RSV increased the mineralization of OA Ob. Moreover, whereas Wnt3a stimulates the Wnt/β-catenin pathway in these cells, RSV further increased the response to Wnt3a. CONCLUSION: These data indicate that RSV promotes Sirt1 levels, inhibits the endogenous expression of leptin by OA osteoblasts and can promote the Wnt/β-catenin and Erk1/2 signaling pathways, which are altered in these cells.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".