Synovial macrophage activation mediates pain experiences in experimental knee osteoarthritis
Bibliographic record
Abstract
Abstract It has been suggested that synovial macrophages mediate nociceptive signals in knee osteoarthritis (OA) but the underlying mechanisms are unknown. Our objectives were to investigate the role of synovial macrophages and their activation via signal transducer and activator of transcription (STAT) signaling in mediating OA pain experiences. We induced experimental OA in rats via knee destabilization surgery and then performed RNA sequencing analysis in sorted synovial macrophages to identify signaling pathways associated with macrophage activation. Next, we repeated intra-articular injections of liposomal clodronate to deplete macrophages, or liposomal inhibitors of STAT1 or STAT6 to block macrophage activation, and tested the effects on local and distal mechanical pain sensitivity. We also assessed synovitis, cartilage damage, and synovial macrophage infiltration with histopathology and immunofluorescence, and crosstalk between liposomal drug-treated synovium and articular chondrocytes in co-culture. Most enriched signaling pathways in activated OA macrophages involved STAT signalling. Macrophage depletion and STAT6 inhibition led to marked, sustained improvements in mechanical pain sensitivity and synovial inflammation compared to controls, but macrophage depletion caused increased synovial fibrosis and vascularization. In contrast, STAT1 and STAT6 inhibition in macrophages did not worsen synovial or cartilage pathology. In crosstalk assays, macrophage STAT1-inhibited synovium caused the greatest increases in the expression of anabolic and catabolic chondrocyte genes and sulphated glycosaminoglycan secretion in chondrocytes. Our results suggest that synovial macrophages play a key role in mediating pain experiences in experimental knee OA, and that selectively blocking STAT6 in synovial macrophages may reduce OA-related pain without accelerating joint tissue damage. (248/250) One Sentence Summary Selective drug targeting to synovial macrophages improves pain experiences in surgical joint destabilization-induced experimental rodent knee OA. (145/150)
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".