NLRP3 promotes autophagy of urate crystals phagocytized by human osteoblasts
Bibliographic record
Abstract
INTRODUCTION: Monosodium urate (MSU) microcrystals present in bone tissues of chronic gout can be ingested by nonprofessional phagocytes like osteoblasts (OBs) that express NLRP3 (nucleotide-binding domain and leucine-rich repeat region containing family of receptor protein 3). MSU is known to activate NLRP3 inflammasomes in professional phagocytes. We have identified a new role for NLRP3 coupled to autophagy in MSU-stimulated human OBs. METHODS: Normal human OBs cultured in vitro were investigated for their capacity for phagocytosis of MSU microcrystals by using confocal microscopy. Subsequent mineralization and matrix metalloproteinase activity were evaluated, whereas regulatory events of phagocytosis were deciphered by using signaling inhibitors, phosphokinase arrays, and small interfering RNAs. Statistics were carried out by using paired or unpaired t tests, and the one-way ANOVA, followed by multiple comparison test. RESULTS: Most of the OBs internalized MSU in vacuoles. This process depends on signaling via PI3K, protein kinase C (PKC), and spleen tyrosine kinase (Syk), but is independent of Src kinases. Simultaneously, MSU decreases phosphorylation of the protein kinases TOR (target of rapamycin) and p70S6K. MSU activates the cleavage of microtubule-associated protein light chain 3 (LC3)-I into LC3-II, and MSU microcrystals are coated with GFP-tagged LC3. However, MSU-stimulated autophagy in OBs absolutely requires the phagocytosis process. We find that MSU upregulates NLRP3, which positively controls the formation of MSU-autophagosomes in OBs. MSU does not increase death and late apoptosis of OBs, but reduces their proliferation in parallel to decreasing their competence for mineralization and to increasing their matrix metalloproteinase activity. CONCLUSIONS: MSU microcrystals, found locally encrusted in the bone matrix of chronic gout, activate phagocytosis and NLRP3-dependent autophagy in OBs, but remain intact in permanent autophagosomes while deregulating OB functions.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".