Abstract 988: Tissue Inhibitor Of Metalloproteinase-3 Regulates Myocardial Fibrosis By Regulating The TGFβ-TNF Interaction
Bibliographic record
Abstract
Fibrosis is the outcome of excess deposition of extracellular matrix components and underlies diastolic and systolic heart failure. Metalloproteinases (MMPs and ADAMs) and their inhibitors (TIMPs) are critical regulators of ECM turnover and fibrosis. TIMP3 is a potent inhibitor of MMPs and ADAMs, whereby it regulates tissue proteolysis and cytokine bioavailability. TIMP3 levels are reduced in human heart disease, and we found that mice lacking Timp3 (KO) exhibit severe dilated cardiomyopathy (DCM), extensive interstitial fibrosis and early heart failure (HF) following pressure overload compared to wild type (WT) mice. We showed upregulated TNF signaling within 6 hrs of aortic banding (AB) which when blocked, significantly improved DCM and prevented HF. We then investigated the mechanism underlying the extensive fibrosis despite the increased MMP activity in the TIMP3KO mice. Comparative microarray analyses show a significant upregulation of the TGFβ1 signaling pathway within 6 hrs of AB in KO vs WT hearts. In vivo treatment of KO-AB mice with a TGFβ1-neutralizing antibody (1D11) completely abolishes fibrosis, markedly improves left ventricular dilation, systolic and diastolic heart function (LVEDD(mm): 4.3 ± 0.1 in WT, 5.4 ± 0.1 in KO, 4.7 ± 0.1 in KO+ 1D11; fractional shortening(%): 40.2 ± 1.7 in WT, 19.6 ± 2.2 in KO, 36.2 ± 0.7 in KO+ 1D11; E/Ac ratio: 2.5 ± 0.3 in WT, 1.8 ± 0.3 in KO, 2.4 ± 0.2 in KO + 1D11; n = 22, P < 0.05). Interestingly, blocking TGFβ1 also prevented the early rise in TNF in KO hearts. Using primary neonatal culture systems, we found that cardiomyocyte-fibroblast interaction is essential for a fibrotic response to agonists (Ang II, PE). Further, KO co-cultures generate a 5-fold greater fibrosis (P < 0.05) through activation of Smad2/3 pathway compared to WT. TGFβ also regulates TNF transcription more potently in KO cells since a 3-fold higher TNF induction occurred in response to recombinant TGFβ1 in KO vs WT co-cultures (P < 0.05). In conclusion, TIMP3 is a critical regulator of TGFβ1 and TNF, and its deficiency induces parallel dysregulations in the signaling of these cytokines very early after pressure overload, leading to severe interstitial fibrosis and DCM, hence, TIMP3-based therapies can simultaneously impact fibrosis and DCM.
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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) | 0.000 | 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) | 0.000 | 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".