Differential role of TIMP2 and TIMP3 in cardiac hypertrophy, fibrosis, and diastolic dysfunction
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Bibliographic record
Abstract
AIMS: Tissue inhibitor of metalloproteinases (TIMPs) can mediate myocardial remodelling, hypertrophy, and fibrosis in heart disease. We investigated the impact of TIMP2 vs. TIMP3 deficiency in angiotensin II (Ang II)-induced myocardial remodelling and cardiac dysfunction. METHODS AND RESULTS: TIMP2(-/-), TIMP3(-/-), and wild-type (WT) mice received Ang II/saline (Alzet pump) for 2 weeks. Ang II infusion resulted in enhanced myocardial hypertrophy and lack of fibrosis in TIMP2(-/-), and conversely, excess fibrosis without hypertrophy in TIMP3(-/-) mice. Echocardiographic imaging revealed preserved ejection fraction in all groups; however, exacerbated left ventricular (LV) diastolic dysfunction was detected in Ang II-infused TIMP2(-/-) and TIMP3(-/-) mice, despite the suppressed Ang II-induced hypertension in TIMP3(-/-) mice. Enhanced hypertrophy in TIMP2(-/-) mice impaired active relaxation, while excess fibrosis in TIMP3(-/-) mice increased LV passive stiffness. Adult WT cardiomyocytes, only when co-cultured with cardiac fibroblasts, exhibited Ang II-induced hypertrophy which was suppressed in TIMP3(-/-) cardiomyocytes. In vitro studies on adult cardiofibroblasts (quiescent and cyclically stretched), and in vivo analyses, revealed that the increased fibrosis in TIMP3(-/-)-Ang II hearts is due to post-translational stabilization and deposition of collagen by matricellular proteins [osteopontin and Secreted Protein Acidic and Rich in Cysteine (SPARC)], which correlated with increased inflammation, rather than increased de novo synthesis. Reduced cross-linking enzymes, LOX and PLOD1, could underlie suppressed collagen deposition in TIMP2(-/-)-Ang II hearts. CONCLUSION: TIMP2 and TIMP3 play fundamental and differential roles in mediating pathological remodelling, independent from their MMP-inhibitory function. TIMP2(-/-) and TIMP3(-/-) mice provide a unique opportunity to study myocardial hypertrophy and fibrosis independently, and their impact on cardiac dysfunction.
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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 | 0.000 |
| 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 it