The Role of TIMP3 in Microvascular Endothelial Cell‐Extracellular Matrix Interaction and Regulation of Microvascular Barrier Function
Bibliographic record
Abstract
Background During sepsis, disruption of the pulmonary microvascular endothelial cell (PMVEC) barrier is associated with lung dysfunction and death. PMVEC‐PMVEC interactions through adherens and tight junctions are crucial for maintaining barrier function, as disruption of these junctions causes protein leak. Multiple mechanisms support PMVEC junctional and barrier function, including PMVEC binding to the extracellular matrix (ECM). Data suggest that decreased PMVEC‐ECM interactions under pro‐inflammatory conditions, indicated by altered focal adhesion kinase (FAK) phosphorylation, may be associated with increased leak. Tissue inhibitor of metalloproteinases 3 (TIMP3) is shown to regulate barrier function as PMVEC from Timp3 −/− mice have increased leak; however, the specific mechanisms are unknown. Interestingly, previous studies in the developing lung found that TIMP3 can mediate PMVEC‐ECM interactions. Based on this, I hypothesized that TIMP3 maintains PMVEC barrier function by promoting PMVEC‐ECM interactions. Method PMVEC from wild type (WT) and Timp3 − / − mice were cultured on different matrices and stimulated with pro‐inflammatory cytokines (sepsis) vs control PBS. PMVEC‐ECM interactions were assessed using adhesion assays, immunocytochemistry, and the XPERT‐permeability assay. Results Examination of PMVEC adhesion to fibronectin, laminin, vitronectin, and collagen I indicated preferential adhesion of WT PMVEC to fibronectin with lowest adhesion to collagen. While Timp3 − / − PMVEC appeared to also preferentially adhere to fibronectin, overall adhesion to the ECM vs. WT PMVEC was reduced. Assessment of phosphorylated FAK (pFAK) through immunocytochemistry revealed reduced abundance of pFAK in both cell types under cytomix‐treatment vs. PBS. Additionally, pFAK organisation and localised distribution around the periphery of cell borders appeared to be reduced in Timp3 − / − vs. WT PMVEC. The XPERT‐permeability assay revealed differences in total inter‐PMVEC avidin fluorescence and specifically avidin leak diffusion distance between PMVEC and the ECM in WT vs. Timp3 − / − cells, especially under cytomix‐treatment. Significance These findings demonstrate that sepsis disrupts the interaction of WT PMVEC with ECM, which is further enhanced in Timp3 − / − cells. The results suggest that TIMP3 may play an important role in regulating PMVEC‐ECM interactions, and could help elucidate therapeutic targets to maintain or rescue PMVEC barrier integrity in sepsis. Support or Funding Information Heart and Stroke Foundation of Ontario, Ontario Thoracic Society Grant‐in‐Aid, NSERC Discovery Grant
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".