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Updated: Mar 24, 2026
Visualization of Neutrophil Extracellular Traps in Mesenteric Venules After Mesenteric Ischemia-Reperfusion Injury via Intravital Microscopy
Published on: September 27, 2024
Tissue inhibitor of metalloproteinases 3-dependent microvascular endothelial cell barrier function is disrupted under
Valerie Arpino1, Sanjay Mehta2, Lefeng Wang3
1Centre for Critical Illness Research, Lawson Health Research Institute, London, Ontario, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.
Abstract:
Sepsis is associated with dysfunction of microvascular endothelial cells (MVEC) leading to tissue edema and multiple organ dysfunction. Metalloproteinases can regulate MVEC function through processing of cell surface proteins, and tissue inhibitor of metalloproteinases 3 (TIMP3) regulates metalloproteinase activity in the lung following injury. We hypothesize that TIMP3 promotes normal pulmonary MVEC barrier function through inhibition of metalloproteinase activity. Naive Timp3(-/-) mice had significantly higher basal pulmonary microvascular Evans blue (EB) dye-labeled albumin leak vs. wild-type (WT) mice. Additionally, cecal-ligation/perforation (CLP)-induced sepsis significantly increased pulmonary microvascular EB-labeled albumin leak in WT but not Timp3(-/-) mice. Similarly, PBS-treated isolated MVEC monolayers from Timp3(-/-) mice displayed permeability barrier dysfunction vs. WT MVEC, evidenced by lower transendothelial electrical resistance and greater trans-MVEC flux of fluorescein-dextran and EB-albumin. Cytomix (equimolar interferon γ, tumor necrosis factor α, and interleukin 1β) treatment of WT MVEC induced significant barrier dysfunction (by all three methods), and was associated with a time-dependent decrease in TIMP3 mRNA and protein levels. Additionally, basal Timp3(-/-) MVEC barrier dysfunction was associated with disrupted MVEC surface VE-cadherin localization, and both barrier dysfunction and VE-cadherin localization were rescued by treatment with GM6001, a synthetic metalloproteinase inhibitor. TIMP3 promotes normal MVEC barrier function, at least partially, through inhibition of metalloproteinase-dependent disruption of adherens junctions, and septic downregulation of TIMP3 may contribute to septic MVEC barrier dysfunction.
Insights
Tissue inhibitor of metalloproteinases 3 (TIMP3) maintains normal pulmonary microvascular endothelial cell (MVEC) barrier function. Septic downregulation of TIMP3 may contribute to sepsis-induced MVEC barrier dysfunction and organ damage.
Area of Science:
- Pulmonary Medicine
- Cell Biology
- Biochemistry
Background:
- Sepsis causes microvascular endothelial cell (MVEC) dysfunction, leading to tissue edema and organ failure.
- Metalloproteinases regulate MVEC function; tissue inhibitor of metalloproteinases 3 (TIMP3) modulates metalloproteinase activity in lung injury.
- TIMP3's role in maintaining normal pulmonary MVEC barrier function is not fully understood.
Purpose of the Study:
- To investigate the role of TIMP3 in regulating pulmonary MVEC barrier function.
- To determine if TIMP3 deficiency exacerbates sepsis-induced lung vascular leak.
- To elucidate the molecular mechanisms by which TIMP3 influences MVEC barrier integrity.
Main Methods:
- Comparison of pulmonary microvascular albumin leak in wild-type (WT) and Timp3(-/-) mice under basal and septic (cecal-ligation/perforation) conditions.
- Assessment of MVEC monolayer permeability using transendothelial electrical resistance and flux assays.
- Analysis of MVEC surface protein localization (VE-cadherin) and response to metalloproteinase inhibition (GM6001).
Main Results:
- Naive Timp3(-/-) mice exhibited higher basal pulmonary microvascular albumin leak than WT mice.
- Sepsis significantly increased lung vascular leak in WT mice, but not in Timp3(-/-) mice.
- Timp3(-/-) MVEC monolayers showed intrinsic barrier dysfunction, which was rescued by metalloproteinase inhibition, suggesting a metalloproteinase-dependent mechanism.
Conclusions:
- TIMP3 is crucial for maintaining normal pulmonary MVEC barrier function.
- Septic downregulation of TIMP3 contributes to MVEC barrier dysfunction.
- Targeting TIMP3 or metalloproteinase activity may offer therapeutic strategies for sepsis-induced vascular injury.
