Endothelium-Derived 5-Methoxytryptophan Protects Endothelial Barrier Function by Blocking p38 MAPK Activation

Area of Science:

• Vascular Biology
• Endocrinology
• Inflammation Research

Background:

• Endothelial barrier integrity is crucial for preventing inflammation and vascular damage.
• Disruption of this barrier by endotoxins, cytokines, or growth factors contributes to vascular diseases.
• The role of endothelium-derived molecules in maintaining barrier function requires further elucidation.

Purpose of the Study:

• To investigate the potential role of endothelial cells in releasing protective factors against barrier disruption.
• To identify novel anti-inflammatory molecules produced by endothelial cells.
• To elucidate the mechanism by which these molecules protect endothelial barrier function.

Main Methods:

• Metabolomic analysis of human umbilical vein endothelial cell (HUVEC)-conditioned medium.
• Enzyme-linked immunosorbent assay (ELISA) for molecule detection.
• In vitro assays assessing endothelial hyperpermeability and VE-cadherin expression.
• In vivo studies using a murine model of LPS-induced microvascular permeability.

Main Results:

• 5-methoxytryptophan (5-MTP) was identified as an anti-inflammatory factor in HUVEC-conditioned medium.
• 5-MTP prevented endothelial hyperpermeability and VE-cadherin downregulation induced by inflammatory mediators.
• 5-MTP protected endothelial barrier function by inhibiting p38 MAPK activation.
• Administration of 5-MTP significantly reduced vascular permeability in vivo.

Conclusions:

• 5-methoxytryptophan (5-MTP) is an endothelium-derived molecule that safeguards endothelial barrier function.
• 5-MTP exerts its protective effects by blocking p38 MAPK signaling.
• These findings identify 5-MTP as a potential therapeutic target for vascular diseases.