Locking endothelial junctions blocks leukocyte extravasation, but not in all tissues

Area of Science:

• Immunology
• Cell Biology
• Vascular Biology

Background:

• Leukocyte transmigration across blood vessel walls is crucial for inflammation.
• The exact pathway (paracellular vs. transcellular) of leukocyte diapedesis remains debated.
• Understanding these mechanisms is key to modulating inflammatory responses.

Purpose of the Study:

• To investigate the predominant pathway of leukocyte transmigration.
• To determine the role of VE-cadherin-α-catenin in regulating endothelial junctions and diapedesis.
• To explore potential tissue-specific differences in leukocyte extravasation.

Main Methods:

• Utilized a VE-cadherin-α-catenin fusion protein to lock endothelial junctions.
• Assessed leukocyte diapedesis in various tissues (lung, skin, cremaster, lymph nodes, peritoneum).
• Analyzed the impact of the fusion protein on endothelial junction integrity and leukocyte migration.

Main Results:

• The VE-cadherin-α-catenin fusion protein significantly reduced leukocyte diapedesis in lung, skin, and cremaster tissues.
• This reduction established the paracellular route as the major transmigration pathway in these specific tissues.
• Homing of lymphocytes into lymph nodes and neutrophil extravasation in the peritoneum were unaffected by the fusion protein.

Conclusions:

• The paracellular route is the predominant pathway for leukocyte transmigration in many tissues.
• Tissue-specific mechanisms regulate leukocyte diapedesis, highlighting the complexity of the inflammatory response.
• The cadherin-catenin complex plays a dynamic role in controlling endothelial junctions and leukocyte extravasation.