Peripheral serotonin lacks effects on endothelial adhesion molecule expression in acute inflammation

Area of Science:

• Immunology
• Vascular Biology
• Biochemistry

Background:

• Peripheral, non-neuronal serotonin influences neutrophil recruitment to inflammatory sites.
• While serotonin's direct effects on neutrophils are known, its impact on endothelial cells in inflammation is unclear.

Purpose of the Study:

• To determine if serotonin modulates endothelial cell function in leukocyte recruitment during acute inflammation.

Main Methods:

• Utilized murine models of acute inflammation (LPS injection, mesenteric ischemia/reperfusion).
• Compared leukocyte recruitment and endothelial adhesion molecule expression in wild-type and Tph1 knockout mice (lacking peripheral serotonin).
• Conducted in vitro studies using human umbilical vein endothelial cells (HUVECs).

Main Results:

• Neutrophil transmigration was impaired in Tph1 knockout mice after LPS injection.
• Leukocyte rolling was reduced in Tph1 knockout mice during mesenteric ischemia/reperfusion.
• Endothelial adhesion molecule expression and serotonin's effect on HUVECs were independent of peripheral serotonin.

Conclusions:

• Inflammatory release of peripheral serotonin is not required for regulating endothelial adhesion molecules.
• Serotonin's role in acute inflammation does not involve direct modulation of endothelial cell adhesion molecule expression.