ICAM-1-mediated endothelial nitric oxide synthase activation via calcium and AMP-activated protein kinase is required...

Area of Science:

• Immunology
• Cell Biology
• Vascular Biology

Background:

• The vasculature acts as a gatekeeper for leukocyte trafficking, a critical immune function.
• Previous research identified ICAM-1-mediated VEC phosphorylation as a control point for lymphocyte migration.

Purpose of the Study:

• To investigate the role of endothelial nitric oxide synthase (eNOS) in ICAM-1-mediated lymphocyte transendothelial migration.
• To elucidate the signaling pathway regulating eNOS activity during leukocyte trafficking.

Main Methods:

• Investigated eNOS phosphorylation at S1177 in response to ICAM-1 stimulation.
• Utilized functional neutralization of pathway components (src kinase, rho GTPase, Ca2+, CaMKK, AMPK, guanylyl cyclase) to assess impact on lymphocyte diapedesis.
• Examined T-cell transmigration across primary rat and human microvascular endothelial cells under static and shear flow conditions.

Main Results:

• ICAM-1 stimulated eNOS via a pathway involving src family kinase, rho GTPase, Ca2+, CaMKK, and AMPK, distinct from insulin signaling.
• Neutralization of pathway components or guanylyl cyclase significantly reduced lymphocyte diapedesis.
• NO signaling activation promoted lymphocyte transmigration.
• The eNOS pathway was essential for T-cell transmigration across various endothelial cells and under shear flow.

Conclusions:

• Endothelial nitric oxide synthase (eNOS) is a critical regulator of leukocyte trafficking.
• A novel signaling pathway involving eNOS is essential for lymphocyte diapedesis across the vasculature.
• This pathway provides a key molecular link governing endothelial cell compliance during immune cell migration.