monocyte extravasation

Definition

Target type: biologicalprocess

The migration of a monocyte from the blood vessels into the surrounding tissue. [CL:0000576, GOC:BHF, PMID:10657654]

Monocyte extravasation, the process by which monocytes exit the bloodstream and enter tissues, is a crucial step in both innate and adaptive immune responses. It involves a complex interplay of adhesion molecules, chemokines, and signaling pathways.

1. **Rolling:** Monocytes initially interact with the vascular endothelium through weak, transient interactions mediated by selectins, like L-selectin on the monocyte and E-selectin on the endothelium. This results in the rolling of monocytes along the blood vessel wall.

2. **Activation:** Chemokines, like CCL2 (MCP-1), are released by inflamed tissues and attract monocytes. These chemokines bind to chemokine receptors on monocytes, triggering intracellular signaling cascades that activate integrins.

3. **Adhesion:** Activated integrins, like LFA-1 and Mac-1, on monocytes bind to their respective ligands, ICAM-1 and ICAM-2, on the endothelial cells. This interaction leads to firm adhesion of monocytes to the endothelium.

4. **Diapedesis:** Monocytes then migrate between endothelial cells, a process called diapedesis. This movement involves the reorganization of the cytoskeleton and the interaction of monocytes with junctional proteins on the endothelial cells.

5. **Migration:** Once in the tissues, monocytes are guided by chemokine gradients towards the site of inflammation or injury. They differentiate into macrophages or dendritic cells, depending on the microenvironment, and perform their effector functions, such as phagocytosis, antigen presentation, and cytokine production.

Monocyte extravasation is a tightly regulated process that ensures efficient delivery of these immune cells to the appropriate location. Dysregulation of this process can contribute to various inflammatory disorders, such as atherosclerosis and autoimmune diseases.'
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Proteins (1)

Compounds (19)