Migration of Human Monocytes is stimulated by Jagged-1 and DLL-4 via the Notch Pathway

The Notch signaling pathway is a well-conserved signaling pathway. As known so far Notch signaling is engaged in physiological processes in lung cancer and pulmonary hypertension (PAH). As shown recently, a significant increase of perivascular numbers of macrophages (CD68(+) and monocytes (CD14(+) can be observed in PAH. The aim of this study was to elucidate the role of the Notch signaling pathway in the migration of human monocytes.

Human monocytes were isolated from venous blood, taken from healthy donors. For the chemotactic assays modified 48-well microchemotaxis chambers were used. Cells migrated through a 5 µm pore sized cellulose membrane filter for 45 min in a humidified atmosphere against a gradient of the substances tested (fMLP, Jagged-1, DLL-4). Migration depth of the cells was quantified microscopically by measuring the distance [µm] from the surface of the filters to the leading front of the cells.

The Notch ligands DLL-4 and Jagged-1 significantly stimulated direct and indirect migration in a dose dependent manner revealing a maximal effect at 100ng/ml. The effect was comparable with the maximal stimulation elicited by the well-known chemoattractants fMLP and MCP-1 (10 – 8 M). Via checkerboard assay was shown, that monocytes migrate in a chemotactic and chemokinetic manner. Interestingly, at least 30 min of preincubation was necessary to induce chemokinesis. Inhibition of migration was reached by preincubation of cells with ADAM 17.

Jagged-1 and DLL-4 stimulated migration of human monocytes in vitro. Thus, it can be expected, that Jagged-1 and DLL-4 are involved in innate and adaptive immunological responses in PAH. Consequently, the Notch pathway may serve as a new therapeutic target in future.