Activation of the NOTCH signaling pathway stimulates migration of human b-lymphocytes

The NOTCH signaling pathway is essentially required for embryonic development, cell differentiation, as well as for maintenance of tissue homeostasis and stem cell function. Consequently, dysfunction of the NOTCH pathway is associated with several genetic diseases or cancer development. Engagement in inflammatory disorders is under investigation. We explored whether the NOTCH ligands Jagged-1 and Delta-like-4 might affect migration of human B-lymphocytes in vitro.

B-lymphocytes were isolated from EDTA-anticoagulated venous blood of healthy volunteers. For migration assays 5 µm pore sized nitrocellulose membrane filters and a modified 48 well microchemotaxis chamber were used. After an incubation period of 90 minutes in a humified atmosphere, the distances cells migrated were measured microscopically, and the “Chemotactic Index” (CI) was defined as the ratio between the distance cells migrated towards the NOTCH ligands tested and that towards control medium. Additionally, migration behavior was investigated after preincubation of cells with the γ-secretase inhibitor DAPT and ADAM17. Both revealed the direct engagement of the NOTCH signaling pathway.

We report for the first time that the NOTCH ligands Jagged-1 and Delta-like-4 significantly stimulate the migration of human B-lymphocytes in vitro. The observed effects were comparable to the maximal effects elicited by the well-known chemoattractant fMLP. Furthermore, preincubation of cells with DAPT and ADAM17 diminished migration. Checkerboard assays showed that B-lymphocytes migrate both, in a chemokinetic and chemotactic manner in response to the NOTCH ligands tested.

In conclusion this study shows that activation of the NOTCH signaling pathway can stimulate migration of B-lymphocytes and thus may serve as a new target in inflammatory pulmonary diseases.