Adhesion of B Cell Lines to Endothelial Cells from Human Lymphoid Tissue Modulates Tyrosine Phosphorylation and Endothelial Cell Activation

Abstract

Through the production of cytokines and growth factors the endothelium of secondary lymphoid organs plays a crucial role in controlling lymphocyte migration to the lymphoid microenvironment, an essential step in the initiation of the immune response. Here we demonstrate that direct contact of B cell lines with tonsil-derived human endothelial cells resulted in changes in the phosphorylation state of endothelial cells, causing their functional activation. We found a rapid (<15-s) and transient dephosphorylation, followed by a rapid rephosphorylation of tyrosine residues of the focal adhesion kinase, paxillin, and ERK2. Maximal rephosphorylation occurred after 15–30 min of B cell contact. Preincubation of lymphoid B cells with an adhesion-blocking Ab directed against α4β1 integrin abrogated adhesion-mediated changes of endothelial cell tyrosine phosphorylation, suggesting that cell contact was essential. Similar patterns of tyrosine phosphorylation, but with slightly different kinetics were induced after cross-linking of β1 integrin or CD40 on endothelial cells. Functional activation of endothelial cells by B cell adhesion was confirmed by the production of IL-6, IL-8, monocyte chemoattractant protein-1, M-CSF, and macrophage inflammatory protein-1β mRNA. However, direct cross-linking of β1 integrin and CD40 failed to accomplish the same functional activation. These data indicate that direct contact of lymphoid B cells with the endothelium from lymphoid tissue induce endothelial cell signaling, resulting in chemokine and cytokine production. This phenomenon may provide a mechanism for the remodeling of the endothelium from lymphoid tissues, thus contributing to the free migration of lymphocytes and other cells into the lymphoid organs.

Eosinophil adhesion under flow conditions activates mechanosensitive signaling pathways in human endothelial cells

“…It is increasingly appreciated that the endothelium actively participates in leukocyte recruitment ( 53 ). Studies have shown that leukocyte adhesion can activate endothelial cell signaling pathways ( 5 – 8 , 25 , 54 , 55 ), some of which can promote subsequent leukocyte transmigration ( 5 – 8 , 10 , 54 ). Our data further support an active role for the endothelium in leukocyte transmigration and present the first evidence that mechanotransduction through lumenal adhesion molecules is important for leukocyte transmigration under shear conditions.…”

Expression of a family of noncoding mitochondrial RNAs distinguishes normal from cancer cells

“…Total RNA from cells and isolated mitochondria was extracted as described before (4,18,19). RNA was treated with TurboDNAfree (Ambion), according to manufacturer's directions.…”

“…HeLa, MDA-MB-231, OVCAR3, Jurkat, and HUVEC cells were cultured according to American Type Culture Collection recommendations. HFK and HUTEC were cultured as described before (3,4). Isolated human lymphocytes were cultured for 48 h without or with 10 g/mL phytohaemagglutinin (PHA) as described before (2).…”

The CD40-Induced Signaling Pathway in Endothelial Cells Resulting in the Overexpression of Vascular Endothelial Growth Factor Involves Ras and Phosphatidylinositol 3-Kinase

“…Bavendiek et al (34) examined the ability of CD40-CD40L interactions to regulate the expression of tissue factor, and found that ligation of CD40 on EC results in the activation of the transcription factors AP-1, NF-B, and Egr-1. Reyes et al (35) determined that cell surface CD40L on B cells interacts with EC CD40, resulting in the dephosphorylation and rephosphorylation of focal adhesion kinase, paxcillin, and extracellular signalregulated kinase-2. And, more recently, Deregibus et al (36) reported that ligation of CD40 on EC results in phosphorylation of Akt, Akt-dependent EC proliferation, and tube formation.…”