Endothelial PI 3-kinase activity regulates lymphocyte diapedesis.
Lymphocyte recruitment to sites of inflammation involves a bidirectional series of cues between the endothelial cell (EC) and the leukocyte that culminate in lymphocyte migration into the tissue. Remodeling of the EC F-actin cytoskeleton has been observed after leukocyte adhesion, but the signals to the EC remain poorly defined. We studied the dependence of peripheral blood lymphocyte transendothelial migration (TEM) through an EC monolayer in vitro on EC phosphatidylinositol 3-kinase (PI 3-kinase) activity. Lymphocytes were perfused over cytokine-activated EC using a parallel-plate laminar flow chamber. Inhibition of EC PI 3-kinase activity using LY-294002 or wortmannin decreased lymphocyte TEM (48 +/- 6 or 34 +/- 7%, respectively, vs. control; mean +/- SE; P < 0.05). Similarly, EC knockdown of the p85alpha regulatory subunit of PI 3-kinase decreased lymphocyte transmigration. Treatment of EC with jasplakinolide to inhibit EC F-actin remodeling also decreased lymphocyte TEM to 24 +/- 10% vs. control (P < 0.05). EC PI 3-kinase inhibition did not change the strength of lymphocyte adhesion to the EC or formation of the EC "docking structure" after intercellular adhesion molecule-1 ligation, whereas this was inhibited by jasplakinolide treatment. A similar fraction of lymphocytes migrated on control or LY-294002-treated EC and localized to interendothelial junctions. However, lymphocytes failed to extend processes below the level of vascular endothelial (VE)-cadherin on LY-294002-treated EC. Together these observations indicate that EC PI 3-kinase activity and F-actin remodeling are required during lymphocyte diapedesis and identify a PI 3-kinase-dependent step following initial separation of the VE-cadherin barrier.
Nakhaei-Nejad
Maryam
M
Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.
Hussain
Amer M
AM
Zhang
Qiu-Xia
QX
Murray
Allan G
AG
D000199:Actins / Q000378:metabolism; D000730:Androstadienes / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D018920:Coculture Techniques; D016207:Cytokines / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D047630:Depsipeptides / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D036904:Leukocyte Rolling / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D000077191:Wortmannin; D054460:rho-Associated Kinases / Q000378:metabolism; D000099152:Cadherin 5
D000199:Actins; D000730:Androstadienes; D015703:Antigens, CD; D015820:Cadherins; D002867:Chromones; D016207:Cytokines; D047630:Depsipeptides; D018799:Intercellular Adhesion Molecule-1; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D000077191:Wortmannin; D054460:rho-Associated Kinases; D000099152:Cadherin 5; C057531:jasplakinolide; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one