title: CD40/CD154 ligation induces mononuclear cell adhesion to human renal proximal tubule cells via increased ICAM-1 expression.
abstract: The role of CD40/CD154 ligation in the upregulation of genes of the proinflammatory nuclear factor-kappaB (NF-kappaB) signal transduction pathway was explored in primary cultures of human renal proximal tubule epithelial cells. Using a cDNA gene array specific for human NF-kappaB signal pathway genes, 38 genes were upregulated at 1 h, and 7 of these genes remained upregulated at 3 h. Of these genes, intercellular adhesion molecule-1 (ICAM-1) was explored in further detail. Quantitative real-time PCR for ICAM-1 mRNA expression confirmed the gene array findings. Western blot analysis and quantitative sandwich-enzyme ELISA confirmed this observation at the protein level. A cell-surface ELISA assay showed that ICAM-1 expression doubled by 48 h of CD154 exposure, and fluorescence-activated cell sorter analysis suggested that both the number of cells expressing ICAM-1 and the expression of ICAM-1 on these cells had increased. A cell adhesion assay using fluorescein-labeled human peripheral mononuclear cells showed that ICAM-1 upregulation resulted in increased mononuclear cell adhesion to the monolayer, which was abrogated by pretreatment of the monolayer with a neutralizing ICAM-1 antibody. The p38 mitogen-activated protein kinase (MAPK) inhibitor SB-203580 but not the extracellular signal-regulated kinase 1/2 inhibitor (PD-98059) nor the protein kinase C inhibitor (calphostin) blunted ICAM-1 expression and mononuclear cell adhesion to the monolayer. We conclude that, in human renal proximal tubule epithelial cells, CD40 activation upregulates ICAM-1 (and other NF-kappaB pathway genes) expression with concomitant enhanced adhesion of mononuclear cells, which is mediated via the p38 MAPK signal transduction pathway.
authors.affiliation: Division of Nephrology, Dept. of Medicine, School of Medicine, State University of New York at Stony Brook, NY 11794, USA.
authors.forename: Hongye
authors.initials: H
authors.lastname: Li
authors.forename: Edward P
authors.initials: EP
authors.lastname: Nord
mesh_terms: D019013:CD40 Antigens / Q000502:physiology*; D023201:CD40 Ligand / Q000502:physiology*; D002448:Cell Adhesion / Q000502:physiology*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000502:physiology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis*; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000502:physiology*; D007963:Leukocytes, Mononuclear / Q000502:physiology*; D015398:Signal Transduction; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D019013:CD40 Antigens; D018799:Intercellular Adhesion Molecule-1; D023201:CD40 Ligand; D048051:p38 Mitogen-Activated Protein Kinases