title: Human RPE-monocyte co-culture induces chemokine gene expression through activation of MAPK and NIK cascade.
abstract: Cell-cell contact between human retinal pigment epithelium (hRPE) cells and monocytes occurs in many retinal diseases involving blood-retinal barrier breakdown. This study investigates chemokine secretion induced by co-culture of hRPE cells and monocytes and illustrates the roles of p38 kinase, ERK, JNK/SAPK and NF-kappaB-inducing kinase signaling pathways for hRPE IL-8 and MCP-1 secretion induced in hRPE by co-culture with monocytes. Co-culture of hRPE cells with monocytes increased steady-state IL-8 and MCP-1 mRNA and protein secretion. Stimulation of hRPE cells by monocytes resulted in prominent increases in p38, ERK1/2 and JNK/SAPK phosphorolation, IkappaBalpha degradation, and NF-kappaB nuclear translocation. The induced IL-8 and MCP-1 proteins were almost completely supporessed by U0126, a specific mitogen-activated protein kinase kinase (MEK) inhibitor, or by SB203580, a selective p38 inhibitor. Chemokine secretion was completely blocked by simultaneous administration of U0126 and SB203580. Induction of IL-8 and MCP-1 was abrogated by Ro318220, an inhibitor of PKC, as well as by genistein or herbimycin A, inhibitors of PTK. In addition, anti-inflammatory drugs dexamethasone (DEX) and cyclosporin A (CSA) both blocked activation of JNKS/SAPK and the cell-cell contact induced production of hRPE IL-8 and MCP-1, while activation of p38 and ERK was only inhibited by DEX, but not by CSA. These results suggest that activation of DEX-sensitive, CSA-resistant MEK/ERK and p38 pathways, and activation of NF-kappaB, PKC, and PTK are essential for IL-8 and MCP-1 expression by hRPE cells.
authors.affiliation: Department of Ophthalmology, University of Michigan, Ann Arbor, MI 48105, USA.
authors.forename: Zong-Mei
authors.initials: ZM
authors.lastname: Bian
authors.forename: Susan G
authors.initials: SG
authors.lastname: Elner
authors.forename: Ayako
authors.initials: A
authors.lastname: Yoshida
authors.forename: Victor M
authors.initials: VM
authors.lastname: Elner
mesh_terms: D002450:Cell Communication / Q000502:physiology; D002478:Cells, Cultured; D018925:Chemokines / Q000096:biosynthesis* / Q000235:genetics; D018920:Coculture Techniques; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000166:cytology* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014178:Translocation, Genetic; D000097782:NF-kappaB-Inducing Kinase
chemical_list: D018925:Chemokines; D007166:Immunosuppressive Agents; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D000097782:NF-kappaB-Inducing Kinase