title: CD40 ligand-activated human monocytes amplify glomerular inflammatory responses through soluble and cell-to-cell contact-dependent mechanisms.
abstract: Monocytes/macrophages play a critical role in the initiation and progression of a variety of glomerulonephritides. We sought to define the interactions between physiologically activated human monocytes and glomerular mesangial cells (MC) by employing a cell culture system that permits the accurate assessment of the contribution of soluble factors and cell-to-cell contact. Human peripheral blood monocytes, primed with IFN-gamma and GM-CSF, were activated with CD40 ligand (CD40L) or TNF-alpha and cocultured with MC. CD40L-activated monocytes induced higher levels of IL-6, monocyte chemoattractant protein-1 (MCP-1) and ICAM-1 synthesis by MC. Separation of CD40L-activated monocytes from MC by a porous membrane decreased the mesangial synthesis of IL-6 by 80% and ICAM-1 by 45%, but had no effect on MCP-1. Neutralizing Abs against the beta 2 integrins, LFA-1 and Mac-1, decreased IL-6 production by 40 and 50%, respectively. Ligation of mesangial surface ICAM-1 directly enhanced IL-6, but not MCP-1, production. Simultaneous neutralization of soluble TNF-alpha and IL-1 beta decreased MCP-1 production by 55% in membrane-separated cocultures of MC/CD40L-activated monocytes. Paraformaldehyde-fixed CD40L-activated monocytes (to preserve membrane integrity but prevent secretory activity), cocultured with MC at various ratios, induced IL-6, MCP-1, and ICAM-1 synthesis by MC. Plasma membrane preparations from activated monocytes also induced mesangial IL-6 and MCP-1 synthesis. The addition of plasma membrane enhanced TNF-alpha-induced mesangial IL-6 production by approximately 4-fold. Together, these data suggest that the CD40/CD40L is essential for optimal effector function of monocytes, that CD40L-activated monocytes stimulate MC through both soluble factors and cell-to-cell contact mediated pathways, and that both pathways are essential for maximum stimulation of MC.
authors.affiliation: Arthritis and Rheumatism Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Bethesda, MD 20892, USA. kuroiwat@arb.niams.nih.gov
authors.forename: T
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: E G
authors.initials: EG
authors.lastname: Lee
authors.forename: C L
authors.initials: CL
authors.lastname: Danning
authors.forename: G G
authors.initials: GG
authors.lastname: Illei
authors.forename: I B
authors.initials: IB
authors.lastname: McInnes
authors.forename: D T
authors.initials: DT
authors.lastname: Boumpas
mesh_terms: D018821:CD18 Antigens / Q000502:physiology; D019013:CD40 Antigens / Q000502:physiology*; D023201:CD40 Ligand; D002450:Cell Communication / Q000276:immunology*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis; D018920:Coculture Techniques; D005920:Glomerular Mesangium / Q000378:metabolism; D005921:Glomerulonephritis / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism / Q000502:physiology; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000276:immunology; D018664:Interleukin-12 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008024:Ligands; D008262:Macrophage Activation; D008562:Membrane Glycoproteins / Q000502:physiology*; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D012995:Solubility; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000276:immunology
chemical_list: D018821:CD18 Antigens; D019013:CD40 Antigens; D018932:Chemokine CCL2; D007375:Interleukin-1; D015850:Interleukin-6; D008024:Ligands; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D023201:CD40 Ligand; D018664:Interleukin-12