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Carlos Subauste, Jose-Andres Portillo, Isaac Schwatrz, Maria Cecilia Subauste; Pro-inflammatory Responses Induced by CD40 Ligation in Retinal Endothelial Cells and Muller Cells are TRAF Dependent. Invest. Ophthalmol. Vis. Sci. 2013;54(15):135.
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© ARVO (1962-2015); The Authors (2016-present)
CD40 is constitutively expressed in retinal endothelial and Muller cells. CD40 mediates inflammatory disorders and is required for the development of retinopathies induced by ischemia. The signaling pathways by which CD40 triggers pro-inflammatory responses in retinal cells are unknown.
Primary human retinal endothelial and Muller cells were transduced with retroviral vectors that encode wild type CD40 or CD40 with mutations in sites that recruit TNF receptor associated factors (TRAF): TRAF2,3 (ΔT2,3), TRAF6 (ΔT6) or TRAF2,3 plus TRAF6 (ΔT2,3,6). Cells were also incubated with CD40-TRAF2,3 or CD40-TRAF6 blocking peptides. Cells were stimulated with CD154 (CD40 ligand). ICAM-1 and CD40 expression were assessed by flow cytometry. MCP-1 production was examined by ELISA.
CD40 stimulation of retinal endothelial and Muller cells caused ICAM-1 upregulation and MCP-1 production. These responses were ablated in cells that expressed CD40 that cannot recruit TRAFs (CD40 ΔT2,3,6). Blockade of either the TRAF2,3 (CD40 ΔT2,3) or the TRAF6 (CD40 ΔT6) pathway was sufficient to significantly impair ICAM-1/MCP-1 upregulation. Similar results were obtained when cells were incubated with CD40-TRAF2,3 or CD40-TRAF6 blocking peptides.
ICAM-1 and MCP-1 upregulation in retinal endothelial and Muller cells stimulated through CD40 are TRAF dependent. Blockade of a single CD40-TRAF pathway was sufficient to impair these pro-inflammatory responses. Selective blockade of CD40-TRAF signaling may represent an approach to control CD40-driven retinopathies.
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