Chemokine expression in retinal pigment epithelial cells in response to co-culture with activated T Cells

Purpose: To investigate the effects of T cell-derived cytokines on gene and protein expression of chemokines in a human RPE cell line (ARPE-19). Methods: We used an in vitro co-culture system in which the RPE and CD3/28-activated T cells were separated by a membrane. Differential gene expression in the RPE cells of chemokine genes was quantified using three different microarrays. Protein expression was determined by single- and multiplex ELISA and immunoblotting. Results: Co-culture with activated T cells increased RPE mRNA and protein expression of chemokines CCL2 (MCP-1), CCL5 (RANTES), CCL7 (MCP-3), CCL8 (MCP-2), CXCL1 (GRO-α), IL8 (CXCL8), CXCL9 (MIG), CXCL10 (IP10), CXCL11 (ITAC), and CX3CL1 (fractalkine). The secretion of CCL7 and CXCL9, 10, and 11 was polarized in the apical direction. Using recombinant human cytokines and neutralizing antibodies we identified IFNgamma and TNFalpha as the two major T cell-derived cytokines responsible for the RPE response. For CCL5, CXCL9, 10, 11, 16, and CX3CL1 we observed a synergistic effect of IFNgamma and TNFalpha in combination. CCL20, CXCL1 and 6, and IL8 were negatively regulated by IFNgamma. Conclusions: RPE cells responded to exposure to T cell-derived cytokines by upregulating expression of several chemokines related to microglial, T cell, and monocyte chemotaxis and activation. This inflammatory stress response may have implications for immune homeostasis in the retina, and for the further understanding of inflammatory ocular diseases such as uveitis and age-related macular degeneration. Differentiated ARPE19 grown on inserts in serum-free media was basolaterally stimulated for 48h with activated T cells or recombinant cytokines (IFNg and/or TNFa) or neutralizing antibodies (aIFNg and/or aTNFa)