Data we collected in FY 2015 revealed that interferon (IFN)- enhances in RPE cells (ARPE19 human cell line) the expression of IL-18 binding protein (IL-18BP), but inhibits the expression of IL-18. In new experiments in 2016 we found that these two cytokines are expressed in different compartments of the RPE cell: whereas IL-18BP is found in the supernatant of cultured ARPE19 cells, IL-18 is detected only in the lysate of these cells. This unique different pattern of expression of IL-18 and IL-18BP is assumed to prevent interaction between the two cytokines and the consequent mutual neutralization of their activity. IFN- is an early product of inflammatory processes and is responsible for mediating numerous pathogenic reactions. The expression levels of IL-18 and IL-18BP affect the outcome of pathogenic processes in the eye and we further investigated in FY 2016 this issue. To learn about the biochemical processes involved in the activity of IFN-, identified the transcription factors that are regulated by this cytokine. We used the MetaCore system to analyze the interactions among the molecules involved in the process. The accumulated data suggest that IFN- inhibits the activity of the transcription factor AP-1, an enhancer for IL-18 production, but upregulates the activity of Stat1 or IRF1, two transcription factors that increase the production of IL-18BP. To further examine the data collected by the MetaCore system, we carried out chip-qPCR analysis, to detect the binding activity of AP-1 in the promoter region of IL-18 gene and the binding activities of Stat1 and IRF1 in the promoter region of IL-18BP, in the presence of IFN-. The primers were designed based on the predicted binding sites by the software from Qiagen and confirmed that in RPE cells IFN- inhibits the binding activity of AP-1 complex in the promoter region upstream of transcription starting site of IL-18, but promotes the binding activity of Stat 1 and IRF1 in the promoter region around transcription starting site of IL-18BP. To our knowledge, our study is the first to disclose the signal pathways controlling IL-18:IL-18BP balance in RPE cells.
| Schewitz-Bowers, Lauren P; Lait, Philippa J P; Copland, David A et al. (2015) Glucocorticoid-resistant Th17 cells are selectively attenuated by cyclosporine A. Proc Natl Acad Sci U S A 112:4080-5 |
| Shi, Guangpu; Chen, Siqi; Wandu, Wambui S et al. (2015) Inflammasomes Induced by 7-Ketocholesterol and Other Stimuli in RPE and in Bone Marrow-Derived Cells Differ Markedly in Their Production of IL-1? and IL-18. Invest Ophthalmol Vis Sci 56:1658-64 |
| Zhao, Chan; Shi, Guangpu; Vistica, Barbara P et al. (2014) Induced regulatory T-cells (iTregs) generated by activation with anti-CD3/CD28 antibodies differ from those generated by the physiological-like activation with antigen/APC. Cell Immunol 290:179-84 |
