Extracellular vesicles (EV), such as exosomes, are important mediators of intercellular communication and have been implicated in modulation of the immune system. We investigated if EV released from retinal pigment epithelium (RPE) modulate immune responses in vitro. In collaboration with Dr Leonid Margolies (NICHD), we have found that Retinal pigment epithelium cells constitutively secrete extracellular vesicles (EV) in the size range of exosomes. Interestingly EV release is increased by ARPE-19 cells stimulated with inflammatory cytokines. Extracellular vesicles from both nonstimulated and cytokine-stimulated RPE inhibited T-cell stimulation. Whereas, EV from nonstimulated ARPE-19 cells promoted an immunoregulatory CD14++CD16+ phenotype in human monocytes, and exosomes from cytokine-stimulated ARPE-19 cells caused human monocyte death. These findings suggest that RPE cells use EV to induce a downregulatory immune environment under homeostatic conditions. In an inflammatory milieu, RPE-derived EV may mitigate a potentially harmful inflammatory response through killing of monocytes. This work was published in IOVS (PMID:27537259). We are now extending these findings to iPS derived RPE cells in collaboration with Dr. Bharti (NEI). We also induced experimental autoimmune uveitis in wild type and SR-A1 knockout mice. SR-A1 deletion inhibited the development of EAU. Macrophages and dendritic cells from these animals expressed lower levels of pro-inflammatory genes and markers. Macrophages have been implicated in the pathogenesis of AMD. Class A scavenger receptors, SR-A and MARCO, are expressed on macrophages and are associated with macrophage function. The goal of this study is to examine the role of macrophage scavenger receptors in immune cell recruitment and the formation of CNV. We had previously reported that the deficiency of scavenger receptors impairs the formation of CNV and immune cell recruitment and in these experiments that of EAU. Our findings suggest a potential role for scavenger receptors in contributing to CNV formation and inflammation in AMD and uveitis. Immunosenescence is also of interest in uveitis. Using unbiased bioinformatics analysis of deep immunophenotyping by flow cytometry, we have unraveled a phenotype in CD8 T cells. Uveitis, like most autoimmune disease is believed to be mainly driven by CD4 T cells. This observation opens the way to new prospect of uveitis and ocular inflammatory disease in general. Specifically, we found that the CD8+CD45RA+CD27-CCR7- T cells, corresponding roughly to the effector memory expressing CD45RA subsets were increased in uveitis patients. Moreover, the relative abundance of this population was correlated with disease activity. Interestingly, those CD8 T cells exhibit features of immunosenescence, such as upregulation of CD57, loss of proliferative ability, aberrant cytokines production in response to TCR stimulation. We further indentified that the MAPK p38 was overphosphorylated in these cells and that in vitro treatment of uveitis patients cells with a p38 inhibitor, was sufficient to reverse functional defect in vitro. These findings raise the question of the role of these CD8 cells in uveitis, and more broadly the notion of immunosenescence. A manuscript is under preparation at the moment. We had shown previously that C5a promoted IL-22 and IL-17 expression from human CD4+ T cells of AMD patients and normals accompanied by the expression of the transcription factor BATF. This effect was dependent on B7, IL-1beta and IL-6 expression from monocytes. Intriguingly, we found significantly increased levels of IL-22 in the serum of 22 AMD patients as compared to non-AMD controls, strongly suggesting possible roles of IL-22 and IL-17 in the inflammation that contributes to AMD. We wished to further these observations by evaluating macrophage subtypes in ocular inflammatory disease. While human macrophages have been categorized into subtypes they have not be well evaluated in ocular inflammatory disease and autoimmunity. Uveitis patients circulating monocytes were skewed to the CD14++CD16+ type and this was associated with corticosteroid therapy. This subset had an attenuated capacity to promote nave CD4+ T cells to proliferate and polarize into a TH1 phenotype, memory CD4+ memory cell proliferation and IL-17 expression. They also inhibited T cell inhibition induced by other monocyte subsets while increasing CD4 T regulatory cells. We further studied the effect of immunosuppression on human inflammatory cells. A subset of T cells appearappears to be resistant to corticosteroid therapy but do respond to cyclosporine therapy, thus selectively attenuating TH17 cells.
| Knickelbein, Jared E; Liu, Baoying; Arakelyan, Anush et al. (2016) Modulation of Immune Responses by Extracellular Vesicles From Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 57:4101-7 |
| Chen, Ping; Urzua, Cristhian A; Knickelbein, Jared E et al. (2016) Elevated CD1c+ Myeloid Dendritic Cell Proportions Associate With Clinical Activity and Predict Disease Reactivation in Noninfectious Uveitis. Invest Ophthalmol Vis Sci 57:1765-72 |
| 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 |
| Liu, Baoying; Dhanda, Ashwin; Hirani, Sima et al. (2015) CD14++CD16+ Monocytes Are Enriched by Glucocorticoid Treatment and Are Functionally Attenuated in Driving Effector T Cell Responses. J Immunol 194:5150-60 |
| Chen, Ping; Denniston, Alastair; Hannes, Susan et al. (2015) Increased CD1c+ mDC1 with mature phenotype regulated by TNF?-p38 MAPK in autoimmune ocular inflammatory disease. Clin Immunol 158:35-46 |
| Nussenblatt, Robert B; Lee, Richard W J; Chew, Emily et al. (2014) Immune responses in age-related macular degeneration and a possible long-term therapeutic strategy for prevention. Am J Ophthalmol 158:5-11.e2 |
| Dagur, Pradeep K; Biancotto, Angélique; Stansky, Elena et al. (2014) Secretion of interleukin-17 by CD8+ T cells expressing CD146 (MCAM). Clin Immunol 152:36-47 |
| Wu, Wenting; Jin, Ming; Wang, Yujuan et al. (2014) Overexpression of IL-17RC associated with ocular sarcoidosis. J Transl Med 12:152 |
| Lima, Breno R; Mandelcorn, Efrem D; Bakshi, Nupura et al. (2014) Syphilitic outer retinopathy. Ocul Immunol Inflamm 22:4-8 |
| Whitcup, Scott M; Nussenblatt, Robert B; Lightman, Susan L et al. (2013) Inflammation in retinal disease. Int J Inflam 2013:724648 |
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