Abstract
Abstract: :
Purpose:Previous studies by Streilein et al. revealed that the subretinal space is an immunosuppressive microenvironment. Since both the neuroretinal cells (NR) and the pigmented epithelial cells (RPE) have the potential to contribute factors into the subretinal space, we investigated the expression of cytokines produced by the NR and RPE and their effect on inflammatory macrophage activity. Methods: RPE eyecups and NR from healthy C57BL/6J mice were prepared and cultured for 24 hours. The eyecup supernatant (RPE–SN) and NR conditioned media (NR–SN) were transferred to macrophage cultures with or without lipopolyssacharide activation. After 48 hours culture, the macrophage culture supernatants were analyzed using a Bio–Rad multiplex analyzer for IL–1ß, IL–6, Il–10, IL–12 (p70), TNF–α, G–CSF, GM–CSF, MIP–1α, RANTES and KC. The RPE–SN and NR–SN were also analyzed by the multiplex analysis. Results: We found IL–6, IL–10, TNF–α, GM–CSF and KC in RPE–SN, and G–CSF and KC in the NR–SN. In the presence of resting macrophage, KC levels were reduced in both RPE–SN and NR–SN. RPE–SN suppressed G–CSF, while NR–SN increased GM–CSF production by resting macrophage. For LPS–activated macrophages, the RPE–SN did not suppress any LPS–induced factor, but did induce significant production of IL–10. The NR–SN significantly promoted TNF–α production, and significantly suppressed IL–1ß production by the activated macrophages. Conclusions:Both RPE and NR supernatants did not activate the macrophages; however, RPE–SN and NR–SN had differential effects on LPS–activated macrophages. Therefore neuroretinal and RPE cells contribute differently to the subretinal microenvironment. This implies that the mechanism of immunosuppression observed in the subretinal space is a combined effort of the RPE and neuroretina.
Keywords: immunomodulation/immunoregulation • inflammation • cytokines/chemokines