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Apoptosis-mediating receptor-ligand systems in human retinal pigment epithelial cells
Arno Hueber1, Sanjay Aduckathil, Norbert Kociok
1Department of Vitreo-Retinal Surgery, Center of Ophthalmology, University of Cologne, Joseph-Stelzmann-Strasse 9, Germany. Arno.Hueber@uni-koeln.de
Background:
To establish new strategies for the treatment of proliferative vitreoretinopathy (PVR), we investigated new members of a recently discovered apoptosis-inducing receptor-ligand system in human retinal pigment epithelial (RPE) cells. TRAIL (Apo2-L) and Apo3-L are capable of inducing cell death via their receptors Trail-R1 to Trail-R4 and TRAMP. The goal of this study was to prove the existence of these new apoptosis-inducing receptors and ligands in RPE cells.
Methods:
Human RPE cells, cultured or prepared directly from the eye, were examined by RT-PCR. Immunohistochemistry of epiretinal membranes of traumatic PVR was performed for the detection of TRAIL and Trail-R1. Protein expression of Trail-R1 was examined in cultured human RPE cells by western blot. Cell death after TRAIL treatment of human RPE cells was measured by crystal violet staining.
Results:
For RPE cells derived directly from the eye, we detected mRNAs of Trail-R2, Trail-R3, TRAIL, and APO3-L, but not Trail-R1, Trail-R4, and TRAMP. All the examined transcripts were detected in human P0 RPE cells in vitro. Immunohistochemical studies on PVR membranes identified TRAIL and Trail-R1. Western blot confirmed the presence of Trail-R1 in cultured human RPE cells. TRAIL failed to kill RPE cells in vitro, but showed a strong synergistic killing effect when coincubated with protein (cycloheximide) or RNA (actinomycin D) synthesis inhibitor.
Conclusions:
We detected a novel apoptosis-inducing receptor-ligand system in RPE cells. An induction of apoptosis as a treatment of PVR seems to be possible. Further investigations are needed including an animal model of PVR.
Insights
Researchers identified a novel apoptosis-inducing receptor-ligand system in retinal pigment epithelial cells. This discovery offers potential new strategies for treating proliferative vitreoretinopathy (PVR) by inducing cell death.
Area of Science:
- Ophthalmology
- Cell Biology
- Molecular Biology
Background:
- Proliferative vitreoretinopathy (PVR) treatment strategies are limited.
- Retinal pigment epithelial (RPE) cells are crucial in PVR pathogenesis.
- Apoptosis-inducing receptor-ligand systems offer potential therapeutic targets.
Purpose of the Study:
- To investigate novel apoptosis-inducing receptor-ligand systems in human RPE cells.
- To confirm the presence and expression of TRAIL (Apo2-L) and Apo3-L ligands and their receptors in RPE.
- To explore the potential of these systems for PVR treatment.
Main Methods:
- RT-PCR analysis of RPE cells (cultured and ex vivo).
- Immunohistochemistry on epiretinal membranes from PVR patients.
- Western blot analysis of RPE cell protein expression.
- Crystal violet staining to assess cell death after TRAIL treatment.
Main Results:
- Detected mRNAs for Trail-R2, Trail-R3, TRAIL, and APO3-L in ex vivo RPE cells.
- Confirmed TRAIL and Trail-R1 expression in PVR epiretinal membranes.
- TRAIL alone did not induce RPE cell death but showed synergy with protein/RNA synthesis inhibitors.
Conclusions:
- A novel apoptosis-inducing receptor-ligand system exists in RPE cells.
- Targeting apoptosis in RPE cells is a potential therapeutic avenue for PVR.
- Further research, including animal models, is necessary to validate PVR treatment strategies.