Gene expression regulation in retinal pigment epithelial cells induced by viral RNA and viral/bacterial DNA.
OBJECTIVE
The pathogenesis of age-related macular degeneration (AMD) is associated with systemic and local inflammation. Various studies suggested that viral or bacterial infection may aggravate retinal inflammation in the aged retina. We compared the effects of synthetic viral RNA (poly(I:C)) and viral/bacterial DNA (CpG-ODN) on the expression of genes known to be involved in the development of AMD in retinal pigment epithelial (RPE) cells.


METHODS
Cultured human RPE cells were stimulated with poly(I:C; 500 µg/ml) or CpG-ODN (500 nM). Alterations in gene expression and protein secretion were determined with real-time RT-PCR and ELISA, respectively. Phosphorylation of signal transduction molecules was revealed by western blotting.


RESULTS
Poly(I:C) induced gene expression of the pattern recognition receptor TLR3, transcription factors (HIF-1α, p65/NF-κB), the angiogenic factor bFGF, inflammatory factors (IL-1β, IL-6, TNFα, MCP-1, MIP-2), and complement factors (C5, C9, CFB). Poly(I:C) also induced phosphorylation of ERK1/2 and p38 MAPK proteins, and the secretion of bFGF and TNFα from the cells. CpG-ODN induced moderate gene expression of transcription factors (p65/NF-κB, NFAT5) and complement factors (C5, C9), while it had no effect on the expression of various TLR, angiogenic factor, and inflammatory factor genes. The activities of various signal transduction pathways and transcription factors were differentially involved in mediating the poly(I:C)-induced transcriptional activation of distinct genes.


CONCLUSIONS
The widespread effects of viral RNA, and the restricted effects of viral/bacterial DNA, on the gene expression pattern of RPE cells may suggest that viral RNA rather than viral/bacterial DNA induces physiologic alterations of RPE cells, which may aggravate inflammation in the aged retina. The data also suggest that selective inhibition of distinct signal transduction pathways or individual transcription factors may not be effective to inhibit viral retinal inflammation.
Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany.
Anton
A
Brosig
Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
Heidrun
H
Kuhrt
Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany.
Peter
P
Wiedemann
Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany ; Helios Klinikum Aue, Aue, Germany.
Leon
L
Kohen
Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany.
Andreas
A
Bringmann
Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany.
Margrit
M
Hollborn
D042501:Angiogenic Proteins / Q000235:genetics; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000235:genetics; D016207:Cytokines / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics*; D004279:DNA, Viral / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D008268:Macular Degeneration / Q000209:etiology* / Q000235:genetics / Q000382:microbiology; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D011070:Poly I-C / Q000494:pharmacology; D012367:RNA, Viral / Q000235:genetics*; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D051193:Toll-Like Receptors / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
D042501:Angiogenic Proteins; C408982:CPG-oligonucleotide; D016207:Cytokines; D004269:DNA, Bacterial; D004279:DNA, Viral; D018836:Inflammation Mediators; D009838:Oligodeoxyribonucleotides; D012367:RNA, Viral; D051193:Toll-Like Receptors; D014157:Transcription Factors; D003165:Complement System Proteins; D011070:Poly I-C