Interleukin-10 receptor signaling through STAT-3 regulates the apoptosis of retinal ganglion cells in response to stress.
OBJECTIVE
Interleukin (IL)-10 has recently been shown to promote survival of neurons and glia. The purpose of this report is to investigate whether IL-10 has any role in protecting retinal ganglion cells (RGCs) from death under conditions in which growth factors are removed, or in which oxidative stress is present. Signal transduction pathways that activate IL-10 signaling in RGCs were studied in both stress conditions.


METHODS
Effects of various interleukins on the viability of the RGC cell line was determined, and apoptotic cells were quantified. Immunoblot analysis was preformed to identify the IL-10 receptor (IL-10R) and phosphorylated or nonphosphorylated Akt and STAT-3 proteins in RGC extracts. Immunohistochemistry was performed on the rat retinal sections to identify native IL-10R.


RESULTS
Apoptosis of RGCs in the absence of growth factors with or without dexamethasone (1 microM) occurred in 68.5% +/- 3.4% and 53.4% +/- 2.6% of cells, respectively, after 96 hours. Addition of IL-10 at a concentration of 50 ng/mL significantly reduced the apoptotic population of RGCs to 28.2% +/- 2.3% in the absence of growth factors with dexamethasone and to 31% +/- 2.7% in the absence of growth factors alone. RGCs as well as native retina expressed functional IL-10R as determined by immunoblot analysis and by the ability of IL-10 to phosphorylate Stat-3. However, IL-10 failed to phosphorylate Akt in these cells.


CONCLUSIONS
IL-10 caused a 59% and 42% reduction in the apoptotic population of serum-deprived cells with and without dexamethasone treatment, respectively. These observations establish that activation of IL-10R promotes survival of RGCs and this survival-promoting activity is due to IL-10 signaling through the Stat-3 pathway, which inhibits the cell death and not through the Akt cell survival pathway.
Boyd
Zachary S
ZS
Department of Ophthalmology, University of Nebraska Medical Center, 985145 Nebraska Medical Center, Omaha, NE 68198-5145, USA.
Kriatchko
Aleksie
A
Yang
Junjie
J
Agarwal
Neeraj
N
Wax
Martin B
MB
Patil
Rajkumar V
RV
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D005434:Flow Cytometry; D005938:Glucocorticoids / Q000494:pharmacology; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D016753:Interleukin-10 / Q000494:pharmacology; D018384:Oxidative Stress; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D018123:Receptors, Interleukin / Q000378:metabolism*; D053701:Receptors, Interleukin-10; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D013778:Tetrazolium Salts; D013844:Thiazoles; D015534:Trans-Activators / Q000378:metabolism*
D004268:DNA-Binding Proteins; D005938:Glucocorticoids; D011518:Proto-Oncogene Proteins; D018123:Receptors, Interleukin; D053701:Receptors, Interleukin-10; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D013778:Tetrazolium Salts; D013844:Thiazoles; D015534:Trans-Activators; D016753:Interleukin-10; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C022616:thiazolyl blue