HGF regulation of RPE proliferation in an IL-1beta/retinal hole-induced rabbit model of PVR.
OBJECTIVE
To understand molecular events that lead to retinal pigment epithelial (RPE) cell proliferation and migration during the early phases of proliferative vitreoretinopathy (PVR) in a rabbit model.


METHODS
Retinal holes were created and interleukin-1beta(IL-1beta) was injected intravitreally. Eyes were examined by indirect ophthalmoscopy and eyecup pieces containing retinal holes were analyzed at different times after the surgery up to 4 weeks. RPE proliferation and migration were examined by immunohistochemistry. Tyrosine phosphorylation of extracellular signal regulated kinase (ERK) and hepatocyte growth factor receptor (HGFR or c-met) was determined by immunoprecipitation and western blot analysis. Tyrosine phosphorylation of c-met and morphological studies was performed on vitreous treated ARPE-19 cells. Expression of c-jun was determined by Northern blot analysis. Matrix metalloproteinase (MMP) content in vitreous was assessed by zymography.


RESULTS
Indirect ophthalmoscopy identified formation of epiretinal membrane and immunohistochemistry identified proliferative and migratory RPE and other cells in the posterior segment containing retinal holes at 4 weeks post-surgery. Tyrosine phosphorylation of ERK and c-met occurred in this segment within 30 min of surgery. ARPE-19 cells treated with vitreous from the 24 h post-surgical eyes, but not with control vitreous or IL-1beta, showed morphological changes and tyrosine phosphorylation of c-met. Northern blot analysis in this segment identified upregulation of c-jun within 30 min of surgery and the expression peaked at 72 h. Zymographic analysis of vitreous identified MMP-9 in 12-72 h post-surgery.


CONCLUSIONS
These data suggest that the presence of retinal holes and IL-1beta may lead to activation of HGF, mitogen activated protein kinases (MAPK), c-jun and extracellular matrix remodeling, resulting in proliferative and migratory cells in the wounded retina.
Liou
Gregory I
GI
Department of Ophthalmology, Medical College of Georgia, Augusta, GA 30912, USA. giliou@mail.mcg.edu
Pakalnis
Vytautas A
VA
Matragoon
Suraporn
S
Samuel
Sara
S
Behzadian
M Ali
MA
Baker
Justin
J
Khalil
Ibrahim E
IE
Roon
Penny
P
Caldwell
Ruth B
RB
Hunt
Richard C
RC
Marcus
Dennis M
DM
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002455:Cell Division; D002465:Cell Movement; D004195:Disease Models, Animal; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D007375:Interleukin-1 / Q000008:administration & dosage*; D007633:Keratins / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D010857:Pigment Epithelium of Eye / Q000473:pathology*; D011233:Precipitin Tests; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D011817:Rabbits; D012167:Retinal Perforations / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D014443:Tyrosine / Q000378:metabolism; D018630:Vitreoretinopathy, Proliferative / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D014822:Vitreous Body / Q000187:drug effects / Q000201:enzymology
D007375:Interleukin-1; D018809:Proliferating Cell Nuclear Antigen; D016755:Proto-Oncogene Proteins c-jun; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D007633:Keratins; D019859:Proto-Oncogene Proteins c-met; D020928:Mitogen-Activated Protein Kinases; D020782:Matrix Metalloproteinases