Induction of FGF-2 synthesis by IL-1beta in aqueous humor through P13-kinase and p38 in rabbit corneal endothelium.
OBJECTIVE
To determine whether the elevated level of interleukin (IL)-1beta in aqueous humor after transcorneal freezing upregulates FGF-2 synthesis in rabbit corneal endothelium through PI3-kinase and p38 pathways.


METHODS
Transcorneal freezing was performed in New Zealand White rabbits to induce an injury-mediated inflammation. The concentration of IL-1beta was measured, and the expression of FGF-2, p38, and Akt underwent Western blot analysis. Intracellular location of FGF-2 and actin cytoskeleton was determined by immunofluorescence staining.


RESULTS
Massive infiltration of polymorphonuclear leukocytes (PMNs) to the corneal endothelium was observed after freezing, and IL-1beta concentration in the aqueous humor was elevated in a time-dependent manner after freezing. Similarly, FGF-2 expression was increased in a time-dependent manner. When corneal endothelium was stained with anti-FGF-2 antibody, the nuclear location of FGF-2 was observed primarily in the cornea after cryotreatment, whereas FGF-2 in normal corneal endothelium was localized at the plasma membrane. Treatment of the ex vivo corneal tissue with IL-1beta upregulated FGF-2 and facilitated its nuclear location in corneal endothelium. Transcorneal freezing disrupted the actin cytoskeleton at the cortex, and cell shapes were altered from cobblestone morphology to irregular shape. Topical treatment with LY294002 and SB203580 on the cornea after cryotreatment blocked the phosphorylation of Akt and p38, respectively, in the corneal endothelium. These inhibitors also reduced FGF-2 levels and partially blocked morphologic changes after freezing.


CONCLUSIONS
These data suggest that after transcorneal freezing, IL-1beta released by PMNs into the aqueous humor stimulates FGF-2 synthesis in corneal endothelium via PI3-kinase and p38.
Doheny Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California 90033, USA.
Jong-Suk
JS
Song
Jeong Goo
JG
Lee
EunDuck P
EP
Kay
D000199:Actins / Q000378:metabolism; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism*; D015153:Blotting, Western; D002867:Chromones / Q000494:pharmacology; D003318:Corneal Opacity / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D003452:Cryosurgery; D004728:Endothelium, Corneal / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000096:biosynthesis*; D019084:Fluorescent Antibody Technique, Indirect; D007093:Imidazoles / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology / Q000502:physiology*; D008856:Microscopy, Fluorescence; D009025:Morpholines / Q000494:pharmacology; D020556:Neutrophil Infiltration / Q000502:physiology*; D009504:Neutrophils / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D011817:Rabbits; D013997:Time Factors; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D000199:Actins; D002867:Chromones; D004791:Enzyme Inhibitors; D007093:Imidazoles; D053583:Interleukin-1beta; D009025:Morpholines; D011725:Pyridines; D016222:Fibroblast Growth Factor 2; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019869:Phosphatidylinositol 3-Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580