TNF-α stimulates MMP-2 and MMP-9 activities in human corneal epithelial cells via the activation of FAK/ERK signaling.
OBJECTIVE
Herpes simplex virus type-1-induced herpes simplex keratitis (HSK) is a common immunological cornea disease. While previous studies have addressed the role of tumor necrosis factor (TNF)-α and matrix metalloproteinases (MMPs) in HSK, the mechanistic link between TNF-α and MMPs in the pathogenesis of HSK remains elusive.


METHODS
We first established a HSK mice model and measured the levels of TNF-α, MMP-2 and MMP-9 in the corneas at different time points by ELISA. Next, we employed cultured human corneal epithelial (HCE) cells as an in vitro model and performed gelatin zymography analysis.


RESULTS
We observed that the change in the TNF-α level shared a similar pattern to that of MMP-2 and MMP-9 in the HSK mice model. Furthermore, TNF-α stimulated MMP-2 and MMP-9 activities in a dose-dependent manner, but either knockdown of focal adhesion kinase (FAK) by short interference RNA or inhibition of extracellular regulated protein kinase (ERK) by chemical inhibitor could block TNF-α-stimulated MMP-2 and MMP-9 activities in vitro. Taken together, our results provide in vivo evidence that the TNF-α level is positively correlated with MMP-2 and MMP-9 levels in a HSK model and in vitro evidence that TNF-α stimulates MMP-2 and MMP-9 activities via the activation of FAK/ERK signaling in HCE cells.


CONCLUSIONS
Our findings shed new light on the pathogenesis of HSK and open up new possibility of modulating the TNF-α-FAK-ERK signaling cascade to pursue therapeutic measures for HSK.
Department of Ophthalmology, Renmin Hospital of Wuhan University, Wuhan, China. ophyyn@163.com
Yan-Ning
YN
Yang
Fang
F
Wang
Wei
W
Zhou
Zhi-Qing
ZQ
Wu
Yi-Qiao
YQ
Xing
D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000201:enzymology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism*; D018259:Herpesvirus 1, Human / Q000472:pathogenicity; D006801:Humans; D015151:Immunoblotting; D016849:Keratitis, Herpetic / Q000201:enzymology; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; C496051:Ptk2 protein, mouse; D048049:Extracellular Signal-Regulated MAP Kinases; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse