Modulation of matrix metalloproteinase and TIMP-1 expression by cytokines in human RPE cells.
OBJECTIVE
The balance between matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) is crucial for homeostasis of ocular extracellular matrices. To assess altered MMP activity as a determinant in the migration of human retinal pigment epithelial (RPE) cells, expression characteristics of several MMPs and TIMP-1 in RPE cell cultures were investigated.


METHODS
Expression studies were performed with RT-PCR, ELISA, and immunofluorescence analysis. Secretion of MMP-2 was demonstrated by zymography. Migration of cytokine-stimulated RPE cells was evaluated with microporous membranes of permeable chambers.


RESULTS
MMP-1, -2, -3, and -9; MT2-MMP; and TIMP-1 were expressed in cultured RPE cells. MMP-2 was detected on the cell surface and in secreted inactive and active forms. TGF-beta(2), IL-1beta, and TNF-alpha enhanced secretion of MMP-1, -2, and -3. TGF-beta(2) also stimulated MT2-MMP cell surface expression and release of TIMP-1. The mRNA levels of MMP-1, -2, and -3 and TIMP-1 were markedly increased by TNF-alpha and TGF-beta(2). MMP-2 mRNA levels were also upregulated by PDGF-BB. Migration of RPE cells stimulated by TGF-beta(2) or PDGF-BB was inhibited in presence of a synthetic MMP inhibitor.


CONCLUSIONS
Proinflammatory cytokines and TGF-beta(2) play an important role in the upregulation of expression of MMP-1, -2, and -3 in RPE cells and account for a directional shift in the balance between MMPs and TIMPs. Facilitation of RPE cell migration stimulated by cytokines (i.e., TGF-beta(2) or PDGF-BB) in ocular diseases may be due to increased release of MMPs, in the presence of comparatively lower levels of their inhibitors.
Eichler
Wolfram
W
University of Leipzig, Eye Hospital, Leipzig, Germany. eichwolf@rz.uni-leipzig.de
Friedrichs
Ulrike
U
Thies
Alexander
A
Tratz
Corinna
C
Wiedemann
Peter
P
D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005109:Extracellular Matrix / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D018093:Gelatinases / Q000378:metabolism; D006801:Humans; D020782:Matrix Metalloproteinases / Q000096:biosynthesis* / Q000235:genetics; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000096:biosynthesis* / Q000235:genetics; D015854:Up-Regulation
D016207:Cytokines; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D018093:Gelatinases; D020782:Matrix Metalloproteinases