PURPOSE. The fibrotic lens disorder posterior capsule opacification (PCO) develops in millions of patients following cataract surgery. PCO characteristics are extensive extracellular matrix (ECM) production and contraction of the posterior lens capsule, resulting in light-scattering ECM modification (wrinkling). The pro-fibrotic cytokine transforming growth factor beta (TGFb) is central to PCO development. This study aimed to elucidate the role of the ECM modulators matrix metalloproteinases (MMPs) in TGFb-mediated PCO formation. METHODS.The human lens epithelial cell-line FHL-124 and human capsular bag models were employed. Gene expression of MMP family members was determined by oligonucleotide microarray and quantitative real-time RT-PCR. MMP2 and MT1-MMP protein levels were analyzed by ELISA and Western blotting, respectively. Matrix contraction was determined using an FHL-124 patch contraction assay; at end-point, cells were stained with Coomassie brilliant blue and area was determined using image analysis software. Cell coverage and wrinkle formation on the posterior capsule were also assessed using human capsular bag models.RESULTS. Active TGFb2 (10 ng/mL) increased gene and protein levels of MMP2 and MT1-MMP and induced matrix contraction in FHL-124 cells. Specific siRNA inhibition of MT1-MMP did not suppress TGFb2-induced matrix contraction. Active TGFb2-mediated contraction was prevented by broad-spectrum MMP inhibitor GM6001 (25 lM), MMP2 siRNA, and MMP2 neutralizing antibody (4 lg/mL). TGFb2-induced wrinkle formation was attenuated in human capsular bags treated with MMP2 neutralizing antibody (20 lg/mL).CONCLUSIONS. MMP2 plays a critical role in TGFb2-mediated matrix contraction, which appears to be independent of MT1-MMP. MMP2 inhibition provides a novel strategy for the treatment of PCO and potentially other fibrotic disorders. (Invest Ophthalmol Vis Sci. 2012;53:4085-4098)

PURPOSE.Matrix metalloproteinases (MMPs) and the tissue inhibitors of the MMPs (TIMPs) have been implicated in lens differentiation, growth, remodeling, and cataract. Hence, a gene expression analysis was undertaken in epithelial and fiber cells dissected from clear human donor lenses. METHODS. The human lens was dissected into three regions: anterior epithelial, equatorial, and fiber cells. Primary lens cell cultures were also analyzed. cDNA was generated by reverse transcription of the mRNA portion of the total RNA isolated from each sample. Gene expression data were generated using quantitative real-time reverse transcription PCR. Data were analyzed in terms of cycle threshold number (C T ) and were normalized to endogenous 18S expression. Western blot analyses were carried out to confirm the presence of two critical MMPs. RESULTS. Anterior and equatorial samples were uncontaminated by fiber cells because they showed high expression of ␣-crystallin genes but low expression of ␤-and ␥-crystallins. The fibers had high expression of these genes and of MIP. MMP genes were expressed at uniformly low levels in the native tissues except for MMP-14 and -15 (MT1-and MT2-MMP, respectively). In fact, MT1-MMP declined in expression from the anterior epithelium to fibers, whereas MT2-MMP increased. The presence of MT1 and MT2-MMP proforms and faster migrating bands, indicating processed or activated forms, was confirmed at the protein level. TIMP genes were uniformly highly expressed in native tissues, with TIMP-3 having the highest expression in the epithelial tissues and TIMP-2 in the fibers. MMP expression was generally elevated in both sets of cultured cells, including MMP-2 and -9. TIMP genes were also relatively highly expressed in the cultured cells. CONCLUSIONS. MMP expression is generally well regulated in native tissues, with relatively low expression of MMPs and high expression of TIMPs. Membrane-type MMPs (MT1 and 2-MMPs) were the most highly expressed; this is important in a tissue with relatively high membrane content but low extracellular space. The striking reciprocal patterns of expression of MT1-MMP and MT2-MMP indicate that these enzymes are of particular significance in lens function. (Invest Ophthalmol Vis Sci.