Decreased TNF Levels and Improved Retinal Ganglion Cell Survival in MMP-2 Null Mice Suggest a Role for MMP-2 as TNF Sheddase

Figure 1

Expression profiles of MMP-2 and MMP-9 in the excitotoxic mouse retina. (a) Upon excitotoxic injury to the retina, pro-MMP-2 expression, as revealed by gelatin zymography, was upregulated, reaching maximum expression at 18 hpi and returning to baseline levels by 24 hpi. (b) Immunohistochemical (IHC) staining for MMP-2 (green) in the naive retina. (c) Immunostaining for MMP-2 revealed that the increased MMP-2 expression at 18 hpi localized to the activated astrocytes and/or radial processes of the Müller glia. (d) Gelatin zymography disclosed that, upon excitotoxic injury to the retina, pro-MMP-9 steeply increased to reach a maximum at 18 hpi, accompanied by a lower peak of activated MMP-9. At 24 hpi, both mature and pro-MMP-9 levels had returned to baseline. (e) Immunostaining for MMP-9 (green) in the naive retina. (f) Upon excitotoxic injury to the retina, an increased number of MMP-9⁺ microglia and RGCs, and augmented MMP-9 immunoreactivity in the plexiform layers were observed. Scale bars, 20 μm.

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