Primary open-angle glaucoma (POAG) is a progressive optic neuropathy, which is a major cause of worldwide visual impairment and blindness. Pathological hallmarks of the glaucomatous optic nerve head (ONH) include retinal ganglion cell axon loss and extracellular matrix (ECM) remodeling of the lamina cribrosa layer. Transforming growth factor-beta (TGF-beta) is an important pro-fibrotic modulator of ECM metabolism, whose levels are elevated in human POAG lamina cribrosa tissue compared with non-glaucomatous controls. We hypothesize that in POAG, lamina cribrosa (LC) glial cells respond to elevated TGF-beta, producing a remodeled ONH ECM. Using Affymetrix microarrays, we report the first study examining the effect of TGF-beta1 on global gene expression profiles in glial fibrillary acidic acid (GFAP)-negative LC glial cells in vitro. Prominent among the differentially expressed genes were those with established fibrogenic potential, including CTGF, collagen I, elastin, thrombospondin, decorin, biglycan, and fibromodulin. Independent TaqMan and Sybr Green quantitative PCR analysis significantly validated genes involved in regulation of cell proliferation (platelet-derived growth factor [PDGF-alpha]), angiogenesis (vascular endothelial growth factor [VEGF]), ECM accumulation and degradation (CTGF, IL-11, and ADAMT-S5), and growth factor binding (ESM-1). Bioinformatic analysis of the ESM-1 promoter identified putative Smad and Runx transcription factor binding sites, and luciferase assays confirmed that TGF-beta1 drives transcription of the ESM-1 gene. TGF-beta1 induces expression and release of ECM components in LC cells, which may be important in regulating matrix remodeling in the lamina cribrosa. In disease states such as POAG, the LC cell may represent an important pro-fibrotic cell type and an attractive target for novel therapeutic strategies.

These results suggest that cyclical stretch and TGF-beta1 modulate MMP-2 activity in human lamina cribrosa cells. TGF-beta 1 and MMP-2 release from lamina cribrosa cells may facilitate matrix remodeling of the optic nerve head in primary open angle glaucoma.

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We investigated thymidine kinase (tk) mutants isolated during multiple episodes of recurrent bilateral acyclovir resistant herpes simplex keratitis in an immunocompetent patient. From one eye, we found a single guanine insertion, previously shown to greatly reduce TK expression, and from the other, a previously unidentified substitution, which genetic experiments confirmed confers drug resistance. The substitution, although distant from substrate binding sites, reduced thymidine phosphorylation 10-20-fold, and acyclovir phosphorylation >100-fold. This phenotype should permit reactivation from latency to cause recurrent disease. The results may have implications for the prevalence and prevention of acyclovir resistance in patients with herpes simplex keratitis.