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X. Liu, P. Gonzalez, P.B. Liton, P. Challa, M. Bodman, D.L. Epstein; Induction of the TGF–beta–1 gene promoter in the trabecular meshwork after mechanical stress: potential implications in glaucoma pathophysiology . Invest. Ophthalmol. Vis. Sci. 2004;45(13):3661.
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Purpose: TGF–beta–1 has been implicated in the pathophysiology of several chronic diseases. Here we studied the distribution of the expression of the TGF–beta–1 gene promoter in the cells of the anterior segment of human eyes and analyzed its induction after chronic mechanical stress in organ culture. Methods: We generated two recombinant adenoviruses with a 464 nt fragment of the human TGF–beta–1 gene promoter driving the expression of the reporter genes: LacZ (AdTGFb1LacZ), and SEAP (AdTGFb1SEAP) respectively. The AdTGFb1LacZ virus was perfused into six anterior segments from human eyes at 107 pfu/eye. 48 hours after infection, the anterior segments were fixed and analyzed histologically to identify the specific cells expressing LacZ. The AdTGFb1SEAP virus was perfused into three pairs of anterior segments from pig eyes 107 pfu/eye. One eye of each pair was subjected to mechanical stress by oscillating the flow between 2uL/min (15 min) and 25 uL/min (1 min). The induction of the TGF–beta–1 promoter was measured by analyzing the amount of SEAP released to the effluent from each eye. Results:LacZ expression driven by the TGF–beta–1 promoter fragment was observed preferentially in the trabecular meshwork (TM). There were important differences in the levels of expression within the TM cells. Lower levels of LacZ expression were also found in the corneal endothelial cells. Mechanical stress induced a 10–fold increase in the production of SEAP driven by the TGF–beta–1 promoter with respect to non–stressed controls. Conclusions: The preferential expression of the TGF–beta–1 promoter fragment in TM cells and its induction after mechanical stress indicate that chronic mechanical stress could potentially lead to pathologic effects such as fibrosis in the TM, mediated by increased production of TGF–beta–1. Additionally, the promoter from the TGF–beta–1 gene can be used for gene transfer in the cells of the TM with the important advantage that the transgene expression can be modulated by mechanical stress.
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