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H. Kaur, S. S. Chaurasia, V. Agrawal, S. E. Wilson; Opposing Effects of IL-1 and TGFβ1 on Corneal Myofibroblast Viability in vitro . Invest. Ophthalmol. Vis. Sci. 2009;50(13):4537.
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© ARVO (1962-2015); The Authors (2016-present)
To elucidate the effect of interleukin-1 and transforming growth factor beta-1 on corneal stromal myofibroblasts viability and death in vitro.
Primary rabbit corneal fibroblasts were cultured with 2ng/ml of transforming growth factor-β1 (TGFβ1) to induce myofibroblast differentiation confirmed by monitoring -smooth muscle actin (-SMA) expression. Fluorescence-based TUNEL assay was performed to analyze the apoptotic response of myofibroblasts to IL-1 or IL-1β in the presence or absence of TGFβ1. Dose response experiments were performed after withdrawal of TGFβ1 and exposure to 1, 5, or 10 ng/ml of IL-1 or IL-1β for 1 hour. Subsequent experiments were performed with myofibroblasts exposed to 5 ng/ml IL-1 or IL-1β in conjunction with 0, 1, 5, or 10 ng/ml TGFβ1. Results 4 wells at each cytokine concentration at each time point were analyzed.
Exposure to TGFβ1 resulted in greater than 99% transformation of corneal fibroblasts to -SMA+ myofibroblasts. There was a statistically significant dose dependent increase in the percentage of TUNEL+ cells with either IL-1 or IL-1β at each time point (ANOVA, P<0.05). For example, in one experiment, after withdrawal of TGFβ1, the % TUNEL+ cells at 1 hour after exposure to IL-1 cytokine increased significantly with increasing concentration (0 ng/ml, 2.4±0.8 (S.E.M.) %; 1 ng/ml, 15.4±1.8%; 5 ng/ml, 47.4±3.9%; or 10 ng/ml, 70.3±3.2%). The differences between the means were significantly different (ANOVA p<0.001). Similarly, with IL-1β at 0 ng/ml, 1 ng/ml, 5 ng/ml or 10 ng/ml the % TUNEL+ cells significantly increased at 1 hour (2.4±0.8%, 12.8±0.7%, 53.5±4.1%, and 84.6±3.7%, respectively). The differences between the means were significantly different (ANOVA p<0.001). When myofibroblasts were exposed to 5 ng/ml IL-1 or IL-1β the % TUNEL+ cells at 1 hour was reduced in a dose dependent manner when TGFβ1 at a concentration of 0 ng/ml, 1 ng/ml, 5 ng/ml or 10 ng/ml TGFβ1 was present in the medium. The differences between the means were significantly different (ANOVA p<0.001).
IL-1 or IL-1β triggers the death of myofibroblasts in vitro and TGFβ1 inhibits the IL-1 effect on cell death. The mechanism of IL-1 induced myofibroblast cell death is likely apoptosis.
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