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Takashi Nagano, Ji-Long Hao, Masatsugu Nakamura, Naoki Kumagai, Mitsuko Abe, Teruko Nakazawa, Teruo Nishida; Stimulatory Effect of Pseudomonal Elastase on Collagen Degradation by Cultured Keratocytes. Invest. Ophthalmol. Vis. Sci. 2001;42(6):1247-1253.
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© ARVO (1962-2015); The Authors (2016-present)
purpose. The pathobiology of corneal ulceration induced by Pseudomonas
aeruginosa was investigated by characterization of the
pseudomonal pathogenic factors responsible for degradation of the
methods. Three-dimensional gels of type I collagen containing (or not) rabbit
keratocytes were incubated in the presence of either culture
supernatant of P. aeruginosa strain PAO1 or pseudomonal
pathogenic factors (elastase, lipopolysaccharide, or exotoxin A), and
the extent of collagen degradation was assessed after 24 hours by
measurement of released hydroxyproline. Activation of matrix
metalloproteinases (MMPs) produced by keratocytes was also examined by
gelatin zymography and immunoblot analysis.
results. In the absence of keratocytes, the PAO1-conditioned medium increased
the extent of collagen degradation. The conditioned medium also
promoted keratocyte-mediated collagen degradation. Of the pseudomonal
pathogenic factors examined, only elastase degraded collagen directly
as well as stimulated keratocyte-mediated collagen degradation. Culture
supernatant of elastase-deficient P. aeruginosa (lasR or lasB) mutants had no effect on
collagen degradation in the absence or presence of keratocytes.
Elastase also induced the conversion of the inactive precursors of
MMP-1, -2, -3, and -9 produced by keratocytes to the active forms of
conclusions. These results suggest that pseudomonal elastase both degrades type I
collagen directly and promotes collagen degradation mediated by
keratocytes, the latter effect being likely attributable, at least in
part, to the activation of proMMPs.
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