Abstract
Purpose :
Staphylococcus aureus (S. aureus) is the most common cause of bacterial corneal ulcer. The precise mechanism of collagen degradation in S. aureus induced corneal ulcer is unknown. Plasminogen (plg) plays an important role in collagen degradation by corneal fibroblasts. Staphylokinase (SAK), which produced by Staphylococcus is a bacterial (plg) activator. In this study, to determine the possible role of collagen degradation by S. aureus, we compared the effect of S. aureus culture broth and SAK on collagen degradation using a culture model which human corneal fibroblasts were embedded in a collagen gel.
Methods :
Human corneal fibroblasts were cultured in a three-dimensional gel of type I collagen. Media containing S. aureus culture broth or SAK were overlaid on the gels in the presence or absence of plasminogen. Collagen degradation was assessed by measurement of hydroxyproline in acid hydrolysates of culture supernatants. Plasmin activity was estimated using S-2251. MMP-1 production was detected by immunoblot analysis and real time RT-PCR
Results :
Both S. aureus culture broth and SAK exhibited its collagenolytic activity under the existence of plg. Both S. aureus culture broth+plg and SAK + plg exhibited its plasmin activity under the existence of corneal fibloblasts and did not increase their plasmin activities in a cell number dependent manner. In the presence of corneal fibroblasts, the amount of degraded collagen by S. aureus +plg remarkably increased in a cell number fashion. On the other hands, SAK+plg did not increase the amount of degraded collagen in cell number dependent manner. S. aureus culture broth increased MMP-1 production in corneal fibroblasts, whereas SAK did not affect MMP-1 production in corneal fibroblasts.
Conclusions :
Plasminogen is probably nessesary for collagen degradation by S. aureus. The mechanism of collagen degradation by S. aureus culture broth, not by SAK, involved in an increased MMP-1 production by corneal fibroblasts. The mechanism of collagen degradation by SAK was depended on plasmin activity.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.