LIPOTEICHOIC ACID FROM STAPHYLOCOCCUS AUREUS INDUCED EXPRESSION OF MMP-9 IN HUMAN MIDDLE EAR CELLS
Hyun Jun Kim
Background : Otitis media (OM) is the most common diagnosis in children who visit physicians for illness. Although microbial infection and Eustachian tube dysfunction are known to be common cause, exact pathophysiology are not fully understood. Change in matrix metalloproteinase (MMPs) and regulation of their tissue inhibitors of metalloproteinase (TIMPs) could play certain role in the pathogenesis of otitis media. This study was designed to evaluate the modulation of MMPs and TIMPs in middle ear epithelium by lipoteichoic acid (LTA) isolated from Staphylococcus aureus.
Material : Human middle ear epithelial (HMEE) cells were treated with LTA from Staphylococcus aureus. MMP activities were examined by real-time PCR, ELISA and gelatin zymography, and levels of TIMPs were measured by PCR and ELISA.
Results : LTA isolated from Staphylococcus aureus increased MMP-9 mRNA expression and secretion in HMEE cells in a dose-dependent and a time-dependent manner, whereas no effect on the expressions of MMP-1, -2, -3, -7 and TIMP-1, -2 was observed.
Conclusions : We demonstrated increased activity of MMP-9 in the middle ear epithelial cells when treated with LTA, whereas it had no effect on the expression of TIMP-1 and TIMP-2. The disturbed balance between MMP-9 and TIMPs expressions after exposure to LTA may contribute to the destruction of middle ear epithelial cells, thus leading to OM.
Keywords: Otitis media lipoteichoic acid matrix metalloproteinase
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