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Q. Li, A. Kumar, F.–S.X. Yu; Lipoproteins of Pseudomonas Aeruginosa and Staphylococcus Aureus Activate Human Corneal Epithelial Cells Through Toll–Like Receptor 2 . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1908.
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© ARVO (1962-2015); The Authors (2016-present)
Bacterial lipoproteins (BLPs) are a family of cell wall components found in both Gram–positive and Gram–negative bacteria. In this study, we sought to determine if BLPs from P. aeruginosa and S. aureus induce an inflammatory response in cultured human corneal epithelial cells (HCEC) and to elucidate the underlying mechanisms.
BLPs were prepared from P. aeruginosa or S. aureus by Triton X–114 extraction and used to challenge HUCL, a telomerase–immortalized HCEC. The activation of NF–ΚB, JNK, P38, ERK pathway was assessed by Western blotting with phospho–specific antibodies to the effector proteins. The production of IL–6 and IL–8 in challenged cells was measured using ELISA and of antimicrobial peptide human beta–defensin–2(hBD–2) by slot blot. PCR was used to detect the mRNA expression of IL–6, IL–1ß, IL–8, TNF–α, hBD–2 during the time course of BLPs stimulation. To verify the involvement of BLPs and TLR2 in the process, lipase, TLR2 neutralizing antibody and human embryonic kidney (HEK) cell lines expressing individual TLR were also used.
Exposure of HUCL cells to BLPs resulted in the activation of NF–ΚB and JNK, P38 and ERK pathway. Concomitant with their activation, production of IL–6, IL–1ß, IL–8, TNF–α, and hBD–2 in HUCL cells was also induced in HUCL cells stimulated with BLPs. Digestion of BLPs with lipase resulted in the loss of their stimulatory effects on HUCL cells. TLR2 neutralizing antibody attenuated BLPs–induced NF–ΚB activation and IL–6, IL–1ß, IL–8, TNF–α, hBD–2 gene expression and production. BLPs activated HEK cell line expressing TLR2, but not control or that expressing TLR9.
Human corneal epithelial cells recognize and respond to BLPs isolated from keratitis causing bacteria P. aeruginosa and S. aureus via TLR2.
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