April 2010
Volume 51, Issue 13
ARVO Annual Meeting Abstract  |   April 2010
Acanthamoeba Infections Initiate Toll-Like Receptor 4 Expression and Inflammatory Responses in the Corneal Epithelium
Author Affiliations & Notes
  • H. Alizadeh
    Department of Cell Biology and Anatomy, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas
  • H. Li
    Department of Ophthalmology, UT Southwestern Medical School, Dallas, TX, Dallas, Texas
  • S. Neelam
    Alcon Research Ltd., Fort Worth, Texas
  • Footnotes
    Commercial Relationships  H. Alizadeh, None; H. Li, None; S. Neelam, None.
  • Footnotes
    Support  This work was supported by NIH grants EY009756
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 3910. doi:
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      H. Alizadeh, H. Li, S. Neelam; Acanthamoeba Infections Initiate Toll-Like Receptor 4 Expression and Inflammatory Responses in the Corneal Epithelium. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3910.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : To determine if Toll-like receptors (TLRs) on corneal epithelial cells are activated by Acanthamoeba, leading to initiation of inflammatory responses in the cornea.

Methods: : The expression of mRNA for TLR1, TLR2, TLR3, TLR4, and TLR9 in normal and A. castellanii infected human corneal epithelial (HCE) cells were examined by RT-PCR. Secretion of IL-8 and IL-6 was examined by ELISA. To determine whether Acanthamoeba trophozoites modulate the expression of TLRs in Chinese hamster corneal epithelial cells, hamsters were infected with pathogenic A. castellanii and non-pathogenic A. castellanii neff strains of Acanthamoeba trophozoites. The expression of TLR1, TLR2, TLR3, TLR4, TLR9, genes was examined by RT-PCR. Production of MIP-2 by the corneal cells was examined by ELISA.

Results: : HCE cells constitutively expressed TLR1, TLR2, TLR3, TLR4, and TLR9 mRNA, and A. castellanii upregulated TLR2 and TLR4 transcription. Expression of TLR1, TLR3, and TLR9 mRNA was unchanged when HCE cells were exposed to A. castellanii trophozoites. Both IL-6 and IL-8 mRNA expression was upregulated in HCE cells exposed to A. castellanii trophozoites. A. castellanii trophozoites and lipopolysaccharide (LPS) induced significant IL-8 production by HCE cells as measured by ELISA. Clinical isolates of Acanthamoeba (A.castellanii) but not soil isolates (A.castellanii neff) activate TLR4 expression in the Chinese hamster corneas, while TLR2 expression was unchanaged..A.castellanii but not A.castellanii neff trophozoites induced significant (P<0.05) MIP-2 production in Chinese hamster corneas 3 and 7 days after infection.

Conclusions: : These results suggest that A. castellanii trophozoitesactivate TLR2 and TLR4 and induce IL-6 and IL-8 secretion in HCE cells. A. castellanii trophozoitesactivate TLR4 andinduce production of MIP-2 in the Chinese hamster corneas.

Keywords: Acanthamoeba • keratitis • cornea: basic science 

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