Purchase this article with an account.
X. Wu, J. Gao, J. Zhao; Activation of Toll-Like Receptor (TLR)2 and TLR4 in the Human Corneal Epithelium Induced by Aspergillus fumigatus. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3650.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To determine whether human corneal epithelial cells and cultured telomerase-immortalized human corneal epithelial (THCE) cells express Toll-like receptor (TLR)2 and TLR4 and whether these expressions are altered when THCE cells are challenged with Aspergillus fumigatus.
The localization and expression of TLR2 and TLR4 in human corneal epithelial cells and THCE cells were analyzed by western blot and immunocytochemistry using anti-TLR2 and anti-TLR4 antibodies. A. fumigatus hyphae and supernatant purified from A. fumigatus cultures were used to challenge THCE cells. Inhibitory IΚB-α degradation was detected by Western blot. The expressions of Interleukin (IL)-8 and TNF-α were assessed using enzyme-linked immunosorbent assay (ELISA). Anti-TLR2 antibody and anti-TLR4 antibody were used for functional blocking of TLR2 and TLR4 activation.
The expression of TLR2 and TLR4 was detected in both THCE cells and human corneal epithelial cells. Exposure of THCE cells to purified A. fumigatus hyphae or A. fumigatus supernatant resulted in IΚB-α degradation. Which declined at 30 minutes (decreased from 51.57±5.58 and 49.23±3.49 in the controls to 10.31±1.30 and 8.15±2.37, P<0.01) and thereafter increased steadily up to 2 hours after challenge until it reached the control level. Concomitant with IΚB-α activation, secretion of IL-8 and TNF-α in A. fumigatus hyphae or A. fumigatus supernatant -challenged cells increased, starting 1 hour after challenge and peaking at 8 hours (P<0.01). Incubation of THCE cells with anti-TLR2 antibody or anti-TLR4 antibody for 30 minutes before A. fumigatus hyphae challenge resulted in inhibition of A. fumigatus hyphae-induced IL-8 and TNF-α secretion (P<0.05), whereas anti-TLR2 antibody and anti-TLR4 antibody together significantly inhibited the A. fumigatus hyphae -induced secretion of IL-8 and TNF-α from THCE cells (P<0.01). Use of anti-TLR2 antibody alone did not inhibit the A. fumigatus supernatant-induced secretion of IL-8 and TNF-α from THCE cells (P>0.05), whereas, blocking with anti-TLR4 antibody or anti-TLR2 antibody and anti-TLR4 antibody together significantly inhibited the A. fumigatus supernatant-induced secretion of IL-8 and TNF-α from THCE cells (P<0.01).
A. fumigatus contributes to the secretion of IL-8 and TNF-α from THCE cells in a TLR-NF-ΚB signaling pathway-dependent manner. TLR2 and TLR4 are important receptors of A. fumigatus hyphae in THCE cells, whereas the recognition of A. fumigatus supernatant was mainly induced by TLR4 in THCE cells.
This PDF is available to Subscribers Only