Abstract
Purpose:
We investigated the expression and function of thymic stromal lymphopoietin (TSLP) in telomerase-immortalized human corneal epithelial cells (THCEs) and telomerase-immortalized human stroma fibroblasts (THSFs) challenged by A. fumigatus hyphae and its relationship with Toll-like receptors (TLR).
Methods:
We stimulated THCEs and THSFs with TLR2 Ligand zymosan, TLR4 ligand lipopolysaccharide (LPS), human recombinant TSLP or A. fumigatus hyphae for various periods, with or without the inhibition of TLR2, TLR4 or TSLP using monoclonal antibody or small interfering RNA previously. The release and expression of TLR2, TLR4, TSLP, IL-4, IL-8, IL-13 and TNF-α were measured by means of ELISA, quantitative RT-PCR or western blot.
Results:
It was demonstrated that enhanced expression of TSLP, IL-4 and IL-13 was associated with the treatment of A. fumigatus hyphae in human corneal cell lines. Stimulation of THCEs and THSFs with TLR2 Ligand zymosan or TLR4 ligand lipopolysaccharide (LPS) induced upregulated gene expression and release of TSLP; Inhibition of either TLR2 or TLR4 with monoclonal antibody impaired the A. fumigatus hyphae-induced TSLP and its downstream cytokines expression. The human recombinant TSLP augmented genetic and protein levels of TLR2 and TLR4 in human corneal cell lines; Small interfering RNA-mediated knockdown of TSLP hindered the expression of TLRs, IL-8 and TNF-α in AF-treated THCEs and THSFs.
Conclusions:
These results indicated that TSLP, as a critical factor in adaptive immunity, participated in the immune response of THCEs and THSFs challenge by Aspergillus fumigates, which is closely related to the function of TLRs, key players in innate immunity. At the same time, the innate immunity mediated by TLRs could be enhanced by TSLP in AF-treated THCEs and THSFs. Thus, TSLP may serve as a link between the innate and adaptive immune responses in corneal cell lines infected by Aspergillus fumigates.