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- Title
Expression of surfactant protein D in human corneal epithelial cells is upregulated by Pseudomonas aeruginosa.
- Authors
Ni, Minjian; Tam, Connie; Verma, Amrisha; Ramphal, Reuben; Hawgood, Samuel; Evans, David J; Fleiszig, Suzanne M J
- Abstract
We reported previously that surfactant protein D (SP-D) was present in human tears and corneal epithelial cells, and that it contributed to tear fluid protection of those cells against Pseudomonas aeruginosa invasion. This suggested a role in ocular innate immunity. Here, we explored the effects of bacterial challenge on SP-D expression by human corneal epithelial cells. Results showed that these cells produced and secreted SP-D constitutively in culture, and that production (mRNA, protein) and secretion of SP-D were upregulated after exposure to heat-killed P. aeruginosa or to purified flagellin or lipopolysaccharide. To begin exploring the mechanism for flagellin-mediated SP-D induction, cells were exposed to purified flagellin or flagellin mutated in the TLR-5-binding domain (L94A, L88A) which reduces IL-8 secretion by A549 respiratory cells. Mutated flagellin did not upregulate IL-8 expression in corneal epithelial cells, but did induce SP-D responses. Mitogen-activated protein kinase inhibitors, especially the JNK inhibitor SP600125, reduced secretion of SP-D, but not production, in the presence of P. aeruginosa. These data show that while SP-D and IL-8 corneal responses are each induced by P. aeruginosa or its antigens, they can involve different regions of the same ligand. The data suggest that separate mechanisms may regulate SP-D secretion and production by human corneal epithelia.
- Publication
FEMS immunology and medical microbiology, 2008, Vol 54, Issue 2, p177
- ISSN
0928-8244
- Publication type
Journal Article
- DOI
10.1111/j.1574-695X.2008.00461.x