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Infection and Immunity, August 2003, p. 4289-4296, Vol. 71, No. 8
0019-9567/03/$08.00+0 DOI: 10.1128/IAI.71.8.4289-4296.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.
Division of Otologic Research, College of Medicine and Public Health, The Ohio State University, Columbus, Ohio 43210
Received 19 March 2003/ Returned for modification 24 April 2003/ Accepted 14 May 2003
Real-time PCR and enzyme-linked immunosorbent assay were used to evaluate the ability of influenza A virus and Streptococcus pneumoniae opacity variants, either alone or in combination, to induce cytokine and chemokine genes in primary cultures of human middle ear epithelial (HMEE) cells. Following treatment with influenza A virus, the induction of gene expression, which occurred in a dose- and time-dependent manner, was strong for macrophage inflammatory protein 1
(MIP-1
) and MIP-1ß; moderate for tumor necrosis factor alpha (TNF-
), interleukin-6 (IL-6), and IL-8; and weak for IL-1ß and monocyte chemotactic peptide 1 (MCP-1). Except for TNF-
, all the gene products were detected in the cell culture supernatants. In contrast, infection of HMEE cells with S. pneumoniae alone induced low levels of mRNA expression of MIP-1
and MIP-1ß and did not significantly induce the transcription of the other cytokines and chemokines examined. However, both S. pneumoniae opacity variants increased mRNA expression of MIP-1
, MIP-1ß, IL-6, and MCP-1 in HMEE cells activated by a prior influenza A virus infection compared to levels in cells treated with either agent alone. Up-regulation of IL-6, IL-8, and MCP-1 mRNA expression and production by the virus in combination with opaque S. pneumoniae was two- to threefold higher than that induced by the virus combined with the transparent S. pneumoniae variant. These data indicate that the activation of HMEE cells by influenza A virus enhances the induction of cytokine and chemokine gene transcripts by S. pneumoniae and that this effect appears to be most pronounced when S. pneumoniae is in the opaque phase.
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