Role of TLRs in the production of chemical mediators in nasal polyp fibroblasts by fungi.

OBJECTIVE: Fibroblasts are major supporting cells in nasal mucosa and can induce inflammatory process with recruitment of inflammatory cells. Airborne fungi have been suggested as an etiologic factor of chronic rhinosinusitis (CRS). The aim of this study was to investigate the interaction between airborne fungi and pattern recognition receptors (PRRs) in nasal fibroblasts.

METHODS: Primary nasal polyp fibroblasts were cultured with Alternaria and Aspergillus for 48h. To determine the production of chemical mediators interleukine-6 (IL-6), IL-8, granulocyte-macrophage colony stimulating factor (GM-CSF), eotaxin, and regulated on activation normal T expressed and secreted (RANTES) were measured with enzyme immunoassay methods. PRRs for toll-like receptors (TLRs) and protease-activated receptors (PARs) mRNA were determined with reverse transcription polymerase chain reaction (RT-PCR). To determine the role of PRRs, fibroblasts were treated with small interfering RNA (siRNA).

RESULTS: IL-6 and IL-8 productions were significantly increased by 50 and 100μg/ml of Alternaria. However, GM-CSF, eotaxin, and RANTES productions did not change. Aspergillus did not influence the production of chemical mediators from nasal polyp fibroblasts. TLR2 and TLR5 mRNA expressions were significantly increased by fungi and these two TLRs were associated with the production of IL-6 and IL-8.

CONCLUSION: Alternaria interacts as a pathogen-associated molecular pattern with the PRRs, such as TLR2 and TLR5, which induce the production of inflammatory chemical mediators from nasal polyp fibroblasts. Airborne fungi enhance the innate immune defense mechanism and may be associated with the pathogenesis of nasal inflammatory diseases.