Innate pattern recognizing receptors (MMR, TLR 2 and TLR4), capable of recognizing pathogen recognizing molecular patterns and signal transduction for proinflammatory mechanisms, might have an important role in immune interactions in chronic sinus disease.

Surgical samples from patients with chronic rhinosinusitis (CS, n=10), nasal polyps (NPs, n=10) and controls (turbinate tissue, n=10) were investigated with real time RT-PCR for MMR, TLR 2 and TLR4 mRNA expression and the presence and location of MMR positive cells was analyzed by immunohistochemistry.

Quantification of MMR mRNA showed a statistically significant higher expression in NPs compared to CS (p=0.04) and controls (p=0.001). Although immunohistochemistry revealed expression of MMR in all tissue samples, only in NP we found an enhanced positive cellular staining including cell aggregates. Quantification of TLR 2 and TLR 4 mRNA showed no difference of expression in CS compared to NP. Yet, TLR-2 and TLR-4 mRNA expression in nasal tissues were significantly correlated (r=0.57, p=0.001) and was found in all tissue samples.

We demonstrated for the first time that the expression of MMR is significantly up-regulated in NP compared to patients with CS or turbinate tissue of controls. Macrophages expressing MMR, accumulated in cell aggregates in NP, play a possible key role in pathogen-macrophage interaction in NP disease. Toll-like receptor expression in all sino-nasal tissue illustrates their possibly important immunological sentinel function in upper airway mucosa.