| Background: Respiratory infections are thought to be a leading cause of exacerbationof several airway diseases including asthma, chronic rhinosinusitis and chronicobstructive pulmonary disease. The epithelium is thought to serve an important barrierfunction in the airways. However, growing evidence supports the notion that therespiratory epithelium plays a key role in host responses to infectious and allergenicstimuli. The clear mechanism(s) by which it plays in both the innate and adaptiveimmune response of the airways are not well understood.Objective: To investigate important roles of the respiratory epithelium and theunderlying mechanisms in the innate immune response of the airways. To evaluate theexpression and significance of IL-10,C3,C4,C1q in the pathophysiology of nasalpolyps.Methods: Human pulmonary epithelial-derived cell line A549 was cultured. Heat-inactivated E.coli in different concentration was added 24h after the cells were seeded.The cells were harvested and supernatant were collected at different time points. Theexpression of IL-6, C3 and CRP at the mRNA levels from cells were measured bysemi-quantitative reverse transcription polymerase chain reaction (RT-PCR) analysis.The expression of IL-6, CRP, SAA and C3 at the protein level in the supematant wasmeasured by enzyme-linked immunosorbent assay and immunonephelometry. Theexpression of IL-10,C3,C4,C1q were determinated in 38 tissue samples of nasal polyps and 14 controls from normal inferior turbinates by immunohistochemicalmethod, respectively. The cell types and distributed were analysed in positiveexpression of IL-10,C3,C4,C1q.Results: Heat-inactivated E.coli at different concentrations and for different timeinduced the expression of IL-6, C3 and CRP mRNA and the secretion of IL-6, C3,CRP and SAA in A549 cells with a concentration- and time-dependent manner. Thedifference between each experimental groups and control groups was significant(P＜0.05). There was a significant over-expression of IL-10,C3,C4,C1q in nasalpolyps compared to normal inferior turbinates. The difference between these two groupswas significant (P＜0.01). IL-10,C3,C4,C1q-positive cells were localized inepithelium and inflammatory cells in nasal polyps.Conclusions: The respiratory epithelium produces a lot of nonspecific immunologicalmolecules in host responses to infectious stimuli. These molecules eliminatemicroorganisms positively and play important roles in host responses to infectious. Theepithelium may act as a bridge between innate and adaptive immunity at the mucosalsurface of the airways. IL-10,C3,C4,C1q may play some important roles with localanti-bacterial properties and anti-inflammatory effects in nasal polyps. |
