Potential Effect Of IL-18and P100Protein On The Formation Of Human Nasal Polyps

Objectives:Nasal polyposis is a chronic inflammatory disease of the nasal mucosa. The etiology and mechanisms of the formation of nasal polyps are still not clear. Interleukin (IL)-18is a novel proinflammatory cytokine that plays important roles in regulating immune inflammatory responses。 p100protein on the other hand can combine with many kinds of transcription factors. It is a ubiquitously and highly conserved protein expressed in a wide range of eukaryotes from yeasts to human. However, the presence of IL-18and p100protein in human nasal mucosa and their roles in the inflammatory process of nasal polyps has not been studied yet. In the present study, we investigate the expression of IL-18and p100protein in human nasal mucosa and nasal polyps, and their potential function in the formation of nasal polyps.Methods:Part I:The expression of IL-18and p100in nasal polyps. Nasal mucosa of control samples and nasal polyp samples were obtained. Each sample was divided into two parts. One part was homogenized immediately and quick-frozen for Western blot analysis. The other was fixed in a10%neutral formaldehyde solution and embedded in paraffin for hematoxylin-eosin staining and immunohistochemistry.Part II:The potential role of IL-18in the formation of nasal polyps. A549cells, which is often used as representative of respiratory epithelial cells, were treated with LPS (1μg/ml) or IL-4(50ng/ml), to some extent, mimic infection and inflammation. Then detect the expression of IL-18in order to verify that epithelial cells can express more IL-18and IL-18can be regulated by other cytokines such as IL-4. Thus, evaluation of their expression will provide new insights into the pathophysiological roles of IL-18in the pathogenesis of nasal polyp formation, and in the potential role of epithelial cells in this process.Part III:The potential role of p1OO in the formation of nasal polyps. In this part, we divide the study into two parts. In the first part, we treat A549cells with LPS and IL-4to mimic LPS/TLR4and IL-4/STAT6signal pathways respectively. Then, we detect the expression of IL-8, IL-6, STAT6and p1OO. We also detect the expression of p100protein in the bronchial epithelial cell of mouse lung which were treated with LPS and OVA also to mimic LPS/TLR4and IL-4/STAT6signal pathway. In the second part, we want to study the relationship between pi00protein and proliferation. We also divide this study into two parts:①we detect the expression of p100protein in mouse tissues with different proliferation status and the expression of p100protein in different peripheral blood cells.②we detect if p100protein can combine with c-Myc protein by COIP and detect if the expression of p100protein can influence the expression of c-Myc protein.Results:Part I:We observed that in both the normal sinus mucous and nasal polyps, IL-18, IFN-y and IL-4immunoreactivity was observed in the epithelium, submucosal glandular cells and the inflammatory cells. Moreover, the intensity of the IL-18, IFN-y and IL-4bands in the eosinopbilic nasal polyps were higher than that of non-eosinophilic nasal polyps. We also observed p100protein is expressed in the epithelium, submucosal glandular cells in nasal polyps, but absent in80%of eosinophils.Part II:We found that IL-18is expressed in A549cells and the expression of IL-18was increased after LPS treatment. The18-kDa mature form of IL-18could only be detected after LPS treatment, but was absent in the control groups. We also found that IL-18expression was lower after IL-4treatment in A549cells. Cytokines from airway epithelial cells can regulate each other.Part III:pi00protein take part in IL-4/STAT6signal pathway but not in LPS/TLR4signal pathway in the process of inflammation. Further more, p100protein maybe related with cell cycle and tissues proliferation. And our result showed that p100protein take part in the cell cycle not in c-Myc pathway but may be in other signal pathway.Conclusions:IL-18and p100protein expressed in normal nasal mucous and in nasal polyps. Since mIL-18only can be detected in nasal polyps, IL-18play an important role in the formation of nasal polyps. Nasal epithelial cells maybe the "initiator" in the formation of nasal polyps since they are the first physical barriers against airborne particles from the environment and can release lots of cytokines such as IL-18、 IL-4、 IFN-yand so on. p100protein takes part in IL-4/STAT6signal pathway but not in LPS/TLR4signal pathway in the process of inflammation, p100protein is related with the cell cycle and tissues proliferation and plays an important role in the formation of nasal polyps.