Background Interleukin 6 (IL-6) activates Th17 cells and regulates the response of B-lymphocytes and T regulatory cells. The IL-6 receptor and the membrane protein, gp130, form an active signaling complex that signals through STAT3 and other signaling molecules. Both the IL-6 receptor (IL-6R) and gp130 can be found in soluble forms that regulate the pathway. Objective We measured IL-6 signaling components and IL-17 in chronic rhinosinusitis with nasal polyps (CRSwNP), CRS without nasal polyps (CRSsNP) and controls to assess the IL-6 pathway in CRS. Methods IL-6, soluble IL-6R (sIL-6R), soluble gp130 (sgp130), and IL-17 were measured in sinus tissue extracts and in nasal lavage fluid by either cytokine bead array or ELISA. phosphoSTAT3 (p-STAT3) was determined by western blot and by immunohistochemistry. Results IL-6 protein was significantly (p<0.001) increased in CRSwNP compared to CRSsNP and controls. sIL-6R was also increased in nasal polyp compared to control tissue (p<0.01). Despite elevated IL-6 and sIL-6R, IL-17A, E, and F were undetectable in the sinus tissue from most of the patients with CRS and controls. p-STAT3 levels were reduced in the polyp tissue, possibly indicating reduced activity of IL-6 in the tissue. sgp130 was elevated in CRSwNP compared to CRSsNP and controls. Conclusion p-STAT3 levels are decreased in CRSwNP despite increased levels of IL-6 and sIL-6R and are associated with the absence of an IL-17 response. This may be a response to elevated levels of sgp130, a known inhibitor of IL-6 signaling. These results indicate that IL-6 and its signaling pathway may be altered in CRSwNP. Clinical implications The IL-6 signaling pathway may have a pathogenic role in CRSwNP.

Background-Chronic rhinosinusitis (CRS) is a disease characterized by inflammation of the nasal mucosa and paranasal sinuses. This inflammation may result in part from decreased epithelial barrier and innate immune responses, leading to frequent bacterial and fungal colonization. The objectives of this study were to investigate the expression of innate immune proteins of the Palate Lung and Nasal epithelium Clone (PLUNC) family in patients with CRS.

Macrophages and their precursors, monocytes, are key cells involved in the innate immune response. Although both monocytes and macrophages produce caspase-1, the key enzyme responsible for pro-IL-1β processing; macrophages are limited in their ability to activate the enzyme and release functional IL-1β. In this context, because mutations in the pyrin gene (MEFV) cause the inflammatory disorder familial Mediterranean fever, pyrin is believed to regulate IL-1β processing. To determine whether variations in pyrin expression explain the difference between monocytes and macrophages in IL-1β processing and release, pyrin was studied in human monocytes and monocyte-derived macrophages. Although monocytes express pyrin mRNA and protein, which is readily inducible by endotoxin, monocyte-derived macrophages express significantly less pyrin mRNA and protein. Pyrin levels directly correlated with IL-1β processing in monocytes and macrophages; therefore, we asked whether pyrin might promote IL-1β processing and release. HEK293 cells were transfected with pyrin, caspase-1, apoptotic speck protein with a caspase recruitment domain, and IL-1β. Pyrin induced IL-1β processing and release in a dose-dependent manner. Conversely, pyrin small interference RNA suppressed pro-IL-1β processing in both THP-1 cells and fresh human monocytes. In summary, both pyrin expression and IL-1β processing and release are diminished upon the maturation of monocytes to macrophages. When pyrin is ectopically expressed or silenced, IL-1β processing and release parallels the level of pyrin. In conclusion, in the context of endotoxin-induced activation of mononuclear phagocytes, pyrin augments IL-1β processing and release.

Relative to monocytes, human macrophages are deficient in their ability to process and release IL-1β. In an effort to explain this difference, we used a model of IL-1β processing and release that is dependent upon bacterial escape into the cytosol. Fresh human blood monocytes were compared with monocyte-derived macrophages (MDM) for their IL-1β release in response to challenge with Francisella novicida. Although both cell types produced similar levels of IL-1β mRNA and intracellular pro-IL-1β, only monocytes readily released processed mature IL-1β. Baseline mRNA expression profiling of candidate genes revealed a remarkable deficiency in the pyrin gene, MEFV, expression in MDM compared with monocytes. Immunoblots confirmed a corresponding deficit in MDM pyrin protein. To determine whether pyrin levels were responsible for the monocyte/MDM difference in mature IL-1β release, pyrin expression was knocked down by nucleofecting small interfering RNA against pyrin into monocytes or stably transducing small interfering RNA against pyrin into the monocyte cell line, THP-1. Pyrin knockdown was associated with a significant drop in IL-1β release in both cell types. Importantly, M-CSF treatment of MDM restored pyrin levels and IL-1β release. Similarly, the stable expression of pyrin in PMA-stimulated THP-1-derived macrophages induces caspase-1 activation, associated with increased IL-1β release after infection with F. novicida. In summary, intracellular pyrin levels positively regulate MDM IL-1β responsiveness to Francisella challenge.

Background Chronic rhinosinusitis (CRS) is a multifactorial disease of unknown etiology characterized by sinonasal inflammation, increased mucus production and defective mucociliary clearance. Pendrin, an epithelial anion transporter, is increased in asthma and chronic obstructive pulmonary disease. Pendrin increases mucus production and regulates mucociliary clearance. Objectives We sought to investigate the expression of pendrin and the mucus-related protein Muc5AC in sinonasal tissues of control and CRS patients, and to evaluate the regulation of pendrin expression in nasal epithelial cells (NECs) in vitro. Methods The expression and distribution of pendrin in sinonasal tissues was analyzed using real-time PCR, immunoblot analysis and immunohistochemistry. Differentiated NECs were used to study the regulation of pendrin expression. Results Increased pendrin was observed in NP tissue of CRS patients. Immunohistochemistry analysis revealed that pendrin was largely restricted to the epithelial layer. Pendrin expression significantly correlated with inflammatory cell markers, suggesting that the factors made by these cells may induce pendrin expression. Furthermore, both pendrin and periostin (a biomarker in asthma) correlated with IL-13, suggesting that pendrin may be induced by this cytokine in sinonasal tissues. The mucus component protein Muc5AC, correlated weakly with pendrin, indicating that pendrin might modulate mucus production in NPs. In cultured NECs, pendrin expression was induced by Th2 cytokines and was induced synergistically when Th2 cytokines were combined with IL-17A. Interestingly, human rhinovirus had a potentiating effect on IL-13 induced pendrin expression. Dexamethasone suppressed pendrin expression suggesting that the therapeutic benefit of dexamethasone in asthma and CRS may involve regulation of pendrin expression. Conclusions Th2-mediated pendrin expression is increased in nasal polyps of patients with CRS and may lead to increased inflammation, mucus production and a decreased mucociliary clearance.