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Background Although increased accumulation of neutrophils has been noted in chronic rhinosinusitis (CRS), the function and regulation of neutrophils in CRS are largely unknown. IL-36 family cytokines may play an important role in neutrophilic inflammation. Objective This study sought to investigate the expression and function of IL-36 cytokines in CRS. Methods Quantitative RT-PCR, immunohistochemistry, immunofluorescence, and ELISA were used to investigate the expression of IL-36 cytokines and IL-36 receptor (IL-36R) in sinonasal mucosa. The expression of IL-36R on neutrophils in polyps and blood was measured by flow cytometry. Purified blood neutrophils were cultured to investigate the regulation of IL-36R expression. The cleavage of IL-36γ was detected by Western blotting. Dispersed nasal polyp cells were treated with IL-36γ with or without elastase inhibitor and dexamethasone. Results Neutrophil infiltration and expression of IL-36 cytokines and IL-36R were upregulated in both CRS with and without nasal polyps. IL-36γ was the most abundant isoform and mainly expressed by epithelial cells in CRS. Neutrophils were the principal IL-36R + cell type in polyps. IL-36R expression was almost absent in blood neutrophils and upregulated by IL-6, IL-1β, and Dermatophagoides pteronyssinus group 1. Elastase activity was increased in polyps and degraded full-length IL-36γ. Consistently, the levels of cleaved IL-36γ were increased in polyps. Full-length IL-36γ promoted the production of matrix metalloproteinase 9; IL-17A; and chemokine (C-X-C motif) ligands 1, 2, and 8 from dispersed nasal polyp cells, which was abolished by elastase inhibitor. The proinflammatory effect of IL-36γ was not suppressed by dexamethasone. Conclusions Increased production and activation of IL-36γ may act on neutrophils and further exaggerate neutrophilic inflammation in CRS.

While a variety of genetic mutations have been shown to be associated with renal cyst formation, mechanisms of renal cyst formation are largely unknown. In prior communications we described alterations in E-cadherin assembly in cultured cystic epithelial cells (Charron AJ, Nakamura S, Bacallao R, Wandinger-Ness A. J Cell Biol 149: 111–124, 2000). Using the same cell line we assayed cadherin expression by RT-PCR using primer pairs that anneal to highly conserved sequences of cadherin genes but flank informative regions of cadherins. Using this approach we found that autosomal dominant polycystic kidney disease (ADPKD) cells express cadherin 8, a neuronal cadherin with limited expression in the kidney. Immunohistochemistry confirmed cadherin 8 expression in cystic epithelia. To test the functional significance of cadherin 8 expression in renal epithelial cells, we adapted a three-dimensional collagen culture method in which HK-2 cells form tubule structures and microinjected adenovirus into the matrix space surrounding tubule structures. Adenovirus expressing cadherin 8 under the control of a tet promoter caused cyst structures to grow out of the tubules when coinjected with adenovirus expressing a tet transactivator. Microinjection of single adenovirus expressing either tet transactivator or cadherin 8 failed to cause cyst formation. When doxycycline was added to the culture, following coinjection of adenovirus, there was a dose-response reduction in cadherin 8 expression and cyst formation. Similarly, HK-2 cells transfected with Flag-tagged cadherin 8 form cysts in addition to tubular structures. HK-2 cells transfected with Flag-tagged N-cadherin do not form cysts. These data suggest that ectopic expression of cadherin 8 in renal epithelial cells is sufficient to cause the morphogenic pattern of cyst formation.