The Induction of IL-33 in the Sinus Epithelium and Its Influence on T-Helper Cell Responses.

BACKGROUND: Chronic rhinosinusitis (CRS) is characterized by epithelial activation and chronic T-cell infiltration in sinonasal mucosa and nasal polyps. IL-33 is a new cytokine of the IL-1 cytokine family that has a pro-inflammatory and Th2 type cytokine induction property. The role of IL-33 in the pathomechanisms of CRS and its interaction with other T cell subsets remain to be fully understood. METHODS: The main trigger for IL-33 mRNA expression in primary human sinonasal epithelial cells was determined in multiple cytokine and T-cell stimulated cultures. The effects of IL-33 on naïve, Th0 and memory T-cells was studied by PCR, ELISA and flow cytometry. Biopsies from sinus tissue were analyzed by PCR and immunofluorescence for the presence of different cytokines and receptors with a special focus on IL-33. RESULTS: IL-33 was mainly induced by IFN-γ in primary sinonasal epithelial cells, and induced a typical CRSwNP Th2 favoring cytokine profile upon co-culture with T-helper cell subsets. IL-33 and its receptor ST2 were highly expressed in the inflamed epithelial tissue of CRS patients. While IL-33 was significantly up-regulated in the epithelium for CRSsNP, its receptor was higher expressed in sinus tissue from CRSwNP. CONCLUSIONS: The present study delineates the influence of IL-33 in upper airway epithelium and a potential role of IL-33 in chronic inflammation of CRSwNP by enhancing Th2 type cytokine production, which could both contribute to a further increase of an established Th2 profile in CRSwNP.

Dual nature of T cell-epithelium interaction in chronic rhinosinusitis.

BACKGROUND: T-cell infiltration of submucosa, release of proinflammatory cytokines leading to epithelial activation, and contributions to inflammation are observed in chronic rhinosinusitis (CRS). OBJECTIVES: Molecular mechanisms and kinetics of T-cell interaction with sinus epithelium leading to activation followed by subsequent apoptosis of epithelial cells were the focus of the current study. METHODS: Primary human sinus epithelial cells and T cells generated from sinus tissues of healthy individuals and patients with CRS with or without allergy and sinus tissue biopsies were characterized in terms of activation (surface marker expression, cytokine production via real-time PCR, confocal microscopy, ELISA) and apoptosis (annexin V/7-amino-actinomycin D staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, receptor expression by flow cytometry, confocal microscopy) of epithelial cells. RESULTS: Primary human sinus epithelial cells isolated from patients with CRS were at an activated state with upregulated expression of HLA-DR, IFN-gamma-inducible protein 10, monokine induced by IFN-gamma, and TNF-related apoptosis-inducing ligand (TRAIL) compared with healthy individuals. The expressions of these chemokines, HLA-DR, TRAIL, and TNF receptor 2 were significantly induced by IFN-gamma, whereas TRAIL receptor 4 was downregulated. Epithelial cells started to undergo apoptosis 48 hours after IFN-gamma stimulation when the transcription of proinflammatory cytokines and chemokines decreased to initial levels. The essential factors for sinus epithelial apoptosis were T(H)1 cells and IFN-gamma. Epithelial apoptosis was enhanced by Fas-Fas-ligand and TRAIL-TRAIL receptor 2 interactions. Remarkable apoptosis of epithelial cells and shedding was observed in CRS in situ. CONCLUSION: Epithelial cell interaction with activated T cells is a biphasic phenomenon in CRS. Initially activated T cells lead to activation and induction of proinflammatory functions of epithelial cells, and thereafter their apoptotic death, resulting in no more contribution to inflammation, takes place.

Differentiation and functional analysis of human T(H)17 cells.

BACKGROUND: T(H)17 cells are of pathologic relevance in autoimmune disorders and presumably also in allergy and asthma. Regulatory T (Treg) cells, in contrast, suppress inflammatory and allergen-driven responses. Despite these disparate functions, both T-cell subsets have been shown to be dependent on TGF-beta for their development. OBJECTIVE: The aim of the study was to analyze the differentiation and function of human T(H)17 cells in comparison with other T(H) cell subsets. METHODS: Naive human CD4(+) T cells were differentiated in vitro, and gene expression was analyzed by means of quantitative real-time PCR, ELISA, and immunofluorescence. The function of T(H) cell subsets was assessed by monitoring the response of primary bronchial epithelial cells in coculture experiments. RESULTS: In vitro differentiated T(H)17 cells differ from Treg and other T(H) cells in their potency to induce IL-6 and IL-1beta expression in primary bronchial epithelial cells. TGF-beta, IL-1beta, IL-6, and IL-23 are necessary during T(H)17 cell differentiation to acquire these functions, including IL-17 production. In contrast, TGF-beta alone is necessary and sufficient to induce the transcription factor RORC2. This transcription factor, previously thought to be specific for T(H)17 cells, is also expressed in Treg cells, CD25(+) cells, cytotoxic T cells, and natural killer T cells. CONCLUSION: This study demonstrates mechanisms of differentiation to human T(H)17 cells, a subset that effectively and uniquely modulates the function of primary bronchial epithelial cells.

T-cell regulation in chronic paranasal sinus disease.

BACKGROUND: Chronic rhinosinusitis is an inflammatory disease with distinct cytokine and remodeling patterns. Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by a T(H)2-skewed eosinophilic inflammation, whereas chronic rhinosinusitis without nasal polyps (CRSsNP) represents a predominant T(H)1 milieu. OBJECTIVE: We aimed to study the direct tissue expression of transcription factors for T-cell subpopulations, including T regulatory cells, in relation to the cytokine expression patterns in the different disease subgroups. METHODS: The expression of forkhead box P3 (FOXP3), T-box transcription factor (T-bet), GATA-3, retinoid acid-related orphan receptor C (RORc), the suppressive cytokines TGF-beta1 and IL-10, and T(H)1/ T(H)2/ T(H)17 cytokines (IFN-gamma, IL-4, IL-5, IL-13, IL-17) were analyzed by means of RT-PCR in 13 CRSsNP, 16 CRSwNP, and 10 control samples. Additional protein measurements were performed for TGF-beta1 and IFN-gamma. RESULTS: In CRSwNP, we observed a significantly lower FOXP3 mRNA and TGF-beta1 protein expression, but a significantly higher T-bet, GATA-3, IL-5, and IL-13 mRNA expression compared with controls, whereas RORc was not significantly different compared with controls. In CRSsNP, FOXP3, T-bet, GATA-3, and RORc expression was not significantly different from controls, whereas TGF-beta1 mRNA, IFN-gamma mRNA, and protein were significantly higher in CRSsNP compared with controls. For IL-17, no significant differences were noted among all groups. CONCLUSION: We demonstrate for the first time a decreased FOXP3 expression accompanied by an upregulation of T-bet and GATA-3 and a downregulation of TGF-beta1 in CRSwNP versus controls and CRSsNP.