Activation of human bronchial epithelial cells by inflammatory cytokines IL-27 and TNF-alpha: implications for immunopathophysiology of airway inflammation.
ABSTRACT Interleukin (IL)-27 is a member of IL-6/IL-12 family cytokines produced by antigen-presenting cells in immune responses. IL-27 can drive the commitment of naive T cells to a T helper type 1 (Th1) phenotype and inhibit inflammation in later phases of infection. Human bronchial epithelial cells have been shown to express IL-27 receptor complex. In this study, we investigated the in vitro effects of IL-27, alone or in combination with inflammatory cytokine tumor necrosis factor (TNF)-alpha on the pro-inflammatory activation of human primary bronchial epithelial cells and the underlying intracellular signaling mechanisms. IL-27 was found to enhance intercellular adhesion molecule 1 (ICAM-1) expression on the surface of human bronchial epithelial cells, and a synergistic effect was observed in the combined treatment of IL-27 and TNF-alpha on the expression of ICAM-1. Although IL-27 did not alter the basal IL-6 secretion from bronchial epithelial cells, it could significantly augment TNF-alpha-induced IL-6 release. These synergistic effects on the up-regulation of ICAM-1 and IL-6 were partially due to the elevated expression of TNF-alpha receptor (p55TNFR) induced by IL-27. Further investigations showed that the elevation of ICAM-1 and IL-6 in human bronchial epithelial cells stimulated by IL-27 and TNF-alpha was differentially regulated by phosphatidylinositol 3-OH kinase (PI3K)-Akt, p38 mitogen-activated protein kinase, and nuclear factor-kappaB pathways. Our results therefore provide a new insight into the molecular mechanisms involved in airway inflammation.
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ABSTRACT: The mechanisms underlying the increased susceptibility of the elderly to respiratory infections are not well understood. The crosstalk between the dendritic cells (DCs) and epithelial cells is essential in maintaining tolerance as well as in generating immunity in the respiratory mucosa. DCs from aged subjects display an enhanced basal level of activation, which can affect the function of epithelial cells. Our results suggest that this is indeed the scenario as exposure of primary bronchial epithelial cells (PBECs) to supernatants from unstimulated DCs of aged subjects resulted in activation of PBECs. The expression of CCL20, CCL26, CXCL10, mucin, and CD54 was significantly increased in the PBECs exposed to aged DC supernatants, but not to young DC supernatants. Furthermore, aged DC supernatants also enhanced the permeability of the PBEC barrier. We also found that DCs from aged subjects spontaneously secreted increased levels of pro-inflammatory mediators, interleukin-6, tumor necrosis factor (TNF)-α, and metalloproteinase A disintegrin family of metalloproteinase 10, which can affect the functions of PBECs. Finally, we demonstrated that TNF-α, present in the supernatant of DCs from aged subjects, was the primary pro-inflammatory mediator that affected PBEC functions. Thus, age-associated alterations in DC-epithelial interactions contribute to chronic airway inflammation in the elderly, increasing their susceptibility to respiratory diseases.Mucosal Immunology advance online publication, 23 April 2014; doi:10.1038/mi.2014.28.Mucosal Immunology 04/2014; · 7.54 Impact Factor
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ABSTRACT: IL-27 is involved in inflammatory reactions. CXCL10 is an important chemokine contributing to airway inflammatory diseases. In this study, we investigated whether IL-27 modulated the synthesis of CXCL10 in primary human lung fibroblasts (HLF). HLF were activated by IL-27 alone, or in combination with other cytokines. CXCL10 synthesis was measured by real-time PCR and ELISA. Examination of transcriptional regulation was performed via transient transfection of promoter constructs, whereas mRNA stability was assessed by actinomycin D chase and real-time PCR. The underlying signaling pathways were studied by Western blot and intracellular staining using flow cytometry. Our results demonstrated that IL-27 induced and synergized with TNF-α to upregulate CXCL10 mRNA and protein levels in a steroid-insensitive manner. This synergistic CXCL10 production was dependent on transcriptional regulation of CXCL10 gene promoter activity and the enhanced stability of CXCL10 mRNA by IL-27 and TNF-α, and this synergism was regulated by the activation of p38 MAPK and PI3K-Akt dominantly and in a little part via NF-kB. Interestingly, IL-27 promoted basal and enhanced TNF-α-induced phosphorylation of p38 MAPK and Akt, but not IkBα. Besides, the enhanced CXCL10 mRNA stability occurred via a p38 MAPK-dependent pathway. Finally, clinical analysis showed that IL-27 was detected in BAL of patients with asthma, COPD, and PTB, and the increased IL-27 levels was correlated with the increased CXCL10 levels in patients with COPD and PTB. Our findings suggest that IL-27 has the potential to amplify airway inflammation via the induction of CXCL10 from HLF in combination with TNF-α.American Journal of Respiratory Cell and Molecular Biology 01/2013; · 4.15 Impact Factor
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ABSTRACT: Airway epithelium acts as multifunctional site of response in the respiratory tract. Epithelial activity plays an important part in the pathophysiology of obstructive lung disease. In this study, we compare normal human epithelial cells from various levels of the respiratory tract in terms of their reactivity to pro-allergic and pro-inflammatory stimulation. Normal human nasal, bronchial and small airway epithelial cells were stimulated with IL-4 and IL-13. The expressions of the eotaxins IL-6 and CXCL8 were evaluated at the mRNA and protein levels. The effects of pre-treatment with IFN-γ on the cell reactivity were measured, and the responses to TNF-α, LPS and IFN-γ were evaluated. All of the studied primary cells expressed CCL26, IL-6 and IL- 8 after IL-4 or IL-13 stimulation. IFN-γ pre-treatment resulted in decreased CCL26 and increased IL-6 expression in the nasal and small airway cells, but this effect was not observed in the bronchial cells. IL-6 and CXCL8 were produced in varying degrees by all of the epithelial primary cells in cultures stimulated with TNF-α, LPS or IFN-γ. We showed that epithelial cells from the various levels of the respiratory tract act in a united way, responding in a similar manner to stimulation with IL-4 and IL-13, showing similar reactivity to TNF-α and LPS, and giving an almost unified response to IFN-γ pre-stimulation.Cellular & Molecular Biology Letters 12/2013; · 1.95 Impact Factor