Effect of lipopolysaccharide on glucocorticoid receptor function in control nasal mucosa fibroblasts and in fibroblasts from patients with chronic rhinosinusitis with nasal polyps and asthma

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease of the upper airways frequently associated with asthma. Bacterial infection is a feature of CRSwNP that can aggravate the disease and the response to glucocorticoid treatment.We examined whether the bacterial product lipopolysaccharide (LPS) reduces glucocorticoid receptor (GR) function in control nasal mucosa (NM) fibroblasts and in nasal polyp (NP) fibroblasts from patients with CRSwNP and asthma.NP (n = 12) and NM fibroblasts (n = 10) were in vitro pre-incubated with LPS (24 hours) prior to the addition of dexamethasone. Cytokine/chemokine secretion was measured by ELISA and Cytometric Bead Array. GR?, GR?, mitogen-activated protein-kinase phosphatase-1 (MKP-1) and glucocorticoid-induced leucine zipper (GILZ) expression was measured by RT-PCR and immunoblotting, GR? nuclear translocation by immunocytochemistry, and GR? localization by immunoblotting. The role of MKP-1 and GILZ on dexamethasone-mediated cytokine inhibition was analyzed by small interfering RNA silencing.Pre-incubation of nasal fibroblasts with LPS enhanced the secretion of IL-6, CXCL8, RANTES, and GM-CSF induced by FBS. FBS-induced CXCL8 secretion was higher in NP than in NM fibroblasts. LPS effects on IL-6 and CXCL8 were mediated via activation of p38?/? MAPK and IKK/NF-?B pathways. Additionally, LPS pre-incubation: 1) reduced dexamethasone's capacity to inhibit FBS-induced IL-6, CXCL8 and RANTES, 2) reduced dexamethasone-induced GR? nuclear translocation (only in NM fibroblasts), 3) did not alter GR?/GR? expression, 4) decreased GILZ expression, and 5) did not affect dexamethasone's capacity to induce MKP-1 and GILZ expression. MKP-1 knockdown reduced dexamethasone's capacity to suppress FBS-induced CXCL8 release.The bacterial product LPS negatively affects GR function in control NM and NP fibroblasts by interfering with the capacity of the activated receptor to inhibit the production of pro-inflammatory mediators. This study contributes to the understanding of how bacterial infection of the upper airways may limit the efficacy of glucocorticoid treatment

Superior effect of MP-AzeFlu than azelastine or fluticasone propionate alone on reducing inflammatory markers

Background: MP-AzeFlu, intranasal formulation of azelastine hydrochloride (AZE) and fluticasone propionate (FP), is superior to AZE or FP alone for treatment of allergic rhinitis (AR). However, the precise anti-inflammatory mechanism of action of MP-AzeFlu has not been characterized. Objective: To investigate the anti-inflammatory effects of MP-AzeFlu compared with AZE or FP alone in an established in vitro model of eosinophilic inflammation. Methods: Nasal mucosal epithelial cells and peripheral blood eosinophils were obtained from human volunteers. Epithelial cells were stimulated with 10% fetal bovine serum (FBS) in the presence of MP-AzeFlu, AZE, or FP (1:102 to 1:105 dilution). Concentrations of interleukin (IL)-6, IL-8, and granulocyte-macrophage colony-stimulating factor (GM-CSF) were measured by ELISA. Eosinophils were incubated in 10% human epithelial cell-conditioned medium (HECM) and survival assessed by trypan blue dye exclusion. Results are expressed as mean ± SEM percentage secretion/survival compared with FBS/HECM (respectively). Results: FP and MP-AzeFlu (all dilutions) and AZE (1:102) significantly reduced IL-6 secretion and eosinophil survival compared with positive controls. At 1:102 dilution, IL-6 secretion was significantly lower with MP-AzeFlu (38.3 ± 4.2%, compared with FBS = 100%) than with AZE (76.1 ± 4.9%) or FP (53.0 ± 4.9%). At 1:102 dilution, eosinophil survival was significantly lower with MP-AzeFlu at day 3 (17.5 ± 3.0%) and day 4 (2.4 ± 1.4%, compared with HECM = 100%) than with AZE (day 3: 75.2 ± 7.2%; day 4: 44.0 ± 9.7%) or FP (day 3: 38.5 ± 3.5%; day 4: 14.6 ± 4.0%). Conclusion: Greater reductions in cytokine secretion and eosinophil survival observed with MP-AzeFlu in vitro may underlie MP-AzeFlu's superior clinical efficacy vs. AZE or FP alone observed in AR patients

Reconstituted human upper airway epithelium as 3-d in vitro model for nasal polyposis.

BACKGROUND: Primary human airway epithelial cells cultured in an air-liquid interface (ALI) develop a well-differentiated epithelium. However, neither characterization of mucociliar differentiation overtime nor the inflammatory function of reconstituted nasal polyp (NP) epithelia have been described. OBJECTIVES: 1st) To develop and characterize the mucociliar differentiation overtime of human epithelial cells of chronic rhinosinusitis with nasal polyps (CRSwNP) in ALI culture system; 2nd) To corroborate that 3D in vitro model of NP reconstituted epithelium maintains, compared to control nasal mucosa (NM), an inflammatory function. METHODS: Epithelial cells were obtained from 9 NP and 7 control NM, and differentiated in ALI culture for 28 days. Mucociliary differentiation was characterized at different times (0, 7, 14, 21, and 28 days) using ultrastructure analysis by electron microscopy; ΔNp63 (basal stem/progenitor cell), β-tubulin IV (cilia), and MUC5AC (goblet cell) expression by immunocytochemistry; and mucous (MUC5AC, MUC5B) and serous (Lactoferrin) secretion by ELISA. Inflammatory function of ALI cultures (at days 0, 14, and 28) through cytokine (IL-8, IL-1β, IL-6, IL-10, TNF-α, and IL-12p70) and chemokine (RANTES, MIG, MCP-1, IP-10, eotaxin-1, and GM-CSF) production was analysed by CBA (Cytometric Bead Array). RESULTS: In both NP and control NM ALI cultures, pseudostratified epithelium with ciliated, mucus-secreting, and basal cells were observed by electron microscopy at days 14 and 28. Displaying epithelial cell re-differentation, β-tubulin IV and MUC5AC positive cells increased, while ΔNp63 positive cells decreased overtime. No significant differences were found overtime in MUC5AC, MUC5B, and lactoferrin secretions between both ALI cultures. IL-8 and GM-CSF were significantly increased in NP compared to control NM regenerated epithelia. CONCLUSION: Reconstituted epithelia from human NP epithelial cells cultured in ALI system provides a 3D in vitro model that could be useful both for studying the role of epithelium in CRSwNP while developing new therapeutic strategies, including cell therapy, for CRSwN

Proteasome inhibition reduces proliferation, collagen expression, and inflammatory cytokine production in nasal mucosa and polyp fibroblasts

Proteasome inhibitors, used in cancer treatment for their proapoptotic effects, have anti-inflammatory and antifibrotic effects on animal models of various inflammatory and fibrotic diseases. Their effects in cells from patients affected by either inflammatory or fibrotic diseases have been poorly investigated. Nasal polyposis is a chronic inflammatory disease of the sinus mucosa characterized by tissue inflammation and remodeling. We tested the hypothesis that proteasome inhibition of nasal polyp fibroblasts might reduce their proliferation and inflammatory and fibrotic response. Accordingly, we investigated the effect of the proteasome inhibitor Z-Leu-Leu-Leu-B(OH)2 (MG262) on cell viability and proliferation and on the production of collagen and inflammatory cytokines in nasal polyp and nasal mucosa fibroblasts obtained from surgery specimens. MG262 reduced the viability of nasal mucosa and polyp fibroblasts concentration- and time-dependently, with marked effects after 48 h of treatment. The proteasome inhibitor bortezomib provoked a similar effect. MG262-induced cell death involved loss of mitochondrial membrane potential, caspase-3 and poly(ADP-ribose) polymerase activation, induction of c-Jun phosphorylation, and mitogen-activated protein kinase phosphatase-1 expression. Low concentrations of MG262 provoked growth arrest, inhibited DNA replication and retinoblastoma phosphorylation, and increased expression of the cell cycle inhibitors p21 and p27. MG262 concentration-dependently inhibited basal and transforming growth factor-β-induced collagen mRNA expression and interleukin (IL)-1β-induced production of IL-6, IL-8, monocyte chemoattractant protein-1, regulated on activation normal T cell expressed and secreted, and granulocyte/macrophage colony-stimulating factor in both fibroblast types. MG262 inhibited IL-1β/tumor necrosis factor-α-induced activation of nuclear factor-κB. We conclude that noncytotoxic treatment with MG262 reduces the proliferative, fibrotic, and inflammatory response of nasal fibroblasts, whereas high MG262 concentrations induce apoptosis

Effect of Lipopolysaccharide on Glucocorticoid Receptor Function in Control Nasal Mucosa Fibroblasts and in Fibroblasts from Patients with Chronic Rhinosinusitis with Nasal Polyps and Asthma

<div><p>Background</p><p>Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease of the upper airways frequently associated with asthma. Bacterial infection is a feature of CRSwNP that can aggravate the disease and the response to glucocorticoid treatment.</p><p>Objective</p><p>We examined whether the bacterial product lipopolysaccharide (LPS) reduces glucocorticoid receptor (GR) function in control nasal mucosa (NM) fibroblasts and in nasal polyp (NP) fibroblasts from patients with CRSwNP and asthma.</p><p>Methods</p><p>NP (n = 12) and NM fibroblasts (n = 10) were <i>in vitro</i> pre-incubated with LPS (24 hours) prior to the addition of dexamethasone. Cytokine/chemokine secretion was measured by ELISA and Cytometric Bead Array. GRα, GRβ, mitogen-activated protein-kinase phosphatase-1 (MKP-1) and glucocorticoid-induced leucine zipper (GILZ) expression was measured by RT-PCR and immunoblotting, GRα nuclear translocation by immunocytochemistry, and GRβ localization by immunoblotting. The role of MKP-1 and GILZ on dexamethasone-mediated cytokine inhibition was analyzed by small interfering RNA silencing.</p><p>Results</p><p>Pre-incubation of nasal fibroblasts with LPS enhanced the secretion of IL-6, CXCL8, RANTES, and GM-CSF induced by FBS. FBS-induced CXCL8 secretion was higher in NP than in NM fibroblasts. LPS effects on IL-6 and CXCL8 were mediated via activation of p38α/β MAPK and IKK/NF-κB pathways. Additionally, LPS pre-incubation: 1) reduced dexamethasone’s capacity to inhibit FBS-induced IL-6, CXCL8 and RANTES, 2) reduced dexamethasone-induced GRα nuclear translocation (only in NM fibroblasts), 3) did not alter GRα/GRβ expression, 4) decreased GILZ expression, and 5) did not affect dexamethasone’s capacity to induce MKP-1 and GILZ expression. MKP-1 knockdown reduced dexamethasone’s capacity to suppress FBS-induced CXCL8 release.</p><p>Conclusion</p><p>The bacterial product LPS negatively affects GR function in control NM and NP fibroblasts by interfering with the capacity of the activated receptor to inhibit the production of pro-inflammatory mediators. This study contributes to the understanding of how bacterial infection of the upper airways may limit the efficacy of glucocorticoid treatment.</p></div

Role of MKP-1 and GILZ on dexamethasone inhibition of CXCL8 production.

<p>NM fibroblasts were transfected with MKP-1/GILZ/negative control siRNAs, as indicated in Methods. Twenty-four hours later, cells were pre-incubated with/without LPS (10 μg/ml, 24 hours) prior to incubation with 10% FBS-supplemented medium with/without dexamethasone (DEX, 10^–6 M) for one (MKP-1 protein), six (GILZ protein) or twenty-four (CXCL8 release) hours. (<b>A</b>) MKP-1 and GILZ protein analysis (n = 3–4). ***<i>P</i><.001 <i>versus</i> negative control siRNA. (<b>B</b>) FBS-induced CXCL8 production (n = 6). **<i>P</i><.01 <i>versus</i> no LPS. (<b>C</b>) Dexamethasone inhibition of FBS-induced CXCL8 in LPS-pre-incubated cells (n = 6). *<i>P</i><.05, **<i>P</i><.01, and ***<i>P</i><.001 <i>versus</i> LPS alone.</p

Effect of LPS on dexamethasone induction of GRα nuclear translocation.

<p>(A) GR immunofluorescence images of nasal fibroblasts pre-incubated with 10% csFBS-supplemented medium with/without LPS (10 μg/ml, 24 hours) prior to dexamethasone addition (10^–7 M). (B) Quantification of GRα nuclear translocation in NM and NP fibroblasts (n = 12 each). *<i>P</i><.05, **<i>P</i><.01, and ***<i>P</i><.001 <i>versus</i> 0 hours. (C) Ratio of GRα nuclear translocation induced by dexamethasone over time to the respective (medium or LPS) baseline (0 hours) values.</p

Effect of LPS on cytokine production.

<p>(A) ELISA quantification of IL-6 production in cell supernatants of NM and NP fibroblasts (n = 8 each) pre-incubated with 10% csFBS-supplemented medium with/without 10 μg/ml LPS (Pre-LPS, 24 hours) and then incubated with LPS or 10% FBS-supplemented medium (10% FBS) for 24 hours. *<i>P</i><.05. (B) Effect of increasing LPS concentrations on 10% FBS-induced IL-6 production (NM and NP, n = 4–5). (C) Effect of LPS (10 μg/ml) on 10% FBS-induced cytokine/chemokine production (NM and NP, n = 5–8). *<i>P</i><.05, ** <i>P</i><.01, and ***<i>P</i><.001 <i>versus</i> medium-treated cells.</p

Effect of LPS on dexamethasone induction of <i>MKP-1</i> and <i>GILZ</i> gene expression.

<p>RT-PCR quantification of <i>MKP-1</i> (A) and <i>GILZ</i> (B) mRNAs in NM (n = 9–10) and NP (n = 12) fibroblasts pre-incubated with 10% csFBS-supplemented medium with/without LPS (10 μg/ml, 24 hours) prior to dexamethasone (DEX, 10^–7 M) addition for the indicated times. *<i>P</i><.05, **<i>P</i><.01, and ***<i>P</i><.001 <i>versus</i> untreated cells at each time point.</p