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.
BACKGROUND
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.


OBJECTIVE
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.


METHODS
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. 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.


RESULTS
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.


CONCLUSIONS
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.
Clinical and Experimental Respiratory Immunoallergy, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERes), Barcelona, Spain.
Laura
L
Fernández-Bertolín
Clinical and Experimental Respiratory Immunoallergy, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERes), Barcelona, Spain; Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, Barcelona, Spain.
Joaquim
J
Mullol
Clinical and Experimental Respiratory Immunoallergy, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERes), Barcelona, Spain.
Mireya
M
Fuentes-Prado
Clinical and Experimental Respiratory Immunoallergy, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERes), Barcelona, Spain.
Jordi
J
Roca-Ferrer
Clinical and Experimental Respiratory Immunoallergy, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERes), Barcelona, Spain; Rhinology Unit and Smell Clinic, ENT Department, Hospital Clínic, Barcelona, Spain.
Isam
I
Alobid
Clinical and Experimental Respiratory Immunoallergy, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERes), Barcelona, Spain; Allergy Unit, Pneumology and Allergy Department, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
César
C
Picado
Clinical and Experimental Respiratory Immunoallergy, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigaciones Biomédicas en Red de Enfermedades Respiratorias (CIBERes), Barcelona, Spain.
Laura
L
Pujols
D001249:Asthma / Q000150:complications*; D002908:Chronic Disease; D016207:Cytokines / Q000096:biosynthesis; D003907:Dexamethasone / Q000494:pharmacology; D054638:Dual Specificity Phosphatase 1 / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology; D009297:Nasal Mucosa / Q000276:immunology / Q000378:metabolism*; D009298:Nasal Polyps / Q000150:complications*; D021381:Protein Transport; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism*; D012220:Rhinitis / Q000150:complications / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D012852:Sinusitis / Q000150:complications / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D016207:Cytokines; D008070:Lipopolysaccharides; D011965:Receptors, Glucocorticoid; C404226:TSC22D3 protein, human; D014157:Transcription Factors; D003907:Dexamethasone; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1