title: P-glycoprotein regulates Staphylococcus aureus enterotoxin B-stimulated interleukin-5 and thymic stromal lymphopoietin secretion in organotypic mucosal explants.
abstract: BACKGROUND
  T-helper 2 (Th2) inflammation is a hallmark of chronic rhinosinusitis with nasal polyps (CRSwNP) although the pathogenesis is poorly understood. P-glycoprotein (permeability glycoprotein, P-gp) is an efflux pump that is capable of regulating cytokine transport and is expressed within sinonasal mucosa. The purpose of this study was to examine if the oversecretion of interleukin 5 (IL-5) and thymic stromal lymphopoietin (TSLP) in CRSwNP could be explained through P-gp-mediated secretory pathways.
  
  
  METHODS
  Fifteen ethmoid mucosal explants were harvested from patients with CRS (n = 10) and CRSwNP (n = 10) and stimulated with Staphylococcus aureus enterotoxin B (SEB). P-gp was inhibited using zosuquidar trihydrochloride (herein Zosuquidar). P-gp expression was measured using real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). IL-5, IL-8, and TSLP secretion were quantified using ELISA.
  
  
  RESULTS
  P-gp protein was overexpressed in CRSwNP (28.32 ± 25.94 ng/mL per mg explant) as compared to CRS (10.74 ± 8.61; p = 0.01, 2-tailed Mann-Whitney U test). There was no difference in messenger RNA (mRNA) expression. SEB induced a significant increase in IL-5 and TSLP but not IL-8 secretion relative to control in the CRSwNP explants only. Subsequent P-gp inhibition significantly reduced IL-5 and TSLP secretion (p = 0.04 for both, 2-tailed Student t test) to control levels. The concentration of IL-5 and TSLP secretion were strongly and significantly correlated to the concentration of P-gp within the same explant (IL-5: r = 0.791, p = 0.001; TSLP: r = 0.687, p = 0.003; 2-tailed Spearman's rank-order correlation).
  
  
  CONCLUSIONS
  P-gp protein is expressed at higher concentrations in CRSwNP as compared to CRS. This overexpression directly contributes to the relative hypersecretion of IL-5 and TSLP. These findings suggest a novel mechanism for Th2 skewing in CRSwNP.
authors.affiliation: Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA.
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Bleier
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, MA.
authors.forename: Amy
authors.initials: A
authors.lastname: Singleton
authors.affiliation: Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Nocera
authors.affiliation: Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA.
authors.forename: Armine
authors.initials: A
authors.lastname: Kocharyan
authors.affiliation: Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Petkova
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, MA.
authors.forename: Xue
authors.initials: X
authors.lastname: Han
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002908:Chronic Disease; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D003986:Dibenzocycloheptenes / Q000494:pharmacology; D004768:Enterotoxins / Q000378:metabolism*; D006801:Humans; D015848:Interleukin-5 / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D009297:Nasal Mucosa / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology; D009924:Organ Culture Techniques; D011804:Quinolines / Q000494:pharmacology; D012220:Rhinitis / Q000276:immunology* / Q000382:microbiology; D012852:Sinusitis / Q000276:immunology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000276:immunology*; D000094632:Thymic Stromal Lymphopoietin
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D016207:Cytokines; D003986:Dibenzocycloheptenes; D004768:Enterotoxins; D015848:Interleukin-5; D016209:Interleukin-8; D011804:Quinolines; C031818:enterotoxin B, staphylococcal; C095179:zosuquidar trihydrochloride; D000094632:Thymic Stromal Lymphopoietin
keywords: P-glycoprotein; Th2 inflammation; chronic sinusitis with nasal polyps; cytokine secretion; immunomodulator; organotypic explant; sinonasal mucosa; zosuquidar trihydrochloride