title: Impact of Staphylococcus epidermidis lysates on middle ear epithelial proinflammatory and mucogenic response.
abstract: BACKGROUND
  Chronic otitis media with effusion (COME) develops after sustained inflammation and is characterized by secretory middle ear epithelial metaplasia and effusion, most frequently mucoid. Staphylococcus epidermidis, typically considered a commensal organism, is very frequently recovered in chronic middle ear fluid and in middle ear biofilms. Although it has been shown to drive inflammation in sinonasal epithelium, the impact of S. epidermidis on COME is markedly understudied. The goal of this study was to examine the in vitro effects of S. epidermidis lysates on murine and human middle ear epithelial cells.
  
  
  METHODS
  Staphylococcus epidermidis lysates were generated and used to stimulate submerged and differentiated human and murine epithelial cells (MEECs) for 24 to 48 hours. Quantitative real time-polymerase chain reaction, Western blot, enzyme-linked immunosorbent assay, and immunocytochemistry techniques were performed to interrogate the mucin gene MUC5AC and MUC5B expression and protein production, chemokine response, as well as NF-κB activation. Luciferase reporter assays were performed to further evaluate nuclear factor κB (NF-κB) activation and query specific promoter responses after S. epidermidis exposure.
  
  
  RESULTS
  Staphylococcus epidermidis induced a time- and dose-dependent MUC5AC and MUC5B overexpression along with a parallel overexpression of Cxcl2 in mouse MEEC and IL-8 in human MEEC. Further investigations in mMEEC showed a 1.3 to 1.5 induction of the MUC5AC and MUC5B promoters. As potential mechanisms for these responses, induction of an oxidative stress marker, along with early nuclear translocation and activation of NF-κB, was found. Finally, chronic exposure induced marked epithelial thickening of cells differentiated at the air liquid interface.
  
  
  CONCLUSIONS
  Staphylococcus epidermidis lysates activate a proinflammatory response in MEEC, including mucin gene expression and protein production. Although typically considered a nonpathogenic commensal organism in the ear, these results suggest that they may play a role in the perpetuation of an inflammatory and mucogenic response in COME.
authors.affiliation: From the *Sheikh Zayed Center for Pediatric Surgical Innovation, Children's National Health System; and †Division of Pediatric Otolaryngology, Children's National Health System, Washington, DC.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Val
authors.forename: Humaira
authors.initials: H
authors.lastname: Mubeen
authors.forename: Amarel
authors.initials: A
authors.lastname: Tomney
authors.forename: Saisai
authors.initials: S
authors.lastname: Chen
authors.forename: Diego
authors.initials: D
authors.lastname: Preciado
mesh_terms: D000818:Animals; D002460:Cell Line; D004432:Ear, Middle / Q000382:microbiology* / Q000473:pathology*; D004847:Epithelial Cells / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology*; D005786:Gene Expression Regulation; D006801:Humans; D007249:Inflammation / Q000150:complications / Q000235:genetics / Q000473:pathology*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009077:Mucins / Q000235:genetics* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D018384:Oxidative Stress; D040901:Proteomics; D013203:Staphylococcal Infections / Q000150:complications / Q000235:genetics / Q000382:microbiology / Q000473:pathology; D013212:Staphylococcus epidermidis / Q000502:physiology*
chemical_list: D016209:Interleukin-8; D009077:Mucins; D016328:NF-kappa B