title: TLR-mediated induction of proinflammatory cytokine IL-32 in corneal epithelium.
abstract: OBJECTIVE
  IL-32, a newly discovered cytokine, has been associated with a variety of inflammatory diseases. The role of innate immunity in regulation of IL-32 expression has not been elucidated. This study was to explore TLR-mediated induction of IL-32 and the inflammatory effects of IL-32 in corneal epithelium.
  
  
  METHODS
  Human corneal tissues and primary human corneal epithelial cells (HCECs) were treated with a variety of viral or bacterial components, as well as IL-32 without or with different TLR pathway inhibitors. The mRNA expression was determined by reverse transcription and real time PCR, and the protein levels were measured by ELISA and immunostaining.
  
  
  RESULTS
  IL-32 mRNA and protein were largely induced by specific microbial components, including polyinosinic-polycytidylic acid (polyI:C) and flagellin, the ligands to TLR3 and TLR5 respectively, in human corneal epithelium ex vivo and in vitro cultures. The polyI:C-induced IL-32 production was blocked by TLR3 antibody or TRIF inhibitory peptide, while flagellin-stimulated IL-32 was blocked by TLR5 antibody or MyD88 inhibitory peptide. Interestingly, IκB-α inhibitor (BAY11-7082) or nuclear factor kappa B (NF-κB) inhibitor (quinazoline) blocked NF-κB p65 protein nuclear translocation, and also suppressed IL-32 production induced by polyI:C or flagellin. When HCECs were treated with IL-32, we observed its stimulatory affects on inflammatory cytokines, TNF-α, IL-1ß and IL-8, at both mRNA and protein levels.
  
  
  CONCLUSIONS
  These findings demonstrate that IL-32 is induced by microbial ligands through TLR-mediated innate signaling pathways, suggesting an important role of corneal epithelium in inflammatory disease.
authors.affiliation: Department of Ophthalmology, the Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Zhang
authors.forename: Chengye
authors.initials: C
authors.lastname: Che
authors.forename: Jing
authors.initials: J
authors.lastname: Lin
authors.forename: Kuixiang
authors.initials: K
authors.lastname: Liu
authors.forename: De-Quan
authors.initials: DQ
authors.lastname: Li
authors.forename: Guiqiu
authors.initials: G
authors.lastname: Zhao
mesh_terms: D000328:Adult; D019138:Antibodies, Blocking / Q000494:pharmacology; D019573:Epithelium, Corneal / Q000276:immunology* / Q000378:metabolism; D005125:Eye Banks; D006801:Humans; D053583:Interleukin-1beta / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D007378:Interleukins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008024:Ligands; D008875:Middle Aged; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D051198:Toll-Like Receptor 5 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D055815:Young Adult
chemical_list: D019138:Antibodies, Blocking; C508606:CXCL8 protein, human; C496971:IL32 protein, human; D053583:Interleukin-1beta; D016209:Interleukin-8; D007378:Interleukins; D008024:Ligands; D016328:NF-kappa B; D012333:RNA, Messenger; C495344:TLR3 protein, human; C495346:TLR5 protein, human; D051196:Toll-Like Receptor 3; D051198:Toll-Like Receptor 5; D014409:Tumor Necrosis Factor-alpha