title: Klf4 regulates the expression of Slurp1, which functions as an immunomodulatory peptide in the mouse cornea.
abstract: OBJECTIVE
  The secreted Ly6/uPAR-related protein-1 (Slurp1), associated with the hyperkeratotic disorder mal de Meleda, is abundantly expressed in corneas. Here, we examine its corneal expression and functions.
  
  
  METHODS
  Gene expression was quantified by quantitative PCR (qPCR), immunoblots, and immunofluorescent staining. Effect of Kruppel-like factor 4 (Klf4) on Slurp1 promoter was evaluated by chromatin immunoprecipitation (ChIP) and transient transfections. Adenoviral vectors were used to express Slurp1 in corneas. Leukocytic infiltration in bacterial lipopolysaccharide (LPS)-, herpes simplex virus type 1 (HSV-1)-, or adenovirus (serotype 5)-treated mouse corneas was characterized by flow cytometry.
  
  
  RESULTS
  Corneal expression of Slurp1 increased sharply upon mouse eyelid opening, concurrent with the elevated expression of Klf4. Slurp1 was significantly decreased in Klf4 conditional null (Klf4CN) corneas that displayed elevated expression of cytokines and cytokine receptors, as well as neutrophil influx consistent with a proinflammatory environment. In additional models of corneal inflammation, Slurp1 expression was abrogated within 24 hours of LPS injection or HSV-1 or adenoviral infection, accompanied by a predominantly neutrophilic infiltrate. Neutrophilic infiltration was enhanced in HSV-1-infected Klf4CN corneas lacking Slurp1. SLURP1 promoter activity was stimulated by KLF4, suppressed by IL-4, IL-13, and TNFα, and unperturbed by IFN-γ. Slurp1 downregulation and neutrophil influx were comparable in HSV-1-infected wild-type (WT) and Ifng-/- mouse corneas. Mouse corneas infected with Slurp1-expressing adenoviral vectors displayed reduced signs of inflammation and restricted neutrophilic infiltration compared with those infected with control vectors.
  
  
  CONCLUSIONS
  Klf4 regulates the expression of Slurp1, a key immunomodulatory peptide that is abundantly expressed in healthy corneas and is downregulated in proinflammatory conditions.
authors.affiliation: Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. Swamynathansk@upmc.edu
authors.forename: Sudha
authors.initials: S
authors.lastname: Swamynathan
authors.forename: Kristine-Ann
authors.initials: KA
authors.lastname: Buela
authors.forename: Paul
authors.initials: P
authors.lastname: Kinchington
authors.forename: Kira L
authors.initials: KL
authors.lastname: Lathrop
authors.forename: Hidemi
authors.initials: H
authors.lastname: Misawa
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hendricks
authors.forename: Shivalingappa K
authors.initials: SK
authors.lastname: Swamynathan
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000950:Antigens, Ly / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D047369:Chromatin Immunoprecipitation; D003315:Cornea / Q000378:metabolism*; D016207:Cytokines / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation / Q000502:physiology*; D005822:Genetic Vectors; D006131:Growth Inhibitors / Q000502:physiology*; D018259:Herpesvirus 1, Human / Q000502:physiology; D007154:Immune System Diseases; D015151:Immunoblotting; D007155:Immunologic Factors / Q000235:genetics / Q000378:metabolism; D016849:Keratitis, Herpetic / Q000235:genetics / Q000378:metabolism; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000502:physiology*; D007960:Leukocyte Disorders; D008070:Lipopolysaccharides / Q000633:toxicity; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D014162:Transfection; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics* / Q000378:metabolism
chemical_list: D000950:Antigens, Ly; D016207:Cytokines; D006131:Growth Inhibitors; D007155:Immunologic Factors; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D008070:Lipopolysaccharides; C545249:SLURP-1 protein, mouse; D014568:Urokinase-Type Plasminogen Activator