Keratocan and lumican regulate neutrophil infiltration and corneal clarity in lipopolysaccharide-induced keratitis by direct interaction with CXCL1

J Biol Chem. 2007 Dec 7;282(49):35502-9. doi: 10.1074/jbc.M705823200. Epub 2007 Oct 2.

Abstract

Keratocan and lumican are keratan-sulfate proteoglycans (KSPG), which have a critical role in maintaining corneal clarity. To determine whether these KSPGs have a role in corneal inflammation, we examined Kera(-/-) and Lum(-/-) mice in a model of lipopolysaccharide (LPS)-induced keratitis in which wild-type mice develop increased corneal thickness and haze due to neutrophil infiltration to the corneal stroma. Corneal thickness increases caused by LPS mice were significantly lower in Kera(-/-) and Lum(-/-) than wild-type mice. Further, LPS-injected Lum(-/-) mice had elevated corneal haze levels compared with that of Kera(-/-) and wild-type. At 24 h post-injection, total enhanced green fluorescent protein-positive bone marrow-derived inflammatory cells in chimeric mice was significantly lower in Kera(-/-) mice and Lum(-/-) mice compared with wild-type mice. Neutrophil infiltration was inhibited in Kera(-/-) and Lum(-/-) mice at 6 and 24 h post-stimulation, with Lum(-/-) corneas having the most profound defect in neutrophil migration. Reconstitution of keratocan and lumican expression in corneas of Kera(-/-) and Lum(-/-) mice using adeno-keratocan and adeno-lumican viral vectors, respectively, resulted in normal neutrophil infiltration in response to LPS. Immunoprecipitation/Western blot analysis showed that lumican and keratocan core proteins bind the CXC chemokine KC during a corneal inflammatory response, indicating that corneal KSPGs mediate neutrophil recruitment to the cornea by regulating chemokine gradient formation. Together, these data support a significant role for lumican and keratocan in a corneal inflammatory response with respect to edema, corneal clarity, and cellular infiltration.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae
  • Animals
  • Chemokine CXCL1 / metabolism*
  • Chondroitin Sulfate Proteoglycans / genetics
  • Chondroitin Sulfate Proteoglycans / metabolism*
  • Cornea / metabolism
  • Inflammation / chemically induced
  • Inflammation / genetics
  • Inflammation / metabolism
  • Keratan Sulfate / genetics
  • Keratan Sulfate / metabolism*
  • Keratitis / chemically induced
  • Keratitis / genetics
  • Keratitis / metabolism*
  • Lipopolysaccharides / toxicity*
  • Lumican
  • Mice
  • Mice, Knockout
  • Neutrophil Infiltration* / drug effects
  • Neutrophils / metabolism*
  • Protein Binding / genetics
  • Proteoglycans / genetics
  • Proteoglycans / metabolism*
  • Time Factors
  • Transduction, Genetic

Substances

  • Chemokine CXCL1
  • Chondroitin Sulfate Proteoglycans
  • Cxcl1 protein, mouse
  • Kera protein, mouse
  • Lipopolysaccharides
  • Lum protein, mouse
  • Lumican
  • Proteoglycans
  • Keratan Sulfate