Keratocan and lumican regulate neutrophil infiltration and corneal clarity in lipopolysaccharide-induced keratitis by direct interaction with CXCL1.
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.
Carlson
Eric C
EC
Department of Ophthalmology, Case Western Reserve University, Cleveland, Ohio 44106, USA. Eric.Carlson@case.edu
Lin
Michelle
M
Liu
Chia-Yang
CY
Kao
Winston W-Y
WW
Perez
Victor L
VL
Pearlman
Eric
E
D000256:Adenoviridae; D000818:Animals; D054360:Chemokine CXCL1 / Q000378:metabolism*; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism; D007249:Inflammation / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism; D007632:Keratan Sulfate / Q000235:genetics / Q000378:metabolism*; D007634:Keratitis / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity*; D000071234:Lumican; D051379:Mice; D018345:Mice, Knockout; D020556:Neutrophil Infiltration / Q000187:drug effects; D009504:Neutrophils / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014161:Transduction, Genetic
D054360:Chemokine CXCL1; D011508:Chondroitin Sulfate Proteoglycans; C475895:Cxcl1 protein, mouse; C099280:Kera protein, mouse; D008070:Lipopolysaccharides; C000604307:Lum protein, mouse; D000071234:Lumican; D011509:Proteoglycans; D007632:Keratan Sulfate