Corneal expression of the inflammatory mediator CAP37.
OBJECTIVE
CAP37 is a polymorphonuclear neutrophil (PMN)-derived inflammatory protein with potent antibiotic and chemotactic activity. To further investigate the biological significance of CAP37 in infection and inflammation, a well-characterized in vivo rabbit model of bacterial keratitis was selected to study its contribution to host defenses.


METHODS
One hundred colony-forming units of log phase Staphylococcus aureus was injected intrastromally. Eyes were enucleated at 5 to 25 hours after infection and CAP37 detected by immunohistochemistry. To identify the mechanism of CAP37 upregulation in corneal epithelium, in vitro studies using immortalized human corneal epithelial cells (HCECs) were undertaken to determine whether proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), induce CAP37. Because adhesion of leukocytes is important in leukocyte-epithelium interactions, the effect of CAP37 on expression of intercellular adhesion molecule (ICAM)-1 on HCECs was determined by flow cytometry.


RESULTS
Strong staining for CAP37 was demonstrated in the corneal epithelium, stromal fibroblasts, ciliary epithelium, related limbus, ciliary vascular endothelium, and bulbar conjunctiva in rabbits injected with S. aureus. The most dramatic expression of CAP37 aside from that in the PMNs occurred in the corneal epithelium. The in vitro studies suggest that CAP37 induction is regulated by TNF-alpha and IL-1beta. In addition, ICAM-1 expression on HCECs was increased in response to CAP37. Molecular cloning of corneal epithelial CAP37 indicated strong sequence identity with an extensive region of PMN-CAP37.


CONCLUSIONS
The findings in this study describe the extraneutrophilic expression of CAP37 in response to infection and suggest a role for CAP37 in host defense against infection in the eye.
Ruan
Xin
X
Department of Pathology, University of Oklahoma Health Sciences Center, Dean A. McGee Eye Institute, Oklahoma City, OK 73190, USA.
Chodosh
James
J
Callegan
Michelle C
MC
Booth
Mary C
MC
Lee
Taunia D
TD
Kumar
Padmasini
P
Gilmore
Michael S
MS
Pereira
H Anne
HA
D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D003001:Cloning, Molecular; D019573:Epithelium, Corneal / Q000187:drug effects / Q000378:metabolism*; D015818:Eye Infections, Bacterial / Q000378:metabolism* / Q000382:microbiology; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D007124:Immunoenzyme Techniques; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D007634:Keratitis / Q000378:metabolism* / Q000382:microbiology; D008969:Molecular Sequence Data; D018945:Monocyte Chemoattractant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D011817:Rabbits; D011994:Recombinant Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000378:metabolism* / Q000382:microbiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation
C062991:AZU1 protein, human; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D002352:Carrier Proteins; D005136:Eye Proteins; D007375:Interleukin-1; D018945:Monocyte Chemoattractant Proteins; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1