Host defense against bacterial keratitis.
OBJECTIVE
To define factors that protect the eye from Staphylococcus aureus keratitis and limit tissue damage once keratitis occurs.


METHODS
Rabbit tears were analyzed for bactericidal and phospholipase A(2) (PLA(2)) activities on S. aureus. Inhibition by spermidine of PLA(2) anti-staphylococcal activity in tears was tested in vitro and in vivo. Rabbits immunized with heat-inactivated alpha-toxin were challenged with intrastromal injection of S. aureus.


RESULTS
Arachidonic acid was cleaved from S. aureus by purified PLA( 2) or rabbit tears. Spermidine inhibited these reactions in vitro and facilitated keratitis in vivo. PLA(2) activity decreased with advanced age and shortly following sleep, but increased with keratitis. Antibody to alpha-toxin significantly reduced corneal damage and epithelial cell sloughing during keratitis.


CONCLUSIONS
PLA(2) is a major host-defense component of rabbit tears. Alpha-toxin is a major mediator of corneal damage, and antibody to alpha-toxin reduces pathologic changes during keratitis.
O'Callaghan
Richard J
RJ
Department of Microbiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA. rocall@lsuhsc.edu
Girgis
Dalia O
DO
Dajcs
Joseph J
JJ
Sloop
Gregory D
GD
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D003319:Corneal Stroma / Q000382:microbiology; D003320:Corneal Ulcer / Q000276:immunology* / Q000382:microbiology* / Q000517:prevention & control; D015818:Eye Infections, Bacterial / Q000276:immunology* / Q000517:prevention & control; D007113:Immunity, Innate / Q000502:physiology; D007114:Immunization; D010741:Phospholipases A / Q000378:metabolism; D011817:Rabbits; D013095:Spermidine / Q000494:pharmacology; D013203:Staphylococcal Infections / Q000276:immunology* / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000502:physiology*; D013666:Tears / Q000201:enzymology; D010738:Type C Phospholipases / Q000008:administration & dosage
D016718:Arachidonic Acid; D010741:Phospholipases A; D010738:Type C Phospholipases; D013095:Spermidine