Aging and PMN response to P. aeruginosa infection.
OBJECTIVE
Alterations in immune system function associated with aging may contribute to increased morbidity in this population of individuals. The current studies were performed to determine aging-related changes in polymorphonuclear neutrophil (PMN) function after corneal infection with Pseudomonas aeruginosa.


METHODS
Total PMN number, macrophage inflammatory protein (MIP)-2 mRNA and protein expression, and ocular bacterial load were determined in 8-week- and 12-month-old inbred BALB/c mice at various times after infection with P. aeruginosa. In addition, 12-month-old mice were treated systemically with the MIP-2 polyclonal antibody (pAb) to determine the effects of MIP-2 neutralization on ocular disease and PMN recruitment.


RESULTS
Histologically, PMN infiltration into the cornea of 12-month-old mice was delayed initially and was associated with an inability to reduce bacterial load at later postinfection (PI) times. In addition, a significantly greater number of PMNs were found in the cornea of 12-month-old mice at later PI times. The increase in PMN number in 12-month-old mice correlated with a persistence of MIP-2 expression in cornea at these later times. Systemic treatment of 12-month-old mice with neutralizing MIP-2 pAb versus normal rabbit serum (NRS) resulted in reduced corneal PMN number and ocular disease.


CONCLUSIONS
These data provide evidence that persistence of PMN in the cornea of 12-month-old mice contributes to corneal tissue destruction after P. aeruginosa challenge. Further evidence also is provided that the chemoattractant MIP-2 contributes to the altered PMN response in these animals.
Kernacki
K A
KA
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Barrett
R P
RP
McClellan
S A
SA
Hazlett
L D
LD
D000375:Aging / Q000276:immunology*; D000818:Animals; D054426:Chemokine CXCL2; D003320:Corneal Ulcer / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D015818:Eye Infections, Bacterial / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D007958:Leukocyte Count; D051379:Mice; D008807:Mice, Inbred BALB C; D015846:Monokines / Q000235:genetics / Q000276:immunology; D020556:Neutrophil Infiltration / Q000276:immunology; D009504:Neutrophils / Q000502:physiology*; D011552:Pseudomonas Infections / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification*; D012333:RNA, Messenger / Q000378:metabolism
D054426:Chemokine CXCL2; D015846:Monokines; D012333:RNA, Messenger