Calcium-binding proteins MRP 8 and 14 in a Staphylococcus aureus infection model: role of therapy, inflammation, and infection persistence.
Concentrations of the calcium-binding proteins of the S100 family, myeloid-related proteins 8 and MRP 14 (MRP8/14), are elevated in chronic infections, yet the role of these proteins is not clearly defined. Using commercial and developed enzyme immunoassays, we assayed for MRP8/14 in sterile-filtered abscess fluid from tissue-cage-implanted rats and rabbits. Staphylococcus aureus abscesses were created 6 weeks after the intraperitoneal implantation of tissue cages. Leukocytes, bacteria, and non-protein-bound calcium and zinc were measured in the infection exudate at day 3 or 5 of infection and after 8 days of treatment with antimicrobials beta-lactams (18 rabbits, 35 rats) and fluoroquinolone-rifampin (6 rabbits). Half of the infected rats were depleted of neutrophils; these rats exhibited significantly lower MRP 8/14 concentrations on all days sampled, regardless of the level of infection. The level of abscess MRP 8/14 is high early in the course of infection but decreases with effective antimicrobial treatment by as much as 100-fold. Thirty-day-old abscesses with log 6 bacterial counts and low neutrophil counts showed low concentrations of MRP 8/14 in these models. In abscess fluid, interleukin-6, as a representative marker of inflammation, correlated with MRP8/14, whereas ionized calcium and zinc did not. Our data suggest that infection and inflammation are not equal stimuli for MRP 8/14. The neutrophil appears to be the main source of MRP8/14 in this model.
Herndon
Betty L
BL
Section of Infectious Diseases, School of Medicine, University of Missouri, Kansas City, MO 64108, USA. herndonb@umkc.edu
Abbasi
Suhail
S
Bennett
David
D
Bamberger
David
D
D000038:Abscess / Q000382:microbiology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000627:therapeutic use; D002118:Calcium / Q000032:analysis; D040501:Calgranulin A / Q000032:analysis*; D040502:Calgranulin B / Q000032:analysis*; D002413:Cations, Divalent / Q000032:analysis; D002712:Chlorides / Q000032:analysis; D004195:Disease Models, Animal; D005122:Exudates and Transudates / Q000737:chemistry; D024841:Fluoroquinolones; D007124:Immunoenzyme Techniques; D007249:Inflammation / Q000378:metabolism* / Q000473:pathology; D015850:Interleukin-6 / Q000032:analysis; D007769:Lactams; D007958:Leukocyte Count; D009504:Neutrophils / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D012293:Rifampin / Q000627:therapeutic use; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D015032:Zinc / Q000032:analysis
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D040501:Calgranulin A; D040502:Calgranulin B; D002413:Cations, Divalent; D002712:Chlorides; D024841:Fluoroquinolones; D015850:Interleukin-6; D007769:Lactams; D015032:Zinc; D002118:Calcium; D012293:Rifampin