High-dose exogenous iron following cecal ligation and puncture increases mortality rate in mice and is associated with an increase in gut epithelial and splenic apoptosis.
OBJECTIVE
Despite having dysregulated iron metabolism, critically ill patients may receive exogenous iron for the treatment of anemia. Iron is associated with increased tissue apoptosis and may facilitate bacterial growth. We hypothesized that exogenous iron administration given after the onset of sepsis would lead to increased mortality rate. To discriminate between elevated cell death and bacterial overgrowth as potential mediators of mortality, we examined gut epithelial and lymphocyte apoptosis and systemic bacterial counts in animals given iron supplementation after the onset of sepsis.


METHODS
Prospective, randomized, controlled study.


METHODS
Animal laboratory in a university medical center.


METHODS
Male C57BL/6 mice, 6-10 wks old.


METHODS
C57BL/6 mice were subjected to cecal ligation and puncture (CLP), a well-accepted model of intra-abdominal sepsis, followed by daily subcutaneous injections of either 1 mL of iron dextran (5 mg/mL) or 0.9% NaCl for a total of five doses. Animals (n = 78) were followed for survival for 8 days. Separate cohorts (n = 76) were killed 24 or 48 hrs after cecal ligation and puncture or sham laparotomy and were assayed for gut epithelial and splenic apoptosis as well as for quantitative blood cultures.


RESULTS
Eight-day survival was 7% in animals that received iron and 26% in mice that received 0.9% NaCl (p < .005). Iron supplementation after cecal ligation and puncture increased apoptosis by both active caspase 3 and hematoxylin and eosin staining in both the intestinal epithelium and spleen at 24 hrs (p < .05). Iron supplementation after sham laparotomy did not cause mortality or elevated apoptosis. Quantitative blood cultures revealed no detectable differences between septic animals that received iron and those that received 0.9% NaCl.


CONCLUSIONS
High-dose iron supplementation with iron dextran after the onset of sepsis significantly increases mortality rate in this animal model. Iron-induced mortality may be mediated by an increase in gut epithelial and splenic apoptosis, whereas severity of bacteremia does not appear to play a causative role.
Javadi
Pardis
P
Department of Surgery, Washington University School of Medicine, St. Louis, MO, USA.
Buchman
Timothy G
TG
Stromberg
Paul E
PE
Husain
Kareem D
KD
Dunne
W Michael
WM
Woolsey
Cheryl A
CA
Turnbull
Isaiah R
IR
Hotchkiss
Richard S
RS
Karl
Irene E
IE
Coopersmith
Craig M
CM
D018798:Anemia, Iron-Deficiency / Q000188:drug therapy* / Q000382:microbiology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000032:analysis; D015984:Causality; D002432:Cecum / Q000293:injuries; D016638:Critical Illness / Q000401:mortality / Q000628:therapy; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D007279:Injections, Subcutaneous; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D007501:Iron / Q000378:metabolism; D007505:Iron-Dextran Complex / Q000008:administration & dosage / Q000009:adverse effects*; D008026:Ligation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011677:Punctures; D011897:Random Allocation; D018805:Sepsis / Q000150:complications / Q000378:metabolism / Q000401:mortality* / Q000473:pathology; D012965:Sodium Chloride / Q000008:administration & dosage; D013154:Spleen / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D016019:Survival Analysis; D013997:Time Factors
D012965:Sodium Chloride; D007505:Iron-Dextran Complex; D007501:Iron; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases