Lack of suppressed renal thrombomodulin expression in a septic rat model with glomerular thrombotic microangiopathy.
BACKGROUND
The thrombomodulin-dependent protein C anticoagulant pathway plays a major physiologic role in the down-regulation of the coagulation process. In cell culture, inflammatory cytokines or endotoxin can down-regulate endothelial thrombomodulin (TM) suggesting that suppressed TM expression may contribute to thrombotic complications noted in Gram-negative sepsis.


METHODS
In the present study, we have examined TM expression in the kidneys of septic rats utilizing indirect immunofluorescence and have quantified TM antigen and TM activity in extracts of the same kidneys by enzyme-linked immunosorbent assays and protein C activation assays, respectively. Conscious Sprague-Dawley rats were injected intravenously with LD95 doses of live E. coli (N = 30), or endotoxin (N = 30). Control animals (N = 30) were injected with equivalent volumes of saline. The rats were killed 30, 90, 180, 360, and 720 minutes after the initiation of sepsis.


RESULTS
Glomerular capillary thrombosis developed by 180 minutes in approximately half of the animals after the initiation of sepsis. We failed to demonstrate suppressed TM expression in the kidneys of septic animals using immunofluorescence. Neither enzyme-linked immunosorbent assays, nor protein C activation assays showed decreased levels in TM antigen expression or activity at different time points during the sepsis.


CONCLUSIONS
These results indicate that suppressed TM expression does not contribute to the development of the glomerular capillary thrombosis in this septic rat model.
Laszik
Z
Z
Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City.
Carson
C W
CW
Nadasdy
T
T
Johnson
L D
LD
Lerner
M R
MR
Brackett
D J
DJ
Esmon
C T
CT
Silva
F G
FG
D000818:Animals; D001160:Arterioles / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000473:pathology; D004731:Endotoxins; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli; D004927:Escherichia coli Infections / Q000378:metabolism* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D007672:Kidney Cortex / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D007678:Kidney Glomerulus / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D008297:Male; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012772:Shock, Septic / Q000378:metabolism* / Q000473:pathology; D018180:Thrombomodulin / Q000032:analysis / Q000096:biosynthesis*; D013927:Thrombosis / Q000378:metabolism / Q000473:pathology
D004731:Endotoxins; D018180:Thrombomodulin; D011493:Protein Kinase C