Serine proteinase inhibitor-9, an endogenous blocker of granzyme B/perforin lytic pathway, is hyperexpressed during acute rejection of renal allografts.
BACKGROUND
Serine proteinase inhibitor (PI)-9 with a reactive center P1 (Glu)-P1' is a natural antagonist of granzyme B and is expressed in high levels in cytotoxic T lymphocytes (CTL). In view of the role of CTL in acute rejection, we explored the hypothesis that PI-9 would be hyperexpressed during acute rejection. Because PI-9 can protect CTL from its own fatal arsenal and potentially enhance the vitality of CTL, we examined whether PI-9 levels correlate with the severity of rejection as well as predict subsequent graft function.


METHODS
We obtained 95 urine specimens from 87 renal allograft recipients. RNA was isolated from the urinary cells and mRNA encoding PI-9, granzyme B, or perforin and a constitutively expressed 18S rRNA was measured with the use of real-time quantitative polymerase chain reaction assay, and the level of expression was correlated with allograft status.


RESULTS
The levels of PI-9 (P=0.001), granzyme B (P<0.0001), and perforin mRNAs (P<0.0001), but not the levels of 18S rRNA (P=0.54), were higher in the urinary cells from the 29 patients with a biopsy-confirmed acute rejection than in the 58 recipients without acute rejection. PI-9 levels were significantly higher in patients with type II or higher acute rejection changes compared with those with less than type II changes (P=0.01). Furthermore, PI-9 levels predicted subsequent graft function (r=0.43, P=0.01).


CONCLUSIONS
PI-9 mRNA levels in urinary cells are diagnostic of acute rejection, predict renal allograft histology grade, and predict functional outcome following an acute rejection episode.
Muthukumar
Thangamani
T
Division of Nephrology, Department of Medicine, Weill Medical College of Cornell University, New York-Presbyterian Hospital, NY, USA.
Ding
Ruchuang
R
Dadhania
Darshana
D
Medeiros
Mara
M
Li
Baogui
B
Sharma
Vijay K
VK
Hartono
Choli
C
Serur
David
D
Seshan
Surya V
SV
Volk
Hans-Dieter
HD
Reinke
Petra
P
Kapur
Sandip
S
Suthanthiran
Manikkam
M
D000208:Acute Disease; D000328:Adult; D000368:Aged; D005260:Female; D006084:Graft Rejection / Q000378:metabolism*; D053804:Granzymes; D006801:Humans; D016030:Kidney Transplantation / Q000276:immunology*; D008297:Male; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D008875:Middle Aged; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger / Q000032:analysis; D012697:Serine Endopeptidases / Q000235:genetics; D015843:Serpins / Q000096:biosynthesis* / Q000235:genetics; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014184:Transplantation, Homologous
D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger; C102316:SERPINB9 protein, human; D015843:Serpins; D054353:Perforin; C509213:GZMB protein, human; D053804:Granzymes; D012697:Serine Endopeptidases