Kidney Injury Molecule-1 Staining Identifies Acute Tubular Injury in Pediatric Kidneys Regardless of Autolysis.
Mary E Pietrangelo, Jacqueline K Macknis, Sharon K Hicks, Ping L Zhang. William Beaumont Hospital, Royal Oak, MI
Background: Kidney injury molecule-1 (KIM-1) is a specific marker for identifiying injury in proximal tubules. Our recent study demonstrates that KIM-1 is expressed in injured proximal tubules in adult kidneys regardless of autolysis and is significantly associated with premortem serum creatinine (sCr). The current study was to identify proximal tubular injury in kidneys from pediatric autopsies using KIM-1. The second goal was to determine the correlation between clinical indices and KIM-1 expression, since sCr was not available in this age group.
Design: Pediatric autopsy cases (n=52) were identified in our archives from 1/08 to 6/10. All pediatric kidney sections were stained by a Dako Autostainer using a KIM-1 antibody (AKG7, JV Bonventre's lab, Brigham and Women's Hospital, Boston). The staining intensity of KIM-1 in proximal tubules was scored from 0 (no staining) to 3+ (strong granular staining across the entire luminal surface). The autolysis was graded from 0 (no autolysis) to 3+ (entire loss of chromatin staining). The presence of aspirated amniotic fluid contents in stillborn or need for intubation in liveborn were obtained as indices of hypoxia and correlated with KIM-1 expression.
Results: In our pediatric cases, the ages ranged from 15 to 40 gestational weeks (n=52, 29/52 stillborn and 23/52 liveborn). KIM-1 was expressed in 40/52 (77%) of cases: 0 expression in 12 cases; 1+ in 25 cases; 2+ in 14 cases and 3+ in 1 case. KIM-1 staining was upregulated as early as 16 weeks gestation. Twenty-three (23) cases did not show autolysis, whereas autolysis was present in twenty-nine (29) kidneys ranging from 1+ in 8 cases, to 2+ in 7 cases, and to 3+ in 14 cases. There was no significant correlation between KIM-1 scores and autolysis scores (r value = 0.201 and p = 0.1521, linear regression analysis). Cinical correlation (CC) was available for 30/52 (58%) of cases. Among the 30 cases with CC available, there was 73% correlation between KIM-1 expression and either presence of aspirated amniotic fluid contents or need for intubation.
|Table 1||Stillborn (%)||Liveborn (%)||Total (%)|
|KIM-1 +/case #||21/29 (72%)||19/23 (83%)||40/52 (77%)|
|CC available/case #||11/29 (38%)||19/23 (83%)||30/52 (58%)|
|CC +/KIM-1 +||6/11 (55%)||16/19 (84%)||22/30 (73%)|