Urine neutrophil gelatinase-associated lipocalin is a marker of graft recovery after kidney transplantation.

Delayed graft function (DGF), especially long-lasting DGF, complicates kidney transplant outcome. Neutrophil gelatinase-associated lipocalin (NGAL) is an acute kidney injury marker; therefore, we tested whether urine NGAL could predict DGF, prolonged DGF (lasting over 14 days), or the quality of kidney function in transplant recipients without DGF (non-DGF). We collected urine samples from 176 recipients transplanted with deceased donor kidneys before and various days after transplantation. A total of 70 transplantations had DGF, of which 26 were prolonged. Patients who developed DGF had a significantly slower decrease in urinary NGAL compared with those without DGF, such that day 1 NGAL predicted DGF (area under the curve (AUC) 0.75) and predicted DGF in 15 of 112 cases with day 1 urine output over 1 l (AUC 0.70) and in 19 of 86 cases with a day 1 decrease in creatinine over 50 µmol/l (AUC 0.74). The urinary NGAL level on day 1 predicted prolonged DGF (AUC 0.75), which had significantly worse 1-year graft survival (73%), compared with shorter DGF (100%). In non-DGF, high day 3 NGAL (greater than the mean) was associated with significantly worse kidney function at 3 weeks compared with low NGAL, but not at 3 months and 1 year. NGAL did not correlate with long-term function in DGF. Hence, day 1 urinary NGAL predicted DGF even when it was not clinically expected early on, and importantly, it predicted prolonged DGF that led to worse graft survival.

Deceased donor neutrophil gelatinase-associated lipocalin and delayed graft function after kidney transplantation: a prospective study.

INTRODUCTION: Expanding the criteria for deceased organ donors increases the risk of delayed graft function (DGF) and complicates kidney transplant outcome. We studied whether donor neutrophil gelatinase-associated lipocalin (NGAL), a novel biomarker for acute kidney injury, could predict DGF after transplantation. METHODS: We included 99 consecutive, deceased donors and their 176 kidney recipients. For NGAL detection, donor serum and urine samples were collected before the donor operation. The samples were analyzed using a commercial enzyme-linked immunosorbent assay kit (serum) and the ARCHITECT method (urine). RESULTS: Mean donor serum NGAL (S-NGAL) concentration was 218 ng/mL (range 27 to 658, standard deviation (SD) 145.1) and mean donor urine NGAL (U-NGAL) concentration was 18 ng/mL (range 0 to 177, SD 27.1). Donor S-NGAL and U-NGAL concentrations correlated directly with donor plasma creatinine levels and indirectly with estimated glomerular filtration rate (eGFR) calculated using the modification of diet in renal disease equation for glomerular filtration rate. In transplantations with high (greater than the mean) donor U-NGAL concentrations, prolonged DGF lasting longer than 14 days occurred more often than in transplantations with low (less than the mean) U-NGAL concentration (23% vs. 11%, P = 0.028), and 1-year graft survival was worse (90.3% vs. 97.4%, P = 0.048). High U-NGAL concentration was also associated with significantly more histological changes in the donor kidney biopsies than the low U-NGAL concentration. In a multivariate analysis, U-NGAL, expanded criteria donor status and eGFR emerged as independent risk factors for prolonged DGF. U-NGAL concentration failed to predict DGF on the basis of receiver operating characteristic curve analysis. CONCLUSIONS: This first report on S-NGAL and U-NGAL levels in deceased donors shows that donor U-NGAL, but not donor S-NGAL, measurements give added value when evaluating the suitability of a potential deceased kidney donor.

Matrix metalloproteinase induction in post-transplant obliterative bronchiolitis.

BACKGROUND: Epithelial cell injury, inflammation, fibrosis, and airway obliteration are associated in post-transplant obliterative bronchiolitis. Fibrosis is a consequence of fibroblastic activity and of collagen deposition after disturbances in the balance of protein formation and degradation. Proteolytic enzymes such as the matrix metalloproteinases mediate degradation. To assess matrix metalloproteinases during obliterative bronchiolitis development, we studied porcine, heterotopic bronchial allografts. METHODS: A total of 119 allografts or autografts were harvested serially at 3 to 60 days after transplantation and processed for histology and in situ hybridization for matrix metalloproteinases 2 and 9. Immunocytochemistry for vimentin and alpha-smooth-muscle-cell actin was performed with specific antibodies. RESULTS: Implants had initial ischemic injury to airway epithelium and to the bronchial wall. Recovery was rapid in autografts and in immunosuppressed allografts. In matrix metalloproteinase-2 mRNA activity in fibroblasts, correlation with endothelial expression and expression in macrophages occurred during intense fibroproliferation. We observed intense matrix metalloproteinase-9 positivity during onset of inflammation and fibroproliferation in endothelial cells (p < 0.01), fibroblasts (p < 0.05), macrophages (p < 0.05), and lymphocytes (p < 0.05). Matrix metalloproteinase-9 mRNA activity in fibroblasts correlated with that in endothelial and inflammatory cells and also proved predictive of early obliteration. CONCLUSIONS: Matrix metalloproteinase-2, and especially matrix metalloproteinase-9, gene activity was associated with onset of inflammation and fibroblastic proliferation in allografts, predicting early obliteration. Although this may be the case in the model described, its role in human-allograft post-transplant obliterative bronchiolitis requires further supportive data.

Fibrosis and matrix metalloproteinases in rat renal allografts.

The temporal activity and gene expression of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinase (TIMP) were investigated in a rat model of chronic allograft nephropathy. Gelatinolytic activity of MMP-2 and -9 were demonstrated by zymography, and MMP-2,-9 and TIMP-3 mRNA by in situ hybridization. The generation of fibrosis was determined as total collagen content/DNA. Significantly more latent and active MMP-2, as well as latent MMP-9, were seen in allografts than in autografts. Intense MMP-2 mRNA expression was demonstrated in the allografts during the first 20 days after transplantation, located mainly in the interstitium of the kidney. In addition, some tubular cells expressed MMP-2 mRNA. After day 20, MMP-2 gene expression was faint. MMP-9 mRNA expression in allografts was located mainly in the glomerulus. TIMP-3 mRNA expression was downregulated in allografts. MMP-2, MMP-9 and TIMP-3 seem to play a critical role in the development of fibrosis in the renal allograft.