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Noninvasive Tim-3 messenger RNA evaluation in renal transplant recipients with graft dysfunction.

Background. Renal biopsies are usually needed to elucidate graft dysfunction. In this study, T-cell immunoglobulin domain, mucin domain mRNA expression in the peripheral blood leukocytes (PBL) and urinary cells (UC) were studied as a noninvasive method for the diagnosis of acute rejection (AR) of kidney transplant patients with dysfunction. Methods. One hundred sixty biopsies were obtained from 115 patients. Blood and urine samples were collected immediately before the biopsies. Histopathologic diagnoses were acute tubular necrosis with superimposed AR or acute tubular necrosis in patients with delayed graft function (DGF), and (AR), or calcineurin inhibitor nephrotoxicity (CIN), or interstitial fibrosis and tubular atrophy in patients with acute graft dysfunction (AGD). Fifteen protocol biopsies of stable grafts were used as controls. mRNA relative quantification was performed by real-time polymerase chain reaction. Results. Gene expression in tissue, PBL, and UC was always higher in patients with AR than in patients with the other causes of graft dysfunction (P<0.001). Significant correlations of gene expression in different compartments were observed (P<0.001). The obtained diagnostic parameters were 100% accurate in the DGF group and, respectively, for blood and urine: sensitivity (87% and 84%); specificity (95% and 96%); positive predictive value (87% and 89%); negative predictive value (93% and 94%); and accuracy (91% and 93%) for the group of patients with AGD. Conclusion. T-cell immunoglobulin domain, mucin domain mRNA quantification by real-time polymerase chain reaction in PBL and UC of renal transplant patients undergoing DGF or AGD may become a useful tool for an accurate noninvasive diagnosis of AR.

Noninvasive Analyses of Kidney Injury Molecule-1 Messenger RNA in Kidney Transplant Recipients With Graft Dysfunction

BACKGROUND Kidney graft fibrosis is a major factor related to chronic loss of kidney function. At present, the finding of fibrosis depends on the analysis of tissue in the renal biopsy, which has important limitations. In this study, we evaluated the messenger mRNA transcription and gene expression of kidney injury molecule-1 (KIM-1) in kidney tissue and in urinary sediment cells of kidney transplant patients with graft dysfunction aiming at the development of techniques that may allow the noninvasive diagnosis of interstitral fibrosis/tubular atrophy (IF/TA). PATIENTS AND METHODS RNA extracted from cells in tissue and urine of 77 renal transplant patients whose biopsies were classified according to the Banff scheme-2007. Four diagnostic groups were established: (1) acute tubular necrosis (n = 9); (2) acute rejection (n = 49); (3) acute calcineurin inhibitors nephrotoxicity (n = 10); and (4) interstitial fibrosis and tubular atrophy (IFTA, n = 29). Tissue and urine cell RNA was amplified and quantification were made by real-time polymerase chain reactron. Data from the quantification of gene expression are presented as median and 25th to 75th percentiles. RESULTS Messenger RNA levels of the KIM-1 gene were higher in the biopsies (26.17; 3.38-294.53) and urinary sediment cells (0.09; 0-5.81) of the patients classified as having IF/TA as compared with all others groups. A significant correlation between gene expression in samples of urine and tissue cells was found (P < .01). CONCLUSION These initial data suggests that KIM-1 gene mRNA quantification can be used as a noninvasive biomarker of IF/TA.

Expression of fibrosis-related genes in human renal allografts with interstitial fibrosis and tubular atrophy.

BACKGROUND Gene expression analysis of fibrosis-related genes may became useful for the early identification of fibrosis processes. We quantitatively assessed messenger RNA transcripts of the CTGF, TGF-β and KIM-1 genes, in biopsy samples from renal transplant recipients with graft dysfunction, to test the hypothesis that in patients with chronic disease of the renal transplant, these molecules could be markers of the development and severity of graft fibrosis. METHODS Ninety-six kidney transplant recipients who undertook 121 indication graft biopsies between January 2008 and December 2009 were included. Patients and biopsies were classified into 4 major diagnostic groups according to the Banff 2007 classification: acute tubular necrosis (ATN; n = 20), acute rejection (AR; n = 58), acute calcineurin inhibitor nephrotoxicity (CIN; n = 13) and interstitial fibrosis and tubular atrophy (IF/TA; n = 30). RESULTS Messenger RNA transcripts of the CTGF and TGF-β genes were significantly higher in IF/TA compared with all other conditions. Messenger RNA transcripts of the KIM-1 gene in the IF/TA group were higher than in the CIN group. In addition, it was observed that gene expression of CTGF, TGF-β and KIM-1 increased with severity of fibrosis observed in the pathological examinations. CONCLUSIONS Gene expression evaluation of the kidney graft tissue may be used to improve pathological diagnosis and perhaps for the future development of noninvasive biomarkers.

Kidney injury molecule-1 expression in human kidney transplants with interstitial fibrosis and tubular atrophy

BackgroundKidney injury molecule-1 (KIM-1) is expressed in tubular epithelial cells after injury and may have a role in the development of renal graft fibrosis. In this study we evaluated the molecular and protein expressions of KIM-1 in dysfunctional allografts and also mRNA KIM-1 expression in urine as potential biomarkers of graft fibrosis.MethodsProtein and mRNA levels in renal tissue and urinary sediment cells of 69 kidney transplant recipients that undertook for-cause graft biopsies were evaluated by immunohistochemistry and real-time polymerase chain reaction. The histopathology was classified according to the 2007 Banff schema.ResultsKIM-1 protein expression was increased in biopsies with interstitial fibrosis and tubular atrophy (IF/TA) compared with biopsies showing acute calcineurin inhibitor nephrotoxicity (CIN) (P <0.05). Kidney tissue KIM-1 mRNA signaling (in) was increased in biopsies with IF/TA compared with all other groups (P <0.05). In the urine cells KIM-1 mRNA was also increased in patients with IF/TA compared with patients with acute CIN (P <0.05). Significant correlations were found between KIM-1 protein and mRNA levels in tissue, between mRNA expressions in tissue and urine and between protein tissue expression and gene expression in the urine.ConclusionsKIM-1 seems to be a marker of kidney graft fibrosis. Urinary KIM-1 mRNA may become a useful non-invasive biomarker of the injuries that can trigger intra-graft fibrotic processes, such as interstitial fibrosis and tubular atrophy.