Association between fibrosis-related gene polymorphism and long-term allograft outcome in renal transplant recipients.

BACKGROUND: Renal allograft fibrosis is one of characteristic causes of long-term renal function loss. The purpose of our study is to investigate the association between fibrosis-related genes single nucleotide polymorphism (SNPs) and kidney function in 5 years after kidney transplantation. METHODS: A total of 143 recipients were eligible for screening with 5-year follow-up information and SNP sequencing information from blood samples were included in this study. Minor Allele Frequency (MAF) and Hardy-Weinberg Equilibrium (HWE) analysis was conducted to identify tagger single-nucleotide polymorphisms (SNPs) and haplotypes. SNPs associated with the fifth year chronic kidney disease (CKD) staging were screened by SPSS and the "SNPassoc" package in RStudio and used for subsequent prediction model construction. RESULTS: A total of 275 renal transplant-related SNPs identified after target sequencing analysis. 64 Tagger SNPs were selected, and two SNPs (rs13969 and rs243849) were statistically significant for stage of CKD in 5 years. Finally, a model based on Gender, Age, rs1396, and rs243849 was constructed by multivariate linear regression analysis. Additionally, this model has a good performance in predicting uremia five years after kidney transplantation. CONCLUSION: Two SNPs (rs13969 and rs243849) were identified to be significantly associated with long-term renal allograft function. Based on this, a prediction model for long-term allograft function was established containing Gender, Age, rs1396, and rs243849. However, an independent cohort should be enrolled to validate the predicting performance.

Incidence and risk factors of subclinical rejection after pediatric liver transplantation, and impact on allograft fibrosis.

INTRODUCTION: Subclinical rejection (SCR) is a common injury in protocol biopsy after pediatric liver transplantation (pLT), but its effect on the recipient is not clearly understood. We herein investigated the incidence and risk factors involved in SCR and analyzed the relationship between SCR and allograft fibrosis (AF). METHODS: We retrospectively reviewed the biopsy results from 507 children between May 2013 and May 2019, and 352 patients underwent protocol biopsy 2 years after pLT, 203 underwent protocol biopsy 5 years after pLT, and 48 underwent protocol biopsy both 2 and 5 years after pLT. RESULTS: The incidence of SCR in the 5-year group was higher than that in the 2-year group (20.2% vs.13.4%, respectively, p = .033). The number of patients with mild and moderate SCR in the 5-year group was also higher than that in the 2-year group (p = .039). Logistic regression analysis showed that acute rejection before liver biopsy and deceased donor liver transplantation (DDLT) were independent risk factors for SCR in the two groups, and that the incidence and severity of AF in protocol biopsies at both periods in the SCR group were higher than those in the non-SCR group (p < .05). CONCLUSIONS: The incidence and severity of SCR increased with the prolongation of protocol biopsy time. We postulate that acute rejection and DDLT are independent risk factors for SCR after transplantation. As the occurrence of SCR also augmented the incidence and severity of AF.

Long-term liver allograft fibrosis: A review with emphasis on idiopathic post-transplant hepatitis and chronic antibody mediated rejection.

Liver transplantation (LT) is a life-saving surgical procedure and the current standard of care for most patients with end stage liver disease. With improvements in organ preservation techniques, perioperative care, and immunosuppression, there is better patient and graft survival following LT, and assessment of the liver allograft in long-term survivors is becoming increasingly important. Recurrent or de novo viral or autoimmune injury remains the most common causes of chronic hepatitis and fibrosis following liver transplantation in adults. However, no obvious cause can be identified in many adults with controlled recurrent disease and the majority of pediatric LT recipients, as they have been transplanted for non-recurrent liver diseases. Serial surveillance liver biopsies post LT have been evaluated in several adult and pediatric centers to identify long-term pathological changes. Pathological findings are frequently present in liver biopsies obtained after a year post LT. The significance of these findings is uncertain as many of these are seen in protocol liver biopsies from patients with clinically good allograft function and normal liver chemistry parameters. This narrative review summaries the factors predisposing to long-term liver allograft fibrosis, highlighting the putative role of idiopathic post-LT hepatitis and chronic antibody mediated rejection in its pathogenesis.

Determination of allograft fibrosis by measurement of liver stiffness using transient elastography in children after liver transplantation at Shiraz Organ Transplant Center.

AIM: The aim of this study was to determine allograft fibrosis by measuring LS using TE in children after liver transplantation at Shiraz Organ Transplant Center. BACKGROUND: Liver stiffness (LS) assessment using fibro-scanning (transient elastography-TE) is a non-invasive method for evaluating liver fibrosis. METHODS: All children undergoing liver transplant from 2012 to 2016 were included in the study. Data on demographics, graft types, immunosuppressive drugs, as well as clinical and paraclinical data were obtained from patients' records. TE was performed to determine LS in all patients. Liver fibrosis was also confirmed based on Metavir score. RESULTS: During this period, more than 400 liver Tx were done in children, but only 54 patients, comprising 20 (37%) girls and 34 (63%) boys who underwent liver transplantation, were available and willing to participate in this study. The mean age of the patients was 12.96 ± 5.32 years. Correlations between FS score (LS) and AST (p = 0.01), total bilirubin (p = 0.002), albumin (p = 0.001), PT (p = 0.03), and INR (p = 0.001) were significant. There was no significant relationship between FS score (LS) and type of allograft (p = 0.79) and underlying disease (p = 0.36). Positive and significant correlations were observed between Metavir score and AST (p = 0.01), total bilirubin (p = 0.01), INR (p = 0.004), and cholesterol (p = 0.001). The severity of fibrosis significantly and negatively correlated with albumin (p = 0.004) and glucose (p = 0.003). Also, there was no significant relationship between Metavir score and allograft type (p = 0.7). CONCLUSION: The current study demonstrated that 14.9% of LT patients had a METAVIR ≥ F2. The time between LT and TE was significantly correlated with LS and the degree of liver fibrosis based on Metavir score. However, there was no significant relationship between LS with allograft type or underlying liver disease.

Curcumin Blunts IL-6 Dependent Endothelial-to-Mesenchymal Transition to Alleviate Renal Allograft Fibrosis Through Autophagy Activation.

Fibrosis contributes to graft loss in chronic renal allograft injury. Endothelial-to-mesenchymal transition (EndMT) plays an important role in the development of fibrosis following kidney transplantation. Autophagy plays an important role in the homeostasis of diverse cell types including endothelial cells. Here we demonstrate that inhibition of autophagy by treatment with 3-methyladenine (3-MA) or by silencing autophagy-related (ATG)5 promoted interleukin (IL)-6-dependent EndMT in human umbilical vein endothelial cells (HUVECs) and human renal glomerular endothelial cells (HRGECs), and autophagy inactivation was associated with EndMT in patients with chronic allograft dysfunction. IL-6 level was significantly higher in the culture medium of HUVECs transfected with ATG5 siRNA or treated with 3-MA compared to the respective control groups. IL-6 application induced EndMT in HUVECs and HRGECs, whereas antibody-mediated neutralization of IL-6 suppressed EndMT induced by ATG5 silencing. The protective role of curcumin (Cur) against allograft fibrosis was confirmed in a rat kidney transplantation model of F344 donors to Lewis recipients. Curcumin-a natural polyphenol compound with known antifibrotic effects in various tissues-alleviated IL-6-induced EndMT and promoted autophagy in the allografted organ and in HUVECs. This is the first demonstration of the role of autophagy in renal allograft fibrosis; our findings indicate that curcumin can alleviate chronic renal allograft injury by suppressing IL-6-dependent EndMT via activation of autophagy.

Donor-But Not Recipient-Derived Cells Produce Collagen-1 in Chronically Rejected Cardiac Allografts.

Fibrosis is a prominent feature of chronic allograft rejection, caused by an excessive production of matrix proteins, including collagen-1. Several cell types produce collagen-1, including mesenchymal fibroblasts and cells of hematopoietic origin. Here, we sought to determine whether tissue-resident donor-derived cells or allograft-infiltrating recipient-derived cells are responsible for allograft fibrosis, and whether hematopoietic cells contribute to collagen production. A fully MHC-mismatched mouse heterotopic heart transplantation model was used, with transient depletion of CD4+ T cells to prevent acute rejection. Collagen-1 was selectively knocked out in recipients or donors. In addition, collagen-1 was specifically deleted in hematopoietic cells. Tissue-resident macrophages were depleted using anti-CSF1R antibody. Allograft fibrosis and inflammation were quantified 20 days post-transplantation. Selective collagen-1 knock-out in recipients or donors showed that tissue-resident cells from donor hearts, but not infiltrating recipient-derived cells, are responsible for production of collagen-1 in allografts. Cell-type-specific knock-out experiments showed that hematopoietic tissue-resident cells in donor hearts substantially contributed to graft fibrosis. Tissue resident macrophages, however, were not responsible for collagen-production, as their deletion worsened allograft fibrosis. Donor-derived cells including those of hematopoietic origin determine allograft fibrosis, making them attractive targets for organ preconditioning to improve long-term transplantation outcomes.

Significance of progressive liver fibrosis in pediatric liver transplants: A review of current evidence.

This article reviews the current evidence and knowledge of progressive liver fibrosis after pediatric liver transplantation. This often-silent histologic finding is common in long-term survivors and may lead to allograft dysfunction in advanced stages. Surveillance through protocolized liver allograft biopsy remains the gold standard for diagnosis, and recent evidence suggests that chronic inflammation precedes fibrosis.

Multiparametric magnetic resonance imaging shows promising results to assess renal transplant dysfunction with fibrosis.

Here we assessed the diagnostic value of a quantitative multiparametric magnetic resonance imaging (mpMRI) protocol for evaluation of renal allograft dysfunction with fibrosis. Twenty-seven renal transplant patients, including 15 with stable functional allografts (eGFR mean 71.5 ml/min/1.73m2), and 12 with chronic dysfunction/established fibrosis (eGFR mean 30.1 ml/min/1.73m2), were enrolled in this prospective single-center study. Sixteen of the patients had renal biopsy (mean 150 days) before the MRI. All patients underwent mpMRI at 1.5T including intravoxel-incoherent motion diffusion-weighted imaging, diffusion tensor imaging, blood oxygen level dependent (BOLD R2*) and T1 quantification. True diffusion D, pseudodiffusion D*, perfusion fraction PF, apparent diffusion coefficient (ADC), fractional anisotropy (FA), R2* and T1 were calculated for cortex and medulla. ΔT1 was calculated as (100x(T1 Cortex-T1 Medulla)/T1 Cortex). Test-retest repeatability and inter-observer reproducibility were assessed in four and ten patients, respectively. mpMRI parameters had substantial test-retest and interobserver repeatability (coefficient of variation under 15%), except for medullary PF and D* (coefficient of variation over 25%). Cortical ADC, D, medullary ADC and ΔT1 were all significantly decreased, while cortical T1 was significantly elevated in fibrotic allografts. Cortical T1 showed positive correlation to the Banff fibrosis and tubular atrophy scores. The combination of ΔT1 and cortical ADC had excellent cross-validated diagnostic performance for detection of chronic dysfunction with fibrosis. Cortical ADC and T1 had good performance for predicting eGFR decline at 18 months (4 or more ml/min/1.73m2/year). Thus, the combination of cortical ADC and T1 measurements shows promising results for the non-invasive assessment of renal allograft histology and outcomes.

Tissue inhibitor of metalloproteinase 1 and AST-to-Platelet Ratio Index as noninvasive biomarkers predict allograft fibrosis after pediatric liver transplantation.

BACKGROUND: Assessing liver fibrosis in patients after liver transplantation is still largely dependent on liver biopsy. Especially in children, noninvasive methods are of utmost importance. We evaluated tissue inhibitor of metalloproteinase 1 (TIMP1) and AST-to-Platelet Ratio Index (APRI) and their potential as serum biomarkers to predict liver allograft fibrosis (LAF) in a pediatric cohort. METHODS: In this retrospective, observational study, we analyzed 91 protocol liver biopsy specimens from 73 children after pediatric liver transplantation (PLT) and compared histological stage of liver fibrosis using LAF Score (LAFSc) and Ishak Score (IshakSc) to TIMP1-serum concentration and APRI using ROC analysis. RESULTS: In our cohort, TIMP1 and APRI reliably predict LAF. Depending on the histological scoring system, cutoff values for TIMP1 were 328 ng/mL (IshakSc ≥ IV) and 351 ng/mL (LAFSc ≥ 5) with AUC of 0.86 and 0.98. The cutoff for APRI was 0.8 with AUC of 0.87 (IshakSc ≥ IV) and 0.94 (LAFSc ≥ 5). Using LAFSc, TIMP1 and APRI showed excellent diagnostic accuracy to detect severe LAF (LAFSc ≥ 5) with PPV of ≥ 90% and NPV of 100%. CONCLUSION: TIMP1 and APRI are accurate biomarkers to predict severe LAF in children. The use of TIMP1 and APRI will not replace but complement liver biopsies after PLT to further improve our understanding of each individual patient.

Late allograft fibrosis in pediatric liver transplant recipients: Assessed by histology and transient elastography.

Late allograft fibrosis in LT recipients can cause graft dysfunction and may result in re-transplantation. TE is a non-invasive tool for the assessment of liver fibrosis. We aimed to evaluate the prevalence of allograft fibrosis in pediatric LT recipients, identify factors associated with allograft fibrosis, and determine the diagnostic value of TE, compared to histology. All children who underwent LT for ≥3 years were included. TE was performed for LSM in all patients. LSM of ≥7.5 kPa was considered as abnormal and suggestive of allograft fibrosis. Percutaneous liver biopsy was performed when patients had abnormal LSM and/or abnormal LFTs. Histological fibrosis was diagnosed when METAVIR score ≥F1 or LAF scores ≥1. TE was performed in 43 patients and 14 (32.5%) had abnormal LSM suggestive of allograft fibrosis. Histological fibrosis was identified in 10 of the 15 patients (66.7%) who underwent percutaneous liver biopsy and associated findings included chronic active HBV infection (n = 3), and late acute rejection (n = 3). Multivariate analysis showed that graft age was significantly associated with allograft fibrosis (OR = 1.22, 95% CI: 1.05-1.41, P = 0.01). In conclusion, late allograft fibrosis is common in children undergoing LT for ≥3 years and associated with graft age. HBV infection and late acute rejection are common associated findings. Abnormal TE and/or LFTs may guide physicians to consider liver biopsy for the detection of late allograft fibrosis in LT children.

Multiparametric Functional Magnetic Resonance Imaging for Evaluating Renal Allograft Injury.

Kidney transplantation is the treatment of choice for patients with end-stage renal disease, as it extends survival and increases quality of life in these patients. However, chronic allograft injury continues to be a major problem, and leads to eventual graft loss. Early detection of allograft injury is essential for guiding appropriate intervention to delay or prevent irreversible damage. Several advanced MRI techniques can offer some important information regarding functional changes such as perfusion, diffusion, structural complexity, as well as oxygenation and fibrosis. This review highlights the potential of multiparametric MRI for noninvasive and comprehensive assessment of renal allograft injury.

Multiparametric Functional Magnetic Resonance Imaging for Evaluating Renal Allograft Injury

Kidney transplantation is the treatment of choice for patients with end-stage renal disease, as it extends survival and increases quality of life in these patients. However, chronic allograft injury continues to be a major problem, and leads to eventual graft loss. Early detection of allograft injury is essential for guiding appropriate intervention to delay or prevent irreversible damage. Several advanced MRI techniques can offer some important information regarding functional changes such as perfusion, diffusion, structural complexity, as well as oxygenation and fibrosis. This review highlights the potential of multiparametric MRI for noninvasive and comprehensive assessment of renal allograft injury.

Expression profile of mammalian target of rapamycin-related proteins in graft biopsy specimens: Significance for predicting interstitial fibrosis after kidney transplantation.

OBJECTIVE: To investigate the influence of the expression profile of mammalian target of rapamycin-related proteins on the development of interstitial fibrosis after kidney transplantation. METHODS: Immunohistochemical staining was carried out to evaluate the expression of five mammalian target of rapamycin-related proteins (phosphorylated-Akt, Ras homolog enriched in brain, phosphorylated-mammalian target of rapamycin, phosphorylated-p70 ribosomal S6 kinase and phosphorylated-4E binding protein 1) in graft biopsy specimens obtained from 77 patients at 3 months after kidney transplantation. The change of the estimated glomerular filtration rate and the change of the fibrosis index (defined as the change in the percent area of fibrosis on Masson's trichrome-stained sections of biopsy specimens) from 3 months to 3 years after kidney transplantation were determined. RESULTS: There was a significant correlation between change of the estimated glomerular filtration and change of the fibrosis index in the 77 patients. Univariate analysis identified expression of phosphorylated-Akt, phosphorylated-mammalian target of rapamycin and phosphorylated-p70 ribosomal S6 kinase, as well as donor type and pre-transplant dialysis duration, as significant predictors of a change of the fibrosis index >10%. However, only phosphorylated-mammalian target of rapamycin expression, phosphorylated-p70 ribosomal S6 kinase expression and donor type were independently associated with a change of the fibrosis index >10% according to multivariate analysis. CONCLUSIONS: These findings suggest that mammalian target of rapamycin-related proteins are involved in the development of interstitial fibrosis after kidney transplantation.

Blood capillary rarefaction and lymphatic capillary neoangiogenesis are key contributors to renal allograft fibrosis in an ACE inhibition rat model.

Chronic allograft fibrosis is the major cause of graft loss in kidney transplantation. Progression can only be reduced by inhibition of the renin-angiotensin system (RAS). We tested the hypothesis that the protection provided by angiotensin-converting enzyme (ACE) inhibition also decreases capillary rarefaction, lymphangiogenesis, and podocyte injury in allograft fibrosis. Fisher kidneys were transplanted into bilaterally nephrectomized Lewis rats treated with enalapril (60 mg/kg per day) (ACE inhibitor, ACEi) or vehicle. Proteinuria, blood urea nitrogen, and plasma creatinine were regularly assessed, and grafts were harvested for morphological and immunohistological analysis at various times up to 32 wk. In the vehicle group, many new lymphatic capillaries and severe and diffuse mononuclear infiltration of allografts were observed already 1 wk after transplantation. Lymphangiogenesis increased until week 4, by which time inflammatory infiltration became focal. Lymphatic capillaries were often located at sites of inflammation. Progressive interstitial fibrosis, glomerulosclerosis, capillary rarefaction, and proteinuria appeared later, at weeks 4-12 The number of lymphatic capillary cross sections strongly correlated with the interstitial fibrosis score. Podoplanin immunostaining, a marker of healthy podocytes, disappeared from inflamed or sclerotic glomerular areas. ACEi protected from lymphangiogenesis and associated inflammation, preserved glomerular podoplanin protein expression, and reduced glomerulosclerosis, proteinuria, tubulointerstitial fibrosis, and blood capillary rarefaction at 32 wk. In conclusion, ACEi considerably decreased and/or delayed both glomerulosclerosis and tubulointerstitial injury. Prevention of glomerular podoplanin loss and proteinuria could be attributed to the known intraglomerular pressure-lowering effects of ACEi. Reduction of lymphangiogenesis could contribute to amelioration of tubulointerstitial fibrosis and inflammatory infiltration after ACEi.

Use of Contrast-Enhanced Ultrasonography to Evaluate Chronic Allograft Nephropathy in Rats and Correlations between Time-Intensity Curve Parameters and Allograft Fibrosis.

This study quantitatively analyzed changes in the hemodynamic characteristics of renal allografts at different stages in a rat chronic allograft nephropathy (CAN) model as well as the relationship between hemodynamic parameters and renal allograft fibrosis using contrast-enhanced ultrasonography (CEUS). The experimental group used a CAN rat model (n = 30), and the control group used an orthotopic syngeneic renal transplant model (n = 30). After surgery, creatinine clearance rates were regularly monitored every 2 wk. The checking times were set at 4, 12 and 24 wk after surgery, which represent early, middle and late stage of CAN, respectively. At different stages of CAN, eight rats from each group were randomly selected for CEUS examination. Time-intensity curve (TIC) parameters, including rise time, peak intensity, mean transit time, area under the curve, wash-in slope, time-to-peak and α-smooth muscle actin (α-SMA) expression; Vimentin expression; and chronic allograft damage index scores were evaluated by linear correlation analysis. Before the creatinine clearance rate showed significant abnormalities, the renal allografts in the experimental group had already presented pathologic changes associated with CAN. In the early stage after surgery, compared to the TIC curve of the control group, the experimental group showed increased rise time, mean transit time, area under the curve and time-to-peak, and decreased wash-in slope (p < 0.05). Chronic allograft damage index scores and the expression levels of α-SMA and Vimentin proteins in renal allografts were correlated with TIC parameters (p < 0.05). Compared to creatinine clearance rate, CEUS can detect CAN at earlier stages. The correlations between TIC-related parameters and the expression levels of α-SMA and Vimentin in renal allografts indicate that CEUS is a feasible way to assess the degree of renal allograft fibrosis quantitatively.

The role of renin-angiotensin system in the chronic allograft nephropathy: an immunohistochemical study.

BACKGROUND: Evidences suggest a role of renin-angiotensin system (RAS) in the development of chronic allograft injury. METHODS: We correlated intrarenal angiotensin-converting enzyme, angiotensin II (Angio II) and transforming growth factor ß1 (TGFß1) expression in 58 biopsies-proven chronic allograft nephropathy (CAN) with tissue injury and allograft survival. RESULTS: The biopsies with CAN were graded according to Banff classification as I (22 cases), II (17) and III (19); 27 biopsies also showed a mononuclear inflammatory infiltrate in scarred areas. There were increased expression of angiotensin converting-enzyme (ACE), Angio II and TGFß1 mainly in tubulointerstitial compartment in the group with CAN; there was no association of Angio II and TGFß1 expression with interstitial fibrosis. There were no significant differences of ACE, Angio II and TGFß1 expression between the patients treated and untreated with RAS blockade, and with the graft outcome. Interstitial inflammatory infiltrate had positive correlation with interstitial fibrosis and significant impact on graft survival at 8 years. CONCLUSIONS: Our study showed in a group of cases with CAN a high percentage of inflammatory infiltrate that correlated with interstitial fibrosis and graft outcome. The chronic inflammatory changes in these cases did not show significant association with local RAS expression.

Evolution of allograft fibrosis and function in kidney transplant recipients: a retrospective analysis of stable patients under CNI and mTORi.

Histological evaluations of renal allograft biopsies are essential for diagnosis, but still show a low predictive value for long-term allograft function. One limitation relies on the fact that the analysis is usually based on a single biopsy sample, and therefore, no dynamic changes are considered. Using two distinct approaches, we evaluated the evolution of fibrosis and related markers in 36 stable kidney transplant patients under calcineurin inhibitor therapy with two indication biopsies each, prior and at least 6 months after substitution by mTORi (N = 18), or maintenance on CNI (N = 18). In the method comparison, both Banff chronicity score and the digitally assessed fibrosis were correlated with allograft function at biopsy (r = -0.36 and r = -0.72, P = 0.002 and P < 0.0001, respectively). However, only the progression of fibrosis digitally assessed was correlated with allograft function loss, not only within the time between biopsies (r = -0.47, P = 0.004) but also in the 60-month follow-up (r = -0.47, P = 0.006). In the group analysis, despite of a higher incidence of C4d positivity (P = 0.05), progression of fibrosis, TGF-ß1 expression, and allograft function decline were significantly lower after conversion to mTORi compared with maintenance on CNI (P = 0.05, P = 0.02 and P = 0.01, respectively). PDGF, VEGF, b-FGF, and HIF1A expressions remained stable over time regardless of therapy.