Irina B. Torres

The reproducibility and predictive value on outcome of renal biopsies from expanded criteria donors

Reproducibility and predictive value on outcome are the main criteria to evaluate the utility of histological scores. Here we analyze the reproducibility of donor biopsy assessment by different on-call pathologists and the retrospective evaluation by a single renal pathologist blinded to clinical outcomes. We also evaluate the predictive value on graft outcome of both evaluations. A biopsy was performed in donors with any of the following: age≥55 years, hypertension, diabetes, creatinine>1.5 mg/dl, or stroke. Glomerulosclerosis, interstitial fibrosis, tubular atrophy, intimal thickening, and arteriolar hyalinosis evaluated according to the Banff criteria were added to obtain a chronic score. Biopsies were classified as mild (≥3), intermediate (4-5), or advanced (6-7) damage, and unacceptable (≥8) for transplantation of 127 kidneys biopsied. Weighted κ value between both readings was 0.41 (95% CI: 0.28-0.54). Evaluation of biopsies by the renal pathologist was significantly and independently associated with estimated 12-month glomerular filtration rate and a significant composite outcome variable, including death-censored graft survival and time to reach an estimated glomerular filtration rate<30 ml/min per 1.73 m2. Thus, there was no association between readings of on-call pathologists and outcome. The lack of association between histological scores obtained by the on-call pathologists and graft outcome suggests that a specific training on renal pathology is recommended to optimize the use of kidneys retrieved from expanded criteria donors.

Assessing Glomerular Filtration Rate in Hospitalized Patients: A Comparison Between CKD-EPI and Four Cystatin C-Based Equations

BACKGROUND AND OBJECTIVES A specific method is required for estimating glomerular filtration rate GFR in hospitalized patients. Our objective was to validate the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and four cystatin C (CysC)-based equations in this setting. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This was an epidemiologic, cross-sectional study in a random sample of hospitalized patients (n = 3114). We studied the accuracy of the CKD-EPI and four CysC-based equations--based on (1) CysC alone or (2) adjusted by gender; (3) age, gender, and race; and (4) age, gender, race, and creatinine, respectively--compared with GFR measured by iohexol clearance (mGFR). Clinical, biochemical, and nutritional data were also collected. RESULTS The CysC equation 3 significantly overestimated the GFR (bias of 7.4 ml/min per 1.73 m(2)). Most of the error in creatinine-based equations was attributable to calculated muscle mass, which depended on patients nutritional status. In patients without malnutrition or reduced body surface area, the CKD-EPI equation adequately estimated GFR. Equations based on CysC gave more precise mGFR estimates when malnutrition, extensive reduction of body surface area, or loss of muscle mass were present (biases of 1 and 1.3 ml/min per 1.73 m(2) for equations 2 and 4, respectively, versus 5.9 ml/min per 1.73 m(2) for CKD-EPI). CONCLUSIONS These results suggest that the use of equations based on CysC and gender, or CysC, age, gender, and race, is more appropriate in hospitalized patients to estimate GFR, since these equations are much less dependent on patients nutritional status or muscle mass than the CKD-EPI equation.

The Interplay between inflammation and fibrosis in kidney transplantation.

Serial surveillance renal allograft biopsies have shown that early subclinical inflammation constitutes a risk factor for the development of interstitial fibrosis. More recently, it has been observed that persistent inflammation is also associated with fibrosis progression and chronic humoral rejection, two histological conditions associated with poor allograft survival. Treatment of subclinical inflammation with steroid boluses prevents progression of fibrosis and preserves renal function in patients treated with a cyclosporine-based regimen. Subclinical inflammation has been reduced after the introduction of tacrolimus based regimens, and it has been shown that immunosuppressive schedules that are effective in preventing acute rejection and subclinical inflammation may prevent the progression of fibrosis and chronic humoral rejection. On the other hand, minimization protocols are associated with progression of fibrosis, and noncompliance with the immunosuppressive regime constitutes a major risk factor for chronic humoral rejection. Thus, adequate immunosuppressive treatment, avoiding minimization strategies and reinforcing educational actions to prevent noncompliance, is at present an effective approach to combat the progression of fibrosis.

Gene expression signature of tolerance and lymphocyte subsets in stable renal transplants: Results of a cross-sectional study

BACKGROUND In kidney transplants operational tolerance has been associated with up-regulation of B cell differentiation genes and an increased number of total, naive and transitional peripheral B cells. The aim is to evaluate tolerance biomarkers in different cohorts of stable renal transplants under immunosuppression. METHODS This is a cross-sectional study conducted in renal transplants. We evaluate genetic tolerance signature and lymphocyte subsets in stable transplants treated with calcineurin inhibitors (CNI) at 1 (n=15), 5 (n=14) and 10 (n=16) years, and azathioprine-treated transplants followed 30 years (n=8). Healthy volunteers (n=10) and patients with chronic rejection (n=15) served as controls. RESULTS We confirm that peripheral expression of IGKV1D-13 and IGKV4-1 genes by RT-PCR distinguish tolerant (n=10) from stable transplants (n=10) provided by the International Tolerance Network. Tolerance signature was defined as the lowest expression for both genes in tolerant patients. In CNI-treated patients, genetic signature of tolerance and B cells showed a time-dependent increase not observed in azathioprine-treated patients (p<0.01). Genetic tolerance signature was observed in 0% at 1, 7% at 5 and 25% at 10-years while it was not observed in azathioprine-treated and chronic rejection patients. Fifteen out of 16 CNI-treated transplants at 10 years were revaluated 3 months apart. Nine did not show the tolerance signature in any determination, 4 in one and 2 in both determinations. Genetic signature of tolerance was associated with an increase of total, naive and transitional B cells (p<0.05). CONCLUSIONS IGKV1D-13 and IGKV4-1 gene expression and its linked B cell populations increase during follow up in CNI-treated patients. At 10 years, 2 out of 15 CNI treated patients consistently express biomarkers associated with true tolerance. In azathioprine-treated patients these biomarkers were down-regulated.

Hypertension in chronic kidney disease: the influence of renal transplantation.

Background Hypertension is one of the most prevalent cardiovascular risk factors in chronic kidney disease (CKD) and kidney transplants. The contribution of transplantation to hypertension in comparison to patients with CKD and similar renal function has not been characterized. Methods Ninety-two transplants and 97 CKD patients with an estimated glomerular filtration rate less than 60 mL/min/1.73 m2 not receiving dialysis were enrolled. At entry, office blood pressure (BP) and 24-hr ambulatory blood pressure monitoring (ABPM) were obtained. Results Office BP was not different between transplants and CKD patients (139.5±14.3 vs. 135.2±19.3, P=1.00, respectively). ABPM 24-hr systolic blood pressure (SBP) (133.9±14.3 vs. 126.2±16.1, P=0.014), awake SBP (135.6±15.2 vs. 128.7±16.2, P=0.042), and sleep SBP (131.2±16.2 vs. 120.2 ±17.9, P=0.0014) were higher in renal transplants. When patients were classified according to BP patterns associated with highest cardiovascular risk, the proportion of patients with both nocturnal hypertension and non-dipper pattern was higher in transplants (68.5% vs. 47.4%, P=0.03). In the multivariate regression analysis, transplantation was an independent predictor of 24-hr, awake, and sleep SBP. Conclusion Office BP is similar in kidney transplants and CKD patients with similar renal function. On the contrary, hypertension is more severe in kidney transplants when evaluated with ABPM mainly as a result of increased sleep systolic BP. Thus, precise evaluation of hypertension in kidney transplants requires ABPM.

Comparing transplant glomerulopathy in the absence of C4d deposition and donor-specific antibodies to chronic antibody-mediated rejection

Transplant glomerulopathy (TG) is the characteristic lesion of chronic antibody‐mediated rejection (AMR). However, in some patients presents with no circulating HLA antibodies or C4d positivity.

Estimation of renal allograft half-life: fact or fiction?

INTRODUCTION Renal allograft half-life time (t½) is the most straightforward representation of long-term graft survival. Since some statistical models overestimate this parameter, we compare different approaches to evaluate t½. PATIENTS AND METHODS Patients with a 1-year functioning graft transplanted in Spain during 1990, 1994, 1998 and 2002 were included. Exponential, Weibull, gamma, lognormal and log-logistic models censoring the last year of follow-up were evaluated. The goodness of fit of these models was evaluated according to the Cox-Snell residuals and the Akaikes information criterion (AIC) was employed to compare these models. RESULTS We included 4842 patients. Real t½ in 1990 was 14.2 years. Median t½ (95% confidence interval) in 1990 and 2002 was 15.8 (14.2-17.5) versus 52.6 (35.6-69.5) according to the exponential model (P < 0.001). No differences between 1990 and 2002 were observed when t½ was estimated with the other models. In 1990 and 2002, t½ was 14.0 (13.1-15.0) versus 18.0 (13.7-22.4) according to Weibull, 15.5 (13.9-17.1) versus 19.1 (15.6-22.6) according to gamma, 14.4 (13.3-15.6) versus 18.3 (14.2-22.3) according to the log-logistic and 15.2 (13.8-16.6) versus 18.8 (15.3-22.3) according to the lognormal models. The AIC confirmed that the exponential model had the lowest goodness of fit, while the other models yielded a similar result. CONCLUSIONS The exponential model overestimates t½, especially in cohorts of patients with a short follow-up, while any of the other studied models allow a better estimation even in cohorts with short follow-up.

Treatment of chronic antibody mediated rejection with intravenous immunoglobulins and rituximab: A multicenter, prospective, randomized, double-blind clinical trial

There are no approved treatments for chronic antibody mediated rejection (ABMR). We conducted a multicenter, prospective, randomized, placebo‐controlled, double‐blind clinical trial to evaluate efficacy and safety of intravenous immunoglobulins (IVIG) combined with rituximab (RTX) (EudraCT 2010‐023746‐67). Patients with transplant glomerulopathy and anti‐HLA donor‐specific antibodies (DSA) were eligible. Patients with estimated glomerular filtration rate (eGFR) <20 mL/min per 1.73m2 and/or severe interstitial fibrosis/tubular atrophy were excluded. Patients were randomized to receive IVIG (4 doses of 0.5 g/kg) and RTX (375 mg/m2) or a wrapped isovolumetric saline infusion. Primary efficacy variable was the decline of eGFR at one year. Secondary efficacy variables included evolution of proteinuria, renal lesions, and DSA at 1 year. The planned sample size was 25 patients per group. During 2012‐2015, 25 patients were randomized (13 to the treatment and 12 to the placebo group). The planned patient enrollment was not achieved because of budgetary constraints and slow patient recruitment. There were no differences between the treatment and placebo groups in eGFR decline (−4.2 ± 14.4 vs. −6.6 ± 12.0 mL/min per 1.73 m2, P‐value = .475), increase of proteinuria (+0.9 ± 2.1 vs. +0.9 ± 2.1 g/day, P‐value = .378), Banff scores at one year and MFI of the immunodominant DSA. Safety was similar between groups. These data suggest that the combination of IVIG and RTX is not useful in patients displaying transplant glomerulopathy and DSA.

Inflammation and Atherosclerosis Are Associated With Hypertension in Kidney Transplant Recipients.

The aim of the current study was to evaluate risk factors associated with hypertension in kidney transplant recipients. The authors recruited 92 consecutive kidney transplant recipients and 30 age‐matched patients with chronic kidney disease without history of cardiovascular events. Twenty‐four–hour ambulatory blood pressure monitoring, pulse wave velocity, and carotid ultrasound were performed. Serum levels of log‐transformed interleukin 6 (Log IL‐6), soluble tumor necrosis factor receptor 2, and intercellular adhesion molecule 1 were determined. Twenty‐four–hour systolic blood pressure (SBP) (P=.0001), Log IL‐6 (P=.011), and total number of carotid plaques (P=.013) were higher, while the percentage decline of SBP from day to night was lower in kidney transplant recipients (P=.003). Independent predictors of 24‐hour SBP were urinary protein/creatinine ratio and circulating monocytes (P=.001), while Log IL‐6, serum creatinine, and total number of carotid plaques (P=.0001) were independent predictors of percentage decline of SBP from day to night. These results suggest that subclinical atherosclerosis and systemic inflammation are associated with hypertension after transplantation.

Nonadherence to immunosuppression: challenges and solutions

License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php Transplant Research and Risk Management 2015:7 27–34 Transplant Research and Risk Management Dovepress