Roberto Ceratti Manfro

Non-invasive diagnosis of acute rejection in kidney transplants with delayed graft function.

Delayed graft function (DGF) often occurs in kidney transplants from deceased donors. We wanted to provide studies giving more accurate non-invasive tests for acute rejection (AR). Using real-time PCR, we examined the expression of cytolytic molecules such as perforin, granzyme B, and fas-ligand along with serpin proteinase inhibitor-9. We also measured the expression of FOXP3, a characteristic gene of T-regulatory cells known to be involved in AR. These studies were conducted on peripheral blood monocytes, urinary cells, and 48 surveillance kidney biopsies taken from a total of 35 patients with DGF. Of these patients, 20 had a histopathological diagnosis of AR, whereas other 28 had characteristics of acute tubular necrosis (ATN). Expression of cytolytic and apoptotic-associated genes in the biopsy tissue, peripheral blood leukocytes, and urinary cells was significantly higher in patients with AR than that in patients with ATN. Diagnostic parameters associated with FOXP3 gene expression were most accurate in peripheral blood leukocytes and urine cells with sensitivity, specificity, positive and negative predictive values, and accuracy between 94 and 100%. Our study shows that quantification of selected genes in peripheral blood leukocytes and urinary cells from renal transplant patients with DGF may provide a useful and accurate non-invasive diagnosis of AR.

FOXP3+ regulatory T cells: From suppression of rejection to induction of renal allograft tolerance☆

Naturally occurring and induced regulatory T cells (Tregs) can become hyporesponsive and anergic to antigen stimulation in autoimmune diseases and allograft rejection. The mechanisms of suppression of effector T cells by Tregs remain unclear, but there are in vitro and in vivo evidences showing that these cells are able to suppress antigen-specific responses via direct cell-to-cell contact, secrete anti-inflammatory cytokines such as TGF-β and IL-10, and inhibit the generation of memory T cells, among others. The transcription factor FOXP3 is a specific marker of Tregs and its deficiency is associated with autoimmune diseases and inflammation. During acute rejection of kidney allografts, an augmented FOXP3 gene expression as well as increased CD4(+)CD25(+)FOXP3(+) and other cell populations are observed in graft biopsies. However, it is not clear whether Tregs migrate into the graft and are retained there to suppress the inflammatory process, or whether they are directly associated with more complex mechanisms to induce immune tolerance. FOXP3(+) Tregs may direct the immune response toward a graft acceptance program, potentially affecting the long-term survival of transplanted organs and tissues. Immunosuppressive drugs modulate the number and function of circulating Tregs and FOXP3 expression. Experimental and clinical studies have shown that mTOR inhibitors have positive and calcineurin inhibitors negative effects on Tregs, but it is difficult to set apart the effect of multiple other factors known to be associated with short- and long-term renal graft outcomes. This review aimed to describe the functions of Tregs and its transcription factor FOXP3 in suppression of immune response during rejection and in induction of kidney graft tolerance, as well as to review the individual effects of immunosuppressive drugs on Tregs.

Reproducibility of the Banff classification in subclinical kidney transplant rejection.

Abstract:  The Banff classification for kidney allograft pathology has proved to be reproducible, but its inter and intraobserver agreement can vary substantially among centres. The aim of this study was to evaluate Banff reproducibility of surveillance renal allograft biopsies among renal pathologists from different transplant centres. This study included 32 renal transplant patients with stable graft function. Biopsies were performed 2 and 12 months post‐transplant. Histology was interpreted according to the Banff schema by three renal pathologists, and inter and intraobserver agreement were measured. The best reproducibility was obtained for the presence or absence of acute rejection (AR), with kappa values ranging from moderate (κ = 0.47; p = 0.006) to good (κ = 0.72; p = 0.0001). However, the agreement for ‘suspicious for AR’ category was poor between all observers. For scoring and grading interstitial inflammation and intimal arteritis the agreement were poor and moderate, respectively. Reproducibility for the presence or absence of chronic allograft nephropathy (CAN) was heterogeneous, ranging from poor (κ = 0.13; p = NS) to moderate (κ = 0.56; p = 0.007). Scoring chronic changes such as fibrous intimal thickening gave a reasonable interobserver agreement. Intraobserver reproducibility was good for presence or absence of AR, but was poor for the diagnosis of CAN. In conclusion, histologic analysis of stable renal allografts based on Banff criteria showed a good agreement for the diagnosis of AR and a reasonable kappa for CAN, but reproducibility for scoring and grading showed a substantial interobserver variation.

Endothelin-1 plasma levels and hypertension in cyclosporine-treated renal transplant patients

Abstract:  Experimental models suggest that endothelin‐1 (ET‐1) has a significant role in the pathogenesis of cyclosporin A (CyA)‐induced hypertension. However, its serum levels evaluated in different studies, including patients who received solid organ transplants, exhibited controversial results. Our study population consisted of 43 renal transplant patients: 33 were taking CyA as a component of their immunosuppressive regimen (CyA group) and 10 that were not taking CyA (control group). Baseline laboratory data, blood pressure and ET‐1 levels were taken at baseline and 3 and 4 h after the ingestion of CyA. In the control group samples were collected in the corresponding periods of time. Blood pressure was significantly higher in the CyA group (mean blood pressure: 101.2 ± 9.5 vs. 91.1 ± 10.7 mmHg; p < 0.001), who also presented higher serum creatinine (1.2 ± 0.28 vs. 0.97 ± 0.13 mg/dL; p < 0.001) and ET‐1 levels. In the CyA group an ET‐1 peak was evident by the third hour after CyA ingestion that showed its maximum concentration after 1–2 h; the control group exhibited significantly lower levels of ET‐1 (p = 0.044). ET‐1 levels compared between patients with and without hypertension showed a non‐statistically significant difference (1.54 ± 0.76 vs. 1.27 ± 0.62 ng/mL; p = 0.27, respectively). In conclusion, in the present study chronic CyA ingestion was associated with higher blood pressure and plasma ET‐1 levels.

Interleukin-6 Is a Better Predictor of Mortality as Compared to C-Reactive Protein, Homocysteine, Pentosidine and Advanced Oxidation Protein Products in Hemodialysis Patients

Inflammatory markers predict mortality in hemodialysis (HD) patients, whereas a possible association between oxidative stress (OS) markers and survival is less clear. We assessed the impact on all-cause mortality of baseline inflammatory [high-sensitivity C-reactive protein and interleukin-6 (IL-6)] and OS markers (advanced oxidation protein products, pentosidine, homocysteine) in 112 HD patients. We found no significant correlations between inflammatory and OS markers. During the 5.5 years of follow-up, 51 patients died. In a Kaplan-Meier analysis, the survival rate was reduced in patients with IL-6 higher than the median (IL-6 >4.2 pg/ml) (log- rank = 6.47; p = 0.01), in diabetics (log-rank = 12.26; p = 0.0005) and in older patients (log-rank = 11.22; p = 0.0008). Moreover, in Cox analysis only IL-6 and age were independently associated with mortality. We conclude that in this group of prevalent Brazilian HD patients, IL-6 was a better predictor of survival than other inflammatory and OS markers.

Effect of hepatitis C serology on C-reactive protein in a cohort of Brazilian hemodialysis patients.

Hepatitis C (HCV) is not an uncommon feature in hemodialysis (HD) patients and may be a cause of systemic inflammation. Plasma cytokine interleukin-6 (IL-6) is mainly produced by circulating and peripheral cells and induces the hepatic synthesis of C-reactive protein (CRP), which is the main acute phase reactant. The aim of this study was to investigate the influence of HCV on two markers of systemic inflammation, serum CRP and IL-6, in HD patients. The study included 118 HD patients (47% males, age 47 +/- 13 years, 9% diabetics) who had been treated by standard HD for at least 6 months. The patients were divided into two groups depending on the presence (HCV+) or absence (HCV-) of serum antibodies against HCV. Serum albumin (S-Alb), plasma high sensitivity CRP (hsCRP), IL-6, and alanine aminotransferase (ALT) were measured and the values were compared with those for 22 healthy controls. Median hsCRP and IL-6 values and hsCRP/IL-6 ratio were: 3.5 vs 2.1 mg/l, P < 0.05; 4.3 vs 0.9 pg/ml, P < 0.0001, and 0.8 vs 2.7, P < 0.0001, for patients and controls, respectively. Age, gender, S-Alb, IL-6 and hsCRP did not differ between the HCV+ and HCV- patients. However, HCV+ patients had higher ALT (29 +/- 21 vs 21 +/- 25 IU/l) and had been on HD for a longer time (6.1 +/- 3.0 vs 4.0 +/- 2.0 years, P < 0.0001). Moreover, HCV+ patients had a significantly lower median hsCRP/IL-6 ratio (0.7 vs 0.9, P < 0.05) compared to the HCV- group. The lower hsCRP/IL-6 ratio in HCV+ patients than in HCV- patients suggests that hsCRP may be a less useful marker of inflammation in HCV+ patients and that a different cut-off value for hsCRP for this population of patients on HD may be required to define inflammation.

Improvement in renal function in kidney transplant recipients switched from cyclosporine or tacrolimus to belatacept: 2‐year results from the long‐term extension of a phase II study

Kidney transplant recipients who switched from a calcineurin inhibitor (CNI) to belatacept demonstrated higher calculated glomerular filtration rates (cGFRs) at 1 year in a Phase II study. This report addresses whether improvement was sustained at 2 years in the long‐term extension (LTE). Patients receiving cyclosporine or tacrolimus were randomized to switch to belatacept or continue CNI. Of 173 randomized patients, 162 completed the 12‐month main study and entered the LTE. Two patients (n = 1 each group) had graft loss between Years 1–2. At Year 2, mean cGFR was 62.0 ml/min (belatacept) vs. 55.4 ml/min (CNI). The mean change in cGFR from baseline was +8.8 ml/min (belatacept) and +0.3 ml/min (CNI). Higher cGFR was observed in patients switched from either cyclosporine (+7.8 ml/min) or tacrolimus (+8.9 ml/min). The frequency of acute rejection in the LTE cohort was comparable between the belatacept and CNI groups by Year 2. All acute rejection episodes occurred during Year 1 in the belatacept patients and during Year 2 in the CNI group. There were more non‐serious mucocutaneous fungal infections in the belatacept group. Switching to a belatacept‐based regimen from a CNI‐based regimen resulted in a continued trend toward improved renal function at 2 years after switching.

Prevalence and immunohistochemical findings of subclinical kidney allograft rejection and its association with graft outcome

Abstract:  Subclinical acute rejection (SAR) occurs in about 30% of stable renal transplant patients and may be a risk factor for a poor allograft outcome. In the present study, the prevalence and clinical features of subclinical rejection, and the expression of immune activation markers in surveillance graft biopsies were assessed and correlated with late graft outcomes. Protocol biopsies were obtained at 2 and 12 months post‐transplant in 32 and 26 patients, respectively, with stable renal function. The Banff 1997 criteria were used for histological diagnosis. Graft function and survival and proteinuria were assessed during the 36 months of follow‐up. Immunohistochemical evaluation of cell subpopulations and immunoactivation markers were performed on protocol biopsies. The prevalence of SAR at 2 months and of chronic allograft nephropathy (CAN) at 12 months in representative biopsies was 55 and 50%, respectively. Patients with SAR presented mononuclear cell infiltration with an increased expression of CD3, CD4, CD68, IL‐2R and granzyme B. Kidney graft function was significantly worse in patients with SAR at 2 months who had chronic rejection on biopsy at 12 months, but SAR was not associated with a worse graft function, greater proteinuria or a lower graft survival in 3 yr of follow‐up. In conclusion, we found an elevated prevalence of SAR at 2 months after transplantation with an increased expression of activation markers. Although an association of SAR with poor graft outcome was not observed, our results suggest that SAR is an immunologically active process and underscore the importance of protocol biopsies in the surveillance of transplanted kidneys.

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.

Flaxseed oil supplementation decreases C-reactive protein levels in chronic hemodialysis patients

Malnutrition and chronic inflammation in dialysis patients negatively impact their survival prognosis, and nutrients, such as omega-3 oils, are postulated to reduce proinflammatory response. In this randomized, double-blind, multicenter, placebo-controlled trial, we investigated the effects of flaxseed oil (FO) on the inflammatory state of patients with chronic renal failure undergoing renal replacement therapy with hemodialysis (HD). We hypothesized that FO supplementation lowers C-reactive protein (CRP) levels. One hundred sixty patients with chronic renal failure who received HD therapy of 3 dialysis units over a 3-month period in South Brazil were included. The patients received blind doses of FO (1 g twice a day) and placebo (mineral oil, 1 g twice a day) for a period of 120 days. Inflammation was observed in 89 patients (61%) at the beginning of the study. There was a correlation between CRP and the body mass index (R(s) = 0.22; P = .022) and high-density lipoprotein cholesterol (R(s) = -0.23; P = .032), and the CRP levels decreased significantly over time in the group that received FO compared with the control group (P < .001). During the study period, 33.3% of the FO group changed from an inflamed to a not-inflamed category, whereas only 16.9% changed in the mineral oil group (P = .04). We conclude that the administration of FO decreases the CRP levels and that inflammation in HD patients appears to be correlated to their body mass index and reduced high-density lipoprotein cholesterol levels. Studies with a larger number of patients and over a longer duration are necessary to corroborate these findings.