Urine-Derived Renal Epithelial Cells (URECs) from Transplanted Kidneys as a Promising Immunomodulatory Cell Population.

Kidney transplantation is a lifesaving procedure for patients with end-stage kidney disease (ESKD). Organs derived from donation after cardiac death (DCD) are constantly increasing; however, DCD often leads to ischaemia-reperfusion (IR) and Acute Kidney Injury (AKI) events. These phenomena increase kidney cell turnover to replace damaged cells, which are voided in urine. Urine-derived renal epithelial cells (URECs) are rarely present in the urine of healthy subjects, and their loss has been associated with several kidney disorders. The present study aimed to characterize the phenotype and potential applications of URECs voided after transplant. The results indicate that URECs are highly proliferating cells, expressing several kidney markers, including markers of kidney epithelial progenitor cells. Since the regulation of the immune response is crucial in organ transplantation and new immunoregulatory strategies are needed, UREC immunomodulatory properties were investigated. Co-culture with peripheral blood mononuclear cells (PBMCs) revealed that URECs reduced PBMC apoptosis, inhibited lymphocyte proliferation, increased T regulatory (Treg) cells and reduced T helper 1 (Th1) cells. URECs from transplanted patients represent a promising cell source for the investigation of regenerative processes occurring in kidneys, and for cell-therapy applications based on the regulation of the immune response.

Impact of Single Hemodialysis Treatment on immune Cell Subpopulations.

Hemodialysis (HD) is known to trigger a chronic inflammatory status, affecting the innate and acquired immune response. This study was aimed at a comparative analysis of immune cell subsets, proliferation, and apoptosis in subjects receiving chronic HD treatment with respect to a healthy control. Regardless of the dialysis filter used, we observed a reshaping of the acquired immune component both with respect to healthy patients and between the various sessions of dialysis treatment, with an impairment of CD3 cells, along with an increase in CD4 and CD8 cell populations producing pro-inflammatory factors such as IL-17 and IFN-gamma. The population of B cells, monocytes and NK cells were not impaired by the dialysis procedure. These results confirmed the high impact of the HD treatment on the patient's immune system, underlying the imbalance of T cell counterparts.

Adaptive Mechanisms of Renal Bile Acid Transporters in a Rat Model of Carbon Tetrachloride-Induced Liver Cirrhosis.

BACKGROUND: Acute kidney injury (AKI) is common in advanced liver cirrhosis, a consequence of reduced kidney perfusion due to splanchnic arterial vasodilation and intrarenal vasoconstriction. It clinically manifests as hepatorenal syndrome type 1, type 2, or as acute tubular necrosis. Beyond hemodynamic factors, an additional mechanism may be hypothesized to explain the renal dysfunction during liver cirrhosis. Recent evidence suggest that such mechanisms may be closely related to obstructive jaundice. METHODS: Given the not completely elucidated role of bile acids in kidney tissue damage, this study developed a rat model of AKI with liver cirrhosis induction by carbon tetrachloride (CCl4) inhalation for 12 weeks. Histological analyses of renal and liver biopsies were performed at sacrifice. Organic anion tubular transporter distribution and apoptosis in kidney cells were analyzed by immunohistochemistry. Circulating and urinary markers of inflammation and tubular injury were assayed in 21 treated rats over time (1, 2, 4, 8, and 12 weeks of CCl4 administration) and 5 controls. RESULTS: No renal histopathological alterations were found at sacrifice. Comparing treated rats with controls, organic anion transporters were differentially expressed and localized. High serum bile acid values were detected in cirrhotic animals, while caspase-3 staining was negative in both groups. Increased levels of serum inflammatory and urinary tubular injury biomarkers were observed during cirrhosis progression, with a peak after 4 and 8 weeks of treatment. CONCLUSIONS: These findings suggest possible adaptive tubular mechanisms for bile acid transporters in response to cirrhosis-induced AKI.

Vitamin D Effects on Bone Homeostasis and Cardiovascular System in Patients with Chronic Kidney Disease and Renal Transplant Recipients.

Poor vitamin D status is common in patients with impaired renal function and represents one main component of the complex scenario of chronic kidney disease-mineral and bone disorder (CKD-MBD). Therapeutic and dietary efforts to limit the consequences of uremia-associated vitamin D deficiency are a current hot topic for researchers and clinicians in the nephrology area. Evidence indicates that the low levels of vitamin D in patients with CKD stage above 4 (GFR < 15 mL/min) have a multifactorial origin, mainly related to uremic malnutrition, namely impaired gastrointestinal absorption, dietary restrictions (low-protein and low-phosphate diets), and proteinuria. This condition is further worsened by the compromised response of CKD patients to high-dose cholecalciferol supplementation due to the defective activation of renal hydroxylation of vitamin D. Currently, the literature lacks large and interventional studies on the so-called non-calcemic activities of vitamin D and, above all, the modulation of renal and cardiovascular functions and immune response. Here, we review the current state of the art of the benefits of supplementation with native vitamin D in various clinical settings of nephrological interest: CKD, dialysis, and renal transplant, with a special focus on the effects on bone homeostasis and cardiovascular outcomes.

Screening strategies for the diagnosis of asymptomatic Leishmania infection in dialysis patients as a model for kidney transplant candidates.

Despite being considered a tropical disease, visceral leishmaniasis (VL) caused by L. infantum is also endemic in the Mediterranean Europe and represents an increasing cause of morbidity and mortality in solid organ transplant (SOT) recipients. VL occurring in kidney transplant recipients is a severe event, often worsening the renal damage and leading to poor outcome. It is believed that most of VL cases in transplant recipients are caused by reactivation of a pre-existent, dormant leishmanial infection induced by the immunosuppressive drugs. Nevertheless, the prevalence of asymptomatic Leishmania infection in candidates to kidney transplant residing in or visiting endemic areas is unknown. As L. infantum is highly circulating in northeastern Italy, we aimed to examine the occurrence of this parasitic infection in 119 dialysis patients living in the mentioned area, 71 of whom were potential candidates to kidney transplant. By employing a combination of sensitive serological and molecular methods, we observed a prevalence of 15.9% asymptomatic Leishmania infection in the study cohort. This finding emphasizes the need of further evaluating potential screening strategies for Leishmania infection in solid organ transplant candidates residing in or visiting endemic areas.

Vitamin B Supplementation and Nutritional Intake of Methyl Donors in Patients with Chronic Kidney Disease: A Critical Review of the Impact on Epigenetic Machinery.

Cardiovascular morbidity and mortality are several-fold higher in patients with advanced chronic kidney disease (CKD) and end-stage renal disease (ESRD) than in the general population. Hyperhomocysteinemia has undoubtedly a central role in such a prominent cardiovascular burden. The levels of homocysteine are regulated by methyl donors (folate, methionine, choline, betaine), and cofactors (vitamin B6, vitamin B12,). Uremia-induced hyperhomocysteinemia has as its main targets DNA methyltransferases, and this leads to an altered epigenetic control of genes regulated through methylation. In renal patients, the epigenetic landscape is strictly correlated with the uremic phenotype and dependent on dietary intake of micronutrients, inflammation, gut microbiome, inflammatory status, oxidative stress, and lifestyle habits. All these factors are key contributors in methylome maintenance and in the modulation of gene transcription through DNA hypo- or hypermethylation in CKD. This is an overview of the epigenetic changes related to DNA methylation in patients with advanced CKD and ESRD. We explored the currently available data on the molecular dysregulations resulting from altered gene expression in uremia. Special attention was paid to the efficacy of B-vitamins supplementation and dietary intake of methyl donors on homocysteine lowering and cardiovascular protection.

Bloodstream infections and patient survival with tunneled-cuffed catheters for hemodialysis: A single-center observational study.

BACKGROUND: In hemodialysis patients, a tunneled-cuffed permanent catheter is mandatory when the arteriovenous fistula is not feasible. The major risks of the use of tunneled-cuffed permanent catheter are bloodstream infections. The aim of this study is to analyze bloodstream infections from tunneled-cuffed permanent catheter in hemodialysis patients. METHODS: An observational prospective study was carried out and 79 hemodialysis patients with tunneled-cuffed permanent catheter were enrolled. Patients were divided into those with bloodstream infections from tunneled-cuffed permanent catheter and those without. Their clinical and laboratory characteristics were compared. An original tunneled-cuffed permanent catheter lock therapy sequence was carried out combined with systemic antibiotic therapy. In case of antibiotic resistance, the tunneled-cuffed permanent catheter was removed. RESULTS: The patients affected by bloodstream infections from tunneled-cuffed permanent catheter were 16/79 (20.3%). The bloodstream infection from tunneled-cuffed permanent catheter's incidence rate was 0.52 per 1000 catheter days. Twenty-three bloodstream infections from tunneled-cuffed permanent catheter were found in 16/79 patients who used tunneled-cuffed permanent catheter. Staphylococcus aureus was the cause of bloodstream infection from tunneled-cuffed permanent catheter in 35% of the cases and Staphylococcus epidermidis in 30% of the cases. Risk factors were infection located in other organs and the presence of peripheral obstructive arterial disease. CONCLUSION: The enrolled cohort showed a reduced bloodstream infection from tunneled-cuffed permanent catheter incidence rate in comparison with the reference value (1 per 1000 catheter days). To reduce the number of bloodstream infections from tunneled-cuffed permanent catheter, hand hygiene and asepsis management of the tunneled-cuffed permanent catheter during the connection to the extracorporeal circuit and an original tunneled-cuffed permanent catheter lock therapy sequence seem to be the most efficient measures. Infections of other organs and the presence of peripheral obstructive arterial disease are the most important risk factors for bloodstream infections from tunneled-cuffed permanent catheter.

Immunological Effects of a Single Hemodialysis Treatment.

Immune disorders, involving both innate and adaptive response, are common in patients with end-stage renal disease under chronic hemodialysis. Endogenous and exogenous factors, such as uremic toxins and the extracorporeal treatment itself, alter the immune balance, leading to chronic inflammation and higher risk of cardiovascular events. Several studies have previously described the immune effects of chronic hemodialysis and the possibility to modulate inflammation through more biocompatible dialyzers and innovative techniques. On the other hand, very limited data are available on the possible immunological effects of a single hemodialysis treatment. In spite of the lacking information about the immunological reactivity related to a single session, there is evidence to indicate that mediators of innate and adaptive response, above all complement cascade and T cells, are implicated in immune system modulation during hemodialysis treatment. Expanding our understanding of these modulations represents a necessary basis to develop pro-tolerogenic strategies in specific conditions, like hemodialysis in septic patients or the last session prior to kidney transplant in candidates for receiving a graft.

Sodium Prescription in the Prevention of Intradialytic Hypotension: New Insights into an Old Concept.

BACKGROUND: Sodium prescription in patients with intradialytic hypotension remains a challenge for the attending nephrologist, as it increases dialysate conductivity in hypotension-prone patients, thereby adding to dietary sodium levels. METHODS: New sodium prescription strategies are now available, including the use of a mathematical model to compute the sodium mass to be removed during dialysis as a physiological controller. RESULTS: This review describes the sodium load of patients with end-stage renal disease on chronic hemodialysis (HD) and discusses 2 strategies to remove excess sodium in patients prone to intradialytic hypotension, namely, Profiled HD and the hemodiafiltration Aequilibrium System. CONCLUSION: The Profiled HD and Aequilibrium System trial both proved effective in counteracting intradialytic hypotension.

Fifteen-Year Analysis of Deceased Kidney Donation: A Single Transplant Center Experience in a Region of Northern Italy.

BACKGROUND The rising number of patients on waiting lists for kidney transplant and the shortage of available organs has intensified efforts to increase the number of potential donors. MATERIAL AND METHODS This study investigated changes in clinical parameters among potential deceased donors in the 15-year period between 1999 and 2013 and their impact on transplantation procedure and outcomes. A total of 1634 potential deceased donors were examined and divided into 2 groups: 707 of them identified from 1999 to 2005 (Group A), and 927 from 2006 to 2013 (Group B). RESULTS The comparison between the potential donors in Group A vs. Group B revealed an increase over time in donor age (54.6±17.2 vs. 58.8±16.3, p<0.001), a reduction in the percentage of standard donors (52.3% vs. 39.8%, p<0.001), a broader utilization of organs from expanded criteria donors, and a greater number of comorbidities, particularly cardiovascular disease and dyslipidemia. However, renal function parameters and the bioptic scores did not change significantly over the years. CONCLUSIONS These results suggest the usefulness of strategies to increase the number of potential donors suitable for organ donation, especially among elderly and marginal donors.

Identification of expanded T-cell clones by spectratyping in nonfunctioning kidney transplants.

BACKGROUND: The aim of this study was the application of complementarity-determining region-3 spectratyping analysis to determine T-cell-repertoire complexity and to detect T-cell-clone expansion, as a measure of immune response in nonfunctioning kidney transplants (group hemodialysis-transplant [HD-Tx]), nontransplanted dialysis patients (group hemodialysis [HD]), and normal subjects as controls (group C). PATIENTS AND METHODS: Analysis of T-cell receptor (TCR) diversity by spectratyping was applied to peripheral blood samples collected from 21 subjects: eight in group HD-Tx, seven in group HD, and six in group C. RESULTS: Considering the extent of the skew in TCR variable region repertoires as a measure of clonal T cells, we found that the number of altered spectra showed a progressive increase from normal subjects to dialysis patients and to nonfunctioning kidney transplants, respectively. Healthy subjects had the lowest number of altered spectra, and patients with nonfunctioning kidney transplants the highest. Differences were significant for group HD-Tx vs group C (P=0.017) and group HD vs group C (P=0.015), but not between nonfunctioning kidney-transplant recipients and dialysis patients (group HD-Tx vs group HD). CONCLUSION: Although dialysis appears to be a weaker trigger for clonal expansion of T cells, our data suggest that the utilization of complementarity-determining region-3 spectratyping analysis of the TCR repertoire might be useful to monitor specific immunoactivation in patients before and after kidney transplantation.

Cardiovascular disease in kidney transplant recipients: the prognostic value of inflammatory cytokine genotypes.

BACKGROUND: Cardiovascular disease (CVD) represents the main cause of morbidity and mortality after renal transplantation. In view of the modern paradigm of atherosclerosis as an inflammatory disease, this study investigated the impact of inflammatory cytokine polymorphisms on posttransplant CVD. METHODS: The association between cytokine polymorphisms and CVD was assessed in a case-control study to identify the differences in genotype distributions between kidney allografts with or without posttransplant CVD. To validate our results in two independent groups, we divided a cohort of 798 renal transplant recipients according to geographic area: an evaluation cohort of 478 patients from Emilia-Romagna and a validation cohort of 320 patients from the rest of Italy. Tumor necrosis factor (TNF)-alpha, transforming growth factor-beta1, interleukin (IL)-10, IL-6, interferon-gamma, and IL-8 polymorphisms were analyzed, and thereafter, the cytokine production genotype was assigned. RESULTS: In the evaluation cohort, the patients in the CVD and no-CVD groups differed significantly in TNF-alpha and IL-10 genotype frequencies. Using multivariate analyses to test the association with CVD, the TNF-alpha high-producer genotype was associated with a significantly increased cardiovascular risk (odds ratio [OR]=4.41, 95% confidence interval (CI)=2.53-7.67). Conversely, the IL-10 high-producer genotype resulted protective against CVD (OR=0.07, 95% CI=0.02-0.29). These findings were confirmed in the validation cohort where the carriers of the TNF-alpha high-producer genotype proved to be at 2.45-fold increased cardiovascular risk (OR=2.45, 95% CI=1.29-4.63), whereas the IL-10 high-producer genotype was associated with a 0.08-fold reduced risk (OR=0.08, 95% CI=0.02-0.36). CONCLUSIONS: This work suggests a prognostic value of TNF-alpha and IL-10 genotypes, which might represent cardiovascular risk markers in renal transplant.

An in vivo autotransplant model of renal preservation: cold storage versus machine perfusion in the prevention of ischemia/reperfusion injury.

There is increasing proof that organ preservation by machine perfusion is able to limit ischemia/reperfusion injury in kidney transplantation. This study was designed to compare the efficiency in hypothermic organ preservation by machine perfusion or cold storage in an animal model of kidney autotransplantation. Twelve pigs underwent left nephrectomy after warm ischemic time; the organs were preserved in machine perfusion (n = 6) or cold storage (n = 6) and then autotransplanted with immediate contralateral nephrectomy. The following parameters were compared between the two groups of animals: hematological and urine indexes of renal function, blood/gas analysis values, histological features, tissue adenosine-5'-triphosphate (ATP) content, perforin gene expression in kidney biopsies, and organ weight changes were compared before and after preservation. The amount of cellular ATP was significantly higher in organs preserved by machine perfusion; moreover, the study of apoptosis induction revealed an enhanced perforin expression in the kidneys, which underwent simple hypothermic preservation compared to the machine-preserved ones. Organ weight was significantly decreased after cold storage, but it remained quite stable for machine-perfused kidneys. The present model seems to suggest that organ preservation by hypothermic machine perfusion is able to better control cellular impairment in comparison with cold storage.