Urinary extracellular vesicles as source of biomarkers in kidney diseases.

Most cells physiologically release vesicles as way of intercellular communication. The so-called Extracellular Vesicles (EVs) include exosomes, ectosomes, and apoptotic bodies, which basically differ in their composition and subcellular origin. Specifically, EVs found in urine reflect the state of the urinary system, from podocytes to renal-tubular cells, thus making them an excellent source of samples for the study of kidney physiology and pathology. Several groups have focused on defining biomarkers of kidney-related disorders, from graft rejection to metabolic syndromes. So far, the lack of a standard protocol for EVs isolation precludes the possibility of a proper comparison among the different biomarkers proposed in the literature, stressing the need for validation of these biomarkers not only in larger cohorts of patients but also considering the different methods for EVs isolation. In this review, we aim to gather the current knowledge about EVs-related biomarkers in kidney diseases, with a special emphasis in the methods used to date for EVs enrichment, and discussing the need for more specific protocols of EV isolation in clinical practice.

Size-exclusion chromatography-based enrichment of extracellular vesicles from urine samples.

Renal biopsy is the gold-standard procedure to diagnose most of renal pathologies. However, this invasive method is of limited repeatability and often describes an irreversible renal damage. Urine is an easily accessible fluid and urinary extracellular vesicles (EVs) may be ideal to describe new biomarkers associated with renal pathologies. Several methods to enrich EVs have been described. Most of them contain a mixture of proteins, lipoproteins and cell debris that may be masking relevant biomarkers. Here, we evaluated size-exclusion chromatography (SEC) as a suitable method to isolate urinary EVs. Following a conventional centrifugation to eliminate cell debris and apoptotic bodies, urine samples were concentrated using ultrafiltration and loaded on a SEC column. Collected fractions were analysed by protein content and flow cytometry to determine the presence of tetraspanin markers (CD63 and CD9). The highest tetraspanin content was routinely detected in fractions well before the bulk of proteins eluted. These tetraspanin-peak fractions were analysed by cryo-electron microscopy (cryo-EM) and nanoparticle tracking analysis revealing the presence of EVs.When analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, tetraspanin-peak fractions from urine concentrated samples contained multiple bands but the main urine proteins (such as Tamm-Horsfall protein) were absent. Furthermore, a preliminary proteomic study of these fractions revealed the presence of EV-related proteins, suggesting their enrichment in concentrated samples. In addition, RNA profiling also showed the presence of vesicular small RNA species.To summarize, our results demonstrated that concentrated urine followed by SEC is a suitable option to isolate EVs with low presence of soluble contaminants. This methodology could permit more accurate analyses of EV-related biomarkers when further characterized by -omics technologies compared with other approaches.

Neoplasm in kidney graft. Analysis of the cause of the tumour and treatment options.

Kidney transplant is the treatment of choice for chronic kidney disease. Cardiovascular disease, infections, and postransplant de novo neoplasms are the main causes of death in transplant patients. The most frequent kind of post kidney transplant neoplasms are lymphoproliferative processes and cutaneous neoplasms. Another type of neoplasm, that of kidney tumours, also represents approximately 3% of all neoplasms in transplant patients. A review of the kidney transplants from our unit performed between July 1985 and October 2012 which presented a mass in the kidney graft was carried out, confirming the diagnosis by taking a biopsy of the mass. In all the cases, the underlying pathology, kidney function and immunosuppressive treatment were analysed. This article aims to give importance to monitoring and management of the appearance of possible tumour masses in kidney transplants.

Tolerance in organ transplantation: from conventional immunosuppression to extracellular vesicles.

Organ transplantation is often the unique solution for organ failure. However, rejection is still an unsolved problem. Although acute rejection is well controlled, the chronic use of immunosuppressive drugs for allograft acceptance causes numerous side effects in the recipient and do not prevent chronic allograft dysfunction. Different alternative therapies have been proposed to replace the classical treatment for allograft rejection. The alternative therapies are mainly based in pre-infusions of different types of regulatory cells, including DCs, MSCs, and Tregs. Nevertheless, these approaches lack full efficiency and have many problems related to availability and applicability. In this context, the use of extracellular vesicles, and in particular exosomes, may represent a cell-free alternative approach in inducing transplant tolerance and survival. Preliminary approaches in vitro and in vivo have demonstrated the efficient alloantigen presentation and immunomodulation abilities of exosomes, leading to alloantigen-specific tolerance and allograft acceptance in rodent models. Donor exosomes have been used alone, processed by recipient antigen-presenting cells, or administered together with suboptimal doses of immunosuppressive drugs, achieving specific allograft tolerance and infinite transplant survival. In this review, we gathered the latest exosome-based strategies for graft acceptance and discuss the tolerance mechanisms involved in organ tolerance mediated by the administration of exosomes. We will also deal with the feasibility and difficulties that arise from the application of this strategy into the clinic.

Neoplasia en el injerto renal. Análisis del origen tumoral y opciones terapéuticas / Neoplasm in kidney graft. Analysis of the cause of the tumour and treatment options

El trasplante renal es el tratamiento de elección de la enfermedad renal crónica. La enfermedad cardiovascular, las infecciones, así como las neoplasiasde novo postrasplante renal son las principales causas de mortalidad de los pacientes trasplantados. Las neoplasias más frecuentes en el postrasplante renal son los procesos linfoproliferativos y las neoplasias cutáneas. Otro tipo de neoplasias, como son los tumores renales, también representan aproximadamente el 3 % de todas las neoplasias de los trasplantados. Se ha realizado una revisión de los trasplantados renales de nuestra unidad entre julio de 1985 y octubre de 2012 que han presentado una masa a nivel del injerto renal, confirmando el diagnóstico por biopsia de la masa. Se ha analizado en todos los casos la patología de base, la función renal y el tratamiento inmunosupresor. Este artículo quiere dar importancia a la monitorización de la aparición de posibles masas tumorales en el injerto renal y su manejo (AU)

Kidney transplant is the treatment of choice for chronic kidney disease. Cardiovascular disease, infections, and postransplant de novo neoplasms are the main causes of death in transplant patients. The most frequent kind of post kidney transplant neoplasms are lymphoproliferative processes and cutaneous neoplasms. Another type of neoplasm, that of kidney tumours, also represents approximately 3% of all neoplasms in transplant patients. A review of the kidney transplants from our unit performed between July 1985 and October 2012 which presented a mass in the kidney graft was carried out, confirming the diagnosis by taking a biopsy of the mass. In all the cases, the underlying pathology, kidney function and immunosuppressive treatment were analysed. This article aims to give importance to monitoring and management of the appearance of possible tumour masses in kidney transplants (AU)

Mycophenolate mofetil-induced mouth ulcers in a kidney transplant patient: Case report and literature review / Úlceras orales secundarias a micofenolato mofetilo en un paciente trasplantado renal: caso clínico y revisión de la literatura

Mouth ulcers are a cutaneous complication that can often affect kidney transplant patients, mostly due to the effect of immunosuppressive treatment. Even so, before asserting that said complication is indeed secondary to drugs, it is very important to establish a differential diagnosis with other mouth ulcer causes, such as systemic diseases or viral infections, which are also common in these patients

Las úlceras orales son una de las complicaciones cutáneas que pueden afectar con frecuencia a los pacientes trasplantados renales, debido muchas veces al efecto del tratamiento inmunosupresor. Aun así, es importante, antes de asegurar que dicha complicación es secundaria a los fármacos, establecer el diagnóstico diferencial con otras causas de úlceras orales como pueden ser enfermedades sistémicas o infecciones virales, también frecuentes en este tipo de pacientes

The effects of hyperlipidaemia on graft and patient outcome in renal transplantation.

Hyperlipidaemia is a frequent complication after renal transplantation. As to whether total cholesterol (TC) and triglyceride levels are risk factors for cardiovascular disease and graft survival is controversial. The prevalence of hypercholesterolaemia in the transplanted population in Spain has increased over the years, going from 38.8% in 1990 to 48% in 1998. In contrast, the prevalence of hypertriglyceridaemia being approximately 20%, has not shown any significant variation. Transplant recipients with high cholesterol were characterized by increased age, lower proportion of males, higher mean body mass index, lower proportion of HCV antibodies, reduced time on dialysis and diabetes. Patients with high cholesterol were more frequently treated with cyclosporine + MMF + prednisone and less frequently treated with tacrolimus + MMF + prednisone. Hypertriglyceridaemia was more frequent in patients treated with cyclosporine + MMF + prednisone, and these patients showed significantly higher creatinine plasma levels at 1 year and were more frequently treated with lipid-lowering agents. Hypertriglyceridaemia at 3 months after transplantation is associated with worse graft survival (RR 1.078; CI 1.07-1.143; P = 0.011) and greater cardiovascular mortality (RR 1.265; CI 1.20-1.428; P = 0.0002), while treatment with statins has a protective effect on the graft survival (RR 0.64; CI 0.512-0.888; P = 0.0051). In conclusion, in the renal transplant population in Spain, hypertriglyceridaemia rather than hypercholesterolaemia, may exert a deleterious effect on graft and patient survival.

Tendinitis por levofloxacino / Tendinitis associated with levofloxacin

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Piomiositis por Nocardia asteroides en un paciente trasplantado renal / Pyomiositis by Nocardia asteroides in a patient submitted to a kidney transplantation

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