Identification of a serum and urine extracellular vesicle signature predicting renal outcome after kidney transplant

Extracellular vesicles: Illuminating renal pathophysiology and therapeutic frontiers

Extracellular vesicles (EVs) are minute sacs released by cells into the extracellular milieu, harboring an array of biomolecules including proteins, nucleic acids, and lipids. Notably, a large number of studies have demonstrated the important involvement of EVs in both physiological and pathological aspects of renal function. EVs can facilitate communication between different renal cells, but it is important to recognize their dual role: they can either transmit beneficial information or lead to renal damage and worsening of existing conditions. The composition of EVs in the context of the kidneys offers valuable insights into the intricate mechanisms underlying specific renal functions or disease states. In addition, mesenchymal stem cell-derived EVs have the potential to alleviate acute and chronic kidney diseases. More importantly, the innate nanoparticle properties of EVs, coupled with their engineering potential, make them effective tools for drug delivery and therapeutic intervention. In this review, we focus on the intricate biological functions of EVs in the kidney. In addition, we explore the emerging role of EVs as diagnostic tools and innovative therapeutic agents in a range of renal diseases.

Urinary extracellular vesicles as a monitoring tool for renal damage in patients not meeting criteria for chronic kidney disease

Background

Current definition of chronic kidney disease (CKD) identifies only advanced stages, but effective management demands early detection. Urinary albumin-to-creatinine ratio (ACR) 30 mg/g is a cut-off point for CKD clinical diagnosis. Patients with lower values (normoalbuminuria) and eGFR > 60 mL/min/1.73 m2 are considered at no increased cardiorenal risk. However, higher incidence of renal function decline and cardiovascular events have been shown within the normoalbuminuria range. Novel subclinical indicators may help to identify higher-risk patients. Urinary extracellular vesicles (uEVs) are sentinels of renal function non-invasively. Here we aimed to approach the early assessment of cardiorenal risk by investigating the protein cargo of uEVs.

Methods

Hypertensive patients were classified in control group (C) with ACR < 10 mg/g, and high-normal group (HN) with ACR 10-30 mg/g. Isolated uEVs were characterized by western blotting and electron microscopy and the protein cargo was analyzed by untargeted proteomics (LC-MS/MS) in a first discovery cohort. Protein confirmation was performed in a different cohort by ExoView. Immunohistochemistry of human kidney biopsies was also performed to evaluate the potential of uEVs to reflect renal damage.

Results

HN albuminuria does not affect the uEVs concentration, size, or tetraspanin profile. Among >6200 uEVs proteins identified, 43 define a panel significantly altered in HN patients without variation in urine, mostly annotated in the tubule (39 out of 43). The tubular transporter long-chain fatty acid transport protein 2 (SLC27A2) and the apical membrane protein amnionless (AMN) confirmed their alteration in HN patients evidencing impaired tubular reabsorption. SLC27A2 showed tubular expression and significantly reduced levels in patients with diagnostic criteria for CKD.

Conclusions

Alterations in the EV-mediated molecular profile are evident before pathological ACR levels are reached. Direct quantitation of SLC27A2 and AMN in uEVs helps identifying normoalbuminuric subjects with higher cardiorenal risk in early monitoring of CKD.

Extracellular vesicles in kidney development and pediatric kidney diseases

Extracellular vesicles (EVs) are membranous cargo particles that mediate intercellular communication. They are heterogeneous in size and mechanism of release, and found in all biological fluids. Since EV content is in relation to the originating cell type and to its physiopathological conditions, EVs are under study to understand organ physiology and pathology. In addition, EV surface cargo, or corona, can be influenced by the microenvironment, leading to the concept that EV-associated molecules can represent useful biomarkers for diseases. Recent studies also focus on the use of natural, engineered, or synthetic EVs for therapeutic purposes. This review highlights the role of EVs in kidney development, pediatric kidney diseases, including inherited disorders, and kidney transplantation. Although few studies exist, they have promising results and may guide researchers in this field. Main limitations, including the influence of age on EV analyses, are also discussed.

Advancing kidney transplant outcomes: the role of urinary proteomics in graft function monitoring and rejection detection

INTRODUCTION

Kidney transplantation significantly improves the lives of those with end-stage kidney disease, offering best alternative to dialysis. However, transplant success is threatened by the acute and chronic rejection mechanisms due to complex immune responses against the new organ.

AREAS COVERED

The ongoing research into biomarkers holds promise for revolutionizing the early detection and monitoring of the graft health. Liquid biopsy techniques offer a new avenue, with several diagnostic, predictive, and prognostic biomarkers showing promise in detecting and monitoring kidney diseases and an early and chronic allograft rejection.

EXPERT OPINION

Evaluating the protein composition related to kidney transplant results could lead to identifying biomarkers that provide insights into the graft functionality. Non-invasive proteomic biomarkers can drastically enhance clinical outcomes and change the way how kidney transplants are evaluated for patients and physicians if they succeed in this transition. Hence, the advancement in proteomic technologies, leads toward a significant improvement in understanding of the protein markers and molecular mechanisms linked to the outcomes of kidney transplants. However, the road from discovery to the use of such proteins in clinical practice is long, with a need for continuous validation and beyond the singular research team with comprehensive infrastructure and across research groups collaboration.

Characteristic changes in blood routine and peripheral blood lymphocyte subpopulations in recipients of different types of rejection

OBJECTIVES

Rejection remains the most important factor limiting the survival of transplanted kidneys. Although a pathological biopsy of the transplanted kidney is the gold standard for diagnosing rejection, its limitations prevent it from being used as a routine monitoring method. Recently, peripheral blood lymphocyte subpopulation testing has become an important means of assessing the body's immune system, however, its application value and strategy in the field of kidney transplantation need further exploration. Additionally, the development and utilization of routine test parameters are also important methods for exploring diagnostic strategies and predictive models for kidney transplant diseases. This study aims to explore the correlation between peripheral blood lymphocyte subpopulations and T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR), as well as their diagnostic value, in conjunction with routine blood tests.

METHODS

A total of 154 kidney transplant recipients, who met the inclusion and exclusion criteria and were treated at the Second Xiangya Hospital of Central South University from January to December, 2021, were selected as the study subjects. They were assigned into a stable group, a TCMR group, and an ABMR group, based on the occurrence and type of rejection. The basic and clinical data of these recipients were retrospectively analyzed and compared among the 3 groups. The transplant kidney function, routine blood tests, and peripheral blood lymphocyte subpopulation data of the TCMR group and the ABMR group before rejection treatment were compared with those of the stable group.

RESULTS

The stable, TCMR group, and ABMR group showed no statistically significant differences in immunosuppressive maintenance regimens or sources of transplanted kidneys (all P>0.05). However, the post-transplant duration was significantly longer in the ABMR group compared with the stable group (P<0.001) and the TCMR group (P<0.05). Regarding kidney function, serum creatinine levels in the ABMR group were higher than in the stable group and the TCMR group (both P<0.01), with the TCMR group also showing higher levels than the stable group (P<0.01). Both TCMR and ABMR groups had significantly higher blood urea nitrogen levels than the stable group (P<0.01), with no statistically significant difference between TCMR and ABMR groups (P>0.05). The estimated glomerular filtration rate (eGFR) was lower in both TCMR and ABMR groups compared with the stable group (both P<0.01). In routine blood tests, the ABMR group had lower hemoglobin, red blood cell count, and platelet count than the stable group (all P<0.05). The TCMR group had higher neutrophil percentage (P<0.05) and count (P<0.05) than the stable group, and the ABMR group had a higher neutrophil percentage than the stable group (P<0.05). The eosinophil percentage and count in the TCMR group were lower than in the stable and ABMR groups (all P<0.05). Both TCMR and ABMR groups had lower basophil percentage and count, as well as lower lymphocyte percentage and count, compared with the stable group (all P<0.05). There were no significant differences in monocyte percentage and count among the 3 groups (all P>0.05). In lymphocyte subpopulations, the TCMR and ABMR groups had lower counts of CD45+ cells and T cells compared with the stable group (all P<0.05). The TCMR group also had lower counts of CD4+ T cells, NK cells, and B cells than the stable group (all P<0.05). There were no significant differences in the T cell percentage, CD4+ T cell percentage, CD8+ T cell percentage and their counts, CD4+/CD8+ T cell ratio, NK cell percentage, and B cell percentage among the stable, TCMR, and ABMR groups (all P>0.05).

CONCLUSIONS

The occurrence of rejection leads to impaired transplant kidney function, accompanied by characteristic changes in some parameters of routine blood tests and peripheral blood lymphocyte subpopulations in kidney transplant recipients. The different characteristics of changes in some parameters of routine blood tests and peripheral blood lymphocyte subpopulations during TCMR and ABMR may help predict and diagnose rejection and differentiate between TCMR and ABMR.

Emerging roles of prominin-1 (CD133) in the dynamics of plasma membrane architecture and cell signaling pathways in health and disease

Prominin-1 (CD133) is a cholesterol-binding membrane glycoprotein selectively associated with highly curved and prominent membrane structures. It is widely recognized as an antigenic marker of stem cells and cancer stem cells and is frequently used to isolate them from biological and clinical samples. Recent progress in understanding various aspects of CD133 biology in different cell types has revealed the involvement of CD133 in the architecture and dynamics of plasma membrane protrusions, such as microvilli and cilia, including the release of extracellular vesicles, as well as in various signaling pathways, which may be regulated in part by posttranslational modifications of CD133 and its interactions with a variety of proteins and lipids. Hence, CD133 appears to be a master regulator of cell signaling as its engagement in PI3K/Akt, Src-FAK, Wnt/β-catenin, TGF-β/Smad and MAPK/ERK pathways may explain its broad action in many cellular processes, including cell proliferation, differentiation, and migration or intercellular communication. Here, we summarize early studies on CD133, as they are essential to grasp its novel features, and describe recent evidence demonstrating that this unique molecule is involved in membrane dynamics and molecular signaling that affects various facets of tissue homeostasis and cancer development. We hope this review will provide an informative resource for future efforts to elucidate the details of CD133's molecular function in health and disease.

Engineered Extracellular Vesicles in Chronic Kidney Diseases: A Comprehensive Review

Chronic kidney diseases (CKD) present a formidable global health challenge, characterized by a deficiency of effective treatment options. Extracellular vesicles (EVs), recognized as multifunctional drug delivery systems in biomedicine, have gained accumulative interest. Specifically, engineered EVs have emerged as a promising therapeutic approach for targeted drug delivery, potentially addressing the complexities of CKD management. In this review, we systematically dissect EVs, elucidating their classification, biogenesis, composition, and cargo molecules. Furthermore, we explore techniques for EV engineering and strategies for their precise renal delivery, focusing on cargo loading and transportation, providing a comprehensive perspective. Moreover, this review also discusses and summarizes the diverse therapeutic applications of engineered EVs in CKD, emphasizing their anti-inflammatory, immunomodulatory, renoprotective, and tissue-regenerating effects. It critically evaluates the challenges and limitations in translating EV therapies from laboratory settings to clinical applications, while outlining future prospects and emerging trends.

The application of nanotechnology in kidney transplantation

Kidney transplantation is a crucial treatment option for end-stage renal disease patients, but challenges related to graft function, rejection and immunosuppressant side effects persist. This review highlights the potential of nanotechnology in addressing these challenges. Nanotechnology offers innovative solutions to enhance organ preservation, evaluate graft function, mitigate ischemia-reperfusion injury and improve drug delivery for immunosuppressants. The integration of nanotechnology holds promise for improving outcomes in kidney transplantation.

Whispers in the Blood: Leveraging MicroRNAs for Unveiling Autologous Blood Doping in Athletes

The prevalence of autologous blood transfusions (ABTs) presents a formidable challenge in maintaining fair competition in sports, as it significantly enhances hemoglobin mass and oxygen capacity. In recognizing ABT as a prohibited form of doping, the World Anti-Doping Agency (WADA) mandates stringent detection methodologies. While current methods effectively identify homologous erythrocyte transfusions, a critical gap persists in detecting autologous transfusions. The gold standard practice of longitudinally monitoring hematological markers exhibits promise but is encumbered by limitations. Despite its potential, instances of blood doping often go undetected due to the absence of definitive verification processes. Moreover, some cases remain unpenalized due to conservative athlete-sanctioning approaches. This gap underscores the imperative need for a more reliable and comprehensive detection method capable of unequivocally differentiating autologous transfusions, addressing the challenges faced in accurately identifying such prohibited practices. The development of an advanced detection methodology is crucial to uphold the integrity of anti-doping measures, effectively identifying and penalizing instances of autologous blood transfusion. This, in turn, safeguards the fairness and equality essential to competitive sports. Our review tackles this critical gap by harnessing the potential of microRNAs in ABT doping detection. We aim to summarize alterations in the total microRNA profiles of erythrocyte concentrates during storage and explore the viability of observing these changes post-transfusion. This innovative approach opens avenues for anti-doping technologies and commercialization, positioning it as a cornerstone in the ongoing fight against doping in sports and beyond. The significance of developing a robust detection method cannot be overstated, as it ensures the credibility of anti-doping efforts and promotes a level playing field for all athletes.

Exploring the role of urinary extracellular vesicles in kidney physiology, aging, and disease progression

Extracellular vesicles (EVs), membranous vesicles present in all body fluids, are considered important messengers, carrying their information over long distance and modulating the gene expression profile of recipient cells. EVs collected in urine (uEVs) are mainly originated from the apical part of urogenital tract, following the urine flow. Moreover, bacterial-derived EVs are present within urine and may reflect the composition of microbiota. Consolidated evidence has established the involvement of uEVs in renal physiology, being responsible for glomerular and tubular cross talk and among different tubular segments. uEVs may also be involved in other physiological functions such as modulation of innate immunity, coagulation, or metabolic activities. Furthermore, it has been recently remonstrated that age, sex, endurance excise, and lifestyle may influence uEV composition and release, modifying their cargo. On the other hand, uEVs appear modulators of different urogenital pathological conditions, triggering disease progression. uEVs sustain fibrosis and inflammation processes, both involved in acute and chronic kidney diseases, aging, and stone formation. The molecular signature of uEVs collected from diseased patients can be of interest for understanding kidney physiopathology and for identifying diagnostic and prognostic biomarkers.

Rapid purification and multiparametric characterization of circulating small extracellular vesicles utilizing a label-free lab-on-a-chip device

Nano-scale extracellular vesicles are lipid-bilayer delimited particles that are naturally secreted by all cells and have emerged as valuable biomarkers for a wide range of diseases. Efficient isolation of small extracellular vesicles while maintaining yield and purity is crucial to harvest their potential in diagnostic, prognostic, and therapeutic applications. Most conventional methods of isolation suffer from significant shortcomings, including low purity or yield, long duration, need for large sample volumes, specialized equipment, trained personnel, and high costs. To address some of these challenges, our group has reported a novel insulator-based dielectrophoretic device for rapid isolation of small extracellular vesicles from biofluids and cell culture media based on their size and dielectric properties. In this study, we report a comprehensive characterization of small extracellular vesicles isolated from cancer-patients' biofluids at a twofold enrichment using the device. The three-fold characterization that was performed using conventional flow cytometry, advanced imaging flow cytometry, and microRNA sequencing indicated high yield and purity of the isolated small extracellular vesicles. The device thus offers an efficient platform for rapid isolation while maintaining biomolecular integrity.

Extracellular Vesicles as Source of Biomarkers in Glomerulonephritis

Kidney disease is a global health and healthcare burden. Glomerulonephritis (Gn), both primary and secondary, is generally characterized by an inflammatory glomerular injury and may lead to end-stage renal disease. Kidney biopsy is fundamental to the diagnosis; however, kidney biopsy presents some concerns that may partly hamper the clinical process. Therefore, more accurate diagnostic tools are needed. Extracellular vesicles (EVs) are membranous vesicles released by cells and found in bodily fluids, including urine. EVs mediate intercellular signaling both in health and disease. EVs can have both harmful and cytoprotective effects in kidney diseases, especially Gn. Previous findings reported that the specific cargo of urinary EV contains an aerobic metabolic ability that may either restore the recipient cell metabolism or cause oxidative stress production. Here, we provide an overview of the most recent proteomic findings on the role of EVs in several aspects of glomerulopathies, with a focus on this metabolic and redox potential. Future studies may elucidate how the ability of EVs to interfere with aerobic metabolism and redox status can shed light on aspects of Gn etiology which have remained elusive so far.

Physiopathological role of extracellular vesicles in alloimmunity and kidney transplantation and their use as biomarkers

Antibody-mediated rejection is the leading cause of kidney graft dysfunction. The process of diagnosing it requires the performance of an invasive biopsy and subsequent histological examination. Early and sensitive biomarkers of graft damage and alloimmunity are needed to identify graft injury and eventually limit the need for a kidney biopsy. Moreover, other scenarios such as delayed graft function or interstitial fibrosis and tubular atrophy face the same problem. In recent years, interest has grown around extracellular vesicles, specifically exosomes actively secreted by immune cells, which are intercellular communicators and have shown biological significance. This review presents their potential as biomarkers in kidney transplantation and alloimmunity.

Exploring urinary extracellular vesicles for organ transplant monitoring: A comprehensive study for detection of allograft dysfunction using immune-specific markers

BACKGROUND

Allograft dysfunction (AGD) is a common complication following solid organ transplantation (SOT). This study leverages the potential of urinary extracellular vesicles (UEVs) for the non-invasive detection of AGD.

AIM

We aimed to assess the diagnostic value of T-cell and B-cell markers characteristic of T-cell-mediated and antibody-mediated rejection in UEV-mRNA using renal transplantation as a model.

MATERIALS AND METHODS

UEVs were isolated from 123 participants, spanning healthy controls, functional transplant recipients, and biopsy-proven AGD patients. T-cell and B-cell marker mRNA expressions were evaluated using RT-qPCR.

RESULTS

We observed significant differences in marker expression between healthy controls and AGD patients. ROC analysis revealed an AUC of 0.80 for T-cell markers, 0.98 for B-cell markers, and 0.94 for combined markers. T-cell markers achieved 81.3 % sensitivity, 80 % specificity, and 80.4 % efficiency. A triad of T-cell markers (PRF1, OX40, and CD3e) increased sensitivity to 87.5 % and efficiency to 82.1 %. B-cell markers (CD20, CXCL3, CD46, and CF3) delivered 100 % sensitivity and 97.5 % specificity. The combined gene signature of T-cell and B-cell markers offered 93.8 % sensitivity and 95 % specificity.

CONCLUSION

Our findings underscore the diagnostic potential of UEV-derived mRNA markers for T-cells and B-cells in AGD, suggesting a promising non-invasive strategy for monitoring graft health.

Peripheral blood cellular profile at pre-lymphodepletion is associated with CD19-targeted CAR-T cell-associated neurotoxicity

Background

Infusion of second generation autologous CD19-targeted chimeric antigen receptor (CAR) T cells in patients with R/R relapsed/refractory B-cell lymphoma (BCL) is affected by inflammatory complications, such as Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS). Current literature suggests that the immune profile prior to CAR-T infusion modifies the chance to develop ICANS.

Methods

This is a monocenter prospective study on 53 patients receiving approved CAR T-cell products (29 axi-cel, 24 tisa-cel) for R/R-BCL. Clinical, biochemical, and hematological variables were analyzed at the time of pre-lymphodepletion (pre-LD). In a subset of 21 patients whose fresh peripheral blood sample was available, we performed cytofluorimetric analysis of leukocytes and extracellular vesicles (EVs). Moreover, we assessed a panel of soluble plasma biomarkers (IL-6/IL-10/GDF-15/IL-15/CXCL9/NfL) and microRNAs (miR-146a-5p, miR-21-5p, miR-126-3p, miR-150-5p) which are associated with senescence and inflammation.

Results

Multivariate analysis at the pre-LD time-point in the entire cohort (n=53) showed that a lower percentage of CD3⁺CD8⁺ lymphocytes (38.6% vs 46.8%, OR=0.937 [95% CI: 0.882-0.996], p=0.035) and higher levels of serum C-reactive protein (CRP, 4.52 mg/dl vs 1.00 mg/dl, OR=7.133 [95% CI: 1.796-28], p=0.005) are associated with ICANS. In the pre-LD samples of 21 patients, a significant increase in the percentage of CD8⁺CD45RA⁺CD57⁺ senescent cells (median % value: 16.50% vs 9.10%, p=0.009) and monocytic-myeloid derived suppressor cells (M-MDSC, median % value: 4.4 vs 1.8, p=0.020) was found in ICANS patients. These latter also showed increased levels of EVs carrying CD14⁺ and CD45⁺ myeloid markers, of the myeloid chemokine CXCL-9, as well of the MDSC-secreted cytokine IL-10. Notably, the serum levels of circulating neurofilament light chain, a marker of neuroaxonal injury, were positively correlated with the levels of senescent CD8⁺ T cells, M-MDSC, IL-10 and CXCL-9. No variation in the levels of the selected miRNAs was observed between ICANS and no-ICANS patients.

Discussion

Our data support the notion that pre-CAR-T systemic inflammation is associated with ICANS. Higher proportion of senescence CD8⁺ T cells and M-MDSC correlate with early signs of neuroaxonal injury at pre-LD time-point, suggesting that ICANS may be the final event of a process that begins before CAR-T infusion, consequence to patient clinical history.