Kidney tissue proteomics reveals regucalcin downregulation in response to diabetic nephropathy with reflection in urinary exosomes

Future embracing: exosomes driving a revolutionary approach to the diagnosis and treatment of idiopathic membranous nephropathy

Membranous nephropathy (MN) is a leading cause of nephrotic syndrome in adults and is associated with high rates of end-stage renal disease. Early detection and precise interventions are crucial for improving patient prognosis and quality of life. However, the current diagnosis primarily relies on renal biopsies and traditional biomarkers, which have limitations. Additionally, targeted therapeutic strategies are lacking. Exosomes, small vesicles that facilitate intercellular communication, have emerged as potential noninvasive diagnostic markers due to their stability, diverse cargo, and rapid detectability. They also hold promise as carriers for gene and drug delivery, presenting innovative opportunities in renal disease prognosis and treatment. However, research on exosomes in the context of idiopathic membranous nephropathy (IMN) remains limited, with a focus on exploring urinary exosomes as IMN markers. In this review, we summarize the current status of MN diagnosis and treatment, highlight the fundamental characteristics of exosomes, and discuss recent advancements in their application to IMN diagnosis and therapy. We provide insights into the clinical prospects of exosomes in IMN and acknowledge potential challenges. This article aims to offer forward-looking insights into the future of exosome-mediated IMN diagnosis and treatment, indicating a revolutionary transformation in this field.

Urine beyond electrolytes: diagnosis through extracellular vesicles

BACKGROUND AND OBJECTIVE

Extracellular vesicles (EV) reflect the pathophysiological state of their cells of origin and are a reservoir of renal information accessible in urine. When biopsy is not an option, EV present themselves as sentinels of function and damage, providing a non-invasive approach. However, the analysis of EV in urine requires prior isolation, which slows down and hinders transition into clinical practice. The aim of this study is to show the applicability of the "single particle interferometric reflectance imaging sensor" (SP-IRIS) technology through the ExoView® platform for the direct analysis of urine EV and proteins involved in renal function.

MATERIALS AND METHODS

The ExoView® technology enables the quantification and phenotyping of EV present in urine and the quantification of their membrane and internal proteins. We have applied this technology to the quantification of urinary EV and their proteins with renal tubular expression, amnionless (AMN) and secreted frizzled-related protein 1 (SFRP1), using only 5 μl of urine. Tubular expression was confirmed by immunohistochemistry.

RESULTS

The mean size of the EV analysed was 59 ± 16 nm for those captured by tetraspanin CD63, 61 ± 16 nm for those captured by tetraspanin CD81, and 59 ± 10 for tetraspanin CD9, with CD63 being the majority EV subpopulation in urine (48.92%). The distribution of AMN and SFRP1 in the three capture tetraspanins turned out to be similar for both proteins, being expressed mainly in CD63 (48.23% for AMN and 52.1% for SFRP1).

CONCLUSIONS

This work demonstrates the applicability and advantages of the ExoView® technique for the direct analysis of urine EV and their protein content in relation to the renal tubule. The use of minimum volumes, 5 μl, and the total analysis time not exceeding three hours facilitate the transition of EV into daily clinical practice as sources of diagnostic information.

Extracellular Vesicles: Investigating the Pathophysiology of Diabetes-Associated Hypertension and Diabetic Nephropathy

Extracellular vesicles (EVs) include exosomes, microvesicles, and apoptotic bodies. EVs are released by all cell types and are found in biological fluids including plasma and urine. Urinary extracellular vesicles (uEVs) are a mixed population of EVs that comprise small EVs that are filtered and excreted, EVs secreted by tubular epithelial cells, and EVs released from the bladder, urethra, and prostate. The packaged cargo within uEVs includes bioactive molecules such as metabolites, lipids, proteins, mRNAs, and miRNAs. These molecules are involved in intercellular communication, elicit changes in intracellular signaling pathways, and play a role in the pathogenesis of various diseases including diabetes-associated hypertension and diabetic nephropathy. uEVs represent a rich source of biomarkers, prognosis markers, and can be loaded with small-molecule drugs as a vehicle for delivery.

Nanoparticle Tracking Analysis of Urinary Extracellular Vesicle Proteins as a New Challenge in Laboratory Medicine

Urinary extracellular vesicle (uEV) proteins may be used as specific markers of kidney damage in various pathophysiological conditions. The nanoparticle-tracking analysis (NTA) appears to be the most useful method for the analysis of uEVs due to its ability to analyze particles below 300 nm. The NTA method has been used to measure the size and concentration of uEVs and also allows for a deeper analysis of uEVs based on their protein composition using fluorescence measurements. However, despite much interest in the clinical application of uEVs, their analysis using the NTA method is poorly described and requires meticulous sample preparation, experimental adjustment of instrument settings, and above all, an understanding of the limitations of the method. In the present work, we demonstrate the usefulness of an NTA. We also present problems encountered during analysis with possible solutions: the choice of sample dilution, the method of the presentation and comparison of results, photobleaching, and the adjustment of instrument settings for a specific analysis. We show that the NTA method appears to be a promising method for the determination of uEVs. However, it is important to be aware of potential problems that may affect the results.

Experimental Models to Study Diabetes Mellitus and Its Complications: Limitations and New Opportunities

Preclinical biomedical models are a fundamental tool to improve the knowledge and management of diseases, particularly in diabetes mellitus (DM) since, currently, the pathophysiological and molecular mechanisms involved in its development are not fully clarified, and there is no treatment to cure DM. This review will focus on the features, advantages and limitations of some of the most used DM models in rats, such as the spontaneous models: Bio-Breeding Diabetes-Prone (BB-DP) and LEW.1AR1-iddm, as representative models of type 1 DM (DM-1); the Zucker diabetic fatty (ZDF) and Goto-kakizaki (GK) rats, as representative models of type 2 DM (DM-2); and other models induced by surgical, dietary and pharmacological-alloxan and streptozotocin-procedures. Given the variety of DM models in rats, as well as the non-uniformity in the protocols and the absence of all the manifestation of the long-term multifactorial complications of DM in humans, the researchers must choose the one that best suits the final objectives of the study. These circumstances, added to the fact that most of the experimental research in the literature is focused on the study of the early phase of DM, makes it necessary to develop long-term studies closer to DM in humans. In this review, a recently published rat DM model induced by streptozotocin injection with chronic exogenous administration of insulin to reduce hyperglycaemia has also been included in an attempt to mimic the chronic phase of DM in humans.

Urinary Exosomes: A Promising Biomarker for Disease Diagnosis

Exosomes are nanoscale vesicles derived from endocytosis, formed by fusion of multivesicular bodies with membranes and secreted into the extracellular matrix or body fluids. Many studies have shown that exosomes can be present in a variety of biological fluids, such as plasma, urine, saliva, amniotic fluid, ascites, and sweat, and most types of cells can secrete exosomes. Exosomes play an important role in many aspects of human development, including immunity, cardiovascular diseases, neurodegenerative diseases, and neoplasia. Urine can be an alternative to blood or tissue samples as a potential source of disease biomarkers because of its simple, noninvasive, sufficient, and stable characteristics. Therefore, urinary exosomes have valuable potential for early screening, monitoring disease progression, prognosis, and treatment. The method for isolating urinary exosomes has been perfected, and exosome proteomics is widely used. Therefore, we review the potential use of urinary exosomes for disease diagnosis and summarize the related literature.

Extracellular Vesicles: The Future of Diagnosis in Solid Organ Transplantation?

Solid organ transplantation (SOT) is a life-saving treatment for end-stage organ failure, but it comes with several challenges, the most important of which is the existing gap between the need for transplants and organ availability. One of the main concerns in this regard is the lack of accurate non-invasive biomarkers to monitor the status of a transplanted organ. Extracellular vesicles (EVs) have recently emerged as a promising source of biomarkers for various diseases. In the context of SOT, EVs have been shown to be involved in the communication between donor and recipient cells and may carry valuable information about the function of an allograft. This has led to an increasing interest in exploring the use of EVs for the preoperative assessment of organs, early postoperative monitoring of graft function, or the diagnosis of rejection, infection, ischemia-reperfusion injury, or drug toxicity. In this review, we summarize recent evidence on the use of EVs as biomarkers for these conditions and discuss their applicability in the clinical setting.

Extracellular Vesicles in Kidney Diseases: Moving Forward

Extracellular vesicles (EVs) are evolving as novel cell mediators, biomarkers, and therapeutic targets in kidney health and disease. They are naturally derived from cells both within and outside the kidney and carry cargo which mirrors the state of the parent cell. Thus, they are potentially more sensitive and disease-specific as biomarkers and messengers in various kidney diseases. Beside their role as novel communicators within the nephron, they likely communicate between different organs affected by various kidney diseases. Study of urinary EVs (uEVs) can help to fill current knowledge gaps in kidney diseases. However, separation and characterization are challenged by their heterogeneity in size, shape, and cargo. Fortunately, more sensitive and direct EV measuring tools are in development. Many clinical syndromes in nephrology from acute to chronic kidney and glomerular to tubular diseases have been studied. Yet, validation of biomarkers in larger cohorts is warranted and simpler tools are needed. Translation from in vitro to in vivo studies is also urgently needed. The therapeutic role of uEVs in kidney diseases has been studied extensively in rodent models of AKI. On the basis of the current exponential growth of EV research, the field of EV diagnostics and therapeutics is moving forward.

Urinary Extracellular Vesicles in Chronic Kidney Disease: From Bench to Bedside?

Extracellular vesicles are a diverse group of particles that include exosomes, microvesicles, and apoptotic bodies and are defined by size, composition, site of origin, and density. They incorporate various bioactive molecules from their cell of origin during formation, such as soluble proteins, membrane receptors, nucleic acids (mRNAs and miRNAs), and lipids, which can then be transferred to target cells. Extracellular vesicles/exosomes have been extensively studied as a critical factor in pathophysiological processes of human diseases. Urinary extracellular vesicles could be a promising liquid biopsy for determining the pattern and/or severity of kidney histologic injury. The signature of urinary extracellular vesicles may pave the way for noninvasive methods to supplement existing testing methods for diagnosing kidney diseases. We discuss the potential role of urinary extracellular vesicles in various chronic kidney diseases in this review, highlighting open questions and discussing the potential for future research.

Molecular profiling of urinary extracellular vesicles in chronic kidney disease and renal fibrosis

Chronic kidney disease (CKD) is a long-term kidney damage caused by gradual loss of essential kidney functions. A global health issue, CKD affects up to 16% of the population worldwide. Symptoms are often not apparent in the early stages, and if left untreated, CKD can progress to end-stage kidney disease (ESKD), also known as kidney failure, when the only possible treatments are dialysis and kidney transplantation. The end point of nearly all forms of CKD is kidney fibrosis, a process of unsuccessful wound-healing of kidney tissue. Detection of kidney fibrosis, therefore, often means detection of CKD. Renal biopsy remains the best test for renal scarring, despite being intrinsically limited by its invasiveness and sampling bias. Urine is a desirable source of fibrosis biomarkers as it can be easily obtained in a non-invasive way and in large volumes. Besides, urine contains biomolecules filtered through the glomeruli, mirroring the pathological state. There is, however, a problem of highly abundant urinary proteins that can mask rare disease biomarkers. Urinary extracellular vesicles (uEVs), which originate from renal cells and carry proteins, nucleic acids, and lipids, are an attractive source of potential rare CKD biomarkers. Their cargo consists of low-abundant proteins but highly concentrated in a nanosize-volume, as well as molecules too large to be filtered from plasma. Combining molecular profiling data (protein and miRNAs) of uEVs, isolated from patients affected by various forms of CKD, this review considers the possible diagnostic and prognostic value of uEVs biomarkers and their potential application in the translation of new experimental antifibrotic therapeutics.

Metabolites as extracellular vesicle cargo in health, cancer, pleural effusion, and cardiovascular diseases: An emerging field of study to diagnostic and therapeutic purposes

Extracellular vesicles (EVs) are highly diverse nanoscale membrane-bound structures released from different cell types into the extracellular environment. They play essential functions in cell signaling by transporting their cargo, such as proteins, RNA, DNA, lipids, metabolites, and small molecules, to recipient cells. It has recently been shown that EVs might modulate carcinogenesis by delivering cargo to recipient cells. Furthermore, recent discoveries revealed that changes in plasma-derived EV levels and cargo in subjects with metabolic diseases were documented by many researchers, suggesting that EVs might be a promising source of disease biomarkers. One of the cargos of EVs that has recently attracted the most attention is metabolites. The metabolome of these vesicles introduces a plethora of disease indicators; hence, examining the metabolomics of EVs detected in human biofluids would be an effective approach. On the other hand, metabolites have various roles in biological systems, including the production of energies, synthesizing macromolecules, and serving as signaling molecules and hormones. Metabolome rewiring in cancer and stromal cells is a characteristic of malignancy, but the current understanding of how this affects the metabolite composition and activity of tumor-derived EVs remains in its infancy. Since new findings and studies in the field of exosome biology and metabolism are constantly being published, it is likely that diagnostic and treatment techniques, including the use of exosome metabolites, will be launched in the coming years. Recent years have seen increased interest in the EV metabolome as a possible source for biomarker development. However, our understanding of the role of these molecules in health and disease is still immature. In this work, we have provided the latest findings regarding the role of metabolites as EV cargoes in the pathophysiology of diseases, including cancer, pleural effusion (PE), and cardiovascular disease (CVD). We also discussed the significance of metabolites as EV cargoes of microbiota and their role in host-microbe interaction. In addition, the latest findings on metabolites in the form of EV cargoes as biomarkers for disease diagnosis and treatment are presented in this study.

Release of SMP30 in Extracellular Vesicles under Conditions of Ascorbic Acid Deficiency Is Involved with Acute Phase Response in ODS Rat

Senescence marker protein-30 (SMP30) is a senescence marker molecule that exhibits lactonase activity in the ascorbic acid (AsA) biosynthesis pathway, except in primate mammals, including humans. Although numerous studies have shown that hepatic AsA deficiency causes acute-phase responses, details of the relationship between SMP30 expression and acute-phase responses in AsA-deficient conditions remain to be elucidated. Here, we investigated the effects of AsA deficiency on the relationship between SMP30 and acute liver injury in osteogenic disorder Shionogi (ODS) rats, which have a hereditary defect in AsA biosynthesis. Male-ODS rats (4 wk old) were pair-fed an AsA-free diet with distilled or 0.1% AsA-dissolved water for 14 d. Under AsA-deficient conditions, hepatic SMP30 protein level was decreased and liver injury markers, the serum aspartate aminotransferase/alanine transaminase ratio and cytokine-induced neutrophil chemoattractant-1 (CINC-1) concentration, were elevated. In contrast, SMP30 protein level in extracellular vesicles (EVs) was significantly increased in addition to the positive acute proteins haptoglobin and asialoglycoprotein receptor 1 (ASGPR1), hepatic-derived specific markers expression under AsA-deficient conditions. AsA deficiency also activated signal transducer and activator of transcription 3 (STAT3) which is linked to EVs release in the liver. These results suggest that the release of SMP30 in EVs by AsA deficiency is involved with acute-phase responses.

Molecular Pathways of Diabetic Kidney Disease Inferred from Proteomics

Diabetic kidney disease (DKD) affects an estimated 20-40% of type 2 diabetes patients and is among the most prevalent microvascular complications in this patient population, contributing to high morbidity and mortality rates. Currently, changes in albuminuria status are thought to be a primary indicator of the onset or progression of DKD, yet progressive nephropathy and renal impairment can occur in certain diabetic individuals who exhibit normal urinary albumin levels, emphasizing the lack of sensitivity and specificity associated with the use of albuminuria as a biomarker for detecting diabetic kidney disease and predicting DKD risk. According to the study, a non-invasive method for early detection or prediction of DKD may involve combining proteomic analytical techniques such second generation sequencing, mass spectrometry, two-dimensional gel electrophoresis, and other advanced system biology algorithms. Another category of proteins of relevance may now be provided by renal tissue biomarkers. The establishment of reliable proteomic biomarkers of DKD represents a novel approach to improving the diagnosis, prognostic evaluation, and treatment of affected patients. In the present review, a series of protein biomarkers that have been characterized to date are discussed, offering a theoretical foundation for future efforts to aid patients suffering from this debilitating microvascular complication.

Metabolomics Analysis of Urinary Extracellular Vesicles by Nuclear Magnetic Resonance and Liquid Chromatography-Mass Spectrometry

Extracellular vesicle (EV) release and their content are influenced by diverse clinical conditions. EVs participate in inter-cellular communication and have been postulated as reflectors of the pathophysiology of the cells, tissues, organs or the whole system with which they are in contact. Urinary EVs have been proved to reflect pathophysiology not only of renal system related diseases constituting an additional source of potential biomarkers easily accessible in a non-invasive way. The interest in EVs cargo has been mostly focused on proteins and nucleic acids and more recently it has been extended to metabolites. Metabolites represent the downstream changes in the genome, transcriptome, and proteome as a reflection of processes occurring in living organisms. For their study, nuclear magnetic resonance (NMR) and mass spectrometry in tandem (LC-MS/MS) are widely used. NMR is a reproducible and non-destructive technique and we show here methodological protocols for the metabolomics analysis of urinary EVs by NMR. Additionally, we also describe the workflow for a targeted LC-MS/MS analysis that is extensible to untargeted studies.

Extracellular Vesicles as Theranostic Tools in Kidney Disease

Extracellular vesicles are important vectors for cell-cell communication and show potential value for diagnosis and treatment of kidney diseases. The pathologic diagnosis of kidney diseases relies on kidney biopsy, whereas collection of extracellular vesicles from urine or circulating blood may constitute a less invasive diagnostic tool. In particular, urinary extracellular vesicles released mainly from resident kidney cells might provide an alternative tool for detection of kidney injury. Because extracellular vesicles mirror many features of their parent cells, cargoes of several populations of urinary extracellular vesicles are promising biomarkers for disease processes, like diabetic kidney disease, kidney transplant, and lupus nephritis. Contrarily, extracellular vesicles derived from reparative cells, such as mesenchymal stem cells, tubular epithelial progenitor cells, and human umbilical cord blood represent promising regenerative tools for treatment of kidney diseases. Furthermore, induced pluripotent stem cells-derived and engineered extracellular vesicles are being developed for specific applications for the kidney. Nevertheless, some assumptions regarding the specificity and immunogenicity of extracellular vesicles remain to be established. This review focuses on the utility of extracellular vesicles as therapeutic and diagnostic (theranostic) tools in kidney diseases and future directions for studies.

Urinary exosomes: Emerging therapy delivery tools and biomarkers for urinary system diseases

Urinary exosomes (UE) are small circular membranous vesicles with a lipid bilayer with a diameter of 40-160 nm secreted by epithelial cells of the kidney and genitourinary system, which can reflect the physiological and functional status of secretory cells. Protein and RNA in exosomes can be used as markers for diseases diagnosis. Urine specimens are available and non-invasive. The protein and RNA in UE are more stable than the soluble protein and RNA in urine, which have broad application prospects in the diagnosis of urinary system diseases. This article reviews the recent advances in the application of protein or RNA in UE as markers to the diagnosis of urinary system diseases.

Application of exosomes in the diagnosis and treatment of pancreatic diseases

Pancreatic diseases, a serious threat to human health, have garnered considerable research interest, as they are associated with a high mortality rate. However, owing to the uncertain etiology and complex pathophysiology, the treatment of pancreatic diseases is a challenge for clinicians and researchers. Exosomes, carriers of intercellular communication signals, play an important role in the diagnosis and treatment of pancreatic diseases. Exosomes are involved in multiple stages of pancreatic disease development, including apoptosis, immune regulation, angiogenesis, cell migration, and cell proliferation. Thus, extensive alterations in the quantity and variety of exosomes may be indicative of abnormal biological behaviors of pancreatic cells. This phenomenon could be exploited for the development of exosomes as a new biomarker or target of new treatment strategies. Several studies have demonstrated the diagnostic and therapeutic effects of exosomes in cancer and inflammatory pancreatic diseases. Herein, we introduce the roles of exosomes in the diagnosis and treatment of pancreatic diseases and discuss directions for future research and perspectives of their applications.

Extracellular Vesicles in Type 1 Diabetes: A Versatile Tool

Type 1 diabetes is a chronic autoimmune disease affecting nearly 35 million people. This disease develops as T-cells continually attack the β-cells of the islets of Langerhans in the pancreas, which leads to β-cell death, and steadily decreasing secretion of insulin. Lowered levels of insulin minimize the uptake of glucose into cells, thus putting the body in a hyperglycemic state. Despite significant progress in the understanding of the pathophysiology of this disease, there is a need for novel developments in the diagnostics and management of type 1 diabetes. Extracellular vesicles (EVs) are lipid-bound nanoparticles that contain diverse content from their cell of origin and can be used as a biomarker for both the onset of diabetes and transplantation rejection. Furthermore, vesicles can be loaded with therapeutic cargo and delivered in conjunction with a transplant to increase cell survival and long-term outcomes. Crucially, several studies have linked EVs and their cargos to the progression of type 1 diabetes. As a result, gaining a better understanding of EVs would help researchers better comprehend the utility of EVs in regulating and understanding type 1 diabetes. EVs are a composition of biologically active components such as nucleic acids, proteins, metabolites, and lipids that can be transported to particular cells/tissues through the blood system. Through their varied content, EVs can serve as a flexible aid in the diagnosis and management of type 1 diabetes. In this review, we provide an overview of existing knowledge about EVs. We also cover the role of EVs in the pathogenesis, detection, and treatment of type 1 diabetes and the function of EVs in pancreas and islet β-cell transplantation.

A systematic review and Meta-analysis of urinary extracellular vesicles proteome in diabetic nephropathy

Diabetic nephropathy (DN) is a major microvascular complication of both type 1 and type 2 diabetes mellitus and is the most frequent cause of end-stage renal disease with an increasing prevalence. Presently there is no non-invasive method for differential diagnosis, and an efficient target therapy is lacking. Extracellular vesicles (EV), including exosomes, microvesicles, and apoptotic bodies, are present in various body fluids such as blood, cerebrospinal fluid, and urine. Proteins in EV are speculated to be involved in various processes of disease and reflect the original cells' physiological states and pathological conditions. This systematic review is based on urinary extracellular vesicles studies, which enrolled patients with DN and investigated the proteins in urinary EV. We systematically reviewed articles from the PubMed, Embase, Web of Science databases, and China National Knowledge Infrastructure (CNKI) database until January 4, 2022. The article quality was appraised according to the Newcastle-Ottawa Quality Assessment Scale (NOS). The methodology of samples, isolation and purification techniques of urinary EV, and characterization methods are summarized. Molecular functions, biological processes, and pathways were enriched in all retrievable urinary EV proteins. Protein-protein interaction analysis (PPI) revealed pathways of potential biomarkers. A total of 539 articles were retrieved, and 13 eligible records were enrolled in this systematic review and meta-analysis. And two studies performed mass spectrometry to obtain the proteome profile. Two of them enrolled only T1DM patients, two studies enrolled both patients with T1DM and T2DM, and other the nine studies focused on T2DM patients. In total 988 participants were enrolled, and DN was diagnosed according to UACR, UAER, or decreased GFR. Totally 579 urinary EV proteins were detected and 28 of them showed a potential value to be biomarkers. The results of bioinformatics analysis revealed that urinary EV may participate in DN through various pathways such as angiogenesis, biogenesis of EV, renin-angiotensin system, fluid shear stress and atherosclerosis, collagen degradation, and immune system. Besides that, it is necessary to report results compliant with the guideline of ISEV, in orderto assure repeatability and help for further studies. This systematic review concordance with previous studies and the results of meta-analysis may help to value the methodology details when urinary EV proteins were reported, and also help to deepen the understanding of urinary EV proteins in DN.

The roles of mesenchymal stem cell-derived exosomes in diabetes mellitus and its related complications

Diabetes mellitus is a type of metabolic disease characterized by hyperglycemia, primarily caused by defects in insulin secretion, insulin action, or both. Long-term chronic hyperglycemia can lead to diabetes-related complications, causing damage, dysfunction, and failure of different organs. However, traditional insulin and oral drug therapy can only treat the symptoms but not delay the progressive failure of pancreatic beta cells or prevent the emergence of diabetic complications. Mesenchymal stem cells have received extensive attention due to their strong immunoregulatory functions and regeneration effects. Mesenchymal stem cell-derived exosomes (MSC-Exos) have been proposed as a novel treatment for diabetic patients as they have demonstrated superior efficiency to mesenchymal stem cells. This review summarizes the therapeutic effects, mechanisms, challenges, and future prospects of MSC-Exos in treating diabetes mellitus and its related complications. This review supports the potential use of MSC-Exos in future regenerative medicine to overcome the current difficulties in clinical treatment, particularly in treating diabetes.

Senescence marker protein 30 (SMP30) protects against high glucose-induced apoptosis, oxidative stress and inflammatory response in retinal ganglion cells by enhancing Nrf2 activation via regulation of Akt/GSK-3β pathway

Senescence marker protein 30 (SMP30) is an aging-related protein that participates in the regulation of tissue damage under various pathological conditions. However, the role of SMP30 in mediating high glucose (HG)-induced injury of retinal ganglion cells (RGCs) has not been fully determined. We found that SMP30 expression declined during HG stimulation in RGCs. Cellular functional studies showed that the up-regulation of SMP30 dramatically prohibited HG-evoked apoptosis, oxidative stress and inflammatory response in RGCs. Mechanism research reported that SMP30 overexpression led to the enhancement of nuclear factor erythroid 2-related factor (Nrf2) activation in HG-stimulated RGCs. Moreover, SMP30 overexpression enhanced the phosphorylation of Akt and glucogen synthase kinase-3β (GSK-3β), and the suppression of Akt markedly abolished SMP30-mediated Nrf2 activation in HG-stimulated RGCs. Additionally, the suppression of Nrf2 substantially reversed SMP30-overexpression-induced anti-HG injury effects in RGCs. Overall, these findings suggest that SMP30 protects against HG injury of RGCs by potentiating Nrf2 through regulation of the Akt/GSK-3β pathway. Our work underscores that SMP30/Akt/GSK-3β/Nrf2 may exert a vital role in mediating the injury of RGCs during diabetic retinopathy.

Long non-cording RNA XIST promoted cell proliferation and suppressed apoptosis by miR-423-5p/HMGA2 axis in diabetic nephropathy

This research studied the effect of long non-coding RNA X-inactive-specific transcript (XIST) on DN. The effect of high glucose (HG) on the expression of XIST and miR-423-5p was detected by quantitative real-time PCR (qRT-PCR) in human kidney (HK) cells (human glomerular mesangial cells (HMCs) and human kidney-2 (HK-2) cells). The effect of XIST depletion and miR-423-5p inhibition or overexpression on high mobility group protein A2 (HMGA2) protein level was examined by western blot in HG-induced HK cells. The impacts of XIST depletion on viability and apoptosis were assessed by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) and flow cytometry assays in HG-induced HK cells. We found the expression of XIST and HMGA2 protein was significantly upregulated in DN tissues and cells. Moreover, HG treatment induced the upregulation of XIST and HMGA2 protein level in HK cells. Besides, both XIST depletion and HMGA2 depletion decreased cell proliferation but increased apoptosis in HG-treated HK cells. Furthermore, HMGA2 upregulation or miR-423-5p inhibition partly eliminated the effects of XIST depletion on cell proliferation, apoptosis of HG-treated HK cells. Interestingly, HMGA2 upregulation partly reversed miR-423-5p overexpression-mediated suppression on viability and promotion on apoptosis in HG-treated HK cells. Mechanistically, XIST sponged miR-423-5p to regulate HMGA2 expression in DN cells. Taken together, XIST depletion suppressed proliferation and promoted apoptosis via miR-423-5p/HMGA2 axis in HG-treated HK cells, which may provide a potential therapeutic target for DN.

Exosomes: Emerging Therapy Delivery Tools and Biomarkers for Kidney Diseases

Exosomes are nanometer-sized small EVs coated with bilayer structure, which are released by prokaryotic and eukaryotic cells. Exosomes are rich in a variety of biologically active substances, such as proteins, nucleotides, and lipids. Exosomes are widely present in various body fluids and cell culture supernatants, and it mediates the physiological and pathological processes of the body through the shuttle of these active ingredients to target cells. In recent years, studies have shown that exosomes from a variety of cell sources can play a beneficial role in acute and chronic kidney disease. In particular, exosomes derived from mesenchymal stem cells have significant curative effects on the prevention and treatment of kidney disease in preclinical trials. Besides, some encapsulated substances are demonstrated to exert beneficial effects on various diseases, so they have attracted much attention. In addition, exosomes have extensive sources, stable biological activity, and good biocompatibility and are easy to store and transport; these advantages endow exosomes with superior diagnostic value. With the rapid development of liquid biopsy technology related to exosomes, the application of exosomes in the rapid diagnosis of kidney disease has become more prominent. In this review, the latest development of exosomes, including the biosynthesis process, the isolation and identification methods of exosomes are systematically summarized. The utilization of exosomes in diagnosis and their positive effects in the repair of kidney dysfunction are discussed, along with the specific mechanisms. This review is expected to be helpful for relevant studies and to provide insight into future applications in clinical practice.

Exosomes: Advances, development and potential therapeutic strategies in diabetic nephropathy

Exosomes, a major type of extracellular vesicles (EVs), are nanoscale vesicles excreted by almost all cell types via invagination of the endosomal membrane pathway. Exosomes play a crucial role in the mediation of intercellular communication both in health and disease, which can be ascribed to their capacity to be transported to neighboring or distant cells, thus regulating the biological function of recipient cells through cargos such as DNA, mRNA, proteins and microRNA. Diabetic nephropathy (DN) is a serious microvascular complication associated with diabetes mellitus as well as a significant cause of end-stage renal disease worldwide, which has resulted in a substantial economic burden on individuals and society. However, despite extensive efforts, therapeutic approaches that prevent the progression of DN do not exist, which implies new approaches are required. An increasing number of studies suggest that exosomes are involved in the pathophysiological processes associated with DN, which may potentially provide novel biomarkers and therapeutic targets for DN. Hence, this review summarizes recent advances involving exosome mechanisms in DN and their potential as biomarkers and therapeutic targets.

Analysis of urinary exosomal metabolites identifies cardiovascular risk signatures with added value to urine analysis

BACKGROUND

Subclinical atherosclerosis may result in fatal cardiovascular (CV) events, but the underlying mechanisms and molecular players leading to disease are not entirely understood. Thus, novel approaches capable of identifying the factors involved in pathological progression and providing a better understanding of the subjacent mechanisms are needed. Extracellular vesicles (EVs) have been shown to have numerous biological functions, and their metabolome has recently generated interest as a source of novel biomarkers. The metabolic content of the exosomes has been so far unexplored in cardiovascular disease (CVD), and here, we developed an analytical strategy aimed at probing urinary exosomal metabolite content and its association to CV risk.

RESULTS

Direct analysis of the exosomes without metabolite extraction was evaluated by high-resolution magic angle spinning (¹H HR-MAS). Other two methodologies for the analysis of exosomal metabolites by ¹H NMR were set up, based on methanol or organic solvents sequential extraction. The three methods were compared in terms of the number of detected signals and signal to noise ratio (S/N). The methanol method was applied to identify altered metabolites in the urinary exosomes of subjects with programmed coronary artery by-pass grafting (CABG) versus a control group. Target mass spectrometry (MS) was also performed for differential analysis. The clinical performance of exosomal metabolites of interest in CVD was investigated, and the added value of the exosomes compared to urine analysis was evaluated. Based on S/N ratio, simplicity, reproducibility, and quality of the spectrum, the methanol method was chosen for the study in CVD. A cardiometabolic signature composed by 4-aminohippuric acid, N-1-methylnicotinamide, and citric acid was identified in urinary exosomes. Directly in urine, 4-aminohippuric acid and citric acid do not show variation between groups and changes in N-1-methylnicotinamide are less pronounced, proving the added value of exosomes.

CONCLUSIONS

We set up a novel methodology to analyze metabolic alterations in urinary exosomes and identified a cardiometabolic signature in these microvesicles. This study constitutes the first evidence of a role for the exosomal metabolism in CVD and demonstrates the possibility to evaluate the urinary exosomal metabolic content by NMR and MS.

Emerging Roles of Exosomes in T1DM

Type 1 diabetes mellitus (T1DM) is a complex autoimmune disorder that mainly affects children and adolescents. The elevated blood glucose level of patients with T1DM results from absolute insulin deficiency and leads to hyperglycemia and the development of life-threatening diabetic complications. Although great efforts have been made to elucidate the pathogenesis of this disease, the precise underlying mechanisms are still obscure. Emerging evidence indicates that small extracellular vesicles, namely, exosomes, take part in intercellular communication and regulate interorgan crosstalk. More importantly, many findings suggest that exosomes and their cargo are associated with the development of T1DM. Therefore, a deeper understanding of exosomes is beneficial for further elucidating the pathogenic process of T1DM. Exosomes are promising biomarkers for evaluating the risk of developingty T1DM, monitoring the disease state and predicting related complications because their number and composition can reflect the status of their parent cells. Additionally, since exosomes are natural carriers of functional proteins, RNA and DNA, they can be used as therapeutic tools to deliver these molecules and drugs. In this review, we briefly introduce the current understanding of exosomes. Next, we focus on the relationship between exosomes and T1DM from three perspectives, i.e., the pathogenic role of exosomes in T1DM, exosomes as novel biomarkers of T1DM and exosomes as therapeutic tools for T1DM.

Regucalcin enhances adipocyte differentiation and attenuates inflammation in 3T3-L1 cells

Dysregulation of adipocyte differentiation and dysfunction play key roles in the pathogenesis of obesity and associated disorders such as diabetes and metabolic syndrome, and as such, a better understanding of the molecular mechanism of adipogenesis may help to elucidate the pathological condition of obesity and its associated disorders. Regucalcin (RGN) plays multiple regulatory roles in intracellular Ca²⁺ signaling pathways in mammalian cells. Here, we report that overexpression of RGN enhances lipid accumulation in 3T3‐L1 adipocyte cells after adipogenic stimulation, accompanied by upregulation of adipocyte differentiation marker proteins. In contrast, genetic disruption of RGN inhibited adipogenic stimulation‐induced differentiation of 3T3‐L1 cells. Furthermore, RGN overexpression in differentiated 3T3‐L1 adipocytes blocked inflammatory crosstalk between 3T3‐L1 adipocytes and RAW264.7 macrophages in a transwell coculture system. Knockdown of RGN expression in cocultured 3T3‐L1 adipocytes enhanced their susceptibility to RAW264.7 macrophage‐mediated inflammation. These results suggest that RGN is required for 3T3‐L1 adipocyte differentiation and that it exerts anti‐inflammatory activity against 3T3‐L1 adipocyte inflammation after coculture with RAW264.7 macrophages. Thus, RGN may be a novel regulator of adipocyte differentiation and act as a suppressor of inflammation in macrophage‐infiltrated adipocyte tissue.

Exosomes in Nephropathies: A Rich Source of Novel Biomarkers

The biomarkers commonly utilized in diagnostic evaluations of kidney disease suffer from low sensitivity, especially in the early stages of renal damage. On the other hand, obtaining a renal biopsy to augment clinical decision making can lead to potentially serious complications. In order to overcome the shortcomings of currently available diagnostic tools, recent studies suggest that exosomes, cell-secreted extracellular vesicles containing a large array of active molecules to facilitate cell-to-cell communication, may represent a rich source of novel disease biomarkers. Because of their endocytic origin, exosomes carry markers typical for their parent cells, which could permit the localization of biochemical cellular alterations in specific kidney compartments. Different types of exosomes can be isolated from noninvasively obtained biofluids; however, in the context of kidney disease, evidence has emerged on the role of urinary exosomes in the diagnostic and predictive modeling of renal pathology. The current review summarizes the potential application of exosomes in the detection of acute and chronic inflammatory, metabolic, degenerative, and genetic renal diseases.

The involvement of a regucalcin in suppressing hemocyte apoptosis in Pacific oyster Crassostrea gigas

Regucalcin (RGN), also known as senescence marker protein-30 (SMP30), plays a vital role in the regulation of Ca²⁺ homeostasis. In the present study, a regucalcin (designated as CgRGN) was identified from Pacific oyster Crassostrea gigas. The complete cDNA sequence of CgRGN was of 1059 bp, containing an open reading frame of 933 bp which encoded a protein of 310 amino acids. The deduced amino acid sequence of CgRGN shared similarity with other RGNs from the genome of C. gigas as well as other species. The mRNA transcripts of CgRGN were universally detected in all tested tissues, with higher level in hepatopancreas, labial palp, and gills. The relative expression level of CgRGN in hemocytes was significantly up-regulated (p < 0.05) at 3, 12, 72, and 96 h after the stimulation of lipopolysaccharide (LPS). After CgRGN expression was interfered by specific CgRGN-dsRNA, the hemocytes apoptosis rate increased dramatically at 12 h post LPS stimulation (1.56 fold, p < 0.01), compared to the control group. The caspase-3 activity in hemocytes and NO concentration in hemolymph increased significantly (p < 0.05) in dsCgRGN injection oysters. These results collectively indicated that CgRGN could suppress LPS-induced apoptosis and be involved in the immune response of oysters.

Increased cellular senescence in the murine and human stenotic kidney: Effect of mesenchymal stem cells

Cell stress may give rise to insuperable growth arrest, which is defined as cellular senescence. Stenotic kidney (STK) ischemia and injury induced by renal artery stenosis (RAS) may be associated with cellular senescence. Mesenchymal stem cells (MSCs) decrease some forms of STK injury, but their ability to reverse senescence in RAS remains unknown. We hypothesized that RAS evokes STK senescence, which would be ameliorated by MSCs. Mice were studied after 4 weeks of RAS, RAS treated with adipose tissue-derived MSCs 2 weeks earlier, or sham. STK senescence-associated β-galactosidase (SA-β-Gal) activity was measured. Protein and gene expression was used to assess senescence and the senescence-associated secretory phenotype (SASP), and staining for renal fibrosis, inflammation, and capillary density. In addition, senescence was assessed as p16+ and p21+ urinary exosomes in patients with renovascular hypertension (RVH) without or 3 months after autologous adipose tissue-derived MSC delivery, and in healthy volunteers (HV). In RAS mice, STK SA-β-Gal activity increased, and senescence and SASP marker expression was markedly elevated. MSCs improved renal function, fibrosis, inflammation, and capillary density, and attenuated SA-β-Gal activity, but most senescence and SASP levels remained unchanged. Congruently, in human RVH, p21+ urinary exosomes were elevated compared to HV, and only slightly improved by MSC, whereas p16+ exosomes remained unchanged. Therefore, RAS triggers renal senescence in both mice and human subjects. MSCs decrease renal injury, but only partly mitigate renal senescence. These observations support exploration of targeted senolytic therapy in RAS.

Proteomic analysis in lupus mice identifies Coronin-1A as a potential biomarker for lupus nephritis

BACKGROUND

Approximately 50% of systemic lupus erythematosus (SLE) patients develop nephritis, which is among the most severe and frequent complications of the disease and a leading cause of morbidity and mortality. Despite intensive research, there are still no reliable lupus nephritis (LN) markers in clinical use that can assess renal damage and activity with a high sensitivity and specificity. To this end, the aim of this study was to identify new clinically relevant tissue-specific protein biomarkers and possible underlying molecular mechanisms associated with renal involvement in SLE, using mass spectrometry (MS)-based proteomics.

METHODS

Kidneys were harvested from female triple congenic B6.NZMsle1/sle2/sle3 lupus mice model, and the respective sex- and age-matched C57BL/6 control mice at 12, 24 and 36 weeks of age, representing pre-symptomatic, established and end-stage LN, respectively. Proteins were extracted from kidneys, purified, reduced, alkylated and digested by trypsin. Purified peptides were separated by liquid chromatography and analysed by high-resolution MS. Data were processed by the Progenesis QIp software, and functional annotation analysis was performed using DAVID bioinformatics resources. Immunofluorescence and multiple reaction monitoring (MRM) MS methods were used to confirm prospective biomarkers in SLE mouse strains as well as human serum samples.

RESULTS

Proteomic profiling of kidney tissues from SLE and control mice resulted in the identification of more than 3800 unique proteins. Pathway analysis revealed a number of dysregulated molecular pathways that may be mechanistically involved in renal pathology, including phagosome and proximal tubule bicarbonate reclamation pathways. Proteomic analysis supported by human transcriptomic data and pathway analysis revealed Coronin-1A, Ubiquitin-like protein ISG15, and Rho GDP-dissociation inhibitor 2, as potential LN biomarkers. These results were further validated in other SLE mouse strains using MRM-MS. Most importantly, experiments in humans showed that measurement of Coronin-1A in human sera using MRM-MS can segregate LN patients from SLE patients without nephritis with a high sensitivity (100%) and specificity (100%).

CONCLUSIONS

These preliminary findings suggest that serum Coronin-1A may serve as a promising non-invasive biomarker for LN and, upon validation in larger cohorts, may be employed in the future as a screening test for renal disease in SLE patients.

Urinary exosomes: Potential biomarkers for diabetic nephropathy

Diabetic nephropathy is the most common diabetic complication culminating often into end-stage renal disease. Classically, it is defined by the presence of albuminuria which has limited ability to be detected at early stages but deterioration in kidney function generally precedes albuminuria. This necessitates the development of newer diagnostic assays for diabetic nephropathy to determine the progression of the disease. Kidney associated diseases with non-albuminuria further complicates a timely diagnosis and thus demands an early biomarker. Urinary exosomes, the nanovesicular entities are released by every epithelial cells of the nephron. Their protein or molecular cargo varies in the diseased state which may provide the pathophysiology of the kidney associated diseases. This drives them to be exploited as non-invasive biomarker. This review thus integrates the recent findings on the significance of the urinary exosomes as diagnostic biomarker in kidney-associated diseases, primarily in diabetic nephropathy.

Diabetic Nephropathy: Perspective on Extracellular Vesicles

Diabetic nephropathy (DN) is a major microvascular complication of diabetes mellitus. It is the most frequent cause of end-stage renal disease with no definitive therapy available so far. Extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, are nano- and micron-sized heterogeneous vesicles that can be secreted by almost all cell types. Importantly, EVs contain many biologically active materials, such as RNAs, DNAs, proteins, and lipids, from their parental cells, which can be transported to their recipient cells to mediate intercellular communication and signaling. Accumulating studies demonstrated that EVs, mainly exosomes and microvesicles, participated in the pathophysiological process of DN. Recently emerging studies also found that the contents of EVs in the urine (miRNAs, mRNAs, and proteins) could be used as potential biomarkers for DN. Therefore, in this mini-review, the generation, isolation methods, and biological function of EVs were introduced, and then the current information about the mechanism and the diagnostic value in the development of DN was summarized. Moreover, the review also discussed the future challenges of exploring the role of EVs in kidney disease.

The Association Between Leucine and Diabetic Nephropathy in Different Gender: A Cross-Sectional Study in Chinese Patients With Type 2 Diabetes

OBJECTIVE

This study aimed to evaluate how leucine are associated with diabetic nephropathy (DN) in type 2 diabetes (T2D) patients and the gender difference of this association.

METHODS

We retrieved 1,031 consecutive patients with T2D who meet the inclusion and exclusion criteria from the same tertiary care center and extracted clinical information from electronic medical record. Plasma leucine was measured by liquid chromatography-mass spectrometer. Restricted cubic spline (RCS) was conducted to examine potential non-linear relationship between leucine and the risk of DN. Logistic regression was used to obtain odds ratio (OR) and confidence interval (CI). Additive interaction was used to estimate the interaction effect between leucine and gender for DN.

RESULTS

We found there was a negative correlation between leucine and the risk of DN. After stratifying all patients by gender, this relationship only remained significant in women (OR:0.57, CI:0.41-0.79).

CONCLUSIONS

In conclusion, T2D patients with high levels of leucine have a lower risk of developing DN in female.

Fumarate accumulation involved in renal diabetic fibrosis in Goto-Kakizaki rats

The Goto-Kakizaki (GK) rat is a spontaneous animal model of type 2 diabetes and early stage of diabetic nephropathy. However, the pathophysiological mechanisms contributing to the progression of diabetic nephropathy in GK rats remain unclear. Kidneys from 15-week old male diabetic GK/Jcl rats and age-matched Wistar rats, which have the same genetic background as GK rats, were used. Proteomic analyses of GK and Wistar kidneys were performed using two-dimensional fluorescence difference gel electrophoresis (2D-DIGE). Differentially expressed proteins in GK rats were subjected to pathway analysis, and expression levels of hypoxia inducible factor 1α (HIF-1α) and transforming growth factor-β1 (TGF-β1), and fumarate accumulation in GK kidneys were examined. Azan staining and immunohistochemical staining of α-smooth muscle actin were performed in relation to fibrosis in GK kidneys. Proteomic analysis using 2D-DIGE, analysis of fumarate content, and expression analysis of HIF-1α, TGF-β1, and α-smooth muscle actin of GK rat's kidney, suggested the mechanism of fibrosis characterized as two stages in diabetic nephropathy of GK rats. Abnormalities of glucose metabolism such as elevated levels of 2-oxoglutarate dehydrogenase and reduction of fumarate hydratase caused the accumulation of fumarate followed by the upregulation of HIF-1α and TGF-β1 leading to fibrosis in diabetic nephropathy. Alterations in proteins involved in the tricarboxylic acid cycle are associated with fibrosis through fumarate accumulation in diabetic nephropathy of GK rats.

Exosomes and microvesicles in normal physiology, pathophysiology, and renal diseases

Extracellular vesicles are cell-derived membrane particles ranging from 30 to 5,000 nm in size, including exosomes, microvesicles, and apoptotic bodies. They are released under physiological conditions, but also upon cellular activation, senescence, and apoptosis. They play an important role in intercellular communication. Their release may also maintain cellular integrity by ridding the cell of damaging substances. This review describes the biogenesis, uptake, and detection of extracellular vesicles in addition to the impact that they have on recipient cells, focusing on mechanisms important in the pathophysiology of kidney diseases, such as thrombosis, angiogenesis, tissue regeneration, immune modulation, and inflammation. In kidney diseases, extracellular vesicles may be utilized as biomarkers, as they are detected in both blood and urine. Furthermore, they may contribute to the pathophysiology of renal disease while also having beneficial effects associated with tissue repair. Because of their role in the promotion of thrombosis, inflammation, and immune-mediated disease, they could be the target of drug therapy, whereas their favorable effects could be utilized therapeutically in acute and chronic kidney injury.

The role of mass spectrometry in studies of glycation processes and diabetes management

In the last decade, mass spectrometry has been widely employed in the study of diabetes. This was mainly due to the development of new, highly sensitive, and specific methods representing powerful tools to go deep into the biochemical and pathogenetic processes typical of the disease. The aim of this review is to give a panorama of the scientifically valid results obtained in this contest. The recent studies on glycation processes, in particular those devoted to the mechanism of production and to the reactivity of advanced glycation end products (AGEs, AGE peptides, glyoxal, methylglyoxal, dicarbonyl compounds) allowed to obtain a different view on short and long term complications of diabetes. These results have been employed in the research of effective markers and mass spectrometry represented a precious tool allowing the monitoring of diabetic nephropathy, cardiovascular complications, and gestational diabetes. The same approaches have been employed to monitor the non-insulinic diabetes pharmacological treatments, as well as in the discovery and characterization of antidiabetic agents from natural products. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 38:112-146, 2019.

Implementation of Proteomics Biomarkers in Nephrology: From Animal Models to Human Application?

Preclinical animal models are extensively used in nephrology. In this review, the utility of performing proteome analysis of kidney tissue or urine in such models and transfer of the results to human application has been assessed. Analysis of the literature identified 68 relevant publications. Pathway analysis of the reported proteins clearly indicated links with known biological processes in kidney disease providing validation of the observed changes in the preclinical models. However, although most studies focused on the identification of early markers of kidney disease or prediction of its progression, none of the identified makers has made it to substantial validation in the clinic or at least in human samples. Especially in renal disease where urine is an abundant source of biomarkers of diseases of the kidney and the urinary tract, it therefore appears that the focus should be on human material based discovery studies. In contrast, the most valid information of proteome analysis of preclinical models in nephrology for translation in human disease resides in studies focusing on drug evaluation, both efficacy for translation to the clinic and for mechanistic insight.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Changes in the urinary extracellular vesicle proteome are associated with nephronophthisis-related ciliopathies

Nephronophthisis is one of the leading genetic causes of end-stage renal disease in childhood. Early diagnostics and prognostics for nephronophthisis are currently limited. We aimed to identify non-invasive protein biomarkers for nephronophthisis in urinary extracellular vesicles. Extracellular vesicles were isolated from urine of 12 patients with a nephronophthisis-related ciliopathy and 12 age- and gender-matched controls, followed by in-depth label-free LC-MS/MS proteomics analysis of gel fractionated extracellular vesicle proteins. Supervised cluster analysis of proteomic profiles separated patients from controls. We identified 156 differentially expressed proteins with fold change ≥4 in patients compared to controls (P < .05). Importantly, expression levels of discriminating proteins were correlated with chronic kidney disease stage, suggesting possible applications for urinary extracellular vesicle biomarkers in prognostics for nephronophthisis. Enrichment analysis of gene ontology terms revealed GO terms including signaling, actin cytoskeleton and endocytosis among the downregulated proteins in patients, whereas terms related to response to wounding and extracellular matrix organization were enriched among upregulated proteins. Our findings represent the first step towards a non-invasive diagnostic test for nephronophthisis. Further research is needed to determine specificity of the candidate biomarkers. In conclusion, proteomic profiles of urinary extracellular vesicles differentiate nephronophthisis-related ciliopathy patients from healthy controls. SIGNIFICANCE: Nephronophthisis is an important cause of end-stage renal disease in children and is associated with an average diagnostic delay of 3.5 years. This is the first study investigating candidate biomarkers for nephronophthisis using global proteomics analysis of urinary extracellular vesicles in patients with nephronophthisis compared to control individuals. We show that measuring protein markers in urinary extracellular vesicles is a promising approach for non-invasive early diagnostics of nephronophthisis.

Urinary Extracellular Vesicle: A Potential Source of Early Diagnostic and Therapeutic Biomarker in Diabetic Kidney Disease

OBJECTIVE

Diabetic kidney disease (DKD) has become one of the major causes of end-stage renal disease. Urinary extracellular vesicles (uEVs) contain rich biological information which could be the ideal source for noninvasive biomarkers of DKD. This review discussed the potential early diagnostic and therapeutic values of proteins and microRNAs in uEVs in DKD.

DATA SOURCES

This review was based articles published in PubMed, Embase, Cochrane, and Google Scholar databases up to November 20, 2017, with the following keywords: "Diabetic kidney disease", "Extracellular vesicle", and "Urine".

STUDY SELECTION

Relevant articles were carefully reviewed, with no exclusions applied to the study design and publication type.

RESULTS

There is no "gold standard" technology to separate and/or purify uEVs. The uEVs contain a variety of proteins and RNAs and participate in the physiological and pathological processes of the kidney. UEVs, especially urinary exosomes, may be useful biomarkers for early diagnosis and treatment to DKD. Furthermore, the uEVs has been used as a therapeutic target for DKD.

CONCLUSION

Proteins and nucleic acids in uEVs represent promising biomarker for the diagnosis and treatment of DKD.

Exosomes from adipose-derived stem cells overexpressing Nrf2 accelerate cutaneous wound healing by promoting vascularization in a diabetic foot ulcer rat model

Diabetic foot ulcers (DFU) increase the risks of infection and amputation in patients with diabetes mellitus (DM). The impaired function and senescence of endothelial progenitor cells (EPCs) and high glucose-induced ROS likely exacerbate DFUs. We assessed EPCs in 60 patients with DM in a hospital or primary care setting. We also evaluated the therapeutic effects of exosomes secreted from adipose-derived stem cells (ADSCs) on stress-mediated senescence of EPCs induced by high glucose. Additionally, the effects of exosomes and Nrf2 overexpression in ADSCs were investigated in vitro and in vivo in a diabetic rat model. We found that ADSCs that secreted exosomes promoted proliferation and angiopoiesis in EPCs in a high glucose environment and that overexpression of Nrf2 increased this protective effect. Wounds in the feet of diabetic rats had a significantly reduced ulcerated area when treated with exosomes from ADSCs overexpressing Nrf2. Increased granulation tissue formation, angiogenesis, and levels of growth factor expression as well as reduced levels of inflammation and oxidative stress-related proteins were detected in wound beds. Our data suggest that exosomes from ADSCs can potentially promote wound healing, particularly when overexpressing Nrf2 and therefore that the transplantation of exosomes may be suitable for clinical application in the treatment of DFUs.

Tiny membrane-bound sacs released by some stem cells carry chemicals that can heal the foot ulcers that are a major complication of diabetes. The sacs, called exosomes, are released by many cells for signaling between cells and other functions. Xue Li of Tongji University in Shanghai and co-workers focused on the effects of exosomes from stem cells derived from body fat cells. They found that the exosomes could encourage the healing of diabetic foot ulcers in rats. The research also uncovered useful information about the molecular interactions involved in the accelerated healing. It revealed the significance of one particular protein in the formation of new blood vessels, which is central to the healing. The authors suggest that collecting and transplanting suitable exosomes could offer a new approach for treating diabetic foot ulcers.

Urinary exosomes reveal protein signatures in hypertensive patients with albuminuria

Albuminuria is an indicator of cardiovascular risk and renal damage in hypertensive individuals. Chronic renin-angiotensin system (RAS) suppression facilitates blood pressure control and prevents development of new-onset-albuminuria. A significant number of patients, however, develop albuminuria despite chronic RAS blockade, and the physiopathological mechanisms are underexplored. Urinary exosomes reflect pathological changes taking place in the kidney. The objective of this work was to examine exosomal protein alterations in hypertensive patients with albuminuria in the presence of chronic RAS suppression, to find novel clues underlying its development. Patients were followed-up for three years and were classified as: a) patients with persistent normoalbuminuria; b) patients developing de novo albuminuria; and c) patients with maintained albuminuria. Exosomal protein alterations between groups were identified by isobaric tag quantitation (iTRAQ). Confirmation was approached by target analysis (SRM). In total, 487 proteins were identified with high confidence. Specifically, 48 proteins showed an altered pattern in response to hypertension and/or albuminuria. Out of them, 21 proteins interact together in three main functional clusters: glycosaminoglycan degradation, coagulation and complement system, and oxidative stress. The identified proteins constitute potential targets for drug development and may help to define therapeutic strategies to evade albuminuria progression in hypertensive patients chronically treated.

Extracellular vesicles in renal disease

Extracellular vesicles, such as exosomes and microvesicles, are host cell-derived packages of information that allow cell-cell communication and enable cells to rid themselves of unwanted substances. The release and uptake of extracellular vesicles has important physiological functions and may also contribute to the development and propagation of inflammatory, vascular, malignant, infectious and neurodegenerative diseases. This Review describes the different types of extracellular vesicles, how they are detected and the mechanisms by which they communicate with cells and transfer information. We also describe their physiological functions in cellular interactions, such as in thrombosis, immune modulation, cell proliferation, tissue regeneration and matrix modulation, with an emphasis on renal processes. We discuss how the detection of extracellular vesicles could be utilized as biomarkers of renal disease and how they might contribute to disease processes in the kidney, such as in acute kidney injury, chronic kidney disease, renal transplantation, thrombotic microangiopathies, vasculitides, IgA nephropathy, nephrotic syndrome, urinary tract infection, cystic kidney disease and tubulopathies. Finally, we consider how the release or uptake of extracellular vesicles can be blocked, as well as the associated benefits and risks, and how extracellular vesicles might be used to treat renal diseases by delivering therapeutics to specific cells.

Potential Role of Serum and Urinary Biomarkers in Diagnosis and Prognosis of Diabetic Nephropathy

PURPOSE OF REVIEW

Diabetic nephropathy (DN) is a progressive kidney disease caused by alterations in kidney architecture and function, and constitutes one of the leading causes of end-stage renal disease (ESRD). The purpose of this review is to summarize the state of the art of the DN-biomarker field with a focus on the new strategies that enhance the sensitivity of biomarkers to predict patients who will develop DN or are at risk of progressing to ESRD.

OBJECTIVE

In this review, we provide a description of the pathophysiology of DN and propose a panel of novel putative biomarkers associated with DN pathophysiology that have been increasingly investigated for diagnosis, to predict disease progression or to provide efficient personal treatment.

METHODS

We performed a review of the literature with PubMed and Google Scholar to collect baseline data about the pathophysiology of DN and biomarkers associated. We focused our research on new and emerging biomarkers of DN.

KEY FINDINGS

In this review, we summarized the critical signaling pathways and biological processes involved in DN and highlighted the pathogenic mediators of this disease. We next proposed a large review of the major advances that have been made in identifying new biomarkers which are more sensitive and reliable compared with currently used biomarkers. This includes information about emergent biomarkers such as functional noncoding RNAs, microRNAs, long noncoding RNAs, exosomes, and microparticles.

LIMITATIONS

Despite intensive strategies and constant investigation, no current single treatment has been able to reverse or at least mitigate the progression of DN, or reduce the morbidity and mortality associated with this disease. Major difficulties probably come from the renal disease being heterogeneous among the patients.

IMPLICATIONS

Expanding the proteomics screening, including oxidative stress and inflammatory markers, along with metabolomics approaches may further improve the prognostic value and help in identifying the patients with diabetes who are at high risk of developing kidney diseases.

Exosomal and Non-Exosomal Urinary miRNAs in Prostate Cancer Detection and Prognosis

BACKGROUND

MicroRNAs (miRNAs) are non-coding small RNAs, involved in post-transcriptional regulation of many target genes.

METHODS

Five miRNAs that have been consistently found deregulated in PCa (miR-21, miR-141, miR-214, miR-375, and let-7c) were analyzed in urinary pellets from 60 prostate cancer (PCa) patients and 10 healthy subjects by qRT-PCR. Besides, urinary exosomes were isolated by differential centrifugation and analyzed for those miRNAs.

RESULTS

Significant upregulation of miR-21, miR-141, and miR-375 was found comparing PCa patients with healthy subjects in urinary pellets, while miR-214 was found significantly downregulated. Regarding urinary exosomes, miR-21 and miR-375 were also significantly upregulated in PCa but no differences were found for miR-141. Significant differences were found for let-7c in PCa in urinary exosomes while no differences were observed in urinary pellets. A panel combining miR-21 and miR-375 is suggested as the best combination to distinguish PCa patients and healthy subjects, with an AUC of 0.872. Furthermore, the association of miRNAs with clinicopathological characteristics was investigated. MiR-141 resulted significantly correlated with Gleason score in urinary pellets and let-7c with clinical stage in urinary exosomes. Additionally, miR-21, miR-141, and miR-214 were found significantly deregulated in intermediate/high-risk PCa versus low-risk/healthy subjects in urinary pellets. Significant differences between both groups were found in urinary exosomes for miR-21, miR-375, and let-7c.

CONCLUSIONS

These findings suggest that the analysis of miRNAs-especially miRNA-21 and miR-375- in urine could be useful as biomarkers in PCa. Prostate 77: 573-583, 2017. © 2016 Wiley Periodicals, Inc.

Involvement of senescence marker protein-30 in glucose metabolism disorder and non-alcoholic fatty liver disease

Senescence marker protein-30 (SMP30) was found to decrease in the liver, kidneys and lungs of mice during aging. SMP30 is a pleiotropic protein that acts to protect cells from apoptosis by enhancing plasma membrane Ca(2+) -pump activity and is bona fide gluconolactonase (EC 3.1.1.17) that participates in the penultimate step of the vitamin C biosynthetic pathway. For the past several years, we have obtained strong evidence showing the close relationship between SMP30, glucose metabolism disorder and non-alchoholic fatty liver disease in experiments with SMP30 knockout mice. Emerging proof links the following abnormalities: (i) the reduction of SMP30 by aging and/or excessive dietary fat or genetic deficiency causes a loss of Ca(2+) pumping activity, which impairs acute insulin release in pancreatic β-cells, initiates inflammatory responses with oxidative stress and endoplasmic reticulum stress in non-alchoholic steatohepatitis, exacerbates renal tubule damage, and introduces tubulointerstitial inflammation and fibrosis in diabetic nephropathy; (ii) vitamin C insufficiency also impairs acute insulin secretion in pancreatic β-cells by a mechanism distinct from that of the SMP30 deficiency; and (iii) the increased oxidative stress by concomitant deficiencies of SMP30, superoxide dismutase 1 and vitamin C similarly causes hepatic steatosis. Here, we review recent advances in our understanding of SMP30 in glucose metabolism disorder and non-alchoholic fatty liver disease.

Urinary Microvesicle-Bound Uromodulin: A Potential Molecular Biomarker in Diabetic Kidney Disease

This study was designed to investigate the changes of urinary microvesicle-bound uromodulin and total urinary uromodulin levels in human urine and the correlations with the severity of diabetic kidney disease (DKD). 31 healthy subjects without diabetes and 100 patients with type 2 diabetes mellitus (T2DM) were included in this study. The patients with T2DM were divided into three groups based on the urinary albumin/creatinine ratio (UACR): normoalbuminuria group (DM, n = 46); microalbuminuria group (DN1, n = 32); and macroalbuminuria group (DN2, n = 22). We use a specific monoclonal antibody AD-1 to capture the urinary microvesicles. Urinary microvesicle-bound uromodulin and total urinary uromodulin levels were determined by enzyme-linked immunosorbent assay (ELISA). Our results showed that the levels of urinary microvesicle-bound uromodulin in DN1 and DN2 groups were significantly higher than those in control group and DM group (P < 0.01). Multiple stepwise linear regression analysis showed that UACR was independent determinant for urinary microvesicle-bound uromodulin (P < 0.05) but not for total urinary uromodulin. These findings suggest that the levels of urinary microvesicle-bound uromodulin are associated with the severity of DKD. The uromodulin in urinary microvesicles may be a specific marker of DKD and potentially may be used to predict the onset and/or monitor the progression of DKD.

Urine Exosomes: An Emerging Trove of Biomarkers

Exosomes are released by most cells and can be isolated from all biofluids including urine. Exosomes are small vesicles formed as part of the endosomal pathway that contain cellular material surrounded by a lipid bilayer that can be traced to the plasma membrane. Exosomes are potentially a more targeted source of material for biomarker discovery than unfractionated urine, and provide diagnostic and pathophysiological information without an invasive tissue biopsy. Cytoplasmic contents including protein, mRNA, miRNA, and lipids have all been studied within the exosomal fraction. Many prospective urinary exosomal biomarkers have been successfully identified for a variety of kidney or genitourinary tract conditions; detection of systemic conditions may also be possible. Isolation and analysis of exosomes can be achieved by several approaches, although many require specialized equipment or involve lengthy protocols. The need for timely analysis in the clinical setting has driven considerable innovation with several promising options recently emerging. Consensus on exosome isolation, characterization, and normalization procedures would resolve critical clinical translational bottlenecks for existing candidate exosomal biomarkers and provide a template for additional discovery studies.