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

Extracellular Vesicle Preparation and Analysis: A State-of-the-Art Review

In recent decades, research on Extracellular Vesicles (EVs) has gained prominence in the life sciences due to their critical roles in both health and disease states, offering promising applications in disease diagnosis, drug delivery, and therapy. However, their inherent heterogeneity and complex origins pose significant challenges to their preparation, analysis, and subsequent clinical application. This review is structured to provide an overview of the biogenesis, composition, and various sources of EVs, thereby laying the groundwork for a detailed discussion of contemporary techniques for their preparation and analysis. Particular focus is given to state-of-the-art technologies that employ both microfluidic and non-microfluidic platforms for EV processing. Furthermore, this discourse extends into innovative approaches that incorporate artificial intelligence and cutting-edge electrochemical sensors, with a particular emphasis on single EV analysis. This review proposes current challenges and outlines prospective avenues for future research. The objective is to motivate researchers to innovate and expand methods for the preparation and analysis of EVs, fully unlocking their biomedical potential.

Sex differences in FASN protein concentrations in urinary exosomes related to serum triglycerides levels in healthy adults

BACKGROUND

Dysregulation of lipid metabolism is the most prominent metabolic alteration observed in obesity, cancer, and cardiovascular diseases. The present study aimed to explore the sex differences associated with lipid metabolism in urinary exosome proteins, and evaluate the correlation of urinary exosome proteins with serum lipid biomarkers.

METHODS

The key enzymes regulating lipid metabolism in healthy adults were screened using urinary exosome data. Urinary exosomes were isolated from 120 healthy subjects and the expression of urinary proteins was assessed by Western blotting and ELISA. The correlation between urinary protein concentrations and the levels of serum lipid biomarkers was analyzed using correlation analysis.

RESULTS

Three urinary exosome proteins, namely fatty acid synthase (FASN), phosphoenolpyruvate carboxykinase (PCK1), and ATP-citrate synthase (ACLY) were identified, and only FASN showed sex differences. Sex differences were also observed in the serum triglyceride (TG) levels. Healthy males had higher FASN levels than females, and a moderate positive correlation was found between FASN concentrations and serum TG levels in healthy males (r = 0.479, P < 0.05). FASN concentrations in different age groups were positively correlated with the level of serum TG (18 ~ 30 years, r = 0.502; 31 ~ 44 years, r = 0.587; 45 ~ 59 years, r = 0.654; all P < 0.05). In addition, FASN concentrations was positively related to the increase in serum TG levels (range:1.0 ~ 1.7 mmol/L; r = 0.574, P < 0.05).

CONCLUSIONS

Sex differences were observed in urinary exosome FASN protein levels in healthy adults. FASN protein levels positively correlated with increased serum TG levels. FASN may serve as a novel biomarker to evaluate fatty acid synthesis in the human body.

Urinary exosome proteins PAK6 and EGFR as noninvasive diagnostic biomarkers of diabetic nephropathy

OBJECTIVE

The actin cytoskeleton plays an essential role in maintaining podocyte functions. However, whether the urinary exosome proteins related to the regulation of the actin cytoskeleton are changed in diabetic nephropathy (DN) is still unknown. This study was to investigate the possibility that related proteins can be applied as diagnostic biomarkers for DN.

METHODS

Urinary exosomes were obtained from 144 participants (Discovery phase: n = 72; Validation phase: n = 72) by size exclusion chromatography methods. Proteomic analysis of urinary exosome by LC-MS/MS. Western blot and ELISA were applied to validate the selected urinary exosome proteins. The clinical value of selected urinary exosome proteins was evaluated using correlation and receiver operating characteristic curve analyses.

RESULTS

Fifteen urinary proteins related to the regulation of the actin cytoskeleton were identified in urinary exosomes. Three upregulated proteins were selected, including Serine/threonine-protein kinase PAK6 (PAK6), Epidermal growth factor receptor (EGFR), and SHC-transforming protein 1(SHC1). The expression level of PAK6 and EGFR was negatively correlated with estimated glomerular filtration rate and positively correlated with serum creatinine levels. For diagnosing DN in the discovery phase: the area under curve (AUC) of PAK6 was 0.903, EGFR was 0.842, and the combination of two proteins was 0.912. These better performances were also observed in the validation phase (For PAK6: AUC = 0.829; For EGFR: AUC = 0.797; For PAK6 + EGFR: AUC = 0.897).

CONCLUSIONS

Urinary exosome proteins PAK6 and EGFR may be promising and noninvasive biomarkers for diagnosing DN.

Urinary exosomes: a promising biomarker of drug-induced nephrotoxicity

Drug-induced nephrotoxicity (DIN) is a big concern for clinical medication, but the clinical use of certain nephrotoxic drugs is still inevitable. Current testing methods make it hard to detect early renal injury accurately. In addition to understanding the pathogenesis and risk factors of drug-induced nephrotoxicity, it is crucial to identify specific renal injury biomarkers for early detection of DIN. Urine is an ideal sample source for biomarkers related to kidney disease, and urinary exosomes have great potential as biomarkers for predicting DIN, which has attracted the attention of many scholars. In the present paper, we will first introduce the mechanism of DIN and the biogenesis of urinary exosomes. Finally, we will discuss the changes in urinary exosomes in DIN and compare them with other predictive indicators to enrich and boost the development of biomarkers of DIN.

The Fatal Role of Enterohaemorrhagic Escherichia coli Shiga Toxin-associated Extracellular Vesicles in Host Cells

Enterohemorrhagic Escherichia coli (EHEC) is a specific subset of Shiga toxin-producing Escherichia coli (STEC) strains that are characterized by their ability to cause bloody diarrhea (hemorrhagic colitis) and potentially life-threatening, extraintestinal complications such as hemolytic uremic syndrome (HUS), which is associated with acute renal failure., contributing to severe clinical outcomes. The Shiga toxins (Stxs), produced by EHEC, are primary virulence factors. These potent cytotoxins are composed of one enzymatically active A subunit (StxA) and five receptor-binding B subunits (StxB). Although the toxins are primarily associated with cytotoxic effects, they also elicit other pathogenic consequences due to their induction of a number of biological processes, including apoptosis through ER-stress, pro-inflammatory responses, autophagy, and post-translational modification (PTM). Moreover, several studies have reported the association between Stxs and extracellular vesicles (EVs), including microvesicles and exosomes, demonstrating that Stx-containing EVs secreted by intoxicated macrophages are taken up by recipient cells, such as toxin-sensitive renal proximal tubular epithelial cells. This mechanism likely contributes to the spreading of Stxs within the host, and may exacerbate gastrointestinal illnesses and kidney dysfunction. In this review, we summarize recent findings relating to the host responses, in different types of cells in vitro and in animal models, mediated by Stxs-containing exosomes. Due to their unique properties, EVs have been explored as therapeutic agents, drug delivery systems, and diagnostic tools. Thus, potential therapeutic applications of EVs in EHEC Stxs-mediated pathogenesis are also briefly reviewed.

Extracellular vesicles: Focus on peri-implantation period of pregnancy in pigs

The establishment of cell-to-cell communication between the endometrium and the developing embryo is the most important step in successful mammalian pregnancy. Close interaction between the uterine luminal epithelium and trophoblast cells requires triggering timely molecular dialog for successful maternal recognition of pregnancy, embryo implantation, and placenta development. Quite recently, extracellular vesicles (EVs) carrying unique molecular cargo emerged as evolutionarily conserved mediators of cell-to-cell communication during early pregnancy. To date, the presence of EVs at the embryo-maternal interface has been demonstrated in numerous mammals, including domestic livestock, such as pigs. However, few studies have focused on revealing the mechanism of EV-mediated crosstalk between developing early embryos and receptive endometrium. Over the past years, it has appeared that understanding the role of EVs in mammalian reproduction can substantially improve our understanding of the biological challenges of successful reproductive performance. This review describes current knowledge of EVs, specifically in relation to the peri-implantation period in pigs, characterized by common features of embryo implantation and high embryonic mortality in mammals.

Comparison of proteomic landscape of extracellular vesicles in pleural effusions isolated by three strategies

Extracellular vesicles (EVs) derived from pleural effusion (PE) is emerging as disease biomarkers. However, the methods for isolation of EVs from PE (pEVs) were rarely studied. In our study, three methods for isolating pEVs of lung cancer patients were compared, including ultracentrifugation (UC), a combination of UC and size exclusion chromatography (UC-SEC) and a combination of UC and density gradient ultracentrifugation (UC-DGU). The subpopulation of pEVs was identified by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), Western blotting (WB) and nano-flow cytometry (nFCM). Additionally, the proteomic landscape of pEVs was analyzed by Label-free proteomics. The results showed that, compared with UC and UC-DGU, the UC-SEC method separated pEVs with the highest purity. In the proteomic analysis, on average, 1595 proteins were identified in the pEVs isolated by UC-SEC, much more than pEVs isolated by UC (1222) or UC-DGU (807). Furthermore, approximately 90% of identified proteins in each method were found in the EVs public database ExoCarta. Consistent with this, GO annotation indicated that the core proteins identified in each method were mainly enriched in "extracellular exosome." Many of the top 100 proteins with high expression in each method were suggested as protein markers to validate the presence of EVs in the MISEV2018 guidelines. In addition, combined with lung tissue-specific proteins and vesicular membrane proteins, we screened out and validated several novel protein markers (CD11C, HLA DPA1 and HLA DRB1), which were enriched in pEVs rather than in plasma EVs. In conclusion, our study shows that the method of UC-SEC could significantly improve the purity of EVs and the performance of mass spectrometry-based proteomic profiling in analyzing pEVs. The exosomal proteins CD11C, HLA DPA1 and HLA DRB1 may act as potential markers of pEVs. The proteomic analysis of pEVs provides important information and new ideas for studying diseases complicated with PE.

Urinary extracellular vesicles carry valuable hints through mRNA for the understanding of endocrine hypertension

Urinary extracellular vesicles (uEVs), released from cells of the urogenital tract organs, carry precious information about originating tissues. The study of molecules transported through uEVs such as proteins, lipids and nucleic acids provides a deeper understanding of the function of the kidney, an organ involved in the pathogenesis of hypertension and a target of hypertension-mediated organ damage. Molecules derived from uEVs are often proposed for the study of disease pathophysiology or as possible disease diagnostic and prognostic biomarkers. Analysis of mRNA loading within uEVs may be a unique and readily obtainable way to assess gene expression patterns of renal cells, otherwise achievable only by an invasive biopsy procedure. Interestingly, the only few studies investigating transcriptomics of hypertension-related genes through the analysis of mRNA from uEVs are inherent to mineralocorticoid hypertension. More specifically, it has been observed that perturbation in human endocrine signalling through mineralcorticoid receptors (MR) activation parallels changes of mRNA transcripts in urine supernatant. Furthermore, an increased copy number of uEVs-extracted mRNA transcripts of the 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2) gene were detected among subjects affected by apparent mineralocorticoid excess (AME), a hypertension-inducing autosomal recessive disorder due to a defective enzyme function. Moreover, by studying uEVs mRNA, it was observed that the renal sodium chloride cotransporter (NCC) gene expression is modulated under different conditions related to hypertension. Following this perspective, we illustrate here the state of the art and the possible future of uEVs transcriptomics towards a deeper knowledge of hypertension pathophysiology and ultimately more tailored investigational, diagnostic-prognostic approaches.

Identification and analysis of the predictive urinary exosomal miR-195-5p in lupus nephritis based on renal miRNA-mRNA co-expression network

OBJECTIVE

Lupus nephritis (LN) is the main complication of systemic lupus erythematosus (SLE), causing huge financial burden and poor quality of life. Due to the low compliance of renal biopsy, we aim to find a non-invasive biomarker of LN to optimize its predictive, preventive, and personalized medical service or management.

METHOD

Herein, we provided a bioinformatic screen combined clinical validation strategy for rapidly mining exosomal miRNAs for LN diagnosis and management. We screened out differentially expressed miRNAs (DEMs) and differentially expressed mRNAs (DEGs) in LN database and performed a miRNA-mRNA integrated analysis to select out reliable changed miRNAs in LN tissues by using R and Cytoscape. Urinary exosomes were collected by ultracentrifugation and analyzed by nano-tracking analysis and western blotting. Detection of aquaporin-2 showed the tubular source of urinary exosomes. Urinary exosomal miRNAs were detected by RT-qPCR and the target of miR-195-5p was verified by using bioinformatic, dual-luciferase, and western blotting.

RESULT

15 miRNAs and their 60 target mRNAs were contained in miRNA-mRNA integrated map. Bioinformatic analysis showed these miRNAs were involved in various cellular biological process. Exosomal miR-195-5p, miR-25-3p, miR-429, and miR-218-5p were verified in a small clinical group (n = 47). Urinary exosomal miR-195-5p, miR-25-3p, and miR-429 were downregulated in patients and miR-195-5p could recognize LN patients from SLE with good sensitivity and specificity, showing good potential in LN disease monitoring and diagnosis.

CONCLUSION

We analyzed and obtained a series of differential miRNAs in LN kidney tissues and suggested that urinary exosomal miR-195-5p could serve as a novel biomarker in LN. Further, miR-195-5p-CXCL10 axis could be a therapeutic target of LN.