Extracellular vesicles, the liquid biopsy of the future

Liver-based inter-organ communication: A disease perspective

Inter-organ communication through hormones, cytokines and extracellular vesicles (EVs) has emerged to contribute to the physiological states and pathological processes of the human body. Notably, the liver coordinates multiple tissues and organs to maintain homeostasis and maximize energy utilization, with the underlying mechanisms being unraveled in recent studies. Particularly, liver-derived EVs have been found to play a key role in regulating health and disease. As an endocrine organ, the liver has also been found to perform functions via the secretion of hepatokines. Investigating the multi-organ communication centered on the liver, especially in the manner of EVs and hepatokines, is of great importance to the diagnosis and treatment of liver-related diseases. This review summarizes the crosstalk between the liver and distant organs, including the brain, the bone, the adipose tissue and the intestine in noticeable situations. The discussion of these contents will add to a new dimension of organismal homeostasis and shed light on novel theranostics of pathologies.

Decrease of exosomal miR-21-5p and the increase of CD62p+ exosomes are associated with the development of sepsis in polytraumatized patients

Sepsis as a severe systemic inflammation leads oftentimes to organ dysfunction and subsequently to death. In polytrauma patients, septic complications represent with 45% the predominant cause of late death and are responsible for extremely high costs in the healthcare system. Therefore, clinicians have to detect as early as possible the begin of sepsis to improve the patient's outcome. One new promising diagnostic tool to diagnose septic complications in polytraumatized patients are exosomes. Plasma samples from polytraumatized patients (Injury Severity Score (ISS) ≥16) which developed sepsis (n = 10) and without sepsis (n = 10), were collected at emergency room (ER), 24h and 5 days after trauma. The EVs subpopulations were investigated by a bead-based multiplex flow cytometry measurement of surface epitopes and were compared with plasma EVs from healthy controls (n = 10). Moreover, exosomal cytokine concentrations were measured via high-sensitive ELISA and were correlated with systemic concentrations. For miRNA cargo analysis, we analysed the miRNAs miR-1298-5p, miR-1262, miR-125b-5p, miR-92a-3p, miR-93-5p, miR-155-5p and miR-21-5p and compared their exosomal concentrations by means of RT-qPCR. CD62p + exosomes were significantly increased in septic polytrauma-patients (p ≤ 0.05), while CD40+exosomes, as well as CD49e + exosomes were diminished (p ≤ 0.05). Furthermore, we observed that the exosomal IL-6 concentration reflects the systemic IL-6 concentration (r2 = 0.63) and did not significantly alter between patients with and without sepsis. The exosomal IL-10 concentration seemed to be constant in all patients and healthy controls. We observed that a decrease of miR-21-5p in exosomes was associated with the development of sepsis (p ≤ 0.05), while exosomal miR-93-5p, miR-155-5p and miR-92a-3p were not specifically altered in septic patients. Taken together, the present study in polytraumatized patients demonstrated that the development of sepsis is associated with an increase of CD62p + exosomes. Furthermore, the exosomal cargo was changed in septic patients: miR-21-5p was diminished.

Semaglutide Modulates Extracellular Matrix Production of LX-2 Cells via Exosomes and Improves Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD) is closely related to some metabolic disorders, such as central obesity and type 2 diabetes (T2D). Glucagon-like peptide 1 receptor agonists (GLP-1RAs), such as semaglutide, may have therapeutic roles in MASLD associated with T2D. This study aims to investigate the molecular mechanisms underlying the effectiveness of semaglutide on MASLD in terms of progression from liver steatosis to fibrosis. We characterized exosomes from ten patients with type 2 diabetes (T2D) before (T0) and after 12 months (T12) of treatment with once-weekly subcutaneous semaglutide. Six of ten patients were considered responders to therapy (R) based on MASLD severity downgrading by at least one class according to a validated ultrasonographic (US) score. Normal hepatocytes (HEPA-RG) and stellate (LX-2) cells were challenged with exosomes from R and NR patients, isolated before and after 12 months of therapy. Exosomes from both R and NR patients isolated at T0 significantly affected LX-2 viability. After 12 months of treatment, only those isolated from R patients restored cell viability, whereas those from NR patients did not. No effects were observed on HEPA-RG cells. Exosomes at T12 from R but not from NR patients significantly decreased the production of α-SMA, a marker of LX-2 activation, a liver stellate cell model, and ph-SMAD2 and CTGF, involved in fibrosis processes. TGF-β1 was not modulated by the exosomes of R and NR patients. As a downstream effect, Vimentin, Collagen 1A1, and Fibronectin extracellular matrix components were also downregulated, as measured by droplets digital PCR. In conclusion, these results shed light on the potential effectiveness of semaglutide in improving liver fibrosis in MASLD.

The non-vesicle cell-free DNA (cfDNA) induces cell transformation associated with horizontal DNA transfer

BACKGROUND

Cell-free DNA (cfDNA) is a source for liquid biopsy used for cancer diagnosis, therapy selection, and disease monitoring due to its non-invasive nature and ease of extraction. However, cfDNA also participates in cancer development and progression by horizontal transfer. In humans, cfDNA circulates complexed with extracellular vesicles (EV) and macromolecular complexes such as nucleosomes, lipids, and serum proteins. The present study aimed to demonstrate whether cfDNA not associated with EV induces cell transformation and tumorigenesis.

METHODS

Supernatant of the SW480 human colon cancer cell line was processed by ultracentrifugation to obtain a soluble fraction (SF) and a fraction associated with EV (EVF). Primary murine embryonic fibroblast cells (NIH3T3) underwent passive transfection with these fractions, and cell proliferation, cell cycle, apoptosis, cell transformation, and tumorigenic assays were performed. Next, cfDNA was analyzed by electronic microscopy, and horizontal transfer was assessed by human mutant KRAS in recipient cells via PCR and recipient cell internalization via fluorescence microscopy.

RESULTS

The results showed that the SF but not the EVF of cfDNA induced proliferative and antiapoptotic effects, cell transformation, and tumorigenesis in nude mice, which were reduced by digestion with DNAse I and proteinase K. These effects were associated with horizontal DNA transfer and cfDNA internalization into recipient cells.

CONCLUSIONS

The results suggest pro-tumorigenic effects of cfDNA in the SF that can be offset by enzyme treatment. Further exploration of the horizontal tumor progression phenomenon mediated by cfDNA is needed to determine whether its manipulation may play a role in cancer therapy.

Advancements in Mid-Infrared spectroscopy of extracellular vesicles

Extracellular vesicles (EVs) are lipid vesicles secreted by all cells into the extracellular space and act as nanosized biological messengers among cells. They carry a specific molecular cargo, composed of lipids, proteins, nucleic acids, and carbohydrates, which reflects the state of their parent cells. Due to their remarkable structural and compositional heterogeneity, characterizing EVs, particularly from a biochemical perspective, presents complex challenges. In this context, mid-infrared (IR) spectroscopy is emerging as a valuable tool, providing researchers with a comprehensive and label-free spectral fingerprint of EVs in terms of their specific molecular content. This review aims to provide an up-to-date critical overview of the major advancements in mid-IR spectroscopy of extracellular vesicles, encompassing both fundamental and applied research achievements. We also systematically emphasize the new possibilities offered by the integration of emerging cutting-edge IR technologies, such as tip-enhanced and surface-enhanced spectroscopy approaches, along with the growing use of machine learning for data analysis and spectral interpretation. Additionally, to assist researchers in navigating this intricate subject, our manuscript includes a wide and detailed collection of the spectral peaks that have been assigned to EV molecular constituents up to now in the literature.

Exosomes Derived from Human Adipose Mesenchymal Stem Cells Inhibits Fibrosis and Treats Oral Submucous Fibrosis via the miR-181a-5p/Smad2 Axis

BACKGROUND

Oral submucous fibrosis (OSF) is a chronic disease with carcinogenic tendency that poses a non-negligible threat to human health. Exosomes derived from human adipose mesenchymal stem cells (ADSC-Exo) reduces visceral and cutaneous fibroses, but their role in OSF has received little attention. The aim of this study was to investigate the effects of ADSC-Exo on OSF and elucidate the mechanism.

METHODS

In brief, ADSCs were extracted from adipose tissues and subjected to flow cytometry and induction culture. Fibroblasts were isolated from human buccal mucosa and subjected to immunofluorescence. Myofibroblasts were obtained from fibroblasts induced by arecoline and identified. Immunofluorescence assay confirmed that myofibroblasts could take up ADSC-Exo. The effects of ADSC-Exo on the proliferative and migratory capacities of myofibroblasts were examined using the Cell Counting Kit-8 and scratch assay. Real-time quantitative polymerase chain reaction (qPCR) was performed to evaluate mothers against decapentaplegic homolog 2 (Smad2), Smad3, Smad7, collagen type 1 (Col1), Col3, alpha smooth muscle actin (α-SMA), fibronectin, and vimentin. Western blotting was performed to detect phospho (p)-Smad2, Smad2, p-Smad2/3, Smad2/3, Smad7, Col1, Col3, α-SMA, fibronectin, and vimentin. Furthermore, the dual-luciferase reporter assay was performed to prove that miR-181a-5p in ADSC-Exo directly inhibited the expression of Smad2 mRNA to regulate the transforming growth factor beta (TGF-β) pathway. We also performed qPCR and western blotting to verify the results.

RESULTS

ADSC-Exo could promote the proliferation and migration of myofibroblasts, reduce the expressions of p-smad2, Smad2, p-smad2/3, Smad2/3, Col1, αSMA, fibronectin, and vimentin and elevated the levels of Smad7 and Col3. In addition, miR-181a-5p was highly expressed in ADSC-Exo and bound to the 3'-untranslated region of Smad2. ADSC-Exo enriched with miR-181a-5p reduced collagen production in myofibroblasts and modulated the TGF-β pathway.

CONCLUSIONS

ADSC-Exo promoted the proliferative and migratory capacities of myofibroblasts and inhibited collagen deposition and trans-differentiation of myofibroblasts in vitro. miR-181a-5p in exosomes targets Smad2 to regulate the TGF-β pathway in myofibroblasts. ADSC-Exo perform antifibrotic actions through the miR-181a-5p/Smad2 axis and may be a promising clinical treatment for OSF.

Genome-wide analysis of circulating tumor DNA methylation profiles in cerebrospinal fluid: a clinical trial of oncolytic virus for glioblastoma

Glioblastoma (GBM) is a common malignant tumor of the central nervous system with a poor prognosis and a short survival period. A novel tumor oncolytic virus, Ad-TD-nsIL-12, has manifested anti-tumor properties in preclinical studies. However, the genetic changes caused by Ad-TD-nsIL-12 after GBM treatment are unclear. Therefore, we collected cerebrospinal fluid and tumor tissues from patients injected with Ad-TD-nsIL-12 at different time points and analyzed the methylation and expression profiles of cerebrospinal fluid-derived circulating tumor DNA (ctDNA). The differential genes were screened using the least absolute selection and shrinkage operator (LASSO) and Cox regression analyses. The CIBERSORT algorithm was used to assess the abundance of glioma immune cell infiltration in The Cancer Genome Atlas (TCGA) dataset. The role of hub genes in the diagnosis, prognosis, and immune cell correlation was analyzed using R software, SPSS software, and GraphPad Prism. The results showed that after Ad-TD-nsIL-12 injection, 3631 differential methylation regions (DMRs) were up-regulated and 497 DMRs were down-regulated. The methylation levels of these DMRs recovered within 70 to 82 days. Combined with the TCGA dataset, 8 key genes were selected for the construction of diagnostic and prognostic models. There was a significant correlation between core genes and immune cells. The results revealed that the hub genes in CSF could be used as a biomarker for the diagnosis and prognosis of GBM and led us to speculate the effect of the hub gene on the immune mechanism underlying Ad-TD-nsIL-12.

Liquid biopsy biomarkers to guide immunotherapy in breast cancer

Immune checkpoint inhibitors (ICIs) therapy has emerged as a promising treatment strategy for breast cancer (BC). However, current reliance on immunohistochemical (IHC) detection of PD-L1 expression alone has limited predictive capability, resulting in suboptimal efficacy of ICIs for some BC patients. Hence, developing novel predictive biomarkers is indispensable to enhance patient selection for immunotherapy. In this context, utilizing liquid biopsy (LB) can provide supplementary or alternative value to PD-L1 IHC testing for identifying patients most likely to benefit from immunotherapy and exhibit favorable responses. This review discusses the predictive and prognostic value of LB in breast cancer immunotherapy, as well as its limitations and future directions. We aim to promote the individualization and precision of immunotherapy in BC by elucidating the role of LB in clinical practice.

Extracellular Vesicles as Therapeutic and Diagnostic Tools for Chronic Liver Diseases

Chronic liver diseases can lead to fibrotic changes that may progress to the development of cirrhosis, which poses a significant risk for morbidity and increased mortality rates. Metabolic dysfunction-associated steatotic liver disease (MASLD), alcohol-associated liver disease (ALD), and viral hepatitis are prevalent liver diseases that may lead to cirrhosis. The advanced stages of cirrhosis can be further complicated by cancer development or end-stage liver disease and liver failure. Hence, early detection and diagnosis of liver fibrosis is crucial for preventing the progression to cirrhosis and improving patient outcomes. Traditionally, invasive liver biopsy has been considered the gold standard for diagnosing and staging liver fibrosis. In the last decade, research has focused on non-invasive methods, known as liquid biopsies, which involve the identification of disease-specific biomarkers in human fluids, such as blood. Among these alternative approaches, extracellular vesicles (EVs) have emerged as promising diagnostic and therapeutic tools for various diseases, including chronic liver diseases. EVs are released from stressed or damaged cells and can be isolated and quantified. Moreover, EVs facilitate cell-to-cell communication by transporting various cargo, and they have shown the potential to reduce the expression of profibrogenic markers, making them appealing tools for novel anti-fibrotic treatments. This review focuses on the impact of EVs in chronic liver diseases and exploring their potential applications in innovative therapeutic and diagnostic approaches.

Detection of lineage-reprogramming efficiency of tumor cells in a 3D-printed liver-on-a-chip model

Background: The liver metastasis accompanied with the loss of liver function is one of the most common complications in patients with triple-negative breast cancers (TNBC). Lineage reprogramming, as a technique direct inducing the functional cell types from one lineage to another lineage without passing through an intermediate pluripotent stage, is promising in changing cell fates and overcoming the limitations of primary cells. However, most reprogramming techniques are derived from human fibroblasts, and whether cancer cells can be reversed into hepatocytes remains elusive. Methods: Herein, we simplify preparation of reprogramming reagents by expressing six transcriptional factors (HNF4A, FOXA2, FOXA3, ATF5, PROX1, and HNF1) from two lentiviral vectors, each expressing three factors. Then the virus was transduced into MDA-MB-231 cells to generated human induced hepatocyte-like cells (hiHeps) and single-cell sequencing was used to analyze the fate for the cells after reprogramming. Furthermore, we constructed a Liver-on-a-chip (LOC) model by bioprinting the Gelatin Methacryloyl hydrogel loaded with hepatocyte extracellular vesicles (GelMA-EV) bioink onto the microfluidic chip to assess the metastasis behavior of the reprogrammed TNBC cells under the 3D liver microenvironment in vitro. Results: The combination of the genes HNF4A, FOXA2, FOXA3, ATF5, PROX1 and HNF1A could reprogram MDA-MB-231 tumor cells into human-induced hepatocytes (hiHeps), limiting metastasis of these cells. Single-cell sequencing analysis showed that the oncogenes were significantly inhibited while the liver-specific genes were activated after lineage reprogramming. Finally, the constructed LOC model showed that the hepatic phenotypes of the reprogrammed cells could be observed, and the metastasis of embedded cancer cells could be inhibited under the liver microenvironment. Conclusion: Our findings demonstrate that reprogramming could be a promising method to produce hepatocytes and treat TNBC liver metastasis. And the LOC model could intimate the 3D liver microenvironment and assess the behavior of the reprogrammed TNBC cells.

Role of EpCAM+ CD133+ extracellular vesicles in steatosis to steatohepatitis transition in NAFLD

BACKGROUND AND AIMS

Extracellular vesicles (EVs) have emerged as a potential source of circulating biomarkers in liver disease. We evaluated circulating AV+ EpCAM+ CD133+ EVs as a potential biomarker of the transition from simple steatosis to steatohepatitis.

METHODS

EpCAM and CD133 liver proteins and EpCAM+ CD133+ EVs levels were analysed in 31 C57BL/6J mice fed with a chow or high fat, high cholesterol and carbohydrates diet (HFHCC) for 52 weeks. The hepatic origin of MVs was addressed using AlbCrexmT/mG mice fed a Western (WD) or Dual diet for 23 weeks. Besides, we assessed plasma MVs in 130 biopsy-proven NAFLD patients.

RESULTS

Hepatic expression of EpCAM and CD133 and EpCAM+ CD133+ EVs increased during disease progression in HFHCC mice. GFP+ MVs were higher in AlbCrexmT/mG mice fed a WD (5.2% vs 12.1%) or a Dual diet (0.5% vs 7.3%). Most GFP+ MVs were also positive for EpCAM and CD133 (98.3% and 92.9% respectively), suggesting their hepatic origin. In 71 biopsy-proven NAFLD patients, EpCAM+ CD133+ EVs were significantly higher in those with steatohepatitis compare to those with simple steatosis (286.4 ± 61.9 vs 758.4 ± 82.3; p < 0.001). Patients with ballooning 367 ± 40.6 vs 532.0 ± 45.1; p = 0.01 and lobular inflammation (321.1 ± 74.1 vs 721.4 ± 80.1; p = 0.001), showed higher levels of these EVs. These findings were replicated in an independent cohort.

CONCLUSIONS

Circulating levels of EpCAM+ CD133+ MVs in clinical and experimental NAFLD were increased in the presence of steatohepatitis, showing high potential as a non-invasive biomarker for the evaluation and management of these patients.

Diagnostic and Prognostic Potential of Exosomal Cytokines IL-6 and IL-10 in Polytrauma Patients

Trauma remains a leading cause of morbidity and mortality. Polytraumatized patients need a precise, early diagnosis to avoid complications such as multiorgan failure or sepsis. Inflammatory cytokines, commonly used for diagnosis, have a short half-life, which limits their efficacy as a diagnostic or prognostic marker. In this study, we hypothesized that cytokines in exosomes could have a longer half-life, and therefore could be used as diagnostic and prognostic markers in polytrauma patients. Plasma samples from polytraumatized patients (ISS ≥ 16, n = 18) were collected in the emergency room (ER) 1, 2, 3 and 5 days after trauma. Plasma-exosomes were isolated via size exclusion chromatography from polytraumatized patients and healthy volunteers (n = 10). The systemic and exosomal concentrations of interleukin (IL)-6, IL-10, IL-1β and TNF were measured using high-sensitive ELISAs. To investigate the diagnostic and prognostic potential of exosomal cytokines, data were correlated with clinical outcome parameters (injury severity, ventilation time, time in ICU and survival) documented in the patients' electronic records. Despite the use of high-sensitive ELISAs, IL-1β and TNF alpha were not detected in exosomes. IL-6 and IL-10 were detectable in polytraumatized patient exosomes at all time points. A decrease over time of both systemic and exosomal IL-6 concentrations was observed. Furthermore, exosomal and systemic IL-6 concentrations moderately correlated (r = 0.63). Exosomal IL-6 in the ER moderately correlated with the Injury Severity Score (ISS) (mean 35.5 ± 11.5) (r = 0.45) and was associated with non-survival in polytrauma patients (p < 0.05). In contrast to IL-6, no correlation between systemic and exosomal IL-10 concentrations was found. Exosomal IL-10 concentrations remained unchanged throughout the observation time, whereas systemic IL-10 concentrations peaked in the ER and were significantly reduced after 24 h. Data from this study support our hypothesis that some cytokines (IL-10), but not all (IL-6), are detectable in exosomes significantly longer than they are in plasma. This might indicate that they are protected from degradation. Although we did not find a correlation between IL-10 exosomal concentration and patient outcome, our data confirm that exosomal cytokines are of interest as potential diagnostic and prognostic markers in polytrauma patients, and require further detailed research.

Immune microenvironment changes of liver cirrhosis: emerging role of mesenchymal stromal cells

Cirrhosis is a progressive and diffuse liver disease characterized by liver tissue fibrosis and impaired liver function. This condition is brought about by several factors, including chronic hepatitis, hepatic steatosis, alcohol abuse, and other immunological injuries. The pathogenesis of liver cirrhosis is a complex process that involves the interaction of various immune cells and cytokines, which work together to create the hepatic homeostasis imbalance in the liver. Some studies have indicated that alterations in the immune microenvironment of liver cirrhosis are closely linked to the development and prognosis of the disease. The noteworthy function of mesenchymal stem cells and their paracrine secretion lies in their ability to promote the production of cytokines, which in turn enhance the self-repairing capabilities of tissues. The objective of this review is to provide a summary of the alterations in liver homeostasis and to discuss intercellular communication within the organ. Recent research on MSCs is yielding a blueprint for cell typing and biomarker immunoregulation. Hopefully, as MSCs researches continue to progress, novel therapeutic approaches will emerge to address cirrhosis.

Extracellular Vesicles in Hepatobiliary Health and Disease

Extracellular vesicles (EVs) are membrane-bound nanoparticles released by cells and are an important means of intercellular communication in physiological and pathological states. We provide an overview of recent advances in the understanding of EV biogenesis, cargo selection, recipient cell effects, and key considerations in isolation and characterization techniques. Studies on the physiological role of EVs have relied on cell-based model systems due to technical limitations of studying endogenous nanoparticles in vivo . Several recent studies have elucidated the mechanistic role of EVs in liver diseases, including nonalcoholic fatty liver disease, viral hepatitis, cholestatic liver disease, alcohol-associated liver disease, acute liver injury, and liver cancers. Employing disease models and human samples, the biogenesis of lipotoxic EVs downstream of endoplasmic reticulum stress and microvesicles via intracellular activation stress signaling are discussed in detail. The diverse cargoes of EVs including proteins, lipids, and nucleic acids can be enriched in a disease-specific manner. By carrying diverse cargo, EVs can directly confer pathogenic potential, for example, recruitment and activation of monocyte-derived macrophages in NASH and tumorigenicity and chemoresistance in hepatocellular carcinoma. We discuss the pathogenic role of EVs cargoes and the signaling pathways activated by EVs in recipient cells. We review the literature that EVs can serve as biomarkers in hepatobiliary diseases. Further, we describe novel approaches to engineer EVs to deliver regulatory signals to specific cell types, and thus use them as therapeutic shuttles in liver diseases. Lastly, we identify key lacunae and future directions in this promising field of discovery and development. © 2023 American Physiological Society. Compr Physiol 13:4631-4658, 2023.

Release of exosomes in polytraumatized patients: The injury pattern is reflected by the surface epitopes

Background

Trauma is still a leading cause of morbidity and mortality, especially in the younger population. Trauma patients need a precise, early diagnostic to avoid complications like multiorgan failure and sepsis. Exosomes were described as markers and mediators in trauma. The aim of the present study was to analyze, whether the surface epitopes of plasma-exosomes can reflect the injury pattern in polytrauma.

Material and Methods

Polytraumatized patients (Injury Severity Score = ISS ≥16, n = 38) were subdivided according to the predominant injury in either abdominal trauma, chest trauma or traumatic brain injury (TBI). Plasma exosomes were isolated via size exclusion chromatography. The concentration and size distribution of the plasma exosomes from emergency room samples were measured by nanoparticle tracking analysis. The exosomal surface antigens were investigated by bead-based multiplex flow cytometry and compared with healthy controls (n=10).

Results

In contrast to other studies, we did not observe an increase in the total amount of plasma exosomes in polytrauma patients (1,15x109 vs. 1,13x109 particles/ml), but found changes in the exosomal surface epitopes. We found a significant reduction of CD42a+ (platelet-derived) exosomes in polytrauma patients, CD209+ (dendritic cell-derived) exosomes in the patients with predominant abdominal trauma, and CD11+ (monocyte-derived) exosomes in the patients with chest trauma. The group of patients with TBI was characterized in contrast by an increase of CD62p+ (endothelial/platelet-derived) exosomes (*p&lt;0.05).

Conclusion

Our data showed that the polytrauma injury pattern might be reflected by the cellular origin/surface epitopes of plasma-released exosomes immediately after trauma. The observed reduction of CD42+ exosomes in polytrauma patients was not associated with a reduction of total platelets in polytrauma patients.

THE ROLES OF EXTRACELLULAR VESICLES IN SEPSIS AND SYSTEMIC INFLAMMATORY RESPONSE SYNDROME

ABSTRACT

Sepsis is a life-threatening organ dysfunction, caused by dysregulation of the host response to infection. To understand the underlying mechanisms of sepsis, the vast spectrum of extracellular vesicles (EVs) is gaining importance in this research field. A connection between EVs and sepsis was shown in 1998 in an endotoxemia pig model. Since then, the number of studies describing EVs as markers and mediators of sepsis increased steadily. Extracellular vesicles in sepsis could be friends and foes at the same time depending on their origin and cargo. On the one hand, transfer of EVs or outer membrane vesicles can induce sepsis or systemic inflammatory response syndrome with comparable efficiency as well-established methods, such as cecal ligation puncture or lipopolysaccharide injection. On the other hand, EVs could provide certain therapeutic effects, mediated via reduction of reactive oxygen species, inflammatory cytokines and chemokines, influence on macrophage polarization and apoptosis, as well as increase of anti-inflammatory cytokines. Moreover, EVs could be helpful in the diagnosis of sepsis. Extracellular vesicles of different cellular origin, such as leucocytes, macrophages, platelets, and granulocytes, have been suggested as potential sepsis biomarkers. They ensure the diagnosis of sepsis earlier than classical clinical inflammation markers, such as C-reactive protein, leucocytes, or IL-6. This review summarizes the three roles of EVs in sepsis-mediator/inducer, biomarker, and therapeutic tool.

Extracellular vesicles in fatty liver disease and steatohepatitis: Role as biomarkers and therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) and alcohol-associated liver disease (ALD) are characterized by lipid deposition in hepatocytes in the absence or presence of excessive alcohol consumption, respectively, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH) or alcoholic hepatitis (AH) and from mild fibrosis to cirrhosis. Fatty liver disease and steatohepatitis similarly occur in individuals who have both metabolic syndrome and excessive alcohol intake; therefore, the single overarching term metabolic associated fatty liver disease (MAFLD) has been proposed to better reflect these risk factors and the continuity of disease progression. Extracellular vesicles (EVs) are membrane-bound endogenous nanoparticles released into the extracellular space by a majority of cell types. Liver disease-related EVs contain a variety of cellular cargo and are internalized into target cells resulting in the transfer of bioinformation reflecting the state of the donor cell to the recipient. Furthermore, EV composition can be used to identify the degree and type of liver disease, suggesting that EV composition may be a useful biomarker. With regard to MAFLD, the presence of metabolic risk factors, such as insulin resistance, will be indicated by adipose tissue-derived EVs and with that comes the potential to use as a clinical monitor of overall metabolic status. However, the inhibition of specific EV composition may be difficult to implement as a real-world therapeutic approach. Current global evidence shows that mesenchymal stem cell (MSCs)-derived EVs (MSC-EVs) play an important role in regulating the immune response, which has spawned a clinical trial to treat liver disease.

Circulating Histones to Detect and Monitor the Progression of Cancer

Liquid biopsies have emerged as a minimally invasive cancer detection and monitoring method, which could identify cancer-related alterations in nucleosome or histone levels and modifications in blood, saliva, and urine. Histones, the core component of the nucleosome, are essential for chromatin compaction and gene expression modulation. Increasing evidence suggests that circulating histones and histone complexes, originating from cell death or immune cell activation, could act as promising biomarkers for cancer detection and management. In this review, we provide an overview of circulating histones as a powerful liquid biopsy approach and methods for their detection. We highlight current knowledge on circulating histones in hematologic malignancies and solid cancer, with a focus on their role in cancer dissemination, monitoring, and tumorigenesis. Last, we describe recently developed strategies to identify cancer tissue-of-origin in blood plasma based on nucleosome positioning, inferred from nucleosomal DNA fragmentation footprint, which is independent of the genetic landscape.

The potential of sertoli cells (SCs) derived exosomes and its therapeutic efficacy in male reproductive disorders

In the male reproductive system, seminiferous tubules in testis are lined by a complex stratified epithelium containing two distinct populations of cells, spermatogenic cells that develop into spermatozoa, and sertoli cells (SCs) that mainly support and nourish spermatogenic cell lineage as well as exerting powerful effect on men reproductive capacity. Different varieties of proteins, hormones, exosomes and growth factors are secreted by SCs. There are different kinds of junctions found between SCs called BTB. It was elucidated that complete absence of BTB or its dysfunction leads to infertility. To promote spermatogenesis, crosstalk of SCs with spermatogenic cells plays an important role. The ability of SCs to support germ cell productivity and development is related to its various products carrying out several functions. Exosomes (EXOs) are one of the main EVs with 30-100 nm size generating from endocytic pathway. They are produced in different parts of male reproductive system including epididymis, prostate and SCs. The most prominent characteristics of SC-based exosomes is considered mutual interaction of sertoli cells with spermatogonial stem cells and Leydig cells mainly through establishment of intercellular communication. Exosomes have gotten a lot of interest because of their role in pathobiological processes and as a cell free therapy which led to developing multiple exosome isolation methods based on different principles. Transmission of nucleic acids, proteins, and growth factors via SC-based exosomes and exosomal miRNAs are proved to have potential to be valuable biomarkers in male reproductive disease. Among testicular abnormalities, non-obstructive azoospermia and testicular cancer have been more contributed with SCs performance. The identification of key proteins and miRNAs involved in the signaling pathways related with spermatogenesis, can serve as diagnostic and regenerative targets in male infertility.

Increased expression of miR-224-5p in circulating extracellular vesicles of patients with reduced coronary flow reserve

Background

Endothelial and microvascular dysfunction are pivotal causes of major adverse cardiac events predicted by coronary flow reserve (CFR). Extracellular Vesicles (EVs) have been studied extensively in the pathophysiology of coronary artery disease. However, little is known on the impact of the non-coding RNA content of EVs with respect to CFR.

Methods

We carried out a study among 120 patients divided by high-CFR and low-CFR to profile the miRNA content of circulating EVs.

Results

A multiplex array profiling on circulating EVs revealed mir-224-5p (p-value ≤ 0.000001) as the most differentially expressed miRNA in the Low-CFR group and showed a significantly independent relationship to CFR. Literature survey indicated the origin of the miR from liver cells and not of platelet, leukocyte, smooth muscle or endothelial (EC) origin. A q-PCR panel of the conventional cell type-EVs along with hepatic EVs showed that EVs from liver cells showed higher expression of the miR-224-5p. FACS analysis demonstrated the presence of liver-specific (ASGPR-1+/CD14−) EVs in the plasma of our cohort with the presence of Vanin-1 required to enter the EC barrier. Hepatic EVs with and without the miR-224-5p were introduced to ECs in-vitro, but with no difference in effect on ICAM-1 or eNOS expression. However, hepatic EVs elevated endothelial ICAM-1 levels per se independent of the miR-224-5p.

Conclusion

This indicated a role of hepatic EVs identified by the miR-224-5p in endothelial dysfunction in patients with Low CFR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02756-w.

Protein and miRNA profile of circulating extracellular vesicles in patients with primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is an idiopathic and heterogenous cholestatic liver disease characterized by chronic inflammation and fibrosis of the biliary tree. Currently, no effective therapies are available for this condition, whose incidence is rising. At present, specificity and sensitivity of current serum markers used to diagnose PSC are limited and often unreliable. In this study, we characterize circulating extracellular vesicles and provide supporting data on their potential use as novel surrogate biomarkers for PSC. EVs are membrane surrounded structures, 100–1000 nm in size, released by cells under various conditions and which carry a variety of bioactive molecules, including small non-coding RNAs, lipids and proteins. In recent years, a large body of evidence has pointed to diagnostic implications of EVs and relative cargo in various human diseases. We isolated EVs from serum of well-characterized patients with PSC or control subjects by differential centrifugation and size-exclusion chromatography. A complete characterization identified elevated levels of circulating EVs in PSC patients compared to healthy control subjects (2000 vs. 500 Calcein-FITC + EVs/μL). Tissue and cell specificity of circulating EVs was assessed by identification of liver-specific markers and cholangiocyte marker CK-19. Further molecular characterization identified 282 proteins that were differentially regulated in PSC-derived compared to healthy control-EVs. Among those, IL-13Ra1 was the most significantly and differentially expressed protein in PSC-derived EVs and correlated with the degree of liver fibrosis. In addition to protein profiling, we performed a miRNA-sequencing analysis which identified 11 among established, liver-specific (e.g., miR-122 and miR-192) and novel miRNAs. One of the newly identified miRNAs, miR-4645-3p, was significantly up-regulated fourfold in PSC-derived EVs compared to circulating EVs isolated from healthy controls. This study provides supporting evidence of the potential role of circulating EVs and associated protein and miRNA cargo as surrogate noninvasive and reliable biomarker for PSC.

Cell-to-Cell Communications in Alcohol-Associated Liver Disease

This review covers some important new aspects of the alcohol-induced communications between liver parenchymal and non-parenchymal cells leading to liver injury development. The information exchange between various cell types may promote end-stage liver disease progression and involves multiple mechanisms, such as direct cell-to-cell interactions, extracellular vesicles (EVs) or chemokines, cytokines, and growth factors contained in extracellular fluids/cell culture supernatants. Here, we highlighted the role of EVs derived from alcohol-exposed hepatocytes (HCs) in activation of non-parenchymal cells, liver macrophages (LM), and hepatic stellate cells (HSC). The review also concentrates on EV-mediated crosstalk between liver parenchymal and non-parenchymal cells in the settings of HIV- and alcohol co-exposure. In addition, we overviewed the literature on the crosstalk between cell death pathways and inflammasome activation in alcohol-activated HCs and macrophages. Furthermore, we covered highly clinically relevant studies on the role of non-inflammatory factors, sinusoidal pressure (SP), and hepatic arterialization in alcohol-induced hepatic fibrogenesis. We strongly believe that the review will disclose major mechanisms of cell-to-cell communications pertained to alcohol-induced liver injury progression and will identify therapeutically important targets, which can be used for alcohol-associated liver disease (ALD) prevention.

Extracellular vesicles from pancreatic ductal adenocarcinoma endoscopic ultrasound-fine needle aspiration samples contain a protein barcode

BACKGROUND

The survival rate of pancreatic ductal adenocarcinoma (PDAC) is very poor because early detection is difficult. Extracellular vesicles (EVs) are released from cells associating with the cellular condition and circulated in the blood. We aimed to identify EV proteins from endoscopic ultrasound-fine needle aspiration (EUS-FNA) biopsy samples in order to develop novel biomarkers for PDAC.

METHODS

Extracellular vesicles were isolated from EUS-FNA samples of 40 PDAC patients and six autoimmune pancreatitis (AIP) patients to be used as a control. EV proteins were identified using nanoLC-MS/MS.

RESULTS

Intact EVs approximately 200 nm in diameter were detected from EUS-FNA samples. We identified 2059 or 1032 EV proteins in PDAC or AIP, respectively, and 1071 EV proteins were detected only in PDAC. One hundred and fifty-three EV proteins were significantly different between PDAC and AIP: 64 proteins were down-regulated in PDAC whereas 89 EV proteins were up-regulated in PDAC including mucins, keratins, Ras-related proteins, and olfactomedin-4, which proteins have been reported to be elevated in PDAC tissue/blood, or cultured pancreatic cancer cell lines. Notably, in the 89 up-regulated PDAC EV proteins we identified novel proteins including ADP-ribosylation factor 3, CD55, pyruvate kinase, and lipopolysaccharide-induced tumor necrosis factor. Out of 89 proteins, a total of 13 proteins including Ras-related proteins were significantly elevated in PDAC stages II-IV compared to PDAC stage I, including Ras-related proteins, moesin, and CD55.

CONCLUSIONS

The EV proteins obtained from EUS-FNA samples contain a PDAC-specific protein barcode. The EV proteins identified from EUS-FNA samples include promising biomarkers for the diagnosis and clinical staging of PDAC.

Role of extracellular vesicles in liver diseases and their therapeutic potential

More than eight hundred million people worldwide have chronic liver disease, with two million deaths per year. Recurring liver injury results in fibrogenesis, progressing towards cirrhosis, for which there doesn't exists any cure except liver transplantation. Better understanding of the mechanisms leading to cirrhosis and its complications is needed to develop effective therapies. Extracellular vesicles (EVs) are released by cells and are important for cell-to-cell communication. EVs have been reported to be involved in homeostasis maintenance, as well as in liver diseases. In this review, we present current knowledge on the role of EVs in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis, alcohol-associated liver disease, chronic viral hepatitis, primary liver cancers, acute liver injury and liver regeneration. Moreover, therapeutic strategies involving EVs as targets or as tools to treat liver diseases are summarized.

Characteristics and Clinical Application of Extracellular Vesicle-Derived DNA

Extracellular vesicles (EVs) carry RNA, proteins, lipids, and diverse biomolecules for intercellular communication. Recent studies have reported that EVs contain double-stranded DNA (dsDNA) and oncogenic mutant DNA. The advantage of EV-derived DNA (EV DNA) over cell-free DNA (cfDNA) is the stability achieved through the encapsulation in the lipid bilayer of EVs, which protects EV DNA from degradation by external factors. The existence of DNA and its stability make EVs a useful source of biomarkers. However, fundamental research on EV DNA remains limited, and many aspects of EV DNA are poorly understood. This review examines the known characteristics of EV DNA, biogenesis of DNA-containing EVs, methylation, and next-generation sequencing (NGS) analysis using EV DNA for biomarker detection. On the basis of this knowledge, this review explores how EV DNA can be incorporated into diagnosis and prognosis in clinical settings, as well as gene transfer of EV DNA and its therapeutic potential.

The Multifaceted Role of Extracellular Vesicles in Glioblastoma: microRNA Nanocarriers for Disease Progression and Gene Therapy

Glioblastoma (GB) is the most aggressive form of brain cancer in adults, characterized by poor survival rates and lack of effective therapies. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate gene expression post-transcriptionally through specific pairing with target messenger RNAs (mRNAs). Extracellular vesicles (EVs), a heterogeneous group of cell-derived vesicles, transport miRNAs, mRNAs and intracellular proteins, and have been shown to promote horizontal malignancy into adjacent tissue, as well as resistance to conventional therapies. Furthermore, GB-derived EVs have distinct miRNA contents and are able to penetrate the blood-brain barrier. Numerous studies have attempted to identify EV-associated miRNA biomarkers in serum/plasma and cerebrospinal fluid, but their collective findings fail to identify reliable biomarkers that can be applied in clinical settings. However, EVs carrying specific miRNAs or miRNA inhibitors have great potential as therapeutic nanotools in GB, and several studies have investigated this possibility on in vitro and in vivo models. In this review, we discuss the role of EVs and their miRNA content in GB progression and resistance to therapy, with emphasis on their potential as diagnostic, prognostic and disease monitoring biomarkers and as nanocarriers for gene therapy.

Circulating extracellular vesicles are a biomarker for NAFLD resolution and response to weight loss surgery

There is increasing interest in the development of minimally invasive biomarkers for the diagnosis and prognosis of NAFLD via extracellular vesicles (EV). Plasma EVs were isolated by differential ultracentrifugation and quantified by nanoparticle tracking analysis from pre (n = 28) and post (n = 28) weight loss patients. In the pre weight loss group 22 had NAFLD. Nanoplasmon enhanced scattering (nPES) of gold nanoparticles conjugated to hepatocyte-specific antibodies was employed to identify hepatocyte-specific EVs. Complex lipid panel and targeted sphingolipids were performed. Logistic regression analysis was used to identify predictors of NAFLD. Plasma levels of EVs and hepatocyte-derived EVs are dynamic and decrease following NAFLD resolution due to weight loss surgery. Hepatocyte-derived EVs correlate with steatosis in NAFLD patients and steatosis and inflammation in NASH patients. Plasma levels of small EVs correlate with EV sphingolipids in patients with NASH. Hepatocyte-derived EVs measured by the nPES assay could serve as a point-of-care test for NAFLD.

Exosomes derived from human adipose mesenchymal stem cells attenuate hypertrophic scar fibrosis by miR-192-5p/IL-17RA/Smad axis

BACKGROUND

Hypertrophic scar (HS) is a fibro-proliferative disorder of dermis after burn or trauma and usually leads to esthetic disfiguration and functionary impairment for patients. Emerging evidences demonstrated ADSC-Exo could alleviate the visceral fibrosis, but little attention had been paid to its role in skin fibrosis. In the study, we would explore the effect of ADSC-Exo on HS and investigated the exact mechanism underlying the properties.

METHODS

ADSC-Exo were isolated, identified, and internalized by HS-derived fibroblasts (HSFs). The effect of ADSC-Exo on the proliferation and migration of HSFs were detected by flow cytometry and Ki67 immunofluorescence staining, or scratch and trans-wells assays, respectively. RT-PCR, immunoblotting, immunofluorescence, and immunohistochemistry staining were used to evaluate the expression of IL-17RA, Col1, Col3, α-SMA, SIP1, and p-Smad2/p-Smad3 in HSFs stimulated with ADSC-Exo, miR-192-5p mimics, or inhibitors, IL-17RA siRNA and their negative controls. Digital morphology, H&E, Masson's trichrome staining, and immunohistochemistry staining were performed to measure the effect of ADSC-Exo and Lv-IL-17RA shRNA on excisional wound of BALB/c mice.

RESULTS

The verified ADSC-Exo effectively inhibited the proliferation and migration of HSFs, decreased the expression of Col1, Col3, α-SMA, IL-17RA, and p-Smad2/p-Smad3 and increased the levels of SIP1 in HSFs. Besides, the mice in ADSC-Exo-treated group demonstrated faster wound healing and less collagen deposition. Furthermore, miR-192-5p was highly expressed in ADSC-Exo and ADSC-Exosomal miR-192-5p ameliorated hypertrophic scar fibrosis. Meanwhile, miR-192-5p targeted the expression of IL-17RA to decrease the pro-fibrotic proteins levels. Moreover, IL-17RA was overexpressed in HS and HSFs, and knockdown IL-17RA alleviated the expression of Col1, Col3, α-SMA, and p-Smad2/p-Smad3 and increased the expression of SIP1 in HSFs. Most importantly, IL-17RA silence also facilitated wound healing, attenuated collagen production, and modulated Smad pathway in HSFs.

CONCLUSIONS

This study illustrated ADSC-Exo attenuated the deposition of collagen, the trans-differentiation of fibroblasts-to-myofibroblasts, and the formation of hypertrophic scar by in vitro and in vivo experiments. ADSC-Exosomal miR-192-5p targeted IL-17RA to regulate Smad pathway in hypertrophic scar fibrosis. ADSC-Exo could be a promising therapeutic strategy for clinical treatment of hypertrophic scar and the anti-fibrotic properties could be achieved by miR-192-5p/IL-17RA/Smad axis.

Branched-chain amino acids and l-carnitine attenuate lipotoxic hepatocellular damage in rat cirrhotic liver

Branched-chain amino acids (BCAA) reverse malnutrition and l-carnitine leads to the reduction of hyperammonemia and muscle cramps in cirrhotic patients. BCAA and l-carnitine are involved in glucose and fatty acid metabolism, however their mechanistic activity in cirrhotic liver is not fully understood. We aim to define the molecular mechanism(s) and combined effects of BCAA and l-carnitine using a cirrhotic rat model. Rats were administered carbon tetrachloride for 10 weeks to induce cirrhosis. During the last 6 weeks of administration, cirrhotic rats received BCAA, l-carnitine or a combination of BCAA and l-carnitine daily via gavage. We found that BCAA and l-carnitine treatments significantly improved hepatocellular function associated with reduced triglyceride level, lipid deposition and adipophilin expression, in cirrhotic liver. Lipidomic analysis revealed dynamic changes in hepatic lipid composition by BCAA and l-carnitine administrations. BCAA and l-carnitine globally increased molecular species of phosphatidylcholine. Liver triacylglycerol and phosphatidylcholine hydroperoxides were significantly decreased by BCAA and l-carnitine. Furthermore, serum and liver ATP levels were significantly increased in all treatments, which were attributed to the elevation of mature cardiolipins and mitochondrial component gene expressions. Finally, BCAA and l-carnitine dramatically reduced hepatocellular death. In conclusion, BCAA and l-carnitine treatments attenuate hepatocellular damage through the reduction of lipid peroxides and the overall maintenance of mitochondrial integrity within the cirrhotic liver. These effectiveness of BCAA and l-carnitine support the therapeutic strategies in human chronic liver diseases.

Extracellular vesicles as mediators and markers of acute organ injury: current concepts

Due to the continued high incidence and mortality rate worldwide, there is a need to develop new strategies for the quick, precise, and valuable recognition of presenting injury pattern in traumatized and poly-traumatized patients. Extracellular vesicles (EVs) have been shown to facilitate intercellular communication processes between cells in close proximity as well as distant cells in healthy and disease organisms. miRNAs and proteins transferred by EVs play biological roles in maintaining normal organ structure and function under physiological conditions. In pathological conditions, EVs change the miRNAs and protein cargo composition, mediating or suppressing the injury consequences. Therefore, incorporating EVs with their unique protein and miRNAs signature into the list of promising new biomarkers is a logical next step. In this review, we discuss the general characteristics and technical aspects of EVs isolation and characterization. We discuss results of recent in vitro, in vivo, and patients study describing the role of EVs in different inflammatory diseases and traumatic organ injuries. miRNAs and protein signature of EVs found in patients with acute organ injury are also debated.

The Role of Elevated Liver-Type Fatty Acid-Binding Proteins in Liver Diseases

Liver-type fatty acid-binding protein (L-FABP) is mainly expressed in the liver as well as the proximal tubular epithelial cells in the kidney. In general, the proteins and enzymes existing within the hepatocytes have the potential to become biomarkers, for instance alanine aminotransferase, which reflects hepatocellular damage. However, due to reduced hepatocellular function in late stage of chronic liver diseases (e.g. cirrhosis), proteins and enzymes relating to hepatocellular damage are not always accurate measures of disease progression. Recently, several publications have demonstrated elevated serum L-FABP levels during the progression of human liver diseases, including hepatocellular carcinoma (HCC), and were a prognostic factor for survival in acute and chronic liver disease patients. However, the study regarding serum L-FABP levels and hepatic L-FABP expression in liver diseases is not sufficient to understand the molecular mechanism of L-FABP during the progression of these disease states. In this review, we focus on the use of serum and/or hepatic L-FABP expression as a biomarker in human liver diseases, including mechanistic potential in HCC.

Circulating Extracellular Vesicles Carrying Sphingolipid Cargo for the Diagnosis and Dynamic Risk Profiling of Alcoholic Hepatitis

BACKGROUND AND AIMS

Alcoholic hepatitis (AH) is diagnosed by clinical criteria, although several objective scores facilitate risk stratification. Extracellular vesicles (EVs) have emerged as biomarkers for many diseases and are also implicated in the pathogenesis of AH. Therefore, we investigated whether plasma EV concentration and sphingolipid cargo could serve as diagnostic biomarkers for AH and inform prognosis to permit dynamic risk profiling of AH subjects.

APPROACH AND RESULTS

EVs were isolated and quantified from plasma samples from healthy controls, heavy drinkers, and subjects with end-stage liver disease (ESLD) attributed to cholestatic liver diseases and nonalcoholic steatohepatitis, decompensated alcohol-associated cirrhosis (AC), and AH. Sphingolipids were quantified by tandem mass spectroscopy. The median plasma EV concentration was significantly higher in AH subjects (5.38 × 10¹¹ /mL) compared to healthy controls (4.38 × 10¹⁰ /mL; P < 0.0001), heavy drinkers (1.28 × 10¹¹ /mL; P < 0.0001), ESLD (5.35 × 10¹⁰ /mL; P < 0.0001), and decompensated AC (9.2 × 10¹⁰ /mL; P < 0.0001) disease controls. Among AH subjects, EV concentration correlated with Model for End-Stage Liver Disease score. When EV counts were dichotomized at the median, survival probability for AH subjects at 90 days was 63.0% in the high-EV group and 90.0% in the low-EV group (log-rank P value = 0.015). Interestingly, EV sphingolipid cargo was significantly enriched in AH when compared to healthy controls, heavy drinkers, ESLD, and decompensated AC (P = 0.0001). Multiple sphingolipids demonstrated good diagnostic and prognostic performance as biomarkers for AH.

CONCLUSIONS

Circulating EV concentration and sphingolipid cargo signature can be used in the diagnosis and differentiation of AH from heavy drinkers, decompensated AC, and other etiologies of ESLD and predict 90-day survival permitting dynamic risk profiling.

Hepatic stellate cell autophagy inhibits extracellular vesicle release to attenuate liver fibrosis

BACKGROUND & AIMS

Autophagy plays a crucial role in hepatic homeostasis and its deregulation has been associated with chronic liver disease. However, the effect of autophagy on the release of fibrogenic extracellular vesicles (EVs) by platelet-derived growth factor (PDGF)-stimulated hepatic stellate cells (HSCs) remains unknown. Herein, we aimed to elucidate the role of autophagy, specifically relating to fibrogenic EV release, in fibrosis.

METHODS

In vitro experiments were conducted in primary human and murine HSCs as well as LX2 cells. Small EVs were purified by differential ultracentrifugation. Carbon tetrachloride (CCl₄) or bile duct ligation (BDL) were used to induce fibrosis in our mouse model. Liver lysates from patients with cirrhosis or healthy controls were compared by RNA sequencing.

RESULTS

In vitro, PDGF and its downstream molecule SHP2 (Src homology 2-containing protein tyrosine phosphatase 2) inhibited autophagy and increased HSC-derived EV release. We used this PDGF/SHP2 model to further investigate how autophagy affects fibrogenic EV release. RNA sequencing identified an mTOR (mammalian target of rapamycin) signaling molecule that was regulated by SHP2 and PDGF. Disruption of mTOR signaling abolished PDGF-dependent EV release. Activation of mTOR signaling induced the release of multivesicular body-derived exosomes (by inhibiting autophagy) and microvesicles (by activating ROCK1 signaling). These mTOR-dependent EVs promoted in vitro HSC migration. To assess the importance of this mechanism in vivo, SHP2 was selectively deleted in HSCs, which attenuated CCl_4- or BDL-induced liver fibrosis. Furthermore, in the CCl₄ model, mice receiving circulating EVs derived from mice with HSC-specific Shp2 deletion had less fibrosis than mice receiving EVs from control mice. Correspondingly, SHP2 was upregulated in patients with liver cirrhosis.

CONCLUSION

These results demonstrate that autophagy in HSCs attenuates liver fibrosis by inhibiting the release of fibrogenic EVs.

LAY SUMMARY

During liver fibrosis and cirrhosis, activated hepatic stellate cells (HSCs) are the key cell type responsible for fibrotic tissue deposition. Recently, we demonstrated that activated HSCs release nano-sized vesicles enriched with fibrogenic proteins. In the current study, we unveil the mechanism by which these fibrogenic vesicles are released, moving a step closer to the long-term goal of therapeutically targeting this process.

Uveal Melanoma-Derived Extracellular Vesicles Display Transforming Potential and Carry Protein Cargo Involved in Metastatic Niche Preparation

Extracellular vesicles (EVs) carry molecules derived from donor cells and are able to alter the properties of recipient cells. They are important players during the genesis and progression of tumors. Uveal melanoma (UM) is the most common primary intraocular tumor in adults and is associated with a high rate of metastasis, primarily to the liver. However, the mechanisms underlying this process are poorly understood. In the present study, we analyzed the oncogenic potential of UM-derived EVs and their protein signature. We isolated and characterized EVs from five UM cell lines and from normal choroidal melanocytes (NCMs). BRCA1-deficient fibroblasts (Fibro-BKO) were exposed to the EVs and analyzed for their growth in vitro and their reprograming potential in vivo following inoculation into NOD-SCID mice. Mass spectrometry of proteins from UM-EVs and NCM-EVs was performed to determine a protein signature that could elucidate potential key players in UM progression. In-depth analyses showed the presence of exosomal markers, and proteins involved in cell-cell and focal adhesion, endocytosis, and PI3K-Akt signaling pathway. Notably, we observed high expression levels of HSP90, HSP70 and integrin V in UM-EVs. Our data bring new evidence on the involvement of UM-EVs in cancer progression and metastasis.

Characterization and Proteome of Circulating Extracellular Vesicles as Potential Biomarkers for NASH

Nonalcoholic fatty liver disease (NAFLD) is currently one of most common forms of chronic liver disease globally. NAFLD represents a wide spectrum of liver involvement from nonprogressive isolated steatosis to nonalcoholic steatohepatitis (NASH), characterized by liver necroinflammation and fibrosis and currently one of the top causes of end‐stage liver disease and hepatocellular carcinoma. At present, there is a lack of effective treatments, and a central barrier to the development of therapies is the requirement for an invasive liver biopsy for diagnosis of NASH. Discovery of reliable, noninvasive biomarkers are urgently needed. In this study, we tested whether circulating extracellular vesicles (EVs), cell‐derived small membrane‐surrounded structures with a rich cargo of bioactive molecules, may serve as reliable noninvasive “liquid biopsies” for NASH diagnosis and assessment of disease severity. Total circulating EVs and hepatocyte‐derived EVs were isolated by differential centrifugation and size‐exclusion chromatography from serum samples of healthy individuals, patients with precirrhotic NASH, and patients with cirrhotic NASH. EVs were further characterized by flow cytometry, electron microscopy, western blotting, and dynamic light scattering assays before performing a proteomics analysis. Our findings suggest that levels of total and hepatocyte‐derived EVs correlate with NASH clinical characteristics and disease severity. Additionally, using proteomics data, we developed understandable, powerful, and unique EV‐based proteomic signatures for potential diagnosis of advanced NASH. Conclusion: Our study shows that the quantity and protein constituents of circulating EVs provide strong evidence for EV protein–based liquid biopsies for NAFLD/NASH diagnosis.

Comprehensive characterization of hepatocyte-derived extracellular vesicles identifies direct miRNA-based regulation of hepatic stellate cells and DAMP-based hepatic macrophage IL-1β and IL-17 upregulation in alcoholic hepatitis mice

Extracellular vesicles (EVs) have been growingly recognized as biomarkers and mediators of alcoholic liver disease (ALD) in human and mice. Here we characterized hepatocyte-derived EVs (HC-EVs) and their cargo for their biological functions in a novel murine model that closely resembles liver pathology observed in patients with alcoholic hepatitis (AH), the most severe spectrum of ALD. The numbers of circulating EVs and HC-EVs were significantly increased by 10-fold in AH mice compared with control mice. The miRNA (miR)-seq analysis detected 20 upregulated and 4 downregulated miRNAs (P < 0.001-0.05) in AH-HC-EVs. Treatment of murine primary hepatic stellate cells (HSCs) with AH-HC-EVs induced α-SMA (P < 0.05) and Col1a1 (P < 0.001). Smad7 and Nr1d2 genes, which were downregulated in HSCs from the AH mice, were predicted targets of 20 miRs upregulated in AH-HC-EVs. Among them were miR-27a and miR-181 which upon transfection in HSCs, indeed repressed Nr1d2, the quiescent HSC marker. AH-HC-EVs were also enriched with organelle proteins and mitochondrial DNA (10-fold, P < 0.05) and upregulated IL-1β and IL-17 production by hepatic macrophages (HMs) from AH mice in a TLR9-dependent manner. These results demonstrate HC-EV release is intensified in AH and suggest that AH-HC-EVs orchestrate liver fibrogenesis by directly targeting the quiescent HSC transcripts via a unique set of miRNAs and by amplifying HSC activation via DAMP-based induction of profibrogenic IL-1β and IL-17 by HMs. KEY MESSAGES: • Circulating EVs and HC-EVs were increased in AH mice compared with control mice • AH-HC-EVs were enriched in miRNAs, organelle proteins, and mitochondrial DNA • AH-HC-EVs increased cytokine production by AH-HMs in a TLR9-dependent manner.

Identification of actin network proteins, talin-1 and filamin-A, in circulating extracellular vesicles as blood biomarkers for human myalgic encephalomyelitis/chronic fatigue syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a serious, debilitating disorder with a wide spectrum of symptoms, including pain, depression, and neurocognitive deterioration. Over 17 million people around the world have ME/CFS, predominantly women with peak onset at 30-50 years. Given the wide spectrum of symptoms and unclear etiology, specific biomarkers for diagnosis and stratification of ME/CFS are lacking. Here we show that actin network proteins in circulating extracellular vesicles (EVs) offer specific non-invasive biomarkers for ME/CFS. We found that circulating EVs were significantly increased in ME/CFS patients correlating to C-reactive protein, as well as biological antioxidant potential. Area under the receiver operating characteristic curve for circulating EVs was 0.80, allowing correct diagnosis in 90-94% of ME/CFS cases. From two independent proteomic analyses using circulating EVs from ME/CFS, healthy controls, idiopathic chronic fatigue, and depression, proteins identified from ME/CFS patients are involved in focal adhesion, actin skeletal regulation, PI3K-Akt signaling pathway, and Epstein-Barr virus infection. In particular, talin-1, filamin-A, and 14-3-3 family proteins were the most abundant proteins, representing highly specific ME/CFS biomarkers. Our results identified circulating EV number and EV-specific proteins as novel biomarkers for diagnosing ME/CFS, providing important information on the pathogenic mechanisms of ME/CFS.

Cholangiocyte-Derived Exosomal lncRNA H19 Promotes Macrophage Activation and Hepatic Inflammation under Cholestatic Conditions

Activation of hepatic macrophages represents the critical driving force to promote cholestatic liver injury. Exosomes, as important small extracellular vesicles released by almost all types of cells, contribute to intercellular communication. We previously reported that cholangiocyte-derived exosomal long noncoding RNA (lncRNA) H19 plays a vital role in disrupting bile acid homeostasis in hepatocytes and promoting the activation of hepatic stellate cells (HSCs). Exosomal H19 derived from cholangiocytes was rapidly taken up by Kupffer cells. However, the mechanistic links between exosomal lncRNA H19 and macrophage-driven inflammation in cholestasis remain unclear. Here, we reported that the hepatic H19 level was closely correlated with macrophage activation and hepatic fibrosis in both Mdr2^-/- and bile duct ligation (BDL) cholestatic mouse models, as well as in human primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) patients. Exosomal H19 significantly induced the expression and secretion of chemokine (C–C motif) ligand 2 (CCL-2) and interleukin 6 (IL-6) in Kupffer cells. H19-enriched exosomes enhanced the activation M1 polarization of Kupffer cells and promoted the recruitment and differentiation of bone marrow-derived macrophages, which were inhibited by a CCL-2 pharmacological inhibitor. In conclusion, Cholangiocyte-derived exosomal H19 played a critical role in macrophage activation, differentiation, and chemotaxis through CCL-2/CCR-2 signaling pathways, which represent a therapeutic target for cholestatic liver diseases.

Emerging role of extracellular vesicles in liver diseases

Extracellular vesicles (EVs) are membrane-defined nanoparticles released by most cell types. The EVs released by cells may differ quantitatively and qualitatively from physiological states to disease states. There are several unique properties of EVs, including their proteins, lipids and nucleic acid cargoes, stability in circulation, and presence in biofluids, which make them a critical vector for cell-to-cell communication and impart utility as a biomarker. EVs may also serve as a vehicle for selective cargo secretion. Similarly, EV cargo may be selectively manipulated for targeted therapeutic delivery. In this review an overview is provided on the EV classification, biogenesis, and secretion pathways, which are conserved across cell types. Next, cargo characterization and effector cell responses are discussed in the context of nonalcoholic steatohepatitis, alcoholic hepatitis, and acetaminophen-induced liver injury. The review also discusses the potential biomarker and therapeutic uses of circulating EVs.

3D cell culture stimulates the secretion of in vivo like extracellular vesicles

For studying cellular communications ex-vivo, a two-dimensional (2D) cell culture model is currently used as the “gold standard”. 2D culture models are also widely used in the study of RNA expression profiles from tumor cells secreted extracellular vesicles (EVs) for tumor biomarker discovery. Although the 2D culture system is simple and easily accessible, the culture environment is unable to represent in vivo extracellular matrix (ECM) microenvironment. Our study observed that 2D- culture derived EVs showed significantly different profiles in terms of secretion dynamics and essential signaling molecular contents (RNAs and DNAs), when compared to the three-dimensional (3D) culture derived EVs. By performing small RNA next-generation sequencing (NGS) analysis of cervical cancer cells and their EVs compared with cervical cancer patient plasma EV-derived small RNAs, we observed that 3D- culture derived EV small RNAs differ from their parent cell small RNA profile which may indicate a specific sorting process. Most importantly, the 3D- culture derived EV small RNA profile exhibited a much higher similarity (~96%) to in vivo circulating EVs derived from cervical cancer patient plasma. However, 2D- culture derived EV small RNA profile correlated better with only their parent cells cultured in 2D. On the other hand, DNA sequencing analysis suggests that culture and growth conditions do not affect the genomic information carried by EV secretion. This work also suggests that tackling EV molecular alterations secreted into interstitial fluids can provide an alternative, non-invasive approach for investigating 3D tissue behaviors at the molecular precision. This work could serve as a foundation for building precise models employed in mimicking in vivo tissue system with EVs as the molecular indicators or transporters. Such models could be used for investigating tumor biomarkers, drug screening, and understanding tumor progression and metastasis.

The cell biology of the hepatocyte: A membrane trafficking machine

The liver performs numerous vital functions, including the detoxification of blood before access to the brain while simultaneously secreting and internalizing scores of proteins and lipids to maintain appropriate blood chemistry. Furthermore, the liver also synthesizes and secretes bile to enable the digestion of food. These diverse attributes are all performed by hepatocytes, the parenchymal cells of the liver. As predicted, these cells possess a remarkably well-developed and complex membrane trafficking machinery that is dedicated to moving specific cargos to their correct cellular locations. Importantly, while most epithelial cells secrete nascent proteins directionally toward a single lumen, the hepatocyte secretes both proteins and bile concomitantly at its basolateral and apical domains, respectively. In this Beyond the Cell review, we will detail these central features of the hepatocyte and highlight how membrane transport processes play a key role in healthy liver function and how they are affected by disease.