Exosomal miRNAs in hepatitis B virus related liver disease: a new hope for biomarker

MicroRNAs and their vital role in apoptosis in hepatocellular carcinoma: miRNA-based diagnostic and treatment methods

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies with high invasive and metastatic capability. Although significant advances have been made in the treatment of HCC, the overall survival rate of patients is still low. It is essential to explore accurate biomarkers for early diagnosis and prognosis along with therapeutic procedures to increase the survival rate of these patients. Anticancer therapies can contribute to induce apoptosis for the elimination of cancerous cells. However, dysregulated apoptosis and proliferation signaling pathways lead to treatment resistance, a significant challenge in improving efficient therapies. MiRNAs, short non-coding RNAs, play crucial roles in the progression of HCC, which regulate gene expression through post-transcriptional inhibition and targeting mRNA degradation in cancers. Dysregulated expression of multiple miRNAs is associated with numerous biological processes, including cell proliferation, apoptosis, invasion and metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and drug resistance in HCC. This review summarizes the role and potential efficacy of miRNAs in promoting and inhibiting cell proliferation and apoptosis in HCC, as well as the role of miRNAs in therapy resistance in HCC.

Engineered small extracellular vesicles as a novel platform to suppress human oncovirus-associated cancers

BACKGROUND

Cancer, as a complex, heterogeneous disease, is currently affecting millions of people worldwide. Even if the most common traditional treatments, namely, chemotherapy (CTx) and radiotherapy (RTx), have been so far effective in some conditions, there is still a dire need for novel, innovative approaches to treat types of cancer. In this context, oncoviruses are responsible for 12% of all malignancies, such as human papillomavirus (HPV), Merkel cell polyomavirus (MCPyV), Epstein-Barr virus (EBV), human herpesvirus 8 (HHV-8), as well as hepatitis B virus (HBV) and hepatitis C virus (HCV), and the poorest in the world also account for 80% of all human cancer cases. Against this background, nanomedicine has developed nano-based drug delivery systems (DDS) to meet the demand for drug delivery vectors, e.g., extracellular vesicles (EVs). This review article aimed to explore the potential of engineered small EVs (sEVs) in suppressing human oncovirus-associated cancers.

METHODS

Our search was conducted for published research between 2000 and 2022 using several international databases, including Scopus, PubMed, Web of Science, and Google Scholar. We also reviewed additional evidence from relevant published articles.

RESULTS

In this line, the findings revealed that EV engineering as a new field is witnessing the development of novel sEV-based structures, and it is expected to be advanced in the future. EVs may be further exploited in specialized applications as therapeutic or diagnostic tools. The techniques of biotechnology have been additionally utilized to create synthetic bilayers based on the physical and chemical properties of parent molecules via a top-down strategy for downsizing complicated, big particles into nano-sized sEVs.

CONCLUSION

As the final point, EV-mediated treatments are less toxic to the body than the most conventional ones, making them a safer and even more effective option. Although many in vitro studies have so far tested the efficacy of sEVs, further research is still needed to develop their potential in animal and clinical trials to reap the therapeutic benefits of this promising platform.

The promise of small particles: extracellular vesicles as biomarkers in liver pathology

Extracellular vesicles (EVs) are nanoscopic packages that are heterogeneous and bona fide players in hepatic physiology and pathology as they are involved in intercellular communication. EVs carrying bioactive cargoes rich in lipids, proteins or nucleic acids are implicated in the onset and progression of liver diseases. Liver pathology using liver biopsy has been assessed for several intricate conditions such as viral hepatitis, alcoholic and non-alcoholic fatty liver disease, hepatic malignancies and drug-induced liver injury. The lacunae, however, lie in early diagnosis and timely treatment of the above conditions, underscoring the need for non-invasive, accurate diagnostic tools that could replace the gold standard method of tissue biopsy. In this regard, EVs have emerged as promising candidates that could serve as potential biomarkers. In the last two decades, EVs, owing to their multifaceted charm in bringing out cell-free therapeutic responses and the ability of their cargoes to be applied to novel biomarkers, have drawn the great attention of researchers with the advancement and clinical application of liquid biopsy. In this review, we recapitulate the role of EVs and provide insights into the promising role of these small packages as biomarkers in liver pathology.

Exosomal MicroRNA and Protein Profiles of Hepatitis B Virus-Related Hepatocellular Carcinoma Cells

Infection with hepatitis B virus (HBV) is a main risk factor for hepatocellular carcinoma (HCC). Extracellular vesicles, such as exosomes, play an important role in tumor development and metastasis, including regulation of HBV-related HCC. In this study, we have characterized exosome microRNA and proteins released in vitro from hepatitis B virus (HBV)-related HCC cell lines SNU-423 and SNU-182 and immortalized normal hepatocyte cell lines (THLE2 and THLE3) using microRNA sequencing and mass spectrometry. Bioinformatics, including functional enrichment and network analysis, combined with survival analysis using data related to HCC in The Cancer Genome Atlas (TCGA) database, were applied to examine the prognostic significance of the results. More than 40 microRNAs and 200 proteins were significantly dysregulated (p < 0.05) in the exosomes released from HCC cells in comparison with the normal liver cells. The functional analysis of the differentially expressed exosomal miRNAs (i.e., mir-483, mir-133a, mir-34a, mir-155, mir-183, mir-182), their predicted targets, and exosomal differentially expressed proteins (i.e., POSTN, STAM, EXOC8, SNX9, COL1A2, IDH1, FN1) showed correlation with pathways associated with HBV, virus activity and invasion, exosome formation and adhesion, and exogenous protein binding. The results from this study may help in our understanding of the role of HBV infection in the development of HCC and in the development of new targets for treatment or non-invasive predictive biomarkers of HCC.

Dysregulated microRNAs as a biomarker for diagnosis and prognosis of hepatitis B virus-associated hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignancy with a high incidence and fatality rate worldwide. Hepatitis B virus (HBV) infection is one of the most important risk factors for its occurrence and development. Early detection of HBV-associated HCC (HBV-HCC) can improve clinical decision-making and patient outcomes. Biomarkers are extremely helpful, not only for early diagnosis, but also for the development of therapeutics. MicroRNAs (miRNAs), a subset of non-coding RNAs approximately 22 nucleotides in length, have increasingly attracted scientists' attention due to their potential utility as biomarkers for cancer detection and therapy. HBV profoundly impacts the expression of miRNAs potentially involved in the development of hepatocarcinogenesis. In this review, we summarize the current progress on the role of miRNAs in the diagnosis and treatment of HBV-HCC. From a molecular standpoint, we discuss the mechanism by which HBV regulates miRNAs and investigate the exact effect of miRNAs on the promotion of HCC. In the near future, miRNA-based diagnostic, prognostic, and therapeutic applications will make their way into the clinical routine.

Emerging role of microRNAs and long non-coding RNAs in COVID-19 with implications to therapeutics

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection which is commonly known as COVID-19 (COronaVIrus Disease 2019) has creeped into the human population taking tolls of life and causing tremendous economic crisis. It is indeed crucial to gain knowledge about their characteristics and interactions with human host cells. It has been shown that the majority of our genome consists of non-coding RNAs. Non-coding RNAs including micro RNAs (miRNAs) and long non-coding RNAs (lncRNAs) display significant roles in regulating gene expression in almost all cancers and viral diseases. It is intriguing that miRNAs and lncRNAs remarkably regulate the function and expression of major immune components of SARS-CoV-2. MiRNAs act via RNA interference mechanism in which they bind to the complementary sequences of the viral RNA strand, inducing the formation of silencing complex that eventually degrades or inhibits the viral RNA and viral protein expression. LncRNAs have been extensively shown to regulate gene expression in cytokine storm and thus emerges as a critical target for COVID-19 treatment. These lncRNAs also act as competing endogenous RNAs (ceRNAs) by sponging miRNAs and thus affecting the expression of downstream targets during SARS-CoV-2 infection. In this review, we extensively discuss the role of miRNAs and lncRNAs, describe their mechanism of action and their different interacting human targets cells during SARS-CoV-2 infection. Finally, we discuss possible ways how an interference with their molecular function could be exploited for new therapies against SARS-CoV-2.

Peripheral Circulating Exosomal-miRNAs Potentially Mediate the Sensitivity to Interferon Treatment in Chronic Hepatitis B Virus Patients

Pegylated interferon alfa-2b (Peg-IFN α-2b), a first-line treatment for hepatitis B virus (HBV) infection, can significantly achieve HBsAg clearance in clinic. However, only 30-40% of patients had achieved HBsAg clearance after Peg-IFN α-2b administration. The biological targets and the underline mechanisms that distinguish sensitive and insensitive populations to interferon therapy are still unclear. In the present study, only 33.33% of patients achieved HBsAg loss after 48 weeks of Peg-IFN α-2b therapy. Thirty-six exosomal-microRNAs (miRNAs) in the sensitive group were identified that might induce sensitivity specifically, whereas 32 exosomal-miRNAs in the insensitive group were identified that might induce insensitive specifically. Among these miRNAs, five miRNAs (miR-425-5p, miR-8485, miR-619-5p, miR-181a-5p, and miR-484) might increase the sensitivity to Peg-IFN α-2b therapy by regulating key genes GSK3B, KRAS, FLT1, or GRB2, whereas, 13 miRNAs (miR-195-5p, miR-215-5p, miR-9-5p, miR-130a-3p, miR-214-3p, miR-149-5p, miR-429, miR-200b-3p, miR-200c-3p, miR-16-2-3p, miR-141-3p, miR-200a-3p, and miR-218-5p) might decrease the sensitivity to Peg-IFN α-2b therapy by regulating key genes, FGF2, GSK3B, PDGFRA, FGFR1, KRAS, FLT1, MYC, TGFB2, EFNA1, MAPK9, or GRB2. Furthermore, seven novel miRNAs, namely Novel_352, Novel_459, Novel_527, Novel_677, Novel_717, Novel_749, and Novel_801 were found to be downregulated specifically in the sensitive group, whereas, Novel_142 and Novel_664 were found to be downregulated specifically in the insensitive group. Our data indicate that the serum exosomal-miRNAs could be involved in regulating the sensitivity of chronic HBV (CHB) patients to Peg-IFN α-2b therapy, which might suggest potential novel therapeutic biomarkers and standard options for CHB patients. Clinical Trials.gov ID: NCT04035837.

Cell cycle kinases (AUKA, CDK1, PLK1) are prognostic biomarkers and correlated with tumor-infiltrating leukocytes in HBV related HCC

Hepatocellular carcinoma (HCC) is one of the high incidence cancers and third leading cause of cancer-related mortality. HBV is the top most risk factor accounting for 50-80% of the HCC cases. Kinases: Aurora kinase A (AURKA), cyclin-dependent kinase (CDK1) and Polo-like kinase 1 (PLK1), the key regulators of cell mitosis are overexpressed in varieties of cancers including HCC. However, the exact role of these genes in prognosis of HCC is not fully unveiled. In addition, there is no such an accurate prognostic biomarker for HBV-related HCC. To address this issue, we performed a multidimensional analysis of AURKA, CDK1 and PLK1 with a series of publicly available databases in multiple cancers and with experimental validation in HBV-related HCC tissues. Overexpression of AURKA, CDK1 and PLK1 was found in multiple cancers including HCC. Elevated expression of these genes could result from lowered DNA methylation and genomic alterations. Transcriptional overexpression was significantly correlated with poor prognosis of HCC patients. The expression levels were also significantly positively associated with tumor grades and stages. Furthermore, the expression levels of these genes had a strong correlation with infiltration of immune cells. Our analysis shows that AURKA, CDK1 and PLK1 are correlated with immune infiltration and are the prognostic biomarkers for HBV-induced HCC.Communicated by Ramaswamy H. Sarma.

Fc receptor-like 5 gene polymorphisms and mRNA expression are associated with liver fibrosis in chronic hepatitis B

Objective: To investigate the associations of Fc receptor-like 5 (FCRL5) gene polymorphisms and mRNA expression with liver fibrosis in chronic hepatitis B (CHB).

Methods: A total of 114 CHB patients with liver fibrosis and 120 CHB patients without liver fibrosis were selected for this study. The gender, age, body mass index (BMI), alanine transaminase (ALT) value, aspartate aminotransferase (AST) value, aspartate aminotransferase-to-platelet ratio index (APRI), and fibrosis index based on 4 factors (FIB-4) were recorded. Two polymorphisms of the FCRL5 gene (rs6427384 and rs6692977) were genotyped. The mRNA expression level of FCRL5 in peripheral blood monocytes was determined.

Results: ALT, AST, APRI, and FIB-4 in patients with fibrosis were significantly higher than those in non-fibrosis patients. There was statistically significant difference between fibrosis and non-fibrosis groups in the genotype distribution (χ2 = 7.805, p = 0.020) and allele frequencies (χ2 = 13.252, p &lt; 0.001) at FCRL5 rs6692977. When compared with CC genotype, the genotype CT or TT at rs6692977 was significantly associated with a increased risk of liver fibrosis in CHB patients (CT vs. CC: OR = 1.921, 95% CI = 1.093–3.375, p = 0.023; TT vs. CC: OR = 2.598, 95% CI = 1.067–6.324, p = 0.031). The mRNA relative expression levels of FCRL5 in patients with liver fibrosis were significantly higher than those in the non-fibrosis group (t = 13.456, p &lt; 0.001). The fibrosis patients carried TT or CT genotype of rs6692977 had significantly higher FCRL5 mRNA expression levels than those carried CC genotype (t = 2.859, p = 0.005). The mRNA expression levels of FCRL5, APRI, and FIB-4 index showed predictive efficacy in liver fibrosis with cut-off values of 0.75 (AUC = 0.896, 95% CI = 0.856–0.935), 0.45 (AUC = 0.852, 95% CI = 0.802–0.902) and 1.84 (AUC = 0.765, 95% CI = 0.703–0.826), respectively.

Conclusion: FCRL5 gene rs6692977 polymorphisms and mRNA expression levels are associated with liver fibrosis in CHB patients.

Exosomal miR-142-3p secreted by hepatitis B virus (HBV)-hepatocellular carcinoma (HCC) cells promotes ferroptosis of M1-type macrophages through SLC3A2 and the mechanism of HCC progression

BACKGROUND

Most patients with hepatitis B virus (HBV) infection will develop hepatocellular carcinoma (HCC). This study aimed to explore the potential mechanism of miR-142-3p in HCC caused by HBV infection.

METHODS

HepG2 cells and M1 macrophages were cocultured and then infected with HBV to establish an in vitro model. MicroRNA (miRNA) and messenger RNA (mRNA) expression was analyzed by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot. The protein expressions of COX2, ACSL4, PTGS2, GPX4, and NOX1 were analyzed by Western blot. Flow cytometry and TUNEL assays were used to assess cell reactive oxygen species (ROS) and ferroptosis, respectively. Cell invasion and migration were measured by Transwell assay. To evaluate the ferroptosis of M1-type macrophages, glutathione (GSH), malondialdehyde (MDA), and Fe2+ content was detected by corresponding kits. Dual luciferase reporter gene detection verified the targeting relationship between miR-142-3p and SLC3A2.

RESULTS

MiR-142-3p was highly expressed in HBV-infected HCC patients and HBV-infected M1-type macrophages. Inhibition of miR-142-3p or overexpression of SLC3A2 reversed ferroptosis and inhibited the proliferation, migration, and invasion of HCC cells.

CONCLUSIONS

Our findings indicated that miR-142-3p promoted HBV-infected M1-type macrophage ferroptosis through SLC3A2, affecting the production of GSH, MDA, and Fe2+ and accelerating the development of HCC. The regulation of miR-142-3p and its target genes will help to clarify the pathogenesis of HCC induced by HBV infection and provide new theoretical foundations and therapeutic targets.

Hepatitis B core antigen modulates exosomal miR-135a to target vesicle-associated membrane protein 2 promoting chemoresistance in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. The association of hepatitis B virus (HBV) infection with HCC is hitherto documented. Exosomal miRNAs contribute to cancer progression and chemoresistance. HBV X protein has been known to modulate miRNAs that facilitate cell proliferation and the process of hepatocarcinogenesis. However, there has been no report on hepatitis B core antigen (HBc) regulating exosomal miRNAs to induce drug resistance of HCC cells.

AIM

To elucidate the mechanism by which HBc promotes Doxorubicin hydrochloride (Dox) resistance in HCC.

METHODS

Exosomes were isolated by ultracentrifugation. The morphology and size of exosomes were evaluated by Dynamic Light Scattering (DLS) and transmission electron microscopy (TEM). The miRNAs differentially expressed in HCC were identified using The Cancer Genome Atlas (TCGA) database. The level of miR-135a-5p in patient tissue samples was detected by quantitative polymerase chain reaction. TargetScan and luciferase assay were used to predict and prove the target gene of miR-135a-5p. Finally, we identified the effects of miR-135a-5p on anti-apoptosis and the proliferation of HCC in the presence or absence of Dox using flow cytometry, Cell counting kit 8 (CCK-8) assay and western blot.

RESULTS

We found that HBc increased the expression of exosomal miR-135a-5p. Integrated analysis of bioinformatics and patient samples found that miR-135a-5p was increased in HCC tissues in comparison with paracancerous tissues. Bioinformatic analysis and in vitro validation identified vesicle-associated membrane protein 2 (VAMP2) as a novel target gene of miR-135a-5p. Functional assays showed that exosomal miR-135a-5p induced apoptosis protection, cell proliferation, and chemotherapy resistance in HCC. In addition, the rescue experiment demonstrated that VAMP2 reversed apoptosis protection, cell growth, and drug resistance by miR-135a-5p. Finally, HBc promoted HCC anti-apoptosis, proliferation, and drug resistance and prevented Dox-induced apoptosis via the miR-135a-5p/VAMP2 axis.

CONCLUSION

These data suggested that HBc upregulated the expression of exosomal miR-135a-5p and promoted anti-apoptosis, cell proliferation, and chemical resistance through miR-135a-5p/VAMP2. Thus, our work indicated an essential role of the miR-135a-5p/VAMP2 regulatory axis in chemotherapy resistance of HCC and a potential molecular therapeutic target for HCC.

Roles and mechanisms of exosomal non-coding RNAs in human health and diseases

Exosomes play a role as mediators of cell-to-cell communication, thus exhibiting pleiotropic activities to homeostasis regulation. Exosomal non-coding RNAs (ncRNAs), mainly microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are closely related to a variety of biological and functional aspects of human health. When the exosomal ncRNAs undergo tissue-specific changes due to diverse internal or external disorders, they can cause tissue dysfunction, aging, and diseases. In this review, we comprehensively discuss the underlying regulatory mechanisms of exosomes in human diseases. In addition, we explore the current knowledge on the roles of exosomal miRNAs, lncRNAs, and circRNAs in human health and diseases, including cancers, metabolic diseases, neurodegenerative diseases, cardiovascular diseases, autoimmune diseases, and infectious diseases, to determine their potential implication in biomarker identification and therapeutic exploration.

Genetic polymorphisms in the miR-372 (rs12983273) and LncRNA HULC (rs7763881) genes and susceptibility to Hepatitis B virus (HBV) infection

BACKGROUND

MicroRNAs (miRNAs) and Long non-coding RNAs (lncRNAs) are two major types of non-coding RNAs (ncRNAs) with regulatory roles. The initiation and progression of numerous diseases have been linked to genetic variation in miRNAs and lncRNAs. Many diseases, including hepatitis infection, are thought to be regulated by miRNA-LncRNA interactions. In this study, Single nucleotide polymorphisms (SNPs) in miR-372 (rs28461391 C/T) and HULC (rs7763881 A/C) were believed to play a role in HBV infection risk.

METHODS AND RESULTS

Using the Polymerase chain reaction sequence-specific primer technique (PCR-SSP), 100 HBV patients and 100 healthy controls were genotyped for SNPs rs28461391 in miR-372 and rs7763881 in HULC. There was no significant difference in miR-372 rs12983273 genotype distribution between controls and HBV patients, according to our findings. On the other hand, there was a significant increase in HULC rs7763881 CC genotype (P < 0.05) coincides with a significant decrease in AC genotype distribution (P < 0.05) in HBV patients as compared to controls. Our results showed that the AA genotype is protective for HBV infection (OR 0.3; CI 0.13-9.07) while the CC genotype is associated with an increased risk of HBV infection (OR 3.43; CI 1.3-9.07).

CONCLUSIONS

Our results suggest that HULC rs7763881 A/C might be a biomarker for HBV susceptibility. Larger sample studies are needed to confirm our preliminary data. To the best of our knowledge, the present study was the first to investigate the relevance of miR-372 (rs28461391 C/T) and HULC (rs7763881 A/C) gene polymorphisms to the risk of HBV infection in the Egyptian population.

[CDK1, CCNB1 and NDC80 are associated with prognosis and progression of hepatitis B virus-associated hepatocellular carcinoma: a bioinformatic analysis]

OBJECTIVE

To identify the key genes involved in the transformation of hepatitis B virus (HBV) into hepatocellular carcinoma (HCC) and explore the underlying molecular mechanisms.

METHODS

We analyzed the mRNA microarray data of 119 HBV-related HCC tissues and 252 HBV-related non-tumor tissues in GSE55092, GSE84044 and GSE121248 from the GEO database, and the "sva" R package was used to remove the batch effects. Integration analysis was performed to identify the differentially expressed genes (DEGs) in HBV-related liver cancer and liver tissues with HBV infection. The significant DEGs were functionally annotated using GO and KEGG analyses, and the most important modules and hub genes were explored with STRING analysis. Kaplan-Meier and Oncomine databases were used to verify the HCC gene expression data in the TCGA database to explore the correlations of the hub genes with the occurrence, progression and prognosis of HCC. We also examined the expressions of the hub genes in 17 pairs of surgical specimens of HCC and adjacent tissues using RT-qPCR.

RESULTS

We identified a total of 121 DEGs and 3 genetic markers in HCC (P < 0.01). These DEGs included cyclin1 (CDK1), cyclin B1 (CCNB1), and nuclear division cycle 80 (NDC80), which participated in cell cycle, pyrimidine metabolism and DNA replication and were highly correlated (P < 0.05). Analysis of the UALCAN database confirmed high expressions of these 3 genes in HCC tissues, which were correlated with a low survival rate of the patients, as shown by Kaplan-Meier analysis of the prognostic data from the UALCAN database. CDK1, CCNB1 and NDC80 were all correlated with the clinical grading of HCC (P < 0.05). The results of RT-qPCR on the surgical specimens verified significantly higher expressions of CDK1, CCNB1 and NDC80 mRNA in HCC tissues than in the adjacent tissues.

CONCLUSION

CDK1, CCNB1 and NDC80 genes can be used as prognostic markers of HBV-related HCC and may serve as potential targets in preclinical studies and clinical treatment of HCC.

Mesenchymal Stem Cell-Derived Exosomes: Applications in Regenerative Medicine

Exosomes are a type of extracellular vesicles, produced within multivesicular bodies, that are then released into the extracellular space through a merging of the multivesicular body with the plasma membrane. These vesicles are secreted by almost all cell types to aid in a vast array of cellular functions, including intercellular communication, cell differentiation and proliferation, angiogenesis, stress response, and immune signaling. This ability to contribute to several distinct processes is due to the complexity of exosomes, as they carry a multitude of signaling moieties, including proteins, lipids, cell surface receptors, enzymes, cytokines, transcription factors, and nucleic acids. The favorable biological properties of exosomes including biocompatibility, stability, low toxicity, and proficient exchange of molecular cargos make exosomes prime candidates for tissue engineering and regenerative medicine. Exploring the functions and molecular payloads of exosomes can facilitate tissue regeneration therapies and provide mechanistic insight into paracrine modulation of cellular activities. In this review, we summarize the current knowledge of exosome biogenesis, composition, and isolation methods. We also discuss emerging healing properties of exosomes and exosomal cargos, such as microRNAs, in brain injuries, cardiovascular disease, and COVID-19 amongst others. Overall, this review highlights the burgeoning roles and potential applications of exosomes in regenerative medicine.

Exosome-Based Vaccines: History, Current State, and Clinical Trials

Extracellular vesicles (EVs) are released by most cell types as part of an intracellular communication system in crucial processes such as inflammation, cell proliferation, and immune response. However, EVs have also been implicated in the pathogenesis of several diseases, such as cancer and numerous infectious diseases. An important feature of EVs is their ability to deliver a wide range of molecules to nearby targets or over long distances, which allows the mediation of different biological functions. This delivery mechanism can be utilized for the development of therapeutic strategies, such as vaccination. Here, we have highlighted several studies from a historical perspective, with respect to current investigations on EV-based vaccines. For example, vaccines based on exosomes derived from dendritic cells proved to be simpler in terms of management and cost-effectiveness than dendritic cell vaccines. Recent evidence suggests that EVs derived from cancer cells can be leveraged for therapeutics to induce strong anti-tumor immune responses. Moreover, EV-based vaccines have shown exciting and promising results against different types of infectious diseases. We have also summarized the results obtained from completed clinical trials conducted on the usage of exosome-based vaccines in the treatment of cancer, and more recently, coronavirus disease.

Silencing hepatitis B virus covalently closed circular DNA: The potential of an epigenetic therapy approach

Global prophylactic vaccination programmes have helped to curb new hepatitis B virus (HBV) infections. However, it is estimated that nearly 300 million people are chronically infected and have a high risk of developing hepatocellular carcinoma. As such, HBV remains a serious health priority and the development of novel curative therapeutics is urgently needed. Chronic HBV infection has been attributed to the persistence of the covalently closed circular DNA (cccDNA) which establishes itself as a minichromosome in the nucleus of hepatocytes. As the viral transcription intermediate, the cccDNA is responsible for producing new virions and perpetuating infection. HBV is dependent on various host factors for cccDNA formation and the minichromosome is amenable to epigenetic modifications. Two HBV proteins, X (HBx) and core (HBc) promote viral replication by modulating the cccDNA epigenome and regulating host cell responses. This includes viral and host gene expression, chromatin remodeling, DNA methylation, the antiviral immune response, apoptosis, and ubiquitination. Elimination of the cccDNA minichromosome would result in a sterilizing cure; however, this may be difficult to achieve. Epigenetic therapies could permanently silence the cccDNA minichromosome and promote a functional cure. This review explores the cccDNA epigenome, how host and viral factors influence transcription, and the recent epigenetic therapies and epigenome engineering approaches that have been described.

Extracellular vesicles in embryo implantation and disorders of the endometrium

Implantation of the embryo is a rate-limiting step for a successful pregnancy, and it requires an intricate crosstalk between the embryo and the endometrium. Extracellular vesicles (EVs) are membrane-enclosed, nano-sized structures produced by cells to mediate cell to cell communication and modulate a diverse set of biological processes. Herein, we review the involvement of EVs in the process of embryo implantation and endometrial diseases. EVs have been isolated from uterine fluid, cultured endometrial epithelial/stromal cells and trophectodermal cells. The endometrial epithelial and stromal/decidual cell-derived EVs and its cargo are internalized bythe trophoblast cells, and they regulate a diverse set of genes involved in adhesion, invasion and migration. Conversely, the embryo-derived EVs and its cargo are internalized by epithelial and immune cells of the endometrium for biosensing and immunomodulation required for successful implantation. EVs have also been shown to play a role in infertility, recurrent implantation failure, endometriosis, endometritis and endometrial cancer. Further research should set a stage for EVs as non-invasive "liquid biopsy" tools for assessment of endometrial health.

The expression and clinical significance of TPM4 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is known as the fifth most common cancer in the world for its poor prognosis. New diagnostic markers and treatments are urgent to discover. To evaluate the protein expression of Tropomyosin4 (TPM4) and investigate its prognostic value in HCC, we collected 110 patients with different degrees of HCC and 10 patients with normal hepatic tissues and performed immunohistochemistry. Western bot was used to evaluate the expression of TPM4 in three HCC cell lines (HepG2, Huh7, SMMC-7721) and normal liver cell line LO2, as well as 7 HCC tissues and 7 normal hepatic tissues. The results of TPM4 staining revealed that TPM4 expression in HCC was higher than that in normal hepatic tissues, which was positive in 51.8% (n=57) and negative in 48.2% (n=53) while in normal hepatic tissues positive staining was in 10% (n=1) and negative staining was in 90% (n=9) (P=0.011). And the expression of TPM4 was related to pT status, grade and stage (P<0.001, P=0.015 and P<0.001, respectively). Western blot results indicated that TPM4 was high expressed in HCC cell line and HCC tissues. In conclusion, we believe that TPM4 can be applied as a diagnostic and prognostic marker to assist the management of HCC.

Evaluation of miR-222 Expression in HBV Infected Patients in Comparison with HDV and HBV Co-infected Patients

BACKGROUND

Liver disease is more severe in HDV+HBV co-infected patients than HBV infected patients which seems to be related to differences in the expression of genes and other factors such as MicroRNAs (miRNAs). The aim of this study was to investigate miR-222 expression in HBV infected patients in comparison with HDV+HBV co-infected patients.

METHODS

First, total RNA was extracted from the serum samples and then, complementary DNA (cDNA) was produced using cDNA synthesis kit. Finally, miR-222 gene expression was measured using U6 as the internal control by quantitative PCR (qPCR).

RESULTS

The level of miR-222 expression in HDV+HBV co-infected samples was significantly up regulated. The fold change of the miR-222 expression between two groups was 3.3 (95% CI; 0.011-17.63) with p<0.001.

CONCLUSION

The expression of miR-222 was higher in HBV+HDV co-infected patients than HBV infected patients. Further studies should be conducted to confirm whether miR-222 can be a biomarker for prognosis of severe liver diseases.

Emerging role and therapeutic application of exosome in hepatitis virus infection and associated diseases

Hepatitis viruses are chief pathogens of hepatitis and end-stage liver diseases. Their replication and related pathogenic process highly rely on the host micro-environment and multiple cellular elements, including exosomes. Representing with a sort of cell-derived vesicle structure, exosomes were considered to be dispensable cellular components, even wastes. Along with advancing investigation, a specific profile of exosome in driving hepatitis viruses' infection and hepatic disease progression is revealed. Exosomes greatly affect the pathogenesis of hepatitis viruses by mediating their replication and modulating the host immune responses. The characteristics of host exosomes are markedly changed after infection with hepatitis viruses. Exosomes released from hepatitis virus-infected cells can carry viral nucleic or protein components, thereby acting as an effective subterfuge for hepatitis viruses by participating in viral transportation and immune escape. On the contrary, immune cell-derived exosomes contribute toward the innate antiviral immune defense and virus eradication. There is growing evidence supporting the application of exosomal biomarkers for predicting disease progress or therapeutic outcome, while exosomal nanoshuttles are regarded as promising therapeutic options based on their delivery properties and immune compatibility. In this review, we summarize the biogenesis and secretion mechanism of exosomes, review the recent findings pertaining to the role of exosomes in the interplay between hepatitis viruses and innate immune responses, and conclude their potential in further therapeutic application.

hUCB-MSC derived exosomal miR-124 promotes rat liver regeneration after partial hepatectomy via downregulating Foxg1

Liver regeneration after partial hepatectomy (PH) is a complex and well-orchestrated process involving multiple factors such as cytokines, growth factors, and signaling pathways. MicroRNAs (miRNAs) participate in various biological processes including liver regeneration after PH. In the current study, we investigated the expression and function of human umbilical cord blood mesenchymal stem cell (hUCB-MSC) derived exosomal miRNAs on liver regeneration using a rat PH model. We found that hUCB-MSC derived exosomes promoted rat liver regeneration and ameliorated liver injury after PH. MicroRNA microarray was performed to identify the differentially expressed miRNAs in hUCB-MSC derived exosomes involving in liver regeneration after PH. We demonstrated that hUCB-MSC derived exosomal miR-124 could promote liver regeneration and prevent against liver injury after PH in rats. Inhibition of miR-124 abrogated the protective role of hUCB-MSC derived exosome in rat liver regeneration after PH. In addition, we identified that transcription factor Foxg1 was a direct target of miR-124 and miR-124 promoted rat liver cell proliferation via suppressing Foxg1 expression. Furthermore, we demonstrated that hUCB-MSC derived exosomal miR-124 enhanced liver regeneration via inhibiting Foxg1 in rats after PH. In summary, our findings suggest that hUCB-MSC-derived exosomal miR-124 could promote rat liver regeneration after PH via downregulating Foxg1.

Functional mechanism and clinical implications of MicroRNA-423 in human cancers

MicroRNAs play a vital role in the regulatory mechanisms of tumorigenesis. Current research indicates that microRNA-423 (miR-423) is abnormally expressed in various human tumors and participates in multiple signaling pathways of cancer progression. In most studies, miR-423 was confirmed as oncomiR, while a few contradictory reports considered miR-423 as an anticancer miRNA. The paradoxical role in cancer may hinder the application of miR-423 as a diagnostic and therapeutic target. Simultaneously, the interaction mechanism between miR-423 and lncRNA also needs attention. In this review, we have summarized the dual role of aberrant miR-423 expression and its mechanisms in tumorigenesis, and the therapeutic potential of miR-423 in human tumors.

Differential microRNA expression in the peripheral blood from human patients with COVID-19

INTRODUCTION

The coronavirus disease (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which play important roles in regulating gene expression and are also considered as essential modulators during viral infection. The aim of this study was to elucidate the differential expression of miRNAs in COVID-19.

METHODS

The total RNA was extracted and purified from the peripheral blood of ten patients with COVID-19 and four healthy donors. The expression levels of various miRNAs were detected by high-throughput sequencing, and correlation analysis was performed on the target genes that are primed by miRNAs.

KEY FINDINGS

Compared with the healthy controls, 35 miRNAs were upregulated and 38 miRNAs were downregulated in the human patients with COVID-19. The top 10 genes were listed below: hsa-miR-16-2-3P,hsa-miR-5695,hsa-miR-10399-3P,hsa-miR-6501-5P,hsa-miR-361-3P,hsa-miR-361-3p, hsa-miR-4659a-3p, hsa-miR-142-5p, hsa-miR-4685-3p, hsa-miR-454-5p, and hsa-miR-30c-5p. The 10 genes with the greatest reduction were listed below: hsa-miR-183-5p, hsa-miR-627-5p, hsa-miR-941, hsa-miR-21-5p, hsa-miR-20a-5p, hsa-miR-146b-5p, hsa-miR-454-3p, hsa-miR-18a-5p, hsa-miR-340-5p, and hsa-miR-17-5p. Remarkably, miR-16-2-3p was the most upregulated miRNA, with a 1.6-fold change compared to that of the controls. Moreover, the expression of miR-6501-5p and miR-618 was 1.5-fold higher in the COVID-19 patients than in the healthy donors. Meanwhile, miR-627-5p was the most downregulated miRNA, with a 2.3-fold change compared to that of the controls. The expression of other miRNAs (miR-183-5p, miR-627-5p, and miR-144-3p) was reduced by more than 1.3-fold compared to that of the healthy donors. Cluster analysis revealed that all of the differentially expressed miRNA target genes were clustered by their regulation of cellular components, molecular functions, and biological processes. Importantly, peptidases, protein kinases, and the ubiquitin system were shown to be the highest enrichment categories by enrichment analysis.

CONCLUSIONS

The differential miRNA expression found in COVID-19 patients may regulate the immune responses and viral replication during viral infection.

miR-874 inhibits gastric cancer cell proliferation by targeting SPAG9

Background

microRNAs (miRNAs) play essential roles in the development and progression of gastric cancer (GC). Although aberrant miR-874 expression has been reported in various human cancers, its role in GC remains obscure.

Methods

miR-874 expression was assessed by real-time quantitative polymerase chain reaction (RT-qPCR) in 62 matched GC and adjacent normal tissues, as well as in GC cell lines and immortalized human gastric epithelial cells. CCK8 assay, colony formation assay, and flow cytometry were used to assess the role of miR-874 in GC cell proliferation and apoptosis in vitro. Additionally, to determine the effects of miR-874 on GC cell proliferation and apoptosis in vivo, BALB/c nude mice were injected with GC cells transfected with a miR-874 mimic. The role of miR-874 in SPAG9 expression was assessed by luciferase assay, Western blotting, and RT-qPCR.

Results

miR-874 was downregulated in GC cell lines and tissues. miR-874 overexpression in GC cells led to inhibition of cell proliferation and induction of apoptosis. Moreover, SPAG9 was identified as a direct miR-874 target, the expression of which was suppressed by miR-874. SPAG9 overexpression markedly promoted GC cell proliferation.

Conclusions

miR-874 inhibited cell proliferation and induced apoptosis in GC cells. SPAG9 downregulation was crucial for the tumor-suppressive effects of miR-874. Hence, the miR-874/SPAG9 axis could serve as a novel therapeutic target in GC.