miR-21 is a negative modulator of T-cell activation

Integrative analysis of single-cell and transcriptome sequencing with experimental validation reveals PKHD1L1 as a novel biomarker in lung adenocarcinoma

Polycystic kidney and hepatic disease 1-like protein 1 (PKHD1L1) is predicted to encode a large type I transmembrane protein involved in hearing transmission and mediating cellular immunity under physiological conditions. However, its role in cancer progression, especially in lung adenocarcinoma (LUAD), has not been fully elucidated. In this study, we observed significantly lower expression of PKHD1L1 in LUAD tissues than in normal lung tissues on the basis of the integration of public datasets from the TCGA and GEO cohorts. Furthermore, we found that low PKHD1L1 expression was a strong predictor of poor prognosis in patients with LUAD. Pathway enrichment analyses revealed that PKHD1L1 is associated primarily with asthma and multiple immune processes. Through meticulous analysis of immune cell infiltrates and single-cell datasets, we discerned a notable correlation between the expression of PKHD1L1 and the presence of B cells, with a particularly strong association observed in plasma cells. This finding led us to believe that the role of PKHD1L1 may extend beyond its previously reported involvement in cellular immunity, potentially impacting humoral immunity as well. In vitro experiments revealed that the over-expression of PKHD1L1 significantly inhibited the proliferation and migration ability of LUAD cell lines. These findings suggest that PKHD1L1 is an important prognostic indicator and a potential therapeutic target for LUAD.

Expression Levels of lncRNA NEAT1, miRNA-21, and IL-17 in a Group of Egyptian Patients with Behçet's Disease: Relation to Disease Manifestations and Activity

Background

Long noncoding ribonucleic acids (lncRNAs), small noncoding RNAs known as microRNAs (miRNAs) as well as some cytokines are recently thought to have a role in many inflammatory and autoimmune disorders including Behçet's disease (BD). This chronic multisystem disease lacks the particular histological or laboratory findings that might aid in its diagnosis. Therefore, any association with such molecules may have an impact on understanding the disease pathogenesis and/or management. The current study compared the levels of NEAT1, miR-21 and IL17 levels in sera of Egyptian BD patients and healthy individuals. The expression levels of these molecules were further investigated for their association with BD manifestations and activity aiming to explore their potential application in disease management.

Results

NEAT1 & miR-21 showed down-regulation while IL-17 showed up-regulation among BD patients as compared to controls. IL-17 had significant correlation with major vessels involvement and cyclophosphamide intake. NEAT1 showed a significant negative correlation with colchicine intake. Disease activity did not correlate significantly with any of NEAT1, miR-21 or IL-17.

Conclusion

NEAT1, miR-21 and IL17 might have a role in Behçet's disease pathogenesis, so more research is needed to unveil that role and their potential usage as biomarkers for the diagnosis or therapeutic targets.

Targeted Microglial Membrane-Coated MicroRNA Nanosponge Mediates Inhibition of Glioblastoma

Glioblastoma (GBM) is the most prevalent primary brain tumor. Recent research emphasizes the crucial role of microRNAs (miRs) in GBM pathogenesis, and targeting miRs offers an effective approach for precise GBM therapy. However, inhibiting a single miR may not be sufficient due to the compensatory mechanisms of GBM. Herein, we developed a miR-nanosponge capable of specifically capturing multiple miRs involved in tumor growth, migration, invasion, angiogenesis, and the creation of an immunosuppressive microenvironment, thereby offering a comprehensive treatment for GBM. Coated with BV2 cell membrane (BM) for enhanced blood-brain barrier (BBB) crossing and GBM targeting, the BM@miR-nanosponge targets miR-9, miR-21, miR-215, and miR-221, significantly inhibiting GBM progression and modulating the immune system for a thorough GBM eradication. The BM@miR-nanosponge notably extended the median survival time of GBM-bearing mice and outperformed the standard treatment drug temozolomide (TMZ). This study introduces a comprehensive miR-based strategy for GBM treatment and highlights the importance of targeting multiple miRs associated with tumor survival for effective therapy.

Donor Sites and Harvesting Techniques Affect miRNA Cargos of Extracellular Vesicles Released by Human Adipose-Derived Mesenchymal Stromal Cells

Osteoarthritis (OA) is a degenerative joint disorder characterized by the progressive deterioration of articular cartilage driven and sustained by catabolic and inflammatory processes that lead to pain and functional impairment. Adipose-derived stem cells (ASCs) have emerged as a promising therapeutic strategy for OA due to their regenerative potential, which mainly relies on the adaptive release of paracrine molecules that are soluble or encapsulated in extracellular vesicles (EVs). The biological effects of EVs specifically depend on their cargo; in particular, microRNAs (miRNAs) can specifically modulate target cell function through gene expression regulation. This study aimed to investigate the impact of collection site (abdominal vs. peri-trochanteric adipose tissue) and collection method (surgical excision vs. lipoaspiration) on the miRNAs profile in ASC-derived EVs and their potential implications for OA therapy. EV-miRNA cargo profiles from ASCs of different origins were compared. An extensive bioinformatics search through experimentally validated and OA-related targets, pathways, and tissues was conducted. Several miRNAs involved in the restoration of cartilage homeostasis and in immunomodulation were identified in all ASC types. However, EV-miRNA expression profiles were affected by both the tissue-harvesting site and procedure, leading to peculiar characteristics for each type. Our results suggest that adipose-tissue-harvesting techniques and the anatomical site of origin influence the therapeutic efficacy of ASC-EVs for tissue-specific regenerative therapies in OA, which warrants further investigation.

Non-Coding RNAs as Potential Targets for Diagnosis and Treatment of Oral Lichen Planus: A Narrative Review

Oral lichen planus (OLP) is a chronic inflammatory disease that is characterized by the infiltration of T cells into the oral mucosa, causing the apoptosis of basal keratinocytes. OLP is a multifactorial disease of unknown etiology and is not solely caused by the malfunction of a single key gene but rather by various intracellular and extracellular factors. Non-coding RNAs play a critical role in immunological homeostasis and inflammatory response and are found in all cell types and bodily fluids, and their expression is closely regulated to preserve normal physiologies. The dysregulation of non-coding RNAs may be highly implicated in the onset and progression of diverse inflammatory disorders, including OLP. This narrative review summarizes the role of non-coding RNAs in molecular and cellular changes in the oral epithelium during OLP pathogenesis.

Identification and validation of a T-cell-related MIR600HG/hsa-mir-21-5p competing endogenous RNA network in tuberculosis activation based on integrated bioinformatics approaches

Background: T cells play critical roles in the progression of tuberculosis (TB); however, knowledge regarding these molecular mechanisms remains inadequate. This study constructed a critical ceRNA network was constructed to identify the potentially important role of TB activation via T-cell regulation.

Methods: We performed integrated bioinformatics analysis in a randomly selected training set from the GSE37250 dataset. After estimating the abundance of 18 types of T cells using ImmuCellAI, critical T-cell subsets were determined by their diagnostic accuracy in distinguishing active from latent TB. We then identified the critical genes associated with T-cell subsets in TB activation through co-expression analysis and PPI network prediction. Then, the ceRNA network was constructed based on RNA complementarity detection on the DIANA-LncBase and mirDIP platform. The gene biomarkers included in the ceRNA network were lncRNA, miRNA, and targeting mRNA. We then applied an elastic net regression model to develop a diagnostic classifier to assess the significance of the gene biomarkers in clinical applications. Internal and external validations were performed to assess the repeatability and generalizability.

Results: We identified CD4⁺ T, Tr1, nTreg, iTreg, and Tfh as T cells critical for TB activation. A ceRNA network mediated by the MIR600HG/hsa-mir-21-5p axis was constructed, in which the significant gene cluster regulated the critical T subsets in TB activation. MIR600HG, hsa-mir-21-5p, and five targeting mRNAs (BCL11B, ETS1, EPHA4, KLF12, and KMT2A) were identified as gene biomarkers. The elastic net diagnostic classifier accurately distinguished active TB from latent. The validation analysis confirmed that our findings had high generalizability in different host background cases.

Conclusion: The findings of this study provided novel insight into the underlying mechanisms of TB activation and identifying prospective biomarkers for clinical applications.

MicroRNA-21 induces cisplatin resistance in head and neck squamous cell carcinoma

Drug resistance, either intrinsic or acquired, can impair treatment effects and result in increased cell motility and death. MicroRNA-21 (miR-21), a proto-oncogene, may facilitate the development or maintenance of drug resistance in cancer cells. Restoring drug sensitivity can improve therapeutic strategies, a possibility that requires functional evaluation and mechanistic exploration. For miR-21 detection, matched tissue samples from 30 head and neck squamous cell carcinoma (HNSCC) patients and 8 head and neck cancer (HNC) cell lines were obtained. Reverse transcription-PCR to detect expression, MTT and clonogenic assays to evaluate cell proliferation, apoptosis assays, resazurin cell viability assays, western blot and luciferase reporter assays to detect protein expression, and flow cytometry to analyse the cell cycle were adopted. Compared to the corresponding normal control (NC) tissues, 25 cancer tissues had miR-21 upregulation among the 30 matched pair tissues (25/30, 83.8%); furthermore, among the 8 HNC cell lines, miR-21 expression that was notably upregulated in three: UPCI-4B, UMSCC-1, and UPCI-15B. In both the UMSCC-1 and UPCI-4B cell lines, the miR-21 mimic enhanced cell proliferation with reduced apoptosis and increased viability, whereas the miR-21 inhibitor resulted in the opposite effects (all P<0.001); additionally, miR-21 directly targeted the tumour suppressor phosphatase and tensin homologue (PTEN) and inhibited PTEN expression. Furthermore, the miR-21 mimic induced cisplatin resistance, while the miR-21 inhibitor restored cisplatin sensitivity. Overexpression of miR-21 can enhance cell proliferation, reduce apoptosis, and induce drug resistance by inhibiting PTEN expression. Targeting miR-21 may facilitate cancer diagnosis, restore drug sensitivity, and improve therapeutic effects.

Differential Expression of miRNAs in Trichloroethene-Mediated Inflammatory/Autoimmune Response and Its Modulation by Sulforaphane: Delineating the Role of miRNA-21 and miRNA-690

Trichloroethene (TCE), an occupational and ubiquitous environmental contaminant, is associated with the induction of autoimmune diseases (ADs). Although oxidative stress plays a major role in TCE-mediated autoimmunity, the underlying molecular mechanisms still need to be delineated. Altered non-coding RNAs, including the expression of microRNAs (miRNAs), can influence target genes, especially related to apoptosis and inflammation, and contribute to ADs. Therefore, the objective of this study was to delineate the contribution of miRNAs in TCE-mediated inflammatory and autoimmune response. To achieve this, we treated female MRL+/+ mice with TCE (10 mmol/kg in corn oil, i.p., every fourth day) with/without antioxidant sulforaphane (SFN; 8 mg/kg in corn oil, i.p., every other day) for 6 weeks. With the use of miRNA microarray, 293 miRNAs were analyzed, which included 35 miRNAs that were relevant to inflammation and ADs. Among those 35 miRNAs, 8 were modulated by TCE and/or TCE+SFN exposure. TCE treatment led to increased expression of 3 miRNAs and also decreased expression of 3 miRNAs. Interestingly, among the 35 differentially expressed miRNAs, antioxidant SFN modulated the expression of 6 miRNAs. Based on the microarray findings, we subsequently focused on two miRNAs (miRNA-21 and miRNA-690), which are known to be involved in inflammation and autoimmune response. The increases in miRNA-21 and miR-690 (observed using miRNA microarray) were further validated by RT-PCR, and the TCE-mediated increases in miR-21 and miR-690 were ameliorated by SFN treatment. Modulating miR-21 and miR-690 by respective inhibitors or mimics suppressed the expression of NF-κB (p65) and IL-12 in RAW 264.7 cells. Our findings suggest a contributory role of miR-21 and miR-690 in TCE-mediated and its metabolite dichloroacetyl chloride (DCAC)-mediated inflammation and autoimmune response and support that antioxidant SFN could be a potential therapeutic candidate for inflammatory responses and ADs.

Regulatory roles of MicroRNA in shaping T cell function, differentiation and polarization

T lymphocytes are an integral component of adaptive immunity with pleotropic effector functions. Impairment of T cell activity is implicated in various immune pathologies including autoimmune diseases, AIDS, carcinogenesis, and periodontitis. Evidently, T cell differentiation and function are under robust regulation by various endogenous factors that orchestrate underlying molecular pathways. MicroRNAs (miRNA) are a class of noncoding, regulatory RNAs that post-transcriptionally control multiple mRNA targets by sequence-specific interaction. In this article, we will review the recent progress in our understanding of miRNA-gene networks that are uniquely required by specific T cell effector functions and provide miRNA-mediated mechanisms that govern the fate of T cells. A subset of miRNAs may act in a synergistic or antagonistic manner to exert functional suppression of genes and regulate pathways that control T cell activation and differentiation. Significance of T cell-specific miRNAs and their dysregulation in immune-mediated diseases is discussed. Exosome-mediated horizontal transfer of miRNAs from antigen presenting cells (APCs) to T cells and from one T cell to another T cell subset and their impact on recipient cell functions is summarized.

Differential Leukocyte MicroRNA Responses Following Pan T Cell, Allorecognition and Allosecretome-Based Therapeutic Activation

Effective immunomodulation of T-cell responses is critical in treating both autoimmune diseases and cancer. Our previous studies have demonstrated that secretomes derived from control or methoxypolyethylene glycol mixed lymphocyte alloactivation assays exerted potent immunomodulatory activity that was mediated by microRNAs (miRNA). The immunomodulatory effects of biomanufactured miRNA-based allo-secretome therapeutics (SYN, TA1, IA1 and IA2) were compared to Pan T-cell activators (PHA and anti-CD3/CD28) and lymphocyte alloactivation. The differential effects of these activation strategies on resting peripheral blood mononuclear cells (PBMC) were assessed via T-cell proliferation, subset analysis and miRNA expression profiles. Mitogen-induced PBMC proliferation (> 85%) significantly exceeded that arising from either allostimulation (~ 30%) or the pro-inflammatory IA1 secretome product (~ 12%). Consequent to stimulation, the ratio of CD4 to CD8 cells of the resting PBMC (CD4:CD8; 1.7 ± 0.1) decreased in the Pan T cell, allrecognition and IA1 activated cells (averages of 1.1 ± 0.2; 1.2 ± 0.1 and 1.0 ± 0.1). These changes arose consequent to the expansion of both CD4⁺CD8⁺ and CD4^–CD8^– populations as well as the shrinkage of the CD4 subset and the expansion of the CD8 T cells. Importantly, these activation strategies induced vastly different miRNA expression profiles which were associated with significant differences in cellular differentiation and biological function. These findings support the concept that the “differential patterns of miRNA expression” regulate the biologic immune response in a “lock and key” manner. The biomanufacturing of miRNA-enriched secretome biotherapeutics may be a successful therapeutic approach for the systemic treatment of autoimmune diseases (TA1) and cancer (IA1).

Highlighting the interplay of microRNAs from Leishmania parasites and infected-host cells

Leishmania parasites, the causative agents of leishmaniasis, are protozoan parasites with the ability to modify the signalling pathway and cell responses of their infected host cells. These parasite strategies alter the host cell environment and conditions favouring their replication, survival and pathogenesis. Since microRNAs (miRNAs) are able to post-transcriptionally regulate gene expression processes, these biomolecules can exert critical roles in controlling Leishmania-host cell interplay. Therefore, the identification of relevant miRNAs differentially expressed in Leishmania parasites as well as in infected cells, which affect the host fitness, could be critical to understand the infection biology, pathogenicity and immune response against these parasites. Accordingly, the current review aims to address the differentially expressed miRNAs in both, the parasite and infected host cells and how these biomolecules change cell signalling and host immune responses during infection. A deep understanding of these processes could provide novel guidelines and therapeutic strategies for managing and treating leishmaniasis.

miR-21 sustains CD28 signalling and low-affinity T-cell responses at the expense of self-tolerance

Objective

miR-21 is highly expressed in iNKT and activated T cells, but its T-cell autonomous functions are poorly defined. We sought to investigate the role of miR-21 in the development and functions of T and iNKT cells, representing adaptive and innate-like populations, respectively.

Methods

We studied mice with a conditional deletion of miR-21 in all mature T lymphocytes.

Results

Thymic and peripheral T and iNKT compartments were normal in miR-21 KO mice. Upon activation in vitro, miR-21 depletion reduced T-cell survival, T_H17 polarisation and, remarkably, T- and iNKT cell ability to respond to low-affinity antigens, without altering their response to high-affinity ones. Mechanistically, miR-21 sustained CD28-dependent costimulation pathways required to lower the T-cell activation threshold, inhibiting its repressors in a positive feedback circuit, in turn increasing T-cell sensitivity to antigenic stimulation and survival. Upon immunisation with the low-affinity self-epitope MOG_35-55, miR-21 KO mice were indeed less susceptible than WT animals to the induction of experimental autoimmune encephalomyelitis, whereas they mounted normal T-cell responses against high-affinity viral epitopes generated upon lymphocytic choriomeningitis virus infection.

Conclusion

The induction of T-cell responses to weak antigens (signal 1) depends on CD28 costimulation (signal 2). miR-21 sustains CD28 costimulation, decreasing the T-cell activation threshold and increasing their sensitivity to antigenic stimulation and survival, broadening the immune surveillance range. This occurs at the cost of unleashing autoimmunity, resulting from the recognition of weak self-antigens by autoreactive immune responses. Thus, miR-21 fine-tunes T-cell response and self-/non-self-discrimination.

MicroRNA-21 Deficiency Promotes the Early Th1 Immune Response and Resistance toward Visceral Leishmaniasis

MicroRNA-21 (miR-21) inhibits IL-12 expression and impairs the Th1 response necessary for control of Leishmania infection. Recent studies have shown that Leishmania infection induces miR-21 expression in dendritic cells and macrophages, and inhibition of miR-21 restores IL-12 expression. Because miR-21 is known to be expressed due to inflammatory stimuli in a wide range of hematopoietic cells, we investigated the role of miR-21 in regulating immune responses during visceral leishmaniasis (VL) caused by Leishmania donovani infection. We found that miR-21 expression was significantly elevated in dendritic cells, macrophages, inflammatory monocytes, polymorphonuclear neutrophils, and in the spleen and liver tissues after L. donovani infection, concomitant with an increased expression of disease exacerbating IL-6 and STAT3. Bone marrow dendritic cells from miR-21 knockout (miR-21KO) mice showed increased IL-12 production and decreased production of IL-10. On L. donovani infection, miR-21KO mice exhibited significantly greater numbers of IFN-γ- and TNF-α-producing CD4⁺ and CD8⁺ T cells in their organs that was associated with increased production of Th1-associated IFN-γ, TNF-α, and NO from the splenocytes. Finally, miR-21KO mice displayed significantly more developing and mature hepatic granulomas leading to reduction in organ parasitic loads compared with wild type counterparts. Similar results were noted in L. donovani-infected wild type mice after transient miR-21 depletion. These observations indicate that miR-21 plays a critical role in pathogenesis of VL by suppressing IL-12- and Th1-associated IFN-γ and also inducing disease-promoting induction of the IL-6 and STAT-3 signaling pathway. miR-21 could therefore be used as a potential target for developing host-directed treatment for VL.

MiR-21 in the Cancers of the Digestive System and Its Potential Role as a Diagnostic, Predictive, and Therapeutic Biomarker

MicroRNAs (miRNAs) are small non-coding RNAs. They can regulate the expression of their target genes, and thus, their dysregulation significantly contributes to the development of cancer. Growing evidence suggests that miRNAs could be used as cancer biomarkers. As an oncogenic miRNA, the roles of miR-21 as a diagnostic and prognostic biomarker, and its therapeutic applications have been extensively studied. In this review, the roles of miR-21 are first demonstrated via its different molecular networks. Then, a comprehensive review on the potential targets and the current applications as a diagnostic and prognostic cancer biomarker and the therapeutic roles of miR-21 in six different cancers in the digestive system is provided. Lastly, a brief discussion on the challenges for the use of miR-21 as a therapeutic tool for these cancers is added.

microRNA-21: a key modulator in oncogenic viral infections

Oncogenic viruses are associated with approximately 15% of human cancers. In viral infections, microRNAs play an important role in host-pathogen interactions. miR-21 is a highly conserved non-coding RNA that not only regulates the development of oncogenic viral diseases, but also responds to the regulation of intracellular signal pathways. Oncogenic viruses, including HBV, HCV, HPV, and EBV, co-evolve with their hosts and cause persistent infections. The upregulation of host miR-21 manipulates key cellular pathways to evade host immune responses and then promote viral replication. Thus, a better understanding of the role of miR-21 in viral infections may help us to develop effective genetically-engineered oncolytic virus-based therapies against cancer.

Cartilage Protective and Immunomodulatory Features of Osteoarthritis Synovial Fluid-Treated Adipose-Derived Mesenchymal Stem Cells Secreted Factors and Extracellular Vesicles-Embedded miRNAs

Intra-articular administration of adipose-derived mesenchymal stem cells (ASCs), either in vitro expanded or within adipose tissue-based products obtained at point-of-care, has gained popularity as innovative regenerative medicine approach for osteoarthritis (OA) treatment. ASCs can stimulate tissue repair and immunomodulation through paracrine factors, both soluble and extracellular vesicles (EV) embedded, collectively defining the secretome. Interaction with the degenerative/inflamed environment is a crucial factor in understanding the finely tuned molecular message but, to date, the majority of reports have described ASC-secretome features in resting conditions or under chemical stimuli far from the in vivo environment of degenerated OA joints. In this report, the secretory profile of ASCs treated with native synovial fluid from OA patients was evaluated, sifting 200 soluble factors and 754 EV-embedded miRNAs. Fifty-eight factors and 223 EV-miRNAs were identified, and discussed in the frame of cartilage and immune cell homeostasis. Bioinformatics gave a molecular basis for M2 macrophage polarization, T cell proliferation inhibition and T reg expansion enhancement, as well as cartilage protection, further confirmed in an in vitro model of OA chondrocytes. Moreover, a strong influence on immune cell chemotaxis emerged. In conclusion, obtained molecular data support the regenerative and immunomodulatory properties of ASCs when interacting with osteoarthritic joint environment.

Long Non-coding RNA GAS5 Regulates T Cell Functions via miR21-Mediated Signaling in People Living With HIV

T cells are critical for the control of viral infections and T cell responses are regulated by a dynamic network of non-coding RNAs, including microRNAs (miR) and long non-coding RNAs (lncRNA). Here we show that an activation-induced decline of lncRNA growth arrest-specific transcript 5 (GAS5) activates DNA damage response (DDR), and regulates cellular functions and apoptosis in CD4 T cells derived from people living with HIV (PLHIV) via upregulation of miR-21. Notably, GAS5-miR21-mediated DDR and T cell dysfunction are observed in PLHIV on antiretroviral therapy (ART), who often exhibit immune activation due to low-grade inflammation despite robust virologic control. We found that GAS5 negatively regulates miR-21 expression, which in turn controls critical signaling pathways involved in DNA damage and cellular response. The sustained stimulation of T cells decreased GAS5, increased miR-21 and, as a result, caused dysfunction and apoptosis in CD4 T cells. Importantly, this inflammation-driven T cell over-activation and aberrant apoptosis in ART-controlled PLHIV and healthy subjects (HS) could be reversed by antagonizing the GAS5-miR-21 axis. Also, mutation of the miR-21 binding site on exon 4 of GAS5 gene to generate a GAS5 mutant abolished its ability to regulate miR-21 expression as well as T cell activation and apoptosis markers compared to the wild-type GAS5 transcript. Our data suggest that GAS5 regulates TCR-mediated activation and apoptosis in CD4 T cells during HIV infection through miR-21-mediated signaling. However, GAS5 effects on T cell exhaustion during HIV infection may be mediated by a mechanism beyond the GAS5-miR-21-mediated signaling. These results indicate that targeting the GAS5-miR-21 axis may improve activity and longevity of CD4 T cells in ART-treated PLHIV. This approach may also be useful for targeting other infectious or inflammatory diseases associated with T cell over-activation, exhaustion, and premature immune aging.

Clinical Significance of PDCD4 in Melanoma by Subcellular Expression and in Tumor-Associated Immune Cells

Simple Summary

While targeting programmed cell death (PDCD) 1 is a central treatment against melanoma, little is known about the related protein PDCD4. We defined differences in melanoma PDCD4 subcellular localization (either total cellular or nuclear-only) during oncogenesis, evaluated its presence on tumor-infiltrating immune cells, and determined its impact on survival. High PDCD4 expression resulted in improved survival in patients with primary and intracranial but not extracranial metastatic melanoma. High PDCD4 levels in surrounding tumor tissue were also associated with increased infiltrating immune cells. PDCD4 may be a potentially useful biomarker in melanoma to help guide our understanding of patient prognosis. Methods to increase PDCD4 in those with melanoma brain metastases may also help improve disease response.

Abstract

Little is known about the subcellular localization and function of programmed cell death 4 (PDCD4) in melanoma. Our past studies suggest PDCD4 interacts with Pleckstrin Homology Domain Containing A5 (PLEKHA5) to influence melanoma brain metastasis outcomes, as high intracranial PDCD4 expression leads to improved survival. We aimed to define the subcellular distribution of PDCD4 in melanoma and in the tumor microenvironment during neoplastic progression and its impact on clinical outcomes. We analyzed multiple tissue microarrays with well-annotated clinicopathological variables using quantitative immunofluorescence and evaluated single-cell RNA-sequencing on a brain metastasis sample to characterize PDCD4+ immune cell subsets. We demonstrate differences in PDCD4 expression during neoplastic progression, with high tumor and stromal PDCD4 levels associated with improved survival in primary melanomas and in intracranial metastases, but not in extracranial metastatic disease. While the expression of PDCD4 is well-documented on CD8+ T cells and natural killer cells, we show that it is also found on B cells and mast cells. PDCD4 expression in the tumor microenvironment is associated with increased immune cell infiltration. Further studies are needed to define the interaction of PDCD4 and PLEKHA5 and to evaluate the utility of this pathway as a therapeutic target in melanoma brain metastasis.

Quantitative and time-resolved miRNA pattern of early human T cell activation

T cells are central to the immune response against various pathogens and cancer cells. Complex networks of transcriptional and post-transcriptional regulators, including microRNAs (miRNAs), coordinate the T cell activation process. Available miRNA datasets, however, do not sufficiently dissolve the dynamic changes of miRNA controlled networks upon T cell activation. Here, we established a quantitative and time-resolved expression pattern for the entire miRNome over a period of 24 h upon human T-cell activation. Based on our time-resolved datasets, we identified central miRNAs and specified common miRNA expression profiles. We found the most prominent quantitative expression changes for miR-155-5p with a range from initially 40 molecules/cell to 1600 molecules/cell upon T-cell activation. We established a comprehensive dynamic regulatory network of both the up- and downstream regulation of miR-155. Upstream, we highlight IRF4 and its complexes with SPI1 and BATF as central for the transcriptional regulation of miR-155. Downstream of miR-155-5p, we verified 17 of its target genes by the time-resolved data recorded after T cell activation. Our data provide comprehensive insights into the range of stimulus induced miRNA abundance changes and lay the ground to identify efficient points of intervention for modifying the T cell response.

Impact of Bone Marrow miR-21 Expression on Acute Myeloid Leukemia T Lymphocyte Fragility and Dysfunction

BACKGROUND

Acute myeloid leukemia (AML) is a hematopoietic malignancy in which antitumor immunity is impaired. The therapeutic management of AML requires understanding the mechanisms involved in the fragility and immune dysfunction of AML T lymphocytes.

METHODS

In this study, T lymphocytes from healthy donors (HD) and AML patients were used. Extracellular vesicles (EVs) from leukemic cells were screened for their microRNA content and impact on T lymphocytes. Flow cytometry, transcriptomic as well as lentiviral transduction techniques were used to carry out the research.

RESULTS

We observed increased cell death of T lymphocytes from AML patients. EVs from leukemia myeloid cell lines harbored several miRNAs, including miR-21, and were able to induce T lymphocyte death. Compared to that in HD, miR-21 was overexpressed in both the bone marrow fluid and infiltrating T lymphocytes of AML patients. MiR-21 induces T lymphocyte cell death by upregulating proapoptotic gene expression. It also increases the immunosuppressive profile of T lymphocytes by upregulating the IL13, IL4, IL10, and FoxP3 genes.

CONCLUSIONS

Our results demonstrate that miR-21 plays a significant role in AML T lymphocyte dysfunction and apoptosis. Targeting miR-21 may be a novel approach to restore the efficacy of the immune response against AML.

Under-expression of microRNA-146a and 21 and their association with Crohn's disease

MicroRNAs (miRNAs) can post-transcriptionally regulate gene expression and are involved in the immune response. Excessive immune response to the gut microbiota plays a major role in the pathogenesis of Crohn's disease (CD). Regarding the role of miRNAs in immune response, this study aimed to investigate the contribution of miRNAs in the pathogenesis of CD. A total of 53 participants, including 23 CD patients and 30 healthy controls (HCs) were enrolled in this study. miRNAs, including miR-21, miR-29a, miR-29b, miR-31, miR-146a, miR-155, miR-181a, and miR-181c were evaluated via TaqMan MicroRNA Assays. Among the eight miRNAs, the amounts of miR-146a and miR-21 were significantly decreased in the CD patients relative to HC subjects. Moreover, we showed that there was a negative correlation between miR-146a and Harvey-Bradshaw index (HBI), as well as a positive correlation of miR-21 and miR-29b with HBI. Under-expression of miR-146a and miR-21, which are critical for the regulatory function of regulatory T cells (Tregs), is remarkably associated with CD.

Suppressing miR-21 activity in tumor-associated macrophages promotes an antitumor immune response

microRNA-21 (miR-21) is the most commonly upregulated miRNA in solid tumors. This cancer-associated microRNA (oncomiR) regulates various downstream effectors associated with tumor pathogenesis during all stages of carcinogenesis. In this study, we analyzed the function of miR-21 in noncancer cells of the tumor microenvironment to further evaluate its contribution to tumor progression. We report that the expression of miR-21 in cells of the tumor immune infiltrate, and in particular in macrophages, was responsible for promoting tumor growth. Absence of miR-21 expression in tumor- associated macrophages (TAMs), caused a global rewiring of their transcriptional regulatory network that was skewed toward a proinflammatory angiostatic phenotype. This promoted an antitumoral immune response characterized by a macrophage-mediated improvement of cytotoxic T-cell responses through the induction of cytokines and chemokines, including IL-12 and C-X-C motif chemokine 10. These effects translated to a reduction in tumor neovascularization and an induction of tumor cell death that led to decreased tumor growth. Additionally, using the carrier peptide pH (low) insertion peptide, we were able to target miR-21 in TAMs, which decreased tumor growth even under conditions where miR-21 expression was deficient in cancer cells. Consequently, miR-21 inhibition in TAMs induced an angiostatic and immunostimulatory activation with potential therapeutic implications.

Novel Applications of Mesenchymal Stem Cell-derived Exosomes for Myocardial Infarction Therapeutics

Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity globally, representing approximately a third of all deaths every year. The greater part of these cases is represented by myocardial infarction (MI), or heart attack as it is better known, which occurs when declining blood flow to the heart causes injury to cardiac tissue. Mesenchymal stem cells (MSCs) are multipotent stem cells that represent a promising vector for cell therapies that aim to treat MI due to their potent regenerative effects. However, it remains unclear the extent to which MSC-based therapies are able to induce regeneration in the heart and even less clear the degree to which clinical outcomes could be improved. Exosomes, which are small extracellular vesicles (EVs) known to have implications in intracellular communication, derived from MSCs (MSC-Exos), have recently emerged as a novel cell-free vector that is capable of conferring cardio-protection and regeneration in target cardiac cells. In this review, we assess the current state of research of MSC-Exos in the context of MI. In particular, we place emphasis on the mechanisms of action by which MSC-Exos accomplish their therapeutic effects, along with commentary on the current difficulties faced with exosome research and the ongoing clinical applications of stem-cell derived exosomes in different medical contexts.

Role of exosomal miR‑21 in the tumor microenvironment and osteosarcoma tumorigenesis and progression (Review)

Osteosarcoma is the most common bone tumor affecting both adolescents and children. Early detection is critical for the effective treatment of the disease. Derived from cancer cells, miR‑21 contained within exosomes in the tumor microenvironment may act on both cancer cells and the surrounding tumor microenvironment (TME), including immune cells, endothelial cells and fibroblasts. In human serum and plasm, the level of exosomal miR‑21 between osteosarcoma patients and healthy controls differs, supporting the role of miR‑21 as a biomarker for osteosarcoma. The involvement of a number of miR‑21 target genes in tumor progression suggests that miR‑21 may significantly affect the plasticity of cancer cells, leading to tumor progression, metastasis, angiogenesis and immune escape in osteosarcoma. Understanding the biogenesis and functions of exosomal miR‑21 is of great value for the diagnosis and therapy of cancer, including osteosarcoma. The present review discusses the role of miR‑21 in the tumor microenvironment, and in the development and progression of osteosarcoma, with an aim to summarize the functions of this miRNA in cancer.

Non-coding RNAs in CD8 T cell biology

CD8 T cells are among the most vigorous soldiers of the immune system that fight viral infections and cancer. CD8 T cell development, maintenance, activation and differentiation are under the tight control of multiple transcriptional and post-transcriptional networks. Over the last two decades it has become clear that non-coding RNAs (ncRNAs), which consist of microRNAs (miRNAs) and long ncRNAs (lncRNAs), have emerged as global biological regulators. While our understanding of the function of specific miRNAs has increased since the discovery of RNA interference, it is still very limited, and the field of lncRNAs is just starting to blossom. Here we will summarize our knowledge on the role of ncRNAs in CD8 T cell biology, including differentiation into memory and exhausted cells.

MicroRNA-21-5p participates in IgA nephropathy by driving T helper cell polarization

BACKGROUND

Previous studies have revealed abnormal lymphocyte subsets in IgA nephropathy (IgAN). Some microRNAs have been reported to influence T helper differentiation. Here, we explored the underlying mechanism regarding how miRNAs regulate lymphocyte subsets in IgAN.

METHODS

First, miRNA and mRNA profiles in PBMCs from IgAN patients and controls were obtained by next-generation sequencing and gene expression array. The target miRNAs and mRNAs were identified through combined analysis. Then, in an independent population, we detected the expression of target miRNA in CD3⁺ T cells and CD19⁺ B cells. Next, we detected T helper cell subgroups and plasma IgA1 levels in another independent population and analyzed the correlations between them.

RESULTS

In total, 22 differentially expressed miRNAs were identified between IgAN patients and controls. Among them, microRNA-21-5p (miR-21) showed the highest expression, and SPRY1, SPRY2, and FASLG were chosen as miR-21 target genes. Then, we confirmed elevated miR-21 levels in CD3⁺ T cells of IgAN patients. Accordingly, decreased mRNA levels of SPRY1, SPRY2, and FASLG were found, and miR-21 showed a significant negative correlation with SPRY1 levels in CD3⁺ T cells of IgAN patients. Finally, we revealed that the proportion of Th17 cells was significantly elevated in IgAN patients and negatively correlated with SPRY1 expression. Furthermore, the proportion of Th17 cells showed a positive correlation trend with plasma IgA1 levels.

CONCLUSIONS

Our results suggested that in IgAN, the upregulated miR-21 expression in T lymphocytes inhibited SPRY1 expression and thereby induced Th17 polarization, which might influence the characteristic feature of IgA1 overproduction in IgAN patients.

Induction of miR 21 impairs the anti-Leishmania response through inhibition of IL-12 in canine splenic leukocytes

Visceral Leishmaniasis is a chronic zoonosis and, if left untreated, can be fatal. Infected dogs have decreased cellular immunity (Th1) and develop a potent humoral response (Th2), which is not effective for elimination of the protozoan. Immune response can be modulated by microRNAs (miRNAs), however, characterization of miRNAs and their possible regulatory role in the spleen of infected dogs have not been done. We evaluated miRNA expression in splenic leukocytes (SL) from dogs naturally infected with Leishmania infantum and developing leishmaniasis (CanL; n = 8) compared to healthy dogs (n = 4). Microarray analysis showed increased expression of miR 21, miR 148a, miR 7 and miR 615, and downregulation of miR 150, miR 125a and miR 125b. Real-time PCR validated the differential expression of miR 21, miR 148a and miR 615. Further, decrease of miR 21 in SL, by means of transfection with a miR 21 inhibitor, increased the IL-12 cytokine and the T-bet/GATA-3 ratio, and decreased parasite load on SL of dogs with CanL. Taken together, these findings suggest that L. infantum infection alters splenic expression of miRNAs and that miR 21 interferes in the cellular immune response of L. infantum-infected dogs, placing this miRNA as a possible therapeutic target in CanL.

MiRNA as biomarker for uveitis - A systematic review of the literature

AIM

A systematic review of miRNA profiling studies in uveitis.

METHODS

Literature search strategy - Pubmed central central database, using miRNA/microRNA and intraocular inflammation/uveitis as keywords.

RESULTS

We found twenty publications regarding the experimental and clinical use of miRNA in uveitis, published between 2011 and 2018.

CONCLUSION

The publications regarding the role of miRNA in uveitis are very scarce, but provide some valuable information about the potential new mechanisms in uveitis. Some of the identified miRNAs in different uveitis entities could serve as a biomarker of intraocular inflammation. Possible candidate miRNAs could be let-7e, miRNA-1, miR-9-3, miR-20a-5p, miR-23a, mir-29a-3p, miR-140-5p, miR-143, miR-146a and miR-146a-5p, miR-155, miR-182 and miR-182-5p, miR-196a2, miR-205, miR-223-3p, miR-301a. MiR-146a, miR-146a-5p, miR-155, miR-182, miR-223-3p, have been found to be possibly associated with uveitis disease in both, human and animal species.

Enhancing the pro-inflammatory anti-cancer T cell response via biomanufactured, secretome-based, immunotherapeutics

T lymphocytes play a critical role in the pro-inflammatory anti-cancer response; hence, significant pharmacologic efforts have been made to enhance the endogenous T cell response. Unfortunately, significant toxicity arises consequent to pan T cell activation. In contrast, the less robust T cell alloresponse has also demonstrated an anti-cancer effect, but poses an inherent risk of GvHD. To overcome the GvHD risk, an acellular pro-inflammatory agent (IA1) has been biomanufactured from the secretome of the allorecognition response. To assess IA1's immunomodulatory activity, T cell proliferation and differentiation were determined in vitro. The pro-inflammatory properties of the IA1 therapeutic were mediated by the miRNA-enriched fractions. Moreover, cross-species efficacy was observed consequent to the evolutionary conservation of miRNA. IA1 exerted no toxicity to resting PBMC but induced significant proliferation of resting CD3⁺ (CD4⁺ and CD8⁺) T cells and skewed the response towards a pro-inflammatory state (i.e., increased Teff:Treg ratio). Crucially, IA1-activated PBMC demonstrated a potent inhibition of cancer cell (HeLa and SH-4 melanoma) proliferation relative to the resting PBMC. The anti-proliferation effect of IA1-activated PBMC was noted within ˜12 h versus 4-5 days for resting cells. A second biomanufactured therapeutic (IA2; produced using HeLa cells) surprisingly demonstrated direct toxicity to cancer cells but was less effective than IA1 in inducing a cell-mediated response. This study demonstrates that miRNA-enriched therapeutics can be biomanufactured from the secretome and can induce a potent pro-inflammatory, anti-cancer, effect on resting lymphocytes.

Relationship of peripheral blood mononuclear cells miRNA expression and parasitic load in canine visceral leishmaniasis

Visceral leishmaniasis (VL) in humans is a chronic and often fatal disease if left untreated. Dogs appear to be the main reservoir host for L. infantum infection, however, in many regions other canids such as jackals, foxes, wolves and other mammals, such as hares or black rats, have been implicated as wild reservoirs. Most dogs cannot form an effective immune response against this infection, and this could be modulated by small non-coding RNAs, called microRNAs, responsible for post-transcriptional control of gene expression. Here, we evaluated the expression of miRNAs in peripheral blood mononuclear cells (PBMC) of symptomatic dogs naturally infected with Leishmania (L.) infantum (n = 10) and compared to those of healthy dogs (n = 5). Microarray analysis revealed that miR-21, miR-424, miR-194 and miR-451 had a 3-fold increase in expression, miR-192, miR-503, and miR-371 had a 2-fold increase in expression, whereas a 2-fold reduction in expression was observed for miR-150 and miR-574. Real-time PCR validated the differential expression of miR-21, miR-150, miR-451, miR-192, miR-194, and miR-371. Parasite load of PBMC was measured by real-time PCR and correlated to the differentially expressed miRNAs, showing a strong positive correlation with expression of miR-194, a regular positive correlation with miR-371 expression, and a moderate negative correlation with miR-150 expression in PBMC. These findings suggest that Leishmania infection interferes with miRNAs expression in PBMC, and their correlation with parasite load may help in the identification of therapeutic targets in Canine Visceral Leishmaniasis (CVL).

miRNA miR-21 Is Largely Dispensable for Intrathymic T-Cell Development

Development of T cells in the thymus is tightly controlled to continually produce functional, but not autoreactive, T cells. miRNAs provide a layer of post-transcriptional gene regulation to this process, but the role of many individual miRNAs in T-cell development remains unclear. miR-21 is prominently expressed in immature thymocytes followed by a steep decline in more mature cells. We hypothesized that such a dynamic expression was indicative of a regulatory function in intrathymic T-cell development. To test this hypothesis, we analyzed T-cell development in miR-21-deficient mice at steady state and under competitive conditions in mixed bone-marrow chimeras. We complemented analysis of knock-out animals by employing over-expression in vivo. Finally, we assessed miR-21 function in negative selection in vivo as well as differentiation in co-cultures. Together, these experiments revealed that miR-21 is largely dispensable for physiologic T-cell development. Given that miR-21 has been implicated in regulation of cellular stress responses, we assessed a potential role of miR-21 in endogenous regeneration of the thymus after sublethal irradiation. Again, miR-21 was completely dispensable in this process. We concluded that, despite prominent and highly dynamic expression in thymocytes, miR-21 expression was not required for physiologic T-cell development or endogenous regeneration.

miR-21 depletion in macrophages promotes tumoricidal polarization and enhances PD-1 immunotherapy

MicroRNA-21 (miR-21) is one of the most abundant microRNAs in mammalian cells. It has been intensively studied for its role in regulating apoptosis and oncogenic transformation. However, the impact of miR-21 on host anti-tumor immunity remains unknown. Tumor-associated macrophages are a major leukocyte type that infiltrates tumors and predominantly develops into immunosuppressive, tumor-promoting M2-like macrophages. In contrast, the pro-inflammatory M1-like macrophages have tumoricidal activity. In this study, we show that genetic deficiency of miR-21 promotes the polarization of macrophages toward an M1-like phenotype in vivo and in vitro in the presence of tumor cells; thus it confers host mice with enhanced anti-tumor immunity. By downregulating JAK2 and STAT1, miR-21 inhibits the IFN-γ-induced STAT1 signaling pathway, which is required for macrophage M1 polarization. We also show that the expression of miR-21 in macrophages is regulated upon polarization stimuli as well as upon macrophages co-culturing with tumor cells. Thus, tumor cells may stimulate miR-21 expression in tumor-associated macrophages to prevent tumoricidal M1 polarization. However, augmented STAT1 signaling mediated by miR-21 deficiency upregulates PD-L1 expression in macrophages, which is known to inhibit phagocytic anti-tumor activity. This adverse effect can be alleviated by PD-1 blockade; indeed, miR-21 depletion in macrophages and PD-1 antibody treatment offer superior anti-tumor activity than either agent alone. These studies shed lights on potential application of the combination of miR-21 inhibition and immune checkpoint blockade to target the tumor microenvironment.

A potential microRNA regulation of immune-related genes in invertebrate haemocytes

Bivalve mollusks have been employed as sentinel organisms in environmental health programs due to their sedentary lifestyle, filter-feeding behavior and their ability to accumulate pathogens or toxin molecules inside tissues. Endocrine disrupting chemicals (EDCs) can be up taken and bioaccumulated, and due to sensibility of mollusks to these EDCs, being able to cause immune alterations. Recently, microRNAs (miRNAs) were shown to be involved in modulation and buffering developmental processes against the effects of environmental alterations and pathogenic microorganisms. Moreover, it is suggested that this miRNAs are incorporated into the estrogen-controlled immune network, regulating mechanism of immune gene expression at the posttranscriptional level, modulating immune responses as phagocytosis, redox reaction and apoptosis in bivalve haemocytes. Thus, miRNAs can be used as biomarkers that specifically elucidate immunotoxic effects caused by exogenous biotic or abiotic factors, and can act as useful tools in integrated monitoring environmental health programs. In this review, we aim to describe the investigations that have been carried out on miRNAs in bivalve mollusks, especially those associated with immune responses against infectious agents and xenobiotic exposure.

Downregulation of MicroRNA eca-mir-128 in Seminal Exosomes and Enhanced Expression of CXCL16 in the Stallion Reproductive Tract Are Associated with Long-Term Persistence of Equine Arteritis Virus

Equine arteritis virus (EAV) can establish long-term persistent infection in the reproductive tract of stallions and is shed in the semen. Previous studies showed that long-term persistence is associated with a specific allele of the CXCL16 gene (CXCL16S) and that persistent infection is maintained despite the presence of a local inflammatory and humoral and mucosal antibody responses. In this study, we demonstrated that equine seminal exosomes (SEs) are enriched in a small subset of microRNAs (miRNAs). Most importantly, we demonstrated that long-term EAV persistence is associated with the downregulation of an SE-associated miRNA (eca-mir-128) and with an enhanced expression of CXCL16 in the reproductive tract, a putative target of eca-mir-128. The findings presented here suggest that SE eca-mir-128 is implicated in the regulation of the CXCL16/CXCR6 axis in the reproductive tract of persistently infected stallions, a chemokine axis strongly implicated in EAV persistence. This is a novel finding and warrants further investigation to identify its specific mechanism in modulating the CXCL16/CXCR6 axis in the reproductive tract of the EAV long-term carrier stallion.IMPORTANCE Equine arteritis virus (EAV) has the ability to establish long-term persistent infection in the stallion reproductive tract and to be shed in semen, which jeopardizes its worldwide control. Currently, the molecular mechanisms of viral persistence are being unraveled, and these are essential for the development of effective therapeutics to eliminate persistent infection. Recently, it has been determined that long-term persistence is associated with a specific allele of the CXCL16 gene (CXCL16S) and is maintained despite induction of local inflammatory, humoral, and mucosal antibody responses. This study demonstrated that long-term persistence is associated with the downregulation of seminal exosome miRNA eca-mir-128 and enhanced expression of its putative target, CXCL16, in the reproductive tract. For the first time, this study suggests complex interactions between eca-mir-128 and cellular elements at the site of EAV persistence and implicates this miRNA in the regulation of the CXCL16/CXCR6 axis in the reproductive tract during long-term persistence.

MicroRNA Profiling in Asthma: Potential Biomarkers and Therapeutic Targets

Asthma is a heterogeneous chronic inflammatory disorder in which different endotypes contribute to define clinical inflammatory phenotypes. MicroRNAs (miRNAs) are a group of minute, endogenous 22-25 nt RNA elements that join to particular mRNAs to reduce translation and increase messenger RNA degradation. miRNAs operate in post-transcriptional control and regulate physiological and pathological processes in several illnesses. The purpose of this work is to review and discuss the current knowledge about the function of miRNAs in asthma, focusing particularly on their biological properties, pathophysiologic actions, and possible use as markers and treatments for asthma.

Hypermethylation of MIR21 in CD4+ T cells from patients with relapsing-remitting multiple sclerosis associates with lower miRNA-21 levels and concomitant up-regulation of its target genes

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system caused by genetic and environmental factors. DNA methylation, an epigenetic mechanism that controls genome activity, may provide a link between genetic and environmental risk factors.

OBJECTIVE

We sought to identify DNA methylation changes in CD4+ T cells in patients with relapsing-remitting (RR-MS) and secondary-progressive (SP-MS) disease and healthy controls (HC).

METHODS

We performed DNA methylation analysis in CD4+ T cells from RR-MS, SP-MS, and HC and associated identified changes with the nearby risk allele, smoking, age, and gene expression.

RESULTS

We observed significant methylation differences in the VMP1/MIR21 locus, with RR-MS displaying higher methylation compared to SP-MS and HC. VMP1/MIR21 methylation did not correlate with a known MS risk variant in VMP1 or smoking but displayed a significant negative correlation with age and the levels of mature miR-21 in CD4+ T cells. Accordingly, RR-MS displayed lower levels of miR-21 compared to SP-MS, which might reflect differences in age between the groups, and healthy individuals and a significant enrichment of up-regulated miR-21 target genes.

CONCLUSION

Disease-related changes in epigenetic marking of MIR21 in RR-MS lead to differences in miR-21 expression with a consequence on miR-21 target genes.

Hypermethylation of MIR21 in CD4+ T cells from patients with relapsing-remitting multiple sclerosis associates with lower miRNA-21 levels and concomitant up-regulation of its target genes

Background:

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system caused by genetic and environmental factors. DNA methylation, an epigenetic mechanism that controls genome activity, may provide a link between genetic and environmental risk factors.

Objective:

We sought to identify DNA methylation changes in CD4+ T cells in patients with relapsing-remitting (RR-MS) and secondary-progressive (SP-MS) disease and healthy controls (HC).

Methods:

We performed DNA methylation analysis in CD4+ T cells from RR-MS, SP-MS, and HC and associated identified changes with the nearby risk allele, smoking, age, and gene expression.

Results:

We observed significant methylation differences in the VMP1/MIR21 locus, with RR-MS displaying higher methylation compared to SP-MS and HC. VMP1/MIR21 methylation did not correlate with a known MS risk variant in VMP1 or smoking but displayed a significant negative correlation with age and the levels of mature miR-21 in CD4+ T cells. Accordingly, RR-MS displayed lower levels of miR-21 compared to SP-MS, which might reflect differences in age between the groups, and healthy individuals and a significant enrichment of up-regulated miR-21 target genes.

Conclusion:

Disease-related changes in epigenetic marking of MIR21 in RR-MS lead to differences in miR-21 expression with a consequence on miR-21 target genes.

Exosomes carrying immunoinhibitory proteins and their role in cancer

Recent emergence of exosomes as information carriers between cells has introduced us to a new previously unknown biological communication system. Multi-directional cross-talk mediated by exosomes carrying proteins, lipids and nucleic acids between normal cells, cells harbouring a pathogen or cancer and immune cells has been instrumental in determining outcomes of physiological as well as pathological conditions. Exosomes play a key role in the broad spectrum of human diseases. In cancer, tumour-derived exosomes carry multiple immunoinhibitory signals, disable anti-tumour immune effector cells and promote tumour escape from immune control. Exosomes delivering negative signals to immune cells in cancer, viral infections, autoimmune or other diseases may interfere with therapy and influence outcome. Exosomes can activate tissue cells to produce inhibitory factors and thus can suppress the host immune responses indirectly. Exosomes also promise to be non-invasive disease biomarkers with a dual capability to provide insights into immune dysfunction as well as disease progression and outcome.

Argonaute 2 immunoprecipitation revealed large tumor suppressor kinase 1 as a novel proapoptotic target of miR-21 in T cells

MicroRNA (miR)-21 is an important suppressor of T-cell apoptosis that is also overexpressed in many types of cancers. The exact mechanisms underlying the antiapoptotic effects of miR-21 are not well understood. In this study, we used the Jurkat T-cell line as a model to identify apoptosis-associated miR-21 target genes. We showed that expression of miR-21 rapidly increases upon αCD3/αCD28 activation of Jurkat cells. Inhibition of miR-21 reduced cell growth which could be explained by an increase in apoptosis. MicroRNA target gene identification by AGO2 RNA-immunoprecipitation followed by gene expression microarray (RIP-Chip) resulted in the identification of 72 predicted miR-21 target genes that were at least twofold enriched in the AGO2-IP fraction of miR-21 overexpressing cells. Of these, 71 were at least twofold more enriched in the AGO2-IP fraction of miR-21 overexpressing cells as compared to AGO2-IP fraction of control cells. The target gene for which the AGO2-IP enrichment was most prominently increased upon miR-21 overexpression was the proapoptotic protein LATS1. Luciferase reporter assays and western blot analysis confirmed targeting of LATS1 by miR-21. qRT-PCR analysis in primary T cells showed an inverse expression pattern between LATS1 transcript levels and miR-21 upon T-cell stimulation. Finally, LATS1 knockdown partially rescued the miR-21 inhibition-induced impaired cell growth. Collectively, these data identify LATS1 as a miR-21 target important for the antiapoptotic function of miR-21 in T cells and likely also in many types of cancer.

Exosomes in Cancer: Another Mechanism of Tumor-Induced Immune Suppression

Exosomes are the smallest extracellular vesicles (EV) produced under physiological and pathological conditions by all cells and present in all body fluids. They are critical components of the intercellular communication network. Tumor cells release exosomes which are enriched in immunosuppressive molecules as well as biologically-active soluble factors and enzymes. Tumor-derived exosomes (TEX) interact with immune effector cells in the tumor microenvironment and in the circulation, deliver negative signals to these cells and interfere with their anti-tumor functions. By suppressing functions of immune effector cells, TEX promote tumor progression and facilitate tumor escape from the immune system. Thus, TEX can be viewed as immune checkpoint inhibitors. Silencing of TEX-mediated immune inhibition without disrupting the physiologically important cellular communication networks represents a considerable challenge. Current efforts are directed at achieving a better understanding of the role exosomes play in cancer progression and/or outcome and of molecular/genetic mechanisms responsible for immunoinhibitory activity of TEX.

Tumor-Derived Exosomes and Their Role in Tumor-Induced Immune Suppression

Tumor-derived exosomes (TEX) are emerging as critical components of an intercellular information network between the tumor and the host. The tumor escapes from the host immune system by using a variety of mechanisms designed to impair or eliminate anti-tumor immunity. TEX carrying a cargo of immunoinhibitory molecules and factors represent one such mechanism. TEX, which are present in all body fluids of cancer patients, deliver negative molecular or genetic signals to immune cells re-programming their functions. Although TEX can also stimulate immune activity, in the microenvironments dominated by the tumor, TEX tend to mediate immune suppression thus promoting tumor progression. The TEX content, in part resembling that of the parent cell, may serve as a source of cancer biomarkers. TEX also interfere with immune therapies. A better understanding of TEX and their contribution to cancer progression and cancer patients’ response to immune therapies represents a challenging new field of investigation.

The MicroRNA-21 in Autoimmune Diseases

MicroRNA-21 (miR-21) is an oncomiR and significantly upregulated in a wide range of cancers. It is strongly involved in apoptosis and oncogenesis, since most of its reported targets are tumor suppressors. Recently, miR-21 was found to be correlated with the pathogenesis of autoimmune diseases and may play an essential role in regulating autoimmune responses. In particular, miR-21 promotes Th17 cell differentiation, which mediates the development of multiple autoimmune diseases. In this article, we review the current research on the mechanisms that regulate miR-21 expression, the potential of miR-21 as a diagnostic biomarker for autoimmune disease and the mechanisms by which miR-21 promotes the development of autoimmune disease. We also discussed the therapeutic potential of targeting miR-21 in treating patients with autoimmune disease.

Differential regulation of miR-146a/FAS and miR-21/FASLG axes in autoimmune lymphoproliferative syndrome due to FAS mutation (ALPS-FAS)

Most cases of autoimmune lymphoproliferative syndrome (ALPS) have an inherited genetic defect involving apoptosis-related genes of the FAS pathway. MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs playing a role in the control of gene expression. This is the first report on miRNAs in ALPS patients. We studied a mother and son carrying the same FAS cell surface death receptor (FAS) mutation, but with only the son manifesting the signs and symptoms of ALPS-FAS. The aim was to analyse, by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), the peripheral blood mononuclear cells (PBMC) relative expression of miR-146a and miR-21, including their passenger strands and respective targets (FAS and FASLG). In comparison with healthy matched control individuals, miR-21-3p was over-expressed significantly (P = 0·0313) in the son, with no significant change in the expression of miR-146a, miR-146a-3p and miR-21. In contrast, the mother had a slight under-expression of the miR-146a pair and miR-21-3p (P = 0·0625). Regarding the miRNA targets, FAS was up-regulated markedly for the mother (P = 0·0078), but down-regulated for the son (P = 0·0625), while FASLG did not have any significant alteration. Taken together, our finding clearly suggests a role of the miR-146a/FAS axis in ALPS-FAS variable expressivity in which FAS haploinsufficiency seems to be compensated only in the mother who had the miR-146a pair down-regulated. As only the son had the major clinical manifestations of ALPS-FAS, miR-21-3p should be investigated as playing a critical role in ALPS physiopathology, including the development of lymphoma.

Tumor-Derived Exosomes and Their Role in Cancer Progression

Tumor cells actively produce, release, and utilize exosomes to promote tumor growth. Mechanisms through which tumor-derived exosomes subserve the tumor are under intense investigation. These exosomes are information carriers, conveying molecular and genetic messages from tumor cells to normal or other abnormal cells residing at close or distant sites. Tumor-derived exosomes are found in all body fluids. Upon contact with target cells, they alter phenotypic and functional attributes of recipients, reprogramming them into active contributors to angiogenesis, thrombosis, metastasis, and immunosuppression. Exosomes produced by tumors carry cargos that in part mimic contents of parent cells and are of potential interest as noninvasive biomarkers of cancer. Their role in inhibiting the host antitumor responses and in mediating drug resistance is important for cancer therapy. Tumor-derived exosomes may interfere with cancer immunotherapy, but they also could serve as adjuvants and antigenic components of antitumor vaccines. Their biological roles in cancer development or progression as well as cancer therapy suggest that tumor-derived exosomes are critical components of oncogenic transformation.

Exosomes and tumor-mediated immune suppression

Tumor-derived exosomes (TEX) are harbingers of tumor-induced immune suppression: they carry immunosuppressive molecules and factors known to interfere with immune cell functions. By delivering suppressive cargos consisting of proteins similar to those in parent tumor cells to immune cells, TEX directly or indirectly influence the development, maturation, and antitumor activities of immune cells. TEX also deliver genomic DNA, mRNA, and microRNAs to immune cells, thereby reprogramming functions of responder cells to promote tumor progression. TEX carrying tumor-associated antigens can interfere with antitumor immunotherapies. TEX also have the potential to serve as noninvasive biomarkers of tumor progression. In the tumor microenvironment, TEX may be involved in operating numerous signaling pathways responsible for the downregulation of antitumor immunity.

Exosomes and tumor-mediated immune suppression

Tumor-derived exosomes (TEX) are harbingers of tumor-induced immune suppression: they carry immunosuppressive molecules and factors known to interfere with immune cell functions. By delivering suppressive cargos consisting of proteins similar to those in parent tumor cells to immune cells, TEX directly or indirectly influence the development, maturation, and antitumor activities of immune cells. TEX also deliver genomic DNA, mRNA, and microRNAs to immune cells, thereby reprogramming functions of responder cells to promote tumor progression. TEX carrying tumor-associated antigens can interfere with antitumor immunotherapies. TEX also have the potential to serve as noninvasive biomarkers of tumor progression. In the tumor microenvironment, TEX may be involved in operating numerous signaling pathways responsible for the downregulation of antitumor immunity.

Comprehensive RNA dataset of AGO2 associated RNAs in Jurkat cells following miR-21 over-expression

We set out to identify miR-21 targets in Jurkat cells using a high-throughput biochemical approach (10.1016/j.biochi.2014.09.021[1]). Using a specific monoclonal antibody raised against AGO2, RISC complexes were immunopurified in Jurkat cells over-expressing miR-21 following lentiviral trasduction as well as in Jurkat control cells lines. A parallel immunoprecipitation using isotype-matched rat IgG was performed as a control. AGO2 associated mRNAs were profiled by microarray (GEO: GSE37212). AGO2 bound miRNAs were profiled by RNA-seq.