An Update in Epigenetics in Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD) is characterized by hepatic steatosis accompanied by one of three features: overweight or obesity, T2DM, or lean or normal weight with evidence of metabolic dysregulation. It is distinguished by excessive fat accumulation in hepatocytes, and a decrease in the liver's ability to oxidize fats, the accumulation of ectopic fat, and the activation of proinflammatory pathways. Chronic damage will keep this pathophysiologic cycle active causing progression from hepatic steatosis to cirrhosis and eventually, hepatocarcinoma. Epigenetics affecting gene expression without altering DNA sequence allows us to study MAFLD pathophysiology from a different perspective, in which DNA methylation processes, histone modifications, and miRNAs expression have been closely associated with MAFLD progression. However, these considerations also faced us with the circumstance that modifying those epigenetics patterns might lead to MAFLD regression. Currently, epigenetics is an area of great interest because it could provide new insights in therapeutic targets and non-invasive biomarkers. This review comprises an update on the role of epigenetic patterns, as well as innovative therapeutic targets and biomarkers in MAFLD.

The regulatory network played by miRNAs during normal pregnancy and preeclampsia: a comparative study

Background: Preeclampsia is a pregnancy-specific syndrome, characterized by hypertension, proteinuria, and edema. Affecting between 2% and 8% of gestations worldwide, it accounts for 10% to 15% of maternal deaths. Although its etiology remains unclear, it includes complex pathological processes involving microRNAs, small non-coding RNA molecules with post-transcriptional repression effects on target mRNAs. Objective: To assess the expression of miRNAs during normal pregnancies and those complicated by preeclampsia, a sample of Venezuelan women were studied. Method: Nine placental microRNAs (hsa-miR- 20a-5p, 21-3p, 26a-5p, 181a-5p, 199a-5p, 210-3p, 222-5p, 223-3p, 424-3p) were measured in maternal plasma during the second and third trimesters of normal pregnancies, using a SYBR Green®-based real-time PCR, and compared the results against women affected by preeclampsia. Results: All assessed miRNAs were detected in maternal plasma in pregnancies with and without preeclampsia. All except miR-222 were over-expressed during disease when compared to the second and to third-trimester controls. miR-20a, miR-21, miR-26a, and miR-223 were down-regulated in the third trimester in comparison to the second trimester in normal pregnancies. Conclusion: The variation of the miRNAs expression through normal pregnancies suggested their involvement in normal physiological pregnancy processes. In contrast, the significant deregulation of the nine studied miRNAs during preeclampsia indicated the involvement of their target genes in the pathogenesis of the disease. miR-199a and miR-21-3p showed the greatest changes in expression. This study shows for the first time the presence of miR-20a, miR-199, and miR-424 and the variations they undergo in the plasma of pregnant women with preeclampsia.

Preeclamptic Women Have Disrupted Placental microRNA Expression at the Time of Preeclampsia Diagnosis: Meta-Analysis

Introduction: Preeclampsia (PE) is a pregnancy-associated, multi-organ, life-threatening disease that appears after the 20th week of gestation. The aim of this study was to perform a systematic review and meta-analysis to determine whether women with PE have disrupted miRNA expression compared to women who do not have PE.Methods: We conducted a systematic review and meta-analysis of studies that reported miRNAs expression levels in placenta or peripheral blood of pregnant women with vs. without PE. Studies published before October 29, 2021 were identified through PubMed, EMBASE and Web of Science. Two reviewers used predefined forms and protocols to evaluate independently the eligibility of studies based on titles and abstracts and to perform full-text screening, data abstraction and quality assessment. Standardized mean difference (SMD) was used as a measure of effect size.Results: 229 publications were included in the systematic review and 53 in the meta-analysis. The expression levels in placenta were significantly higher in women with PE compared to women without PE for miRNA-16 (SMD = 1.51,95%CI = 0.55–2.46), miRNA-20b (SMD = 0.89, 95%CI = 0.33–1.45), miRNA-23a (SMD = 2.02, 95%CI = 1.25–2.78), miRNA-29b (SMD = 1.37, 95%CI = 0.36–2.37), miRNA-155 (SMD = 2.99, 95%CI = 0.83–5.14) and miRNA-210 (SMD = 1.63, 95%CI = 0.69–2.58), and significantly lower for miRNA-376c (SMD = –4.86, 95%CI = –9.51 to –0.20). An increased level of miRNK-155 expression was found in peripheral blood of women with PE (SMD = 2.06, 95%CI = 0.35–3.76), while the expression level of miRNA-16 was significantly lower in peripheral blood of PE women (SMD = –0.47, 95%CI = –0.91 to –0.03). The functional roles of the presented miRNAs include control of trophoblast proliferation, migration, invasion, apoptosis, differentiation, cellular metabolism and angiogenesis.Conclusion: miRNAs play an important role in the pathophysiology of PE. The identification of differentially expressed miRNAs in maternal blood creates an opportunity to define an easily accessible biomarker of PE.

MiR-155: An Important Regulator of Neuroinflammation

MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression at the post-transcriptional level and that play an important role in many cellular processes, including modulation of inflammation. MiRNAs are present in high concentrations in the central nervous system (CNS) and are spatially and temporally expressed in a specific way. Therefore, an imbalance in the expression pattern of these small molecules can be involved in the development of neurological diseases. Generally, CNS responds to damage or disease through the activation of an inflammatory response, but many neurological disorders are characterized by uncontrolled neuroinflammation. Many studies support the involvement of miRNAs in the activation or inhibition of inflammatory signaling and in the promotion of uncontrolled neuroinflammation with pathological consequences. MiR-155 is a pro-inflammatory mediator of the CNS and plays an important regulatory role. The purpose of this review is to summarize how miR-155 is regulated and the pathological consequences of its deregulation during neuroinflammatory disorders, including multiple sclerosis, Alzheimer’s disease and other neuroinflammatory disorders. Modulation of miRNAs’ expression could be used as a therapeutic strategy in the treatment of pathological neuroinflammation.

The Association between Bisphenol A, Steroid Hormones, and Selected MicroRNAs Levels in Seminal Plasma of Men with Infertility

Bisphenol A (BPA), the most common endocrine-disrupting chemical, has been associated with male reproductive dysfunctions. Recently, it has been shown that BPA may also affect miRNAs expression. Herein, we aimed to evaluate the association of BPA levels with steroid hormone concentration and circulating miRNAs levels to investigate the potential direct effect of BPA on homeostasis in the testis environment. The level of BPA in the seminal plasma of azoospermic men was significantly higher compared to the healthy control. The concentrations of estradiol (E2) and androstenedione (A) were significantly decreased in the seminal plasma of azoospermic men compared to the normospermic men. The levels of miR-let-7a, miR-let-7b, and miR-let-7c were significantly up-regulated, and the level of miR-518f was significantly down-regulated in the seminal plasma of the azoospermic men compared to the healthy control. The level of BPA correlated negatively with sperm concentration and normal semen morphology. A significant positive correlation was found between BPA levels and miR-let-7a and miR-let-7c levels, whereas BPA negatively correlated with miR-518f levels. Our results suggest that BPA may negatively affect sperm quality. Moreover, BPA correlated with the miR-let-7a, miR-let-7c, and miR-518f levels in seminal plasma, which suggests that BPA may act directly in seminal plasma, affecting the testicular environment.

MicroRNAs Regulate Cell Cycle and Cell Death Pathways in Glioblastoma

Glioblastoma (GBM), a grade IV brain tumor, is known for its heterogenicity and its resistance to the current treatment regimen. Over the last few decades, a significant amount of new molecular and genetic findings has been reported regarding factors contributing to GBM’s development into a lethal phenotype and its overall poor prognosis. MicroRNA (miRNAs) are small non-coding sequences of RNA that regulate and influence the expression of multiple genes. Many research findings have highlighted the importance of miRNAs in facilitating and controlling normal biological functions, including cell differentiation, proliferation, and apoptosis. Furthermore, miRNAs’ ability to initiate and promote cancer development, directly or indirectly, has been shown in many types of cancer. There is a clear association between alteration in miRNAs expression in GBM’s ability to escape apoptosis, proliferation, and resistance to treatment. Further, miRNAs regulate the already altered pathways in GBM, including P53, RB, and PI3K-AKT pathways. Furthermore, miRNAs also contribute to autophagy at multiple stages. In this review, we summarize the functions of miRNAs in GBM pathways linked to dysregulation of cell cycle control, apoptosis and resistance to treatment, and the possible use of miRNAs in clinical settings as treatment and prediction biomarkers.

Vitamins a and D Enhance the Expression of Ror-γ-Targeting MiRNAs in a Mouse Model of Multiple Sclerosis

Background: Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system. Autoreactive T cells including cells with a Th17 phenotype are critical players in MS pathogenesis. In this study, we investigated the effects of VitA/D on miRNAs expression involved in Th17 development neuroinflammation using (EAE). Methods: EAE was induced in C57BL/6 mice and received IP injections of vitamins A, D or their combination starting one day before the immunization and continued every other day for 30 days. Animals were scored for 30 days. Percentages of Th17 cells were measured in splenocytes following in vitro re-stimulation with MOG using intracellular staining and flow cytometry. Expression of miR-98-5p and Let-7a-5p, two miRNAs that are known to target Ror-t and Ror-t was measured in MOG-stimulated splenocytes as well as in spinal cord tissues using real-time RT-PCR. Results: Treated mice showed decreased frequency of Th17 cells in their spleens following in vitro re-stimulation with antigen, also lower expression of IL17 and Ror-t in their in CNS and splenocytes. Vitamin A and vitamin D-treated splenocytes showed significant upregulation of miR-98-5p in 24 hour and 48 hours time-points and Let-7a-5p expression was induced at 48-hour post-treatment in MOG-treated cells, which showed a strong negative correlation with splenocyte Ror-t levels. Conclusion: Our data suggest that treatment with vitamins A and D can decreased differentiation of Th17 phenotype. This is likely due to upregulation of Ror-t-targeting miRNAs, miR-98-5p and Let-7a-5p following treatment. These findings point to a potential protective role for miRNAs in the context of autoimmune neuroinflammation.

Longitudinal Changes In Maternal Circulating Micrornas As Potential Biomarkers of Specific Events During Healthy Pregnancy

Background: Novel high-resolution tools for pregnancy monitoring, including early detection of prenatal disorders, are needed. Changes in circulating microRNAs (c-miRNAs) during pregnancy could potentially inform about the functional status of the mother, the placenta and/or the fetus. However, whether c-miRNA profiles actually reflect distinct pregnancy-specific events at all stages remains unclear.Methods: Longitudinal large-scale RNAseq c-miRNA profiles at early, middle and late pregnancy, and after birth derived from eight women with healthy term pregnancies (n=32 plasma samples) were compared against corresponding circulating profiles derived from age-matched non-pregnant women (n=10). Data of fetal sex and growth indicators obtained during pregnancy evolution of the same women, were used to identify specific c-miRNA correlates in circulation.Results: 1449 c-miRNAs were detected in circulation in both pregnant and non-pregnant women with only 48 c-miRNAs differentially expressed relative to non-pregnant controls in at least one of the four studied stages (FDR<0.05). Surprisingly, c-miRNA subpopulations with reported prominent expression in various pregnancy-associated compartments (placenta, amniotic fluid, umbilical cord plasma and breast milk) were found collectively under-expressed in maternal circulation throughout pregnancy (p<0.05). Furthermore, we found a bias in global miRNAs expression in direct association with fetal sex right from the first trimester, in addition to a specific c-miRNA signature of fetal growth (R = 0.7, p < 0.01).Conclusion: Our results demonstrate the existence of temporal changes in c-miRNAs populations associated to distinct aspects of pregnancy, including correlates of placental function and lactation, as well as fetal gender and growth, revealing a wider potential of c-miRNAs as biomarkers of specific aspects of maternal health and fetal growth.

Regulation of miRNAs Expression by Mutant p53 Gain of Function in Cancer

The p53 roles have been largely described; among them, cell proliferation and apoptosis control are some of the best studied and understood. Interestingly, the mutations on the six hotspot sites within the region that encodes the DNA-binding domain of p53 give rise to other very different variants. The particular behavior of these variants led to consider p53 mutants as separate oncogene entities; that is, they do not retain wild type functions but acquire new ones, namely Gain-of-function p53 mutants. Furthermore, recent studies have revealed how p53 mutants regulate gene expression and exert oncogenic effects by unbalancing specific microRNAs (miRNAs) levels that provoke epithelial-mesenchymal transition, chemoresistance, and cell survival, among others. In this review, we discuss recent evidence of the crosstalk between miRNAs and mutants of p53, as well as the consequent cellular processes dysregulated.

COT-3 Exosomal microRNA expression signature in blood and cerebrospinal fluid of glioblastoma patients

Analysis of exosomes derived from plasma or cerebrospinal fluid (CSF) has emerged as a promising biomarker platform for therapeutic monitoring in glioblastoma patients. However, the contents of the various subpopulations of exosomes in these clinical specimens remain poorly defined. Here we characterize the relative abundance of miRNA species in exosomes derived from the plasma and CSF of glioblastoma patients. To this end, we first employed miRNA arrays to measure the expression of exosomal miRNAs in the plasma from glioblastoma patients (n = 24) and healthy volunteers (n = 7) as control. In addition, we performed global miRNA profiling of exosomal miRNAs in the CSF from glioblastoma patients (n = 5) and non-tumoral patients (n = 3; hydrocephalus patients) as control. In plasma derived exosomes, 80 miRNAs were altered by &gt;2-fold in glioblastoma patients compared to controls. In CSF, 92 miRNAs were altered by &gt;2-fold in glioblastoma patients compared to controls. Combined analysis of plasma and CSF revealed a similar fold difference in eight miRNAs. Next, we measured these eight miRNAs expression in in the plasma from pre- and post-operative glioblastoma patients (n = 9). Among these eight miRNAs, we identified only one miRNA (miR-34b-3p) that was upregulated in exosomes from pre-operative glioblastoma patients. Our results suggest that miR-34b-3p might have a potential as a novel diagnostic marker or a therapeutic tool for glioblastoma patients.