Efficient delivery of miR-122 to regulate cholesterol metabolism using a non-covalent peptide-based strategy

MiRNA-122-5p inhibitor abolishes angiotensin II-mediated loss of autophagy and promotion of apoptosis in rat cardiofibroblasts by modulation of the apelin-AMPK-mTOR signaling

MicroRNAs (miRNAs) have emerged as essential regulators that could have pivotal roles in cardiac homeostasis and pathological remodeling of various cardiovascular diseases. We previously demonstrated that miRNA-122-5p overexpression exacerbated the process of vascular hypertrophy, fibrosis, and dysfunction in hypertensive rats and rat aortic adventitial fibroblasts. However, the exact roles and underlying mechanisms of miRNA-122-5p in myocardial fibroblasts remain largely unknown. In this work, neonatal rat cardiofibroblasts (CFs) were isolated and primarily cultured from the hearts of 2- to 3-d-old Sprague-Dawley rats. Stimulation of angiotensin II (Ang II) resulted in marked increases in cellular proliferation and migration and levels of collagen I, collagen III, CTGF, and TGF-β1 in cultured CFs. Furthermore, Ang II led to promoted expression of P62, Bax, and phosphorylated mTOR as well as downregulation of LC3II, beclin-1, and AMPK-phosphorylated levels, thereby contributing to imbalance of autophagy and apoptosis, and cellular injury in CFs, which were significantly ameliorated by treatment with miRNA-122-5p inhibitor. These changes were associated with decreased levels of collagen I, collagen III, CTGF, and TGF-β1. Furthermore, Ang II-induced loss of autophagy and promotion of apoptosis in CFs were prevented by the treatment with Pyr¹-apelin-13 or AMPK agonist AICAR or mTOR inhibitor rapamycin, respectively. In contrast, administration of miRNA-122-5p mimics and autophagy inhibitor 3-methylademine reversed beneficial roles of Pyr¹-apelin-13. Collectively, these data indicated that miRNA-122-5p is an essential regulator of autophagy and apoptosis in rat CFs via the apelin/AMPK/mTOR signaling pathway, which may be potentially used as a therapeutic target in myocardial fibrosis and related diseases.

Emerging landscape of cell-penetrating peptide-mediated nucleic acid delivery and their utility in imaging, gene-editing, and RNA-sequencing

The safety issues like immunogenicity and unacceptable cancer risk of viral vectors for DNA/mRNA vaccine delivery necessitate the development of non-viral vectors with no toxicity. Among the non-viral strategies, cell-penetrating peptides (CPPs) have been a topic of interest recently because of their ability to cross plasma membranes and facilitate nucleic acids delivery both in vivo and in vitro. In addition to the application in the field of gene vaccine and gene therapy, CPPs based nucleic acids delivery have been proved by its potential application like gene editing, RNA-sequencing, and imaging. Here, we focus on summarizing the recent applications and progress of CPPs-mediated nucleic acids delivery and discuss the current problems and solutions in this field.

Systematic review of microRNA biomarkers in acute coronary syndrome and stable coronary artery disease

The aim of this systematic review was to assess dysregulated miRNA biomarkers in coronary artery disease (CAD). Dysregulated microRNA (miRNAs) have been shown to be linked to cardiovascular pathologies including CAD and may have utility as diagnostic and prognostic biomarkers. We compared miRNAs identified in acute coronary syndrome (ACS) compared with stable CAD and control populations. We conducted a systematic search of controlled vocabulary and free text terms related to ACS, stable CAD and miRNA in Biosis Previews (OvidSP), The Cochrane Library (Wiley), Embase (OvidSP), Global Health (OvidSP), Medline (PubMed and OvidSP), Web of Science (Clarivate Analytics), and ClinicalTrials.gov which yielded 7370 articles. Of these, 140 original articles were appropriate for data extraction. The most frequently reported miRNAs in any CAD (miR-1, miR-133a, miR-208a/b, and miR-499) are expressed abundantly in the heart and play crucial roles in cardiac physiology. In studies comparing ACS cases with stable CAD patients, miR-21, miR-208a/b, miR-133a/b, miR-30 family, miR-19, and miR-20 were most frequently reported to be dysregulated in ACS. While a number of miRNAs feature consistently across studies in their expression in both ACS and stable CAD, when compared with controls, certain miRNAs were reported as biomarkers specifically in ACS (miR-499, miR-1, miR-133a/b, and miR-208a/b) and stable CAD (miR-215, miR-487a, and miR-502). Thus, miR-21, miR-133, and miR-499 appear to have the most potential as biomarkers to differentiate the diagnosis of ACS from stable CAD, especially miR-499 which showed a correlation between the level of their concentration gradient and myocardial damage. Although these miRNAs are potential diagnostic biomarkers, these findings should be interpreted with caution as the majority of studies conducted predefined candidate-driven assessments of a limited number of miRNAs (PROSPERO registration: CRD42017079744).

Circulating MicroRNAs Implicate Multiple Atherogenic Abnormalities in the Long-Term Cardiovascular Sequelae of Preeclampsia

BACKGROUND

Women who have had preeclampsia (PE) are at increased risk for premature cardiovascular disease (CVD). The underlying pathophysiology of this risk remains unclear, but potentially involves subclinical vascular damage or dysfunction. Alterations in the levels of circulating microRNAs may be implicated, as they are known to play pervasive roles in vascular biology. We investigated whether levels of circulating microRNAs are altered between women with premature acute coronary syndrome (ACS), with and without a history of PE.

METHODS

Women with premature ACS (age ≤ 55 years) were categorized based on a prior history of PE or normotensive pregnancy. Relative plasma levels of 372 microRNAs were initially assessed by polymerase chain reaction array in a subset of subjects (n = 12–13/group) matched for age, chronic hypertension, dyslipidemia, and smoking status. Candidate microRNAs were then validated in a larger cohort of ACS patients (n = 176).

RESULTS

MicroRNAs previously linked to angiogenesis (miR-126-3p), inflammation (miR-146a-5p), and cholesterol metabolism (miR-122-5p) were significantly decreased in women with prior PE compared to women with prior normotensive pregnancy (P = 0.002, 0.017, and 0.009, respectively), even after adjustment for chronic hypertension.

CONCLUSIONS

Circulating levels of miR-126-3p, -146a-5p, and -122-5p were significantly decreased in women with premature ACS who reported prior PE compared to those with prior normotensive pregnancy. These data provide novel insight into potential pathways that may contribute to the increased risk of CVD following PE.

Inducing Hepatitis C Virus Resistance After Pig Liver Transplantation-A Proof of Concept of Liver Graft Modification Using Warm Ex Vivo Perfusion

Normothermic ex vivo liver perfusion (NEVLP) offers the potential to optimize graft function prior to liver transplantation (LT). Hepatitis C virus (HCV) is dependent on the presence of miRNA(microRNA)-122. Miravirsen, a locked-nucleic acid oligonucleotide, sequesters miR-122 and inhibits HCV replication. The aim of this study was to assess the efficacy of delivering miravirsen during NEVLP to inhibit miR-122 function in a pig LT model. Pig livers were treated with miravirsen during NEVLP or cold storage (CS). Miravirsen absorption, miR-122 sequestration, and miR-122 target gene derepression were determined before and after LT. The effect of miravirsen treatment on HCV infection of hepatoma cells was also assessed. NEVLP improved miravirsen uptake versus CS. Significant miR-122 sequestration and miR-122 target gene derepression were seen with NEVLP but not with CS. In vitro data confirmed miravirsen suppression of HCV replication after established infection and prevented HCV infection with pretreatment of cells, analogous to the pretreatment of grafts in the transplant setting. In conclusion, miravirsen delivery during NEVLP is a potential strategy to prevent HCV reinfection after LT. This is the first large-animal study to provide "proof of concept" for using NEVLP to modify and optimize liver grafts for transplantation.

Ascending aortic adventitial remodeling and fibrosis are ameliorated with Apelin-13 in rats after TAC via suppression of the miRNA-122 and LGR4-β-catenin signaling

Apelin has been proved to be a critical mediator of vascular function and homeostasis. Here, we investigated roles of Apelin in aortic remodeling and fibrosis in rats with transverse aortic constriction (TAC). Male Sprague-Dawley rats were subjected to TAC and then randomized to daily deliver Apelin-13 (50μg/kg) or angiotensin type 1 receptor (AT1) blocker Irbesartan (50mg/kg) for 4 weeks. Pressure overload resulted in myocardial hypertrophy, systolic dysfunction, aortic remodeling and adventitial fibrosis with reduced levels of Apelin in ascending aortas of rat after TAC compared with sham-operated group. These changes were associated with marked increases in levels of miRNA-122, TGFβ1, CTGF, NFAT5, LGR4, and β-catenin. More importantly, Apelin and Irbesartan treatment strikingly prevented TAC-mediated aortic remodeling and adventitial fibrosis in pressure overloaded rats by blocking AT1 receptor and miRNA-122 levels and repressing activation of the CTGF-NFAT5 and LGR4-β-catenin signaling. In cultured primary rat adventitial fibroblasts, exposure to angiotensin II (100nmolL^-1) led to significant increases in cellular migration and levels of TGFβ1, CTGF, NFAT5, LGR4 and β-catenin, which were effectively reversed by pre-treatment with Apelin (100nmolL^-1) and miRNA-122 inhibitor (50nmolL^-1). In conclusion, Apelin counterregulated against TAC-mediated ascending aortic remodeling and angiotensin II-induced promotion of cellular migration by blocking AT1 receptor and miRNA-122 levels and preventing activation of the TGFβ1-CTGF-NFAT5 and LGR4-β-catenin signaling, ultimately contributing to attenuation of aortic adventitial fibrosis. Our data point to Apelin as an important regulator of aortic remodeling and adventitial fibrosis and a promising target for vasoprotective therapies.

HNF-4α regulated miR-122 contributes to development of gluconeogenesis and lipid metabolism disorders in Type 2 diabetic mice and in palmitate-treated HepG2 cells

Hepatocyte Nuclear Factor-4α (HNF-4α) is a key nuclear receptor protein required for liver development. miR-122 is a predominant microRNA expressed in liver and is involved in the regulation of cholesterol and fatty acid metabolism. HNF-4α is know to regulate expression of miR-122 in liver. We examined how HNF-4α regulated gluconeogenesis and lipid metabolism through miR-122 in vivo and in vitro. Expression of miR-122, HNF-4α, phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6Pase), sterol response elementary binding protein-1 (SREBP-1), fatty acid synthase-1 (FAS-1), carnitine palmitoyltransferase-1 (CPT-1) and acetyl Coenzyme A carboxylase alpha (ACCα) were determined in livers of Type 2 diabetic mice and in insulin resistant palmitate-treated HepG2 cells. CPT-1 and phosphorylated ACCα expression were significantly decreased in livers of Type 2 diabetic mice and in palmitate-treated HepG2 cells compared to controls. In contrast, expression of miR-122, HNF-4α, PEPCK, G6Pase, SREBP-1, FAS-1 and ACCα were significantly elevated in liver of Type 2 diabetic mice and in palmitate-treated HepG2 cells compared to controls. Expression of HNF-4α increased whereas siRNA knockdown of HNF-4α decreased miR-122 levels in HepG2 cells compared to controls. In addition, expression of HNF-4α in HepG2 cells increased PEPCK, G6Pase, SREBP-1, FAS-1, ACCα mRNA and protein expression and decreased CPT-1 and p-ACCα mRNA and protein expression compared to controls. Addition of miR-122 inhibitors attenuated the HNF-4α mediated effect on expression of these gluconeogenic and lipid metabolism proteins. The results indicate that HNF-4α regulated miR-122 contributes to development of the gluconeogenic and lipid metabolism alterations observed in Type 2 diabetic mice and in palmitate-treated HepG2 cells.

miR-122 Regulates LH Receptor Expression by Activating Sterol Response Element Binding Protein in Rat Ovaries

LH/human chorionic gonadotropin receptor (LHR) undergoes down-regulation during preovulatory LH surge or in response to exposure to a supraphysiological concentration of its ligands through a posttranscriptional mechanism involving an RNA binding protein designated as LHR mRNA binding protein (LRBP). miR-122, a short noncoding RNA, has been shown to mediate the up-regulation of LRBP. In the present study, we show that inhibition of miR-122 using a locked nucleic acid (LNA)-conjugated antagomir suppressed human chorionic gonadotropin (hCG)-induced up-regulation of LRBP as well as its association with LHR mRNA, as analyzed by RNA EMSA. Most importantly, inhibition of miR-122 resulted in the abolishment of hCG-mediated LHR mRNA down-regulation. We also show that the transcription factor, sterol regulatory element binding protein (SREBP) (SREBP-1a and SREBP-2 isoforms), is an intermediate in miR-122-mediated LHR mRNA regulation. HCG-stimulated increase in the activation of both SREBP-1a and SREBP-2 was inhibited by pretreatment with the miR-122 antagomir. The inhibition of cAMP/protein kinase A (PKA) and ERK pathways, upstream activators of miR-122, abolished SREBP activation after hCG treatment. SREBP-mediated regulation of LRBP expression is mediated by recruitment of LRBP promoter element to SREBP-1a, because chromatin immunoprecipitation assay revealed that association of LRBP promoter to SREBP was increased by hCG treatment. Pretreatment with miR-122 antagomir suppressed this response. Inhibition of SREBP activation by pretreating the rats with a chemical compound, fatostatin abrogated hCG-induced up-regulation of LRBP mRNA and protein. Fatostatin also inhibited LHR-LRBP mRNA-protein complex formation and LHR down-regulation. These results conclusively show that miR-122 plays a regulatory role in LH/hCG-induced LHR mRNA down-regulation by increasing LRBP expression through the activation of SREBP pathway.

A new model of reverse cholesterol transport: enTICEing strategies to stimulate intestinal cholesterol excretion

Cardiovascular disease (CVD) remains the largest cause of mortality in most developed countries. Although recent failed clinical trials and Mendelian randomization studies have called into question the high-density lipoprotein (HDL) hypothesis, it remains well accepted that stimulating the process of reverse cholesterol transport (RCT) can prevent or even regress atherosclerosis. The prevailing model for RCT is that cholesterol from the artery wall must be delivered to the liver where it is secreted into bile before leaving the body through fecal excretion. However, many studies have demonstrated that RCT can proceed through a non-biliary pathway known as transintestinal cholesterol excretion (TICE). The goal of this review is to discuss the current state of knowledge of the TICE pathway, with emphasis on points of therapeutic intervention.

Emerging role of microRNAs in lipid metabolism

microRNAs (miRNAs or miRs) are small non-coding RNAs that are involved in post-transcriptional regulation of their target genes in a sequence-specific manner. Emerging evidence demonstrates that miRNAs are critical regulators of lipid synthesis, fatty acid oxidation and lipoprotein formation and secretion. Dysregulation of miRNAs disrupts gene regulatory network, leading to metabolic syndrome and its related diseases. In this review, we introduced epigenetic and transcriptional regulation of miRNAs expression. We emphasized on several representative miRNAs that are functionally involved into lipid metabolism, including miR-33/33^⁎, miR122, miR27a/b, miR378/378^⁎, miR-34a and miR-21. Understanding the function of miRNAs in lipid homeostasis may provide potential therapeutic strategies for fatty liver disease.

Clinical significance of miRNA changes in chronic liver diseases

MicroRNAs (miRNAs) are small molecules that regulate gene expression at the post-transcriptional level. MiRNAs could exhibit specific changes in many liver diseases, which reflects pathologic changes of hepatic tissue. To better understand the relationship between miRNAs and liver diseases, this review summarizes the roles of miRNAs in hepatitis, alcohol-induced liver injury, drug-induced liver injury and hepatocellular carcinoma. Investigation of miRNA changes in humans might not only help to elucidate the mechanism of chronic hepatitis B virus infection, but also provide new molecular markers for clinical diagnosis and evaluation of the curative effect of antiviral treatment. In addition, it might provide new ideas and methods for the diagnosis and treatment of alcoholic liver disease, drug-induced liver injury, fatty liver disease and hepatocellular carcinoma.

Peptides used in the delivery of small noncoding RNA

RNA interference (RNAi) is an endogenous process in which small noncoding RNAs, including small interfering RNAs (siRNAs) and microRNAs (miRNAs), post-transcriptionally regulate gene expressions. In general, siRNA and miRNA/miRNA mimics are similar in nature and activity except their origin and specificity. Although both siRNAs and miRNAs have been extensively studied as novel therapeutics for a wide range of diseases, the large molecular weight, anionic surface charges, instability in blood circulation, and intracellular trafficking to the RISC after cellular uptake have hindered the translation of these RNAs from bench to clinic. As a result, a great variety of delivery systems have been investigated for safe and effective delivery of small noncoding RNAs. Among these systems, peptides, especially cationic peptides, have emerged as a promising type of carrier due to their inherent ability to condense negatively charged RNAs, ease of synthesis, controllable size, and tunable structure. In this review, we will focus on three major types of cationic peptides, including poly(l-lysine) (PLL), protamine, and cell penetrating peptides (CPP), as well as peptide targeting ligands that have been extensively used in RNA delivery. The delivery strategies, applications, and limitations of these cationic peptides in siRNA/miRNA delivery will be discussed.

Therapeutic potential of microRNA: a new target to treat intrahepatic portal hypertension?

Intrahepatic portal hypertension accounts for most of the morbidity and mortality encountered in patients with liver cirrhosis, due to increased portal inflow and intrahepatic vascular resistance. Most treatments have focused only on portal inflow or vascular resistance. However, miRNA multitarget regulation therapy may potentially intervene in these two processes for therapeutic benefit in cirrhosis and portal hypertension. This review presents an overview of the most recent knowledge of and future possibilities for the use of miRNA therapy. The benefits of this therapeutic modality--which is poorly applied in the clinical setting--are still uncertain. Increasing the knowledge and current understanding of the roles of miRNAs in the development of intrahepatic portal hypertension and hepatic stellate cells (HSCs) functions, as well as their potential as novel drug targets, is critical.