miR-21 promotes fibrosis in an acute cardiac allograft transplantation model

Transplant genetics and genomics

Ever since the discovery of the major histocompatibility complex, scientific and clinical understanding in the field of transplantation has been advanced through genetic and genomic studies. Candidate-gene approaches and recent genome-wide association studies (GWAS) have enabled a deeper understanding of the complex interplay of the donor-recipient interactions that lead to transplant tolerance or rejection. Genetic analysis in transplantation, when linked to demographic and clinical outcomes, has the potential to drive personalized medicine by enabling individualized risk stratification and immunosuppression through the identification of variants associated with immune-mediated complications, post-transplant disease or alterations in drug-metabolizing genes.

MicroRNA-98 inhibits TGF-β1-induced differentiation and collagen production of cardiac fibroblasts by targeting TGFBR1

To investigate the effects of miR-98 on TGF-β1-induced cardiac fibrosis in human cardiac fibroblasts (HCFs), and to establish the mechanism underlying these effects, HCFs were transfected with miR-98 inhibitor or mimic, and then treated with or without TGF-β1. The level of miR-98 was determined by qRT-PCR in TGF-β1-induced HCFs. Cell differentiation and collagen accumulation of HCFs were detected by qRT-PCR and Western blot assays, respectively. The mRNA and protein expressions of TGFBR1 were determined by qRT-PCR and Western blotting. In this study, the outcomes showed that TGF-β1 could dramatically decrease the level of miR-98 in a time- and concentration-dependent manner. Upregulation of miR-98 dramatically improved TGF-β1-induced increases in cell differentiation and collagen accumulation of HCFs. Moreover, bioinformatics analysis predicted that the TGFBR1 was a potential target gene of miR-98. Luciferase reporter assay demonstrated that miR-98 could directly target TGFBR1. Inhibition of TGFBR1 had the similar effect as miR-98 overexpression. Downregulation of TGFBR1 in HCFs transfected with miR-98 inhibitor partially reversed the protective effect of miR-98 overexpression on TGF-β1-induced cardiac fibrosis in HCFs. Upregulation of miR-98 ameliorates TGF-β1-induced differentiation and collagen accumulation of HCFs by downregulation of TGFBR1. These results provide further evidence for protective effect of miR-98 overexpression on TGF-β1-induced cardiac fibrosis.

Myocardial microRNAs associated with reverse remodeling in human heart failure

BACKGROUND

In dilated cardiomyopathies (DCMs) changes in expression of protein-coding genes are associated with reverse remodeling, and these changes can be regulated by microRNAs (miRs). We tested the general hypothesis that dynamic changes in myocardial miR expression are predictive of β-blocker-associated reverse remodeling.

METHODS

Forty-three idiopathic DCM patients (mean left ventricular ejection fraction 0.24 ± 0.09) were treated with β-blockers. Serial ventriculography and endomyocardial biopsies were performed at baseline, and after 3 and 12 months of treatment. Changes in RT-PCR (candidate miRs) or array-measured miRs were compared based on the presence (R) or absence (NR) of a reverse-remodeling response, and a miR-mRNA-function pathway analysis (PA) was performed.

RESULTS

At 3 months, 2 candidate miRs were selectively changed in Rs, decreases in miR-208a-3p and miR-591. PA revealed changes in miR-mRNA interactions predictive of decreased apoptosis and myocardial cell death. At 12 months, 5 miRs exhibited selective changes in Rs (decreases in miR-208a-3p, -208b-3p, 21-5p, and 199a-5p; increase in miR-1-3p). PA predicted decreases in apoptosis, cardiac myocyte cell death, hypertrophy, and heart failure, with increases in contractile and overall cardiac functions.

CONCLUSIONS

In DCMs, myocardial miRs predict the time-dependent reverse-remodeling response to β-blocker treatment, and likely regulate the expression of remodeling-associated miRs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01798992.

FUNDING

NIH 2R01 HL48013, 1R01 HL71118 (Bristow, PI); sponsored research agreements from Glaxo-SmithKline and AstraZeneca (Bristow, PI); NIH P20 HL101435 (Lowes, Port multi-PD/PI); sponsored research agreement from Miragen Therapeutics (Port, PI).

The Potential of MicroRNAs as Novel Biomarkers for Transplant Rejection

The control of gene expression by microRNAs (miRNAs, miR) influences many cellular functions, including cellular differentiation, cell proliferation, cell development, and functional regulation of the immune system. Recently, miRNAs have been detected in serum, plasma, and urine and circulating miR profiles have been associated with a variety of diseases. Rejection is one of the major causes of allograft failure and preventing and treating acute rejection are the central task for clinicians working with transplant patients. Invasive biopsies used in monitoring rejection are burdensome and risky to transplant patients. Novel and easily accessible biomarkers of acute rejection could make it possible to detect rejection earlier and make more fine-tuned calibration of immunosuppressive or new target treatment possible. In this review, we discuss whether circulating miRNA can serve as an early noninvasive diagnostic biomarker and an expression fingerprint of allograft rejection and transplant failure. Understanding the regulatory interplay of relevant miRNAs and the rejecting allograft will result in a better understanding of the molecular pathophysiology of alloimmune injury.

Exosomes Derived From Pancreatic Stellate Cells: MicroRNA Signature and Effects on Pancreatic Cancer Cells

OBJECTIVES

Pancreatic stellate cells (PSCs) interact with pancreatic cancer cells in the tumor microenvironment. Cell constituents including microRNAs may be exported from cells within membranous nanovesicles termed exosomes. Exosomes might play a pivotal role in intercellular communication. This study aimed to clarify the microRNA signature of PSC-derived exosomes and their effects on pancreatic cancer cells.

METHODS

Exosomes were prepared from the conditioned medium of immortalized human PSCs. MicroRNAs were prepared from the exosomes and their source PSCs, and the microRNA expression profiles were compared by microarray. The effects of PSC-derived exosomes on proliferation, migration, and the mRNA expression profiles were examined in pancreatic cancer cells.

RESULTS

Pancreatic stellate cell-derived exosomes contained a variety of microRNAs including miR-21-5p. Several microRNAs such as miR-451a were enriched in exosomes compared to their source PSCs. Pancreatic stellate cell-derived exosomes stimulated the proliferation, migration and expression of mRNAs for chemokine (C - X - C motif) ligands 1 and 2 in pancreatic cancer cells. The stimulation of proliferation, migration, and chemokine gene expression by the conditioned medium of PSCs was suppressed by GW4869, an exosome inhibitor.

CONCLUSIONS

We clarified the microRNA expression profile in PSC-derived exosomes. Pancreatic stellate cell-derived exosomes might play a role in the interactions between PSCs and pancreatic cancer cells.

Micro-RNA-21 (biomarker) and global longitudinal strain (functional marker) in detection of myocardial fibrotic burden in severe aortic valve stenosis: a pilot study

Aims

Myocardial fibrosis (MF) is a deleterious consequence of aortic valve stenosis (AVS). Global longitudinal strain (GLS) is a novel left ventricular (LV) functional parameter potentially useful to non-invasively estimate MF. MicroRNAs (miRNAs) are non-coding small ribonucleic acids (RNA) modulating genes function, mainly through RNA degradation. miRNA-21 is a biomarker associated with MF in pressure overload. The aim of the present study was to find an integrated algorithm for detection of MF using a combined approach with both bio- and functional markers.

Methods

Thirty-six patients (75.2 ± 8 y.o.; 63 % Female) with severe AVS and preserved LV ejection fraction (EF), candidate to surgical aortic valve replacement (sAVR) were enrolled. Clinical, bio-humoral evaluation (including plasmatic miRNA-21 collected using specific tubes, PAXgene, for stabilization of peripheral RNA) and a complete echocardiographic study, including GLS and septal strain, were performed before sAVR. Twenty-eight of those patients underwent sAVR and, in 23 of them, an inter-ventricular septum biopsy was performed. Tissues were fixed in formalin and embedded in paraffin. Sections were stained with Hematoxylin and Eosin for histological evaluation and with histochemical Masson trichrome for collagen fibers. The different components were calculated and expressed as micrometers². To evaluate tissue miRNA components, sections 2-μm thick were cut using a microtome blade for each slide. Regression analysis was performed to test association between dependent variable and various predictors included in the model.

Results

Despite a preserved EF (66 ± 11 %), patients presented altered myocardial deformation parameters (GLS −14,02 ± 3.8 %; septal longitudinal strain, SSL −9.63 ± 2.9 %; septal longitudinal strain rate, SL-Sr −0.58 ± 0.17 1/s; Septal Longitudinal early-diastolic strain rate, SL-SrE 0.62 ± 0.32 1/s). The extent of MF showed an inverse association with both GLS and septal longitudinal deformation indices (GLS: R² = 0.30; p = 0.02; SSL: R² = 0.36; p = 0.01; SL-Sr: R² = 0.39; p < 0.001; SL-SrE: R² = 0.35; p = 0.001). miRNA-21 was mainly expressed in fibrous tissue (p < 0.0001). A significant association between MF and plasmatic miRNA-21, alone and weighted for measures of structural (LVMi R² = 0.50; p = 0.0005) and functional (SSL R² = 0.35; p = 0.006) remodeling, was found.

Conclusions

In AVS, MF is associated with alterations of regional and global strain. Plasmatic miRNA-21 is directly related to MF and associated with LV structural and functional impairment.

Endomyocardial miR-133a levels correlate with myocardial inflammation, improved left ventricular function, and clinical outcome in patients with inflammatory cardiomyopathy

AIMS

Inflammatory heart disease represents an important cause of chronic dilated cardiomyopathy (DCM). Predicting the clinical course of patients with inflammatory cardiomyopathy (iCMP) is difficult, and the prognostic value of current biological markers remains controversial. We tested whether expression of selected microRNAs in endomyocardial biopsies (EMBs) is related to LV functional recovery and clinical events in iCMP patients.

METHODS AND RESULTS

EMBs were obtained from patients with iCMP (n = 76) and non-inflammatory DCM (n = 22). A set of six microRNAs implicated in inflammation (miR-155 and miR-146b), heart failure (miR-21 and miR-133a), and endothelial cell (miR-126) and skeletal muscle function (miR-206) was pre-defined. Endomyocardial expression of miR-155 and miR-133a, as quantified by reverse transcription-PCR (RT-PCR), was up-regulated in patients with iCMP as compared with patients with DCM. Levels of miR-133a (R = 0.73, P < 0.01) and miR-155 (R = 0.63, P < 0.01) correlated with inflammatory cell count on EMBs from patients with iCMP. Patients with iCMP and preserved LV function at study entry demonstrated higher expression of miR-133a than patients with reduced LV function. Also, increased expression of miR-133a was associated with less fibrosis and myocyte necrosis on EMB, and LV functional recovery during a mean follow-up of 3.1 years. Importantly, patients with iCMP and miR-133a levels in the upper tertile showed longer survival free of death, malignant arrhythmias, and hospitalizations for heart failure.

CONCLUSION

The present study demonstrates that miR-133a levels correlate with macrophage infiltration, cardiac injury, improved LV function, and clinical outcome in patients with iCMP. miR-133a may serve as a potential novel biomarker and therapeutic target in human iCMP.