miR-155 Knockout Research Articles

Exploring miR-21 Knock-Out Using CRISPR/Cas as a Treatment for Lung Cancer

Background: Lung cancer is a leading cause of cancer-related deaths worldwide. Its high incidence and poor prognosis demonstrate the need to investigate new therapies. The PI3K/AKT pathway is activated in carcinogenic processes such as invasion, proliferation, and drug resistance. MiR-21 is a microRNA overexpressed in numerous types of cancer and which activates PI3K/AKT pathway by down-regulating its main targets, PTEN and PDCD4. CRISPR is a revolutionary gene-editing technology that allows genes to be deleted. The aim of this study was to use CRISPR/Cas9 technology as an option to reduce carcinogenic and drug resistance processes by eliminating miR-21. Methods: CRISPR/Cas9 was used to knock out miR-21 (miR-21 KO) in A549 lung cancer cells and thus reverse the carcinogenic processes activated by miR-21 overexpression. Furthermore, the effect of miR-21 KO on drug resistance was studied, choosing the main chemotherapeutic agents used for the treatment of lung cancer: gemcitabine, carboplatin, paclitaxel, and oxaliplatin. Results: miR-21 KO A549 cells exhibited a reduction in proliferation, migration, and colony formation compared to A549 cells. In contrast, the expression of PTEN and PDCD4 increased in miR-21 KO A549 cells. Furthermore, miR-21 KO A549 cells showed a decrease in the IC50 of the drugs used for the treatment of lung cancer: gemcitabine, carboplatin, paclitaxel, and oxaliplatin. Conclusions: Based on these results, miR-21 knock-out using CRISPR/Cas could be a promising strategy for the treatment of lung cancer.

The Role of miR-155 in Modulating Gene Expression in CD4+ T Cells: Insights into Alternative Immune Pathways in Autoimmune Encephalomyelitis.

CD4+ T cells are considered the main orchestrators of autoimmune diseases. Their disruptive effect on CD4+ T cell differentiation and the imbalance between T helper cell populations can be most accurately determined using experimental autoimmune encephalomyelitis (EAE) as an animal model of multiple sclerosis (MS). One epigenetic factor known to promote autoimmune inflammation is miRNA-155 (miR-155), which is significantly upregulated in inflammatory T cells. The aim of the present study was to profile the transcriptome of immunized mice and determine their gene expression levels based on mRNA and miRNA sequencing. No statistically significant differences in miRNA profile were observed; however, substantial changes in gene expression between miRNA-155 knockout (KO) mice and WT were noted. In miR-155 KO mice, mRNA expression in CD4+ T cells changed in response to immunization with the myeloid antigen MOG35-55. After restimulation with MOG35-55, increased Ffar1 (free fatty acid receptor 1) and Scg2 (secretogranin-2) expression were noted in the CD4+ T cells of miR-155-deficient mice; this is an example of an alternative response to antigen stimulation.

Regulation of cardiac allograft immune responses by microRNA-155

IntroductionA better understanding of the immune mechanisms involved in allograft rejection after transplantation is urgently needed to improve patient outcomes. As microRNA-155 (miR155) plays a critical role in inflammation, we postulated that a deficiency of miR155 will improve cardiac allograft survival and enhance tolerance induction after heart transplantation. MethodsWe developed an acute rejection mouse model through heterotopic BALB/c cardiac transplantation to C57BL/6 (wild-type) and C57BL/6 miR155 knock-out (miR155KO) mice. Further, we induced tolerance in both groups through a costimulatory blockade with CTLA4-Ig (200 μg; post-transplant day 2) and MRI antibodies (250 μg; post-transplant day 0), targeting CD28/B7 and CD40/CD154 signals, respectively. Finally, we examined the effects of injecting 100 μg of small extracellular vesicles (sEVs) isolated from wild-type mice undergoing rejection into tolerant miR155KO mice. ResultsMean survival time (MST) of the cardiac allografts in wild-type and miR155KO mice was 7 and 15 days, respectively (p < 0.0001). Costimulatory blockade increased MST to 65 days and > 100 days in the wild-type and miR155KO recipients, respectively (p < 0.001). Injection of sEVs isolated from wild-type mice undergoing rejection into tolerant miR155KO mice decreased the allograft survival to 9 days, significantly lower than the tolerant miR155KO mice without injection of sEVs (>100 days; p < 0.0001). ConclusionmiR155KO mice have improved cardiac allograft survival and enhanced induction of tolerance after heterotopic cardiac transplantation. Injection of sEVs from wild-type mice undergoing rejection into the miR155KO mice reversed these benefits.

MicroRNA-21 modulates brown adipose tissue adipogenesis and thermogenesis in a mouse model of polycystic ovary syndrome

BackgroundPolycystic ovary syndrome (PCOS), the most common endocrine disorder in premenopausal women, is associated with increased obesity, hyperandrogenism, and altered brown adipose tissue (BAT) thermogenesis. MicroRNAs play critical functions in brown adipocyte differentiation and maintenance. We aim to study the role of microRNA-21 (miR-21) in altered energy homeostasis and BAT thermogenesis in a PCOS mouse model of peripubertal androgen exposure.MethodsThree-week-old miR-21 knockout (miR21KO) or wild-type (WT) female mice were treated with dihydrotestosterone (DHT) or vehicle for 90 days. Body composition was determined by EchoMRI. Energy expenditure (EE), oxygen consumption (VO2), carbon dioxide production (VCO2), and respiratory exchange ratio (RER) were measured by indirect calorimetry. Androgen receptor (AR), and markers of adipogenesis, de novo lipogenesis, angiogenesis, extracellular matrix remodeling, and thermogenesis were quantified by RT-qPCR and/or Western-blot.ResultsMiR-21 ablation attenuated DHT-mediated increase in body weight while having no effect on fat or BAT mass. MiR-21 ablation attenuated DHT-mediated BAT AR upregulation. MiR-21 ablation did not alter EE; however, miR21KO DHT-treated mice have reduced VO2, VCO2, and RER. MiR-21 ablation reversed DHT-mediated decrease in food intake and increase in sleep time. MiR-21 ablation decreased some adipogenesis (Adipoq, Pparγ, and Cebpβ) and extracellular matrix remodeling (Mmp-9 and Timp-1) markers expression in DHT-treated mice. MiR-21 ablation abolished DHT-mediated increases in thermogenesis markers Cpt1a and Cpt1b, while decreasing CIDE-A expression.ConclusionsOur findings suggest that BAT miR-21 may play a role in regulating DHT-mediated thermogenic dysfunction in PCOS. Modulation of BAT miR-21 levels could be a novel therapeutic approach for the treatment of PCOS-associated metabolic derangements.

Macrophage-derived exosomes promote telomere fragility and senescence in tubular epithelial cells by delivering miR-155

BackgroundChronic kidney disease (CKD) is highly prevalent worldwide, and its global burden is substantial and growing. CKD displays a number of features of accelerated senescence. Tubular cell senescence is a common biological process that contributes to CKD progression. Tubulointerstitial inflammation is a driver of tubular cell senescence and a common characteristic of CKD. However, the mechanism by which the interstitial inflammation drives tubular cell senescence remains unclear. This paper aims to explore the role of exosomal miRNAs derived from macrophages in the development of tubular cell senescence.MethodsAmong the identified inflammation-related miRNAs, miR-155 is considered to be one of the most important miRNAs involved in the inflammatory response. Macrophages, the primary immune cells that mediate inflammatory processes, contain a high abundance of miR-155 in their released exosomes. We assessed the potential role of miR-155 in tubular cell senescence and renal fibrosis. We subjected miR-155−/− mice and wild-type controls, as well as tubular epithelial cells (TECs), to angiotensin II (AngII)-induced kidney injury. We assessed kidney function and injury using standard techniques. TECs were evaluated for cell senescence and telomere dysfunction in vivo and in vitro. Telomeres were measured by the fluorescence in situ hybridization.ResultsCompared with normal controls, miR-155 was up-regulated in proximal renal tubule cells in CKD patients and mouse models of CKD. Moreover, the expression of miR-155 was positively correlated with the extent of renal fibrosis, eGFR decline and p16INK4A expression. The overexpression of miR-155 exacerbated tubular senescence, evidenced by increased detection of p16INK4A/p21expression and senescence-associated β-galactosidase activity. Notably, miR-155 knockout attenuates renal fibrosis and tubule cell senescence in vivo. Interestingly, once released, macrophages-derived exosomal miR-155 was internalized by TECs, leading to telomere shortening and dysfunction through targeting TRF1. A dual-luciferase reporter assay confirmed that TRF1 was the direct target of miR-155. Thus, our study clearly demonstrates that exosomal miR-155 may mediate communication between macrophages and TECs, subsequently inducing telomere dysfunction and senescence in TECs.ConclusionsOur work suggests a new mechanism by which macrophage exosomes are involved in the development of tubule senescence and renal fibrosis, in part by delivering miR-155 to target TRF1 to promote telomere dysfunction. Our study may provide novel strategies for the treatment of AngII-induced kidney injury.

MiR-21-Mediated Endothelial Senescence and Dysfunction Are Involved in Cigarette Smoke-Induced Pulmonary Hypertension through Activation of PI3K/AKT/mTOR Signaling.

Smoking is a pathogenic factor for pulmonary hypertension (PH). Our previous study showed that serum miR-21 levels are elevated in smokers. miR-21 is considered as engaged in the PH process; however, its mechanisms remain unclear. In this investigation, we found that in the lung tissue of smoking-induced PH patients, the levels of miR-21 and aging markers (p21 and p16) were upregulated, and the function of pulmonary vascular endothelial cells was also impaired. Exposure of mice to cigarette smoke (CS) for four months caused similar changes in lung tissues and increased pulmonary arterial pressure, which were attenuated by knockout of miR-21. Further, human umbilical vein endothelial cells (HUVECs) exposed to cigarette smoke extract (CSE) revealed upregulation of miR-21 levels, depression of PTEN, activation of PI3K/AKT/mTOR signaling, an increase in senescence indexes, and enhanced dysfunction. Inhibiting miR-21 overexpression reversed the PTEN-mTOR signaling pathway and prevented senescence and dysfunction of HUVECs. In sum, our data indicate that miR-21-mediated endothelial senescence and dysfunction are involved in CS-induced PH through the activation of PI3K/AKT/mTOR signaling, which suggests that selective miR-21 inhibition offers the potential to attenuate PH.

The Regulatory Role of microRNA-21 in Coronary Microcirculation in Metabolic Syndrome

Coronary vasculature is essential to supply oxygen and nutrients to the heart and maintain normal cardiac function. Obstruction of large vessels of coronaries (atherosclerosis) is well studied, but coronary microvascular dysfunction (CMD), which is associated with diabetic cardiomyopathy, Takotsubo cardiomyopathy, Ischemia with the non-obstructive coronary artery (INOCA), and HFpEF, is understudied. CMD is characterized by impaired endothelial-dependent vasodilation, but detailed mechanisms have yet to be elucidated. The anti-fibrotic role of microRNA-21 (miR-21) is reported in the HFrEF induced by ischemia/reperfusion or pressure overload, but how miR-21 regulates CMD is not entirely understood. Our recent study shows miR-21 ablation ameliorated impaired vasodilation in isolated coronaries of mice fed on high fat and high sugar (HFHS) diet. In this study, we examined the coronary flow reserve (CFR), the relationship between myocardial blood flow (MBF) and cardiac work (doppler) under hyperemia, cardiac function (echocardiography and exercise exertion test), fibrosis and gene expression of miR-21 knockout and wild-type (WT) mice fed on chow or HFHS diet. Our preliminary data show that MBF and CFR were decreased, cardiac index, stroke volume, and running distance were reduced, and the E/E’ ratio was increased in WT mice fed on the HFHS diet compared to the WT mice fed on the chow diet. The perivascular fibrosis was increased in the WT mice fed on the HFHS diet compared to WT mice on the chow diet. The ablation of miR-21 reversed all these changes in the mice treated with HFHS, suggesting miR-21 deficiency ameliorated CMD in metabolic syndrome. Moreover, we used endothelial-specific miR-21 knockout to study the endothelial miR-21 function. Interestingly, the endothelial mi-R21 KO phenocopied the global knockouts, suggesting the benefit of miR-21 deficiency to coronary microvascular function in metabolic syndrome is from endothelial cells. The study provides the potential therapeutic strategy to target vascular endothelial cells with miR-21 antagomir for CMD in metabolic syndromes. AHA 970663,1R56HL165207,1 R01 HL165207-01A1 to LY and 1 F31 HL156726-01A1 to CJ. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cardiorenal Effects of Chronic High Phosphate Diet in Female Rats

Cardiorenal Syndrome Type 4 (CRS4) refers to the development of cardiovascular dysfunction as a result of chronic kidney disease. The accumulation of circulating phosphate in the later stages of chronic kidney disease (CKD) has been positively associated with cardiac hypertrophy and dysfunction. In our previous work, we found that male Sprague Dawley rats that underwent 5/6 nephrectomy (5/6Nx) to induce CKD phenotypes also developed cardiac pathology when serum phosphorus levels became elevated. Small RNA sequencing of left ventricle tissue revealed upregulated microRNA-21-5p and -3p expression in 5/6Nx rats, when compared to sham-operated controls, and suppression of miR-21-5p attenuated left ventricle pathology in male 5/6Nx rats. We hypothesize that hyperphosphatemia, independent of CKD, can impair cardiac function and that miR-21 may mediate these effects. It has been recently reported that females exhibit higher urinary phosphate excretion in response to high dietary phosphate intake than males. In this study, hyperphosphatemia was induced by placing 9-week old female wild-type (WT) Sprague Dawley and global miR-21 knockout (miR-21−/−; lacking both miR-21-5p and -3p rats) (n=4-9/group) on either high phosphate (2% Pi) or control diet (0.6% Pi) for 8 weeks. Echocardiography and renal ultrasound were performed under anesthesia to assess cardiac function and renal cross-sectional area, respectively, prior to tissue collection at endpoint. Rats of either genotype fed 2% Pi diet exhibited increased left kidney weight, left kidney/body weight, and left kidney cross-sectional area (2-way ANOVA, main effect of diet; p&lt;0.05). In animals fed 2% Pi, miR-21−/− rats had significantly higher left ventricle fractional shortening than WT rats (57.06 ± 3.32 vs. 43.96 ± 1.34; 2-way ANOVA with Tukey multiple comparisons; p&lt;0.05). This study allowed the cardiovascular effects of chronically elevated phosphate to be isolated from other uremic toxins elevated in CKD. We find that loss of miR-21 augments cardiac function, supporting a role for miR-21 in mediating phosphate-related pathology. Ongoing studies are focused on identifying specific molecular mechanisms driving these changes. This study was supported by T32HL007852 and R01HL128332. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Correlation of miR-155 Expression with Drug Sensitivity of FLT3-ITD+ Acute Myeloid Leukemia Cell Line and Its Mechanism

To investigate the correlation of miR-155 expression with drug sensitivity of FLT3-ITD+ acute myeloid leukemia (AML) cell line and its potential regulatory mechanism. By knocking out miR-155 gene in FLT3-ITD+ AML cell line MV411 through CRISPR/Cas9 gene-editing technology, monoclonal cells were screened. The genotype of these monoclonal cells was validated by PCR and Sanger sequencing. The expression of mature miRNA was measured by RT-qPCR. The treatment response of doxorubicin, quizartinib and midostaurin were measured by MTT assay and IC50 of these drugs were calculated to identify the sensitivity. Transcriptome sequencing was used to analyze change of mRNA level in MV411 cells after miR-155 knockout, gene set enrichment analysis to analyze change of signaling pathway, and Western blot to verify expressions of key molecules in signaling pathway. Four heterozygotes with gene knockout and one heterozygote with gene insertion were obtained through PCR screening and Sanger sequencing. RT-qPCR results showed that the expression of mature miR-155 in the monoclonal cells was significantly lower than wild-type clones. MTT results showed that the sensitivity of MV411 cells to various anti FLT3-ITD+ AML drugs increased significantly after miR-155 knockout compared with wild-type clones. RNA sequencing showed that the mTOR signaling pathway and Wnt signaling pathway were inhibited after miR-155 knockout. Western blot showed that the expressions of key molecules p-mTOR, Wnt5α and β-catenin in signaling pathway were down-regulated. Drug sensitivity of MV411 cells to doxorubicin, quizartinib and midostaurin can be enhanced significantly after miR-155 knockout, which is related to the inhibition of multiple signaling pathways including mTOR and Wnt signaling pathways.

Abstract 5689: miR-21: A therapeutic target that delays severe liver disease and hepatocellular carcinoma under high-fat-diet conditions

Abstract Liver disease is a major global health concern, claiming approximately 2 million lives worldwide annually, yet curative treatments remain elusive. In our study, we aimed to investigate the role of microRNA-21-5p (miR-21) in metabolic dysfunction-associated steatotic liver disease (previously NAFLD), metabolic-associated steatohepatitis (previously NASH), and hepatocellular carcinoma (HCC) within the context of a Western high-fat diet (HFD) and offering potential therapeutic insights. We found that reduced miR-21 levels correlated with liver disease progression in WT mice fed on HFD, while miR-21 knockout mice showed exacerbated metabolic dysfunction, including obesity, hepatomegaly, hyperglycemia, insulin resistance, steatosis, fibrosis, and HCC. Our study reveals that miR-21 plays a protective role in metabolic syndrome and in the progression of liver disease to cancer. miR-21 directly targets Transforming growth factor beta-induced (Tgfbi), a gene also known to be significantly upregulated and a potential oncogene in HCC. Further, our study showed that intervention with the administration of a miR-21 mimic in WT livers in HFD conditions effectively improves insulin sensitivity, steatosis, fibrosis, tumor burden, as well as Tgfbi expression. These findings indicate that miR-21 could serve as an effective strategy to delay or prevent liver disease in high-fat-diet environments. Citation Format: Urmila Jagtap, Anan Quan, Yuho Ono, Jonathan Lee, Kylie A. Shen, Sergei Manakov, Gyongyi Szabo, Imad Nasser, Frank J. Slack. miR-21: A therapeutic target that delays severe liver disease and hepatocellular carcinoma under high-fat-diet conditions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5689.

MicroRNA-150 Deletion Reduces the Occurrence and Severity of Rheumatoid Arthritis by Inhibiting IL-17.

Understanding the effects of epigenetic factors on the pathogenesis of rheumatoid arthritis (RA) is important for the early diagnosis and therapeutic intervention of this disease. MicroRNA-150 (miR-150) exerts an important influence on the development and function of lymphocytes. However, the role of miR-150 in the pathogenesis of RA remains unclear. To explore the role of miR-150 in the pathogenesis of RA and the related immune mechanism. In this study, we used miR-150 knock-out (miR-150KO) and created animal models of RA. Flow cytometry, immunohistochemistry, and real-time RT-PCR were employed to assess the frequency of T cell subsets and cytokines expression. Compared to wild-type (WT) mice, the onset of RA was postponed and the incidence of RA was reduced in miR-150KO mice. The expression of IL-4 and IFN-γ significantly increased while the expression of IL-17 decreased significantly in NKT and CD4+ T cells of KO mice compared to that of WT mice after RA induction. In addition, the expression of IL-4 and IFN-γ increased while the expression of IL-17 decreased significantly in the joint tissues of KO mice compared to that of WT mice. Furthermore, the mRNA expression of TNF-α and IL-17 decreased significantly in the synovial fluid cells of KO mice compared to that of the WT mice after RA induction. MiR-150 deficiency decreases the expression of IL-17 in T cells and joint tissues, and alleviates the occurrence and progression of RA in mice.

Antiviral therapy reduces hepatocellular carcinoma through suppressing hepatitis B virus replication may improve ER stress, mitochondrial and metabolic dysfunctions and decrease p62 in hybridized mice with single HBV transgene and miR-122.

Hepatitis B virus (HBV) hijacks autophagy for its replication. Nucleos(t)ide analogs (NUCs) treatment suppressed HBV replication and reduced hepatocellular carcinoma (HCC) incidence. However, the use of NUCs in chronic hepatitis B (CHB) patients with normal or minimally elevated serum alanine aminotransferase (ALT) levels is still debated. Animal models are crucial for studying the unanswered issue and evaluating new therapies. MicroRNA-122 (miR-122), which regulates fatty acid and cholesterol metabolism, is downregulated during hepatitis and HCC progression. The reciprocal inhibition of miR-122 with HBV highlights its role in HCC development as a tumor suppressor. By crossbreeding HBV-transgenic mice with miR-122 knockout mice, we generated a hybrid mouse model with a high incidence of HCC up to 89% and normal ALT levels before HCC. The model exhibited early-onset hepatic steatosis, progressive liver fibrosis, and impaired late-phase autophagy. Metabolomics and microarray analysis identified metabolic signatures, including dysregulation of lipid metabolism, inflammation, genomic instability, the Warburg effect, reduced TCA cycle flux, energy deficiency, and impaired free radical scavenging. Antiviral treatment reduced HCC incidence in hybrid mice by approximately 30-35% compared to untreated mice. This effect was linked to the activation of ER stress-responsive transcription factor ATF4, clearance of autophagosome cargo p62, and suppression of the CHOP-mediated apoptosis pathway. In summary, this study suggests that despite minimal ALT elevation, HBV replication can lead to liver injury. Endoplasmic reticulum stress, reduced miR-122 levels, mitochondrial and metabolic dysfunctions, blocking protective autophagy resulting in p62 accumulation, apoptosis, fibrosis, and HCC. Antiviral may improve the above-mentioned pathogenesis through HBV suppression.

MiR-223-3p Prevents Necroptotic Macrophage Death by Targeting Ripk3 in a Negative Feedback Loop and Consequently Ameliorates Advanced Atherosclerosis.

The formation of large necrotic cores results in vulnerable atherosclerotic plaques, which can lead to severe cardiovascular diseases. However, the specific regulatory mechanisms underlying the development of necrotic cores remain unclear. To evaluate how the modes of lesional cell death are reprogrammed during the development of atherosclerosis, the expression levels of key proteins that are involved in the necroptotic, apoptotic, and pyroptotic pathways were compared between different stages of plaques in humans and mice. Luciferase assays and loss-of-function studies were performed to identify the microRNA-mediated regulatory mechanism that protects foamy macrophages from necroptotic cell death. The role of this mechanism in atherosclerosis was determined by using a knockout mouse model with perivascular drug administration and tail vein injection of microRNA inhibitors in Apoe-/- mice. Here, we demonstrate that the necroptotic, rather than the apoptotic or pyroptotic, pathway is more activated in advanced unstable plaques compared with stable plaques in both humans and mice, which closely correlates with necrotic core formation. The upregulated expression of Ripk3 (receptor-interacting protein kinase 3) promotes the C/EBPβ (CCAAT/enhancer binding protein beta)-dependent transcription of the microRNA miR-223-3p, which conversely inhibits Ripk3 expression and forms a negative feedback loop to regulate the necroptosis of foamy macrophages. The knockout of the Mir223 gene in bone marrow cells accelerates atherosclerosis in Apoe-/- mice, but this effect can be rescued by Ripk3 deficiency or treatment with the necroptosis inhibitors necrostatin-1 and GSK-872. Like the Mir223 knockout, treating Apoe-/- mice with miR-223-3p inhibitors increases atherosclerosis. Our study suggests that miR-223-3p expression in macrophages protects against atherosclerotic plaque rupture by limiting the formation of necrotic cores, thus providing a potential microRNA therapeutic candidate for atherosclerosis.

Abstract 15626: Novel Function Annotation Tool Revealed Obesity-Induced Inflammation is Exacerbated by miR-150 Regulated B Cell Receptor Signaling

B cells exacerbate obesity-induced metabolic dysfunction and become the second most abundant immune lineage in obese adipose tissue. However, high-resolution strategies to interrogate cellular dynamics driving B cell responses under chronic obesity stress are lacking, stifling innovative B cell-targeted therapies against obesity-induced health&amp;nbsp;risk. Our previous work established the potent role of&amp;nbsp;miR-150 in adipose tissue&amp;nbsp;B cells’ (ATB) pro-inflammatory responses under obesity. This project aims to elucidate the mechanism of miR-150 regulated ATB actions that bolster obesity-induced inflammation. Method: We employed single-cell techniques to decipher obesity-perturbed signaling networks in B cell-specific miR-150 gain/loss of function mouse models&amp;nbsp; in vivo and&amp;nbsp; ex vivo . We utilized our novel B cell function annotation tool, B-RAY, to&amp;nbsp;quantify&amp;nbsp;B cell cytokine production, antibody secretion, and antigen presentation from single-cell RNA-Seq. These strengths permitted several key findings: Result: A) miR-150 overexpression in mature B cells alone improved systemic glucose tolerance in obesity, despite similar body adiposity. In line, miR-150 knock-out worsened glucose tolerance. B) In obese adipose tissue, B cells were skewed towards higher cytokine production and antigen presentation and away from antibody secretion compared to lean tissue. Importantly, ATBs in obesity displayed increased activity of miR-150 direct targets, Myb, Etf1, and Elk1, and reduced expression of miR-150. C) ATBs in obesity were enriched in B cell receptor (BCR) signaling and downstream cascades. miR-150 overexpression B cells exhibited reduced BCR-mediated Syk phosphorylation and calcium influx, while miR-150 knock-out yielded enhanced responses. Conclusion: These results support the hypothesis that miR-150 regulation of ATBs limits chronic inflammation in obese adipose tissue via modulating BCR signaling to prevent excessive B cell cytokine production and antigen presentation. Future work will investigate ATB actions and BCR activation in&amp;nbsp;miR-150 gain/loss of function mice&amp;nbsp;across time in diet-induced obesity. Collectively, this work will elucidate an important immunoregulatory network bolstering obesity-induced inflammation and health risk.

Abstract P2099: Small Proline-rich Protein 1a Is A Key Downstream Effector Of Microrna-150 During Both Maladaptive Cardiac Remodeling In Mice And Human Cardiac Fibroblast Activation

Background &amp; Objectives: MicroRNA-150 (miR-150) is conserved between rodents and humans, is significantly downregulated during heart failure (HF), and correlates with patient outcomes. We reported that miR-150 is protective during myocardial infarction (MI) in part by decreasing cardiomyocyte (CM) apoptosis and that proapoptotic small proline-rich protein 1a ( Sprr1a ) is a direct CM target of miR-150. We also showed that Sprr1a knockdown in mice improves cardiac dysfunction and fibrosis post-MI and that Sprr1a is upregulated in pathological mouse cardiac fibroblasts (CFs) from ischemic myocardium. However, the direct functional relationship between miR-150 and SPRR1A during both post-MI remodeling in mice and human CF (HCF) activation was not established. Methods &amp; Results: Here, using a novel miR-150 knockout (KO); Sprr1a -hypomorphic ( Sprr1a hypo/hypo ) mouse model, we demonstrate that Sprr1a knockdown blunts adverse post-MI effects caused by miR-150 loss. MiR-150 KO; Sprr1a hypo/hypo mice also exhibit decreased profibrotic markers in the infarct areas of hearts as compared to miR-150 KO mice. Moreover, primary adult HCF studies reveal that SPRR1A is upregulated in hypoxia/reoxygenation-treated HCFs and is downregulated in HCFs exposed to the cardioprotective β-blocker carvedilol, which is inversely associated with miR-150 expression. Significantly, we show that the protective roles of miR-150 in HCFs are directly mediated by functional repression of profibrotic SPRR1A (See Figure). Conclusions: These findings delineate a pivotal functional interaction between miR-150 and SPRR1A as a novel regulatory mechanism pertinent to CF activation and ischemic HF.

SPRR1A is a key downstream effector of MiR-150 during both maladaptive cardiac remodeling in mice and human cardiac fibroblast activation

MicroRNA-150 (miR-150) is conserved between rodents and humans, is significantly downregulated during heart failure (HF), and correlates with patient outcomes. We previously reported that miR-150 is protective during myocardial infarction (MI) in part by decreasing cardiomyocyte (CM) apoptosis and that proapoptotic small proline-rich protein 1a (Sprr1a) is a direct CM target of miR-150. We also showed that Sprr1a knockdown in mice improves cardiac dysfunction and fibrosis post-MI and that Sprr1a is upregulated in pathological mouse cardiac fibroblasts (CFs) from ischemic myocardium. However, the direct functional relationship between miR-150 and SPRR1A during both post-MI remodeling in mice and human CF (HCF) activation was not established. Here, using a novel miR-150 knockout;Sprr1a-hypomorphic (Sprr1ahypo/hypo) mouse model, we demonstrate that Sprr1a knockdown blunts adverse post-MI effects caused by miR-150 loss. Moreover, HCF studies reveal that SPRR1A is upregulated in hypoxia/reoxygenation-treated HCFs and is downregulated in HCFs exposed to the cardioprotective β-blocker carvedilol, which is inversely associated with miR-150 expression. Significantly, we show that the protective roles of miR-150 in HCFs are directly mediated by functional repression of profibrotic SPRR1A. These findings delineate a pivotal functional interaction between miR-150 and SPRR1A as a novel regulatory mechanism pertinent to CF activation and ischemic HF.

Therapeutic inhibition of miR-155 attenuates liver fibrosis via STAT3 signaling

Most chronic liver diseases progress to liver fibrosis, which, when left untreated, can lead to cirrhosis and hepatocellular carcinoma. MicroRNA (miRNA)-targeted therapeutics have become attractive approaches to treat diseases. In this study, we investigated the therapeutic effect of miR-155 inhibition in the bile duct ligation (BDL) mouse model of liver fibrosis and evaluated the role of miR-155 in chronic liver fibrosis using miR-155-deficient (miR-155 knockout [KO]) mice. We found increased hepatic miR-155 expression in patients with cirrhosis and in the BDL- and CCl4-induced mouse models of liver fibrosis. Liver fibrosis was significantly reduced in miR-155 KO mice after CCl4 administration or BDL. To assess the therapeutic potential of miR-155 inhibition, we administered an rAAV8-anti-miR-155 tough decoy invivo that significantly reduced liver damage and fibrosis in BDL. BDL-induced protein levels of transforming growth factor β (TGF-β), p-SMAD2/3, and p-STAT3 were attenuated in anti-miR-155-treated compared with control mice. Hepatic stellate cells from miR-155 KO mice showed attenuation in activation and mesenchymal marker expression. Invitro, miR-155 gain- and loss-of-function studies revealed that miR-155 regulates activation of stellate cells partly via STAT3 signaling. Our study suggests that miR-155 is the key regulator of liver fibrosis and might be a potential therapeutic target to attenuate fibrosis progression.

Effects of microRNA-21 on endothelial-to-mesenchymal transition and its role in the pathogenesis of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a disease characterized by persistent airflow restriction. This study aims to explore whether there is endothelial-to-mesenchymal transition (EndMT) in COPD mice and to explore the relationship between microRNA-21 (miR-21) and EndMT. We established the COPD and the miR-21 gene knockout COPD animal model (both cigarette smoke-induced). Mice were divided into 3 groups (n=4): a control group, a COPD group, and a miR-21 knockout COPD (miR-21-/--COPD) group. Masson trichrome staining was used to observe the deposition of collagen around the perivascular. The relative protein levels and positions of endothelial cell markers including vascular endothelial-cadherin (VE-cadherin), endothelial nitric oxide synthase (eNOS), and platelet endothelial cell adhesion molecule-1 (CD31) as well as mesenchymal cell markers including α-smooth muscle actin (α-SMA) and neural cadherin (N-cadherin) in lung tissues were observed by immunohistochemical staining. Compared with the control group, the area of collagen fibril deposition was increased in the COPD group (P<0.05), the expression levels of VE-cadherin, eNOS, and CD31 were all decreased (all P<0.05), and the expression levels of α-SMA and N-cadherin were increased (both P<0.05). Compared with the COPD group, the miR-21-/--COPD group had a reduced area of collagen fiber deposition (P<0.05), the expression levels of VE-cadherin, eNOS, and CD31 were all increased (all P<0.05), and the expression levels of α-SMA and N-cadherin were decreased (both P<0.05). There is a EndMT process in cigarette smoke-induced COPD animal models.MiR-21 gene knockdown could reduce collagen deposition area and inhibit the EndMT process in COPD mice.

MicroRNA-155 Plays Selective Cell-Intrinsic Roles in Brain-Infiltrating Immune Cell Populations during Neuroinflammation.

The proinflammatory microRNA-155 (miR-155) is highly expressed in the serum and CNS lesions of patients with multiple sclerosis (MS). Global knockout (KO) of miR-155 in mice confers resistance to a mouse model of MS, experimental autoimmune encephalomyelitis (EAE), by reducing the encephalogenic potential of CNS-infiltrating Th17 T cells. However, cell-intrinsic roles for miR-155 during EAE have not been formally determined. In this study, we use single-cell RNA sequencing and cell-specific conditional miR-155 KOs to determine the importance of miR-155 expression in distinct immune cell populations. Time-course single-cell sequencing revealed reductions in T cells, macrophages, and dendritic cells (DCs) in global miR-155 KO mice compared with wild-type controls at day 21 after EAE induction. Deletion of miR-155 in T cells, driven by CD4 Cre, significantly reduced disease severity similar to global miR-155 KOs. CD11c Cre-mediated deletion of miR-155 in DCs also resulted in a modest yet significant reduction in the development of EAE, with both T cell- and DC-specific KOs showing a reduction in Th17 T cell infiltration into the CNS. Although miR-155 is highly expressed in infiltrating macrophages during EAE, deletion of miR-155 using LysM Cre did not impact disease severity. Taken together, these data show that although miR-155 is highly expressed in most infiltrating immune cells, miR-155 has distinct roles and requirements depending on the cell type, and we have demonstrated this using the gold standard conditional KO approach. This provides insights into which functionally relevant cell types should be targeted by the next generation of miRNA therapeutics.

MicroRNA-223 attenuates hepatocarcinogenesis by blocking hypoxia-driven angiogenesis and immunosuppression

ObjectiveThe current treatment for hepatocellular carcinoma (HCC) to block angiogenesis and immunosuppression provides some benefits only for a subset of patients with HCC, thus optimised therapeutic regimens are unmet needs,...