The Potential Role of MiRs-139-5p and -454-3p in Endoglin-Knockdown-Induced Angiogenic Dysfunction in HUVECs

Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic disease characterized by aberrant angiogenesis and vascular malformations. Mutations in the transforming growth factor beta co-receptor, endoglin (ENG), account for approximately half of known HHT cases and cause abnormal angiogenic activity in endothelial cells (ECs). To date, how ENG deficiency contributes to EC dysfunction remains to be fully understood. MicroRNAs (miRNAs) regulate virtually every cellular process. We hypothesized that ENG depletion results in miRNA dysregulation that plays an important role in mediating EC dysfunction. Our goal was to test the hypothesis by identifying dysregulated miRNAs in ENG-knockdown human umbilical vein endothelial cells (HUVECs) and characterizing their potential role in EC function. We identified 32 potentially downregulated miRNAs in ENG-knockdown HUVECs with a TaqMan miRNA microarray. MiRs-139-5p and -454-3p were found to be significantly downregulated after RT-qPCR validation. While the inhibition of miR-139-5p or miR-454-3p had no effect on HUVEC viability, proliferation or apoptosis, angiogenic capacity was significantly compromised as determined by a tube formation assay. Most notably, the overexpression of miRs-139-5p and -454-3p rescued impaired tube formation in HUVECs with ENG knockdown. To our knowledge, we are the first to demonstrate miRNA alterations after the knockdown of ENG in HUVECs. Our results indicate a potential role of miRs-139-5p and -454-3p in ENG-deficiency-induced angiogenic dysfunction in ECs. Further study to examine the involvement of miRs-139-5p and -454-3p in HHT pathogenesis is warranted.

The role of Narrow Band Imaging (NBI) in the diagnosis of sinonasal diseases

BACKGROUND

Narrow band imaging (NBI) endoscopy is an optical method that helps to characterise tissue vasculature. Its appli- cation in sinonasal pathology remains scarce and a systematic study of its application to rhinology is lacking. The aim of this study is to analyse and describe the normal sinonasal mucosa under NBI light and to characterise the microvascular features of various sinonasal pathologies. We also want to suggest a classification of the patterns, peculiar to this district, and to evaluate whether they can be indicative of a specific physiological or pathological condition.

METHODS

Digital videos and images under white light and NBI of 103 patients (82 evaluated) with 29 sinonasal pathologies and 55 controls (33 evaluated). were independently analysed by three otolaryngologists and the final pattern was then arranged for each image, reaching an agreement between the individual evaluations.

RESULTS

Once the appearance of normal sinonasal (SN) mucosa was established (SN1), four patterns for the pathological mucosa were described and a working classification was proposed (SN2, SN3, SN4, SN5). We calculated specificity (80.6% vs 90.6%), sensi- tivity (20% vs 38.5%), PPV (46.1% vs 50%), NPV (54.7% vs 85.7%) and accuracy (53% vs 80.3%) of the ability of SN4 and SN5 pattern to discriminate between benign and malignant nasal neoformations.

CONCLUSIONS

This is the first study to propose a systematic NBI description and a classification of the vasculature of healthy and pathological mucosa in the sinonasal tract. Our preliminary results show that this technique can help in the workup of several rhinologic conditions and especially in distinguishing benign from malignant tumors.

Non-Coding RNAs and Hereditary Hemorrhagic Telangiectasia

Non-coding RNAs (ncRNAs) are functional ribonucleic acid (RNA) species that include microRNAs (miRs), a class of short non-coding RNAs (∼21–25 nucleotides), and long non-coding RNAs (lncRNAs) consisting of more than 200 nucleotides. They regulate gene expression post-transcriptionally and are involved in a wide range of pathophysiological processes. Hereditary hemorrhagic telangiectasia (HHT) is a rare disorder inherited in an autosomal dominant fashion characterized by vascular dysplasia. Patients can develop life-threatening vascular malformations and experience severe hemorrhaging. Effective pharmacological therapies are limited. The study of ncRNAs in HHT is an emerging field with great promise. This review will explore the current literature on the involvement of ncRNAs in HHT as diagnostic and pathogenic factors.

MicroRNA profiling of human myeloid angiogenic cells derived from peripheral blood mononuclear cells

Human myeloid angiogenic cells (MACs), also termed early endothelial progenitor cells, play an important role in neovascularization and vascular repair. MicroRNAs (miRNAs) are a class of naturally occurring, noncoding, short (∼22 nucleotides), single-stranded RNAs that regulate gene expression post-transcriptionally. MiRNAs have been shown to regulate MAC function. A miRNA signature of MACs was described approximately a decade ago, and many new miRNAs have been discovered in recent years. In this study, we aimed to provide an up-to-date miRNA signature for human MACs. MACs were obtained by culture of human peripheral blood mononuclear cells in endothelial medium for 7 days. Using qPCR array analysis we identified 72 highly expressed miRNAs (C_T value < 30) in human MACs. RT-qPCR quantification of select miRNAs revealed a strong correlation between the C_T values detected by the array analysis and RT-qPCR, suggesting the miRNA signature generated by the qPCR array assay is accurate and reliable. Experimentally validated target genes of the 10 most highly expressed miRNAs were retrieved. Only a few of the targets and their respective miRNAs have been studied for their role in MAC biology. Our study therefore provides a valuable repository of miRNAs for future exploration of miRNA function in MACs.

Decreased levels of miR-28-5p and miR-361-3p and increased levels of insulin-like growth factor 1 mRNA in mononuclear cells from patients with hereditary hemorrhagic telangiectasia 1

Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular disorder inherited in an autosomal dominant manner. Patients with HHT can develop vascular dysplasias called telangiectasias and arteriovenous malformations (AVMs). Our objective was to profile and characterize micro-RNAs (miRNAs), short noncoding RNAs that regulate gene expression posttranscriptionally, in HHT patient-derived peripheral blood mononuclear cells (PBMCs). PBMCs, comprised mostly of lymphocytes and monocytes, have been reported to be dysfunctional in HHT. A total of 40 clinically confirmed HHT patients and 22 controls were enrolled in this study. PBMCs were isolated from 16 mL of peripheral blood and purified for total RNA. MiRNA expression profiling was conducted with a human miRNA array analysis. Select dysregulated miRNAs and miRNA targets were validated with reverse transcription-quantitative polymerase chain reaction. Of the 377 miRNAs screened, 41 dysregulated miRNAs were identified. Both miR-28-5p and miR-361-3p, known to target insulin-like growth factor 1 (IGF1), a potent angiogenic growth factor, were found to be significantly downregulated in HHT patients. Consequently, IGF1 mRNA levels were found to be significantly elevated. Our research successfully identified miRNA dysregulation and elevated IGF1 mRNA levels in PBMCs from HHT patients. This novel discovery represents a potential pathogenic mechanism that could be targeted to alleviate clinical manifestations of HHT.

Dysfunction and Therapeutic Potential of Endothelial Progenitor Cells in Diabetes Mellitus

Diabetes mellitus (DM) is a chronic, multifactorial metabolic disease whereby insulin deficiency or resistance results in hyperglycemia. Endothelial cells (ECs) form the innermost layer of the blood vessel and produce and release a variety of vasoactive substances and growth factors to regulate vascular homeostasis and angiogenesis. Hyperglycemia and insulin resistance can cause endothelial dysfunction, leading to vascular complications such as coronary artery disease, peripheral arterial disease, diabetic nephropathy, neuropathy and retinopathy. The detrimental effect exerted on ECs by hyperglycemia and insulin resistance underlines the importance of reparatory mechanisms in DM. Endothelial progenitor cells (EPCs), derived from bone marrow, have been recognized as endogenous cells involved in endothelial repair and new blood vessel formation. Initially isolated from a subset of circulating CD34+ mononuclear cells, EPCs were found to possess the ability to differentiate into ECs when cultured in vitro and incorporate into newly formed vessels upon transplantation in animal models of ischemia. Due to the low frequency of CD34+ cells in circulation, the vast majority of studies investigating EPC actions have used cells that are generated through the culture of peripheral blood mononuclear cells (PBMNCs) for 4 - 7 days in endothelial selective medium. These cells, mainly of myeloid hematopoietic cell origin, were termed “Early EPCs,” of which, few expressed stem/progenitor-cell markers. Therefore, early EPCs were also termed “myeloid angiogenic cells” (MACs). When PBMNCs are cultured for over 2 weeks, early EPCs gradually diminish while so-called late EPCs appear. Late EPCs share phenotypic features with mature ECs and are therefore also termed blood-derived ECs; they will not be addressed in this review. MAC dysfunction has been observed in a variety of disease conditions including DM. In this article we review the activities and therapeutic potential of MACs in DM. We will interchangeably use “EPCs” and “MACs” to refer to the cells procured by culture of PBMNCs in EC selective medium for approximately 7 days.

Abstract 330: MicroRNA Dysregulation in Patients with Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a rare, understudied, autosomal dominant disorder that is characterized by angiogenic abnormalities. Gene mutations in HHT involve key angiogenic factors. Clinical manifestations of HHT include benign telangiectasias and potentially life threatening arteriovenous malformations (AVMs) that can occur in the pulmonary and cerebral circulation. Currently, there is no effective treatment for HHT. PBMCs have been implicated in the pathogenesis of HHT and the goal of this study was to profile and characterize PBMC microRNAs, to determine whether they had a role in the observed angiogenic abnormalities. A total of 28 HHT patients with confirmed mutations in either ENG , ACVRL1 or SMAD4 , and 25 controls were recruited. PBMCs were isolated from 16 ml of peripheral blood and total RNA was obtained. PBMC expression profiling was conducted with a human miR array analysis. Dysregulated miRs identified from the analysis were then validated with RT-qPCR. Significant differences were determined using a two-tailed t- test. Of the 800 miRs screened, 167 dysregulated miRs were identified in PBMCs. Selected PBMC miRs (MiRs-28-5p, -30b-5p, -361-3p and -374a-5p) were validated with RT-qPCR. PBMC miR-361-3p ( p =0.025) known to target IGF1, was found to be significantly decreased compared to controls. IGF1 messenger RNA (mRNA) levels in PBMCS of HHT patients was significantly elevated (p=0.005) compared to controls. Our results show dysregulation of select miRs in PBMCs from HHT patients. We also show an increase in IGF1 mRNA, an important angiogenic factor, in PBMCs that may be related to the downregulation of miR-361-3p in HHT patients. This may represent an important pathogenic mechanism that is involved in the angiogenic dysfunction observed in HHT and may provide for a unique miR therapeutic target.