Reproducibility of quantitative real-time PCR assay in microRNA expression profiling and comparison with microarray analysis in narcolepsy

Unraveling the pathophysiology of narcolepsy type 1 through hypothesis-driven and hypothesis-generating approaches

Narcolepsy type 1 (NT1) is a chronic orphan neurological sleep disorder characterized by the loss of hypocretin-producing neurons in the lateral hypothalamus, which play a crucial role in wakefulness. Given the genetic association with the HLA-DQB1 * 06:02 allele and environmental links with the 2009 influenza pandemic, many lines of evidence point towards an immune mechanism, notably autoimmunity, underlying the disease pathophysiology. Autoreactive T cells are found in the blood of NT1 patients, and mouse models demonstrate their migratory capacity and contribution in the selective destruction of hypocretin-producing neurons. However, direct evidence for their role in human NT1 pathophysiology remains elusive. In complementing these findings, hypothesis-generating approaches-including multiparametric immune profiling, transcriptomic sequencing and large-scale proteomic of blood and cerebrospinal fluid-have uncovered promising new avenues into the immune system's involvement in NT1. In this review, we explore the mechanisms driving NT1 pathogenesis, emphasizing both hypothesis-driven and hypothesis-generating approaches, and discuss potential future directions that could pave the way for targeted immunotherapies.

Genetics and epigenetics of rare hypersomnia

Herein we focus on connections between genetics and some central disorders of hypersomnolence - narcolepsy types 1 and 2 (NT1, NT2), idiopathic hypersomnia (IH), and Kleine-Levin syndrome (KLS) - for a better understanding of their etiopathogenetic mechanisms and a better diagnostic and therapeutic definition. Gene pleiotropism influences neurological and sleep disorders such as hypersomnia; therefore, genetics allows us to uncover common pathways to different pathologies, with potential new therapeutic perspectives. An important body of evidence has accumulated on NT1 and IH, allowing a better understanding of etiopathogenesis, disease biomarkers, and possible new therapeutic approaches. Further studies are needed in the field of epigenetics, which has a potential role in the modulation of biological specific hypersomnia pathways.

Focus on the Complex Interconnection between Cancer, Narcolepsy and Other Neurodegenerative Diseases: A Possible Case of Orexin-Dependent Inverse Comorbidity

Simple Summary

This narrative review first describes from several points of view the complex interrelationship between cancer and neurodegeneration, with special attention to the mechanisms that might underlie an inverse relationship between them. In particular, the mechanisms that might induce an imbalance between cell apoptotic and proliferative stimuli are discussed. Second, the review summarizes findings on orexins and their involvement in narcolepsy, neurodegenerative diseases, and cancer, starting from epidemiological data then addressing laboratory findings, animal models, and human clinical observational and interventional investigations. Important research efforts are warranted on these topics, as they might lead to novel therapeutic approaches to both neurodegenerative diseases and cancer.

Abstract

Conditions such as Alzheimer’s (AD) and Parkinson’s diseases (PD) are less prevalent in cancer survivors and, overall, cancer is less prevalent in subjects with these neurodegenerative disorders. This seems to suggest that a propensity towards one type of disease may decrease the risk of the other. In addition to epidemiologic data, there is also evidence of a complex biological interconnection, with genes, proteins, and pathways often showing opposite dysregulation in cancer and neurodegenerative diseases. In this narrative review, we focus on the possible role played by orexin signaling, which is altered in patients with narcolepsy type 1 and in those with AD and PD, and which has been linked to β-amyloid brain levels and inflammation in mouse models and to cancer in cell lines. Taken together, these lines of evidence depict a possible case of inverse comorbidity between cancer and neurodegenerative disorders, with a role played by orexins. These considerations suggest a therapeutic potential of orexin modulation in diverse pathologies such as narcolepsy, neurodegenerative disorders, and cancer.

The emerging role of the MiR-1272-ADAM9-CDCP1 signaling pathway in the progression of glioma

Glioma is a primary, malignant, and aggressive brain tumor in adults. To develop new therapeutic strategies for glioma, we must determine its underlying mechanisms. In the present study, we aimed to investigate the potential role of miR-1272-ADAM9-CDCP1 signaling in the progression of glioma. We found that ectopic expression of miR-1272 produced significant inhibitory effects on cell proliferation and migration and was associated with cell cycle G0/G1 arrest in A172 and SHG44 glioma cells. Using the luciferase reporter assay, we identified ADAM9 as a target of miR-1272. The expression of ADAM9 was markedly decreased or increased after overexpression or inhibition, respectively, of miR-1272 in glioma cells. Moreover, overexpression of ADAM9 reversed the inhibitory effects of miR-1272 on glioma cell progression. Furthermore, CDCP1 served as a potential downstream molecule of miR-1272/ADAM9 signaling in glioma and promoted the proliferation and migration of glioma. Results derived from clinical samples and online databases confirmed correlations between the expression of ADAM9 and CDCP1 and both the severity and prognosis of glioma. In conclusion, these results suggest that miR-1272 and CDCP1 may act as novel regulators in glioma. The miR-1272/ADAM9/CDCP1 pathway may serve as a potential candidate pathway for the prevention of glioma.

Short-term transcriptome and microRNAs responses to exposure to different air pollutants in two population studies

Diesel vehicle emissions are the major source of genotoxic compounds in ambient air from urban areas. These pollutants are linked to risks of cardiovascular diseases, lung cancer, respiratory infections and adverse neurological effects. Biological events associated with exposure to some air pollutants are widely unknown but applying omics techniques may help to identify the molecular processes that link exposure to disease risk. Most data on health risks are related to long-term exposure, so the aim of this study is to investigate the impact of short-term exposure (two hours) to air pollutants on the blood transcriptome and microRNA expression levels. We analyzed transcriptomics and microRNA expression using microarray technology on blood samples from volunteers participating in studies in London, the Oxford Street cohort, and, in Barcelona, the TAPAS cohort. Personal exposure levels measurements of particulate matter (PM₁₀, PM_2.5), ultrafine particles (UFPC), nitrogen oxides (NO₂, NO and NOx), black carbon (BC) and carbon oxides (CO and CO₂) were registered for each volunteer. Associations between air pollutant levels and gene/microRNA expression were evaluated using multivariate normal models (MVN). MVN-models identified compound-specific expression of blood cell genes and microRNAs associated with air pollution despite the low exposure levels, the short exposure periods and the relatively small-sized cohorts. Hsa-miR-197-3p, hsa-miR-29a-3p, hsa-miR-15a-5p, hsa-miR-16-5p and hsa-miR-92a-3p are found significantly expressed in association with exposures. These microRNAs target also relevant transcripts, indicating their potential relevance in the research of omics-biomarkers responding to air pollution. Furthermore, these microRNAs are also known to be associated with diseases previously linked to air pollution exposure including several cancers such lung cancer and Alzheimer's disease. In conclusion, we identified in this study promising compound-specific mRNA and microRNA biomarkers after two hours of exposure to low levels of air pollutants during two hours that suggest increased cancer risks.

Narcolepsy patients' blood-based miRNA expression profiling: miRNA expression differences with Pandemrix vaccination

OBJECTIVES

Narcolepsy is a neurological sleep disorder characterized by excessive daytime sleepiness and nighttime sleep disturbance. Among children and adolescents vaccinated with Pandemrix vaccine in Finland and Sweden, the number of narcolepsy cases increased. Our aim was to identify miRNAs involved in narcolepsy and their association with Pandemrix vaccination.

MATERIALS AND METHODS

We performed global miRNA proofing by miRNA microarrays followed by RT-PCR verification on 20 narcolepsy patients (Pandemrix-associated and Pandemrix-non-associated) and 17 controls (vaccinated and non-vaccinated).

RESULTS

Between all narcolepsy patients and controls, 11 miRNAs were differentially expressed; 17 miRNAs showed significantly differential expression between Pandemrix-non-associated narcolepsy patients and non-vaccinated healthy controls. MiR-188-5p and miR-4499 were over-expressed in narcolepsy patients vs healthy controls. Two miRNAs, miR-1470 and miR-4455, were under-expressed in Pandemrix-associated narcolepsy patients vs Pandemrix-non-associated narcolepsy patients.

CONCLUSIONS

We identified miRNA expression patterns in narcolepsy patients that linked them to mRNA targets known to be involved in brain-related pathways or brain disorders.