MicroRNA levels quantified in whole blood varies from PBMCs

Hypermethylation of the miR-155 gene in the whole blood and decreased plasma level of miR-155 in rheumatoid arthritis

Objectives

miR-155 plays a critical role in the inflammatory process and in diseases such as rheumatoid arthritis (RA). miR155 gene expression is regulated by its gene promoter region CpG island methylation. Previous studies have shown inconsistent changes in circulating levels of mir-155 in RA patients. The aims of our study were to evaluate miR-155 levels in plasma, to investigate its gene methylation level, and to correlate these levels with RA disease activity.

Methods

One hundred and twenty-five patients with RA, and 30 age and sex-matched healthy controls (HC) were enrolled. Whole blood and plasma samples were collected and stored at -80°C until analysis. DAS28 score at the time of the blood draw was used to assess RA disease activity. The methylation status of miR-155 host gene was determined in whole blood by quantitative real-time methylation-specific PCR (qPCR). miR-155 expression levels were evaluated by quantitative reverse transcription PCR.

Results

We found significantly lower circulating miR155 levels in RA patients compared to HC. Interestingly, the miR-155 gene methylation level was significantly higher in RA patients than in HC. miR-155 levels did not correlate with ACPA or RF positivity or disease activity.

Conclusions

We show here higher miR-155 methylation in whole blood and lower plasma miR155 expression in RA patients in comparison to HC. The evaluation of miR-155 host gene methylation status or miR155 plasma level might be a potentially useful marker in RA determination.

Validation of Altered Umbilical Cord Blood MicroRNA Expression in Neonatal Hypoxic-Ischemic Encephalopathy

Importance

Neonatal hypoxic-ischemic encephalopathy (HIE) remains a significant cause of neurologic disability. Identifying infants suitable for therapeutic hypothermia (TH) within a narrow therapeutic time is difficult. No single robust biochemical marker is available to clinicians.

Objective

To assess the ability of a panel of candidate microRNA (miRNA) to evaluate the development and severity of encephalopathy following perinatal asphyxia (PA).

Design, Setting, and Participants

This validation study included 2 cohorts. For the discovery cohort, full-term infants with PA were enrolled at birth to the Biomarkers in Hypoxic-Ischemic Encephalopathy (BiHiVE1) study (2009-2011) in Cork, Ireland. Encephalopathy grade was defined using early electroencephalogram and Sarnat score (n = 68). The BiHiVE1 cohort also enrolled healthy control infants (n = 22). For the validation cohort, the BiHiVE2 multicenter study (2013-2015), based in Cork, Ireland (7500 live births per annum), and Karolinska Huddinge, Sweden (4400 live births per annum), recruited infants with PA along with healthy control infants to validate findings from BiHiVE1 using identical recruitment criteria (n = 80). The experimental design was formulated prior to recruitment, and analysis was conducted from June 2016 to March 2017.

Main Outcomes and Measures

Alterations in umbilical cord whole-blood miRNA expression.

Results

From 170 neonates, 160 were included in the final analysis. The BiHiVE1 cohort included 87 infants (21 control infants, 39 infants with PA, and 27 infants with HIE), and BiHiVE2 included 73 infants (control [n = 22], PA [n = 26], and HIE [n = 25]). The BiHiVE1 and BiHiVE2 had a median age of 40 weeks (interquartile range [IQR], 39-41 weeks) and 40 weeks (IQR, 39-41 weeks), respectively, and included 56 boys and 31 girls and 45 boys and 28 girls, respectively. In BiHiVE1, 12 candidate miRNAs were identified, and 7 of these miRNAs were chosen for validation in BiHiVE2. The BiHiVE2 cohort showed consistent alteration of 3 miRNAs; miR-374a-5p was decreased in infants diagnosed as having HIE compared with healthy control infants (median relative quantification, 0.38; IQR, 0.17-0.77 vs 0.95; IQR, 0.68-1.19; P = .009), miR-376c-3p was decreased in infants with PA compared with healthy control infants (median, 0.42; IQR, 0.21-0.61 vs 0.90; IQR, 0.70-1.30; P = .004), and mir-181b-5p was decreased in infants eligible for TH (median, 0.27; IQR, 0.14-1.41) vs 1.18; IQR, 0.70-2.05; P = .02).

Conclusions and Relevance

Altered miRNA expression was detected in umbilical cord blood of neonates with PA and HIE. These miRNA could assist diagnostic markers for early detection of HIE and PA at birth.

MicroRNAs as biomarkers of resilience or vulnerability to stress

Identifying novel biomarkers of resilience or vulnerability to stress could provide valuable information for the prevention and treatment of stress-related psychiatric disorders. To investigate the utility of blood microRNAs as biomarkers of resilience or vulnerability to stress, microRNAs were assessed before and after 7days of chronic social defeat in rats. Additionally, microRNA profiles of two important stress-regulatory brain regions, the medial prefrontal cortex (mPFC) and basolateral amygdala (BLA), were assessed. Rats that displayed vulnerability to subsequent chronic stress exhibited reductions in circulating miR-24-2-5p, miR-27a-3p, miR-30e-5p, miR-3590-3p, miR-362-3p, and miR-532-5p levels. In contrast, rats that became resilient to stress displayed reduced levels of miR-139-5p, miR-28-3p, miR-326-3p, and miR-99b-5p compared to controls. In the mPFC, miR-126a-3p and miR-708-5p levels were higher in vulnerability compared to resilient rats. In the BLA, 77 microRNAs were significantly altered by stress but none were significantly different between resilient and vulnerable animals. These results provide proof-of-principle that assessment of circulating microRNAs is useful in identifying individuals who are vulnerable to the effects of future stress or individuals who have become resilient to the effects of stress. Furthermore, these data suggest that microRNAs in the mPFC but not in the BLA are regulators of resilience/vulnerability to stress.