Reduced expression level of the cyclic adenosine monophosphate response element-binding protein contributes to lung aging

miRNome Profiling Detects miR-101-3p and miR-142-5p as Putative Blood Biomarkers of Frailty Syndrome

Frailty is an aging-related pathology, defined as a state of increased vulnerability to stressors, leading to a limited capacity to meet homeostatic demands. Extracellular microRNAs (miRNAs) were proposed as potential biomarkers of various disease conditions, including age-related pathologies. The primary objective of this study was to identify blood miRNAs that could serve as potential biomarkers and candidate mechanisms of frailty. Using the Fried index, we enrolled 22 robust and 19 frail subjects. Blood and urine samples were analysed for several biochemical parameters. We observed that sTNF-R was robustly upregulated in the frail group, indicating the presence of an inflammatory state. Further, by RNA-seq, we profiled 2654 mature miRNAs in the whole blood of the two groups. Expression levels of selected differentially expressed miRNAs were validated by qPCR, and target prediction analyses were performed for the dysregulated miRNAs. We identified 2 miRNAs able to significantly differentiate frail patients from robust subjects. Both miR-101-3p and miR-142-5p were found to be downregulated in the frail vs. robust group. Finally, using bioinformatics targets prediction tools, we explored the potential molecular mechanisms and cellular pathways regulated by the two miRNAs and potentially involved in frailty.

Glucocorticoid Receptor α Mediates Roflumilast's Ability to Restore Dexamethasone Sensitivity in COPD

Background

Glucocorticoids are commonly prescribed to treat inflammation of the respiratory system; however, they are mostly ineffective for controlling chronic obstructive pulmonary disease (COPD)-associated inflammation. This study aimed to elucidate the molecular mechanisms responsible for such glucocorticoid inefficacy in COPD, which may be instrumental to providing better patient outcomes. Roflumilast is a selective phosphodiesterase-4 (PDE4) inhibitor with anti-inflammatory properties in severe COPD patients who have a history of exacerbations. Roflumilast has a suggested ability to mitigate glucocorticoid resistance, but the mechanism is unknown.

Methods

To understand the mechanism that mediates roflumilast-induced restoration of glucocorticoid sensitivity in COPD, we tested the role of glucocorticoid receptor α (GRα). Roflumilast's effects on GRα expression and transcriptional activity were assessed in bronchial epithelial cells from COPD patients.

Results

We found that both GRα expression and activity are downregulated in bronchial epithelial cells from COPD patients and that roflumilast stimulates both GRα mRNA synthesis and GRα's transcriptional activity in COPD bronchial epithelial cells. We also demonstrate that roflumilast enhances dexamethasone's ability to suppress pro-inflammatory mediator production, in a GRα-dependent manner.

Discussion

Our findings highlight the significance of roflumilast-induced GRα upregulation for COPD therapeutic strategies by revealing that roflumilast restores glucocorticoid sensitivity by sustaining GRα expression.

Receptor for advanced glycation end-products modulates lung development and lung sensitivity to hyperoxic injury in newborn mice

The receptor for advanced glycation end-products is mainly expressed in type I alveolar epithelial cells but its importance in lung development and response to neonatal hyperoxia is unclear. Therefore, our study aimed at the analysis of young wildtype and RAGE knockout mice which grew up under normoxic or hyperoxic air conditions for the first 14 days followed by a longer period of normoxic conditions. Lung histology, expression of lung-specific proteins, and respiratory mechanics were analyzed when the mice reached an age of 2 or 4 months. These analyses indicated less but larger and thicker alveoli in RAGE knockout mice, reverse differences in the mRNA and protein amount of pro-surfactant proteins (pro-SP-B, pro-SP-C) and aquaporin-5, and differences in the amount of elastin and CREB, a pro-survival transcription factor, as well as higher lung compliance. Despite this potential disadvantages, RAGE knockout lungs showed less long-term damages mediated by neonatal hyperoxia. In detail, the hyperoxia-mediated reduction in alveoli, enlargement of airspaces, fragmentation of elastic fibers, and increased lung compliance combined with reduced peak airflows was less pronounced in RAGE knockout mice. In conclusion, RAGE supports the alveolarization but makes the lung more susceptible to hyperoxic injury shortly after birth. Blocking RAGE function could still be a helpful tool in reducing hyperoxia-mediated lung pathologies during alveolarization.

Long-term endurance running activity causes pulmonary changes depending on the receptor for advanced glycation end-products

The receptor for advanced glycation end-products (RAGE) is an immunoglobulin superfamily cell adhesion molecule predominantly expressed in the lung, but its pulmonary importance is incompletely understood. Since RAGE alters the respiratory mechanics, which is also challenged by endurance running activity, we studied the RAGE-dependent effect of higher running activity on selected lung parameters in a long-term animal model using wild-type (WT) and RAGE knockout (RAGE-KO) mice. Higher long-term running activity of mice was ensured by providing a running wheel for 8 months. Recording the running activity revealed that RAGE-KO mice are more active than WT mice. RAGE-KO caused an increased lung compliance which additionally increased after long-term running activity with minor limitation of the expiratory flow, whereas the respiratory mechanics of WT mice remained constant. Although RAGE-KO mice had a less dense alveolar-capillary barrier for immune cells, higher long-term running activity led only in WT mice to more leukocyte infiltrations in the lung tissue and aggregations of lymphoid cells in the airways. In this regard, WT mice of the activity group were also more sensitive to ventilation-mediated airway damages. In contrast to RAGE-KO mice of the activity group, lungs of WT mice did not show an increase in the cAMP response element-binding protein, a transcription factor regulating many pro-survival genes. Our findings suggest an important role of RAGE in the physical capability due to its effect on the lung compliance as well as RAGE as a mediator of airway damages caused by higher long-term running activity.

A common variant in RAB27A gene is associated with fractional exhaled nitric oxide levels in adults

BACKGROUND

Exhaled nitric oxide (FeNO) is a biomarker for eosinophilic inflammation in the airways and for responsiveness to corticosteroids in asthmatics.

OBJECTIVE

We sought to identify in adults the genetic determinants of fractional exhaled nitric oxide (FeNO) levels and to assess whether environmental and disease-related factors influence these associations.

METHODS

We performed a genome-wide association study of FeNO through meta-analysis of two independent discovery samples of European ancestry: the outbred EGEA study (French Epidemiological study on the Genetics and Environment of Asthma, N = 610 adults) and the Hutterites (N = 601 adults), a founder population living on communal farms. Replication of main findings was assessed in adults from an isolated village in Sardinia (Talana study, N = 450). We then investigated the influence of asthma, atopy and tobacco smoke exposure on these genetic associations, and whether they were also associated with FeNO values in children of the EAGLE (EArly Genetics & Lifecourse Epidemiology, N = 8858) consortium.

RESULTS

We detected a common variant in RAB27A (rs2444043) associated with FeNO that reached the genome-wide significant level (P = 1.6 × 10(-7) ) in the combined discovery and replication adult data sets. This SNP belongs to member of RAS oncogene family (RAB27A) and was associated with an expression quantitative trait locus for RAB27A in lymphoblastoid cell lines from asthmatics. A second suggestive locus (rs2194437, P = 8.9 × 10(-7) ) located nearby the sodium/calcium exchanger 1 (SLC8A1) was mainly detected in atopic subjects and influenced by inhaled corticosteroid use. These two loci were not associated with childhood FeNO values.

CONCLUSIONS AND CLINICAL RELEVANCE

This study identified a common variant located in RAB27A gene influencing FeNO levels specifically in adults and with a biological relevance to the regulation of FeNO levels. This study provides new insight into the biological mechanisms underlying FeNO levels in adults.