Anti-inflammatory effects of methoxyphenolic compounds on human airway cells

<p>Abstract</p> <p>Background</p> <p>The respiratory epithelium plays a central role in the inflammatory response in asthma and other diseases. Methoxyphenolic compounds are purported to be effective anti-inflammatory agents, but their effects on the airway epithelium have not been well characterized.</p> <p>Methods</p> <p>Human airway cells were stimulated with TNF-α in the presence or absence of 4-substituted methoxyphenols and resveratrol. The expression of various cytokines was measured by qPCR, ELISAs, and protein arrays. Reactive oxygen species (ROS) production was measured with a reactive fluorescent probe (3',6'-diacetate-2',7'-dichlorofluorescein). Activation of NF-κB was measured by nuclear translocation and phosphorylation. Ribonuclear protein association with mRNA was assessed with a biotin-RNA affinity isolation assay.</p> <p>Results</p> <p>Multiple inflammatory mediators were inhibited by methoxyphenols, including: CCL2, CCL5, IL-6, IL-8, ICAM-1, MIF, CXCL1, CXCL10, and Serpin E1. IC₅₀values were obtained for each compound that showed significant anti-inflammatory activity: diapocynin (20.3 μM), resveratrol (42.7 μM), 2-methoxyhydroquinone (64.3 μM), apocynin (146.6 μM), and 4-amino-2-methoxyphenol (410 μM). The anti-inflammatory activity did not correlate with inhibition of reactive oxygen species production or NF-κB activation. However, methoxyphenols inhibited binding of the RNA-binding protein HuR to mRNA, indicating that they may act post-transcriptionally.</p> <p>Conclusions</p> <p>Methoxyphenols demonstrate anti-inflammatory activity in human airway cells. More potent compounds that act via similar mechanisms may have therapeutic potential as novel anti-inflammatory agents.</p

A challenging diagnosis of alpha-1-antitrypsin deficiency: identification of a patient with a novel F/Null phenotype

Alpha-1-antitrypsin (A1AT) deficiency is a genetic disease characterized by low levels and/or function of A1AT protein. A1AT deficiency can result in the development of COPD, liver disease, and certain skin conditions. The disease can be diagnosed by demonstrating a low level of A1AT protein and genotype screening for S and Z mutations, which are the most common. However, there are many genetic variants in A1AT deficiency, and this screening may miss rarer cases, such as those caused by dysfunctional protein. We identified a patient with a previously unreported F/null phenotype that was missed by routine screening. This case highlights the wide variation in possible mutations, limitations in diagnostics, and the importance of combining clinical suspicion with measurement of protein levels, phenotypic analysis, and in appropriate cases expanded genetic analysis

Post-transcriptional regulation of glucocorticoid function

Glucocorticoids (GCs) are corticosteroid hormones critically involved in the homeostatic control of stress and immune responses. Endogenous GCs generally tend to support the innate immune responses while inhibiting overexpressed adaptive immune responses. Synthetic GCs, given systemically or topically, are the first-line anti-inflammatory drug class prescribed in the treatment of the majority of chronic inflammatory and immune-mediated diseases. Regulation of gene transcription through the ligand-activated glucocorticoid receptor (GR) is the core mechanism of their anti-inflammatory action; however their regulatory function spans from early signaling-through non-genomic actions-to downstream post-translational modifications. The anti-inflammatory action of GCs is achieved also through post-transcriptional regulation (PTR) of gene expression, which modulates the rates of mRNA transport, decay and translation. The molecular mechanisms by which GC act on PTR are still ill-defined but studies aimed at their discovery have been increasing in the last decade, subsequent to definitive experimental evidences of the important pathogenic role of PTR in inflammatory responses. In this chapter we will review the growing data indicating that control of deregulated post-transcriptional pathways is a critical, yet underappreciated component of GCs' efficient anti-inflammatory action. A more detailed understanding of the molecular species and pathways by which GC regulate inflammation by post-transcriptional mechanisms may lead to novel anti-inflammatory strategies that could be pursued as a GC-independent therapeutic approach

Identification of biologic-responsive phenotypes in elderly people with eosinophilic asthma

Background: Asthma in the elderly is not as well studied as in younger age groups. Age-related immunosenescence may result in diminished TH2 inflammation, which raises a question about whether asthma in elderly patients responds well to anti-TH2 asthma biologics. Objective: We sought to determine whether asthma in elderly people has different TH2 biomarkers and clinical features compared to nonelderly people, and if disease in the 2 age groups responds differently to anti-TH2 biologics. We also aimed to identify treatment-responsive phenotypes with clinical and biomarker features that could be used to predict best response to biologics. Methods: A retrospective chart review was conducted for 56 patients (30 elderly [age ≥62 years] and 26 nonelderly [ages 18-59 years] subjects) with severe asthma treated with dupilumab or benralizumab. Differences in baseline characteristics and response to treatment were analyzed. A hierarchical cluster analysis was also performed to identify treatment-responsive phenotypes. Significance threshold was P = .05 for all analyses. Results: Baseline characteristics and TH2 biomarkers (blood eosinophil level, total IgE, aeroallergen sensitivity) were similar between elderly and nonelderly subjects. The disease in both groups responded well to biologics (improvement in ACT scores, decreased exacerbations, decreased need for prednisone), but no significant response difference was found based on age groups. Cluster analysis identified 3 phenotypes, as follows: cluster 1, youngest age, moderate eosinophil levels, lowest total IgE, few environmental allergies, and least response to biologics; cluster 2, intermediate age, lowest eosinophil level, highest IgE level, many environmental allergies, and an intermediate response to biologics; and cluster 3, oldest ages, highest eosinophil levels, high total IgE, few environmental allergies, and best response to biologics. These results confirm trends seen in another study utilizing cluster analyses showing that subjects with highest levels of IgE and eosinophils responded better to biologic treatment for asthma. Conclusion: Elderly people with asthma should be considered for biologic therapy no differently than younger people. There may be subgroups of patients with different biologic responses based on age, allergenicity, IgE, and eosinophil levels that could be used to predict treatment response

MicroRNA-146a is induced by inflammatory stimuli in airway epithelial cells and augments the anti-inflammatory effects of glucocorticoids.

BACKGROUND:MicroRNAs (miRNAs) are emerging as central regulators of inflammation, but their role in asthma and airway epithelial cells is not well studied. Glucocorticoids are the cornerstone of therapy in asthma and other inflammatory disease, yet their mechanisms of action are not completely elucidated, and it is not clear whether miRNAs modulate their effects. OBJECTIVE:We aimed to identify miRNAs that regulate cytokine and chemokine expression in airway epithelial cells and whether these miRNAs are subject to the effects of glucocorticoids. METHODS AND RESULTS:MicroRNAomic analyses of immortalized, normal human bronchial epithelial cells identified 7 miRNAs that were altered by inflammatory cytokine treatment and 22 that were regulated by glucocorticoids (n = 3 for each treatment condition). MiR-146a emerged as a central candidate, whose expression was induced by TNF-α and repressed by glucocorticoids. Its role as a candidate in asthmatic inflammation was supported by expression profiling in human asthmatics, which showed that plasma miR-146a expression was elevated in asthma and associated with measures related to worse asthma outcomes, including elevated blood eosinophil counts, higher asthma control questionnaire scores, and need for higher doses of inhaled glucocorticoids. However, transfection of miR-146a in A549 cells treated with TNF-α +/- glucocorticoids produced an anti-inflammatory effect and increased efficacy of glucocorticoids. CONCLUSIONS:We propose a model whereby miR-146a is induced by inflammatory conditions as a feedback mechanism to limit inflammation. Exogenous administration of miR-146a augmented the effects of glucocorticoids and could be a novel therapeutic strategy to enhance efficacy of these medications

Plasma microRNA profiles identify distinct clinical phenotypes in human asthmatics

Aim: Asthma is a chronic inflammatory syndrome that is characterized by heterogeneous disease pathogeneses that produce distinct subtypes. There is a great need to develop biomarkers to distinguish these subtypes and help guide specific therapy and better predict outcomes, particularly in severe asthma where a number of targeted therapeutics are now available. We sought to determine whether expression of asthma-specific microRNAs (miRNAs) could distinguish phenotypic differences in a diverse cohort of asthmatic subjects that spanned a range of disease severity.Methods: RNA was isolated from peripheral blood from human subjects. Expression of 39 miRNAs was then screened. Sample cycle threshold values were normalized. Normally distributed data were analyzed and hierarchical cluster was performed.Results: Peripheral blood was obtained from 62 adults. We identified four clusters of asthmatics defined by 5 distinct miRNA expression patterns. Cluster 1 was associated with mild asthma, low inhaled corticosteroid use, and low eosinophil levels. Cluster 3 and 4 consisted primarily of severe asthmatics with poor asthma control, and Cluster 3 was specifically associated with high IgE, high blood eosinophil levels, and racial disparity (higher proportion of Black subjects). Cluster 2 was comprised predominantly of mild-moderate asthmatics that had higher blood eosinophils than Cluster 1.Conclusion: These results indicate the miRNA expression profiling can be useful to identify distinct asthma phenotypes, and have potential to better understand disease pathogenesis and help guide therapy

MicroRNA-570-3p regulates HuR and cytokine expression in airway epithelial cells

Asthma is a chronic lung disease that affects people of all ages and is characterized by high morbidity. The mechanisms of asthma pathogenesis are unclear, and there is a need for development of diagnostic biomarkers and greater understanding of regulation of inflammatory responses in the lung. Post-transcriptional regulation of cytokines, chemokines, and growth factors by the action of microRNAs and RNA-binding proteins on stability or translation of mature transcripts is emerging as a central means of regulating the inflammatory response. In this study, we demonstrate that miR-570-3p expression is increased with TNFα stimuli in normal human bronchial epithelial cells (2.6 ± 0.6, p = 0.01) and the human airway epithelial cell line A549 (4.6 ± 1.4, p = 0.0068), and evaluate the functional effects of its overexpression on predicted mRNA target genes in transfected A549 cells. MiR-570-3p upregulated numerous cytokines and chemokines (CCL4, CCL5, TNFα, and IL-6) and also enhanced their induction by TNFα. For other cytokines (CCL2 and IL-8), the microRNA exhibited an inhibitory effect to repress their upregulation by TNFα. These effects were mediated by a complex pattern of both direct and indirect regulation of downstream targets by miR-570-3p. We also show that the RNA-binding protein HuR is a direct target of miR-570-3p, which has implications for expression of numerous other inflammatory mediators that HuR is known regulate post-transcriptionally. Finally, expression of endogenous miR-570-3p was examined in both serum and exhaled breath condensate (EBC) from asthmatic and healthy patients, and was found to be significantly lower in EBC of asthmatics and inversely correlated to their lung function. These studies implicate miR-570-3p as a potential regulator of asthmatic inflammation with potential as both a diagnostic and therapeutic target in asthma