Spurious transcription causing innate immune responses is prevented by 5-hydroxymethylcytosine

Generation of functional transcripts requires transcriptional initiation at regular start sites, avoiding production of aberrant and potentially hazardous aberrant RNAs. The mechanisms maintaining transcriptional fidelity and the impact of spurious transcripts on cellular physiology and organ function have not been fully elucidated. Here we show that TET3, which successively oxidizes 5-methylcytosine to 5-hydroxymethylcytosine (5hmC) and other derivatives, prevents aberrant intragenic entry of RNA polymerase II pSer5 into highly expressed genes of airway smooth muscle cells, assuring faithful transcriptional initiation at canonical start sites. Loss of TET3-dependent 5hmC production in SMCs results in accumulation of spurious transcripts, which stimulate the endosomal nucleic-acid-sensing TLR7/8 signaling pathway, thereby provoking massive inflammation and airway remodeling resembling human bronchial asthma. Furthermore, we found that 5hmC levels are substantially lower in human asthma airways compared with control samples. Suppression of spurious transcription might be important to prevent chronic inflammation in asthma

Immune mechanisms in pulmonary fibrosis.

Pulmonary fibrosis, particularly idiopathic pulmonary fibrosis, represents a chronic and progressive disease with high mortality and limited therapeutic options. Excessive deposition of extracellular matrix proteins results in fibrotic remodeling, alveolar destruction and irreversible loss of lung function. Both innate and adaptive immune mechanisms contribute to fibrogenesis at several cellular and non-cellular levels. Here, we summarize and discuss the role of immune cells (T cells, neutrophils, macrophages and fibrocytes) and soluble mediators (cytokines and chemokines) involved in pulmonary fibrosis, pointing towards novel immune-based therapeutic strategies in the field

Dietary flavanones and citrus fruits influence cytokines and thyroid transcription factor-1 in an HDM-induced chronic asthma murine model

The effects of hesperetin plus naringenin, orange juice and grapefruit juice on mRNA expression of TNF-α, TGF-β1 and TTF-1 in a house dust mite (HDM)-induced asthma animal model were investigated. Interventional mice exposed to HDM for 6 weeks received hesperetin plus naringenin, orange plus grapefruit juice, orange juice, grapefruit juice or water during the last 4 weeks, whereas non-asthmatic control mice consumed water. Lung tissue TNF-α and TGF-β1 expressions in supplemented groups were significantly reduced (p�<�0.0001 and p�<�0.001, respectively) compared with asthmatic controls. Hesperetin plus naringenin and orange plus grapefruit juice intake reduced expression of TGF-β1 more than grapefruit juice (p���0.02) or orange juice compared with the asthmatic control group. All supplemented groups had non-significantly higher TTF-1 expression compared with water intake groups. Orange plus grapefruit juice or hesperetin plus naringenin with down-regulation of TNF-α and TGF-β1 may ameliorate lung damage in the lung tissue of asthmatic subjects. © 2016 Elsevier Lt

Effects of the flavanone combination hesperetin-naringenin, and orange and grapefruit juices, on airway inflammation and remodeling in a murine asthma model

We investigated whether flavanones, hesperetin-naringenin, orange, and grapefruit juices reduce airway inflammation and remodeling in murine chronic asthma model. To establish chronic asthma, mice received house dust mite (HDM) for 3days in 2weeks, followed by twice per week for 4weeks. Concurrently, during the last 4weeks, mice received hesperetin plus naringenin (HN), orange plus grapefruit juice (OGJ), orange juice (OJ), or grapefruit juice (GJ); whereas the asthmatic control (AC) group and non-asthmatic control (NC) group consumed water ad libitum. In histopathological examination, no goblet cells metaplasia was observed in the HN, OJ, and GJ groups; also, intra-alveolar macrophages decreased compared with those of the AC group. Hesperetin plus naringenin significantly decreased subepithelial fibrosis, smooth muscle hypertrophy in airways, and lung atelectasis compared with the AC group. Also, there was a reduction of subepithelial fibrosis in airways in OJ and GJ groups compared with AC group, but it was not noticed in OGJ group. In bronchoalveolar lavage fluid, macrophages numbers decreased in OJ and OGJ groups, whereas eosinophil numbers were increased in OJ group compared with NC group. Our finding revealed that hesperetin plus naringenin ameliorate airway structural remodeling more than orange juice and grapefruit juice in murine model of HDM-induced asthma. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd

Muscarinic M3 receptor stimulation increases cigarette smoke-induced IL-8 secretion by human airway smooth muscle cells

Acetylcholine is the primary parasympathetic neurotransmitter in the airways and is known to cause bronchoconstriction and mucus secretion. Recent findings suggest that acetylcholine also regulates aspects of remodelling and inflammation through its action on muscarinic receptors. In the present study, we aimed to determine the effects of muscarinic receptor stimulation on cytokine production by human airway smooth muscle cells (primary and immortalised cell lines). The muscarinic receptor agonists carbachol and methacholine both induced modest effects on basal interleukin (IL)-8 and -6 secretion, whereas the secretion of RANTES, eotaxin, vascular endothelial growth factor-A and monocyte chemoattractant protein-1 was not affected. Secretion of IL-8 and -6 was only observed in immortalised airway smooth muscle cells that. express muscarinic M3 receptors,. In these cells, methacholine also significantly augmented IL-8 secretion in, combination with cigarette smoke extract in a synergistic, manner, whereas synergistic effects on IL-6 secretion were not significant. Muscarinic M3 receptors were the primary subtype, involved in augmenting cigarette smoke extract-induced IL-8 secretion, as only tiotropium bromide and muscarinic, M3 receptor subtype selective antagonists. abrogated the effects of methacholine. Collectively, these results indicate that muscarinic M3. receptor stimulation augments cigarette smoke extract-induced cytokine produc ion by airway smooth muscle. This interaction could be of importance in patients with chronic obstructive pulmonary, disease

Pro-inflammatory mechanisms of muscarinic receptor stimulation in airway smooth muscle

Abstract Background Acetylcholine, the primary parasympathetic neurotransmitter in the airways, plays an important role in bronchoconstriction and mucus production. Recently, it has been shown that acetylcholine, by acting on muscarinic receptors, is also involved in airway inflammation and remodelling. The mechanism(s) by which muscarinic receptors regulate inflammatory responses are, however, still unknown. Methods The present study was aimed at characterizing the effect of muscarinic receptor stimulation on cytokine secretion by human airway smooth muscle cells (hASMc) and to dissect the intracellular signalling mechanisms involved. hASMc expressing functional muscarinic M2 and M3 receptors were stimulated with the muscarinic receptor agonist methacholine, alone, and in combination with cigarette smoke extract (CSE), TNF-α, PDGF-AB or IL-1β. Results Muscarinic receptor stimulation induced modest IL-8 secretion by itself, yet augmented IL-8 secretion in combination with CSE, TNF-α or PDGF-AB, but not with IL-1β. Pretreatment with GF109203X, a protein kinase C (PKC) inhibitor, completely normalized the effect of methacholine on CSE-induced IL-8 secretion, whereas PMA, a PKC activator, mimicked the effects of methacholine, inducing IL-8 secretion and augmenting the effects of CSE. Similar inhibition was observed using inhibitors of IκB-kinase-2 (SC514) and MEK1/2 (U0126), both downstream effectors of PKC. Accordingly, western blot analysis revealed that methacholine augmented the degradation of IκBα and the phosphorylation of ERK1/2 in combination with CSE, but not with IL-1β in hASMc. Conclusions We conclude that muscarinic receptors facilitate CSE-induced IL-8 secretion by hASMc via PKC dependent activation of IκBα and ERK1/2. This mechanism could be of importance for COPD patients using anticholinergics.</p