Rediscovering the Therapeutic Potential of Agarwood in the Management of Chronic Inflammatory Diseases.

The inflammatory response is a central aspect of the human immune system that acts as a defense mechanism to protect the body against infections and injuries. A dysregulated inflammatory response is a major health concern, as it can disrupt homeostasis and lead to a plethora of chronic inflammatory conditions. These chronic inflammatory diseases are one of the major causes of morbidity and mortality worldwide and the need for them to be managed in the long term has become a crucial task to alleviate symptoms and improve patients' overall quality of life. Although various synthetic anti-inflammatory agents have been developed to date, these medications are associated with several adverse effects that have led to poor therapeutic outcomes. The hunt for novel alternatives to modulate underlying chronic inflammatory processes has unveiled nature to be a plentiful source. One such example is agarwood, which is a valuable resinous wood from the trees of Aquilaria spp. Agarwood has been widely utilized for medicinal purposes since ancient times due to its ability to relieve pain, asthmatic symptoms, and arrest vomiting. In terms of inflammation, the major constituent of agarwood, agarwood oil, has been shown to possess multiple bioactive compounds that can regulate molecular mechanisms of chronic inflammation, thereby producing a multitude of pharmacological functions for treating various inflammatory disorders. As such, agarwood oil presents great potential to be developed as a novel anti-inflammatory therapeutic to overcome the drawbacks of existing therapies and improve treatment outcomes. In this review, we have summarized the current literature on agarwood and its bioactive components and have highlighted the potential roles of agarwood oil in treating various chronic inflammatory diseases.

Extracellular Matrix Oxidised by the Granulocyte Oxidants Hypochlorous and Hypobromous Acid Reduces Lung Fibroblast Adhesion and Proliferation In Vitro.

Chronic airway inflammation and oxidative stress play crucial roles in the pathogenesis of chronic inflammatory lung diseases, with airway inflammation being a key driving mechanism of oxidative stress in the lungs. Inflammatory responses in the lungs activate neutrophils and/or eosinophils, leading to the generation of hypohalous acids (HOX). These HOX oxidants can damage the extracellular matrix (ECM) structure and may influence cell-ECM interactions. The ECM of the lung provides structural, mechanical, and biochemical support for cells and determines the airway structure. One of the critical cells in chronic respiratory disease is the fibroblast. Thus, we hypothesised that primary human lung fibroblasts (PHLF) exposed to an oxidised cell-derived ECM will result in functional changes to the PHLF. Here, we show that PHLF adhesion, proliferation, and inflammatory cytokine secretion is affected by exposure to HOX-induced oxidisation of the cell-derived ECM. Furthermore, we investigated the impact on fibroblast function from the presence of haloamines in the ECM. Haloamines are chemical by-products of HOX and, like the HOX, haloamines can also modify the ECM. In conclusion, this study revealed that oxidising the cell-derived ECM might contribute to functional changes in PHLF, a key mechanism behind the pathogenesis of inflammatory lung diseases.

Recent trends of NFκB decoy oligodeoxynucleotide-based nanotherapeutics in lung diseases.

Nuclear factor κB (NFκB) is a unique protein complex that plays a major role in lung inflammation and respiratory dysfunction. The NFκB signaling pathway, therefore becomes an avenue for the development of potential pharmacological interventions, especially in situations where chronic inflammation is often constitutively active and plays a key role in the pathogenesis and progression of the disease. NFκB decoy oligodeoxynucleotides (ODNs) are double-stranded and carry NFκB binding sequences. They prevent the formation of NFκB-mediated inflammatory cytokines and thus have been employed in the treatment of a variety of chronic inflammatory diseases. However, the systemic administration of naked decoy ODNs restricts their therapeutic effectiveness because of their poor pharmacokinetic profile, instability, degradation by cellular enzymes and their low cellular uptake. Both structural modification and nanotechnology have shown promising results in enhancing the pharmacokinetic profiles of potent therapeutic substances and have also shown great potential in the treatment of respiratory diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. In this review, we examine the contribution of NFκB activation in respiratory diseases and recent advancements in the therapeutic use of decoy ODNs. In addition, we also highlight the limitations and challenges in use of decoy ODNs as therapeutic molecules, cellular uptake of decoy ODNs, and the current need for novel delivery systems to provide efficient delivery of decoy ODNs. Furthermore, this review provides a common platform for discussion on the existence of decoy ODNs, as well as outlining perspectives on the latest generation of delivery systems that encapsulate decoy ODNs and target NFκB in respiratory diseases.

BET proteins are associated with the induction of small airway fibrosis in COPD.

RATIONALE: In COPD, small airway fibrosis occurs due to increased extracellular matrix (ECM) deposition in and around the airway smooth muscle (ASM) layer. Studies of immune cells and peripheral lung tissue have shown that epigenetic changes occur in COPD but it is unknown whether airway mesenchymal cells are reprogrammed. OBJECTIVES: Determine if COPD ASM cells have a unique epigenetic response to profibrotic cytokine transforming growth factor ß1 (TGF-ß1). METHODS: Primary human ASM cells from COPD and non-COPD smoking patients were stimulated with TGF-ß1. Gene array analysis performed to identify differences in ECM expression. Airway accumulation of collagen 15α1 and tenascin-C proteins was assessed. Aforementioned ASM cells were stimulated with TGF-ß1 ± epigenetic inhibitors with qPCR quantification of COL15A1 and TNC. Global histone acetyltransferase (HAT) and histone deacetylase (HDAC) activity were assessed. chromatin immunoprecipitation (ChIP)-qPCR for histone H3 and H4 acetylation at COL15A1 and TNC promoters was carried out. Effects of bromoterminal and extraterminal domain (BET) inhibitor JQ1(+) on expression and acetylation of ECM target genes were assessed. MEASUREMENTS AND MAIN RESULTS: COPD ASM show significantly higher COL15A1 and TNC expression in vitro and the same trend for higher levels of collagen 15α1 and tenascin-c deposited in COPD airways in vivo. Epigenetic screening indicated differential response to HDAC inhibition. ChIP-qPCR revealed histone H4 acetylation at COL15A1 and TNC promoters in COPD ASM only. ChIP-qPCR found JQ1(+) pretreatment significantly abrogated TGF-ß1 induced histone H4 acetylation at COL15A1 and TNC. CONCLUSIONS: BET protein binding to acetylated histones is important in TGF-ß1 induced expression of COL15A1 and TNC and maintenance of TGF-ß1 induced histone H4 acetylation in cell progeny.

Targeting eosinophils in respiratory diseases: Biological axis, emerging therapeutics and treatment modalities.

Eosinophils are bi-lobed, multi-functional innate immune cells with diverse cell surface receptors that regulate local immune and inflammatory responses. Several inflammatory and infectious diseases are triggered with their build up in the blood and tissues. The mobilization of eosinophils into the lungs is regulated by a cascade of processes guided by Th2 cytokine generating T-cells. Recruitment of eosinophils essentially leads to a characteristic immune response followed by airway hyperresponsiveness and remodeling, which are hallmarks of chronic respiratory diseases. By analysing the dynamic interactions of eosinophils with their extracellular environment, which also involve signaling molecules and tissues, various therapies have been invented and developed to target respiratory diseases. Having entered clinical testing, several eosinophil targeting therapeutic agents have shown much promise and have further bridged the gap between theory and practice. Moreover, researchers now have a clearer understanding of the roles and mechanisms of eosinophils. These factors have successfully assisted molecular biologists to block specific pathways in the growth, migration and activation of eosinophils. The primary purpose of this review is to provide an overview of the eosinophil biology with a special emphasis on potential pharmacotherapeutic targets. The review also summarizes promising eosinophil-targeting agents, along with their mechanisms and rationale for use, including those in developmental pipeline, in clinical trials, or approved for other respiratory disorders.

Sexually dimorphic production of interleukin-6 in respiratory disease.

Diverging susceptibility and severity in respiratory diseases is prevalent between males and females. Sex hormones have inconclusively been attributed as the cause of these differences, however, strong evidence exists promoting genetic factors leading to sexual dimorphism. As such, we investigate differential proinflammatory cytokine (interleukin (IL)-6 and CXCL8) release from TNF-α stimulated primary human lung fibroblasts in vitro. We present, for the first time, in vitro evidence supporting clinical findings of differential production of IL-6 between males and females across various respiratory diseases. IL-6 was found to be produced approximately two times more from fibroblasts derived from females compared to males. As such we demonstrate sexual dimorphism in cytokine production of IL-6 outside the context of biological factors in the human body. As such, our data highlight that differences exist between males and females in the absence of sex hormones. We, for the first time, demonstrate inherent in vitro differences exist between males and females in pulmonary fibroblasts.

Crucial role for lung iron level and regulation in the pathogenesis and severity of asthma.

Accumulating evidence highlights links between iron regulation and respiratory disease. Here, we assessed the relationship between iron levels and regulatory responses in clinical and experimental asthma.We show that cell-free iron levels are reduced in the bronchoalveolar lavage (BAL) supernatant of severe or mild-moderate asthma patients and correlate with lower forced expiratory volume in 1 s (FEV1). Conversely, iron-loaded cell numbers were increased in BAL in these patients and with lower FEV1/forced vital capacity (FVC) ratio. The airway tissue expression of the iron sequestration molecules divalent metal transporter 1 (DMT1) and transferrin receptor 1 (TFR1) are increased in asthma, with TFR1 expression correlating with reduced lung function and increased Type-2 (T2) inflammatory responses in the airways. Furthermore, pulmonary iron levels are increased in a house dust mite (HDM)-induced model of experimental asthma in association with augmented Tfr1 expression in airway tissue, similar to human disease. We show that macrophages are the predominant source of increased Tfr1 and Tfr1+ macrophages have increased Il13 expression. We also show that increased iron levels induce increased pro-inflammatory cytokine and/or extracellular matrix (ECM) responses in human airway smooth muscle (ASM) cells and fibroblasts ex vivo and induce key features of asthma in vivo, including airway hyper-responsiveness (AHR) and fibrosis, and T2 inflammatory responses.Together these complementary clinical and experimental data highlight the importance of altered pulmonary iron levels and regulation in asthma, and the need for a greater focus on the role and potential therapeutic targeting of iron in the pathogenesis and severity of disease.

Critical role for iron accumulation in the pathogenesis of fibrotic lung disease.

Increased iron levels and dysregulated iron homeostasis, or both, occur in several lung diseases. Here, the effects of iron accumulation on the pathogenesis of pulmonary fibrosis and associated lung function decline was investigated using a combination of murine models of iron overload and bleomycin-induced pulmonary fibrosis, primary human lung fibroblasts treated with iron, and histological samples from patients with or without idiopathic pulmonary fibrosis (IPF). Iron levels are significantly increased in iron overloaded transferrin receptor 2 (Tfr2) mutant mice and homeostatic iron regulator (Hfe) gene-deficient mice and this is associated with increases in airway fibrosis and reduced lung function. Furthermore, fibrosis and lung function decline are associated with pulmonary iron accumulation in bleomycin-induced pulmonary fibrosis. In addition, we show that iron accumulation is increased in lung sections from patients with IPF and that human lung fibroblasts show greater proliferation and cytokine and extracellular matrix responses when exposed to increased iron levels. Significantly, we show that intranasal treatment with the iron chelator, deferoxamine (DFO), from the time when pulmonary iron levels accumulate, prevents airway fibrosis and decline in lung function in experimental pulmonary fibrosis. Pulmonary fibrosis is associated with an increase in Tfr1+ macrophages that display altered phenotype in disease, and DFO treatment modified the abundance of these cells. These experimental and clinical data demonstrate that increased accumulation of pulmonary iron plays a key role in the pathogenesis of pulmonary fibrosis and lung function decline. Furthermore, these data highlight the potential for the therapeutic targeting of increased pulmonary iron in the treatment of fibrotic lung diseases such as IPF. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Unique mechanisms of connective tissue growth factor regulation in airway smooth muscle in asthma: Relationship with airway remodelling.

Neovascularization, increased basal membrane thickness and increased airway smooth muscle (ASM) bulk are hallmarks of airway remodelling in asthma. In this study, we examined connective tissue growth factor (CTGF) dysregulation in human lung tissue and animal models of allergic airway disease. Immunohistochemistry revealed that ASM cells from patients with severe asthma (A) exhibited high expression of CTGF, compared to mild and non-asthmatic (NA) tissues. This finding was replicated in a sheep model of allergic airways disease. In vitro, transforming growth factor (TGF)-ß increased CTGF expression both in NA- and A-ASM cells but the expression was higher in A-ASM at both the mRNA and protein level as assessed by PCR and Western blot. Transfection of CTGF promoter-luciferase reporter constructs into NA- and A-ASM cells indicated that no region of the CTGF promoter (-1500 to +200 bp) displayed enhanced activity in the presence of TGF-ß. However, in silico analysis of the CTGF promoter suggested that distant transcription factor binding sites may influence CTGF promoter activation by TGF-ß in ASM cells. The discord between promoter activity and mRNA expression was also explained, in part, by differential post-transcriptional regulation in A-ASM cells due to enhanced mRNA stability for CTGF. In patients, higher CTGF gene expression in bronchial biopsies was correlated with increased basement membrane thickness indicating that the enhanced CTGF expression in A-ASM may contribute to airway remodelling in asthma.

Roflumilast N-Oxide in Combination with Formoterol Enhances the Antiinflammatory Effect of Dexamethasone in Airway Smooth Muscle Cells.

Roflumilast is an orally active phosphodiesterase 4 inhibitor approved for use in chronic obstructive pulmonary disease. Roflumilast N-oxide (RNO) is the active metabolite of roflumilast and has a demonstrated antiinflammatory impact in vivo and in vitro. To date, the effect of RNO on the synthetic function of airway smooth muscle (ASM) cells is unknown. We address this herein and investigate the effect of RNO on ß2-adrenoceptor-mediated, cAMP-dependent responses in ASM cells in vitro, and whether RNO enhances steroid-induced repression of inflammation. RNO (0.001-1,000 nM) alone had no effect on AMP production from ASM cells, and significant potentiation of the long-acting ß2-agonist formoterol-induced cAMP could only be achieved at the highest concentration of RNO tested (1,000 nM). At this concentration, RNO exerted a small, but not significantly different, potentiation of formoterol-induced expression of antiinflammatory mitogen-activated protein kinase phosphatase 1. Consequently, tumor necrosis factor-induced IL-8 secretion was unaffected by RNO in combination with formoterol. However, because there was the potential for phosphodiesterase 4 inhibitors and long-acting ß2-agonists to interact with corticosteroids to achieve superior antiinflammatory efficacy, we examined whether RNO, alone or in combination with formoterol, enhanced the antiinflammatory effect of dexamethasone by measuring the impact on IL-8 secretion. Although RNO alone did not significantly enhance the cytokine repression achieved with steroids, RNO in combination with formoterol significantly enhanced the antiinflammatory effect of dexamethasone in ASM cells. This was linked to increased mitogen-activated protein kinase phosphatase 1 expression in ASM cells, suggesting that a molecular mechanism is responsible for augmented antiinflammatory actions of combination therapeutic approaches that include RNO.