Cysteinyl leukotriene D4 (LTD4) promotes airway epithelial cell inflammation and remodelling

Dysregulation of lipid mediators in patients with frequent exacerbations of COPD

Introduction

Specialised pro-resolving mediators (SPMs) are endogenously produced lipid mediators (LMs) that regulate the propagation of inflammation and promote tissue repair. We hypothesised that SPM production is dysregulated in COPD and is associated with disease severity, defined by patients with stable COPD (no exacerbations) versus patients with frequent exacerbations.

Methods

LMs were measured in plasma samples from patients with COPD (stable patients and patients with frequent exacerbations) and from healthy controls, matched for age, sex and body mass index, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The LM profiles of controls were compared with those of stable COPD patients, and the LM profiles of stable COPD patients were compared with those of COPD patients with frequent exacerbations. We explored whether or not there was an association between LM profile and ever having a severe COPD exacerbation over 4.1 years of follow-up. Data are presented as mean±sem in pg·mL-1 for LMs, or mean±sd.

Results

49 stable COPD patients had increased levels of pro-inflammatory mediators and some SPMs, compared with 28 controls (prostaglandin (PG)D2: 13.97±2.44 versus 0.53±0.13; p<0.001; lipoxins: 226.83±23.84 versus 59.84±20.25; p<0.01, respectively). 52 patients with frequent exacerbations had lower levels of PGD2 (3.07±0.97 versus 13.97±2.44; p<0.01) and SPMs (D-resolvins: 8.73±1.25 versus 34.53±8.95; p<0.01; lipoxins: 53.93±9.23 versus 226.83±23.84; p<0.01) than stable COPD patients, despite having a higher neutrophil count (5.28±2.16×109 L-1 versus 4.28±1.60×109 L-1; p=0.004). Among patients with frequent exacerbations, D-resolvin levels were independently inversely associated with occurrence of severe exacerbation (OR 0.88, 95% confidence interval (CI) 0.79-0.97; p=0.03) during follow-up.

Conclusion

These findings demonstrate distinct LM profiles of stable COPD patients and patients with frequent exacerbations. In those with exacerbations, D-resolvins were downregulated, compared with stable COPD patients, and associated with future risk of severe exacerbations during follow-up. Further work is needed to understand these findings.

Oxylipin Profiling of Airway Structural Cells Is Unique and Modified by Relevant Stimuli

Oxylipins, diverse lipid mediators derived from fatty acids, play key roles in respiratory physiology, but the contribution of lung structural cells to this diverse profile is not well understood. This study aimed to characterize the oxylipin profiles of airway smooth muscle (ASM), lung fibroblasts (HLF), and epithelial (HBE) cells and define how they shift when they are exposed to stimuli related to contractility, fibrosis, and inflammation. Using HPLC-MS/MS, 162 oxylipins were measured in baseline media from cultured human ASM, HLF, and HBE cells as well as after stimulation with modulators of contractility and central regulators of fibrosis/inflammation. At the baseline, ASM and HLF cells had the most similar oxylipin profiles, dominated by oxylipins from cytochrome P450 (CYP450) epoxygenase metabolites. TGFβ stimulation of HLF suppressed CYP450-derived oxylipins, while ASM stimulation increased prostaglandin production. HBE showed the most distinct baseline profile enriched with cyclooxygenase (COX)-derived oxylipins. TGFβ stimulation of HBE increased the level of several oxylipins from CYP450 epoxygenases. These findings highlight the importance of CYP450 oxylipins, which are relatively unexplored in the context of respiratory physiology. By resolving these oxylipin profiles, we enable future respiratory research to understand the function of these oxylipins in regulating physiology, especially in the context of modifying contraction and inflammation.

Effects of oral montelukast on pulmonary function and clinical symptoms in acute asthma exacerbations: a randomized, double-blind, placebo-controlled trial

Introduction

Montelukast is a leukotriene receptor antagonist that helps treat chronic asthma and allergic rhinitis by reducing inflammation and bronchoconstriction. However, oral montelukast's effectiveness in managing acute asthma attacks has yet to be completely identified.

Methods

This randomized, double-blind, placebo-controlled trial investigated the efficacy of oral montelukast in acute exacerbations of asthma. Seventy patients between 18 and 65 years of age with a primary diagnosis of asthma attack were included in the study and were randomly assigned to receive 10 mg of montelukast orally daily or placebo. Symptoms, signs, forced expiratory volume in 1 second (FEV1), and peak expiratory flow rate (PEFR) were evaluated.

Results

Our findings showed a statistically significant difference between montelukast and placebo regarding FEV1 (78.05 ± 7.84 vs. 72.05 ± 12.00, P = 0.016), PEFR (322.86 ± 28.95 vs. 290.86 ± 44.21, P = 0.003), and wheezing (P = 0.022) on the fifth day of treatment. Additionally, FEV1 and PEFR values were compared in two subgroups of patients, ICS users (ICSU) and non-ICS users (NICSU), in both the montelukast and placebo groups. In the montelukast group, while PEFR improved significantly for day 5 in both the ICSU (P = 0.007) and NICSU (P = 0.027) subgroups, FEV1 only improved in the ICSU (P = 0.009) subgroup compared to placebo.

Conclusion

The present study demonstrated that oral montelukast administered in acute asthma exacerbation could lead to better values of PEFR and FEV1 on pulmonary function and improvement of wheezing in terms of symptoms.

Naringenin attenuated airway cilia structural and functional injury induced by cigarette smoke extract via IL-17 and cAMP pathways

BACKGROUND

Cigarette smoke impairs mucociliary clearance via mechanisms such as inflammatory response and oxidative injury, which in turn induces various respiratory diseases. Naringenin, a naturally occurring flavonoid in grapes and grapefruit, has exhibited pharmacological properties such as anti-inflammatory, expectorant, and antioxidant properties. However, it is still unclear whether naringenin protects airway cilia from injury caused by cigarette smoke.

PURPOSE

This study aimed to investigate the effect of naringenin on cigarette smoke extract (CSE)-induced structural and functional abnormalities in airway cilia and highlight the potential regulatory mechanism.

METHODS

Initially, network pharmacology was used to predict the mechanism of action of naringenin in ciliary disease. Next, HE staining, immunofluorescence, TEM, qRT-PCR, western blot, and ELISA were performed to assess the effects of naringenin on airway cilia in tracheal rings and air-liquid interface (ALI) cultures of Sprague Dawley rats after co-exposure to CSE (10% or 20%) and naringenin (0, 25, 50, 100 μM) for 24 h. Finally, transcriptomics and molecular biotechnology methods were conducted to elucidate the mechanism by which naringenin protected cilia from CSE-induced damage in ALI cultures.

RESULTS

The targets of ciliary diseases regulated by naringenin were significantly enriched in inflammation and oxidative stress pathways. Also, the CSE decreased the number of cilia in the tracheal rings and ALI cultures and reduced the ciliary beat frequency (CBF). However, naringenin prevented CSE-induced cilia damage via mechanisms such as the downregulation of cilia-related genes (e.g., RFX3, DNAI1, DNAH5, IFT88) and ciliary marker proteins such as DNAI2, FOXJ1, and β-tubulin IV, the upregulation of inflammatory factors (e.g., IL-6, IL-8, IL-13), ROS and MDA. IL-17 signaling pathway might be involved in the protective effect of naringenin on airway cilia. Additionally, the cAMP signaling pathway might also be related to the enhancement of CBF by naringenin.

CONCLUSION

In this study, we first found that naringenin reduces CSE-induced structural disruption of airway cilia in part via modulation of the IL-17 signaling pathway. Furthermore, we also found that naringenin enhances CBF by activating the cAMP signaling pathway. This is the first report to reveal the beneficial effects of naringenin on airway cilia and the potential underlying mechanisms.

Impact of obesity on airway remodeling in asthma: pathophysiological insights and clinical implications

The prevalence of obesity among asthma patients has surged in recent years, posing a significant risk factor for uncontrolled asthma. Beyond its impact on asthma severity and patients' quality of life, obesity is associated with reduced lung function, increased asthma exacerbations, hospitalizations, heightened airway hyperresponsiveness, and elevated asthma-related mortality. Obesity may lead to metabolic dysfunction and immune dysregulation, fostering chronic inflammation characterized by increased pro-inflammatory mediators and adipocytokines, elevated reactive oxygen species, and reduced antioxidant activity. This chronic inflammation holds the potential to induce airway remodeling in individuals with asthma and obesity. Airway remodeling encompasses structural and pathological changes, involving alterations in the airway's epithelial and subepithelial layers, hyperplasia and hypertrophy of airway smooth muscle, and changes in airway vascularity. In individuals with asthma and obesity, airway remodeling may underlie heightened airway hyperresponsiveness and increased asthma severity, ultimately contributing to the development of persistent airflow limitation, declining lung function, and a potential increase in asthma-related mortality. Despite efforts to address the impact of obesity on asthma outcomes, the intricate mechanisms linking obesity to asthma pathophysiology, particularly concerning airway remodeling, remain incompletely understood. This comprehensive review discusses current research investigating the influence of obesity on airway remodeling, to enhance our understanding of obesity's role in the context of asthma airway remodeling.

Role of transforming growth factor-β in airway remodelling in bronchiolitis obliterans

Airway remodelling is the main pathological mechanism of bronchiolitis obliterans (BO). Several studies have found that transforming growth factor-β (TGF-β) expression is increased in BO during airway remodelling, where it plays an important role in various biological processes by binding to its receptor complex to activate multiple signalling proteins and pathways. This review examines the role of TGF-β in airway remodelling in BO and its potential as a therapeutic target, highlighting the mechanisms of TGF-β activation and signalling, cellular targets of TGF-β actions, and research progress in TGF-β signalling and TGF-β-mediated processes.

Cigarette smoke induces epithelial-to-mesenchymal transition, stemness, and metastasis in lung adenocarcinoma cells via upregulated RUNX-2/galectin-3 pathway

AIMS

An elevated level of galectin-3, a carbohydrate-binding lectin implicated in tumorigenesis, metastasis, and epithelial-mesenchymal transition (EMT), has been found in cigarette smokers. However, the regulation of its expression and role in the pathogenesis of CS-induced EMT and lung cancer metastasis is unclear. Here, we have investigated the mechanism of CS-induced and galectin-3-mediated EMT in airway epithelial cells (AECs).

MAIN METHODS

A549 adenocarcinoma cells and primary small airway epithelial cells cultured on an air-liquid interface (ALI) were exposed to cigarette smoke extract (CSE), and MTT, trypan blue, migration, invasion, tumor spheroid and colony formation assays were performed to assess EMT phenotype. Immunoblotting was performed to assess EMT and stemness markers and other regulatory proteins.

KEY FINDINGS

CSE exposure affected cell survival and morphology, migration, invasion, and clonogenicity of AECs, which were concomitant with an increase in the expression of EMT markers, galectin-3, and runt-related transcription factor-2 (RUNX-2), an osteogenic transcription factor and upstream regulator of galectin-3. Chemical inhibition or silencing of RUNX-2 downregulated galectin-3 and modulated EMT marker expression, migration, invasion, and clonogenicity in CSE-exposed AECs. Recombinant human galectin-3 also induced EMT and stemness-associated changes in the AECs, and GB1107, a galectin-3 inhibitor, ameliorated these changes. Further, CSE-induced intracellular ROS enabled an increase in RUNX-2 and galectin-3 expression, which were reversed by n-acetyl-cysteine.

SIGNIFICANCE

These results provide a novel mechanistic insight into CSE-induced EMT via RUNX-2/galectin-3 axis mediated through ROS, which promoted EMT-associated changes, including invasion, migration, and stemness in AECs, which could be implicated in CS-induced lung cancer progression.

Pediatric obesity and severe asthma: Targeting pathways driving inflammation

Asthma affects more than 300 million people of all ages worldwide, including about 10-15% of school-aged children, and its prevalence is increasing. Severe asthma (SA) is a particular and rare phenotype requiring treatment with high-dose inhaled corticosteroids plus a second controller and/or systemic glucocorticoid courses to achieve symptom control or remaining "uncontrolled" despite this therapy. In SA, other diagnoses have been excluded, and potential exacerbating factors have been addressed. Notably, obese asthmatics are at higher risk of developing SA. Obesity is both a major risk factor and a disease modifier of asthma in children and adults: two main "obese asthma" phenotypes have been described in childhood with high or low levels of Type 2 inflammation biomarkers, respectively, the former characterized by early onset and eosinophilic inflammation and the latter by neutrophilic inflammation and late-onset. Nevertheless, the interplay between obesity and asthma is far more complex and includes obese tissue-driven inflammatory pathways, mechanical factors, comorbidities, and poor response to corticosteroids. This review outlines the most recent findings on SA in obese children, particularly focusing on inflammatory pathways, which are becoming of pivotal importance in order to identify selective targets for specific treatments, such as biological agents.

Baicalin Ameliorates Radiation-Induced Lung Injury by Inhibiting the CysLTs/CysLT1 Signaling Pathway

Objective

Radiation-induced lung injury (RILI) is a common complication of radiotherapy for thoracic tumors. This study investigated the alleviating effect of baicalin (BA) on RILI and its possible mechanism.

Methods

RILI model was established by chest irradiation (IR) of C57BL/6 mice for 16 weeks. Different concentrations of BA were administered, and dexamethasone (DXM) was used as a positive control. Then, the lung pathological changes were observed by HE and Masson staining. The levels of TGF-β, TNF-α, IL-1β, IL-6, CysLT, LTC4, and LTE4 were measured by ELISA. The CysLT1 expression was detected by qPCR, immunohistochemistry, and western blot. Type II AEC cells were pretreated with LTD-4 to establish the RILI cell model and intervened with different concentrations of BA. Then, the collagen I protein level was measured by ELISA. The CysLT1 and α-SMA expression were detected by qPCR, immunofluorescence, and western blot.

Results

BA could effectively improve lung histopathological changes and pulmonary fibrosis. In vivo, BA could inhibit the levels of TGF-β, TNF-α, IL-1β, and IL-6 and reduce the levels of CysLT, LTC4, and LTE4. In vitro, different concentrations of LTD4 could reduce the viability of type II AEC cells, which could be reversed by the administration of different concentrations of BA. In addition, BA could reduce CysLT1 mRNA, as well as CysLT1 and α-SMA protein levels in vitro and in vivo.

Conclusion

BA attenuated lung inflammation and pulmonary fibrosis by inhibiting the CysLTs/CysLT1 pathway, thereby protecting against RILI.

Montelukast, an Antagonist of Cysteinyl Leukotriene Signaling, Impairs Burn Wound Healing

BACKGROUND

Burns are severe injuries often associated with impaired wound healing. Impaired healing is caused by multiple factors, including dysregulated inflammatory responses at the wound site. Interestingly, montelukast, an antagonist for cysteinyl leukotrienes and U.S. Food and Drug Administration approved for treatment of asthma and allergy, was previously shown to enhance healing in excision wounds and to modulate local inflammation.

METHODS

In this study, the authors examined the effect of montelukast on wound healing in a mouse model of scald burn injury. Burn wound tissues isolated from montelukast- and vehicle-treated mice at various times after burn injury were analyzed for wound areas ( n = 34 to 36), reepithelialization ( n = 14), inflammation ( n = 8 to 9), and immune cell infiltration ( n = 3 to 6) and proliferation ( n = 7 to 8).

RESULTS

In contrast to previously described beneficial effects in excision wounds, this study shows that montelukast delays burn wound healing by impairing the proliferation of keratinocytes and endothelial cells. This occurs largely independently of inflammatory responses at the wound site, suggesting that montelukast impairs specifically the proliferative phase of wound healing in burns. Wound healing rates in mice in which leukotrienes are not produced were not affected by montelukast.

CONCLUSION

Montelukast delays wound healing mainly by reducing the proliferation of local cells after burn injury.

CLINICAL RELEVANCE STATEMENT

Although additional and clinical studies are necessary, our study suggests that burn patients who are on montelukast may exhibit delayed healing, necessitating extra observation.

Role of Obesity in Inflammation and Remodeling of Asthmatic Airway

Obesity is considered as an important risk factor for the onset of asthma and plays a key role in enhancing the disease's severity. Obese asthmatic individuals represent a distinct phenotype of asthma that is associated with additional symptoms, more severe exacerbation, decreased response to standard medication, and poor quality of life. Obesity impairs the function of the lung airway in asthmatic individuals, leading to increased inflammation and severe remodeling of the bronchus; however, the molecular events that trigger such changes are not completely understood. In this manuscript, we review the current findings from studies that focused on understanding the role of obesity in modulating the functions of airway cells, including lung immune cells, epithelial cells, smooth muscle cells, and fibroblasts, leading to airway inflammation and remodeling. Finally, the review sheds light on the current knowledge of different therapeutic approaches for treating obese asthmatic individuals. Given the fact that the prevalence of asthma and obesity has been increasing rapidly in recent years, it is necessary to understand the molecular mechanisms that play a role in the disease pathophysiology of obese asthmatic individuals for developing novel therapies.

Pharmacogenomics of Hypersensitivity to Non-steroidal Anti-inflammatory Drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are extensively prescribed in daily clinical practice. NSAIDs are the main cause of drug hypersensitivity reactions all over the world. The inhibition of cyclooxygenase enzymes by NSAIDs can perpetuate arachidonic acid metabolism, shunting to the 5-lipoxygenase pathway and its downstream inflammatory process. Clinical phenotypes of NSAID hypersensitivity are diverse and can be classified into cross-reactive or selective responses. Efforts have been made to understand pathogenic mechanisms, in which, genetic and epigenetic backgrounds are implicated in various processes of NSAID-induced hypersensitivity reactions. Although there were some similarities among patients, several genetic polymorphisms are distinct in those exhibiting respiratory or cutaneous symptoms. Moreover, the expression levels, as well as the methylation status of genes related to immune responses were demonstrated to be involved in NSAID-induced hypersensitivity reactions. There is still a lack of data on delayed type reactions. Further studies with a larger sample size, which integrate different genetic pathways, can help overcome current limitations of gen etic/epigenetic studies, and provide valuable information on NSAID hypersensitivity reactions.