IL-17A Monoclonal Antibody Partly Reverses the Glucocorticoids Insensitivity in Mice Exposed to Ozonec

Reduction in Hippocampal Amyloid-β Peptide (Aβ) Content during Glycine-Proline-Glutamate (Gly-Pro-Glu) Co-Administration Is Associated with Changes in Inflammation and Insulin-like Growth Factor (IGF)-I Signaling

Alzheimer's disease (AD) is characterized by the deposition in the brain of senile plaques composed of amyloid-β peptides (Aβs) that increase inflammation. An endogenous peptide derived from the insulin-like growth factor (IGF)-I, glycine-proline-glutamate (GPE), has IGF-I-sensitizing and neuroprotective actions. Here, we examined the effects of GPE on Aβ levels and hippocampal inflammation generated by the intracerebroventricular infusion of Aβ25-35 for 2 weeks (300 pmol/day) in ovariectomized rats and the signaling-related pathways and levels of Aβ-degrading enzymes associated with these GPE-related effects. GPE prevented the Aβ-induced increase in the phosphorylation of p38 mitogen-activated protein kinase and the reduction in activation of signal transducer and activator of transcription 3, insulin receptor substrate-1, and Akt, as well as on interleukin (IL)-2 and IL-13 levels in the hippocampus. The functionality of somatostatin, measured as the percentage of inhibition of adenylate cyclase activity and the levels of insulin-degrading enzyme, was also preserved by GPE co-treatment. These findings indicate that GPE co-administration may protect from Aβ insult by changing hippocampal cytokine content and somatostatin functionality through regulation of leptin- and IGF-I-signaling pathways that could influence the reduction in Aβ levels through modulation of levels and/or activity of Aβ proteases.

The contribution of the WNT pathway to the therapeutic effects of montelukast in experimental murine airway inflammation induced by ovalbumin and lipopolysaccharide

The wingless/integrase-1 (WNT) pathway involved in the pathogenesis of inflammatory airway diseases has recently generated considerable research interest. Montelukast, a leukotriene receptor antagonist, provides therapeutic benefits in allergic asthma involving eosinophils. We aimed to investigate the role of the WNT pathway in the therapeutic actions of montelukast (MT) in a mixed type of allergic-acute airway inflammation model induced by ovalbumin (OVA) and lipopolysaccharide (LPS) in mice. Female mice were sensitized with intraperitoneal OVA-Al(OH)3 administration in the initiation phase and intranasal OVA followed by LPS administration in the challenge phase. The mice were divided into eight groups: control, asthmatic, and control/asthmatic treated with XAV939 (inhibitor of the canonical WNT pathway), LGK-974 (inhibitor of the secretion of WNT ligands), or MT at different doses. The inhibition of the WNT pathway prevented tracheal 5-HT and bradykinin hyperreactivity, while only the inhibition of the canonical WNT pathway partially reduced 5-HT and bradykinin contractions compared to the inflammation group. Therefore, MT treatment hindered 5-HT and bradykinin hyperreactivity associated with airway inflammation. Furthermore, MT prevented the increases in the phosphorylated GSK-3β and WNT5A levels, which had been induced by airway inflammation, in a dose-dependent manner. Conversely, the MT application caused a further increase in the fibronectin levels, while there was no significant alteration in the phosphorylation of the Smad-2 levels in the isolated lungs of the mice. The MT treatment reversed the increase in the mRNA expression levels of interleukin-17A. An increase in eosinophil and neutrophil counts was observed in bronchoalveolar lavage fluid samples obtained from the mice in the inflammation group, which was hampered by the MT treatment. The inhibition of the WNT pathway did not alter inflammatory cytokine expression or cell infiltration. The WNT pathway mediated the therapeutic effects of MT due to the inhibition of GSK-3β phosphorylation as well as the reduction of WNT5A levels in a murine airway inflammation model.

"Air That Once Was Breath" Part 2: Wildfire Smoke and Airway Disease - "Climate Change, Allergy and Immunology" Special IAAI Article Collection: Collegium Internationale Allergologicum Update 2023

BACKGROUND

Population growth and climate change have led to more frequent and larger wildfires, increasing the exposure of individuals to wildfire smoke. Notably, asthma exacerbations and allergic airway sensitization are prominent outcomes of such exposure.

SUMMARY

Key research questions relate to determining the precise impact on individuals with asthma, including the severity, duration, and long-term consequences of exacerbations. Identifying specific risk factors contributing to vulnerability, such as age, genetics, comorbidities, or environmental factors, is crucial. Additionally, reliable biomarkers for predicting severe exacerbations need exploration. Understanding the long-term health effects of repeated wildfire smoke exposures in individuals with asthma and addressing healthcare disparities are important research areas.

KEY MESSAGES

This review discusses the need for comprehensive research efforts to better grasp wildfire smoke-induced respiratory health, particularly in vulnerable populations such as farmworkers, firefighters, pregnant women, children, the elderly, and marginalized communities. Effective mitigation would require addressing the current limitations we face by supporting research aimed at a better understanding of wildfire smoke-induced airway disease.

The Dual Role of the Airway Epithelium in Asthma: Active Barrier and Regulator of Inflammation

Chronic airway inflammation is the cornerstone on which bronchial asthma arises, and in turn, chronic inflammation arises from a complex interplay between environmental factors such as allergens and pathogens and immune cells as well as structural cells constituting the airway mucosa. Airway epithelial cells (AECs) are at the center of these processes. On the one hand, they represent the borderline separating the body from its environment in order to keep inner homeostasis. The airway epithelium forms a multi-tiered, self-cleaning barrier that involves an unstirred, discontinuous mucous layer, the dense and rigid mesh of the glycocalyx, and the cellular layer itself, consisting of multiple, densely interconnected cell types. On the other hand, the airway epithelium represents an immunologically highly active tissue once its barrier has been penetrated: AECs play a pivotal role in releasing protective immunoglobulin A. They express a broad spectrum of pattern recognition receptors, enabling them to react to environmental stressors that overcome the mucosal barrier. By releasing alarmins-proinflammatory and regulatory cytokines-AECs play an active role in the formation, strategic orientation, and control of the subsequent defense reaction. Consequently, the airway epithelium is of vital importance to chronic inflammatory diseases, such as asthma.

Hypoxia pretreatment enhances the therapeutic potential of mesenchymal stem cells (BMSCs) on ozone-induced lung injury in rats

Ozone (O₃) gas is a double-sided weapon. It provides a shield that protects life on earth from the harmful ultraviolet (UV) rays, but ground-level O₃ is considered an urban air pollutant. So, a rat model of chronic O₃ inhalation was established to assess the biochemical and morphological alterations in the lung tissue and to investigate the ameliorative effects of bone marrow-derived mesenchymal stem cells (BMSCs) with or without hypoxia pre-treatment. Forty-two adult male albino rats were divided into four groups: control, ozone-exposed, normoxic BMSC-treated, and hypoxic BMSC-treated groups. Lung tissue sections were processed for light and electron microscope examination, immunohistochemical staining for caspase 3, and iNOS. Quantitative real-time PCR for IL-1α, IL-17, TNF-α, and Nrf2 mRNA gene expression were also performed. Chronic O₃ exposure caused elevated inflammatory cytokines and decreased antioxidant Nrf2 mRNA expression. Marked morphological alterations with increased collagen deposition and elevated apoptotic markers and iNOS were evident. BMSC treatment showed immunomodulatory (decreased inflammatory cytokine gene expression), antioxidant (increased Nrf2 expression and decreased iNOS), and anti-apoptotic (decreased caspase3 expression) effects. Consequently, ameliorated lung morphology with diminished collagen deposition was observed. Hypoxia pretreatment enhanced BMSC survival by MTT assay. It also augmented the previously mentioned effects of BMSCs on the lung tissue as proved by statistical analysis. Lung morphology was similar to that of control group. In conclusion, hypoxia pretreatment represents a valuable intervention to enhance the effects of MSCs on chronic lung injury.

Potential Role of Mast Cells in Regulating Corticosteroid Insensitivity in Severe Asthma

The mechanisms driving corticosteroid insensitivity in asthma are still unclear although evidence points toward a potential role of lung mast cells. Indeed, a number of in vitro studies using various cell types showed that different mediators produced by activated mast cells, including cytokines, have the capacity to interfere with the therapeutic action of corticosteroids. In patients with severe allergic refractory asthma, the anti-IgE monoclonal antibody (mAb), Omalizumab, has been shown to be associated with a marked reduction in inhaled and systemic use of corticosteroids, further suggesting a key role of mast cells in the poor response of patients to these drugs. The present chapter will discuss the possible underlying mechanisms by which mast cells could contribute to reducing corticosteroid sensitivity seen in patients with severe asthma.

Ozone-Induced Oxidative Stress, Neutrophilic Airway Inflammation, and Glucocorticoid Resistance in Asthma

Despite recent advances in using biologicals that target Th2 pathways, glucocorticoids form the mainstay of asthma treatment. Asthma morbidity and mortality remain high due to the wide variability of treatment responsiveness and complex clinical phenotypes driven by distinct underlying mechanisms. Emerging evidence suggests that inhalation of the toxic air pollutant, ozone, worsens asthma by impairing glucocorticoid responsiveness. This review discusses the role of oxidative stress in glucocorticoid resistance in asthma. The underlying mechanisms point to a central role of oxidative stress pathways. The primary data source for this review consisted of peer-reviewed publications on the impact of ozone on airway inflammation and glucocorticoid responsiveness indexed in PubMed. Our main search strategy focused on cross-referencing "asthma and glucocorticoid resistance" against "ozone, oxidative stress, alarmins, innate lymphoid, NK and γδ T cells, dendritic cells and alveolar type II epithelial cells, glucocorticoid receptor and transcription factors". Recent work was placed in the context from articles in the last 10 years and older seminal research papers and comprehensive reviews. We excluded papers that did not focus on respiratory injury in the setting of oxidative stress. The pathways discussed here have however wide clinical implications to pathologies associated with inflammation and oxidative stress and in which glucocorticoid treatment is essential.

The Role of Neutrophils in the Pathophysiology of Asthma in Humans and Horses

Asthma is a common and debilitating chronic airway disease that affects people and horses of all ages worldwide. While asthma in humans most commonly involves an excessive type 2 immune response and eosinophilic inflammation, neutrophils have also been recognized as key players in the pathophysiology of asthma, including in the severe asthma phenotype where neutrophilic inflammation predominates. Severe equine asthma syndrome (sEAS) features prominent neutrophilic inflammation and has been increasingly used as a naturally occurring animal model for the study of human neutrophilic asthma. This comparative review examines the recent literature in order to explore the role of neutrophil inflammatory functions in the pathophysiology and immunology of asthma in humans and horses.

Ozone Inhalation Attenuated the Effects of Budesonide on Aspergillus fumigatus-Induced Airway Inflammation and Hyperreactivity in Mice

Inhaled glucocorticoids form the mainstay of asthma treatment because of their anti-inflammatory effects in the lung. Exposure to the air pollutant ozone (O₃) exacerbates chronic airways disease. We and others showed that presence of the epithelial-derived surfactant protein-D (SP-D) is important in immunoprotection against inflammatory changes including those induced by O₃ inhalation in the airways. SP-D synthesis requires glucocorticoids. We hypothesized here that O₃ exposure impairs glucocorticoid responsiveness (including SP-D production) in allergic airway inflammation. The effects of O₃ inhalation and glucocorticoid treatment were studied in a mouse model of allergic asthma induced by sensitization and challenge with Aspergillus fumigatus (Af) in vivo. The role of O₃ and glucocorticoids in regulation of SP-D expression was investigated in A549 and primary human type II alveolar epithelial cells in vitro. Budesonide inhibited airway hyperreactivity, eosinophil counts in the lung and bronchoalveolar lavage (BAL) and CCL11, IL-13, and IL-23p19 release in the BAL of mice sensitized and challenged with Af (p < 0.05). The inhibitory effects of budesonide were attenuated on inflammatory changes and were completely abolished on airway hyperreactivity after O₃ exposure of mice sensitized and challenged with Af. O₃ stimulated release of pro-neutrophilic mediators including CCL20 and IL-6 into the airways and impaired the inhibitory effects of budesonide on CCL11, IL-13 and IL-23. O₃ also prevented budesonide-induced release of the immunoprotective lung collectin SP-D into the airways of allergen-challenged mice. O₃ had a bi-phasic direct effect with early (<12 h) inhibition and late (>48 h) activation of SP-D mRNA (sftpd) in vitro. Dexamethasone and budesonide induced sftpd transcription and translation in human type II alveolar epithelial cells in a glucocorticoid receptor and STAT3 (an IL-6 responsive transcription factor) dependent manner. Our study indicates that O₃ exposure counteracts the effects of budesonide on airway inflammation, airway hyperreactivity, and SP-D production. We speculate that impairment of SP-D expression may contribute to the acute O₃-induced airway inflammation. Asthmatics exposed to high ambient O₃ levels may become less responsive to glucocorticoid treatment during acute exacerbations.

Transcriptional Effects of Ozone and Impact on Airway Inflammation

Epidemiological and challenge studies in healthy subjects and in individuals with asthma highlight the health impact of environmental ozone even at levels considered safe. Acute ozone exposure in man results in sputum neutrophilia in 30% of subjects particularly young children, females, and those with ongoing cardiopulmonary disease. This may be associated with systemic inflammation although not in all cases. Chronic exposure amplifies these effects and can result in the formation of asthma-like symptoms and immunopathology. Asthmatic patients who respond to ozone (responders) induce a greater number of genes in bronchoalveolar (BAL) macrophages than healthy responders with up-regulation of inflammatory and immune pathways under the control of cytokines and chemokines and the enhanced expression of remodeling and repair programmes including those associated with protease imbalances and cell-cell adhesion. These pathways are under the control of several key transcription regulatory factors including nuclear factor (NF)-κB, anti-oxidant factors such as nuclear factor (erythroid-derived 2)-like 2 NRF2, the p38 mitogen activated protein kinase (MAPK), and priming of the immune system by up-regulating toll-like receptor (TLR) expression. Murine and cellular models of acute and chronic ozone exposure recapitulate the inflammatory effects seen in humans and enable the elucidation of key transcriptional pathways. These studies emphasize the importance of distinct transcriptional networks in driving the detrimental effects of ozone. Studies indicate the critical role of mediators including IL-1, IL-17, and IL-33 in driving ozone effects on airway inflammation, remodeling and hyperresponsiveness. Transcription analysis and proof of mechanisms studies will enable the development of drugs to ameliorate the effects of ozone exposure in susceptible individuals.