The Impact of Environmental Pollutants on Barrier Dysfunction in Respiratory Disease

Modulation of the Respiratory Epithelium Physiology by Flavonoids-Insights from 16HBEσcell Model

Extensive evidence indicates that the compromise of airway epithelial barrier function is closely linked to the development of various diseases, posing a significant concern for global mortality and morbidity. Flavonoids, natural bioactive compounds, renowned for their antioxidant and anti-inflammatory properties, have been used for centuries to prevent and treat numerous ailments. Lately, a growing body of evidence suggests that flavonoids can enhance the integrity of the airway epithelial barrier. The objective of this study was to investigate the impact of selected flavonoids representing different subclasses, such as kaempferol (flavonol), luteolin (flavone), and naringenin (flavanone), on transepithelial electrical resistance (TEER), ionic currents, cells migration, and proliferation of a human bronchial epithelial cell line (16HBE14σ). To investigate the effect of selected flavonoids, MTT assay, trypan blue staining, and wound healing were assessed. Additionally, transepithelial resistance and Ussing chamber measurements were applied to investigate the impact of the flavonoids on the electrical properties of the epithelial barrier. This study showed that kaempferol, luteolin, and naringenin at micromolar concentrations were not cytotoxic to 16HBE14σ cells. Indeed, in MTT tests, a statistically significant change in cell metabolic activity for luteolin and naringenin was observed. However, our experiments showed that naringenin did not affect the proliferation of 16HBE14σ cells, while the effect of kaempferol and luteolin was inhibitory. Moreover, transepithelial electrical resistance measurements have shown that all of the flavonoids used in this study improved the epithelial integrity with the slightest effect of kaempferol and the significant impact of naringenin and luteolin. Finally, our observations suggest that luteolin increases the Cl- transport through cystic fibrosis transmembrane conductance regulator (CFTR) channel. Our findings reveal that flavonoids representing different subclasses exert distinct effects in the employed cellular model despite their similar chemical structures. In summary, our study sheds new light on the diverse effects of selected flavonoids on airway epithelial barrier function, underscoring the importance of further exploration into their potential therapeutic applications in respiratory health.

Environmental factors and the incidence of pediatric epistaxis: A systematic review with meta-analysis

BACKGROUND

A growing body of literature explores environmental risk factors for pediatric epistaxis, yielding variable results. We aim to clarify these associations through a systematic review and meta-analysis.

METHODS

PubMed, Scopus, Cochrane Central Register of Control Trials, Web of Science, Medline, Google Scholars, and Embase were systematically searched up to April 2024. Eligible articles were reviewed, and the quality was assessed. A systematic review and meta-analysis was conducted to clarify correlations between the incidence of epistaxis and multiple environmental factors according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines.

RESULTS

A total of 8 studies, comprising 55,176 participants, met the inclusion criteria. The incidence of epistaxis peaked during the summer months (Proportion = 12.73 %, CI: 9.629 %-16.201 %). Significant risk factors included environmental variables elevated in the summer, including higher monthly mean temperatures, increased sunlight exposure, elevated O3 levels, and lower atmospheric pressure. In contrast, factors like mean monthly humidity, wind speed, SO2, CO, NO2, and PM-10 levels were not associated with an increased risk of epistaxis.

CONCLUSIONS

This meta-analysis underscores the significant impact of multiple environmental factors, particularly those more pronounced during the summer months, on the incidence of pediatric epistaxis.

The Effect of Green Tea Extract on Pulmonary Inflammation in Nanoparticles-Exposed Mice

SCOPE

Titanium dioxide nanoparticles (TiO2 NPs) are air pollutants that exacerbate chronic respiratory diseases such as asthma and Chronic Obstructive Pulmonary Disease (COPD) However, little is known about the mechanism underlying the antipollutant effects of green tea extract (GTE). This study evaluates the efficacy and mechanism of GTE on lung inflammation and fibrosis in mice exposed to TiO2 NPs.

METHODS AND RESULTS

The TiO2 NPs model is induced by having mice inhale TiO2 NPs, while controls receive an equivalent volume of saline. Treatment with oral GTE is initiated after TiO2 NPs inhalation and is given once daily for 4 weeks. Airway resistance and pulmonary inflammation are increased in mice exposed to TiO2 NPs. GTE treatment reduces the airway inflammation and airway resistance, and attenuates the pathological changes including lung fibrosis compared to the mice exposed to TiO2 NPs. With GTE, there are no significant increases in cytokines and immunoglobulin E (IgE) in mice exposed to TiO2 NPs. GTE inhibits matrix metalloproteinases (MMPs) and apoptotic factors induced by TiO2 NPs exposure, and these protective effects of GTE are closely related to the mitogen-activated protein kinase (MAPK) signaling pathway.

CONCLUSION

GTE modulates pulmonary inflammation in mice exposed to air pollutants, suggesting that GTE may be beneficial in respiratory diseases exacerbated by such pollutants.

Transient receptor potential vanilloid 4 channel inhibition attenuates lung ischemia-reperfusion injury in a porcine lung transplant model

OBJECTIVE

Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel important in many physiological and pathophysiological processes, including pulmonary disease. Using a murine model, we previously demonstrated that TRPV4 mediates lung ischemia-reperfusion injury, the major cause of primary graft dysfunction after transplant. The current study tests the hypothesis that treatment with a TRPV4 inhibitor will attenuate lung ischemia-reperfusion injury in a clinically relevant porcine lung transplant model.

METHODS

A porcine left-lung transplant model was used. Animals were randomized to 2 treatment groups (n = 5/group): vehicle or GSK2193874 (selective TRPV4 inhibitor). Donor lungs underwent 30 minutes of warm ischemia and 24 hours of cold preservation before left lung allotransplantation and 4 hours of reperfusion. Vehicle or GSK2193874 (1 mg/kg) was administered to the recipient as a systemic infusion after recipient lung explant. Lung function, injury, and inflammatory biomarkers were compared.

RESULTS

After transplant, left lung oxygenation was significantly improved in the TRPV4 inhibitor group after 3 and 4 hours of reperfusion. Lung histology scores and edema were significantly improved, and neutrophil infiltration was significantly reduced in the TRPV4 inhibitor group. TRPV4 inhibitor-treated recipients had significantly reduced expression of interleukin-8, high mobility group box 1, P-selectin, and tight junction proteins (occludin, claudin-5, and zonula occludens-1) in bronchoalveolar lavage fluid as well as reduced angiopoietin-2 in plasma, all indicative of preservation of endothelial barrier function.

CONCLUSIONS

Treatment of lung transplant recipients with TRPV4 inhibitor significantly improves lung function and attenuates ischemia-reperfusion injury. Thus, selective TRPV4 inhibition may be a promising therapeutic strategy to prevent primary graft dysfunction after transplant.

PM2.5 Exposure Inhibits Transepithelial Anion Short-circuit Current by Downregulating P2Y2 Receptor/CFTR Pathway

Fine particulate matter (PM2.5) can damage airway epithelial barriers. The anion transport system plays a crucial role in airway epithelial barriers. However, the detrimental effect and mechanism of PM2.5 on the anion transport system are still unclear. In this study, airway epithelial cells and ovalbumin (OVA)-induced asthmatic mice were used. In transwell model, the adenosine triphosphate (ATP)-induced transepithelial anion short-circuit current (Isc) and airway surface liquid (ASL) significantly decreased after PM2.5 exposure. In addition, PM2.5 exposure decreased the expression levels of P2Y2R, CFTR and cytoplasmic free-calcium, but ATP can increase the expressions of these proteins. PM2.5 exposure increased the levels of Th2-related cytokines of bronchoalveolar lavage fluid, lung inflammation, collagen deposition and hyperplasisa of goblet cells. Interestingly, the administration of ATP showed an inhibitory effect on lung inflammation induced by PM2.5. Together, our study reveals that PM2.5 impairs the ATP-induced transepithelial anion Isc through downregulating P2Y2R/CFTR pathway, and this process may participate in aggravating airway hyperresponsiveness and airway inflammation. These findings may provide important insights on PM2.5-mediated airway epithelial injury.

The airway epithelium: an orchestrator of inflammation, a key structural barrier and a therapeutic target in severe asthma

Asthma is a disease of heterogeneous pathology, typically characterised by excessive inflammatory and bronchoconstrictor responses to the environment. The clinical expression of the disease is a consequence of the interaction between environmental factors and host factors over time, including genetic susceptibility, immune dysregulation and airway remodelling. As a critical interface between the host and the environment, the airway epithelium plays an important role in maintaining homeostasis in the face of environmental challenges. Disruption of epithelial integrity is a key factor contributing to multiple processes underlying asthma pathology. In this review, we first discuss the unmet need in asthma management and provide an overview of the structure and function of the airway epithelium. We then focus on key pathophysiological changes that occur in the airway epithelium, including epithelial barrier disruption, immune hyperreactivity, remodelling, mucus hypersecretion and mucus plugging, highlighting how these processes manifest clinically and how they might be targeted by current and novel therapeutics.

Air pollutants contribute to epithelial barrier dysfunction and allergic diseases

Air pollution is a global problem associated with various health conditions, causing elevated rates of morbidity and mortality. Major sources of air pollutants include industrial emissions, traffic-related pollutants, and household biomass combustion, in addition to indoor pollutants from chemicals and tobacco. Various types of air pollutants originate from both human activities and natural sources. These include particulate matter, pollen, greenhouse gases, and other harmful gases. Air pollution is linked to allergic diseases, including atopic dermatitis, allergic rhinitis, allergic conjunctivitis, food allergy, and bronchial asthma. These pollutants lead to epithelial barrier dysfunction, dysbiosis, and immune dysregulation. In addition, climate change and global warming may contribute to the exacerbation and the development of allergic diseases related to air pollutants. Epigenetic changes associated with air pollutants have also been connected to the onset of allergic diseases. Furthermore, these changes can be passed down through subsequent generations, causing a higher prevalence of allergic diseases in offspring. Modulation of the aryl hydrocarbon receptor could be a valuable strategy for alleviating air pollutant-induced epidermal barrier dysfunction and atopic dermatitis. A more effective approach to preventing allergic diseases triggered by air pollutants is to reduce exposure to them. Implementing public policies aimed at safeguarding individuals from air pollutant exposure may prove to be the most efficient solution. A pressing need exists for global policy initiatives that prioritize efforts to reduce the production of air pollutants.

Interaction between mitochondrial homeostasis and barrier function in lipopolysaccharide-induced endothelial cell injury

This study aimed to investigate the effects of mitochondrial homeostasis on lipopolysaccharide (LPS)-induced endothelial cell barrier function and the mechanisms that underlie these effects. Cells were treated with LPS or oligomycin (mitochondrial adenosine triphosphate synthase inhibitor) and the mitochondrial morphology, mitochondrial reactive oxygen species (mtROS), and mitochondrial membrane potential (ΔΨm) were evaluated. Moreover, the shedding of glycocalyx-heparan sulphate (HS), the levels of HS-specific degrading enzyme heparanase (HPA), and the expression of occludin and zonula occludens (ZO-1) of Tight Junctions (TJ)s, which are mediated by myosin light chain phosphorylation (p-MLC), were assessed. Examining the changes in mitochondrial homeostasis showed that adding heparinase III, which is an exogenous HPA, can destroy the integrity of glycocalyx. LPS simultaneously increased mitochondrial swelling, mtROS, and ΔΨm. Without oligomycin effects, HS, HPA levels, and p-MLC were found to be elevated, and the destruction of occludin and ZO-1 increased. Heparinase III not only damaged the glycocalyx by increasing HS shedding but also increased mitochondrial swelling and mtROS and decreased ΔΨm. Mitochondrial homeostasis is involved in LPS-induced endothelial cell barrier dysfunction by aggravating HPA and p-MLC levels. In turn, the integrated glycocalyx protects mitochondrial homeostasis.

Air pollution and pregnancy

Increased fossil fuel usage and extreme climate change events have led to global increases in greenhouse gases and particulate matter with 99% of the world's population now breathing polluted air that exceeds the World Health Organization's recommended limits. Pregnant women and neonates with exposure to high levels of air pollutants are at increased risk of adverse health outcomes such as maternal hypertensive disorders, postpartum depression, placental abruption, low birth weight, preterm birth, infant mortality, and adverse lung and respiratory effects. While the exact mechanism by which air pollution exerts adverse health effects is unknown, oxidative stress as well as epigenetic and immune mechanisms are thought to play roles. Comprehensive, global efforts are urgently required to tackle the health challenges posed by air pollution through policies and action for reducing air pollution as well as finding ways to protect the health of vulnerable populations in the face of increasing air pollution.

Impact of the Junction Adhesion Molecule-A on Asthma

PURPOSE

Junctional adhesion molecule (JAM)-A is an immunoglobulin-like molecule that colocalizes with tight junctions (TJs) in the endothelium and epithelium. It is also found in blood leukocytes and platelets. The biological significance of JAM-A in asthma, as well as its clinical potential as a therapeutic target, are not well understood. The aim of this study was to elucidate the role of JAM-A in a mouse model of asthma, and to determine blood levels of JAM-A in asthmatic patients.

MATERIALS AND METHODS

Mice sensitized and challenged with ovalbumin (OVA) or saline were used to investigate the role of JAM-A in the pathogenesis of bronchial asthma. In addition, JAM-A levels were measured in the plasma of asthmatic patients and healthy controls. The relationships between JAM-A and clinical variables in patients with asthma were also examined.

RESULTS

Plasma JAM-A levels were higher in asthma patients (n=19) than in healthy controls (n=12). In asthma patients, the JAM-A levels correlated with forced expiratory volume in 1 second (FEV₁%), FEV₁/forced vital capacity (FVC), and the blood lymphocyte proportion. JAM-A, phospho-JNK, and phospho-ERK protein expressions in lung tissue were significantly higher in OVA/OVA mice than in control mice. In human bronchial epithelial cells treated with house dust mite extracts for 4 h, 8 h, and 24 h, the JAM-A, phospho-JNK, and phospho-ERK expressions were increased, as shown by Western blotting, while the transepithelial electrical resistance was reduced.

CONCLUSION

These results suggest that JAM-A is involved in the pathogenesis of asthma, and may be a marker for asthma.

Cimifugin suppresses type 2 airway inflammation by binding to SPR and regulating its protein expression in a non-enzymatic manner

BACKGROUND

Cimifugin is one of the main bioactive components of Yu-Ping-Feng-San, a well-known traditional Chinese medicine, which can effectively relieve Allergic asthma (AA) and atopic dermatitis and reduce recurrence in clinic. However, the underlying mechanism of cimifugin on AA is still unknown.

PURPOSE

In the present study, we aimed to investigate the effect and mechanism of cimifugin on AA.

STUDY DESIGN

In vivo and in vitro experimental studies were performed.

METHODS

The effect of cimifugin on AA was demonstrated in vivo and in vitro. Sepiapterin reductase (SPR) was predicted as the most potent target of cimifugin in treating AA by reverse docking. Molecular docking and microscale thermophoresis (MST) were used to analyze the direct binding between cimifugin and SPR. Overexpression and interference of SPR were performed to verify whether targeting SPR is a key step of cimifugin in the treatment of AA. QM385, an inhibitor of SPR, was administrated in vivo and in vitro to evaluate the role of SPR in AA. Further, HPLC and cell-free direct hSPR enzyme activity assay were performed to research whether cimifugin regulated SPR by influencing the enzyme activity. Simultaneously, the inhibitors of protein degradation were used in vitro to explore the mechanism of cimifugin on SPR.

RESULTS

We found cimifugin effectively alleviated AA by reducing airway hyperresponsiveness, inhibiting type 2 cytokines-mediated airway inflammation, and restoring the expression of epithelial barrier proteins. Molecular docking predicted the direct binding ability of cimifugin to SPR, which was further verified by MST. Notably, the therapeutic effect of cimifugin on AA was dampened with SPR interfering, in contrast, the phenotypic features of AA were significantly alleviated with QM385 application both in vivo and in vitro. Interestingly, cimifugin showed no effect on the enzyme activity of SPR, as the level of its substrate sepiapterin was not affected with cimifugin treatment by cell-free enzyme activity assay. Furthermore, we found cimifugin could reduce SPR protein expression without affecting its mRNA expression probably through autophagosome pathway.

CONCLUSIONS

To our knowledge, we're reporting for the first time that cimifugin can suppresses type 2 airway inflammation to alleviate AA by directly binding to SPR and regulating its protein expression in a non-enzymatic manner.

Antioxidants prevent particulate matter-induced senescence of lung fibroblasts

Particulate matter (PM) contributes to human diseases, particularly lung disease; however, the molecular mechanism of its action is yet to be determined. Herein, we found that prolonged PM exposure induced the cellular senescence of normal lung fibroblasts via a DNA damage-mediated response. This PM-induced senescence (PM-IS) was only observed in lung fibroblasts but not in A549 lung adenocarcinoma cells. Mechanistic analysis revealed that reactive oxygen species (ROS) activate the DNA damage response signaling axis, increasing p53 phosphorylation, ultimately leading to cellular senescence via an increase in p21 expression without affecting the p16-pRB pathway. A549 cells, instead, were resistant to PM-IS due to the PM-induced ROS production suppression. Water-soluble antioxidants, such as vitamin C and N-Acetyl Cysteine, were found to alleviate PM-IS by suppressing ROS production, implying that antioxidants are a promising therapeutic intervention for PM-mediated lung pathogenesis.

Deciphering the Effects of 2D Black Phosphorus on Disrupted Hematopoiesis and Pulmonary Immune Homeostasis Using a Developed Flow Cytometry Method

As an emerging two-dimensional nanomaterial with promising prospects, mono- or few-layer black phosphorus (BP) is potentially toxic to humans. We investigated the effects of two types of BPs on adult male mice through intratracheal instillation. Using the flow cytometry method, the generation, migration, and recruitment of immune cells in different organs have been characterized on days 1, 7, 14, and 21 post-exposure. Compared with small BP (S-BP, lateral size at ∼188 nm), large BP (L-BP, lateral size at ∼326 nm) induced a stronger stress lymphopoiesis and B cell infiltration into the alveolar sac. More importantly, L-BP dramatically increased peripheral neutrophil (NE) counts up to 1.9-fold on day 21 post-exposure. Decreased expression of the CXCR4 on NEs, an important regulator of NE retention in the bone marrow, explained the increased NE release into the circulation induced by L-BP. Therefore, BP triggers systemic inflammation via the disruption of both the generation and migration of inflammatory immune cells.

Genome-Wide Gene Expression Analysis Reveals Unique Genes Signatures of Epithelial Reorganization in Primary Airway Epithelium Induced by Type-I, -II and -III Interferons

Biosensors such as toll-like receptors (TLR) induce the expression of interferons (IFNs) after viral infection that are critical to the first step in cell-intrinsic host defense mechanisms. Their differential influence on epithelial integrity genes, however, remains elusive. A genome-wide gene expression biosensor chip for gene expression sensing was used to examine the effects of type-I, -II, and -III IFN stimulation on the epithelial expression profiles of primary organotypic 3D air-liquid interface airway cultures. All types of IFNs induced similar interferon-stimulated genes (ISGs): OAS1, OAS2, and IFIT2. However, they differentially induced transcription factors, epithelial modulators, and pro-inflammatory genes. Type-I IFN-induced genes were associated with cell-cell adhesion and tight junctions, while type-III IFNs promoted genes important for transepithelial transport. In contrast, type-II IFN stimulated proliferation-triggering genes associated and enhanced pro-inflammatory mediator secretion. In conclusion, with our microarray system, we provide evidence that the three IFN types exceed their antiviral ISG-response by inducing distinct remodeling processes, thereby likely strengthening the epithelial airway barrier by enhancing cross-cell-integrity (I), transepithelial transport (III) and finally reconstruction through proliferation (II).

Current Insights on the Impact of Proteomics in Respiratory Allergies

Respiratory allergies affect humans worldwide, causing extensive morbidity and mortality. They include allergic rhinitis (AR), asthma, pollen food allergy syndrome (PFAS), aspirin-exacerbated respiratory disease (AERD), and nasal polyps (NPs). The study of respiratory allergic diseases requires new technologies for early and accurate diagnosis and treatment. Omics technologies provide the tools required to investigate DNA, RNA, proteins, and other molecular determinants. These technologies include genomics, transcriptomics, proteomics, and metabolomics. However, proteomics is one of the main approaches to studying allergic disorders' pathophysiology. Proteins are used to indicate normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. In this field, the principal goal of proteomics has been to discover new proteins and use them in precision medicine. Multiple technologies have been applied to proteomics, but that most used for identifying, quantifying, and profiling proteins is mass spectrometry (MS). Over the last few years, proteomics has enabled the establishment of several proteins for diagnosing and treating respiratory allergic diseases.

Korean red ginseng water extract inhibits cadmium-induced lung injury via suppressing MAPK/ERK1/2/AP-1 pathway

Background

Few studies reported the therapeutic effect of Korean Red Ginseng (KRG) in lung inflammatory diseases. However, the anti-inflammatory role and underlying molecular in cadmium-induced lung injury have been poorly understood, directly linked to chronic lung diseases (CLDs): chronic obstructive pulmonary disease (COPD), cancer etc. Therefore, in this study we aim to investigate the therapeutic activities of water extract of KRG (KRG-WE) in mouse cadmium-induced lung injury model.

Method

The anti-inflammatory roles and underlying mechanisms of KRG-WE were evaluated in vitro under cadmium-stimulated lung epithelial cells (A549) and HEK293T cell line and in vivo in cadmium-induced lung injury mouse model using semi-quantitative polymerase chain reaction (RT-PCR), quantitative real-time PCR (qPCR), luciferase assay, immunoblotting, and FACS.

Results

KRG-WE strongly ameliorated the symptoms of CdSO₄-induced lung injury in mice according to total cell number in bronchoalveolar lavage fluid (BALF) and severity scores as well as cytokine levels. KRG-WE significantly suppressed the upregulation of inflammatory signaling comprising mitogen-activated protein kinases (MAPK) and their upstream enzymes. In in vitro study, KRG-WE suppressed expression of interleukin (IL)-6, matrix metalloproteinase (MMP)-2, and IL-8 while promoting recovery in CdSO₄-treated A549 cells. Similarly, KRG-WE reduced phosphorylation of MAPK and c-Jun/c-Fos in cadmium-exposed A549 cells.

Conclusion

KRG-WE was found to attenuate symptoms of cadmium-induced lung injury and reduce the expression of inflammatory genes by suppression of MAPK/AP-1-mediated pathway.