Vitamin D Modulates the Response of Bronchial Epithelial Cells Exposed to Cigarette Smoke Extract

The development and characterization of in vivo-like three-dimensional models of bronchial epithelial cell lines

In vitro models of differentiated respiratory epithelium that allow high-throughput screening are an important tool to explore new therapeutics for chronic respiratory diseases. In the present study, we developed in vivo-like three-dimensional (3-D) models of bronchial epithelial cell lines that are commonly used to study chronic lung disease (16HBE14o-, CFBE41o- and CFBE41o- 6.2 WT-CFTR). To this end, cells were cultured on porous microcarrier beads in the rotating wall vessel (RWV) bioreactor, an optimized suspension culture method that allows higher throughput experimentation than other physiologically relevant models. Cell differentiation was compared to conventional two-dimensional (2-D) monolayer cultures and to the current gold standard in the respiratory field, i.e. air-liquid interface (ALI) cultures. Cellular differentiation was assessed in the three model systems by evaluating the expression and localization of markers that reflect the formation of tight junctions (zonula occludens 1), cell polarity (intercellular adhesion molecule 1 at the apical side and collagen IV expression at the basal cell side), multicellular complexity (acetylated α-tubulin for ciliated cells, CC10 for club cells, keratin-5 for basal cells) and mucus production (MUC5AC) through immunostaining and confocal laser scanning microscopy. Results were validated using Western Blot analysis. We found that tight junctions were expressed in 2-D monolayers, ALI cultures and 3-D models for all three cell lines. All tested bronchial epithelial cell lines showed polarization in ALI and 3-D cultures, but not in 2-D monolayers. Mucus secreting goblet-like cells were present in ALI and 3-D cultures of CFBE41o- and CFBE41o- 6.2 WT-CFTR cells, but not in 16HBE14o- cells. For all cell lines, there were no ciliated cells, basal cells, or club cells found in any of the model systems. In conclusion, we developed RWV-derived 3-D models of commonly used bronchial epithelial cell lines and showed that these models are a valuable alternative to ALI cultures, as they recapitulate similar key aspects of the in vivo parental tissue.

Vitamin D3 protects against respiratory syncytial virus-induced barrier dysfunction in airway epithelial cells via PKA signaling pathway

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infection in infants and young children globally and is responsible for hospitalization and mortality in the elderly population. Virus-induced airway epithelial barrier damage is a critical step during RSV infection, and emerging studies suggest that RSV disrupts the tight junctions (TJs) and adherens junctions (AJs) between epithelial cells, increasing the permeability of the airway epithelial barrier. The lack of commercially available vaccines and effective antiviral drugs for RSV emphasizes the need for new management strategies. Vitamin D3 is a promising intervention for viral infection due to its critical role in modulating innate immune responses. However, there is limited evidence on the effect of vitamin D3 on RSV pathogenies. Here, we investigated the impact of vitamin D3 on RSV-induced epithelial barrier dysfunction and the underlying mechanisms. We found that pre-incubation with 1,25(OH)2D3, the active form of vitamin D3, alleviated RSV-induced epithelial barrier disruption in a dose-dependent manner without affecting viability in 16HBE cells. 1,25(OH)2D3 induced minor changes in the protein expression level of TJ/AJ proteins in RSV-infected cells. We observed increased CREB phosphorylation at Ser133 during 1,25(OH)2D3 exposure, indicating that vitamin D3 triggered protein kinase A (PKA) activity in 16HBE. PKA inhibitors modified the restoration of barrier function by 1,25(OH)2D3 in RSV-infected cells, implying that PKA signaling is responsible for the protective effects of vitamin D3 against RSV-induced barrier dysfunction in airway epithelial cells. Our findings suggest vitamin D3 as a prophylactic intervention to protect the respiratory epithelium during RSV infections.

Protective effects of inhaled antioxidants against air pollution-induced pathological responses

As the public health burden of air pollution continues to increase, new strategies to mitigate harmful health effects are needed. Dietary antioxidants have previously been explored to protect against air pollution-induced lung injury producing inconclusive results. Inhaled (pulmonary or nasal) administration of antioxidants presents a more promising approach as it could directly increase antioxidant levels in the airway surface liquid (ASL), providing protection against oxidative damage from air pollution. Several antioxidants have been shown to exhibit antioxidant, anti-inflammatory, and anti-microbial properties in in vitro and in vivo models of air pollution exposure; however, little work has been done to translate these basic research findings into practice. This narrative review summarizes these findings and data from human studies using inhaled antioxidants in response to air pollution, which have produced positive results, indicating further investigation is warranted. In addition to human studies, cell and murine studies should be conducted using more relevant models of exposure such as air-liquid interface (ALI) cultures of primary cells and non-aqueous apical delivery of antioxidants and pollutants. Inhalation of antioxidants shows promise as a protective intervention to prevent air pollution-induced lung injury and exacerbation of existing lung disease.

Visualising SARS-CoV-2 infection of the lung in deceased COVID-19 patients

BACKGROUND

SARS-CoV-2 is a single-stranded positive-sense RNA virus. Several negative-sense SARS-CoV-2 RNA species, both full-length genomic and subgenomic, are produced transiently during viral replication. Methodologies for rigorously characterising cell tropism and visualising ongoing viral replication at single-cell resolution in histological sections are needed to assess the virological and pathological phenotypes of future SARS-CoV-2 variants. We aimed to provide a robust methodology for examining the human lung, the major target organ of this RNA virus.

METHODS

A prospective cohort study took place at the University Hospitals Leuven in Leuven, Belgium. Lung samples were procured postmortem from 22 patients who died from or with COVID-19. Tissue sections were fluorescently stained with the ultrasensitive single-molecule RNA in situ hybridisation platform of RNAscope combined with immunohistochemistry followed by confocal imaging.

FINDINGS

We visualised perinuclear RNAscope signal for negative-sense SARS-CoV-2 RNA species in ciliated cells of the bronchiolar epithelium of a patient who died with COVID-19 in the hyperacute phase of the infection, and in ciliated cells of a primary culture of human airway epithelium that had been infected experimentally with SARS-CoV-2. In patients who died between 5 and 13 days after diagnosis of the infection, we detected RNAscope signal for positive-sense but not for negative-sense SARS-CoV-2 RNA species in pneumocytes, macrophages, and among debris in the alveoli. SARS-CoV-2 RNA levels decreased after a disease course of 2-3 weeks, concomitant with a histopathological change from exudative to fibroproliferative diffuse alveolar damage. Taken together, our confocal images illustrate the complexities stemming from traditional approaches in the literature to characterise cell tropism and visualise ongoing viral replication solely by the surrogate parameters of nucleocapsid-immunoreactive signal or in situ hybridisation for positive-sense SARS-CoV-2 RNA species.

INTERPRETATION

Confocal imaging of human lung sections stained fluorescently with commercially available RNAscope probes for negative-sense SARS-CoV-2 RNA species enables the visualisation of viral replication at single-cell resolution during the acute phase of the infection in COVID-19. This methodology will be valuable for research on future SARS-CoV-2 variants and other respiratory viruses.

FUNDING

Max Planck Society, Coronafonds UZ/KU Leuven, European Society for Organ Transplantation.

Anemoside B4 prevents chronic obstructive pulmonary disease through alleviating cigarette smoke-induced inflammatory response and airway epithelial hyperplasia

BACKGROUND

Cigarette smoke (CS) is one of the major risk factors for chronic obstructive pulmonary disease (COPD) and increases the risk of lung cancer (LC). Anemoside B4 (B4) is the main bioactive ingredient in Pulsatilla chinensis (P. chinensis), a traditional medicinal herb for various diseases. It has a wide range of anti-inflammatory, anti-oxidation and anti-cancer activities. However, in recent years, there is no relevant literature report on the therapeutic effect of B4 on COPD, and the anti-inflammatory and inhibitory effects of anemoside B4 on basal cell hyperplasia in CS-induced COPD have not been clearly established.

PURPOSE

In the present study, we investigated whether anemoside B4 could alleviate CS or cigarette smoke extract (CSE) induced inflammation of COPD and further prevent basal cell hyperplasia, hoping to find its possible mechanism.

METHODS

In this study, a COPD mouse model was established in C57BL mice by CS exposure 3 months. Bronchial pathology and basal cell hyperplasia were observed by HE staining and immunostaining. The contents of glutathione peroxidase catalase (GSH-PX), malondialdehyde (MDA) and superoxide dismutase (MPO) were determined by GSH-PX, MDA and SOD assay kits, respectively. 16HBE cells were cultured with 5% CSE with or without treatment with B4 (1, 10, 100 μM) or DEX (20 μM) in vitro. Cell viability was assessed by a cell counting kit 8 (CCK-8). Reactive oxygen species (ROS) generation was tested by DCFH-DA. Moreover, anti-inflammatory mechanism of anemoside B4 was further determined by pro-inflammatory cytokines production using RT-PCR. Protein expression levels of MAPK/AP-1/TGF-β signaling pathway were measured by western blot.

RESULTS

Anemoside B4 improved the lung function of mice, relieved lung inflammation and reduced the MDA, MPO and GSH-Px in the plasma. At the same time, B4 repressed the oxidative stress response and played a role in balancing the levels of protease and anti-protease. During the process of bronchial basal cell hyperplasia, B4 alleviated the degree of cell hyperplasia, and prevented further deterioration of hyperplasia through increased P53 and inhibited FHIT protein. In addition, B4 reduced ROS levels in human bronchial epithelial cells stimulated by CSE in vitro study. Meanwhile, B4 treatment also significantly attenuated increased IL-1β, TGF-β, IL-8 and TNF-α from CSE treated human bronchial epithelial cells. The expression of p-P38, AP-1(c-fos, and c-Jun), TGF-β proteins in MAPK/AP-1/TGF-β signaling pathway were decreased and the signal cascade reaction was blocked.

CONCLUSION

Anemoside B4 protects against CS-induced COPD. These findings indicated that B4 may have therapeutic potential for the prevention and treatment of COPD.

A Scoping Analysis of Cathelicidin in Response to Organic Dust Exposure and Related Chronic Lung Illnesses

Over two billion people worldwide are exposed to organic dust, which can cause respiratory disorders. The discovery of the cathelicidin peptide provides novel insights into the lung’s response to organic dust; however, its role in the lung’s response to organic dust exposure and chronic lung diseases remains limited. We conducted a scoping review to map the current evidence on the role of cathelicidin LL-37/CRAMP in response to organic dust exposure and related chronic lung diseases: hypersensitivity pneumonitis (HP), chronic obstructive pulmonary disease (COPD) and asthma. We included a total of n = 53 peer-reviewed articles in this review, following the process of (i) a preliminary screening; (ii) a systematic MEDLINE/PubMed database search; (iii) title, abstract and full-text screening; (iv) data extraction and charting. Cathelicidin levels were shown to be altered in all clinical settings investigated; its pleiotropic function was confirmed. It was found that cathelicidin contributes to maintaining homeostasis and participates in lung injury response and repair, in addition to exerting a positive effect against microbial load and infections. In addition, LL-37 was found to sustain continuous inflammation, increase mucus formation and inhibit microorganisms and corticosteroids. In addition, studies investigated cathelicidin as a treatment modality, such as cathelicidin inhalation in experimental HP, which had positive effects. However, the primary focus of the included articles was on LL-37’s antibacterial effect, leading to the conclusion that the beneficial LL-37 activity has not been adequately examined and that further research is required.

The Dietary Inflammatory Index and Early COPD: Results from the National Health and Nutrition Examination Survey

We examined 3962 people aged 20 to 49 years who had information on spirometry testing and underwent a 24 h dietary recall interview from the 2007-2012 National Health and Nutrition Examination Survey (NHANES) and used multivariable logistic regression to evaluate associations between Dietary Inflammatory Index (DII, a pro-inflammatory diet) and early COPD and lung function. The overall prevalence of early COPD was 5.05%. Higher DII was associated with increased odds of early COPD (quartile 4 vs. 1, the OR = 1.657, 95% CI = 1.100-2.496, p = 0.0156). In a full-adjusted model, each unit of increase in DII score was associated with a 90.3% increase in the risk of early COPD. Higher DII is significantly associated with lower FEV1 and FVC among individuals with early COPD, each unit increment in the DII was significantly associated with 0.43 L-0.58 L decrements in FEV1 (β = -0.43, 95% CI = -0.74, -0.12) and FVC (β = -0.58, 95% CI = -1.01, -0.16). These findings demonstrate that higher consumption of a pro-inflammatory diet may contribute to an increased risk of early COPD and lower lung function, and further support dietary interventions as part of a healthy lifestyle in order to preserve lung function and prevent or improve COPD.

CircRNA circ_0006892 regulates miR-24/PHLPP2 axis to mitigate cigarette smoke extract-induced bronchial epithelial cell injury

Chronic obstructive pulmonary disease (COPD) is a chronic airway disorder mainly resulted from cigarette smoke exposure. The dysregulated circular RNAs (circRNAs) are relevant to the pathogenesis of COPD. This study aims to explore the function and mechanism of circRNA hsa_circ_0006892 (circ_0006892) in cigarette smoke extract (CSE)-induced bronchial epithelial injury. The lung tissues were collected from 17 nonsmokers and 23 smokers with COPD. The bronchial epithelial cells (BEAS-2B and 16HBE) were stimulated via CSE. Circ_0006892, microRNA-24 (miR-24), and PH domain and leucine-rich repeat protein phosphatase 2 (PHLPP2) abundances were examined via a quantitative reverse transcription polymerase chain reaction or Western blot. Cell viability, apoptosis, and inflammatory response were assessed via cell counting kit-8 (CCK-8), flow cytometry, and enzyme-linked immunosorbent assay (ELISA). The target relationship of miR-24 and circ_0006892 or PHLPP2 was tested via dual-luciferase reporter analysis, RNA immunoprecipitation, and RNA pull-down. Circ_0006892 expression was reduced in lung tissues of smokers with COPD and CSE-stimulated bronchial epithelial cells. Circ_0006892 overexpression alleviated CSE-induced viability reduction and promotion of apoptosis and inflammatory response. MiR-24 was bound via circ_0006892, and miR-24 overexpression reversed the effect of circ_0006892 on CSE-induced injury. PHLPP2 was targeted via miR-24, and miR-24 knockdown mitigated CSE-induced viability reduction and promotion of apoptosis and inflammatory response via regulating PHLPP2. Circ_0006892 could promote PHLPP2 expression via regulating miR-24. Circ_0006892 attenuated CSE-induced bronchial epithelial cell apoptosis and inflammatory response via regulating miR-24/PHLPP2 axis.

Vitamin D3 alleviates cigarette smoke extract‑mediated epithelial‑mesenchymal transition and fibrogenesis by upregulating CC16 expression in bronchial epithelial cells

Vitamin D3 supplementation has been previously reported to inhibit the occurrence and development of chronic obstructive pulmonary disease (COPD). However, the underlying mechanism remains unclear. Epithelial-mesenchymal transition (EMT) and fibrogenesis have been associated with the development of COPD. The aim of the present study was to investigate the potential effects and mechanism of vitamin D3 in an in vitro model of cigarette smoke (CS)-induced EMT and fibrosis, with specific focus on the role of club cell protein 16 (CC16). CS extract (CSE) at different concentrations (5, 10 and 20%) was used to treat 16-HBE cells to induce EMT and fibrogenesis following which they were treated with vitamin D3. Subsequently, the 20% CSE group was selected for further experiments, where 16-HBE cells were divided into the following five groups: The control group; the CSE group; the low-dose vitamin D3 group (250 nM); the medium-dose vitamin D3 group (500 nM); and the high-dose vitamin D3 group (1,000 nM). Western blot analysis was used to detect the protein expression levels of the EMT-related proteins E-cadherin, N-cadherin, Slug and α-SMA, fibrogenesis-related proteins collagen Ⅳ and fibronectin 1, proteins involved in the TGF-β1/SMAD3 signaling pathway and CC16. Immunofluorescence was used to measure the protein expression levels of E-cadherin, N-cadherin and collagen Ⅳ. Specific CC16 knockdown was performed using short hairpin RNA transfection to investigate the role of CC16. The results of the present study found that vitamin D3 could increase the protein expression level of CC16 to inhibit the activation of the TGF-β1/SMAD3 signaling pathway; thereby reducing the 20% increase in CSE-induced EMT- and fibrogenesis-related protein expression levels. Following CC16 knockdown, the inhibitory effects of vitamin D3 on EMT- and fibrogenesis-related protein expression were partially reversed. To conclude, these results suggest that vitamin D3 can inhibit the protein expression levels of EMT- and fibrogenesis-related proteins induced by CSE, at least partially through the function of CC16. These findings are expected to provide novel theoretical foundations and ideas for the pathogenesis and treatment of COPD.

Local nebulization of 1α,25(OH)2D3 attenuates LPS-induced acute lung inflammation

Background

Evidence supports a critical role of vitamin D status on exacerbation in chronic obstructive pulmonary disease, indicating the need to avoid vitamin D deficiency in these patients. However, oral vitamin D supplementation is limited by the potential risk for hypercalcemia. In this study, we investigated if local delivery of vitamin D to the lungs improves vitamin D-mediated anti-inflammatory action in response to acute inflammation without inducing hypercalcemia.

Methods

We studied vitamin D sufficient (VDS) or deficient (VDD) mice in whom 1α,25(OH)₂D₃ (0.2 μg/kg) or a vehicle followed by lipopolysaccharide (LPS 25 µg) were delivered to the lung as a micro-spray.

Results

Local 1α,25(OH)₂D₃ reduced LPS-induced inflammatory cells in bronchoalveolar lavage (BAL) in VDS (absolute number of cells: − 57% and neutrophils − 51% p < 0.01) and tended to diminish LPS-increased CXCL5 BAL levels in VDS (− 40%, p = 0.05) while it had no effect on CXCL1 and CXCL2 in BAL and mRNA in lung of VDS and VDD. It also significantly attenuated the increased IL-13 in BAL and lung, especially in VDD mice (− 41 and − 75%, respectively). mRNA expression of Claudin-18 in lung was significantly lower in VDS mice with local 1α,25(OH)₂D₃ while Claudin-3, -5 and -8 mRNA levels remained unchanged. Finally, in VDD mice only, LPS reduced lung mRNA expression of adhesion junction Zona-occludens-1, in addition to increasing uric acid and total protein in BAL, which both were prevented by local 1α,25(OH)₂D₃.

Conclusion

Under normal levels of vitamin D, local 1α,25(OH)₂D₃ nebulization into the lung efficiently reduced LPS induction of inflammatory cells in BAL and slightly attenuated LPS-increase in CXCL5. In case of severe vitamin D deficiency, although local 1α,25(OH)₂D₃ nebulization failed to significantly minimize cellular inflammation in BAL at this dose, it prevented epithelial barrier leakage and damage in lung. Additional research is needed to determine the potential long-term beneficial effects of local 1α,25(OH)2D3 nebulization on lung inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01997-9.

Vitamin D Actions: The Lung Is a Major Target for Vitamin D, FGF23, and Klotho

Vitamin D is well known for its role as a calcium regulator and in maintenance of phosphate homeostasis in musculoskeletal health, and fibroblast growth factor 23 (FGF23) and its coreceptor α-klotho are known for their roles as regulators of serum phosphate levels. However, apart from these classical actions, recent data point out a relevant role of vitamin D and FGF23/klotho in lung health. The expression of the vitamin D receptor by different cell types in the lung and the fact that those cells respond to vitamin D or can locally produce vitamin D indicate that the lung represents a target for vitamin D actions. Similarly, the presence of the four FGF receptor isoforms in the lung and the ability of FGF23 to stimulate pulmonary cells support the concept that the lung is a target for FGF23 actions, whereas the contribution of klotho is still undetermined. This review will give an overview on how vitamin D or FGF23/klotho may act on the lung and interfere positively or negatively with lung health. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Genome-wide CRISPR screening identifies TMEM106B as a proviral host factor for SARS-CoV-2

The ongoing COVID-19 pandemic has caused a global economic and health crisis. To identify host factors essential for coronavirus infection, we performed genome-wide functional genetic screens with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and human coronavirus 229E. These screens uncovered virus-specific as well as shared host factors, including TMEM41B and PI3K type 3. We discovered that SARS-CoV-2 requires the lysosomal protein TMEM106B to infect human cell lines and primary lung cells. TMEM106B overexpression enhanced SARS-CoV-2 infection as well as pseudovirus infection, suggesting a role in viral entry. Furthermore, single-cell RNA-sequencing of airway cells from patients with COVID-19 demonstrated that TMEM106B expression correlates with SARS-CoV-2 infection. The present study uncovered a collection of coronavirus host factors that may be exploited to develop drugs against SARS-CoV-2 infection or future zoonotic coronavirus outbreaks.

Vitamin D modulates E-cadherin turnover by regulating TGF-β and Wnt signalings during EMT-mediated myofibroblast differentiation in A459 cells

Vitamin D (VitD) has an anti-fibrotic effect on fibrotic lungs. It reduces epithelial-mesenchymal transition (EMT) on tumors. We aimed to investigate target proteins of VitD for the regression of EMT-mediated myofibroblast differentiation. A group of A549 cells were treated with 5 % cigarette smoke extract (CSE) and 5 %CSE + TGF-β (5 ng/ml) to induce EMT. The others were treated with 50 nM VitD 30 min before %5CSE and TGF-β treatments. All cells were collected at 24, 48 and 72 h following 5 %CSE and TGF-β administrations. The expression of p120ctn and NEDD9 proteins acted on E-cadherin turnover in addition to activations of TGF-β and Wnt pathways were examined in these cells and fibrotic human lungs. CSE and TGF-β induced EMT by reducing E-cadherin, p-VDR, SMAD7 and DKK1, increasing α-SMA, p120ctn, Kaiso, NEDD9 and stimulating TGF-β and Wnt/β-catenin signalings in A549 cells. VitD administration reversed these alterations and regressed EMT. Co-immunoprecipitation analysis revealed p-VDR interaction with β-catenin and Kaiso in fibrotic and non-fibrotic human lungs. VitD pre-treatments reduced TGF-β and Wnt/β-catenin signalings by increasing p-VDR, protected from E-cadherin degradation and led to the regression of EMT in A549 cells treated with CSE and TGF-β. Finally, VitD supplementation combined with anti-fibrotic therapeutics can be suggested for treatment of pulmonary fibrosis, which may be developed by smoking, in cases of VitD deficiency.

Local expression profiles of vitamin D-related genes in airways of COPD patients

Treatment of Chronic Obstructive Pulmonary Disease (COPD) is based on bronchodilation, with inhaled corticosteroids or azithromycin associated when frequent exacerbations occur. Despite the proven benefits of current treatment regimens, the need for new interventions in delineated subgroups remains. There is convincing evidence for oral vitamin D supplementation in reducing exacerbations in COPD patients severely deficient for circulating vitamin D. However, little is known about local vitamin D metabolism in the airways and studies examining expression of the vitamin D receptor (VDR), the activating enzyme (CYP27B1) and inactivating enzyme (CYP24A1) of vitamin D in lung tissue of COPD patients are lacking. Therefore, the expression and localization of key enzymes and the receptor of the vitamin D pathway were examined in tissue of 10 unused donor lungs and 10 COPD explant lungs. No differences in the expression of CYP27B1 and CYP24A1 were found. Although protein expression of VDR was significantly lower in COPD explant tissue, there was no difference in downstream expression of the antimicrobial peptide cathelicidin. Whereas CYP27B1 and CYP24A1 were present in all layers of the bronchial epithelium, VDR was only expressed at the apical layer of a fully differentiated bronchial epithelium with no expression in vascular endothelial cells. By contrast, CYP24A1 expression was highly present in lung endothelial cells suggesting that systemic vitamin D can be inactivated before reaching the epithelial compartment and the tissue immune cells. These data support the idea of exploring the role of vitamin D inhalation in patients with COPD.