Cigarette smoke extract enhances neutrophil elastase-induced IL-8 production via proteinase-activated receptor-2 upregulation in human bronchial epithelial cells

Molecular Mechanisms and the Interplay of Important Chronic Obstructive Pulmonary Disease Biomarkers Reveals Novel Therapeutic Targets

Chronic Obstructive Pulmonary Disease (COPD) is a progressive, age-dependent, and unmet chronic inflammatory disease of the peripheral airways, leading to difficulty in exhalation. Several biomarkers have been tested in general towards the resolution for a long time, but no apparent success was achieved. Ongoing therapies of COPD have only symptomatic relief but no cure. Reactive oxygen species (ROS) are highly reactive species which include oxygen radicals and nonradical derivatives, and are the prominent players in COPD. They are produced as natural byproducts of cellular metabolism, but their levels can vary due to exposure to indoor air pollution, occupational pollution, and environmental pollutants such as cigarette smoke. In COPD, the lungs are continuously exposed to high levels of ROS thus leading to oxidative stress. ROS can cause damage to cells, proteins, lipids, and DNA which further contributes to the chronic inflammation in COPD and exacerbates the disease condition. Excessive ROS production can overwhelm cellular antioxidant systems and act as signaling molecules that regulate cellular processes, including antioxidant defense mechanisms involving glutathione and sirtuins which further leads to cellular apoptosis, cellular senescence, inflammation, and sarcopenia. In this review paper, we focused on COPD from different perspectives including potential markers and different cellular processes such as apoptosis, cellular senescence, inflammation, sirtuins, and sarcopenia, and tried to connect the dots between them so that novel therapeutic strategies to evaluate and target the possible underlying mechanisms in COPD could be explored.

A Structural Network Analysis of Neuronal ArhGAP21/23 Interactors by Computational Modeling

RhoGTPase-activating proteins (RhoGAPs) play multiple roles in neuronal development; however, details of their substrate recognition system remain elusive. ArhGAP21 and ArhGAP23 are RhoGAPs that contain N-terminal PDZ and pleckstrin homology domains. In the present study, the RhoGAP domain of these ArhGAPs was computationally modeled by template-based methods and the AlphaFold2 software program, and their intrinsic RhoGTPase recognition mechanism was analyzed from the domain structures using the protein docking programs HADDOCK and HDOCK. ArhGAP21 was predicted to preferentially catalyze Cdc42, RhoA, RhoB, RhoC, and RhoG and to downregulate RhoD and Tc10 activities. Regarding ArhGAP23, RhoA and Cdc42 were deduced to be its substrates, whereas RhoD downregulation was predicted to be less efficient. The PDZ domains of ArhGAP21/23 possess the FTLRXXXVY sequence, and similar globular folding consists of antiparalleled β-sheets and two α-helices that are conserved with PDZ domains of MAST-family proteins. A peptide docking analysis revealed the specific interaction of the ArhGAP23 PDZ domain with the PTEN C-terminus. The pleckstrin homology domain structure of ArhGAP23 was also predicted, and the functional selectivity for the interactors regulated by the folding and disordered domains in ArhGAP21 and ArhGAP23 was examined by an in silico analysis. An interaction analysis of these RhoGAPs revealed the existence of mammalian ArhGAP21/23-specific type I and type III Arf- and RhoGTPase-regulated signaling. Multiple recognition systems of RhoGTPase substrates and selective Arf-dependent localization of ArhGAP21/23 may form the basis of the functional core signaling necessary for synaptic homeostasis and axon/dendritic transport regulated by RhoGAP localization and activities.

PAR2 Overexpression is Involved in the Occurrence of Hyperoxygen-Induced Bronchopulmonary Dysplasia in Rats

BACKGROUND

Bronchopulmonary dysplasia is a chronic lung disease commonly seen in preterm infants. It is characterized by delayed development of the alveoli and lung fibrosis. Protease-activated receptor 2 (PAR2) is an inflammatory driver that plays a proinflammatory role mainly through the P38 MAPK/NF-κB signaling pathway.

METHODS

Newborn rat pups were kept under air or oxygen at >60% concentration. Lung tissues were collected at postnatal days (P) 1, 4, 7, and 10 to observe pathological changes and take measurements.

RESULTS

In the hyperoxic group, P4 and P7 rats showed delayed alveolar development, septal thickening, and disturbances in alveolar structure.PAR2, P38 MAPK, NF-κB, and IL-18 expression at P4, P7, and P10 was significantly higher than in the air group.

CONCLUSION

PAR2 is involved in lung injury induced by persistent hyperoxia. Activated PAR2 promotes IL-18 overexpression through the P38 MAPK/NF-κB signaling pathway, which may be an important mechanism of PAR2-mediated lung injury in bronchopulmonary dysplasia.

Candida albicans Sap6 Initiates Oral Mucosal Inflammation via the Protease Activated Receptor PAR2

Candida albicans Sap6, a secreted aspartyl protease (Sap), contributes to fungal virulence in oral candidiasis. Beside its protease activity, Sap6 contains RGD (RGDRGD) motif required for its binding to host integrins. Sap6 activates immune cells to induce proinflammatory cytokines, although its ability to interact and activate human oral epithelial cells (OECs) remain unknown. Addition of purified recombinant Sap6 (rSap6) to OECs resulted in production of IL-1β and IL-8 cytokines similar to live hyphal C. albicans. OECs exposed to rSap6 showed phosphorylation of p38 and MKP1 and expression of c-Fos not found with C. albicans Δsap6, heat-inactivated Sap6, or rSap6ΔRGD . Heat inactivated rSap6 was able to induce IL-1β but not IL-8 in OECs, while rSap6ΔRGD induced IL-8 but not IL-1β suggesting parallel signaling pathways. C. albicans hyphae increased surface expression of Protease Activated Receptors PAR1, PAR2 and PAR3, while rSap6 increased PAR2 expression exclusively. Pretreatment of OECs with a PAR2 antagonist blocked rSap6-induced p38 MAPK signaling and IL-8 release, while rSap6ΔRGD had reduced MKP1 signaling and IL-1β release independent from PAR2. OECs exposed to rSap6 exhibited loss of barrier function as measured by TEER and reduction in levels of E-cadherin and occludin junctional proteins that was prevented by pretreating OECs with a PAR2 antagonist. OECs treated with PAR2 antagonist also showed reduced rSap6-mediated invasion by C. albicans cells. Thus, Sap6 may initiate OEC responses mediated both through protease activation of PAR2 and by its RGD domain. This novel role of PAR2 suggests new drug targets to block C. albicans oral infection.

Pristimerin alleviates cigarette smoke-induced inflammation in chronic obstructive pulmonary disease via inhibiting NF-κB pathway

Cigarette smoke (CS) is a risk factor for chronic obstructive pulmonary disease (COPD), which can exacerbate inflammation and oxidative stress. Pristimerin (Pris) is a natural compound with antioxidant and anti-inflammatory effects. We managed to evaluate the protective effects of Pris on CS-induced COPD. The CS-induced COPD mice model and cell model were constructed. The effects of Pris treatment on lung function, inflammatory cell infiltration, myeloperoxidase (MPO), and pathological changes of lung tissues in mice model were evaluated. The impacts of Pris treatment on inflammatory factors, chemokines, and oxidative stress parameters in mice lung tissues and cells were determined by kits. The viability of human bronchial epithelial cells after Pris treatment was tested by CCK-8. The activation of NF-κB pathway was confirmed by Western blot and immunofluorescence. CS treatment impaired lung function, reduced weight of mice, and enhanced inflammatory cell infiltration, MPO, and lung tissue damage, but these effects of CS were reversed by Pris treatment. Furthermore, Pris treatment downregulated the levels of malondialdehyde, IL-6, IL-1β, TNF-α, CXCL1, and CXLC2, but upregulated superoxide dismutase and catalase levels. Pris treatment could overturn CS-induced activation of the NF-κB pathway. Pris alleviates CS-induced COPD by inactivating NF-κB pathway.

The role of neutrophil elastase in aortic valve calcification

Background

Calcific aortic valve disease (CAVD) is the most commonly valvular disease in the western countries initiated by inflammation and abnormal calcium deposition. Currently, there is no clinical drug for CAVD. Neutrophil elastase (NE) plays a causal role in inflammation and participates actively in cardiovascular diseases. However, the effect of NE on valve calcification remains unclear. So we next explore whether it is involved in valve calcification and the molecular mechanisms involved.

Methods

NE expression and activity in calcific aortic valve stenosis (CAVD) patients (n = 58) and healthy patients (n = 30) were measured by enzyme-linked immunosorbent assay (ELISA), western blot and immunohistochemistry (IHC). Porcine aortic valve interstitial cells (pVICs) were isolated and used in vitro expriments. The effects of NE on pVICs inflammation, apoptosis and calcification were detected by TUNEL assay, MTT assay, reverse transcription polymerase chain reaction (RT-PCR) and western blot. The effects of NE knockdown and NE activity inhibitor Alvelestat on pVICs inflammation, apoptosis and calcification under osteogenic medium induction were also detected by RT-PCR, western blot, alkaline phosphatase staining and alizarin red staining. Changes of Intracellular signaling pathways after NE treatment were measured by western blot. Apolipoprotein E⁻/⁻ (APOE⁻/⁻) mice were employed in this study to establish the important role of Alvelestat in valve calcification. HE was used to detected the thickness of valve. IHC was used to detected the NE and α-SMA expression in APOE⁻/⁻ mice. Echocardiography was employed to assess the heat function of APOE⁻/⁻ mice.

Results

The level and activity of NE were evaluated in patients with CAVD and calcified valve tissues. NE promoted inflammation, apoptosis and phenotype transition in pVICs in the presence or absence of osteogenic medium. Under osteogenic medium induction, NE silencing or NE inhibitor Alvelestat both suppressed the osteogenic differentiation of pVICs. Mechanically, NE played its role in promoting osteogenic differentiation of pVICs by activating the NF-κB and AKT signaling pathway. Alvelestat alleviated valve thickening and decreased the expression of NE and α-SMA in western diet-induced APOE⁻/⁻ mice. Alvelestat also reduced NE activity and partially improved the heart function of APOE⁻/⁻mice.

Conclusions

Collectively, NE is highly involved in the pathogenesis of valve calcification. Targeting NE such as Alvelestat may be a potential treatment for CAVD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03363-1.

Cellular and Molecular Signatures of Oxidative Stress in Bronchial Epithelial Cell Models Injured by Cigarette Smoke Extract

Exposure of the airways epithelium to environmental insults, including cigarette smoke, results in increased oxidative stress due to unbalance between oxidants and antioxidants in favor of oxidants. Oxidative stress is a feature of inflammation and promotes the progression of chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). Increased oxidative stress leads to exhaustion of antioxidant defenses, alterations in autophagy/mitophagy and cell survival regulatory mechanisms, thus promoting cell senescence. All these events are amplified by the increase of inflammation driven by oxidative stress. Several models of bronchial epithelial cells are used to study the molecular mechanisms and the cellular functions altered by cigarette smoke extract (CSE) exposure, and to test the efficacy of molecules with antioxidant properties. This review offers a comprehensive synthesis of human in-vitro and ex-vivo studies published from 2011 to 2021 describing the molecular and cellular mechanisms evoked by CSE exposure in bronchial epithelial cells, the most used experimental models and the mechanisms of action of cellular antioxidants systems as well as natural and synthetic antioxidant compounds.

Therapeutic Potential of Human Umbilical Cord-Derived Mesenchymal Stem Cells in Recovering From Murine Pulmonary Emphysema Under Cigarette Smoke Exposure

Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) were shown to have potential for immunoregulation and tissue repair. The objective of this study was to investigate the effects of hUC-MSCs on emphysema in chronic obstructive pulmonary disease (COPD). The C57BL/6JNarl mice were exposed to cigarette smoke (CS) for 4 months followed by administration of hUC-MSCs at 3 × 10⁶ (low dose), 1 × 10⁷ (medium dose), and 3 × 10⁷ cells/kg body weight (high dose). The hUC-MSCs caused significant decreases in emphysema severity by measuring the mean linear intercept (MLI) and destructive index (DI). A decrease in neutrophils (%) and an increase in lymphocytes (%) in bronchoalveolar lavage fluid (BALF) were observed in emphysematous mice after hUC-MSC treatment. Lung levels of interleukin (IL)-1β, C-X-C motif chemokine ligand 1 (CXCL1)/keratinocyte chemoattractant (KC), and matrix metalloproteinase (MMP)-12 significantly decreased after hUC-MSC administration. Significant reductions in tumor necrosis factor (TNF)-α, IL-1β, and IL-17A in serum occurred after hUC-MSC administration. Notably, the cell viability of lung fibroblasts improved with hUC-MSCs after being treated with CS extract (CSE). Furthermore, the hUC-MSCs-conditioned medium (hUC-MSCs-CM) restored the contractile force, and increased messenger RNA expressions of elastin and fibronectin by lung fibroblasts. In conclusion, hUC-MSCs reduced inflammatory responses and emphysema severity in CS-induced emphysematous mice.

Role of Neutrophils on the Ocular Surface

The ocular surface is a gateway that contacts the outside and receives stimulation from the outside. The corneal innate immune system is composed of many types of cells, including epithelial cells, fibroblasts, natural killer cells, macrophages, neutrophils, dendritic cells, mast cells, basophils, eosinophils, mucin, and lysozyme. Neutrophil infiltration and degranulation occur on the ocular surface. Degranulation, neutrophil extracellular traps formation, called NETosis, and autophagy in neutrophils are involved in the pathogenesis of ocular surface diseases. It is necessary to understand the role of neutrophils on the ocular surface. Furthermore, there is a need for research on therapeutic agents targeting neutrophils and neutrophil extracellular trap formation for ocular surface diseases.

Impact of air pollution and smoking on COVID-19: a review

Background

The 21st century already witnessed many deadly epidemics and pandemics. The major ones were respiratory tract infections like SARS (2003), H1N1 (2009), MERS (2012) and the most recent pandemic COVID-19 (2019). The COVID-19 story begins when pneumonia of unknown cause was reported in the WHO country office of China at the end of 2019. SARS-CoV-2 is the causative agent that enters the host through the receptor ACE2, a component of the renin–angiotensin system.

Main body of the abstract

Symptoms of COVID-19 varies from patient to patient. It is all about the immunity and health status of the individual that decides the severity of the disease. The review focuses on the significant and often prevailing factors, those that influence the lung function. The factors that compromise the lung functions which may prepare the ground for severe COVID-19 infection are interestingly looked into. Focus was more on air pollution and cigarette smoke.

Short conclusion

The fact that the forested areas across the world show very low COVID-19 infection rate suggests that we are in need of the “Clean Air” on the fiftieth anniversary of World Earth Day. As many policies are implemented worldwide to protect from SARS-CoV-2, one simple remedy that we forgot was clean air can save lives. SARS-CoV-2 infects our lungs, and air pollution makes us more susceptible. In this crucial situation, the focus is only on the main threat; all other conditions are only in words to console the situation.

Human Neutrophil Elastase Mediates MUC5AC Hypersecretion via the Tumour Necrosis Factor-α Converting Enzyme-Epidermal Growth Factor Receptor Signalling Pathway in vivo

OBJECTIVES

The objective of this study is to examine the role of the tumour necrosis factor-α converting enzyme-epidermal growth factor receptor (TACE-EGFR) pathway in human neutrophil elastase (HNE)-induced MUC5AC mucin expression in mice.

METHOD

Four groups of mice, treated with HNE alone (HNE group), HNE plus TACE inhibitor (HNE + TAPI-2 group), HNE plus EGFR inhibitor (HNE + AG1478 group), and untreated (control group), were used in the experiment. Histopathological changes were monitored by haematoxylin-eosin (HE) and periodic acid-Schiff (PAS) staining. TACE, EGFR, and MUC5AC expression in the nasal mucosa were determined using immunohistochemistry. The expression of p-EGFR, EGFR, and TACE protein was analysed on Western blots, and MUC5AC protein levels were assessed via ELISA. TACE, EGFR, and MUC5AC expression in the nasal mucosa were determined using real-time quantitative PCR.

RESULTS

Compared to the control group, HE-stained tissues from the HNE group showed an irregular epithelium as well as goblet cell and submucosal glandular hyperplasia. In the nasal mucosa, strongly positive fuchsia granules were seen in PAS staining and significant increases in TACE, EGFR, MUC5AC mRNA, and protein expression were detected (p < 0.01). The HNE + TAPI-2 and HNE + AG1478 groups had significantly less goblet cell and submucosal gland hyperplasia as well as weaker PAS staining. Compared to mice treated with HNE alone, in HNE + TAPI-2-treated mice, the levels of TACE, EGFR, and MUC5AC mRNA and protein as well as p-EGFR protein were significantly reduced (p < 0.01). In HNE + AG1478-treated mice, EGFR and MUC5AC mRNA and protein levels and p-EGFR protein expression were reduced significantly (p < 0.01), but the difference in TACE mRNA and protein expression between the HNE + AG1478 and HNE groups was not significant (p > 0.05).

CONCLUSION

Using a newly developed, stable experimental model of nasal hypersecretion in mice, we showed that TAPI-2 or AG1478 inhibited HNE-induced MUC5AC production. This suggests that MUC5AC mucin expression in vivo is mediated by a cascade involving the HNE-TACE-EGFR signalling pathway.

Synergistic cycles of protease activity and inflammation via PPARγ degradation in chronic obstructive pulmonary disease

Inflammation, oxidative stress, and protease-antiprotease imbalance have been suggested to be a pathogenic triad in chronic obstructive pulmonary disease (COPD). However, it is not clear how proteases interact with components of inflammatory pathways. Therefore, this study aimed to evaluate the effect of neutrophil elastase (NE) on lipopolysaccharide (LPS)-induced interleukin 8 (IL-8) production and determine the molecular mechanism in human bronchial epithelial cells (HBECs). Immortalized bronchial epithelial cells and primary HBECs were used to investigate the impact of NE on LPS-induced IL-8 production. The molecular mechanism by which NE modulated LPS-induced IL-8 production was confirmed in elastase-treated C57BL/6 mice and primary HBECs obtained from COPD patients and healthy controls. The results showed that NE treatment synergistically augmented LPS-induced IL-8 production in both immortalized bronchial epithelial cells and primary HBECs. NE partially degraded peroxisome proliferator-activated receptor gamma (PPARγ), which is known to regulate IL-8 production in the nucleus. Treatment with a PPARγ agonist and overexpression of PPARγ reversed the NE-induced synergistic increase in LPS-induced IL-8 production. Moreover, PPARγ levels were lower in lung homogenates and lung epithelial cells from elastase-treated mice than in those from saline-treated mice. In accordance with the findings in mice, PPARγ levels were lower in primary HBECs from COPD patients than in those from healthy never-smokers or healthy smokers. In conclusion, a vicious cycle of mutual augmentation of protease activity and inflammation resulting from PPARγ degradation plays a role in the pathogenesis of COPD.

Lung epithelium damage in COPD - An unstoppable pathological event?

Chronic obstructive pulmonary disease (COPD) is a common term for alveolar septal wall destruction resulting in emphysema, and chronic bronchitis accompanied by conductive airway remodelling. In general, this disease is characterized by a disbalance of proteolytic/anti-proteolytic activity, augmented inflammatory response, increased oxidative/nitrosative stress, rise in number of apoptotic cells and decreased proliferation. As the first responder to the various environmental stimuli, epithelium occupies an important position in different lung pathologies, including COPD. Epithelium sequentially transitions from the upper airways in the direction of the gas exchange surface in the alveoli, and every cell type possesses a distinct role in the maintenance of the homeostasis. Basically, a thick ciliated structure of the airway epithelium has a major function in mucus secretion, whereas, alveolar epithelium which forms a thin barrier covered by surfactant has a function in gas exchange. Following this line, we will try to reveal whether or not the chronic bronchitis and emphysema, being two pathological phenotypes in COPD, could originate in two different types of epithelium. In addition, this review focuses on the role of lung epithelium in COPD pathology, and summarises underlying mechanisms and potential therapeutics.

In utero tobacco smoke exposure alters lung inflammation, viral clearance, and CD8+T-cell responses in neonatal mice infected with respiratory syncytial virus

Maternal smoking during pregnancy and exposure of infants to cigarette smoke are strongly associated with adverse health effects in childhood including higher susceptibility to respiratory viral infections. Human respiratory syncytial virus (HRSV) is the most important cause of lower respiratory tract infection among young infants. Exacerbation of respiratory disease, including HRSV bronchiolitis and higher susceptibility to HRSV infection, is well correlated with previous smoke exposure. The mechanisms of recurrence and susceptibility to viral pathogens after passive smoke exposure are multifactorial and include alteration of the structural and immunologic host defenses. In this work, we used a well-established mouse model of in utero smoke exposure to investigate the effect of in utero smoke exposure in HRSV-induced pathogenesis. Sample analysis indicated that in utero exposure led to increased lung inflammation characterized by an increased influx of neutrophils to the airways of the infected mice and a delayed viral clearance. On the other hand, decreased HRSV-specific CD8+T-cell response was observed. These findings indicate that cigarette smoke exposure during pregnancy alters HRSV-induced disease as well as several aspects of the neonatal immune responses.

Pistacia weinmannifolia ameliorates cigarette smoke and lipopolysaccharide‑induced pulmonary inflammation by inhibiting interleukin‑8 production and NF‑κB activation

Pistacia weinmannifolia (PW) has been used in traditional Chinese medicine to treat headaches, dysentery, enteritis and influenza. However, PW has not been known for treating respiratory inflammatory diseases, including chronic obstructive pulmonary disease (COPD). The present in vitro analysis confirmed that PW root extract (PWRE) exerts anti-inflammatory effects in phorbol myristate acetate- or tumor necrosis factor α (TNF-α)-stimulated human lung epithelial NCI-H292 cells by attenuating the expression of interleukin (IL)-8, IL-6 and Mucin A5 (MUC5AC), which are closely associated with the pulmonary inflammatory response in the pathogenesis of COPD. Thus, the aim of the present study was to evaluate the protective effect of PWRE on pulmonary inflammation induced by cigarette smoke (CS) and lipopoly-saccharide (LPS). Treatment with PWRE significantly reduced the quantity of neutrophils and the levels of inflammatory molecules and toxic molecules, including tumor TNF-α, IL-6, IL-8, monocyte chemoattractant protein-1, neutrophil elastase and reactive oxygen species, in the bronchoalveolar lavage fluid of mice with CS- and LPS-induced pulmonary inflammation. PWRE also attenuated the influx of inflammatory cells in the lung tissues. Furthermore, PWRE downregulated the activation of nuclear factor-κB and the expression of phosphodiesterase 4 in the lung tissues. Therefore, these findings suggest that PWRE may be a valuable adjuvant treatment for COPD.