Effects of second hand smoke on airway secretion and mucociliary clearance

Advantages of pulsed electric field ablation for COPD: Excellent killing effect on goblet cells

Mucus hypersecretion resulting from excessive proliferation and metaplasia of goblet cells in the airways is the pathological foundation for Chronic obstructive pulmonary disease (COPD). Clinical trials have confirmed the clinical efficacy of pulsed electric field ablation (PFA) for COPD, but its underlying mechanisms is poorly understood. Cellular and animal models of COPD (rich in goblet cells) were established in this study to detect goblet cells' sensitivity to PFA. Schwan's equation was adopted to calculate the cells' transmembrane potential and the electroporation areas in the cell membrane. We found that goblet cells are more sensitive to low-intensity PFA (250 V/cm-500 V/cm) than BEAS-2B cells. It is attributed to the larger size of goblet cells, which allows a stronger transmembrane potential formation under the same electric field strength. Additionally, the transmembrane potential of larger-sized cells can reach the cell membrane electroporation threshold in more areas. Trypan blue staining confirmed that the cells underwent IRE rate was higher in goblet cells than in BEAS-2B cells. Animal experiments also confirmed that the airway epithelium of COPD is more sensitive to PFA. We conclude that lower-intensity PFA can selectively kill goblet cells in the COPD airway epithelium, ultimately achieving the therapeutic effect of treating COPD.

Machine Learning Reveals Impacts of Smoking on Gene Profiles of Different Cell Types in Lung

Smoking significantly elevates the risk of lung diseases such as chronic obstructive pulmonary disease (COPD) and lung cancer. This risk is attributed to the harmful chemicals in tobacco smoke that damage lung tissue and impair lung function. Current research on the impact of smoking on gene expression in specific lung cells is limited. This study addresses this gap by analyzing gene expression profiles at the single-cell level from 43,539 lung endothelial cells, 234,349 lung epithelial cells, 189,843 lung immune cells, and 16,031 lung stromal cells using advanced machine learning techniques. The data, categorized by different lung cell types, were classified into three smoking states: active smoker, former smoker, and never smoker. Each cell sample encompassed 28,024 feature genes. Employing an incremental feature selection method within a computational framework, several specific genes have been identified as potential markers of smoking status in different lung cell types. These include B2M, EEF1A1, and TPT1 in lung endothelial cells; FTL and MT-ATP8 in lung epithelial cells; HLA-B and HLA-C in lung immune cells; and HSP90B1 and LCN2 in lung stroma cells. Additionally, this study developed quantitative rules for representing the gene expression patterns related to smoking. This research highlights the potential of machine learning in oncology, enhancing our molecular understanding of smoking's harm and laying the groundwork for future mechanism-based studies.

TNF-α and MMPs mediated mucus hypersecretion induced by cigarette smoke: An in vitro study

Cigarette smoke is one of the leading causes of oxidative stress due to high levels of free radicals, which in turn leads to the degradation of alveolar cell walls and development of emphysema. Cigarette smoking has been linked to chronic bronchitis, Chronic Obstructive Pulmonary Disease (COPD) and lung cancer as well. The aim of the present study was to observe the effect of cigarette smoke extract (CSE) on TNF-α and MMPs mediated mucus hypersecretion in A549 cell line. The MTT experiments showed that CSE caused a dose-dependent decline in the level of viability of A549 cells. In addition, AO/PI and Mitotracker Red staining assays demonstrated that CSE caused the A549 cells to undergo apoptosis. This was determined by observing the reduction in mitochondrial membrane potential. CSE was found to be responsible for the formation of intracellular ROS, which was observed by DCFDA staining through fluorescence microscopy. Approximately 65% migration rate was decreased in 20% CSE exposed cells. CSE exposure led to the significantly increased mRNA levels of TNF-α, MMP-7, and MMP-12, in comparison to the control cells. Additionally, the expression of MUC5AC and MUC5B was provoked by CSE as well. Human epithelial cells are stimulated by TNF-α and MMPs secreted mucus, as shown by expression of MUC5AC and MUC5B. CSE could induce mucus in lungs through TNF-α and MMPs mediated pathways.

Lung SPLUNC1 Peptide Derivatives in the Lipid Membrane Headgroup Kill Gram-Negative Planktonic and Biofilm Bacteria

SPLUNC1 (short palate lung and nasal epithelial clone 1) is a multifunctional host defense protein found in human respiratory tract with antimicrobial properties. In this work, we compare the biological activities of four SPLUNC1 antimicrobial peptide (AMP) derivatives using paired clinical isolates of the Gram-negative (G(-)) bacteria Klebsiella pneumoniae, obtained from 11 patients with/without colistin resistance. Secondary structural studies were carried out to study interactions between the AMPs and lipid model membranes (LMMs) utilizing circular dichroism (CD). Two peptides were further characterized using X-ray diffuse scattering (XDS) and neutron reflectivity (NR). A4-153 displayed superior antibacterial activity in both G(-) planktonic cultures and biofilms. NR and XDS revealed that A4-153 (highest activity) is located primarily in membrane headgroups, while A4-198 (lowest activity) is located in hydrophobic interior. CD revealed that A4-153 is helical, while A4-198 has little helical character, demonstrating that helicity and efficacy are correlated in these SPLUNC1 AMPs.

Association of e-Cigarette Exposure with Pediatric Otitis Media Recurrence

OBJECTIVE

Otitis media (OM) is a common inflammatory disease spectrum in children and a leading cause of pediatric physician visits, antibiotic prescriptions and surgery. Tobacco exposure is associated with increased risk of OM recurrence, chronicity and surgeries. Tobacco products have changed dramatically in recent years with the advent of electronic cigarettes (e-cigarettes). While users frequently perceive vape as less harmful than traditional cigarettes, burgeoning evidence supports its contribution to respiratory pathologies. The consequences of secondhand exposure, particularly among children, are understudied. The aim of this study was to examine the association of e-cigarette emissions (EE) with OM recurrence and surgeries in the US.

METHODS

Questionnaire data regarding ear infections and tobacco exposure was gathered for all pediatric respondents of the National Health and Nutrition Examination Survey (NHANES) 2017 to 2018. Weighted analyzes and logistic regression models were used to assess associations.

RESULTS

Data was available for 2022 participants (aged 6-17); all were included for analyzes. Tobacco exposure was observed in 42%; 9% were exposed to EE. EE contributed to risk of ≥3 ear infections (OR = 1.61, 95% CI 1.01-2.58, P = .047). After adjustment for significant covariates (race and asthma), the association fell below significance (P = .081). No other significant associations were observed between ear infections, or tympanostomy tube insertion and exposure variables (EE, gestational or other household exposure).

CONCLUSIONS

Exposure to EE may confer greater risk of pediatric OM than previously identified factors such as household smoke, or gestational exposure. Further investigation of EE and its health implications in children is warranted.

LEVEL OF EVIDENCE

IV.

Lung carcinomas induced by NNK and LPS

Cigarette smoking is the major culprit of chronic lung diseases and the most dominant risk factor for the development of both lung cancer and chronic obstructive pulmonary disease (COPD). In addition, chronic inflammation has been shown to increase the risk of lung cancer and COPD in clinical and epidemiological studies. For pulmonary disease-related research, mice are the most commonly used model system. Multiple lung cancer mouse models driven by targeted genetic alterations are used to evaluate the critical roles of oncogenes and tumor suppressor genes. These models are useful in addressing lung tumorigenesis associated with specific genetic changes, but they are not able to provide a global insight into cigarette smoke-induced carcinogenesis. To fill this knowledge gap, we developed a lung cancer model by treating mice with cigarette smoke carcinogen nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) with/without repeated lipopolysaccharides (LPS) exposure in order to determine the role of chronic inflammation in lung tumorigenesis. Notably, combined LPS/NNK treatment increased tumor number, tumor incidence, and tumor area compared to NNK treatment alone. Therefore, this model offers a feasible approach to investigate lung cancer development on a more global level, determine the role of inflammation in carcinogenesis, and provide a tool for evaluating chemoprevention and immunotherapy.

Treatment with a Urinary Bladder Matrix Alters the Innate Host Response to Pneumonia Induced by Escherichia coli

Escherichia coli has become the prominent cause of nosocomial pneumonia in recent years. In the meantime, some strains of E. coli have developed resistance to commonly used antibacterial drugs. The urinary bladder matrix (UBM) is a biologically derived scaffold material that has been used to promote site-appropriate tissue remodeling in a variety of body systems, partially through the modulation of the innate immune response. In this study, we seek to determine UBM efficacy in preventing bacterial pneumonia in mouse lungs using the Gram-negative bacterial strain E. coli. Our results show that the UBM prevented bacterial biofilm formation in both abiotic and biotic conditions through experimentation on polystyrene plates and culture on the apical surface of differentiated airway epithelial cells. Intratracheal treatment with UBM led to host protection from E. coli-induced respiratory infection in a murine pneumonia model. Transcriptomic analysis revealed the involvement of the enhanced host immune response in UBM-treated mice. Additionally, UBM-treated macrophages had an increased iNOS expression and enhanced phagocytosis activity. Therefore, the protection against E. coli-induced infection and the antibacterial function observed by UBM is potentially through both the anti-biofilm activity and enhanced host immunity following UBM treatment. Taken together, our results support further investigation of UBM as an alternative treatment to attenuate bacterial-induced respiratory infection.

Protective role of overexpressed MUC5AC against fibrosis in MHV-68-induced combined pulmonary fibrosis and emphysema mouse model

Mucins have long been regarded to play a role as a barrier to prevent mucosal infections; however, some studies report that overexpression of mucins induces obstruction and inflammation of airways. We investigated whether the secretion of overexpressed mucin, mucin5ac (MUC5AC), could improve protection against pathogens. To examine the possible roles of mucin hypersecretion in augmenting host defense against disease-promoting muco-obstructive lung disease, a mouse model that overexpressed MUC5AC was generated. We had previously proved that murine gammaherpesvirus-68 (MHV-68) infection could induce emphysema in mice, which later developed into combined pulmonary fibrosis and emphysema (CPFE). We further explored whether increased MUC5AC secretion could provide benefits against MHV-68 induced fibrosis. We initially developed a pcDNA3.1-MUC5AC mouse model. Next, the experimental mice were randomly divided into five groups: normal control, pcDNA3.1 control, pcDNA3.1-MUC5AC, CPFE, and pcDNA3.1- MUC5AC + CPFE. Morphometric analysis of each group was performed by hematoxylin and eosin staining and Masson trichrome staining. MUC5AC levels in lung tissues were analyzed by immunohistochemical staining, real-time polymerase chain reaction, and Western blot analysis. The airway inflammation was determined by differential cell counts of bronchoalveolar lavage fluid (BALF) and measurement of cytokines and chemokines in BALF by enzyme-linked immunosorbent assay. MUC5AC hypersecretion alone was not sufficient to drive goblet cell metaplasia to induce obvious mucus plugging and airway inflammation. However, MUC5AC overexpression served as a protective barrier against MHV-68 virus infection in vivo. Infectivity of MHV-68 was decreased in the pcDNA3.1-MUC5AC + CPFE group compared with that in CPFE group. Meanwhile, a reduction of MHV-68 virus attenuated the expressions of chemokine (C-C motif) ligand 2 (CCL2), chemokine (C-X-C motif) ligand 5 (CXCL5), interleukin-13 (IL-13), and transforming growth factor-β1 (TGF-β1), and weakened airway inflammation and fibrosis in the pcDNA3.1-MUC5AC + CPFE group. Overexpression of MUC5AC appears to exhibit a protective role against MHV-68 infection in mice with emphysema that subsequently developed into CPFE and to further decrease airway inflammation and fibrosis induced by MHV-68 by decreasing the expressions of CCL2, CXCL5, IL-13, and TGF-β1.

Cigarette Smoke Exposure and Inflammatory Signaling Increase the Expression of the SARS-CoV-2 Receptor ACE2 in the Respiratory Tract

The factors mediating fatal SARS-CoV-2 infections are poorly understood. Here, we show that cigarette smoke causes a dose-dependent upregulation of angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 receptor, in rodent and human lungs. Using single-cell sequencing data, we demonstrate that ACE2 is expressed in a subset of secretory cells in the respiratory tract. Chronic smoke exposure triggers the expansion of this cell population and a concomitant increase in ACE2 expression. In contrast, quitting smoking decreases the abundance of these secretory cells and reduces ACE2 levels. Finally, we demonstrate that ACE2 expression is responsive to inflammatory signaling and can be upregulated by viral infections or interferon treatment. Taken together, these results may partially explain why smokers are particularly susceptible to severe SARS-CoV-2 infections. Furthermore, our work identifies ACE2 as an interferon-stimulated gene in lung cells, suggesting that SARS-CoV-2 infections could create positive feedback loops that increase ACE2 levels and facilitate viral dissemination.

The Role of MicroRNA in the Airway Surface Liquid Homeostasis

Mucociliary clearance, mediated by a coordinated function of cilia bathing in the airway surface liquid (ASL) on the surface of airway epithelium, protects the host from inhaled pathogens and is an essential component of the innate immunity. ASL is composed of the superficial mucus layer and the deeper periciliary liquid. Ion channels, transporters, and pumps coordinate the transcellular and paracellular movement of ions and water to maintain the ASL volume and mucus hydration. microRNA (miRNA) is a class of non-coding, short single-stranded RNA regulating gene expression by post-transcriptional mechanisms. miRNAs have been increasingly recognized as essential regulators of ion channels and transporters responsible for ASL homeostasis. miRNAs also influence the airway host defense. We summarize the most up-to-date information on the role of miRNAs in ASL homeostasis and host-pathogen interactions in the airway and discuss concepts for miRNA-directed therapy.

Comprehensive RNA-Seq profiling of the lung transcriptome of Argali hybrid sheep in response to experimental Mycoplasma ovipneumoniae infection

BACKGROUND

An experiment was conducted to reveal why the Argali hybrid sheep are susceptible to Mycoplasma ovipneumoniae infection, the causative agent of mycoplasma ovipneumonia, a chronic respiratory disease that is harmful to the sheep industry.

RESULTS

After nine Argali hybrid sheep, divided into three groups, were experimentally infected with an M. ovipneumoniae strain at 0, 4 and 14 days, transcriptome profiling of lung tissues was performed by deep RNA sequencing, using the Illumina platform. Analysis of differentially expressed genes was performed to determine concomitant gene-specific temporal patterns of mRNA expression in the lungs after M. ovipneumoniae infection. 156 differentially expressed genes (44 up-regulated, 112 down-regulated) were found when comparing transcriptomic data at 4 and 0 days post-infection, and 367 (35 up-regulated, 332 down-regulated) when comparing 14 versus 0 days post-infection. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that the differentially expressed genes at 4 and 14 versus 0 days post-infection were enriched in 109 and 150 pathways, respectively, and the Primary immunodeficiency pathway was considered most closely related to MO infection (p < .01). Hyper-IgM syndrome was identified based on the B-cell Immunodeficiency signaling pathway from differentially expressed genes related to M. ovipneumoniae infection. Gene Ontology analysis showed that differentially expressed genes in different groups were enriched for 497 and 928 terms, where those most closely related to M. ovipneumoniae infection are ciliated motor damage (p < .01).

CONCLUSIONS

The situation that ciliary movement is significantly inhibited and B cells in immunodeficiency are possibly the most important reason why Argali hybrid sheep are susceptible to MO.

Enhanced biofilm prevention activity of a SPLUNC1-derived antimicrobial peptide against Staphylococcus aureus

SPLUNC1 is a multifunctional protein of the airway with antimicrobial properties. We previously reported that it displayed antibiofilm activities against P. aeruginosa. The goal of this study was to determine whether (1) the antibiofilm property is broad (including S. aureus, another prevalent organism in cystic fibrosis); (2) the α4 region is responsible for such activity; and (3), if so, this motif could be structurally optimized as an antimicrobial peptide with enhanced activities. We used S. aureus biofilm-prevention assays to determine bacterial biomass in the presence of SPLUNC1 and SPLUNC1Δα4 recombinant proteins, or SPLUNC1-derived peptides (α4 and α4M1), using the well-established crystal-violet biofilm detection assay. The SPLUNC1Δα4 showed markedly reduced biofilm prevention compared to the parent protein. Surprisingly, the 30-residue long α4 motif alone demonstrated minimal biofilm prevention activities. However, structural optimization of the α4 motif resulted in a modified peptide (α4M1) with significantly enhanced antibiofilm properties against methicillin–sensitive (MSSA) and–resistant (MRSA) S. aureus, including six different clinical strains of MRSA and the well-known USA300. Hemolytic activity was undetectable at up to 100μM for the peptides. The data warrant further investigation of α4-derived AMPs to explore the potential application of antimicrobial peptides to combat bacterial biofilm-related infections.

Insights in particulate matter-induced allergic airway inflammation: Focus on the epithelium

Outdoor air pollution is a major environmental health problem throughout the world. In particular, exposure to particulate matter (PM) has been associated with the development and exacerbation of several respiratory diseases, including asthma. Although the adverse health effects of PM have been demonstrated for many years, the underlying mechanisms have not been fully identified. In this review, we focus on the role of the lung epithelium and specifically highlight multiple cytokines in PM-induced respiratory responses. We describe the available literature on the topic including in vitro studies, findings in humans (ie observations in human cohorts, human controlled exposure and ex vivo studies) and in vivo animal studies. In brief, it has been shown that exposure to PM modulates the airway epithelium and promotes the production of several cytokines, including IL-1, IL-6, IL-8, IL-25, IL-33, TNF-α, TSLP and GM-CSF. Further, we propose that PM-induced type 2-promoting cytokines are important mediators in the acute and aggravating effects of PM on airway inflammation. Targeting these cytokines could therefore be a new approach in the treatment of asthma.

Aberrant epithelial remodeling with impairment of cilia architecture in non-cystic fibrosis bronchiectasis

BACKGROUND

Aberrant epithelial remodeling and/or abnormalities in mucociliary apparatus in airway epithelium contribute to infection and inflammation. It is uncertain if these changes occur in both large and small airways in non-cystic fibrosis bronchiectasis (non-CF bronchiectasis). In this study, we aim to investigate the histopathology and inflammatory profile in the epithelium of bronchi and bronchioles in bronchiectasis.

METHODS

Excised lung tissue sections from 52 patients with non-CF bronchiectasis were stained with specific cellular markers and analyzed by immunohistochemistry and immunofluorescence to assess the epithelial structures, including ciliated cells and goblet cells morphology. Inflammatory cell counts and ciliary proteins expression levels of centrosomal protein 110 (CP110) and dynein heavy chain 5, axonemal (DNAH5) were assessed.

RESULTS

Epithelial hyperplasia is found in both bronchi and bronchioles in all specimens, including hyperplasia and/or hypertrophy of goblet cells. The median cilia length is longer in hyperplastic epithelium [bronchi: 8.16 (7.03-9.14) µm, P<0.0001; bronchioles: 7.46 (6.41-8.48) µm, P<0.0001] as compared to non-hyperplastic epithelium (bronchi: 5.60 µm; bronchioles: 4.89 µm). Hyperplastic epithelium is associated with overexpression of CP110 and decreased intensity of DNAH5 expression in both bronchial and bronchiolar epithelium. Though infiltration of neutrophils is predominant (63.0% in bronchi and 76.7% in bronchioles), eosinophilic infiltration is also present in the mucosa of bronchi (30.8%) and bronchioles (54.8%).

CONCLUSIONS

Aberrant epithelial remodeling with impaired mucociliary architecture is present in both large and small airways in patients with refractory non-CF bronchiectasis. Future studies should evaluate the interplay between these individual components in driving chronic inflammation and lung damage in patients.

Establishment and Evaluation of a Rat Model of Sidestream Cigarette Smoke-Induced Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common cause of mortality worldwide. The current lack of an animal model that can be established within a certain time frame and imitate the unique features of the disease is a major limiting factor in its study. The present study established and evaluated an animal model of COPD that represents the early and advanced stage features using short-, middle-, and long-term sidestream cigarette smoke (CS) exposure. One hundred and nine Sprague-Dawley rats were randomly divided into 10 groups for different periods of sidestream CS exposure or no exposure (i.e., normal groups). The rats were exposed to CS from 3R4F cigarettes in an exposure chamber. Histological analysis was performed to determine pathological changes. We also conducted open-field tests, lung function evaluations, and cytokine analysis of the blood serum, bronchoalveolar lavage fluid, and lung tissue. The lung tissue protein levels, blood gases, and were also analyzed. As the CS exposure time increased, the indicators associated with oxidative stress, inflammatory responses, and airway remodeling were greater in the CS exposure groups than in the normal group. At 24 and 36 weeks, the COPD model rats displayed the middle- and advanced-stage features of COPD, respectively. In the 8-week CS exposure group, after the CS exposure was stopped for 4 weeks, inflammatory responses and oxidative responses were ameliorated and lung function exacerbation was reduced compared with the 12-week CS exposure group. Therefore, we established a more adequate rat model of sidestream CS induced COPD, which will have great significance for a better understanding of the pathogenesis of COPD and drug effectiveness evaluation.

Sex-specific lung functional changes in adult mice exposed only to second-hand smoke in utero

Background

An increasing number of epidemiological and experimental studies have associated exposure to second-hand smoke (SHS) during pregnancy with adverse outcomes in newborns. As we have previously shown in mice, in utero exposure to SHS at critical stages of fetal development, results in altered lung responses and increased disease susceptibility upon re-exposure to irritants (SHS or ovalbumin) in adulthood. In this study, we asked whether the in utero SHS exposure alone is sufficient to alter lung structure and function in adult mice.

Methods

Pregnant BALB/c mice were exposed from days 6 to 19 of pregnancy to 10 mg/m³ of SHS or HEPA-filtered air. Male and female offspring (n = 13–15/group) were sacrificed at 15 weeks of age. We measured lung function with non-invasive and invasive methods, performed lung morphometric analysis on trichrome-stained lung tissue samples, and assessed lung gene expression via RNA sequencing and protein assays.

Results

In utero SHS exposure significantly increased mean linear intercept and decreased the surface area per unit volume of the lungs in both males and females, indicating perturbation in alveolar developmental processes. Tidal volume, minute volume and inspiratory capacity were significantly decreased compared with the controls only in male mice exposed in utero to SHS, suggesting that males are more sensitive than females to an SHS insult during lung development. This also suggests that in our model, lung structure changes may be necessary but are not sufficient to impair lung function. SERPINA1A, the mouse ortholog of human α1-antitrypsin, deficiency of which is a known genetic risk factor for emphysema, was down-regulated at the protein level in the in utero SHS-exposed mice. Additionally, DNMT3A protein expression was dysregulated, indicating that DNA methylation occurred in the lungs.

Conclusions

Our results indicate that in utero SHS exposure alone alters both lung function and structure well into adulthood (15 weeks) in male mice. Furthermore, lung function alterations in this model are sex-specific, with males being more susceptible to in utero SHS effects. Overall, our data suggest that in utero SHS exposure alone can predispose to adult lung diseases.

[The use of fenspiride for the combined treatment of exacerbation of chronic laryngitis]

The present study was carried out based at the Department of Otorhinolaryngology of I.P. Pavlov First State Medical University of Saint-Petersburg. The objective of this work was to elucidate the efficacy and safety of fenspiride therapy for the treatment of exacerbation of chronic laryngitis associated with an acute respiratory infection. The patients comprising the main group received fenspiride (Eurespal, 'Servier', France) at the standard dose in addition to the conventional therapy with the use of antibiotics, inhalation, and voice rest. The patients in the group of comparison were treated following the conventional protocol without fenspiride. The clinical symptoms evaluated based on the scoring system, the results of videolaryngoscopy, and computer-assisted analysis of the voice were compared before and after treatment in the patients of both groups. The results of the study have confirmed the high effectiveness and safety of fenspiride therapy of exacerbation of chronic laryngitis.

3D Reconstruction of the Human Airway Mucosa In Vitro as an Experimental Model to Study NTHi Infections

We have established an in vitro 3D system which recapitulates the human tracheo-bronchial mucosa comprehensive of the pseudostratified epithelium and the underlying stromal tissue. In particular, we reported that the mature model, entirely constituted of primary cells of human origin, develops key markers proper of the native tissue such as the mucociliary differentiation of the epithelial sheet and the formation of the basement membrane. The infection of the pseudo-tissue with a strain of NonTypeable Haemophilus influenzae results in bacteria association and crossing of the mucus layer leading to an apparent targeting of the stromal space where they release large amounts of vesicles and form macro-structures. In summary, we propose our in vitro model as a reliable and potentially customizable system to study mid/long term host-pathogen processes.

Inflammatory Diseases of the Lung Induced by Conventional Cigarette Smoke: A Review

Smoking-induced lung diseases were extremely rare prior to the 20th century. With commercialization and introduction of machine-made cigarettes, worldwide use skyrocketed and several new pulmonary diseases have been recognized. The majority of pulmonary diseases caused by cigarette smoke (CS) are inflammatory in origin. Airway epithelial cells and alveolar macrophages have altered inflammatory signaling in response to CS, which leads to recruitment of lymphocytes, eosinophils, neutrophils, and mast cells to the lungs-depending on the signaling pathway (nuclear factor-κB, adenosine monophosphate-activated protein kinase, c-Jun N-terminal kinase, p38, and signal transducer and activator of transcription 3) activated. Multiple proteins are upregulated and secreted in response to CS exposure, and many of these have immunomodulatory activities that contribute to disease pathogenesis. In particular, metalloproteases 9 and 12, surfactant protein D, antimicrobial peptides (LL-37 and human β defensin 2), and IL-1, IL-6, IL-8, and IL-17 have been found in higher quantities in the lungs of smokers with ongoing inflammation. However, many underlying mechanisms of smoking-induced inflammatory diseases are not yet known. We review here the known cellular and molecular mechanisms of CS-induced diseases, including COPD, respiratory bronchiolitis-interstitial lung disease, desquamative interstitial pneumonia, acute eosinophilic pneumonia, chronic rhinosinusitis, pulmonary Langerhans cell histiocytosis, and chronic bacterial infections. We also discuss inflammation induced by secondhand and thirdhand smoke exposure and the pulmonary diseases that result. New targeted antiinflammatory therapeutic options are currently under investigation and hopefully will yield promising results for the treatment of these highly prevalent smoking-induced diseases.

The spacer arm length in cell-penetrating peptides influences chitosan/siRNA nanoparticle delivery for pulmonary inflammation treatment

Although chitosan and its derivatives have been frequently utilized as delivery vehicles for small interfering RNA (siRNA), it is challenging to improve the gene silencing efficiency of chitosan-based nanoparticles. In this study, we hypothesized that controlling the spacer arm length between a cell-penetrating peptide (CPP) and a nanoparticle could be critical to enhancing the cellular uptake as well as the gene silencing efficiency of conventional chitosan/siRNA nanoparticles. A peptide consisting of nine arginine units (R9) was used as a CPP, and the spacer arm length was controlled by varying the number of glycine units between the peptide (R9Gn) and the nanoparticle (n = 0, 4, and 10). Various physicochemical characteristics of R9Gn-chitosan/siRNA nanoparticles were investigated in vitro. Increasing the spacing arm length did not significantly affect the complex formation between R9Gn-chitosan and siRNA. However, R9G10-chitosan was much more effective in delivering genes both in vitro and in vivo compared with non-modified chitosan (without the peptide) and R9-chitosan (without the spacer arm). Chitosan derivatives modified with oligoarginine containing a spacer arm can be considered as potential delivery vehicles for various genes.

Closed-loop ARS mode for scanning ion conductance microscopy with improved speed and stability for live cell imaging applications

Scanning ion conductance microscopy (SICM) is an increasingly useful nanotechnology tool for non-contact, high resolution imaging of live biological specimens such as cellular membranes. In particular, approach-retract-scanning (ARS) mode enables fast probing of delicate biological structures by rapid and repeated approach/retraction of a nano-pipette tip. For optimal performance, accurate control of the tip position is a critical issue. Herein, we present a novel closed-loop control strategy for the ARS mode that achieves higher operating speeds with increased stability. The algorithm differs from that of most conventional (i.e., constant velocity) approach schemes as it includes a deceleration phase near the sample surface, which is intended to minimize the possibility of contact with the surface. Analysis of the ion current and tip position demonstrates that the new mode is able to operate at approach speeds of up to 250 μm s(-1). As a result of the improved stability, SICM imaging with the new approach scheme enables significantly improved, high resolution imaging of subtle features of fixed and live cells (e.g., filamentous structures & membrane edges). Taken together, the results suggest that optimization of the tip approach speed can substantially improve SICM imaging performance, further enabling SICM to become widely adopted as a general and versatile research tool for biological studies at the nanoscale level.

Moraxella catarrhalis induces an immune response in the murine lung that is independent of human CEACAM5 expression and long-term smoke exposure

In patients with chronic obstructive pulmonary disease (COPD), Moraxella catarrhalis infection of the lower airways is associated with chronic colonization and inflammation during stable disease and acute exacerbations. Chronic smoke exposure induces chronic inflammation and impairs mucociliary clearance, thus contributing to bacterial colonization of the lower airways in COPD patients. The human-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 5, expressed in human airways, has been shown to contribute to epithelial colonization of CEACAM-binding pathogens. To investigate the impact of CEACAM5 expression on pulmonary M. catarrhalis colonization, we infected mice transgenic for human CEACAM5 (hCEACAM5) and wild type mice intratracheally with M. catarrhalis with or without preceding smoke exposure and analyzed bacterial colonization and local and systemic inflammation. Our results show that airway infection with M. catarrhalis accelerated acute local but not systemic inflammation, albeit independent of hCEACAM5 expression. Long-term smoke exposure alone or prior to M. catarrhalis infection did not contribute to increased local or systemic inflammation. No difference was found in pulmonary clearance of M. catarrhalis in hCEACAM5-transgenic mice compared with wild-type mice. Smoke exposure neither altered time nor extent of persistence of M. catarrhalis in the lungs of both genotypes. In conclusion, M. catarrhalis induced a local acute immune response in murine airways. Neither hCEACAM5 expression nor chronic smoke exposure nor a combination of both was sufficient as prerequisites for the establishment of chronic M. catarrhalis colonization. Our results demonstrate the difficulties in mirroring conditions of chronic airways colonization of M. catarrhalis in a murine model.

Increased susceptibility to pulmonary Pseudomonas infection in Splunc1 knockout mice

The airway epithelium is the first line of host defense against pathogens. The short palate, lung, and nasal epithelium clone (SPLUNC)1 protein is secreted in respiratory tracts and is a member of the bacterial/permeability increasing (BPI) fold-containing protein family, which shares structural similarities with BPI-like proteins. On the basis of its homology with BPIs and restricted expression of SPLUNC1 in serous cells of submucosal glands and surface epithelial cells of the upper respiratory tract, SPLUNC1 is thought to possess antimicrobial activity in host defense. SPLUNC1 is also reported to have surfactant properties, which may contribute to anti-biofilm defenses. The objective of this study was to determine the in vivo functions of SPLUNC1 following Pseudomonas aeruginosa infection and to elucidate the underlying mechanism by using a knockout (KO) mouse model with a genetic ablation of Splunc1. Splunc1 KO mice showed accelerated mortality and increased susceptibility to P. aeruginosa infection with significantly decreased survival rates, increased bacterial burdens, exaggerated tissue injuries, and elevated proinflammatory cytokine levels as compared with those of their wild-type littermates. Increased neutrophil infiltration in Splunc1 KO mice was accompanied by elevated chemokine levels, including Cxcl1, Cxcl2, and Ccl20. Furthermore, the expression of several epithelial secretory proteins and antimicrobial molecules was considerably suppressed in the lungs of Splunc1 KO mice. The deficiency of Splunc1 in mouse airway epithelium also results in increased biofilm formation of P. aeruginosa. Taken together, our results support that the ablation of Splunc1 in mouse airways affects the mucociliary clearance, resulting in decreased innate immune response during Pseudomonas-induced respiratory infection.

Barrier function of airway tract epithelium

Airway epithelium contributes significantly to the barrier function of airway tract. Mucociliary escalator, intercellular apical junctional complexes which regulate paracellular permeability and antimicrobial peptides secreted by the airway epithelial cells are the three primary components of barrier function of airway tract. These three components act cooperatively to clear inhaled pathogens, allergens and particulate matter without inducing inflammation and maintain tissue homeostasis. Therefore impairment of one or more of these essential components of barrier function may increase susceptibility to infection and promote exaggerated and prolonged innate immune responses to environmental factors including allergens and pathogens resulting in chronic inflammation. Here we review the regulation of components of barrier function with respect to chronic airways diseases.