Lung Macrophage Phenotypes and Functional Responses: Role in the Pathogenesis of COPD

Cigarette Smoke Constituents and Nicotine Differentially Affect Cytokine Production by Human Macrophages Stimulated by TLR Ligands In Vitro: Considerations for a Standardised Protocol

Chronic obstructive pulmonary disease (COPD) is an inflammatory lung condition associated with cigarette (tobacco) smoking. Numerous in vivo animal studies have been conducted to investigate the links between cigarette smoke, nicotine and infection in lung pathology. As an alternative to animal experiments, we used an in vitro system to investigate the effects of cigarette smoke extract (CSE) or nicotine on TNF-α and IL-10 production by monocyte-derived human macrophages. The macrophages were simultaneously stimulated with either poly-IC (as a chemical surrogate for viral infection) or lipopolysaccharide (as a chemical surrogate for Gram-negative bacterial infection). CSE enhanced TNF-α production, whereas nicotine inhibited IL-10 production by the macrophages, particularly when co-stimulated with the microbial chemical surrogates. A system of this type may help to further our understanding of the immunological and inflammatory effects of smoking, without recourse to in vivo studies. Requirements for the optimisation and standardisation of such an in vitro system are also discussed.

Exportin XPO6 upregulation activates the TLR2/MyD88/NF-κB signaling by facilitating TLR2 mRNA nuclear export in COPD pulmonary monocytes

Chronic obstructive pulmonary disease (COPD) poses a significant health threat characterized by lung inflammation primarily triggered by pulmonary monocytes. Despite the centrality of inflammation in COPD, the regulatory mechanisms governing this response remain elusive, presenting a challenge for anti-inflammatory interventions. In this study, we assessed the expression of exportins in COPD mouse models, revealing a notable upregulation of XPO6 in the mouse lung (P = 0.0011). Intriguingly, we observed a consistent upregulation of XPO6 in pulmonary monocytes from both human and mouse COPD subjects (P < 0.0001). Furthermore, in human lung tissue, XPO6 expression exhibited a positive correlation with TLR2 expression (P = 0). In vitro investigations demonstrated that XPO6 enhances TLR2 expression, activating the MyD88/NF-κB inflammatory signaling pathway. This activation, in turn, promotes the secretion of pro-inflammatory cytokines such as TNFα, IL-6, and IL-1β in monocytes. Mechanistically, XPO6 facilitates the nuclear export of TLR2 mRNA, ensuring its stability and subsequent protein expression in monocytes. In conclusion, our findings unveil that the upregulation of XPO6 in COPD pulmonary monocytes activates the MyD88/NF-κB inflammatory signaling pathway by facilitating the nuclear export of TLR2 mRNA, thereby identifying XPO6 as a promising therapeutic target for anti-inflammatory interventions in COPD.

Melatonin improves influenza virus infection-induced acute exacerbation of COPD by suppressing macrophage M1 polarization and apoptosis

BACKGROUND

Influenza A viruses (IAV) are extremely common respiratory viruses for the acute exacerbation of chronic obstructive pulmonary disease (AECOPD), in which IAV infection may further evoke abnormal macrophage polarization, amplify cytokine storms. Melatonin exerts potential effects of anti-inflammation and anti-IAV infection, while its effects on IAV infection-induced AECOPD are poorly understood.

METHODS

COPD mice models were established through cigarette smoke exposure for consecutive 24 weeks, evaluated by the detection of lung function. AECOPD mice models were established through the intratracheal atomization of influenza A/H3N2 stocks in COPD mice, and were injected intraperitoneally with melatonin (Mel). Then, The polarization of alveolar macrophages (AMs) was assayed by flow cytometry of bronchoalveolar lavage (BAL) cells. In vitro, the effects of melatonin on macrophage polarization were analyzed in IAV-infected Cigarette smoking extract (CSE)-stimulated Raw264.7 macrophages. Moreover, the roles of the melatonin receptors (MTs) in regulating macrophage polarization and apoptosis were determined using MTs antagonist luzindole.

RESULTS

The present results demonstrated that IAV/H3N2 infection deteriorated lung function (reduced FEV20,50/FVC), exacerbated lung damages in COPD mice with higher dual polarization of AMs. Melatonin therapy improved airflow limitation and lung damages of AECOPD mice by decreasing IAV nucleoprotein (IAV-NP) protein levels and the M1 polarization of pulmonary macrophages. Furthermore, in CSE-stimulated Raw264.7 cells, IAV infection further promoted the dual polarization of macrophages accompanied with decreased MT1 expression. Melatonin decreased STAT1 phosphorylation, the levels of M1 markers and IAV-NP via MTs reflected by the addition of luzindole. Recombinant IL-1β attenuated the inhibitory effects of melatonin on IAV infection and STAT1-driven M1 polarization, while its converting enzyme inhibitor VX765 potentiated the inhibitory effects of melatonin on them. Moreover, melatonin inhibited IAV infection-induced apoptosis by suppressing IL-1β/STAT1 signaling via MTs.

CONCLUSIONS

These findings suggested that melatonin inhibited IAV infection, improved lung function and lung damages of AECOPD via suppressing IL-1β/STAT1-driven macrophage M1 polarization and apoptosis in a MTs-dependent manner. Melatonin may be considered as a potential therapeutic agent for influenza virus infection-induced AECOPD.

Inflammation mediates the association between furan exposure and the prevalence and mortality of chronic obstructive pulmonary disease: National Health and Nutrition Examination Survey 2013-2018

BACKGROUND

Although extensive research has established associations between chronic obstructive pulmonary disease (COPD) and environmental pollutants, the connection between furan and COPD remains unclear. This study aimed to explore the association between furan and COPD while investigating potential mechanisms.

METHODS

The study involved 7,482 adults from the National Health and Nutrition Examination Survey 2013-2018. Exposure to furan was assessed using blood furan levels. Participants were categorized into five groups based on quartiles of log10-transformed blood furan levels. Logistic regression and restricted cubic spline regression models were used to assess the association between furan exposure and COPD risk. Mediating analysis was performed to assess the contribution of inflammation to the effects of furan exposure on COPD prevalence. Cox regression was used to assess the association between furan exposure and the prognosis of COPD.

RESULTS

Participants with COPD exhibited higher blood furan levels compared to those without COPD (P < 0.001). Log10-transformed blood furan levels were independently associated with an increased COPD risk after adjusting for all covariates (Q5 vs. Q1: OR = 4.47, 95% CI = 1.58-12.66, P = 0.006, P for trend = 0.001). Inflammatory cells such as monocytes, neutrophils, and basophils were identified as mediators in the relationship between furan exposure and COPD prevalence, with mediated proportions of 8.73%, 20.90%, and 10.94%, respectively (all P < 0.05). Moreover, multivariate Cox regression analysis revealed a positive correlation between log10-transformed blood furan levels and respiratory mortality in COPD patients (HR = 41.00, 95% CI = 3.70-460.00, P = 0.003).

CONCLUSIONS

Exposure to furan demonstrates a positive correlation with both the prevalence and respiratory mortality of COPD, with inflammation identified as a crucial mediator in this relationship.

Evaluating β2-agonists as siRNA delivery adjuvants for pulmonary surfactant-coated nanogel inhalation therapy

The lung is an attractive target organ for inhalation of RNA therapeutics, such as small interfering RNA (siRNA). However, clinical translation of siRNA drugs for application in the lung is hampered by many extra- and intracellular barriers. We previously developed hybrid nanoparticles consisting of an siRNA-loaded nanosized hydrogel (nanogel) core coated with Curosurf®, a clinically used pulmonary surfactant. The surfactant shell was shown to markedly improve particle stability and promote intracellular siRNA delivery, both in vitro and in vivo. However, the full potential of siRNA nanocarriers is typically not reached as they are rapidly trafficked towards lysosomes for degradation and only a fraction of the internalized siRNA cargo is able to escape into the cytosol. We recently reported on the repurposing of widely applied cationic amphiphilic drugs (CADs) as siRNA delivery enhancers. Due to their physicochemical properties, CADs passively accumulate in the (endo)lysosomal compartment causing a transient permeabilization of the lysosomal membrane, which facilitates cytosolic drug delivery. In this work, we assessed a selection of cationic amphiphilic β2-agonists (i.e., salbutamol, formoterol, salmeterol and indacaterol) for their ability to enhance siRNA delivery in a lung epithelial and macrophage cell line. These drugs are widely used in the clinic for their bronchodilating effect in obstructive lung disease. As opposed to the least hydrophobic drugs salbutamol and formoterol, the more hydrophobic long-acting β2-agonist (LABA) salmeterol promoted siRNA delivery in both cell types for both uncoated and surfactant-coated nanogels, whereas indacaterol showed this effect solely in lung epithelial cells. Our results demonstrate the potential of both salmeterol and indacaterol to be repurposed as adjuvants for nanocarrier-mediated siRNA delivery to the lung, which could provide opportunities for drug combination therapy.

Periodontitis aggravates COPD through the activation of γδ T cell and M2 macrophage

Chronic obstructive pulmonary disease (COPD) is a chronic systemic inflammatory disease with high morbidity and mortality. Periodontitis exacerbates COPD progression; however, the immune mechanisms by which periodontitis affects COPD remain unclear. Here, by constructing periodontitis and COPD mouse models, we demonstrated that periodontitis and COPD could mutually aggravate disease progression. For the first time, we found that the progression was associated with the activation of γδ T cells and M2 macrophages, and M2 polarization of macrophages was affected by γδ T cells activation. In the lung tissues of COPD with periodontitis, the activation of γδ T cells finally led to the increase of IL 17 and IFN γ expression and M2 macrophage polarization. Furthermore, we found that the periodontitis-associated bacteria Porphyromonas gingivalis (P. gingivalis) promoted the activation of γδ T cells and M2 macrophages ex vivo. The data from clinical bronchoalveolar lavage fluid (BALF) samples were consistent with the in vivo and ex vivo experiments. For the first time, our results identified the crucial role of γδ T-M2 immune mechanism in mediating periodontitis-promoted COPD progression. Therefore, targeting at periodontitis treatment and the γδ T-M2 immune mechanism might provide a new practical strategy for COPD prevention or control.IMPORTANCEPeriodontitis exacerbates chronic obstructive pulmonary disease (COPD) progression. For the first time, the current study identified that the impact of periodontitis on COPD progression was associated with the activation of γδ T cells and M2 macrophages and that M2 polarization of macrophages was affected by γδ T cells activation. The results indicated that targeting at periodontitis treatment and the γδ T-M2 immune mechanism might provide a new practical strategy for COPD prevention or control.

Inhalation of Citrus Reticulata essential oil alleviates airway inflammation and emphysema in COPD rats through regulation of macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory respiratory disease. Citrus Reticulata peel, the dried ripe peel of Citrus Reticulata species, has been found to have anti-inflammatory and cough attenuation effects. However, the therapeutic effects and its precise underlying mechanisms of atomizing inhalation using Citrus Reticulata essential oil (CREO) have not yet been fully elucidated.

AIM OF THE STUDY

The aim of this study was to assess the therapeutic effects of Citrus Reticulata essential oil and its associated anti-inflammatory mechanisms in COPD rat model.

METHODS

A total of 80 SD rats were randomized into four groups: control group (Con), COPD model group (COPD), COPD + ipratropium bromide (IB), and COPD + citrus reticulata essential oil (CREO). To induce COPD in rats, cigarette smoke (CS) exposure was used, while CREO and IB groups were administered through atomizing inhalation. The clinical signs, pathological lesions of the lung, percentages of antigen-presenting lung macrophages (CD11b/c+/CD86+ cells) and CD8+ T cells, and the content and mRNA expression of cytokines of the lung were analyzed.

RESULTS

The findings revealed that atomizing inhalation of Citrus reticulata essential oil had therapeutic effects on COPD rats. The treatment resulted in improvement in the body weight and mental status of COPD rats, reduced pathological injury of the lung, and increased proportion of CD11b/c+/CD86+ cells in lung macrophages, while also decreasing the number of CD8+ T cells. In addition, the Citrus Reticulata essential oil reduced the contents of IL-18, IL-17A, IL-12p70, and GM-CSF, downregulated the relative mRNA expression of IFN-γ, IL-4, and MMP-12, and upregulated the mRNA expression of IL-10.

CONCLUSIONS

Citrus reticulata essential oil can alleviate histological injury of the lung and regulate macrophages and CD8+ T cells in COPD rats. The study suggests that citrus reticulata essential oil could be a potential therapeutic agent for COPD.

The role of extracellular vesicles in COPD and potential clinical value

Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung disease and a major health burden worldwide. Extracellular vesicles (EVs) are nanosized vesicles which possess a lipid bilayer structure that are secreted by various cells. They contain a variety of bioactive substances, which can regulate various physiological and pathological processes and are closely related to the development of diseases. Recently, EVs have emerged as a novel tool for intercellular crosstalk, which plays an essential role in COPD development. This paper reviews the role of EVs in the development of COPD and their potential clinical value, in order to provide a reference for further research on COPD.

Increased oxidative stress responses in murine macrophages exposed at the air-liquid interface to third- and fourth-generation electronic nicotine delivery system (ENDS) aerosols

Background

New fourth generation electronic nicotine delivery system (ENDS) devices contain high levels of nicotine salt (up to 60 mg/mL), whose cellular and molecular effects on immune cells are currently unknown. Here, we used a physiologically-relevant in vitro air-liquid interface (ALI) exposure model to assess the toxicity of distinct ENDS, a 3rd-generation electronic-cigarette (e-cig) and two 4th-generation ENDS devices (JUUL and Posh Plus).

Methods

Murine macrophages (RAW 264.7) were exposed at the ALI to either air, Menthol or Crème Brûlée-flavored ENDS aerosols generated from those devices for 1-hour per day for 1 or 3 consecutive days. Cellular and molecular toxicity was evaluated 24 h post-exposure.

Results

1-day of Menthol-flavored JUUL aerosol exposure significantly decreased cell viability and significantly increased lactate dehydrogenase (LDH) levels compared to air controls. Further, JUUL Menthol elicited significantly increased reactive oxygen species (ROS) and nitric oxide (NO) production compared to air controls. Posh Crème Brûlée-flavored aerosols displayed significant cytotoxicity - decreased cell viability and increased LDH levels -after 1- and 3-day exposures, while the Crème Brûlée-flavored aerosol produced by the 3rd-generation e-cig device only displayed significant cytotoxicity after 3 days compared to air controls. Further, both Posh and third-generation e-cig Crème Brûlée flavored-aerosols elicited significantly increased ROS plus high levels of 8-isoprostane after 1 and 3 days compared to air controls, indicating increased oxidative stress. Posh and third-generation e-cig Crème Brûlée flavored-aerosols elicited reduction in NO levels after one day, but elicited increase in NO after 3 days. Genes in common dysregulated by both devices after 1 day included α7nAChR, Cyp1a1, Ahr, Mmp12, and iNos.

Conclusion

Our results suggest that ENDS Menthol and Crème Brûlée-flavored aerosol exposures from both 3rd- and 4th-generation ENDS devices are cytotoxic to macrophages and cause oxidative stress. This can translate into macrophage dysfunction. Although 4th-generation disposable ENDS devices have no adjustable operational settings and are considered low-powered ENDS devices, their aerosols can induce cellular toxicity compared to air-exposed control cells. This study provides scientific evidence for regulation of nicotine salt-based disposable ENDS products.

Advances in the investigation of the role of autophagy in the etiology of chronic obstructive pulmonary disease: A review

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory illness. It arises from emphysema and chronic bronchitis and is characterized by progressive and irreversible airflow limitation and chronic inflammation of the lungs, which eventually progresses to pulmonary hypertension, chronic pulmonary heart disease and respiratory failure. Autophagy is a highly conserved cellular homeostasis maintenance mechanism that involves the transport of damaged organelles and proteins to lysosomes for destruction. Dysregulation of autophagy is one of the pathogenic mechanisms of many diseases and is strongly associated with the development of COPD, although the precise mechanisms are unknown. In this paper, we focus on macroautophagy, a type of autophagy that has been thoroughly studied, and describe the characteristics, processes, regulatory pathways, and functions of autophagy, and discuss its relationship with COPD from the perspectives of inflammation, emphysema, mucus hypersecretion, cilia structure and function, airway remodeling, vascular remodeling, and bacterial infections, with a view to searching for the therapeutic targets of COPD from the perspective of autophagy, which is hoped to be helpful for the clinical treatment.

The role of lncRNA in the pathogenesis of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by progressive and irreversible airflow obstruction with abnormal lung function. Because its pathogenesis involves multiple aspects of oxidative stress, immunity and inflammation, apoptosis, airway and lung repair and destruction, the clinical approach to COPD treatment is not further updated. Therefore, it is crucial to discover a new means of COPD diagnosis and treatment. COPD etiology is associated with complex interactions between environmental and genetic determinants. Numerous genes are involved in the pathogenic process of this illness in research samples exposed to hazardous environmental conditions. Among them, Long non-coding RNAs (lncRNAs) have been reported to be involved in the molecular mechanisms of COPD development induced by different environmental exposures and genetic susceptibility encounters, and some potential lncRNA biomarkers have been identified as early diagnostic, disease course determination, and therapeutic targets for COPD. In this review, we summarize the expression profiles of the reported lncRNAs that have been reported in COPD studies related to environmental risk factors such as smoking and air pollution exposure and provided an overview of the roles of those lncRNAs in the pathogenesis of the disease.

Regulatory T cell adoptive transfer alters uterine immune populations, increasing a novel MHC-IIlow macrophage associated with healthy pregnancy

Intrauterine fetal demise (IUFD) - fetal loss after 20 weeks - affects 6 pregnancies per 1,000 live births in the United States, and the majority are of unknown etiology. Maternal systemic regulatory T cell (Treg) deficits have been implicated in fetal loss, but whether mucosal immune cells at the maternal-fetal interface contribute to fetal loss is under-explored. We hypothesized that the immune cell composition and function of the uterine mucosa would contribute to the pathogenesis of IUFD. To investigate local immune mechanisms of IUFD, we used the CBA mouse strain, which naturally has mid-late gestation fetal loss. We performed a Treg adoptive transfer and interrogated both pregnancy outcomes and the impact of systemic maternal Tregs on mucosal immune populations at the maternal-fetal interface. Treg transfer prevented fetal loss and increased an MHC-IIlow population of uterine macrophages. Single-cell RNA-sequencing was utilized to precisely evaluate the impact of systemic Tregs on uterine myeloid populations. A population of C1q+, Trem2+, MHC-IIlow uterine macrophages were increased in Treg-recipient mice. The transcriptional signature of this novel uterine macrophage subtype is enriched in multiple studies of human healthy decidual macrophages, suggesting a conserved role for these macrophages in preventing fetal loss.

A multi-organ, lung-derived inflammatory response following in vitro airway exposure to cigarette smoke and next-generation nicotine delivery products

Despite increasing use of in vitro models that closely resemble in vivo human biology, their application in understanding downstream effects of airway toxicity, such as inflammation, are at an early stage. In this study, we used various assays to examine the inflammatory response induced in MucilAir™ tissues and A549 cells exposed to three products known to induce toxicity. Reduced barrier integrity was observed in tissues following exposure to each product, with reduced viability and increased cytotoxicity also shown. Similar changes in viability were also observed in A549 cells. Furthermore, whole cigarette smoke (CS) induced downstream phenotypic THP-1 changes and endothelial cell adhesion, an early marker of atherosclerosis. In contrast, exposure to next-generation delivery product (NGP) aerosol did not induce this response. Cytokine, histological and RNA analysis highlighted increased biomarkers linked to inflammatory pathways and immune cell differentiation following exposure to whole cigarette smoke, including GM-CSF, IL-1β, cleaved caspase-3 and cytochrome P450 enzymes. As a result of similar observations in human airway inflammation, we propose that our exposure platform could act as a representative model for studying such events in vitro. Furthermore, this model could be used to test the inflammatory or anti-inflammatory impact posed by inhaled compounds delivered to the lung.

Mechanisms and Effects of Macrophage Polarization and Its Specifics in Pulmonary Environment

Macrophages are a specific group of cells found in all body tissues. They have specific characteristics in each of the tissues that correspond to the functional needs of the specific environment. These cells are involved in a wide range of processes, both pro-inflammatory and anti-inflammatory ("wound healing"). This is due to their specific capacity for so-called polarization, a phenotypic change that is, moreover, partially reversible compared to other differentiated cells of the human body. This promises a wide range of possibilities for its influence and thus therapeutic use. In this article, we therefore review the mechanisms that cause polarization, the basic classification of polarized macrophages, their characteristic markers and the effects that accompany these phenotypic changes. Since the study of pulmonary (and among them mainly alveolar) macrophages is currently the focus of scientific interest of many researchers and these macrophages are found in very specific environments, given mainly by the extremely high partial pressure of oxygen compared to other locations, which specifically affects their behavior, we will focus our review on this group.

Modulation of Alveolar Macrophage Activity by Eugenol Attenuates Cigarette-Smoke-Induced Acute Lung Injury in Mice

This study investigates the role of eugenol (EUG) on CS-induced acute lung injury (ALI) and how this compound is able to modulate macrophage activity. C57BL/6 mice were exposed to 12 cigarettes/day/5days and treated 15 min/day/5days with EUG. Rat alveolar macrophages (RAMs) were exposed to CSE (5%) and treated with EUG. In vivo, EUG reduced morphological changes inflammatory cells, oxidative stress markers, while, in vitro, it induced balance in the oxidative stress and reduced the pro-inflammatory cytokine release while increasing the anti-inflammatory one. These results suggest that eugenol reduced CS-induced ALI and acted as a modulator of macrophage activity.

Extracellular vesicles and COPD: foe or friend?

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory airway disease characterized by progressive airflow limitation. The complex biological processes of COPD include protein hydrolysis tissue remodeling, innate immune inflammation, disturbed host-pathogen response, abnormal cellular phenotype conversion, and cellular senescence. Extracellular vesicles (EVs) (including apoptotic vesicles, microvesicles and exosomes), are released by almost all cell types and can be found in a variety of body fluids including blood, sputum and urine. EVs are key mediators in cell-cell communication and can be used by using their bioactive substances (DNA, RNA, miRNA, proteins and other metabolites) to enable cells in adjacent and distant tissues to perform a wide variety of functions, which in turn affect the physiological and pathological functions of the body. Thus, EVs is expected to play an important role in the pathogenesis of COPD, which in turn affects its acute exacerbations and may serve as a diagnostic marker for it. Furthermore, recent therapeutic approaches and advances have introduced EVs into the treatment of COPD, such as the modification of EVs into novel drug delivery vehicles. Here, we discuss the role of EVs from cells of different origins in the pathogenesis of COPD and explore their possible use as biomarkers in diagnosis, and finally describe their role in therapy and future prospects for their application. Graphical Abstract.

GSPE attenuates CSE-induced lung inflammation and emphysema by regulating autophagy via the reactive oxygen species/TFEB signaling pathway

Cigarette smoke can enhance reactive oxygen species (ROS) production in inflammatory and epithelial cells. Subsequently, ROS enhance autophagy-induced inflammation due to alveolar macrophages (AMs), the primary source of cytokines implicated in chronic obstructive pulmonary disease (COPD) pathogenesis. Therefore, we hypothesized that grape seed proanthocyanidin extract (GSPE), an effective antioxidant, could inhibit emphysema and airway inflammation by ameliorating cigarette smoke extract (CSE)-induced autophagy via suppressing oxidative stress in macrophages. We observed that GSPE significantly attenuated histological changes observed in CSE-induced emphysema and airway inflammation in the lungs of mice. Moreover, GSPE ameliorated lung inflammation by reducing the number of cells, macrophages, and neutrophils and the tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 levels measured in bronchioloalveolar lavage fluid. ROS levels increased after CSE instillation and significantly decreased with in vitro GSPE treatment. GSPE decreased transcription factor EB (TFEB) oxidation by reducing ROS, inhibiting TFEB nuclear translocation. Furthermore, GSPE inhibited ROS-induced autophagy in RAW 264.7 cells, bone marrow-derived macrophages, and AMs. Inhibiting autophagy through GSPE treatment diminishes CSE-induced lung inflammation by inhibiting the NLRP3 inflammasome. This study demonstrates that GSPE can ameliorate CSE-induced inflammation and emphysema via autophagy-induced NLRP3 inflammasome regulation through the ROS/TFEB signaling pathway in a COPD mouse model.

Human vasculature-on-a-chip with macrophage-mediated endothelial activation: The biological effect of aerosol from heated tobacco products on monocyte adhesion

Heated tobacco products (HTPs) are expected to have the potential to reduce risks of smoking-associated cardiovascular disease (CVD). However, mechanism-based investigations of the effect of HTPs on atherosclerosis remain insufficient and further studies under human-relevant situations are desired for deeper understanding of the reduced risk potential of HTPs. In this study, we first developed an in vitro model of monocyte adhesion by considering macrophage-derived proinflammatory cytokine-mediated endothelial activation using an organ-on-a-chip (OoC), which provided great opportunities to mimic major aspects of human physiology. Then biological activities of aerosol from three different types of HTPs in terms of monocyte adhesion were compared with that of cigarette smoke (CS). Our model showed that the effective concentration ranges of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were close to the actual condition in CVD pathogenesis. The model also showed that monocyte adhesion was less induced by each HTP aerosol than CS, which may be caused by less proinflammatory cytokine secretion. In summary, our vasculature-on-a-chip model assessed the difference in biological effects between cigarettes and HTPs, and suggested a reduced risk potential of HTPs for atherosclerosis.

Macrophage Polarization: An Important Candidate Regulator for Lung Diseases

Macrophages are crucial components of the immune system and play a critical role in the initial defense against pathogens. They are highly heterogeneous and plastic and can be polarized into classically activated macrophages (M1) or selectively activated macrophages (M2) in response to local microenvironments. Macrophage polarization involves the regulation of multiple signaling pathways and transcription factors. Here, we focused on the origin of macrophages, the phenotype and polarization of macrophages, as well as the signaling pathways associated with macrophage polarization. We also highlighted the role of macrophage polarization in lung diseases. We intend to enhance the understanding of the functions and immunomodulatory features of macrophages. Based on our review, we believe that targeting macrophage phenotypes is a viable and promising strategy for treating lung diseases.

The role of lung macrophages in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) as a common, preventable and treatable chronic respiratory disease in clinic, gets continuous deterioration and we can't take effective intervention at present. Lung macrophages (LMs) are closely related to the occurrence and development of COPD, but the specific mechanism is not completely clear. In this review we will focus on the role of LMs and potential avenues for therapeutic targeting for LMs in COPD.

Black carbon content in airway macrophages is associated with increased severe exacerbations and worse COPD morbidity in SPIROMICS

BACKGROUND

Airway macrophages (AM), crucial for the immune response in chronic obstructive pulmonary disease (COPD), are exposed to environmental particulate matter (PM), which they retain in their cytoplasm as black carbon (BC). However, whether AM BC accurately reflects environmental PM2.5 exposure, and can serve as a biomarker of COPD outcomes, is unknown.

METHODS

We analyzed induced sputum from participants at 7 of 12 sites SPIROMICS sites for AM BC content, which we related to exposures and to lung function and respiratory outcomes. Models were adjusted for batch (first vs. second), age, race (white vs. non-white), income (<$35,000, $35,000~$74,999, ≥$75,000, decline to answer), BMI, and use of long-acting beta-agonist/long-acting muscarinic antagonists, with sensitivity analysis performed with inclusion of urinary cotinine and lung function as covariates.

RESULTS

Of 324 participants, 143 were current smokers and 201 had spirometric-confirmed COPD. Modeled indoor fine (< 2.5 μm in aerodynamic diameter) particulate matter (PM2.5) and urinary cotinine were associated with higher AM BC. Other assessed indoor and ambient pollutant exposures were not associated with higher AM BC. Higher AM BC was associated with worse lung function and odds of severe exacerbation, as well as worse functional status, respiratory symptoms and quality of life.

CONCLUSION

Indoor PM2.5 and cigarette smoke exposure may lead to increased AM BC deposition. Black carbon content in AMs is associated with worse COPD morbidity in current and former smokers, which remained after sensitivity analysis adjusting for cigarette smoke burden. Airway macrophage BC, which may alter macrophage function, could serve as a predictor of experiencing worse respiratory symptoms and impaired lung function.

Role of Monocytes/Macrophages in the Etiology of Bullous Keratopathy After Argon Laser Iridotomy

Purpose

The etiologic mechanisms of bullous keratopathy (BK) after argon laser iridotomy (ALI) are still unknown. Therefore, we investigated potential mechanisms on BK after ALI.

Methods

Corneal endothelial surface obtained in penetrating keratoplasty for BK after ALI was observed and analyzed immunohistochemically. We investigated how various leukocytes react to cultured human corneal endothelial cells in an inflamed condition and monocytes/macrophages respond to the iris treated by an argon and YAG laser or pigmented and nonpigmented iris treated by an argon laser.

Results

We detected infiltration of CD68- and CD11b-positive monocytes/macrophages in the posterior surface of trephined corneas obtained during penetrating keratoplasty for BK after ALI in three of the seven eyes with ALI. In vitro, monocytes/macrophages, but not T cells, B cells, neutrophils, or pan-leukocytes, removed many cultured human corneal endothelial cells in the medium stimulated with proinflammatory cytokines. Human pigmented iris tissues treated by the argon laser, but not those treated by the YAG laser, attracted many monocytes/macrophages and formed large, round colonies. Human monocytes/macrophages formed large colonies on the argon laser–treated pigmented iris from C3H mice but not nonpigmented iris from albino BALB/c mice.

Conclusions

Our results suggest that monocytes/macrophages, argon laser, and pigmented iris are all involved in the pathogenesis of BK after LI.

Translational Relevance

Etiology in BK after ALI has not been clear, but our findings based on clinical and experimental findings give a critical clue to explain possible mechanisms on BK after ALI.

Human Pluripotent Stem Cell-Derived Alveolar Organoid with Macrophages

Alveolar organoids (AOs), derived from human pluripotent stem cells (hPSCs) exhibit lung-specific functions. Therefore, the application of AOs in pulmonary disease modeling is a promising tool for understanding disease pathogenesis. However, the lack of immune cells in organoids limits the use of human AOs as models of inflammatory diseases. In this study, we generated AOs containing a functional macrophage derived from hPSCs based on human fetal lung development using biomimetic strategies. We optimized culture conditions to maintain the iMACs (induced hPSC-derived macrophages) AOs for up to 14 days. In lipopolysaccharide (LPS)-induced inflammatory conditions, IL-1β, MCP-1 and TNF-α levels were significantly increased in iMAC-AOs, which were not detected in AOs. In addition, chemotactic factor IL-8, which is produced by mononuclear phagocytic cells, was induced by LPS treatment in iMACs-AOs. iMACs-AOs can be used to understand pulmonary infectious diseases and is a useful tool in identifying the mechanism of action of therapeutic drugs in humans. Our study highlights the importance of immune cell presentation in AOs for modeling inflammatory pulmonary diseases.

Association between chronic obstructive pulmonary disease and periodontitis: The common role of innate immune cells?

Innate immune cells are of broad interest in a variety of diseases. These cells include neutrophils, macrophages, dendritic cells and mast cells, etc. Innate immune cells are often mentioned in inflammatory diseases as the first line of defense against pathogens' invasion. As chronic obstructive pulmonary disease and periodontitis are inflammatory diseases, innate immune cells play an important role in the development of both diseases. COPD and periodontitis are common epidemic diseases with a very high prevalence, thus affecting a large number of people and also reducing the quality of life of patients. In addition, epidemiological studies suggested a link between the two, creating a co-morbid burden, but the mechanism of the link is yet to be explained. This article discusses the possible mechanism of the link between the two diseases in terms of innate immune cells and discusses possible future targeted therapies that could alleviate the burden on patients.

A Sedentary and Unhealthy Lifestyle Fuels Chronic Disease Progression by Changing Interstitial Cell Behaviour: A Network Analysis

Managing chronic diseases, such as heart disease, stroke, diabetes, chronic lung disease and Alzheimer’s disease, account for a large proportion of health care spending, yet they remain in the top causes of premature mortality and are preventable. It is currently accepted that an unhealthy lifestyle fosters a state of chronic low-grade inflammation that is linked to chronic disease progression. Although this is known to be related to inflammatory cytokines, how an unhealthy lifestyle causes cytokine release and how that in turn leads to chronic disease progression are not well known. This article presents a theory that an unhealthy lifestyle fosters chronic disease by changing interstitial cell behavior and is supported by a six-level hierarchical network analysis. The top three networks include the macroenvironment, social and cultural factors, and lifestyle itself. The fourth network includes the immune, autonomic and neuroendocrine systems and how they interact with lifestyle factors and with each other. The fifth network identifies the effects these systems have on the microenvironment and two types of interstitial cells: macrophages and fibroblasts. Depending on their behaviour, these cells can either help maintain and restore normal function or foster chronic disease progression. When macrophages and fibroblasts dysregulate, it leads to chronic low-grade inflammation, fibrosis, and eventually damage to parenchymal (organ-specific) cells. The sixth network considers how macrophages change phenotype. Thus, a pathway is identified through this hierarchical network to reveal how external factors and lifestyle affect interstitial cell behaviour. This theory can be tested and it needs to be tested because, if correct, it has profound implications. Not only does this theory explain how chronic low-grade inflammation causes chronic disease progression, it also provides insight into salutogenesis, or the process by which health is maintained and restored. Understanding low-grade inflammation as a stalled healing process offers a new strategy for chronic disease management. Rather than treating each chronic disease separately by a focus on parenchymal pathology, a salutogenic strategy of optimizing interstitial health could prevent and mitigate multiple chronic diseases simultaneously.

Early taurine administration as a means for halting the cytokine storm progression in COVID-19 patients

Around the world, more than 6.2 million individuals have died as a result of coronavirus disease 2019 (COVID-19). According to a recent survey conducted among immunologists, epidemiologists, and virologists, this disease is expected to become endemic. This implies that the disease could have a continuous presence and/or normal frequency in the population. Pharmacological interventions to prevent infection, as well as to treat the patients at an early phase of illness to avoid hospitalization are essential additions to the vaccines. Taurine is known to inhibit the generation of all inflammatory mediators linked to the cytokine storm. It can also protect against lung injury by suppressing increased oxidants production and promoting the resolution of the inflammatory process. Neutrophil lactoferrin degranulation stimulated by taurine may have antiviral effects against SARS-CoV-2, limiting viral replication. It is hypothesized that if taurine is administered early in the onset of COVID-19 disease, it may stop the cytokine storm from progressing, lowering morbidity and mortality.

Recruitment of monocytes primed to express heme oxygenase-1 ameliorates pathological lung inflammation in cystic fibrosis

Overwhelming neutrophilic inflammation is a leading cause of lung damage in many pulmonary diseases, including cystic fibrosis (CF). The heme oxygenase-1 (HO-1)/carbon monoxide (CO) pathway mediates the resolution of inflammation and is defective in CF-affected macrophages (MΦs). Here, we provide evidence that systemic administration of PP-007, a CO releasing/O₂ transfer agent, induces the expression of HO-1 in a myeloid differentiation factor 88 (MyD88) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)-dependent manner. It also rescues the reduced HO-1 levels in CF-affected cells induced in response to lipopolysaccharides (LPS) or Pseudomonas aeruginosa (PA). Treatment of CF and muco-obstructive lung disease mouse models with a single clinically relevant dose of PP-007 leads to effective resolution of lung neutrophilia and to decreased levels of proinflammatory cytokines in response to LPS. Using HO-1 conditional knockout mice, we show that the beneficial effect of PP-007 is due to the priming of circulating monocytes trafficking to the lungs in response to infection to express high levels of HO-1. Finally, we show that PP-007 does not compromise the clearance of PA in the setting of chronic airway infection. Overall, we reveal the mechanism of action of PP-007 responsible for the immunomodulatory function observed in clinical trials for a wide range of diseases and demonstrate the potential use of PP-007 in controlling neutrophilic pulmonary inflammation by promoting the expression of HO-1 in monocytes/macrophages.

The activity of an enzyme that is significantly reduced in cystic fibrosis (CF) could be boosted by an existing drug, reducing lung inflammation and associated tissue damage. Chronic inflammation in CF is currently treated using long-term corticosteroids which may leave patients immuno-suppressed, or high-dose ibuprofen, which is not well tolerated. Scientists hope to find alternative therapies targeting chronic inflammation. Emanuela Bruscia, Caterina Di Pietro (Yale University, New Haven, USA) and co-workers examined the mechanisms of action of the first-in-class drug PP-007 (Prolong Pharmaceuticals®) and assessed its potential for controlling inflammation in CF. Patients with CF have reduced expression of the heme oxygenase-1 enzyme in immune cells called monocytes. In CF mouse models, treatment with PP-007 boosted the expression of this enzyme in circulating monocytes. The treatment reduced levels of proinflammatory proteins and associated lung damage.

A century of attempts to develop an effective tuberculosis vaccine: Why they failed?

Tuberculosis (TB) remains a major global health problem despite widespread use of the Bacillus BCG vaccine. This situation is worsened by co-infection with HIV, and the development of multidrug-resistant Mycobacterium tuberculosis (Mtb) strains. Thus, novel vaccine candidates and improved vaccination strategies are urgently needed in order to reduce the incidence of TB and even to eradicate TB by 2050. Over the last few decades, 23 novel TB vaccines have entered into clinical trials, more than 13 new vaccines have reached various stages of preclinical development, and more than 50 potential candidates are in the discovery stage as next-generation vaccines. Nevertheless, why has a century of attempts to introduce an effective TB vaccine failed? Who should be blamed -scientists, human response, or Mtb strategies? Literature review reveals that the elimination of latent or active Mtb infections in a given population seems to be an epigenetic process. With a better understanding of the connections between bacterial infections and gene expression conditions in epigenetic events, opportunities arise in designing protective vaccines or therapeutic agents, particularly as epigenetic processes can be reversed. Therefore, this review provides a brief overview of different approaches towards novel vaccination strategies and the mechanisms underlying these approaches.

Secretome of Mesenchymal Stem Cells from Consecutive Hypoxic Cultures Promotes Resolution of Lung Inflammation by Reprogramming Anti-Inflammatory Macrophages

The secretome from hypoxia-preconditioned mesenchymal stem cells (MSCs) has been shown to promote resolution of inflammation and alleviate acute lung injury (ALI) through its immunomodulatory function. However, the effects of consecutive hypoxic culture on immunomodulatory function of the MSCs secretome are largely unclarified. Here, we intend to investigate the effects of consecutive hypoxia on therapeutic efficacy of conditioned medium derived from MSCs (MSCs-CM) in alleviating ALI. Human umbilical cord-derived MSCs (UC-MSCs) were consecutively cultured in 21% O₂ (Nor-MSCs) or in 1% O₂ (Hypo-MSCs) from passage 0. Their conditioned medium (Nor-CM and Hypo-CM respectively) was collected and administered into ALI models. Our findings confirmed that Hypo-MSCs exhibited increased proliferation ability and decreased cell senescence compared with Nor-MSCs. Consecutive hypoxia promoted UC-MSCs to secrete immunomodulatory cytokines, such as insulin-like growth factor 1(IGF1), IL10, TNFα-stimulated gene 6(TSG6), TGFβ, and prostaglandin E2 (PGE2). Both Nor-CM and Hypo-CM could effectively limit lung inflammation, promote efferocytosis and modulate anti-inflammatory polarization of lung macrophages in ALI models. Moreover, the effects of Hypo-CM were more potent than Nor-CM. Taken together, our findings indicate that consecutive hypoxic cultures could not only promote both proliferation and quality of UC-MSCs, but also enhance the therapeutic efficacy of their secretome in mitigating lung inflammation by promoting efferocytosis and anti-inflammatory polarization of macrophages.

Exploring the Change of Host and Microorganism in Chronic Obstructive Pulmonary Disease Patients Based on Metagenomic and Metatranscriptomic Sequencing

Background

Chronic obstructive pulmonary disease (COPD) is a universal respiratory disease resulting from the complex interactions between genes and environmental conditions. The process of COPD is deteriorated by repeated episodes of exacerbations, which are the primary reason for COPD-related morbidity and mortality. Bacterial pathogens are commonly identified in patients’ respiratory tracts both in the stable state and during acute exacerbations, with significant changes in the prevalence of airway bacteria occurring during acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Therefore, the changes in microbial composition and host inflammatory responses will be necessary to investigate the mechanistic link between the airway microbiome and chronic pulmonary inflammation in COPD patients.

Methods

We performed metatranscriptomic and metagenomic sequencing on sputum samples for twelve AECOPD patients before treatment and for four of them stable COPD (stabilization of AECOPD patients after treatment). Sequencing reads were classified by Kraken2, and the host gene expression was analyzed by Hisat2 and HTseq. The correlation between genes was obtained by the Spearman correlation coefficient. Mann–Whitney U-test was applied to identify microbes that exhibit significantly different distribution in two groups.

Results

At the phyla level, the top 5 dominant phyla were Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes, and Fusobacteria. The proportion of dominant gates in metagenomic data was similar in metatranscriptomic data. There were significant differences in the abundance of specific microorganisms at the class level between the two methods. No significant difference between AECOPD and stable COPD was found. However, the different expression levels of 5 host genes were significantly increased in stable COPD and were involved in immune response and inflammatory pathways, which were associated with macrophages.

Conclusion

Our study may provide a clue to investigate the mechanism of COPD and potential biomarkers in clinical diagnosis and treatment.

The Emerging Role of Macrophages in Chronic Obstructive Pulmonary Disease: The Potential Impact of Oxidative Stress and Extracellular Vesicle on Macrophage Polarization and Function

Chronic obstructive pulmonary disease (COPD) is one of the most common airway diseases, and it is considered a major global health problem. Macrophages are the most representative immune cells in the respiratory tract, given their role in surveying airways, removing cellular debris, immune surveillance, and resolving inflammation. Macrophages exert their functions by adopting phenotypical changes based on the stimuli they receive from the surrounding tissue. This plasticity is described as M1/M2 macrophage polarization, which consists of a strictly coordinated process leading to a difference in the expression of surface markers, the production of specific factors, and the execution of biological activities. This review focuses on the role played by macrophages in COPD and their implication in inflammatory and oxidative stress processes. Particular attention is on macrophage polarization, given macrophage plasticity is a key feature in COPD. We also discuss the regulatory influence of extracellular vesicles (EVs) in cell-to-cell communications. EV composition and cargo may influence many COPD-related aspects, including inflammation, tissue remodeling, and macrophage dysfunctions. These findings could be useful for better addressing the role of macrophages in the complex pathogenesis and outcomes of COPD.

Pathogenesis of COPD at the cellular and molecular level

Chronic inflammatory responses in the lung of patients with stable mild-to severe forms of COPD play a central role in the definition, comprehension and monitoring of the disease state. A better understanding of the COPD pathogenesis can't avoid a detailed knowledge of these inflammatory changes altering the functional health of the lung during the disease progression. We here summarize and discuss the role and principal functions of the inflammatory cells populating the large, small airways and lung parenchyma of patients with COPD of increasing severity in comparison with healthy control subjects: T and B lymphocytes, NK and Innate Lymphoid cells, macrophages, and neutrophils. The differential inflammatory distribution in large and small airways of patients is also discussed. Furthermore, relevant cellular mechanisms controlling the homeostasis and the "normal" balance of these inflammatory cells and of structural cells in the lung, such as autophagy, apoptosis, necroptosis and pyroptosis are as well presented and discussed in the context of the COPD severity.

Role of CC Chemokine Ligand 17 in Mouse Models of Chronic Obstructive Pulmonary Disease

Lung function deterioration is significantly associated with poor prognosis in patients with chronic obstructive pulmonary disease (COPD). We previously reported that CC chemokine ligand 17/thymus and activation-regulated chemokine (CCL17/TARC) could be a predictive factor of lung function decline in patients with COPD. However, the role of CCL17 in the pathogenesis of COPD is unclear. Here we examined the role of CCL17 in lung inflammation using mouse COPD models. Exposure to cigarette smoking induced CCL17 production in bronchial epithelial cells and accumulation of alveolar macrophages in the lungs. Intranasal administration of recombinant CCL17 further enhanced cigarette smoke-induced macrophage accumulation and also aggravated elastase-induced pulmonary emphysema. We confirmed that cigarette smoke extract as well as H₂O₂ upregulated CCL17 in BAES-2B cells. Of note, macrophages of both M1 and M2 surface markers were accumulated by cigarette smoke. Both alveolar macrophage accumulation via exposure to cigarette smoking and emphysematous changes induced by elastase administration were significantly reduced in CCL17-deficient mice. We further demonstrated that CCL17 strongly induced the expression of CC chemokine ligand 2 (CCL2), a chemoattractant for macrophages, in RAW264.7 cells, and its production was inhibited by knockdown of CCR4, the receptor of CCL17. Collectively, the present results demonstrate that CCL17 is produced by lung epithelial cells upon cigarette smoke (CS) exposure. Furthermore, CCL17 is involved in CS-induced accumulation of alveolar macrophages and development of elastase-induced pulmonary emphysema, possibly through CCL17-induced production of CCL2 by macrophages. Our findings may provide a new insight into the pathogenesis of COPD.

Identification of Potential Key Genes in the Pathogenesis of Chronic Obstructive Pulmonary Disease Through Bioinformatics Analysis

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease with high morbidity and mortality. The etiology of COPD is complex, and the pathogenesis mechanisms remain unclear. In this study, we used rat and human COPD gene expression data from our laboratory and the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) between individuals with COPD and healthy individuals. Then, protein–protein interaction (PPI) networks were constructed, and hub genes were identified. Cytoscape was used to construct the co-expressed network and competitive endogenous RNA (ceRNA) networks. A total of 198 DEGs were identified, and a PPI network with 144 nodes and 355 edges was constructed. Twelve hub genes were identified by the cytoHubba plugin in Cytoscape. Of these genes, CCR3, CCL2, COL4A2, VWF, IL1RN, IL2RA, and CCL13 were related to inflammation or immunity, or tissue-specific expression in lung tissue, and their messenger RNA (mRNA) levels were validated by qRT-PCR. COL4A2, VWF, and IL1RN were further verified by the GEO dataset GSE76925, and the ceRNA network was constructed with Cytoscape. These three genes were consistent with COPD rat model data compared with control data, and their dysregulation direction was reversed when the COPD rat model was treated with effective-component compatibility of Bufei Yishen formula III. This bioinformatics analysis strategy may be useful for elucidating novel mechanisms underlying COPD. We pinpointed three key genes that may play a role in COPD pathogenesis and therapy, which deserved to be further studied.

Effective-components combination improves airway remodeling in COPD rats by suppressing M2 macrophage polarization via the inhibition of mTORC2 activity

BACKGROUND

In chronic obstructive pulmonary disease (COPD), M2 macrophages release multiple tissue repair-related factors, leading to airway remodeling, a significant pathological characteristic. Meanwhile, effective-components combination (ECC), derived from Bufei Yishen formula (BYF), is an effective treatment for COPD.

PURPOSE

To determine the potential mechanisms of ECC in airway remodeling in COPD by suppressing M2 macrophage polarization.

METHODS

We established a rat COPD Model using exposure to cigarette smoke and bacterial infection to investigate the efficacy of ECC. We also treated macrophages with IL-4 for 12 h to explore the in vivo effect of ECC on M2 macrophage polarization and mTORC2 signals.

RESULTS

The disease severity of COPD rats could be alleviated by ECC treatment, which improved pulmonary function and alleviated pathological injuries in lung tissue and the inflammatory cytokine levels. Meanwhile, ECC could ameliorate airway remodeling by reducing collagen deposition, hindering airway mucus hypersecretion and smooth muscle cell proliferation, and reducing the number of M2 macrophages in the lung tissues of COPD rats. Furthermore, with IL-4-induced macrophages, we found that ECC could suppress M2 macrophage polarization by decreasing the levels of M2 macrophage markers. Finally, we discovered that ECC inhibited mTORC2 activity by examining p-mTOR²⁴⁸¹ and its downstream protein p-Akt⁴⁷³.

CONCLUSIONS

ECC exerts beneficial effects on airway remodeling in COPD rats, likely by suppressing M2 macrophage polarization via the inhibition of mTORC2 activity.

Immunofluorescence-guided segmentation of three-dimensional features in micro-computed tomography datasets of human lung tissue

Micro-computed tomography (µCT) provides non-destructive three-dimensional (3D) imaging of soft tissue microstructures. Specific features in µCT images can be identified using correlated two-dimensional (2D) histology images allowing manual segmentation. However, this is very time-consuming and requires specialist knowledge of the tissue and imaging modalities involved. Using a custom-designed µCT system optimized for imaging unstained formalin-fixed paraffin-embedded soft tissues, we imaged human lung tissue at isotropic voxel sizes less than 10 µm. Tissue sections were stained with haematoxylin and eosin or cytokeratin 18 in columnar airway epithelial cells using immunofluorescence (IF), as an exemplar of this workflow. Novel utilization of tissue autofluorescence allowed automatic alignment of 2D microscopy images to the 3D µCT data using scripted co-registration and automated image warping algorithms. Warped IF images, which were accurately aligned with the µCT datasets, allowed 3D segmentation of immunoreactive tissue microstructures in the human lung. Blood vessels were segmented semi-automatically using the co-registered µCT datasets. Correlating 2D IF and 3D µCT data enables accurate identification, localization and segmentation of features in fixed soft lung tissue. Our novel correlative imaging workflow provides faster and more automated 3D segmentation of µCT datasets. This is applicable to the huge range of formalin-fixed paraffin-embedded tissues held in biobanks and archives.

[Liuwei Buqi capsule modulates immune function by targeting multiple immune cell subsets in lung tissue of patients with COPD]

OBJECTIVE

To investigate the characteristics of immune cell subsets in the lung tissues of patients with chronic obstructive pulmonary disease (COPD) and the mechanism of Liuwei Buqi capsule in modulating immune and inflammatory imbalance in COPD.

METHODS

We downloaded COPD-related single-cell RNA sequencing data from Gene Expression Omnibus (GEO) and identified COPD immune cell subsets using the Seurat package in the R software to construct an immune cell subsets-differential genes network. The target genes and active ingredients of Liuwei Buqi capsule were obtained from the Chinese Medicine System Pharmacology Database and Analysis Platform (TCMSP), and the Liuwei Buqi capsule-immune cell subsets-target genes network was constructed by mapping the target genes to the differentially expressed genes in each immune cell subset. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was performed to analyze significantly enriched pathways of the target genes, and the key genes involved in the top 20 pathways were identified. In a rat model of COPD, we investigated the effects of Liuwei Buqi capsule on pulmonary function, lung tissue pathology, serum levels of IL-1β, NF-κB, and TNF-α, and expressions of IKBα, JNK, c-JUN, and c-FOS proteins in the lung tissue.

RESULTS

A total of 18 immune-related cell subsets, including macrophages and alveolar macrophages, were identified in both COPD patients and healthy control subjects, and the patients with COPD showed significant changes the percentages of macrophages, cDC1, pDC, mast cells, T cells, and mature dendritic cells (P < 0.05). Liuwei Buqi capsules targeted multiple immune cell subsets, and the identified target genes were enriched mostly in such immune and inflammation-related signaling pathways as lipids and atherosclerosis, IL-17 signaling pathway, Toll-like receptor signaling pathway, and TNF signaling pathway; the genes CXCL8, IL1B, JUN, NFKBIA, MAPK8, and FOS were the key genes involved in the significantly enriched pathways. In the rat models of COPD, treatment with Liuwei Buqi capsule significantly improved pulmonary function, alleviated lung pathologies, reduced serum levels of IL-1β, TNF-α, and NF-κB (P < 0.05) and pulmonary expressions of JNK, c-JUN, and c-FOS (P < 0.01) protein, and increased pulmonary expression of IκBα (P < 0.01).

CONCLUSION

Liuwei Buqi capsule may play an immunomodulatory role by targeting multiple immune cell subsets in the lung tissue of COPD patients.

Pulmonary macrophages and their different roles in health and disease

Macrophages are a heterogeneous population of myeloid cells with phenotype and function modulated according to the microenvironment in which they are found. The lung resident macrophages known as Alveolar Macrophages (AM) and Interstitial Macrophages (IM) are localized in two different compartments. During lung homeostasis, macrophages can remove inhaled particulates, cellular debris and contribute to some metabolic processes. Macrophages may assume a pro-inflammatory phenotype after being classically activated (M1) or anti-inflammatory when being alternatively activated (M2). M1 and M2 have different transcription profiles and act by eliminating bacteria, viruses and fungi from the host or repairing the damage triggered by inflammation, respectively. Nevertheless, macrophages also may contribute to lung damage during persistent inflammation or continuous exposure to antigens. In this review, we discuss the origin and function of pulmonary macrophages in the context of homeostasis, infectious and non-infectious lung diseases.

Transcriptomics Analysis Identifies the Presence of Upregulated Ribosomal Housekeeping Genes in the Alveolar Macrophages of Patients with Smoking-Induced Chronic Obstructive Pulmonary Disease

Background and Aims

Alveolar macrophages (AM) play a crucial role in the development of chronic obstructive pulmonary disease (COPD). The role that AM plays in the molecular pathways and clinical phenotypes associated with tobacco-related emphysema remain poorly understood. Thus, we investigated the transcriptomic profile of AM in COPD patients with a history of smoking and explored the molecular mechanisms associated with enriched pathways and hub genes.

Methods

Four data sets (GSE2125, GSE8823, GSE13896 and GSE130928) were retrieved from the GEO Database. A total of 203 GEO samples (GSM) were collated for this study. About 125 of these cases were classified as smokers (91 as healthy non-COPD smokers and 34 as COPD smokers). Based on the bioinformatics obtained using the R3.6.1 program, the data were successively adopted for differential genetic expression analysis, enrichment analysis (EA), and then protein–protein interaction analysis (PPI) in a STRING database. Finally, Cytoscape 3.8 software was used to screen the hub genes. A further data analysis was performed using a set of 154 cases, classified as 64 healthy non-smokers and 91 as healthy smokers. The same procedures were used as for the COPD dataset.

Results

When comparing the data pertaining to COPD-smokers and non-COPD smokers, the top ten genes with the greatest transcriptional differences were found to be NADK, DRAP1, DEDD, NONO, KLHL12, PRKAR1A, ITGAL, GLE1, SLC8A1, SVIL. A GSEA (Gene Set Enrichment Analysis) revealed that these genes manifested an up-regulated ribosomal pathway in contrast with other genes that exhibited an extensive down-regulated pathway. The hub genes were mainly genes encoding ribosomal subunits through PPI. Furthermore, it was found that there is a narrow transcriptional difference between healthy non-smokers and non-COPD smokers and the hub genes identified here are mainly members of the chemokines, including CCL5, CCR5, CXCL9 and CXCL11.

Conclusion

An elevated activity of the ribosome pathway in addition to the increased expression of ribosomal housekeeping genes (also known as hub genes) were identified with COPD-smokers, and these have the potential to cause a wide range of downstream pathogenetic effects. As for the preclinical phase, non-COPD smokers were found to be characterized by enriched pathways of several chemokines in AM.

Mogroside V reduce OVA-induced pulmonary inflammation based on lung and serum metabolomics

BACKGROUND

Mogroside V, the main ingredient of Siraitia grosvenorii, has been proved to have therapeutic effects on pulmonary diseases. The specific mechanism still remains to be clarified, which hinders the potence of its medicinal value.

PURPOSE

Serum and lung metabolomics based on LC-MS analysis were applied to explore the mechanism of mogroside V against lung inflammation.

METHOD

In this study, balb/c mice were divided into control, model, mogeoside V and SH groups. We evaluated the protective effects of mogroside V on lung inflammation in asthmatic mice. Suhuang Zhike Jiaonang was used as positive drug. Metabolic profiles of serum and lung samples of mice in control, model and mogroside V groups were analyzed by LC-MS.

RESULTS

Administration of mogroside V effectively relieved the expression of biochemical cytokines and lung inflammatory infiltration of asthmatic mice caused by ovalbumin (OVA). And visceral index of mice treated with mogroside V was close to control group. These results indicated that mogroside V ameliorated OVA-induced lung inflammation. LC-MS based metabolomics analysis demonstrated 6 main pathways in asthmatic mice including Vitamin B6 metabolism, Taurine and hypotaurine metabolism, Ascorbate and aldarate metabolism, Histidine metabolism, Pentose and glucuronate interconversions, Citrate cycle (TCA cycle) were regulated after using mogroside V.

CONCLUSION

The study firstly elucidates the metabolic pathways regulated by mogroside V on lung inflammation through metabolomics, providing a theoretical basis for more sufficient utilization and compatibility of mogroside V.

Mechanisms, Pathophysiology and Currently Proposed Treatments of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is one of the leading global causes of morbidity and mortality. A hallmark of COPD is progressive airflow obstruction primarily caused by cigarette smoke (CS). CS exposure causes an imbalance favoring pro- over antioxidants (oxidative stress), leading to transcription factor activation and increased expression of inflammatory mediators and proteases. Different cell types, including macrophages, epithelial cells, neutrophils, and T lymphocytes, contribute to COPD pathophysiology. Alteration in cell functions results in the generation of an oxidative and inflammatory microenvironment, which contributes to disease progression. Current treatments include inhaled corticosteroids and bronchodilator therapy. However, these therapies do not effectively halt disease progression. Due to the complexity of its pathophysiology, and the risk of exacerbating symptoms with existing therapies, other specific and effective treatment options are required. Therapies directly or indirectly targeting the oxidative imbalance may be promising alternatives. This review briefly discusses COPD pathophysiology, and provides an update on the development and clinical testing of novel COPD treatments.

Analysis of the polarization states of the alveolar macrophages in chronic obstructive pulmonary disease samples based on miRNA-mRNA network signatures

Background

Multiple gene expression studies have been performed to investigate the biomarkers of chronic obstructive pulmonary disease (COPD). However, few studies have related COPD to macrophage cells.

Methods

The gene expression levels of clinical samples of COPD smokers (COPD; n=6), healthy smokers (Smoke; n=11), and never smokers (Never; n=4) were downloaded from the Gene Expression Omnibus (GEO) repository of GSE124180. The expression levels of messenger RNAs (mRNAs) and microRNAs (miRNAs) in macrophage cells of M0 (n=7), M1 (n=7), and M2 (n=7) were downloaded from the GEO repository of GSE46903 and GSE51307. Differentially expressed (DE) mRNAs (DEmRNAs) were identified by edgeR and GEO2R, with an adjusted P value <0.05 and |log₂fold change (FC)| ≥1 chosen as the cut-off threshold. The potential target genes of miRNA were identified using miRanda (v3.3a) and TargetScan (v6.0) with default settings. Gene Ontology (GO) and Reactome pathway analyses were performed.

Results

The composition of macrophages was quite different between COPD, Never, and Smoke samples. The proportion of M1 cells was lower than that of M0 and M2 cells in Smokers and COPD samples. Most of the genes specifically up-regulated in M1 are related to inflammation/immunity. The expression levels of miR-30a-5p, miR-200c-3p, miR-20b-5p, miR-199b-5p, and miR-301b-3p in M1 macrophages were all lower than that of M0. Their expression levels in M2 macrophages compared with M1 varied, with higher expression in miR-30a-5p, miR-20b-5p, and lower expression in miR-200c-3p, and miR-301b-3p. The mRNAs of the fms related receptor tyrosine kinase 1 (FLT1), cardiotrophin like cytokine factor 1 (CLCF1), phosphodiesterase 4D (PDE4D), coagulation factor III, and tissue factor (F3) were dysregulated in COPD and macrophage cells.

Conclusions

The present study mined the miRNA-mRNA signature which might play an essential role in COPD and macrophage polarization.

Bioinformatic Analysis of ABCA1 Gene Expression in Smoking and Chronic Obstructive Pulmonary Disease

Smoking is a key modifiable risk factor for developing the chronic obstructive pulmonary disease (COPD). When smoking, many processes, including the reverse transport of cholesterol mediated by the ATP binding cassette transporter A1 (ABCA1) protein are disrupted in the lungs. Changes in the cholesterol content in the lipid rafts of plasma membranes can modulate the function of transmembrane proteins localized in them. It is believed that this mechanism participates in increasing the inflammation in COPD.

METHODS

Bioinformatic analysis of datasets from Gene Expression Omnibus (GEO) was carried out. Gene expression data from datasets of alveolar macrophages and the epithelium of the respiratory tract in smokers and COPD patients compared with non-smokers were used for the analysis. To evaluate differentially expressed genes, bioinformatic analysis was performed in comparison groups using the limma package in R (v. 4.0.2), and the GEO2R and Phantasus tools (v. 1.11.0).

RESULTS

The conducted bioinformatic analysis showed changes in the expression of the ABCA1 gene associated with smoking. In the alveolar macrophages of smokers, the expression levels of ABCA1 were lower than in non-smokers. At the same time, in most of the airway epithelial datasets, gene expression did not show any difference between the groups of smokers and non-smokers. In addition, it was shown that the expression of ABCA1 in the epithelial cells of the trachea and large bronchi is higher than in small bronchi.

CONCLUSIONS

The conducted bioinformatic analysis showed that smoking can influence the expression of the ABCA1 gene, thereby modulating lipid transport processes in macrophages, which are part of the mechanisms of inflammation development.

Smoking induces sex-specific changes in the small airway proteome

Introduction

Cigarette smoke triggers many cellular and signaling responses in the lung and the resulting inflammation plays a central role in smoke-related lung diseases, such as COPD. We explored the effects of smoking on the small airway proteome in samples obtained by collection of exhaled particles with the aim to identify specific proteins dysregulated by smoking.

Methods

Exhaled particles were obtained from 38 current smokers, 47 former smokers and 22 healthy controls with the PExA method. 120 ng of sample was collected from individual subjects and analyzed with the SOMAscan proteomics platform. General linear model-based statistics were performed.

Results

Two hundred and three proteins were detected in at least half of 107 total samples. Active smoking exerted a significant impact on the protein composition of respiratory tract lining fluid (RTLF), with 81 proteins altered in current smokers compared to never smokers (p < 0.05, q < 0.124). Among the proteins most clearly discriminating between current and never smokers were sRAGE, FSTL3, SPOCK2 and protein S, all of them being less abundant in current smokers. Analysis stratified for sex unveiled sex differences with more pronounced proteomic alterations due to active smoking in females than males. Proteins whose abundance was altered by active smoking in women were to a larger extent related to the complement system. The small airway protein profile of former smokers appeared to be more similar to that observed in never smokers.

Conclusions

The study shows that smoking has a strong impact on protein expression in the small airways, and that smoking affects men and women differently, suggesting PExA sampling combined with high sensitivity protein analysis offers a promising platform for early detection of COPD and identification of novel COPD drug targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01825-6.

Nerve Growth Factor: A Potential Therapeutic Target for Lung Diseases

The lungs play a very important role in the human respiratory system. However, many factors can destroy the structure of the lung, causing several lung diseases and, often, serious damage to people's health. Nerve growth factor (NGF) is a polypeptide which is widely expressed in lung tissues. Under different microenvironments, NGF participates in the occurrence and development of lung diseases by changing protein expression levels and mediating cell function. In this review, we summarize the functions of NGF as well as some potential underlying mechanisms in pulmonary fibrosis (PF), coronavirus disease 2019 (COVID-19), pulmonary hypertension (PH), asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. Furthermore, we highlight that anti-NGF may be used in future therapeutic strategies.

Risk assessment of occupational exposure to anesthesia Isoflurane in the hospital and veterinary settings

Despite the modern ventilation and waste anesthetic gas (WAG) scavenging systems, occupational exposure to common volatile anesthesia, isoflurane, can occur in the hospital and veterinary settings, but limited information exists on potential exposure and health risk of isoflurane. We assessed exposure dose rates and risks among clinicians and veterinary professionals from occupational exposure to isoflurane. Through a critical review of open literature (1965 to 2020), we summarized potential adverse effects and exposure scenarios of isoflurane among the professional groups, including anesthetists, nurses, operating room personnel, researchers, and/or veterinarians. Deterministic United States National Research Council/Environmental Protection Agency's risk assessment framework (hazard identification, dose-response relationship, exposure assessment and risk characterization) was used to compute inhalation Reference Doses (RfDs), Average Daily Doses (ADDs), and Hazard Quotient (HQ) values-an established measure of non-carcinogenic (systemic) risks-from exposure to isoflurane to workers in hospital and veterinary settings. We identified the central nervous system as the main target for isoflurane, and that isoflurane has dose-dependent effects on cardiac hemodynamics, can impair pulmonary functions and potentially cross the utero-placental barrier leading to congenital malformation in fetus. Based on the modelled RfDs (range 0.8003-7.55 mg/kg-day) and ADDs (range 0.071-1.9617 mg/kg-day), we estimated 56 different HQ values, of which 5 HQs were higher than 1 (range 1.099-2.4512) under high exposure scenarios. Our results suggest a significant non-carcinogenic risk from isoflurane exposures among workers in the occupational settings. The findings underscore the need to significantly minimize isoflurane release to protect workers' health in the hospital and veterinary environments.

Host factors facilitating SARS-CoV-2 virus infection and replication in the lungs

SARS-CoV-2 is the virus causing the major pandemic facing the world today. Although, SARS-CoV-2 primarily causes lung infection, a variety of symptoms have proven a systemic impact on the body. SARS-CoV-2 has spread in the community quickly infecting humans from all age, ethnicities and gender. However, fatal outcomes have been linked to specific host factors and co-morbidities such as age, hypertension, immuno-deficiencies, chronic lung diseases or metabolic disorders. A major shift in the microbiome of patients suffering of the coronavirus disease 2019 (COVID-19) have also been observed and is linked to a worst outcome of the disease. As many co-morbidities are already known to be associated with a dysbiosis of the microbiome such as hypertension, diabetes and metabolic disorders. Host factors and microbiome changes are believed to be involved as a network in the acquisition of the infection and the development of the diseases. We will review in detail in this manuscript, the immune response toward SARS-CoV-2 infection as well as the host factors involved in the facilitation and worsening of the infection. We will also address the impact of COVID-19 on the host's microbiome and secondary infection which also worsen the disease.