Chronic Obstructive Pulmonary Disease-Derived Circulating Cells Release IL-18 and IL-33 under Ultrafine Particulate Matter Exposure in a Caspase-1/8-Independent Manner

Assessment of NLRP3 inflammasome activation in patients with chronic obstructive pulmonary disease before and after lung transplantation

The interplay between purinergic receptors as well as pattern recognition receptors like Toll-like receptors (TLRs) and NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) might have a role in the pathogenesis of chronic obstructive pulmonary disease (COPD). The aim of this study was to determine and compare the concentrations of the damage-associated molecular patterns (DAMPs) heat shock protein 70 (Hsp70) and adenosine triphosphate (ATP), and gene expression of their respective receptors as well as NLRP3 inflammasome-related molecules in the peripheral blood of patients with end-stage COPD before and 1 year after lung transplantation (LT). Lung function was assessed by spirometry and diffusion capacity for carbon monoxide (DLCO). Quantitative polymerase chain reaction (qPCR) was applied for detection of TLR2, TLR4, P2X7R, P2Y2R, IL1B, CASP1, and NLRP3 expression. High-sensitivity ELISA kits were used for extracellular (e) Hsp70 and IL-1β, and luminescence assay for eATP measurements. Concentrations of eHsp70 and eATP as well as IL-1β were significantly increased in the plasma of end-stage COPD patients and significantly decreased after LT. In addition, TLR4, P2Y2R, IL1B, CASP1, and NLRP3 expression was up-regulated in COPD patients before LT, while it was significantly suppressed after LT. In conclusion, it could be assumed that NLRP3 inflammasome is activated in the peripheral blood of end-stage COPD patients and that eHsp70 and eATP could be responsible for its activation through triggering their receptors. On the other hand, previously enhanced pro-inflammatory reactions seem to be suppressed to the healthy population levels in lung recipients without allograft rejection.

Fine particulate matter aggravates smoking induced lung injury via NLRP3/caspase-1 pathway in COPD

BACKGROUND

Exposure to noxious particles, including cigarette smoke and fine particulate matter (PM2.5), is a risk factor for chronic obstructive pulmonary disease (COPD) and promotes inflammation and cell death in the lungs. We investigated the combined effects of cigarette smoking and PM2.5 exposure in patients with COPD, mice, and human bronchial epithelial cells.

METHODS

The relationship between PM2.5 exposure and clinical parameters was investigated in patients with COPD based on smoking status. Alveolar destruction, inflammatory cell infiltration, and pro-inflammatory cytokines were monitored in the smoking-exposed emphysema mouse model. To investigate the mechanisms, cell viability and death and pyroptosis-related changes in BEAS-2B cells were assessed following the exposure to cigarette smoke extract (CSE) and PM2.5.

RESULTS

High levels of ambient PM2.5 were more strongly associated with high Saint George's respiratory questionnaire specific for COPD (SGRQ-C) scores in currently smoking patients with COPD. Combined exposure to cigarette smoke and PM2.5 increased mean linear intercept and TUNEL-positive cells in lung tissue, which was associated with increased inflammatory cell infiltration and inflammatory cytokine release in mice. Exposure to a combination of CSE and PM2.5 reduced cell viability and upregulated NLRP3, caspase-1, IL-1β, and IL-18 transcription in BEAS-2B cells. NLRP3 silencing with siRNA reduced pyroptosis and restored cell viability.

CONCLUSIONS

PM2.5 aggravates smoking-induced airway inflammation and cell death via pyroptosis. Clinically, PM2.5 deteriorates quality of life and may worsen prognosis in currently smoking patients with COPD.

Genetic variation of six specific SNPs of chronic obstructive pulmonary disease among Chinese population

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a chronic bronchitis (or) emphysema with a high disability and fatality rate. This study aimed to explore the correlation between the six selected single nucleotide polymorphisms (SNPs) and the risk of COPD in the Chinese population.

METHODS

The Agena MassARRAY platform was used to select six SNPs from 629 subjects for genotyping. The correlation between SNPs and COPD risk was evaluated using calculated odds ratios (ORs) and 95% confidence intervals (CIs). Multi-factor dimensionality reduction (MDR) was performed to analyze the impact of SNP interactions on COPD risk. Multiple comparisons were performed using Bonferroni- correction.

RESULTS

Our results indicated that rs4719841 and rs7934083 variants were associated with a reduced risk of COPD. The analysis results of age, gender and non-smokers showed that rs4719841 and rs7934083 were associated with reducing the risk of COPD. In addition, the results showed that the genetic models of rs4719841, rs7934083 and rs7780562 were related to the forced vital capacity, respiratory rate per second, and respiratory rate / forced vital capacity of COPD patients, respectively. The results of the MDR analysis showed that the three-locus model (rs4719841, rs7934083, and rs78750958) is the best for COPD risk assessment.

CONCLUSION

This study shows that rs4719841 and rs7934083 are associated with the risk of COPD in the Chinese population, which provides some insights for early screening, prevention, and diagnosis of COPD in high-risk populations.

Absent in melanoma 2 (AIM2) positive profile identifies a poor prognosis of lung adenocarcinoma patients

The absent in melanoma 2 (AIM2) inflammasome has been demonstrated as involved in tumor growth. In this study we used human samples of lung adenocarcinoma (LUAD) patients, taking advantage of a mouse model of smoking cessation. Human samples were stratified according to the smoking status, high-risk factor for this type of tumor. Both public transcriptomic and human samples obtained by a clinical trial proved that AIM2 was upregulated either in terms of mRNA or protein, respectively, in the tumor mass according to the TNM stage, but it did not relate to the smoking status, age and sex. The upregulation of AIM2 was correlated to an immunosuppressive environment according to resting/non-active dendritic cells (DCs) and T regulatory cells, as demonstrated in both human samples and by means of an experimental model of smoking mice. Computational analysis showed that AIM2 upregulation was correlated to both an inflammasome profile, responsible for the poor prognosis of non-smoker and smoker LUAD patients, and to a non-inflammasome profile for former smoker. In conclusion, our study demonstrated that AIM2 is involved in lung carcinogenesis either in a canonical and non-canonical manner due to an immunosuppressive microenvironment associated to a dismal prognosis of LUAD patients.

Epithelial alarmins: a new target to treat chronic respiratory diseases

INTRODUCTION

In response to injury, epithelial cells release alarmins including thymic stromal lymphopoietin (TSLP), high mobility group-box-1 (HMGB1), interleukin (IL)-33 and -25 that can initiate innate immune responses. These alarmins are recognized as activators of T2-immune responses characteristic for asthma, but recent evidence highlighted their role in non-T2 inflammation, airway remodeling, and pulmonary fibrosis making them an attractive therapeutic target for chronic respiratory diseases (CRD).

AREAS COVERED

In this review, firstly we discuss the role of TSLP, IL-33, IL-25, and HMGB1 in the pathogenesis of asthma, COPD, idiopathic pulmonary fibrosis, and cystic fibrosis according to the published data. In the second part, we summarize the current evidence concerning the efficacy of the antialarmin therapies in CRD. Recent clinical trials showed that anti-TSLP and IL-33/R antibodies can improve severe asthma outcomes. Blocking the IL-33-mediated pathway decreased the exacerbation rate in COPD patients with more important benefit for former-smokers.

EXPERT OPINION

Despite progress in the understanding of the alarmins' role in the pathogenesis of CRD, all their mechanisms of action are not yet identified. Blocking IL-33 and TSLP pathways offers an interesting option to treat severe asthma and COPD, but future investigations are needed to establish their place in the treatment strategies.

The Role of IL-33/ST2 in COPD and Its Future as an Antibody Therapy

COPD is a leading cause of mortality and morbidity worldwide and is associated with a high socioeconomic burden. Current treatment includes the use of inhaled corticosteroids and bronchodilators, which can help to improve symptoms and reduce exacerbations; however, there is no solution for restoring lung function and the emphysema caused by loss of the alveolar tissue. Moreover, exacerbations accelerate progression and challenge even more the management of COPD. Mechanisms of inflammation in COPD have been investigated over the past years, thus opening new avenues to develop novel targeted-directed therapies. Special attention has been paid to IL-33 and its receptor ST2, as they have been found to mediate immune responses and alveolar damage, and their expression is upregulated in COPD patients, which correlates with disease progression. Here we summarize the current knowledge on the IL-33/ST2 pathway and its involvement in COPD, with a special focus on developed antibodies and the ongoing clinical trials using anti-IL-33 and anti-ST2 strategies in COPD patients.

ASSOCIATION OF CASPASE-8 LEVELS WITH RESPIRATORY PARAMETERS AND PRESENCE OF HYPERTENSION IN COPD PATIENTS

OBJECTIVE

The aim: To investigate the association between hypertension and serum Caspase-8 levels in COPD patients.

PATIENTS AND METHODS

Materials and methods: 95 COPD patients (GOLD 2nd grade, group B) were included in the study: 47 non-hypertensive COPD patients formed the main group, and 48 patients with concomitant COPD and hypertension formed the comparison group. Patients underwent examination according to GOLD 2022 Guidelines. Caspase-8 serum levels were measured by ELISA.

RESULTS

Results: Performed analysis showed that an increase in Caspase-8 serum levels was significantly associated with the presence of concomitant hypertension in both univariate and multivariate analyses. A significant association was also found regarding FEV1 levels but not FVC.

CONCLUSION

Conclusions: Both presence of concomitant hypertension and spirometry parameters, which indicate the severity of COPD, can be considered strong predictors of the intensification of apoptosis in COPD patients.

Pyroptosis and respiratory diseases: A review of current knowledge

Pyroptosis is a relatively newly discovered programmed cell death accompanied by an inflammatory response. In the classical view, pyroptosis is mediated by caspases-1,-4,-5,-11 and executed by GSDMD, however, recently it was demonstrated that caspase-3 and-8 also participate in the process of pyroptosis, by cleaving GSDMD/E and GSDMD respectively. Different from autophagy and apoptosis, many pores are formed on the cell membrane during pyroptosis, which makes the cell membrane lose its integrity, eventually leading to the release of cytokines interleukin(IL)-1β and IL-18. When the body is infected with pathogens or exposed to some stimulations, pyroptosis could play an immune defense role. It is found that pyroptosis exists widely in infectious and inflammatory respiratory diseases such as acute lung injury, bronchial dysplasia, chronic obstructive pulmonary disease, and asthma. Excessive pyroptosis may accompany airway inflammation, tissue injury, and airway damage, and induce an inflammatory reaction, leading to more serious damage and poor prognosis of respiratory diseases. This review summarizes the relationship between pyroptosis and related respiratory diseases.

Size-based effects of anthropogenic ultrafine particles on activation of human lung macrophages

The anthropogenic particulate matter (PM), suspended air dust that can be inhaled by humans and deposited in the lungs, is one of the main pollutants in the industrialized cities atmosphere. Recent studies have shown that PM has adverse effects on respiratory diseases. These effects are mainly due to the ultrafine particles (PM0.1, PM < 100 nm), which, thanks to their PM size, are efficiently deposited in nasal, tracheobronchial, and alveolar regions. Pulmonary macrophages are a heterogeneous cell population distributed in different lung compartments, whose role in inflammatory response to injury is of particular relevance. In this study, we investigated the effect of PM0.1 on Human Lung Macrophages (HLMs) activation evaluated as proinflammatory cytokines and chemokine release, Reactive Oxygen Species (ROS) production and intracellular Ca²⁺concentration ([Ca²⁺]_i). Furthermore, PM0.1, after removal of organic fraction, was fractionated in nanoparticles both smaller (NP20) and bigger (NP100) than 20 nm by a properlydeveloped analytical protocol, allowed isolating their individual contribution. Interestingly, while PM0.1 and NP20 induced stimulatory effects on HLM cytokines release, NP100 had not effect. In particular, PM0.1 induced IL-6, IL-1β, TNF-α, but not CXCL8, release from HLMs. Moreover, PM0.1, NP20 and NP100 did not induce β-glucuronidase release, a preformed mediator contained in HLMs. The long time necessary for cytokines release (18 h) suggested that PM0.1 and NP20 could induce ex-novo production of the tested mediators. Accordingly, after 6 h of incubation, PM0.1 and NP20 induced mRNA expression of IL-6, TNF-α and IL-1β. Moreover, NP20 induced ROS production and [Ca²⁺]_i increase in a time-dependent manner, without producing cytotoxicity. Collectively, the present data highlight the main proinflammatory role of NP20 among PM fractions. This is particularly of concern because this fraction is not currently covered by legal limits as it is not easily measured at the exhausts by the available technical methodologies, suggesting that it is mandatory to search for new monitoring techniques and strategies for limiting NP20 formation.

Polyphenols, flavonoids and inflammasomes: the role of cigarette smoke in COPD

COPD is predicted to become the third leading cause of morbidity and mortality worldwide by 2030. Cigarette smoking (active or passive) is one of its chief causes, with about 20% of cigarette smokers developing COPD from cigarette smoke (CS)-induced irreversible damage and sustained inflammation of the airway epithelium. Inflammasome activation leads to the cleavage of pro-interleukin (IL)-1β and pro-IL-18, along with the release of pro-inflammatory cytokines via gasdermin D N-terminal fragment membrane pores, which further triggers acute phase pro-inflammatory responses and concurrent pyroptosis. There is currently intense interest in the role of nucleotide-binding oligomerisation domain-like receptor family, pyrin domain containing protein-3 inflammasomes in chronic inflammatory lung diseases such as COPD and their potential for therapeutic targeting. Phytochemicals including polyphenols and flavonoids have phyto-medicinal benefits in CS-COPD. Here, we review published articles from the last decade regarding the known associations between inflammasome-mediated responses and ameliorations in pre-clinical manifestations of CS-COPD via polyphenol and flavonoid treatment, with a focus on the underlying mechanistic insights. This article will potentially assist the development of drugs for the prevention and therapy of COPD, particularly in cigarette smokers.

This review compiles current investigations into the role of polyphenols/flavonoids in the alleviation of cigarette smoke-induced inflammasome; notably it provides a promising hit for rectifying the treatment of COPD.https://bit.ly/36OcUO9

Angiogenesis, Lymphangiogenesis, and Inflammation in Chronic Obstructive Pulmonary Disease (COPD): Few Certainties and Many Outstanding Questions

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation, predominantly affecting the lung parenchyma and peripheral airways, that results in progressive and irreversible airflow obstruction. COPD development is promoted by persistent pulmonary inflammation in response to several stimuli (e.g., cigarette smoke, bacterial and viral infections, air pollution, etc.). Angiogenesis, the formation of new blood vessels, and lymphangiogenesis, the formation of new lymphatic vessels, are features of airway inflammation in COPD. There is compelling evidence that effector cells of inflammation (lung-resident macrophages and mast cells and infiltrating neutrophils, eosinophils, basophils, lymphocytes, etc.) are major sources of a vast array of angiogenic (e.g., vascular endothelial growth factor-A (VEGF-A), angiopoietins) and/or lymphangiogenic factors (VEGF-C, -D). Further, structural cells, including bronchial and alveolar epithelial cells, endothelial cells, fibroblasts/myofibroblasts, and airway smooth muscle cells, can contribute to inflammation and angiogenesis in COPD. Although there is evidence that alterations of angiogenesis and, to a lesser extent, lymphangiogenesis, are associated with COPD, there are still many unanswered questions.

TI: NLRP3 Inflammasome-Dependent Pyroptosis in CNS Trauma: A Potential Therapeutic Target

Central nervous system (CNS) trauma, including traumatic brain injury (TBI) and traumatic spinal cord injury (SCI), is characterized by high morbidity, disability, and mortality. TBI and SCI have similar pathophysiological mechanisms and are often accompanied by serious inflammatory responses. Pyroptosis, an inflammation-dependent programmed cell death, is becoming a major problem in CNS post-traumatic injury. Notably, the pyrin domain containing 3 (NLRP3) inflammasome is a key protein in the pyroptosis signaling pathway. Therefore, underlying mechanism of the NLRP3 inflammasome in the development of CNS trauma has attracted much attention. In this review, we briefly summarize the molecular mechanisms of NLRP3 inflammasome in pyroptosis signaling pathway, including its prime and activation. Moreover, the dynamic expression pattern, and roles of the NLRP3 inflammasome in CNS post-traumatic injury are summarized. The therapeutic applications of NLRP3 inflammasome activation inhibitors are also discussed.

Role of Particulate Matter from Afghanistan and Iraq in Deployment-Related Lung Disease

Approximately 3 million United States military personnel and contractors were deployed to Southwest Asia and Afghanistan over the past two decades. After returning to the United States, many developed persistent respiratory symptoms, including those due to asthma, rhinosinusitis, bronchiolitis, and others, which we collectively refer to as deployment-related lung diseases (DRLD). The mechanisms of different DRLD have not been well defined. Limited studies from us and others suggest that multiple factors and biological signaling pathways contribute to the onset of DRLD. These include, but are not limited to, exposures to high levels of particulate matter (PM) from sandstorms, burn pit combustion products, improvised explosive devices, and diesel exhaust particles. Once inhaled, these hazardous substances can activate lung immune and structural cells to initiate numerous cell-signaling pathways such as oxidative stress, Toll-like receptors, and cytokine-driven cell injury (e.g., interleukin-33). These biological events may lead to a pro-inflammatory response and airway hyperresponsiveness. Additionally, exposures to PM and other environmental hazards may predispose military personnel and contractors to more severe disease due to the interactions of those hazardous materials with subsequent exposures to allergens and cigarette smoke. Understanding how airborne exposures during deployment contribute to DRLD may identify effective targets to alleviate respiratory diseases and improve quality of life in veterans and active duty military personnel.

From Biomarkers to Novel Therapeutic Approaches in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous and complex disorder. In this review, we provided a comprehensive overview of biomarkers involved in COPD, and potential novel biological therapies that may provide additional therapeutic options for COPD. The complex characteristics of COPD have made the recommendation of a generalized therapy challenging, suggesting that a tailored, personalized strategy may lead to better outcomes. Existing and unmet needs for COPD treatment support the continued development of biological therapies, including additional investigations into the potential clinical applications of this approach.

Caspase-11 and AIM2 inflammasome are involved in smoking-induced COPD and lung adenocarcinoma

Cigarette smoking is the leading risk factor for COPD and lung cancer establishment. Epidemiologically, COPD patients are 6.35 times more likely to develop lung cancer. To mimic COPD, we exposed mice to nose-only cigarette smoke and used human samples of lung adenocarcinoma patients according to the smoking and COPD status. Smoking C57Bl/6N mice had higher enlargement of alveoli, deposition of collagen and mucus production, associated to the release of IL-1-like cytokines, such as IL-1α and IL-1β at early time points and IL-18 at later time points. AIM2 expression was higher in lung recruited dendritic cells and macrophages in smoking mice, associated to the activation of caspase-11, rather than caspase-1. In support,129Sv mice, which are dysfunctional for caspase-11, had lower collagen deposition and mucus production, associated to lower release of IL-1-like and fibrotic TGFβ. Interestingly, higher expression of AIM2 in non-cancerous tissue of smoking COPD adenocarcinoma patients was correlated to a higher hazard ratio of poor survival rate than in patients who presented lower levels of AIM2. We found that AIM2 inflammasome is at the crossroad between COPD and lung cancer in that its higher presence is correlated to lower survival rate of smoking COPD adenocarcinoma patients.

Interleukin-33 gene polymorphisms and chronic obstructive pulmonary disease in the Chinese Han population

Objective

To investigate the relationship between interleukin (IL)-33 gene polymorphisms rs928413 and rs7044343 with chronic obstructive pulmonary disease (COPD) in the Chinese Han population.

Method

We assessed IL-33 rs928413 and rs7044343 polymorphisms by Sanger sequencing of PCR products amplified from the genomic DNA of 160 COPD patients and 123 healthy controls.

Results

There was no significant difference in the distribution of rs928413 AA, AG, or AA genotypes or rs7044343 CC, CT, or TT genotypes between the two groups. However, COPD patients had a significantly higher frequency of the rs928413 G allele G (14.1% vs 7.3%, respectively). This allele was significantly associated with susceptibility to COPD (odds ratio [OR]: 2.04, 95% confidence interval [CI]: 1.12–3.57). The rs928413 dominant inheritance model was associated with COPD susceptibility (OR: 2.08, 95%CI: 1.09–4.04).

Conclusion

The G allele of rs928413 and the rs928413 dominant inheritance model were associated with susceptibility to COPD in the Chinese Han population.

Variations in Reactive Oxygen Species Generation by Urban Airborne Particulate Matter in Lung Epithelial Cells-Impact of Inorganic Fraction

Air pollution is associated with numerous negative effects on human health. The toxicity of organic components of air pollution is well-recognized, while the impact of their inorganic counterparts in the overall toxicity is still a matter of various discussions. The influence of airborne particulate matter (PM) and their inorganic components on biological function of human alveolar-like epithelial cells (A549) was investigated in vitro. A novel treatment protocol based on covering culture plates with PM allowed increasing the studied pollutant concentrations and prolonging their incubation time without cell exposure on physical suffocation and mechanical disturbance. PM decreased the viability of A549 cells and disrupted their mitochondrial membrane potential and calcium homeostasis. For the first time, the difference in the reactive oxygen species (ROS) profiles generated by organic and inorganic counterparts of PM was shown. Singlet oxygen generation was observed only after treatment of cells with inorganic fraction of PM, while hydrogen peroxide, hydroxyl radical, and superoxide anion radical were induced after exposure of A549 cells to both PM and their inorganic fraction.

Antioxidant and antimicrobial properties of Pelargonium sidoides DC and lactoferrin combination

Lactoferrin (LAT), a multifunctional protein involved in numerous physiological functions, and the medicinal plant Pelargonium sidoides DC (PEL) have been described for their anti-inflammatory properties. Because the main advantage of natural products consists in administering them in combination rather than as single compound, we aimed to understand whether the combination of PEL and LAT, herein PELIRGOSTIM, could still prove beneficial or additive/synergistic activities during inflammatory conditions. To pursue this goal, we used macrophagic cells (J774.1) and treated them with PEL and LAT in a concentration-dependent manner. We found that PELIRGOSTIM was able to reduce the levels of reactive oxygen species (ROS) and nitrite, effects that were correlated to the release of lower levels of IL-1β after LPS treatment. In addition, the combination of PEL and LAT showed bacteriostatic activities against Staphylococcus aureus and Escherichia coli which had limited growth starting from 5 hours up to 20 hours. This effect was stronger than that observed for penicillin/streptomycin.

Our results provide PELIRGOSTIM as an innovative combination of natural products capable to prevent inflammation-, oxidative stress- and microbial-related disorders.

New Insights into the Implication of Mitochondrial Dysfunction in Tissue, Peripheral Blood Mononuclear Cells, and Platelets during Lung Diseases

Lung diseases such as chronic obstructive pulmonary disease, asthma, pulmonary arterial hypertension, or idiopathic pulmonary fibrosis are major causes of morbidity and mortality. Complex, their physiopathology is multifactorial and includes lung mitochondrial dysfunction and enhanced reactive oxygen species (ROS) release, which deserves increased attention. Further, and importantly, circulating blood cells (peripheral blood mononuclear cells-(PBMCs) and platelets) likely participate in these systemic diseases. This review presents the data published so far and shows that circulating blood cells mitochondrial oxidative capacity are likely to be reduced in chronic obstructive pulmonary disease (COPD), but enhanced in asthma and pulmonary arterial hypertension in a context of increased oxidative stress. Besides such PBMCs or platelets bioenergetics modifications, mitochondrial DNA (mtDNA) changes have also been observed in patients. These new insights open exciting challenges to determine their role as biomarkers or potential guide to a new therapeutic approach in lung diseases.

IL-33 in Chronic Respiratory Disease: From Preclinical to Clinical Studies

IL-33 has been deorphanized as a member of the IL-1 family and has key roles as an alarmin and cytokine with potent capacity to drive type 2 inflammation. This has led to a plethora of studies surrounding its role in chronic diseases with a type 2 inflammatory component. Here, we review the roles of IL-33 in two chronic respiratory diseases, asthma and chronic obstructive pulmonary disease (COPD). We discuss the hallmark and paradigm-shifting studies that have contributed to our understanding of IL-33 biology. We cover animal studies that have elucidated the mechanisms of IL-33 and assessed the role of anti-IL-33 treatment and immunization against IL-33. We highlight key clinical evidence for the potential of targeting increased IL-33 in respiratory diseases including exacerbations, and we outline current clinical trials using an anti-IL-33 monoclonal antibody in asthma patients. Finally, we discuss some of the challenges that have arisen in IL-33 biology and highlight potential future directions in targeting this cytokine in chronic respiratory diseases.

AIM2/IL-1α/TGF-β Axis in PBMCs From Exacerbated Chronic Obstructive Pulmonary Disease (COPD) Patients Is Not Related to COX-2-Dependent Inflammatory Pathway

Chronic obstructive pulmonary disease (COPD) is a lung disorder characterized by persistent respiratory symptoms and progressive airflow limitation as a consequence of a chronic inflammatory response. Corticosteroids are the main treatment for COPD patients with a history of exacerbation, in that they attenuate exacerbation and dyspnea, and improve the response to bronchodilators. Nevertheless, despite corticosteroid administration, COPD patients still undergo exacerbation phases. In this context, the aim of this study was to evaluate the activity of Absent in melanoma 2 (AIM2) inflammasome-dependent pathways under corticosteroid treatment during COPD exacerbation. Stable and exacerbated COPD-derived Peripheral Blood Mononuclear Cells (PBMCs) were treated with a well-known anti-inflammatory agent, Dexamethasone (DEX), in the presence or not of Poly (deoxyadenylic-deoxythymidylate) acid (Poly dA:dT), an AIM2 ligand. We found that IL-1α was highly increased when AIM2 was activated from Poly dA:dT in exacerbated, but not in stable, COPD-derived PBMCs. To note, the release of IL-1α after the stimulation of AIM2 in PBMCs obtained from stable (hospitalized) COPD patients was not higher from the basal conditions, though it was still as high as that observed for Poly dA:dT-stimulated PBMCs obtained from exacerbated patients. This effect was associated with a higher expression of AIM2 in pair-matched circulating CD14⁺ cells obtained from hospitalized patients who passed from the exacerbation to stable status. Because the difference between stable and exacerbated COPD patients relies on the treatment with corticosteroids, exacerbated and stable COPD-derived PBMCs were treated with DEX. Indeed, the release of IL-1α and TGF-β was not altered after DEX treatment. In conclusion, we found that the administration of DEX in vitro on exacerbated COPD-derived PBMCs was not able to revert the detrimental inflammatory mechanism associated with AIM2 activation responsible for the release of IL-1α and the ensuing TGF-β, contributing to the severity of disease.

The Inhibition of Caspase-1- Does Not Revert Particulate Matter (PM)-Induced Lung Immunesuppression in Mice

Background: Air pollution is becoming a threatening issue for human health. Many epidemiological studies relate air pollution index to adverse effects in terms of disease incidence and/or disease exacerbation. In our previous studies, we found air pollutants can induce the release of pro-inflammatory cytokines from human peripheral blood cells. To better understand, the effects of air pollution in the lung, we took advantage of an animal model. Experimental Approach: Mice were intratracheally and daily exposed to urban collected particulate matter (PM, PM10, and PM1) and to the sub-micrometric carbonaceous component, Soot. Results: We found that PM10, PM1, and Soot promoted lung inflammation associated to higher bronchial responsiveness and lower dilation together with an immunosuppressive lung environment, characterized by tolerogenic dendritic cells (DCs), macrophages and myeloid -derived suppressor cells (MDSCs), the latter two Arginase I positive. In support, higher recruitment of Treg associated to higher levels of IL-10 were detected in the lung of PM10, PM1, and Soot treated mice. This effect was not abolished by the administration of a caspase-1 inhibitor, Ac-Y-VAD, implying that the canonical inflammasome complex was not associated to PMx-induced lung immunosuppression in mice. Conclusion: Our study proves that PM exposure leads to an immunosuppressive lung environment in a caspase-1-independent manner, paving the way to understand the molecular and cellular mechanism/s underlying the establishment of some respiratory disorders according to the exposure to air pollution.

AIM2 Inflammasome Activation Leads to IL-1α and TGF-β Release From Exacerbated Chronic Obstructive Pulmonary Disease-Derived Peripheral Blood Mononuclear Cells

Chronic obstructive pulmonary disease (COPD) is now the fourth-leading cause of death worldwide and its prevalence is increasing. The progressive decline of lung function and airway remodelling are a consequence of chronic inflammatory responses. It was recently postulated the involvement of the inflammasome in COPD, although the underlying mechanism/s still need to be elucidated. Therefore, we isolated peripheral blood mononuclear cells (PBMCs) from exacerbated/unstable COPD patients. The stimulation of PBMCs with an AIM2 inflammasome activator, Poly dA:dT, led to IL-1α, but not IL-1β, release. The release of this cytokine was caspase-1- and caspase-4-dependent and correlated to higher levels of 8-OH-dG in COPD compared to non-smoker and smoker-derived PBMCs. Interestingly, AIM2-depedent IL-1α release was responsible for higher TGF-β levels, crucial mediator during pro-fibrotic processes associated to COPD progression. In conclusion, our data highlight the involvement of AIM2/caspase-1/caspase-4 in IL-1α-induced TGF-β release in unstable COPD-derived PBMCs, opening new therapeutic perspectives for unstable COPD patients.

Short-term Haze Exposure Predisposes Healthy Volunteers to Nasal Inflammation

PURPOSE

This study aimed to investigate the impact of short-term haze exposure on nasal inflammation in healthy volunteers.

METHODS

Thirty-three healthy university students were assessed for nasal symptoms, nasal patency, upper and lower respiratory tract nitric oxide (NO) as well as inflammatory mediators and neuropeptides in nasal secretions before and after a 5-day haze episode. Peripheral blood mononuclear cells (PBMCs) were stimulated with particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5), and cytokines in the supernatants were examined.

RESULTS

Mild nasal symptoms were reported by some participants during the haze episode. Objective measures of nasal patency demonstrated that nasal airway resistance was significantly increased from baseline levels, while nasal cavity volume and minimum cross-sectional area were significantly decreased. Similarly, the levels of nasal and exhaled NO, eotaxin, interleukin (IL)-5, chemokine (C-C motif) ligand 17, IL-8, substance P, nerve growth factor and vasoactive intestinal peptides in nasal secretions were significantly increased from baseline values following the haze episode. In contrast, the levels of interferon-γ, IL-10, transforming growth factor-β and neuropeptide Y were significantly decreased. Incubation with 0.1-10 μg/mL PM2.5 significantly increased release of IL-1β, IL-4, IL-5, IL-8 and IL-10 from PBMCs.

CONCLUSIONS

Short-term haze exposure may lead to nasal inflammation and hypersensitivity in healthy subjects predominantly by Th2 cytokine-mediated immune responses.

Circulating and tumor-associated caspase-4: a novel diagnostic and prognostic biomarker for non-small cell lung cancer

Late diagnosis limits therapeutic options and survival rate of non-small cell lung cancer (NSCLC) patients. Therefore the identification of biomarkers represents an emerging medical need.

A highly sensitive and specific test was developed to identify/quantify a novel/selective diagnostic biomarker for NSCLC patients, caspase-4. This test was validated by using i) plasma from 125 NSCLC patients and 79 healthy (non-pathological) subjects, ii) plasma from 139 smokers and iii) from 70 chronic-obstructive pulmonary disease (COPD) patients. Caspase-4 quantification was also assessed in the lung tumor mass of 98 paired NSCLC patients compared to 10 non-tumor lung tissues (i.e. tuberculosis).

Circulating caspase-4 was detected in both healthy and NSCLC patients; however at different range values: 2.603–3.372 ng/ml for NSCLC patients (95% CI) compared to 0.3994-0.6219 ng/ml for healthy subjects (95% CI). The sensitivity of the test ranged from 97.07% to 100%; the specificity was 88.1% with a positive predictive value of 92.54%, accuracy of 95.19% and AUC of 0.971. Smokers (95% CI, 0.3947–0.6197 ng/ml) and COPD patients (95% CI, 1.703–2.995 ng/ml) showed intermediate values of circulating caspase-4. Tissue levels of caspase-4 in the tumor mass showed that 72 (72.7%) out of 99 patients were positive. More importantly, higher levels (cut-off value = 0.307 ng/ml) of caspase-4 in the tumor mass were associated to reduced overall survival (median 0.92 years) compared to NSCLC patients with lower levels (median 3.02 years).

We report for the first time caspase-4 as a novel diagnostic and prognostic biomarker, opening new therapeutic perspectives for NSCLC patients.