Innate immune recognition in infectious and noninfectious diseases of the lung

COPD risk due to extreme temperature exposure: combining epidemiological evidence with pathophysiological mechanisms

Climate change is amplifying the frequency and intensity of extreme temperature events, posing a significant risk for chronic obstructive pulmonary disease (COPD). This review synthesised epidemiological evidence linking extreme temperature to COPD morbidity and mortality, while elucidating synergistic interactions with other environmental exposures. Combining population-level findings with biomedical mechanistic insights, we proposed a framework illustrating how biomarkers bridge the gap between extreme temperature exposure and COPD, highlighting the pathophysiological mechanisms of prodromal symptoms, key pathogenic processes and early molecular events. The mechanisms and biomarkers identified in this study would provide critical information for elucidating the causal pathways through which extreme temperatures increase COPD risk, and thus inform preventive interventions. Future research should incorporate multi-omics techniques to explore the underlying mechanisms in greater depth, while validating the biomarkers through large-scale cohort studies.

Review on the molecular mechanisms of low-level laser therapy: gene expression and signaling pathways

Low-level laser therapy (LLLT) has been shown to influence cellular and molecular processes in irradiated tissues and cells. By altering gene expression and activating specific laser-induced signaling pathways, LLLT can impact key cellular activities such as proliferation, differentiation, migration, and metabolism. This review focuses on exploring the molecular-level effects of LLLT, examining how different wavelengths interact with various cell lines, including stem cells, to induce these changes in gene expression and signaling pathways. A comprehensive review was performed by analyzing relevant literature published between 2003 and 2024. The search utilized databases such as PubMed, Scopus, MEDLINE, EMBASE, and Google Scholar. Selection criteria were based on the presence of keywords including "gene expression," "signaling pathways," "molecular mechanisms," "photobiomodulation," and "LLLT." Among the 150 recent studies on low-level laser therapy and its molecular and cellular effects on irradiated cells, articles related to changes in gene expression and laser-induced signaling pathways were reviewed. Low-level laser therapy exhibits varying effects based on the parameters and wavelengths used. Red and infrared lasers are particularly effective for promoting cell proliferation, differentiation, reducing inflammation, and enhancing wound healing. Blue lasers tend to inhibit cell proliferation, while green lasers are effective in reducing inflammation and aiding in conditions such as intervertebral disc (IVD) degeneration. These effects are linked to changes in gene expression and laser-induced signaling pathways, highlighting the importance of selecting the appropriate laser type for specific therapeutic goals.

Role of Cellular Senescence Genes and Immune Infiltration in Sepsis and Sepsis-Induced ARDS Based on Bioinformatics Analysis

Introduction

Sepsis is the leading cause of death in critically ill patients; it results in multiorgan dysfunction, including acute respiratory distress syndrome (ARDS). Our study was conducted to determine the role of cellular senescence genes and immune infiltration in sepsis and sepsis-induced ARDS via bioinformatic analyses.

Experimental Procedures

Datasets GSE66890 and GSE145227 were obtained from the Gene Expression Omnibus (GEO) database and utilized for bioinformatics analyses. Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the differentially expressed genes (DEGs) were performed to identify the key functional modules. Two machine learning algorithms, least absolute shrinkage and selection operator (LASSO) and support vector machine recursive feature elimination (SVM-RFE), were used to screen for characteristic genes in sepsis and sepsis-induced ARDS. ROC curves were generated to evaluate the predictive ability of gene hubs. Differences in immune infiltration levels between the disease and control groups were compared via ssGSEA. The diagnostic value of the hub genes was verified via quantitative PCR (qPCR) in hospitalized patients.

Results

Four characteristic genes (ATM, CCNB1, CCNA1, and E2F2) were identified as biomarkers for the progression of sepsis-induced ARDS. E2F2 showed the highest predictive ability for the occurrence of ARDS in patients with sepsis. CD56bright and plasmacytoid dendritic cells exhibited high infiltration in the sepsis-induced ARDS group, whereas eosinophils, MDSCs, macrophages, and neutrophils exhibited low infiltration. In addition, ATM expression was lower in patients with sepsis than in those without sepsis (n = 6).

Conclusion

Sepsis-induced ARDS is correlated with circulating immune responses, and the expression of ATM, CCNB1, CCNA1, and E2F2 may serve as potential diagnostic biomarkers and therapeutic targets in sepsis-induced ARDS.

Transcription factor NF-E2-related factor 2 plays a critical role in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) by regulating ferroptosis

NRF2 is an important transcription factor that regulates redox homeostasis in vivo and exerts its anti-oxidative stress and anti-inflammatory response by binding to the ARE to activate and regulate the transcription of downstream protective protein genes, reducing the release of reactive oxygen species. Ferroptosis is a novel iron-dependent, lipid peroxidation-driven cell death mode, and recent studies have shown that ferroptosis is closely associated with acute lung injury/acute respiratory distress syndrome (ALI/ARDS). NRF2 is able to regulate ferroptosis through the regulation of the transcription of its target genes to ameliorate ALI/ARDS. Therefore, This article focuses on how NRF2 plays a role in ALI/ARDS by regulating ferroptosis. We further reviewed the literature and deeply analyzed the signaling pathways related to ferroptosis which were regulated by NRF2. Additionally, we sorted out the chemical molecules targeting NRF2 that are effective for ALI/ARDS. This review provides a relevant theoretical basis for further research on this theory and the prevention and treatment of ALI/ARDS. The intended audience is clinicians and researchers in the field of respiratory disease.

Foxq1 Promotes Alveolar Epithelial Cell Death through Tle1-mediated Inhibition of the NF-κB Signaling Pathway

Acute lung injury (ALI) is a common respiratory disease characterized by diffuse alveolar injury and interstitial edema, as well as a hyperinflammatory response, lung cell damage, and oxidative stress. Foxq1, a member of the FOX family of transcription factors, is expressed in various tissues, such as the lungs, liver, and kidneys, and contributes to various biological processes, such as stress, metabolism, cell cycle arrest, and aging-related apoptosis. However, the role of Foxq1 in ALI is unknown. We constructed ex vivo and in vivo ALI models by LPS tracheal perfusion of ICR mice and conditioned medium stimulation of injured MLE-12 cells. Foxq1 expression was increased, and its localization was altered, in our ALI model. In normal or injured MLE-12 cells, knockdown of Foxq1 promoted cell survival, and overexpression had the opposite effect. This regulatory effect was likely mediated by Tle1 and the NF-κB/Bcl2/Bax signaling pathway. These data suggest a potential link between Foxq1 and ALI, indicating that Foxq1 can be used as a biomarker for the diagnosis of ALI. Targeted inhibition of Foxq1 expression could promote alveolar epithelial cell survival and may provide a strategy for mitigating ALI.

IL-33 controls IL-22-dependent antibacterial defense by modulating the microbiota

IL-22 plays a critical role in defending against mucosal infections, but how IL-22 production is regulated is incompletely understood. Here, we show that mice lacking IL-33 or its receptor ST2 (IL-1RL1) were more resistant to Streptococcus pneumoniae lung infection than wild-type animals and that single-nucleotide polymorphisms in IL33 and IL1RL1 were associated with pneumococcal pneumonia in humans. The effect of IL-33 on S. pneumoniae infection was mediated by negative regulation of IL-22 production in innate lymphoid cells (ILCs) but independent of ILC2s as well as IL-4 and IL-13 signaling. Moreover, IL-33's influence on IL-22-dependent antibacterial defense was dependent on housing conditions of the mice and mediated by IL-33's modulatory effect on the gut microbiota. Collectively, we provide insight into the bidirectional crosstalk between the innate immune system and the microbiota. We conclude that both genetic and environmental factors influence the gut microbiota, thereby impacting the efficacy of antibacterial immune defense and susceptibility to pneumonia.

Establishment of a Predictive Model for Acute Respiratory Distress Syndrome in Patients with Bacterial Pneumonia

Background

Community-acquired pneumonia (CAP) is a global health concern due to its high rates of morbidity and mortality. Bacterial pathogens are common causes of CAP. It is one of the most common causes of acute respiratory distress syndrome (ARDS), a common severe respiratory system manifestation threatening human health. This study aimed to establish a predictive model for ARDS in patients with bacterial pneumonia, which was conducive to early identification of the occurrence and effective prevention of ARDS.

Methods

We collected the clinical data of hospitalized patients with bacterial pneumonia in Affiliated Huzhou Hospital of Zhejiang University School of Medicine from January 2022 to November 2022. The independent risk factors for ARDS in patients with bacterial pneumonia were determined by univariate and multivariate binary logistic regression analyses. The nomogram was constructed to display the predictive model, and the receiver-operating characteristic curve was plotted to evaluate the predictive value of ARDS.

Results

This study included 254 patients with bacterial pneumonia, of which 114 developed ARDS. The multivariate logistic regression analysis revealed age [odds ratio (OR) = 1.041, P = 0.003], heart rate (OR = 1.020, P = 0.028), lymphocyte count (OR = 0.555, P = 0.033), white blood cell count (OR = 1.062, P = 0.033), bilateral lung lesions (OR = 7.352, P = 0.011) and pleural effusion (OR = 2.512, P = 0.002) as the independent risk factors for ARDS. The predictive model was constructed based on the six independent factors, which was valuable in predicting ARDS with area under the curve of 0.794.

Conclusion

The predictive model was beneficial to evaluate the disease progression in patients with bacterial pneumonia and identify ARDS. Further, our nomogram might help doctors predict the incidence of ARDS and conduct treatment as early as possible.

Broussonin E against acute respiratory distress syndrome: the potential roles of anti-inflammatory

We applied network pharmacology and molecular docking analyses to study the efficacy of Broussonin E (BRE) in acute respiratory distress syndrome (ARDS) treatment and to determine the core components, potential targets, and mechanism of action of BRE. The SwissTargetprediction and SEA databases were used to predict BRE targets, and the GeneCards and OMIM databases were used to predict ARDS-related genes. The drug targets and disease targets were mapped to obtain an intersecting drug target gene network, which was then uploaded into the String database for protein-protein interaction network analysis. The intersecting gene was also uploaded into the DAVID database for gene ontology enrichment analysis and Kyoto encyclopedia of genes and genomes pathway analysis. Molecular docking analysis was performed to verify the interaction of BRE with the key targets. Finally, to validate the experiment in vivo, we established an oleic acid-induced ARDS rat model and evaluated the protective effect of BRE on ARDS by histological evaluation and enzyme-linked immunosorbent assay. Overall, 79 targets of BRE and 3974 targets of ARDS were predicted, and 79 targets were obtained after intersection. Key genes such as HSP90AA1, JUN, ESR1, MTOR, and PIK3CA play important roles in the nucleus and cytoplasm by regulating the tumor necrosis factor, nuclear factor-κB, and PI3K-Akt signaling pathways. Molecular docking results showed that small molecules of BRE could freely bind to the active site of the target proteins. In vivo experiments showed that BRE could reduce ARDS-related histopathological changes, release of inflammatory factors, and infiltration of macrophages and oxidative stress reaction. BRE exerts its therapeutic effect on ARDS through target and multiple pathways. This study also predicted the potential mechanism of BRE on ARDS, which provides the theoretical basis for in-depth and comprehensive studies of BRE treatment on ARDS.

Immune Cell-Mediated Autoimmune Responses in Severe Asthma

Severe asthma (SA) has heterogeneous inflammatory phenotypes characterized by persistent airway inflammation (eosinophilic and/or neutrophilic inflammation) and remodeling. Various immune cells (eosinophils, neutrophils, and macrophages) become more activated and release inflammatory mediators and extracellular traps, damaging the protective barrier of airway epithelial cells and further activating other immune and structural cells. These cells play a role in autoimmune responses in asthmatic airways, where the adaptive immune system generates autoantibodies, inducing immunoglobulin G-dependent airway inflammation. Recent studies have suggested that adult asthmatics had high titers of autoantibodies associated with asthma severity, although pathogenic factors or diagnostic criteria are not well-defined. This challenge is further compounded by asthmatics with the autoimmune responses showing therapy insensitivity or failure to current pharmacological and biological treatment. This review updates emerging mechanisms of autoimmune responses in asthmatic airways and provides insights into their roles, proposing potential biomarkers and therapeutic targets for SA.

Advances of presepsin in sepsis-associated ARDS

This article reviews the correlation between presepsin and sepsis and the resulting acute respiratory distress syndrome (ARDS). ARDS is a severe complication of sepsis. Despite the successful application of protective mechanical ventilation, restrictive fluid therapy, and neuromuscular blockade, which have effectively reduced the morbidity and mortality associated with ARDS, the mortality rate among patients with sepsis-associated ARDS remains notably high. The challenge lies in the prediction of ARDS onset and the timely implementation of intervention strategies. Recent studies have demonstrated significant variations in presepsin (PSEP) levels between patients with sepsis and those without, particularly in the context of ARDS. Moreover, these studies have revealed substantially elevated PSEP levels in patients with sepsis-associated ARDS compared to those with nonsepsis-associated ARDS. Consequently, PSEP emerges as a valuable biomarker for identifying patients with an increased risk of sepsis-associated ARDS and to predict in-hospital mortality.

Pyroptosis: a double-edged sword in lung cancer and other respiratory diseases

Pyroptosis is an active cell death process mediated by gasdermin family proteins including Gasdermin A (GSDMA), Gasdermin B (GSDMB), Gasdermin C (GSDMC), Gasdermin D (GSDMD), Gasdermin E (GSDME, DFNA5), and DFNB59. Emerging evidences have shown that pyroptosis contributes to many pulmonary diseases, especially lung cancer, and pneumonia. The exact roles of pyroptosis and gasdermin family proteins are tremendously intricate. Besides, there are evidences that pyroptosis contributes to these respiratory diseases. However, it often plays a dual role in these diseases which is a cause for concern and makes it difficult for clinical translation. This review will focus on the multifaceted roles of pyroptosis in respiratory diseases.

Signaling pathways and potential therapeutic targets in acute respiratory distress syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a common condition associated with critically ill patients, characterized by bilateral chest radiographical opacities with refractory hypoxemia due to noncardiogenic pulmonary edema. Despite significant advances, the mortality of ARDS remains unacceptably high, and there are still no effective targeted pharmacotherapeutic agents. With the outbreak of coronavirus disease 19 worldwide, the mortality of ARDS has increased correspondingly. Comprehending the pathophysiology and the underlying molecular mechanisms of ARDS may thus be essential to developing effective therapeutic strategies and reducing mortality. To facilitate further understanding of its pathogenesis and exploring novel therapeutics, this review provides comprehensive information of ARDS from pathophysiology to molecular mechanisms and presents targeted therapeutics. We first describe the pathogenesis and pathophysiology of ARDS that involve dysregulated inflammation, alveolar-capillary barrier dysfunction, impaired alveolar fluid clearance and oxidative stress. Next, we summarize the molecular mechanisms and signaling pathways related to the above four aspects of ARDS pathophysiology, along with the latest research progress. Finally, we discuss the emerging therapeutic strategies that show exciting promise in ARDS, including several pharmacologic therapies, microRNA-based therapies and mesenchymal stromal cell therapies, highlighting the pathophysiological basis and the influences on signal transduction pathways for their use.

[Exosomes' role in intercellular interactions in different variants of lung injury in fatal cases of COVID-19]

BACKGROUND

Extracellular vesicles are surrounded by a phospholipid bilayer, carrying various active biomolecules and participating in many physiological and pathological processes, including infectious ones.

OBJECTIVE

To research the role of exosomes in intercellular interactions in the pathogenesis of various types of lung damage in fatal cases of COVID-19.

MATERIAL AND METHODS

We conducted a clinical and morphological analysis of 118 fatal cases caused by coronavirus infection in Moscow. We selected 32 cases with morphological signs of various types of lung lesions for immunohistochemical reaction (IHC) with antibodies against tetraspanin proteins (CD63, CD81), which are involved in the assembly of exosomes, as well as with antibodies against viral proteins: nucleocapsid and spike protein. We determined the main producing cells of extracellular vesicles and cells containing viral proteins, carried out their comparison and quantitative analysis.

RESULTS

IHC reaction with antibodies against CD63 showed cytoplasmic granular uniform and subapical staining of cells, as well as granular extracellular staining. We determined similar staining using antibodies against viral proteins. Extracellular vesicles were found in the same cells as viral proteins. The main producing cells of vesicles and cells containing viral proteins were found to be macrophages, type II pneumocytes, and endothelial cells.

CONCLUSION

Taking into account the results of the literature, the localization of viral proteins and extracellular vesicles in the same cells indicates the key role of vesicles in the pathogenesis of various forms of lung damage by the SARS-CoV-2 virus, in the dissemination of the pathogen in the organism, which leads to interaction with the adaptive immune system and the formation of immunity.

Design, QSAR Methodology, Synthesis and Assessment of Some Structurally Different Xanthone Derivatives as Selective Cox-2 Inhibitors for their Anti-inflammatory Properties

INTRODUCTION

Inflammation can be defined as a complex biological response that is produced by body tissues to harmful agents like pathogens, irritants, and damaged cells and thereby acts as a protective response incorporating immune cells, blood vessels, and molecular mediators. Histamine, serotonin, bradykinin, leukotrienes (LTB4), prostaglandins (PGE2), prostacyclins, reactive oxygen species, proinflammatory cytokines like IL-1, IL-11, TNF- anti-inflammatory cytokines like IL-4, IL-10, IL-11, IL-6 and IL-13, etc. all have different effects on both pro and anti-inflammatory mediators. Incorporation of combinatorial chemistry and computational studies have helped the researchers to design xanthones moieties with high selectivity that can serve as a lead compound and help develop potential compounds that can act as effective COX-2 inhibitors. The study aims to design and develop different series of substituted hydroxyxanthone derivatives with anti-inflammatory potential.

METHODS

The partially purified synthetic xanthone derivatives were orally administered to the carrageenan induced paw oedemic rat models at the dose of 100 mg/kg, and their effect in controlling the degree of inflammation was measured at the time interval of 30 min, 1, 2, 3, 4 and 6 hrs. respectively. Further, these compounds were also subjected to modern analytical studies like UV, IR, NMR and mass spectrometry or their characterization.

RESULTS

The results drawn out of the in silico, in vitro, in vivo and analytical studies concluded that the hydroxyxanthone derivatives can obstruct the enzyme COX-2 and produce anti-inflammatory action potentially.

CONCLUSION

With the aim to evaluate the compounds for their anti-inflammatory activity, it was observed that the newly designed xanthonic compounds also possess a safe toxicity margin and hence can be utilized by the researchers to develop hybrid xanthonic moieties that can specifically target the enzyme COX-2.

Airway epithelial cGAS inhibits LPS-induced acute lung injury through CREB signaling

Increased levels of cytosolic DNA in lung tissues play an important role in acute lung injury. However, the detailed mechanisms involved remain elusive. Here, we found that cyclic GMP-AMP synthase (cGAS, a cytosolic DNA sensor) expression was increased in airway epithelium in response to increased cytosolic DNA. Conditional deletion of airway epithelial cGAS exacerbated acute lung injury in mice, cGAS knockdown augmented LPS-induced production of interleukin (IL)-6 and IL-8. Mechanically, deletion of cGAS augmented expression of phosphorylated CREB (cAMP response element-binding protein), and cGAS directly interacted with CREB via its C-terminal domain. Furthermore, CREB knockdown rescued the LPS-induced excessive inflammatory response caused by cGAS deletion. Our study demonstrates that airway epithelial cGAS plays a protective role in acute lung injury and confirms a non-canonical cGAS-CREB pathway that regulates the inflammatory responses in airway epithelium to mediate LPS-induced acute lung injury.

A critical assessment of the cellular defences of the avian respiratory system: are birds in general and poultry in particular relatively more susceptible to pulmonary infections/afflictions?

In commercial poultry farming, respiratory diseases cause high morbidities and mortalities, begetting colossal economic losses. Without empirical evidence, early observations led to the supposition that birds in general, and poultry in particular, have weak innate and adaptive pulmonary defences and are therefore highly susceptible to injury by pathogens. Recent findings have, however, shown that birds possess notably efficient pulmonary defences that include: (i) a structurally complex three-tiered airway arrangement with aerodynamically intricate air-flow dynamics that provide efficient filtration of inhaled air; (ii) a specialised airway mucosal lining that comprises air-filtering (ciliated) cells and various resident phagocytic cells such as surface and tissue macrophages, dendritic cells and lymphocytes; (iii) an exceptionally efficient mucociliary escalator system that efficiently removes trapped foreign agents; (iv) phagocytotic atrial and infundibular epithelial cells; (v) phagocytically competent surface macrophages that destroy pathogens and injurious particulates; (vi) pulmonary intravascular macrophages that protect the lung from the vascular side; and (vii) proficiently phagocytic pulmonary extravasated erythrocytes. Additionally, the avian respiratory system rapidly translocates phagocytic cells onto the respiratory surface, ostensibly from the subepithelial space and the circulatory system: the mobilised cells complement the surface macrophages in destroying foreign agents. Further studies are needed to determine whether the posited weak defence of the avian respiratory system is a global avian feature or is exclusive to poultry. This review argues that any inadequacies of pulmonary defences in poultry may have derived from exacting genetic manipulation(s) for traits such as rapid weight gain from efficient conversion of food into meat and eggs and the harsh environmental conditions and severe husbandry operations in modern poultry farming. To reduce pulmonary diseases and their severity, greater effort must be directed at establishment of optimal poultry housing conditions and use of more humane husbandry practices.

The rate of ward to intensive care transfer and its predictors among hospitalized COPD patients, a retrospective study in a local tertiary center in Saudi Arabia

OBJECTIVE

To investigate the prevalence of intensive care unit (ICU) admission and its predictors among hospitalized chronic obstructive pulmonary disease (COPD) patients.

METHODS

An observational retrospective study was conducted. All patients with a confirmed diagnosis of COPD according to the GOLD guidelines between 28 and 2020 and 1 March 2023 at Al-Noor Specialist Hospital were included in this study. Patients were excluded if a preemptive diagnosis of COPD was made clinically without spirometry evidence of fixed airflow limitation. Descriptive results were presented as frequency (percentage) for categorical variables and mean (SD) for continuous variables and to estimate prevalence of ICU admission. Predictors of ICU admission among hospitalized COPD patients were determined using logistic regression analysis. A SPSS (Statistical Package for the Social Sciences) version 25 was used to perform all statistical analysis.

RESULTS

A total of 705 patients with COPD were included in this study. The mean age was 65.4 (25.3) years. Around 12.4% of the hospitalized patients were admitted to the ICD. Logistic regression analysis identified that older age (OR; 1.92, (1.41-2.62)), smoking (OR; 1.60 (1.17-2.19)), and having specific comorbidities (Hypertension (OR; 1.98 (1.45-2.71)), Diabetes mellitus (OR; 1.42 (1.04-1.93)), GERD (OR; 2.81 (1.99-3.96)), Ischemic heart disease (OR; 3.22 (2.19-4.75)), Obstructive sleep apnea syndrome (OR; 2.14 (1.38-3.33)), stroke (OR; 4.51 (2.20-9.26))) were predictors of ICU admissions among patients with COPD.

CONCLUSIONS

Our study found that a step-up approach to inpatient COPD management requires admission to the ICU in 12.4%, for which age, smoking status, cardiovascular, and stroke were important predictors. Further clinical research is needed to provide a validated model that can be incorporated into clinical practice to monitor this patient population during their admission and identify at-risk individuals for early transfer to higher acuity settings and intensive care units.

A Disintegrin and Metalloproteinase with Thrombospondin Motifs 4 Regulates Pulmonary Vascular Hyperpermeability through Destruction of Glycocalyx in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) has no specific and effective treatment, and there is an urgent need to understand its pathogenesis. Therefore, based on the hypothesis that molecules whose expression is upregulated in injured pulmonary vascular endothelial cells (VECs) are involved in the pathogenesis of ARDS, we conducted a study to elucidate the molecular mechanisms and identify target factors for treatment. Primary human lung microvascular endothelial cells (HMVEC-Ls) were stimulated with lipopolysaccharide (LPS) or poly (I:C) and analyzed via a microarray to identify target genes for ARDS. We found that a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4) was induced in murine lung VECs in an LPS-mediated ARDS model. Elevated ADAMTS4 was also observed by the immunostaining of lung samples from ARDS patients. The suppression of ADAMTS4 by siRNA in VECs ameliorated LPS-stimulated vascular permeability. The impairment of the cell surface expression of syndecan-1, a marker of the glycocalyx that is an extracellular matrix involved in vascular permeability, was dramatically inhibited by ADAMTS4 suppression. In addition, the suppression of ADAMTS4 protected against LPS-induced reductions in syndecan-1 and the adherens junction protein vascular endothelial cadherin. These results suggest that ADAMTS4 regulates VEC permeability in ARDS and may be a predictive marker and therapeutic target for ARDS.

Immunology in COPD and the use of combustible cigarettes and heated tobacco products

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic respiratory diseases, characterised by high morbidity and mortality. COPD is characterised by a progressive decline of lung function caused by chronic inflammatory reactions in the lung tissue due to continual exposure to harmful molecules by inhalation. As prevention plays a very important role in COPD, quitting smoking is the most important factor in reducing the decline in lung function. Unfortunately, many people are unable to break their nicotine addiction. This paper summarises current knowledge about combustible cigarettes (CSs) and alternative tobacco products such as heated tobacco products (HTPs) in COPD. The paper focuses on the immunological aspects of COPD and the influence of tobacco products on lung tissue immunology. There are differences in research results between HTPs and CSs in favour of HTPs. More long-term studies are needed to look at the effects of HTPs, especially in COPD. However, there is no doubt that it would be best for patients to give up their nicotine addiction completely.

Plausibility of natural immunomodulators in the treatment of COVID-19-A comprehensive analysis and future recommendations

The COVID-19 pandemic has inflicted millions of deaths worldwide. Despite the availability of several vaccines and some special drugs approved for emergency use to prevent or treat this disease still, there is a huge concern regarding their effectiveness, adverse effects, and most importantly, their efficacy against the new variants. A cascade of immune-inflammatory responses is involved with the pathogenesis and severe complications with COVID-19. People with dysfunctional and compromised immune systems display severe complications, including acute respiratory distress syndrome, sepsis, multiple organ failure etc., when they get infected with the SARS-CoV-2 virus. Plant-derived natural immune-suppressant compounds, such as resveratrol, quercetin, curcumin, berberine, luteolin, etc., have been reported to inhibit pro-inflammatory cytokines and chemokines. Therefore, natural products with immunomodulatory and anti-inflammatory potential could be plausible targets to treat this contagious disease. This review aims to delineate the clinical trials status and outcomes of natural compounds with immunomodulatory potential in COVID-19 patients along with the outcomes of their in-vivo studies. In clinical trials several natural immunomodulators resulted in significant improvement of COVID-19 patients by diminishing COVID-19 symptoms such as fever, cough, sore throat, and breathlessness. Most importantly, they reduced the duration of hospitalization and the need for supplemental oxygen therapy, improved clinical outcomes in patients with COVID-19, especially weakness, and eliminated acute lung injury and acute respiratory distress syndrome. This paper also discusses many potent natural immunomodulators yet to undergo clinical trials. In-vivo studies with natural immunomodulators demonstrated reduction of a wide range of proinflammatory cytokines. Natural immunomodulators that were found effective, safe, and well tolerated in small-scale clinical trials are warranted to undergo large-scale trials to be used as drugs to treat COVID-19 infections. Alongside, compounds yet to test clinically must undergo clinical trials to find their effectiveness and safety in the treatment of COVID-19 patients.

Targeting TLR4/3 using chlorogenic acid ameliorates LPS+POLY I:C-induced acute respiratory distress syndrome via alleviating oxidative stress-mediated NLRP3/NF-κB axis

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is a life-threatening condition caused due to significant pulmonary and systemic inflammation. Chlorogenic acid (CGA) has been shown to possess potent antioxidant, anti-inflammatory, and immunoprotective properties. However, the protective effect of CGA on viral and bacterial-induced ALI/ARDS is not yet explored. Hence, the current study is aimed to evaluate the preclinical efficacy of CGA in lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (POLY I:C)-induced ALI/ARDS models in vitro and in vivo. Human airway epithelial (BEAS-2B) cells exposed to LPS+POLY I:C significantly elevated oxidative stress and inflammatory signaling. Co-treatment with CGA (10 and 50 µM) prevented inflammation and oxidative stress mediated by TLR4/TLR3 and NLRP3 inflammasome axis. BALB/c mice, when chronically challenged with LPS+POLY I:C showed a significant influx of immune cells, up-regulation of pro-inflammatory cytokines, namely: IL-6, IL-1β, and TNF-α, and treatment with intranasal CGA (1 and 5 mg/kg) normalized the elevated levels of immune cell infiltration as well as pro-inflammatory cytokines. D-Dimer, the serum marker for intravascular coagulation, was significantly increased in LPS+ POLY I:C challenged animals which was reduced with CGA treatment. Further, CGA treatment also has a beneficial effect on the lung and heart, as shown by improving lung physiological and cardiac functional parameters accompanied by the elevated antioxidant response and simultaneous reduction in tissue damage caused by LPS+POLY I:C co-infection. In summary, these comprehensive, in vitro and in vivo studies suggest that CGA may be a viable therapeutic option for bacterial and viral-induced ALI-ARDS-like pathology.

Sulfasalazine prevents lung injury due to intra-abdominal sepsis in rats: possible role of Nrf2 and angiopoietin-2

This study aimed to investigate the effect of sulfasalazine in preventing and treating intra-abdominal sepsis-induced acute respiratory distress syndrome (ARDS) in a rat model. Forty male Wistar albino rats were used. The rats were randomly divided into four equal groups, and sepsis was induced in 30 rats by intraperitoneal administration of a fecal saline solution prepared from rat feces. Group 1: normal control (n=10) [non-surgical], Group 2: fecal intraperitoneal injection (FIP) (n=10) [untreated septic group], Group 3: FIP+saline (placebo) (n=10) [saline administered intraperitoneally], Group 4 (n=10): FIP+sulfasalazine [250 mg/kg per day administered intraperitoneally]. Computed tomography was performed and blood samples were collected for biochemical and blood gas analysis. The lungs were removed for histopathological studies. Statistically significant reductions in interleukin (IL)-6, IL1-β, tumor necrosis factor (TNF)-α, malondialdehyde (MDA), and angiopoietin-2 (ANG-2) levels were observed in the sulfasalazine group compared to the FIP+saline group (P<0.001). Nrf2 levels were significantly higher in the sulfasalazine-treated group than in the FIP and FIP+saline groups (P<0.01). Lung tissue scores were significantly reduced in the sulfasalazine group compared to the other sepsis groups. The Hounsfield unit (HU) value was significantly lower in the sulfasalazine group than in the FIP+saline group (P<0.001). PaO2 values were significantly higher in the sulfasalazine-treated group than in the FIP+saline-treated group (P<0.05). Sulfasalazine was shown to be effective in preventing and treating ARDS.

A Diagnostic Classifier Based on Circulating miRNA Pairs for COPD Using a Machine Learning Approach

Chronic obstructive pulmonary disease (COPD) is highly underdiagnosed, and early detection is urgent to prevent advanced progression. Circulating microRNAs (miRNAs) have been diagnostic candidates for multiple diseases. However, their diagnostic value has not yet been fully established in COPD. The purpose of this study was to develop an effective model for the diagnosis of COPD based on circulating miRNAs. We included circulating miRNA expression profiles of two independent cohorts consisting of 63 COPD and 110 normal samples, and then we constructed a miRNA pair-based matrix. Diagnostic models were developed using several machine learning algorithms. The predictive performance of the optimal model was validated in our external cohort. In this study, the diagnostic values of miRNAs based on the expression levels were unsatisfactory. We identified five key miRNA pairs and further developed seven machine learning models. The classifier based on LightGBM was selected as the final model with the area under the curve (AUC) values of 0.883 and 0.794 in test and validation datasets, respectively. We also built a web tool to assist diagnosis for clinicians. Enriched signaling pathways indicated the potential biological functions of the model. Collectively, we developed a robust machine learning model based on circulating miRNAs for COPD screening.

In Vitro Characteristics of Canine Primary Tracheal Epithelial Cells Maintained at an Air-Liquid Interface Compared to In Vivo Morphology

Culturing respiratory epithelial cells at an air-liquid interface (ALI) represents an established method for studies on infection or toxicology by the generation of an in vivo-like respiratory tract epithelial cellular layer. Although primary respiratory cells from a variety of animals have been cultured, an in-depth characterization of canine tracheal ALI cultures is lacking despite the fact that canines are a highly relevant animal species susceptible to various respiratory agents, including zoonotic pathogens such as severe acute respiratory coronavirus 2 (SARS-CoV-2). In this study, canine primary tracheal epithelial cells were cultured under ALI conditions for four weeks, and their development was characterized during the entire culture period. Light and electron microscopy were performed to evaluate cell morphology in correlation with the immunohistological expression profile. The formation of tight junctions was confirmed using transepithelial electrical resistance (TEER) measurements and immunofluorescence staining for the junctional protein ZO-1. After 21 days of culture at the ALI, a columnar epithelium containing basal, ciliated and goblet cells was seen, resembling native canine tracheal samples. However, cilia formation, goblet cell distribution and epithelial thickness differed significantly from the native tissue. Despite this limitation, tracheal ALI cultures could be used to investigate the pathomorphological interactions of canine respiratory diseases and zoonotic agents.

Specific upregulation of extracellular miR-6238 in particulate matter-induced acute lung injury and its immunomodulation

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening diseases characterized by a severe inflammatory response and the destruction of alveolar epithelium and endothelium. ALI/ARDS is caused by pathogens and toxic environmental stimuli, such as particulate matter (PM). However, the general symptoms of ALI/ARDS are similar, and determining the cause of lung injury is often challenging. In this study, we investigated whether there is a critical miRNA that characterizes PM-induced ALI. We found that the expression of miR-6238 is specifically upregulated in lung tissue and lung-derived extracellular vesicles (EVs) in response to PM exposure. Notably, bacterial endotoxin (Lipopolysaccharide; LPS or peptidoglycan; PTG) does not induce the expression of miR-6238 in the lung. Instead, the expression of miR-155 is dramatically increased in LPS-induced ALI. We further demonstrated that human lung epithelial cells and macrophages predominantly produce miR-6238 and miR-155, respectively. Mechanistically, EV-miR-6238 is effectively internalized into alveolar macrophages (AMs) and regulates inflammatory responses in vivo. CXCL3 is a main target of miR-6238 in AMs and modulates neutrophil infiltration into the lung alveoli. Collectively, our findings suggest that miR-6238 is a novel regulator of pulmonary inflammation and a putative biomarker that distinguishes PM-induced ALI from endotoxin (LPS/PTG)-mediated ALI.

Impact of chronic cold exposure on lung inflammation, pyroptosis and oxidative stress in mice

Chronic cold exposure, which is the main inducer of lung diseases in high latitudes, affects production efficiency and restricts the development of aquaculture. Although the relationship between cold exposure and susceptibility to the lungs is widely accepted, but the influence between them has not been fully explored. The aim of this study is to understand the underlying mechanism. In the present study, the mice, which are used to establish cold stress (CS)-induced lung injury model, are exposed to cold temperature (4 °C) for 3 h each day for 4 weeks. The results indicate that the expression of heat shock protein 70 (HSP70) is augmented by cold exposure. In addition, chronic cold exposure aggravate the formation of malondialdehyde (MDA) and lead to a significant decrease in the contents of micrococcus catalase (CAT) and glutathione (GSH). Moreover, chronic cold exposure significantly exacerbates the expression of inflammation- and apoptosis-related proteins. The activation of Bax and caspase-3 are significantly augmented. However, that of Bcl-2 is decreased. These results are different from those in room team. The results show that chronic cold exposure plays an important roles in the activation of multiple signaling pathways, such as pyroptosis-related, inflammation-related and oxidative stress-regulated signaling pathways. In summary, these investigations support that chronic cold exposure increase the risk of lung injury by activating inflammation, oxidative stress and pyroptosis.

Pharmacologic therapies of ARDS: From natural herb to nanomedicine

Acute respiratory distress syndrome (ARDS) is a common critical illness in respiratory care units with a huge public health burden. Despite tremendous advances in the prevention and treatment of ARDS, it remains the main cause of intensive care unit (ICU) management, and the mortality rate of ARDS remains unacceptably high. The poor performance of ARDS is closely related to its heterogeneous clinical syndrome caused by complicated pathophysiology. Based on the different pathophysiology phases, drugs, protective mechanical ventilation, conservative fluid therapy, and other treatment have been developed to serve as the ARDS therapeutic methods. In recent years, there has been a rapid development in nanomedicine, in which nanoparticles as drug delivery vehicles have been extensively studied in the treatment of ARDS. This study provides an overview of pharmacologic therapies for ARDS, including conventional drugs, natural medicine therapy, and nanomedicine. Particularly, we discuss the unique mechanism and strength of nanomedicine which may provide great promises in treating ARDS in the future.

NOD2 Signaling Circuitry during Allergen Sensitization Does Not Worsen Experimental Neutrophilic Asthma but Promotes a Th2/Th17 Profile in Asthma Patients but Not Healthy Subjects

Nucleotide-binding oligomerization domain 2 (NOD2) recognizes pathogens associated with the development of asthma. Moreover, NOD2 adjuvants are used in vaccine design to boost immune responses. Muramyl di-peptide (MDP) is a NOD2 ligand, which is able to promote Th2/Th17 responses. Furthermore, polymorphisms of the NOD2 receptor are associated with allergy and asthma development. This study aimed to evaluate if MDP given as an adjuvant during allergen sensitization may worsen the development of Th2/Th17 responses. We used a mouse model of Th2/Th17-type allergic neutrophil airway inflammation (AAI) to dog allergen, with in vitro polarization of human naive T cells by dendritic cells (DC) from healthy and dog-allergic asthma subjects. In the mouse model, intranasal co-administration of MDP did not modify the AAI parameters, including Th2/Th17-type lung inflammation. In humans, MDP co-stimulation of allergen-primed DC did not change the polarization profile of T cells in healthy subjects but elicited a Th2/Th17 profile in asthma subjects, as compared with MDP alone. These results support the idea that NOD2 may not be involved in the infection-related development of asthma and that, while care has to be taken in asthma patients, NOD2 adjuvants might be used in non-sensitized individuals.

Therapeutic Benefits of Mesenchymal Stem Cells in Acute Respiratory Distress Syndrome: Potential Mechanisms and Challenges

Acute respiratory distress syndrome (ARDS) presents as a form of acute respiratory failure resulting from non-cardiogenic pulmonary edema due to excessive alveolocapillary permeability, which may be pulmonary or systemic in origin. In the last 3 years, the coronavirus disease 2019 pandemic has resulted in an increase in ARDS cases and highlighted the challenges associated with this syndrome, as well as the unacceptably high mortality rates and lack of effective treatments. Currently, clinical treatment remains primarily supportive, including mechanical ventilation and drug-based therapy. Mesenchymal stem cell (MSC) therapies are emerging as a promising intervention in patients with ARDS and have promising therapeutic effects and safety. The therapeutic mechanisms include modifying the immune response and assisting with tissue repair. This review provides an overview of the general properties of MSCs and outlines their role in mitigating lung injury and promoting tissue repair in ARDS. Finally, we summarize the current challenges in the study of translational MSC research and identify avenues by which the discipline may progress in the coming years.

Allyl methyl trisulfide protected against LPS-induced acute lung injury in mice via inhibition of the NF-κB and MAPK pathways

Allyl methyl trisulfide (AMTS) is one major lipid-soluble organosulfur compound of garlic. Previous studies have reported the potential therapeutic effect of garlic on acute lung injury (ALI) or its severe condition acute respiratory distress syndrome (ARDS), but the specific substances that exert the regulatory effects are still unclear. In this study, we investigate the protective effects of AMTS on lipopolysaccharide (LPS)-induced ALI mice and explored the underlying mechanisms. In vivo experiments, ICR mice were pretreated with 25–100 mg/kg AMTS for 7 days and followed by intratracheal instillation of LPS (1.5 mg/kg). The results showed that AMTS significantly attenuated LPS-induced deterioration of lung pathology, demonstrated by ameliorative edema and protein leakage, and improved pulmonary histopathological morphology. Meanwhile, the expression of inflammatory mediators and the infiltration of inflammation-regulation cells induced by LPS were also inhibited. In vitro experiments also revealed that AMTS could alleviate inflammation response and inhibit the exaggeration of macrophage M1 polarization in LPS-induced RAW264.7 cells. Mechanistically, we identified that AMTS treatment could attenuate the LPS-induced elevation of protein expression of p-IκBα, nuclear NF-κB-p65, COX2, iNOS, p-P38, p-ERK1/2, and p-JNK. Collectively, these data suggest that AMTS could attenuate LPS-induced ALI and the molecular mechanisms should be related to the suppression of the NF-κB and MAPKs pathways.

Epigenetic underpinnings of inflammation: Connecting the dots between pulmonary diseases, lung cancer and COVID-19

Inflammation is an essential component of several respiratory diseases, such as chronic obstructive pulmonary disease (COPD), asthma and acute respiratory distress syndrome (ARDS). It is central to lung cancer, the leading cancer in terms of associated mortality that has affected millions of individuals worldwide. Inflammation and pulmonary manifestations are also the major causes of COVID-19 related deaths. Acute hyperinflammation plays an important role in the COVID-19 disease progression and severity, and development of protective immunity against the virus is greatly sought. Further, the severity of COVID-19 is greatly enhanced in lung cancer patients, probably due to the genes such as ACE2, TMPRSS2, PAI-1 and furin that are commonly involved in cancer progression as well as SAR-CoV-2 infection. The importance of inflammation in pulmonary manifestations, cancer and COVID-19 calls for a closer look at the underlying processes, particularly the associated increase in IL-6 and other cytokines, the dysregulation of immune cells and the coagulation pathway. Towards this end, several reports have identified epigenetic regulation of inflammation at different levels. Expression of several key inflammation-related cytokines, chemokines and other genes is affected by methylation and acetylation while non-coding RNAs, including microRNAs as well as long non-coding RNAs, also affect the overall inflammatory responses. Select miRNAs can regulate inflammation in COVID-19 infection, lung cancer as well as other inflammatory lung diseases, and can serve as epigenetic links that can be therapeutically targeted. Furthermore, epigenetic changes also mediate the environmental factors-induced inflammation. Therefore, a better understanding of epigenetic regulation of inflammation can potentially help develop novel strategies to prevent, diagnose and treat chronic pulmonary diseases, lung cancer and COVID-19.

Intestinal Microbiota - An Unmissable Bridge to Severe Acute Pancreatitis-Associated Acute Lung Injury

Severe acute pancreatitis (SAP), one of the most serious abdominal emergencies in general surgery, is characterized by acute and rapid onset as well as high mortality, which often leads to multiple organ failure (MOF). Acute lung injury (ALI), the earliest accompanied organ dysfunction, is the most common cause of death in patients following the SAP onset. The exact pathogenesis of ALI during SAP, however, remains unclear. In recent years, advances in the microbiota-gut-lung axis have led to a better understanding of SAP-associated lung injury (PALI). In addition, the bidirectional communications between intestinal microbes and the lung are becoming more apparent. This paper aims to review the mechanisms of an imbalanced intestinal microbiota contributing to the development of PALI, which is mediated by the disruption of physical, chemical, and immune barriers in the intestine, promotes bacterial translocation, and results in the activation of abnormal immune responses in severe pancreatitis. The pathogen-associated molecular patterns (PAMPs) mediated immunol mechanisms in the occurrence of PALI via binding with pattern recognition receptors (PRRs) through the microbiota-gut-lung axis are focused in this study. Moreover, the potential therapeutic strategies for alleviating PALI by regulating the composition or the function of the intestinal microbiota are discussed in this review. The aim of this study is to provide new ideas and therapeutic tools for PALI patients.

Uterus globulin associated protein 1 (UGRP1) binds podoplanin (PDPN) to promote a novel inflammation pathway during Streptococcus pneumoniae infection

Background

Streptococcus pneumoniae is the major cause of life‐threatening infections. Toll‐like receptors (TLRs) and NOD‐like receptors (NLRs) could recognise S. pneumoniae and regulate the production of pro‐inflammatory cytokines. UGRP1, highly expressed in lung, is predominantly secreted in airways. However, the function of UGRP1 in pneumonia is mainly unknown.

Methods and results

We showed that upon TLR2/TLR4/NOD2 agonists stimulation or S. pneumoniae infection, treatment with UGRP1 could promote phosphorylation of p65 and enhance IL‐6, IL‐1β and TNFα production in macrophages. We further elucidated that after binding with cell‐surface receptor PDPN, UGRP1 could activate RhoA to enhance interaction of IKKγ and IKKβ, which slightly activated NF‐κB to improve expression of TLR2, MyD88, NOD2 and NLRP3. Deletion of UGRP1 or blocking UGRP1 interaction with PDPN protected mice against S. pneumoniae‐induced severe pneumococcal pneumonia, and activating RhoA with agonist in UGRP1‐deficient mice restored the reduced IL‐6 production.

Conclusion

We demonstrated that UGRP1–PDPN–RhoA signaling could activate NF‐κB to promote expression of TLR2, MyD88, NOD2 and NLRP3, which enhanced inflammatory cytokines secretion during S. pneumoniae infection. Antibodies, which could interrupt interaction of UGRP1 and PDPN, are potential therapeutics against S. pneumoniae.

Title-Inflammatory Signaling Pathways in Allergic and Infection-Associated Lung Diseases

Lung inflammation can be caused by pathogen infection alone or by allergic disease, leading to pneumonitis. Most of the allergens (antigens) that cause allergic lung diseases, including asthma and hypersensitivity pneumonitis (HP), are derived from microorganisms, such as bacteria, viruses, and fungi, but some inorganic materials, such as mercury, can also cause pneumonitis. Certain allergens, including food and pollen, can also cause acute allergic reactions and lead to lung inflammation in individuals predisposed to such reactions. Pattern recognition-associated and damage-associated signaling by these allergens can be critical in determining the type of hypersensitization and allergic disease, as well as the potential for fibrosis and irreversible lung damage. This review discusses the signs, symptoms, and etiology of allergic asthma, and HP. Furthermore, we review the immune response and signaling pathways involved in pneumonitis due to both microbial infection and allergic processes. We also discuss current and potential therapeutic interventions for infection-associated and allergic lung inflammation.

Epithelial‑derived exosomes promote M2 macrophage polarization via Notch2/SOCS1 during mechanical ventilation

Alveolar macrophages (AMs) play an essential role in ventilator-induced lung injury (VILI). Exosomes and their cargo, including microRNAs (miRNAs/miRs) serve as regulators of the intercellular communications between macrophages and epithelial cells (ECs), and are involved in maintaining homeostasis in lung tissue. The present study found that exosomes released by ECs subjected to cyclic stretching promoted M2 macrophage polarization. It was demonstrated that miR-21a-5p, upregulated in epithelial-derived exosomes, increased the percentage of M2 macrophages by suppressing the expression of Notch2 and the suppressor of cytokine signaling 1 (SOCS1). The overexpression of Notch2 decreased the percentage of M2 macrophages. However, these effects were reversed by the downregulation of SOCS1. The percentage of M2 macrophages was increased in both short-term high- and low-tidal-volume mechanical ventilation, and the administration of exosomes-derived from cyclically stretched ECs had the same function. However, the administration of miR-21a-5p antagomir decreased M2 macrophage activation induced by cyclically stretched ECs or ventilation. Thus, the present study demonstrates that the intercellular transferring of exosomes from ECs to AMs promotes M2 macrophage polarization. Exosomes may prove to be a novel treatment for VILI.

Ethanol Intoxication Impairs Respiratory Function and Bacterial Clearance and Is Associated With Neutrophil Accumulation in the Lung After Streptococcus pneumoniae Infection

Alcohol consumption is commonplace in the United States and its prevalence has increased in recent years. Excessive alcohol use is linked to an increased risk of infections including pneumococcal pneumonia, mostly commonly caused by Streptococcus pneumoniae. In addition, pneumonia patients with prior alcohol use often require more intensive treatment and longer hospital stays due to complications of infection. The initial respiratory tract immune response to S. pneumoniae includes the production of pro-inflammatory cytokines and chemokines by resident cells in the upper and lower airways which activate and recruit leukocytes to the site of infection. However, this inflammation must be tightly regulated to avoid accumulation of toxic by-products and subsequent tissue damage. A majority of previous work on alcohol and pneumonia involve animal models utilizing high concentrations of ethanol or chronic exposure and offer conflicting results about how ethanol alters immunity to pathogens. Further, animal models often employ a high bacterial inoculum which may overwhelm the immune system and obscure results, limiting their applicability to the course of human infection. Here, we sought to determine how a more moderate ethanol exposure paradigm affects respiratory function and innate immunity in mice after intranasal infection with 10⁴ colony forming units of S. pneumoniae. Ethanol-exposed mice displayed respiratory dysfunction and impaired bacterial clearance after infection compared to their vehicle-exposed counterparts. This altered response was associated with increased gene expression of neutrophil chemokines Cxcl1 and Cxcl2 in whole lung homogenates, elevated concentrations of circulating granulocyte-colony stimulating factor (G-CSF), and higher neutrophil numbers in the lung 24 hours after infection. Taken together, these findings suggest that even a more moderate ethanol consumption pattern can dramatically modulate the innate immune response to S. pneumoniae after only 3 days of ethanol exposure and provide insight into possible mechanisms related to the compromised respiratory immunity seen in alcohol consumers with pneumonia.

Immunomodulation via MyD88-NFκB Signaling Pathway from Human Umbilical Cord-Derived Mesenchymal Stem Cells in Acute Lung Injury

Excess inflammatory processes play a key detrimental role in the pathophysiology of acute lung injury (ALI). Mesenchymal stem cells (MSCs) were reported to be beneficial to ALI, but the underlying mechanisms have not been completely understood. The present study aimed to examine the involvement of MyD88−NFκB signaling in the immunomodulation of MSCs in mice with lipopolysaccharides (LPS)-induced ALI. We found that serum concentrations of IL-6, TNF-α, MCP-1, IL-1β, and IL-8 were significantly decreased at 6 h after LPS-induced ALI in the MSC group (p < 0.05). For each of the five cytokines, the serum concentration of each individual mouse in either group declined to a similar level at 48 h. The intensity of lung injury lessened in the MSC group, as shown by histopathology and lung injury scores (p < 0.001). The expressions of MyD88 and phospho-NFκB in the lung tissue were significantly decreased in mice receiving MSCs as measured by Western blotting and immunohistochemistry. Our data demonstrated that human umbilical cord-derived MSCs could effectively alleviate the cytokine storm in mice after LPS-induced ALI and attenuated lung injury. Firstly, we documented the correlation between the down-regulation of MyD88−NFκB signaling and immunomodulatory effects of MSCs in the situation of ALI.

The Role of Airway Epithelial Cell Alarmins in Asthma

The airway epithelium is the first line of defense for the lungs, detecting inhaled environmental threats through pattern recognition receptors expressed transmembrane or intracellularly. Activation of pattern recognition receptors triggers the release of alarmin cytokines IL-25, IL-33, and TSLP. These alarmins are important mediators of inflammation, with receptors widely expressed in structural cells as well as innate and adaptive immune cells. Many of the key effector cells in the allergic cascade also produce alarmins, thereby contributing to the airways disease by driving downstream type 2 inflammatory processes. Randomized controlled clinical trials have demonstrated benefit when blockade of TSLP and IL-33 were added to standard of care medications, suggesting these are important new targets for treatment of asthma. With genome-wide association studies demonstrating associations between single-nucleotide polymorphisms of the TSLP and IL-33 gene and risk of asthma, it will be important to understand which subsets of asthma patients will benefit most from anti-alarmin therapy.

Immunomodulation by Tetracyclines in the Critically Ill: An Emerging Treatment Option?

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2022. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2022 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901 .

Nano-Enabled Reposition of Proton Pump Inhibitors for TLR Inhibition: Toward A New Targeted Nanotherapy for Acute Lung Injury

Toll-like receptor (TLR) activation in macrophages plays a critical role in the pathogenesis of acute lung injury (ALI). While TLR inhibition is a promising strategy to control the overwhelming inflammation in ALI, there still lacks effective TLR inhibitors for clinical uses to date. A unique class of peptide-coated gold nanoparticles (GNPs) is previously discovered, which effectively inhibited TLR signaling and protected mice from lipopolysaccharide (LPS)-induced ALI. To fast translate such a discovery into potential clinical applicable nanotherapeutics, herein an elegant strategy of "nano-enabled drug repurposing" with "nano-targeting" is introduced to empower the existing drugs for new uses. Combining transcriptome sequencing with Connectivity Map analysis, it is identified that the proton pump inhibitors (PPIs) share similar mechanisms of action to the discovered GNP-based TLR inhibitor. It is confirmed that PPIs (including omeprazole) do inhibit endosomal TLR signaling and inflammatory responses in macrophages and human peripheral blood mononuclear cells, and exhibits anti-inflammatory activity in an LPS-induced ALI mouse model. The omeprazole is then formulated into a nanoform with liposomes to enhance its macrophage targeting ability and the therapeutic efficacy in vivo. This research provides a new translational strategy of nano-enabled drug repurposing to translate bioactive nanoparticles into clinically used drugs and targeted nano-therapeutics for ALI.

Antibiotics as immunomodulators: a potential pharmacologic approach for ARDS treatment

First described in the mid-1960s, acute respiratory distress syndrome (ARDS) is a life-threatening form of respiratory failure with an overall mortality rate of approximately 40%. Despite significant advances in the understanding and treatment of ARDS, no substantive pharmacologic therapy has proven to be beneficial, and current management continues to be primarily supportive. Beyond their antibacterial activity, several antibiotics such as macrolides and tetracyclines exert pleiotropic immunomodulatory effects that might be able to rectify the dysregulated inflammatory response present in patients with ARDS. This review aims to provide an overview of preclinical and clinical studies that describe the immunomodulatory effects of antibiotics in ARDS. Moreover, the underlying mechanisms of their immunomodulatory properties will be discussed. Further studies are necessary to investigate their full therapeutic potential and to identify ARDS phenotypes which are most likely to benefit from their immunomodulatory effects.

GHS-R1a deficiency mitigates lipopolysaccharide-induced lung injury in mice via the downregulation of macrophage activity

Acute respiratory distress syndrome (ARDS) is a critical illness syndrome characterized by dysregulated pulmonary inflammation. Currently, effective pharmacological treatments for ARDS are unavailable. Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor type 1a (GHS-R1a), has a pivotal role in regulating energy metabolism and immunomodulation. The role of endogenous ghrelin in ARDS remains unresolved. Herein, we investigated the role of endogenous ghrelin signaling by using GHS-R1a-null (ghsr^-/-) mice and lipopolysaccharide (LPS)-induced ARDS model. Ghsr^-/- mice survived longer than controls after LPS-induced lung injury. Ghsr^-/- mice showed lower levels of pro-inflammatory cytokines and higher oxygenation levels after lung injury. The peritoneal macrophages isolated from ghsr^-/- mice exhibited lower levels of cytokines production and oxygen consumption rate after LPS stimulation. Our results indicated that endogenous ghrelin plays a pivotal role in initiation and continuation in acute inflammatory response in LPS-induced ARDS model by modulating macrophage activity, and highlighted endogenous GHS-R1a signaling in macrophage as a potential therapeutic target in this relentless disease.

Neutrophil-Dependent Immunity During Pulmonary Infections and Inflammations

Rapid recruitment of neutrophils to an inflamed site is one of the hallmarks of an effective host defense mechanism. The main pathway through which this happens is by the innate immune response. Neutrophils, which play an important part in innate immune defense, migrate into lungs through the modulation actions of chemokines to execute a variety of pro-inflammatory functions. Despite the importance of chemokines in host immunity, little has been discussed on their roles in host immunity. A holistic understanding of neutrophil recruitment, pattern recognition pathways, the roles of chemokines and the pathophysiological roles of neutrophils in host immunity may allow for new approaches in the treatment of infectious and inflammatory disease of the lung. Herein, this review aims at highlighting some of the developments in lung neutrophil-immunity by focusing on the functions and roles of CXC/CC chemokines and pattern recognition receptors in neutrophil immunity during pulmonary inflammations. The pathophysiological roles of neutrophils in COVID-19 and thromboembolism have also been summarized. We finally summarized various neutrophil biomarkers that can be utilized as prognostic molecules in pulmonary inflammations and discussed various neutrophil-targeted therapies for neutrophil-driven pulmonary inflammatory diseases.

Azilsartan attenuates lipopolysaccharide-induced acute lung injury via the Nrf2/HO-1 signaling pathway

Acute lung injury (ALI) is a severe complication of sepsis and hemorrhagic shock with high morbidity. In the present study, the protective effect of Azilsartan on lipopolysaccharide (LPS)-induced ALI in mice was investigated to explore the potential therapeutic property of Azilsartan for the treatment of ALI. LPS was used to induce an ALI model in mice. Hematoxylin-eosin (HE) staining sections were then evaluated for the pathological state of lung tissues. Bronchoalveolar lavage fluid (BALF) protein concentration, wet/dry weight ratios of lung tissues, and pulmonary myeloperoxidase (MPO) activity were detected to determine the degree of pulmonary injury. The number of total cells, macrophages, and neutrophils in BALF were counted using a hemocytometer to illustrate the inflammatory cell infiltration. The lung function was monitored using a spirometer. The concentrations of interleukin-1β (IL-1β), monocyte chemoattractant protein-1 (MCP-1), and interleukin-8 (IL-8) were determined using enzyme-linked immunosorbent assay (ELISA). Oxidative stress was evaluated by the superoxide dismutase (SOD) activity, glutathione (GSH), and malondialdehyde (MDA) concentrations in the lung tissue. The expressions of nuclear erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were determined using Western blot analysis. Azilsartan therapy alleviated LPS-induced lung tissue damage, increased BALF protein concentration, lung wet to dry weight ratio, MPO activity, and macrophage and neutrophils infiltration. Also, Azilsartan ameliorated the production of inflammatory factors (IL-1β, MCP-1, and IL-8). Azilsartan ameliorated LPS-impaired lung SOD activity, the GSH concentration, and the MDA concentration. Mechanistically, Azilsartan activated the LPS-impaired Nrf2/HO-1 signaling pathway. Azilsartan therapy attenuates LPS-induced ALI via the Nrf2/HO-1 signaling pathway.

Long non-coding RNA HOTAIR knockdown alleviates lipopolysaccharide-induced acute respiratory distress syndrome and the associated inflammatory response by modulating the microRNA-30a-5p/PDE7A axis

Acute respiratory distress syndrome (ARDS) is a severe pulmonary disease, which can be modulated by certain long non-coding (lnc)RNAs. The present study aimed to investigate the regulatory mechanism of lncRNA HOTAIR in ARDS and the inflammatory response induced by lipopolysaccharide (LPS). The mRNA expression levels of HOTAIR, microRNA (miR)-30a-5p and PDE7A were determined using reverse transcription-quantitative PCR, while a MTT assay was used to assess the viability of the MLE-12 cells and ELISA was used to determine the concentration of different inflammatory factors [tumor necrosis factor (TNF)-α, IL-1β and IL-6]. The interactions between miR-30a-5p and HOTAIR/PDE7A were predicted using TargetScan and StarBase databases and verified using a dual-luciferase reporter assay. The protein expression levels of PDE7A were determined using western blot analysis. Mouse models of LPS-induced ARDS were established to investigate the suppressive effect of HOTAIR knockdown on ARDS in vivo. lncRNA HOTAIR was increased in LPS-treated MLE-12 cells and in a ARDS mouse model. HOTAIR knockdown decreased the concentration of TNF-α, IL-1β and IL-6, and increased cell viability in vitro. miR-30a-5p upregulation decreased TNF-α, IL-1β and IL-6 concentrations, and increased cell viability in vitro. HOTAIR targeted miR-30a-5p and miR-30a-5p targeted PDE7A. miR-30a-5p downregulation and PDE7A upregulation reversed the suppressive effect of HOTAIR knockdown on the concentrations of TNF-α, IL-1β and IL-6, and the positive effect of HOTAIR knockdown on cell viability in vitro. HOTAIR knockdown also attenuated ARDS and the inflammatory response induced by LPS in vivo. The suppression of HOTAIR alleviated ARDS and the inflammatory response induced by LPS by modulating the miR-30a-5p/PDE7A axis. These results provide a potential therapeutic strategy for ARDS.

Potential therapeutics in pediatric acute respiratory distress syndrome: what does the immune system have to offer? A narrative review

Since first described, acute respiratory distress syndrome (ARDS) has been understood to be an inflammatory disease with a dysregulated hyperinflammatory response. While fewer investigations have studied these phenomena in pediatric ARDS (PARDS), similar pathways are believed to be involved. Significant attention has been paid to the innate immune system, particularly neutrophils and neutrophil-related signaling, more recent studies have provided additional nuance regarding the role of upstream damage-associated molecular patterns (DAMPs) and subsequent neutrophil-mediated inflammation, lung permeability, and alveolar epithelial damage. For example, neutrophil extracellular traps (NETs) and inflammasome signaling have been identified as critical mediators existing at the junction of DAMPs and downstream inflammation. We demonstrate how the conclusions obtained from pre-clinical studies of lung injury are highly dependent upon the model chosen, and how this can lead us astray when developing therapies. More recently the adaptive immune system, specifically select T cell subpopulations, have also been implicated in ARDS. This raises the possibility of antigen-specific immunomodulation as a potential therapeutic avenue in ARDS. Finally, we briefly review randomized controlled trials attempting to manipulate the immune dysregulation in ARDS, including pleiotropic immunomodulators like corticosteroids and interferon-β, and what these studies can teach us about the design of novel therapeutics and the design of future trials.

Nanotherapeutics in the treatment of acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a form of oxygenation failure primarily characterized by rapid inflammation resulting from a direct pulmonary or indirect systemic insult. ARDS has been a major cause of death in the recent COVID-19 outbreak wherein asymptomatic respiratory tract infection progresses to ARDS from pneumonia have emphasized the need for a reliable therapy for the disease. The disease has a high mortality rate of approximately 30-50%. Despite the high mortality rate, a dearth of effective pharmacotherapy exists that demands extensive research in this area. The complex ARDS pathophysiology which remains to be understood completely and the multifactorial etiology of the disease has led to the poor diagnosis, impeded drug-delivery to the deeper pulmonary tissues, and delayed treatment of the ARDS patients. Besides, critically ill patients are unable to tolerate the off-target side effects. The vast domain of nanobiotechnology presents several drug delivery systems offering numerous benefits such as targeted delivery, prolonged drug release, and uniform drug-distribution. The present review presents a brief insight into the ARDS pathophysiology and summarizes conventional pharmacotherapies available to date. Furthermore, the review provides an updated report of major developments in the nanomedicinal approaches for the treatment of ARDS. We also discuss different nano-formulations studied extensively in the ARDS preclinical models along with underlining the advantages as well as challenges that need to be addressed in the future.

Heteromeric TRP Channels in Lung Inflammation

Activation of Transient Receptor Potential (TRP) channels can disrupt endothelial barrier function, as their mediated Ca²⁺ influx activates the CaM (calmodulin)/MLCK (myosin light chain kinase)-signaling pathway, and thereby rearranges the cytoskeleton, increases endothelial permeability and thus can facilitate activation of inflammatory cells and formation of pulmonary edema. Interestingly, TRP channel subunits can build heterotetramers, whereas heteromeric TRPC1/4, TRPC3/6 and TRPV1/4 are expressed in the lung endothelium and could be targeted as a protective strategy to reduce endothelial permeability in pulmonary inflammation. An update on TRP heteromers and their role in lung inflammation will be provided with this review.

How could perfluorocarbon affect cytokine storm and angiogenesis in coronavirus disease 2019 (COVID-19): role of hypoxia-inducible factor 1α

Coronavirus disease 2019 (COVID-19) pandemic is still a world-class challenge. Inflammation, especially its severe form with excess release of pro-inflammatory cytokines (cytokine storm) which is a life-threatening condition, is among the most important suspects involved in COVID-19 pathogenesis. It has been shown that cytokine storm could cause notable morbidities such as acute respiratory distress syndrome (ARDS) which leads to hypoxia which is significantly associated with mortality of patients with COVID-19. Hypoxia-inducible factor 1α (HIF-1α) which activates following ARDS-induced hypoxia plays a crucial role in pathogenesis of cytokine storm. The expression of tumor necrosis factor α (TNF-α), interleukin 1 β (IL-1β), and IL-6 which are key elements of cytokine storm are by nuclear factor κβ (NFκB). Interestingly, during the hypoxia, HIF-1α activates NFκB to induce expression of pro-angiogenic and pro-inflammatory factors. These released factors starts a autocrine/paracrine loop and causes deterioration of their etiological pathways of expression: cytokine storm and ARDS. To sum up, it seems HIF-1α is an important target to hit to ameliorate the mentioned pathways. Herein, we suggest perfluorocarbons (PFCs) which are among the organofluorine compounds as a possible co-treatment to reduce hypoxemia and then hypoxia. These substances are known for their high gas solving potential that make them able to be used as a synthetic artificial blood product. Due to the potential of PFCs to affect the fountain of important physiopathological pathway such as inflammation a hypoxia through affecting NFκB, they could be considered as multi-target co-treatment for ARD individuals with COVID-19. It is highly suggested to evaluate this hypothesis in following researches.

Surface Proteins of SARS-CoV-2 Drive Airway Epithelial Cells to Induce IFN-Dependent Inflammation

SARS-CoV-2, the virus that has caused the COVID-19 pandemic, robustly activates the host immune system in critically ill patients. Understanding how the virus engages the immune system will facilitate the development of needed therapeutic strategies. In this study, we demonstrate both in vitro and in vivo that the SARS-CoV-2 surface proteins spike (S) and envelope (E) activate the key immune signaling IFN pathway in both human and mouse immune and epithelial cells independent of viral infection and replication. These proteins induce reactive oxidative species generation and increases in human- and murine-specific, IFN-responsive cytokines and chemokines, similar to their upregulation in critically ill COVID-19 patients. Induction of IFN signaling is dependent on canonical but discrepant inflammatory signaling mediators, as the activation induced by S is dependent on IRF3, TBK1, and MyD88, whereas that of E is largely MyD88 independent. Furthermore, these viral surface proteins, specifically E, induced peribronchial inflammation and pulmonary vasculitis in a mouse model. Finally, we show that the organized inflammatory infiltrates are dependent on type I IFN signaling, specifically in lung epithelial cells. These findings underscore the role of SARS-CoV-2 surface proteins, particularly the understudied E protein, in driving cell specific inflammation and their potential for therapeutic intervention.