Mast cells and their activation in lung disease

Transfusion-Related Acute Lung Injury: from Mechanistic Insights to Therapeutic Strategies

Transfusion-related acute lung injury (TRALI) is a potentially lethal complication of blood transfusions, characterized by the rapid onset of pulmonary edema and hypoxemia within six hours post-transfusion. As one of the primary causes of transfusion-related mortality, TRALI carries a significant mortality rate of 6-12%. However, effective treatment strategies for TRALI are currently lacking, underscoring the urgent need for a comprehensive and in-depth understanding of its pathogenesis. This comprehensive review provides an updated and detailed analysis of the current landscape of TRALI, including its clinical presentation, pathogenetic hypotheses, animal models, cellular mechanisms, signaling pathways, and potential therapeutic targets. By highlighting the critical roles of these pathways and therapies, this review offers valuable insights to inform the development of preventative and therapeutic strategies and to guide future research efforts aimed at addressing this life-threatening condition.

Cromolyn sodium reduces LPS-induced pulmonary fibrosis by inhibiting the EMT process enhanced by MC-derived IL-13

BACKGROUND

Sepsis is a systemic inflammatory response caused by infection. When this inflammatory response spreads to the lungs, it can lead to acute lung injury (ALI) or more severe acute respiratory distress syndrome (ARDS). Pulmonary fibrosis is a potential complication of these conditions, and the early occurrence of pulmonary fibrosis is associated with a higher mortality rate. The underlying mechanism of ARDS-related pulmonary fibrosis remains unclear.

METHODS

To evaluate the role of mast cell in sepsis-induced pulmonary fibrosis and elucidate its molecular mechanism. We investigated the level of mast cell and epithelial-mesenchymal transition(EMT) in LPS-induced mouse model and cellular model. We also explored the influence of cromolyn sodium and mast cell knockout on pulmonary fibrosis. Additionally, we explored the effect of MC-derived IL-13 on the EMT and illustrated the relationship between mast cell and pulmonary fibrosis.

RESULTS

Mast cell was up-regulated in the lung tissues of the pulmonary fibrotic mouse model compared to control groups. Cromolyn sodium and mast cell knockout decreased the expression of EMT-related protein and IL-13, alleviated the symptoms of pulmonary fibrosis in vivo and in vitro. The PI3K/AKT/mTOR signaling was activated in fibrotic lung tissue, whereas Cromolyn sodium and mast cell knockout inhibited this pathway.

CONCLUSION

The expression level of mast cell is increased in fibrotic lungs. Cromolyn sodium intervention and mast cell knockout alleviate the symptoms of pulmonary fibrosis probably via the PI3K/AKT/mTOR signaling pathway. Therefore, mast cell inhibition is a potential therapeutic target for sepsis-induced pulmonary fibrosis.

Targeting mast cell activation alleviates anti-MHC I antibody and LPS-induced TRALI in mice by pharmacologically blocking the TLR3 and MAPK pathway

Transfusion-related lung injury (TRALI) poses a significant risk following blood transfusion and remains the primary cause of transfusion-related morbidity and mortality, primarily driven by the activation of immune cells through anti-major histocompatibility complex class I (anti-MHC I) antibody. However, it remains to be defined how immune microenvironmental cue contributes to TRALI. Here, we uncover that activated mast cells within the immune microenvironment promote lung inflammation and injury in antibody-mediated TRALI, both in vitro and in vivo. This was demonstrated by co-culturing lipopolysaccharide (LPS)-pretreated mast cell line with anti-MHC I antibody and establishing a "two-hit" TRALI mouse model through intratracheal injection of LPS followed by tail-vein injection of anti-MHC I antibody. Importantly, mast cell-deficient KitW-sh/W-sh mice exhibited markedly reduced lung inflammation and injury responses in antibody-mediated TRALI compared with wild-type mice. Mechanistically, activation of toll-like receptor 3 (TLR3)/mitogen-activated protein kinase (MAPK) signaling pathway in mast cells contributes to the enhanced production of proinflammatory factors. These excessive proinflammatory factors produced by activated mast cells contribute to lung inflammation and injury in antibody-mediated TRALI. Pharmacologically targeting the TLR3/MAPK pathway to inhibit mast cell activation normalizes the proinflammatory microenvironment and alleviates lung inflammation and injury in the preclinical TRALI mouse model. Overall, we find that activation of mast cells via the TLR3/MAPK pathway contributes to lung inflammation and injury in antibody-mediated TRALI, providing novel insights into its underlying mechanisms. Furthermore, targeting activated mast cells and the associated pathway offers potential therapeutic strategies for antibody-mediated TRALI.

Reduced microRNA-744 expression in mast cell-derived exosomes triggers epithelial cell ferroptosis in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a critical disorder characterized by immune-related damage to epithelial cells; however, its underlying mechanism remains elusive. This study investigated the effects of alterations in microRNA (miRNA) expression in mast cell-derived exosomes on human bronchial epithelial (HBE) cells and ARDS development in cellular and mouse models challenged with lipopolysaccharide. Lipopolysaccharide-treated mast cell-derived exosomes reduced glutathione peroxidase 4 (GPX4) expression and increased long-chain acyl-CoA synthetase 4 (ACSL4), 15-lipoxygenase (ALOX15), and inflammatory mediator levels in HBE cells. miRNA sequencing revealed a reduction in mast cell-derived exosomal miR-744 levels, which was associated with the regulation of ACSL4, ALOX15, and GPX4 expression. This downregulation of exosomal miR-744 expression reduced miR-744 levels and promoted ferroptosis in HBE cells, whereas the experimental upregulation of miR-744 reversed these adverse effects. Down-regulation of miR-744 induced the expression of markers for ferroptosis and inflammation in HBE cells and promoted pulmonary ferroptosis, inflammation, and injury in LPS-stimulated mice. In vivo, treatment with ACSL4, ALOX15, and GPX4 inhibitors mitigated these effects, and experimental miR-744 expression rescued the lipopolysaccharide-induced changes in HBE cells and mouse lungs. Notably, miR-744 levels were reduced in the plasma and exosomes of patients with ARDS. We concluded that decreased mast cell-derived exosomal miR-744 levels trigger epithelial cell ferroptosis, promoting lung inflammation and damage in ARDS. This study provides new mechanistic insights into the development and sustained pulmonary damage associated with ARDS and highlights potential therapeutic strategies.

G0 arrest gene patterns to predict the prognosis and drug sensitivity of patients with lung adenocarcinoma

G0 arrest (G0A) is widely recognized as a crucial factor contributing to tumor relapse. The role of genes related to G0A in lung adenocarcinoma (LUAD) was unclear. This study aimed to develop a gene signature based on for LUAD patients and investigate its relationship with prognosis, tumor immune microenvironment, and therapeutic response in LUAD. We use the TCGA-LUAD database as the discovery cohort, focusing specifically on genes associated with the G0A pathway. We used various statistical methods, including Cox and lasso regression, to develop the model. We validated the model using bulk transcriptome and single-cell transcriptome datasets (GSE50081, GSE72094, GSE127465, GSE131907 and EMTAB6149). We used GSEA enrichment and the CIBERSORT algorithm to gain insight into the annotation of the signaling pathway and the characterization of the tumor microenvironment. We evaluated the response to immunotherapy, chemotherapy, and targeted therapy in these patients. The expression of six genes was validated in cell lines by quantitative real-time PCR (qRT-PCR). Our study successfully established a six-gene signature (CHCHD4, DUT, LARP1, PTTG1IP, RBM14, and WBP11) that demonstrated significant predictive power for overall survival in patients with LUAD. It demonstrated independent prognostic value in LUAD. To enhance clinical applicability, we developed a nomogram based on this gene signature, which showed high reliability in predicting patient outcomes. Furthermore, we observed a significant association between G0A-related risk and tumor microenvironment as well as drug susceptibility, highlighting the potential of the gene signature to guide personalized treatment strategies. The expression of six genes were significantly upregulated in the LUAD cell lines. This signature holds the potential to contribute to improved prognostic prediction and new personalized therapies specifically for LUAD patients.

Immune cells crosstalk Pathways, and metabolic alterations in Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) presents a challenging progression characterized by lung tissue scarring and abnormal extracellular matrix deposition. This review examines the influence of immune responses, emphasizing their complex role in initiating and perpetuating fibrosis. It highlights how metabolic pathways modulate immune cell function during IPF. Immune cell modulation holds promise in managing pulmonary fibrosis (PF). Inhibiting neutrophil recruitment and monitoring mast cell levels offer insights into PF progression. Low-dose IL-2 therapy and regulation of fibroblast recruitment present potential therapeutic avenues, while the role of innate lymphoid cells (ILC2s) in allergic lung inflammation sheds light on disease mechanisms. The review focuses on metabolic reprogramming's role in shaping immune cell function during IPF progression. While some immune cells use glycolysis for pro-inflammatory responses, others favor fatty acid oxidation for regulatory functions. Targeting specialized pro-resolving lipid mediators (SPMs) presents significant potential for managing fibrotic disorders. Additionally, it highlights the pivotal role of amino acid metabolism in synthesizing serine and glycine as crucial regulators of collagen production and exploring the interconnectedness of lipid metabolism, mitochondrial dysfunction, and adipokines in driving fibrotic processes. Moreover, the review discusses the impact of metabolic disorders such as obesity and diabetes on lung fibrosis. Advocating for a holistic approach, it emphasizes the importance of considering this interplay between immune cell function and metabolic pathways in developing effective and personalized treatments for IPF.

Role of mechanoregulation in mast cell-mediated immune inflammation of the smooth muscle in the pathophysiology of esophageal motility disorders

Major esophageal disorders involve obstructive transport of bolus to the stomach, causing symptoms of dysphagia and impaired clearing of the refluxed gastric contents. These may occur due to mechanical constriction of the esophageal lumen or loss of relaxation associated with deglutitive inhibition, as in achalasia-like disorders. Recently, immune inflammation has been identified as an important cause of esophageal strictures and the loss of inhibitory neurotransmission. These disorders are also associated with smooth muscle hypertrophy and hypercontractility, whose cause is unknown. This review investigated immune inflammation in the causation of smooth muscle changes in obstructive esophageal bolus transport. Findings suggest that smooth muscle hypertrophy occurs above the obstruction and is due to mechanical stress on the smooth muscles. The mechanostressed smooth muscles release cytokines and other molecules that may recruit and microlocalize mast cells to smooth muscle bundles, so that their products may have a close bidirectional effect on each other. Acting in a paracrine fashion, the inflammatory cytokines induce genetic and epigenetic changes in the smooth muscles, leading to smooth muscle hypercontractility, hypertrophy, and impaired relaxation. These changes may worsen difficulty in the esophageal transport. Immune processes differ in the first phase of obstructive bolus transport, and the second phase of muscle hypertrophy and hypercontractility. Moreover, changes in the type of mechanical stress may change immune response and effect on smooth muscles. Understanding immune signaling in causes of obstructive bolus transport, type of mechanical stress, and associated smooth muscle changes may help pathophysiology-based prevention and targeted treatment of esophageal motility disorders.NEW & NOTEWORTHY Esophageal disorders such as esophageal stricture or achalasia, and diffuse esophageal spasm are associated with smooth muscle hypertrophy and hypercontractility, above the obstruction, yet the cause of such changes is unknown. This review suggests that smooth muscle obstructive disorders may cause mechanical stress on smooth muscle, which then secretes chemicals that recruit, microlocalize, and activate mast cells to initiate immune inflammation, producing functional and structural changes in smooth muscles. Understanding the immune signaling in these changes may help pathophysiology-based prevention and targeted treatment of esophageal motility disorders.

Ayurveda management of a patient having bronchial asthma and hemorrhoids- A case report

Ayurveda is a holistic science that treats root cause of diseases. One disease can become a causative factor for another disease. This concept is fundamentally described as Nidanarthakar Vyadhi in Ayurveda. In the same way, treating causative diseases is helpful in managing another diseases. However, many published clinical trials on Ayurveda management of Bronchial asthma and Hemorrhoids exist. There is a dearth of published case reports or clinical trials showing an association between Arsha (hemorrhoids) and Shwasa (bronchial asthma). This case report gives important viewpoints about the role of hemorrhoids and its treatment in pathogenesis and treatment of bronchial asthma. This case report of a 38-year-old female patient known case of bronchial asthma who came to the OPD of Kayachikitsa Government Ayurved College and Hospital, Nagpur with complaints of cough with sputum, breathlessness, chest pain (on/off) for three years. The severity of these symptoms increased for three months. The patient was treated with conventional Shwasghna Chikitsa (treatment of bronchial asthma) for five days, but the response was unsatisfactory. After five days of Shwasghna treatment, the patient gave a history of hemorrhoids. Considering Nidanarthakar Roga (one disease can cause of another disease), treatment was planned. The treatment principle is the treatment of causative disease (Arsha). Hence, Arshoghna treatment was added. Significant increases in peak expiratory flow rate (PEFR), Sustained minimal inspiration (SMI), and Modified Medical Research Council Dyspnoea scale (mMRC) were observed. The respiratory rate was also reduced from 28/min to 18/min. Improvement in the subjective and objective parameters of the patient was observed. The inclusion of Arsha treatment can be helpful in the management of Tamakshwas (Bronchial Asthma). The need for further research in this direction is warranted.

Meta-analysis of single-cell RNA-sequencing data for depicting the transcriptomic landscape of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a respiratory disease characterized by airflow limitation and chronic inflammation of the lungs that is a leading cause of death worldwide. Since the complete pathological mechanisms at the single-cell level are not fully understood yet, an integrative approach to characterizing the single-cell-resolution landscape of COPD is required. To identify the cell types and mechanisms associated with the development of COPD, we conducted a meta-analysis using three single-cell RNA-sequencing datasets of COPD. Among the 154,011 cells from 16 COPD patients and 18 healthy subjects, 17 distinct cell types were observed. Of the 17 cell types, monocytes, mast cells, and alveolar type 2 cells (AT2 cells) were found to be etiologically implicated in COPD based on genetic and transcriptomic features. The most transcriptomically diversified states of the three etiological cell types showed significant enrichment in immune/inflammatory responses (monocytes and mast cells) and/or mitochondrial dysfunction (monocytes and AT2 cells). We then identified three chemical candidates that may potentially induce COPD by modulating gene expression patterns in the three etiological cell types. Overall, our study suggests the single-cell level mechanisms underlying the pathogenesis of COPD and may provide information on toxic compounds that could be potential risk factors for COPD.

Airway inflammatory changes in the lungs of patients with asthma-COPD overlap (ACO): a bronchoscopy endobronchial biopsy study

BACKGROUND

Although asthma and chronic obstructive pulmonary disease (COPD) are two distinct chronic airway inflammatory diseases, they often co-exist in a patient and the condition is referred to as asthma-COPD overlap (ACO). Lack of evidence regarding the inflammatory cells in ACO airways has led to their poor prognosis and treatment. The objective of this endobronchial biopsy (EBB) study was to enumerate inflammatory cellular changes in the airway wall of ACO compared with asthma, COPD current smokers (CS) and ex-smokers (ES), normal lung function smokers (NLFS), and non-smoker controls (HC).

METHODS

EBB tissues from 74 patients were immunohistochemically stained for macrophages, mast cells, eosinophils, neutrophils, CD8+ T-cells and CD4+ T-cells. The microscopic images of stained tissues were evaluated in the epithelium, reticular basement membrane (RBM) cells/mm RBM length, and lamina propria (LP) cells/mm2 up to a depth of 120 µM using the image analysis software Image-Pro Plus 7.0. The observer was blinded to the images and disease diagnosis. Statistical analysis was performed using GraphPad Prism v9.

RESULTS

The tissue macrophages in ACO were substantially higher in the epithelium and RBM than in HC (P < 0.001 for both), COPD-ES (P < 0.001 for both), and -CS (P < 0.05 and < 0.0001, respectively). The ACO LP macrophages were significantly higher in number than COPD-CS (P < 0.05). The mast cell numbers in ACO were lower than in NLFS (P < 0.05) in the epithelium, lower than COPD (P < 0.05) and NLFS (P < 0.001) in RBM; and lower than  HC (P < 0.05) in LP. We noted lower eosinophils in ACO LP than HC (P < 0.05) and the lowest neutrophils in both ACO and asthma. Furthermore, CD8+ T-cell numbers increased in the ACO RBM than HC (P < 0.05), COPD-ES (P < 0.05), and NLFS (P < 0.01); however, they were similar in number in epithelium and LP across groups. CD4+ T-cells remained lower in number across all regions and groups.

CONCLUSION

These results suggest that the ACO airway tissue inflammatory cellular profile differed from the contributing diseases of asthma and COPD with a predominance of macrophages.

A novel defined risk signature of cuproptosis-related long non-coding RNA for predicting prognosis, immune infiltration, and immunotherapy response in lung adenocarcinoma

Background: Cuproptosis is a newly discovered non-apoptotic form of cell death that may be related to the development of tumors. Nonetheless, the potential role of cuproptosis-related lncRNAs in tumor immunity formation and patient-tailored treatment optimization of lung adenocarcinoma (LUAD) is still unclear. Methods: RNA sequencing and survival data of LUAD patients were downloaded from The Cancer Genome Atlas (TCGA) database for model training. The patients with LUAD in GSE29013, GSE30219, GSE31210, GSE37745, and GSE50081 were used for validation. The proofed cuproptosis-related genes were extracted from the previous studies. The Pearson correlation was applied to select cuproptosis-related lncRNAs. We chose differentially expressed cuproptosis-related lncRNAs in the tumor and normal tissues and allowed them to go to a Cox regression and a LASSO regression for a lncRNA signature that predicts the LUAD prognosis. Kaplan-Meier estimator, Cox model, ROC, tAUC, PCA, nomogram predictor, decision curve analysis, and real-time PCR were further deployed to confirm the model's accuracy. We examined this model's link to other regulated cell death forms. Applying TMB, immune-related signatures, and TIDE demonstrated the immunotherapeutic capabilities of signatures. We evaluated the relationship of our signature to anticancer drug sensitivity. GSEA, immune infiltration analysis, and function experiments further investigated the functional mechanisms of the signature and the role of immune cells in the prognostic power of the signature. Results: An eight-lncRNA signature (TSPOAP1-AS1, AC107464.3, AC006449.7, LINC00324, COLCA1, HAGLR, MIR4435-2HG, and NKILA) was built and demonstrated owning prognostic power by applied to the validation cohort. Each signature gene was confirmed differentially expressed in the real world by real-time PCR. The eight-lncRNA signature correlated with 2321/3681 (63.05%) apoptosis-related genes, 11/20 (55.00%) necroptosis-related genes, 34/50 (68.00%) pyroptosis-related genes, and 222/380 (58.42%) ferroptosis-related genes. Immunotherapy analysis suggested that our signature may have utility in predicting immunotherapy efficacy in patients with LUAD. Mast cells were identified as key players that support the predicting capacity of the eight-lncRNA signature through the immune infiltrating analysis. Conclusion: In this study, an eight-lncRNA signature linked to cuproptosis was identified, which may improve LUAD management strategies. This signature may possess the ability to predict the effect of LUAD immunotherapy. In addition, infiltrating mast cells may affect the signature's prognostic power.

Efficacy and safety of inhaled heparin in asthmatic and chronic obstructive pulmonary disease patients: a systematic review and a meta-analysis

Asthma and chronic obstructive pulmonary disease (COPD) are prevalent chronic respiratory disorders that cause significant morbidity and mortality. Some studies evaluated the use of inhaled unfractionated heparin (UFH) in the treatment of asthma and COPD. We aimed to synthesize the available evidence for the efficacy and safety of inhaled heparin in improving lung functions among asthmatic and COPD patients. A comprehensive search was performed using Pubmed, Embase, EBSCO, Scopus, Web of Science, Cochrane CENTRAL, WHO Clinical trials, clinicaltrials.gov, Iranian Clinical trials, Google Scholar, Research Gate, ProQuest Thesis, OVID, and medRxiv databases. Two independent reviewers included all pertinent articles according to PRISMA guidelines, and extract data independently. The two reviewers checked the quality of studies using the ROB2 tool. To determine the pooled effect estimate of the efficacy and safety of inhaled heparin, a meta-analysis was carried out using the R programming language. Publication bias was evaluated using Egger's regression test. The heterogeneity was explained using a meta-regression, and the quality of evidence was assessed by the GRADE approach. Twenty-six studies with a total of 581 patients were included in the qualitative analysis and 16 in the meta-analysis. The primary outcome was treatment success (improvement of lung function) that was measured by standardized mean differences (SMD) of the forced expiratory volume per second (FEV1) either per ml or percentage. Heparin has a large effect on both FEV1% and FEV1 ml when compared to the control group (SMD 2.7, 95% CI 1.00; 4.39; GRADE high, SMD 2.12, 95% CI - 1.49; 5.72: GRADE moderate, respectively). Secondary outcomes are other lung functions improving parameters such as PC20 (SMD 0.91, 95% CI - 0.15; 1.96). Meta-regression and subgroup analysis show that heparin type, dose, year of publication, study design, and quality of studies had a substantial effect. Regarding safety, inhaled heparin showed a good coagulation profile and mild tolerable side effects. Inhaled heparin showed improvement in lung functions either alone or when added to standard care. More large parallel RCTs are needed including COPD patients, children, and other types, and stages of asthmatic patients.

Melatonin alleviates lung injury in H1N1-infected mice by mast cell inactivation and cytokine storm suppression

Influenza A virus (IAV) H1N1 infection is a constant threat to human health and it remains so due to the lack of an effective treatment. Since melatonin is a potent antioxidant and anti-inflammatory molecule with anti-viral action, in the present study we used melatonin to protect against H1N1 infection under in vitro and in vivo conditions. The death rate of the H1N1-infected mice was negatively associated with the nose and lung tissue local melatonin levels but not with serum melatonin concentrations. The H1N1-infected AANAT-/- melatonin-deficient mice had a significantly higher death rate than that of the WT mice and melatonin administration significantly reduced the death rate. All evidence confirmed the protective effects of melatonin against H1N1 infection. Further study identified that the mast cells were the primary targets of melatonin action, i.e., melatonin suppresses the mast cell activation caused by H1N1 infection. The molecular mechanisms involved melatonin down-regulation of gene expression for the HIF-1 pathway and inhibition of proinflammatory cytokine release from mast cells; this resulted in a reduction in the migration and activation of the macrophages and neutrophils in the lung tissue. This pathway was mediated by melatonin receptor 2 (MT2) since the MT2 specific antagonist 4P-PDOT significantly blocked the effects of melatonin on mast cell activation. Via targeting mast cells, melatonin suppressed apoptosis of alveolar epithelial cells and the lung injury caused by H1N1 infection. The findings provide a novel mechanism to protect against the H1N1-induced pulmonary injury, which may better facilitate the progress of new strategies to fight H1N1 infection or other IAV viral infections.

A more novel and powerful prognostic gene signature of lung adenocarcinoma determined from the immune cell infiltration landscape

Background

Lung adenocarcinoma (LUAD) is the leading histological subtype of lung cancer worldwide, causing high mortality each year. The tumor immune cell infiltration (ICI) is closely associated with clinical outcome with LUAD patients. The present study was designed to construct a gene signature based on the ICI of LUAD to predict prognosis.

Methods

Downloaded the raw data of three cohorts of the TCGA-LUAD, GSE72094, and GSE68465 and treat them as training cohort, validation cohort one, and validation cohort two for this research. Unsupervised clustering detailed grouped LUAD cases of the training cohort based on the ICI profile. The univariate Cox regression and Kaplan-Meier was adopted to identify potential prognostic genes from the differentially expressed genes recognized from the ICI clusters. A risk score-based prognostic signature was subsequently developed using LASSO-penalized Cox regression analysis. The Kaplan-Meier analysis, Cox analysis, ROC, IAUC, and IBS were constructed to assess the ability to predict the prognosis and effects of clinical variables in another two independent validation cohorts. More innovatively, we searched similar papers in the most recent year and made comprehensive comparisons with ours. GSEA was used to discover the related signaling pathway. The immune relevant signature correlation identification and immune infiltrating analysis were used to evaluate the potential role of the signature for immunotherapy and recognize the critical immune cell that can influence the signature's prognosis capability.

Results

A signature composed of thirteen gene including ABCC2, CCR2, CERS4, CMAHP, DENND1C, ECT2, FKBP4, GJB3, GNG7, KRT6A, PCDH7, PLK1, and VEGFC, was identified as significantly associated with the prognosis in LUAD patients. The thirteen-gene signature exhibited independence in evaluating the prognosis of LUAD patients in our training and validation cohorts. Compared to our predecessors, our model has an advantage in predictive power. Nine well know immunotherapy targets, including TBX2, TNF, CTLA4, HAVCR2, GZMB, CD8A, PRF1, GZMA, and PDCD1 were recognized correlating with our signature. The mast cells were found to play vital parts in backing on the thirteen-gene signature's outcome predictive capacity.

Conclusions

Collectively, the current study indicated a robust thirteen-gene signature that can accurately predict LUAD prognosis, which is superior to our predecessors in predictive ability. The immune relevant signatures, TBX2, TNF, CTLA4, HAVCR2, GZMB, CD8A, PRF1, GZMA, PDCD1, and mast cells infiltrating were found closely correlate with the thirteen-gene signature's power.

Screening and identification of tissue-infiltrating immune cells and genes for patients with emphysema phenotype of COPD

Objective

To study the tissue-infiltrating immune cells of the emphysema phenotype of chronic obstructive pulmonary disease (COPD) and find the molecular mechanism related to the development of emphysema to offer potential targets for more precise treatment of patients with COPD.

Methods

Combined analyses of COPD emphysema phenotype lung tissue-related datasets, GSE47460 and GSE1122, were performed. CIBERSORT was used to assess the distribution of tissue-infiltrating immune cells. Weighted gene co-expression network analysis (WGCNA) was used to select immune key genes closely related to clinical features. Rt-qPCR experiments were used for the validation of key genes. Emphysema risk prediction models were constructed by logistic regression analysis and a nomogram was developed.

Results

In this study, three immune cells significantly associated with clinical features of emphysema (FEV1 post-bronchodilator % predicted, GOLD Stage, and DLCO) were found. The proportion of neutrophils (p=0.025) infiltrating in the emphysema phenotype was significantly increased compared with the non-emphysema phenotype, while the proportions of M2 macrophages (p=0.004) and resting mast cells (p=0.01) were significantly decreased. Five immune-related differentially expressed genes (DEGs) were found. WGCNA and clinical lung tissue validation of patients with emphysema phenotype were performed to further screen immune-related genes closely related to clinical features. A key gene (SERPINA3) was selected and included in the emphysema risk prediction model. Compared with the traditional clinical prediction model (AUC=0.923), the combined prediction model, including SERPINA3 and resting mast cells (AUC=0.941), had better discrimination power and higher net benefit.

Conclusion

This study comprehensively analyzed the tissue-infiltrating immune cells significantly associated with emphysema phenotype, including M2 macrophages, neutrophils, and resting mast cells, and identified SERPINA3 as a key immune-related gene.

Aerosol-Administered Adelmidrol Attenuates Lung Inflammation in a Murine Model of Acute Lung Injury

Acute lung injury (ALI) is a common and devastating clinical disorder with a high mortality rate and no specific therapy. The pathophysiology of ALI is characterized by increased alveolar/capillary permeability, lung inflammation, oxidative stress and structural damage to lung tissues, which can progress to acute respiratory distress syndrome (ARDS). Adelmidrol (ADM), an analogue of palmitoylethanolamide (PEA), is known for its anti-inflammatory and antioxidant functions, which are mainly due to down-modulating mast cells (MCs) and promoting endogenous antioxidant defense. The aim of this study is to evaluate the protective effects of ADM in a mice model of ALI, induced by intratracheal administration of lipopolysaccharide (LPS) at the dose of 5 mg/kg. ADM 2% was administered by aerosol 1 and 6 h after LPS instillation. In this study, we clearly demonstrated that ADM reduced lung damage and airway infiltration induced by LPS instillation. At the same time, ADM counteracted the increase in MC number and the expression of specific markers of MC activation, i.e., chymase and tryptase. Moreover, ADM reduced oxidative stress by upregulating antioxidant enzymes as well as modulating the Nf-kB pathway and the resulting pro-inflammatory cytokine release. These results suggest that ADM could be a potential candidate in the management of ALI.

Prognostic Ability of Enhancer RNAs in Metastasis of Non-Small Cell Lung Cancer

(1) Background: Non-small cell lung cancer (NSCLC) is the most common lung cancer. Enhancer RNA (eRNA) has potential utility in the diagnosis, prognosis and treatment of cancer, but the role of eRNAs in NSCLC metastasis is not clear; (2) Methods: Differentially expressed transcription factors (DETFs), enhancer RNAs (DEEs), and target genes (DETGs) between primary NSCLC and metastatic NSCLC were identified. Prognostic DEEs (PDEEs) were screened by Cox regression analyses and a predicting model for metastatic NSCLC was constructed. We identified DEE interactions with DETFs, DETGs, reverse phase protein arrays (RPPA) protein chips, immunocytes, and pathways to construct a regulation network using Pearson correlation. Finally, the mechanisms and clinical significance were explained using multi-dimensional validation unambiguously; (3) Results: A total of 255 DEEs were identified, and 24 PDEEs were selected into the multivariate Cox regression model (AUC = 0.699). Additionally, the NSCLC metastasis-specific regulation network was constructed, and six key PDEEs were defined (ANXA8L1, CASTOR2, CYP4B1, GTF2H2C, PSMF1 and TNS4); (4) Conclusions: This study focused on the exploration of the prognostic value of eRNAs in the metastasis of NSCLC. Finally, six eRNAs were identified as potential markers for the prediction of metastasis of NSCLC.

Fatty Acid Amide Hydrolase (FAAH) Inhibition Plays a Key Role in Counteracting Acute Lung Injury

Acute lung injury (ALI) is a group of lung illnesses characterized by severe inflammation, with no treatment. The fatty acid amide hydrolase (FAAH) enzyme is an integral membrane protein responsible for the hydrolysis of the main endocannabinoids, such as anandamide (AEA). In pre-clinical pain and inflammation models, increasing the endogenous levels of AEA and other bioactive fatty acid amides (FAAs) via genetic deletion or the pharmacological inhibition of FAAH produces many analgesic benefits in several different experimental models. To date, nobody has investigated the role of FAAH inhibition on an ALI mouse model. Mice were subjected to a carrageenan injection and treated orally 1 h after with the FAAH inhibitor URB878 dissolved in a vehicle consisting of 10% PEG-400, 10% Tween-80 and 80% saline at different doses: The inhibition of FAAH activity was able to counteract not only the CAR-induced histological alteration, but also the cascade of related inflammatory events. URB878 clears the way for further studies based on FAAH inhibition in acute lung pathologies.

The ingenious mast cell: Contemporary insights into mast cell behavior and function

Mast cells are (in)famous for their role in allergic diseases, but the physiological and pathophysiological roles of this ingenious cell are still not fully understood. Mast cells are important for homeostasis and surveillance of the human system, recognizing both endogenous and exogenous agents, which induce release of a variety of mediators acting on both immune and non-immune cells, including nerve cells, fibroblasts, endothelial cells, smooth muscle cells, and epithelial cells. During recent years, clinical and experimental studies on human mast cells, as well as experiments using animal models, have resulted in many discoveries that help decipher the function of mast cells in health and disease. In this review, we focus particularly on new insights into mast cell biology, with a focus on mast cell development, recruitment, heterogeneity, and reactivity. We also highlight the development in our understanding of mast cell-driven diseases and discuss the development of novel strategies to treat such conditions.

Immune Characteristics Analysis and Transcriptional Regulation Prediction Based on Gene Signatures of Chronic Obstructive Pulmonary Disease

Purpose

The variation in inflammation in chronic obstructive pulmonary disease (COPD) between individuals is genetically determined. This study aimed to identify gene signatures of COPD through bioinformatics analysis based on multiple gene sets and explore their immune characteristics and transcriptional regulation mechanisms.

Methods

Data from four microarrays were downloaded from the Gene Expression Omnibus database to screen differentially expressed genes (DEGs) between COPD patients and controls. Weighted gene co-expression network analysis was applied to identify trait-related modules and then select key module-related DEGs. The optimized gene set of signatures was obtained using the least absolute shrinkage and selection operator (LASSO) regression analysis. The CIBERSORT algorithm and Pearson correlation test were used to analyze the relationship between gene signatures and immune cells. Finally, public databases were used to predict the transcription factors (TFs) and upstream miRNAs.

Results

A total of 127 DEGs in COPD were identified from the combined dataset. By considering the intersection of DEGs and genes in two trait-related modules, 83 key module-related DEGs were identified, which were mainly enriched in interleukin-related pathways. Seven-gene signatures, including MTHFD2, KANK3, GFPT2, PHLDA1, HS3ST2, FGG, and RPS4Y1, were further selected using the LASSO algorithm. These gene signatures showed the predictive potential for COPD risks and were significantly correlated with 18 types of immune cells. Finally, nine miRNAs and three TFs were predicted to target MTHFD2, GFPT2, PHLDA1, and FGG.

Conclusion

We proposed the seven-gene-signature to predict COPD risk and explored its potential immune characteristics and regulatory mechanisms.

The Emerging Roles of Tripartite Motif Proteins (TRIMs) in Acute Lung Injury

Acute lung injury (ALI) is an inflammatory disorder of the lung that causes high mortality and lacks any pharmacological intervention. Ubiquitination plays a critical role in the pathogenesis of ALI as it regulates the alveolocapillary barrier and the inflammatory response. Tripartite motif (TRIM) proteins are one of the subfamilies of the RING-type E3 ubiquitin ligases, which contains more than 80 distinct members in humans involved in a broad range of biological processes including antivirus innate immunity, development, and tumorigenesis. Recently, some studies have shown that several members of TRIM family proteins play important regulatory roles in inflammation and ALI. Herein, we integrate emerging evidence regarding the roles of TRIMs in ALI. Articles were selected from the searches of PubMed database that had the terms "acute lung injury," "ubiquitin ligases," "tripartite motif protein," "inflammation," and "ubiquitination" using both MeSH terms and keywords. Better understanding of these mechanisms may ultimately lead to novel therapeutic approaches by targeting TRIMs for ALI treatment.

Bronchoalveolar lavage fluid cell subsets associate with the disease course in Löfgren's and non-Löfgren's sarcoidosis patients

BACKGROUND

Sarcoidosis is a multisystem granulomatous inflammatory disorder, that predominantly involves the lungs. Patients with Löfgren's syndrome (LS) are characterized by acute onset and usually have the HLA-DRB1*03 (DR3^positive) allele and a good prognosis. Non-LS patients are usually DR3^negative and are more likely to develop chronic disease. The study aimed to identify bronchoalveolar lavage fluid (BALF) cells that could associate with disease severity (reduced pulmonary function tests (PFTs), advanced chest radiographs, need for treatment) and/or chronicity (duration >2 years) in newly diagnosed LS and non-LS patients, respectively.

METHODS

We retrospectively included data from 955 non-LS patients, 477 LS patients, and 295 healthy controls (HC) in this study. Intra-group comparison of patients with resolving versus chronic disease was performed in LS and non-LS, respectively. Non-LS patients were divided into two subgroups according to the binary BALF cell concentrations for intra-group comparison (i.e. higher or lower than the 95th percentile of the BALF cells references in healthy individuals).

RESULTS

LS patients with a non-resolving disease course had higher BALF lymphocytes, neutrophils, and eosinophils than LS with a favourable outcome. In non-LS subjects increased BALF of the same cells and in addition also of basophils and mast cells were more likely associated with more severe disease course.

CONCLUSION

Increased BALF cells display prognostic significance in sarcoidosis. Certain BALF profiles should promote the clinician to monitor these patients more closely as they may associate non-resolving disease, in turn, resulting in future irreversible functional impairment.

Mechanisms of Progression and Heterogeneity in Multiple Nodules of Lung Adenocarcinoma

Lung cancer remains the leading cause of cancer-related death worldwide. Lung adenocarcinoma (LUAD) is thought to be caused by precursor lesions of atypical adenoma-like hyperplasia and may have extensive in situ growth before infiltration. To explore the relevant factors in heterogeneity and evolution of lung adenocarcinoma subtypes, the authors perform single-cell RNA sequencing (scRNA-seq) on tumor and normal tissue from five multiple nodules' LUAD patients and conduct a thorough gene expression profiling of cancer cells and cells in their microenvironment at single-cell level. This study gives a deep understanding of heterogeneity and evolution in early glandular neoplasia of the lung. This dataset leads to discovery of the changes in the immune microenvironment during the development of LUAD, and the development process from adenocarcinoma in situ (AIS) to invasive adenocarcinoma (IAC). This work sheds light on the direction of early tumor development and whether they are homologous.

Comprehensive analysis of competitive endogenous RNA associated with immune infiltration in lung adenocarcinoma

To identify the prognostic biomarker of the competitive endogenous RNA (ceRNA) and explore the tumor infiltrating immune cells (TIICs) which might be the potential prognostic factors in lung adenocarcinoma. In addition, we also try to explain the crosstalk between the ceRNA and TIICs to explore the molecular mechanisms involved in lung adenocarcinoma. The transcriptome data of lung adenocarcinoma were obtained from The Cancer Genome Atlas (TCGA) database, and the hypergeometric correlation of the differently expressed miRNA-lncRNA and miRNA-mRNA were analyzed based on the starBase. In addition, the Kaplan–Meier survival and Cox regression model analysis were used to identify the prognostic ceRNA network and TIICs. Correlation analysis was performed to analysis the correlation between the ceRNA network and TIICs. In the differently expressed RNAs between tumor and normal tissue, a total of 190 miRNAs, 224 lncRNAs and 3024 mRNAs were detected, and the constructed ceRNA network contained 5 lncRNAs, 92 mRNAs and 10 miRNAs. Then, six prognostic RNAs (FKBP3, GPI, LOXL2, IL22RA1, GPR37, and has-miR-148a-3p) were viewed as the key members for constructing the prognostic prediction model in the ceRNA network, and three kinds of TIICs (Monocytes, Macrophages M1, activated mast cells) were identified to be significantly related with the prognosis in lung adenocarcinoma. Correlation analysis suggested that the FKBP3 was associated with Monocytes and Macrophages M1, and the GPI was obviously related with Monocytes and Macrophages M1. Besides, the LOXL2 was associated with Monocytes and Activated mast cells, and the IL22RA1 was significantly associated with Monocytes and Macrophages M1, while the GPR37 and Macrophages M1 was closely related. The constructed ceRNA network and identified Monocytes, Macrophages M1 and activated Mast cells are all prognostic factors for lung adenocarcinoma. Moreover, the crosstalk between the ceRNA network and TIICs might be a potential molecular mechanism involved.

Potential of brain mast cells for therapeutic application in the immune response to bacterial and viral infections

A wide range of microorganisms can infect the central nervous system (CNS). The immune response of the CNS provides limited protection against microbes penetrating the blood-brain barrier. This results in a neurological deficit and sometimes leads to high morbidity and mortality rates despite advanced therapies. For the last two decades, different studies have expanded our understanding of the molecular basis of human neuroinfectious diseases, especially concerning the contributions of mast cell interactions with other central nervous system compartments. Brain mast cells are multifunctional cells derived from the bone marrow and reside in the brain. Their proximity to blood vessels, their role as "first responders" their unique receptors systems and their ability to rapidly release pathogen responsive mediators enable them to exert a crucial defensive role in the host-defense system. This review describes key biological and physiological functions of mast cells, concerning their ability to recognize pathogens via various receptor systems, followed by a coordinated and selective mediator release upon specific interactions with pathogenic stimulating factors. The goal of this review is to direct attention to the possibilities for therapeutic applications of mast cells against bacterial and viral related infections. We also focus on opportunities for future research activating mast cells via adjuvants.

Substance P-induced lung inflammation in mice is mast cell dependent

BACKGROUND

Allergic asthma is a common inflammatory lung disease and a major health problem worldwide. Mast cells (MCs) play a key role in the early-stage pathophysiology of allergic asthma. Substance P (SP) functions in neurogenic inflammation by activating MCs, and therefore, it may to participate in the occurrence and development of asthma.

OBJECTIVE

We examined the relationship between SP and lung inflammation, and also whether SP can directly trigger asthma.

METHODS

We measured the number of peripheral blood eosinophils, neutrophils and basophils and evaluated the levels of IgE and SP in blood samples of 86 individuals with allergic asthma. Serum IgE and SP levels were also determined in 29 healthy individuals. C57BL/6 mice were subjected to different doses of SP, and bronchoalveolar lavage fluid (BALF) was collected to count the inflammatory cells. Lung tissues were analysed using histopathological methods to evaluate lung peribronchial inflammation, fibrosis and glycogen deposition. Levels of IgE, interleukin (IL)-1, IL-2, IL-4, IL-5, IL-13, IL-17 and IFN-γ were determined in mouse serum.

RESULTS

Substance P levels were increased in the serum samples of patients with asthma. SP induced mouse lung peribronchial inflammation, fibrosis and glycogen deposition, with high levels of Th2-related cytokines such as IL-4, IL-5 and IL-13 observed in the BALF. Furthermore, low level of total IgE was noted in the serum, and SP had little effect on MC-deficient kit^W-sh/W-sh mice.

CONCLUSIONS & CLINICAL RELEVANCE

Substance P levels increased significantly in serum of asthmatic patients and independently associated with the risk of asthma. Furthermore, SP induced Th2 lung inflammation in mice, which was dependent on MCs.

Exosomes From Packed Red Cells Induce Human Mast Cell Activation and the Production of Multiple Inflammatory Mediators

Most blood transfusion-related adverse reactions involve the immunologic responses of recipients to exogenous blood components. Extracellular vesicles isolated from packed red cells can affect the recipient’s immune system. Mast cells are traditionally known as effector cells for allergic transfusion reactions. However, growing evidence supports the notion that activated mast cells might disturb host innate immunologic responses. Exosomes are a type of extracellular vesicle. To determine the effect of exosomes on mast cells, we enriched exosomes derived from volunteer plasma (EXs-nor) and packed red cells (EXs-RBCs) using ultracentrifugation and incubated them with a human mast cell line (HMC-1). We found that EXs-RBC exposure increased the expression of tryptase-1 and prostaglandin D2, the production of multiple inflammatory mediators, and the levels of Toll-like receptor-3 (TLR-3) and phospho-mitogen-activated protein kinase (MAPK) in HMC-1 cells. MAPK inhibitors (SB203580, PD98059, and SP600125) and a TLR-3/dsRNA complex inhibitor reduced the EXs-RBC-stimulated production of inflammatory mediators in HMC-1 cells, whereas the TLR-3 agonist [poly (A:U)] elevated the production of these mediators. These results indicate that EXs-RBCs activate HMC-1 cells and elicit the production of multiple inflammatory mediators, partly via the TLR-3 and MAPK pathways. Mast cells activated by EXs-RBCs exhibit complex inflammatory properties and might play a potential role in transfusion-related adverse reactions.

Imperatorin ameliorates mast cell-mediated allergic airway inflammation by inhibiting MRGPRX2 and CamKII/ERK signaling pathway

BACKGROUND

Allergic asthma is a common inflammatory lung disease associated with complex pathogenesis. Mast cell (MC) is one of the key drivers of allergic asthma, Mas-related G protein-coupled receptor X2 (MRGPRX2) on the MC could mediate MC activation and trigger a pseudo-allergic reaction. Imperatorin (IMP), the main active compound of Radix Angelicae Dahuricae, has been reported to exert various pharmacological effects. In this study, we focused on the therapeutical mechanism of IMP on MRGPRX2-induced pseudo-allergy and allergic asthma.

METHODS

We examined the effect of IMP on MRGPRX2 related mast cell activation in mouse peritoneal MC (MPMC), Human Laboratory of Allergic Disease 2 MCs (LAD2 cells) and Mrgprx2-expressing HEK293 cells. Molecular docking and Surface plasmon resonance (SPR) were taken to reveal the binding character between IMP and MRPGRX2. MRGPRX2 downstream proteins were also detected by western blotting. IgE-independent responses was evaluated by using passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis (ASA) models. The therapeutic effect of IMP on asthma was evaluated by a lung inflammation mouse model which was induced by ovalbumin (OVA).

RESULTS

IMP was found to reduce substance P (SP) induced calcium flux and suppressed degranulation of MC. SP can promote the phosphorylation of ERK and CamKII, which regulates the synthesis of inflammatory factors such as MIP-2 and TNF-α in MC. In vivo assays revealed that IMP can mitigate SP-induced mouse PCA and ASA. IMP could also mitigate lung inflammation in an OVA induced mice model by inhibiting MC activation in the lung tissue. Furthermore, IMP binds well to MRGPRX2 protein. The binding constant (KD) is 4.48 ± 0.49 × 10-7 M. The data suggeste that IMP is a novel inhibitor of MRGPRX2 to treat allergic asthma.

Disruption in the balance between apolipoprotein A-I and mast cell chymase in chronic hypersensitivity pneumonitis

Background

Apolipoprotein A‐I (apoA‐I) has an antifibrotic effect in idiopathic pulmonary fibrosis. Although pulmonary fibrosis is associated with poor prognosis of patients with hypersensitivity pneumonitis (HP), little is known regarding the role of apoA‐I in the pathogenesis of HP.

Methods

Two‐dimensional electrophoresis, immunoblotting, and enzyme‐linked immunosorbent assays were performed for the identification and quantification of apoA‐I in bronchoalveolar lavage fluid (BALF) from patients with acute and chronic HP. To investigate the degradation of apoA‐I, apoA‐I was incubated with BALF. Moreover, the role of apoA‐I in TGF‐β1‐induced epithelial–mesenchymal transition of A549 cells was examined.

Results

The concentration of apoA‐I in the BALF was significantly lower in chronic HP (n = 56) compared with acute HP (n = 31). The expression level of apoA‐I was also low in the lung tissues of chronic HP. ApoA‐I was degraded by BALF from HP patients. The number of chymase‐positive mast cells in the alveolar parenchyma was inversely correlated with apoA‐I levels in the BALF of chronic HP patients. In vitro experiment using A549 cells, untreated apoA‐I inhibited TGF‐β1‐induced epithelial–mesenchymal transition, although this trend was not observed in the chymase‐treated apoA‐I.

Conclusions

A decrease of apoA‐I was associated with the pathogenesis of chronic HP in terms of pulmonary fibrosis and mast cell chymase attenuated the protective effect of apoA‐I against pulmonary fibrosis. Furthermore, apoA‐I could be a crucial molecule associated with lung fibrogenesis of HP.

Effects of mesenchymal stromal cell-conditioned media on measures of lung structure and function: a systematic review and meta-analysis of preclinical studies

BACKGROUND

Lung disease is a leading cause of morbidity and mortality. A breach in the lung alveolar-epithelial barrier and impairment in lung function are hallmarks of acute and chronic pulmonary illness. This review is part two of our previous work. In part 1, we demonstrated that CdM is as effective as MSCs in modulating inflammation. Herein, we investigated the effects of mesenchymal stromal cell (MSC)-conditioned media (CdM) on (i) lung architecture/function in animal models mimicking human lung disease, and (ii) performed a head-to-head comparison of CdM to MSCs.

METHODS

Adhering to the animal Systematic Review Centre for Laboratory animal Experimentation protocol, we conducted a search of English articles in five medical databases. Two independent investigators collected information regarding lung: alveolarization, vasculogenesis, permeability, histologic injury, compliance, and measures of right ventricular hypertrophy and right pulmonary pressure. Meta-analysis was performed to generate random effect size using standardized mean difference with 95% confidence interval.

RESULTS

A total of 29 studies met inclusion. Lung diseases included bronchopulmonary dysplasia, asthma, pulmonary hypertension, acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis. CdM improved all measures of lung structure and function. Moreover, no statistical difference was observed in any of the lung measures between MSCs and CdM.

CONCLUSIONS

In this meta-analysis of animal models recapitulating human lung disease, CdM improved lung structure and function and had an effect size comparable to MSCs.

Granulocyte-targeted therapies for airway diseases

The average respiration rate for an adult is 12-20 breaths per minute, which constantly exposes the lungs to allergens and harmful particles. As a result, respiratory diseases, which includes asthma, chronic obstructive pulmonary disease (COPD) and acute lower respiratory tract infections (LTRI), are a major cause of death worldwide. Although asthma, COPD and LTRI are distinctly different diseases with separate mechanisms of disease progression, they do share a common feature - airway inflammation with intense recruitment and activation of granulocytes and mast cells. Neutrophils, eosinophils, basophils, and mast cells are crucial players in host defense against pathogens and maintenance of lung homeostasis. Upon contact with harmful particles, part of the pulmonary defense mechanism is to recruit these cells into the airways. Despite their protective nature, overactivation or accumulation of granulocytes and mast cells in the lungs results in unwanted chronic airway inflammation and damage. As such, understanding the bright and the dark side of these leukocytes in lung physiology paves the way for the development of therapies targeting this important mechanism of disease. Here we discuss the role of granulocytes in respiratory diseases and summarize therapeutic strategies focused on granulocyte recruitment and activation in the lungs.

Repositioning Chromones for Early Anti-inflammatory Treatment of COVID-19

The COVID-19 pandemic is posing an unprecedented sanitary threat. In the absence of specific vaccines and anti-SARS-CoV-2 drugs, medicines that may assist in tackling the emergency and limiting the high number of fatalities are urgently needed. The repositioning of available drugs to treat COVID-19 is the only and rapid option in the face of the lack of direct antiviral agents and vaccines available. In this light it is important to focus on available drugs, which, based on their pharmacodynamics, could plausibly attenuate viral growth as well as COVID-19’s worst complications. This is the case of chloroquine and tocilizumab which seem to limit virus replication and the severity of interstitial pneumonia, respectively. However, these treatments, particularly those aimed at containing inflammation, are still reserved for the most severe cases. This commentary elaborates on the pharmacological rationale of repositioning the mast cell stabilizer chromones as an adjunctive treatment for SARS‐CoV‐2 infection, and proposes their practical clinical testing as an early, safe, and cost-effective anti-inflammatory intervention in COVID-19 to limit the eventual secondary progression toward life-threatening respiratory complications.

Microphysiological systems modeling acute respiratory distress syndrome that capture mechanical force-induced injury-inflammation-repair

Complex in vitro models of the tissue microenvironment, termed microphysiological systems, have enormous potential to transform the process of discovering drugs and disease mechanisms. Such a paradigm shift is urgently needed in acute respiratory distress syndrome (ARDS), an acute lung condition with no successful therapies and a 40% mortality rate. Here, we consider how microphysiological systems could improve understanding of biological mechanisms driving ARDS and ultimately improve the success of therapies in clinical trials. We first discuss how microphysiological systems could explain the biological mechanisms underlying the segregation of ARDS patients into two clinically distinct phenotypes. Then, we contend that ARDS-mimetic microphysiological systems should recapitulate three critical aspects of the distal airway microenvironment, namely, mechanical force, inflammation, and fibrosis, and we review models that incorporate each of these aspects. Finally, we recognize the substantial challenges associated with combining inflammation, fibrosis, and/or mechanical force in microphysiological systems. Nevertheless, complex in vitro models are a novel paradigm for studying ARDS, and they could ultimately improve patient care.

Crosstalk between cancer-associated fibroblasts and immune cells in cancer

Multiple studies have shown that cancer‐associated fibroblasts (CAFs) play an important role in tumour progression, including carcinogenesis, invasion, metastasis and the chemoresistance of cancer cells. Immune cells, including macrophages, natural killer cells, dendritic cells and T cells, play a dual role in the tumour microenvironment. Although increasing research has focused on studying interactions between distinct cells in the tumour microenvironment, the complex relationships between CAFs and immune cells remain unclear and need further study. Here, we summarize our current understanding of crosstalk between CAFs and immune cells, which may help clarify their diagnostic and therapeutic value in tumour progression.

Modulation of the endogenous Annexin A1 in a cigarette smoke cessation model: Potential therapeutic target in reversing the damage caused by smoking?

BACKGROUND

Smoking cessation may help in the reversal of inflammation and damage caused by smoking. The endogenous annexin A1 (AnxA1) protein has anti-inflammatory effects which instigates the understanding of its role in the attenuation of inflammatory processes caused by smoking.

MATERIAL AND METHODS

Wistar rats were exposed to cigarette smoke for 8 weeks. After the exposure period, one of the groups remained other 8 weeks in the absence of smoke. Animals not exposed to smoke were used as control. Blood, trachea and lungs were obtained for histopathological, immunohistochemical and biochemical analyses.

RESULTS

Loss of cilia of the tracheal lining epithelium was found by smoke exposure, but smoking cessation led to recovery of the tracheal epithelium. Similarly, chronically exposed-to-smoke animals showed increased lymphocytes and macrophages in bronchoalveolar lavage and higher levels of glucose and gamma-GT in their blood. Reduction of lymphocytes, glucose and gamma-GT occurred after smoking cessation. In addition, IL-1β, IL-6, IL-10, TNF-α and MCP-1 levels were elevated by smoke exposure. Smoking cessation significantly reduced the levels of IL-1β, IL-6 and MCP-1 but increased the IL-10 concentration. Numerous mast cells and macrophages were observed in the lung of chronically exposed-to-smoke animals with reduction by smoking cigarette abstinence. AnxA1 increased expression and concomitant NF-κB reduction were found in the smoking cessation group.

CONCLUSION

Our results showed that cigarette abstinence promoted partial recovery of the inflammatory process. The attenuation of the inflammatory profile may be associated with the overexpression of AnxA1 protein.

Impact of fossil fuel emissions and particulate matter on pulmonary health

In recent decades, several national and international legislative efforts have aimed to improve air quality standards and limit major pollutants, such as carbon monoxide, sulfur dioxide, and nitrogen dioxide, linked to several public health problems. In recent years, particulate matter sources have become an important cause of several pulmonary and systemic diseases. Specifically, several studies examining cigarette smoke particulates have discovered the important contribution that mast cells play in the pathogenesis and progression of smoking-related lung disease and other particulate matter-related lung injury. By understanding the mechanisms of activation and signaling cascades involved in cigarette smoke and mast cell activation, novel pharmacological therapies for particulate matter-induced lung diseases could be developed.

Mast Cell-Mediated Orchestration of the Immune Responses in Human Allergic Asthma: Current Insights

Improving the lung function after experimental allergen challenge by blocking of mast cell (MC) mediators and the capability of MC mediators (including histamine, prostaglandin (PG) D2, and leukotriene (LT) C4) in induction of mucosal edema, bronchoconstriction, and mucus secretion provide evidence that MCs play a key role in pathophysiology of asthma. In asthma, the number of MCs increases in the airways and infiltration of MCs in a variety of anatomical sites including the epithelium, the submucosal glands, and the smooth muscle bundles occurs. MC localization within the ASM is accompanied with the hypertrophy and hyperplasia of the layer, and smooth muscle dysfunction that is mainly observed in forms of bronchial hyperresponsiveness, and variable airflow obstruction. Owing to the expression of a wide range of surface receptors and releasing various cytoplasmic mediators, MCs orchestrate the pathologic events of the disease. MC-released preformed mediators including chymase, tryptase, and histamine and de novo synthesized mediators such as PGD2, LTC4, and LTE4 in addition of cytokines mainly TGFβ1, TSLP, IL-33, IL-4, and IL-13 participate in pathogenesis of asthma. The release of MC mediators and MC/airway cell interactions during remodeling phase of asthma results in persistent cellular and structural changes in the airway wall mainly epithelial cell shedding, goblet cell hyperplasia, hypertrophy of ASM bundles, fibrosis in subepithelial region, abnormal deposition of extracellular matrix (ECM), increased tissue vascularity, and basement membrane thickening. We will review the current knowledge regarding the participation of MCs in each stage of asthma pathophysiology including the releasing mediators and their mechanism of action, expression of receptors by which they respond to stimuli, and finally the pharmaceutical products designed based on the strategy of blocking MC activation and mediator release.

Leukocyte immunoglobulin-like receptor B4 deficiency exacerbates acute lung injury via NF-κB signaling in bone marrow-derived macrophages

Acute lung injury (ALI) is an acute inflammatory disease. Leukocyte immunoglobulin-like receptor B4 (LILRB4) is an immunoreceptor tyrosine-based inhibitory motif (ITIM)-bearing inhibitory receptor that is implicated in various pathological processes. However, the function of LILRB4 in ALI remains largely unknown. The aim of the present study was to explore the role of LILRB4 in ALI. LILRB4 knockout mice (LILRB4 KO) were used to construct a model of ALI. Bone marrow cell transplantation was used to identify the cell source of the LILRB4 deficiency-aggravated inflammatory response in ALI. The effect on ALI was analyzed by pathological and molecular analyses. Our results indicated that LILRB4 KO exacerbated ALI triggered by LPS. Additionally, LILRB4 deficiency can enhance lung inflammation. According to the results of our bone marrow transplant model, LILRB4 regulates the occurrence and development of ALI by bone marrow-derived macrophages (BMDMs) rather than by stromal cells in the lung. The observed inflammation was mainly due to BMDM-induced NF-κB signaling. In conclusion, our study demonstrates that LILRB4 deficiency plays a detrimental role in ALI-associated BMDM activation by prompting the NF-κB signal pathway.

Dermal exposure determines the outcome of repeated airway exposure in a long-term chemical-induced asthma-like mouse model

BACKGROUND

Exposure to diisocyanates is an important cause of occupational asthma (OA) in the industrialized world. Since OA occurs after long-term exposure to diisocyanates, we developed a chronic mouse model of chemical-induced asthma where toluene diisocyanate (TDI) was administered at two different exposure sites.

OBJECTIVES

Evaluating the effect of long-term respiratory isocyanate exposure - with or without prior dermal exposure- on sensitization, inflammatory responses and airway hyperreactivity (AHR).

METHODS

On days 1 and 8, BALB/c mice were dermally treated (20 μl/ear) with 0.5% 2,4-toluene diisocyanate TDI or the vehicle acetone olive oil (AOO) (3:2). Starting from day 15, mice received intranasal instillations with 0.1% TDI of vehicle five times in a week, for five successive weeks. One day after the last instillation airway hyperreactivity (AHR) to methacholine was assessed, followed by an evaluation of pulmonary inflammation and structural lung changes. Immune-related parameters were assessed in the lungs (BAL and tissue), blood, cervical- and auricular lymph nodes.

RESULTS

Mice repeatedly intranasally exposed to TDI showed systemic sensitization and a mixed Th1/Th2 type immune response, without the presence of AHR. However, when mice are first dermally sensitized with TDI, followed by repeated intranasal TDI challenges, this results in a pronounced Th2 response and AHR.

CONCLUSION

Dermal exposure to TDI determines airway hyperreactivity after repeated airway exposure to TDI.

Exon Skipping of FcεRIβ for Allergic Diseases

Mast cells are key effector cells in allergic inflammation and consequently are ideal targets for new therapeutics. The high-affinity IgE receptor complex, FcεRI, plays a critical role in mast cell and basophil activation by allergens to drive the immediate allergic inflammatory response. The β subunit of FcεRI is critical for trafficking the FcεRI complex to the cell membrane and amplifies the FcεRI signaling cascade. We have utilized splice switching antisense oligonucleotides to force expression of a truncated isoform of FcεRIβ, which we have shown does not associate with the FcεRI complex. This approach eliminates surface FcεRI expression in mast cells by targeting protein-protein interactions. Exon skipping has several therapeutic applications, and our findings demonstrate a novel application to alter receptor trafficking and dampen allergic inflammation. Here, we describe the methods of exon skipping in mast cells and the assays used to examine the responses of mast cells in vitro and in vivo.

The anti-fibrotic role of mast cells in the liver is mediated by HLA-G and interaction with hepatic stellate cells

BACKGROUND & AIMS

We have reported a significant association between HLA-G expression or the number of hepatic mast cells and liver fibrosis. Here, we investigated the role of HLA-G and mast cells in liver fibrosis, focusing, in particular, on interactions between human mast and stellate cells.

METHODS

Human mast cells (HMC cell line, CD34-derived mast cells, or tissue-derived mast cells) were co-cultured with purified human hepatic stellate cells (HSCs), and collagen I production by HSCs was evaluated. Mast cells and HSCs were characterized by immunocytochemistry. Various conditions were tested: different times in direct or indirect contact, presence or absence of cytokines, addition or not of HLA-G, and presence or absence of specific protease inhibitors.

RESULTS

The reciprocal interaction between HSCs and mast cells led to the attraction of mast cells to HSCs in vivo and in vitro, and to a significant decrease in collagen production, at all times of co-culture, following the direct or indirect contact of mast cells with HSCs alone or in the presence of TGF-β, IFN-α or IL-10. We identified the diffusible factors involved in collagen I degradation as mast cell proteases. Moreover, HLA-G expression increased during the co-culture of HSCs and mast cells, with HLA-G acting on both mast cells and HSCs, to enhance collagen I degradation.

CONCLUSIONS

Mast cells play a beneficial, anti-fibrotic role in liver fibrosis, via the HLA-G-mediated decrease of collagen I. These findings are consistent with high levels of cross-communication between mast cells and hepatic stellate cells and the role of HLA-G.

Rescue of rhesus macaques from the lethality of aerosolized ricin toxin

Ricin toxin (RT) ranks at the top of the list of bioweapons of concern to civilian and military personnel alike, due to its high potential for morbidity and mortality after inhalation. In nonhuman primates, aerosolized ricin triggers severe acute respiratory distress characterized by perivascular and alveolar edema, neutrophilic infiltration, and severe necrotizing bronchiolitis and alveolitis. There are currently no approved countermeasures for ricin intoxication. Here, we report the therapeutic potential of a humanized mAb against an immunodominant epitope on ricin's enzymatic A chain (RTA). Rhesus macaques that received i.v. huPB10 4 hours after a lethal dose of ricin aerosol exposure survived toxin challenge, whereas control animals succumbed to ricin intoxication within 30 hours. Antibody intervention at 12 hours resulted in the survival of 1 of 5 monkeys. Changes in proinflammatory cytokine, chemokine, and growth factor profiles in bronchial alveolar lavage fluids before and after toxin challenge successfully clustered animals by treatment group and survival, indicating a relationship between local tissue damage and experimental outcome. This study represents the first demonstration, to our knowledge, in nonhuman primates that the lethal effects of inhalational ricin exposure can be negated by a drug candidate, and it opens up a path forward for product development.

Role of inflammatory cells in airway remodeling in COPD

COPD is characterized by chronic bronchitis, chronic airway obstruction, and emphysema, leading to a progressive and irreversible decline in lung function. Inflammation is central for the development of COPD. Chronic inflammation in COPD mainly involves the infiltration of neutrophils, macrophages, lymphocytes, and other inflammatory cells into the small airways. The contribution of resident airway structural cells to the inflammatory process is also important in COPD. Airway remodeling consists of detrimental changes in structural tissues and cells including airway wall thickening, epithelial metaplasia, goblet cell hypertrophy, and smooth muscle hyperplasia. Persistent airway inflammation might contribute to airway remodeling and small airway obstruction. However, the underlying mechanisms remain unclear. In this review, we will provide an overview of recent insights into the role of major immunoinflammatory cells in COPD airway remodeling.

Expression and modulation of S100A4 protein by human mast cells

S100A4 protein is expressed in fibroblasts during tissue remodelling and in cancer stem cells and it induces the metastatic spread of tumor cells. In mast cells (MCs) S100A4 have been found in some pathological conditions, but its function in normal MCs remains to be described. The purpose of this study was to characterize the cellular localization of the S100A4 protein in MCs of human tissues with inflammatory or tumor disorders and, to determine the consequence of reducing its expression in MC response. We found that tissue resident MCs stained positive to S100A4. Both human HMC-1 cell line and resting CD34⁺-derived MCs expressed S100A4, whose levels were differentially modulated upon MC activation. Downregulation of the S100A4 protein resulted in MC growth inhibition, enhanced apoptosis and deregulation of MMP-1 and MMP-10 production. Our results suggest that S100A4 is also playing a role in the MC life cycle and functions.

The contribution of mast cells to bacterial and fungal infection immunity

Mast cells are hematopoietic progenitor-derived, granule-containing immune cells that are widely distributed in tissues that interact with the external environment, such as the skin and mucosal tissues. It is well-known that mast cells are significantly involved in IgE-mediated allergic reactions, but because of their location, it has also been long hypothesized that mast cells can act as sentinel cells that sense pathogens and initiate protective immune responses. Using mast cell or mast cell protease-deficient murine models, recent studies by our groups and others indicate that mast cells have pleiotropic regulatory roles in immunological responses against pathogens. In this review, we discuss studies that demonstrate that mast cells can either promote host resistance to infections caused by bacteria and fungi or contribute to dysregulated immune responses that can increase host morbidity and mortality. Overall, these studies indicate that mast cells can influence innate immune responses against bacterial and fungal infections via multiple mechanisms. Importantly, the contribution of mast cells to infection outcomes depends in part on the infection model, including the genetic approach used to assess the influence of mast cells on host immunity, hence highlighting the complexity of mast cell biology in the context of innate immune responses.

Therapeutic use of heparin and derivatives beyond anticoagulation in patients with bronchial asthma or COPD

In this review, we identify potential targets for the therapeutic effects of heparin in asthma and chronic obstructive pulmonary disease (COPD), consider the safety and delivery modalities of this therapeutic approach. Specifically, we point to the anti-inflammatory, antioxidant and mucolytic effects of unfractionated heparin with potential to modify disease progression in COPD and asthma when administered via the inhaled route. Inhaled heparin may represent an effective add-on therapy in COPD and asthma patient groups, especially when taking into consideration the relative deficiency in endogenous heparin reported in asthma patients.

Palmitoylethanolamide Supplementation during Sensitization Prevents Airway Allergic Symptoms in the Mouse

One important risk factor for the development of asthma is allergen sensitization. Recent increasing evidence suggests a prominent role of mast cells in asthma pathophysiology. Since Palmitoylethanolamide (PEA), an endogenous lipid mediator chemically related to - and co-released with- the endocannabinoid anandamide, behaves as a local autacoid down-regulator of mast cell activation and inflammation, we explored the possible contribution of PEA in allergic sensitization, by using ovalbumin (OVA) as sensitizing agent in the mouse. PEA levels were dramatically reduced in the bronchi of OVA-treated animals. This effect was coupled to a significant up-regulation of CB₂ and GPR55 receptors, two of the proposed molecular PEA targets, in bronchi harvested from allergen-sensitized mice. PEA supplementation (10 mg/kg, 15 min before each allergen exposure) prevented OVA-induced bronchial hyperreactivity, but it did not affect IgE plasma increase. On the other hand, PEA abrogated allergen-induced cell recruitment as well as pulmonary inflammation. Evaluation of pulmonary sections evidenced a significant inhibitory action of PEA on pulmonary mast cell recruitment and degranulation, an effect coupled to a reduction of leukotriene C₄ production. These findings demonstrate that allergen sensitization negatively affects PEA bronchial levels and suggest that its supplementation has the potential to prevent the development of asthma-like features.