The role of HMGB1/RAGE/TLR4 signaling pathways in cigarette smoke-induced inflammation in chronic obstructive pulmonary disease

The implication of dendritic cells in lung diseases: Immunological role of toll-like receptor 4

The immune responses play a profound role in the progression of lung lesions in both infectious and non-infectious diseases. Dendritic cells, as the "frontline" immune cells responsible for antigen presentation, set up a bridge between innate and adaptive immunity in the course of these diseases. Among the receptors equipped in dendritic cells, Toll-like receptors are a group of specialized receptors as one type of pattern recognition receptors, capable of sensing environmental signals including invading pathogens and self-antigens. Toll-like receptor 4, a pivotal member of the Toll-like receptor family, was formerly recognized as a receptor sensitive to the outer membrane component lipopolysaccharide derived from Gram-negative bacteria, triggering the subsequent response. Moreover, its other essential roles in immune responses have drawn significant attention in the past decade. A better understanding of the implication of Toll-like receptor 4 in dendritic cells could contribute to the management of pulmonary diseases including pneumonia, pulmonary tuberculosis, asthma, acute lung injury, and lung cancer.

Interleukin-1 receptor-associated kinase 4 (IRAK4) is a critical regulator of inflammatory signalling through toll-like receptors 4 and 7/8 in murine and human lungs

BACKGROUND AND PURPOSE

Toll-like receptors 4 (TLR4) and TLR7/TLR8 play an important role in mediating the inflammatory effects of bacterial and viral pathogens. Interleukin-1 receptor-associated kinase 4 (IRAK4) is an important regulator of signalling by toll-like receptor (TLR) and hence is a potential therapeutic target in diseases characterized by increased lung inflammatory signalling.

EXPERIMENTAL APPROACH

We used an established murine model of acute lung inflammation, and studied human lung tissue ex vivo, to investigate the effects of inhibiting IRAK4 on lung inflammatory pathways.

KEY RESULTS

We show that TLR4 stimulation produces an inflammatory response characterized by neutrophil influx and tumour necrosis factor-α (TNF-α) production in murine lungs and that these responses are markedly reduced in IRAK4 kinase-dead mice. In addition, we characterize a novel selective IRAK4 inhibitor, BI1543673, and show that this compound can reduce lipopolysaccharide (LPS)-induced airway inflammation in wild-type mice. Additionally, BI1543673 reduced inflammatory responses to both TLR4 and TLR7/8 stimulation in human lung tissue studied ex vivo.

CONCLUSION AND IMPLICATIONS

These data demonstrate a key role for IRAK4 signalling in lung inflammation and suggest that IRAK4 inhibition has potential utility to treat lung diseases characterized by inflammatory responses driven through TLR4 and TLR7/8.

Role of diesel exhaust particle-induced cellular senescence in the development of asthma in young and old mice

BACKGROUND

Although it has been reported that cellular senescence is important in the pathogenesis of asthma, the differential effects of diesel exhaust particle (DEP)-induced cellular senescence on the development of asthma according to age have not been thoroughly studied.

METHODS

We first confirmed that DEP induced cellular senescence in mouse lungs, and then that DEP-induced cellular senescence followed by intranasal instillation of a low-dose house dust mite (HDM) allergen resulted in murine asthma. Second, we examined age-dependent differential effects using 6-week-old (young) and 18-month-old mice (old), and tested whether the mammalian target of the rapamycin (mTOR) pathway plays an important role in this process. Finally, we performed in vitro experiments using human bronchial epithelial cells (HBEC) originating from young and elderly adults to identify the underlying mechanisms.

RESULTS

DEP induced cellular senescence in the airway epithelial cells of young and old mice characterized by increased senescence-associated beta-galactosidase, S100A8/9, and high mobility group box 1 (HMGB1) expressions. DEP-induced cellular senescence with subsequent exposure to a low-dose HDM allergen resulted in asthma in young and old mice. Rapamycin (mTOR pathway inhibitor) administration before DEP instillation significantly attenuated these asthmatic features. In addition, after treatment with a low-dose HDM allergen, S100A9 and HMGB1 over-expressed HBEC originating from young and elderly adults greatly activated co-cultured monocyte-derived dendritic cells (DCs).

CONCLUSIONS

This study showed that DEP-induced senescence made both young and old mice susceptible to allergic sensitization and resultant asthma development by enhancing DC activation. Public health efforts to reduce DEP exposure are warranted.

Anti-inflammatory actions of aspirin-triggered resolvin D1 (AT-RvD1) in bronchial epithelial cells stimulated by cigarette smoke extract

Smoking causes several diseases such as chronic obstructive pulmonary disease (COPD). Aspirin-triggered-resolvin D1 (AT-RvD1) is a lipid mediator produced during the resolution of inflammation and demonstrates anti-inflammatory and pro-resolution effects in several inflammatory experimental models including in the airways. Here we evaluated the role of AT-RvD1 (100 nM) in bronchial epithelial cells (BEAS-2B) stimulated by cigarette smoke extract (CSE; 1%; 1 cigarette) for 24 h. CSE induced the productions of IL-1β, TNF-α, IL-10, IL-4 and IFN-γ as well as the activations of NF-κB and STAT3 and the expression of ALX/FPR2 receptor. AT-RvD1 reduced the IL-1β and TNF-α production and increased the production of IFN-γ. These effects were reversed BOC2, an antagonist of ALX/FPR2 receptor for AT-RvD1. The production of IL-4 and IL-10 were not altered by AT-RvD1. In addition, AT-RvD1 reduced the phosphorylation of NF-κB and STAT3 when compared to CSE-stimulated BEAS-2B cells. No alteration of ALX/FPR2 expression was observed by AT-RvD1 when compared to CSE group. In the human monocytic leukemia cell line, the relative number of copies of IL-1β and IL-4 was significantly higher in CSE + AT-RvD1 group compared CSE group, however, the expression of M1 cytokine was more pronounced than M2 profile. AT-RvD1 could be an important target for the reduction of inflammation in the airways associated with smoking.

Identification of related-genes of T cells in lung tissue of chronic obstructive pulmonary disease based on bioinformatics and experimental validation

T cells are one of the main cell types shaping the immune microenvironment in chronic obstructive pulmonary disease (COPD). They persist andplay cytotoxic roles. The purpose of this study aimed to explore the potential related-genes of T cells in lung tissue of COPD. Chip data GSE38974 and single_celldata GSE196638 were downloaded from the GEO database. Difference analyses and WGCNA of GSE38974 were performed to identify DEGs and the modules most associated with the COPD phenotype. Various cell subsets were obtained by GSE196638, and DEGs of T cells were further identified. GO, GSEA and KEGG enrichment analyses were conducted to explore the biological functions and regulatory signaling pathways of the DEGs and DEGs of T cells. The intersection of the DEGs, module genes and DEGs of T cells was assessed to acquire related-genes of T cells. The mRNA and protein expression levels of related-genes ofT cells were verified in lung tissue of mouse with emphysema model. Based on GSE38974 difference analysis, 3811 DEGs were obtained. The results of WGCNA showed that the red module had the highest correlation coefficient with the COPD phenotype. GSE196638 analysis identified 124 DEGs of T cells. The GO, GSEAand KEGG enrichment analyses mainly identified genes involved in I-kappaB kinase/NF-kappaB signaling, receptor signaling pathway via STAT, regulationof CD4-positive cells, regulation of T-helper cell differentiation, chemokine signaling pathway, Toll-likereceptor signaling pathway, CD8-positive cells, alpha-beta T cell differentiation, MAPK signaling pathway and Th17 cell differentiation. The DEGs, genes of the red module and DEGs of T cells were overlapped to acquire FOXO1 and DDX17. The results of RT-qPCR and Western Blot indicate that the mRNA and protein expression levels of FOXO1 and DDX17 in lung tissue of emphysema mice were significantly higher compared with those in air-exposed mice. FOXO1 as well as DDX17 may be related-genesof T cells in lung tissue of patient with COPD, and their participation in the biological processes of different signaling pathways may inspire further COPD research.

Combined analysis of bulk RNA and single-cell RNA sequencing to identify pyroptosis-related markers and the role of dendritic cells in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by dyspnea caused by airflow limitation. Further development may lead to decreased lung function and other lung diseases. Pyroptosis is a type of programmed cell death that involves multiple pathways. For example, the pathway induced by the NLR family pyrin domain containing 3 (NLRP3) inflammasome is closely associated with COPD exacerbation. Therefore, in this study, various machine learning algorithms were applied to screen for diagnostically relevant pyroptosis-related genes from the GEO dataset, and the results were verified using external datasets. The results showed that deep neural networks and logistic regression algorithms had the highest AUC of 0.91 and 0.74 in the internal and external test sets, respectively. Here, we explored the immune landscape of COPD using diagnosis-related genes. We found that the infiltrating abundance of dendritic cells significantly differed between the COPD and control groups. Finally, the communication patterns of each cell type were explored based on scRNA-seq data. The critical role of significant pathways involved in communication between DCS and other cell populations in the occurrence and progression of COPD was identified.

Intranasal Exendin-4 modifies necroptosis-mediated innate immune response to combat septic encephalopathy in rats: Role of mTORC1 in immunogenic and tolerogenic cell demise

Septic encephalopathy (SE) is a critical mental status associated with potential long-term cognitive deficits and higher mortality rates in ICU patients. The shortfall in comprehending its pathophysiology limits effective treatment options, however, GLP-1 agonists opened an entry point for future neurodegenerative disease management. This work aims to explore the mTORC1 prospective role in the pathogenesis of SE using rapamycin (RAPA) and investigate the involvement of this complex in exendin-4 (EX4) neurotherapeutic potential using cecal ligation and puncturing (CLP)-induced SE model, focusing on necroptosis as a novel intervention besides necrosis and apoptosis. EX4 was administered intranasally alone or preceded by RAPA, which was also solely given to male Sprague-Dawley rats subjected to CLP. First, opposite to the SE effect, RAPA inhibited mTORC1 and blunted TNF-α-induced necroptosis and Drp1, a mitochondrial fission marker. However, RAPA worsened the SE effect on endotoxemia, functional/cortical structures, and apoptotic/necrotic cell deaths. Second, EX4 increased mTORC1 assembly in the cerebral cortex and reduced sepsis-induced endotoxemia and behavioral/cerebral histopathology deficits in an mTOR-dependent manner. EX4 also reduced the inflammatory marker TNF-α and necroptosis as indicated by RIPK-1/RIPK-3/MLKL dephosphorylation and deactivated PGAM/Drp1 axis. Besides, EX4 turned off the apoptotic cue, caspase-3&8/cytochrome-C. However, RAPA pre-administration nullified the EX4 effect on apoptosis and HMGB1-induced necrosis. In conclusion, our research declares that targeting mTORC1 could be a promising approach for managing SE. Additionally, we highlight that the novel neuroprotective effect of EX4 in ameliorating SE is achieved by reducing necroptosis and utilizing the anti-apoptotic and anti-necrotic properties of mTORC1.

Lung Microbiome as a Treatable Trait in Chronic Respiratory Disorders

Once thought to be a sterile environment, it is now established that lungs are populated by various microorganisms that participate in maintaining lung function and play an important role in shaping lung immune surveillance. Although our comprehension of the molecular and metabolic interactions between microbes and lung cells is still in its infancy, any event causing a persistent qualitative or quantitative variation in the composition of lung microbiome, termed "dysbiosis", has been virtually associated with many respiratory diseases. A deep understanding of the composition and function of the "healthy" lung microbiota and how dysbiosis can cause or participate in disease progression will be pivotal in finding specific therapies aimed at preventing diseases and restoring lung function. Here, we review lung microbiome dysbiosis in different lung pathologies and the mechanisms by which these bacteria can cause or contribute to the severity of the disease. Furthermore, we describe how different respiratory disorders can be caused by the same pathogen, and that the real pathogenetic mechanism is not only dependent by the presence and amount of the main pathogen but can be shaped by the interaction it can build with other bacteria, fungi, and viruses present in the lung. Understanding the nature of this bacteria crosstalk could further our understanding of each respiratory disease leading to the development of new therapeutic strategies.

Liver X receptors and estrogen receptor β, two players in a rare subtype of NSCLC

Liver X receptors (LXRαβ) play essential roles in the maintenance of the normal functions of macrophages, in modulation of immune system responses and cholesterol homeostasis. We have reported that LXRαβ^-/- mice develop squamous cell lung cancer. We now report that those LXRαβ^-/- mice, which live to 18-months of age, spontaneously develop a second type of lung cancer resembling a rare subtype of NSCLC (TTF-1 and P63-positive). The lesions are characterized as follows: a high proliferation rate; a marked accumulation of abnormal macrophages; an increase in the number of regulatory T cells; a remarkably low level of CD8⁺ cytotoxic T lymphocytes; enhanced TGFβ signaling; an increased expression of matrix metalloproteinases accompanied by degradation of lung collagen; and a loss of estrogen receptor β (ERβ). Because NSCLC is associated with cigarette smoking, we investigated the possible links between loss of LXRαβ and CS. A Kaplan-Meier Plotter database revealed reduced expression of LXRαβ and ERβ was correlated with low overall survival (OS). Thus, reduction of LXRαβ expression by cigarette smoking may be one mechanism through which CS causes lung cancer. The possibility that maintenance of LXRαβ and ERβ signaling could be used in the treatment of NSCLC needs further investigation.

Advanced Biomarkers of Hepatotoxicity in Psychiatry: A Narrative Review and Recommendations for New Psychoactive Substances

One of the factors that increase the effectiveness of the pharmacotherapy used in patients abusing various types of new psychoactive substances (NPSs) is the proper functioning of the liver. However, the articles published to date on NPS hepatotoxicity only address non-specific hepatic parameters. The aim of this manuscript was to review three advanced markers of hepatotoxicity in psychiatry, namely, osteopontin (OPN), high-mobility group box 1 protein (HMGB1) and glutathione dehydrogenase (GDH, GLDH), and, on this basis, to identify recommendations that should be included in future studies in patients abusing NPSs. This will make it possible to determine whether NPSs do indeed have a hepatotoxic effect or whether other factors, such as additional substances taken or hepatitis C virus (HCV) infection, are responsible. NPS abusers are at particular risk of HCV infection, and for this reason, it is all the more important to determine what factors actually show a hepatotoxic effect in them.