Cigarette Smoke-Induced Lymphoid Neogenesis in COPD Involves IL-17/RANKL Pathway

TET2 stabilized by deubiquitinase USP21 ameliorates cigarette smoke-induced apoptosis in airway epithelial cells

DNA demethylase TET2 was related with lung function. However, the precise role of TET2 in cigarette smoke (CS)-induced apoptosis of airway epithelium cells, and the mechanisms involved, have yet to be elucidated. Here, we showed that CS decreased TET2 protein levels but had no significant effect on its mRNA levels in lung tissues of chronic obstructive pulmonary disease (COPD) patients and CS-induced COPD mice model and even in airway epithelial cell lines. TET2 could inhibit CS-induced apoptosis of airway epithelial cell in vivo and in vitro. Moreover, we identified ubiquitin-specific protease 21 (USP21) as a deubiquitinase of TET2 in airway epithelial cells. USP21 interacted with TET2 and inhibited CSE-induced TET2 degradation. USP21 downregulated decreased TET2 abundance and further reduced the anti-apoptosis effect of TET2. Thus, we draw a conclusion that the USP21/TET2 axis is involved in CS-induced apoptosis of airway epithelial cells.

Blocking CD40 Alleviates Th1 and Th17 Cell Responses in Elastin Peptide-Induced Murine Emphysema

Purpose

To investigate the role of the CD40-CD40 ligand (CD40L) pathway in the regulation of Th1, Th17, and regulatory T (Treg)-cell responses in an elastin peptide (EP)-induced autoimmune emphysema mouse model.

Methods

BALB/c mice were transnasally treated with EP on day 0, injected intravenously with anti-CD40 antibody via the tail vein on day 33, and sacrificed on day 40. The severity of emphysema was evaluated by determining the mean linear intercept (MLI) and destructive index (DI) from lung sections. The proportions of myeloid dendritic cells (mDCs) and Th1, Th17, and Treg cells in the blood, spleen, and lungs were determined via flow cytometry. The levels of the cytokines interleukin (IL)-6, IL-17, interferon (IFN)-γ, and transforming growth factor (TGF)-β were detected via enzyme-linked immunosorbent assay. Ifnγ, IL17a, Rorγt and Foxp3 transcription levels were detected via polymerase chain reaction.

Results

CD40+ mDCs accumulated in the lungs of EP-stimulated mice. Blocking the CD40-CD40L pathway with an anti-CD40 antibody alleviated Th1 and Th17 responses; increased the proportion of Treg cells; decreased MLI and DI; reduced the levels of cytokines IL-6, IL-17, and IFN-γ as well as the transcription levels of Ifnγ, IL17a, and Rorγt; and upregulated the expression of TGF-β and Foxp3.

Conclusion

The CD40-CD40L pathway could play a critical role in Th1, Th17 and Treg cell dysregulation in EP-mediated emphysema and could be a potential therapeutic target.

Does Chronic Obstructive Pulmonary Disease Originate from Different Cell Types?

The onset of chronic obstructive pulmonary disease (COPD) is heterogeneous, and current approaches to define distinct disease phenotypes are lacking. In addition to clinical methodologies, subtyping COPD has also been challenged by the reliance on human lung samples from late-stage diseases. Different COPD phenotypes may be initiated from the susceptibility of different cell types to cigarette smoke, environmental pollution, and infections at early stages that ultimately converge at later stages in airway remodeling and destruction of the alveoli when the disease is diagnosed. This perspective provides discussion points on how studies to date define different cell types of the lung that can initiate COPD pathogenesis, focusing on the susceptibility of macrophages, T and B cells, mast cells, dendritic cells, endothelial cells, and airway epithelial cells. Additional cell types, including fibroblasts, smooth muscle cells, neuronal cells, and other rare cell types not covered here, may also play a role in orchestrating COPD. Here, we discuss current knowledge gaps, such as which cell types drive distinct disease phenotypes and/or stages of the disease and which cells are primarily affected by the genetic variants identified by whole genome-wide association studies. Applying new technologies that interrogate the functional role of a specific cell type or a combination of cell types as well as single-cell transcriptomics and proteomic approaches are creating new opportunities to understand and clarify the pathophysiology and thereby the clinical heterogeneity of COPD.

Contribution of adaptive immunity to human COPD and experimental models of emphysema

The pathophysiology of chronic obstructive pulmonary disease (COPD) and the undisputed role of innate immune cells in this condition have dominated the field in the basic research arena for many years. Recently, however, compelling data suggesting that adaptive immune cells may also contribute to the progressive nature of lung destruction associated with COPD in smokers have gained considerable attention. The histopathological changes in the lungs of smokers can be limited to the large or small airways, but alveolar loss leading to emphysema, which occurs in some individuals, remains its most significant and irreversible outcome. Critically, however, the question of why emphysema progresses in a subset of former smokers remained a mystery for many years. The recognition of activated and organized tertiary T- and B-lymphoid aggregates in emphysematous lungs provided the first clue that adaptive immune cells may play a crucial role in COPD pathophysiology. Based on these findings from human translational studies, experimental animal models of emphysema were used to determine the mechanisms through which smoke exposure initiates and orchestrates adaptive autoreactive inflammation in the lungs. These models have revealed that T helper (Th)1 and Th17 subsets promote a positive feedback loop that activates innate immune cells, confirming their role in emphysema pathogenesis. Results from genetic studies and immune-based discoveries have further provided strong evidence for autoimmunity induction in smokers with emphysema. These new findings offer a novel opportunity to explore the mechanisms underlying the inflammatory landscape in the COPD lung and offer insights for development of precision-based treatment to halt lung destruction.

Akkermansia muciniphila Ameliorates Lung Injury in Smoke-Induced COPD Mice by IL-17 and Autophagy

Objective. Smoking is a primary hazard factor for chronic obstructive pulmonary disease (COPD), which induced a decrease in intestinal Akkermansia muciniphila abundance and Th17 imbalance in COPD. This study analyzed the changes of gut microbiota metabolism and Akkermansia abundance in patients with smoking-related COPD and explored the potential function of Akkermansia muciniphila in smoke-induced COPD mice. Methods. Gut microbiota diversity and metabolic profile were analyzed by 16S rRNA sequence and metabolomics in COPD patients. The IL-1β, IL-17, TNF-α, and IL-6 levels were tested by ELISA. Lung tissue damage was observed by HE staining. The expression of cleave-caspase 3, trophoblast antigen 2 (TROP2), and LC3 in lung tissues were analyzed by IHC or IF. The p-mTOR, mTOR, p62, and LC3 expression in lung tissues were tested by western blot. Results. The levels of IL-17, IL-1β, TNF-α, and IL-6 in the peripheral blood of COPD patients increased significantly. The number and alpha diversity of gut microbiota were decreased in COPD patients. The abundance of Akkermansia muciniphila in gut of COPD patients was decreased, and the metabolic phenotype and retinol metabolism were changed. In the retinol metabolism, the retinol and retinal were significantly changed. Akkermansia muciniphila could improve the alveolar structure and inflammatory cell infiltration in lung tissue, reduce the IL-17, TNF-α, and IL-6 levels in peripheral blood, promote the p-mTOR expression, and inhibit the expression of autophagy-related proteins in smoke-induced COPD mice. Conclusion. The number and alpha diversity of gut microbiota were decreased in patients with smoking-related COPD, accompanied by decreased abundance of Akkermansia muciniphila, and altered retinol metabolism function. Gut Akkermansia muciniphila ameliorated lung injury in smoke-induced COPD mice by inflammation and autophagy.

Identification and Analysis of Necroptosis-Related Genes in COPD by Bioinformatics and Experimental Verification

Chronic obstructive pulmonary disease (COPD) is a heterogeneous and complex progressive inflammatory disease. Necroptosis is a newly identified type of programmed cell death. However, the role of necroptosis in COPD is unclear. This study aimed to identify necroptosis-related genes in COPD and explore the roles of necroptosis and immune infiltration through bioinformatics. The analysis identified 49 differentially expressed necroptosis-related genes that were primarily engaged in inflammatory immune response pathways. The infiltration of CD8+ T cells and M2 macrophages in COPD lung tissue was relatively reduced, whereas that of M0 macrophages was increased. We identified 10 necroptosis-related hub genes significantly associated with infiltrated immune cells. Furthermore, 7 hub genes, CASP8, IL1B, RIPK1, MLKL, XIAP, TNFRSF1A, and CFLAR, were validated using an external dataset and experimental mice. CFLAR was considered to have the best COPD-diagnosing capability. TF and miRNA interactions with common hub genes were identified. Several related potentially therapeutic molecules for COPD were also identified. The present findings suggest that necroptosis occurs in COPD pathogenesis and is correlated with immune cell infiltration, which indicates that necroptosis may participate in the development of COPD by interacting with the immune response.

Role of Th17 cells, Treg cells, and Th17/Treg imbalance in immune homeostasis disorders in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide, following strokes and cardiovascular diseases. Chronic lung inflammation is believed to play a role in the development of COPD. In addition, accumulating evidence shows that the immune system plays a crucial role in the pathogenesis of COPD. Significant advancements have been made in research on the pathogenesis of immune diseases and chronic inflammation in recent years, and T helper 17 (Th17) cells and regulatory T (Treg) cells have been found to play a crucial role in the autoimmune response. Th17 cells are a proinflammatory subpopulation that causes autoimmune disease and tissue damage. Treg cells, on the other hand, have a negative effect but can contribute to the occurrence of the same disease when their antagonism fails. This review mainly summarizes the biological characteristics of Th17 cells and Treg cells, their roles in chronic inflammatory diseases of COPD, and the role of the Th17/Treg ratio in the onset, development, and outcome of inflammatory disorders, as well as recent advancements in immunomodulatory treatment targeting Th17/Treg cells in COPD.

Complement component 3 protects human bronchial epithelial cells from cigarette smoke-induced oxidative stress and prevents incessant apoptosis

The complement component 3 (C3) is a pivotal element of the complement system and plays an important role in innate immunity. A previous study showed that intracellular C3 was upregulated in airway epithelial cells (AECs) from individuals with end-stage chronic obstructive pulmonary disease (COPD). Accumulating evidence has shown that cigarette smoke extract (CSE) induces oxidative stress and apoptosis in AECs. Therefore, we investigated whether C3 modulated cigarette smoke-induced oxidative stress and apoptosis in AECs and participated in the pathogenesis of COPD. We found increased C3 expression, together with increased oxidative stress and apoptosis, in a cigarette smoke-induced mouse model of COPD and in AECs from patients with COPD. Different concentrations of CSEinduced C3 expression in 16HBE cells in vitro. Interestingly, C3 knockdown (KD) exacerbated oxidative stress and apoptosis in 16HBE cells exposed to CSE. Furthermore, C3 exerted its pro-survival effects through JNK inhibition, while exogenous C3 partially rescued CSE-induced cell death and oxidative stress in C3 KD cells. These data indicate that locally produced C3 is an important pro-survival molecule in AECs under cigarette smoke exposure, revealing a potentially novel mechanism in the pathogenesis of COPD.

IL-17A Promotes Epithelial ADAM9 Expression in Cigarette Smoke-Related COPD

Background

It has been reported that a disintegrin and metalloproteinase 9 (ADAM9) is involved in the pathogenesis of cigarette smoke (CS)-associated chronic obstructive pulmonary disease (COPD). But how CS exposure leads to upregulation of ADAM9 remains unknown.

Methods

Patients who underwent lobectomy for a solitary pulmonary nodule were enrolled and divided into three groups: non-smokers with normal lung function, smokers without COPD and smoker patients with COPD. Immunoreactivity of interleukin (IL)-17A and ADAM9 in small airways and alveolar walls was measured by immunohistochemistry. Wild-type and Il17a^−/− C57BL/6 mice were exposed to CS for six months, and ADAM9 expression in the airway epithelia was measured by immunoreactivity. In addition, the protein and mRNA expression levels of IL-17A and ADAM9 were assessed in CS extract (CSE) and/or IL-17A-treated human bronchial epithelial (HBE) cells.

Results

The immunoreactivity of ADAM9 was increased in the airway epithelia and alveolar walls of patients with COPD compared to that of the controls. The expression of IL-17A was also upregulated in airway epithelial cells of patients with COPD and correlated positively with the level of ADAM9. The results from the animal model showed that Il17a^−/− mice were protected from emphysema induced by CS exposure, together with a reduced level of ADAM9 expression in the airway epithelia, suggesting a possible link between ADAM9 and IL-17A. Consistently, our in vitro cell model showed that CSE stimulated the expression of ADAM9 and IL-17A in HBE cells in a dose- and time-dependent manner. Recombinant IL-17A induced ADAM9 upregulation in HBE cells and had a synergistic effect with CSE, whereas blocking IL-17A inhibited CSE-induced ADAM9 expression. Further analysis revealed that IL-17A induced c-Jun N-terminal kinase (JNK) phosphorylation, thereby increasing ADAM9 expression.

Conclusion

Our results revealed a novel role of IL-17A in CS-related COPD, where IL-17A contributes to ADAM9 expression by activating JNK signaling.

Dysregulated myokines and signaling pathways in skeletal muscle dysfunction in a cigarette smoke–induced model of chronic obstructive pulmonary disease

Skeletal muscle dysfunction is an important extrapulmonary comorbidity of chronic obstructive pulmonary disease (COPD). Muscle-derived cytokines (myokines) play important roles in skeletal muscle growth and function, but their contributions to skeletal muscle dysfunction in COPD have not been fully understood. In the current study, by using a well-established mouse model of COPD with skeletal muscle dysfunction, we found that the expressions of Fndc5 (fibronectin type III domain-containing protein 5, the precursor of irisin) and peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) were decreased, while myostatin (Mstn), phosphorylated extracellular regulated kinase (p-Erk1/2), and p-Smad3 expressions were upregulated in skeletal muscles from cigarette smoke-exposed mice and in cigarette smoke extract (CSE)-stimulated C2C12 myotubes. Treatment with Smad3 or Erk1/2 inhibitors partially restored the expression of Fndc5 in CSE-stimulated C2C12 myotubes. Taken together, CSE exposure, by upregulation of p-Erk1/2, promoted the expression of Mstn, which further inhibited Fndc5 expression by the p-Smad3/PGC-1α pathway, revealing a novel regulating mechanism of myokines in the pathogenesis of skeletal muscle comorbidities of COPD.

The role of Th17 cells: explanation of relationship between periodontitis and COPD?

Periodontitis and chronic obstructive pulmonary disease (COPD) are chronic inflammatory diseases with common risk factors, such as long-term smoking, age, and social deprivation. Many observational studies have shown that periodontitis and COPD are correlated. Moreover, they share a common pathophysiological process involving local accumulation of inflammatory cells and cytokines and damage of soft tissues. The T helper 17 (Th17) cells and the related cytokines, interleukin (IL)-17, IL-22, IL-1β, IL-6, IL-23, and transforming growth factor (TGF)-β, play a crucial regulatory role during the pathophysiological process. This paper reviewed the essential roles of Th17 lineage in the occurrence of periodontitis and COPD. The gaps in the study of their common pathological mechanism were also evaluated to explore future research directions. Therefore, this review can provide study direction for the association between periodontitis and COPD and new ideas for the clinical diagnosis and treatment of the two diseases.

Transient Receptor Potential Cation Channel Subfamily V Member 4 Mediates Pyroptosis in Chronic Obstructive Pulmonary Disease

TRPV4, a calcium permeable cation selective channel, was found to be involved in chronic obstructive pulmonary disease (COPD) through releasing ATP and IL-1β. Pyroptosis, a newly discovered pro-inflammatory cell death, was induced by cigarette smoke (CS) in airway epithelial cells (AECs). More recent studies indicated that blocking Ca²⁺ influx effectively inhibited pyroptosis. Therefore, we asked whether TRPV4 mediated CS-induced pyroptosis of AECs and hence participated in the pathogenesis of COPD. We found that pyroptosis and TRPV4 were upregulated in AECs from patients with COPD and long-term CS-exposed mice. Moreover, pharmacological inhibition or knockdown of TRPV4 function alleviated CS extract (CSE)-induced pyroptosis by inhibiting NACHT, LRP, PYD domains-containing protein 3 (NLRP3) inflammasome/activated caspase-1/gasdermin D pathway, decreasing the number of PI positive cells and lactate dehydrogenase (LDH) release, decreasing the expression of pro- inflammatory interleukin gene (IL)-1β, IL-8, and IL-18 expression, as well as increasing anti-inflammatory gene expression [NAD(P)H quinone dehydrogenase 1 (NQO1), superoxide dismutase 2 (mitochondrial) (MNSOD), and catalase, (CAT)]. Moreover, pharmacological inhibition or knockdown of TRPV4 function significantly relieved CSE-induced mitochondrial damage including decreased mitochondrial membrane potential, mitochondrial fusion protein (OPA1, MFN2) expression, and increased mitochondrial fission protein (DRP1, MFF) expression. Taken together, these findings indicate that TRPV4 mediates AEC pyroptosis via NLRP3/caspase-1/GSDMD pathway in COPD.