Cigarette smoke extract alters genome-wide profiles of circular RNAs and mRNAs in primary human small airway epithelial cells

Circular RNAs in human diseases

Circular RNAs (circRNAs) are a unique class of RNA molecules formed through back-splicing rather than linear splicing. As an emerging field in molecular biology, circRNAs have garnered significant attention due to their distinct structure and potential functional implications. A comprehensive understanding of circRNAs' functions and potential clinical applications remains elusive despite accumulating evidence of their involvement in disease pathogenesis. Recent research highlights their significant roles in various human diseases, but comprehensive reviews on their functions and applications remain scarce. This review provides an in-depth examination of circRNAs, focusing first on their involvement in non-neoplastic diseases such as respiratory, endocrine, metabolic, musculoskeletal, cardiovascular, and renal disorders. We then explore their roles in tumors, with particular emphasis on exosomal circular RNAs, which are crucial for cancer initiation, progression, and resistance to treatment. By detailing their biogenesis, functions, and impact on disease mechanisms, this review underscores the potential of circRNAs as diagnostic biomarkers and therapeutic targets. The review not only enhances our understanding of circRNAs' roles in specific diseases and tumor types but also highlights their potential as novel diagnostic and therapeutic tools, thereby paving the way for future clinical investigations and potential therapeutic interventions.

CircRNA-associated ceRNA networks (circCeNETs) in chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD), a chronic airway disorder, which is mostly brought on by cigarette smoke extract (CSE), is a leading cause of death which has a high frequency. In COPD patients, smoking cigarette could also trigger the epithelial-mesenchymal transition (EMT) of airway remodeling. One of the most significant elements of environmental contaminants that is linked to pulmonary damage is fine particulate matter (PM2.5). However, the basic processes of lung injury brought on by environmental contaminants and cigarette smoke are poorly understood, particularly the molecular pathways involved in inflammation. For the clinical management of COPD, investigating the molecular process and identifying workable biomarkers will be important. According to newly available research, circular RNAs (circRNAs) are aberrantly produced and serve as important regulators in the pathological processes of COPD. This class of non-coding RNAs (ncRNAs) functions as microRNA (miRNA) sponges to control the levels of gene expression, changing cellular phenotypes and advancing disease. These findings led us to concentrate our attention in this review on new studies about the regulatory mechanism and potential roles of circRNA-associated ceRNA networks (circCeNETs) in COPD.

Construction of a ceRNA network and screening of potential biomarkers and molecular targets in male smokers with chronic obstructive pulmonary disease

Background

Circular RNAs (circRNAs) play an important role in the occurrence and development of diseases. However, the role of circRNAs in male smokers with chronic obstructive pulmonary disease (COPD) remains unclear.

Methods

Stable COPD patients and healthy controls were recruited. Peripheral blood mononuclear cells (PBMCs) were extracted. After high-throughput RNA sequencing (RNA-Seq) of PBMCs, a bioinformatics method was used to analyse differentially expressed (DE) circRNAs (DEcircRNAs) and mRNAs (DEmRNAs).

Results

Total of 114 DEcircRNAs and 58 DEmRNAs were identified. Functional enrichment analysis showed that processes related to COPD include the regulation of interleukin (IL)-18, IL-5 and the NLRP3 inflammasome; differentiation of T helper type 1 (Th1), Th2, and Th17 cells, and the AMPK, Wnt, JAK-STAT, and PI3K-Akt signalling pathways. In the protein-protein interaction (PPI) network, the core genes were MYO16, MYL4, SCN4A, NRCAM, HMCN1, MYOM2, and IQSEC3. Small-molecule prediction results revealed potential drugs for the COPD treatment. Additionally, the circRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) regulatory network was constructed.

Conclusion

This study identified a set of dysregulated circRNAs and mRNAs and revealed potentially important genes, pathways, new small-molecule drugs and ceRNA regulatory networks in male smokers with COPD. These circRNAs might be prospective biomarkers or potential molecular targets of the ceRNA mechanism for COPD.

Unwinding circular RNA's role in inflammatory pulmonary diseases

Circular RNAs (circRNAs) have emerged as pivotal regulators of gene expression and cellular processes in various physiological and pathological conditions. In recent years, there has been a growing interest in investigating the role of circRNAs in inflammatory lung diseases, owing to their potential to modulate inflammation-associated pathways and contribute to disease pathogenesis. Inflammatory lung diseases, like asthma, chronic obstructive pulmonary disease (COPD), and COVID-19, pose significant global health challenges. The dysregulation of inflammatory responses demonstrates a pivotal function in advancing these diseases. CircRNAs have been identified as important players in regulating inflammation by functioning as miRNA sponges, engaging with RNA-binding proteins, and participating in intricate ceRNA networks. These interactions enable circRNAs to regulate the manifestation of key inflammatory genes and signaling pathways. Furthermore, emerging evidence suggests that specific circRNAs are differentially expressed in response to inflammatory stimuli and exhibit distinct patterns in various lung diseases. Their involvement in immune cell activation, cytokine production, and tissue remodeling processes underscores their possible capabilities as therapeutic targets and diagnostic biomarkers. Harnessing the knowledge of circRNA-mediated regulation in inflammatory lung diseases could lead to the development of innovative strategies for disease management and intervention. This review summarizes the current understanding of the role of circRNAs in inflammatory lung diseases, focusing on their regulatory mechanisms and functional implications.

Circular RNA Expression of Peripheral Blood Mononuclear Cells Associated with Risk of Acute Exacerbation in Smoking Chronic Obstructive Pulmonary Disease

Purpose

Circular RNAs (circRNAs) are newly identified endogenous non-coding RNAs that function as crucial gene modulators in the development of several diseases. By assessing the expression levels of circRNAs in peripheral blood mononuclear cells (PBMCs) from patients with chronic obstructive pulmonary disease (COPD), this study attempted to find new biomarkers for COPD screening.

Patients and Methods

We confirmed altered circRNA expression in PBMCs of COPD (n=41) vs controls (n=29). Further analysis focused on the highest and lowest circRNA expression levels. The T-test is used to assess the statistical variances in circRNAs among COPD patients in the smoking and non-smoking cohorts. Additionally, among smokers, the Spearman correlation test assesses the association between circRNAs and clinical indicators.

Results

Two circRNAs, hsa_circ_0042590 and hsa_circ_0049875, that were highly upregulated and downregulated in PBMCs from COPD patients were identified and verified. Smokers with COPD had lower hsa_circ_0042590 and higher hsa_circ_0049875, in comparison to non-smokers. There was a significant correlation (r=0.52, P<0.01) between the number of acute exacerbations (AEs) that smokers with COPD experienced in the previous year and the following year (r=0.67, P<0.001). Moreover, hsa_circ_0049875 was connected to the quantity of AEs in the year prior (r=0.68, P<0.0001) as well as the year after (r=0.72, P<0.0001). AUC: 0.79, 95% CI: 0.1210-0.3209, P<0.0001) for hsa_circ_0049875 showed a strong diagnostic value for COPD, according to ROC curve analysis. Hsa_circ_0042590 showed a close second with an AUC of 0.83 and 95% CI: -0.1972--0.0739 (P <0.0001).

Conclusion

This research identified a strong correlation between smoking and hsa_circ_0049875 and hsa_circ_0042590 in COPD PBMCs. The number of AEs in the preceding and succeeding years was substantially linked with the existence of hsa_circ_0042590 and hsa_circ_0049875 in COPD patients who smoke. Additionally, according to our research, hsa_circ_0049875 and hsa_circ_0042590 may be valuable biomarkers for COPD diagnosis.

Hsa_circ_0008833 promotes COPD progression via inducing pyroptosis in bronchial epithelial cells

Purpose: Chronic obstructive pulmonary disease (COPD) is a common respiratory disorder. Pyroptosis represents a distinctive form of inflammatory cell death that is mediated through the activation of Caspase-1 and inflammasomes. CircRNAs have emerged as a novel class of biomolecules with implications in various human diseases. This study aims to investigate the circRNAs profile of in COPD progression and identify pivotal circRNAs associated with the development of this disease. Methods: he expression profiles of circRNAs in peripheral blood mononuclear cells of COPD patients were assessed by circRNA microarray. Furthermore, flag-labeled vectors were constructed to assess the potential protein-coding capacity of has-circ-0008833. 16HBE cells were stably transfected with lentivirus approach, and cell proliferation and death were assessed to clarify the functional roles of has-circ-0008833 and its encoded protein circ-0008833aa. Additionally, western blot analysis was furthered performed to determine the level of Caspase-1, IL-18, IL-1β, NLRP3, ASC, and cleaved GSDMD regulated by has-circ-0008833 and circ-0008833-57aa. Results: Initially, we screened the expression profiles of human circRNAs in peripheral blood mononuclear cells of COPD patients, and found that has-circ-0008833 exhibited a significant increase in COPD mononuclear cells. Subsequently, we demonstrated that has-circ-0008833 carried an open reading frame (ORF), which encoded a functional protein, referred to as circ-0008833-57aa. By employing gain-of-function approaches, our results suggested that both circ-0008833 and circ-0008833-57aa inhibited proliferation, but accelerated the rate of 16HBE cell death. Finally, we discovered that circ-0008833 and circ-0008833-57aa promoted the expression of Caspase-1, IL-18, IL-1β, NLRP3, ASC, and cleaved GSDMD in 16HBE cells. Conclusions: Upregulation of circ-0008833 might promote COPD progression by inducing pyroptosis of bronchial epithelial cells through the encoding of a 57-amino acid peptide.

Circular RNAs: emerging players in asthma and COPD

Circular RNAs (circRNAs) belong to a unique class of endogenously expressed non-protein-coding RNAs with a distinct circularized structure, characterized by the absence of 5'-cap and 3'-polyadenylate ends. They are generally formed through back-splicing from pre-mRNAs. They serve as regulators of transcription and splicing, and act as sponges for microRNAs (miRNAs) and RNA-binding proteins, thereby modulating the expression of target genes. As a result, they exert a substantial impact on a diverse array of cellular and biological processes, including cell proliferation, migration, inflammation, and oxidative stress. Asthma and COPD are chronic airway conditions that currently have no cure. In recent years, emerging evidence suggests that altered expression of circRNAs in airway, bronchial and immune cells is involved in asthma and COPD pathogenesis. Studies exploring circRNA dysregulation in asthma have showcased their involvement in regulating the proliferation, migration, and inflammation of airway smooth muscle and bronchial epithelial cells, as well as impacting goblet cell metaplasia, Th2 cell differentiation, and macrophage activation, primarily through interactions with miRNAs. Similarly, in COPD, circRNAs have shown altered expression patterns in the blood and lungs of patients, and these changes have been linked to modulating inflammation, oxidative stress, and airway remodeling in preclinical models. Furthermore, certain circRNAs have demonstrated promising potential as diagnostic and prognostic biomarkers for both asthma and COPD. This review delves into the current understanding of the function and molecular mechanisms of circRNAs in asthma and COPD, along with exploring their potential as biomarkers in these respiratory conditions.

Comprehensive Analysis of a Competing Endogenous RNA Co-Expression Network in Chronic Obstructive Pulmonary Disease

Purpose

Chronic obstructive pulmonary disease (COPD) is the main cause of mortality world widely. Non-coding RNAs (lncRNAs) and associated competitive endogenous RNAs (ceRNAs) networks were recently proved to lead to mRNA gene expression downregulation but were still unclear in COPD. This study aims to investigate and elucidate the mechanisms underlying the involvement of ceRNA co-expression networks in COPD pathogenesis.

Methods

Obtained expression signature of data from the Gene Expression Omnibus database and compared the differentially expression of mRNAs and miRNAs between COPD patients and healthy smokers. Predicted the miRNA-lncRNA and miRNA-mRNA interaction using online library and employed CIBERSORT to measure the proportions of the 22 immune cells in the COPD and control groups.

Results

Established a ceRNA-network comprising 11 lncRNAs, 5 miRNAs, and 16 mRNAs. Using the weighted correlation network analysis method, we identified hub genes and hub miRNAs and obtained one core sub-network, XIST, FGD5-AS1, KCNQ1OT1, HOXA11-AS, LINC00667, H19, PRKCQ-AS1, NUTM2A-AS1/has-mir-454-3p/ZNF678, PRRG4. COPD patients had different proportions of immune cells than controls, and these variations were associated with the magnitude of pulmonary function parameters.

Conclusion

The ceRNA-network, particularly the core sub-network, may be a putative goal for COPD, in which specific immune cells were involved.

Identification of circRNA-associated ceRNA networks in peripheral blood mononuclear cells as potential biomarkers for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), which is a common respiratory disorder with high morbidity and mortality globally, has a complex pathogenesis that is not fully understood. Some circular RNAs (circRNAs) have been recognized to serve as miRNA sponges for regulating target RNA transcripts during the processes of human diseases. In the present study, we aimed to investigate novel circRNA-associated biomarkers for COPD, 245 differentially expressed circRNAs were identified, including 111 up-regulated and 134 down-regulated circRNAs. These candidate circRNAs were enriched in inflammation-associated pathways (such as mTOR, B-cell receptor, and NF-κB signaling pathways) via Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. A combination of two circRNAs (up-regulated hsa_circ_0067209 and down-regulated hsa_circ_0000673) demonstrated good diagnostic value (area under the receiver operating characteristic curve [AUC] = 0.866) for COPD by receiver operating characteristic curve (ROC) analysis and qRT-PCR validation. Subsequently, hsa-miR-8082 and hsa-miR-1248 were identified as targets for hsa_circ_0067209 and hsa_circ_0000673, respectively, via bioinformatics analysis and a dual-luciferase reporter assay, and the combination of these two miRNAs displayed better diagnosis potential for COPD (AUC = 0.967) than each other. Evaluation of COPD-related mRNA profiles revealed that the up-regulated genes ABR and TRPM6 were predicted downstream targets for hsa_circ_0067209/hsa-miR-8082, whereas the down-regulated gene RORC was a predicted downstream target for hsa_circ_0000673/hsa-miR-1248. In summary, hsa_circ_0067209 and hsa_circ_0000673 have potential as novel diagnostic biomarkers of COPD. In addition, competing endogenous RNA networks of hsa_circ_0067209/hsa-miR-8082/ABR/TRPM6 and hsa_circ_0000673/hsa-miR-1248/RORC may play critical regulation roles for COPD pathogenesis.

CircRNA_0026344 via miR-21 is involved in cigarette smoke-induced autophagy and apoptosis of alveolar epithelial cells in emphysema

Cigarette smoke (CS), a main source of indoor air pollution, is a primary risk factor for emphysema, and aberrant cellular autophagy is related to the pathogenesis of emphysema. Circular RNAs (circRNAs) affect the expression of mRNAs via acting as microRNA (miRNA) sponges, but their role in emphysema progression is not established. In the present investigation, CS, acting on alveolar epithelial cells, caused higher levels of miR-21, p-ERK, and cleaved-caspase 3 and led to lower levels of circRNA_0026344 and PTEN, which induced autophagy and apoptosis. miR-21 suppressed the expression of PTEN, which was involved in the regulation of autophagy and apoptosis. Further, in alveolar epithelial cells, overexpression of circRNA_0026344 blocked cigarette smoke extract (CSE)-induced autophagy and apoptosis, but this blockage was reversed by upregulation of miR-21 with a mimic. These results demonstrated that, in alveolar epithelial cells, CS decreases circRNA_0026344 levels, which sponge miR-21 to inhibit the miR-21 target, PTEN, which, in turn, activates ERK and thereby promotes autophagy and apoptosis, leading to emphysema. Thus, for emphysema, circRNA_0026344 regulates the PTEN/ERK axis by sponging miR-21, which is associated with the CS-induced autophagy and apoptosis of alveolar epithelial cells. In sum, the present investigation identifies a novel mechanism for CS-induced emphysema and provides information useful for the diagnosis and treatment of CS-induced emphysema.

Prediction of COPD acute exacerbation in response to air pollution using exosomal circRNA profile and Machine learning

Ambient fine particulate matter (PM2.5) is linked to an increased risk of chronic obstructive pulmonary disease (COPD) exacerbations, which significantly increase the risk of mortality in COPD patients. Identifying the subtype of COPD patients who are sensitive to environmental aggressions is necessary. Using in vitro and in vivo PM2.5 exposure models, we demonstrate that exosomal hsa_circ_0005045 is upregulated by PM2.5 and binds to the protein cargo peroxiredoxin2, which functionally aggravates hallmarks of COPD by recruiting neutrophil elastase and triggering in situ release of tumor necrosis factor (TNF)-α by inflammatory cells. The biological function of hsa_circ_0005045 associated with aggravation of COPD is validated using exosome-transplantation and conditional circRNA-knockdown murine models. By sorting the major components of PM2.5, we find that PM2.5-bound heavy metals, which are distinguishable from the components of cigarette smoke, trigger the elevation of exosomal hsa_circ_0005045. Finally, using machine learning models in a cohort with 327 COPD patients, the PM2.5 exposure-sensitive COPD patients are characterized by relatively high hsa_circ_0005045 expression, non-smoking, and group C (mMRC 0-1 (or CAT < 10) and ≥ 2 exacerbations (or ≥ 1 exacerbation leading to hospital admission) in the past year). Thus, our results suggest that environmental reduction in PM2.5 emission provides a targeted approach to protecting non-smoking COPD patients against air pollution-related disease exacerbation.

Circ_0040929 Serves as Promising Biomarker and Potential Target for Chronic Obstructive Pulmonary Disease

Background

Circular RNAs (circRNAs) can act as essential regulators in many diseases, including chronic obstructive pulmonary disease (COPD). We aimed to explore the role and underlying mechanism of circ_0040929 in COPD.

Methods

A cellular model of COPD was constructed by treating human bronchial epithelial cells (16HBE) with cigarette smoke extract (CSE). The levels of circ_0040929, microRNA-515-5p (miR-515-5p) and insulin-like growth factor-binding protein 3 (IGFBP3) were measured by quantitative real-time PCR. Cell proliferation was assessed by Cell Counting Kit-8 and 5-ethynyl-2'-deoxyuridine assays. Cell apoptosis was evaluated by flow cytometry. Protein expression was measured using Western blot assay. The levels of inflammatory factors and airway remodeling were assayed via enzyme-linked immunosorbent assay. The interaction between miR-515-5p and circ_0040929/IGFBP3 was confirmed by dual-luciferase reporter, RNA pull-down and RNA immunoprecipitation assays. Exosomes were detected using transmission electron microscopy.

Results

Circ_0040929 expression and IGFBP3 expression were upregulated in the serum of smokers (n = 22) compared to non-smokers (n = 22) and more significantly upregulated in the serum of COPD patients (n = 22). However, miR-515-5p expression was decreased in the serum of smokers compared to non-smokers and further reduced in the serum of COPD. Circ_0040929 knockdown attenuated CSE-induced cell injury by increasing proliferation and reducing apoptosis, inflammation, and airway remodeling in 16HBE cells. MiR-515-5p was a direct target of circ_0040929, and miR-515-5p inhibition reversed the effect of circ_0040929 knockdown in CSE-treated 16HBE cells. IGFBP3 was a direct target of miR-515-5p, and miR-515-5p overexpression alleviated CSE-induced cell injury via targeting IGFBP3. Moreover, circ_0040929 regulated IGFBP3 expression by targeting miR-515-5p. Importantly, circ_0040929 was upregulated in serum exosomes from COPD patients.

Conclusion

Circ_0040929 played a promoting role in CSE-induced COPD by regulating miR-515-5p/IGFBP3 axis, suggesting that it might be a novel potential target for COPD treatment.

Suppression of circXPO1 attenuates cigarette smoke-induced inflammation and cellular senescence of alveolar epithelial cells in chronic obstructive pulmonary disease

Smoking is an essential facet of the pathogenesis of chronic obstructive pulmonary disease (COPD), which is typically characterized by inflammation and cellular senescence of alveolar epithelial cells. In this study, we investigated the function and fundamental mechanism of a novel circular RNA XPO1 (circXPO1) in cigarette smoke (CS)-induced inflammation and cellular senescence of alveolar epithelial cells. We found that circXPO1 was overexpressed in the lungs of CS-exposed mice and the CS extract (CSE)-treated alveolar epithelial cell line MLE12. Suppression of circXPO1 inhibited CSE-induced inflammatory cytokine production and cellular senescence. In vivo assays also demonstrated that circXPO1 knockdown attenuates CS-induced inflammation and senescence in the mouse lungs. Mechanistically, circXPO1 can directly bind to miR-23b-3p, preventing miR-23b-3p from binding to its target TGF-β-activated kinase 1/MAP3K7 binding protein 3 (TAB3)mRNA. In addition, under CSE conditions, miR-23b-3p overexpression recapitulated the prophylactic effects of circXPO1 knockdown. Inhibition of miR-23b-3p attenuated the function of circXPO1 knockdown in CSE-treated MLE12 cells. These results reveal that circXPO1 plays a role in the pathogenesis of COPD by modulating TAB3 through sponging miR-23b-3p.

CircRNA circ_0006892 regulates miR-24/PHLPP2 axis to mitigate cigarette smoke extract-induced bronchial epithelial cell injury

Chronic obstructive pulmonary disease (COPD) is a chronic airway disorder mainly resulted from cigarette smoke exposure. The dysregulated circular RNAs (circRNAs) are relevant to the pathogenesis of COPD. This study aims to explore the function and mechanism of circRNA hsa_circ_0006892 (circ_0006892) in cigarette smoke extract (CSE)-induced bronchial epithelial injury. The lung tissues were collected from 17 nonsmokers and 23 smokers with COPD. The bronchial epithelial cells (BEAS-2B and 16HBE) were stimulated via CSE. Circ_0006892, microRNA-24 (miR-24), and PH domain and leucine-rich repeat protein phosphatase 2 (PHLPP2) abundances were examined via a quantitative reverse transcription polymerase chain reaction or Western blot. Cell viability, apoptosis, and inflammatory response were assessed via cell counting kit-8 (CCK-8), flow cytometry, and enzyme-linked immunosorbent assay (ELISA). The target relationship of miR-24 and circ_0006892 or PHLPP2 was tested via dual-luciferase reporter analysis, RNA immunoprecipitation, and RNA pull-down. Circ_0006892 expression was reduced in lung tissues of smokers with COPD and CSE-stimulated bronchial epithelial cells. Circ_0006892 overexpression alleviated CSE-induced viability reduction and promotion of apoptosis and inflammatory response. MiR-24 was bound via circ_0006892, and miR-24 overexpression reversed the effect of circ_0006892 on CSE-induced injury. PHLPP2 was targeted via miR-24, and miR-24 knockdown mitigated CSE-induced viability reduction and promotion of apoptosis and inflammatory response via regulating PHLPP2. Circ_0006892 could promote PHLPP2 expression via regulating miR-24. Circ_0006892 attenuated CSE-induced bronchial epithelial cell apoptosis and inflammatory response via regulating miR-24/PHLPP2 axis.

Method of Preparation of Cigarette Smoke Extract to Assess Lung Cancer-Associated Changes in Airway Epithelial Cells

Smoking tobacco is a major risk factor for the development of lung cancer, COPD, and other lung pathologies in smokers. Cigarette smoke (CS), which is comprised of several toxic components, is known to cause oxidative stress and inflammation-induced lung damage. Since airway epithelial cells act as the primary barrier, they protect the lung tissues from environmental insults, including CS. Upon exposure to these insults, airway epithelial cells act as the initial site of injury and orchestrate the pathophysiology of lung cancer. Scientists have been using cigarette smoke extract (CSE) in the preclinical model of in vitro cell culture to understand the effect of CS on the cellular, biochemical, and molecular changes in the lung epithelial cells. However, the standard procedure to prepare the CSE in the laboratory with a low-cost assembly and obtaining a reproducible quality of CSE in different batches is a challenge. Here, in this chapter, we delineate the method for the preparation of CSE using a discontinuous puff-based system which is an economical and reproducible method to prepare CSE in the laboratory. This method is suitable for studying CSE-induced molecular changes in lung diseases, including lung cancer, using in vitro models of lung adenocarcinoma cells.

Knockdown of circFOXO3 ameliorates cigarette smoke-induced lung injury in mice

Background

Chronic obstructive pulmonary disease (COPD) remains a prevalent chronic airway inflammatory disease. Circular RNAs (circRNAs) are associated with inflammation regulation; therefore, we examined distinct effects of circRNA FOXO3 (circFOXO3) against pneumonic inflammatory processes in COPD.

Methods

We first quantified and localized circFOXO3 in mouse lung epithelial cell line MLE12 by quantitative reverse-transcription PCR and in situ hybridization. Next, circFOXO3 was suppressed by therapeutic administration of circFOXO3 knockdown lentivirus in mice exposed to air or cigarette smoke (CS) for 12 weeks, and several hallmarks of COPD were evaluated.

Results

We noticed that circFOXO3 is upregulated in CS-exposed lungs and cigarette smoke extract (CSE)-treated murine alveolar epithelial cells. Knockdown of circFOXO3 attenuated the release of CXCL1 and IL-6 as well as inflammatory processes in the lungs of CS-exposed mice. In addition, we identified miR-214-3p as a circFOXO3-targeted microRNA. MiR-214-3p overexpression exerted protective effects against pneumonic inflammation after CS exposure. Silencing of circFOXO3 downregulated IKK-β mRNA (miR-214-3p’s target), resulting in the dysfunction of the NF-κB signaling pathway and attenuation of CSE-induced inflammatory-cytokine expression.

Conclusions

Collectively, these findings reveal a crucial function of circFOXO3 in the pathological remodeling related to CS-induced inflammatory processes. Hence, circFOXO3 might be a good target for the treatment of inflammatory disorders similar to CS-induced lung inflammation.

Identifying a novel biological mechanism for alcohol addiction associated with circRNA networks acting as potential miRNA sponges

Our lab and others have shown that chronic alcohol use leads to gene and miRNA expression changes across the mesocorticolimbic (MCL) system. Circular RNAs (circRNAs) are noncoding RNAs that form closed-loop structures and are reported to alter gene expression through miRNA sequestration, thus providing a potentially novel neurobiological mechanism for the development of alcohol dependence (AD). Genome-wide expression of circRNA was assessed in the nucleus accumbens (NAc) from 32 AD-matched cases/controls. Significant circRNAs (unadj. p ≤ 0.05) were identified via regression and clustered in circRNA networks via weighted gene co-expression network analysis (WGCNA). CircRNA interactions with previously generated mRNA and miRNA were detected via correlation and bioinformatic analyses. Significant circRNAs (N = 542) clustered in nine significant AD modules (FWER p ≤ 0.05), within which we identified 137 circRNA hubs. We detected 23 significant circRNA-miRNA-mRNA interactions (FDR ≤ 0.10). Among these, circRNA-406742 and miR-1200 significantly interact with the highest number of mRNA, including genes associated with neuronal functioning and alcohol addiction (HRAS, PRKCB, HOMER1, and PCLO). Finally, we integrate genotypic information that revealed 96 significant circRNA expression quantitative trait loci (eQTLs) (unadj. p ≤ 0.002) that showed significant enrichment within recent alcohol use disorder (AUD) and smoking genome-wide association study (GWAS). To our knowledge, this is the first study to examine the role of circRNA in the neuropathology of AD. We show that circRNAs impact mRNA expression by interacting with miRNA in the NAc of AD subjects. More importantly, we provide indirect evidence for the clinical importance of circRNA in the development of AUD by detecting a significant enrichment of our circRNA eQTLs among GWAS of substance abuse.

The impact of tobacco exposure on tumor microenvironment and prognosis in lung adenocarcinoma by integrative analysis of multi-omics data

BACKGROUND

Immune checkpoint inhibitors (ICIs) are standard therapies for patients with advanced lung adenocarcinoma and significantly improve treatment outcomes. The effect of tobacco smoking on the response of immune checkpoint inhibitors is somewhat diverging. Here, we assessed the impact of tobacco exposure on the tumor microenvironment and developed a feasible tool for predicting prognosis.

METHODS

Whole exon sequence data and the corresponding clinical information were downloaded from the Cancer Genome Atlas. The signature was developed by the Random Forest algorithm. CIBERSORTx online tool was used to estimate immune infiltration. Functional assays were performed to assess the roles of tobacco exposure in cancer cells. Immunohistochemistry (IHC) was performed to identify and validate the immune activation status.

RESULTS

The TMB of lifelong non-smoker, current reformed smoker for over 15 years, current reformed smoker<15 years and current smoker had a significantly increasing trend in LUAD patients. In vitro tobacco exposure promoted the expression of PD-L1 and malignant phenotype of LUAD cells. In addition, patients with high Random Forest score (RFscore) had a poorer prognosis than those with low RFscore. The ROC curve analysis of RFscore revealed a promising prognostic capability. Memory activated CD4 + T cells, CD8 + t cells and memory B cells were noticeably enriched in the high RFscore group and PDCD1 appreciably upregulated in the high RFscore group as well. Furthermore, IHC results suggested that patients with high RFscore remained an immune activation status, indicating a positive correlation between RFscore and patient's immune status.

CONCLUSION

Our analysis provides further insight into the profound impacts of tobacco exposure on tumor immune microenvironment and envisions integrative predictive models of RFscore, predicting the prognosis of smoking lung adenocarcinoma, which might help to understand the potential mechanism of smoking exposure on tumor immune microenvironment.

Circ-RBMS1 Knockdown Alleviates CSE-Induced Apoptosis, Inflammation and Oxidative Stress via Up-Regulating FBXO11 Through miR-197-3p in 16HBE Cells

Background

Emerging evidence has reported that circular RNAs (circRNAs) are aberrantly expressed and act as significant regulators in pathological processes of chronic obstructive pulmonary disease (COPD). Here, the purpose of this article was to evaluate and clarify the biological functions and mechanism of circRNA single stranded interacting protein 1 (circ-RBMS1) in cigarette smoke (CS)-induced COPD.

Methods

Human bronchial epithelial cells 16HBE treated with or without cigarette smoke extract (CSE) were used in the experimental group in vitro. Levels of circ-RBMS1, microRNA (miR)-197-3p, and F-box only protein 11 (FBXO11) were detected using quantitative real-time polymerase chain reaction and Western blot. The present study used cell counting kit-8 (CCK-8), 5-ethynyl-2ʹ-deoxyuridine (EDU), flow cytometry and Western blot assays to determine the survival of 16HBE cells. The activity of interleukin (IL)-1β, tumor necrosis factor (TNF-α), malondialdehyde (MDA) and superoxide dismutase (SOD) was evaluated using the relative commercial kits. Dual-luciferase activity and RIP assays were used to identify the target relationship between miR-197-3p and circ-RBMS1 or FBXO11.

Results

Circ-RBMS1 was highly expressed in COPD patients, and CSE induced an increased expression of circ-RBMS1 in a dose-dependent manner. Functionally, knockdown of circ-RBMS1 attenuated CSE-induced apoptosis, inflammation and oxidative stress in 16HBE cells. Circ-RBMS1 directly targeted miR-197-3p, and miR-197-3p inhibition reversed the effects of circ-RBMS1 knockdown on CSE-induced 16HBE cells. FBXO11 was a target of miR-197-3p. MiR-197-3p overexpression or FBXO11 silencing reduced the apoptosis, inflammation and oxidative stress in CSE-induced 16HBE cells. Moreover, miR-197-3p exerted its effects by targeting FBXO11. Additionally, circ-RBMS1 acted as a sponge for miR-197-3p to positively regulate FBXO11 expression in 16HBE cells.

Conclusion

Circ-RBMS1 knockdown alleviated CSE-induced apoptosis, inflammation and oxidative stress in 16HBE cells via miR-197-3p/FBXO11 axis, suggesting a new insight into the pathogenesis of CS-induced COPD.

Cigarette Smoke Underlies the Pathogenesis of Palmoplantar Pustulosis via an IL-17A-Induced Production of IL-36γ in Tonsillar Epithelial Cells

Palmoplantar pustulosis (PPP) is characterized by sterile pustules on the palms and soles. A strong association between PPP and tobacco smoking has been reported, and it has been speculated that the IL-17A pathway may play an important role in PPP. Recent studies have suggested that IL-36 plays a pivotal role in the pathogenesis of psoriasis and its subtypes. The relationships among IL-36, smoking, and PPP have not been examined. Here, we investigated the relationships among the smoking index, severity of the clinical condition of PPP, and in vitro dynamics of IL-36 in human tonsillar epithelial cells under the condition of exposure to a cigarette smoke extract. The results demonstrated that the Palmoplantar Pustulosis Area and Severity Index was strongly and positively correlated with the smoking index in female patients. Immunohistochemical examinations showed that IL-36γ was highly expressed in tonsillar epithelial cells from patients with PPP but not in those from patients with recurrent tonsillitis without PPP. The in vitro study revealed that IL-17A synergistically induced a release of IL-36γ under cigarette smoke extract exposure. These results suggest that local production of IL-36γ by epithelial cells induced by cigarette smoke exposure plays an important role in the pathogenesis of PPP.

Circ-HACE1 Aggravates Cigarette Smoke Extract-Induced Injury in Human Bronchial Epithelial Cells via Regulating Toll-Like Receptor 4 by Sponging miR-485-3p

Background

Smoking is the most common cause of chronic obstructive pulmonary disease (COPD), and the early diagnosis for COPD remains poor. Exploring the molecular mechanism and finding feasible biomarkers will be beneficial for clinical management of COPD. Circular RNAs (circRNAs) are noncoding RNAs that act as miRNA sponges to regulate the expression levels of genes, leading to the changes of cellular phenotypes and disease progression. CircRNA HECT domain and ankyrin repeat containing E3 ubiquitin protein ligase 1 (circ-HACE1) was abnormally expressed after the induction of cigarette smoke extract (CSE) in cell model. This study was performed to explore its function and mechanism in COPD.

Methods

Circ-HACE1, microRNA-485-3p (miR-485-3p) and toll-like receptor 4 (TLR4) detection was performed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability and apoptosis/cell cycle were respectively examined using cell counting kit-8 (CCK-8) and flow cytometry. Inflammatory cytokines were determined by enzyme-linked immunosorbent assay (ELISA). Oxidative stress was evaluated through the measurement of malondialdehyde (MDA) and superoxide dismutase (SOD). The target binding analysis was conducted via dual-luciferase reporter assay. Western blot was employed for protein expression detection of TLR4.

Results

Circ-HACE1 was overexpressed in smokers or smokers with COPD and CSE upregulated circ-HACE1 expression in 16HBE cells. Knockdown of circ-HACE1 attenuated CSE-stimulated cell viability and cell cycle repression, as well as the enhancement of cell apoptosis, inflammatory response and oxidative stress. MiR-485-3p was a target of circ-HACE1. Circ-HACE1 regulated CSE-induced cell injury via targeting miR-485-3p. TLR4 was a downstream target of miR-485-3p, and miR-485-3p inhibited the CSE-induced cell damages by directly downregulating the level of TLR4. Circ-HACE1/miR-485-3p regulated TLR4 expression in CSE-treated 16HBE cells, and TLR4 overexpression also reversed all effects of si-circ-HACE1 on CSE-treated 16HBE cells.

Conclusion

These findings elucidated that circ-HACE1 contributed to the CSE-induced cell damages in COPD cell models via regulating TLR4 by acting as the sponge of miR-485-3p.

Circ-OSBPL2 Contributes to Smoke-Related Chronic Obstructive Pulmonary Disease by Targeting miR-193a-5p/BRD4 Axis

Background

Circular RNAs (circRNAs) have been identified to play roles in the respiratory diseases. Here, this study aimed to elucidate the function of circRNA oxysterol binding protein like 2 (circOSBPL2) in the development of smoke-related chronic obstructive pulmonary diseases (COPD).

Methods

The expression of circ-OSBPL2, microRNA (miR)-193a-5p, and bromodomain-containing protein 4 (BRD4) was detected using qRT-PCR and Western blot assays. Cigarette smoke extract (CSE)-induced human bronchial epithelial cells (HBECs) was applied to mimic smoke-related COPD in vitro. Flow cytometric analysis of cell apoptosis and ELISA analysis of interleukins (IL)-6, IL-8, tumor necrosis factor-α (TNF-α) levels were performed. The malondialdehyde (MDA) and superoxide dismutase (SOD) production levels were analyzed according to the kit instructions. The binding interaction between miR-193a-5p and circ-OSBPL2 or BRD4 was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation assays.

Results

Circ-OSBPL2 was highly expressed in lung tissues of smokers without or with COPD, particularly in smokers with COPD. Also, the expression of circ-OSBPL2 was dose and time-dependently elevated in CSE-induced HBECs. Circ-OSBPL2 down-regulation in HBECs attenuated CSE-evoked cell proliferation arrest, and cell apoptosis, inflammation and oxidative stress promotion. Mechanistically, circ-OSBPL2 served as a sponge for miR-193a-5p, and miR-193a-5p inhibition reversed the effects of circ-OSBPL2 knockdown on CSE-mediated HBECs. Besides that, miR-193a-5p directly targeted BRD4, and miR-193a-5p re-expression in HBECs abolished CSE-induced HBEC injury, which was reverted by BRD4 up-regulation. Additionally, we also found circ-OSBPL2 could indirectly regulate BRD4 via miR-193a-5p.

Conclusion

Circ-OSBPL2 contributed to the apoptosis, inflammation, and oxidative stress of HBECs in smoke-related COPD by miR-193a-5p/BRD4 axis, suggesting a novel insight on the pathogenesis of COPD and a potential therapeutic strategy for future clinic intervention in COPD.

Circular RNAs in Toxicology

Circular RNAs (circRNAs) are a type of closed, long, non-coding RNAs, which have attracted significant attention in recent years. CircRNAs exhibit unique functions and are characterized by stable expression in various tissues across different species. Because the identification of circRNA in plant viroids in 1976, numerous studies have been conducted to elucidate its generation as well as expression under normal and disease conditions. The rapid development of research focused on the roles of circRNAs as biomarkers in diseases such as cancers has led to increased interests in evaluating the effects of toxicants on the human genetics from a toxicological perspective. Notably, increasing amounts of chemicals are generated in the environment; however, their toxic features and interactions with the human body, particularly from the epigenetic viewpoint, remain largely unknown. Considering the unique features of circRNAs as potential prognostic biomarkers as well as their roles in evaluating health risks following exposure to toxicants, the aim of this review was to assess the latest progress in the research concerning circRNA, to address the role of the circRNA-miRNA-mRNA axis in diseases and processes occurring after exposure to toxic compounds. Another goal was to identify the gaps in understanding the interactions between toxic compounds and circRNAs as potential biomarkers. The review presents general information about circRNA (ie, biogenesis and functions) and provides insights into newly discovered exosome-contained circRNA. The roles of circRNAs as potential biomarkers are also explored. A comprehensive review of the available literature on the role of circRNA in toxicological research (ie, chemical carcinogenesis, respiratory toxicology, neurotoxicology, and other unclassified toxicological categories) is included.

Circ0061052 regulation of FoxC1/Snail pathway via miR-515-5p is involved in the epithelial-mesenchymal transition of epithelial cells during cigarette smoke-induced airway remodeling

Circular RNA (circRNA) has been shown to be widely involved in a variety of lung diseases. Cigarette smoke (CS) may induce epithelial-mesenchymal transition (EMT) of airway remodeling in chronic obstructive pulmonary disease (COPD), however, in which the roles and mechanisms of circRNA have not been elucidated. In this study, we aimed to determine whether circ0061052 is involved in the EMT of human bronchial epithelial (HBE) cells and its potential mechanism for playing a biological role. Cigarette smoke extract (CSE) caused elevated EMT indicators and the increases of circ0061052 in HBE cells. Circ0061052 has a ring structure and is mainly present in the cytoplasm of HBE cells. We analyzed the regulatory relationship between circ0061052 and miR-515-5p using bioinformatics, a luciferase reporter gene, and qRT-PCR. We found that circ0061052 is mainly distributed in the cytoplasm and competitively binds to miR-515-5p, acting as a sponge for miR-515-5p. The luciferase reporter gene showed that miR-515-5p binds to the 3'UTR region of FoxC1 mRNA to inhibit its transcription. For HBE cells, overexpression of miR-515-5p antagonized the CSE-induced EMT. In addition, circ0061052 acts by binding miR-515-5p competitively to regulate the expression of FoxC1/Snail. When circ0061052 siRNA and miR-515-5p inhibitor were co-transfected into HBE cells, the inhibitor reversed the effect of circ0061052 siRNA on reducing EMT. Chronic exposure of mice to CS induced increases of circ0061052 levels, decreases of miR-515-5p levels, and the EMT in lung tissue, which caused dysfunction and airway obstruction. Overall, the results show that, by regulating miR-515-5p through a FoxC1/Snail regulatory axis, circ0061052 is involved in the CS-induced EMT and airway remodeling in COPD.

CircRNA0001859, a new diagnostic and prognostic biomarkers for COPD and AECOPD

Background

Dysregulation of circRNAs has been reported to be functionally associated with chronic obstructive pulmonary disease (COPD). The present investigation elucidated the potential role of CircRNA0001859 in regulating chronic obstructive pulmonary disease acute (COPD) and Acute Exacerbation of COPD (AECOPD).

Methods

Mice model of COPD was established to screen and verify the dysregulated expression of CircRNA0001859. Fluorescence in situ hybridization (FISH) and quantitative real-time PCR (qRT-PCR) were carried out to detect the expression of CircRNA0001859. 38 stable COPD patients, 24 AECOPD patients, 57 COPD with lung cancer patients and 28 healthy person with age and sex matched to total patients were used for the present investigation.

Results

circRNA0001859 was downregulated in the lung tissue of mice after the three kinds of treatments (Cigarette smoke (CS)/NK alone or CS + NNK) for inducing COPD. FISH assay verified the downregulation of circRNA0001859 both in the mice lung and human bronchial epithelial cell of COPD model. Furthermore,, the level of circRNA0001859 was also downregulated in the peripheral blood of COPD and lung cancer patients. CircRNA0001859 might act as a diagnostic and prognostic biomarker for the treatment of in COPD and AECOPD with Are under the receiver operating characteristic curve (ROC curve) (AUC) of 0.7433 and 0.8717, respectively.

Conclusion

We explored a novel circRNA0001859, which might act as a potential therapeutic biomarker for the treatment of COPD and AECOPD.

Cigarette Smoke Extract induces H19 in Esophageal Squamous Cell Carcinoma in Smoking Patients: Based on A Chronic Exposed Cell Model

Cigarette smoking is a factor capable of inducing esophageal squamous cell carcinoma (ESCC). However, the biological pathways that are responsible for tumor development and are directly affected by cigarette smoking remain unknown. To explore the role of cigarette smoking in ESCC, we developed a long-term cigarette smoke extract (CSE) exposed cell model using the normal immortalized SHEE esophageal epithelial cell line, which would malignantly transform after long-term cultivation without carcinogens. CSE-exposed cells displayed higher malignancy and differently expressed several lncRNAs. Among them, H19, a lncRNA responsible for proliferation and invasion, was upregulated in CSE-exposed SHEE cells. In tumors from ESCC patients, H19 was significantly increased in smoking ESCC patients compared to non-smoking patients, and H19 was overexpressed and correlated with pathological tumor size in smokers. These results indicated that cigarette smoking lead to a different biological change from non-smoking induced ESCC and H19 related to cancer development during CSE-induced carcinogenesis.

Cooperative application of transcriptomics and ceRNA hypothesis: LncRNA-107052630/miR-205a/G0S2 crosstalk is involved in ammonia-induced intestinal apoptotic injury in chicken

Ammonia (NH₃), as a harmful gas from agricultural production, plays an important role in air pollution, such as haze. Although numerous researchers have paid attention to health damage through NH₃ inhalation, the exhaustive mechanism of NH₃ induced intestinal toxicity remains unclear. A genes crosstalk named competing endogenous RNAs (ceRNA) can explain many regulatory manners from the molecular perspective. However, few studies have attempted to interpret the injury mechanism of air pollutants to the organism via ceRNA theory. Here, we thoroughly investigated the lncRNA-associated-ceRNA mechanism in jejunum samples from a 42-days-old NH₃-exposed chicken model through deep RNA sequencing. We observed the occurrence of apoptosis in jejunum, obtained 46 significantly dysregulated lncRNAs and 30 dysregulated miRNAs, and then constructed lncRNA-associated-ceRNA networks in jejunum. Importantly, a network regulating G0S2 in NH₃-induced apoptosis was discovered. Research results showed that G0S2 was upregulated in jejunum of NH₃-exposed group and was associated with activation of the mitochondrial apoptosis pathway. G0S2 antagonized the anti-apoptotic effect of Bcl2, which could be reversed by miR-205a. Meanwhile, lncRNA-107052630 acted as ceRNA to affect G0S2 function. These data provide new insight for revealing the biological effect of NH₃ toxicity, as well as the environmental research.

Lung-derived HMGB1 is detrimental for vascular remodeling of metabolically imbalanced arterial macrophages

Pulmonary disease increases the risk of developing abdominal aortic aneurysms (AAA). However, the mechanism underlying the pathological dialogue between the lungs and aorta is undefined. Here, we find that inflicting acute lung injury (ALI) to mice doubles their incidence of AAA and accelerates macrophage-driven proteolytic damage of the aortic wall. ALI-induced HMGB1 leaks and is captured by arterial macrophages thereby altering their mitochondrial metabolism through RIPK3. RIPK3 promotes mitochondrial fission leading to elevated oxidative stress via DRP1. This triggers MMP12 to lyse arterial matrix, thereby stimulating AAA. Administration of recombinant HMGB1 to WT, but not Ripk3^-/- mice, recapitulates ALI-induced proteolytic collapse of arterial architecture. Deletion of RIPK3 in myeloid cells, DRP1 or MMP12 suppression in ALI-inflicted mice repress arterial stress and brake MMP12 release by transmural macrophages thereby maintaining a strengthened arterial framework refractory to AAA. Our results establish an inter-organ circuitry that alerts arterial macrophages to regulate vascular remodeling.

Identification and Bioinformatic Analysis of Circular RNA Expression in Peripheral Blood Mononuclear Cells from Patients with Chronic Obstructive Pulmonary Disease

Purpose

Circular RNAs (circRNAs) regulate other RNA transcripts by competing for shared microRNAs, which play roles in the pathogenesis of many diseases, including chronic obstructive pulmonary disease (COPD). However, the role of circRNAs in COPD remains unknown. This study aimed to investigate the expression profile and the role of circRNAs in COPD.

Patients and Methods

Twenty-one COPD patients and twenty-one normal controls were recruited. Total RNAs were collected from peripheral blood mononuclear cells (PBMCs) of each participant. CircRNAs and protein-coding mRNAs were profiled by microarray and systematically compared between patients with COPD and control subjects. The top differentially expressed circRNAs and mRNAs were validated by quantitative real-time PCR (RT-qPCR). Functional analysis identified pathways relevant to the pathogenesis of COPD. Next, the circRNA target pathway network, the circRNA-miRNA-mRNA network (ceRNA network) and functional ceRNA regulatory modules were constructed.

Results

In total, 2132 circRNAs and 2734 protein-coding mRNAs were differentially expressed (|fold change| >1.5 and P-value <0.05) in COPD patients. Six out of nine selected RNAs were confirmed by RT-qPCR validation. Our functional analysis suggested that immune imbalances and inflammatory responses play roles in the pathogenesis of COPD. The ceRNA network highlighted the differentially expressed circRNAs and their related miRNAs and mRNAs in COPD. In the circRNA target pathway network and functional ceRNA regulatory modules, hsa_circRNA_0008672 appeared in the top three KEGG pathways (NOD-like receptor signaling pathway, natural killer cell mediated cytotoxicity and Th17 cell differentiation) and may act as the miRNA sponge regulating the hsa_circRNA_0008672/miR-1265/MAPK1 axis.

Conclusion

Our findings demonstrate critical roles of the circRNAs in COPD molecular etiology. The data support a plausible mechanism that circRNAs may be involved in the development of COPD by affecting the immune balance. Moreover, the hsa_circRNA_0008672/miR-1265/MAPK1 axis may contribute to the pathogenesis of COPD, warranting further investigation.

Therapeutic RNA Strategies for Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation with persistent respiratory symptoms. Current therapeutics for COPD are largely borrowed from the drug armamentarium for the treatment of asthma, which has different pathophysiological mechanisms from COPD. COPD has been linked to dysregulated expression of mRNAs and noncoding (nc)RNAs including miRNAs, PIWI-interacting (pi)RNAs, long noncoding (lnc)RNAs, and circular (circ)RNAs. This review highlights and discusses some recent advances towards development of RNA therapeutics for COPD.

Cigarette smoke extract alters genome-wide profiles of circular RNAs and mRNAs in primary human small airway epithelial cells

As a novel kind of non-coding RNA, circular RNAs (circRNAs) were involved in various biological processes. However, the role of circRNAs in the developmental process of chronic obstructive pulmonary disease (COPD) is still unclear. In the present study, by using a cell model of COPD in primary human small airway epithelial cells (HSAECs) treated with or without cigarette smoke extract (CSE), we uncovered 4,379 previously unknown circRNAs in human cells and 903 smoke-specific circRNAs, with the help of RNA-sequencing and bioinformatic analysis. Moreover, 3,872 up- and 4,425 down-regulated mRNAs were also identified under CSE stimulation. Furthermore, a putative circRNA-microRNA-mRNA network was constructed for in-depth mechanism exploration, which indicated that differentially expressed circRNAs could influence expression of some key genes that participate in response to pentose phosphate pathway, ATP-binding cassette (ABC) transporters, glycosaminoglycan biosynthesis pathway and cancer-related pathways. Our research indicated that cigarette smoke had an influence on the biogenesis of circRNAs and mRNAs. CircRNAs might be involved in the response to CSE in COPD through the circRNA-mediated ceRNA networks.