Increased levels of cell death and proliferation in alveolar wall cells in patients with pulmonary emphysema

Nebulized platelet-derived extracellular vesicles attenuate chronic cigarette smoke-induced murine emphysema

Chronic obstructive pulmonary disease (COPD) is a prevalent lung disease usually resulting from cigarette smoking (CS). Cigarette smoking induces oxidative stress, which causes inflammation and alveolar epithelial cell apoptosis and represents a compelling therapeutic target for COPD. Purified human platelet-derived exosome product (PEP) is endowed with antioxidant enzymes and immunomodulatory molecules that mediate tissue repair. In this study, a murine model of CS-induced emphysema was used to determine whether nebulized PEP can influence the development of CS-induced emphysema through the mitigation of oxidative stress and inflammation in the lung. Nebulization of PEP effectively delivered the PEP vesicles into the alveolar region, with evidence of their uptake by type I and type II alveolar epithelial cells and macrophages. Lung function testing and morphometric assessment showed a significant attenuation of CS-induced emphysema in mice treated with nebulized PEP thrice weekly for 4 weeks. Whole lung immuno-oncology RNA sequencing analysis revealed that PEP suppressed several CS-induced cell injuries and inflammatory pathways. Validation of inflammatory cytokines and apoptotic protein expression on the lung tissue revealed that mice treated with PEP had significantly lower levels of S100A8/A9 expressing macrophages, higher levels of CD4+/FOXP3+ Treg cells, and reduced NF-κB activation, inflammatory cytokine production, and apoptotic proteins expression. Further validation using in vitro cell culture showed that pretreatment of alveolar epithelial cells with PEP significantly attenuated CS extract-induced apoptotic cell death. These data show that nebulization of exosomes like PEP can effectively deliver exosome cargo into the lung, mitigate CS-induced emphysema in mice, and suppress oxidative lung injury, inflammation, and apoptotic alveolar epithelial cell death.

The Role of Emphysema on Postoperative Prognosis in Early-Stage Nonsmall Cell Lung Cancer

BACKGROUND

Emphysema is generally considered a poor prognostic factor for patients with nonsmall cell lung cancer; however, whether the poor prognosis is due to highly malignant tumors or emphysema itself remains unclear. This study was designed to determine the prognostic value of emphysema in patients with early-stage nonsmall cell lung cancer.

METHODS

A total of 721 patients with clinical stage IA nonsmall cell lung cancer who underwent complete resection between April 2007 and December 2018 were retrospectively analyzed regarding clinicopathological findings and prognosis related to emphysema.

RESULTS

The emphysematous and normal lung groups comprised 197 and 524 patients, respectively. Compared with the normal lung group, lymphatic invasion (23.9% vs. 14.1%, P = 0.003), vascular invasion (37.6% vs. 17.2%, P < 0.001), and pleural invasion (18.8% vs. 10.9%, P = 0.006) were observed more frequently in the emphysema group. Additionally, the 5-year overall survival rate was lower (77.1% vs. 91.4%, P < 0.001), and the cumulative incidence of other causes of death was higher in the emphysema group (14.0% vs. 3.50%, P < 0.001). Multivariable Cox regression analysis of overall survival revealed that emphysema (vs. normal lung, hazard ratio 2.02, P = 0.0052), age > 70 years (vs. < 70 years, hazard ratio 4.03, P < 0.001), and SUVmax > 1.8 (vs. ≤ 1.8, hazard ratio 2.20, P = 0.0043) were independent prognostic factors.

CONCLUSIONS

Early-stage nonsmall cell lung cancer with emphysema has a tendency for the development of highly malignant tumors. Additionally, emphysema itself may have an impact on poor prognosis.

Arsenic exposure and pulmonary function decline: Potential mediating role of TRAIL in chronic obstructive pulmonary disease patients

BACKGROUND

Environmental arsenic (As) exposure is strongly related to the progression of chronic obstructive pulmonary disease (COPD). Pulmonary epithelial cells apoptosis is implicated in the pathophysiological mechanisms of COPD. However, the role of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), one biomarker of apoptosis, remains unclear in As-mediated pulmonary function alternations in COPD patients.

METHODS

This study included 239 COPD patients. The serum level of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was measured by enzyme-linked immunosorbent assay (ELISA). The blood As level was determined through inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

Blood As levels exhibited a negative and dose-dependent correlation with pulmonary function. Per unit elevation of blood arsenic concentrations was related to reductions of 0.339 L in FEV1, 0.311 L in FVC, 1.171% in FEV1/FVC%, and 7.999% in FEV1% in COPD subjects. Additionally, a positive dose-response correlation of blood As with serum TRAIL was found in COPD subjects. Additionally, the level of serum TRAIL was negatively linked to lung function. Elevated TRAIL significantly mediated As-induced decreases of 11.05%, 13.35%, and 31.78% in FVC, FEV1, and FEV1%, respectively among the COPD patients.

CONCLUSION

Blood As level is positively correlated with pulmonary function decline and serum TRAIL increase in individuals with COPD. Our findings suggest that elevated TRAIL levels may serve as a mediating mechanism through which As contributes to declining lung function in COPD patients.

Mitochondrial network dynamics in pulmonary disease: Bridging the gap between inflammation, oxidative stress, and bioenergetics

Once thought of in terms of bioenergetics, mitochondria are now widely accepted as both the orchestrator of cellular health and the gatekeeper of cell death. The pulmonary disease field has performed extensive efforts to explore the role of mitochondria in regulating inflammation, cellular metabolism, apoptosis, and oxidative stress. However, a critical component of these processes needs to be more studied: mitochondrial network dynamics. Mitochondria morphologically change in response to their environment to regulate these processes through fusion, fission, and mitophagy. This allows mitochondria to adapt their function to respond to cellular requirements, a critical component in maintaining cellular homeostasis. For that reason, mitochondrial network dynamics can be considered a bridge that brings multiple cellular processes together, revealing a potential pathway for therapeutic intervention. In this review, we discuss the critical modulators of mitochondrial dynamics and how they are affected in pulmonary diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), acute lung injury (ALI), and pulmonary arterial hypertension (PAH). A dysregulated mitochondrial network plays a crucial role in lung disease pathobiology, and aberrant fission/fusion/mitophagy pathways are druggable processes that warrant further exploration. Thus, we also discuss the candidates for lung disease therapeutics that regulate mitochondrial network dynamics.

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.

The alveolus: Our current knowledge of how the gas exchange unit of the lung is constructed and repaired

The mammalian lung completes its last step of development, alveologenesis, to generate sufficient surface area for gas exchange. In this process, multiple cell types that include alveolar epithelial cells, endothelial cells, and fibroblasts undergo coordinated cell proliferation, cell migration and/or contraction, cell shape changes, and cell-cell and cell-matrix interactions to produce the gas exchange unit: the alveolus. Full functioning of alveoli also involves immune cells and the lymphatic and autonomic nervous system. With the advent of lineage tracing, conditional gene inactivation, transcriptome analysis, live imaging, and lung organoids, our molecular understanding of alveologenesis has advanced significantly. In this review, we summarize the current knowledge of the constituents of the alveolus and the molecular pathways that control alveolar formation. We also discuss how insight into alveolar formation may inform us of alveolar repair/regeneration mechanisms following lung injury and the pathogenic processes that lead to loss of alveoli or tissue fibrosis.

Alveolar type II epithelial cell FASN maintains lipid homeostasis in experimental COPD

Alveolar epithelial type II (AEC2) cells strictly regulate lipid metabolism to maintain surfactant synthesis. Loss of AEC2 cell function and surfactant production are implicated in the pathogenesis of the smoking-related lung disease chronic obstructive pulmonary disease (COPD). Whether smoking alters lipid synthesis in AEC2 cells and whether altering lipid metabolism in AEC2 cells contributes to COPD development are unclear. In this study, high-throughput lipidomic analysis revealed increased lipid biosynthesis in AEC2 cells isolated from mice chronically exposed to cigarette smoke (CS). Mice with a targeted deletion of the de novo lipogenesis enzyme, fatty acid synthase (FASN), in AEC2 cells (FasniΔAEC2) exposed to CS exhibited higher bronchoalveolar lavage fluid (BALF) neutrophils, higher BALF protein, and more severe airspace enlargement. FasniΔAEC2 mice exposed to CS had lower levels of key surfactant phospholipids but higher levels of BALF ether phospholipids, sphingomyelins, and polyunsaturated fatty acid-containing phospholipids, as well as increased BALF surface tension. FasniΔAEC2 mice exposed to CS also had higher levels of protective ferroptosis markers in the lung. These data suggest that AEC2 cell FASN modulates the response of the lung to smoke by regulating the composition of the surfactant phospholipidome.

Chronic obstructive pulmonary disease and emerging ER stress-related therapeutic targets

COPD pathogenesis is frequently associated with endoplasmic reticulum stress (ER stress) progression. Targeting the major unfolded protein response (UPR) branches in the ER stress pathway may provide pharmacotherapeutic selection strategies for treating COPD and enable relief from its symptoms. In this study, we aimed to systematically review the potential role of the ER stress inhibitors of major UPR branches (IRE1, PERK, and ATF6) in COPD-related studies and determine the current stage of knowledge in this field. The systematic review was carried out adhering to the PRISMA checklist based on published studies obtained from specific keyword searches of three databases, namely PubMed, ScienceDirect and Springer Database. The search was limited to the year 2000-2022 which includes all in vitro studies, in vivo studies and clinical trials related to the application of ER stress inhibitors toward COPD-induced models and disease. The risk of bias was evaluated using the QUIN, SYRCLE, revised Cochrane risk of bias tool for randomized trials (RoB 2.0) and NIH tool respectively. A total of 7828 articles were screened from three databases and a final total of 37 studies were included in the review. The ER stress and UPR pathways are potentially useful to prevent COPD progression and attenuate the exacerbation of COPD and related symptoms. Interestingly, the off-target effects from inhibition of the UPR pathway may be desirable or undesirable depending on context and therapeutic applications. Targeting the UPR pathway could have complex consequences as the production of ER molecules involved in folding may be impaired which could continuously provoke misfolding of proteins. Although several emerging compounds were noted to be potentially useful for targeted therapy against COPD, clinical studies have yet to be thoroughly explored.

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.

The association between leukocyte telomere length and chronic obstructive pulmonary disease is partially mediated by inflammation: a meta-analysis and population-based mediation study

Background

Chronic obstructive pulmonary disease (COPD) is one of the major health issues worldwide. Pathophysiological changes in COPD are mainly reflected in the deterioration of lung function with aging.

Methods

Considering that telomere length is a hallmark of biological aging, we first performed a meta-analysis to summarize the current knowledge about the relationship between telomere length and COPD and then employed individual-level data from the continuous National Health and Nutrition Examination Survey (NHANES) to investigate whether telomere length could reflect accelerated aging in COPD and serve as an independent predictor. A mediation study was further performed to examine whether the association between telomeres and COPD could be mediated by inflammation, as one of the most important etiologies and characteristics of COPD.

Results

The four studies included in our meta-analysis were with high heterogeneity (I² = 95.7%, P_het < 0.001), and the pooled relative risk for COPD comparing the shortest tertile versus the longest tertile was 4.06 (95% CI = 1.38 to 11.96). Of the 6,378 subjects in the individual-level data analyses using NHANES, 455 were diagnosed with COPD, and multivariable-adjusted logistic regression also indicated that short telomere length was associated with COPD. Consistently, cubic regression spline analyses showed that long telomeres exhibited a significant association with a decreased risk of COPD. In the subsequent mediation analyses, C-reactive protein concentration, white blood cells count and blood neutrophil count, as inflammatory biomarkers, showed a significant indirect effect on the relationship between telomere length and COPD.

Conclusion

Accelerated aging in COPD could be characterized by excessive telomere shortening, and inflammatory response might be involved in the underlying mechanisms of COPD pathogenesis promoted by short telomere length. Telomere length measurement may facilitate clinical translational research and targeted therapy of COPD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02114-8.

microRNA Expression Profile of Purified Alveolar Epithelial Type II Cells

Alveolar type II (ATII) cells are essential for the maintenance of the alveolar homeostasis. However, knowledge of the expression of the miRNAs and miRNA-regulated networks which control homeostasis and coordinate diverse functions of murine ATII cells is limited. Therefore, we asked how miRNAs expressed in ATII cells might contribute to the regulation of signaling pathways. We purified “untouched by antibodies” ATII cells using a flow cytometric sorting method with a highly autofluorescent population of lung cells. TaqMan® miRNA low-density arrays were performed on sorted cells and intersected with miRNA profiles of ATII cells isolated according to a previously published protocol. Of 293 miRNAs expressed in both ATII preparations, 111 showed equal abundances. The target mRNAs of bona fide ATII miRNAs were used for pathway enrichment analysis. This analysis identified nine signaling pathways with known functions in fibrosis and/or epithelial-to-mesenchymal transition (EMT). In particular, a subset of 19 miRNAs was found to target 21 components of the TGF-β signaling pathway. Three of these miRNAs (miR-16-5p, -17-5p and -30c-5p) were down-modulated by TGF-β1 stimulation in human A549 cells, and concomitant up-regulation of associated mRNA targets (BMPR2, JUN, RUNX2) was observed. These results suggest an important role for miRNAs in maintaining the homeostasis of the TGF-β signaling pathway in ATII cells under physiological conditions.

Oxidative stress links the tumour suppressor p53 with cell apoptosis induced by cigarette smoke

This study was to investigate the effects of oxidative stress in cigarette smoke (CS)-induced cell apoptosis in mice with emphysema. Thirty-two mice were divided into four groups: the control group, the CS group, the CS + Pifithrin-α group, and the CS + NAC group. Pathological changes and apoptosis in lung tissue of mice were detected. The activity of malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (T-AOC) were measured using spectrophotometer. The proteins expression of p53, Bcl-2, Bax, and caspase-3 were determined by western blot. The results showed that cell apoptosis, lung structural damage, and the activity of MDA, as well as the expression of apoptosis-related proteins Bax, total caspase-3, and cleaved caspase-3 were increased in CS-treated mice. The activity of SOD, CAT, and T-AOC, as well as the expression of anti-apoptosis protein Bcl-2 were decreased in CS-treated mice when compared with the control group. However, Pifithrin-α (p53 inhibitor) and N-Acetylcysteine (NAC) could reduce cell apoptosis, lung structural damage and oxidative stress, accelerate the expression of Bcl-2, while suppressing the expression of Bax, total caspase-3 and cleaved caspase-3. More importantly, the treatment with NAC even inhibited the expression of p53. In conclusions, oxidative stress linking the p53 is involved in cell apoptosis in CS-treated emphysema mice.

Lysophosphatidylcholine Acyltransferase 1 Deficiency Promotes Pulmonary Emphysema via Apoptosis of Alveolar Epithelial Cells

Chronic obstructive pulmonary disease (COPD) is primarily caused by inhalation of cigarette smoke and is the third leading cause of death worldwide. Pulmonary surfactant, a complex of phospholipids and proteins, plays an essential role in respiration by reducing the surface tension in the alveoli. Lysophosphatidylcholine acyltransferase 1 (LPCAT1) is an enzyme that catalyzes the biosynthesis of surfactant lipids and is expressed in type 2 alveolar epithelial cells. Its dysfunction is suggested to be involved in various lung diseases; however, the relationship between LPCAT1 and COPD remains unclear. To investigate the role of LPCAT1 in the pathology of COPD, we analyzed an elastase-induced emphysema model using Lpcat1 knockout (KO) mice. In Lpcat1 KO mice, elastase-induced emphysema was significantly exacerbated with increased apoptotic cells, which was not ameliorated by supplementation with dipalmitoylphosphatidylcholine, which is a major component of the surfactant synthesized by LPCAT1. We subsequently evaluated the effects of cigarette smoking on primary human type 2 alveolar epithelial cells (hAEC2s) and found that cigarette smoke extract (CSE) downregulated the expression of Lpcat1. Furthermore, RNA sequencing analysis revealed that the apoptosis pathway was significantly enriched in CSE-treated primary hAEC2s. Finally, we downregulated the expression of Lpcat1 using small interfering RNA, which resulted in enhanced CSE-induced apoptosis in A549 cells. Taken together, cigarette smoke-induced downregulation of LPCAT1 can promote the exacerbation of pulmonary emphysema by increasing the susceptibility of alveolar epithelial cells to apoptosis, thereby suggesting that Lpcat1 is a novel therapeutic target for irreversible emphysema.

Spiperone Stimulates Regeneration in Pulmonary Endothelium Damaged by Cigarette Smoke and Lipopolysaccharide

Background

Endothelial dysfunction and destruction of the pulmonary microcirculation are important pathogenic factors in chronic obstructive pulmonary disease (COPD). In COPD, bronchial obstruction is associated with endothelial dysfunction. Thus, new pharmacological treatment options aimed at restoring the pulmonary endothelium represent a clinical need in COPD therapy. Notch1 has been shown to protect cells against apoptosis, inflammation, and oxidative stress caused by cigarette smoke extract (CSE). Therefore, drug which effect on Notch1 may be a potential therapeutic target for COPD in the future.

Methods

In this study, we assessed the potential of spiperone to mediate regeneration of pulmonary endothelium in model of pulmonary emphysema induced by a CSE and lipopolysaccharide (LPS) in female C57BL/6 mice.

Results

Spiperone increased the number of capillaries as well as the expression of the CD31 in the alveolar tissue compared to the controls. Moreover, application of spiperone prevented alveolar wall destruction (DI), and reduced the area of emphysema. Lastly, we demonstrated that spiperone positively influenced mobilization and migration of endothelial progenitor cells (EPC, CD45⁻CD34⁺CD31⁺), CD309⁺-endothelial cells, and angiogenesis precursors (CD45⁻CD117⁺CD309⁺) into the lung. Spiperone administration significantly reduced the number Notch1 positive CD309⁺-endothelial cells and Notch1+ EPCs.

Conclusion

Overall, our results suggest that spiperone mediates endothelial regeneration in an animal model of COPD. Thus, it could represent a novel therapeutic approach for treatment of emphysema associated with COPD.

Air pollution-regulated E-cadherin mediates contact inhibition of proliferation via the hippo signaling pathways in emphysema

Air pollution has been linked to emphysema in chronic obstruction pulmonary disease (COPD). However, the underlying mechanisms in the development of emphysema due to air pollution remain unclear. The objective of this study was to investigate the role of components of the Hippo signaling pathway for E-cadherin-mediated contact inhibition of proliferation in the lungs after air pollution exposure. E-Cadherin-mediated contact inhibition of proliferation via the Hippo signaling pathway was investigated in Sprague-Dawley (SD) rats whole-body exposed to air pollution, and in alveolar epithelial A549 cells exposed to diesel exhaust particles (DEPs), E-cadherin-knockdown, and high-mobility group box 1 (HMGB1) treatment. Underlying epithelial differentiation, apoptosis, and senescence were also examined, and the interaction network among these proteins was examined. COPD lung sections were used to confirm the observations in rats. Expressions of HMGB1 and E-cadherin were negatively regulated in the lungs and A549 cells by air pollution, and this was confirmed by knockdown of E-cadherin and by treating A549 cells with HMGB1. Depletion of phosphorylated (p)-Yap occurred after exposure to air pollution and E-cadherin-knockdown, which resulted in decreases of SPC and T1α. Exposure to air pollution and E-cadherin-knockdown respectively downregulated p-Sirt1 and increased p53 levels in the lungs and in A549 cells. Moreover, the protein interaction network suggested that E-cadherin is a key activator in regulating Sirt1 and p53, as well as alveolar epithelial cell differentiation by SPC and T1α. Consistently, downregulation of E-cadherin, p-Yap, SPC, and T1α was observed in COPD alveolar regions with particulate matter (PM) deposition. In conclusion, our results indicated that E-cadherin-mediated cell-cell contact directly regulates the Hippo signaling pathway to control differentiation, cell proliferation, and senescence due to air pollution. Exposure to air pollution may initiate emphysema in COPD patients.

Cigarette Smoke Particle-Induced Lung Injury and Iron Homeostasis

It is proposed that the mechanistic basis for non-neoplastic lung injury with cigarette smoking is a disruption of iron homeostasis in cells after exposure to cigarette smoke particle (CSP). Following the complexation and sequestration of intracellular iron by CSP, the host response (eg, inflammation, mucus production, and fibrosis) attempts to reverse a functional metal deficiency. Clinical manifestations of this response can present as respiratory bronchiolitis, desquamative interstitial pneumonitis, pulmonary Langerhans’ cell histiocytosis, asthma, pulmonary hypertension, chronic bronchitis, and pulmonary fibrosis. If the response is unsuccessful, the functional deficiency of iron progresses to irreversible cell death evident in emphysema and bronchiectasis. The subsequent clinical and pathological presentation is a continuum of lung injuries, which overlap and coexist with one another. Designating these non-neoplastic lung injuries after smoking as distinct disease processes fails to recognize shared relationships to each other and ultimately to CSP, as well as the common mechanistic pathway (ie, disruption of iron homeostasis).

GLIPR1 Protects Against Cigarette Smoke-Induced Airway Inflammation via PLAU/EGFR Signaling

Background

Chronic obstructive pulmonary disease (COPD) is a major health problem associated with high mortality worldwide. Cigarette smoke (CS) exposure is the main cause of COPD. Glioma pathogenesis-related protein 1 (GLIPR1) plays a key role in cell growth, proliferation, and invasion; however, the role of GLIPR1 in COPD remains unclear.

Methods

To clarify the involvement of GLIPR1 in COPD pathogenesis, Glipr1 knockout (Glipr1-/-) mice were generated. Wild-type (WT) and Glipr1-/- mice were challenged with CS for 3 months. To illustrate how GLIPR1 regulates CS-induced airway damage, knockdown experiments targeting GLIPR1 and PLAU, as well as overexpression experiments of PLAU, were performed with human bronchial epithelial cells.

Results

Compared with WT mice, Glipr1-/- mice showed exacerbated CS-induced airway damage including lung inflammation, airway wall thickening, and alveolar destruction. After CS exposure, total proteins, total white cells, neutrophils, lymphocytes, IL-6, and matrix metalloproteinase-9 increased significantly in lung of Glipr1-/- mice than those in lung of WT mice. Furthermore, in vivo and in vitro experiments demonstrated that silencing of GLIPR1 inactivated PLAU/EGFR signaling and promoted caspase-1-dependent pyroptosis (a mode of inflammatory cell death) induced by CS and CS extract exposure, respectively. In vitro experiments further revealed the interaction between GLIPR1 and PLAU, and silencing of PLAU blocked EGFR signaling and promoted pyroptosis, while overexpression of PLAU activated EGFR signaling and reversed pyroptosis.

Conclusion

To conclude, GLIPR1 played a pivotal role in COPD pathogenesis and protected against CS-induced inflammatory response and airway damage, including cell pyroptosis, through the PLAU/EGFR signaling. Thus, GLIPR1 may play a potential role in COPD treatment.

The role of miRNAs in alveolar epithelial cells in emphysema

Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease becoming one of the leading causes of mortality and morbidity globally. The significant risk factors for COPD are exposure to harmful particles such as cigarette smoke, biomass smoke, and air pollution. Pulmonary emphysema belongs to COPD and is characterized by a unique alveolar destruction pattern resulting in marked airspace enlargement. Alveolar type II (ATII) cells have stem cell potential; they proliferate and differentiate to alveolar type I cells to restore the epithelium after damage. Oxidative stress causes premature cell senescence that can contribute to emphysema development. MiRNAs regulate gene expression, are essential for maintaining ATII cell homeostasis, and their dysregulation contributes to this disease development. They also serve as biomarkers of lung diseases and potential therapeutics. In this review, we summarize recent findings on miRNAs’ role in alveolar epithelial cells in emphysema.

Association Between Air Pollution and Lung Lobar Emphysema in COPD

The development of emphysema has been linked to air pollution; however, the association of air pollution with the extent of lobar emphysema remains unclear. This study examined the association of particulate matter <2.5 μm in aerodynamic diameters (PM_2.5) (≤2.5 μm), nitrogen dioxide (NO₂), and ozone (O₃) level of exposure with the presence of emphysema in 86 patients with chronic obstructive pulmonary disease (COPD). Exposure to the air pollution estimated using the land-use regression model was associated with lung function, BODE (a body mass index, degree of obstruction, dyspnea severity, and exercise capacity index) quartiles, and emphysema measured as low-attenuation areas on high-resolution CT (HR-CT) lung scans. Using paraseptal emphysema as the reference group, we observed that a 1 ppb increase in O₃ was associated with a 1.798-fold increased crude odds ratio of panlobular emphysema (p < 0.05). We observed that PM_2.5 was associated with BODE quartiles, modified Medical Research Council (mMRC) dyspnea score, and exercise capacity (all p < 0.05). We found that PM_2.5, NO₂, and O₃ were associated with an increased degree of upper lobe emphysema and lower lobe emphysema (all p < 0.05). Furthermore, we observed that an increase in PM_2.5, NO₂, and O₃ was associated with greater increases in upper lobe emphysema than in lower lobe emphysema. In conclusion, exposure to O₃ can be associated with a higher risk of panlobular emphysema than paraseptal emphysema in patients with COPD. Emphysema severity in lung lobes, especially the upper lobes, may be linked to air pollution exposure in COPD.

Necroptosis in Pulmonary Diseases: A New Therapeutic Target

In the past decades, apoptosis has been the most well-studied regulated cell death (RCD) that has essential functions in tissue homeostasis throughout life. However, a novel form of RCD called necroptosis, which requires receptor-interacting protein kinase-3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL), has recently been receiving increasing scientific attention. The phosphorylation of RIPK3 enables the recruitment and phosphorylation of MLKL, which oligomerizes and translocates to the plasma membranes, ultimately leading to plasma membrane rupture and cell death. Although apoptosis elicits no inflammatory responses, necroptosis triggers inflammation or causes an innate immune response to protect the body through the release of damage-associated molecular patterns (DAMPs). Increasing evidence now suggests that necroptosis is implicated in the pathogenesis of several human diseases such as systemic inflammation, respiratory diseases, cardiovascular diseases, neurodegenerative diseases, neurological diseases, and cancer. This review summarizes the emerging insights of necroptosis and its contribution toward the pathogenesis of lung diseases.

Sodium Tanshinone IIA Sulfonate Attenuates Cigarette Smoke Extract-Induced Mitochondrial Dysfunction, Oxidative Stress, and Apoptosis in Alveolar Epithelial Cells by Enhancing SIRT1 Pathway

Emphysema is one of the most important phenotypes for chronic obstructive pulmonary disease (COPD). Apoptosis in alveolar epithelial cells (AECs) causes the emphysematous alterations in the smokers and patients with COPD. Sirtuin 1 (SIRT1) is able to attenuate mitochondrial dysfunction, oxidative stress, and to modulate apoptosis. It has been shown that sodium tanshinone IIA sulfonate (STS), a water-soluble derivative of tanshinone IIA, protects against cigarette smoke (CS)-induced emphysema/COPD in mice. However, the mechanisms underlying these findings remain unclear. Here, we investigate whether and how STS attenuates AEC apoptosis via a SIRT1-dependent mechanism. We found that STS treatment decreased CS extract (CSE)-induced apoptosis in human alveolar epithelial A549 cells. STS reduced oxidative stress, improved mitochondrial function and mitochondrial membrane potential (ΔΨm), and restored mitochondrial dynamics-related protein expression. Moreover, STS promoted mitophagy, and increased oxidative phosphorylation protein levels (complexes I-IV) in CSE-stimulated A549 cells. The protective effects of STS were associated with SIRT1 upregulation, because SIRT1 inhibition by EX 527 significantly attenuated or abolished the ability of STS to reverse the CSE-induced mitochondrial damage, oxidative stress, and apoptosis in A549 cells. In conclusion, STS ameliorates CSE-induced AEC apoptosis by improving mitochondrial function and reducing oxidative stress via enhancing SIRT1 pathway. These findings provide novel mechanisms underlying the protection of STS against CS-induced COPD.

Effects of Aspergillus fumigatus Conidia on Apoptosis and Proliferation in an In Vitro Model of the Lung Microenvironment

Background/Aim: Aspergillus is often detected in respiratory samples from patients with chronic respiratory diseases, including pulmonary fibrosis, suggesting that it can easily colonize the airways. To determine the role of Aspergillus colonization in pulmonary fibrosis, we cultured human lung epithelial A549 cells or murine embryo fibroblast NIH/3T3 cells with Aspergillus conidia in 3D floating culture representing the microenvironment. Materials and Methods: Cells were cultured in two-dimensional (2D) and three-dimensional floating (3DF) culture with heat-inactivated Aspergillus fumigatus (AF) 293 conidia at an effector-to-target cell ratio of 1:10 (early-phase model) and 1:100 (colonization model), and RNA-sequencing and Western blots (WB) were performed. Results: AF293 conidia reduced A549 cell growth in 2D and 3DF cultures and induced apoptosis in A549 spheroids in 3DF culture. RNA-sequencing revealed the increased expression of genes associated with interferon-mediated antiviral responses including MX dymamin-like GTPase 1 (MX1). Interestingly, the decreased expression of genes associated with the cell cycle was observed with a high concentration of AF293 conidia. WB revealed that epithelial-mesenchymal transition was not involved. Notably, AF293 conidia increased NIH/3T3 growth only in 3DF culture without inducing an apoptotic reaction. RNA-sequencing revealed the increased expression of genes associated with interferon signalling, including MX2; however, the decreased expression of genes associated with the cell cycle was not observed. Conclusions: AF affects both apoptosis of epithelial cells and the growth of fibroblasts. A deeper understanding of the detailed mechanisms underlying Aspergillus-mediated signaling pathway in epithelial cells and fibroblasts will help us to understand the lung microenvironment.

PR1P Stabilizes VEGF and Upregulates Its Signaling to Reduce Elastase-induced Murine Emphysema

Emphysema is a progressive and fatal lung disease with no cure that is characterized by thinning, enlargement, and destruction of alveoli, leading to impaired gas exchange. Disease progression is due in part to dysregulation of VEGF (vascular endothelial growth factor) signaling in the lungs and increased lung-cell apoptosis. Here we asked whether PR1P (Prominin-1-derived peptide), a novel short peptide we designed that increases VEGF binding to endothelial cells, could be used to improve outcome in in vitro and in vivo models of emphysema. We used computer simulation and in vitro and in vivo studies to show that PR1P upregulated endogenous VEGF receptor-2 signaling by binding VEGF and preventing its proteolytic degradation. In so doing, PR1P mitigated toxin-induced lung-cell apoptosis, including from cigarette-smoke extract in vitro and from LPS in vivo in mice. Remarkably, inhaled PR1P led to significantly increased VEGF concentrations in murine lungs within 30 minutes that remained greater than twofold above that of control animals 24 hours later. Finally, inhaled PR1P reduced acute lung injury in 4- and 21-day elastase-induced murine emphysema models. Taken together, these results highlight the potential of PR1P as a novel therapeutic agent for the treatment of emphysema or other lung diseases characterized by VEGF signaling dysregulation.

Severity of emphysema as a prognosticator of resected early lung cancer: an analysis classified by Goddard score

OBJECTIVES

This study aimed to investigate whether the severity of emphysema as classified by Goddard score influences the prognosis of patients with early lung cancer, there are few reports about that.

METHODS

From April 2009 to December 2016, we recruited 412 consecutive patients with completely resected clinical stage 0/IA/IB non-small cell lung cancer. The Goddard score assessed on preoperative computed tomography scan was retrospectively reviewed. Kaplan-Meier and Cox regression analyses were performed to assess the relationship between the Goddard score and early lung cancer prognosis.

RESULTS

The patients were classified into two groups: Goddard score ≤ 4 points and ≥5 points according to the results of receiver operating characteristic curve analysis for recurrence events. The 3-year relapse-free survival rate of emphysema with Goddard score ≤ 4 points (88.6%) was higher than that of emphysema with Goddard score ≥ 5 points (60.8%) (P < 0.001). There was a higher proportion of cancer-related deaths in the group with Goddard score ≥ 5 points compared with the group with Goddard score ≤ 4 points (50% and 32.1%, respectively) (P = 0.082). A Goddard score ≥ 5 points was a significant prognostic factor for relapse-free survival in the univariate (P < 0.001) and multivariate (P = 0.022) analyses. A Goddard score ≥ 5 points was also a significant prognostic factor for overall survival in the univariate (P < 0.001) and multivariate (P = 0.041) analyses.

CONCLUSION

Our findings suggest that emphysema with a Goddard score of ≥5 points may be a factor that can influence the prognosis of patients with primary lung cancer.

Exposure to Cigarette Smoke Enhances the Stemness of Alveolar Type 2 Cells

Chronic exposure to cigarette smoke (CS) causes chronic inflammation, oxidative stress, and apoptosis of epithelial cells, which results in destruction of the lung matrix. However, the mechanism by which the lung fails to repair the CS-induced damage, thereby succumbing to emphysema, remains unclear. Alveolar type 2 (AT2) cells comprise the stem cells of the alveolar compartments and are responsible for repairing and maintaining lung tissues. In this study, we examined the effect of chronic CS on AT2 stem cells. Adult mice expressing GFP in their AT2 cells were exposed to CS for > 3 months. Histological assessment showed that CS not only induced emphysematous changes but also increased the number of AT2 cells compared with that of air-exposed lungs. Assessment of sorted GFP+/AT2 cells via the stem cell three-dimensional organoid/colony-forming assay revealed that the number and size of the colonies formed by the CS-exposed AT2 stem cells were significantly higher than those of air-exposed control AT2 cells. Although CS-exposed lungs had more apoptotic cells, examination of the surviving AT2 stem cells in two-dimensional in vitro culture revealed that they developed a higher ability to resist apoptosis. Microarray analysis of CS-exposed AT2 stem cells revealed the upregulation of genes related to circadian rhythm and inflammatory pathways. In conclusion, we provide evidence that AT2 stem cells respond to chronic CS exposure by activating their stem cell function, thereby proliferating and differentiating faster and becoming more resistant to apoptosis. Disturbances in expression levels of several circadian rhythm-related genes might be involved in these changes.

Chaperone-Mediated Autophagy Suppresses Apoptosis via Regulation of the Unfolded Protein Response during Chronic Obstructive Pulmonary Disease Pathogenesis

Cigarette smoke (CS) induces accumulation of misfolded proteins with concomitantly enhanced unfolded protein response (UPR). Increased apoptosis linked to UPR has been demonstrated in chronic obstructive pulmonary disease (COPD) pathogenesis. Chaperone-mediated autophagy (CMA) is a type of selective autophagy for lysosomal degradation of proteins with the KFERQ peptide motif. CMA has been implicated in not only maintaining nutritional homeostasis but also adapting the cell to stressed conditions. Although recent papers have shown functional cross-talk between UPR and CMA, mechanistic implications for CMA in COPD pathogenesis, especially in association with CS-evoked UPR, remain obscure. In this study, we sought to examine the role of CMA in regulating CS-induced apoptosis linked to UPR during COPD pathogenesis using human bronchial epithelial cells (HBEC) and lung tissues. CS extract (CSE) induced LAMP2A expression and CMA activation through a Nrf2-dependent manner in HBEC. LAMP2A knockdown and the subsequent CMA inhibition enhanced UPR, including CHOP expression, and was accompanied by increased apoptosis during CSE exposure, which was reversed by LAMP2A overexpression. Immunohistochemistry showed that Nrf2 and LAMP2A levels were reduced in small airway epithelial cells in COPD compared with non-COPD lungs. Both Nrf2 and LAMP2A levels were significantly reduced in HBEC isolated from COPD, whereas LAMP2A levels in HBEC were positively correlated with pulmonary function tests. These findings suggest the existence of functional cross-talk between CMA and UPR during CSE exposure and also that impaired CMA may be causally associated with COPD pathogenesis through enhanced UPR-mediated apoptosis in epithelial cells.

NADPH oxidase subunit NOXO1 is a target for emphysema treatment in COPD

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and death worldwide. Peroxynitrite, formed from nitric oxide, which is derived from inducible nitric oxide synthase, and superoxide, has been implicated in the development of emphysema, but the source of the superoxide was hitherto not characterized. Here, we identify the non-phagocytic NADPH oxidase organizer 1 (NOXO1) as the superoxide source and an essential driver of smoke-induced emphysema and pulmonary hypertension development in mice. NOXO1 is consistently upregulated in two models of lung emphysema, Cybb (also known as NADPH oxidase 2, Nox2)-knockout mice and wild-type mice with tobacco-smoke-induced emphysema, and in human COPD. Noxo1-knockout mice are protected against tobacco-smoke-induced pulmonary hypertension and emphysema. Quantification of superoxide, nitrotyrosine and multiple NOXO1-dependent signalling pathways confirm that peroxynitrite formation from nitric oxide and superoxide is a driver of lung emphysema. Our results suggest that NOXO1 may have potential as a therapeutic target in emphysema.

Blockade of Dopamine D2 Receptors as a Novel Approach to Stimulation of Notch1+ Endothelial Progenitor Cells and Angiogenesis in C57BL/6 Mice with Pulmonary Emphysema Induced by Proteases and Deficiency of α1-Antitrypsin

We studied the effects of spiperone, a selective blocker of dopamine D2 receptors, on the model of pulmonary emphysema provoked by administration of elastase and D-galactosamine hydrochloride to female C57BL/6 mice and characterized by activation of proteases in the lungs and systemic deficiency of its inhibitor α1-antitrypsin. In this model, spiperone prevented the development of inflammatory reaction and reduced the area of emphysematous expanded alveolar tissue. The expression of angiogenic marker CD31 in the lungs increased under these conditions. Regeneration of the damaged microvascular bed under the action of spiperone resulted from recruiting of Notch1⁺ endothelial progenitor cells (CD45^-CD31⁺CD34⁺) into the lungs and blockade of the inhibitory effect of dopamine on phosphorylation of VEGF-2 receptors in endothelial cells of different maturity. In addition, spiperone produced a protective effect on hepatocytes and restored the production and secretion of α1-antitrypsin by these cells.

Hydrogen sulfide inhibits cigarette smoke-induced inflammation and injury in alveolar epithelial cells by suppressing PHD2/HIF-1α/MAPK signaling pathway

Chronic obstructive pulmonary fibrosis (COPD) is a chronic and fatal lung disease with few treatment options. Sodium hydrosulfide (NaHS), a donor of hydrogen sulfide (H2S), was found to alleviate cigarette smoke (CS)-induced emphysema in mice, however, the underlying mechanisms have not yet been clarified. In this study, we investigated its effects on COPD in a CS-induced mouse model in vivo and in cigarette smoke extract (CSE)-stimulated alveolar epithelial A549 cells in vitro. The results showed that NaHS not only relieved emphysema, but also improved pulmonary function in CS-exposed mice. NaHS significantly increased the expressions of tight junction proteins (i.e., ZO-1, Occludin and claudin-1), and reduced apoptosis and secretion of pro-inflammatory cytokines (i.e., TNF-α, IL-6 and IL-1β) in CS-exposed mouse lungs and CSE-incubated A549 cells, indicating H2S inhibits CS-induced inflammation, injury and apoptosis in alveolar epithelial cells. NaHS also upregulated prolyl hydroxylase (PHD)2, and suppressed hypoxia-inducible factor (HIF)-1α expression in vivo and in vitro, suggesting H2S inhibits CS-induced activation of PHD2/HIF-1α axis. Moreover, NaHS inhibited CS-induced phosphorylation of ERK, JNK and p38 MAPK in vivo and in vitro, and treatment with their inhibitors reversed CSE-induced ZO-1 expression and inflammation in A549 cells. These results suggest that NaHS may prevent emphysema via the suppression of PHD2/HIF-1α/MAPK signaling pathway, and subsequently inhibition of inflammation, epithelial cell injury and apoptosis, and may be a novel strategy for the treatment of COPD.

Cigarette smoke exposure enhances transforming acidic coiled-coil-containing protein 2 turnover and thereby promotes emphysema

Our integrative genomic and functional analysis identified transforming acidic coiled-coil-containing protein 2 (TACC2) as a chronic obstructive pulmonary disease (COPD) candidate gene. Here, we found that smokers with COPD exhibit a marked decrease in lung TACC2 protein levels relative to smokers without COPD. Single cell RNA sequencing reveals that TACC2 is expressed primarily in lung epithelial cells in normal human lungs. Furthermore, suppression of TACC2 expression impairs the efficiency of homologous recombination repair and augments spontaneous and cigarette smoke extract-induced (CSE-induced) DNA damage and cytotoxicity in immortalized human bronchial epithelial cells. By contrast, enforced expression of TACC2 attenuates the CSE effects. We also found that CSE enhances TACC2 degradation via the ubiquitin-proteasome system mediated by the ubiquitin E3 ligase subunit, F box L7. Furthermore, cellularly expressed TACC2 proteins harboring naturally occurring mutations exhibited altered protein lifespan coupled with modified DNA damage repair and cytotoxic responses. CS triggers emphysematous changes accompanied by accumulated DNA damage, apoptosis of alveolar epithelia, and lung inflammation in Tacc2-/- compared with Tacc2+/+ mice. Our results suggest that CS destabilizes TACC2 protein in lung epithelia by the ubiquitin proteasome system, leading to subsequent DNA damage, cytotoxicity, and emphysema.

Molecular Characteristics and Treatment of Endothelial Dysfunction in Patients with COPD: A Review Article

Patients with chronic obstructive pulmonary disease (COPD) show systemic consequences, such as chronic systemic inflammation leading to changes in the airway, airway penetrability, and endothelial function. Endothelial dysfunction is characterized by a list of alterations of endothelium towards reduced vasodilation, proinflammatory state, detachment and apoptosis of endothelial cells, and development of atherosclerosis. COPD-induced endothelial dysfunction is associated with elevated cardiovascular risk. The increment of physical activities such as pulmonary rehabilitation (PR) training have a significant effect on COPD, thus, PR can be an integrative part of COPD treatment. In this narrative review the focus is on the function of endothelial inflammatory mediators [cytokines, chemokines, and cellular proteases] and pulmonary endothelial cells and endothelial dysfunction in COPD as well as the effects of dysfunction of the endothelium may play in COPD-related pulmonary hypertension. The relationship between smoking and endothelial dysfunction is also discussed. The connection between different pulmonary rehabilitation programs, arterial stiffness and pulse wave velocity (PWV) is presented. Endothelial dysfunction is a significant prognostic factor of COPD, which can be characterized by PWV. We discuss future considerations, like training programs, as an important part of the treatment that has a favorable impact on the endothelial function.

Reduced transient receptor potential vanilloid 2 expression in alveolar macrophages causes COPD in mice through impaired phagocytic activity

Background

Defective phagocytosis in alveolar macrophages is associated with chronic obstructive pulmonary disease (COPD). Transient receptor potential cation channel subfamily V member 2 (TRPV2), a type of nonselective cation channel pertinent to diverse physiological functions, regulates macrophage phagocytosis. However, the role of TRPV2 in COPD remains poorly understood. Here, we explored the role of TRPV2 in the development of COPD.

Methods

Macrophage TRPV2 expression and phagocytosis function were measured in MH-S cells (a murine alveolar macrophage cell line) and a cigarette smoke exposure mouse model.

Results

TRPV2 expression and phagocytosis function were reduced when MH-S cells were exposed to cigarette smoke extract (CSE). TRPV2 knockdown by siRNA decreased phagocytosis in MH-S cells. Consistently, TRPV2 expression was reduced in alveolar macrophages prepared from bronchoalveolar lavage samples of mice which were exposed to cigarette smoke for 2 months. In addition, the alveolar space was progressively enlarged during development in TRPV2 knockout (TRPV2KO) mice. Moreover, exposure to cigarette smoke for 2 months significantly induced alveolar space enlargement in TRPV2KO mice, but not in wild-type (WT) mice. The phagocytic function of alveolar macrophages from TRPV2KO mice was reduced, compared with macrophages from WT mice.

Conclusions

TRPV2 expression is profoundly downregulated in alveolar macrophages at early time points of cigarette smoke exposure. Reduced TRPV2-mediated phagocytic function renders the lung susceptible to cigarette smoke-induced alveolar space enlargement. TRPV2 may provide a therapeutic target for COPD induced by cigarette smoke.

Electronic supplementary material

The online version of this article (10.1186/s12890-019-0821-y) contains supplementary material, which is available to authorized users.

Effects of Scutellaria baicalensis Extract on Cigarette Smoke-Induced Airway Inflammation in a Murine Model of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), including pulmonary emphysema and chronic bronchitis as well as structural and inflammatory changes in small airways, is insensitive to corticosteroid therapies. This study aimed to evaluate the effects of Scutellaria baicalensis root extract (SB_E) in a mouse model of COPD. The COPD mouse model was produced by challenging C57BL/6 mice with a cigarette smoke extract and lipopolysaccharide (LPS). SB_E significantly decreased the neutrophil counts in blood and bronchoalveolar lavage fluid (BALF), and the production of tumor necrosis factor (TNF)-α, interleukin (IL)-17A, macrophage inflammatory protein 2 (MIP2), and chemokine (C-X-C motif) ligand 1 (CXCL-1) in BALF, and TNF-α mRNA expression in lung tissue. The histological lung injury was also alleviated by treatment with SB_E. Thus, SB_E effectively inhibited airway inflammation by regulating the expression of inflammatory cytokines by blocking MIP2 and CXCL-1 secretion. Therefore, S. baicalensis may be a potential therapeutic agent for COPD.

Salvianolic acid B as an anti-emphysema agent II: In vivo reversal activities in two rat models of emphysema

Emphysema progressively destroys alveolar structures, leading to disability and death, yet remains irreversible and incurable to date. Impaired vascular endothelial growth factor (VEGF) signaling is an emerging pathogenic mechanism, thereby proposing a hypothesis that VEGF stimulation/elevation enables recovery from alveolar structural destruction and loss of emphysema. Our previous in vitro study identified that salvianolic acid B (Sal-B), a polyphenol of traditional Chinese herbal danshen, stimulated lung cell proliferation and migration, and protected against induced lung cell death, by virtue of signal transducer and activator of transcription 3 (STAT3) activation and VEGF stimulation/elevation. Thus, this study examined Sal-B for in vivo therapeutic reversal of established emphysema in two rat models. Emphysema was induced with porcine pancreatic elastase (PPE) and cigarette smoke extract (CSE), and established by day 21. Sal-B was then spray-dosed to the lung three times weekly for three weeks. Functional treadmill exercise endurance; morphological airspace enlargement and alveolar destruction; apoptosis, cell proliferation and tissue matrix proteins; phosphorylated STAT3 (pSTAT3) and VEGF expressions; neutrophil accumulation; and lipid peroxidation were determined. In both models, Sal-B at 0.2 mg/kg significantly reversed impaired exercise endurance by 80 and 64%; airspace enlargement [mean linear intercept (MLI)] by 56 and 67%; and alveolar destructive index (%DI) by 63 and 66%, respectively. Induced apoptosis activity [cleaved caspase-3] was normalized by 94 and 82%; and cell proliferation activity [proliferative cell nuclear antigen (PCNA)] was stimulated by 1.6 and 2.1-fold. In the PPE-induced model, Sal-B reduced induction of lung's matrix metalloproteinase (MMP)-9 and MMP-2 activities by 59 and 94%, respectively, and restored pSTAT3 and VEGF expressions to the healthy lung levels, while leaving neutrophil accumulation unchecked [myeloperoxidase (MPO) activity]. In the CSE-induced model, Sal-B elevated pSTAT3 and VEGF expressions both by 1.8-fold over the healthy lung levels, and normalized induced lipid peroxidation [malondialdehyde (MDA) activity] by 68%. These results provide an in vivo proof-of-concept for Sal-B as one of the first anti-emphysema agents enabling reversal of alveolar structural destruction and loss via local lung treatment by virtue of its STAT3 activation and VEGF stimulation.

Proteases and Their Inhibitors in Chronic Obstructive Pulmonary Disease

In the context of respiratory disease, chronic obstructive pulmonary disease (COPD) is the leading cause of mortality worldwide. Despite much development in the area of drug development, currently there are no effective medicines available for the treatment of this disease. An imbalance in the protease: Antiprotease ratio in the COPD lung remains an important aspect of COPD pathophysiology and several studies have shown the efficacy of antiprotease therapy in both in vitro and in vivo COPD models. However more in-depth studies will be required to validate the efficacy of lead drug molecules targeting these proteases. This review discusses the current status of protease-directed drugs used for treating COPD and explores the future prospects of utilizing the potential of antiprotease-based therapeutics as a treatment for this disease.

Gene expression profile of human lung in a relatively early stage of COPD with emphysema

Purpose

As only some smokers develop COPD with emphysema, we explored the molecular pathogenesis of early-stage COPD with emphysema using gene expression profiling of human lung tissues.

Patients and methods

First, 110 subjects who had smoked more than ten pack-years were classified into three groups: COPD with emphysema, COPD without emphysema, and healthy smokers. COPD and emphysema were confirmed by post-bronchodilator forced expiratory volume in 1 second/forced vital capacity <0.7 and by chest computed tomography. Lung tissues obtained surgically from the 110 subjects were processed and used for RNA-Seq analysis.

Results

Among the 110 subjects, 29 had COPD with emphysema, 21 had COPD without emphysema, and 60 were healthy smokers; their mean post-bronchodilator forced expiratory volume in 1 second values were 78%, 80%, and 94%, respectively. Using RNA-Seq, we evaluated 16,676 genes expressed in lung tissues. Among them, 1,226 genes in the COPD with emphysema group and 434 genes in the COPD without emphysema group were differentially expressed genes compared to the expression in healthy smokers. In the COPD with emphysema group, ACER2 and LMAN2L were markedly increased and decreased, respectively. In the COPD without emphysema group, the CHRM3 gene, previously reported to be associated with COPD, and HDAC10 were markedly increased and decreased, respectively.

Conclusion

Our study identified differences in gene expression in subjects with COPD according to emphysema status using RNA-Seq transcriptome analysis. These findings may have mechanistic implications in COPD.

Oleuropein Curtails Pulmonary Inflammation and Tissue Destruction in Models of Experimental Asthma and Emphysema

Airway inflammation has been implicated in evoking progressive pulmonary disorders including chronic obstructive pulmonary disease (COPD) and asthma as a result of exposure to inhaled irritants, characterized by airway fibrosis, mucus hypersecretion, and loss of alveolar integrity. The current study examined whether oleuropein, a phenylethanoid found in olive leaves, inhibited pulmonary inflammation in experimental models of interleukin (IL)-4-exposed bronchial BEAS-2B epithelial cells and ovalbumin (OVA)- or cigarette smoke (CS)-exposed BALB/c mice. Nontoxic oleuropein at 1-20 μM diminished eotaxin-1-mediated induction of α-smooth muscle actin and mucin 5AC in epithelial cells stimulated by IL-4 at the transcriptional levels. Oral supplementation of 10-20 mg/kg oleuropein reduced the airway influx of eosinophils and lymphocytes as well as IL-4 secretion in lung promoted by OVA inhalation or CS. In addition, oleuropein suppressed infiltration of macrophages and neutrophils through blocking OVA inhalation- and CS-promoted induction of ICAM-1, F4/80, CD68, and CD11b in airways. OVA-exposed pulmonary fibrosis was detected, while alveolar emphysema was evident in CS-exposed mouse lungs. In alveolar epithelial A549 cells exposed to CS extracts, oleuropein attenuated apoptotic cell loss. Collectively, oleuropein inhibited pulmonary inflammation leading to asthmatic fibrosis and alveolar emphysema driven by influx of inflammatory cells in airways exposed OVA or CS. Therefore, oleuropein may be a promising anti-inflammatory agent for treating asthma and COPD.

Bone Marrow-Derived Mononuclear Cell Therapy in Papain-Induced Experimental Pulmonary Emphysema

Murine papain-induced emphysema is a model that reproduces many of the features found in patients. Bone marrow-derived mononuclear cells (BMMC) have already been used to repair the alveolar epithelium in respiratory diseases, but not in the papain model. Thus, we hypothesized that BMMC could prevent the pathophysiological processes in papain-induced experimental emphysema. Female BALB/c mice received intratracheal instillation of 50 μL of saline (S groups) or papain (P groups, 10 IU/50 μl of saline) on days 1 and 7 of the experimental protocol. On the 14th day, 2 × 10⁶ BMMC of male BALB/c mice (SC21 and PC21) or saline (SS21 and PS21) were injected by the jugular vein. Analyses were done on days 14 (S14 and P14) and 21 (SS21, PS21, SC21, and PC21) of the protocol. qPCR evaluated the presence of the Y chromosome in the lungs of BMMC recipient animals. Functional residual capacity (FRC), alveolar diameter, cellularity, elastic fiber content, concentrations of TNF-α, IL-1β, IL-6, MIP-2, KC, IFN-γ, apoptosis, mRNA expression of the dual oxidase (DUOX1 and DUOX2), production of H₂O₂ and DUOX activity were evaluated in lung tissue. We did not detect the Y chromosome in recipients' lungs. FRC, alveolar diameter, polymorphonuclear cells (PMN) and levels of KC, MIP-2, and IFN-γ increased in P14 and PS21 groups; the changes in the latter were reverted by BMMC. TNF-α, IL-1β e IL-6 were similar in all groups. The amount of elastic fibers was smaller in P14 and PS21 than in other groups, and BMMC did not increase it in PC21 mice. PS21 animals showed increased DUOX activity and mRNA expression for DUOX1 and 2. Cell therapy reverted the activity of DUOX and mRNA expression of DUOX1. BMMC reduced mRNA expression of DUOX2. Apoptosis index was elevated in PS21 mice, which was reduced by cell therapy in PC21. Static compliance, viscoelastic component of elastance and pressure to overcome viscoelasticity were increased in P14 and PS21 groups. These changes and the high resistive pressure found on day 21 were reverted by BMMC. In conclusion, BMMC showed potent anti-inflammatory, antiapoptotic, antioxidant, and restorative roles in papain-triggered pulmonary emphysema.

miR-34a is involved in CSE-induced apoptosis of human pulmonary microvascular endothelial cells by targeting Notch-1 receptor protein

Background

Abnormal apoptosis of lung endothelial cells has been observed in emphysematous lung tissue and has been suggested to be an important upstream event in the pathogenesis of chronic obstructive pulmonary disease (COPD). Studies have shown that microRNAs (miRNAs) contribute to the pathogenesis of pulmonary diseases by regulating cell apoptosis. The present study was designed to investigate the expression of microRNA-34a (miR-34a) in human pulmonary microvascular endothelial cells (HPMECs) exposed to cigarette smoke extract (CSE), and the potential regulatory role of miR-34a in endothelial cell apoptosis.

Results

Our results showed that the expression of miR-34a was significantly increased in CSE-treated HPMECs, and inhibiting miR-34a attenuated CSE-induced HPMEC apoptosis. Furthermore, expression of Notch-1, a receptor protein in the Notch signalling pathway, was decreased and was inversely correlated with miR-34a expression in HPMECs treated with CSE. Computational miRNA target prediction confirmed that Notch-1 is a target of miR-34a. Luciferase reporter assay further confirmed the direct interaction between miR-34a and the 3’-untranslated region (UTR) of Notch-1. Restoration of Notch-1 pathway was able to partially block the effect of miR-34a on HPMEC apoptosis. These results indicate that Notch-1 is a critical downstream target of miR-34a in regulating the CSE-induced HPMEC apoptosis.

Conclusions

Our results suggest that miR-34a plays a key role in CSE-induced endothelial cell apoptosis by directly regulating its target gene Notch-1 in endothelial cells.

An Increased Proportion of Apoptosis in CD4⁺ T Lymphocytes Isolated from the Peripheral Blood in Patients with Stable Chronic Obstructive Pulmonary Disease

BACKGROUND

The pathophysiology of chronic obstructive pulmonary disease (COPD) includes inflammation, oxidative stress, an imbalance of proteases and antiproteases and apoptosis which has been focused on lately. Abnormal apoptotic events have been demonstrated in both epithelial and endothelial cells, as well as in inflammatory cells including neutrophils and lymphocytes in the lungs of COPD patients. An increased propensity of activated T lymphocytes to undergo apoptosis has been observed in the peripheral blood of COPD patients. Therefore, the apoptosis of T lymphocytes without activating them was investigated in this study.

METHODS

Twelve control subjects, 21 stable COPD patients and 15 exacerbated COPD patients were recruited in the study. The T lymphocytes were isolated from the peripheral blood using magnetically activated cell sorting. Apoptosis of the T lymphocytes was assessed with flow cytometry using Annexin V and 7-aminoactinomycin D. Apoptosis of T lymphocytes at 24 hours after the cell culture was measured so that the T lymphocyte apoptosis among the control and the COPD patients could be compared.

RESULTS

Stable COPD patients had increased rates of CD4⁺ T lymphocyte apoptosis at 24 hours after the cell culture, more than the CD4⁺ T lymphocyte apoptosis which appeared in the control group, while the COPD patients with acute exacerbation had an amplified response of CD4⁺ T lymphocyte apoptosis as well as of CD8⁺ T lymphocyte apoptosis at 24 hours after the cell culture.

CONCLUSION

Stable COPD patients have more apoptosis of CD4⁺ T lymphocytes, which can be associated with the pathophysiology of COPD in stable conditions.

The protective effect of PRMT6 overexpression on cigarette smoke extract-induced murine emphysema model

Background

Cigarette smoke exposure is the most common risk factor for emphysema, which is one of the major pathologies of COPD. Protein arginine methyltransferase 6 (PRMT6) is a nuclear enzyme that specially catalyzes dimethylation of R2 in histone H3 (H3R2me2a). H3R2me2a prevents trimethylation of H3K4 (H3K4me3), which is located in the transcription start sites of genes in mammalian genomes. We attempted to determine the expression of PRMT6 in human samples, and investigate whether the upregulation of PRMT6 expression can attenuate the development of cigarette smoke extract (CSE)-induced emphysema. Further experiments were performed to elucidate the molecular mechanisms involved.

Materials and methods

Human lung tissues were obtained from patients undergoing pneumonectomy for benign pulmonary lesions. BALB/c mice were treated with lentiviral vectors intratracheally and injected with CSE three times. The protein expression of PRMT6, H3R2me2a, and H3K4me3 in human and mouse samples, as well as B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), and endothelial nitric oxide synthase (eNOS) in mice were detected in lung homogenates by Western blotting. The mRNA expression of cyclooxygenase-2, interleukin-6, Bcl-2, Bax, and eNOS in mice was measured by quantitative real-time polymerase chain reaction.

Results

The expression of PRMT6 was significantly downregulated in the pulmonary parenchyma in smokers with COPD as well as in mice treated with CSE. Overexpression of PRMT6 was detected in the CSE + Lenti-PRMT6 group of mice, which reversed the expression of H3R2me2a and H3K4me3. Inflammation, apoptosis, and oxidative stress levels were severe in the CSE-treated emphysema mice compared with the control group, which was inhibited by the overexpression of PRMT6.

Conclusion

The overexpression of PRMT6 might inhibit inflammation, apoptosis, and oxidative stress in CSE-induced emphysema mediated by H3R2me2a.

Posttranscriptional control of airway inflammation

Acute inflammation in the lungs is a vital protective response, efficiently and swiftly eliminating inciters of tissue injury. However, in respiratory diseases characterized by chronic inflammation, such as chronic obstructive pulmonary disease and asthma, enhanced expression of inflammatory mediators leads to tissue damage and impaired lung function. Although transcription is an essential first step in the induction of proinflammatory genes, tight regulation of inflammation requires more rapid, flexible responses. Increasing evidence shows that such responses are achieved by posttranscriptional mechanisms directly affecting mRNA stability and translation initiation. RNA-binding proteins, microRNAs, and long noncoding RNAs interact with messenger RNA and each other to impact the stability and/or translation of mRNAs implicated in lung inflammation. Recent research has shown that these biological processes play a central role in the pathogenesis of several important pulmonary conditions. This review will highlight several posttranscriptional control mechanisms that influence lung inflammation and the known associations of derangements in these mechanisms with common respiratory diseases. WIREs RNA 2018, 9:e1455. doi: 10.1002/wrna.1455 This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA Turnover and Surveillance > Regulation of RNA Stability.

Transcriptomic Analysis of Lung Tissue from Cigarette Smoke-Induced Emphysema Murine Models and Human Chronic Obstructive Pulmonary Disease Show Shared and Distinct Pathways

Although cigarette smoke (CS) is the primary risk factor for chronic obstructive pulmonary disease (COPD), the underlying molecular mechanisms for the significant variability in developing COPD in response to CS are incompletely understood. We performed lung gene expression profiling of two different wild-type murine strains (C57BL/6 and NZW/LacJ) and two genetic models with mutations in COPD genome-wide association study genes (HHIP and FAM13A) after 6 months of chronic CS exposure and compared the results to human COPD lung tissues. We identified gene expression patterns that correlate with severity of emphysema in murine and human lungs. Xenobiotic metabolism and nuclear erythroid 2-related factor 2-mediated oxidative stress response were commonly regulated molecular response patterns in C57BL/6, Hhip^+/-, and Fam13a^-/- murine strains exposed chronically to CS. The CS-resistant Fam13a^-/- mouse and NZW/LacJ strain revealed gene expression response pattern differences. The Fam13a^-/- strain diverged in gene expression compared with C57BL/6 control only after CS exposure. However, the NZW/LacJ strain had a unique baseline expression pattern, enriched for nuclear erythroid 2-related factor 2-mediated oxidative stress response and xenobiotic metabolism, and converged to a gene expression pattern similar to the more susceptible wild-type C57BL/6 after CS exposure. These results suggest that distinct molecular pathways may account for resistance to emphysema. Surprisingly, there were few genes commonly modulated in mice and humans. Our study suggests that gene expression responses to CS may be largely species and model dependent, yet shared pathways could provide biologically significant insights underlying individual susceptibility to CS.

Decrease in an anti-ageing factor, growth differentiation factor 11, in chronic obstructive pulmonary disease

RATIONALE

Cellular senescence is observed in the lungs of patients with COPD and may contribute to the disease pathogenesis. Growth differentiation factor 11 (GDF11) belongs to the transforming growth factor β superfamily and was recently reported to be a circulating protein that may have rejuvenating effects in mice. We aimed to investigate the amounts of GDF11 in the plasma and the lungs of patients with COPD and elucidate the possible roles of GDF11 in cellular senescence.

METHODS

The plasma levels of GDF11 were investigated in two separate cohorts by western blotting. The localisation and expression of GDF11 in the lungs were investigated by immunohistochemistry and quantitative reverse transcription PCR, respectively. The effects of GDF11 on both cigarette smoke extract (CSE)-induced cellular senescence in vitro and on elastase-induced cellular senescence in vivo were investigated.

RESULTS

The levels of plasma GDF11 in the COPD group were decreased compared with the control groups in the two independent cohorts. The levels of plasma GDF11 were significantly positively correlated with pulmonary function data. The mRNA expression of GDF11 in mesenchymal cells from the COPD group was decreased. Chronic exposure to CSE decreased the production of GDF11. Treatment with GDF11 significantly inhibited CSE-induced cellular senescence and upregulation of inflammatory mediators, partly through Smad2/3 signalling in vitro. Daily GDF11 treatment attenuated cellular senescence and airspace enlargement in an elastase-induced mouse model of emphysema.

CONCLUSIONS

The decrease in GDF11 may be involved in the cellular senescence observed in COPD.

β2-Microglobulin participates in development of lung emphysema by inducing lung epithelial cell senescence

β₂-Microglobulin (β₂M), the light chain of the major histocompatibility complex class I (MHC I), has been identified as a proaging factor and is involved in the pathogenesis of neurodegenerative disorders by driving cognitive and regenerative impairments. However, little attention has focused on the effect of β₂M in the development of lung emphysema. Here, we found that concentrations of β₂M in plasma were significantly elevated in patients with lung emphysema than those in normal control subjects (1.89 ± 0.12 vs. 1.42 ± 0.06 mg/l, P < 0.01). Moreover, the expression of β₂M was significantly higher in lung tissue of emphysema (39.90 ± 1.97 vs. 23.94 ± 2.11%, P < 0.01). Immunofluorescence showed that β₂M was mainly expressed in prosurfactant protein C-positive (pro-SPC⁺) alveolar epithelial cells and CD14⁺ macrophages. Exposure to recombinant human β₂M and cigarette smoke extract (CSE) in vitro enhanced cellular senescence and inhibited proliferation of A549 cells, which was partially reversed by the presence of anti-β₂M antibody. However, anti-β₂M antibody did not attenuate the elevated production of IL-1β, IL-6, and TNF-α in A549 cells that were exposed to CSE. Immunofluorescence showed that colocalization of β₂M, and the hemochromatosis gene (HFE) protein was observed on A549 cells. These data suggest β₂M might participate in the development of lung emphysema through induction of lung epithelial cell senescence and inhibition.

Adipose stem cell-derived nanovesicles inhibit emphysema primarily via an FGF2-dependent pathway

Cell therapy using stem cells has produced therapeutic benefits in animal models of COPD. Secretory mediators are proposed as one mechanism for stem cell effects because very few stem cells engraft after injection into recipient animals. Recently, nanovesicles that overcome the disadvantages of natural exosomes have been generated artificially from cells. We generated artificial nanovesicles from adipose-derived stem cells (ASCs) using sequential penetration through polycarbonate membranes. ASC-derived artificial nanovesicles displayed a 100 nm-sized spherical shape similar to ASC-derived natural exosomes and expressed both exosomal and stem cell markers. The proliferation rate of lung epithelial cells was increased in cells treated with ASC-derived artificial nanovesicles compared with cells treated with ASC-derived natural exosomes. The lower dose of ASC-derived artificial nanovesicles had similar regenerative capacity compared with a higher dose of ASCs and ASC-derived natural exosomes. In addition, FGF2 levels in the lungs of mice treated with ASC-derived artificial nanovesicles were increased. The uptake of ASC-derived artificial nanovesicles was inhibited by heparin, which is a competitive inhibitor of heparan sulfate proteoglycan that is associated with FGF2 signaling. Taken together, the data indicate that lower doses of ASC-derived artificial nanovesicles may have beneficial effects similar to higher doses of ASCs or ASC-derived natural exosomes in an animal model with emphysema, suggesting that artificial nanovesicles may have economic advantages that warrant future clinical studies.

Inhaled resveratrol treatments slow ageing-related degenerative changes in mouse lung

BACKGROUND

Lung ageing, a significant risk factor for chronic human lung diseases such as COPD and emphysema, is characterised by airspace enlargement and decreasing lung function. Likewise, in prematurely ageing telomerase null (terc-/-) mice, p53 stabilisation within diminishing numbers of alveolar epithelial type 2 cells (AEC2) accompanies reduced lung function. Resveratrol (RSL) is a plant phytoalexin that has previously showed efficacy in enhancing invertebrate longevity and supporting mammalian muscle metabolism when delivered orally. Here, we tested whether inhaled RSL could protect young, terc-/- mice from accelerated ageing of the lung.

METHODS

terc-/- mice aged 2 months inhaled 1 mg/kg RSL that was instilled intratracheally once per month for 3 months. One month after the last inhalation, whole lung function, structure and cellular DNA damage were evaluated and AEC2 survival was assessed by western blotting for survival pathway gene expression.

RESULTS

RSL treatments delayed the loss of lung compliance (p<0.05), maintained lung structure (p<0.001) and blocked parenchymal cell DNA damage as measured by TdT Nick-End Labeling (TUNEL). RSL, a known agonist of deacetylase SIRT1, supported AEC2 survival by stimulating SIRT1 expression, promoting p53 destabilisation and decreasing Bax expression and by maintaining expression levels of Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), activated p-Akt and p-Mdm2 and inactivated Phospho-Phosphatase and tensin homolog (p-PTEN).

CONCLUSIONS

RSL prophylaxis by inhalation is a potential approach for slowing ageing-related deterioration of lung function and structure by maintaining AEC2 integrity.

The role of cyclooxygenase-2 in the protection against apoptosis in vascular endothelial cells induced by cigarette smoking

BACKGROUND

Apoptosis has been demonstrated to be an important upstream event in the pathogenesis of chronic obstructive pulmonary disease (COPD). Cyclooxygenase-2 (COX-2) seems to be biologically relevant in COPD. However, the role of COX-2 in the apoptosis in vascular endothelial cells induced by cigarette smoke extract (CSE) remains to be elucidated. Our recent study found that the prostacyclin, one of the COX products in the microvascular endothelium, inhibited apoptosis in the emphysematous lungs of rats induced by CSE. In order to clarify the role of COX-2 in the apoptosis of vascular endothelial cells induced by CSE, we performed the present experiment to elucidate it.

METHODS

Twenty surgical lung specimens were obtained from 6 patients with COPD, 7 smoking controls and seven nonsmoking controls. The apoptotic index (AI) and COX-2 protein expression were detected in lung tissues. To further investigate the effects of CSE on the apoptosis and COX-2 expression in a human vascular endothelial cell line, the apoptosis rate and COX-2 expression were examined in human umbilical vein endothelial cells (ECV304) under exposure to varied concentrations of CSE as well as under exposure to 5.0% CSE for varied durations. Repeatedly, the apoptosis rate and COX-2 expression in ECV304 cells under 5.0% CSE were examined after exposing to varied concentrations of celecoxib, a highly selective COX-2 inhibitor.

RESULTS

Significantly increased AI and expression of COX-2 were found both in the lungs of patients with COPD and smoking controls compared with nonsmoking controls. The CSE induced apoptosis in ECV304 cells in means of both dose-dependent and time-dependent manners. The COX-2 was slightly expressed in the cells after exposing to 5% CSE for 3 and 6 h, and markedly expressed after the exposure time for 9 and 12 h, but vanished after 24 h of the exposure. Of interest, with the completely block of the COX-2 expression by celecoxib at 50.0 µmol/L, the apoptosis rate was markedly increased again in ECV304 cells under exposure to 5.0% CSE.

CONCLUSIONS

Endothelial cell apoptosis and the expression of COX-2 protein were increased in both COPD patients and CSE-induced vascular endothelial cells. Of interest, it seems that the COX-2 probably had a protective role against the apoptosis in the vascular endothelial cells induced by cigarette smoking.