Intratracheal transplantation of endothelial progenitor cells attenuates smoking-induced COPD in mice

The effect of thyme essential oil and endothelial progenitor stem cells on lipopolysaccharide-induced sepsis in C57BL/6 mice

Sepsis is a potentially fatal syndrome related to severe systemic inflammation developed by infection. Despite different antimicrobial therapies, morbidity and mortality rates remain high. Herbs along with cell therapy have been introduced as a promising option to improve the symptoms of sepsis. The present study aimed to evaluate the therapeutic effect of simultaneous administration of thyme essential oil (TEO) and endothelial progenitor stem cells (EPCs) on lipopolysaccharide (LPS)-induced sepsis in C57BL/6 mice. Sepsis was induced in C57Bl/6J mice by intraperitoneal injection of LPS, followed 2 h later by an intravenous injection of EPCs or oral administration of TEO or simultaneous administration of TEO and EPCs. After 10 days, the complete blood cell, renal and liver factors, serum levels of inflammatory cytokines, and angiogenic factors were measured. Simultaneous treatment with EPCs and TEO significantly increased the survival of mice with sepsis and modulated the inflammatory response by reducing the serum levels of pro-inflammatory cytokines. Moreover, this treatment significantly reduced the level of white blood cells and neutrophils and increased the number of red blood cells, the percentage of hematocrit, and hemoglobin. The combination of TEO with EPCs decreased organ injuries and was assessed by lower levels of the liver enzymes alanine aminotransferase and aspartate aminotransferase compared to the sepsis group. Administration of EPCs and TEO also significantly improved angiogenic factors, lung function, and toll-like receptor 4 expression. EPCs in combination with TEO increase survival in the LPS-induced sepsis mice model by acting on several targets. Thus, the combination of TEO with EPCs can be a feasible approach for the future clinical treatment and control of sepsis.

LRG1 promotes the apoptosis of pulmonary microvascular endothelial cells through KLK10 in chronic obstructive pulmonary disease

INTRODUCTION

Cigarette smoking is one of the most important causes of COPD and could induce the apoptosis of pulmonary microvascular endothelial cells (PMVECs). The conditional knockout of LRG1 from endothelial cells reduced emphysema in mice. However, the mechanism of the deletion of LRG1 from endothelial cells rescued by cigarette smoke (CS) induced emphysema remains unclear. This research aimed to demonstrate whether LRG1 promotes the apoptosis of PMVECs through KLK10 in COPD.

METHODS

Nineteen patients were divided into three groups: control non-COPD (n=7), smoker non-COPD (n=7), and COPD (n=5). The emphysema mouse model defined as the CS exposure group was induced by CS exposure plus cigarette smoke extract (CSE) intraperitoneal injection for 28 days. Primary PMVECs were isolated from the mouse by magnetic bead sorting method via CD31-Dynabeads. Apoptosis was detected by western blot and flow cytometry.

RESULTS

LRG1 was increased in lung tissue of COPD patients and CS exposure mice, and CSE-induced PMVECs apoptosis model. KLK10 was over-expressed in lung tissue of COPD patients and CS exposure mice, and CSE-induced PMVECs apoptosis model. LRG1 promoted apoptosis in PMVECs. LRG1 knockdown reversed CSE-induced apoptosis in PMVECs. The mRNA and protein expression of KLK10 were increased after over-expressed LRG1 in PMVECs isolated from mice. Similarly, both the mRNA and protein levels of KLK10 were decreased after LRG1 knockdown in PMVECs. The result of co-immunoprecipitation revealed a protein-protein interaction between LRG1 and KLK10 in PMVECs. KLK10 promoted apoptosis via the down-regulation of Bcl-2/Bax in PMVECs. KLK10 knockdown could reverse CSE-induced apoptosis in PMVECs.

CONCLUSIONS

LRG1 promotes apoptosis via up-regulation of KLK10 in PMVECs isolated from mice. KLK10 promotes apoptosis via the down-regulation of Bcl-2/Bax in PMVECs. There was a direct protein-protein interaction between LRG1 and KLK10 in PMVECs. Our novel findings provide insights into the understanding of LRG1/KLK10 function as a potential molecule in COPD.

PU.1 alleviates the inhibitory effects of cigarette smoke on endothelial progenitor cell function and lung-homing through Wnt/β-catenin and CXCL12/CXCR4 pathways

INTRODUCTION

Endothelial progenitor cells (EPCs) dysfunction is involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). The transcription factor PU.1 is essential for the maintenance of stem/progenitor cell homeostasis. However, the role of PU.1 in COPD and its effects on EPC function and lung-homing, remain unclear. This study aimed to explore the protective activity of PU.1 and the underlying mechanisms in a cigarette smoke extract (CSE)-induced emphysema mouse model.

METHODS

C57BL/6 mice were treated with CSE to establish a murine emphysema model and injected with overexpressed PU.1 or negative control adeno-associated virus. Morphometry of lung slides, lung function, and apoptosis of lung tissues were evaluated. Immunofluorescence co-localization was used to analyze EPCs homing into the lung. Flow cytometry was performed to detect EPC count in lung tissues and bone marrow (BM). The angiogenic ability of BM-derived EPCs cultured in vitro was examined by tube formation assay. We determined the expression levels of PU.1, β-catenin, C-X-C motif ligand 12 (CXCL12), C-X-C motif receptor 4 (CXCR4), stem cell antigen-1 (Sca-1), and stemness genes.

RESULTS

CSE exposure significantly reduced the expression of PU.1 in mouse lung tissues, BM, and BM-derived EPCs. PU.1 overexpression attenuated CSE-induced emphysematous changes, lung function decline, and apoptosis. In emphysematous mice, PU.1 overexpression markedly reversed the decreased proportion of EPCs in BM and promoted the lung-homing of EPCs. The impaired angiogenic ability of BM-derived EPCs induced by CSE could be restored by the overexpression of PU.1. In addition, PU.1 upregulation evidently reversed the decreased expression of β-catenin, CXCL12, CXCR4, Scal-1, and stemness genes in mouse lung tissues, BM, and BM-derived EPCs after CSE exposure.

CONCLUSIONS

PU.1 alleviates the inhibitory effects of CSE on EPC function and lung-homing via activating the canonical Wnt/β-catenin pathway and CXCL12/CXCR4 axis. While further research is needed, our research may indicate a potential therapeutic target for COPD patients.

Endothelial progenitor cells systemic administration alleviates multi-organ senescence by down-regulating USP7/p300 pathway in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) has impacted approximately 390 million people worldwide and the morbidity is increasing every year. However, due to the poor treatment efficacy of COPD, exploring novel treatment has become the hotpot of study on COPD. Endothelial progenitor cells (EPCs) aging is a possible molecular way for COPD development. We aimed to explore the effector whether intravenous administration of EPCs has therapeutic effects in COPD mice.

METHODS

COPD mice model was induced by cigarette smoke exposure and EPCs were injected intravenously to investigate their effects on COPD mice. At day 127, heart, liver, spleen, lung and kidney tissues of mice were harvested. The histological effects of EPCs intervention on multiple organs of COPD mice were detected by morphology assay. Quantitative real-time PCR and Western blotting were used to detect the effect of EPCs intervention on the expression of multi-organ senescence-related indicators. And we explored the effect of EPCs systematically intervening on senescence-related USP7/p300 pathway.

RESULTS

Compared with COPD group, senescence-associated β-galactosidase activity was decreased, protein and mRNA expression of p16 was down-regulated, while protein and mRNA expression of cyclin D1 and TERT were up-regulated of multiple organs, including lung, heart, liver, spleen and kidney in COPD mice after EPCs system intervention. But the morphological alterations of the tissues described above in COPD mice failed to be reversed. Mechanistically, EPCs systemic administration inhibited the expression of mRNA and protein of USP7 and p300 in multiple organs of COPD mice, exerting therapeutic effects.

CONCLUSIONS

EPCs administration significantly inhibited the senescence of multiple organs in COPD mice via down-regulating USP7/p300 pathway, which presents a possibility of EPCs therapy for COPD.

Transplantation of Endothelial Progenitor Cells: Summary and prospect

Endothelial Progenitor Cells (EPCs) are precursor cells of endothelial cells (ECs), which can differentiate into vascular ECs, protect from endothelial dysfunction and tissue ischemia, and reduce vascular hyperplasia. Due to these functions, EPCs are used as a candidate cell source for transplantation strategies. In recent years, a great progress was achieved in EPCs biology research, and EPCs transplantation has become a research hotspot. At present, transplanted EPCs have been used to treat ischemic diseases due to their powerful vasculogenesis and beneficial paracrine effects. Although EPCs transplantation has been proved to play an important role, the clinical application of EPCs still faces many challenges. This review briefly summarized the basic characteristics of EPCs, the process of EPCs transplantation promoting the healing of ischemic tissue, and the ways to improve the efficiency of EPCs transplantation. In addition, the application of EPCs in neurological improvement, cardiovascular and respiratory diseases and the challenges and problems in clinical application of EPCs were also discussed. In the end, the application of EPCs transplantation in regenerative medicine and tissue engineering was discussed.

Long noncoding RNA HOTAIR facilitates pulmonary vascular endothelial cell apoptosis via DNMT1 mediated hypermethylation of Bcl-2 promoter in COPD

BACKGROUND

To study the regulatory effect of Long non-coding RNA (LncRNA) HOX transcript antisense RNA (HOTAIR) on pulmonary vascular endothelial cell (HPVEC) apoptosis and determine whether the HOTAIR facilitate HPVEC apoptosis via DNMT1 mediated hypermethylation of Bcl-2 promoter in chronic obstructive pulmonary disease (COPD).

METHODS

LncRNA array was used to measure the differentially expressed lncRNAs in COPD and non-COPD lung tissues. Expression of HOTAIR in COPD patient lungs and cigarette smoke extract (CSE)-induced HPVEC was assessed by qRT-PCR. The location of HOTAIR was determined in COPD patient lungs and HPVEC by RNA in situ hybridization (RNA-ISH). The emphysema mouse model and HOTAIR knockdown mice were each established by inhaling cigarette smoke or intratracheal lentiviral vectors instillation. The dysregulation of DNA methyltransferase enzyme 1 (DNMT1), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax) and Cleaved-caspase 3 protein expression were detected by Western blotting. HOTAIR, DNMT1, Bcl-2 and Bax mRNA expression were measured by quantitative real-time polymerase chain reaction. TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assays were used to assess apoptotic ratio in mice and CSE-induced HPVEC. Methylation-specific PCR (MSP) assay was conducted to observe the alterations in the methylation of the Bcl-2 promoter in specimens. RNA pull-down assay was used for analysis of the correlation between HOTAIR and DNMT1.

RESULTS

The expression levels of the HOTAIR were up-regulated in COPD patient lungs and CSE-induced HPVEC. HPVEC apoptosis with down-regulated Bcl-2 expression, increased promoter methylation, DNMT1, Bax and Cleaved-caspase 3 expression was found in emphysema mouse model and CSE-induced HPVEC. Knockdown HOTAIR can attenuate cell apoptosis and emphysema via DNMT1 mediated hypermethylation of Bcl-2 promoter in mice. In vitro, HOTAIR can aggravate the apoptosis of CSE-exposed HPVEC. DNMT1 was a target of HOTAIR and had a positive correlation with HOTAIR.

CONCLUSION

HOTAIR facilitates HPVEC apoptosis via DNMT1 mediated hypermethylation of Bcl-2 promoter in COPD, and attenuating the expression of HOTAIR may be a new therapy to prevent COPD.

Chronic Obstructive Pulmonary Disease and the Cardiovascular System: Vascular Repair and Regeneration as a Therapeutic Target

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and encompasses chronic bronchitis and emphysema. It has been shown that vascular wall remodeling and pulmonary hypertension (PH) can occur not only in patients with COPD but also in smokers with normal lung function, suggesting a causal role for vascular alterations in the development of emphysema. Mechanistically, abnormalities in the vasculature, such as inflammation, endothelial dysfunction, imbalances in cellular apoptosis/proliferation, and increased oxidative/nitrosative stress promote development of PH, cor pulmonale, and most probably pulmonary emphysema. Hypoxemia in the pulmonary chamber modulates the activation of key transcription factors and signaling cascades, which propagates inflammation and infiltration of neutrophils, resulting in vascular remodeling. Endothelial progenitor cells have angiogenesis capabilities, resulting in transdifferentiation of the smooth muscle cells via aberrant activation of several cytokines, growth factors, and chemokines. The vascular endothelium influences the balance between vaso-constriction and -dilation in the heart. Targeting key players affecting the vasculature might help in the development of new treatment strategies for both PH and COPD. The present review aims to summarize current knowledge about vascular alterations and production of reactive oxygen species in COPD. The present review emphasizes on the importance of the vasculature for the usually parenchyma-focused view of the pathobiology of COPD.

Bone marrow stem cells therapy alleviates vascular injury in a chronic obstructive pulmonary disease‑obstructive sleep apnea overlap syndrome rat model

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are highly prevalent potential risk factors for systemic disease. Previous studies have reported that COPD and OSA are major independent risk factors for cardio- or cerebrovascular diseases. The present study aimed to investigate the role of bone marrow mesenchymal stem cells (BMSCs) on vascular injury in a COPD-OSA overlap syndrome (OS) rat model. Rats were randomly divided into three groups: Sham, OS model and BMSC. BMSC localization in major organs was detected via confocal laser fluorescence microscopy, and the aortic tissue pathological changes and related genes were measured using hematoxylin & eosin and Masson staining. Genes associated with vascular endothelial cell injury, including endothelin 1, vascular cell adhesion molecule 1 and endothelial nitric oxide synthase, were detected via reverse transcription-quantitative PCR and western blotting. Apoptosis of vascular endothelial cells was detected using TUNEL and immunofluorescence assays. The endothelial cell marker CD31 in injured vessels was analyzed via immunohistochemistry. BMSCs migrated into the heart, liver, spleen, lung, kidney, brain and aorta in the OS model. The green fluorescence expression of BMSCs demonstrated the highest level in the lung, followed by the aorta. Aortic tissue had a more severe vascular injury and increased apoptosis in the model group compared with the BMSC group. Vascular endothelial cell apoptosis was decreased in the BMSC group compared with the model group. The findings suggested that BMSCs could repair vascular injury by inhibiting endothelial cell damage and apoptosis. These data provide a theoretical basis for the treatment of cardiovascular diseases caused by OS with BMSCs.

Oxidative stress mediates the apoptosis and epigenetic modification of the Bcl-2 promoter via DNMT1 in a cigarette smoke-induced emphysema model

Background

Emphysema is a crucial pathological characteristic of chronic obstructive pulmonary disease (COPD). Oxidative stress, apoptosis and epigenetic mechanisms contribute to the pathogenesis of emphysema. However, an attempt to accurately identify whether these mechanisms interact with each other and how they are triggered has never been conducted.

Method

The total reactive oxygen species (ROS) level, pulmonary apoptosis and B-cell lymphoma/leukemia-2 (Bcl-2) expression, an apoptosis regulator, were detected in samples from COPD patients. Bisulfite sequencing PCR (BSP) was conducted to observe the alterations in the methylation of the Bcl-2 promoter in specimens. The dysregulation of DNA methyltransferase enzyme 1 (DNMT1), a vital DNA methyltransferase enzyme, in the lungs of patients was confirmed through western blotting. To find out interactions between oxidative stress and DNA methylation in emphysema, mouse models were built with antioxidant treatment and DNMT1 silencing, and were examined with the pulmonary apoptosis, Bcl-2 and DNMT1 levels, and epigenetic alterations of Bcl-2.

Results

Higher ROS levels and pulmonary apoptosis were observed in COPD patients than in healthy controls. Downregulated Bcl-2 expression with increased promoter methylation and DNMT1 protein expression was found in COPD patients. Antioxidant treatment reduced the level of ROS, DNMT1 protein and emphysematous progression in the smoking models. Following DNMT1 blockade, smoking models showed improved lung function, pulmonary apoptosis, emphysematous progression, and increased Bcl-2 protein level with less promoter methylation than emphysema mice.

Conclusion

Cigarette-induced oxidative stress mediates pulmonary apoptosis and hypermethylation of the Bcl-2 promoter in emphysema models through DNMT1.

Stem Cells in Lungs

The respiratory system plays an essential role for human life. This system (like all others) undergoes physiological regeneration due to many types of stem cells found both in the respiratory tract itself and in the alveoli. The stem cell hierarchy is very extensive due to their variety in the lungs and is still not completely understood.The best described lung stem cells are alveolar type II cells, which as progenitor lung stem cells are precursors of alveolar type I cells, i.e., cells that perform gas exchange in the lungs. These progenitor stem cells, which reside in alveoli corners, express high levels of surfactant protein C (SFTPC). Despite the fact that type II pneumocytes occupy only 7-10% of the lung surface, there are almost twice as many as alveolar type I cells occupying almost 95% of the surface.Other stem cells making up the lung regenerative potential have also been identified in the lungs. Both endothelial, mesodermal, and epithelial stem cells are necessary for the lungs to function properly and perform their physiological functions.The lungs, like all other organs, undergo an aging process. As a result of this process, not only the total number of cells changes, the percentage of particular types of cells, but also their efficiency is reduced. With age, the proliferative potential of lung stem cells also decreases, not just their number. This brings about the need to increase the intensity of research in the field of regenerative medicine.

Melatonin protects against COPD by attenuating apoptosis and endoplasmic reticulum stress via upregulating SIRT1 expression in rats

The apoptosis of bronchial and alveolar epithelial cells plays a key role in chronic obstructive pulmonary disease (COPD). The endoplasmic reticulum (ER) stress induced by cigarette smoke contributes to apoptosis. Previous studies demonstrated that melatonin prevented the development of COPD. In addition, silent information regulator 1 (SIRT1) had a protective effect against COPD. However, it remains unclear whether SIRT1 is involved in the protection of melatonin against COPD. In this study, 32 male Wistar rats were randomly assigned to 4 groups: Control, COPD, COPD + Mel, and COPD + Mel + EX527. Rats were challenged with cigarette smoke and lipopolysaccharide with or without melatonin or EX527 (a selective inhibitor of SIRT1). The lung histopathology, apoptotic index, as well as the protein expressions of cleaved caspase-3, SIRT1, C/EBP homologous protein, and caspase-12 in the lung tissues were measured. These results demonstrated that melatonin attenuated apoptosis and ER stress in the lung tissues of rats with COPD. In addition, melatonin increased SIRT1 expression in lung tissues of rats with COPD, while inhibition of SIRT1 by EX527 upregulated ER stress and abolished the protective effect of melatonin against apoptosis. In conclusion, these findings suggested that melatonin protected against COPD by attenuating apoptosis and ER stress via upregulating SIRT1 expression in rats.

Heparin-binding EGF-like growth factor attenuates lung inflammation and injury in a murine model of pulmonary emphysema

Pulmonary inflammation and progressive lung destruction are the major causes of chronic obstructive pulmonary disease (COPD), resulting in emphysema and irreversible pulmonary dysfunction. Heparin-binding EGF-like growth factor (HB-EGF), is known to play a protective role in the process of various inflammatory diseases. However, its effect on COPD is poorly understood. This study was designed to determine the effect of HB-EGF on lung inflammation and injury in a murine model of pulmonary emphysema. HB-EGF promoted percent survival and body weight, attenuated lung injury, inflammatory cells, and cytokines infiltration, and prevented lung function decline. Additionally, treatment of rHB-EGF suppressed the nuclear translocation of nuclear factor κB (NF-κB)/p65, decreased TUNEL-positive cells and the expression of caspase 3, and increased the expression of PCNA, HB-EGF, and EGF receptor (EGFR). We conclude that HB-EGF attenuates lung inflammation and injury, probably through the activation of EGFR, followed by suppression of NF-ΚB signalling, promotion of cell proliferation, and inhibition of apoptosis.