Dynamic evolution of emphysema and airway remodeling in two mouse models of COPD

METTL16 controls airway inflammations in smoking-induced COPD via regulating glutamine metabolism

The persistent airway inflammation is the main characteristic of chronic obstructive pulmonary disease (COPD), typically caused by an indoor environment pollution cigarette smoke (CS). METTL16 is an m6A methyltransferase that has been proven to be closely associated with the occurrence of various diseases. However, its exact role in smoking-induced COPD remains to be investigated. In this study, we found that the level of METTL16 was aberrantly decreased in lung tissues of COPD smokers. Similarly, murine model induced by CS and lung epithelial cell model induced by cigarette smoke extract (CSE) also confirmed this discovery. Moreover, in the Mettl16-deficient (Mettl16+/-) mice challenged with CS, airway inflammation was aggravated. To identify the potential target genes and regulatory pathways through METTL16, methylated RNA immunoprecipitation sequencing (meRIP-seq), RNA sequencing (RNA-seq) and metabolomic profiling were used. Knockdown of METTL16 significantly reduced the stability of glutamic-oxaloacetic transaminase 2 (GOT2) and downregulated its expression through m6A modification, while reprogramed glutamine metabolism in lung epithelial cells. Significant reduction in inflammation levels was observed in the 3-month COPD murine model fed a glutamine-supplemented diet. Mechanistically, METTL16 could regulate lung epithelial mitochondrial function by participating in the reprogramming of glutamine metabolism. Our study characterized the role of the METTL16/GOT2/glutamine axis in the occurrence and development of COPD, and emphasized the potential value of METTL16 and glutamine in the therapy of chronic airway inflammation in smoking-induced COPD.

A novel chronic obstructive pulmonary disease mouse model induced by intubation-mediated intratracheal co-administration of porcine pancreatic elastase and lipopolysaccharide

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a significant respiratory disorder in humans characterized by persistent airway constriction or obstruction due to chronic bronchitis and pulmonary emphysema. Various methods of inducing COPD in mouse models are frequently used in COPD research; however, these cannot completely reproduce histopathologic lesions. This study aimed to establish a new COPD mouse model that reproduces histopathological lesions closely resembling clinical COPD within a shorter induction time.

METHODS

The new strategy involved the co-administration of porcine pancreatic elastase (PPE) and lipopolysaccharide (LPS), with PPE intended to induce pulmonary emphysema and LPS intended to induce chronic bronchitis. Male C57BL/6J mice were administered PPE (8 U/kg) on days 0 and 3 and LPS (400 µg/kg) on days 6, 9, 12, and 15. Each administration was performed using a noninvasive intubation-mediated intratracheal instillation method with a laryngoscope.

RESULTS

Postmortem examination on day 22 revealed that pulmonary emphysema and chronic bronchitis were simultaneously induced in 90.91% of the lung lobes. Molecular studies revealed higher messenger ribonucleic acid (mRNA) expression levels of interleukin-6(IL-6) and matrix metalloproteinase-12(MMP-12) associated with the pathogenesis of COPD.

CONCLUSION

A new method was developed to establish a COPD mouse model that displays a more severe representation of the histopathological findings of clinical COPD than previous COPD models. It also reduces the time required for model induction. This newly developed COPD mouse model is expected to be a valuable tool for the pathogenesis and therapeutic research on human COPD.

YAP O-GlcNAcylation contributes to corneal epithelial cell ferroptosis under cigarette smoke exposure

Cigarette smoke (CS) is an important indoor air pollutant associated with an increased risk of ocular surface disease. As the eye's outermost layer, the cornea is highly sensitive to air pollutants like CS. However, the specific mechanisms linking CS exposure to corneal dysfunction have not been fully elucidated. In the present study, we found that CS exposure damages corneal epithelial cells, accompanied by increased iron (Fe2+) levels and lipid peroxidation, both hallmarks of ferroptosis. Ferroptosis inhibitors, including Ferrostatin-1 (Fer-1) and Deferoxamine mesylate (DFO), protect against CS-induced cell damage. To understand the underlying mechanisms, we investigated how CS affects iron and lipid metabolism. Our results showed that CS could upregulate intracellular iron levels by increasing TFRC expression and promote lipid peroxidation by increasing ACSL4 expression. Silencing ACSL4 or TFRC expression prevented CS-induced ferroptosis. Furthermore, we found that the upregulation of TFRC and ACSL4 was driven by increased YAP transcription. Pharmacological or genetic inhibition of YAP effectively prevented corneal epithelial cell ferroptosis under CS stimulation. Additionally, our results suggest that CS exposure could increase O-GlcNAc transferase activity, leading to YAP O-GlcNAcylation. This glycosylation of YAP interfered with its K48-linked ubiquitination, resulting in YAP stabilization. Collectively, we found that CS exposure induces corneal epithelial cell ferroptosis via the YAP O-GlcNAcylation, and provide evidence that CS exposure is a strong risk factor for ocular surface disease.

SMAD4 promotes EMT in COPD airway remodeling induced by cigarette smoke through interaction with O-GlcNAc transferase

Cigarette smoke (CS) is a prevalent chemical indoor air contaminant known to be the primary cause of EMT during airway remodeling in COPD. While some evidence indicates the involvement of SMAD4 in EMT across certain diseases, its specific role in CS-induced EMT in airway remodeling associated with COPD is not established. In our research, we observed a substantial upregulation in SMAD4 expression, O-GlcNAcylation and EMT in patients with COPD, as well as in vitro and in vivo COPD models induced by CS, than those of the controls. Downregulation of SMAD4 resulted in a reduction in CS-induced EMT in vitro and in vivo. As a post-translational modification of proteins, O-GlcNAcylation is dynamically controlled by the duo of enzymes: O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) and O-GlcNAcase (OGA). We further discovered the enhancement of O-GlcNAcylation levels induced by CS was due to an elevated OGT expression, as the expression of OGA remained unchanged. Using an OGT inhibitor (OSMI-1) counteracted the effects of SMAD4 on EMT. Whereas, overexpressing OGT increased SMAD4 expression and promoted EMT. OGT-mediated SMAD4 O-GlcNAcylation shielded SMAD4 from proteasomal degradation by reducing its ubiquitination, thereby aiding in SMAD4 stabilization in response to EMT induced by CS. Overall, this research uncovers a fresh pathway for CS-induced EMT in the airway remodeling of COPD and offers valuable insights.

Down-regulation of RTEL1 Improves M1/M2 Macrophage Polarization by Promoting SFRP2 in Fibroblasts-derived Exosomes to Alleviate COPD

Chronic obstructive pulmonary disease (COPD) is a common chronic respiratory disease worldwide. Macrophage polarization plays a substantial role in the pathogenesis of COPD. This study is aimed to explore the regulatory mechanism of regulator of telomere elongation 1 (RTEL1) in COPD. COPD model mouse was conducted by cigarette smoke (CS). The pathological features of lung in mice were observed by histological staining. After extracting exosomes, macrophages were co-cultured with fibroblasts-derived exosomes. Then, the effects of RTEL1 and exosomal secreted frizzled-related protein 2 (SFRP2) on macrophage proliferation, inflammation, apoptosis, and M1, M2 macrophage polarization (iNOS and CD206) were evaluated by cell counting kit-8, EdU assay, enzyme-linked immuno sorbent assay, and western blotting, respectively. CS-induced COPD model mouse was successfully constructed. Through in vitro experiments, knockdown of RTEL1 inhibited macrophage proliferation, inflammation (MMP9, IL-1β and TNF-α), and promoted apoptosis (Bax, cleaved-caspase3, Bcl-2) in CS extract-induced lung fibroblasts. Meanwhile, RTEL1 knockdown promoted M1 and suppressed M2 macrophage polarization in COPD. Additionally, silencing SFRP2 in fibroblasts-derived exosomes reversed the effects of RTEL1 knockdown on proliferation, inflammation, apoptosis, and M1, M2 macrophage polarization. Collectively, down-regulation of RTEL1 improved M1/M2 macrophage polarization by promoting SFRP2 in fibroblasts-derived exosomes to alleviate CS-induced COPD.

METTL3-mediated NDUFB5 m6A modification promotes cell migration and mitochondrial respiration to promote the wound healing of diabetic foot ulcer

BACKGROUND

Diabetic foot ulcer (DFU) is the most devastating complication of diabetes mellitus (DM) and plays a major role in disability and death in DM patients. NADH: ubiquinone oxidoreductase subunit B5 (NDUFB5) plays an important role in maintaining mitochondrial respiration, but whether it is involved in regulating the progression of advanced glycation end products (AGEs)-mediated DFU is still unclear.

METHODS

Firstly, the role of AGEs on cell viability, migration, and mitochondrial respiration in human umbilical vein endothelial cells (HUVECs) was explored in vitro. Next, NDUFB5 expression was detected in human samples and AGEs-treated HUVECs, and NDUFB5's effect on AGEs-induced HUVECs injury and skin wound in diabetic mice was further clarified. In addition, the role of m6A modification mediated by methyltransferase-like 3 (METTL3) in regulating NDUFB5 expression and AGEs-induced HUVECs injury was investigated.

RESULTS

NDUFB5 promoted cell viability, migration, and mitochondrial respiration in AGEs-treated HUVECs, whereas mitochondrial fusion promoter M1 facilitated cell viability, migration, and mitochondrial oxiadative respiration in NDUFB5 knockdown HUVECs. Meanwhile, NDUFB5 promotes skin wound healing in diabetic mice. Besides, METTL3-mediated m6A modification and insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2) enhanced NDUFB5 expression in HUVECs. Furthermore, METTL3 promoted cell viability, migration, and mitochondrial respiration in AGEs-treated HUVECs by increasing NDUFB5.

CONCLUSION

METTL3-mediated NDUFB5 m6A modification inhibits AGEs-induced cell injury in HUVECs. METTL3 and NDUFB5 might serve as potential targets for DFU therapy in the future.

NADH Intraperitoneal Injection Prevents Lung Inflammation in a BALB/C Mice Model of Cigarette Smoke-Induced Chronic Obstructive Pulmonary Disease

Cigarette smoke is one of the main factors in Chronic Obstructive Pulmonary Disease (COPD), a respiratory syndrome marked by persistent respiratory symptoms and increasing airway obstruction. Perturbed NAD+/NADH levels may play a role in various diseases, including lung disorders like COPD. In our study, we investigated the preventive effect of NADH supplementation in an experimental model of COPD induced by cigarette smoke extract (CSE). N = 64 mice randomly distributed in eight groups were injected with NADH (two doses of 100 mg/kg or 200 mg/kg) or dexamethasone (2 mg/kg) before being exposed to CSE for up to 9 weeks. Additionally, NADH supplementation preserved lung antioxidant defenses by preventing the functional loss of key enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase, and the expression levels of glutathione (GSH) (n = 4, p < 0.001). It also reduced oxidative damage markers, such as malondialdehyde (MDA) and nitrites (n = 4, p < 0.001). A marked increase in tissue myeloperoxidase activity was assessed (MPO), confirming neutrophils implication in the inflammatory process. The latter was significantly ameliorated in the NADH-treated groups (p < 0.001). Finally, NADH prevented the CSE-induced secretion of cytokines such as Tumor Necrosis Factor alpha (TNF-α), IL-17, and IFN-y (n = 4, p < 0.001). Our study shows, for the first time, the clinical potential of NADH supplementation in preventing key features of COPD via its unique anti-inflammatory and antioxidant properties.

P. gingivalis alters lung microbiota and aggravates disease severity of COPD rats by up-regulating Hsp90α/MLKL

Background

Epidemiological evidence has confirmed that periodontitis is an essential and independent risk factor of chronic obstructive pulmonary disease (COPD). Porphyromonas gingivalis, a major pathogen implicated in periodontitis, may make a vital contribution to COPD progression. However, the specific effects and molecular mechanism of the link between P. gingivalis and COPD are not clear.

Methods and Results

A COPD rat model was constructed by smoke exposure combined intratracheal instillation of E. coli-LPS, then P. gingivalis was introduced into the oral cavity of COPD rats. This research observed that lower lung function, more severe alveolar damage and inflammation occurred in COPD rats with P. gingivalis group. Meanwhile, P. gingivalis/gingipains could colonize the lung tissues and be enriched in bronchoalveolar lavage fluid (BALF) of COPD rats with P. gingivalis group, along with alterations in lung microbiota. Proteomic analysis suggested that Hsp90α/MLKL-meditated necroptosis pathway was up-regulated in P. gingivalis-induced COPD aggravation, the detection of Hsp90α and MLKL in serum and lung tissue verified that Hsp90α/MLKL was up-regulated.

Conclusion

These results indicate that P. gingivalis could emigrate into the lungs, alter lung microbiota and lead to aggravation of COPD, which Hsp90α/MLKL might participate in.

Cullin5 drives experimental asthma exacerbations by modulating alveolar macrophage antiviral immunity

Asthma exacerbations caused by respiratory viral infections are a serious global health problem. Impaired antiviral immunity is thought to contribute to the pathogenesis, but the underlying mechanisms remain understudied. Here using mouse models we find that Cullin5 (CUL5), a key component of Cullin-RING E3 ubiquitin ligase 5, is upregulated and associated with increased neutrophil count and influenza-induced exacerbations of house dust mite-induced asthma. By contrast, CUL5 deficiency mitigates neutrophilic lung inflammation and asthma exacerbations by augmenting IFN-β production. Mechanistically, following thymic stromal lymphopoietin stimulation, CUL5 interacts with O-GlcNAc transferase (OGT) and induces Lys48-linked polyubiquitination of OGT, blocking the effect of OGT on mitochondrial antiviral-signaling protein O-GlcNAcylation and RIG-I signaling activation. Our results thus suggest that, in mouse models, pre-existing allergic injury induces CUL5 expression, impairing antiviral immunity and promoting neutrophilic inflammation for asthma exacerbations. Targeting of the CUL5/IFN-β signaling axis may thereby serve as a possible therapy for treating asthma exacerbations.

The role and mechanism of gut-lung axis mediated bidirectional communication in the occurrence and development of chronic obstructive pulmonary disease

The current studies have shown that the occurrence and development of chronic obstructive pulmonary disease (COPD) are closely related to the changes in gut health and its microenvironment, and even some gut diseases have significant clinical correlation with COPD. The dysbiosis of gut microbiota observed in COPD patients also suggests a potential bidirectional interaction between the gut and lung. Communication between the gut and lung may occur through circulating inflammatory cells, gut microbial metabolites, and circulating inflammatory mediators, but the mechanism of bidirectional communication between the gut and lung in COPD is still under study. Therefore, more research is still needed in this area. In this review, we summarize recent clinical studies and animal models on the role of the gut-lung axis in the occurrence and development of COPD and its mechanisms, so as to provide ideas for further research in this field. In addition, we also summarized the negative effects of COPD medication on gut microbiota and the gut microbiota risk factors for COPD and proposed the potential prevention and treatment strategies.

Regulatory roles of Osteopontin in lung epithelial inflammation and epithelial-telocyte interaction

BACKGROUND

Lung epithelial cells play important roles in lung inflammation and injury, although mechanisms remain unclear. Osteopontin (OPN) has essential roles in epithelial damage and repair and in lung cancer biological behaviours. Telocyte (TC) is a type of interstitial cell that interacts with epithelial cells to alleviate acute inflammation and lung injury. The present studies aim at exploring potential mechanisms by which OPN regulates the epithelial origin lung inflammation and the interaction of epithelial cells with TCs in acute and chronic lung injury.

METHODS

The lung disease specificity of OPN and epithelial inflammation were defined by bioinformatics. We evaluated the regulatory roles of OPN in OPN-knockdown or over-expressed bronchial epithelia (HBEs) challenged with cigarette smoke extracts (CSE) or in animals with genome OPN knockout (gKO) or lung conditional OPN knockout (cKO). Acute lung injury and chronic obstructive pulmonary disease (COPD) were induced by smoking or lipopolysaccharide (LPS). Effects of OPN on PI3K subunits and ERK were assessed using the inhibitors. Spatialization and distribution of OPN, OPN-positive epithelial subtypes, and TCs were defined by spatial transcriptomics. The interaction between HBEs and TCs was assayed by the co-culture system.

RESULTS

Levels of OPN expression increased in smokers, smokers with COPD, and smokers with COPD and lung cancer, as compared with healthy nonsmokers. LPS and/or CSE induced over-production of cytokines from HBEs, dependent upon the dysfunction of OPN. The severity of lung inflammation and injury was significantly lower in OPN-gKO or OPN-cKO mice. HBEs transferred with OPN enhanced the expression of phosphoinositide 3-kinase (PI3K)CA/p110α, PIK3CB/p110β, PIK3CD/p110δ, PIK3CG/p110γ, PIK3R1, PIK3R2 or PIK3R3. Spatial locations of OPN and OPN-positive epithelial subtypes showed the tight contact of airway epithelia and TCs. Epithelial OPN regulated the epithelial communication with TCs, and the down-regulation of OPN induced more alterations in transcriptomic profiles than the up-regulation.

CONCLUSION

Our data evidenced that OPN regulated lung epithelial inflammation, injury, and cell communication between epithelium and TCs in acute and chronic lung injury. The conditional control of lung epithelial OPN may be an alternative for preventing and treating epithelial-origin lung inflammation and injury.

Yifei Sanjie Formula Treats Chronic Obstructive Pulmonary Disease by Remodeling Pulmonary Microbiota

Chronic obstructive pulmonary disease (COPD) is one of the most common pulmonary diseases. Evidence suggests that dysbiosis of pulmonary microbiota leads to the COPD pathological process. Yifei Sanjie Formula (YS) is widely used to treat diseases in respiratory systems, yet little is known about its mechanisms. In the present study, we first established the fingerprint of YS as the background for UHPLC-QTOF-MS. Components were detected, including alkaloids, amino acid derivatives, phenylpropanoids, flavonoids, terpenoids, organic acids, phenols, and the like. The therapeutic effect of YS on COPD was evaluated, and the pulmonary function and ventilatory dysfunction (EF50, TV, and MV) were improved after the administration of YS. Further, the influx of lymphocytes was inhibited in pulmonary parenchyma, accompanied by down-regulation of inflammation cytokines via the NLRP3/caspase-1/IL-1β signaling pathway. The severity of pulmonary pathological damage was reversed. Disturbed pulmonary microbiota was discovered to involve an increased relative abundance of Ralstonia and Mycoplasma and a decreased relative abundance of Lactobacillus and Bacteroides in COPD animals. However, the subversive effect was shown. The abundance and diversity of pulmonary microflora were remodeled, especially increasing beneficial genua Lactobacillus and Bacteroides, as well as downregulating pathogenic genua Ralstonia and Mycoplasma in the YS group. Environmental factor correlation analysis showed that growing pulmonary microbiota was positively correlated with the inflammatory factor, referring to Ralstonia and Mycoplasma, as well as negatively correlated with the inflammatory factor, referring to Lactobacillus and Bacteroides. These results suggest that the effects of YS involved remodeling lung microbes and anti-inflammatory signal pathways, revealing that intervention microbiota and an anti-inflammatory may be a potential therapeutic strategy for COPD.

Regulatory roles of external cholesterol in human airway epithelial mitochondrial function through STARD3 signalling

BACKGROUND

Hypercholesterolemia is found in patients with chronic lung inflammation, during which airway epithelial cells play important roles in maintenance of inflammatory responses to pathogens. The present study aims at molecular mechanisms by which cholesterol changes airway epithelial sensitivity in response to smoking.

METHODS

Human bronchial epithelial cells (HBEs) were stimulated with cigarette smoke extract (CSE) and mice were exposed to CS/lipopolysaccharide (LPS) as models in vitro and in vivo. Severe COPD patients and healthy volunteers were also enrolled and the level of cholesterol in plasma was detected by metabolomics. Filipin III and elisa kits were used to stain free cholesterol. Mitochondrial function was detected by mitotracker green, mitotracker green, and Seahorse. Mitochondrial morphology was detected by high content screening and electron microscopy. The mRNA and protein levels of mitochondrial dynamics-related proteins were detected by RT-qPCR and Western blot,respectively. BODIPY 493/503 was used to stain lipid droplets. Lipidomics was used to detect intracellular lipid components. The mRNA level of interleukin (IL)-6 and IL-8 were detected by RT-qPCR.

RESULTS

We found that the cholesterol overload was associated with chronic obstructive pulmonary disease (COPD) and airway epithelia-driven inflammation, evidenced by hypercholesterolemia in patients with COPD and preclinical models, alteration of lipid metabolism-associated genes in CSE-induced airway epithelia and production of ILs. External cholesterol altered airway epithelial sensitivity of inflammation in response to CSE, through the regulation of STARD3-MFN2 pathway, cholesterol re-distribution, altered transport and accumulation of cholesterol, activities of lipid transport regulators and disorder of mitochondrial function and dynamics. MFN2 down-regulation increased airway epithelial sensitivity and production of ILs after smoking, at least partially by injuring fatty acid oxidation and activating mTOR phosphorylation.

CONCLUSIONS

Our data provide new insights for understanding molecular mechanisms of cholesterol-altered airway epithelial inflammation and for developing diagnostic biomarkers and therapeutic targets to improve patient outcomes.

NCOA4-Mediated Ferroptosis in Bronchial Epithelial Cells Promotes Macrophage M2 Polarization in COPD Emphysema

Background

Macrophage polarization plays an important role in the pathogenesis of COPD emphysema. Changes in macrophage polarization in COPD remain unclear, while polarization and ferroptosis are essential factors in its pathogenesis. Therefore, this study investigated the relationship between macrophage polarization and ferroptosis in COPD emphysema.

Methods

We measured macrophage polarization and the levels of matrix metalloproteinases (MMPs) in the lung tissues of COPD patients and cigarette smoke (CS)-exposed mice. Flow cytometry was used to determine macrophage (THP-M cell) polarization changes. Ferroptosis was examined by FerroOrange, Perls' DAB, C11-BODIPY and 4-HNE staining. Nuclear receptor coactivator 4 (NCOA4) was measured in the lung tissues of COPD patients and CS-exposed mice by western blotting. A cell study was performed to confirm the regulatory effect of NCOA4 on macrophage polarization.

Results

Increased M2 macrophages and MMP9 and MMP12 levels were observed in COPD patients, CS-exposed mice and THP-M cells cocultured with CS extract (CSE)-treated human bronchial epithelial (HBE) cells. Increased NCOA4 levels and ferroptosis were confirmed in COPD. Treatment with NCOA4 siRNA and the ferroptosis inhibitor ferrostatin-1 revealed an association between ferroptosis and M2 macrophages. These findings support a role for NCOA4, which induces an increase in M2 macrophages, in the pathogenesis of COPD emphysema.

Conclusion

In our study, CS led to the dominance of the M2 phenotype in COPD. We identified NCOA4 as a regulator of M2 macrophages and emphysema by mediating ferroptosis, which offers a new direction for research into COPD diagnostics and treatment.

Inhibition of USP7 suppresses advanced glycation end-induced cell cycle arrest and senescence of human umbilical vein endothelial cells through ubiquitination of p53

Diabetes mellitus is a n arising public health concern, and diabetic foot is one of the most common complications of diabetes. Current management for diabetic foot cannot reach optimal remission. In this study, we aim to explore the mechanism underlying the pathogenesis of diabetic foot and provide novel strategies for the treatment of diabetic foot. A total of 10 normal skin tissues and 20 diabetic foot ulcer specimens are collected. Cell proliferation is determined by CCK-8 assay. Cell cycle is determined by flow cytometry, and cell senescence is evaluated by β-galactosidase staining. Co-immunoprecipitation assay is used to explore the interaction between USP7 and p53. Advanced glycation end products (AGEs) are used to establish diabetic cell model, and streptozotocin (STZ) is used to establish diabetic rat model. Our results showed that USP7 expression is increased in diabetic foot ulcer and in human umbilical vein endothelial cells (HUVECs) after treatment with AGEs. Inhibition of USP7 can reduce cell cycle arrest and cell senescence in HUVECs. Moreover, USP7 can interact with p53 and promote its expression through mediating its deubiquitination. Knockdown of p53 can reverse USP7-mediated cell cycle arrest and cell senescence in HUVECs. In diabetic rats, HBX 41108, the specific inhibitor of USP7, can significantly accelerate wound healing. Our study reveals that the inhibition of USP7 can suppress AGEs-induced cell cycle arrest and cell senescence of HUVECs through promoting p53 ubiquitination. USP7 is a potential target for the treatment of diabetic foot ulcers.

Effect of doxofylline on pulmonary inflammatory response and oxidative stress during mechanical ventilation in rats with COPD

OBJECTIVE

To evaluate the effects of doxofylline on inflammatory responses and oxidative stress during mechanical ventilation in rats with chronic obstructive pulmonary disease (COPD).

METHODS

Eight-week-old male Sprague Dawley rats were selected, and the COPD rat model was constructed. The rats were randomly divided into a model group (group M), a model + normal saline group (group N), a doxofylline group (group D), and a control group fed with conventional chow and given normal oxygen supply (group C) (n = 12 in each group). Tracheal intubation and mechanical ventilation were conducted in the rats in each group after anesthesia. A real-time intravenous infusion with 50 mg/kg of doxofylline was conducted in group D, and there was no drug intervention in groups C, N and M. Pathological manifestations of the pulmonary tissues were observed and compared among the groups. And some indicators were evaluated.

RESULTS

(1) The pulmonary tissues of the rats in groups M, N, and D exhibited typical pathological histological changes of COPD. (2) Groups M, N, and D showed increased Ppeak, PaCO2, total white blood cell count in BALF, and IL-8, TNF-α, and MDA levels in the pulmonary tissue and BALF, and decreased PaO2 and IL-10 and SOD levels, compared with group C. (3). Group D showed decreased Ppeak, PaCO2, total white blood cell count in BALF, and IL-8, TNF-α, and MDA levels in the pulmonary tissue, and increased PaO2 and IL-10 and SOD levels, compared with group N or M.

CONCLUSION

Doxofylline was shown to improve ventilation and air exchange during mechanical ventilation in rats with COPD, reduce the inflammatory response and oxidative stress, and mitigate the degree of pulmonary tissue injury.

Quercetin Improves Pulmonary Function and Prevents Emphysema Caused by Exposure to Cigarette Smoke in Male Mice

Chronic obstructive pulmonary disease (COPD) is the major cause of morbidity and mortality worldwide, and cigarette smoke is a key factor in the development of COPD. Thus, the development of effective therapies to prevent the advancement of COPD has become increasingly essential. We hypothesized that quercetin protects lungs in mice exposed to long-term cigarette smoke. Thirty-five C57BL/6 mice were exposed to cigarette smoke (12 cigarettes per day) for 60 days and pretreated with 10 mg/kg/day of quercetin via orogastric gavage. After the experimental protocol, the animals were euthanized and samples were collected for histopathological, antioxidant defense, oxidative stress and inflammatory analysis. The animals exposed to cigarette smoke showed an increase in respiratory rate and hematological parameters, cell influx into the airways, oxidative damage and inflammatory mediators, besides presenting with alterations in the pulmonary histoarchitecture. The animals receiving 10 mg/kg/day of quercetin that were exposed to cigarette smoke presented a reduction in cellular influx, less oxidative damage, reduction in cytokine levels, improvement in the histological pattern and improvement in pulmonary emphysema compared to the group that was only exposed to cigarette smoke. These results suggest that quercetin may be an agent in preventing pulmonary emphysema induced by cigarette smoke.

MF-094, a potent and selective USP30 inhibitor, accelerates diabetic wound healing by inhibiting the NLRP3 inflammasome

Diabetes is a prevalent disease worldwide that can result in several complications, including renal failure, blindness, and amputation. Diabetic foot ulcers, which have the characteristics of chronic wounds, are a devastating component of diabetes progression that can lead to lower extremity amputation. In this study, we set out to investigate the mechanisms involved in wound healing of diabetic foot ulcers. The expression of USP30 in skin tissues of patients with diabetic foot ulcers and HSF2 human skin fibroblasts treated with advanced glycation end (AGE) products was detected by qRT-PCR, and CCK-8, cell scratch and ELISA assay were used to detect cell viability, migration and levels of Col I, Col III, MMP-2, MMP-9, IL-1β and IL-18. The interaction between USP30 and NLRP3 was verified by co-immunoprecipitation and ubiquitination assays. The expression of USP30, NLRP3 and caspase-1 p20 was detected by Western blot. USP30 inhibitor MF-094 was used to treat diabetic rat model established by streptozotocin (STZ). We found that USP30, a deubiquitinase, was upregulated in skin tissues of patients with diabetic foot ulcers compared with normal skin tissues. In vitro, we found that treatment of HSF2 human skin fibroblasts with advanced glycation end (AGE) products, known to contribute to diabetic complications, resulted in suppressed viability and migration of HSF2 cells, as well as increased levels of USP30 mRNA and protein. Functionally, downregulation of USP30 via shRNA-mediated knockdown or treatment with the USP30 inhibitor MF-094, restored viability and migration of AGE-treated HSF2 cells. We identified the NLRP3 inflammasome as a critical target of USP30 in AGE-induced functions. Mechanistically, we demonstrate that USP30 activates the NLRP3 inflammasome by deubiquitinating NLRP3. Finally, we show that inhibition of USP30 via MF-094 treatment facilitated wound healing in diabetic rats and resulted in decreased protein levels of NLRP3 and its downstream target caspase-1 p20, thus establishing the physiological importance of the identified USP30-NLRP3 link. Together, our findings suggest a therapeutic potential for USP30 in diabetic foot ulcers.

Hypermethylation of the Nrf2 Promoter Induces Ferroptosis by Inhibiting the Nrf2-GPX4 Axis in COPD

Background

Nuclear factor E2-related factor 2 (Nrf2) is involved in oxidative stress and lung inflammation and regulates the etiology of chronic obstructive pulmonary disease (COPD). Ferroptosis is characterized by the accumulation of lipid reactive oxygen species (ROS) via ferrous ion-dependent Fenton reactions and is involved in COPD. However, the role of Nrf2 in ferroptosis and its epigenetic regulation in the pathogenesis of COPD remain unclear.

Methods

Ferroptosis was detected by 4-HNE, MDA, C11BODIPY, DCFH-DA, Peals’ staining and CCK-8 assays. qPCR and Western blotting were performed to examine the Nrf2 levels in peripheral lung tissues, primary epithelial cells collected from patients with COPD and subjects with normal pulmonary function (never-smoker [control-NS]; smoker [control-S]), and cigarette smoke extract (CSE)-treated human bronchial epithelial (HBE) cells. ELISA was used to quantify IL-8 and IL-1β levels. Methylation of the Nrf2 promoter was analyzed by bisulfite sequencing and pyrosequencing.

Results

Ferroptosis was involved in COPD and glutathione peroxidase 4 (GPX4) expression was downregulated in the COPD group. Reactive oxygen species (ROS), lipid peroxides and MDA were increased, but GPX4 and SOD were exhausted in CSE-treated HBE cells. The production of IL-1β and IL-8 was promoted in HBE cells in response to CSE but could be reversed by the ferroptosis inhibitor fer-1. The Nrf2 level was significantly decreased in the COPD group compared with the control-S and control-NS groups. Increased Nrf2 expression enhanced GPX4 and SOD levels and inhibited ferroptosis and proinflammatory cytokines in the supernatant. Inhibition of GPX4 reversed the effect of Nrf2 overexpression and promoted ferroptosis. Two specific CpG sites within the Nrf2 promoter were hypermethylated in the COPD group. Similarly, CSE-treated HBE cells exhibited hypermethylation of the Nrf2 gene.

Conclusion

Nrf2 expression was downregulated in the lungs of COPD patients due to hypermethylation of the Nrf2 promoter, inhibiting Nrf2/GPX4 and ferroptosis, which is related to the initiation and progression of COPD. Targeting Nrf2/GPX4 may inhibit ferroptosis, which could provide strategies to delay or treat COPD.