[Effect of SHP-1 knockout in airway epithelial cells on emphysema phenotype in chronic obstructive pulmonary disease in mice].

Objective: To construct and characterize conditional Src homology region 2 protein tyrosine phosphatase 1 (SHP-1) knockout mice in airway epithelial cells and to observe the effect of defective SHP-1 expression in airway epithelial cells on the emphysema phenotype in chronic obstructive pulmonary disease (COPD). Methods: To detect the expression of SHP-1 in the airway epithelium of COPD patients. CRISPR/Cas9 technology was used to construct SHP-1flox/flox transgenic mice, which were mated with airway epithelial Clara protein 10-cyclase recombinase and estrogen receptor fusion transgenic mice (CC10-CreER+/+), and after intraperitoneal injection of tamoxifen, airway epithelial SHP-1 knockout mice were obtained (SHP-1flox/floxCC10-CreER+/-, SHP-1Δ/Δ). Mouse tail and lung tissue DNA was extracted and PCR amplified to discriminate the genotype of the mice; the knockout effect of SHP-1 gene in airway epithelial cells was verified by qRT-PCR, Western blotting, and immunofluorescence. In addition, an emphysema mouse model was constructed using elastase to assess the severity of emphysema in each group of mice. Results: Airway epithelial SHP-1 was significantly downregulated in COPD patients. Genotyping confirmed that SHP-1Δ/Δ mice expressed CC10-CreER and SHP-1-flox. After tamoxifen induction, we demonstrated the absence of SHP-1 protein expression in airway epithelial cells of SHP-1Δ/Δ mice at the DNA, RNA, and protein levels, indicating that airway epithelial cell-specific SHP-1 knockout mice had been successfully constructed. In the emphysema animal model, SHP-1Δ/Δ mice had a more severe emphysema phenotype compared with the control group, which was manifested by disorganization of alveolar structure in lung tissue and rupture and fusion of alveolar walls to form pulmonary alveoli. Conclusions: The present study successfully established and characterized the SHP-1 knockout mouse model of airway epithelial cells, which provides a new experimental tool for the in-depth elucidation of the role of SHP-1 in the emphysema process of COPD and its mechanism.

Association of IL-33 in modeling type-2 airway inflammation and pulmonary emphysema in mice.

We developed pulmonary emphysema and a type 2 airway inflammation overlap mouse model. The bronchoalveolar lavage (BAL) interleukin 13 (IL-13), IL-4, and IL-5 levels in the overlap model were higher than in the pulmonary emphysema model and lower than in the type 2 airway inflammation model, but IL-33 level in the lung was higher than in other models. IL-33 and interferon-γ (IFNγ) in lungs may control the severity of a type 2 airway inflammation in lung.

Systemic antibiotics cause deterioration of emphysema associated with exaggerated inflammation and autophagy.

The interaction between the microbial environment and the host is important for immune homeostasis. Recent research suggests that microbiota dysbiosis can be involved in respiratory diseases. Emphysema is a chronic inflammatory disease, but it is unclear whether dysbiosis caused by antibiotics can affect disease progression. Here, we tried to elucidate the effect of systemic antibiotics on smoking-exposed emphysema models. In this study, the antibiotic mixture caused more alveolar destruction and airspace expansion in the smoking group than in the smoking only or control groups. This emphysema aggravation as a result of antibiotic exposure was associated with increased levels of inflammatory cells, IL-6, IFNγ and protein concentrations in bronchoalveolar lavage fluid. Proteomics analysis indicated that autophagy could be involved in antibiotic-associated emphysema aggravation, and increased protein levels of LC3B, atg3, and atg7 were identified by Western blotting. In microbiome and metabolome analyses, the composition of the gut microbiota was different with smoking and antibiotic exposure, and the levels of short-chain fatty acids (SCFAs), including acetate and propionate, were reduced by antibiotic exposure. SCFA administration restored emphysema development with reduced inflammatory cells, IL-6, and IFNγ and decreased LC3B, atg3, and atg7 levels. In conclusion, antibiotics can aggravate emphysema, and inflammation and autophagy may be associated with this aggravation. This study provides important insight into the systemic impact of microbial dysbiosis and the therapeutic potential of utilizing the gut microbiota in emphysema.

Alpha-1 antitrypsin inhibits fractalkine-mediated monocyte-lung endothelial cell interactions.

Chronic obstructive pulmonary disease (COPD) is characterized by nonresolving inflammation fueled by breach in the endothelial barrier and leukocyte recruitment into the airspaces. Among the ligand-receptor axes that control leukocyte recruitment, the full-length fractalkine ligand (CX3CL1)-receptor (CX3CR1) ensures homeostatic endothelial-leukocyte interactions. Cigarette smoke (CS) exposure and respiratory pathogens increase expression of endothelial sheddases, such as a-disintegrin-and-metalloproteinase-domain 17 (ADAM17, TACE), inhibited by the anti-protease α-1 antitrypsin (AAT). In the systemic endothelium, TACE cleaves CX3CL1 to release soluble CX3CL1 (sCX3CL1). During CS exposure, it is not known whether AAT inhibits sCX3CL1 shedding and CX3CR1+ leukocyte transendothelial migration across lung microvasculature. We investigated the mechanism of sCX3CL1 shedding, its role in endothelial-monocyte interactions, and AAT effect on these interactions during acute inflammation. We used two, CS and lipopolysaccharide (LPS) models of acute inflammation in transgenic Cx3cr1gfp/gfp mice and primary human endothelial cells and monocytes to study sCX3CL1-mediated CX3CR1+ monocyte adhesion and migration. We measured sCX3CL1 levels in plasma and bronchoalveolar lavage (BALF) of individuals with COPD. Both sCX3CL1 shedding and CX3CR1+ monocytes transendothelial migration were triggered by LPS and CS exposure in mice, and were significantly attenuated by AAT. The inhibition of monocyte-endothelial adhesion and migration by AAT was TACE-dependent. Compared with healthy controls, sCX3CL1 levels were increased in plasma and BALF of individuals with COPD, and were associated with clinical parameters of emphysema. Our results indicate that inhibition of sCX3CL1 as well as AAT augmentation may be effective approaches to decrease excessive monocyte lung recruitment during acute and chronic inflammatory states.NEW & NOTEWORTHY Our novel findings that AAT and other inhibitors of TACE, the sheddase that controls full-length fractalkine (CX3CL1) endothelial expression, may provide fine-tuning of the CX3CL1-CX3CR1 axis specifically involved in endothelial-monocyte cross talk and leukocyte recruitment to the alveolar space, suggests that AAT and inhibitors of sCX3CL1 signaling may be harnessed to reduce lung inflammation.

Eosinophils promote pulmonary matrix destruction and emphysema via Cathepsin L.

Patients with chronic obstructive pulmonary disease (COPD) who exhibit elevated blood eosinophil levels often experience worsened lung function and more severe emphysema. This implies the potential involvement of eosinophils in the development of emphysema. However, the precise mechanisms underlying the development of eosinophil-mediated emphysema remain unclear. In this study, we employed single-cell RNA sequencing to identify eosinophil subgroups in mouse models of asthma and emphysema, followed by functional analyses of these subgroups. Assessment of accumulated eosinophils unveiled distinct transcriptomes in the lungs of mice with elastase-induced emphysema and ovalbumin-induced asthma. Depletion of eosinophils through the use of anti-interleukin-5 antibodies ameliorated elastase-induced emphysema. A particularly noteworthy discovery is that eosinophil-derived cathepsin L contributed to the degradation of the extracellular matrix, thereby leading to emphysema in pulmonary tissue. Inhibition of cathepsin L resulted in a reduction of elastase-induced emphysema in a mouse model. Importantly, eosinophil levels correlated positively with serum cathepsin L levels, which were higher in emphysema patients than those without emphysema. Expression of cathepsin L in eosinophils demonstrated a direct association with lung emphysema in COPD patients. Collectively, these findings underscore the significant role of eosinophil-derived cathepsin L in extracellular matrix degradation and remodeling, and its relevance to emphysema in COPD patients. Consequently, targeting eosinophil-derived cathepsin L could potentially offer a therapeutic avenue for emphysema patients. Further investigations are warranted to explore therapeutic strategies targeting cathepsin L in emphysema patients.

Evaluating Novel Protein Phosphatase 2A Activators as Therapeutics for Emphysema.

The activity of PP2A (protein phosphatase 2A), a serine-threonine phosphatase, is reduced by chronic cigarette smoke (SM) exposure and α-1 antitrypsin (AAT) deficiency, and chemical activation of PP2A reduces the loss of lung function in SM-exposed mice. However, the previously studied PP2A-activator tricyclic sulfonamide compound DBK-1154 has low stability to oxidative metabolism, resulting in fast clearance and low systemic exposure. Here we compare the utility of a new more stable PP2A activator, ATUX-792, versus DBK-1154 for the treatment of SM-induced emphysema. ATUX-792 was also tested in human bronchial epithelial cells and a mouse model of AAT deficiency, Serpina1a-e-knockout mice. Human bronchial epithelial cells were treated with ATUX-792 or DBK-1154, and cell viability, PP2A activity, and MAP (mitogen-activated protein) kinase phosphorylation status were examined. Wild-type mice received vehicle, DBK-1154, or ATUX-792 orally in the last 2 months of 4 months of SM exposure, and 8-month-old Serpina1a-e-knockout mice received ATUX-792 daily for 4 months. Forced oscillation and expiratory measurements and histology analysis were performed. Treatment with ATUX-792 or DBK-1154 resulted in PP2A activation, reduced MAP kinase phosphorylation, immune cell infiltration, reduced airspace enlargements, and preserved lung function. Using protein arrays and multiplex assays, PP2A activation was observed to reduce AAT-deficient and SM-induced release of CXCL5, CCL17, and CXCL16 into the airways, which coincided with reduced neutrophil lung infiltration. Our study indicates that suppression of the PP2A activity in two models of emphysema could be restored by next-generation PP2A activators to impact lung function.

Characterization of a spontaneous mouse model of mild, accelerated aging via ECM degradation in emphysematous lungs.

Emphysema limits airflow and causes irreversible progression of chronic obstructive pulmonary disease (COPD). Strain differences must be considered when selecting mouse models of COPD, owing to disease complexity. We previously reported that a novel C57BL/6JJcl substrain, the Mayumi-Emphysema (ME) mouse, exhibits spontaneous emphysema; however, the other characteristics remain unknown. We aimed to characterize the lungs of ME mice and determine their experimental availability as a model. ME mice had a lower body weight than the control C57BL/6JJcl mice, with a median survival time of ~80 weeks. ME mice developed diffused emphysema with respiratory dysfunction from 8 to 26 weeks of age, but did not develop bronchial wall thickening. Proteomic analyses revealed five extracellular matrix-related clusters in downregulated lung proteins in ME mice. Moreover, EFEMP2/fibulin-4, an essential extracellular matrix protein, was the most downregulated protein in the lungs of ME mice. Murine and human EFEMP2 were detected in the pulmonary artery. Furthermore, patients with mild COPD showed decreased EFEMP2 levels in the pulmonary artery when compared to those without COPD. The ME mouse is a model of mild, accelerated aging with low-inflammatory emphysema and respiratory dysfunction that progresses with age and pulmonary EFEMP2 decrease, similar to that observed in patients with mild COPD.

Regorafenib prevents the development of emphysema in a murine elastase model.

Emphysema is a chronic obstructive lung disease characterized by inflammation and enlargement of the air spaces. Regorafenib, a potential senomorphic drug, exhibited a therapeutic effect in porcine pancreatic elastase (PPE)-induced emphysema in mice. In the current study we examined the preventive role of regorafenib in development of emphysema. Lung function tests and morphometry showed that oral administration of regorafenib (5 mg/kg/day) for seven days after instillation of PPE resulted in attenuation of emphysema. Mechanistically, regorafenib reduced the recruitment of inflammatory cells, particularly macrophages and neutrophils, in bronchoalveolar lavage fluid. In agreement with these findings, measurements using a cytokine array and ELISA showed that expression of inflammatory mediators including interleukin (IL)-1ß, IL-6, and CXCL1/KC, and tissue inhibitor of matrix metalloprotease-1 (TIMP-1), was downregulated. The results of immunohistochemical analysis confirmed that expression of IL-6, CXCL1/KC, and TIMP-1 was reduced in the lung parenchyma. Collectively, the results support the preventive role of regorafenib in development of emphysema in mice and provide mechanistic insights into prevention strategies. [BMB Reports 2023; 56(8): 439-444].

Protective effect of oleo-gum resin of Commiphora wightii against elastase-induced chronic obstructive pulmonary disease-linked lung inflammation and emphysema: Isolation and identification of key bioactive phytoconstituent.

ETHNOPHARMACOLOGICAL RELEVANCE: Oleo-gum resin of Commiphora wightii (Arnott) Bhandari of family Burseraceae, commonly known as 'guggul', is a well known Ayurvedic drug used traditionally to treat various disorders including respiratory ailments. However, role of C. wightii in chronic obstructive pulmonary disease (COPD) is not known. AIM: The present work was designed to investigate the protective potential of standardized C. wightii extract/and its fractions against elastase-induced COPD-linked lung inflammation and to identify key bioactive constituent(s). MATERIAL AND METHODS: C. wightii oleo-gum resin extract was prepared using Soxhlet extraction technique and the resultant extract was standardized on basis of guggulsterone content using HPLC. The extract was partitioned by different solvents in increasing order of polarity. Standardized extract/its partitioned fractions were orally administered to male BALB/c mice 1 h prior to intra-tracheal instillation of elastase (1U/mouse). Anti-inflammatory effect was evaluated by analyzing inflammatory cells and myeloperoxidase activity in lungs. The various fraction(s) were subjected to column chromatography to isolate bioactive compound. Isolated compound was identified using 1H and 13C-NMR and analyzed for assessment of several inflammatory mediators using techniques like ELISA, PCR, and gelatin zymography. RESULTS: C. wightii extract attenuated elastase-induced lung inflammation in dose-dependent manner and Ethyl acetate fraction (EAF) provided maximum protection. EAF was subjected to column chromatography followed by assessment of bioactivity of each sub-fraction, ultimately leading towards isolation of two compounds i.e. C1 and C2. C1 seems to be the key active principle of C. wightii, as it displayed significant anti-inflammatory activity against elastase induced lung inflammation while C2 largely remains ineffective. C1 was identified as mixture of E- and Z-guggulsterone (GS). Reduction in the elastase induced lung inflammation by GS was associated with downregulation of expression of several COPD linked pro-inflammatory factors such as IL-6/TNF-α/IL-1ß/KC/MIP-2/MCP-1/G-CSF as well as normalization of redox imbalance as indicated by levels of ROS/MDA/protein carbonyl/nitrite/GSH etc. Further, 21 days prolonged administration of GS (10 mg/kg b.wt; once daily) protected against elastase-induced emphysema by mitigating expression/activity of MMP-2/-9 and increasing TIMP-1 expression. CONCLUSION: Overall, guggulsterone seems to be the key bioactive constituent responsible for exerting beneficial effects of C. wightii against COPD.

Salidroside ameliorated the pulmonary inflammation induced by cigarette smoke via mitigating M1 macrophage polarization by JNK/c-Jun.

Pulmonary inflammation induced by cigarette smoke (CS) promoted the development of chronic obstructive pulmonary disease (COPD), and macrophage polarization caused by CS modulated inflammatory response. Previous studies indicated that salidroside exerted therapeutic effects in COPD, but the anti-inflammatory mechanisms were not clear. This study aimed to explore the effects and mechanisms of salidroside on macrophage polarization induced by CS. Wistar rats received passively CS exposure and were treated intraperitoneally with salidroside at a low, medium or high dose. Lung tissues were stained with hematoxylin-eosin. Emphysema and inflammatory scores were evaluated by histomorphology. Lung function, cytokines, and cell differential counts in BALF were detected. The macrophage polarization was determined by immunohistochemistry in lung tissues. Alveolar macrophages (AMs) were isolated and treated with cigarette smoke extract (CSE), salidroside or inhibitors of relative pathways. The polarization status was determined by qPCR, and the protein level was detected by Western blotting. CS exposure induced emphysema and lung function deterioration. The inflammatory scores, cytokines level and neutrophils counts were elevated after CS exposure. Salidroside treatment partly ameliorated above abnormal. CS exposure activated M1 and M2 polarization of AMs in vivo and in vitro, and salidroside mitigated M1 polarization induced by CS. CSE activated the JNK/c-Jun in AMs and the M1 polarization of AMs was inhibited by the inhibitors of JNK and AP-1. Salidroside treatment deactivated the JNK/c-Jun, which indicated that salidroside mitigated the M1 polarization of AMs induced by CS via inhibiting JNK/c-Jun. Salidroside treatment ameliorated the pulmonary inflammation and M1 polarization of AMs induced by CS, and the process might be mediated by the deactivation of JNK/c-Jun.

Long-term e-cigarette aerosol exposure causes pulmonary emphysema in adult female and male mice.

This study aimed to evaluate long-term exposure to conventional cigarette smoke (CC) and electronic cigarette (EC) aerosol in adult male and female C57BL/6 mice. Forty-eight C57BL/6 mice were used, male (n = 24) and female (n = 24), both were divided into three groups: control, CC and EC. The CC and EC groups were exposed to cigarette smoke or electronic cigarette aerosol, respectively, 3 times a day for 60 consecutive days. Afterwards, they were maintained for 60 days without exposure to cigarettes or electronic cigarette aerosol. Both cigarettes promoted an influx of inflammatory cells to the lung in males and females. All animals exposed to CC and EC showed an increase in lipid peroxidation and protein oxidation. There was an increase of IL-6 in males and females exposed to EC. The IL-13 levels were higher in the females exposed to EC and CC. Both sexes exposed to EC and CC presented tissue damage characterized by septal destruction and increased alveolar spaces compared to control. Our results demonstrated that exposure to CC and EC induced pulmonary emphysema in both sexes, and females seem to be more susceptible to EC.

Therapeutic effect of two strategies directed at disruption of pathogenic neutrophil extracellular vesicles in a murine emphysema model.

Chronic obstructive pulmonary disease (COPD) is characterized by lung extracellular matrix (ECM) remodeling that contributes to obstruction. This is driven, in part by extracellular vesicles (EVs) from activated neutrophils (PMNs), which express on their surface an α-1 antitrypsin (AAT) insensitive form of neutrophil elastase (NE). These EVs are predicted to bind to collagen fibers via Mac-1 integrins, during which time NE can enzymatically degrade the collagen. Protamine sulfate (PS), a cationic compound used safely for decades in humans, has been shown, in vitro, to dissociate this NE from the EV surface, rendering it AAT-sensitive. In addition, a nonapeptide inhibitor, MP-9, has been shown to prevent EV association with collagen. We sought to test whether PS, MP-9, or a combination of the two could effectively prevent NE+ EV-driven ECM remodeling in an animal COPD model. EVs were preincubated with PBS, protamine sulfate (25 µM), MP-9 (50 µM), or a combination of PS and MP-9. These were delivered intratracheally to anesthetized female 10- to 12-wk-old A/J mice for a 7-day time period. One group of mice was euthanized and lungs sectioned for morphometry, and the other group was used for live pulmonary function testing. The effect of alveolar destruction by activated neutrophil EVs was abrogated by pretreatment with PS or MP-9. However, in pulmonary function tests, only the PS groups (and combined PS/MP-9 groups) returned pulmonary function to near-control levels. These data presented here offer an insight into the effective use of PS in therapeutic setting for EV-derived alveolar damage.NEW & NOTEWORTHY Protamine sulfate facilitates the removal of neutrophil elastase (NE) from the surface of extracellular vesicles from activated neutrophils. This "free" NE is no longer protected from inhibition by its endogenous anti-protease, α-1-anti-trypsin. This function of protamine sulfate highlights it as a potential therapeutic strategy for COPD, which may attenuate the disease process.

The relationship between elastin cross linking and alveolar wall rupture in human pulmonary emphysema.

To better define the role of mechanical forces in pulmonary emphysema, we employed methods recently developed in our laboratory to identify microscopic level relationships between airspace size and elastin-specific desmosine and isodesmosine (DID) cross links in normal and emphysematous human lungs. Free DID in wet tissue (a biomarker for elastin degradation) and total DID in formalin-fixed, paraffin-embedded (FFPE) tissue sections were measured using liquid chromatography-tandem mass spectrometry and correlated with alveolar diameter, as determined by the mean linear intercept (MLI) method. There was a positive correlation between free lung DID and MLI (P < 0.0001) in formalin-fixed lungs, and elastin breakdown was greatly accelerated when airspace diameter exceeded 400 µm. In FFPE tissue, DID density was markedly increased beyond 300 µm (P < 0.0001) and leveled off around 400 µm. Elastic fiber surface area similarly peaked at around 400 µm, but to a much lesser extent than DID density, indicating that elastin cross linking is markedly increased in response to early changes in airspace size. These findings support the hypothesis that airspace enlargement is an emergent phenomenon in which initial proliferation of DID cross links to counteract alveolar wall distention is followed by a phase transition involving rapid acceleration of elastin breakdown, alveolar wall rupture, and progression to an active disease state that is less amenable to therapeutic intervention.NEW & NOTEWORTHY The current findings support the hypothesis that airspace enlargement is an emergent phenomenon in which initial proliferation of DID cross links to counteract alveolar wall distention is followed by a phase transition involving rapid acceleration of elastin breakdown, alveolar wall rupture, and progression to an active disease state that is less amenable to therapeutic intervention.

MicroRNA Let-7 Induces M2 Macrophage Polarization in COPD Emphysema Through the IL-6/STAT3 Pathway.

Background: M2 polarized macrophages are involved in the occurrence and development of emphysema in COPD patients. However, the molecular mechanism of M2 macrophage polarization is still unclear. This study investigated the molecular mechanism of let-7 differentially expressed in bronchial epithelial cells of COPD patients participating in COPD emphysema by regulating the expression of IL-6 and inducing M2 polarization of alveolar macrophages (AM). Materials and Methods: We measured let-7c expression in human lung tissue, serum and the lung tissue of cigarette smoke (CS)-exposed mice by qRT‒PCR. We observed the M1/M2 AM polarization in the lungs of COPD patients and COPD model mice by immunofluorescence analysis. Western blotting was used to determine the expression of MMP9/12 in the lung tissue of COPD patients and CS-exposed mice. An in vitro experiment was performed to determine the molecular mechanism of let-7c-induced macrophage polarization. Results: Let-7c expression was downregulated in COPD patients, CS-exposed mice, and CS extract (CSE)-treated human bronchial epithelial (HBE) cells. AMs in COPD patients and CS-exposed mice were dominated by the M2 type, and the release of MMP9/12 was increased. In vitro, the transfection of mimics overexpressing let-7 or the use of tocilizumab to block signal transduction between HBE cells and macrophages inhibited the IL-6/STAT3 pathway. M2 macrophage polarization was inhibited, and MMP9/12 release was reduced. Conclusion: Our results indicate that CS decreased let-7c expression in HBE cells, and M2 AM polarization was dominant in COPD. In HBE cells, let-7c could inhibit M2 polarization of AMs through the IL-6/STAT3 pathway, providing potential diagnostic and therapeutic value for slowing COPD emphysema.

Green tea extract ameliorates macrophage-driven emphysematous lesions in chronic obstructive pulmonary disease induced by cigarette smoke condensate.

Chronic obstructive pulmonary disease (COPD) is an important lung disease characterized by complicated symptoms including emphysema. We aimed to explore the mechanisms underlying the protective effect of green tea extract (GTE) on cigarette smoke condensate (CSC)-induced emphysema by demonstrating the reduction of macrophage-induced protease expression through GTE treatment in vivo and in vitro. Mice were intranasally administered 50 mg/kg CSC once a week for 4 weeks, and doses of 100 or 300 mg/kg GTE were administered orally once daily for 4 weeks. GTE significantly reduced macrophage counts in bronchoalveolar lavage fluid and emphysematous lesions in lung tissues in CSC-exposed mice. In addition, GTE suppressed CSC-induced extracellular signal-regulated kinase (ERK)/activator protein (AP)-1 phosphorylation followed by matrix metalloproteinases (MMP)-9 expression as revealed by western blotting, immunohistochemistry, and zymography in CSC-instilled mice. These underlying mechanisms related to reduced protease expression were confirmed in NCI-H292 cells stimulated by CSC. Taken together, GTE effectively inhibits macrophage-driven emphysematous lesions induced by CSC treatment, and these protective effects of GTE are closely related to the ERK/AP-1 signaling pathway, followed by a reduced protease/antiprotease imbalance. These results suggest that GTE can be used as a supplementary agent for the prevention of emphysema progression in COPD patients.

CC16 augmentation reduces exaggerated COPD-like disease in Cc16-deficient mice.

Low Club Cell 16 kDa protein (CC16) plasma levels are linked to accelerated lung function decline in patients with chronic obstructive pulmonary disease (COPD). Cigarette smoke-exposed (CS-exposed) Cc16-/- mice have exaggerated COPD-like disease associated with increased NF-κB activation in their lungs. It is unclear whether CC16 augmentation can reverse exaggerated COPD in CS-exposed Cc16-/- mice and whether increased NF-κB activation contributes to the exaggerated COPD in CS-exposed Cc16-/- lungs. CS-exposed WT and Cc16-/- mice were treated with recombinant human CC16 (rhCC16) or an NF-κB inhibitor versus vehicle beginning at the midpoint of the exposures. COPD-like disease and NF-κB activation were measured in the lungs. RhCC16 limited the progression of emphysema, small airway fibrosis, and chronic bronchitis-like disease in WT and Cc16-/- mice partly by reducing pulmonary inflammation (reducing myeloid leukocytes and/or increasing regulatory T and/or B cells) and alveolar septal cell apoptosis, reducing NF-κB activation in CS-exposed Cc16-/- lungs, and rescuing the reduced Foxj1 expression in CS-exposed Cc16-/- lungs. IMD0354 treatment reduced exaggerated lung inflammation and rescued the reduced Foxj1 expression in CS-exposed Cc16-/- mice. RhCC16 treatment reduced NF-κB activation in luciferase reporter A549 cells. Thus, rhCC16 treatment limits COPD progression in CS-exposed Cc16-/- mice partly by inhibiting NF-κB activation and represents a potentially novel therapeutic approach for COPD.

Effects of Z-VaD-Ala-Asp-Fluoromethyl Ketone (Z-VAD-FMK) and Acetyl-Asp-Glu-Val-Asp-Aldehyde(Ac-DEVD-CHO) on Inflammation and Mucus Secretion in Mice Exposed to Cigarette Smoke.

Background and Objectives: Smoking can lead to airway inflammation and mucus secretion through the nucleotide-binding domain-like receptor protein 3/caspase-1 pathway. In this study, z-VaD-Ala-Asp-fluoromethyl ketone(Z-VAD), a pan-caspase inhibitor, and acetyl-Asp-Glu-Val-Asp-aldehyde(Ac-DEVD), a caspase-3 inhibitor, were used to investigate the effect of caspase inhibitors on the expression of interleukin(IL)-1ß and IL-8, airway inflammation, and mucus secretion in mice exposed to cigarette smoke(CS). Methods: Thirty-two C57BL/6J male mice were divided into a control group, Smoke group, Z-VAD group, and Ac-DEVD group. Except for the control group, the animals were all exposed to CS for three months. After the experiment, lung function was measured and hematoxylin and eosin staining and periodic acid-Schiff staining were performed. The levels of IL-1ß, IL-8, and mucin 5ac(Muc5ac) in serum and bronchoalveolar lavage fluid(BALF) were determined by enzyme-linked immunosorbent assay. Results: Compared with the control group, the lung function of mice exposed to smoke was poorer, with a large number of inflammatory cells infiltrating around the airway, collapse of alveoli, expansion and fusion of distal alveoli, and formation of emphysema. The Z-VAD group was relieved compared with the smoke group. Airway inflammation was also reduced in the Ac-DEVD group compared with the Smoke group, but the degree of emphysema was not significantly improved. Although Z-VAD relieved airway inflammation and emphysema, Ac-DEVD only relieved inflammation. Z-VAD and Ac-DEVD decreased serum IL-1ß and IL-8 levels. In BALF, IL-1ß was decreased in Z-VAD group and IL-8 was highest in Smoke +Ac-DEVD group compared with control group and Ac-DEVD group. There was no significant difference in the expression of Muc5ac in serum. However, in BALF, levels of Muc5ac were higher in the smoking group and the lowest in the Ac-DEVD group. Conclusion: Mice exposed to smoke had decreased lung function and significant cilia lodging, epithelial cell shedding, and inflammatory cell infiltration, with significant emphysema formation. The pan-caspase inhibitor, Z-VAD, improved airway inflammation and emphysema lesions in the mice exposed to smoke and reduced IL-1ß and IL-8 levels in serum. The caspase-3 inhibitor, Ac-DEVD, reduced airway inflammation, serum IL-1ß and IL-8 levels, and Muc5ac levels in BALF, but it did not improve emphysema.

Matrix Metalloproteinases in Chronic Obstructive Pulmonary Disease.

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade proteins of the extracellular matrix and the basement membrane. Thus, these enzymes regulate airway remodeling, which is a major pathological feature of chronic obstructive pulmonary disease (COPD). Furthermore, proteolytic destruction in the lungs may lead to loss of elastin and the development of emphysema, which is associated with poor lung function in COPD patients. In this literature review, we describe and appraise evidence from the recent literature regarding the role of different MMPs in COPD, as well as how their activity is regulated by specific tissue inhibitors. Considering the importance of MMPs in COPD pathogenesis, we also discuss MMPs as potential targets for therapeutic intervention in COPD and present evidence from recent clinical trials in this regard.

FOXO3 Activation Prevents Cellular Senescence in Emphysema Induced by Cigarette Smoke.

Because cigarette smoke can induce COPD/emphysema through accelerating senescence with or without an incomplete repair system. However, the pathogenesis of COPD following lung senescence induced by CS is not fully understood. Airspace enlargement and airway epithelial cell senescence are common finding during the COPD development. We investigated the lung tress response to CS and demonstrated that a stress-responsive transcription factor, FOXO3, was regulated by deacetylase. SIRT1 inhibited FOXO3 acetylation and FOXO3 degradation, leading to FOXO3 accumulation and activation in airway epithelial cells. CS exposure activated SIRT1 contributed to FOXO3 activation and functioned to protect lungs, as deletion of SIRT1 decreased CS-induced FOXO3 activation and resulted in more severe airway epithelial cells senescence airspace enlargement. Strikingly, deletion of FOXO3 during the development of COPD aggravated lung structural and functional damage, leading to a much more profound COPD phenotype. We show that deletion of FOXO3 resulted in decreased autophagic response and increased senescence, which may explain lung protection by FOXO3. Our study indicates that in the COPD, stress-responsive transcription factors can be activated for adaptions to counteract senescence insults, thus attenuating COPD development.