Caspase-4 promotes metastasis and interferon-γ-induced pyroptosis in lung adenocarcinoma.

Caspase-4 (CASP4) is a member of the inflammatory caspase subfamily and promotes inflammation. Here, we report that CASP4 in lung adenocarcinoma cells contributes to both tumor progression via angiogenesis and tumor hyperkinesis and tumor cell killing in response to high interferon (IFN)-γ levels. We observe that elevated CASP4 expression in the primary tumor is associated with cancer progression in patients with lung adenocarcinoma. Further, CASP4 knockout attenuates tumor angiogenesis and metastasis in subcutaneous tumor mouse models. CASP4 enhances the expression of genes associated with angiogenesis and cell migration in lung adenocarcinoma cell lines through nuclear factor kappa-light chain-enhancer of activated B cell signaling without stimulation by lipopolysaccharide or tumor necrosis factor. CASP4 is induced by endoplasmic reticulum stress or IFN-γ via signal transducer and activator of transcription 1. Most notably, lung adenocarcinoma cells with high CASP4 expression are more prone to IFN-γ-induced pyroptosis than those with low CASP4 expression. Our findings indicate that the CASP4 level in primary lung adenocarcinoma can predict metastasis and responsiveness to high-dose IFN-γ therapy due to cancer cell pyroptosis.

Intratracheal instillation of polyacrylic acid induced pulmonary fibrosis with elevated transforming growth factor-ß1 and connective tissue growth factor.

We investigated the intratracheal instillation of Polyacrylic acid (PAA) in rats to determine if it would cause pulmonary disorders, and to see what factors would be associated with the pathological changes. Male F344 rats were intratracheally instilled with low (0.2 mg/rat) and high (1.0 mg/rat) doses of PAA. They were sacrificed at 3 days, 1 week, 1 month, 3 months, and 6 months after PAA exposure to examine inflammatory and fibrotic changes in the lungs. There was a persistent increase in the neutrophil count, lactate dehydrogenase (LDH) levels, cytokine-induced neutrophil chemoattractant (CINC) values in bronchoalveolar lavage fluid (BALF), and heme oxygenase-1 (HO-1) in lung tissue. Transforming growth factor-beta 1 (TGF-ß1), a fibrotic factor, showed a sustained increase in the BALF until 6 months after intratracheal instillation, and connective tissue growth factor (CTGF) in lung tissue was elevated at 3 days after exposure. Histopathological findings in the lung tissue showed persistent (more than one month) inflammation, fibrotic changes, and epithelial-mesenchymal transition (EMT) changes. There was also a strong correlation between TGF-ß1 in the BALF and, especially, in the fibrosis score of histopathological specimens. Intratracheal instillation of PAA induced persistent neutrophilic inflammation, fibrosis, and EMT in the rats' lungs, and TGF-ß1 and CTGF appeared to be associated with the persistent fibrosis.

The Effects of Endoplasmic Reticulum Stress via Intratracheal Instillation of Water-Soluble Acrylic Acid Polymer on the Lungs of Rats.

Polyacrylic acid (PAA), an organic chemical, has been used as an intermediate in the manufacture of pharmaceuticals and cosmetics. It has been suggested recently that PAA has a high pulmonary inflammatory and fibrotic potential. Although endoplasmic reticulum stress is induced by various external and intracellular stimuli, there have been no reports examining the relationship between PAA-induced lung injury and endoplasmic reticulum stress. F344 rats were intratracheally instilled with dispersed PAA (molecular weight: 269,000) at low (0.5 mg/mL) and high (2.5 mg/mL) doses, and they were sacrificed at 3 days, 1 week, 1 month, 3 months and 6 months after exposure. PAA caused extensive inflammation and fibrotic changes in the lungs' histopathology over a month following instillation. Compared to the control group, the mRNA levels of endoplasmic reticulum stress markers Bip and Chop in BALF were significantly increased in the exposure group. In fluorescent immunostaining, both Bip and Chop exhibited co-localization with macrophages. Intratracheal instillation of PAA induced neutrophil inflammation and fibrosis in the rat lung, suggesting that PAA with molecular weight 269,000 may lead to pulmonary disorder. Furthermore, the presence of endoplasmic reticulum stress in macrophages was suggested to be involved in PAA-induced lung injury.

The impact of chronic obstructive pulmonary disease on bone strength.

Chronic obstructive pulmonary disease (COPD) is a lifestyle-related disease that develops in middle-aged and older adults, often due to smoking habits, and has been noted to cause bone fragility. COPD is a risk factor for osteoporosis and fragility fracture, and a high prevalence of osteoporosis and incidence of vertebral fractures have been shown in patients with COPD. Findings of lung tissue analysis in patients with COPD are primarily emphysema with a loss of alveolar septal walls, and the severity of pulmonary emphysema is negatively correlated with thoracic spine bone mineral density (BMD). On the other hand, epidemiological studies on COPD and fracture risk have reported a BMD-independent increase in fracture risk; however, verification in animal models and human bone biopsy samples has been slow, and the essential pathogenesis has not been elucidated. The detailed pathological/molecular mechanisms of musculoskeletal complications in patients with COPD are unknown, and basic research is needed to elucidate the mechanisms. This paper discusses the impacts of COPD on bone strength, focusing on findings in animal models in terms of bone microstructure, bone metabolic dynamics, and material properties.

Delayed cortical bone healing due to impaired nuclear Nrf2 translocation in COPD mice.

The effect of the pathogenesis of chronic obstructive pulmonary disease (COPD) on bone fracture healing is unknown. Oxidative stress has been implicated in the systemic complications of COPD, and decreased activity of Nrf2 signaling, a central component of the in vivo antioxidant mechanism, has been reported. We investigated the process of cortical bone repair in a mouse model of elastase-induced emphysema by creating a drill hole and focusing on Nrf2 and found that the amount of new bone in the drill hole was reduced and bone formation capacity was decreased in the model mice. Furthermore, nuclear Nrf2 expression in osteoblasts was reduced in model mice. Sulforaphane, an Nrf2 activator, improved delayed cortical bone healing in model mice. This study indicates that bone healing is delayed in COPD mice and that impaired nuclear translocation of Nrf2 is involved in delayed cortical bone healing, suggesting that Nrf2 may be a novel target for bone fracture treatment in COPD patients.

Pulmonary disorder induced by cross-linked polyacrylic acid.

OBJECTIVES: Organic polymers are materials widely used in our daily lives, such as daily necessities, foods, and medicines. There have been reports recently that cross-linked polyacrylic acid (CL-PAA) can possibly cause serious lung disease. We investigated whether intratracheal instillation of CL-PAA causes pulmonary disorder in rats. METHODS: Male F344 rats were administered low (0.2 mg/rat) and high (1.0 mg/rat) doses of CL-PAA intratracheally and were dissected 3 days, 1 week, 1 month, 3 months, and 6 months after exposure to examine inflammatory and fibrotic responses in the lungs. Only the high-dose specimens were subjected to ultrasonic dispersion treatment of the administered material. RESULTS: There was a dose-dependent increase in the total cell count, neutrophil count, neutrophil percentage, lactate dehydrogenase (LDH), surfactant protein D (SP-D), cytokine-induced neutrophil chemoattractant (CINC)-1 and CINC-2 values in bronchoalveolar lavage fluid (BALF) from 3 days to at least 3 months after intratracheal administration of CL-PAA. Heme oxygenase-1 (HO-1) in lung tissue was also persistently elevated from 3 days to 6 months after exposure. Alkaline phosphatase (ALP) in BALF was elevated at 3 days and 1 month after exposure only in the high-dose group. Histopathological findings in lung tissue showed inflammatory and fibrotic changes from 3 days after administration, and we observed obvious inflammatory changes for up to 3 months and fibrotic changes for up to 6 months. CONCLUSION: Intratracheal administration of CL-PAA induced persistent neutrophilic inflammation and fibrosis in the rats' lungs, suggesting that CL-PAA may have inflammogenic and fibrogenic effects.

Chewing Behavior Attenuates Lung-Metastasis-Promoting Effects of Chronic Stress in Breast-Cancer Lung-Metastasis Model Mice.

We assessed the effects of chewing behavior on the lung-metastasis-promoting impact of chronic psychological-stress in mice. Human breast-cancer cells (MDA-MB-231) were injected into the tail vein of female nude mice. Mice were randomly divided into stress, stress-with-chewing, and control groups. We created chronic stress by placing mice in small transparent tubes for 45 min, 3 times a day for 7 weeks. Mice in the stress-with-chewing group were allowed to chew wooden sticks during the experimental period. The histopathological examination showed that chronic psychological-stress increased lung metastasis, and chewing behavior attenuated the stress-related lung metastasis of breast-cancer cells. Chewing behavior decreased the elevated level of the serum corticosterone, normalized the increased expression of glucocorticoid, and attenuated the elevated expression of adrenergic receptors in lung tissues. We also found that chewing behavior normalized the elevated expression of inducible nitric oxide synthase, 4-hydroxynonenal, and superoxide dismutase 2 in lung tissues, induced by chronic stress. The present study demonstrated that chewing behavior could attenuate the promoting effects of chronic psychological-stress on the lung metastasis of breast-cancer cells, by regulating stress hormones and their receptors, and the downstream signaling-molecules, involving angiogenesis and oxidative stress.

Crosslinked Structure of Polyacrylic Acid Affects Pulmonary Fibrogenicity in Rats.

We conducted intratracheal instillations of polyacrylic acid (PAA) with crosslinking and non-crosslinking into rats in order to examine what kinds of physicochemical characteristics of acrylic-acid-based polymers affect responses in the lung. F344 rats were intratracheally exposed to similar molecular weights of crosslinked PAA (CL-PAA) (degree of crosslinking: ~0.1%) and non-crosslinked PAA (Non-CL-PAA) at low and high doses. Rats were sacrificed at 3 days, 1 week, 1 month, 3 months, and 6 months post-exposure. Both PAAs caused increases in neutrophil influx, cytokine-induced neutrophil chemoattractants (CINC) in the bronchoalveolar lavage fluid (BALF), and heme oxygenase-1 (HO-1) in the lung tissue from 3 days to 6 months following instillation. The release of lactate dehydrogenase (LDH) activity in the BALF was higher in the CL-PAA-exposed groups. Histopathological findings of the lungs demonstrated that the extensive fibrotic changes caused by CL-PAA were also greater than those in exposure to the Non-CL- PAA during the observation period. CL-PAA has more fibrogenicity of the lung, suggesting that crosslinking may be one of the physicochemical characteristic factors of PAA-induced lung disorder.

Pulmonary toxicity of tungsten trioxide nanoparticles in an inhalation study and an intratracheal instillation study.

OBJECTIVES: We conducted inhalation and intratracheal instillation studies in order to examine the effects of tungsten trioxide (WO3 ) nanoparticles on the lung, and evaluated whether or not the nanoparticles would cause persistent lung inflammation. METHODS: In the inhalation study, male 10-week-old Fischer 334 rats were classified into 3 groups. The control, low-dose, and high-dose groups inhaled clean air, 2, and 10 mg/m3 WO3 nanoparticles, respectively, for 6 h each day for 4 weeks. The rats were dissected at 3 days, 1 month, and 3 months after the inhalation, and the bronchoalveolar lavage fluid (BALF) and lung tissue were examined. In the intratracheal instillation study, male 12-week-old Fischer 334 rats were divided into 3 subgroups. The control, low-dose, and high-dose groups were intratracheally instilled 0.4 ml distilled water, 0.2, and 1.0 mg WO3 nanoparticles, respectively, dissolved in 0.4 ml distilled water. The rats were sacrificed at 3 days, 1 week, and 1 month after the intratracheal instillation, and the BALF and lung tissue were analyzed as in the inhalation study. RESULTS: The inhalation and instillation of WO3 nanoparticles caused transient increases in the number and rate of neutrophils, cytokine-induced neutrophil chemoattractant (CINC)-1, and CINC-2 in BALF, but no histopathological changes or upregulation of heme oxygenase (HO)-1 in the lung tissue. CONCLUSION: Our results suggest that WO3 nanoparticles have low toxicity to the lung. According to the results of the inhalation study, we also propose that the no observed adverse effect level (NOAEL) of WO3 nanoparticles is 2 mg/m3 .

Oxidative stress causes muscle structural alterations via p38 MAPK signaling in COPD mouse model.

INTRODUCTION: Sarcopenia is a complication of Chronic Obstructive Pulmonary Disease (COPD) that negatively affects physical activity and quality of life. However, the underlying mechanism by which COPD affects skeletal muscles remains to be elucidated. Therefore, we investigated the association between oxidative stress and structural alterations in muscles in elastase-induced emphysema mouse models. MATERIALS AND METHODS: Twelve-week-old male C57BL/6J mice were treated with either intratracheal porcine pancreatic elastase (PPE) dissolved in saline, or saline alone. The mice were euthanized 12 weeks after treatment, and the lungs and limb muscles were used for protein analysis of oxidative stress, p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway and muscle atrophy signaling pathway related with oxidative stress. Furthermore, C57BL/6J mice treated with PPE or saline were analyzed for the effects of oral administration of astaxanthin or p38 inhibitor. RESULTS: The weight of the soleus muscle, proportion of type I muscle fibers, and cross-sectional areas of muscle fibers in the PPE group were lower than those in the control group. Oxidative stress marker levels in the PPE group were elevated in skeletal muscles. The p38 MAPK signaling pathway was activated in the soleus muscles, leading to the activation of the ubiquitin-proteasome system and autophagy. Astaxanthin and p38 inhibitors attenuated alterations in muscle structure through the deactivation of the p38 MAPK signaling pathway. CONCLUSIONS: This study provides first evidence in COPD mouse model that oxidative stress trigger a series of muscle structural changes. Our findings suggest a novel target for sarcopenia in COPD.

Effect of Different Molecular Weights of Polyacrylic Acid on Rat Lung Following Intratracheal Instillation.

BACKGROUND: We conducted intratracheal instillations of different molecular weights of polyacrylic acid (PAA) into rats in order to examine what kinds of physicochemical characteristics of acrylic acid-based polymer affect responses in the lung. METHODS: F344 rats were intratracheally exposed to a high molecular weight (HMW) of 598 thousand g/mol or a low molecular weight (LMW) of 30.9 thousand g/mol PAA at low and high doses. Rats were sacrificed at 3 days, 1 week, 1 month, 3 months and 6 months post exposure. RESULTS: HMW PAA caused persistent increases in neutrophil influx, cytokine-induced neutrophil chemoattractants (CINC) in the bronchoalveolar lavage fluid (BALF), and heme oxygenase-1 (HO-1) in the lung tissue from 3 days to 3 months and 6 months following instillation. On the other hand, LMW PAA caused only transient increases in neutrophil influx, CINC in BALF, and HO-1 in the lung tissue from 3 days to up to 1 week or 1 month following instillation. Histopathological findings of the lungs demonstrated that the extensive inflammation and fibrotic changes caused by the HMW PAA was greater than that in exposure to the LMW PAA during the observation period. CONCLUSION: HMW PAA induced persistence of lung disorder, suggesting that molecular weight is a physicochemical characteristic of PAA-induced lung disorder.

Deletion of Wnt10a Is Implicated in Hippocampal Neurodegeneration in Mice.

The hippocampus plays an important role in maintaining normal cognitive function and is closely associated with the neuropathogenesis of dementia. Wnt signaling is relevant to neuronal development and maturation, synaptic formation, and plasticity. The role of Wnt10a in hippocampus-associated cognition, however, is largely unclear. Here, we examined the morphological and functional alterations in the hippocampus of Wnt10a-knockout (Wnt10a-/-) mice. Neurobehavioral tests revealed that Wnt10a-/- mice exhibited spatial memory impairment and anxiety-like behavior. Immunostaining and Western blot findings showed that the protein expressions of ß-catenin, brain-derived neurotrophic factor, and doublecortin were significantly decreased and that the number of activated microglia increased, accompanied by amyloid-ß accumulation, synaptic dysfunction, and microglia-associated neuroinflammation in the hippocampi of Wnt10a-/- mice. Our findings revealed that the deletion of Wnt10a decreased neurogenesis, impaired synaptic function, and induced hippocampal neuroinflammation, eventually leading to hippocampal neurodegeneration and memory deficit, possibly through the ß-catenin signaling pathway, providing a novel insight into preventive approaches for hippocampus-dependent cognitive impairment.

Novel roles of LSECtin in gastric cancer cell adhesion, migration, invasion, and lymphatic metastasis.

Liver and lymph node sinusoidal endothelial cell C-type lectin (LSECtin) plays an important regulatory role in a variety of diseases, including tumors. However, the underlying mechanism of LSECtin in gastric cancer (GC) remains largely unknown. In our research, LSECtin promoted the adhesion and invasion of GC cells, and was involved in lymphatic metastasis of GC cells. Mechanistically, LSECtin promoted the adhesion, proliferation and migration of GC cells by downregulating STAT1 expression. The circular RNA circFBXL4, which is regulated by LSECtin, sponges the microRNA miR-146a-5p to regulate STAT1 expression. The promotion of GC cell proliferation, migration and invasion mediated by LSECtin was largely inhibited by circFBXL4 overexpression or miR-146a-5p silencing. Moreover, in its role as a transcription factor, STAT1 modulated the expression of FN1 and CHD4. In conclusion, LSECtin might be involved in the lymphatic metastasis of GC by upregulating the expression of FN1 and CHD4 via the circFBXL4/miR-146a-5p/STAT1 axis, possibly indicating a newly discovered pathogenic mechanism.

Deficiency of Wnt10a causes female infertility via the ß-catenin/Cyp19a1 pathway in mice.

Wnt signaling is relevant for a wide range of biological processes, including reproductive function. The function of Wnt10a in female fertility, however, remains obscure. In the present study, we explored the structure and function of the female reproductive organs in Wnt10a knockout (KO) mice. The expression of ß-catenin signaling was significantly lower in the ovaries of the Wnt10a KO mice compared with wild-type (WT) mice. In addition, the estrous cycles were disrupted, ovarian follicles were diminished, and endometria were thinner, accompanied by lower serum estrogen levels, and higher testosterone and progesterone levels in Wnt10a KO mice. The expression of the ovarian cytochrome P450 family 19 subfamily A member 1 (Cyp19a1) was significantly lower in Wnt10a KO mice. We detected no significant changes in the levels of the gonadotropins between WT and KO mice. Together, our findings indicate that deficiency of Wnt10a causes female infertility through ß-catenin and Cyp19a1signaling pathways in mice.

Engineering Properties of New Claw Connectors for Alkali-Resistant Glass-Fiber-Reinforced Plastics.

To optimize the engineering properties of connectors, a new claw-shaped alkali-resistant glass-fiber-composite-reinforced connection member was designed in this study. Tensile, shear, and durability tests were conducted on the joint. Moreover, numerical analysis was performed, and the performance of the proposed connector was verified in engineering applications. Hence, the following conclusions hold: (1) At the same shear diameter and anchorage depth, the anchorage performance and shear resistance of claw connectors are better than those of rod connectors. (2) Claw connectors with an anchorage depth of 3.5 cm and a hollow joint with an outer diameter of 14 mm exhibit an excellent overall performance. (3) Alkali-resistant glass-fiber-reinforced plastics exhibit good durability. (4) The ANSYS numerical model can be used to accurately predict the load-displacement variation law of the pull-out and shear of the connectors. (5) Through research, it has been proven that claw-shaped connectors have good pull-out resistance, shear resistance, and durability, and the structure has good stability in engineering applications. Therefore, the structure can provide a significant reference for similar projects.

Feasibility Study on the Steel-Plastic Geogrid Instead of Wire Mesh for Bolt Mesh Supporting.

Wire mesh is a common material for bolt mesh supporting structures, but its application in engineering has revealed many defects. At the same time, with the development of new materials for civil engineering, the new material mesh performance and cost show outstanding advantages over wire mesh. In this paper, the feasibility of replacing wire mesh with steel-plastic geogrid as an alternative material is carefully studied through indoor tests and field applications. The following conclusions were drawn from a comparative analysis with wire mesh, mainly in terms of mechanical properties, engineering characteristics, and construction techniques: (1) in terms of mesh wire strength, wire mesh is slightly better than steel-plastic geogrid, but in the case of similar tensile strength, the amount of steel used per unit length of steel geogrid bars is only 36.75% of that of steel-plastic geogrid, while the tensile strength of the high-strength steel wire attached to the steel-plastic geogrid belt is about 3.3 times that of steel bars; (2) in terms of junction peel strength, both values are similar, with the injection-moulded junction being 1154.56-1224.38 N and the welded junction of 4 mm mesh being 988.35 N; (3) in terms of the strength of the mesh, steel-plastic geogrid is better than wire mesh, and with the same mesh wire strength, the bearing capacity of steel-plastic geogrid is increased by about 63.17% and the contribution of the mesh wire bearing capacity is increased by 83.66%, with the damage mainly being in the form of wire breakage in the ribbon causing ribbon failure, leading to further damage to the mesh; (4) in terms of the engineering application of steel-plastic geogrid compared to wire mesh, the utilization rate of mesh increases by about 24.99%, the construction efficiency increases by about 14.10%, and the economic benefit increases by about 45.31%. In practical application, the steel-plastic geogrid has good adhesion with surrounding rock and strong corrosion resistance. According to the above research analysis, the steel-plastic geogrid is feasible to replace the wire mesh for bolt mesh supporting.

Inflammogenic effect of polyacrylic acid in rat lung following intratracheal instillation.

BACKGROUND: Some organic chemicals are known to cause allergic disorders such as bronchial asthma and hypersensitivity pneumonitis, and it has been considered that they do not cause irreversible pulmonary fibrosis. It has recently been reported, however, that cross-linked acrylic acid-based polymer, an organic chemical, might cause serious interstitial lung diseases, including pulmonary fibrosis. We investigated whether or not intratracheal instillation exposure to cross-linked polyacrylic acid (CL-PAA) can cause lung disorder in rats. METHODS: Male F344 rats were intratracheally instilled with dispersed CL-PAA at low (0.2 mg/rat) and high (1.0 mg/rat) doses, and were sacrificed at 3 days, 1 week, 1 month, 3 months and 6 months after exposure to examine inflammatory and fibrotic responses and related gene expressions in the lungs. Rat lungs exposed to crystalline silica, asbestos (chrysotile), and NiO and CeO2 nanoparticles were used as comparators. RESULTS: Persistent increases in total cell count, neutrophil count and neutrophil percentage, and in the concentration of the cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-2 and C-X-C motif chemokine 5 (CXCL5), which correlated with lung tissue gene expression, were observed in bronchoalveolar lavage fluid (BALF) from 3 days until at least 1 month following CL-PAA intratracheal instillation. Persistent increases in heme oxygenase-1 (HO-1) in the lung tissue were also observed from 3 days to 6 months after exposure. Histopathological findings of the lungs demonstrated that extensive inflammation at 3 days was greater than that in exposure to silica, NiO nanoparticles and CeO2 nanoparticles, and equal to or greater than that in asbestos (chrysotile) exposure, and the inflammation continued until 1 month. Fibrotic changes also progressed after 1 month postexposure. CONCLUSION: Our results suggested that CL-PAA potentially causes strong neutrophil inflammation in the rat and human lung.

Development of a novel knee contracture mouse model by immobilization using external fixation.

AIMS: Several studies have used animal models to examine knee joint contracture; however, few reports detail the construction process of a knee joint contracture model in a mouse. The use of mouse models is beneficial, as genetically modified mice can be used to investigate the pathogenesis of joint contracture. Compared to others, mouse models are associated with a lower cost to evaluate therapeutic effects. Here, we describe a novel knee contracture mouse model by immobilization using external fixation. METHODS: The knee joints of mice were immobilized by external fixation using a splint and tape. The passive extension range of motion (ROM), histological and immunohistochemical changes, and expression levels of fibrosis-related genes at 2 and 4 weeks were compared between the immobilized (Im group) and non-immobilized (Non-Im group) groups. RESULTS: The extension ROM at 4 weeks was significantly lower in the Im group than in the Non-Im group (p < 0.01). At 2 and 4 weeks, the thickness and area of the joint capsule were significantly greater in the Im group than in the Non-Im group (p < 0.01 in all cases). At 2 weeks, the mRNA expression levels of the fibrosis-related genes, except for the transforming growth factor-ß1, and the protein levels of cellular communication network factor 2 and vimentin in the joint capsule were significantly higher in the Im group (p < 0.01 in all cases). CONCLUSION: This mouse model may serve as a useful tool to investigate the etiology of joint contracture and establish new treatment methods.

Spontaneous pulmonary emphysema in mice lacking all three nitric oxide synthase isoforms.

The roles of endogenous nitric oxide (NO) derived from the entire NO synthases (NOSs) system have yet to be fully elucidated. We addressed this issue in mice in which all three NOS isoforms were deleted. Under basal conditions, the triple n/i/eNOSs-/- mice displayed significantly longer mean alveolar linear intercept length, increased alveolar destructive index, reduced lung elastic fiber content, lower lung field computed tomographic value, and greater end-expiratory lung volume as compared with wild-type (WT) mice. None of single NOS-/- or double NOSs-/- genotypes showed such features. These findings were observed in the triple n/i/eNOSs-/- mice as early as 4 weeks after birth. Cyclopaedic and quantitative comparisons of mRNA expression levels between the lungs of WT and triple n/i/eNOSs-/- mice by cap analysis of gene expression (CAGE) revealed that mRNA expression levels of three Wnt ligands and ten Wnt/ß-catenin signaling components were significantly reduced in the lungs of triple n/i/eNOSs-/- mice. These results provide the first direct evidence that complete disruption of all three NOS genes results in spontaneous pulmonary emphysema in juvenile mice in vivo possibly through down-regulation of the Wnt/ß-catenin signaling pathway, demonstrating a novel preventive role of the endogenous NO/NOS system in the occurrence of pulmonary emphysema.