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Background: Chronic obstructive pulmonary disease (COPD) is among the top 5 causes of mortality in the world and can develop as a consequence of genetic and/or environmental factors. Current efforts are focused on identifying early life insults and how these contribute to COPD development. In line with this, our study focuses on the influence of early life nicotine exposure and its potential impact on (a) lung pulmonary functions, and (b) elastase-induced emphysema in adulthood., Methods: To address this hypothesis, we developed a model of 2 hits, delivered at different time points: mouse pups were first exposed to nicotine/placebo in utero and during lactation, and then subsequently received elastase/placebo at the age of 11 weeks. The effect of nicotine pretreatment and elastase instillation was assessed by (a) measurement of pulmonary function at post-elastase day (ped) 21, and (b) transcriptomic profiling at ped3 and 21, and complementary protein determination. Statistical significance was determined by 3- and 2-way ANOVA for pulmonary functions, and RNAseq results were analyzed using the R project., Results: We did not observe any impact of nicotine pre- and early post-natal exposure compared to control samples on lung pulmonary functions in adulthood, as measured by FLEXIVENT technology. After elastase instillation, substantial lung damage was detected by x-ray tomography and was accompanied by loss in body weight at ped3 as well as an increase in cell numbers, inflammatory markers in BAL and lung volume at ped21. Lung functions showed a decrease in elastance and an increase in deep inflation volume and pressure volume (pv) loop area in animals with emphysema at ped21. Nicotine had no effect on elastance and deep inflation volume, but did affect the pv loop area in animals with emphysema at ped21. Extensive transcriptomic changes were induced by elastase at ped3 both in the nicotine-pretreated and the control samples, with several pathways common to both groups, such as for cell cycle, DNA adhesion and DNA damage. Nicotine pretreatment affected the number of lymphocytes present in BAL after elastase instillation and some of the complement pathway related proteins, arguing for a slight modification of the immune response, as well as changes related to general body metabolism. The majority of elastase-induced transcriptomic changes detected at ped3 had disappeared at ped21. In addition, transcriptomic profiling singled out a common gene pool that was independently activated by nicotine and elastase., Conclusions: Our study reports a broad spectrum of transient transcriptomic changes in mouse emphysema and identifies nicotine as influencing the emphysema-associated immune system response., (© 2022. The Author(s).)

The receptor for advanced glycation end-products (RAGE) has been implicated in the pathophysiology of chronic obstructive pulmonary disease (COPD). However, it is still unknown whether RAGE directly contributes to alveolar epithelial damage and abnormal repair responses. We hypothesize that RAGE activation not only induces lung tissue damage but also hampers alveolar epithelial repair responses. The effects of the RAGE ligands LL-37 and HMGB1 were examined on airway inflammation and alveolar tissue damage in wild-type and RAGE-deficient mice and on lung damage and repair responses using murine precision cut lung slices (PCLS) and organoids. In addition, their effects were studied on the repair response of human alveolar epithelial A549 cells, using siRNA knockdown of RAGE and treatment with the RAGE inhibitor FPS-ZM1. We observed that intranasal installation of LL-37 and HMGB1 induces RAGE-dependent inflammation and severe alveolar tissue damage in mice within 6 h, with stronger effects in a mouse strain susceptible for emphysema compared with a nonsusceptible strain. In PCLS, RAGE inhibition reduced the recovery from elastase-induced alveolar tissue damage. In organoids, RAGE ligands reduced the organoid-forming efficiency and epithelial differentiation into pneumocyte-organoids. Finally, in A549 cells, we confirmed the role of RAGE in impaired repair responses upon exposure to LL-37. Together, our data indicate that activation of RAGE by its ligands LL-37 and HMGB1 induces acute lung tissue damage and that this impedes alveolar epithelial repair, illustrating the therapeutic potential of RAGE inhibitors for lung tissue repair in emphysema.

Histidine treatment has anti-inflammatory effects on several diseases such as colitis and obesity. We revealed that histidine levels were decreased in the serum of patients with chronic obstructive pulmonary disease (COPD) in our previous study. However, whether histidine confers protection against COPD is unclear. In the present study, we evaluated the protective effects of histidine in a porcine pancreatic elastase- and lipopolysaccharide-induced COPD mouse model. We found that the serum histidine concentration was decreased in COPD mice. Histidine supplementation improved the COPD mouse lung function and reduced the inflammatory cell counts and production of cytokines in bronchoalveolar lavage fluid. In addition, histidine treatment ameliorated lung inflammation by inhibiting the nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 3 inflammasome activation both in vivo and in vitro. Furthermore, we found that the potential anti-inflammatory mechanism involved the upregulation of silent information regulator factor 2-related enzyme 1. These results suggest that histidine may be a valuable therapeutic target for COPD., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Alpha-1 antitrypsin (AAT) is a major serine protease inhibitor. AAT deficiency (AATD) is a genetic disorder characterized by early-onset severe emphysema. In well-selected AATD patients, therapy with plasma-derived AAT (pAAT), "augmentation therapy", provides modest clinical improvement but is perceived as cumbersome with weekly intravenous infusions. Using mouse models of emphysema, we compared the effects of a recombinant AAT-IgG1 Fc-fusion protein (AAT-Fc), which is expected to have a longer half-life following infusion, to those of pAAT., Methods: In an elastase model of emphysema, mice received a single intratracheal instillation of porcine pancreatic elastase (PPE) or human leucocyte elastase (hLE). AAT-Fc, pAAT, or vehicle was administered intraperitoneally 1 day prior to or 3 weeks following elastase instillation. Lung function and histology assessments were performed at 7 and 32 days after elastase instillation. In a cigarette smoke (CS) model of emphysema, mice were exposed to CS daily, 5 days a week, for 6 months and AAT-Fc, pAAT, or vehicle were administered every 10 days during the last 3 months of CS exposure. Assessments were performed 3 days after the last CS exposure. Immune responses to lung elastin peptide (EP) and the effects of AAT-Fc or pAAT treatment on dendritic cell (DC) function were determined ex vivo., Results: Both elastase instillation and CS exposure triggered emphysema-like alveolar enlargement, increased lung compliance, and increased markers of inflammation compared to controls. Administration of AAT-Fc either prior to or following elastase instillation or during CS exposure provided greater protection than pAAT against alveolar enlargement, lung dysfunction, and airway inflammation. When challenged ex vivo with EP, spleen mononuclear cells from elastase-exposed mice exhibited dose-dependent production of IFNγ and IL-17, suggesting immune reactivity. In co-culture experiments with splenic CD4 + T cells isolated from elastase-exposed mice, AAT-Fc treatment prior to EP-priming of bone marrow-derived dendritic cells inhibited the production of IFNγ and IL-17., Conclusions: Compared to pAAT, AAT-Fc more effectively prevented or attenuated elastase- and CS-induced models of emphysema. These effects were associated with immunomodulatory effects on DC activity. AAT-Fc may provide a therapeutic option to individuals with AATD- and CS-induced emphysema., (© 2021. The Author(s).)

Betanin, a bioactive ingredient mostly isolated from beetroots, exhibits a protective effect against cardiovascular diseases. However, its effects on abdominal aortic aneurysm (AAA) have not been elucidated. In this study, an AAA model was constructed by infusion of porcine pancreatic elastase in C57BL/6 mice. Mice were then administered with betanin or saline intragastrically once daily for 14 d. Our results showed that treatment with betanin remarkably limited AAA enlargement and mitigated the infiltration of inflammatory cells in the adventitia. The increased expression of proinflammatory cytokines and matrix metalloproteinases (MMPs) was also significantly alleviated following betanin treatment. Furthermore, betanin suppressed the activation of toll-like receptor 4 (TLR4)/nuclear factor-kappaB (NF-κB) signaling in the aortic wall, and downregulated the levels of tissue-reactive oxygen species as well as circulating 8-isoprostane by stimulating the nuclear factor-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. Taken together, these data suggest that betanin may attenuate AAA progression and may be used as a therapeutic drug against AAA.

Background and Purpose: While WEB devices have been shown to be safe and effective for aneurysm treatment, WEB-shape modification compression has been associated with incomplete aneurysm occlusion. We explored the relationship between occlusion rates and WEB-shape modification in different WEB device types in an experimental aneurysm model., Materials and Methods: Elastase-induced aneurysms were created in rabbits and treated with dual-layer ( n  = 12), single-layer ( n  = 12), or single-layer sphere ( n  = 12) WEB devices. Aneurysms were followed up either at 3 or 12 months. Angiographic occlusion was graded using the WEB Occlusion Scale: grade I, complete; grade II, complete but recess filling; grade III, residual neck; or grade IV, residual aneurysm. WEB-shape modification and histologic features were also analyzed., Results: Grade I or II occlusion was seen in 16 (44%) aneurysms, and grade I, II, or III ("adequate") occlusion was observed in 22 (61.1%) aneurysms at follow-up. WEB-shape modification was observed in 22 (61.1%) aneurysms. WEB-shape modification was higher in single-layer (9/12) and dual-layer (10/12) devices compared with single-layer sphere devices (3/12). Aneurysms with WEB-shape modification had a higher level of thrombus organization in the dome compared with those without WEB-shape modification (68% [15/22] versus 50% [7/14]). WEB-shape modification was not correlated with angiographic or histologic outcomes but was significantly correlated with levels of fibrosis and smooth muscle cells in the aneurysm., Conclusions: WEB-shape modification is not associated with incomplete aneurysm occlusion of WEB devices in the rabbit model but may be related to connective tissue formation and the healing response to WEB device implantation., (© 2021 by American Journal of Neuroradiology.)

Hyaluronic acid (HA) is a key component of the extracellular matrix of the lungs. A unique attribute of HA is its water-retaining properties, so HA has a major role in the regulation of fluid balance in the lung interstitium. Hyaluronic acid has been widely used in the treatment of eyes, ears, joints and skin disorders, but in the last years, it has been also proposed in the treatment of certain lung diseases, including airway diseases, due to its anti-inflammatory and water-binding capacities. Hyaluronic acid aerosol decreases the severity of elastase-induced emphysema in murine models, prevents bronchoconstriction in asthmatics and improves some functional parameters in chronic obstructive pulmonary disease (COPD) patients. Due to the protection of HA against bronchoconstriction and its hydration properties, inhaled HA would increase the volume of airway surface liquid, resulting in mucus hydration, increased mucous transport and less mucous plugging of the airways. In addition, it has been seen in human studies that the treatment with nebulised HA improves the tolerability of nebulised hypertonic saline (even at 6% or 7% of concentration), which has been demonstrated to be an effective treatment in bronchial secretion management in patients with cystic fibrosis and bronchiectasis. Our objective is to review the role of HA treatment in the management of chronic airway diseases.

Aim: Abdominal aortic aneurysms (AAA) is a life-threatening weakening and expansion of the abdominal aorta due to inflammatory cell infiltration and gradual degeneration of extracellular matrix (ECM). There are no pharmacological therapies to treat AAA. We tested the hypothesis that nanoparticle (NP) therapy that targets degraded elastin and delivers anti-inflammatory, anti-oxidative, and ECM stabilizing agent, pentagalloyl glucose (PGG) will reverse advance stage aneurysm in an elastase-induced mouse model of AAA., Method and Results: Porcine pancreatic elastase (PPE) was applied periadventitially to the infrarenal aorta in mice and AAA was allowed to develop for 14 days. Nanoparticles loaded with PGG (EL-PGG-NPs) were then delivered via IV route at 14-day and 21-day (10 mg/kg of body weight). A control group of mice received no therapy. The targeting of NPs to the AAA site was confirmed with fluorescent dye marked NPs and gold NPs. Animals were sacrificed at 28-d. We found that targeted PGG therapy reversed the AAA by decreasing matrix metalloproteinases MMP-9 and MMP-2, and the infiltration of macrophages in the medial layer. The increase in diameter of the aorta was reversed to healthy controls. Moreover, PGG treatment restored degraded elastic lamina and increased the circumferential strain of aneurysmal aorta to the healthy levels., Conclusion: Our results support that site-specific delivery of PGG with targeted nanoparticles can be used to treat already developed AAA. Such therapy can reverse inflammatory markers and restore arterial homeostasis., Competing Interests: NRV is a significant shareholder in Elastrin therapeutics Inc. who have licensed elastin targeting nanoparticle patent from Clemson University.

Background and Purpose: Abdominal aortic aneurysm (AAA) is a degenerative disease with irreversible and progressive dilation of the artery. But there are few options for efficacious treatment except for traditional surgery. Probucol has been widely applied to treat hyperlipidaemia and atherosclerosis in clinic, but whether it can protect against AAA remains unknown. In this study, the protective effects of probucol against AAA and its related mechanisms were explored., Experimental Approach: The model of AAA was induced in mice by periaortic application of elastase (40 min) to the abdominal aorta. Probucol at different doses was administered by daily gavage, starting on the same day as AAA was induced, for 14 days. In vitro, cultures of rat vascular smooth muscle cells (VSMCs) were stimulated with TNF-α. Haem oxygenase (HO)-1 siRNA and HO-1 plasmid were used to regulate the expression or activity of HO-1 in the VSMCs and to clarify the effects of HO-1., Key Results: Probucol dose-dependently prevented the development of AAA, reflected by decreased incidence of AAA, diameter of aortic dilation, elastin degradation, and infiltration of inflammatory cells. Probucol also protected VSMCs from oxidative injury and enhanced elastin biosynthesis. This anti-inflammatory effects of probucol on VSMCs were significantly decreased when HO-1 was inhibited by siRNA., Conclusion and Implications: Probucol protected against AAA through inhibiting the degradation of elastin induced by inflammation and oxidation and by facilitating the biosynthesis of elastin. HO-1 played a crucial role in the anti-inflammatory effects of probucol in VSMCs., (© 2019 The British Pharmacological Society.)

Introduction: Pulmonary emphysema is a major component of chronic obstructive pulmonary disease (COPD). Emphysema progression attributed not only to alveolar structure loss and pulmonary regeneration impairment, but also to excessive inflammatory response, proteolytic and anti-proteolytic activity imbalance, lung epithelial cells apoptosis, and abnormal lung remodeling. To ameliorate lung damage with higher efficiency in lung tissue engineering and cell therapy, pre-differentiating graft cells into more restricted cell types before transplantation could enhance their ability to anatomically and functionally integrate into damaged lung. In this study, we aimed to evaluate the regenerative and repair ability of lung alveolar epithelium in emphysema model by using lung epithelial progenitors which pre-differentiated from amniotic fluid mesenchymal stem cells (AFMSCs)., Methods: Pre-differentiation of eGFP-expressing AFMSCs to lung epithelial progenitor-like cells (LEPLCs) was established under a modified small airway growth media (mSAGM) for 7-day induction. Pre-differentiated AFMSCs were intratracheally injected into porcine pancreatic elastase (PPE)-induced emphysema mice at day 14, and then inflammatory-, fibrotic-, and emphysema-related indices and pathological changes were assessed at 6 weeks after PPE administration., Results: An optimal LEPLCs pre-differentiation condition has been achieved, which resulted in a yield of approximately 20% lung epithelial progenitors-like cells from AFMSCs in a 7-day period. In PPE-induced emphysema mice, transplantation of LEPLCs significantly improved regeneration of lung tissues through integrating into the lung alveolar structure, relieved airway inflammation, increased expression of growth factors such as vascular endothelial growth factor (VEGF), and reduced matrix metalloproteinases and lung remodeling factors when compared with mice injected with AFMSCs. Histopathologic examination observed a significant amelioration in DNA damage in alveolar cells, detected by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL), the mean linear intercept, and the collagen deposition in the LEPLC-transplanted groups., Conclusion: Transplantation of predifferentiated AFMSCs through intratracheal injection showed better alveolar regeneration and reverse elastase-induced pulmonary emphysema in PPE-induced pulmonary emphysema mice.

Background and Purpose- Inflammation is a critical determinant of aneurysmal wall destabilization, growth, and rupture risk. Targeting inflammation may suppress aneurysm rupture. Vagus nerve stimulation (VNS) has been shown to suppress inflammation both systemically and in the central nervous system. Therefore, we tested the effect of a novel noninvasive transcutaneous VNS approach on aneurysm rupture and outcome in a mouse model of intracranial aneurysm formation with wall inflammation. Methods- Aneurysms were induced by a single stereotaxic injection of elastase into the cerebrospinal fluid at the skull base, combined with systemic deoxycorticosterone-salt hypertension, without or with high-salt diet, for mild or severe outcomes, respectively. Cervical VNS (two 2-minute stimulations 5 minutes apart) was delivered once a day starting from the day after elastase injection for the duration of follow-up. Transcutaneous stimulation of the femoral nerve (FNS) served as control. Multiple aneurysms developed in the circle of Willis and its major branches, resulting in spontaneous ruptures and subarachnoid hemorrhage, neurological deficits, and mortality. Results- In the milder model, VNS significantly reduced aneurysm rupture rate compared with FNS (29% versus 80%, respectively). Subarachnoid hemorrhage grades were also lower in the VNS group. In the more severe model, both VNS and FNS arms developed very high rupture rates (77% and 85%, respectively). However, VNS significantly improved the survival rate compared with FNS after rupture (median survival 13 versus 6 days, respectively), without diminishing the subarachnoid hemorrhage grades. Chronic daily VNS reduced MMP-9 (matrix metalloproteinase-9) expression compared with FNS, providing a potential mechanism of action. As an important control, chronic daily VNS did not alter systemic arterial blood pressure compared with FNS. Conclusions- VNS can reduce aneurysm rupture rates and improve the outcome from ruptured aneurysms.

Objective- Inflammation occurs during the progression of abdominal aortic aneurysm (AAA). IL (interleukin)-33 is a pleiotropic cytokine with multiple immunomodulatory effects, yet its role in AAA remains unknown. Approach and Results- Immunoblot, immunohistochemistry, and immunofluorescent staining revealed increased IL-33 expression in adventitia fibroblasts from mouse AAA lesions. Daily intraperitoneal administration of recombinant IL-33 or transgenic IL-33 expression ameliorated periaorta CaPO 4 injury- and aortic elastase exposure-induced AAA in mice, as demonstrated by blunted aortic expansion, reduced aortic wall elastica fragmentation, enhanced AAA lesion collagen deposition, attenuated T-cell and macrophage infiltration, reduced inflammatory cytokine production, skewed M2 macrophage polarization, and reduced lesion MMP (matrix metalloproteinase) expression and cell apoptosis. Flow cytometry analysis, immunostaining, and immunoblot analysis showed that exogenous IL-33 increased CD4 + Foxp3 + regulatory T cells in spleens, blood, and aortas in periaorta CaPO 4 -treated mice. Yet, ST2 deficiency muted these IL-33 activities. Regulatory T cells from IL-33-treated mice also showed significantly stronger activities in suppressing smooth muscle cell inflammatory cytokine and chemokine expression, macrophage MMP expression, and in increasing M2 macrophage polarization than those from vehicle-treated mice. In contrast, IL-33 failed to prevent AAA and lost its beneficial activities in CaPO 4 -treated mice after selective depletion of regulatory T cells. Conclusions- Together, this study established a role of IL-33 in protecting mice from AAA formation by enhancing ST2-dependent aortic and systemic regulatory T-cell expansion and their immunosuppressive activities.

Although the positive effects of recombinant fibroblast growth factor-2 (rFGF-2) in chronic obstructive pulmonary disease (COPD) have been implicated in previous studies, knowledge of its role in COPD remains limited. The mechanism of FGF2 in a COPD mouse model and the therapeutic potential of rFGF-2 were investigated in COPD. The mechanism and protective effects of rFGF-2 were evaluated in cigarette smoke-exposed or elastase-induced COPD animal models. Inflammation was assessed in alveolar cells and lung tissues from mice. FGF-2 was decreased in the lungs of cigarette smoke-exposed mice. Intranasal use of rFGF-2 significantly reduced macrophage-dominant inflammation and alveolar destruction in the lungs. In the elastase-induced emphysema model, rFGF-2 improved regeneration of the lungs. In humans, plasma FGF-2 was decreased significantly in COPD compared with normal subjects (10 subjects, P = 0.037). The safety and efficacy of inhaled rFGF-2 use was examined in COPD patients, along with changes in respiratory symptoms and pulmonary function. A 2-week treatment with inhaled rFGF-2 in COPD (n = 6) resulted in significantly improved respiratory symptoms compared with baseline levels (P < 0.05); however, the results were not significant compared with the placebo. The pulmonary function test results of COPD improved numerically compared with those in the placebo, but the difference was not statistically significant. No serious adverse events occurred during treatment with inhaled rFGF-2. The loss of FGF-2 production is an important mechanism in the development of COPD. Inhaling rFGF-2 may be a new therapeutic option for patients with COPD because rFGF-2 decreases inflammation in lungs exposed to cigarette smoke.

All-trans retinoic acid (ATRA) or mesenchymal stem cells (MSCs) have been shown to promote lung tissue regeneration in animal models of emphysema. However, the reparative effects of the combination of the two and the role of p70S6 kinase-1 (p70S6k1) activation in the repair process have not been defined. Twenty-one days after intratracheal instillation of porcine pancreatic elastase (PPE), MSC and/or 10 days of ATRA treatment was initiated. Thirty-two days later, static lung compliance (Cst), mean linear intercepts (MLIs), and alveolar surface area (S) were measured. After PPE, mice demonstrated increased values of Cst and MLI, and decreased S values. Both ATRA and MSC transfer were individually effective in improving these outcomes while the combination of ATRA and MSCs was even more effective. The combination of p70S6k1 -/- MSCs transfer followed by ATRA demonstrated only modest effects, and rapamycin treatment of recipients with wild-type (WT) MSCs and ATRA failed to show any effect. However, transfer of p70S6k1 over-expressing-MSCs together with ATRA resulted in further improvements over those seen following WT MSCs together with ATRA. ATRA activated p70S6k1 in MSCs in vitro, which was completely inhibited by rapamycin. Tracking of transferred MSCs following ATRA revealed enhanced accumulation and extended survival of MSCs in recipient lungs following PPE but not vehicle instillation. These data suggest that in MSCs, p70S6k1 activation plays a critical role in ATRA-enhanced lung tissue repair, mediated in part by prolonged survival of transferred MSCs. p70S6k1-activated MSCs may represent a novel therapeutic approach to reverse the lung damage seen in emphysema. Stem Cells Translational Medicine 2018;7:551-558., (© 2018 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.)

Respiratory syncytial virus (RSV) is associated with enhanced progression of chronic obstructive pulmonary disease (COPD) and COPD exacerbations. However, little is known about the role of IL-17 in RSV-induced lung injury. We first investigated the role of RSV infection in enhancing mucous cell hyperplasia (MCH) and airspace enlargement in the lungs of mice injured with elastase and LPS (E/LPS). Mice injured with E/LPS had an enhanced and prolonged neutrophilic response to RSV that was associated with decreased levels of type I IFN and increased levels of IL-17, IL-23, CXCL-1, granulocyte colony stimulating factor (GCSF), CXCL-5, and matrix metalloproteinase (MMP)-9. In addition, extent of MCH and mean weighted alveolar space were increased significantly in the lungs of E/LPS-injured mice infected with RSV compared with E/LPS-only or RSV-only controls. Interestingly, immunodepletion of IL-17 before viral infection diminished the RSV-driven MCH and airspace enlargement in the E/LPS-injured animals, suggesting that IL-17 may be a therapeutic target for MCH and airspace enlargement when enhanced by RSV infection.

Emphysema results in a proteinase - antiproteinase imbalance, inflammation and oxidative stress. Our objective was to investigate whether atorvastatin could repair mouse lungs after elastase-induced emphysema. Vehicle (50 μL) or porcine pancreatic elastase (PPE) was administered on day 1, 3, 5 and 7 at 0.6 U intranasally. Male mice were divided into a control group (sham), PPE 32d (sacrificed 24 h after 32 days), PPE 64d (sacrificed 24 h after 64 days), and atorvastatin 1, 5 and 20 mg treated from day 33 until day 64 and sacrificed 24 h later (A1 mg, A5 mg and A20 mg, respectively). Treatment with atorvastatin was performed via inhalation for 10 min once a day. We observed that emphysema at day 32 was similar to emphysema at day 64. The mean airspace chord length (Lm) indicated a recovery of pulmonary morphology in groups A5 mg and A20 mg, as well as recovery of collagen and elastic fibers in comparison to the PPE group. Bronchoalveolar lavage fluid (BALF) leukocytes were reduced in all atorvastatin-treated groups. However, tissue macrophages were reduced only in the A20 mg group compared with the PPE group, while tissue neutrophils were reduced in the A5 mg and A20 mg groups. The redox balance was restored mainly in the A20 mg group compared with the PPE group. Finally, atorvastatin at doses of 5 and 20 mg reduced nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and matrix metalloproteinase-12 (MMP-12) compared with the PPE group. In conclusion, atorvastatin was able to induce lung tissue repair in emphysematous mice., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Aims: Inflammation plays a crucial role in aneurysm wall remodeling, which could lead to the rupture of intracranial aneurysms. Stromal cell-derived factor 1α (SDF-1α), a vital inflammation cytokine, is also related to aneurysm pathogenesis. However, the characteristics of SDF-1α expression and its role in aneurysm remodeling remain largely unknown. In this study, we aimed to investigate the expression dynamics of SDF-1α and its correlation with aneurysm remodeling., Methods: Saccular aneurysms were induced by porcine pancreatic elastase in New Zealand White rabbits. Aneurysm size was measured by digital subtraction angiography. Endothelial-like cells on the aneurysm wall were assessed on postoperative days 1, 3, 7, 14, 21, and 30. SDF-1α levels in the aneurysmal wall and serum were examined at several follow-up time points. Adherent molecule expression was examined, and migration assays were performed in vitro. After SDF-1α stimulation, the mobilization of endothelial-lineage cells and its role in the reendothelialization of the aneurysm wall were investigated in a saccular aneurysm rabbit model., Results: After the creation of saccular aneurysms in rabbits, the aneurysm sacs were filled with acute thrombosis within 3days, followed by a significant enlargement on day 14 and maturation on day 21. Serum SDF-1α levels increased in a bimodal fashion on day 1 and day 14, whereas SDF-1α expression in the aneurysm wall reached its maximum on day 14. VE-cadherin was up-regulated after SDF-1α stimulation and down-regulated by the SDF-1α ligand blocker AMD3100. Endothelial progenitor cell migration was enhanced by SDF-1α and blocked by AMD3100. The in vivo administration of SDF-α to rabbits with saccular aneurysms promoted endothelial-lineage cell mobilization into the peripheral blood and reendothelialization of the aneurysm wall., Conclusions: The SDF-1α expression level in the peripheral blood and local aneurysm wall correlated with the aneurysm remodeling process in rabbits with elastase-induced saccular aneurysms. We conclude that SDF-1α may facilitate aneurysm wall remodeling by up-regulating VE-cadherin expression and mobilizing endothelial-lineage cells., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background and Purpose: Rabbit elastase-induced saccular aneurysms have been commonly used for preclinical testing of endovascular devices, including flow diverters. However, all tested devices have been shown to be capable of aneurysm occlusion with this model. We aimed to create a more challenging model to test and discriminate among neurovascular devices of varying efficacies., Materials and Methods: With a surgical approach that included elastase infusion and balloon dilation, we attempted the creation of complex fusiform aneurysms in 16 rabbits, with standard saccular carotid aneurysms created in 15 other animals. Aneurysms were randomly allocated to one of the following treatments: flow diversion ( n = 8), high-porosity stent ( n = 6), double high-porosity stent ( n = 5), and control ( n = 6). Angiographic assessment and pathologic analyses were performed at 3 months., Results: Creation of complex fusiform and standard saccular aneurysms was successful in 12/16 and 13/15 attempts, respectively. All saccular ( n = 4) or complex fusiform ( n = 4) aneurysms treated with flow diverters were successfully occluded. Three of 3 saccular compared with 0/2 complex fusiform aneurysms were occluded by double high-porosity stents. One of 3 saccular and 0/3 complex fusiform aneurysms were occluded by a single high-porosity stent. Both aneurysm types shared the same pathologic findings when untreated: The aneurysm wall lacked an elastic layer and smooth muscle cells, while the lumen was lined with neointima of varying thickness. Neointimal coverage of the devices was complete when aneurysms were occluded, while leaks were always associated with aneurysm remnants., Conclusions: Challenging fusiform aneurysms can be created in rabbits by using a surgical modification of the elastase method., (© 2017 by American Journal of Neuroradiology.)

Background. Proteinases play a key role in emphysema. Bauhinia bauhinioides cruzipain inhibitor (BbCI) is a serine-cysteine proteinase inhibitor. We evaluated BbCI treatment in elastase-induced pulmonary alterations. Methods.  C57BL / 6 mice received intratracheal elastase (ELA group) or saline (SAL group). One group of mice was treated with BbCI (days 1, 15, and 21 after elastase instillation, ELABC group). Controls received saline and BbCI (SALBC group). After 28 days, we evaluated respiratory mechanics, exhaled nitric oxide, and bronchoalveolar lavage fluid. In lung tissue we measured airspace enlargement, quantified neutrophils, TNF α -, MMP-9-, MMP-12-, TIMP-1-, iNOS-, and eNOS-positive cells, 8-iso-PGF2 α , collagen, and elastic fibers in alveolar septa and airways. MUC-5-positive cells were quantified only in airways. Results. BbCI reduced elastase-induced changes in pulmonary mechanics, airspace enlargement and elastase-induced increases in total cells, and neutrophils in BALF. BbCI reduced macrophages and neutrophils positive cells in alveolar septa and neutrophils and TNF α -positive cells in airways. BbCI attenuated elastic and collagen fibers, MMP-9- and MMP-12-positive cells, and isoprostane and iNOS-positive cells in alveolar septa and airways. BbCI reduced MUC5ac-positive cells in airways. Conclusions. BbCI improved lung mechanics and reduced lung inflammation and airspace enlargement and increased oxidative stress levels induced by elastase. BbCI may have therapeutic potential in chronic obstructive pulmonary disease.

Bone-marrow derived mesenchymal stromal cells (MSCs) have potent immunomodulatory and tissue reparative properties, which may be beneficial in the treatment of inflammatory diseases such as COPD. This study examined the mechanisms by which human MSCs protect against elastase induced emphysema. Using a novel human relevant pre-clinical model of emphysema the efficacy of human MSC therapy and optimal cell dose were investigated. Protective effects were examined in the lung through histological examination. Further in vivo experiments examined the reparative abilities of MSCs after tissue damage was established and the role played by soluble factors secreted by MSCs. The mechanism of MSC action was determined in using shRNA gene knockdown. Human MSC therapy and MSC conditioned media exerted significant cytoprotective effects when administered early at the onset of the disease. These protective effects were due to significant anti-inflammatory, anti-fibrotic and anti-apoptotic mechanisms, mediated in part through MSC production of hepatocyte growth factor (HGF). When MSC administration was delayed, significant protection of the lung architecture was observed but this was less extensive. MSC cell therapy was more effective than MSC conditioned medium in this emphysema model.

Abdominal aortic aneurysm (AAA) is a major cause of morbidity and mortality; however, the mechanisms that are involved in disease initiation and progression are incompletely understood. Extracellular matrix proteins play an integral role in modulating vascular homeostasis in health and disease. Here, we determined that the expression of the matricellular protein CCN3 is strongly reduced in rodent AAA models, including angiotensin II-induced AAA and elastase perfusion-stimulated AAA. CCN3 levels were also reduced in human AAA biopsies compared with those in controls. In murine models of induced AAA, germline deletion of Ccn3 resulted in severe phenotypes characterized by elastin fragmentation, vessel dilation, vascular inflammation, dissection, heightened ROS generation, and smooth muscle cell loss. Conversely, overexpression of CCN3 mitigated both elastase- and angiotensin II-induced AAA formation in mice. BM transplantation experiments suggested that the AAA phenotype of CCN3-deficient mice is intrinsic to the vasculature, as AAA was not exacerbated in WT animals that received CCN3-deficient BM and WT BM did not reduce AAA severity in CCN3-deficient mice. Genetic and pharmacological approaches implicated the ERK1/2 pathway as a critical regulator of CCN3-dependent AAA development. Together, these results demonstrate that CCN3 is a nodal regulator in AAA biology and identify CCN3 as a potential therapeutic target for vascular disease.

Background and Purpose: Thin film nitinol can be processed to produce a thin microporous sheet with a low percentage of metal coverage (<20%) and high pore attenuation (∼70 pores/mm(2)) for flow diversion. We present in vivo results from the treatment of experimental rabbit aneurysms by using a thin film nitinol-based flow-diversion device., Materials and Methods: Nineteen aneurysms in the rabbit elastase aneurysm model were treated with a single thin film nitinol flow diverter. Devices were also placed over 17 lumbar arteries to model perianeurysmal branch arteries of the intracranial circulation. Angiography was performed at 2 weeks (n = 7), 1 month (n = 8), and 3 months (n = 4) immediately before sacrifice. Aneurysm occlusion was graded on a 3-point scale (grade I, complete occlusion; grade II, near-complete occlusion; grade III, incomplete occlusion). Toluidine blue staining was used for histologic evaluation. En face CD31 immunofluorescent staining was performed to quantify neck endothelialization., Results: Markedly reduced intra-aneurysmal flow was observed on angiography immediately after device placement in all aneurysms. Grade I or II occlusion was noted in 4 (57%) aneurysms at 2-week, in 6 (75%) aneurysms at 4-week, and in 3 (75%) aneurysms at 12-week follow-up. All 17 lumbar arteries were patent. CD31 staining showed that 75% ± 16% of the aneurysm neck region was endothelialized. Histopathology demonstrated incorporation of the thin film nitinol flow diverter into the vessel wall and no evidence of excessive neointimal hyperplasia., Conclusions: In this rabbit model, the thin film nitinol flow diverter achieved high rates of aneurysm occlusion and promoted tissue in-growth and aneurysm neck healing, even early after implantation., (© 2016 by American Journal of Neuroradiology.)

Emphysema, one of the major components of chronic obstructive pulmonary disease (COPD), is characterized by the progressive and irreversible loss of alveolar lung tissue. Even though >80% of COPD cases are associated with cigarette smoking, only a relatively small proportion of smokers develop emphysema, suggesting a potential role for genetic factors in determining individual susceptibility to emphysema. Although strain-dependent effects have been shown in animal models of emphysema, the molecular basis underlying this intrinsic susceptibility is not fully understood. In this present study, we investigated emphysema development using the elastase-induced experimental emphysema model in two commonly used mouse strains, C57BL/6J and BALB/cJ. The results demonstrate that mice with different genetic backgrounds show disparate susceptibility to the development of emphysema. BALB/cJ mice were found to be much more sensitive than C57BL/6J to elastase injury in both a dose-dependent and time-dependent manner, as measured by significantly higher mortality, greater body weight loss, greater decline in lung function, and a greater loss of alveolar tissue. The more susceptible BALB/cJ strain also showed the persistence of inflammatory cells in the lung, especially macrophages and lymphocytes. A comparative gene expression analysis following elastase-induced injury showed BALB/cJ mice had elevated levels of il17A mRNA and a number of classically (M1) and alternatively (M2) activated macrophage genes, whereas the C57BL/6J mice demonstrated augmented levels of interferon-γ. These findings suggest a possible role for these cellular and molecular mediators in modulating the severity of emphysema and highlight the possibility that they might contribute to the heterogeneity observed in clinical emphysema outcomes., (Copyright © 2015 the American Physiological Society.)

Rationale: Histological examination of abdominal aortic aneurysm (AAA) tissues demonstrates extracellular matrix destruction and infiltration of inflammatory cells. Previous work with mouse models of AAA has shown that anti-inflammatory strategies can effectively attenuate aneurysm formation. Thrombospondin-1 is a matricellular protein involved in the maintenance of vascular structure and homeostasis through the regulation of biological functions, such as cell proliferation, apoptosis, and adhesion. Expression levels of thrombospondin-1 correlate with vascular disease conditions., Objective: To use thrombospondin-1-deficient (Thbs1(-/-)) mice to test the hypothesis that thrombospondin-1 contributes to pathogenesis of AAAs., Methods and Results: Mouse experimental AAA was induced through perivascular treatment with calcium phosphate, intraluminal perfusion with porcine elastase, or systemic administration of angiotensin II. Induction of AAA increased thrombospondin-1 expression in aortas of C57BL/6 or apoE-/- mice. Compared with Thbs1(+/+) mice, Thbs1(-/-) mice developed significantly smaller aortic expansion when subjected to AAA inductions, which was associated with diminished infiltration of macrophages. Thbs1(-/-) monocytic cells had reduced adhesion and migratory capacity in vitro compared with wild-type counterparts. Adoptive transfer of Thbs1(+/+) monocytic cells or bone marrow reconstitution rescued aneurysm development in Thbs1(-/-) mice., Conclusions: Thrombospondin-1 expression plays a significant role in regulation of migration and adhesion of mononuclear cells, contributing to vascular inflammation during AAA development., (© 2015 American Heart Association, Inc.)

Vascular inflammation plays a critical role in the pathogenesis of cerebral aneurysms. Peroxisome proliferator-activated receptor γ (PPARγ) protects against vascular inflammation and atherosclerosis, whereas dominant-negative mutations in PPARγ promote atherosclerosis and vascular dysfunction. We tested the role of PPARγ in aneurysm formation and rupture. Aneurysms were induced with a combination of systemic infusion of angiotensin-II and local injection of elastase in (1) mice that received the PPARγ antagonist GW9662 or the PPARγ agonist pioglitazone, (2) mice carrying dominant-negative PPARγ mutations in endothelial or smooth muscle cells, and (3) mice that received the Cullin inhibitor MLN4924. Incidence of aneurysm formation, rupture, and mortality was quantified. Cerebral arteries were analyzed for expression of Cullin3, Kelch-like ECH-associated protein 1, nuclear factor (erythroid-derived 2)-like 2, NAD(P)H dehydrogenase (quinone)1 (NQO1), and inflammatory marker mRNAs. Neither pioglitazone nor GW9662 altered the incidence of aneurysm formation. GW9662 significantly increased the incidence of aneurysm rupture, whereas pioglitazone tended to decrease the incidence of rupture. Dominant-negative endothelial-specific PPARγ did not alter the incidence of aneurysm formation or rupture. In contrast, dominant-negative smooth muscle-specific PPARγ resulted in an increase in aneurysm formation (P<0.05) and rupture (P=0.05). Dominant-negative smooth muscle-specific PPARγ, but not dominant-negative endothelial-specific PPARγ, resulted in significant decreases in expression of genes encoding Cullin3, Kelch-like ECH-associated protein 1, and nuclear factor (erythroid-derived 2)-like 2, along with significant increases in tumor necrosis factor-α, monocyte chemoattractant protein-1, chemokine (C-X-C motif) ligand 1, CD68, matrix metalloproteinase-3, -9, and -13. MLN4924 did not alter incidence of aneurysm formation, but increased the incidence of rupture (P<0.05). In summary, endogenous PPARγ, specifically smooth muscle PPARγ, plays an important role in protecting from formation and rupture of experimental cerebral aneurysms in mice., (© 2015 American Heart Association, Inc.)

Background: Pulmonary emphysema is characterized by irreversible airflow obstruction, inflammation, oxidative stress imbalance and lung remodeling, resulting in reduced lung function and a lower quality of life. Flavonoids are plant compounds with potential anti-inflammatory and antioxidant effects that have been used in folk medicine. Our aim was to determine whether treatment with sakuranetin, a flavonoid extracted from the aerial parts of Baccharis retusa, interferes with the development of lung emphysema., Methods: Intranasal saline or elastase was administered to mice; the animals were then treated with sakuranetin or vehicle 2 h later and again on days 7, 14 and 28. We evaluated lung function and the inflammatory profile in bronchoalveolar lavage fluid (BALF). The lungs were removed to evaluate alveolar enlargement, extracellular matrix fibers and the expression of MMP-9, MMP-12, TIMP-1, 8-iso-PGF-2α and p65-NF-κB in the fixed tissues as well as to evaluate cytokine levels and p65-NF-κB protein expression., Results: In the elastase-treated animals, sakuranetin treatment reduced the alveolar enlargement, collagen and elastic fiber deposition and the number of MMP-9- and MMP-12-positive cells but increased TIMP-1 expression. In addition, sakuranetin treatment decreased the inflammation and the levels of TNF-α, IL-1β and M-CSF in the BALF as well as the levels of NF-κB and 8-iso-PGF-2α in the lungs of the elastase-treated animals. However, this treatment did not affect the changes in lung function., Conclusion: These data emphasize the importance of oxidative stress and metalloproteinase imbalance in the development of emphysema and suggest that sakuranetin is a potent candidate that should be further investigated as an emphysema treatment. This compound may be useful for counteracting lung remodeling and oxidative stress and thus attenuating the development of emphysema.

Background: Systemic inflammation is present in chronic obstructive pulmonary disease (COPD). A whey peptide-based enteral diet reduce inflammation in patients with COPD, but its effect on COPD development has not been determined. On the other hand, it is known that short chain fatty acids (SCFAs), which are produced by micro-flora in the gut, attenuates bronchial asthma in mice model., Methods: Mice with elastase-induced emphysema were fed with 1 of 3 diets (control diet, whey peptide-based enteral diet, or standard enteral diet) to determine the effects of whey peptide-based enteral diet on emphysema and on cecal SCFAs., Results: The whey peptide-based enteral diet group exhibited fewer emphysematous changes; significantly lower total cell counts in bronchoalveolar lavage fluid (BALF); and significantly higher cecal SCFA levels than either the control or standard enteral diet groups. The total cell count was inversely correlated with total cecal SCFA levels in these three diet groups., Conclusions: The whey peptide-based enteral diet attenuates elastase-induced emphysema through the suppression of inflammation in the lung. This may be related to the increase in cecal SCFA.

Background and Purpose: Cerebral aneurysm (CA) affects 3% of the population and is associated with hemodynamic stress and inflammation. Myeloperoxidase, a major oxidative enzyme associated with inflammation, is increased in patients with CA, but whether myeloperoxidase contributes to CA is not known. We tested the hypotheses that myeloperoxidase is increased within human CA and is critical for formation and rupture of CA in mice., Methods: Blood was drawn from the lumen of CAs and femoral arteries of 25 patients who underwent endovascular coiling of CA, and plasma myeloperoxidase concentrations were measured with ELISA. Effects of endogenous myeloperoxidase on CA formation and rupture were studied in myeloperoxidase knockout mice and wild-type (WT) mice using an angiotensin II-elastase induction model of CA. In addition, effects of myeloperoxidase on inflammatory gene expression in endothelial cells were analyzed., Results: Plasma concentrations of myeloperoxidase were 2.7-fold higher within CA than in femoral arterial blood in patients with CA. myeloperoxidase-positive cells were increased in aneurysm tissue compared with superficial temporal artery of patients with CA. Incidence of aneurysms and subarachnoid hemorrhage was significantly lower in myeloperoxidase knockout than in WT mice. In cerebral arteries, proinflammatory molecules, including tumor necrosis factor-α, cyclooxygenase-2 (COX2), chemokine (C-X-C motif) ligand 1 (CXCL1), chemokine (C motif) ligand (XCL1), matrix metalloproteinase (MMP) 8, cluster of differentiation 68 (CD68), and matrix metalloproteinase 13, and leukocytes were increased, and α-smooth muscle actin was decreased, in WT but not in myeloperoxidase knockout mice after induction of CA. Myeloperoxidase per se increased expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in endothelial cells., Conclusions: These findings suggest that myeloperoxidase may contribute importantly to formation and rupture of CA., (© 2015 American Heart Association, Inc.)

Background: Stiffening of the aortic wall is a phenomenon consistently observed in age and in abdominal aortic aneurysm (AAA). However, its role in AAA pathophysiology is largely undefined., Methods and Results: Using an established murine elastase-induced AAA model, we demonstrate that segmental aortic stiffening precedes aneurysm growth. Finite-element analysis reveals that early stiffening of the aneurysm-prone aortic segment leads to axial (longitudinal) wall stress generated by cyclic (systolic) tethering of adjacent, more compliant wall segments. Interventional stiffening of AAA-adjacent aortic segments (via external application of surgical adhesive) significantly reduces aneurysm growth. These changes correlate with the reduced segmental stiffness of the AAA-prone aorta (attributable to equalized stiffness in adjacent segments), reduced axial wall stress, decreased production of reactive oxygen species, attenuated elastin breakdown, and decreased expression of inflammatory cytokines and macrophage infiltration, and attenuated apoptosis within the aortic wall, as well. Cyclic pressurization of segmentally stiffened aortic segments ex vivo increases the expression of genes related to inflammation and extracellular matrix remodeling. Finally, human ultrasound studies reveal that aging, a significant AAA risk factor, is accompanied by segmental infrarenal aortic stiffening., Conclusions: The present study introduces the novel concept of segmental aortic stiffening as an early pathomechanism generating aortic wall stress and triggering aneurysmal growth, thereby delineating potential underlying molecular mechanisms and therapeutic targets. In addition, monitoring segmental aortic stiffening may aid the identification of patients at risk for AAA., (© 2015 American Heart Association, Inc.)

Background: Thoracic aortic aneurysms (TAAs) are common, but experimental TAA models are limited and the role of interleukin-1β (IL-1β) is undetermined., Methods and Results: IL-1β protein was measured in human TAAs and control aortas, and IL-1β protein was increased ≈20-fold in human TAAs. To develop an experimental model of TAAs, 8- to 10-week-old male C57Bl/6 mice (wild type [WT]) underwent thoracotomy with application of periadventitial elastase (WT TAA) or saline (WT control; n=30 per group). Elastase treatment to thoracic aortas resulted in progressive dilation until day 14 with maximal dilation of 99.6±24.7% compared with 14.4±8.2% for WT saline control (P<0.0001). WT TAAs demonstrated elastin fragmentation, smooth muscle cell loss, macrophage infiltration, and increased IL-1β expression. Next, TAAs were induced in mice deficient of IL-1β (IL-1β knockout) or IL-1 receptor (IL-1R knockout; n=10 each). Genetic deletion of IL-1β and IL-1R significantly decreased thoracic aortic dilation (IL-1β knockout=54.2±16.8% and IL-1R knockout=62.6±17.2% versus WT TAA=104.7±23.8%; P<0.001for both). IL-1β knockout and IL-1R knockout aortas demonstrated preserved elastin and smooth muscle cells with fewer inflammatory cells. Correspondingly, IL-1β and IL-1R knockout aortas had decreased inflammatory cytokine and matrix metalloproteinase 9 expression. Separately, WT mice pretreated with either IL-1R antagonist anakinra (100 mg/kg per day) or vehicle alone (control) underwent elastase treatment. Pretreatment of WT mice with anakinra attenuated TAA formation (control: 99.2±15.5% versus anakinra: 68.3±19.2%; P<0.005). Finally, to investigate treatment of small TAAs, WT mice were treated with anakinra 3 days after TAA induction. Anakinra treatment in WT mice with small TAAs reduced aortic dilation on day 14 (control treatment: 89.1±18.6% versus anakinra treatment: 59.7±25.7%; P=0.01)., Conclusions: Periadventitial application of elastase to murine thoracic aortas reproducibly produced aneurysms with molecular and histological features consistent with TAA disease. Genetic and pharmacological inhibition of IL-1β decreased TAA formation and progression, indicating that IL-1β may be a potential target for TAA treatment., (© 2014 American Heart Association, Inc.)

Background: Abdominal aortic aneurysm (AAA) involves leukocyte recruitment, inflammatory cytokine production, vascular cell apoptosis, neovascularization, and vascular remodeling, all of which contribute to aortic dilatation. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) is a cytokine implicated in proinflammatory responses, angiogenesis, and matrix degradation but its role in AAA formation is currently unknown., Methods and Results: Experimental AAA with aortic elastase perfusion in mice was induced in wild-type (WT), TWEAK deficient (TWEAK KO), or Fn14-deficient (Fn14 KO) mice. TWEAK or Fn14 KO deficiency reduced aortic expansion, lesion macrophages, CD3(+) T cells, neutrophils, CD31(+) microvessels, CCL2 and CCL5 chemokines expression, and MMP activity after 14 days postperfusion. TWEAK and Fn14 KO mice also showed a reduced loss of medial vascular smooth muscle cells (VSMC) that was related to a reduced number of apoptotic cells in these animals compared with WT mice. Aortas from WT animals present a higher disruption of the elastic layer and MMP activity than those from TWEAK or Fn14 KO mice, indicating a diminished vascular remodeling in KO animals. In vitro experiments unveiled that TWEAK induces CCL5 secretion and MMP-9 activation in both VSMC and bone marrow-derived macrophages, and decrease VSMC viability, effects dependent on Fn14., Conclusions: TWEAK/Fn14 axis participates in AAA formation by promoting lesion inflammatory cell accumulation, angiogenesis, matrix-degrading protease expression, and vascular remodeling. Blocking TWEAK/Fn14 interaction could be a new target for the treatment of AAA., (© 2014 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.)

Chronic obstructive pulmonary disease (COPD), manifested as emphysema and chronic airway obstruction, can be exacerbated by bacterial and viral infections. Although the frequency of exacerbations increases as the disease progresses, the mechanisms underlying this phenomenon are largely unknown, and there is a need for a simple in vivo exacerbation model. In this study, we compared four groups of mice treated with PBS alone, elastase alone, LPS alone, and elastase plus LPS. A single intratracheal administration of LPS to mice with elastase-induced emphysema provoked infiltration of inflammatory cells, especially CD8(+) T cells, into alveolar spaces and increased matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, and perforin production in bronchoalveolar lavage fluid at the acute inflammatory phase compared with the other groups. We also measured the percentage of low-attenuation area (LAA%) in the above mice using micro-computed X-ray tomography. The LAA% was the most sensitive parameter for quantitative assessments of emphysema among all the parameters evaluated. Using the parameter of LAA%, we found significantly more severe alveolar destruction in the group treated with elastase plus LPS compared with the other groups during long-term longitudinal observations. We built three-dimensional images of the emphysema and confirmed that the lungs of elastase plus LPS-treated mice contained larger emphysematous areas than mice treated with elastase alone. Although human exacerbation of COPD is clinically and pathologically complicated, this simple mouse model mimics human cases to some extent and will be useful for elucidating its mechanism and developing therapeutic strategies.

Aims: Endothelial progenitor cells (EPCs) are involved in vascular repair and homeostasis after vascular injuries. In this study, we aimed to explore whether bone marrow (BM)-derived EPCs contribute to neointima formation and reendothelialization in rabbit elastase-induced aneurysm after flow diverter treatment., Methods: Elastase-induced aneurysms were created in New Zealand male rabbits. Three weeks after model creation, flow diverter was implanted to cover the induced aneurysm neck. Autologous EPCs were isolated from bone marrow, expanded ex vivo, double labeled with Hoechst 33,342 and CFSE(carboxyfluorescein diacetate succinimidyl ester), and transplanted transvenously into the rabbits. The rabbits were assigned into three groups. The first group received autologous transfusion of double-labeled EPCs from the first day after stent implantation, and the second group received transfusion from the fifteenth day. The autologous transfusion was given at a 3-day interval and continued for 2 weeks. Fluorescence-labeled cells were tracked under fluorescence microscope at the aneurysm neck and parent artery in the two groups. The third group was established as control group without EPCs transplantation. Scanning electron microscope was used to investigate the reendothelialization rate between the former two groups and the control group., Results: In the first group, double-positive EPCs were found in 3/5 rabbits and mainly located in the subendothelial space and around the stent struts. In the second group, double-positive EPCs were found in 2/5 rabbits and mainly located on the surface of neointima. More endothelial-like cells were observed on the neointima of aneurysm neck and stented parent artery in the groups with EPCs transplantation than control group without EPCs transplantation, but the difference on the number of these cells did not reach statistical significance., Conclusions: BM-derived EPCs participate in neointima formation and reendothelialization in elastase-induced aneurysm after flow diverter treatment. The EPCs may differentiate into different cell types according to the stages of neointima formation in vivo., (© 2013 Blackwell Publishing Ltd.)

Endoluminal infusion and incubation of elastase with or without collagenase into the rabbit common carotid artery is an established model of arterial saccular aneurysm. The model mimics naturally occurring human cerebral aneurysms in many ways, including histologic and morphologic characteristics, hemodynamic pressures, and shear stresses. However, complications have been associated with the model. Here, we report 2 complications: 1) the first known case of iatrogenic laryngeal hemiplegia in a rabbit; and 2) histopathologically confirmed iatrogenic hippocampal and cerebellar infarcts (stroke). Finally, we present and review data from current literature on the morbidity and mortality associated with this model.

Background: Abdominal aortic aneurysm (AAA) formation is characterized by inflammation, smooth muscle activation and matrix degradation. This study tests the hypothesis that CD4+ T-cell-produced IL-17 modulates inflammation and smooth muscle cell activation, leading to the pathogenesis of AAA and that human mesenchymal stem cell (MSC) treatment can attenuate IL-17 production and AAA formation., Methods and Results: Human aortic tissue demonstrated a significant increase in IL-17 and IL-23 expression in AAA patients compared with control subjects as analyzed by RT-PCR and ELISA. AAA formation was assessed in C57BL/6 (wild-type; WT), IL-23(-/-) or IL-17(-/-) mice using an elastase-perfusion model. Heat-inactivated elastase was used as control. On days 3, 7, and 14 after perfusion, abdominal aorta diameter was measured by video micrometry, and aortic tissue was analyzed for cytokines, cell counts, and IL-17-producing CD4+ T cells. Aortic diameter and cytokine production (MCP-1, RANTES, KC, TNF-α, MIP-1α, and IFN-γ) was significantly attenuated in elastase-perfused IL-17(-/-) and IL-23(-/-) mice compared with WT mice on day 14. Cellular infiltration (especially IL-17-producing CD4+ T cells) was significantly attenuated in elastase-perfused IL-17(-/-) mice compared with WT mice on day 14. Primary aortic smooth muscle cells were significantly activated by elastase or IL-17 treatment. Furthermore, MSC treatment significantly attenuated AAA formation and IL-17 production in elastase-perfused WT mice., Conclusions: These results demonstrate that CD4+ T-cell-produced IL-17 plays a critical role in promoting inflammation during AAA formation and that immunomodulation of IL-17 by MSCs can offer protection against AAA formation.

Changes in lung function and structure were studied using hyperpolarized (3)He MRI in an elastase-induced murine model of emphysema. The combined analysis of the apparent diffusion coefficient (ADC) and fractional ventilation (R) were used to distinguish emphysematous changes and also to develop a model for classifying sections of the lung into diseased and normal. Twelve healthy male BALB/c mice (26 ± 2 g) were randomized into healthy and elastase-induced mice and studied ∼8-11 wk after model induction. ADC and R were measured at a submillimeter planar resolution. Chord length (L(x)) data were analyzed from histology samples from the corresponding imaged slices. Logistic regression was applied to estimate the probability that an imaged pixel came from a diseased animal, and bootstrap methods (1,000 samples) were used to compare the regression results for the morphological and imaging results. Multivariate ANOVA (MANOVA) was used to analyze transformed ADC (ADC(BC)), and R (R(BC)) data and also to control for the experiment-wide error rate. MANOVA and ANOVA showed that elastase induced a statistically measureable change in the average transformed L(x) and ADC(BC) but not in the average R(BC). Marginal mean analysis demonstrated that ADC(BC) was on average 0.19 [95% confidence interval (CI): 0.16, 0.22] higher in the emphysema group, whereas R(BC) was on average 0.05 (95% CI: 0.04, 0.06) lower. Logistic regression supported the hypothesis that ADC(BC) and R(BC), together, were better at differentiating normal from diseased tissue than either measurement alone. The odds ratios for ADC(BC) and R(BC) were 7.73 (95% CI: 5.23, 11.42) and 9.14 × 10(-5) (95% CI: 3.33 × 10(-5), 25.06 × 10(-5)), respectively. Using a 50% probability cutoff, this model classified 70.6% of pixels correctly. The sensitivity and specificity of this model at the 50% cutoff were 74.9% and 65.2%, respectively. The area under the receiver operating characteristic curve was 0.76 (95% CI: 0.74, 0.78). The regression model presented can be used to map MRI data to disease probability maps. These probability maps present a future possibility of using both measurements in a more clinically feasible method of diagnosing this disease.

All-trans retinoic acid (ATRA) is controversially discussed in emphysema therapy. We re-evaluated ATRA in the elastase model and hypothesised that beneficial effects should be reflected by increased alveolar surface area, elastin expression and downregulation of inflammatory mediators and matrix metalloproteinases (MMPs). Emphysema was induced by porcine pancreatic elastase versus saline in Sprague-Dawley rats. On days 26-37, rats received daily intraperitoneal injections with ATRA (500 μg · kg(-1) body weight) versus olive oil. Lungs were removed at day 38. Rat alveolar epithelial L2 cells were incubated with/without elastase followed by ATRA- or vehicle-treatment, respectively. ATRA only partially ameliorated structural defects. Alveolar walls exhibited irregular architecture: increased arithmetic mean thickness, reduction in surface coverage by alveolar epithelial cells type II. ATRA only partially restored reduced soluble elastin. It tended to increase the ratio of ED1(+):ED2(+) macrophages. Bronchoalveolar lavage (BAL) cells exhibited a proinflammatory state and high expression of interleukin-1β, cytokine-induced neutrophil chemoattractant-1, tumour necrosis factor-α, nuclear factor-κB, MMP-2, MMP-9, MMP-12, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in emphysema, with ATRA exerting only few effects. MMP-7 was highly induced by ATRA in healthy but not in emphysematous lungs. ATRA reduced both MMP-2 and TIMP-1 activity in BAL fluid of emphysematous lungs. ATRA-therapy may bear the risk of unwanted side-effects on alveolar septal architecture in emphysematous lungs.

Nitric oxide (NO) in combination with superoxide produces peroxynitrites and induces protein nitration, which participates in a number of chronic degenerative diseases. NO is produced at high levels in the human emphysematous lung, but its role in this disease is unknown. The aim of this study was to determine whether the NO synthases contribute to the development of elastase-induced emphysema in mice. nNOS, iNOS, and eNOS were quantified and immunolocalized in the lung after a tracheal instillation of elastase in mice. To determine whether eNOS or iNOS had a role in the development of emphysema, mice bearing a germline deletion of the eNOS and iNOS genes and mice treated with a pharmacological iNOS inhibitor were exposed to elastase. Protein nitration was determined by immunofluorescence, protein oxidation was determined by ELISA. Inflammation and MMP activity were quantified by cell counts, RT-PCR and zymography in bronchoalveolar lavage fluid. Cell proliferation was determined by Ki67 immunostaining. Emphysema was quantified morphometrically. iNOS and eNOS were diffusely upregulated in the lung of elastase-treated mice and a 12-fold increase in the number of 3-nitrotyrosine-expressing cells was observed. Over 80% of these cells were alveolar type 2 cells. In elastase-instilled mice, iNOS inactivation reduced protein nitration and increased protein oxidation but had no effect on inflammation, MMP activity, cell proliferation or the subsequent development of emphysema. eNOS inactivation had no effect. In conclusion, in the elastase-injured lung, iNOS mediates protein nitration in alveolar type 2 cells and alleviates oxidative injury. Neither eNOS nor iNOS are required for the development of elastase-induced emphysema.

Background and Purpose: The size of elastase-induced aneurysms created in the usual way is relatively small. Our aim was to determine whether creation of a carotid-jugular AVF to induce remodeling of the RCCA results in larger elastase-induced aneurysms in rabbits., Materials and Methods: RCCA right-jugular AVFs were created in 6 New Zealand white rabbits (group 1), followed by elastase-induced aneurysm creation 4 weeks later. Follow-up DSA was performed to assess AVF patency and aneurysm sizes. Six other elastase-induced aneurysms created in the usual way were used as controls (group 2). The diameters of the RCCA and LCCA in group 1 and aneurysm sizes in both groups were measured from DSA images and compared by using the Student t test., Results: The patency of AVFs in group 1 was confirmed in all 6 (100%) cases. The mean RCCA diameter in group 1 was larger than that in the contralateral LCCA (3.6 ± 0.7 mm versus 2.0 ± 0.1 mm, range, 1.8-2.2 mm, P < .01). The mean aneurysm neck diameter, width, and height for group 1 was larger than those of group 2 (4.6 ± 0.9 mm versus 3.5 ± 0.7 mm, P < .05; 4.7 ± 1.1 mm versus 3.4 ± 0.5 mm, P < .05; 13.8 ± 3.2 mm versus 8.1 ± 1.3 mm, P < .05, respectively). Aneurysm volume for group 1 was significantly larger than that of group 2 (273 ± 172 mm³ versus 77 ± 32 mm³, P < .05)., Conclusions: Carotid-jugular AVFs result in RCCA remodeling that yields relatively larger elastase-induced aneurysms.

Background: Chronic obstructive pulmonary disease (COPD) is characterized by chronic bronchitis, emphysema and irreversible airflow limitation. These changes are thought to be due to oxidative stress and an imbalance of proteases and antiproteases. Quercetin, a plant flavonoid, is a potent antioxidant and anti-inflammatory agent. We hypothesized that quercetin reduces lung inflammation and improves lung function in elastase/lipopolysaccharide (LPS)-exposed mice which show typical features of COPD, including airways inflammation, goblet cell metaplasia, and emphysema., Methods: Mice treated with elastase and LPS once a week for 4 weeks were subsequently administered 0.5 mg of quercetin dihydrate or 50% propylene glycol (vehicle) by gavage for 10 days. Lungs were examined for elastance, oxidative stress, inflammation, and matrix metalloproteinase (MMP) activity. Effects of quercetin on MMP transcription and activity were examined in LPS-exposed murine macrophages., Results: Quercetin-treated, elastase/LPS-exposed mice showed improved elastic recoil and decreased alveolar chord length compared to vehicle-treated controls. Quercetin-treated mice showed decreased levels of thiobarbituric acid reactive substances, a measure of lipid peroxidation caused by oxidative stress. Quercetin also reduced lung inflammation, goblet cell metaplasia, and mRNA expression of pro-inflammatory cytokines and muc5AC. Quercetin treatment decreased the expression and activity of MMP9 and MMP12 in vivo and in vitro, while increasing expression of the histone deacetylase Sirt-1 and suppressing MMP promoter H4 acetylation. Finally, co-treatment with the Sirt-1 inhibitor sirtinol blocked the effects of quercetin on the lung phenotype., Conclusions: Quercetin prevents progression of emphysema in elastase/LPS-treated mice by reducing oxidative stress, lung inflammation and expression of MMP9 and MMP12.

Theories of emphysema traditionally revolved around proteolytic destruction of extracellular matrix. Models have recently been developed that show airspace enlargement with the induction of pulmonary cell apoptosis. The purpose of this study was to determine the mechanism by which a model of epithelial cell apoptosis caused airspace enlargement. Mice were treated with either intratracheal microcystin (MC) to induce apoptosis, intratracheal porcine pancreatic elastase (PPE), or their respective vehicles. Mice from all groups were inflated and morphometry was measured at various time points. Physiology measurements were performed for airway resistance, tissue elastance, and lung volumes. The groups were further analyzed by air-saline quasistatic measurements, surfactant staining, and surfactant functional studies. Mice treated with MC showed evidence of reversible airspace enlargement. In contrast, PPE-treated mice showed irreversible airspace enlargement. The airspace enlargement in MC-treated mice was associated with an increase in elastic recoil due to an increase in alveolar surface tension. PPE-treated mice showed a loss of lung elastic recoil and normal alveolar surface tension, a pattern more consistent with human emphysema. Airspace enlargement that occurs with the MC model of pulmonary epithelial cell apoptosis displays physiology distinct from human emphysema. Reversibility, restrictive physiology due to changes in surface tension, and alveolar enlargement associated with heterogeneous alveolar collapse are most consistent with a mild acute lung injury. Inflation near total lung capacity gives the appearance of enlarged alveoli as neighboring collapsed alveoli exert tethering forces.

Background: There is currently a vast amount of evidence in the literature suggesting that matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are involved in the pathogenesis of inflammatory airways diseases, such as asthma and COPD. Despite this, the majority of reports only focus on single MMPs, often only in one model system. This study aimed to investigate the profile of an extensive range of MMP/TIMP levels in three different pre-clinical models of airways disease. These models each have a different and very distinct inflammatory profile, each exhibiting inflammatory characteristics that are similar to that observed in asthma or COPD. Since these models have their own characteristic pathophysiological phenotype, one would speculate that the MMP/TIMP expression profile would also be different., Methods: With the use of designed and purchased MMP/TIMP assays, investigation of rat MMP-2, 3, 714 and TIMP-14 mRNA expression was undertaken by Real Time PCR. The three rodent models of airways disease investigated were the endotoxin model, elastase model, and the antigen model., Results: Intriguingly, we demonstrated that despite the distinct inflammatory profile observed by each model, the MMP/TIMP expression profile is similar between the models, in that the same MMPs/TIMPs were observed to be generally increased or decreased in all three models. It could therefore be speculated that in a particular disease, it may be a complex network of MMPs, rather than an individual MMP, together with inflammatory cytokines and other mediators, that results in the distinct phenotype of inflammatory diseases, such as asthma and COPD., Conclusion: We believe our data may provide key information necessary to understand the role of various MMPs/TIMPs in different inflammatory airway diseases, and aid the development of more selective therapeutics without the side effect profile of current broad-spectrum MMP inhibitors.

Pulmonary emphysema is characterized by persistent inflammation and progressive alveolar destruction. The keratinocyte growth factor (KGF) favorably influences alveolar maintenance and repair and possesses anti-inflammatory properties. We aimed to determine whether exogenous KGF prevented or corrected elastase-induced pulmonary emphysema in vivo. Treatment with 5 mg x kg(-1) x day(-1) KGF before elastase instillation prevented pulmonary emphysema. This effect was associated with 1) a sharp reduction in bronchoalveolar lavage fluid total protein and inflammatory cell recruitment, 2) a reduction in the pulmonary expression of the chemokines CCL2 (or monocyte chemoattractant protein-1) and CXCL2 (or macrophage inflammatory protein-2alpha) and of the adhesion molecules ICAM-1 and VCAM-1, 3) a reduction in matrix metalloproteinase (MMP)-2 and MMP-9 activity at day 3, and 4) a major reduction in DNA damage detected by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) in alveolar cells at day 7. Treatment with KGF after elastase instillation had no effect on elastase-induced emphysema despite the conserved expression of the KGF receptor in the lungs of elastase-instilled animals as determined by immunohistochemistry. In vitro, KGF abolished the elastase-induced increase in CCL2, CXCL2, and ICAM-1 mRNA in the MLE-12 murine alveolar epithelial cell line. We conclude that KGF pretreatment protected against elastase-induced pulmonary inflammation, activation of MMPs, alveolar cell DNA damage, and subsequent emphysema in mice.

Endothelin (ET) receptor antagonists have been developed to produce a reduction of ET related effects in various diseases, as well as in animal models of airway inflammation. We aimed to investigate the anti-inflammatory potential of bosentan on a rat model of emphysema. Thirty Wistar male rats were classified as control group (group 1), intratracheally (i.t.) instilled with saline, treated with vehicle solution; elastase group (group 2), i.t. instilled with porcine pancreatic elastase (PPE), treated with vehicle solution; and PPE+bosentan group (group 3), i.t. instilled with PPE, treated with bosentan. The levels of TNF-alpha, IL-1beta, IL-6, and IL-8 in bronchoalveolar lavage fluid (BALF) and lung tissue, cell counts in BALF, and histologic analysis of all groups were evaluated. Neutrophile granulocytes (NG) and alveolar macrophages (AM) were increased more in group 2 than in group 1 (P<0.001, P=0.04, respectively). Compared with group 2, neutrophil granulocyte (NG) and alveolar macrophages (AM) counts were decreased in group 3 (P<0.001). Histological examination confirmed a diffuse neutrophilic inflammation and irregular alveolar air space enlargement in group 2. Treatment with bosentan partially reduced the enlarged lung volumes. Compared with group 1, the BALF levels of TNF-alpha and IL-6, and the lung tissue levels of IL-1beta, IL-6, and IL-8 were increased in group 2 (P=0.028, P=0.005, P=0.001, P=0.019, P<0.001, respectively). The TNF-alpha and IL-8 levels of BALF (P=0.007, P=0.001, respectively), and the TNF-alpha, IL-1beta, IL-6, and the IL-8 levels of lung tissue (P=0.031, P=0.017, P=0.007, P<0.001) were decreased in group 3 compared to group 2. In conclusion, bosentan decreased the inflammatory response by reducing numbers of inflammatory cells and proinflammatory cytokines.

Rationale: Oxidants are believed to play a major role in the development of emphysema., Objectives: This study aimed to determine if the expression of human copper-zinc superoxide dismutase (CuZnSOD) within the lungs of mice protects against the development of emphysema., Methods: Transgenic CuZnSOD and littermate mice were exposed to cigarette smoke (6 h/d, 5 d/wk, for 1 yr) and compared with nonexposed mice. A second group was treated with intratracheal elastase to induce emphysema., Measurements: Lung inflammation was measured by cell counts and myeloperoxidase levels. Oxidative damage was assessed by immunofluorescence for 3-nitrotyrosine and 8-hydroxydeoxyguanosine and lipid peroxidation levels. The development of emphysema was determined by measuring the mean linear intercept (Lm)., Main Results: Smoke exposure caused a fourfold increase in neutrophilic inflammation and doubled lung myeloperoxidase activity. This inflammatory response did not occur in the smoke-exposed CuZnSOD mice. Similarly, CuZnSOD expression prevented the 58% increase in lung lipid peroxidation products that occurred after smoke exposure. Most important, CuZnSOD prevented the onset of emphysema in both the smoke-induced model (Lm, 68 exposed control vs. 58 exposed transgenic; p < 0.04) and elastase-generated model (Lm, 80 exposed control vs. 63 exposed transgenic; p < 0.03). These results demonstrate for the first time that antioxidants can prevent smoke-induced inflammation and can counteract the proteolytic cascade that leads to emphysema formation in two separate animal models of the disease., Conclusions: These findings indicate that strategies aimed at enhancing or supplementing lung antioxidants could be effective for the prevention and treatment of this disease.

Objective: Abdominal aortic aneurysm (AAA) progression and disease resistance are related to mural cellularity; adventitial macrophages and neocapillaries predominate in larger, advanced aneurysms, whereas smaller AAAs have fewer macrophages and retain more medial smooth muscle cells (SMCs). Expression analysis of mRNA derived from the entire aorta may mask the role that specific cell types play in modulating disease progression. We used laser capture microdissection (LCM) to isolate SMC and macrophage-predominant mural cell populations for gene expression analysis in variable-flow AAA., Methods: Rat AAAs were created via porcine pancreatic elastase (PPE) infusion. Aortic flow was increased via femoral arteriovenous fistula creation (HF-AAA) or reduced via unilateral iliac ligation (LF-AAA) in selected cohorts. SMC and macrophage-predominant cell populations were isolated via LCM and analyzed for expression of pro-inflammatory transcription factors and chemokines, cytokines, and proteolytic enzymes via real-time polymerase chain reaction., Results: Aortic PPE infusion precipitated endothelial cell (EC) denudation, SMC apoptosis, and elastic lamellar degeneration. Increased aortic flow (HF > NF > LF) stimulated restorative EC and SMC proliferation (45.8 +/- 6.6 > 30.5 +/- 2.1 > 21 +/- 3.6 and 212.2 +/- 9.8 > 136.5 +/- 8.9 > 110 +/- 13.5, respectively, for both cell types; P < .05) at 5 days after PPE infusion, while simultaneously reducing medial SMC apoptosis and transmural macrophage infiltration. Expression of nuclear factor kappa B (NF-kappab), granulocyte macrophage-colony stimulating factor (GM-CSF), macrophage migration inhibitory (MIF), heparin-binding EGF-like factor (HB-EGF) and inducible nitric oxide synthase (iNOS) varied between cell types and flow conditions at all time points examined. Gelatinolytic protease expression varied by cell type in response to flow loading (eg, increased in SMCs, decreased in macrophages), consistent with observed patterns of elastolysis and SMC proliferation reported in prior experiments., Conclusions: Flow differentially regulates cell-specific AAA gene expression. Whole-organ analysis of AAA tissue lysates obscures important cellular responses to inflammation and flow, and may explain previous seemingly contradictory observations regarding proteolysis and cell proliferation. Cell-type specific expression and functional analyses may substantially clarify the pathophysiology of AAA disease., Clinical Relevance: Understanding aneurysmal aortic degeneration at the most fundamental level is a critical precursor to the development of next-generation therapies such as drug-eluting endografts and/or medical therapies to limit expansion of preclinical AAA in high-risk or elderly patients. Although animal modeling is necessary to gain insight into the early initiating events of AAA disease, the methods used in such analyses have critical bearing on the conclusions drawn regarding pathogenesis and potential therapeutic derivations. By analyzing cell-type-specific gene expression rather than whole-organ tissue lysates, the precise roles of important mediators such as metalloproteinases can be placed in the appropriate context. Further refinement of these techniques may allow cell-specific therapies to be applied at defined time points in disease progression with improved patient outcome and reduced procedural morbidity.

Background: Hepatocyte growth factor (HGF) is an important mitogen and morphogen that contributes to the repair process after lung injury. The goal of the present study was to characterize its role in pulmonary emphysema, which may lead to the development of new treatment strategies with HGF., Methods and Results: HGF mRNA and protein levels in lung tissue and plasma from elastase-induced emphysema rats transiently increased, then declined significantly to below the basal level in a time-dependent manner (P<0.01). Furthermore, changes in HGF were correlated with histologically progressive emphysematous changes and deterioration in pulmonary physiology. Use of the HVJ (hemagglutinating virus of Japan) envelope method resulted in successful transfection of cDNA encoding human HGF, as demonstrated by an efficient expression of HGF in alveolar endothelial and epithelial cells. Transfection of HGF resulted in a more extensive pulmonary vasculature and inhibition of alveolar wall cell apoptosis, and those effects led to improved exercise tolerance and gas exchange (P<0.05), which persisted for more than 1 month., Conclusions: Decreased HGF expression due to a failure in sustained endogenous production after injury was associated with emphysema-related histopathologic and physiological changes in the present rat model. In addition, induction of HGF expression by a gene-transfection method resulted in improved pulmonary function via inhibition of alveolar cell apoptosis, enhancement of alveolar regeneration, and promotion of angiogenesis.

Heme oxygenase 1 (HO-1) is an inducible enzyme that catalyzes heme to generate bilirubin, ferritin, and carbon monoxide. Because enhanced expression of HO-1 provides an anti-inflammatory effect and confers cytoprotection, we examined whether HO-1 overexpression induced by inoculation of mice with an adenovirus encoding HO-1 (Ad.HO-1) in the lung would prevent pulmonary emphysema induced by porcine pancreatic elastase (PPE). Pretreatment with Ad.HO-1, which upregulated production of HO-1 in the lung, attenuated the PPE-induced increase of neutrophils in bronchoalveolar lavage fluid (BALF) and enlargement of alveoli. It also reduced PPE-induced elevated levels of tumor necrosis factor alpha, interleukin (IL)-6, and keratinocyte-derived chemokine, and increased the level of anti-inflammatory cytokine IL-10 in BALF. These results suggest that Ad.HO-1-induced HO-1 overexpression suppressed PPE-induced emphysema by attenuating neutrophilic inflammation via modulating cytokine and chemokine profiles in mouse lungs.

Background: Previous work has shown that all-trans-retinoic acid reverses elastase induced emphysema in rats. Since there is currently no effective treatment for pulmonary emphysema, the effect of retinoic acid should be further investigated in other adult species. A study was undertaken using two murine models of emphysema to evaluate the effect of retinoic acid., Methods: The models used were an elastase induced emphysema model for acute alveolar destruction and a tumour necrosis factor (TNF)-alpha transgenic mouse which exhibits chronic air space enlargement, loss of elastic recoil, increased lung volume, and pulmonary hypertension comparable to human pulmonary emphysema. All-trans-retinoic acid (2 mg/kg) was injected for 12 successive days after the establishment of emphysema. The effects of treatment were evaluated using physiological and morphometric analyses., Results: In contrast to the rat, administration of all-trans-retinoic acid in these murine models did not improve the emphysema. Moreover, worsening of emphysema was observed in TNF-alpha transgenic mice treated with all-trans-retinoic acid. The level of keratinocyte chemoattractant (KC), a CXC chemokine, in bronchoalveolar lavage fluid was increased in TNF-alpha transgenic mice following retinoic acid treatment. These data raise the possibility that retinoic acid causes deterioration of emphysema by promoting inflammation in this model., Conclusions: In these models, retinoic acid did not show positive effects on emphysema. The effect of retinoic acid in the treatment of pulmonary emphysema remains controversial, and further studies are required to determine its physiological effects under a variety of experimental conditions.

Many mouse models of abdominal aortic aneurysms have been developed that use a diverse array of methods for producing the disease, including genetic manipulation and chemical induction. These models could provide insight into potential mechanisms in the development of this disease. Although experimental studies on abdominal aortic aneurysms (AAAs) have used a variety of mammalian and avian approaches, there is an increasing reliance on the use of mice. The models recapitulate some facets of the human disease including medial degeneration, inflammation, thrombus formation, and rupture. Most of the mouse models of AAA are evoked either by genetically defined approaches or by chemical means. The genetic approaches are spontaneous and engineered mutations. These include defects in extracellular matrix maturation, increased degradation of elastin and collagen, aberrant cholesterol homeostasis, and enhanced production of angiotensin peptides. The chemical approaches include the intraluminal infusion of elastase, periaortic incubations of calcium chloride, and subcutaneous infusion of AngII. A common feature of these models is the reduction of AAA incidence and severity by the prophylactic administration of matrix metalloproteinase (MMP) inhibitors or genetically engineered deficiencies of specific members of this proteolytic protein family. The validation of mouse models of AAAs will provide insight into the mechanisms of progression of the human disease.