Balloon neck-plasty to create a wide-necked aneurysm in the elastase-induced rabbit model.

PURPOSE: The elastase-induced aneurysm (EIA) model in rabbits has been proposed for translational research; however, the adjustment of aneurysm neck size remains challenging. In this study, the technical feasibility and safety of balloon neck-plasty to create a wide-necked aneurysm in rabbit EIA model were investigated. METHODS: Male New Zealand White rabbits (N = 15) were randomly assigned to three groups: group A, EIA creation without neck-plasty; group B, neck-plasty immediately after EIA creation; group C, neck-plasty 4 weeks after EIA creation. The diameter of balloon used for neck-plasty was determined 1 mm larger than origin carotid artery diameter. All rabbits were euthanized 4 weeks after their final surgery. Aneurysm neck, height, dome-to-neck (D/N) ratio, and histologic parameters were compared among the groups. RESULTS: Aneurysm creation was technically successful in 14 out of 15 rabbits (93.3%), with one rabbit experiencing mortality due to an adverse anesthetic event during the surgery. Saccular and wide-necked aneurysms were successfully created in all rabbits. Aneurysm neck was significantly greater in groups B and C compared to group A (all P < .05). D/N ratio was significantly lower in groups B and C compared to group A (all P < .05). Additionally, tunica media thickness, vessel area, and luminal area were significantly greater in groups B and C compared to group A (all P < .05). These variables were found to be significantly greater in group B compared to group C (all P < .05). CONCLUSION: The creation of a wide-necked aneurysm using balloon neck-plasty after elastase induction in rabbits has been determined to be technically feasible and safe.

Fibroblast growth factor 10 reverses cigarette smoke- and elastase-induced emphysema and pulmonary hypertension in mice.

BACKGROUND: COPD is an incurable disease and a leading cause of death worldwide. In mice, fibroblast growth factor (FGF)10 is essential for lung morphogenesis, and in humans, polymorphisms in the human FGF10 gene correlate with an increased susceptibility to develop COPD. METHODS: We analysed FGF10 signalling in human lung sections and isolated cells from healthy donor, smoker and COPD lungs. The development of emphysema and PH was investigated in Fgf10+/- and Fgfr2b+/- (FGF receptor 2b) mice upon chronic exposure to cigarette smoke. In addition, we overexpressed FGF10 in mice following elastase- or cigarette smoke-induced emphysema and pulmonary hypertension (PH). RESULTS: We found impaired FGF10 expression in human lung alveolar walls and in primary interstitial COPD lung fibroblasts. In contrast, FGF10 expression was increased in large pulmonary vessels in COPD lungs. Consequently, we identified impaired FGF10 signalling in alveolar walls as an integral part of the pathomechanism that leads to emphysema and PH development: mice with impaired FGF10 signalling (Fgf10+/- and Fgfr2b+/- ) spontaneously developed lung emphysema, PH and other typical pathomechanistic features that generally arise in response to cigarette smoke exposure. CONCLUSION: In a therapeutic approach, FGF10 overexpression successfully restored lung alveolar and vascular structure in mice with established cigarette smoke- and elastase-induced emphysema and PH. FGF10 treatment triggered an initial increase in the number of alveolar type 2 cells that gradually returned to the basal level when the FGF10-mediated repair process progressed. Therefore, the application of recombinant FGF10 or stimulation of the downstream signalling cascade might represent a novel therapeutic strategy in the future.

Development of a unilateral porcine emphysema model induced by porcine pancreatic elastase.

Emphysema is one of the pathological hallmarks of chronic obstructive pulmonary disease. We have recently reported that radiofrequency therapy improves lung function in rodent models of emphysema. However, preclinical data using large animals is necessary for clinical translation. Here, we describe the work performed to establish a unilateral porcine emphysema model. Different doses of porcine pancreatic elastase (PPE) were instilled into the left lung of 10 Yucatan pigs. Three additional pigs were used as controls. Six weeks after instillation, lungs were harvested. Lung compliance was measured by a water displacement method and plethysmography. Systematic uniform random sampling of the left and right lungs was performed independently to measure alveolar surface area using micro-computed tomography (micro-CT) and histology. In pigs instilled with 725-750 U/kg of PPE (PPE group, n = 6), the compliance of the left lung was significantly higher by 37.6% than that of the right lung (P = 0.03) using the water displacement method. With plethysmography, the volume of the left lung was significantly larger than that of the right lung at 3, 5, and 10 cmH2O. Measurements from either micro-CT or histology images showed a significant decrease in alveolar surface area by 14.2% or 14.5% (P = 0.031) in the left lung compared with the right lung of the PPE group. A unilateral model for mild emphysema in Yucatan pigs has been established, which can now be used for evaluating novel therapeutics and interventional strategies.NEW & NOTEWORTHY For clinical translation, preclinical data using large animal models is necessary. However, papers describing an emphysema model in pigs, which are anatomically and physiologically similar to humans, are lacking. Here, we report success in creating a unilateral mild-emphysema model in pigs with only one single dose of porcine pancreatic elastase. This model will be useful in bringing novel technologies and therapies from small animals to humans with emphysema.

Effects of elastase-induced emphysema on muscle and bone in mice.

Chronic obstructive pulmonary disease (COPD) causes sarcopenia and osteoporosis. However, the mechanisms underlying muscle and bone loss as well as the interactions between muscle and bone in the COPD state remain unclear. Therefore, we herein investigated the effects of the COPD state on muscle and bone in mice intratracheally administered porcine pancreatic elastase (PPE). The intratracheal administration of PPE to mice significantly reduced trabecular bone mineral density (BMD), trabecular bone volume, trabecular number, cortical BMD and cortical area. It also significantly decreased grip strength, but did not affect muscle mass or the expression of myogenic differentiation-, protein degradation- or autophagy-related genes in the soleus and gastrocnemius muscles. Among the myokines examined, myostatin mRNA levels in the soleus muscles were significantly elevated in mice treated with PPE, and negatively related to grip strength, but not bone parameters, in mice treated with or without 2 U PPE in simple regression analyses. Grip strength positively related to bone parameters in mice treated with or without PPE. In conclusion, we showed that a PPE model of COPD in mice exerts dominant effects on bone rather than skeletal muscles. Increased myostatin expression in the soleus muscles of mice in the COPD state may negatively relate to a reduction in grip strength, but not bone loss.

Intratracheally injected human-induced pluripotent stem cell-derived pneumocytes and endothelial cells engraft in the distal lung and ameliorate emphysema in a rat model.

OBJECTIVES: Pulmonary emphysema is characterized by the destruction of alveolar units and reduced gas exchange capacity. In the present study, we aimed to deliver induced pluripotent stem cell-derived endothelial cells and pneumocytes to repair and regenerate distal lung tissue in an elastase-induced emphysema model. METHODS: We induced emphysema in athymic rats via intratracheal injection of elastase as previously reported. At 21 and 35 days after elastase treatment, we suspended 80 million induced pluripotent stem cell-derived endothelial cells and 20 million induced pluripotent stem cell-derived pneumocytes in hydrogel and injected the mixture intratracheally. On day 49 after elastase treatment, we performed imaging, functional analysis, and collected lungs for histology. RESULTS: Using immunofluorescence detection of human-specific human leukocyte antigen 1, human-specific CD31, and anti--green fluorescent protein for the reporter labeled pneumocytes, we found that transplanted cells engrafted in 14.69% ± 0.95% of the host alveoli and fully integrated to form vascularized alveoli together with host cells. Transmission electron microscopy confirmed the incorporation of the transplanted human cells and the formation of a blood-air barrier. Human endothelial cells formed perfused vasculature. Computed tomography scans revealed improved vascular density and decelerated emphysema progression in cell-treated lungs. Proliferation of both human and rat cell was higher in cell-treated versus nontreated controls. Cell treatment reduced alveolar enlargement, improved dynamic compliance and residual volume, and improved diffusion capacity. CONCLUSIONS: Our findings suggest that human induced pluripotent stem cell-derived distal lung cells can engraft in emphysematous lungs and participate in the formation of functional distal lung units to ameliorate the progression of emphysema.

Mouse Abdominal Aortic Aneurysm Model Induced by Periarterial Incubation of Papain.

For decades, numerous experimental animal models have been developed to examine the pathophysiologic mechanisms and potential treatments for abdominal aortic aneurysms (AAAs) in diverse species with varying chemical or surgical approaches. This study aimed to create an AAA mouse model by the periarterial incubation with papain, which can mimic human AAA with advantages such as simplicity, convenience, and high efficiency. Eighty C57BL/6J male mice were randomly assigned to 1 of the 4 groups: papain (1.0 or 2.0 mg), porcine pancreatic elastase, and phosphate-buffered solution. The aortic segment was wrapped for 20 minutes, and the diameter was measured using ultrasound preoperatively and postoperative days 7 and 14. Then, the mice were killed for histomorphometric and immunohistochemical analyses. According to ultrasound measurements and histomorphometric analyses, on postoperative day 7, 65% of mice in the 1.0-mg papain group and 60% of mice in the 2.0-mg papain group developed AAA. In both papain groups, 100% of mice developed AAA, and 65% of mice in the porcine pancreatic elastase group developed AAA on postoperative day 14. Furthermore, hematoxylin/eosin, elastin van Gieson, and Masson staining of tissues from the papain group revealed thickened media and intimal hyperplasia, collagen sediments, and elastin destruction, indicating that AAA histochemical alteration was similar to that of humans. In addition, the immunohistochemical analysis was conducted to detect infiltrated inflammatory cells, such as macrophages and leukocytes, in the aortic wall and hyperplasic adventitia. The expression of matrix metalloproteinase 2 and 9 was significantly upregulated in papain and human AAA tissues. Periarterial incubation with 1.0 mg of papain for 20 minutes can successfully create an experimental AAA model in mice for 14 days, which can be used to explore the mechanism and treatment of human AAA.

A modified method of elastase-induced saccular aneurysm creation in rabbits: Schematic representation of the method.

BACKGROUND: The purpose of our study was to investigate the safety and effectiveness of a modified technique using a short guiding catheter for instillation of elastase in comparison with the previously described method of creating elastase-induced aneurysm in rabbits. METHODS: Following right common carotid artery (RCCA) access using an arterial sheath and inflating the Fogarty balloon in the subclavian artery, a short guiding catheter was used for the instillation of the elastase in the experimental group (n = 5) while it was performed with a microcatheter in the control group (n = 5). The procedure duration was recorded from the RCCA puncture to the sheath removal. The histological changes were characterized using H&E and Masson's trichrome (MT) staining. RESULTS: The procedure time was 23 ± 2 min in the experimental group and 29 ± 2 min in the control group. All the rabbits (100%) in the experimental group survived without neurologic deficits, but two rabbits (40%) survived in the control group. All aneurysms were created in the saccular shape (100%) with a neck size of 2.3 ± 0.29 mm, a width of 2.75 ± 0.36 mm, and height of 6.37 ± 0.46 mm, and a dome to neck ratio of 1.21 ± 0.23. The aneurysm walls were partly thickened due to the degradation of the media tunica and adventitia proliferation with loss of the internal elastic lamina. CONCLUSION: By using a short guiding catheter, we could instill the elastase in a more effective and safe manner in the creation of the elastase-induced aneurysm model in rabbits.

Peptide-siRNA nanoparticles targeting NF-κB p50 mitigate experimental abdominal aortic aneurysm progression and rupture.

Abdominal aortic aneurysm (AAA) is a progressive vascular condition associated with high risk of mortality if left untreated. AAA is an inflammatory process with excessive local production of extracellular matrix degrading enzymes, leading to dilatation and rupture of the abdominal aorta. We posit that targeting NF-κB, a signaling pathway that controls inflammation, will halt AAA progression and prevent rupture. In an elastase-induced AAA model we observed that NF-κB activation increased progressively post-elastase perfusion. Unexpectedly, we found that AAA progression was marked by predominant nuclear accumulation of the NF-κB p50 subunit at the exclusion of p65. Using the amphipathic peptide p5RHH to form nanocomplexes with siRNA, we sought to mitigate AAA progression by knocking down the expression of different NF-κB subunits. We found that the administration of NF-κB p65 siRNA was only beneficial when given early (day 3 post-elastase perfusion) while p50 siRNA was still effective in mitigating elastase-induced AAA even when delivery was delayed until day 5. Additionally, systemic delivery of p50 siRNA, but not p65 siRNA decreased the risk of aortic rupture and sudden death in the transforming growth factor-beta blockade model of AAA. In both murine models, knockdown of NF-κB was accompanied by a significant decrease in leukocyte infiltrates, inflammatory cytokine release, inducible nitric oxide synthase expression, and cell apoptosis. These results suggest that the NF-κB p50 and p65 subunits contribute differentially at different stages of disease and the timing of in vivo siRNA delivery was of critical importance. The results also provide a rationale for selective targeting of p50 for more specific therapeutic intervention in the medical treatment of small AAA.

Kunming mouse strain is less susceptible to elastase-induced abdominal aortic aneurysms.

BACKGROUND: Porcine pancreatic elastase (PPE) is successfully used to induce abdominal aortic aneurysm (AAA) in mice. However, differences between mouse strains in susceptibility to PPE induction have been reported. Kunming mouse is one of the most frequently used strains in China but whether it is suitable for induction of AAA by PPE application remains unclear. METHODS: PPE infusion (1.5 units/ml) in temporary controlled aorta was performed to induce AAAs in both C57BL/6J and Kunming mice. Phosphate-buffered saline (PBS) application was used as vehicle control. The aorta diameters of all mice were measured at days 0 and 14 after surgery to evaluate the AAA formation. RESULTS: After 14 days of PPE or PBS infusion, all mice were sacrificed and aorta tissues were collected for histological staining analysis. At the 14th day after infusion, PPE successfully induced aortic dilation in Kunming mice and typical AAA in C57BL/6J mice. The aorta diameter increased by 0.23 mm in Kunming mice after PPE infusion, while it was 0.72 mm in the C57BL/6J strain. PPE induced mild elastin degradation, smooth muscle cell (SMC) depletion and mural leucocyte infiltration in Kunming mice, but in PPE-sensitive C57BL/6J mice, it induced total loss of SMCs, elastin disappearance and diffused infiltrated leucocytes in aortic aneurysmal segments. The effects of PPE in inducing angiogenesis and upregulating matrix metalloproteinase 2 and 9 expression in Kunming mice were also weaker than that in C57BL/6J mice. CONCLUSION: At the reported dose of PPE, Kunming mouse is not as susceptible to AAA formation as C57BL/6J mice. The failure of PPE to induce AAA formation in Kunming mice may be associated to its inability to boost a strong inflammatory response.

Dapagliflozin Ameliorates the Formation and Progression of Experimental Abdominal Aortic Aneurysms by Reducing Aortic Inflammation in Mice.

BACKGROUND: Dapagliflozin, a sodium glucose transporter protein-2 (SGLT-2) inhibitor, reduces the risk for cardiovascular diseases. However, the influence of dapagliflozin on nondissecting abdominal aortic aneurysms (AAAs) remains unclear. METHODS: AAAs were created in male C57BL/6 mice via intra-aortic porcine pancreatic elastase (PPE) infusion. Mice were daily treated with dapagliflozin (1 or 5 mg/kg body weight) or an equal volume of vehicle through oral gavage beginning one day prior to PPE infusion for 14 days. To investigate its translational value, dapagliflozin or vehicle was also administered to mice with existing AAAs in another cohort. Aortic diameters were measured prior to (day 0 for baseline) and 14 days after PPE infusion. After sacrifice, mice aortae were collected, and following histological analyses were performed. RESULTS: Dapagliflozin treatment significantly reduced aneurysmal aortic expansion following PPE infusion as compared to vehicle treatment especially at 5 mg/kg body weight (approximately 21% and 33% decreases in 1 and 5 mg/kg treatment groups, respectively). The dose-dependent attenuation of AAAs by dapagliflozin was also confirmed on histological analyses. Dapagliflozin remarkably reduced aortic accumulation of macrophages, CD4+ T cells, and B cells particularly following dapagliflozin treatment at 5 mg/kg. Dapagliflozin treatment also markedly attenuated medial SMC loss. Though the difference was not significant, dapagliflozin treatment tended to attenuate CD8+ T cells and elastin degradation. Dapagliflozin treatment at 5 mg/kg caused a 53% reduction in neovessel density. Furthermore, dapagliflozin treatment mitigated further progress of existing AAAs. CONCLUSION: Dapagliflozin treatment ameliorated PPE-induced AAAs by inhibiting aortic leukocytes infiltration and angiogenesis.

Fusobacterium nucleatum exacerbates chronic obstructive pulmonary disease in elastase-induced emphysematous mice.

Exacerbation of chronic obstructive pulmonary disease (COPD) is associated with disease progression and increased mortality. Periodontal disease is a risk factor for exacerbation of COPD, but little is known about the role of periodontopathic bacteria in this process. Here, we investigated the effects of intratracheal administration of Fusobacterium nucleatum, a periodontopathic bacteria species, on COPD exacerbation in elastase-induced emphysematous mice. The administration of F. nucleatum to elastase-treated mice enhanced inflammatory responses, production of alveolar wall destruction factors, progression of emphysema, and recruitment of mucin, all of which are symptoms observed in patients with COPD exacerbation. Hence, we propose that F. nucleatum may play a role in exacerbation of COPD.

PATENCY-2 trial of vonapanitase to promote radiocephalic fistula use for hemodialysis and secondary patency.

OBJECTIVE: Arteriovenous fistulas created for hemodialysis often fail to become usable and are frequently abandoned. This prospective trial evaluated the efficacy of vonapanitase, a recombinant human elastase, in increasing radiocephalic fistula use for hemodialysis and secondary patency. METHODS: PATENCY-2 was a randomized, double-blind, placebo-controlled trial in patients on or approaching the need for hemodialysis undergoing radiocephalic arteriovenous fistula creation. Of 696 screened, 613 were randomized, and 603 were treated (vonapanitase n = 405, placebo n = 208). The study drug solution was applied topically to the artery and vein for 10 min immediately after fistula creation. The primary endpoints were fistula use for hemodialysis and secondary patency (fistula survival without abandonment). Other efficacy endpoints included unassisted fistula use for hemodialysis, primary unassisted patency, fistula maturation and unassisted maturation by ultrasound criteria, and fistula procedure rates. RESULTS: The proportions of patients with fistula use for hemodialysis was similar between groups, 70% vonapanitase and 65% placebo, (p = 0.33). The Kaplan-Meier estimates of 12-month secondary patency were 78% (95% confidence interval [CI], 73-82) for vonapanitase and 76% (95% CI, 70-82) for placebo (p = 0.93). The proportions with unassisted fistula use for hemodialysis were 46% vonapanitase and 37% placebo (p = 0.054). The Kaplan-Meier estimates of 12-month primary unassisted patency were 50% (95% CI, 44-55) for vonapanitase and 43% (95% CI, 35-50) for placebo (p = 0.18). There were no differences in the proportion of patients with fistula maturation or in fistula procedure rates. Adverse events were similar between groups. Vonapanitase was not immunogenic. CONCLUSIONS: Vonapanitase treatment did not achieve clinical or statistical significance to meaningfully improve radiocephalic fistula surgical outcomes. Outcome in the placebo group were better than in historical controls. Vonapanitase was well-tolerated and safe. TRIAL REGISTRATION: clinicaltrials.gov: NCT02414841 (https://clinicaltrials.gov/ct2/show/NCT02414841).

Progression and Regression of Abdominal Aortic Aneurysms in Mice.

OBJECTIVE: Abdominal aortic aneurysm (AAA) is a significant medical problem with a high mortality rate. Nevertheless, the underlying mechanism for the progression and regression of AAA is unknown. METHODS: Experimental model of AAA was first created by porcine pancreatic elastase incubation around the infrarenal aorta of C57BL/6 mice. Then, AAA progression and regression were evaluated based on the diameter and volume of AAA. The aortas were harvested for hematoxylin-eosin staining (HE), orcein staining, sirius red staining, immunofluorescence analysis and perls' prussian blue staining at the indicated time point. Finally, ß-aminopropionitrile monofumarate (BAPN) was used to explore the underlying mechanism of the regression of AAA. RESULTS: When we extended the observation period to 100 days, we not only observed an increase in the AAA diameter and volume in the early stage, but also a decrease in the late stage. Consistent with AAA diameter and volume, the aortic thickness showed the same tendency based on HE staining. The elastin and collagen content first degraded and then regenerated, which corresponds to the early deterioration and late regression of AAA. Then, endogenous up-regulation of lysyl oxidase (LOX) was detected, accompanying the regression of AAA, as detected by an immunofluorescent assay. BAPN and LOX inhibitor considerably inhibited the regression of AAA, paralleling the degradation of elastin lamella and collagen. CONCLUSION: Taken together, we tentatively conclude that endogenous re-generation of LOX played an influential role in the regression of AAA. Therefore, regulatory factors on the generation of LOX exhibit promising therapeutic potential against AAA.

Reversal of elastase-induced abdominal aortic aneurysm following the delivery of nanoparticle-based pentagalloyl glucose (PGG) is associated with reduced inflammatory and immune markers.

OBJECTIVE: An Abdominal aortic aneurysm (AAA), a deadly disease in elderly population, is featured by expansion of aortic diameter, degradation and weakening of vasculature. Its common and significant characteristics are disarray and inflammation in vasculature. We tested the hypothesis that the reversal of abdominal aortic aneurysm by pentagalloyl glucose-loaded nanoparticles (PGG-NPs) therapy that targets degraded elastin suppresses inflammatory and immune markers to ameliorate the pathophysiology of the disease in advance stage aneurysm in a porcine pancreatic elastase (PPE)-induced mouse model of AAA. METHODS AND RESULTS: After induction of aneurysm in pathogen-free C57BL/6 male mice by applying PPE peri-adventitially to the abdominal aorta, once a week for two doses of intravenous injections of pentagalloyl glucose-loaded nanoparticles (PGG-NPs) conjugated with elastin targeted antibody were used to reverse the aneurysms. We showed that PGG-NPs therapy could suppress infiltration of macrophages, CD8 and CD4 subsets of T cells, matrix metalloproteinases (MMPs), inflammatory cytokines interferon (IFN-γ) and interleukin (IL)-6 at the local and systemic level. Moreover, such PGG-NPs therapy increases the induction of anti-inflammatory cytokines IL-13, IL-27 and IL-10 at the local and systemic level. The therapy also led to remodeling of elastic lamina at the aneurysm site. CONCLUSION: Nanoparticles-loaded pentagalloyl glucose therapy can be an effective treatment option against advanced stage aneurysms to reverse the disease by ameliorating inflammation and restoring arterial homeostasis.

Cholesterol-Ester Transfer Protein Alters M1 and M2 Macrophage Polarization and Worsens Experimental Elastase-Induced Pulmonary Emphysema.

Cholesterol-ester transfer protein (CETP) plays a role in atherosclerosis, the inflammatory response to endotoxemia and in experimental and human sepsis. Functional alterations in lipoprotein (LP) metabolism and immune cell populations, including macrophages, occur during sepsis and may be related to comorbidities such as chronic obstructive pulmonary disease (COPD). Macrophages are significantly associated with pulmonary emphysema, and depending on the microenvironment, might exhibit an M1 or M2 phenotype. Macrophages derived from the peritoneum and bone marrow reveal CETP that contributes to its plasma concentration. Here, we evaluated the role of CETP in macrophage polarization and elastase-induced pulmonary emphysema (ELA) in human CETP-expressing transgenic (huCETP) (line 5203, C57BL6/J background) male mice and compared it to their wild type littermates. We showed that bone marrow-derived macrophages from huCETP mice reduce polarization toward the M1 phenotype, but with increased IL-10. Compared to WT, huCETP mice exposed to elastase showed worsened lung function with an increased mean linear intercept (Lm), reflecting airspace enlargement resulting from parenchymal destruction with increased expression of arginase-1 and IL-10, which are M2 markers. The cytokine profile revealed increased IL-6 in plasma and TNF, and IL-10 in bronchoalveolar lavage (BAL), corroborating with the lung immunohistochemistry in the huCETP-ELA group compared to WT-ELA. Elastase treatment in the huCETP group increased VLDL-C and reduced HDL-C. Elastase-induced pulmonary emphysema in huCETP mice promotes lung M2-like phenotype with a deleterious effect in experimental COPD, corroborating the in vitro result in which CETP promoted M2 macrophage polarization. Our results suggest that CETP is associated with inflammatory response and influences the role of macrophages in COPD.

Long-term endogenous acetylcholine deficiency potentiates pulmonary inflammation in a murine model of elastase-induced emphysema.

Acetylcholine (ACh), the neurotransmitter of the cholinergic system, regulates inflammation in several diseases including pulmonary diseases. ACh is also involved in a non-neuronal mechanism that modulates the innate immune response. Because inflammation and release of pro-inflammatory cytokines are involved in pulmonary emphysema, we hypothesized that vesicular acetylcholine transport protein (VAChT) deficiency, which leads to reduction in ACh release, can modulate lung inflammation in an experimental model of emphysema. Mice with genetical reduced expression of VAChT (VAChT KDHOM 70%) and wild-type mice (WT) received nasal instillation of 50 uL of porcine pancreatic elastase (PPE) or saline on day 0. Twenty-eight days after, animals were evaluated. Elastase instilled VAChT KDHOM mice presented an increase in macrophages, lymphocytes, and neutrophils in bronchoalveolar lavage fluid and MAC2-positive macrophages in lung tissue and peribronchovascular area that was comparable to that observed in WT mice. Conversely, elastase instilled VAChT KDHOM mice showed significantly larger number of NF-κB-positive cells and isoprostane staining in the peribronchovascular area when compared to elastase-instilled WT-mice. Moreover, elastase-instilled VAChT-deficient mice showed increased MCP-1 levels in the lungs. Other cytokines, extracellular matrix remodeling, alveolar enlargement, and lung function were not worse in elastase-instilled VAChT deficiency than in elastase-instilled WT-controls. These data suggest that decreased VAChT expression may contribute to the pathogenesis of emphysema, at least in part, through NF-κB activation, MCP-1, and oxidative stress pathways. This study highlights novel pathways involved in lung inflammation that may contribute to the development of chronic obstrutive lung disease (COPD) in cholinergic deficient individuals such as Alzheimer's disease patients.

Fcγ receptor activation mediates vascular inflammation and abdominal aortic aneurysm development.

BACKGROUND: Abdominal aortic aneurysm (AAA), a degenerative vascular pathology characterized by permanent dilation of the aorta, is considered a chronic inflammatory disease involving innate/adaptive immunity. However, the functional role of antibody-dependent immune response against antigens present in the damaged vessel remains unresolved. We hypothesized that engagement of immunoglobulin G (IgG) Fc receptors (FcγR) by immune complexes (IC) in the aortic wall contributes to AAA development. We therefore evaluated FcγR expression in AAA lesions and analysed whether inhibition of FcγR signaling molecules (γ-chain and Syk kinase) influences AAA formation in mice. METHODS: FcγR gene/protein expression was assessed in human and mouse AAA tissues. Experimental AAA was induced by aortic elastase perfusion in wild-type (WT) mice and γ-chain knockout (γKO) mice (devoid of activating FcγR) in combination with macrophage adoptive transfer or Syk inhibitor treatment. To verify the mechanisms of FcγR in vitro, vascular smooth muscle cells (VSMC) and macrophages were stimulated with IgG IC. RESULTS: FcγR overexpression was detected in adventitia and media layers of human and mouse AAA. Elastase-perfused γKO mice exhibited a decrease in AAA incidence, aortic dilation, elastin degradation, and VSMC loss. This was associated with (1) reduced infiltrating leukocytes and immune deposits in AAA lesions, (2) inflammatory genes and metalloproteinases downregulation, (3) redox balance restoration, and (4) converse phenotype of anti-inflammatory macrophage M2 and contractile VSMC. Adoptive transfer of FcγR-expressing macrophages aggravated aneurysm in γKO mice. In vitro, FcγR deficiency attenuated inflammatory gene expression, oxidative stress, and phenotypic switch triggered by IC. Additionally, Syk inhibition prevented IC-mediated cell responses, reduced inflammation, and mitigated AAA formation. CONCLUSION: Our findings provide insight into the role and mechanisms mediating IgG-FcγR-associated inflammation and aortic wall injury in AAA, which might represent therapeutic targets against AAA disease.

Effect of Slit/Robo signaling on regeneration in lung emphysema.

Emphysema, a pathological component of chronic obstructive pulmonary disease, causes irreversible damage to the lung. Previous studies have shown that Slit plays essential roles in cell proliferation, angiogenesis, and organ development. In this study, we evaluated the effect of Slit2 on the proliferation and migration of mouse lung epithelial cells and its role in regeneration in an emphysema lung mouse model. Here, we have shown that Slit2/Robo signaling contributes to the regeneration of lungs damaged by emphysema. Mouse epithelial lung cells treated with Slit2 exhibited increased proliferation and migration in vitro. Our results also showed that Slit2 administration improved alveolar regeneration in the emphysema mouse model in vivo. Furthermore, Slit2/Robo signaling increased the phosphorylation of ERK and Akt, which was mediated by Ras activity. These Slit2-mediated cellular signaling processes may be involved in the proliferation and migration of mouse lung epithelial cells and are also associated with the potential mechanism of lung regeneration. Our findings suggest that Slit2 administration may be beneficial for alveolar regeneration in lungs damaged by emphysema.

[Studies on Elastase and Elastase Inhibitor from Aspergillus flavus].

The biological properties of elastase and Aspergillus flavus elastase inhibitor (AFLEI) from A. flavus were examined. Pathogenicity of elastase was investigated in mice immunocompromised with cyclophosphamide, cyclosporine, prednisolone and carrageenan. Compared to cyclophosphamide immunocompromised mice treated with the spores of elastase nonproducing strain, cyclophosphamide immunocompromised mice treated with the spores of elastase producing strain had a significantly shorter survival rate. Molecular mass of AFLEI was determined to be 7525.8 Da. The elastolytic activity of elastases from A. flavus, and human leukocytes were inhibited by AFLEI. The primary structure of AFLEI was determined by the Edman sequencing procedure. The search for amino acid homology with other proteins demonstrated that amino acid residues 1 to 68 of AFLEI are 100% identical to residues 20 to 87 of the hypothetical protein AFUA_3G14940 of A. fumigatus. When immunocompromised mice administered of cyclophosphamide were infected by inhalation of A. flavus then administered amphotericin B (AMPH) alone or in combination with AFLEI, survival rate tended to be higher with combination treatment than with AMPH alone. Moreover, although extensive bleeding was seen in pathology sections taken from rat lung resected 24 h after elastase was administered to the lung via the bronchus, this bleeding was inhibited by AFLEI. The X-ray analysis has revealed that the structure of this inhibitor was wedge shaped and composed of a binding loop and a scaffold protein core. As synthetic-inhibitor strongly inhibited cytotoxicity induced by elastase in human-derived cells, it could prove beneficial for the treatment of pulmonary aspergillosis.

Chronic exposure to diesel particles worsened emphysema and increased M2-like phenotype macrophages in a PPE-induced model.

Chronic exposure to ambient levels of air pollution induces respiratory illness exacerbation by increasing inflammatory responses and apoptotic cells in pulmonary tissues. The ineffective phagocytosis of these apoptotic cells (efferocytosis) by macrophages has been considered an important factor in these pathological mechanisms. Depending on microenvironmental stimuli, macrophages can assume different phenotypes with different functional actions. M1 macrophages are recognized by their proinflammatory activity, whereas M2 macrophages play pivotal roles in responding to microorganisms and in efferocytosis to avoid the progression of inflammatory conditions. To verify how exposure to air pollutants interferes with macrophage polarization in emphysema development, we evaluated the different macrophage phenotypes in a PPE- induced model with the exposure to diesel exhaust particles. C57BL/6 mice received intranasal instillation of porcine pancreatic elastase (PPE) to induce emphysema, and the control groups received saline. Both groups were exposed to diesel exhaust particles or filtered air for 60 days according to the groups. We observed that both the diesel and PPE groups had an increase in alveolar enlargement, collagen and elastic fibers in the parenchyma and the number of macrophages, lymphocytes and epithelial cells in BAL, and these responses were exacerbated in animals that received PPE instillation prior to exposure to diesel exhaust particles. The same response pattern was found inCaspase-3 positive cell analysis, attesting to an increase in cell apoptosis, which is in agreement with the increase in M2 phenotype markers, measured by RT-PCR and flow cytometry analysis. We did not verify differences among the groups for the M1 phenotype. In conclusion, our results showed that both chronic exposure to diesel exhaust particles and PPE instillation induced inflammatory conditions, cell apoptosis and emphysema development, as well as an increase in M2 phenotype macrophages, and the combination of these two factors exacerbated these responses. The predominance of the M2-like phenotype likely occurred due to the increased demand for efferocytosis. However, M2 macrophage activity was ineffective, resulting in emphysema development and worsening of symptoms.