Lung parenchyma remodeling in a murine model of chronic allergic inflammation

Lung Mechanics Over the Century: From Bench to Bedside and Back to Bench

Lung physiology research advanced significantly over the last 100 years. Respiratory mechanics applied to animal models of lung disease extended the knowledge of the workings of respiratory system. In human research, a better understanding of respiratory mechanics has contributed to development of mechanical ventilators. In this review, we explore the use of respiratory mechanics in basic science to investigate asthma and chronic obstructive pulmonary disease (COPD). We also discuss the use of lung mechanics in clinical care and its role on the development of modern mechanical ventilators. Additionally, we analyse some bench-developed technologies that are not in widespread use in the present but can become part of the clinical arsenal in the future. Finally, we explore some of the difficult questions that intensive care doctors still face when managing respiratory failure. Bringing back these questions to bench can help to solve them. Interaction between basic and translational science and human subject investigation can be very rewarding, as in the conceptualization of “Lung Protective Ventilation” principles. We expect this interaction to expand further generating new treatments and managing strategies for patients with respiratory disease.

Fish Oil Nanoemulsion Supplementation Attenuates Bleomycin-Induced Pulmonary Fibrosis BALB/c Mice

Diets rich in omega-3 or -6 fatty acids will produce different profiles for cell membranes phospholipid constitutions. Omegas 3 and 6 are part of the diet and can modulate the inflammatory profile. We evaluated the effects of the oral absorption of fish oil, when associated with a lipid nanoemulsion in an experimental pulmonary inflammatory model. Pulmonary fibrosis is a disease associated with excessive extracellular matrix deposition. We determined to investigate the morphophysiological mechanisms in mice that were pretreated after induction with bleomycin (BLM). The pretreatment was for 21 days with saline solution, sunflower oil (SO), fish oil (FO), and fish oil nanoemulsion (NEW3). The animals received a daily dose of 50 mg/Kg of docosahexaenoic acid DHA and 10 mg/Kg eicosapentaenoic (EPA) (100 mg/Kg), represented by a daily dose of 40 µL of NEW3. The blank group was treated with the same amount daily (40 µL) during the 21 days of pretreatment. The animals were treated with SO and FO, 100 mg/Kg (containing 58 mg/Kg of polyunsaturated fats/higher% linoleic acid) and 100 mg/Kg (50 mg/Kg of DHA and 10 mg/Kg EPA), respectively. A single dose of 5 mg/mL (50 μL) bleomycin sulfate, by the intratracheal surgical method in BALB/cAnNTac (BALB/c). NEW3 significantly reduced fibrotic progression, which can be evidenced by the protection from loss of body mass, increase in respiratory incursions per minute, decreased spacing of alveolar septa, decreased severity of fibrosis, and changes in the respiratory system. NEW3 attenuated the inflammatory changes developed in the experimental model of pulmonary fibrosis, while group SO showed a significant increase in inflammatory changes. This concluded that the presented results demonstrated that is possible to positively modulate the immune and inflamamtory response to an external agressor, by changing the nutitional intake of specific fatty acids, such as omega-3 placed in fish oil. Moreover, these benefits can be improved by the nanoencapsulation of fish oil in lipid nanoemulsions.

Effects of a novel roflumilast and formoterol fumarate dry powder inhaler formulation in experimental allergic asthma

In this study we aimed to develop a roflumilast (R) and formoterol fumarate (F) dry powder inhaler formulation (DPI) incorporating HPβCD by spray drying and evaluated if it attenuates the inflammatory process and improves lung function in a murine model of ovalbumin induced allergic asthma. The DPI was characterized by powder X-ray diffraction, thermal analysis, scanning electron microscopy, particle size, density, specific surface area and dynamic vapor sorption analyses. In vitro deposition studies were performed using a NGI, while transepithelial permeability and in vivo effects on lung mechanics and inflammation in a model of allergic asthma were also assessed. The R:F formulation was amorphous with high glass transition temperatures, comprised of wrinkled particles, had low bulk and tapped densities, high surface area, suitable particle size for pulmonary delivery and exhibited no recrystallization even at high relative humidities. MMAD were statistically similar of 4.22 ± 0.19 and 4.32 ± 0.13 µm for F and R, respectively. Fine particle fractions (<5 µm) were of more than 50% of the emitted dose. The R:F formulation led to reduced eosinophil infiltration and airway collagen fiber content, yielding decreased airway hyperresponsiveness. In the current asthma model, the R:F formulation combination decreased inflammation and remodeling, thus improving lung mechanics.

Nanoparticle-based thymulin gene therapy therapeutically reverses key pathology of experimental allergic asthma

Despite long-standing efforts to enhance care for chronic asthma, symptomatic treatments remain the only option to manage this highly prevalent and debilitating disease. We demonstrate that key pathology of allergic asthma can be almost completely resolved in a therapeutic manner by inhaled gene therapy. After the disease was fully and stably established, we treated mice intratracheally with a single dose of thymulin-expressing plasmids delivered via nanoparticles engineered to have a unique ability to penetrate the airway mucus barrier. Twenty days after the treatment, we found that all key pathologic features found in the asthmatic lung, including chronic inflammation, pulmonary fibrosis, and mechanical dysregulation, were normalized. We conducted tissue- and cell-based analyses to confirm that the therapeutic intervention was mediated comprehensively by anti-inflammatory and antifibrotic effects of the therapy. We believe that our findings open a new avenue for clinical development of therapeutically effective gene therapy for chronic asthma.

Cannabidiol reduces airway inflammation and fibrosis in experimental allergic asthma

Asthma is characterized by chronic lung inflammation and airway hyperresponsiveness. Asthma remains a major public health problem and, at present, there are no effective interventions capable of reversing airway remodelling. Cannabidiol (CBD) is known to exert immunomodulatory effects through the activation of cannabinoid-1 and - 2 (CB₁ and CB₂) receptors located in the central nervous system and immune cells, respectively. However, as the role of CBD on airway remodelling and the mechanisms of CB₁ and CB₂ aren't fully elucidated, this study was designed to evaluate the effects of cannabidiol in this scenario. Allergic asthma was induced in Balb/c mice exposed to ovalbumin, and respiratory mechanics, collagen fibre content in airway and alveolar septa, cytokine levels, and CB₁ and CB₂ expression were determined. Moreover, expressions of CB₁ and CB₂ in induced sputum of asthmatic individuals and their correlation with airway inflammation and lung function were also evaluated. CBD treatment, regardless of dosage, decreased airway hyperresponsiveness, whereas static lung elastance only reduced with high dose. These outcomes were accompanied by decreases in collagen fibre content in both airway and alveolar septa and the expression of markers associated with inflammation in the bronchoalveolar lavage fluid and lung homogenate. There was a significant and inverse correlation between CB¹ levels and lung function in asthmatic patients. CBD treatment decreased the inflammatory and remodelling processes in the model of allergic asthma. The mechanisms of action appear to be mediated by CB₁/CB₂ signalling, but these receptors may act differently on lung inflammation and remodelling.

Serum from Asthmatic Mice Potentiates the Therapeutic Effects of Mesenchymal Stromal Cells in Experimental Allergic Asthma

Asthma is a chronic inflammatory disease characterized by airway inflammation and remodeling, which can lead to progressive decline of lung function. Although mesenchymal stromal cells (MSCs) have shown beneficial immunomodulatory properties in preclinical models of allergic asthma, effects on airway remodeling have been limited. Mounting evidence suggests that prior exposure of MSCs to specific inflammatory stimuli or environments can enhance their immunomodulatory properties. Therefore, we investigated whether stimulating MSCs with bronchoalveolar lavage fluid (BALF) or serum from asthmatic mice could potentiate their therapeutic properties in experimental asthma. In a house dust mite (HDM) extract asthma model in mice, unstimulated, asthmatic BALF‐stimulated, or asthmatic serum‐stimulated MSCs were administered intratracheally 24 hours after the final HDM challenge. Lung mechanics and histology; BALF protein, cellularity, and biomarker levels; and lymph‐node and bone marrow cellularity were assessed. Compared with unstimulated or BALF‐stimulated MSCs, serum‐stimulated MSCs further reduced BALF levels of interleukin (IL)‐4, IL‐13, and eotaxin, total and differential cellularity in BALF, bone marrow and lymph nodes, and collagen fiber content, while increasing BALF IL‐10 levels and improving lung function. Serum stimulation led to higher MSC apoptosis, expression of various mediators (transforming growth factor‐β, interferon‐γ, IL‐10, tumor necrosis factor‐α‐stimulated gene 6 protein, indoleamine 2,3‐dioxygenase‐1, and IL‐1 receptor antagonist), and polarization of macrophages to M2 phenotype. In conclusion, asthmatic serum may be a novel strategy to potentiate therapeutic effects of MSCs in experimental asthma, leading to further reductions in both inflammation and remodeling than can be achieved with unstimulated MSCs. stem cells translational medicine2019;8:301&312

Effects of Diet-Induced Obesity on Tracheal Responsiveness to Methacholine, Tracheal Visfatin Level, and Lung Histological Changes in Ovalbumin-Sensitized Female Wistar Rats

Many studies have shown a close relationship between obesity and asthma severity. In the present study, the effects of diet-induced obesity were examined on airway responsiveness to methacholine in addition to visfatin level in female Wistar rats' tracheae after sensitization with ovalbumin. The rats were divided into four groups: control with normal diet (ND), ovalbumin (OVA)-sensitized with normal diet (S + ND), high-fat diet (HFD), and OVA-sensitized with a high-fat diet (S + HFD). The animals were fed for 8 weeks with standard pelts or high-fat diet and then sensitized and challenged with OVA or saline for another 4 weeks. At the end of the study, the tracheae were isolated and assessed for airway responsiveness and visfatin protein levels. Diet-induced obesity groups developed increased weight and obesity indices (p < 0.001). After sensitization with OVA and diet-induced obesity, there were marked leftward shifts in methacholine concentration-response curves in S + HFD group compared to other groups. Also, maximum response was the highest (p < 0.05 to p < 0.001), EC₅₀ was the lowest (p < 0.05 to p < 0.001), and visfatin protein level was the highest (p < 0.05 to p < 0.01) in S + HFD. According to results, diet-induced obesity caused airway hyperresponsiveness to methacholine and enhanced visfatin protein levels in the tracheae of ovalbumin-sensitized female rats. Our results suggested that, in obese ovalbumin-sensitized conditions in female rats, the local production of adipocytokines, such as visfatin, may be increased, resulting in the deterioration of inflammation in lungs. This finding shows a possible mechanism for the altered phenotype in obesity-ovalbumin sensitization conditions in female rats.

Eicosapentaenoic Acid Enhances the Effects of Mesenchymal Stromal Cell Therapy in Experimental Allergic Asthma

Asthma is characterized by chronic lung inflammation and airway hyperresponsiveness. Despite recent advances in the understanding of its pathophysiology, asthma remains a major public health problem and, at present, there are no effective interventions capable of reversing airway remodeling. Mesenchymal stromal cell (MSC)-based therapy mitigates lung inflammation in experimental allergic asthma; however, its ability to reduce airway remodeling is limited. We aimed to investigate whether pre-treatment with eicosapentaenoic acid (EPA) potentiates the therapeutic properties of MSCs in experimental allergic asthma. Seventy-two C57BL/6 mice were used. House dust mite (HDM) extract was intranasally administered to induce severe allergic asthma in mice. Unstimulated or EPA-stimulated MSCs were administered intratracheally 24 h after final HDM challenge. Lung mechanics, histology, protein levels of biomarkers, and cellularity in bronchoalveolar lavage fluid (BALF), thymus, lymph nodes, and bone marrow were analyzed. Furthermore, the effects of EPA on lipid body formation and secretion of resolvin-D₁ (RvD₁), prostaglandin E₂ (PGE₂), interleukin (IL)-10, and transforming growth factor (TGF)-β1 by MSCs were evaluated in vitro. EPA-stimulated MSCs, compared to unstimulated MSCs, yielded greater therapeutic effects by further reducing bronchoconstriction, alveolar collapse, total cell counts (in BALF, bone marrow, and lymph nodes), and collagen fiber content in airways, while increasing IL-10 levels in BALF and M2 macrophage counts in lungs. In conclusion, EPA potentiated MSC-based therapy in experimental allergic asthma, leading to increased secretion of pro-resolution and anti-inflammatory mediators (RvD₁, PGE₂, IL-10, and TGF-β), modulation of macrophages toward an anti-inflammatory phenotype, and reduction in the remodeling process. Taken together, these modifications may explain the greater improvement in lung mechanics obtained. This may be a promising novel strategy to potentiate MSCs effects.

Inflammatory and Oxidative Stress Markers in Experimental Allergic Asthma

Ovalbumin-induced allergic lung inflammation (ALI) is a condition believed to be mediated by cytokines, extracellular matrix remodeling, and redox imbalance. In this study, we evaluated pulmonary function together with inflammatory markers as interleukin-4 (IL-4), myeloperoxidase (MPO), eosinophil cells, and redox markers in the lungs of BALB/c mice after ovalbumin (OVA) sensitization and challenge. Our results showed an increase in bronchial hyperresponsiveness stimulated by methacholine (Mch), inflammatory cell influx, especially eosinophils together with an increase of high mobility group box 1 (HMGB1) and altered lipid peroxidation (LP) and antioxidant defenses in the OVA group compared to the control group (p ≤ 0.5). Thus, we demonstrated that OVA-induced ALI altered redox status concomitantly with impaired lung function, which was associated with HMGB1 expression and proteolytic remodeling. Taken together all results found here, we may suggest HMGB1 is an important therapeutic target for asthma, once orchestrates the redox signaling, inflammation, and remodeling that contribute to the disease development.

Human adipose tissue mesenchymal stromal cells and their extracellular vesicles act differentially on lung mechanics and inflammation in experimental allergic asthma

Background

Asthma is a chronic inflammatory disease that can be difficult to treat due to its complex pathophysiology. Most current drugs focus on controlling the inflammatory process, but are unable to revert the changes of tissue remodeling. Human mesenchymal stromal cells (MSCs) are effective at reducing inflammation and tissue remodeling; nevertheless, no study has evaluated the therapeutic effects of extracellular vesicles (EVs) obtained from human adipose tissue-derived MSCs (AD-MSC) on established airway remodeling in experimental allergic asthma.

Methods

C57BL/6 female mice were sensitized and challenged with ovalbumin (OVA). Control (CTRL) animals received saline solution using the same protocol. One day after the last challenge, each group received saline, 10⁵ human AD-MSCs, or EVs (released by 10⁵ AD-MSCs). Seven days after treatment, animals were anesthetized for lung function assessment and subsequently euthanized. Bronchoalveolar lavage fluid (BALF), lungs, thymus, and mediastinal lymph nodes were harvested for analysis of inflammation. Collagen fiber content of airways and lung parenchyma were also evaluated.

Results

In OVA animals, AD-MSCs and EVs acted differently on static lung elastance and on BALF regulatory T cells, CD3⁺CD4⁺ T cells, and pro-inflammatory mediators (interleukin [IL]-4, IL-5, IL-13, and eotaxin), but similarly reduced eosinophils in lung tissue, collagen fiber content in airways and lung parenchyma, levels of transforming growth factor-β in lung tissue, and CD3⁺CD4⁺ T cell counts in the thymus. No significant changes were observed in total cell count or percentage of CD3⁺CD4⁺ T cells in the mediastinal lymph nodes.

Conclusions

In this immunocompetent mouse model of allergic asthma, human AD-MSCs and EVs effectively reduced eosinophil counts in lung tissue and BALF and modulated airway remodeling, but their effects on T cells differed in lung and thymus. EVs may hold promise for asthma; however, further studies are required to elucidate the different mechanisms of action of AD-MSCs versus their EVs.

Bone Marrow, Adipose, and Lung Tissue-Derived Murine Mesenchymal Stromal Cells Release Different Mediators and Differentially Affect Airway and Lung Parenchyma in Experimental Asthma

Mesenchymal stromal cells (MSCs) from different sources have differential effects on lung injury. To compare the effects of murine MSCs from bone marrow (BM), adipose tissue (AD), and lung tissue (LUNG) on inflammatory and remodeling processes in experimental allergic asthma, female C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) or saline (C). Twenty‐four hours after the last challenge, mice received either saline (50 µl, SAL), BM‐MSCs, AD‐MSCs, or LUNG‐MSCs (10⁵ cells per mouse in 50 µl total volume) intratracheally. At 1 week, BM‐MSCs produced significantly greater reductions in resistive and viscoelastic pressures, bronchoconstriction index, collagen fiber content in lung parenchyma (but not airways), eosinophil infiltration, and levels of interleukin (IL)‐4, IL‐13, transforming growth factor (TGF)‐β, and vascular endothelial growth factor (VEGF) in lung homogenates compared to AD‐MSCs and LUNG‐MSCs. Only BM‐MSCs increased IL‐10 and interferon (IFN)‐γ in lung tissue. In parallel in vitro experiments, BM‐MSCs increased M2 macrophage polarization, whereas AD‐MSCs and LUNG‐MSCs had higher baseline levels of IL‐4, insulin‐like growth factor (IGF), and VEGF secretion. Exposure of MSCs to serum specimens obtained from asthmatic mice promoted reductions in secretion of these mediators, particularly in BM‐MSCs. Intratracheally administered BM‐MSCs, AD‐MSCs, and LUNG‐MSCs were differentially effective at reducing airway inflammation and remodeling and improving lung function in the current model of allergic asthma. In conclusion, intratracheal administration of MSCs from BM, AD, and LUNG were differentially effective at reducing airway inflammation and remodeling and improving lung function comparably reduced inflammation and fibrogenesis in this asthma model. However, altered lung mechanics and lung remodeling responded better to BM‐MSCs than to AD‐MSCs or LUNG‐MSCs. Moreover, each type of MSC was differentially affected in a surrogate in vitro model of the in vivo lung environment. Stem Cells Translational Medicine2017;6:1557–1567

Moderate Aerobic Training Improves Cardiorespiratory Parameters in Elastase-Induced Emphysema

Aim: We investigated the therapeutic effects of aerobic training on lung mechanics, inflammation, morphometry and biological markers associated with inflammation, and endothelial cell damage, as well as cardiac function in a model of elastase-induced emphysema.

Methods: Eighty-four BALB/c mice were randomly allocated to receive saline (control, C) or 0.1 IU porcine pancreatic elastase (emphysema, ELA) intratracheally once weekly for 4 weeks. After the end of administration period, once cardiorespiratory impairment associated with emphysema was confirmed, each group was further randomized into sedentary (S) and trained (T) subgroups. Trained mice ran on a motorized treadmill, at moderate intensity, 30 min/day, 3 times/week for 4 weeks.

Results: Four weeks after the first instillation, ELA animals, compared to C, showed: (1) reduced static lung elastance (Est,L) and levels of vascular endothelial growth factor (VEGF) in lung tissue, (2) increased elastic and collagen fiber content, dynamic elastance (E, in vitro), alveolar hyperinflation, and levels of interleukin-1β and tumor necrosis factor (TNF)-α, and (3) increased right ventricular diastolic area (RVA). Four weeks after aerobic training, ELA-T group, compared to ELA-S, was associated with reduced lung hyperinflation, elastic and collagen fiber content, TNF-α levels, and RVA, as well as increased Est,L, E, and levels of VEGF.

Conclusion: Four weeks of regular and moderate intensity aerobic training modulated lung inflammation and remodeling, thus improving pulmonary function, and reduced RVA and pulmonary arterial hypertension in this animal model of elastase-induced emphysema.

The tyrosine kinase inhibitor dasatinib reduces lung inflammation and remodelling in experimental allergic asthma

BACKGROUND AND PURPOSE

Asthma is characterized by chronic lung inflammation and airway hyperresponsiveness. Despite recent advances in understanding of its pathophysiology, asthma remains a major public health problem, and new therapeutic strategies are urgently needed. In this context, we sought to ascertain whether treatment with the TK inhibitor dasatinib might repair inflammatory and remodelling processes, thus improving lung function, in a murine model of asthma.

EXPERIMENTAL APPROACH

Animals were sensitized and subsequently challenged, with ovalbumin (OVA) or saline. Twenty-four hours after the last challenge, animals were treated with dasatinib, dexamethasone, or saline, every 12 h for 7 consecutive days. Twenty-four hours after the last treatment, the animals were killed, and data were collected. Lung structure and remodelling were evaluated by morphometric analysis, immunohistochemistry, and transmission electron microscopy of lung sections. Inflammation was assessed by cytometric analysis and ELISA, and lung function was evaluated by invasive whole-body plethysmography.

KEY RESULTS

In OVA mice, dasatinib, and dexamethasone led to significant reductions in airway hyperresponsiveness. Dasatinib was also able to attenuate alveolar collapse, contraction index, and collagen fibre deposition, as well as increasing elastic fibre content, in OVA mice. Concerning the inflammatory process, dasatinib reduced inflammatory cell influx to the airway and lung-draining mediastinal lymph nodes, without inducing the thymic atrophy promoted by dexamethasone.

CONCLUSIONS AND IMPLICATIONS

In this model of allergic asthma, dasatinib effectively blunted the inflammatory and remodelling processes in asthmatic lungs, enhancing airway repair and thus improving lung mechanics.

Regular and moderate aerobic training before allergic asthma induction reduces lung inflammation and remodeling

Experimental studies have reported that aerobic exercise after asthma induction reduces lung inflammation and remodeling. Nevertheless, no experimental study has analyzed whether regular/moderate aerobic training before the induction of allergic asthma may prevent these inflammatory and remodeling processes. For this purpose, BALB/c mice (n = 96) were assigned into non-trained and trained groups. Trained animals ran on a motorized treadmill at moderate intensity, 30 min/day, 3 times/week, for 8 weeks, and were further randomized into subgroups to undergo ovalbumin sensitization and challenge or receive saline using the same protocol. Aerobic training continued until the last challenge. Twenty-four hours after challenge, compared to non-trained animals, trained mice exhibited: (a) increased systolic output and left ventricular mass on echocardiography; (b) improved lung mechanics; (c) decreased smooth muscle actin expression and collagen fiber content in airways and lung parenchyma; (d) decreased transforming growth factor (TGF)-β levels in bronchoalveolar lavage fluid (BALF) and blood; (e) increased interferon (IFN)-γ in BALF and interleukin (IL)-10 in blood; and (f) decreased IL-4 and IL-13 in BALF. In conclusion, regular/moderate aerobic training prior to allergic asthma induction reduced inflammation and remodeling, perhaps through increased IL-10 and IFN-γ in tandem with decreased Th2 cytokines.

Angiotensin-(1-7) attenuates airway remodelling and hyperresponsiveness in a model of chronic allergic lung inflammation

BACKGROUND AND PURPOSE

A long-term imbalance between pro- and anti-inflammatory mediators leads to airway remodelling, which is strongly correlated to most of the symptoms, severity and progression of chronic lung inflammation. The Angiotensin-(1-7) [Ang-(1-7)]/Mas receptor axis of the renin-angiotensin system is associated with attenuation of acute and chronic inflammatory processes. In this study, we investigated the effects of Ang-(1-7) treatment in a model of chronic allergic lung inflammation.

EXPERIMENTAL APPROACH

Mice were sensitized to ovalbumin (OVA; 4 injections over 42 days, 14 days apart) and were challenged three times per week (days 21-46). These mice received Ang-(1-7) (1 μg·h(-1) , s.c.) by osmotic mini-pumps, for the last 28 days. Histology and morphometric analysis were performed in left lung and right ventricle. Airway responsiveness to methacholine, analysis of Ang-(1-7) levels (RIA), collagen I and III (qRT-PCR), ERK1/2 and JNK (Western blotting), IgE (elisa), cytokines and chemokines (elisa multiplex), and immunohistochemistry for Mas receptors were performed.

KEY RESULTS

Infusion of Ang-(1-7) in OVA-sensitized and challenged mice decreased inflammatory cell infiltration and collagen deposition in the airways and lung parenchyma, and prevented bronchial hyperresponsiveness. These effects were accompanied by decreased IgE and ERK1/2 phosphorylation, and decreased pro-inflammatory cytokines. Mas receptors were detected in the epithelium and bronchial smooth muscle, suggesting a site in the lung for the beneficial actions of Ang-(1-7).

CONCLUSIONS AND IMPLICATIONS

Ang-(1-7) exerted beneficial attenuation of three major features of chronic asthma: lung inflammation, airway remodelling and hyperresponsiveness. Our results support an important protective role of Ang-(1-7) in lung inflammation.

Effects of bone marrow mononuclear cells from healthy or ovalbumin-induced lung inflammation donors on recipient allergic asthma mice

Introduction

Asthma is characterized by a chronic inflammatory process which may lead to several changes in bone marrow cell composition. We hypothesized that bone marrow mononuclear cells (BMMCs) obtained from ovalbumin (OVA)-induced lung inflammation mice may promote different effects compared to BMMCs from healthy donors in a model of allergic asthma.

Methods

C57BL/6 mice were randomly assigned to two groups. In the OVA group, mice were sensitized and challenged with ovalbumin, while healthy animals (control group) received saline using the same protocol. BMMCs were analyzed by flow cytometry 24 hours after the last challenge. After BMMC characterization, another group of OVA mice were further randomized into three subgroups to receive intratracheal saline (BMMC-SAL), BMMCs from control or BMMCs from OVA mice (BMMC-Control and BMMC-OVA, respectively; 2x10⁶ cells/mouse), 24 hours after the last challenge.

Results

BMMC-OVA exhibited an increased percentage of eosinophils, monocytes and hematopoietic precursors, while mesenchymal stem cells decreased, as compared with BMMC-Control. BMMCs from both donor groups reduced airway resistance, alveolar collapse, bronchoconstriction index, eosinophil infiltration, collagen fiber content in alveolar septa and levels of interleukin (IL)-4, IL-5, IL-13, interferon-γ, transforming growth factor-β, and vascular endothelial growth factor in lung homogenates. However, the benefits of BMMCs were significantly more pronounced when cells were obtained from control donors.

Conclusion

Both BMMC-Control and BMMC-OVA reduced the inflammatory and remodeling processes; nevertheless, BMMC-Control led to a greater improvement in lung morphofunction, which may be due to different BMMC composition and/or properties.

Effects of inhalational anaesthetics in experimental allergic asthma

We evaluated whether isoflurane, halothane and sevoflurane attenuate the inflammatory response and improve lung morphofunction in experimental asthma. Fifty-six BALB/c mice were sensitised and challenged with ovalbumin and anaesthetised with isoflurane, halothane, sevoflurane or pentobarbital sodium for one hour. Lung mechanics and histology were evaluated. Gene expression of pro-inflammatory (tumour necrosis factor-α), pro-fibrogenic (transforming growth factor-β) and pro-angiogenic (vascular endothelial growth factor) mediators, as well as oxidative process modulators, were analysed. These modulators included nuclear factor erythroid-2 related factor 2, sirtuin, catalase and glutathione peroxidase. Isoflurane, halothane and sevoflurane reduced airway resistance, static lung elastance and atelectasis when compared with pentobarbital sodium. Sevoflurane minimised bronchoconstriction and cell infiltration, and decreased tumour necrosis factor-α, transforming growth factor-β, vascular endothelial growth factor, sirtuin, catalase and glutathione peroxidase, while increasing nuclear factor erythroid-2-related factor 2 expression. Sevoflurane down-regulated inflammatory, fibrogenic and angiogenic mediators, and modulated oxidant-antioxidant imbalance, improving lung function in this model of asthma.

DNA nanoparticle-mediated thymulin gene therapy prevents airway remodeling in experimental allergic asthma

Thymulin has been shown to present anti-inflammatory and anti-fibrotic properties in experimental lung diseases. We hypothesized that a biologically active thymulin analog gene, methionine serum thymus factor, delivered by highly compacted DNA nanoparticles may prevent lung inflammation and remodeling in a mouse model of allergic asthma. The DNA nanoparticles are composed of a single molecule of plasmid DNA compacted with block copolymers of poly-L-lysine and polyethylene glycol (CK30PEG), which have been found safe in a human phase I/II clinical trial. Thymulin plasmids were detected in the lungs of ovalbumin-challenged asthmatic mice up to 27days after administration of DNA nanoparticles carrying thymulin plasmids. A single dose of DNA nanoparticles carrying thymulin plasmids prevented lung inflammation, collagen deposition and smooth muscle hypertrophy in the lungs of a murine model of ovalbumin-challenged allergic asthma, leading to improved lung mechanics. In the present model of chronic allergic asthma, highly compacted DNA nanoparticles using thymulin analog gene modulated the inflammatory and remodeling processes improving lung mechanics.

Effects of Rho-kinase inhibition in lung tissue with chronic inflammation

We evaluated whether Rho-kinase inhibition (Y-27632) modulated distal lung responsiveness, inflammation, extracellular matrix remodeling and oxidative stress activation in guinea pigs (GPs) with chronic allergic inflammation. GPs were submitted to inhalation of ovalbumin (OVA-2×/week/4 weeks). From the 5th inhalation on, the Rho-kinase inhibitor group animals were submitted to Y-27632 inhalation 10min before each inhalation of OVA. Seventy-two hours after the seventh inhalation, the oscillatory mechanics of the distal lung strips were assessed under the baseline condition and after the ovalbumin challenge. Subsequently, the lung slices were submitted to morphometry. Rho-kinase inhibition in the ovalbumin-exposed animals attenuated distal lung elastance and resistance, eosinophils, IL-2, IL-4, IL-5, IL-13, TIMP-1, MMP-9, TGF-β, IFN-γ, NF-κB and iNOS-positive cells and the volume fraction of 8-iso-PGF2α, elastic, collagen and actin in alveolar walls compared with the OVA group (P<0.05). Rho-kinase inhibition contributed to the control of distal lung responsiveness, eosinophilic and Th1/Th2 responses and extracellular matrix remodeling in an animal model of chronic allergic inflammation.

Impact of Bacillus Calmette-Guérin Moreau vaccine on lung remodeling in experimental asthma

We analyzed the effects of different administration routes and application times of the BCG-Moreau strain on airway and lung inflammation and remodeling in a murine model of allergic asthma. BALB/c mice (n=168) were divided into two groups. The first group received BCG-Moreau strain while the second group received saline using the same protocol. BCG or saline were intradermally or intranasally injected one or two months before the induction of asthma. Mice were further sensitized and challenged with ovalbumin or received saline. Twenty-four hours after the last challenge, BCG prevented the triggering of pro-inflammatory cytokines, probably by increasing Foxp3 and interleukin (IL)-10, modulating eosinophil infiltration and collagen fiber deposition, thus reducing airway hyperresponsiveness. In conclusion, BCG-Moreau prevented lung remodeling in the present model of allergic asthma, regardless of administration route and time of vaccination. These beneficial effects may be related to the increase in regulatory T cells and to IL-10 production in tandem with decreased Th2 cytokines (IL-4, IL-5, and IL-13).

Eosinophilic inflammation in allergic asthma

Eosinophils are circulating granulocytes involved in pathogenesis of asthma. A cascade of processes directed by Th2 cytokine producing T-cells influence the recruitment of eosinophils into the lungs. Furthermore, multiple elements including interleukin (IL)-5, IL-13, chemoattractants such as eotaxin, Clara cells, and CC chemokine receptor (CCR)3 are already directly involved in recruiting eosinophils to the lung during allergic inflammation. Once recruited, eosinophils participate in the modulation of immune response, induction of airway hyperresponsiveness and remodeling, characteristic features of asthma. Various types of promising treatments for reducing asthmatic response are related to reduction in eosinophil counts both in human and experimental models of pulmonary allergic inflammation, showing that the recruitment of these cells really plays an important role in the pathophysiology of allergic diseases such asthma.

Bone marrow-derived mononuclear cells vs. mesenchymal stromal cells in experimental allergic asthma

We compared the effects of bone marrow-derived mononuclear cells (BMMCs) and mesenchymal stromal cells (MSCs) on airway inflammation and remodeling and lung mechanics in experimental allergic asthma. C57BL/6 mice were sensitized and challenged with ovalbumin (OVA group). A control group received saline using the same protocol. Twenty-four hours after the last challenge, groups were further randomized into subgroups to receive saline, BMMCs (2×10(6)) or MSCs (1×10(5)) intratracheally. BMMC and MSC administration decreased cell infiltration, bronchoconstriction index, alveolar collapse, collagen fiber content in the alveolar septa, and interleukin (IL)-4, IL-13, transforming growth factor (TGF)-β and vascular endothelial growth factor (VEGF) levels compared to OVA-SAL. Lung function, alveolar collapse, collagen fiber deposition in alveolar septa, and levels of TGF-β and VEGF improved more after BMMC than MSC therapy. In conclusion, intratracheal BMMC and MSC administration effectively modulated inflammation and fibrogenesis in an experimental model of asthma, but BMMCs was associated with greater benefit in terms of reducing levels of fibrogenesis-related growth factors.

Airway distension during lung inflation in healthy and allergic-sensitised mice in vivo

We evaluated the airway distention during lung inflation of varying size in healthy and allergic-sensitised mice in vivo. Computed tomography (CT) images of healthy and ovalbumin-treated mice were acquired using a synchrotron in vivo CT system when lung pressures was 0 and 20 cmH(2)O, and the morphometric distension (diameter, length, and volume) and the compliance of airway segments (to as small as ~150 μm internal diameter) were calculated. With respect to airway size, in healthy mice, the changes in airway diameter and compliance were larger in the small-airway group. In contrast, in allergic-sensitised mice, there were no significant differences in the changes in airway distension or compliance. Airway wall thickness in allergic-sensitised mice increased significantly in all airway groups, but the change was much larger in the small than in the large-airway group. Compared with healthy airways, the changes in diameter and airway compliance of the allergic-sensitised mice were significantly smaller in the small-airway group.

Bone marrow mononuclear cell therapy in experimental allergic asthma: intratracheal versus intravenous administration

We hypothesized that the route of administration would impact the beneficial effects of bone marrow-derived mononuclear cell (BMDMC) therapy on the remodelling process of asthma. C57BL/6 mice were randomly assigned to two main groups. In the OVA group, mice were sensitized and challenged with ovalbumin, while the control group received saline using the same protocol. Twenty-four hours before the first challenge, control and OVA animals were further randomized into three subgroups to receive saline (SAL), BMDMCs intravenously (2×10(6)), or BMDMCs intratracheally (2×10(6)). The following changes were induced by BMDMC therapy in OVA mice regardless of administration route: reduction in resistive and viscoelastic pressures, static elastance, eosinophil infiltration, collagen fibre content in airways and lung parenchyma; and reduction in the levels of interleukin (IL)-4, IL-13, transforming growth factor-β and vascular endothelial growth factor. In conclusion, BMDMC modulated inflammatory and remodelling processes regardless of administration route in this experimental model of allergic asthma.

The effect of angiotensin-converting enzyme inhibition by captopril on respiratory mechanics in healthy rats

CONTEXT

Angiotensin stimulates smooth-muscle contraction. Accordingly, angiotensin-converting enzyme (ACE) inhibition is expected to decrease airway resistance.

OBJECTIVES

To measure the effects of ACE inhibition on respiratory mechanics in healthy mammals.

MATERIALS AND METHODS

We measured respiratory mechanics before and after i.p. ACE inhibitor captopril (100 mg/kg) in normal anaesthetised rats. The end-inflation occlusion method allowed the measurements of respiratory system elastance and ohmic and viscoelastic pressure dissipations. Respiratory system hysteresis and the elastic and resistive work of breathing were calculated.

RESULTS

Captopril induced a reduction of the ohmic and the total respiratory system resistances, while respiratory system hysteresis and elastance did not change. Accordingly, a reduction of the resistive and of the total work of breathing was observed.

CONCLUSIONS

The captopril-induced reduction of airway resistance indicates that angiotensin modulates bronchomotor tone in basal conditions. ACE inhibition may positively affect respiratory system mechanics and work of breathing.

Grape seed extract attenuates lung parenchyma pathology in ovalbumin-induced mouse asthma model: an ultrastructural study

Due to the growing incidence of asthma and because of the non-specificity and side effects of the conventional drugs, the development of novel agents for the treatment of asthma has become considerably important. Natural plant products offer promising alternatives for the development of effective and safe treatments. Grape seed extract (GSE) is one such phytochemical supplement that has been shown to have potent antioxidant and anti-inflammatory effects. Thus, the present study aimed to investigate the effect of GSE to suppress lung parenchyma pathology and inflammation in ovalbumin-induced murine asthma model. Ovalbumin exposure was associated with many pathological and morphometric alterations in the lungs of asthmatic mice. The alterations involved alveolar size reduction, alveolar wall thickening, cellular infiltration and blood capillary congestion, as well as significant increase in the number of type II pneumocytes and lamellar bodies. However, GSE significantly ameliorated of the pathological changes of ovalbumin-induced asthma. The results support the possibility of GSE as an effective, safe anti-inflammatory dietary supplement to attenuate the pathogenicity of asthma. While these preliminary results appear promising, further studies are required to elucidate the precise mechanism of the modulatory effect of GSE on asthma remodeling.

Elastin in asthma

Extracellular matrix is generally increased in asthma, causing thickening of the airways which may either increase or decrease airway responsiveness, depending on the mechanical requirements of the deposited matrix. However, in vitro studies have shown that the altered extracellular matrix produced by asthmatic airway smooth muscle cells is able to induce increased proliferation of non-asthmatic smooth muscle cells, which is a process believed to contribute to airway hyper-responsiveness in asthma. Elastin is an extracellular matrix protein that is altered in asthmatic airways, but there has been no systematic investigation of the functional effect of these changes. This review reveals divergent reports of the state of elastin in the airway wall in asthma. In some layers of the airway it has been described as increased, decreased and/or fragmented, or unchanged. There is also considerable evidence for an imbalance of matrix metalloproteinases, which degrade elastin, and their respective inhibitors the tissue inhibitors of metalloproteinases, which collectively help to explain observations of both increased elastin and elastin fragments. A loss of lung elastic recoil in asthma suggests a mechanical role for disordered elastin in the aetiology of the disease, but extensive studies of elastin in other tissues show that elastin fragments elicit cellular effects such as increased proliferation and inflammation. This review summarises the current understanding of the role of elastin in the asthmatic airway.

Inducible nitric oxide synthase inhibition attenuates physical stress-induced lung hyper-responsiveness and oxidative stress in animals with lung inflammation

Mechanisms involved in stress-induced asthmatic alterations have been poorly characterised. We assessed whether inducible nitric oxide synthase (iNOS) inhibition modulates the stress-amplified lung parenchyma responsiveness, oxidative stress and extracellular matrix remodelling that was previously increased by chronic lung inflammation. Guinea pigs were subjected to 7 exposures to ovalbumin (1-5 mg/ml) or saline (OVA and SAL groups) over 4 weeks. To induce behavioural stress, animals were subjected to a forced swimming protocol (5 times/week, over 2 weeks; SAL-Stress and OVA-Stress groups) 24 h after the 4th inhalation. 1400W (iNOS-specific inhibitor) was administered intraperitoneally in the last 4 days of the protocol (SAL-1400W, OVA-1400W, SAL-Stress+1400W and OVA-Stress+1400W groups). Seventy-two hours after the last inhalation, animals were anaesthetised and exsanguinated, and adrenal glands were removed. Lung tissue resistance and elastance were evaluated by oscillatory mechanics and submitted for histopathological evaluation. Stressed animals had higher adrenal weights compared to non-stressed groups, which were reduced by 1400W treatment. Behavioural stress in sensitised animals amplified the resistance and elastance responses after antigen challenge, numbers of eosinophils and iNOS+ cells, actin content and 8-iso-PGF2α density in the distal lung compared to the OVA group. 1400W treatment in ovalbumin-exposed and stressed animals reduced lung mechanics, iNOS+ cell numbers and 8-iso-PGF2α density compared to sensitised and stressed animals that received vehicle treatment. We concluded that stress amplifies the distal lung constriction, eosinophilic inflammation, iNOS expression, actin content and oxidative stress previously induced by chronic lung inflammation. iNOS-derived NO contributes to stress-augmented lung tissue functional alterations in this animal model and is at least partially due to activation of the oxidative stress pathway.

Influenza A facilitates sensitization to house dust mite in infant mice leading to an asthma phenotype in adulthood

The origins of allergic asthma, particularly in infancy, remain obscure. Respiratory viral infections and allergen sensitization in early life have been associated with asthma in young children. However, a causal link has not been established. We investigated whether an influenza A infection in early life alters immune responses to house dust mite (HDM) and promotes an asthmatic phenotype later in life. Neonatal (8-day-old) mice were infected with influenza virus and 7 days later, exposed to HDM for 3 weeks. Unlike adults, neonatal mice exposed to HDM exhibited negligible immune responsiveness to HDM, but not to influenza A. HDM responsiveness in adults was associated with distinct Ly6c+ CD11b+ inflammatory dendritic cell and CD8α+ plasmacytoid (pDC) populations that were absent in HDM-exposed infant mice, suggesting an important role in HDM-mediated inflammation. Remarkably, HDM hyporesponsiveness was overcome when exposure occurred concurrently with an acute influenza infection; young mice now displayed robust allergen-specific immunity, allergic inflammation, and lung remodeling. Remodeling persisted into early adulthood, even after prolonged discontinuation of allergen exposure and was associated with marked impairment of lung function. Our data demonstrate that allergen exposure coincident with acute viral infection in early life subverts constitutive allergen hyporesponsiveness and imprints an asthmatic phenotype in adulthood.

Effects of cysteinyl-leukotriene receptors' antagonism by montelukast on lung mechanics and olfactory system histology in healthy mice

CONTEXT

At variance with steroid administration, the possible effects of leukotrienes inhibition on basal respiratory mechanics and olfactory system function are still unclear.

OBJECTIVE

To investigate if interference with the leukotrienes activity may influence basal lung mechanics in healthy mammals, as well as the olfactory system.

MATERIALS AND METHODS

We measured lung mechanics by the end-inflation occlusion method in control and in montelukast i.p. treated anaesthetised healthy mice (10 mg/kg/die for a week). A study of olfactory system histology was also conducted.

RESULTS

Elastance and resistive properties of the lung were not affected by montelukast, while a significant increment of lung hysteresis was observed. The analysis of olfactory system histology revealed no significant effects of montelukast compared to controls.

DISCUSSION AND CONCLUSIONS

Leukotrienes' antagonism does not affect respiratory mechanics in basal conditions, except for a hysteresis increment, which might counteract the increase in expiratory flow in asthmatic subjects assuming montelukast.

Impact of obesity on airway and lung parenchyma remodeling in experimental chronic allergic asthma

The impact of obesity on the inflammatory process has been described in asthma, however little is known about the influence of diet-induced obesity on lung remodeling. For this purpose, 56 recently weaned A/J mice were randomly divided into 2 groups. In the C group, mice were fed a standard chow diet, while OB animals received isocaloric high-fat diet to reach 1.5 of the mean body weight of C. After 12 weeks, each group was further randomized to be sensitized and challenged with ovalbumin (OVA) or saline. Twenty-four hours after the last challenge, collagen fiber content in airways and lung parenchyma, the volume proportion of smooth muscle-specific actin in alveolar ducts and terminal bronchiole, and the number of eosinophils in bronchoalveolar lavage fluid were higher in OB-OVA than C-OVA. In conclusion, diet-induced obesity enhanced lung remodeling resulting in higher airway responsiveness in the present experimental chronic allergic asthma.

Effects of bone marrow-derived mononuclear cells on airway and lung parenchyma remodeling in a murine model of chronic allergic inflammation

We hypothesized that bone marrow-derived mononuclear cells (BMDMC) would attenuate the remodeling process in a chronic allergic inflammation model. C57BL/6 mice were assigned to two groups. In OVA, mice were sensitized and repeatedly challenged with ovalbumin. Control mice (C) received saline under the same protocol. C and OVA were further randomized to receive BMDMC (2 × 10⁶) or saline intravenously 24 h before the first challenge. BMDMC therapy reduced eosinophil infiltration, smooth muscle-specific actin expression, subepithelial fibrosis, and myocyte hypertrophy and hyperplasia, thus causing a decrease in airway hyperresponsiveness and lung mechanical parameters. BMDMC from green fluorescent protein (GFP)-transgenic mice transplanted into GFP-negative mice yielded lower engraftment in OVA. BMDMC increased insulin-like growth factor expression, but reduced interleukin-5, transforming growth factor-β, platelet-derived growth factor, and vascular endothelial growth factor mRNA expression. In conclusion, in the present chronic allergic inflammation model, BMDMC therapy was an effective pre-treatment protocol that potentiated airway epithelial cell repair and prevented inflammatory and remodeling processes.

Ovalbumin sensitization and challenge increases the number of lung cells possessing a mesenchymal stromal cell phenotype

Background

Recent studies have indicated the presence of multipotent mesenchymal stromal cells (MSCs) in human lung diseases. Excess airway smooth muscle, myofibroblasts and activated fibroblasts have each been noted in asthma, suggesting that mesenchymal progenitor cells play a role in asthma pathogenesis. We therefore sought to determine whether MSCs are present in the lungs of ovalbumin (OVA)-sensitized and challenged mice, a model of allergic airways disease.

Methods

Balb/c mice were sensitized and challenged with PBS or OVA over a 25 day period. Flow cytometry as well as colony forming and differentiation potential were used to analyze the emergence of MSCs along with gene expression studies using immunochemical analyses, quantitative polymerase chain reaction (qPCR), and gene expression beadchips.

Results

A CD45-negative subset of cells expressed Stro-1, Sca-1, CD73 and CD105. Selection for these markers and negative selection against CD45 yielded a population of cells capable of adipogenic, osteogenic and chondrogenic differentiation. Lungs from OVA-treated mice demonstrated a greater average colony forming unit-fibroblast (CFU-F) than control mice. Sorted cells differed from unsorted lung adherent cells, exhibiting a pattern of gene expression nearly identical to bone marrow-derived sorted cells. Finally, cells isolated from the bronchoalveolar lavage of a human asthma patient showed identical patterns of cell surface markers and differentiation potential.

Conclusions

In summary, allergen sensitization and challenge is accompanied by an increase of MSCs resident in the lungs that may regulate inflammatory and fibrotic responses.

Sex-specific lung remodeling and inflammation changes in experimental allergic asthma

There is evidence that sex and sex hormones influence the severity of asthma. Airway and lung parenchyma remodeling and the relationship of ultrastructural changes to airway responsiveness and inflammation in male, female, and oophorectomized mice (OVX) were analyzed in experimental chronic allergic asthma. Seventy-two BALB/c mice were randomly divided into three groups (n=24/each): male, female, and OVX mice, whose ovaries were removed 7 days before the start of sensitization. Each group was further randomized to be sensitized and challenged with ovalbumin (OVA) or saline. Twenty-four hours after the last challenge, collagen fiber content in airways and lung parenchyma, the volume proportion of smooth muscle-specific actin in alveolar ducts and terminal bronchiole, the amount of matrix metalloproteinase (MMP)-2 and MMP-9, and the number of eosinophils and interleukin (IL)-4, IL-5, and transforming growth factor (TGF)-β levels in bronchoalveolar lavage fluid were higher in female than male OVA mice. The response of OVX mice was similar to that of males, except that IL-5 remained higher. Nevertheless, after OVA provocation, airway responsiveness to methacholine was higher in males compared with females and OVX mice. In conclusion, sex influenced the remodeling process, but the mechanisms responsible for airway hyperresponsiveness seemed to differ from those related to remodeling.

Low-intensity swimming training partially inhibits lipopolysaccharide-induced acute lung injury

BACKGROUND

Aerobic exercise decreases pulmonary inflammation and remodeling in experimental models of allergic asthma. However, the effects of aerobic exercise on pulmonary inflammation of nonallergic origin, such as in experimental models of acute lung injury induced by lipopolysaccharide (LPS), have not been evaluated.

OBJECTIVE

The present study evaluated the effects of aerobic exercise in a model of LPS-induced acute lung injury.

METHODS

BALB/c mice were divided into four groups: Control, Aerobic Exercise, LPS, and Aerobic Exercise + LPS. Swimming tests were conducted at baseline and at 3 and 6 wk. Low-intensity swimming training was performed for 6 wk, four times per week, 60 min per session. Intranasal LPS (1 mg x kg(-1) (60 microg per mouse)) was instilled 24 h after the last swimming physical test in the LPS and Aerobic Exercise + LPS mice, and the animals were studied 24 h after LPS instillation. Exhaled nitric oxide, respiratory mechanics, total and differential cell counts in bronchoalveolar lavage, and lung parenchymal inflammation and remodeling were evaluated.

RESULTS

LPS instillation resulted in increased levels of exhaled nitric oxide (P < 0.001), higher numbers of neutrophils in the bronchoalveolar lavage (P < 0.001) and in the lung parenchyma (P < 0.001), and decreased lung tissue resistance (P < 0.05) and volume proportion of elastic fibers (P < 0.01) compared with the Control group. Swim training in LPS-instilled animals resulted in significantly lower exhaled nitric oxide levels (P < 0.001) and fewer neutrophils in the bronchoalveolar lavage (P < 0.001) and the lung parenchyma (P < 0.01) compared with the LPS group.

CONCLUSIONS

These results suggest that low-intensity swimming training inhibits lung neutrophilic inflammation, but not remodeling and impaired lung mechanics, in a model of LPS-induced acute lung injury.

Effect of a matrix metalloproteinase-12 inhibitor, S-1, on allergic airway disease phenotypes in mice

OBJECTIVE

Matrix metalloproteinase-12 (MMP-12) has been reported to play an important role in chronic airway inflammatory diseases, but its detailed role in allergic airway disease is not well known. In this study, we investigated the expressions of MMP-12 and the effect of S-1, an MMP-12 inhibitor, in a mouse model of allergic airway inflammation.

MATERIALS AND METHODS

The expressions and activity of MMP-12 were measured by RT-PCR western blot and zymography, respectively. The locations in the airways of MMP-12 and elastin fiber were histologically studied. The mice were orally administered with S-1 during the period of antigen challenge. Bronchoalveolar lavage fluid (BALF) cells were counted, and the activity of MMP-12 in BALF was measured by zymography after the treatment with S-1.

RESULTS

The allergen challenge model resulted in increased eosinophil number in BALF and damage to elastin fiber. Upregulation of MMP-12 was also found in the airways of challenged mice. The increased eosinophil number in the BALF after antigen challenge was inhibited by S-1.

CONCLUSION

These findings suggest that MMP-12 may play an important role in the eosinophil infiltration of the allergic airway.

The olfactory system is affected by steroid aerosol treatment in mice

Asthma needs continuous treatment often for years. In humans, some drugs are administered via aerosol, therefore they come in contact with both respiratory and olfactory mucosa. We explored the possibility that antiasthma corticosteroid treatment could influence the olfactory function by passage through the nose. A group of mice was exposed twice daily for 42 days to fluticasone propionate aerosol and was compared with a control group. Olfactory behavior, respiratory mechanics, histology, and immunoreactivity in the olfactory system were assessed. Fluticasone-treated mice were slower in retrieving a piece of hidden food, but both groups were similarly fast when the food was visible. When a clearly detectable odor was present in the environment, all mice behaved in a similar way. Respiratory mechanics indices were similar in all mice except for the viscose resistance, which was reduced in fluticasone-treated mice. Olfactory mucosa of fluticasone-treated mice was thicker than that of controls. Slight but consistent differences in staining were present for Olfactory Marker Protein but not for other proteins. A mild impairment of olfactory function is present in mice chronically treated with fluticasone aerosol, apparently accompanied by slight modifications of the olfactory receptor cells, and suggests monitoring of olfactory function modifications in long-term steroid users.

Effects of Tityus serrulatus scorpion venom on lung mechanics and inflammation in mice

The present study evaluated the effects of an intramuscular injection of Tityus serrulatus venom (TsV) (0.67 miocrog/g) on lung mechanics and lung inflammation at 15, 30, 60 and 180 min after inoculation. TsV inoculation resulted in increased lung elastance when compared with the control group (p < 0.001); these values were significantly higher at 60 min than at 15 and 180 min (p < 0.05). Resistive pressure (DeltaP1) values decreased significantly at 30, 60 and 180 min after TsV injection (p < 0.001). TsV inoculation resulted in increased lung inflammation, characterised by an increased density of mononuclear cells at 15, 30, 60 and 180 min after TsV injection when compared with the control group (p < 0.001). TsV inoculation also resulted in an increased pulmonary density of polymorphonuclear cells at 15, 30 and 60 min following injection when compared to the control group (p < 0.001). In conclusion, T. serrulatus venom leads to acute lung injury, characterised by altered lung mechanics and increased pulmonary inflammation.

Regulatory T cells negatively regulate neovasculature of airway remodeling via DLL4-Notch signaling

Regulatory T cells (Treg) have been shown to prevent the development of allergic asthma; however, the role of Treg in asthma with established airway remodeling is unknown. To address this, we exploited an OVA-induced chronic asthma mouse model wherein Treg were adoptively transferred to the mice at chronic stage of the model. We found that among the structural alterations of airway remodeling, Treg selectively reduced the vessel numbers in both peritracheal and peribronchial regions and the lung parenchyma. Extracellular matrix deposition, mucus metaplasia, muscular hyperplasia, and vasodilation, as were also induced by chronic allergen challenge, were not affected by Treg. TUNEL staining of the lung sections revealed an increased endothelial cell (EC) apoptosis in mice receiving Treg transfers compared with their asthmatic counterparts. By using Matrigel angiogenesis assays, we showed that Treg inhibited EC angiogenesis both in vitro and in vivo. Treg preferentially expressed Notch ligand DLL4, and an anti-DLL4 blocking Ab abrogated the inhibitory effect of Treg on EC tube formation. In vivo, decreased airway and lung vessel numbers as well as ameliorated airway hyperresponsiveness after Treg transfers were reverted when Treg-derived DLL4 signal was blocked by the anti-DLL4 Ab. Our findings demonstrate a novel function of Treg whereby Treg down-regulate remodeling angiogenesis via proapoptotic DLL4-Notch signaling, and suggest a therapeutic potential of Treg in alleviating airway hyperresponsiveness of chronic asthma.

Lung parenchymal mechanics in health and disease

The mechanical properties of lung tissue are important determinants of lung physiological functions. The connective tissue is composed mainly of cells and extracellular matrix, where collagen and elastic fibers are the main determinants of lung tissue mechanical properties. These fibers have essentially different elastic properties, form a continuous network along the lungs, and are responsible for passive expiration. In the last decade, many studies analyzed the relationship between tissue composition, microstructure, and macrophysiology, showing that the lung physiological behavior reflects both the mechanical properties of tissue individual components and its complex structural organization. Different lung pathologies such as acute respiratory distress syndrome, fibrosis, inflammation, and emphysema can affect the extracellular matrix. This review focuses on the mechanical properties of lung tissue and how the stress-bearing elements of lung parenchyma can influence its behavior.

Immunological determinants in a mouse model of chemical-induced asthma after multiple exposures

In a mouse model of chemical-induced asthma, we investigated the effects of multiple challenges, using toluene diisocyanate (TDI), a known cause of occupational asthma. On days 1 and 7, BALB/c mice received TDI or vehicle (acetone/olive oil). On days 10, 13 and 16 the mice received an intranasal instillation of TDI. Ventilatory function (Penh) was monitored by whole body plethysmography for 40 min after each challenge. Reactivity to methacholine was measured 22 h later. Pulmonary inflammation, TNF-alpha and MIP-2 levels were assessed 24 h after the last challenge by broncho-alveolar lavage (BAL). Other immunological parameters included total IgE, lymphocyte sub-populations in auricular and cervical lymph nodes, and IL-4, IFN-gamma and IL-13 levels in supernatants of lymph node cells, cultured with or without concanavalin A. Early ventilatory function and airway reactivity increased in all groups that received a dermal application and one or multiple intranasal challenges of TDI. After multiple challenges, lung inflammation was characterized by neutrophils (approximately 15%), and eosinophils (approximately 4%), along with an increase in BAL MIP-2 and TNF-alpha levels. The auricular and cervical lymph node cells of all sensitized mice showed an increase in B cells, Th cells and an increased concentration of in vitro release of IL-4, IFN-gamma and IL-13 after stimulation with concanavalin A. Total serum IgE was elevated in dermally TDI-sensitized mice. This protocol including multiple challenges results in a model that resembles human asthma, indicating that responses found in the model using a single challenge could be a good first indication for the development of asthma.

Allergen-induced formation of F2-isoprostanes in a murine asthma model identifies oxidative stress in acute airway inflammation in vivo

F(2)-isoprostanes have been associated with various forms of oxidant stress. The levels of F(2)-isoprostanes in a murine asthma model were studied both in situ and in vivo and further investigated whether the formation of F(2)-isoprostanes was associated with increased ovalbumin (OVA)-induced airway inflammation after a 17-day (OVA-17) or a 24-day (OVA-24) protocol. Bronchial reactivity was assessed by using a ventilator (FlexiVent). OVA-treated animals had higher lung resistance and lung compliance compared to control groups (P<0.001). 8-Iso-PGF(2)(alpha) levels in bronchoalveolar lavage (BAL) and 8-iso-PGF(2)(alpha) immunoreactivity in lung tissue were analyzed. OVA-17 mice showed a 2.5-fold increased level of 8-iso-PGF(2)(alpha) in BAL compared to PBS-17 mice (P=0.023). Lung tissue from OVA-24 mice had more intense 8-iso-PGF(2)(alpha) staining compared to OVA-17 mice. This study showed an accumulation of F(2)-isoprostanes in acute airway inflammation and a markedly increased tissue damage caused by oxidative stress in an ongoing inflammation.

Different strains of mice present distinct lung tissue mechanics and extracellular matrix composition in a model of chronic allergic asthma

The impact of genetic factors on asthma is well recognized but poorly understood. We tested the hypothesis that different mouse strains present different lung tissue strip mechanics in a model of chronic allergic asthma and that these mechanical differences may be potentially related to changes of extracellular matrix composition and/or contractile elements in lung parenchyma. Oscillatory mechanics were analysed before and after acetylcholine (ACh) in C57BL/10, BALB/c, and A/J mice, subjected or not to ovalbumin sensitization and challenge. In controls, tissue elastance (E) and resistance (R), collagen and elastic fibres' content, and alpha-actin were higher in A/J compared to BALB/c mice, which, in turn, were more elevated than in C57BL/10. A similar response pattern was observed in ovalbumin-challenged animals irrespective of mouse strain. E and R augmented more in ovalbumin-challenged A/J [E: 22%, R: 18%] than C57BL/10 mice [E: 9.4%, R: 11%] after ACh In conclusion, lung parenchyma remodelled differently yielding distinct in vitro mechanics according to mouse strain.

Inducible nitric oxide synthase inhibition attenuates lung tissue responsiveness and remodeling in a model of chronic pulmonary inflammation in guinea pigs

We evaluated the influence of iNOS-derived NO on the mechanics, inflammatory, and remodeling process in peripheral lung parenchyma of guinea pigs with chronic pulmonary allergic inflammation. Animals treated or not with 1400 W were submitted to seven exposures of ovalbumin in increasing doses. Seventy-two hours after the 7th inhalation, lung strips were suspended in a Krebs organ bath, and tissue resistance and elastance measured at baseline and after ovalbumin challenge. The strips were submitted to histopathological measurements. The ovalbumin-exposed animals showed increased maximal responses of resistance and elastance (p<0.05), eosinophils counting (p<0.001), iNOS-positive cells (p<0.001), collagen and elastic fiber deposition (p<0.05), actin density (p<0.05) and 8-iso-PGF2alpha expression (p<0.001) in alveolar septa compared to saline-exposed ones. Ovalbumin-exposed animals treated with 1400 W had a significant reduction in lung functional and histopathological findings (p<0.05). We showed that iNOS-specific inhibition attenuates lung parenchyma constriction, inflammation, and remodeling, suggesting NO-participation in the modulation of the oxidative stress pathway.

Temporal evolution of epithelial, vascular and interstitial lung injury in an experimental model of idiopathic pulmonary fibrosis induced by butyl-hydroxytoluene

This study was undertaken to test whether the structural remodelling of pulmonary parenchyma can be sequentially altered in a model and method that demonstrate the progression of the disease and result in remodelling within the lungs that is typical of idiopathic pulmonary fibrosis. Three groups of mice were studied: (i) animals that received 3-5-di-tert-butyl-4-hydroxytoluene (BHT) and were killed after 2 weeks (early BHT = 9); (ii) animals that received BHT and were killed after 4 weeks (late BHT = 11); (iii) animals that received corn oil solution (control = 10). The mice were placed in a ventilated Plexiglas chamber with a mixture of pure humidified oxygen and compressed air. Lung histological sections underwent haematoxylin-eosin, immunohistochemistry (epithelial, endothelial and immune cells) and specific staining (collagen/elastic fibres) methods for morphometric analysis. When compared with the control group, early BHT and late BHT groups showed significant decrease of type II pneumocytes, lower vascular density in both and higher endothelial activity. CD4 was increased in late BHT compared with early and control groups, while CD8, macrophage and neutrophil cells were more prominent only in early BHT. The collagenous fibre density were significantly higher only in late BHT, whereas elastic fibre content in late BHT was lower than that in control group. We conclude that the BHT experimental model is pathologically very similar to human usual interstitial pneumonia. This feature is important in the identification of animal models of idiopathic pulmonary fibrosis that can accurately reflect the pathogenesis and progression of the human disease.