Alveolar Wall Damage Research Articles

Pulmonary hypertension associated with COPD: a phenotype analysis

BackgroundPulmonary hypertension (PH) associated with chronic obstructive pulmonary disease (COPD; PH-COPD) exhibits diverse phenotypes, challenging therapeutic management. This study aimed to describe the characteristics of COPD patients with distinct phenotypes: end-stage COPD with or without PH; group 1; other COPD patients with mild-to-moderate precapillary PH-COPD; group 2; and COPD patients with a pulmonary vascular phenotype (PVP); group 3.MethodsWe performed a retrospective analysis of COPD patients who underwent right heart catheterization (RHC) from 2015 to 2022.ResultsEighty-one patients were included in group 1, 37 in group 2, and 35 in group 3. The groups differed in clinical, functional, hemodynamic, and imaging characteristics. Group 1 had significantly marked lung hyperinflation with increased total lung capacity and residual volume, a feature not observed in group 3. These results were confirmed by analysis of chest CT scans, which confirmed varying degrees of emphysema: severe in group 1, moderate in group 2, and mild in group 3, with median total emphysema index of 55% (48–62), 32% (16–49), and 16% (3.4–31), respectively, p<0.0001.ConclusionsOur results highlight the broad spectrum of precapillary PH in COPD, from PH associated with end-stage COPD (phenotype/group 1), characterized by predominant alveolar wall damage with severe emphysema, to PVP (phenotype/group 3), mainly due to pulmonary vascular changes. Phenotype/group 2 represents an intermediate state combining features of both. In the current debate on how to distinguish PH-COPD phenotypes, it might be of interest to include quantitative thresholds for emphysema in future diagnostic and management algorithms.

Increased Serum SP-D Level, Neutrophils and Lymphocytes Sputum in Malang Splendid Bird Market Workers

Background: Workers in the bird market have a high risk of exposure in the form of air pollution, pollutant particles including debris / organic dust, loose feathers, insects/ticks, aerosol particles in food, bird excreta (ammonia), various kinds of gram bacteria, fungi and virus. Exposure to particles will stimulate the immune system against harmful pathogens in the form of inflammatory response. An infection or injury will stimulate the secretion of Surfactant protein-D (SP-D) which is a group of collectin (collagen-lectin) with subgroups of the C-type lectin superfamily, together with bovine coglutinin, mannose-binding lectin (MBL), and CL43 protein. This aim of this study was to determine serum SP-D and neutrophil and sputum lymphocyte levels in workers at splendid bird market.Methods: A cross sectional analytic observational study on 35 subjects, analyzed the characteristics of the workers, calculated neutrophil types, lymphocytes on induced sputum and serum SP-D levels using sandwich ELISA.Results: Mean SP-D serum levels in workers in the bird market environment increased (mean SD: 81.39 + 47.656 ng/ml) from normal levels (60 ± 3 ng/ml). There was a significant positive correlation between length of exposure and serum SP-D levels (r: 0.693; p <0.001). There was an average increase in the percentage of neutrophils and sputum lymphocytes (90.71% + 4.04% and 9.17% + 4.42%) compared to normal limit (50.3% + 23.5% and 2.6% + 5.2%).Conclusion: Inhalation exposure in the Bird Market environment can cause an increase in the percentage of neutrophils, sputum lymphocytes and serum SP-D levels in workers that indicate an airway inflammation process, as well as an alleged increase in alveolar wall permeability, damage and regeneration of alveolar epithelial cell type II cells (AEC type II).

Inhibition of Pre-B Cell Colony Enhancing Factor Reduces Lung Injury in Rats Receiving Cardiopulmonary Bypass.

ObjectivePre-B cell colony enhancing factor (PBEF) is an important proinflammatory cytokine involved in acute lung injury. However, whether PBEF participates in lung injury caused by cardiopulmonary bypass (CPB) is still unknown. This study aimed to investigate the effects of silencing PBEF on lung injury and the sodium and water transport system in rats receiving CPB.MethodsMorphological changes in lung tissues were evaluated using hematoxylin and eosin (H&E) staining. PBEF was detected using immunohistochemistry. The sodium and water transport system-related proteins and cellular signaling pathways were detected by Western blotting.ResultsRats receiving CPB (model group) had more severe alveolar wall damage and higher expression of PBEF in free form than the control rats. Western blotting showed that the expression of PBEF, surfactant protein D (SP), aquaporin (AQP) 1, AQP5, and epithelial sodium channel (ENaC) was significantly higher in the lung tissue of CPB rats than control rats. By contrast, adenovirus-encoding sh-PBEF significantly reduced the expression of PBEF, SP, AQP1, AQP5, and ENaC in the lung tissues of rats treated with CPB. The phosphorylation levels of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), protein kinase B (AKT), and p38 mitogen-activated protein kinase (MAPK) were significantly increased in the lung tissue of rats that received CPB, and were downregulated by adenovirus-encoding sh-PBEF.ConclusionAdenovirus-encoding sh-PBEF could reduce lung injury and repair the sodium–water transport system in rats receiving CPB, likely through reducing MAPK, ERK1/2, and Akt signaling pathways.

Emodin inhibiting neutrophil elastase-induced epithelial-mesenchymal transition through Notch1 signalling in alveolar epithelial cells.

The transition of alveolar type II epithelial cells into fibroblasts has been reported to cause and/or aggravate pulmonary fibrosis (PF), which is characterized by fibroblast proliferation, an enhanced production and accumulation of ECM (extracellular matrix), alveolar wall damage and functional capillary unit loss. Traditional Chinese medicine Emodin has been reported to inhibit TGF‐β‐induced epithelial‐mesenchymal transition (EMT) in alveolar epithelial cells through Notch signalling. In the present study, neutrophil elastase (NE, also known as ELA2) treatment promoted EMT, Notch1 cleavage (NICD/Notch1 ratio increase) and NICD nuclear translocation in RLE‐6TN cells and A549 cells. The promotive roles of NE treatment in these events were significantly reversed by Notch1 knockdown. Traditional Chinese medicine Emodin treatment remarkably inhibited the enzyme activity of NE, suppressed EMT, Notch1 cleavage and NICD nuclear translocation within RLE‐6TN and A549 cells, while NE treatment significantly reversed the effects of Emodin. Moreover, in RLE‐6TN, the effects of NE on EMT, Notch1 cleavage and NICD nuclear translocation were remarkably attenuated by Emodin treatment and more attenuated by the combination of Emodin and neutrophil elastase inhibitor Sivelestat or notch signal pathway inhibitor DAPT. In conclusion, we revealed the involvement of NE‐induced Notch1 cleavage in the functions of Emodin suppressing NE‐caused EMT in RLE‐6TN cells and A549 cells. This novel mechanism of Emodin inhibiting EMT might extend the application of Emodin in PF treatment.

Free Desmosine is a Sensitive Marker of Smoke-Induced Emphysema.

While the elastin-specific crosslinks, desmosine and isodesmosine (DID), are increased in blood, urine, and sputum of patients with clinically documented pulmonary emphysema, the usefulness of DID in detecting early lung injury remains untested. To this end, our laboratory has measured DID in a hamster model of smoke-induced emphysema, involving only minimal alveolar wall damage. Animals were either treated with cigarette smoke for 2h/day, 5 days/week, or exposed only to room air (controls) for a period of 3months. DID levels in bronchoalveolar lavage fluid (BALF) and whole lungs were determined at monthly intervals, using liquid chromatography and tandem mass spectrometry. Lung surface area was also determined, as a measure of airspace enlargement. The portion of BALF DID not bound to peptides (free DID) was significantly higher in smoke-exposed animals at 2months (9.2 vs 4.4pg/mg protein; p < 0.05), whereas total BALF DID showed no significant increases over the course of the study, and total lung DID remained unchanged. There was a mild, but significant, loss of lung surface area in the smoke-exposed group at 2months (28.8% vs 25.2%, p < 0.05), which showed no further progression, consistent with the return of free DID to control levels at 3months. These findings support the hypothesis that free DID are sensitive indicators of smoke-induced lung injury. Measurement of free DID in smokers with minimally decreased lung mass may help determine the utility of this parameter as a test for incipient pulmonary emphysema.

Use of cilomilast-loaded phosphatiosomes to suppress neutrophilic inflammation for attenuating acute lung injury: the effect of nanovesicular surface charge

BackgroundCilomilast is a phosphodiesterase 4 (PDE4) inhibitor for treating inflammatory lung diseases. This agent has a narrow therapeutic index with significant adverse effects on the nervous system. This study was conducted to entrap cilomilast into PEGylated phosphatidylcholine-rich niosomes (phosphatiosomes) to improve pulmonary delivery via the strong affinity to pulmonary surfactant film. Neutrophils were used as a cell model to test the anti-inflammatory activity of phosphatiosomes. In an in vivo approach, mice were given lipopolysaccharide to produce acute lung injury. The surface charge in phosphatiosomes that influenced the anti-inflammatory potency is discussed in this study.ResultsThe average diameter of the phosphatiosomes was about 100 nm. The zeta potential of anionic and cationic nanovesicles was − 35 and 32 mV, respectively. Cilomilast in both its free and nanocapsulated forms inhibited superoxide anion production but not elastase release in activated neutrophils. Cationic phosphatiosomes mitigated calcium mobilization far more effectively than the free drug. In vivo biodistribution evaluated by organ imaging demonstrated a 2-fold ameliorated lung uptake after dye encapsulation into the phosphatiosomes. The lung/brain distribution ratio increased from 3 to 11 after nanocarrier loading. The intravenous nanocarriers deactivated the neutrophils in ALI, resulting in the elimination of hemorrhage and alveolar wall damage. Only cationic phosphatiosomes could significantly suppress IL-1β and TNF-α in the inflamed lung tissue.ConclusionsThese results suggest that phosphatiosomes should further be investigated as a potential nanocarrier for the treatment of pulmonary inflammation.

MTOR Modulates Lymphocyte Differentiation through T-bet and Eomesodermin in Response to Invasive Pulmonary Aspergillosis in Rats.

Background:Aspergillosis infection is common in the patients with insufficient immunity. The role of mammalian target of rapamycin (mTOR), T-box expressed in T-cells (T-bet), and eomesodermin (EOMES) in mediating T lymphocytes differentiation in response to Aspergillus fumigatus infection in immunocompromised rats was investigated in this study.Methods:Invasive pulmonary aspergillosis (IPA) of immunosuppressive twenty male rats were established and sacrificed at 24 h (n = 5), 48 h (n = 5), 72 h (n = 5), and 96 h (n = 5) after A. fumigatus infection. In addition, control (n = 5), cyclophosphamide (CTX) (n = 5), and aspergillosis (n = 5) group were also established the tissues and pathology of lung tissue was examined by hematoxylin and eosin staining. CD8+ T-cells was sorted by flow cytometry. Serum mTOR, S6K, T-bet, and EOMES were quantified by enzyme-linked immunosorbent assay.Results:Histology of lung tissue indicated severe lung tissue injury including infiltration of inflammatory cells, alveolar wall damage or degradation, blood congestion, and hemorrhage in the CTX, IPA, and CTX + IPA rats. Hyphae were seen in the IPA, and CTX + IPA groups. The proportion of CD8+ T-cells was significantly increased in the animals of CTX + IPA. Memory CD8+ T-cells was significantly increased in early stage (24 h and 48 h, P < 0.001), but decreased in the late phase of fungal infection (72 h and 96 h) in the animals of CTX + IPA. In addition, at early stage of fungal infection (24 h and 48 h), serum mTOR (P < 0.001), S6K (P < 0.001), and T-bet (P < 0.05) was significantly higher, while EOMES was significantly lower (P < 0.001), in CTX + IPA group than that in control, CTX alone or IPA alone group. Conversely, serum mTOR, S6K, T-bet, and EOMES showed opposite changed in the late stage (72 h and 96 h). Pearson's correlation analysis indicated that mTOR and S6K were significantly correlated with T-bet (r = 0.901 and 0.91, respectively, P < 0.001), but negatively and significantly correlated with EOMES (r = −0.758 and −0.751, respectively, P < 0.001).Conclusions:mTOR may regulate transcription factors of EOMES and T-bet, and by which mechanism, it may modulate lymphocytes differentiation in animals with immune suppression and fungal infection.

Does lysozyme play a role in the pathogenesis of COPD?

Elastic fiber injury is an important process in the pathogenesis of chronic obstructive pulmonary disease (COPD), particularly with regard to the development of pulmonary emphysema. Damage to these fibers results in uneven distribution of mechanical forces in the lung, leading to dilatation and rupture of alveolar walls. While the role of various enzymes and oxidants in this process has been well-documented, we propose that a previously unsuspected agent, lysozyme, may contribute significantly to the changes in elastic fibers observed in this disease. Studies from our laboratory have previously shown that lysozyme preferentially binds to elastic fibers in human emphysematous lungs. On the basis of this finding, it is hypothesized that the attachment of lysozyme to these fibers enhances their susceptibility to injury, and further impairs the transfer of mechanical forces in the lung, leading to increased alveolar wall damage and enhanced progression of COPD. The hypothesized effects of lysozyme are predicated on its interaction with hyaluronan (HA), a long-chain polysaccharide that is found in close proximity to elastic fibers. By preventing the binding of HA to elastic fibers in COPD, lysozyme may interfere with the protective effect of this polysaccharide against enzymes and oxidants that degrade these fibers. Furthermore, the loss of the hydrating effect of HA on these fibers may impair their elastic properties, greatly increasing the probability of their fragmentation in response to mechanical forces. The proposed hypothesis may explain why the content of HA is significantly lower in the lungs of COPD patients. It may also contribute to the design of clinical trials involving the use of exogenously administered HA as a potential treatment for COPD.

Impact of the cardiac arrest mode on cardiac death donor lungs

BackgroundDonation after cardiac death (DCD) organs could alleviate the shortage of donor lungs. This study aimed to assess the influence on lung injuries of the way in which cardiac arrest was induced and to investigate the mechanisms leading to any differences. Materials and methodsMale rats were allocated into three groups as follows: sham (no warm ischemia), ventricular fibrillation (VF), and asphyxia group. Cardiac arrest was induced by either VF by way of a fibrillator or asphyxia caused by withdrawal of ventilation, which reflected uncontrolled and controlled DCD situations, respectively. The impact on lung flushing after 60 min of warm ischemia time was evaluated (n = 5, in each group). The physiological functions of the lungs in an isolated lung perfusion circuit were also evaluated with warm ischemia time prolonged to 150 min (n = 8, in each group). Messenger RNA expression levels of surfactant proteins (SPs) and inflammatory cytokines, pathologic findings, and high-energy phosphates of the lung tissues were investigated. ResultsIn the asphyxia group, flushing and physiological functions in the isolated lung perfusion circuit were the most severely affected. Reverse transcription-polymerase chain reaction and pathologic findings revealed depletion of surfactant protein (SP)-C in lung tissues of the asphyxia group after reperfusion. The VF group was characteristic with elevated pulmonary vascular resistance. ConclusionsLung injuries were mainly attributed to alveolar wall damage and depletion of SP in the asphyxia group, and perivascular area prominent edema in the VF group. DCD donor lungs were affected differently by the way in which cardiac arrest was induced.

The Significance and Mechanism of Propofol on Treatment of Ischemia Reperfusion Induced Lung Injury in Rats

This study is aimed to investigate the efficacy and underlying the mechanism of propofol in treatment of ischemia reperfusion (IR)-induced lung injury in rats, providing a novel insight of therapeutic strategy for IR-induced lung injury. 120 healthy SD rats were selected and randomly divided into sham operation group, IR group, and propofol group (40 rats per group). Bronchoalveolar lavage fluid (BALF) protein content, serum protein content, lung permeability index, lung water content rate, methane dicarboxylic aldehyde (MDA) in lung tissue, superoxide dismutase (SOD), nitric oxide (NO), endothelin (ET-1), toll-like receptor 4 (TLR4), nuclear factor (NF-κB), and tumor necrosis factor-α (TNF-α) were examined and compared among different groups to evaluate the therapeutical effects of propofol on IR-induced lung injury and analyze the mechanism. In sham operation group, neither change in lung tissue nor pulmonary interstitial edema or alveolar wall damage was found under microscope; in IR group, marked pulmonary interstitial edema and alveolar wall damage complicated with inflammatory cell infiltration and hemorrhage were found; in propofol group, alveolar wall widening was observed, however, hemorrhage in alveolar cavity, inflammatory infiltration and tissue damage were less significant than in IR group. At 3 h after reperfusion, BALF protein content, lung permeability index, and lung water content rate were all significantly increased in IR group and propofol group, while the serum protein content was significantly lower than sham operation group (p < 0.05). Moreover, we found that the change of above parameters in propofol group was less significant than in IR group (p < 0.05). No statistically significant difference was found in ET-1 levels in different groups (p > 0.05). In contrast, MDA and NO in IR group and propofol group were significantly increased, while SOD activity was significantly decreased (p < 0.05). Furthermore, the change of above parameters in propofol group was less significant than in IR group (p < 0.05). In addition, mRNAs of TLR4, NF-κB, and TNF-α were significantly increased in IR group and propofol group (p < 0.05) with more significant change in IR group compared with propofol group (p < 0.05). Propofol has protective effects against IR-induced lung injury by improving activity of oxygen radical and restoring NO/ET-1 dynamic balance. Besides, regulation of TLR4, NF-κB, and TNF-α by propofol also play important role in alleviating IR-induced lung injury.

Budesonide/formoterol combination in COPD: a US perspective.

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease of the lung caused primarily by exposure to cigarette smoke. Clinically, it presents with progressive cough, sputum production, dyspnea, reduced exercise capacity, and diminished quality of life. Physiologically, it is characterized by the presence of partially reversible expiratory airflow limitation and hyperinflation. Pathologically, COPD is a multicomponent disease characterized by bronchial submucosal mucous gland hypertrophy, bronchiolar mucosal hyperplasia, increased luminal inflammatory mucus, airway wall inflammation and scarring, and alveolar wall damage and destruction. Management of COPD involves both pharmacological and nonpharmacological approaches. Bronchodilators and inhaled corticosteroids are recommended medications for management of COPD especially in more severe disease. Combination therapies containing these medications are now available for the chronic management of stable COPD. The US Food and Drug Administration, recently, approved the combination of budesonide/formoterol (160/4.5 μg; Symbicort™, AstraZeneca, Sweden) delivered via a pressurized meter dose inhaler for maintenance management of stable COPD. The combination also is delivered via dry powder inhaler (Symbicort™ and Turbuhaler™, AstraZeneca, Sweden) but is not approved for use in the United States. In this review, we evaluate available data of the efficacy and safety of this combination in patients with COPD.

Inflammatory Cells and Chronic Obstructive Pulmonary Disease

A major contributory factor to the development of chronic obstructive pulmonary disease (COPD) is the inflammatory response to cigarette smoke. However, when those with COPD stop smoking, a continuous cycle of inflammation can lead to continued decline in lung function. Understanding the role of inflammatory cells in COPD is difficult because it is a mixture of diseases--bronchitis, small airways disease and emphysema--that exhibit different patterns of inflammation and different pathology. Neutrophils and macrophages have been implicated in this process; they release proteolytic enzymes and generate oxidants, which cause tissue damage, as well as cytokines and chemokines, which can potentiate inflammation and trigger an immune response. Analysis of sputum and bronchoalveolar lavage fluid shows increases in both neutrophils and macrophages in respiratory secretions in COPD subjects; neutrophils are the predominant cell in the conducting airways, whereas macrophages are the major cell in secretions from the small airways and parenchyma. Airway tissue neutrophils are increased in the large and small airways during infection and exacerbations, whilst parenchymal neutrophil numbers are inversely related to alveolar wall destruction, suggesting that they are not involved in the progression of emphysema. Macrophages are increased throughout the respiratory tract airway lumen and epithelium in COPD and are positively related to severity of disease, airway obstruction and degree of alveolar wall damage in emphysema. Unactivated T-lymphocytes do not linger in lung tissue. Activated (eg due to antigenic stimulus) memory T cells home in to the lung and act as effector cells. CD-8+ T cell differentiation into memory cells is facilitated by CD4+ T cells. Binding of CD-8+ T cells to collagen stimulates proliferation and mediator production which may contribute to the inflammatory response. CD8+ cytotoxic/suppressor T cells release cytotoxic perforins and granzyme B which cause cell death and apoptosis, a feature of emphysema. Lung secretions contain only a small percentage of T cells; most T-lymphocytes reside in the subepithelial and smooth muscle region of the tissue. During COPD, there is either an increase in the CD8+/CD4+ ratio of T cells, or an increase in the in total numbers of both CD8+ and CD4+ T cells, in the tissue. Smoking status, smoking history, degree of airway obstruction and emphysema are all related to increased CD8+ cells and/or CD8+/CD4+ ratio. During severe emphysema requiring lung volume reduction surgery, there is a considerable increase in macrophages, neutrophils, eosinophils, CD4+ and CD8+ T cells which relates to the severity of the disease. Interestingly, the marked increase in luminal CD8+ cells results in an increased ratio of CD8+/CD4+ T cells that is not seen in the parenchymal tissue. The florid inflammation observed in severe emphysema is suggested to be related to latent viral infection.

Acute Interstitial Pneumonia in Feedlot Cattle

Acute interstitial pneumonia (AIP) is a descriptive term for a specific histopathological pattern, including hyaline membrane formation, and proliferation of type II alveolar epithelial cells.6,18 Other lesions often identified are interlobular edema, hemorrhage and vascular congestion. The condition occurs secondary to alveolar wall damage resulting in transudation of relatively acellular, and fibrinogen-rich fluid into alveolar spaces and terminal airways.

Cigarette smoking causes sequestration of polymorphonuclear leukocytes released from the bone marrow in lung microvessels.

Studies from our laboratory have shown that chronic cigarette smoke exposure causes a neutrophilia associated with a shortening of the mean transit time of polymorphonuclear leukocytes (PMN) though the postmitotic pool of the marrow. The present study was designed to test the hypothesis that PMN newly released from bone marrow by smoke exposure preferentially sequestered in pulmonary microvessels. The thymidine analogue 5'-bromo-2'-deoxyuridine (BrdU) was used to label dividing PMN in the marrow of rabbits; their appearance in the circulation was measured using immunocytochemistry, and their sequestration in lung tissue was determined using standard morphometric techniques. Animals exposed to 11 d of cigarette smoke (n = 6) compared with sham-exposed control animals (n = 4) showed no increase in circulating PMN counts but showed an increase in both the percentage of band cells (smoking, 9.8 +/- 1.1% versus control, 5.5 +/- 0.9%; P < 0.05) and BrdU-labeled PMN (PMNBrdU) in the circulation (smoking, 10.8 +/- 0.6% versus control, 7.5 +/- 0.3%; P < 0.05). There were more PMN sequestered in the lungs of smoke-exposed animals (51.7 +/- 3.4 x 10(7)/ml tissue) than in those of control animals (25.1 +/- 1.8 x 10(7)/ ml tissue) (P < 0.05) and a higher percentage of these cells were PMNBrdU (smoking, 16.9 +/- 2. 3% versus control, 9.6 +/- 0.4%; P < 0.05). The percentage of PMNBrdU in the gravity-independent regions (11.7 +/- 1.9%) of the lung was higher than gravity-dependent regions (7.8 +/- 1.8%) in the smoke-exposure group (P < 0.05). Transmission electron microscopy showed pulmonary capillary endothelial damage with adherent PMN in the smoke-exposure group. We conclude that younger PMN released from the bone marrow by cigarette smoking preferentially sequestered in pulmonary microvessels and speculate that these PMN may contribute to the alveolar wall damage associated with smoke-induced lung emphysema.

Collagenase and gelatinase activities in bronchoalveolar lavage fluids during bleomycin-induced lung injury.

Basement membrane degradation can be indicative of tissue injury, but the process may also release matrix-bound cytokines to stimulate cell regeneration. To investigate this process, acute lung injury was induced in rats by intratracheal bleomycin and animals were killed from 3 days to 8 weeks later. The lungs were lavaged with saline to collect bronchoalveolar lavage (BAL) fluid and cell proliferation was assessed by pulse incorporation of tritiated thymidine. Bleomycin induced rapid inflammation with increased cell numbers and protein levels in BAL. Collagen degradation products were also increased in BAL fluid from 3 days to 4 weeks. Incubating samples of BAL fluid with radiolabelled collagens I and IV showed that high levels of activity, particularly for the degradation of type IV collagen, were present as early as 3 days post-bleomycin and persisted over the 8-week period. Zymograms demonstrated the highest level of gelatinase A (MMP-2) activity in BAL fluid in the first 2 weeks after bleomycin. Coincident with peak basement membrane degradative activity was the onset of a phase of epithelial cell proliferation, as measured by labelled nuclei in autoradiographs. The results show that enzymes capable of degrading the alveolar basement membrane are secreted early in the lung injury phase and that their presence in BAL fluid can be used as a measure of alveolar wall damage. It is possible that this enzyme action may release bound cytokines from the basement membrane, since maximal gelatinase activity correlates with alveolar epithelial cell proliferation.

Chronic Inhalation Toxicity and Carcinogenicity Study of Respirable Polymeric Methylene Diphenyl Diisocyanate (Polymeric MDI) Aerosol in Rats

Chronic Inhalation Toxicity and Carcinogenicity Study of Respirable Polymeric Methylene Diphenyl Diisocyanate (Polymeric MDI) Aerosol in Rats. Reuzel, P. G. J., Arts, J. H. E., Lomax, L. G., Kuijpers, M. H. M., Kuper, C. F., Gembardt, C., Feron, V. J., and Löser, E. (1994). Fundam. Appl. Toxicol. 22, 195-210.Four groups of 60 Wistar rats of each sex were exposed by inhalation to 0, 0.2, 1.0, or 6.0 mg/m3 respirable polymeric methylene diphenyl diisocyanate (polymeric MDI) aerosol (93.5% < 4.2 μm) for 6 hr a day, 5 days a week for up to 24 months. In addition, satellite groups of 10 rats/sex/group received the same treatment for 12 months. There was no adverse effect on general health, survival, body weight, or hematological or clinical chemistry parameters. Lung weights were increased in both males and females exposed to 6.0 mg polymeric MDI/m3 for 12 or 24 months. Gross examination at autopsy of males exposed to 6.0 mg polymeric MDI/m3 for 24 months revealed an increased incidence of spotted and discolored lungs. Increased incidences of degeneration and basal cell hyperplasia of the nasal olfactory epithelium, often accompanied by hyperplasia of Bowman's glands, were found in the 1.0 and 6.0 mg/m3 groups. Light and electron microscopic studies of the lungs revealed accumulations of alveolar macrophages containing polymeric MDI-associated refractile yellowish material at the level of the alveolar duct in all exposed groups. Alveolar duct epithelialization as well as fibrosis of tissues surrounding the macrophage accumulations occurred at the 1.0 and 6.0 mg/m3 exposure levels. In addition, increased incidences of calcareous deposits and localized alveolar bronchiolization were seen in the 6.0 mg/m3 group. Moreover, eight pulmonary adenomas (six in males and two in females) and one pulmonary adenocarcinoma (in a male) were observed in the 6.0 mg/m3 exposure group. The time sequence of the spectrum of pulmonary changes indicates that recurrent alveolar wall damage by polymeric MDI and/or polymeric MDI-containing alveolar macrophages leads to alveolar bronchiolization and ultimately to bronchioloalveolar tumors. No lung tumors were found in the lower concentration groups and in the control group. The incidence and distribution of other types of tumors were not influenced by polymeric MDI. It was concluded that in the present study, the "no-observed-adverse-effect level" of polymeric MDI was 0.2 mg/m3, and that chronic exposure to polymeric MDI at a level of 6.0 mg/m3 was related to the occurrence of pulmonary tumors. It was also concluded that exposure to polymeric MDI at concentrations not leading to recurrent lung tissue damage will not produce pulmonary tumors.

Chronic Inhalation Toxicity and Carcinogenicity Study of Respirable Polymeric Methylene Diphenyl Diisocyanate (Polymeric MDI) Aerosol in Rats

Four groups of 60 Wistar rats of each sex were exposed by inhalation to 0, 0.2, 1.0, or 6.0 mg/m3 respirable polymeric methylene diphenyl diisocyanate (polymeric MDI) aerosol (93.5% < 4.2μm) for 6 hr a day, 5 days a week for up to 24 months. In addition, satellite groups of 10 rats/sex/group received the same treatment for 12 months. There was no adverse effect on general health, survival, body weight, or hematological or clinical chemistry parameters. Lung weights were increased in both males and females exposed to 6.0 mg polymeric MDI/m3 for 12 or 24 months. Gross examination at autopsy of males exposed to 6.0 mg polymeric MDI/m3 for 24 months revealed an increased incidence of spotted and discolored lungs. Increased incidences of degeneration and basal cell hyperplasia of the nasal olfactory epithelium, often accompanied by hyperplasia of Bowman's glands, were found in the 1.0 and 6.0 mg/m3 groups. Light and electron microscopic studies of the lungs revealed accumulations of alveolar macrophages containing polymeric MDI-associated refractile yellowish material at the level of the alveolar duct in all exposed groups. Alveolar duct epithelialization as well as fibrosis of tissues surrounding the macro phage accumulations occurred at the 1.0 and 6.0 mg/m3 exposure levels. In addition, increased incidences of calcareous deposits and localized alveolar bronchiolization were seen in the 6.0 mg/m3 group. Moreover, eight pulmonary adenomas (six in males and two in females) and one pulmonary adenocarcinoma (in a male) were observed in the 6.0 mg/m3 exposure group. The time sequence of the spectrum of pulmonary changes indicates that recurrent alveolar wall damage by polymeric MDI and/or polymeric MDI-containing alveolar macrophages leads to alveolar bronchiolization and ultimately to bronchioloalveolar tumors. No lung tumors were found in the lower concentration groups and in the control group. The incidence and distribution of other types of tumors were not influenced by polymeric MDI. It was concluded that in the present study, the “no-observed-adverse-effect level” of polymeric MDI was 0.2 mg/m3 and that chronic exposure to polymeric MDI at a level of 6.0 mg/m3 was related to the occurrence of pulmonary tumors. It was also concluded that exposure to polymeric MDI at concentrations not leading to recurrent lung tissue damage will not produce pulmonary tumors.

Adenovirus-mediated transfer of the CFTR gene to lung of nonhuman primates: toxicity study.

In preparation for human trials of gene therapy for cystic fibrosis (CF), we performed a preclinical study of gene transfer into the lungs of baboons. Recombinant adenovirus vectors containing expression cassettes for human cystic fibrosis transmembrane conductance regulator (CFTR) and Escherichia coli beta-galactosidase (lacZ) were instilled through a bronchoscope into limited regions of lung in 14 baboons. A detailed accounting of the extent, distribution, and duration of gene expression is contained in a companion article (Engelhardt et al., 1993b). In this article, we report the results of toxicity studies in which clinical laboratory tests, chest radiographs, and necropsy studies were used to detect adverse effects. The only adverse effect noted was a mononuclear cell inflammatory response within the alveolar compartment of animals receiving doses of virus that were required to induce detectable gene expression. Minimal inflammation was seen at 10(7) and 10(8) pfu/ml, but at 10(9) and more prominently at 10(10) pfu/ml, a perivascular lymphocytic and histiocytic infiltrate was seen. The intensity of inflammation increased between 4 and 21 days. At its greatest intensity, there was diffuse alveolar wall damage with intra-alveolar edema. Airways were relatively spared, despite the intensity of alveolar inflammation. Clinical tests did not accurately reflect the presence of lung inflammation, with the exception of chest radiographs which revealed alveolar infiltrates, but only in regions of lung having the greatest intensity inflammation. We conclude that adenovirus-mediated gene transfer into the lungs of baboons is associated with development of alveolar inflammation at high doses of virus.

Experimental pulmonary infarction in a pig model.

The authors sought to develop a reliable animal model for experimental pulmonary infarction, to evaluate it with radiologic-pathologic correlation, and to determine the use of high-resolution computed tomography (HRCT) in monitoring parenchymal lung damage due to infarction. Selective left lower lobe pulmonary artery occlusion was performed in seven Yorkshire pigs with transcatheter silicone elastomer injection. After occlusion, 99m technetium (99mTc) macroaggregated albumin perfusion lung scans and sequential in vivo HRCT lung scans were obtained from days 0 to 46. The in vivo radiologic findings were correlated with specimen radiography, specimen HRCT, and histologic findings. A complete and permanent arterial occlusion was achieved, involving up to three orders of branching distal to the catheter. An anatomically defined perfusion defect was seen on 99mTc lung scans corresponding to the occluded area. HRCT changes consisted of confluent densities progressing to mixed alveolar and interstitial opacities within the first week after embolization. In the follow-up period, marked parenchymal clearing was observed. In all cases after pulmonary artery occlusion, the histologic findings were characteristic of pulmonary infarction and demonstrated alveolar edema, hemorrhage, limited alveolar wall damage, and septal thickening followed by residual fibrosis. Using this model, it is feasible to produce pulmonary infarction in the pig which may potentially be useful to study the pathophysiologic and radiologic changes of pulmonary infarction.

The beige mouse: role of neutrophil elastase in the development of pulmonary emphysema.

Mutant beige mice and normal C57 black mice were given endotoxin intratracheally (IT) once a week for 10 weeks. The objective was to establish whether repeated recruitment of neutrophils to the lung, at levels that induced lung injury to normal mice, would be ineffective in producing lung lesions in neutrophil elastase-deficient beige mice. Endotoxin (25 mg) given IT causes a rapid influx of neutrophils into the lungs of both the C57 black and beige mice, reaching a maximum after 18 h and remaining elevated for at least another 30 h. After 10 weeks of endotoxin instillation the normal C57 black mouse lungs showed evidence of lung injury. There were histological signs of alveolar wall damage, and the mean linear intercepts (Lm) were increased 30% in the endotoxin-treated group. The specific compliance of the lungs from the endotoxin-treated mice was slightly increased. Beige mice, on the other hand, showed no histological or morphological evidence that the neutrophil influx produced lung injury. There was, however, a notable difference in the histological appearance of the control beige lungs compared to control C57 blacks. Beige lungs appeared normal at birth but apparently do not undergo normal alveolarization during neonatal development. Adult lungs have fewer alveoli with smooth terminal air ducts lacking the normal complement of alveolar struts. There was not indication of copper deficiency or problems in elastin synthesis or structure in the beige mice. The results of these studies support a preeminent role for elastase in neutrophil-induced lung lesions.