Airspace Cells Research Articles

Analysis of recurrence in lung adenocarcinoma with spread through air spaces

ObjectivesSpread through air spaces is defined as tumor cells in air spaces away from the edge of tumor in lung carcinoma. It is associated with higher locoregional recurrence and lower survival in lung adenocarcinoma. The features of spread through air spaces portending worse outcomes are still under investigation. We reviewed our lung cancer experience to define potential factors related to spread through air spaces that influence recurrence and survival. MethodsBetween January 2010 and December 2017, we identified 968 patients who underwent resection for T1-3N0M0 lung adenocarcinoma. Of these, histologic examination was possible in 787 patients. We examined the presence of spread through air spaces, spread through air spaces characteristics (micropapillary, solid nest, or single cell), average density (number per slide), and farthest distance from tumor at which spread through air spaces was detected, or maximal spread distance. Overall survival and recurrence-free survival were estimated using Kaplan–Meier curves, and differences between spread through air spaces positive versus spread through air spaces negative groups were assessed using the log-rank test. ResultsSpread through air spaces was present in 389 of 787 of the reviewed cases (49.4%). Overall survival and recurrence-free survival were significantly lower in the spread through air spaces positive group over 10 years (P < .0001). The incidences of locoregional and distant recurrence were nearly doubled over 10 years in the spread through air spaces positive group compared with the spread through air spaces negative group (P = .002 and <.0001, respectively). In a multivariable Cox regression model adjusted for spread through air spaces characteristics, distance, and tumor size, lobar resection did not confer survival advantage in patients with spread through air spaces (hazard ratio of sublobar resection with respect to lobar resection, 1.44; 95% confidence interval, 0.98-2.11; P = .067). In the spread through air spaces positive group, spread through air spaces density was 2.7 ± 1.4 clusters per slide and the maximal spread distance was 2.2 ± 1.7 mm from the tumor edge. There was no observed correlation between spread through air spaces density or maximal spread distance and overall survival or recurrence. ConclusionsWe show increased distant recurrence in spread through air spaces positive lung adenocarcinoma. Quantifiable measures of spread through air spaces do not appear to correlate with recurrence or survival metrics.

Air-Inflation of Murine Lungs with Vascular Perfusion-Fixation.

Lung histology is often used to investigate the contributions provided by airspace cells during lung homeostasis and disease pathogenesis. However, commonly used instillation-based fixation methods can displace airspace cells and mucus into terminal airways and can alter tissue morphology. In comparison, vascular perfusion-fixation techniques are superior at preserving the location and morphology of cells within airspaces and the mucosal lining. However, if positive airway pressure is not simultaneously applied, regions of the lungs may collapse and capillaries may bulge into the alveolar spaces, leading to distortion of the lung anatomy. Herein, we describe an inexpensive method for air-inflation during vascular perfusion-fixation to preserve the morphology and location of airway and alveolar cells and interstitium in murine lungs for downstream histologic studies. Constant air pressure is delivered to the lungs via the trachea from a sealed, air-filled chamber that maintains pressure via an adjustable liquid column while fixative is perfused through the right ventricle.

Five simple reasons to discard DIP, or why we should stop calling dolphins big fish

The aim of this review is to explain why the term ‘desquamative interstitial pneumonia’ (DIP) should be discarded and replaced with modern terminology. Reason 1: DIP is a misnomer. Within...

Spread through air spaces (STAS) is a predictor of poor outcome in atypical carcinoids of the lung.

Spread through air spaces (STAS) have been recently recognized as a prognostic factor for adenocarcinoma and squamous cell carcinoma of the lung. Pulmonary neuroendocrine neoplasms (NENs) include tumors with different morphology and a heterogeneous clinical behavior. Among atypical carcinoids (ACs), new prognostic factors able to refine prognosis are needed. In the present study, a retrospective series of 91 surgically resected ACs was investigated, in parallel with 191 control cases of typical carcinoids (TCs) and of high-grade small- and large-cell neuroendocrine carcinomas, to assess the presence and potential prognostic role of STAS. STAS was defined by the presence of neoplastic nests or single cells in air spaces beyond the tumor edge. Clinicopathological parameters and survival were correlated by univariate and multivariate analyses. STAS was identified in 48% of ACs (44/91) compared to 20.5% of TCs and 71-88% of high-grade large- and small-cell carcinomas in the control group. In the carcinoid group, presence of STAS was significantly correlated with unfavorable parameters, such as high tumor stage, positive nodal status, high Ki-67 index, presence of angioinvasion, and with adverse disease outcome, shorter overall survival, and time to progression. In conclusion, the presence of STAS is an additional relevant adverse prognostic factor in pulmonary AC that currently has the most unpredictable outcome and the most controversial treatment strategy.

Estradiol and progesterone influence on influenza infection and immune response in a mouse model.

Influenza infection severity may be mediated by estradiol and/or progesterone. An exploratory study was designed to evaluate 17-β-estradiol and progesterone on influenza infection and examine immune-mediated response in a mouse model. Inoculation with placebo or mouse-adapted H1N1 influenza virus occurred. Treatment groups included 17-β-estradiol, progesterone, ovariectomy, and pregnancy. Mice were assessed for morbidity and mortality. Toll-like receptor gene studies and airspace cell differentials were performed. Onset of morbidity was earlier and morbidity duration greater for progesterone. Absence of morbidity/mortality and overall survival was greater for 17-β-estradiol. Airspace cell differentials suggest improved immune cell recruitment for 17-β-estradiol. Pregnant mouse data demonstrate significant mortality during the period of increased progesterone. Select immune cell markers demonstrate patterns of regulation that may promote proper immune response to influenza infection for 17-β-estradiol. Estradiol may play a protective and progesterone a detrimental role in the pathophysiology of influenza infection.

Linking Microscopic Spatial Patterns of Tissue Destruction in Emphysema to Macroscopic Decline in Stiffness Using a 3D Computational Model

Pulmonary emphysema is a connective tissue disease characterized by the progressive destruction of alveolar walls leading to airspace enlargement and decreased elastic recoil of the lung. However, the relationship between microscopic tissue structure and decline in stiffness of the lung is not well understood. In this study, we developed a 3D computational model of lung tissue in which a pre-strained cuboidal block of tissue was represented by a tessellation of space filling polyhedra, with each polyhedral unit-cell representing an alveolus. Destruction of alveolar walls was mimicked by eliminating faces that separate two polyhedral either randomly or in a spatially correlated manner, in which the highest force bearing walls were removed at each step. Simulations were carried out to establish a link between the geometries that emerged and the rate of decline in bulk modulus of the tissue block. The spatially correlated process set up by the force-based destruction lead to a significantly faster rate of decline in bulk modulus accompanied by highly heterogeneous structures than the random destruction pattern. Using the Karhunen-Loève transformation, an estimator of the change in bulk modulus from the first four moments of airspace cell volumes was setup. Simulations were then obtained for tissue destruction with different idealized alveolar geometry, levels of pre-strain, linear and nonlinear elasticity assumptions for alveolar walls and also mixed destruction patterns where both random and force-based destruction occurs simultaneously. In all these cases, the change in bulk modulus from cell volumes was accurately estimated. We conclude that microscopic structural changes in emphysema and the associated decline in tissue stiffness are linked by the spatial pattern of the destruction process.

Persistence of abnormal bronchoalveolar lavage findings after cyclophosphamide treatment in scleroderma patients with interstitial lung disease

Bronchoalveolar lavage (BAL) is a procedure for sampling the terminal airspace cell population to diagnose alveolitis, a condition that predicts changes in lung function in scleroderma patients. Cyclophosphamide (CYC) stabilizes the progression of lung disease in some, but not all, patients with active alveolitis. However, it is unknown whether the BAL fluid cell count obtained after CYC treatment of alveolitis predicts long-term lung function outcomes and can therefore be used to assist in therapeutic decision-making. The purpose of this study was to determine whether CYC therapy for active lung disease alters BAL fluid neutrophil and eosinophil counts and whether the persistence of abnormal BAL findings after CYC therapy predicts a decline in lung function in patients with scleroderma and interstitial lung disease (ILD). We systematically reviewed the records of scleroderma patients who had active ILD, as evidenced by neutrophilia or eosinophilia on BAL fluid analysis before CYC therapy and on repeat analysis after completion of CYC. Pulmonary function tests (PFTs) were performed before initiation of therapy, at completion of therapy, and during long-term followup (mean +/- SD 3.6 +/- 1.94 years). Of the 25 study patients, in only 6 did the BAL fluid cell counts normalize after CYC therapy. No significant differences were observed between the proportions of patients who had a > or =10% decline in the % predicted DLCO or FVC on the second set of PFTs and had abnormal findings on followup BAL fluid analysis. During long-term followup, patients with persistent alveolitis had a decline in lung function (mean +/- SD change in % predicted FVC -0.6 +/- 10.8 liters and mean +/- SD change in % predicted DLCO -4.7 +/- 21.43 ml/minute/mm Hg), but their lung function did not significantly differ from that in patients whose BAL fluid cell counts had normalized (P = 0.70 and P = 0.62, respectively). Persistently abnormal results on BAL fluid analysis following CYC treatment is a common finding and does not predict a subsequent decline in lung function.

The long‐term effects of perinatal glucocorticoid exposure on the host defence system of the respiratory tract

Glucocorticoids are used to mature the fetal lung at times of threatened premature delivery. These drugs modify leukocyte profiles when administered in adulthood, but their effects on the mature host defence system following administration during the perinatal period are incompletely understood. In this study, the long-term effects of perinatal dexamethasone exposure on rodent host defence cells in the pulmonary airspaces, the perivascular compartment of the lung, and the blood were investigated. Rats were treated prenatally (gestational days 16-19) or neonatally (postnatal days 1-7) by inclusion of dexamethasone in the mothers' drinking water (1 microg/ml). The pups were then allowed to develop to adulthood (P60-80), at which time respiratory tissues were collected for light and electron microscopy and bronchoalveolar lavage (BAL), and blood for cell count and fluorescent activated cell-sorting (FACS) analysis. Prenatal treatment had no effect on any parameter examined. Following neonatal dexamethasone exposure, light microscopy of the lung tissue revealed a significant reduction in the number of cells in the perivascular space in both the central and the peripheral regions of the adult lung, but no differences in the number of cells in the airspaces. Neonatal dexamethasone exposure was also characterized by a significant reduction in the total number of white cells in the peripheral blood in adulthood and in particular, the number of lymphocytes relative to neutrophils was significantly reduced at maturity in these animals. The results show that neonatal, but not prenatal, dexamethasone exposure significantly alters the distribution of host defence cells in the blood and lung at maturity compared with control animals. The early neonatal period is characterized by the stress hyporesponsive period in the rat, when endogenous glucocorticoid levels are very low. Therefore, exogenous glucocorticoids administered during this time are likely to have marked "programming" effects on glucocorticoid-sensitive tissues.

Radiation-induced strain differences in mouse alveolar inflammatory cell apoptosis

Whole-thorax irradiation results in the development of the diffuse inflammatory response alveolitis in C3H/HeJ (C3H) mice and a milder alveolitis with fibrosis in C57BL/6J (B6) mice. In this study, we investigate if this mouse strain difference in response to radiation is due to differences in lung inflammatory cell apoptosis. Mice of the C3H and B6 strains were given a radiation dose of 18 Gy to the thorax and the animals were sacrificed at 11 or 18 weeks following exposure or when they were moribund. Active caspase-3 staining was used to identify apoptotic cells in the alveolar space of histological lung sections from the mice. The apoptotic index of B6 mice was greater than that of C3H mice at 11 weeks postirradiation (17.8% of airspace cells vs. 7.8%, p = 0.028) and in mice sacrificed because of illness (27.3% vs. 14.4%, p = 0.036). No C3H mice survived to the later time point. The inflammatory cells undergoing apoptosis in the mouse lungs were morphologically consistent with alveolar macrophages. We conclude that a difference in inflammatory cell apoptosis may contribute to the disparate pulmonary radiation response of these mouse strains.

Increased levels of hypoxia-sensitive proteins in allergic airway inflammation.

In this study we investigated the alterations in protein levels that are induced by allergic eosinophilic lung inflammation. Lung tissue eosinophilia and sequestration of inflammatory cells in airspaces were provoked by systemic sensitization with ovalbumin followed by repeated inhalation challenge with aerosolized ovalbumin. Proteome alterations in lung tissue and bronchoalveolar lavage fluid, respectively, were examined by two-dimensional gel electrophoresis followed by identification of proteins by mass spectrometry. Several proteins were markedly increased in inflamed tissue. In particular, several proteins that are known to be associated with hypoxia were elevated, for example, glycolytic enzymes, glucose-regulated protein 78 kD, prolyl-4-hydroxylase, peroxiredoxin 1, and arginase. Out of the identified proteins, Ym2 displayed the clearest increase, present at high levels in animals with lung eosinophilia, while being undetectable in control subjects. Furthermore, the levels of cathepsin S were markedly increased in inflamed tissue. Taken together, this study identifies a number of marker proteins associated with the pathogenesis of allergic lung inflammation and indicates a link between allergic airway inflammation and induction of hypoxia-related gene products.

The relationship of sputum eosinophilia and sputum cell generation of IL-5

Background: Eosinophil recruitment to the airway after antigen challenge is regulated by many factors, including airway cell generation of cytokines. Objectives: The purpose of this study was to determine the relationship between sputum cell generation of IL-5 and the appearance of eosinophils in the sputum after antigen challenge. Methods: Sputum samples from 11 allergic subjects were collected before and again 4 and 24 hours after antigen challenge. In 6 of these subjects, induced sputum samples were also obtained 48 hours and 7 days after challenge. Sputum leukocyte differential and cell counts and eosinophil-derived neurotoxin levels were determined. Sputum cells were then cultured with PHA (10 μg/mL) to stimulate IL-5 and IFN-γ, which were measured in culture supernatants. Results: An increase in sputum eosinophils and eosinophil-derived neurotoxin levels was detected at 4 hours after antigen challenge, with peak values at 24 hours. In contrast, significant increases in ex vivo generation of IL-5 by sputum cells was not seen until 24 hours after challenge. At 24 hours, PHA-induced IL-5 correlated with airspace eosinophil values (rs = 0.78, P < .01). In addition, the ratio of IFN-γ/IL-5 decreased at 24 hours (P < .05) and had an inverse correlation with sputum eosinophils (rs= –0.68, P < .05). Conclusion: Although eosinophils are increased in the airway lumen as early as 4 hours, the ex vivo generation of IL-5 by sputum cells is first noted in samples obtained 24 hours after antigen challenge. This suggests that the early (4 hours) recruitment of eosinophils to the airway lumen may be regulated by factors other than IL-5 or that mucosal cells (rather than airspace cells) contribute to the IL-5 generation at this time point. Furthermore, IL-5 generation by airspace cells may be more responsible for either eosinophil recruitment or retention at later time points. (J Allergy Clin Immunol 2000;106:1063-9.)

Systemic Effect of Particulate Air Pollution

The association in epidemiological studies between particulate air pollution (PM10) and increased mortality and morbidity from cardiovascular disease is well established. However, the mechanism(s) by which PM10 produces these effects is unknown. We have developed a hypothesis that ultrafine components of PM10 cause lung inflammation by creating local lung oxidative stress, which activates transcription factors such as NF-kB and hence the transcription of genes for inflammatory mediators. In a series of studies in vivo in the rat and using cultured airspace epithelial cells in vitro, we have tested this hypothesis using environmental PM10 and fine (CB 260 nm in diameter) and ultrafine (UfCB, 14 nm in diameter) carbon particles, since carbon is a major component of PM10 We have shown that compared with CB, which produces trivial effects, UFCB and PM10 produce local lung inflammation, increased epithelial permeability, and evidence of oxidative stress. We have also shown that PM10 also activates NF-kB in airspace epithelial cells. We also hypothesized that the local lung inflammation produced by PM10, may result in systemic effects, in particular systemic oxidative stress and enhanced blood coagulation, which may have a role in the adverse cardiovascular effects induced by PM10. To test this hypothesis we measured oxidative stress and changes in coagulation factors in plasma following the inhalation of UFCB, CB, or instillation ofPM,10 in the rat. Immediately after 7 h inhalation of UFCB (1000 (g/m3) there was a significant decrease in the antioxidant capacity in rat plasma, which fell further 16 and 48 h after cessation of the inhalation. A similar fall in plasma antioxidant capacity was shown 6 h after instillation of PM10 (125 tig). In contrast, there were no significant changes in antioxidant capacity in rats after 7 h of inhalation of CB at similar concentrations. The levels of factor VII in plasma, which is a key factor in the intrinsic pathway of coagulation cascade, increased at time points from 6 h to 7 days after inhalation of UFCB, but did not change after CB exposure. There were no changes in plasma fibrinogen or other coagulation factors after inhalation of particles. Thus, inhalation of ultrafine carbon black particles and instillation of PMio in rats decreases plasma antioxidant capacity as an indication of systemic oxidative stress. Ultrafine carbon black particles also cause increased factor VII levels in the plasma, a known risk factor for adverse cardiovascular events. These studies help to explain the relationship between the levels of particulate air pollutants and cardiovascular morbidity/mortality.

Differential NF-kappaB activation after intratracheal endotoxin.

We examined the relationship between nuclear factor (NF)-kappaB DNA binding activity, cytokine gene expression, and neutrophilic alveolitis in rats after intratracheal (IT) instillation of endotoxin [lipopolysaccharide (LPS)]. NF-kappaB activation in lung tissue mirrored neutrophilic alveolitis after IT LPS instillation, with NF-kappaB activation and neutrophilic influx beginning 2 h after IT LPS doses of 0.01 mg/kg or greater. In lung lavage fluid cells, however, transient NF-kappaB activation was present in alveolar macrophages by 15 min after IT LPS instillation, followed by a second peak of NF-kappaB activation corresponding to the onset on neutrophilic alveolitis. For cytokines thought to be NF-kappaB dependent, two different patterns of mRNA expression were found. Interleukin (IL)-1alpha, IL-1beta, and tumor necrosis factor-alpha showed increased mRNA by 30 min after IT LPS instillation, but IL-6- and cytokine-induced neutrophil chemoattractant mRNAs were not substantially increased until 2 h after IT LPS instillation. Therefore, IT LPS causes differential NF-kappaB activation in air space cells and lung tissue, which likely determines production of key cytokines and directs the evolution of neutrophilic alveolitis.

Cytokines in bronchoalveolar lavage fluid of patients with nocturnal asthma.

Airflow obstruction can have a circadian pattern with nocturnal worsening. Airway inflammation is a cardinal feature of asthma, and it has been shown to increase at night in association with the decline in pulmonary function. Although the mechanisms regulating enhanced airway inflammation in asthma at night have yet to be ascertained, we hypothesized that circadian variation in cytokine expression or production is an important factor in the development of nocturnal airflow limitation. To investigate this possibility, spirometry and bronchoscopy were performed; the bronchoalveolar lavage (BAL) fluid obtained at 4:00 A.M. and at 4:00 P.M. were measured for IL-1 beta in asthmatics with (n = 5) and without (n = 9) nocturnal asthma. In addition, the activity of IL-3, IL-5, and GM-CSF was measured using a biologic assay (eosinophil survival-enhancing activity). BAL fluid concentrations of IL-1 beta were significantly greater at 4:00 A.M. than at 4:00 P.M. (1.14 +/- 0.6 versus 0.7 +/- 0.6 pg/ml; p = 0.05) in asthmatics with nocturnal airflow obstruction. Moreover, IL-1 beta levels at 4:00 A.M. tended to be higher in subjects with nocturnal asthma than in those without nighttime airflow reduction (1.14 +/- 0.6 versus 0.3 +/- 0.4 pg/ml; p = 0.1). On the other hand, eosinophil survival-enhancing activity in BAL fluid, which is usually associated with IL-3, IL-5, or GM-CSF, was not detected in relationship to nocturnal asthma. Because IL-1 beta can activate air-space cells, particularly alveolar macrophages, we propose that an increased release of this cytokine is a significant contributor to nocturnal airway inflammation and obstruction in asthma.

Immunohistochemistry of a human type I pneumocyte‐associated protein in lung

A mouse monoclonal antibody to a human lung lavage protein was raised using proteins, with the potential ability to bind surfactant, as the immunogen. The proteins were isolated from cadaver lung lavage. The antibody was tested for its reactivity with lung and other organs. It reacted with type I pneumocytes and some of the nonciliated cells in the surface epithelium of distal bronchioles. Staining was also seen in the cells surrounding the glandular structures, superficial keratinocytes of the skin, endothelium, and nerve sheath cells. With the exception of bronchiolar cells, the stained cells have a squamous morphology, and this protein may serve as a marker or determinant of this characteristic of cells. In pathologic lungs some of the cells in air spaces with "bronchiolarization" of the epithelium exhibited staining for the protein. It could not be ascertained whether the stained cuboidal cells were reactive type II pneumocytes or distal bronchiolar cells. The intraalveolar material in pulmonary alveolar proteinosis did not show remarkable staining for the protein. Even though the protein is not unique to type I pneumocytes, it may serve as a marker for these cells in the study of their development and biology.

Increased Airway Inflammation with Segmental versus Aerosol Antigen Challenge

Airway inflammation is increasingly recognized as a pivotal component of asthma. Because allergens provoke bronchial constriction and inflammation in allergic subjects, bronchial antigen challenge has emerged as a powerful technique for evaluating mechanisms involved in this process. In this study, we compare whole lung antigen challenge (WLAC) with segmental bronchoprovocation (SBP) in eight allergic, non-asthmatic, non-smoking subjects, and evaluated the response by bronchoalveolar lavage (BAL) prior to, and 48 h after antigen challenge. Both challenge techniques evoked airway inflammation, manifest as an increase in total cells and eosinophils recovered by BAL, an increase in total protein concentration, and enhanced production of superoxide anion by airspace cells. The degree to which these changes occurred was significantly greater with SBP than WLAC, and only SBP evoked persistent measurable change in alveolar macrophage density and eosinophil granule protein concentrations. Moreover, although both techniques were associated with a comparable immediate fall in FEV1, only WLAC resulted in statistically significant persistent physiologic changes 48 h afterwards. We conclude that, as anticipated, SBP produces more intense airway inflammation in allergic subjects, does not result in late airway obstruction, and offers specific advantages in studying allergen-driven airway inflammation.

Enhanced production of oxygen radicals in nocturnal asthma.

Although the mechanisms of nocturnal worsening of pulmonary function in asthmatics have not been entirely established, airway inflammation is felt to be a major factor in disease severity. Consequently, to determine whether changes in bronchoalveolar lavage (BAL) fluid cellular components and their functions are related to nocturnal airway obstruction, we performed BAL at 4:00 A.M. and at 4:00 P.M. in asthma subjects with (n = 5) and without (n = 10) nocturnal asthma. No significant changes were observed from 4:00 P.M. to 4:00 A.M. in the concentration of total cells or the percentage or concentration of eosinophils or neutrophils in BAL fluid from subjects with or without nocturnal asthma. However, superoxide anion generation by air-space cells from subjects with nocturnal asthma was significantly greater at 4:00 A.M. than at 4:00 P.M. (6.9 +/- 1.7 versus 1.8 +/- 0.5 nmol/500K cells/h, p less than 0.05). Moreover, superoxide production at 4:00 A.M. was greater in subjects with than in those without nocturnal asthma (6.9 +/- 1.7 versus 2.2 +/- 0.6, p less than 0.02). Furthermore, in our group of asthmatics, the change in generation of superoxide anion from 4:00 P.M. to 4:00 A.M. was significantly correlated with the change in FEV1 (r = -0.71, p less than 0.01). We conclude that the development of nocturnal airway obstruction in asthma is associated with enhanced production of oxygen radicals by air-space cells. Because oxygen radicals can cause airway injury and thus enhance bronchial obstruction, it is possible that the release of these reactive compounds is causally associated with nocturnal asthma.

Enhanced superoxide production by alveolar macrophages and air-space cells, airway inflammation, and alveolar macrophage density changes after segmental antigen bronchoprovocation in allergic subjects.

Airway inflammation is a principal determinant of airway responsiveness and function in asthma and allergic diseases. Alveolar macrophages (AM) may contribute to inflammation in multiple ways, including release of reactive oxygen species such as superoxide (SO) anion. We hypothesized that SO production by AM increases after segmental bronchoprovocation (SBP) with relevant antigen and contributes to airway injury. Eight ragweed-sensitive subjects with allergic rhinitis were studied by bronchoalveolar lavage and ragweed SBP to determine the SO production and characteristics of cells recruited after antigen challenge. No significant changes in cell numbers or total protein concentration were observed immediately after antigen challenge. Purification (to greater than 94%) of AM on discontinuous gradients of Percoll revealed significantly increased spontaneous and opsonized-zymosan-driven SO production immediately after antigen challenge. Forty-eight hours later, total air-space cells, AM, eosinophils, and total protein concentration were significantly increased in relationship to antigen dose given. Furthermore, both unfractionated air-space cells and purified AM obtained 48 h after antigen challenge released increased amounts of SO anion in response to activator compared with either cells obtained immediately after SBP or those obtained 48 h after saline challenge. In addition, significant increases in high density AM were also seen 48 h after antigen challenge. These data suggest that AM activation occurs immediately after antigen challenge, and that the late airway response to antigen is characterized by the appearance of high density AM, which have potentiated SO release. The increased oxidative burden thereby produced may contribute to increased airway injury.

Enhanced reactive oxygen species metabolism of airspace cells and airway inflammation follow antigen challenge in human asthma

Airflow limitation and airway inflammation follow antigen bronchoprovocation in sensitized individuals. Inflammation likely results from the interplay of several previously demonstrated factors, but the participation and persistence of enhanced reactive oxygen species (ROS) metabolism of airspace cells after antigen challenge have received more limited attention. We studied nine subjects with mild asthma by bronchoalveolar lavage before and 48 (one subject) to 72 (eight subjects) hours after antigen bronchoprovocation and compared airspace cell numbers and types, cell function, and bronchoalveolar lavage fluid protein, albumin, and immunoglobulins. Mild, but significant, airflow limitation persisted at the time of the second lavage. Eosinophil influx was a notable component of the increased airspace cells in postchallenge lavages. Airspace cells demonstrated significantly enhanced ROS metabolism, and total protein, albumin, and IgM levels were higher in postchallenge lavage specimens. Antigen bronchial challenge produces airspace inflammation, which may develop, in part, as a consequence of enhanced ROS metabolism of airspace cells.

Bronchoalveolar Lavage in Stable Asthmatics Does Not Cause Pulmonary Inflammation

Bronchoalveolar lavage (BAL) has become an important tool for evaluating changes in airway cells and fluid in asthma, and it may give insights into mechanisms of bronchial inflammation. Many factors contribute to airway inflammation in asthma including, possibly, airway instrumentation. To establish whether BAL leads to diffuse airway inflammation in stable asthmatics, we performed paired BAL studies (24 h apart) in eight subjects with mild asthma whose prebronchoscopy spirometric results were similar on both days. Airflow limitation did not occur in any subject after bronchoscopy. We observed no significant changes in BAL volume return, cell differential, lymphocyte subsets, reactive oxygen species metabolism by air-space cells, or BAL total protein. There was a slight increase in second-day BAL total cell return. We conclude that bronchoscopy and BAL in stable asthmatics with mild disease is not associated with evidence of diffuse airway inflammation.