Immunophenotyping of bronchoalveolar lavage lymphocytes

House dust mite-induced asthma exacerbates Alzheimer's disease changes in the brain of the AppNL-G-F mouse model of disease

Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) plaques, neuroinflammation, and neuronal death. Besides aging, various comorbidities increase the risk of AD, including obesity, diabetes, and allergic asthma. Epidemiological studies have reported a 2.17-fold higher risk of dementia in asthmatic patients. However, the molecular mechanism(s) underlying this asthma-associated AD exacerbation is unknown. This study was designed to explore house dust mite (HDM)-induced asthma effects on AD-related brain changes using the AppNL-G-F transgenic mouse model of disease. Male and female 8-9 months old C57BL/6J wild type and AppNL-G-F mice were exposed to no treatment, saline sham, or HDM extract every alternate day for 16 weeks for comparison across genotypes and treatment. Mice were euthanized at the end of the experiment, and broncho-alveolar lavage fluid (BALF), blood, lungs, and brains were collected. BALF was used to quantify immune cell phenotype, cytokine levels, total protein content, lactate dehydrogenase (LDH) activity, and total IgE. Lungs were sectioned and stained with hematoxylin and eosin, Alcian blue, and Masson's trichrome. Serum levels of cytokines and soluble Aβ1-40/42 were quantified. Brains were sectioned and immunostained for Aβ, GFAP, CD68, and collagen IV. Finally, frozen hippocampi and temporal cortices were used to perform Aβ ELISAs and cytokine arrays, respectively. HDM exposure led to increased levels of inflammatory cells, cytokines, total protein content, LDH activity, and total IgE in the BALF, as well as increased pulmonary mucus and collagen staining in both sexes and genotypes. Levels of serum cytokines increased in all HDM-exposed groups. Serum from the AppNL-G-F HDM-induced asthma group also had significantly increased soluble Aβ1-42 levels in both sexes. In agreement with this peripheral change, hippocampi from asthma-induced male and female AppNL-G-F mice demonstrated elevated Aβ plaque load and increased soluble Aβ 1-40/42 and insoluble Aβ 1-40 levels. HDM exposure also increased astrogliosis and microgliosis in both sexes of AppNL-G-F mice, as indicated by GFAP and CD68 immunoreactivity, respectively. Additionally, HDM exposure elevated cortical levels of several cytokines in both sexes and genotypes. Finally, HDM-exposed groups also showed a disturbed blood-brain-barrier (BBB) integrity in the hippocampus of AppNL-G-F mice, as indicated by decreased collagen IV immunoreactivity. HDM exposure was responsible for an asthma-like condition in the lungs that exacerbated Aβ pathology, astrogliosis, microgliosis, and cytokine changes in the brains of male and female AppNL-G-F mice that correlated with reduced BBB integrity. Defining mechanisms of asthma effects on the brain may identify novel therapeutic targets for asthma and AD.

Unveiling the Diagnostic Potential: A Comprehensive Review of Bronchoalveolar Lavage in Interstitial Lung Disease

This comprehensive review examines the diagnostic potential of bronchoalveolar lavage (BAL) in interstitial lung disease (ILD), emphasizing its accuracy and significance in various ILDs, including idiopathic pulmonary fibrosis (IPF), sarcoidosis, hypersensitivity pneumonitis, and connective tissue disease-associated ILD. The analysis underscores the importance of abnormalities in both cellular and non-cellular components of BAL fluid for precise ILD diagnosis. Recommendations advocate for the integration of BAL into clinical guidelines, a multidisciplinary diagnostic approach, and further standardization of procedures. Looking toward the future, ongoing research highlights technological advancements, biomarker discovery, and the integration of artificial intelligence in BAL interpretation. These developments not only promise to enhance ILD diagnosis but also offer prospects for a more personalized approach to patient management based on insightful patient stratification guided by BAL findings. This abstract encapsulates the key findings, recommendations, and future prospects identified in the review, providing a concise overview of the diagnostic potential of BAL in ILD.

Toxicological evaluation of a nonlethal riot control combinational formulation upon dermal application using animal models

Numerous adverse effects on human health have been reported in epidemiological studies of oleoresin capsicum (OC) and other riot control agents (RCAs). Importantly, the daunting risk of such RCAs can be neutralized by optimizing the desired concentration of such agents for mob dispersal. Hence, a nonlethal riot control combinational formulation (NCF) was prepared for dispersing rioters without imparting fatal outcomes. However, for desired utilization of NCF, it is essential to recognize its extent of potential toxicity. Therefore, the current investigation evaluated the dermal toxicity of NCF using experimental animals in compliance with the OECD guidelines. Additionally, few essential metal ions were analyzed and found non -significantly different in the test rats as compared to control rats. Moreover, abnormal dermal morphology and lesions ultrastructural tissue defects were not noticed as evinced by different studies like ultrasonography, histology, and scanning electron microscopy (SEM) respectively. Further, Doppler ultrasonography exhibited non-significantly different blood flow velocity in both groups, whereas miles test demonstrated a significantly increased Evans blue concentration in test rats compared to the control rats, which might be due to an initial increase in blood flow via an instant action of the NCF at the cutaneous sensory nerve endings. However, our results demonstrated NCF can produce initial skin irritating and sensitizing effects in guinea pigs and rabbits without the antecedence of acute toxicity (≤2000 mg/kg) in Wistar rats.

Characterization of natural killer and T cells in bronchoalveolar lavage and peripheral blood of sarcoidosis patients

The characterization of frequency and phenotypes of natural killer (NK) cells and T cells in BAL and peripheral blood of patients with sarcoidosis was evaluated, to discriminate the differential status of these cells in these two compartments. The analysis revealed that CD56^brightCD16^neg resulted higher in BAL than PB of sarcoidosis and healthy subjects, while CD56^dimCD16⁺ showed a different proportion between BAL and PB of both Sarcoidosis patients and HC. Moreover, in comparison with autologous PB, BAL was characterized by a higher expression of activated NK cell markers NKp44, CD69 and CD25. Significantly increased levels of PD-1⁺ NK cells in the BAL of patients were detected. Regarding the maturation of CD4 and CD8, an increase of Effector Memory T cells (T_EM) was reported in BAL compared to PB. A better characterization of NK and T cells may lead to an improvement of the pathogenetic mechanisms in sarcoidosis.

Using mass cytometry for the analysis of samples of the human airways

Mass cytometry (MC) is a powerful method for mapping complex cellular systems at single-cell levels, based on the detection of cellular proteins. Numerous studies have been performed using human blood, but there is a lack of protocols describing the processing and labeling of bronchoalveolar lavage fluid (BALF) and nasal polyps (NP) for acquisition by MC. These specimens are essential in the investigation of immune cell characteristics in airway diseases such as asthma and chronic rhinosinusitis with NP (CRSwNP). Here we optimized a workflow for processing, labeling, and acquisition of BALF and NP cells by MC. Among three methods tested for NP digestion, combined enzymatic/mechanical processing yielded maximum cell recovery, viability and labeling patterns compared to the other methods. Treatment with DNAse improved sample acquisition by MC. In a final step, we performed a comparison of blood, BALF and NP cell composition using a 31-marker MC antibody panel, revealing expected differences between the different tissue but also heterogeneity among the BALF and NP samples. We here introduce an optimized workflow for the MC analysis of human NP and BALF, which enables comparative analysis of different samples in larger cohorts. A deeper understanding of immune cell characteristics in these samples may guide future researchers and clinicians to a better disease management.

External quality assessment of flow cytometric bronchoalveolar lavage cellular analysis: 20 years' experience in The Netherlands

BACKGROUND

Bronchoalveolar (BAL) cellular analysis can be supportive in the diagnosis of interstitial lung disease. The flow cytometric analysis of BAL fluid cells is complicated by cell fragility and adherence and autofluorescence of macrophages, making conventional analysis of BAL fluid cells as done in external quality schemes (EQA) for blood lymphocyte subsets, not representative. Following a procedure for stabilized BAL cells, a separate EQA was set up. The results of 20 years' experience are presented.

METHODS

From each round between 2000 and 2020 the following flow cytometric parameters were recorded from each participant: total lymphocyte population (TLY), CD3+ lymphocytes, CD3+ CD4+ lymphocytes, CD3+ CD8+ lymphocytes, CD3- CD16+/56+ lymphocytes, CD19+ lymphocytes and CD103 + CD3+ lymphocytes. In addition, the eosinophils and neutrophils were recorded. The mean and standard deviation of each parameter per round were calculated. The 40 rounds were divided in four respective groups of 10 in order to compare the results as function of time. In addition the interpretation of the results of participants was scored.

RESULTS

The median SD in the four groups was below 10% for all parameters except for TLY and the CD103+ CD3+ lymphocytes. No improvement in time was observed for any (sub)population except for the CD3+ CD4+ subset. Interpretation of the results varied based on disease, with greatest consensus for sarcoidosis cases and lowest for nonspecific interstitial lung disease cases.

CONCLUSIONS

A dedicated EQA for BAL fluid cellular analysis appears to be justified as the test material is substantially different from that of peripheral blood. We show that adequate analytical and post-analytical quality control can be achieved.

Assessment of toxicological consequences upon acute inhalation exposure to chemically improvised nonlethal riot control combinational formulation (NCF) containing oleoresin capsicum and skatole

Sensory irritation is an acute adverse effect leading to temporary disability posed by riot control agents in various deployable forms are utilized by defense personal in violent mob attacks but their irreversible toxic effects and risk assessment have been a matter of concern. These intimidating risks of available riot control agents have led to exploring the pulmonary toxicity profile of the oil in water emulsion formulation developed for vicious crowd controls containing an irritant oleoresin capsicum, a malodorant (skatole), and a commercial dye, followed by characterization using standard methods. Nonlethal riot control combinational formulation (NCF) has been aimed to be the best possible low-lethal alternative for riot control measures. In this study, 30 min of acute inhalation exposure of NCF was given to Wistar rats and various respiratory parameters like lung dynamics, bronchoalveolar lavage fluid (BALF) cytological assays, pro-inflammatory cytokines estimation, antioxidant activity, collagen accumulation, cytotoxicity, in vivo lung imaging, western blot, histology of lung tissue, etc. were investigated to validate its potentiality and rate of irritation reversibility as nonlethal agents. An exaggerated physiological change like sensory irritation, changes in lung functional variables, increased pro-inflammatory cytokines, etc. were noticed initially without airway obstruction as the expression of nociceptive TRPV1 protein did not alter the physiological regulation of protective proteins like Nrf2 and HO-1 and also no abnormality was found in lung tissue architecture. In conclusion, it can be stated that this formulation can be explored as a nonlethal riot control agent intending to generate discomfort but with early reversibility of sensory irritation and no recurrence of toxicity.

Prognostic role of NK cell percentages in bronchoalveolar lavage from patients with different fibrotic interstitial lung diseases

BAL cellularity and lymphocyte immunophenotyping offer insights into lung inflammatory status. Natural killer (NK) cells are efficient effector cells, producing pro-inflammatory cytokines. A better understanding of the biology of NK cells in BAL in the lungs is necessary to improve the pathogenesis of fibrotic ILD and develop prospective targeted treatments. Our aim was to analyse NK and NKT-like cell percentages in BAL from 159 patients with different ILD: f-HP, f-NSIP, IPF and CTD-ILD, to evaluate their potential diagnostic/prognostic role. BAL NK cell percentages showed significantly higher values in IPF than in f-HP and f-NSIP, while BAL NKT-like cells showed significantly lower values in the f-NSIP than the f-HP and IPF. A cut-off of 4%NK cells in BAL of IPF showed a significant difference in survival rate. It suggests a possible new marker of survival and raises the possibility of new targeted approach in treatment and management of IPF.

Cellular and Biochemical Analysis of Bronchoalveolar Lavage Fluid from Murine Lungs

Bronchoalveolar lavage (BAL) is a technique used to collect the contents of the airways. The fluid recovered, called BAL fluid (BALF), serves as a dynamic tool to identify various disease pathologies ranging from asthma to infectious diseases to cancer in the lungs. A wide array of tests can be performed with BALF, including total and differential leukocyte counts (DLC), enzyme-linked immunosorbent assays (ELISA) or flow-cytometric quantitation of inflammatory mediators, such as cytokines, chemokines and adhesion molecules, and assessment of nitrate and nitrite content for estimation of nitric oxide synthase (NOS) activity. Here, we describe a detailed procedure for the collection of BALF for a variety of downstream usages, including DLC by cytological and flow-cytometry-based methods, multiplex cytokine analysis by flow cytometry, and NOS activity analysis by determining nitrate and nitrite levels.

Bronchoalveolar lavage fluid lymphocytosis in 104 dogs (2006-2016)

BACKGROUND

Bronchoalveolar lavage (BAL) fluid cytology and culture are used to characterize respiratory diseases in dogs. Little is known about disorders associated with increased numbers of lymphocytes in BAL fluid.

OBJECTIVE

To evaluate duration of clinical signs and detection of specific respiratory diagnoses in dogs with BAL lymphocytosis.

ANIMALS

One-hundred four client-owned dogs evaluated for respiratory signs.

METHODS

Medical records of dogs that had >300 cells/μL and >20% lymphocytes on a differential cell count of BAL fluid between January 1, 2006, and January 1, 2016, were reviewed retrospectively. Cases were evaluated for the duration of clinical signs and respiratory diagnoses, including aspiration injury, infectious or inflammatory respiratory disease, and airway collapse.

RESULTS

Dogs ranged in age from 0.5 to 16 years (median, 7.9 years) and had a median body weight of 11.4 kg (range, 2.0-42.7 kg). Eosinophilic lung disease was documented in 13 of 104 dogs (Group 1) and airway neutrophilia associated with infectious or inflammatory disease was found in 59 of 104 dogs (Group 2). Lymphocytosis alone in BAL fluid was described in 32 dogs (Group 3). Duration of cough did not differ among groups, but airway collapse was significantly more common in dogs with solitary lymphocytosis than in those with other types of inflammation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Lymphocytosis in BAL fluid is common in dogs and, in many cases, likely represents a common response to airway injury, independent of the type or duration of insult. It is unknown whether airway collapse leads to lymphocytosis or if the inflammatory process causes airway collapse.

Original Research: Evaluation of pulmonary response to inhaled tungsten (IV) oxide nanoparticles in golden Syrian hamsters

Extensive industrial and military uses of tungsten have raised the possibilities of human occupational and environmental exposure to nanoparticles of this metal, with concomitant health concerns. The goal of this study was to investigate the potential mechanism of pulmonary toxicity associated with inhaled tungsten (IV) oxide nanoparticles (WO₃ NPs) in Golden Syrian Hamsters. Animals exposed to WO₃ NPs via inhalation were divided into three groups - control and two treatment groups exposed to either 5 or 10 mg/m³ of aerosolized WO₃ NPs for 4 h/day for four days. A long-term exposure study (4 h/day for eight days) was also carried out using an additional three groups. Pulmonary toxicity assessed by examining changes in cell numbers, lactate dehydrogenase activity, alkaline phosphatase activity, total protein content, TNF-α, and HMGB1 levels in bronchoalveolar lavage fluids showed a significant difference when compared to control (P < 0.05). The molecular mechanism was established by assessing protein expression of cathepsin B, TXNIP, NLRP3, ASC, IL-1β and caspase-1. Western blot analysis indicated a 1.5 and 1.7 fold changes in NLRP3 in treatment groups (5 mg/m³, P < 0.05 and 10 mg/m³, P < 0.01, respectively), whereas levels of cathepsin B were 1.3 fold higher in lung tissue exposed to WO₃ NPs suggesting activation of inflammasome pathway. Morphological changes studied using light and electron microscopy showed localization of nanoparticles and subsequent perturbation in airway epithelia, macrophages, and interstitial areas of alveolar structures. Results from the current study indicate that inhalation exposure to WO₃ NPs may induce cytotoxicity, morphological changes, and lung injury via pyroptotic cell death pathway caused by activation of caspase-1.

Interaction with epithelial cells modifies airway macrophage response to ozone

The initial innate immune response to ozone (O3) in the lung is orchestrated by structural cells, such as epithelial cells, and resident immune cells, such as airway macrophages (Macs). We developed an epithelial cell-Mac coculture model to investigate how epithelial cell-derived signals affect Mac response to O3. Macs from the bronchoalveolar lavage (BAL) of healthy volunteers were cocultured with the human bronchial epithelial (16HBE) or alveolar (A549) epithelial cell lines. Cocultures, Mac monocultures, and epithelial cell monocultures were exposed to O3 or air, and Mac immunophenotype, phagocytosis, and cytotoxicity were assessed. Quantities of hyaluronic acid (HA) and IL-8 were compared across cultures and in BAL fluid from healthy volunteers exposed to O3 or air for in vivo confirmation. We show that Macs in coculture had increased markers of alternative activation, enhanced cytotoxicity, and reduced phagocytosis compared with Macs in monoculture that differed based on coculture with A549 or 16HBE. Production of HA by epithelial cell monocultures was not affected by O3, but quantities of HA in the in vitro coculture and BAL fluid from volunteers exposed in vivo were increased with O3 exposure, indicating that O3 exposure impairs Mac regulation of HA. Together, we show epithelial cell-Mac coculture models that have many similarities to the in vivo responses to O3, and demonstrate that epithelial cell-derived signals are important determinants of Mac immunophenotype and response to O3.

Translational research in pediatrics III: bronchoalveolar lavage

The role of flexible bronchoscopy and bronchoalveolar lavage (BAL) for the care of children with airway and pulmonary diseases is well established, with collected BAL fluid most often used clinically for microbiologic pathogen identification and cellular analyses. More recently, powerful analytic research methods have been used to investigate BAL samples to better understand the pathophysiological basis of pediatric respiratory disease. Investigations have focused on the cellular components contained in BAL fluid, such as macrophages, lymphocytes, neutrophils, eosinophils, and mast cells, as well as the noncellular components such as serum molecules, inflammatory proteins, and surfactant. Molecular techniques are frequently used to investigate BAL fluid for the presence of infectious pathologies and for cellular gene expression. Recent advances in proteomics allow identification of multiple protein expression patterns linked to specific respiratory diseases, whereas newer analytic techniques allow for investigations on surfactant quantification and function. These translational research studies on BAL fluid have aided our understanding of pulmonary inflammation and the injury/repair responses in children. We review the ethics and practices for the execution of BAL in children for translational research purposes, with an emphasis on the optimal handling and processing of BAL samples.

Distribution of γδ and other T-lymphocyte subsets in patients with chronic obstructive pulmonary disease and asthma

The role of T lymphocytes in pathogenesis of chronic inflammatory airway diseases - asthma and chronic obstructive pulmonary disease (COPD) has been emphasized in recent years: the importance of αβ T-cells (CD8+ and CD4+) has been widely described. A substantial fraction of γδ T-cells is a composite part of pulmonary T lymphocytes. Specific localisation of γδ T-cells in epithelium/mucosa-rich tissues implies their potential role in local inflammatory immune response, which occurs in chronic inflammatory airway diseases. An investigation was made of the T-lymphocyte subsets in induced sputum (IS), in bronchoalveolar lavage (BAL) and in peripheral blood from 20 patients with COPD (stages II-III; GOLD), 18 patients with asthma (persistent mild to moderate; GINA) and 14 healthy subjects. Relationship of γδ T-cells with lung function and smoking history was analysed. COPD patients had significantly higher numbers of CD8+T-cells in the airways of smokers compared to ex-smokers in the COPD group. A significant positive correlation was found between CD8+T-cells and pack-years of smoking. Differently, the COPD patients had significantly lower relative and absolute numbers of γδ T-cells in IS and in BAL compared to those from asthma or healthy subjects. The quantity of γδ T-cells negatively correlated with forced expiratory volume in 1 s and smoking (pack-years) only in COPD group. Our findings indicate a different local inflammatory response in COPD patients and in asthmatic groups. The reduced amount of γδ T-cells in IS and in BAL from COPD patients raises the hypothesis about their important role in pathogenesis of COPD.

Leukocyte counts in bronchoalveolar lavage fluid obtained from normal and Maedi-Visna-infected sheep

BACKGROUND

Bronchoalveolar lavage has proven helpful for the diagnosis of certain ovine diseases of the lungs. There is insufficient data concerning the leukocyte profile of bronchoalveolar lavage fluid (BALF) from MaediVisna infected sheep.

OBJECTIVE

The objective of this study was to assess the differential leukocyte profile of BALF associated with Maedi virus infection in sheep and to determine whether cytologic examination of BALF is an effective way to diagnose Maedi or determine the severity of lung lesions.

METHODS

BALF and serum samples were analyzed from 400 sheep. Sediment smears of bronchoalveolar lavage were stained with Diff-Quik and examined microscopically to obtain a 200-cell differential cell count. Serum was tested using a commercial kit for Maedi-Visna virus antibodies. Lung samples obtained at the time of slaughter were weighed and examined histologically.

RESULTS

Maedi-infected sheep (n=267; seropositive with lung lesions) had a significantly higher percentage of lymphocytes and lower percentage of macrophages in BALF than normal sheep (n=133; seronegative and no lung lesions). These differences were significantly more severe in animals with advanced vs moderate lung lesions. Using classification trees, a cut-off of 13.5% lymphocytes was predictive of Maedi infection and a cut-off of 24.5% lymphocytes was predictive of advanced lung lesions.

CONCLUSIONS

Cytologic examination of BALF is useful for the clinical diagnosis of Maedi in sheep and provides important information about the severity of the lung lesions.

Alveolar extracellular 20S proteasome in patients with acute respiratory distress syndrome

RATIONALE

Repair mechanisms resulting in alveolar protein degradation in acute respiratory distress syndrome (ARDS) are largely unknown.

OBJECTIVES

To test whether the 20S proteasome is present and functional in the alveolar space in patients with ARDS.

METHODS

Proteasome antigenic concentration in bronchoalveolar lavage (BAL) supernatants was measured by ELISA in patients with ARDS (n = 64), acute lung injury (ALI) (n = 8), sarcoidosis (n = 13), and in healthy subjects (n = 8). Cleavage of specific fluorogenic substrates (+/-epoxomicin), I(125) albumin degradation rate, and gel filtration were used to quantify and characterize proteasomal activity. The presence of proteasomes was confirmed independently by electron microscopic techniques.

MEASUREMENTS AND MAIN RESULTS

Proteasome concentrations in patients with ARDS were markedly increased (1,069 +/- 1,194 ng/ml) in comparison to healthy subjects (60.8 +/- 49.8; P < 0.001), ALI (154 +/- 43; P = 0.006), and sarcoidosis (97.6 +/- 42.2; P = 0.037). All fluorogenic substrates were hydrolyzed (Suc-LLVY-AMC, 3.6 +/- 8.8 pkat/mg; BZ-VGR-AMC, 1.8 +/- 3.1; Suc-LLE-AMC, 1 +/- 1.7) by BAL supernatants of patients with ARDS, with inhibition by epoxomicin (P = 0.0001), and the majority of proteolytic activity was detected in BAL supernatant. Maximum hydrolyzing activity occurred at 660 kD and 20S proteasome was seen microscopically after purification and being released by pneumocytes type II. Proteasomal activity and albumin degradation rate in patients with ARDS were approximately 17-fold lower than in healthy subjects. Proteasomal activity in normal BAL was inhibited by BAL aliquots from patients with ARDS but not by denatured BAL, and returned to normal by purification.

CONCLUSIONS

For the first time, we identified extracellular, biologically active 20S proteasome in the alveolar space of patients with ARDS in concentrations much higher than in normal subjects or in those with ALI.

[Bronchoalveolar lavage]

Bronchoalveolar lavage (BAL) has become an established method for the diagnosis of infectious and interstitial lung diseases. Using a bronchoscope material from the peripheral airways and alveolar spaces can be obtained. When standard protocols are followed the procedure is generally well tolerated and in combination with clinical tests allows a reliable diagnosis in many cases. Certain clinical entities, e.g. alveolar proteinosis and Langerhans cell histiocytosis can be diagnosed by BAL alone without resorting to invasive diagnostic tests. In other diseases, BAL allows to narrow the range of the differential diagnosis. However, biopsies can often still not be avoided completely. A combination of both methods together with the clinical findings represents a powerful tool for diagnosis and research into the pathologic alterations in inflammatory and fibroising lung diseases.

Extracellular proteasome in the human alveolar space: a new housekeeping enzyme?

We hypothesized that 20S proteasome is present and functional in the extracellular alveolar space in humans. Proteasomal activity was measured in bronchoalveolar lavage (BAL) supernatant from eight humans using specific proteasomal fluorogenic substrates and I(125)-albumin with and without specific proteasome inhibitors. Furthermore, gelfiltration, Western blot technique, and mass spectrometry were applied for proteasome characterization. All proteasomal fluorogenic substrates were hydrolyzed by BAL supernatant, with hydrolysis inhibited by epoxomicin (P = 0.024) and other proteasome inhibitors as well. E64, a lysosomal inhibitor, did not inhibit enzyme activity. The majority of proteolytic activity was detected in BAL supernatant rather than in the cell pellet. No correlation was found between proteasomal hydrolysis in BAL supernatant and lactate dehydrogenase activity, the total cell count in the cell pellet, and the fraction of avital cells in the cell pellet, ruling out cell lysis as a major source of proteasomal activity. Gelfiltration revealed hydrolyzing activity in the supernatant at 660 kDa and proteasome core proteins after analysis by ESI-QqTOF mass spectrometry. Furthermore, Western blots using a polyclonal antibody against proteasomal alpha-/beta-subunits detected proteasomal proteins in the typical 20- to 30-kDa range in BAL supernatant. Incubation of BAL supernatant with I(125)-albumin showed a high mean cleavage rate (101.8 microg/ml x h lavage +/- 46 SD) that was inhibited by epoxomicin (P = 0.013) and was ATP and ubiquitin independent. We identified for the first time extracellular, biologically active, ATP- and ubiquitin-independent 20S proteasome in the human alveolar space, with a high albumin cleavage rate. Possibly, the proteasome assists in maintenance of a low intra-alveolar oncotic pressure and/or alveolar protein degradation.

Constitutive activation of prosurvival signaling in alveolar mesenchymal cells isolated from patients with nonresolving acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a clinical syndrome characterized by stereotypic host inflammatory and repair cellular responses; however, mechanisms regulating the resolution of ARDS are poorly understood. Here, we report the isolation and characterization of a novel population of mesenchymal cells from the alveolar space of ARDS patients via fiber-optic bronchoscopy with bronchoalveolar lavage (BAL). BAL was performed on 17 patients during the course of ARDS. Immunofluorescence staining and multiparameter flow cytometric analysis defined a population of alveolar mesenchymal cells (AMCs) that are CD45-/prolyl-4-hydroxylase+/alpha-smooth muscle actin+/-. AMCs proliferated in ex vivo cell culture for multiple passages; early passage (3-5) cells were subsequently analyzed in 13 patients. AMCs isolated from patients with persistent or nonresolving ARDS (ARDS-NR, n = 4) demonstrate enhanced constitutive activation of prosurvival signaling pathways involving PKB/Akt, FKHR, and BCL-2 family proteins compared with AMCs from patients with resolving ARDS (ARDS-R, n = 9). Exogenous transforming growth factor-beta1 markedly induces PKB/Akt activation in AMCs from ARDS-R. ARDS-NR cells are more resistant to serum deprivation-induced apoptosis compared with ARDS-R. This study identifies a novel population of mesenchymal cells that can be isolated from the alveolar spaces of ARDS patients. AMCs in patients with ARDS-NR acquire an activational profile characterized by enhanced prosurvival signaling and an antiapoptotic phenotype. These findings support the concept that apoptosis of mesenchymal cells may be an essential component of normal repair and resolution of ARDS and suggest that dysregulation of this process may contribute to persistent ARDS.

Dendritic cell trafficking and antigen presentation in the human immune response to Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is an extraordinarily successful human pathogen, one of the major causes of death by infectious disease worldwide. A key issue for the study of tuberculosis is to understand why individuals infected with Mtb experience different clinical outcomes. To better understand the dynamics of Mtb infection and immunity, we coupled nonhuman primate experiments with a mathematical model we previously developed that qualitatively and quantitatively captures important processes of cellular priming and activation. These processes occur between the lung and the nearest draining lymph node where the key cells mediating this process are the dendritic cells (DC). The nonhuman primate experiments consist of bacteria and cell numbers from tissues of 17 adult cynomolgus macaques (Macaca fascicularis) that were infected with Mtb strain Erdman ( approximately 25 CFU/animal via bronchoscope). The main result of this work is that delays in either DC migration to the draining lymph node or T cell trafficking to the site of infection can alter the outcome of Mtb infection, defining progression to primary disease or latent infection and reactivated tuberculosis. Our results also support the idea that the development of a new generation of treatment against Mtb should optimally elicit a fast DC turnover at the site of infection, as well as strong activation of DCs for maximal Ag presentation and production of key cytokines. This will induce the most protective T cell response.

Longitudinal profile of bronchoalveolar lavage cell characteristics in patients with a good outcome after lung transplantation

Bronchoalveolar lavage fluid (BALF) analysis is used in patients after lung transplantation (LTX) to obtain more insight into pathological conditions such as acute and chronic allograft rejection. Information on the normal course of BALF cell characteristics in patients with "good outcome" after LTX is limited. Therefore we analyzed 169 BALF samples from 63 well-defined "good outcome" patients after LTX (no acute or chronic transplant dysfunction, bacterial, fungal, or viral infections at the time of BAL). Total cell count decreased from the first months: median (range) 234 x 10(3) (70-610) cells/ml to 103 x 10(3) (10-840) cells/ml during the second year posttransplantation (p < 0.001). Cell differential counts did not change during the 2-yr study period. The CD4/CD8 ratio increased significantly from 0.32 (0.11-0.46) just posttransplantation to 0.62 (0.16-4.27) the second year after LTX. This increasing ratio was mainly due to a sharp decreasing CD8(+) cell count. Thus, characteristics of BAL cellular patterns in patients with good outcomes after LTX show important changes over time. We have defined control values for the BALF cellular profile in patients without pathological airway conditions after LTX. We propose to use these control values as a tool for diagnosing patients with pulmonary complications after LTX and for the follow-up of treatment regimens.

In situ activation of helper T cells in the lung

To better understand the lung and systemic responses of helper T cells mediating memory immunity to Mycobacterium tuberculosis, we used three- and four-color flow cytometry to study the surface phenotype of CD4(+) lymphocytes. Bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) samples were obtained from a total of 25 subjects, including 10 tuberculosis (TB)-infected subjects, 8 purified-protein-derivative-negative subjects, and 7 purified-protein-derivative-positive subjects. In marked contrast to CD4(+) lymphocytes from PB (9% +/- 5% expressing CD45RA and CD29), the majority (55% +/- 16%) of CD4(+) lymphocytes in BAL (ALs) simultaneously expressed CD45RA, a naïve T-cell marker, and CD29, members of the very late activation family. Further evaluation revealed that CD4(+) ALs expressed both CD45RA and CD45RO, a memory T-cell marker. In addition, the proportion of CD4(+) lymphocytes expressing CD69, an early activation marker, was drastically increased in BAL fluid (83% +/- 9%) compared to PB (1% +/- 1%), whereas no significant difference was seen in the expression of CD25, the low-affinity interleukin 2 receptor (34% +/- 15% versus 40% +/- 16%). More importantly, we identified a minor population of CD69(bright) CD25(bright) CD4(+) lymphocytes in BAL (10% +/- 6%) that were consistently absent from PB (1% +/- 1%). Thus, CD4(+) lymphocytes in the lung paradoxically coexpress surface molecules characteristic of naïve and memory helper T cells as well as surface molecules commonly associated with early and late stages of activation. No difference was observed for ALs obtained from TB-infected and uninfected lung segments in this regard. It remains to be determined if these surface molecules are induced by the alveolar environment or if CD4(+) lymphocytes coexpressing this unusual combination of surface molecules are selectively recruited from the circulation. Our data suggest that ex vivo experiments on helper T-cell subsets that display distinctive phenotypes may be pivotal to studies on the human immune response to potential TB vaccines.