Lipid-laden bronchoalveolar macrophages in asthma and chronic cough

Lipid-Laden Macrophages in Pulmonary Diseases

Pulmonary surfactants play a crucial role in managing lung lipid metabolism, and dysregulation of this process is evident in various lung diseases. Alternations in lipid metabolism lead to pulmonary surfactant damage, resulting in hyperlipidemia in response to lung injury. Lung macrophages are responsible for recycling damaged lipid droplets to maintain lipid homeostasis. The inflammatory response triggered by external stimuli such as cigarette smoke, bleomycin, and bacteria can interfere with this process, resulting in the formation of lipid-laden macrophages (LLMs), also known as foamy macrophages. Recent studies have highlighted the potential significance of LLM formation in a range of pulmonary diseases. Furthermore, growing evidence suggests that LLMs are present in patients suffering from various pulmonary conditions. In this review, we summarize the essential metabolic and signaling pathways driving the LLM formation in chronic obstructive pulmonary disease, pulmonary fibrosis, tuberculosis, and acute lung injury.

Scalable nonparametric clustering with unified marker gene selection for single-cell RNA-seq data

Clustering is commonly used in single-cell RNA-sequencing (scRNA-seq) pipelines to characterize cellular heterogeneity. However, current methods face two main limitations. First, they require user-specified heuristics which add time and complexity to bioinformatic workflows; second, they rely on post-selective differential expression analyses to identify marker genes driving cluster differences, which has been shown to be subject to inflated false discovery rates. We address these challenges by introducing nonparametric clustering of single-cell populations (NCLUSION): an infinite mixture model that leverages Bayesian sparse priors to identify marker genes while simultaneously performing clustering on single-cell expression data. NCLUSION uses a scalable variational inference algorithm to perform these analyses on datasets with up to millions of cells. By analyzing publicly available scRNA-seq studies, we demonstrate that NCLUSION (i) matches the performance of other state-of-the-art clustering techniques with significantly reduced runtime and (ii) provides statistically robust and biologically relevant transcriptomic signatures for each of the clusters it identifies. Overall, NCLUSION represents a reliable hypothesis-generating tool for understanding patterns of expression variation present in single-cell populations.

Role of alveolar nitric oxide in gastroesophageal reflux-associated cough: prospective observational study

BACKGROUND

Fractional exhaled nitric oxide (FeNO) measured at multiple exhalation flow rates can be used as a biomarker to differentiate central and peripheral airway inflammation. However, the role of alveolar nitric oxide (CaNO) indicating peripheral airway inflammation remains unclear in gastroesophageal reflux-associated cough (GERC).

OBJECTIVES

We aimed to characterize the changes in alveolar nitric oxide (CaNO) and determine its clinical implication in GERC.

DESIGN

This is a single-center prospective observational study.

METHODS

FeNOs at exhalation flow rates of 50 and 200 ml/s were measured in 102 patients with GERC and 134 patients with other causes of chronic cough (non-GERC). CaNO was calculated based on a two-compartment model and the factors associated with CaNO were analyzed. The effect of anti-reflux therapy on CaNO was examined in 26 GERC patients with elevated CaNO.

RESULTS

CaNO was significantly elevated in GERC compared with that in non-GERC (4.6 ± 4.4 ppb versus 2.8 ± 2.3 ppb, p < 0.001). GERC patients with high CaNO (>5 ppb) had more proximal reflux events (24 ± 15 versus 9 ± 9 episodes, p = 0.001) and a higher level of pepsin (984.8 ± 492.5 versus 634.5 ± 626.4 pg/ml, p = 0.002) in sputum supernatant than those with normal CaNO. More GERC patients with high CaNO required intensified anti-reflux therapy (χ2 = 3.963, p = 0.046), as predicted by a sensitivity of 41.7% and specificity of 83.3%. Cough relief paralleled a significant improvement in CaNO (8.3 ± 3.0 versus 4.8 ± 2.6 ppb, p < 0.001).

CONCLUSION

Peripheral airway inflammation can be assessed by CaNO measurement in GERC. High CaNO indicates potential micro-aspiration and may predict a necessity for intensified anti-reflux therapy.

Immunometabolism in the pathogenesis of asthma

Bronchial asthma is a heterogeneous disease characterised by chronic airway inflammation. A variety of immune cells such as eosinophils, mast cells, T lymphocytes, neutrophils and airway epithelial cells are involved in the airway inflammation and airway hyperresponsiveness in asthma pathogenesis, resulting in extensive and variable reversible expiratory airflow limitation. However, the precise molecular mechanisms underlying the allergic immune responses, particularly immunometabolism, remains unclear. Studies have detected enhanced oxidative stress, and abnormal metabolic progresses of glycolysis, fatty acid and amino acid in various immune cells, inducing dysregulation of innate and adaptive immune responses in asthma pathogenesis. Immunometabolism mechanisms contain multiple signalling pathways, providing novel therapy targets for asthma. This review summarises the current knowledge on immunometabolism reprogramming in asthma pathogenesis, as well as potential therapy strategies.

Lipid from electronic cigarette-aerosol both with and without nicotine induced pro-inflammatory macrophage polarization and disrupted phagocytosis

Clinical cases and experimental evidence revealed that electronic cigarettes (ECIG) induce serious adverse health effects, but underlying mechanisms remain to be fully uncovered. Based on recent exploratory evidence, investigating the effects of ECIG on macrophages can broadly define potential mechanisms by focusing on the effect of ECIG exposure with or without nicotine. Here we investigated the effect of ECIG-aerosol exposure on macrophages (MQ) phenotype, inflammatory response, and function of macrophages.MQ were cultured at air liquid interface and exposed to ECIG-aerosol. Oxidative stress was determined by reactive oxygen species (ROS), heat shock protein 60 (HSP60), glutathione peroxidase (GPx) and heme oxygenase1 (HMOX1). Lipid accumulation and lipid peroxidation were defined by lipid staining and level of malondialdehyde (MDA) respectively. MQ polarization was identified by surface expression markers CD86, CD11C and CD206 as well as pro-inflammatory and anti-inflammatory cytokines in gene and protein level. Phagocytosis of E. coli by MQ was investigated by fluorescence-based phagocytosis assay.ECIG-aerosol exposure in presence or absence of nicotine induced oxidative stress evidenced by ROS, HSP60, GPx, GPx4 and HMOX1 upregulation in MQ. ECIG-aerosol exposure induced accumulation of lipids and the lipid peroxidation product MDA in MQ. Pro-inflammatory MQ (M1) markers CD86 and CD11C but not anti-inflammatory MQ (M2) marker CD206 were upregulated in response to ECIG-aerosol exposure. In addition, ECIG induced pro-inflammatory cytokines IL-1beta and IL-8 in gene level and IL-6, IL-8, and IL-1beta in protein level whereas ECIG exposure downregulated anti-inflammatory cytokine IL-10 in protein level. Phagocytosis activity of MQ was downregulated by ECIG exposure. shRNA mediated lipid scavenger receptor 'CD36' silencing inhibited ECIG-aerosol-induced pro-inflammatory MQ polarization and recovered phagocytic activity of MQ.ECIG exposure alters lung lipid homeostasis and thus induced inflammation by inducing M1 type MQ and impair phagocytic function, which could be a potential cause of ECIG-induced lung inflammation in healthy and inflammatory exacerbation in disease condition.

Alveolar macrophages from EVALI patients and e-cigarette users: a story of shifting phenotype

Exposure to e-cigarette vapors alters important biologic processes including phagocytosis, lipid metabolism, and cytokine activity in the airways and alveolar spaces. Little is known about the biologic mechanisms underpinning the conversion to e-cigarette, or vaping, product use-associated lung injury (EVALI) from normal e-cigarette use in otherwise healthy individuals. We compared cell populations and inflammatory immune populations from bronchoalveolar lavage fluid in individuals with EVALI to e-cigarette users without respiratory disease and healthy controls and found that e-cigarette users with EVALI demonstrate a neutrophilic inflammation with alveolar macrophages skewed towards inflammatory (M1) phenotype and cytokine profile. Comparatively, e-cigarette users without EVALI demonstrate lower inflammatory cytokine production and express features associated with a reparative (M2) phenotype. These data indicate macrophage-specific changes are occurring in e-cigarette users who develop EVALI.

Utilization of Oil Red O staining for assessing aspiration risk in lung transplant patients: A multidisciplinary prospective study with clinical practice insights

BACKGROUND

Gastroesophageal reflux disease with microaspiration has been associated with graft dysfunction in lung transplant patients. Identifying patients with aspiration is clinically important because it enables implementation of appropriate interventions like antireflux therapy. Oil Red O (ORO) staining with determination of the lipid-laden macrophage index (LLMI) has been proposed as a noninvasive surrogate marker in the detection of aspiration. The aim of this study was to prospectively evaluate clinical utilization of ORO staining in the assessment of aspiration risk.

METHODS

All transbronchial surgical pathology biopsies obtained in lung transplant patients undergoing routine surveillance from August 2020 through November 2021 were included in this study. Clinical team members prospectively ascertained the aspiration risk category (ARC) of each patient both before and after biopsy findings and recorded reasons for change in ARC.

RESULTS

A total of 132 transbronchial biopsies with concurrent LLMI were included in the study. LLMI was low in 51 cases (38.6%), including 21 of the 54 cases (38.9%) where aspiration was suggested based on the transbronchial biopsy findings. In total, 19 cases (14.4%) underwent a change in ARC post-biopsy including 10 that were upgraded and nine cases that were downgraded. Transbronchial biopsy findings were noted as the reason for change in ARC in the majority (15/19; 79%) of cases; only a minority (2/19; 10.5%) were due to the LLMI. Notably, 16 cases (12.1%) had a low LLMI with high-risk post-biopsy ARC and nine cases (6.8%) had a high LLMI with low-risk post-biopsy ARC.

CONCLUSIONS

This study observed that clinical evaluation for aspiration relied more heavily on transbronchial biopsy findings. Although LLMI may retain clinical utility in some scenarios, reevaluation of the clinical value of ORO testing would be prudent.

Macrophage-mediated tissue response evoked by subchronic inhalation of lead oxide nanoparticles is associated with the alteration of phospholipases C and cholesterol transporters

Background

Inhalation of lead oxide nanoparticles (PbO NPs), which are emitted to the environment by high-temperature technological processes, heavily impairs target organs. These nanoparticles pass through the lung barrier and are distributed via the blood into secondary target organs, where they cause numerous pathological alterations. Here, we studied in detail, macrophages as specialized cells involved in the innate and adaptive immune response in selected target organs to unravel their potential involvement in reaction to subchronic PbO NP inhalation. In this context, we also tackled possible alterations in lipid uptake in the lungs and liver, which is usually associated with foam macrophage formation.

Results

The histopathological analysis of PbO NP exposed lung revealed serious chronic inflammation of lung tissues. The number of total and foam macrophages was significantly increased in lung, and they contained numerous cholesterol crystals. PbO NP inhalation induced changes in expression of phospholipases C (PLC) as enzymes linked to macrophage-mediated inflammation in lungs. In the liver, the subchronic inhalation of PbO NPs caused predominantly hyperemia, microsteatosis or remodeling of the liver parenchyma, and the number of liver macrophages also significantly was increased. The gene and protein expression of a cholesterol transporter CD36, which is associated with lipid metabolism, was altered in the liver. The amount of selected cholesteryl esters (CE 16:0, CE 18:1, CE 20:4, CE 22:6) in liver tissue was decreased after subchronic PbO NP inhalation, while total and free cholesterol in liver tissue was slightly increased. Gene and protein expression of phospholipase PLCβ1 and receptor CD36 in human hepatocytes were affected also in in vitro experiments after acute PbO NP exposure. No microscopic or serious functional kidney alterations were detected after subchronic PbO NP exposure and CD68 positive cells were present in the physiological mode in its interstitial tissues.

Conclusion

Our study revealed the association of increased cholesterol and lipid storage in targeted tissues with the alteration of scavenger receptors and phospholipases C after subchronic inhalation of PbO NPs and yet uncovered processes, which can contribute to steatosis in liver after metal nanoparticles exposure.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00494-7.

Correlation between cytology Oil Red O staining and lung biopsy specimens: utility of the lipid-laden macrophage index

INTRODUCTION

Oil Red O staining is used for enumeration of the lipid-laden macrophage index (LLMI) as a surrogate for aspiration. As part of quality improvement efforts aimed at optimizing resource utilization, the utility of this stain in current cytopathology practice was re-evaluated. The objective of this study was to explore the clinical utility of Oil Red O staining in bronchoalveolar lavage (BAL) samples by correlating the LLMI with findings in concurrent histologic tissue samples.

MATERIALS AND METHODS

Lung transbronchial biopsy specimens that suggested aspiration that were submitted with concurrent BAL cytology samples were retrieved. Lung tissue biopsies were reviewed for the presence of foamy alveolar macrophages (graded as 0, 1+, and 2+), foreign material, and giant cells. The concurrent BAL was reviewed with consensus determination of the LLMI.

RESULTS

A total of 53 cases were identified. On histology, 13 cases (24.5%) were found to have no foamy alveolar macrophages, 23 cases (43.4%) were found to have 1+ foamy alveolar macrophages, and 17 cases (32.1%) were found to have 2+ foamy alveolar macrophages. Six cases (11.3%) were found to have foreign material, and 10 cases (18.9%) were found to have multinucleated giant cells. The average LLMI score was 16, with 44 (83.0%) in the low range (LLMI &lt;40) and 9 (17.0%) in the intermediate range (LLMI of 40-90).

CONCLUSIONS

None of the cases in our study had an LLMI that exceeded the cutoff value for which aspiration would be suspected. We found no correlation of the LLMI with lung biopsies that suggested aspiration.

Bronchoalveolar Lavage in a Pediatric Population

OBJECTIVES

The cytomorphologic findings of bronchoalveolar lavage (BAL) in pediatrics were correlated with clinical symptoms.

METHODS

Patient demographics, clinical symptoms/history, cytomorphologic findings, and oil red O (ORO) staining of 100 pediatric patients who underwent BAL between 2014 and 2016 were reviewed at a large academic institution.

RESULTS

Of the 100 patients (males/females, 62:38), the most common conditions for BAL included cough (46/100), reflux (39/100), pneumonia (30/100), dysphagia (22/100), asthma (19/100), and cystic fibrosis (15/100). Sixteen of 100 patients were admitted with pulmonary symptoms from the emergency department. Cytomorphologic findings showed acute inflammation in 37 BALs and chronic inflammation in 9. Abundant thick mucin was present in 3 cytology cases from patients with cystic fibrosis. Fungal elements were detected in 3 cases (Candida, Aspergillus, and Pneumocystis jirovecii) and viral effects (rhinovirus) in one. Thirty-seven of 100 had rare ORO-positive lipid-laden macrophages (LLMs), 7 of 100 had moderate LLMs, 11 of 100 had numerous LLMs, 18 of 100 had positive staining without the degree of staining, 25 of 100 had negative ORO staining, and 2 of 100 had noncontributory ORO staining. An iron stain was done on 15 BALs (2 positive, 9 negative, and 4 noncontributory).

CONCLUSIONS

BAL cytology is a useful tool in pediatrics to discriminate underlying causes of aerodigestive system conditions, while ORO staining may occasionally help.

Limited Clinical Utility of Lipid-Laden Macrophage Index of Induced Sputum in Predicting Gastroesophageal Reflux-Related Cough

Gastroesophageal reflux disease (GERD) is a common cause of chronic cough (CC). However, the diagnosis of GERD associated with CC based on 24-hour esophageal pH-monitoring or favorable response to empirical anti-reflux trials is invasive and time-consuming. Lipid-laden macrophages (LLMs) are supposed to be a biomarker for micro-aspiration of gastric content in the respiratory tract. This study was conducted to collect LLMs by the sputum induction technique and observe the relationship among the amount of LLMs, cough severity, parameters of 24-hour esophageal pH-monitoring and therapeutic response. The 24-hour esophageal pH-monitoring and sputum induction were performed on 57 patients with suspected GERD associated with CC. Thirty-four patients were followed up after empirical anti-reflux trials of 8 weeks to record the therapeutic response. Lipid-laden macrophage index (LLMI), a semiquantitative counting of LLMs, showed no significant correlation with the values of 24-hour esophageal pH monitoring at the proximal or remote electrode. No difference in LLMI or DeMeester score, as well as cough symptom association probability, were found between the responders and the non-responders. Reflux symptoms were more common in the responders (50%) compared to the non-responders (6%) (P < 0.05). Our study suggests that LLMI shows limited utility in clinically diagnosing GERD associated with CC as an underlying etiology or in predicting response to anti-reflux therapy. Anti-reflux therapy is more effective for CC patients with reflux symptoms than for those without.

Understanding potential mechanisms of harm: the drivers of electronic cigarette-induced changes in alveolar macrophages, neutrophils, and lung epithelial cells

Electronic (e-) cigarettes are growing in popularity despite uncertainties regarding their long-term health implications. The link between cigarette smoking and initiation of chronic lung disease took decades to unpick so in vitro studies mimicking e-cigarette exposure aim to detect early indicators of harm. In response to e-cigarette exposure, alveolar macrophages adopt a proinflammatory phenotype of increased secretion of proinflammatory cytokines, reduction in phagocytosis, and efferocytosis and reactive oxygen species generation. These effects are largely driven by free radical exposure, changes in PI3K/Akt signaling pathways, nicotine-induced reduction in phagocytosis receptors, and impaired lipid homeostasis leading to a foam-like lipid-laden phenotype. Neutrophils exhibit disrupted chemotaxis and transmigration to chemokines, reduced phagocytosis and bacterial killing, and an increase in protease secretion without corresponding antiproteases in response to e-cigarette exposure. This is driven by an altered ability to respond and to polarize toward chemoattractants, an activation of the p38 MAPK signaling pathway and inability to assemble NADPH oxidase. E-cigarettes induce lung epithelial cells to display decreased ciliary beat frequency and ion channel conductance as well as changes in chemokine secretion and surface protein expression. Changes in gene expression, mitochondrial function, and signaling pathways have been demonstrated in lung epithelial cells to explain these changes. Many functional outputs of alveolar macrophages, neutrophils, and lung epithelial cells have not been fully explored in the context of e-cigarette exposure and the underlying driving mechanisms are poorly understood. This review discusses current evidence surrounding the effects of e-cigarettes on alveolar macrophages, neutrophils, and lung epithelial cells with particular focus on the cellular mechanisms of change.

Lipid metabolism in asthma: Immune regulation and potential therapeutic target

Asthma is a chronic inflammatory disease of the lungs that poses a considerable health and socioeconomic burden. Several risk factors work synergistically to affect the progression of asthma. Lipid metabolism, especially in distinct cells such as T cells, macrophages, granulocytes, and non-immune cells, plays an essential role in the pathogenesis of asthma, as lipids are potent signaling molecules that regulate a multitude of cellular response. In this review, we focused on the metabolic pathways of lipid molecules, especially fatty acids and their derivatives, and summarized their roles in various cells during the pathogenesis of asthma along with the current pharmacological agents targeting lipid metabolism.

Laryngopharyngeal Reflux and Inflammatory Responses in Mucosal Barrier Dysfunction of the Upper Aerodigestive Tract

The upper aerodigestive tract (UAT) is the first line of defense against environmental stresses such as antigens, microbes, inhalants, foods, etc., and mucins, intracellular junctions, epithelial cells, and immune cells are the major constituents of this defensive mucosal barrier. Laryngopharyngeal reflux (LPR) is recognized as an independent risk factor for UAT mucosal disorders, and in this review, we describe the components and functions of the mucosal barrier and the results of LPR-induced mucosal inflammation in the UAT. We discuss the interactions between the refluxate and the mucosal components and the mechanisms through which these damaging events disrupt and alter the mucosal barriers. In addition, we discuss the dynamic alterations in the mucosal barrier that might be potential therapeutic targets for LPR-induced disorders.

Bronchoalveolar lavage: role in the evaluation of pulmonary interstitial disease

INTRODUCTION

Bronchoalveolar lavage (BAL), a noninvasive, well-tolerated procedure is an important diagnostic tool that can facilitate the diagnosis of various lung diseases. This procedure allows the assessment of large alveolar compartments, by providing cells as well as non-cellular constituents from the lower respiratory tract. Alterations in BAL fluid and cells ratio reflects pathological changes in the lung parenchyma. In some cases, clinicians use BAL as a differential diagnosis guide for interstitial lung disease.

AREAS COVERED

In this review, we summarized the diagnostic criteria for BAL in interstitial lung diseases, pulmonary infections, lung cancer and other pathologies such as fat embolism, gastroesophageal reflux and collagen vascular disease. For this review, we have selected scientific papers published in the PubMed database in our area of interest. We aimed to highlight the usefulness of BAL in respiratory pathology.

EXPERT OPINION

Although BAL fluid analyzes has an essential role in the diagnostic work-up of many lung pathologies, it should be performed in selected patients. For accurate results, the BAL technique is very important to be standardized.

Oil red O staining for lipid-laden macrophage index of bronchoalveolar lavage: interobserver agreement and challenges to interpretation

INTRODUCTION

Oil Red O (ORO) staining on cytologic specimens with calculation of the lipid-laden macrophage index (LLMI) is used as a part of the workup in a number of clinical settings, particularly when aspiration is of concern. As a part of ongoing internal quality improvement measures, the objective of the present study was to evaluate the interobserver agreement of the LLMI calculation and to identify factors that affect the variability of the calculation.

MATERIALS AND METHODS

There were 9 study participants, which included 3 trainees, 3 cytotechnologists, and 3 cytopathologists. Each participant reviewed 100 ORO-stained bronchoalveolar lavage slides and assigned an LLMI score to each case. The scores were categorized into 3 groups according to the associated aspiration risk: low, LLMI <40; intermediate, LLMI 40 to 90; and high, LLMI >90. The participants were also requested to note any challenges to the calculation for each case.

RESULTS

The interobserver agreement among all participants was fair (κ = 0.23). Stratified by participant group, the interobserver agreement among the trainees was fair (κ = 0.24), among cytotechnologists was fair (κ = 0.32), and among cytopathologists was moderate (κ = 0.60). In 70 cases, at least one participant scored the case at least one category higher than the other participants; in 47 cases there was a two category difference. A primary diagnostic challenge reported by participants was macrophage pigmentation (hemosiderin, anthracosis).

CONCLUSIONS

We found only fair interobserver agreement among all 9 participants in the study. Hemosiderin and anthracotic pigmentation was a major factor impeding LLMI calculation resulting in overestimation of the LLMI.

Sputum proteomic signature of gastro-oesophageal reflux in patients with severe asthma

Gastro-oesophageal reflux disease (GORD) has long been associated with poor asthma control without an established cause-effect relationship. 610 asthmatics (421 severe/88 mild-moderate) and 101 healthy controls were assessed clinically and a subset of 154 severe asthmatics underwent proteomic analysis of induced sputum using untargeted mass spectrometry, LC-IMS-MS^E. Univariate and multiple logistic regression analyses (MLR) were conducted to identify proteins associated with GORD in this cohort. When compared to mild/moderate asthmatics and healthy individuals, respectively, GORD was three- and ten-fold more prevalent in severe asthmatics and was associated with increased asthma symptoms and oral corticosteroid use, poorer quality of life, depression/anxiety, obesity and symptoms of sino-nasal disease. Comparison of sputum proteomes in severe asthmatics with and without active GORD showed five differentially abundant proteins with described roles in anti-microbial defences, systemic inflammation and epithelial integrity. Three of these were associated with active GORD by multiple linear regression analysis: Ig lambda variable 1-47 (p = 0·017) and plasma protease C1 inhibitor (p = 0·043), both in lower concentrations, and lipocalin-1 (p = 0·034) in higher concentrations in active GORD. This study provides evidence which suggests that reflux can cause subtle perturbation of proteins detectable in the airways lining fluid and that severe asthmatics with GORD may represent a distinct phenotype of asthma.

Immunometabolism features of metabolic deregulation and cancer

Immunometabolism is a branch dealing at the interface of immune functionalities and metabolic regulations. Considered as a bidirectional trafficking, metabolic contents and their precursors bring a considerable change in immune cells signal transductions which as a result affect the metabolic organs and states as an implication. Lipid metabolic ingredients form a major chunk of daily diet and have a proven contribution in immune cells induction, which then undergo metabolic pathway shuffling inside their ownself. Lipid metabolic states activate relevant metabolic pathways inside immune cells that in turn prime appropriate responses to outside environment in various states including lipid metabolic disorders itself and cancers as an extension. Although data on Immunometabolism are still growing, but scientific community need to adjust and readjust according to recent data on given subject. This review attempts to provide current important data on Immunometabolism and consequently its metabolic ramifications. Incumbent data on various lipid metabolic deregulations like obesity, metabolic syndrome, obese asthma and atherosclerosis are analysed. Further, metabolic repercussions on cancers and its immune modalities are also analysed.

Adult exogenous lipoid pneumonia: A rare and underrecognized entity in cytology - A case series

Background:

Exogenous lipoid pneumonia (ELP) is a rare benign entity without specific clinical or imaging presentation. Although cytological studies – either bronchoalveolar lavage (BAL) or fine-needle aspiration (FNA) – may be pursued in patients with ELP, a definitive diagnosis is frequently rendered only on histology. The aim of this study is to highlight the cytological features of ELP.

Methods:

A search of cytopathology (CP) and surgical pathology (SP) diagnoses of ELP was conducted. The corresponding clinical and imaging features were obtained, and the morphology, particularly the presence and size of the intracytoplasmic vacuoles and background, was assessed.

Results:

Nine cases of ELP were identified, including eight with corresponding CP and SP. A neoplasm was suspected in three based on imaging, but ELP was not in the differential clinically or radiographically in any. Among the cases, six patients had BALs and three FNAs. All of the samples showed multiple large vacuoles within macrophages with at least some equal to or larger than the size of the cell nucleus. Similar vacuoles were noted extracellularly on smears.

Conclusions:

ELP is typically described in case reports in the clinical or radiological literature. To the best of our knowledge, this represents the largest series of adult ELP in CP. When large vacuoles are present in macrophages in cytology specimens, at least a suspicion of ELP can be suggested to initiate appropriate therapy, identify/remove the inciting agent, and preclude a more invasive procedure.

Acute Chest Syndrome in Children with Sickle Cell Disease

Acute chest syndrome (ACS) is a frequent cause of acute lung disease in children with sickle cell disease (SCD). Patients may present with ACS or may develop this complication during the course of a hospitalization for acute vaso-occlusive crises (VOC). ACS is associated with prolonged hospitalization, increased risk of respiratory failure, and the potential for developing chronic lung disease. ACS in SCD is defined as the presence of fever and/or new respiratory symptoms accompanied by the presence of a new pulmonary infiltrate on chest X-ray. The spectrum of clinical manifestations can range from mild respiratory illness to acute respiratory distress syndrome. The presence of severe hypoxemia is a useful predictor of severity and outcome. The etiology of ACS is often multifactorial. One of the proposed mechanisms involves increased adhesion of sickle red cells to pulmonary microvasculature in the presence of hypoxia. Other commonly associated etiologies include infection, pulmonary fat embolism, and infarction. Infection is a common cause in children, whereas adults usually present with pain crises. Several risk factors have been identified in children to be associated with increased incidence of ACS. These include younger age, severe SCD genotypes (SS or Sβ⁰ thalassemia), lower fetal hemoglobin concentrations, higher steady-state hemoglobin levels, higher steady-state white blood cell counts, history of asthma, and tobacco smoke exposure. Opiate overdose and resulting hypoventilation can also trigger ACS. Prompt diagnosis and management with intravenous fluids, analgesics, aggressive incentive spirometry, supplemental oxygen or respiratory support, antibiotics, and transfusion therapy, are key to the prevention of clinical deterioration. Bronchodilators should be considered if there is history of asthma or in the presence of acute bronchospasm. Treatment with hydroxyurea should be considered for prevention of recurrent episodes. This review evaluates the etiology, pathophysiology, risk factors, clinical presentation of ACS, and preventive and treatment strategies for effective management of ACS.

Integrating Lung Physiology, Immunology, and Tuberculosis

Lungs are directly exposed to the air, have enormous surface area, and enable gas exchange in air-breathing animals. They are constantly 'attacked' by microbes from both outside and inside and thus possess a unique, highly regulated local immune defense system which efficiently allows for microbial clearance while minimizing damaging inflammatory responses. As a prototypic host-adapted airborne pathogen, Mycobacterium tuberculosis traverses the lung and has several 'interaction points' (IPs) which it must overcome to cause infection. These interactions are critical, not only from a pathogenesis perspective but also in considering the effectiveness of therapies and vaccines in the lungs. Here we discuss emerging views on immunologic interactions occurring in the lungs for M. tuberculosis and their impact on infection and persistence.

Three-dimensional micro computed tomography analysis of the lung vasculature and differential adipose proteomics in the Sugen/hypoxia rat model of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare disease characterized by significant vascular remodeling. The obesity epidemic has produced great interest in the relationship between small visceral adipose tissue depots producing localized inflammatory conditions, which may link metabolism, innate immunity, and vascular remodeling. This study used novel micro computed tomography (microCT) three-dimensional modeling to investigate the degree of remodeling of the lung vasculature and differential proteomics to determine small visceral adipose dysfunction in rats with severe PAH. Sprague-Dawley rats were subjected to a subcutaneous injection of vascular endothelial growth factor receptor blocker (Sugen 5416) with subsequent hypoxia exposure for 3 weeks (SU/hyp). At 12 weeks after hypoxia, microCT analysis showed a decrease in the ratio of vascular to total tissue volume within the SU/hyp group (mean ± standard deviation: 0.27 ± 0.066; P = 0.02) with increased vascular separation (0.37 ± 0.062 mm; P = 0.02) when compared with the control (0.34 ± 0.084 and 0.30 ± 0.072 mm). Differential proteomics detected an up-regulation of complement protein 3 (C3; SU/hyp∶control ratio = 2.86) and the adipose tissue-specific fatty acid binding protein-4 (FABP4, 2.66) in the heart adipose of the SU/hyp. Significant remodeling of the lung vasculature validates the efficacy of the SU/hyp rat for modeling human PAH. The upregulation of C3 and FABP4 within the heart adipose implicates small visceral adipose dysfunction. C3 has been associated with vascular stiffness, and FABP4 suppresses peroxisome proliferator-activated receptor, which is a major regulator of adipose function and known to be downregulated in PAH. These findings reveal that small visceral adipose tissue within the SU/hyp model provides mechanistic links for vascular remodeling and adipose dysfunction in the pathophysiology of PAH.

The effects of exogenous lipid on THP-1 cells: an in vitro model of airway aspiration?

Chronic inflammatory diseases of the airways are associated with gastro-oesophageal reflux (GOR) and aspiration events. The observation of lipid-laden macrophages (LLMs) within the airway may indicate aspiration secondary to GOR. The proposed mechanism, that lipid droplets from undigested or partially digested food are aspirated leading to accumulation in scavenging macrophages, led us to hypothesise that an activated population of LLMs could interact with other immune cells to induce bronchial inflammation. To test this, we generated an in vitro model using differentiated THP-1 cells, which were treated with a high-fat liquid feed. Here, we show that THP-1 cells can take up lipid from the high-fat feed independent of actin polymerisation or CD36-dependent phagocytosis. These cells did not exhibit M1 or M2 polarisation. Gene array analysis confirmed over 8000 genes were upregulated by at least twofold following high fat exposure, and IL-8 was the most upregulated gene. Pathway analysis revealed upregulation of genes known to be involved in chronic obstructive pulmonary disease (COPD) pathophysiology. We suggest that aspiration and macrophage phagocytosis may be important mechanisms in the aetiology of diseases such as COPD and cystic fibrosis that are characterised by high levels of IL-8 within the airways.

Comparative pulmonary toxicity of inhaled metalworking fluids in rats and mice

Metalworking fluids (MWFs) are complex formulations designed for effective lubricating, cooling, and cleaning tools and parts during machining operations. Adverse health effects such as respiratory symptoms, dermatitis, and cancer have been reported in workers exposed to MWFs. Several constituents of MWFs have been implicated in toxicity and have been removed from the formulations over the years. However, animal studies with newer MWFs demonstrate that they continue to pose a health risk. This investigation examines the hypothesis that unrecognized health hazards exist in currently marketed MWF formulations that are presumed to be safe based on hazard assessments of individual ingredients. In vivo 13-week inhalation studies were designed to characterize and compare the potential toxicity of four MWFs: Trim VX, Cimstar 3800, Trim SC210, and Syntilo 1023. Male and female Wistar Han rats or Fischer 344N/Tac rats and B6C3F1/N mice were exposed to MWFs via whole-body inhalation at concentrations of 0, 25, 50, 100, 200, or 400 mg/m³ for 13 weeks, after which, survival, body and organ weights, hematology and clinical chemistry, histopathology, and genotoxicity were assessed following exposure. Although high concentrations were used, survival was not affected and toxicity was primarily within the respiratory tract of male and female rats and mice. Minor variances in toxicity were attributed to differences among species as well as in the chemical components of each MWF. Pulmonary fibrosis was present only in rats and mice exposed to Trim VX. These data confirm that newer MWFs have the potential to cause respiratory toxicity in workers who are repeatedly exposed via inhalation.