Phagocytic Function Of Alveolar Macrophages Research Articles

Chronic exposure of biomass ambient particulate matter induces signal-regulatory protein α (SIRPα) and surfactant protein D expression in rat alveolar macrophages

Objective: To observe the expression of signal-regulatory protein α (SIRPα), surfactant protein (SP) A, and SPD by, and the phagocytic function of alveolar macrophages (AMs) in the rats exposed to biomass ambient particulate matter (BMF). Methods: Seventy-two male SD rats were randomly divided into BMF group and clean air group. Protein levels of SIRPα, SPA, and SPD in AMs were determined by Western blotting and immunofluorescent assay after 4 days, 1 month, and 6 months of BMF exposure. Fluorescent labeled Glucose aureus and Pseudomonas aeruginosa were used to detect the phagocytic ability of AMs in rats at three time points. Results: After 4 days of BMF exposure, there was no significant difference in the protein levels of SIRPα and SPD compared with the clean air group (P>0.05). The relative levels of SIRPα and SPD were (1.73±0.64) and (2.01±0.78) at 1 month of BMF exposure, and those at 6 months of BMF exposure were (1.49±0.28) and (1.48±0.34), both of which were higher than those in the clean air group (P<0.05). The relative level of Staphylococcus aureus median fluorescence intensity (MFI) and Pseudomonas aeruginosa MFI at 1 month BMF group were (0.56±0.16) and (0.80±0.09), and those at 6 months BMF group were (0.67±0.11) and (0.76±0.16), both of which were lower than those in clean air group, and the difference was statistically significant (P<0.05). Conclusions: BMF induces upregulation of SIRPα and SPD in AMs and inhibits the phagocytosis of AMs.

Pioglitazone improves alcohol-induced alveolar macrophage phagocytic dysfunction via increases in microRNAs-1264 and -107.

Abstract Objective: People with a history of alcohol use disorders (AUD) are 2–4 times more likely to develop lung infections, in part due to impaired alveolar macrophage (AM) immune function. Ethanol (EtOH) induces oxidative stress via increases in NAPDH oxidase (Nox)1 and Nox2 and decreases in peroxisome proliferator-activated receptor (PPAR)γ, leading to AM phagocytic dysfunction. Since PPARγ activation with its ligand pioglitazone (PIO) attenuated acute lung injury, we hypothesized that PIO upregulates Nox1-related microRNA (miR)-1264 and Nox2-related miR-107, thereby lowering Nox1 and Nox2 expression and oxidative stress and improving AM phagocytic function. Methods: AM were isolated from C57BL/6J mice fed EtOH (20% w/v) in the drinking water for 12 wks ± PIO (10 mg/kg/day by oral gavage during week 12). In parallel, a mouse AM cell line, MH-S cells, were transfected ± 50 nM miR-1264/-107 mimics and treated ± 0.08% EtOH for 3 d ± 10 μM PIO on day 3. miR-1264 and -107 were assessed by qRT-PCR. Nox1 and Nox2 mRNA and protein levels were measured by qRT-PCR and cytoimmunostaining. Oxidative stress was assessed with DCFH-DA and Amplex Red assays. AM phagocytosis was evaluated by S. aureus internalization. Results: In vivo and in vitro, EtOH: decreased miR-1264/-107 levels, increased Nox1 and Nox2 expression, enhanced oxidative stress, and impaired phagocytosis. miR-1264/-107 mimics or PIO reversed these EtOH-induced AM derangements. Conclusions: PIO rapidly upregulated miRs-1264/-107 and attenuated EtOH-induced AM oxidative stress and phagocytic dysfunction. Our studies suggest PIO as a clinically relevant intervention to mitigate AM immune derangements and may decrease susceptibility of lung infections in people with a history of AUD.

Phagocytosis of alveolar macrophages is suppressed in a mouse model of lipopolysaccharide-induced acute lung injury

To investigate the changes in phagocytic function of alveolar macrophages (AMs) in mice with lipopolysaccharide (LPS)-induced acute lung injury (ALI) and explore the possible mechanism. Kunming mice were randomly divided into normal control group and ALI (induced by LPS instillation in the airway) model group. AMs were obtained from bronchoalveolar lavage fluid in both groups, and phagocytosis of the AMs was observed using flow cytometry and fluorescence microscopy. Western blotting and ELISA were used to detect the expression and secretion of IL-33 in the lung tissue of the mice. We also detected the secretion of IL-33 by an alveolar epithelial cell line MLE-12 in response to stimulation with different concentrations of LPS. The AMs from the normal control mice were treated with different concentrations of LPS and IL-33, and the changes in the phagocytic activity of the cells were observed. Compared with those in normal control group, the percentage of AMs phagocytosing fluorescent microspheres was significantly decreased, and the expression of IL-33 in lung tissue and IL-33 level in the bronchoalveolar lavage fluid were significantly increased in ALI mice (P < 0.01). LPS (100-1000 ng/mL) obviously promoted the secretion of IL-33 in cultured MLE-12 cells (P < 0.01). Both LPS (10-500 ng/mL) and IL-33 (100 ng/mL) significantly inhibited the phagocytic activity of the AMs from normal control mice (P < 0.01). The phagocytic activity of AMs is weakened in ALI mice possibly due to direct LPS stimulation and the inhibitory effect of the alarmin IL-33 produced by LPS-stimulated alveolar epithelial cells.

Exposure to diesel exhaust particles increases susceptibility to invasive pneumococcal disease

BackgroundThe World Health Organization estimates that air pollution is responsible for 7 million deaths per annum, with 7% of these attributable to pneumonia. Many of these fatalities have been linked to exposure to high levels of airborne particulates, such as diesel exhaust particles (DEPs).ObjectivesWe sought to determine whether exposure to DEPs could promote the progression of asymptomatic nasopharyngeal carriage of Streptococcus pneumoniae to invasive pneumococcal disease.MethodsWe used mouse models and in vitro assays to provide a mechanistic understanding of the link between DEP exposure and pneumococcal disease risk, and we confirmed our findings by using induced sputum macrophages isolated from healthy human volunteers.ResultsWe demonstrate that inhaled exposure to DEPs disrupts asymptomatic nasopharyngeal carriage of S pneumoniae in mice, leading to dissemination to lungs and blood. Pneumococci are transported from the nasopharynx to the lungs following exposure to DEPs, leading to increased proinflammatory cytokine production, reduced phagocytic function of alveolar macrophages, and consequently, increased pneumococcal loads within the lungs and translocation into blood. These findings were confirmed by using DEP-exposed induced sputum macrophages isolated from healthy volunteers, demonstrating that impaired innate immune mechanisms following DEP exposure are also at play in humans.ConclusionLung inhaled DEPs increase susceptibility to pneumococcal disease by leading to loss of immunological control of pneumococcal colonisation, increased inflammation, tissue damage, and systemic bacterial dissemination.

The effect of fine particles on the phagocytosis of alveolar macrophages potentially by Arp2/3 complex in a mouse model of chronic obstructive pulmonary disease

Objective: To investigate the mechanism of fine particulate matter (PM2.5) on the phagocytosis of alveolar macrophages (AM) in mice with chronic obstructive pulmonary disease (COPD) through actin-related protein (Arp) 2/3 complex. Methods: Forty mice were divided into healthy control(A) group, healthy PM2.5 (B) group, COPD(C) group, and COPD PM2.5(D) group according to the random number table method. A mouse model of COPD was established by cigarette smoke exposure method. PM2.5 (662 μg/m(3)) model was established by continuously inhalation for 90 days in healthy PM2.5 group and COPD PM2.5 group. Flow cytometry was used to detect the ability of AM to phagocytose fluorescein isothiocyanate-labeled E.coli (FITC-E.coli), expressed as mean fluorescence intensity (MFI) and percentage of phagocytic positive cells (phagocytosis percentage); Western blotting was used to detect AM Arp2 and F-actin content, and laser confocal microscopy for AM Arp2 and F-actin and phagocytic FITC-E.coli average optical density and colocalization of Arp2 and F-actin, while scanning electron microscopy was used to observes the morphology of AM after phagocytizing FITC-E.coli. Results: AM phagocytosis: MFI and phagocytosis percentage in the COPD group [4 656±251, (31.9±1.7)%] were lower than the healthy control group [8 657±247, (65.7±1.9)%] (both P<0.01); and healthy PM2.5 group and COPD PM2.5 group [7 653±228, (47.9±1.6)% and 3 660±237, (19.2±1.2)%] were lower than the respective control groups (all P<0.01), and the decrease in the COPD group was more pronounced. AM Arp2, F-actin content: the COPD group (0.51±0.02, 0.46±0.03) were lower than the healthy control group (0.81±0.04, 0.71±0.04, both P<0.01); the healthy PM2.5 group and the COPD PM2.5 group [(0.64±0.03, 0.56±0.04) and (0.29±0.02, 0.26±0.02)] were lower than the respective control groups (all P<0.01), and the decrease in COPD group was more significant. Arp2, F-actin, and phagocytic FITC-E.coli mean optical density values: the COPD group (33.0±2.3, 62.0±0.7, 41.0±0.4) were lower than the healthy control group (141.0±4.2, 145.0±2.9, 189.0±2.6, both P<0.01); the healthy PM2.5 group and the COPD PM2.5 group (127.0±2.8, 124.0±0.7, 154.0±0.9, and 24.0±2.4, 37.0±0.4, 29.0±0.8) were lower than the respective control groups (all P<0.01), and the decrease in the COPD group was more significant. Colocalization of AM Arp2 and F-actin: Montessori colocalization coefficient (MOC) (0.38±0.03) in the COPD group was lower than the healthy control group (0.88±0.03, P<0.01); healthy PM2.5 group and COPD PM2.5 group [(0.58±0.03) and (0.14±0.02)] were lower than the respective control groups (both P<0.01), and the decrease in COPD group was more significant. Morphology of AM phagocytosis of FITC-E.coli: AM in the healthy control group was obviously deformed, and the surface of the cell membrane was slightly wrinkled and high, and the free edge of the micro-pleated fold had a long and dense filamentous pseudopodia extension. The changes of morphology of AM in the COPD group was not obvious, the micro-wrinkles on the surface of the cell membrane were rare, and the filopodia poorly extended or even absent. The AM form of the healthy PM2.5 group changed slightly, mostly irregular circular or elliptical. The micro-wrinkles on the surface of the cell membrane were less and flat, and the filopodia protrudes short and less; the AM form of the COPD PM2.5 group was stiff, and the micro-wrinkles on the surface of the cell membrane were few and flat, no obvious filopodia or protrusions. Correlation analysis: After basal state and PM2.5 intervention, AM Arp2, F-actin content and MOC values of Arp2 and F-actin were positively correlated with MFI. Conclusions: The phagocytic function of AM in COPD mice was low, which was related to the abnormal rearrangement of cytoskeleton involved in Arp2/3 complex and F-actin. It was speculated that PM2.5 might inhibit Arp2/3 complex and F-actin. The cytoskeletal rearrangement of proteins was involved in the aggravation of AM phagocytosis in mice with COPD.

Hydrogen gas inhalation enhances alveolar macrophage phagocytosis in an ovalbumin-induced asthma model

BackgroundMaintaining an airway clear of bacteria, foreign particles and apoptotic cells by alveolar macrophages is very essential for lung homeostasis. In asthma, the phagocytic capacity of alveolar macrophages is significantly reduced, which is thought to be associated with increased oxidative stress. Hydrogen (H2) has been shown to exert potent antioxidant and anti-inflammatory effects, yet its effects on phagocytosis of alveolar macrophages are unknown. This study is aimed to evaluate the beneficial effects of hydrogen gas inhalation on alveolar macrophage phagocytosis in an ovalbumin (OVA)-induced murine asthma model. MethodsFemale C57BL/6 mice were intraperitoneally sensitized with OVA before they were subject to airway challenge with aerosolized OVA. Hydrogen gas was delivered to the mice through inhalation twice a day (2 h once) for 7 consecutive days. Phagocytic function of alveolar macrophages isolated from bronchoalveolar lavage fluid was assessed by fluorescence-labeled Escherichia coli as well as flow cytometry. ResultsAlveolar macrophages isolated from OVA-induced asthmatic mice showed decreased phagocytic capacity to Escherichia coli when compared with those of control mice. Defective phagocytosis in asthmatic mice was reversed by hydrogen gas inhalation. Hydrogen gas inhalation significantly alleviated OVA-induced airway hyperresponsiveness, inflammation and goblet cell hyperplasia, diminished TH2 response and decreased IL-4 as well as IgE levels, reduced malondialdehyde (MDA) production and increased superoxide dismutase (SOD) activity. Concomitantly, hydrogen gas inhalation inhibited NF-κB activation and markedly activated Nrf2 pathway in OVA-induced asthmatic mice. ConclusionsOur findings demonstrated that hydrogen gas inhalation enhanced alveolar macrophage phagocytosis in OVA-induced asthmatic mice, which may be associated with the antioxidant effects of hydrogen gas and the activation of the Nrf2 pathway.

Reduced transient receptor potential vanilloid 2 expression in alveolar macrophages causes COPD in mice through impaired phagocytic activity

BackgroundDefective phagocytosis in alveolar macrophages is associated with chronic obstructive pulmonary disease (COPD). Transient receptor potential cation channel subfamily V member 2 (TRPV2), a type of nonselective cation channel pertinent to diverse physiological functions, regulates macrophage phagocytosis. However, the role of TRPV2 in COPD remains poorly understood. Here, we explored the role of TRPV2 in the development of COPD.MethodsMacrophage TRPV2 expression and phagocytosis function were measured in MH-S cells (a murine alveolar macrophage cell line) and a cigarette smoke exposure mouse model.ResultsTRPV2 expression and phagocytosis function were reduced when MH-S cells were exposed to cigarette smoke extract (CSE). TRPV2 knockdown by siRNA decreased phagocytosis in MH-S cells. Consistently, TRPV2 expression was reduced in alveolar macrophages prepared from bronchoalveolar lavage samples of mice which were exposed to cigarette smoke for 2 months. In addition, the alveolar space was progressively enlarged during development in TRPV2 knockout (TRPV2KO) mice. Moreover, exposure to cigarette smoke for 2 months significantly induced alveolar space enlargement in TRPV2KO mice, but not in wild-type (WT) mice. The phagocytic function of alveolar macrophages from TRPV2KO mice was reduced, compared with macrophages from WT mice.ConclusionsTRPV2 expression is profoundly downregulated in alveolar macrophages at early time points of cigarette smoke exposure. Reduced TRPV2-mediated phagocytic function renders the lung susceptible to cigarette smoke-induced alveolar space enlargement. TRPV2 may provide a therapeutic target for COPD induced by cigarette smoke.

Alveolar Macrophage Phagocytosis and Bacteria Clearance in Mice.

Alveolar macrophages (AMs) guard the alveolar space of the lung. Phagocytosis by AMs plays a critical role in the defense against invading pathogens, the removal of dead cells or foreign particles, and in the resolution of inflammatory responses and tissue remodeling, processes that are mediated by various surface receptors of the AMs. Here, we report methods for the analysis of the phagocytic function of AMs using in vitro and in vivo assays and experimental strategies to differentiate between the pattern recognition receptor-, complement receptor-, and Fc gamma receptor-mediated phagocytosis. Finally, we discuss a method to establish and characterize a P. aeruginosa pneumonia model in mice to assess bacterial clearance in vivo. These assays represent the most common methods to evaluate AM functions and can also be used to study macrophage function and bacterial clearance in other organs.

Oxidative stress in critically ill ventilated adults: effects of vitamin D3 and associations with alveolar macrophage function.

BackgroundDisruptions in redox balance lead to oxidative stress, a promoter of morbidity in critical illness. This study aimed to: 1) characterize the plasma and alveolar thiol/disulfide redox pools, 2) examine their associations with alveolar macrophage phagocytosis, and 3) determine the effect of high dose vitamin D3 on plasma thiol/disulfide redox.MethodsSubjects were 30 critically ill, ventilated adults in a double-blind randomized trial of high-dose (250 000 or 500 000 IU) vitamin D3 or placebo. Baseline bronchoalveolar lavage fluid (BALF) samples were analyzed for determination of alveolar phagocytosis index (PI) and for concentrations of glutathione (GSH), glutathione disulfide (GSSG), cysteine (Cys), cystine (CySS), and their respective redox potentials (EhGSSG and EhCySS). Plasma redox outcomes were assessed at baseline and days 7 and 14.ResultsBaseline plasma Cys was inversely associated with alveolar PI (ρ = −0.69, P=0.003), and EhCySS was positively associated with PI (ρ = 0.61, P=0.01). Over time, among all subjects there was an increase in plasma GSH levels and a decrease in EhGSSG (P<0.01 for both), with no difference by treatment group. Vitamin D3 decreased oxidized plasma GSSG to a more normal state (P for group × time=0.009).ConclusionsOxidative stress indicators were positively associated with alveolar macrophage phagocytic function in acutely ill ventilated adults. High-dose vitamin D3 decreased plasma GSSG concentrations, which suggests that vitamin D can possibly improve the oxidative stress environment.

Disrupted epithelial/macrophage crosstalk via Spinster homologue 2-mediated S1P signaling may drive defective macrophage phagocytic function in COPD.

IntroductionWe have previously established a link between impaired phagocytic capacity and deregulated S1P signaling in alveolar macrophages from COPD subjects. We hypothesize that this defect may include a disruption of epithelial-macrophage crosstalk via Spns2-mediated intercellular S1P signaling.MethodsPrimary alveolar macrophages and bronchial epithelial cells from COPD subjects and controls, cell lines, and a mouse model of chronic cigarette smoke exposure were studied. Cells were exposed to 10% cigarette smoke extract, or vehicle control. Spns2 expression and subcellular localization was studied by immunofluorescence, confocal microscopy and RT-PCR. Phagocytosis was assessed by flow-cytometry. Levels of intra- and extracellular S1P were measured by S1P [3H]-labeling.ResultsSpns2 expression was significantly increased (p<0.05) in alveolar macrophages from current-smokers/COPD patients (n = 5) compared to healthy nonsmokers (n = 8) and non-smoker lung transplant patients (n = 4). Consistent with this finding, cigarette smoke induced a significant increase in Spns2 expression in both human alveolar and THP-1 macrophages. In contrast, a remarkable Spns2 down-regulation was noted in response to cigarette smoke in 16HBE14o- cell line (p<0.001 in 3 experiments), primary nasal epithelial cells (p<0.01 in 2 experiments), and in smoke-exposed mice (p<0.001, n = 6 animals per group). Spns2 was localized to cilia in primary bronchial epithelial cells. In both macrophage and epithelial cell types, Spns2 was also found localized to cytoplasm and the nucleus, in line with a predicted bipartile Nuclear Localization Signal at the position aa282 of the human Spns2 sequence. In smoke-exposed mice, alveolar macrophage phagocytic function positively correlated with Spns2 protein expression in bronchial epithelial cells.ConclusionOur data suggest that the epithelium may be the major source for extracellular S1P in the airway and that there is a possible disruption of epithelial/macrophage cross talk via Spns2-mediated S1P signaling in COPD and in response to cigarette smoke exposure.

Effects of PM2.5 on phagocytic function of alveolar macrophages in chronic obstructive pulmonary disease mice

To investigate the effects of fine particulate matter with a mean aerodynamic diameter ≤2.5 μm (PM2.5) collected from Lanzhou city on phagocytic function of alveolar macrophages (AM) in chronic obstructive pulmonary disease (COPD) mice. Forty male mice were randomly divided into four groups: healthy group, healthy PM2.5 group, COPD group and COPD PM2.5 group. COPD mice were established by cigarette smoking. PM2.5 (10 mg/kg) collected by air sampler was intratracheally instilled in healthy PM2.5 group and COPD PM2.5 group. Mice were sacrificed after 14 days, and alveolar macrophages (AM) were isolated. Mean fluorescence intensity (MFI) and the positive percent of alveolar macrophages engulfing flurescein isothiocyanate-labeled Escherichia coli (FITC-E.coli) (AM%) were detected by flow cytometry. Total antioxidative capacity (TAC) was measured by O-phenanthroline colorimetry. Malondialdehyde (MDA) was measured by thiobarbiturieacid colorimetry and myeloperoxidase (MPO) was measured by O-dianisidine colorimetry. The peak inspiratory flow (PIF), peak expiratory flow (PEF) and dynamic compliance (Cdyn) of COPD group were significantly lower than healthy control group. The pathology of COPD group showed disruption of alveolar septa, formation of emphysema, and that the number of alveoli had a significant reduction. The MFI and AM% in COPD group were significant lower than healthy group (14.1±1.7 vs 43.2±6.1, 9.2%±2.3% vs 69.1%±8.3%)(all P<0.01). Comparing to healthy group and COPD group, the MFI and AM% in healthy PM2.5 group (20.3±4.5, 40.4%±4.4%) and COPD PM2.5 group (7.5±1.3, 6.0%±2.2%) were respectively lowered. The level of TAC in COPD group was significantly lower than healthy group [(3.10±0.64) vs (15.43±0.69)U/mg], the levels of MDA and MPO in COPD group were higher than healthy group[(2.72±0.13) vs (1.31±0.16) nmol/mg, (1.63±0.11) vs (0.92±0.13)U/g] (all P<0.01). In both healthy PM2.5 group and COPD PM2.5 group, the levels of TAC [(6.75±1.06), (2.34±0.61) U/mg] were lower than their corresponding control group; while the levels of MDA [(1.96±0.31), (3.20±0.19) nmol/mg] and the levels of MPO [(1.01±0.19), (1.74±0.13) U/g] were increased (all P<0.01). For the COPD group at baseline and after the intervention of PM2.5, the MFI and AM% showed positive correlation with the levels of TAC, and negative correlation with the levels of MDA , and negative correlation with the levels of MPO (all P<0.05). For health group at baseline and after the intervention PM2.5, the above relationships still existed (all P<0.05). PM2.5 can damage phagocytosis of AM and exacerbate oxidative stress in COPD mice, and AM phagocytosis impairment by PM2.5 is closely associated with oxidative stress.

Potential Link between the Sphingosine-1-Phosphate (S1P) System and Defective Alveolar Macrophage Phagocytic Function in Chronic Obstructive Pulmonary Disease (COPD).

IntroductionWe previously reported that alveolar macrophages from patients with chronic obstructive pulmonary disease (COPD) are defective in their ability to phagocytose apoptotic cells, with a similar defect in response to cigarette smoke. The exact mechanisms for this defect are unknown. Sphingolipids including ceramide, sphingosine and sphingosine-1-phosphate (S1P) are involved in diverse cellular processes and we hypothesised that a comprehensive analysis of this system in alveolar macrophages in COPD may help to delineate the reasons for defective phagocytic function.MethodsWe compared mRNA expression of sphingosine kinases (SPHK1/2), S1P receptors (S1PR1-5) and S1P-degrading enzymes (SGPP1, SGPP2, SGPL1) in bronchoalveolar lavage-derived alveolar macrophages from 10 healthy controls, 7 healthy smokers and 20 COPD patients (10 current- and 10 ex-smokers) using Real-Time PCR. Phagocytosis of apoptotic cells was investigated using flow cytometry. Functional associations were assessed between sphingosine signalling system components and alveolar macrophage phagocytic ability in COPD. To elucidate functional effects of increased S1PR5 on macrophage phagocytic ability, we performed the phagocytosis assay in the presence of varying concentrations of suramin, an antagonist of S1PR3 and S1PR5. The effects of cigarette smoking on the S1P system were investigated using a THP-1 macrophage cell line model.ResultsWe found significant increases in SPHK1/2 (3.4- and 2.1-fold increases respectively), S1PR2 and 5 (4.3- and 14.6-fold increases respectively), and SGPL1 (4.5-fold increase) in COPD vs. controls. S1PR5 and SGPL1 expression was unaffected by smoking status, suggesting a COPD “disease effect” rather than smoke effect per se. Significant associations were noted between S1PR5 and both lung function and phagocytosis. Cigarette smoke extract significantly increased mRNA expression of SPHK1, SPHK2, S1PR2 and S1PR5 by THP-1 macrophages, confirming the results in patient-derived macrophages. Antagonising SIPR5 significantly improved phagocytosis.ConclusionOur results suggest a potential link between the S1P signalling system and defective macrophage phagocytic function in COPD and advise therapeutic targets.

Glutathione attenuates ethanol-induced alveolar macrophage oxidative stress and dysfunction by downregulating NADPH oxidases

Chronic alcohol abuse increases lung oxidative stress and susceptibility to respiratory infections by impairing alveolar macrophage (AM) function. NADPH oxidases (Nox) are major sources of reactive oxygen species in AMs. We hypothesized that treatment with the critical antioxidant glutathione (GSH) attenuates chronic alcohol-induced oxidative stress by downregulating Noxes and restores AM phagocytic function. Bronchoalveolar lavage (BAL) fluid and AMs were isolated from male C57BL/6J mice (8-10 wk) treated ± ethanol in drinking water (20% wt/vol, 12 wk) ± orally gavaged GSH in methylcellulose vehicle (300 mg x kg(-1) x day(-1), during week 12). MH-S cells, a mouse AM cell line, were treated ± ethanol (0.08%, 3 days) ± GSH (500 μM, 3 days or last 1 day of ethanol). BAL and AMs were also isolated from ethanol-fed and control mice ± inoculated airway Klebsiella pneumoniae (200 colony-forming units, 28 h) ± orally gavaged GSH (300 mg/kg, 24 h). GSH levels (HPLC), Nox mRNA (quantitative RT-PCR) and protein levels (Western blot and immunostaining), oxidative stress (2',7'-dichlorofluorescein-diacetate and Amplex Red), and phagocytosis (Staphylococcus aureus internalization) were measured. Chronic alcohol decreased GSH levels, increased Nox expression and activity, enhanced oxidative stress, impaired phagocytic function in AMs in vivo and in vitro, and exacerbated K. pneumonia-induced oxidative stress. Although how oral GSH restored GSH pools in ethanol-fed mice is unknown, oral GSH treatments abrogated the detrimental effects of chronic alcohol exposure and improved AM function. These studies provide GSH as a novel therapeutic approach for attenuating alcohol-induced derangements in AM Nox expression, oxidative stress, dysfunction, and risk for pneumonia.

Effects of pulmonary surfactant on alveolar macrophage function after pulmonary contusion

Objective To observe the effects of porcine pulmonary surfactant(PPS) on the function of pulmonary alveolar macrophages(AMs) in vitro,so as to explore the mechanism by which PPS treating pulmonary contusion in rats. Methods AMs were separated by adherent culture from bronchoalveolar lavage fluid of rats with pulmonary contusion.The AMs were then cultured with media containing PPS(100 μg/ml or 200 μg/ml),LPS(20 μg/ml)+PPS(100 μg/ml or 200 μg/ml),or LPS(20 μg/ml) alone for 2 h.Then the phagocytic function of AMs in each group was examined with fungus.TNF-α mRNA was determined by RT-PCR in AMs of each group.AMs untreated with PPS and LPS were taken as blank control. Results The phagocytic function of the AMs and the expression of TNF-α mRNA were not significantly affected by PPS alone compared with the control group.LPS stimulation increased the phagocytic function of AMs and the TNF-α mRNA expression in AMs.PPS showed no significant effect on LPS-induced increase of phagocytic function of AMs,but it could greatly inhibit LPS-induced TNF-α mRNA increase. Conclusion PPS has no noticeable effect on the phagocytic function of the AMs,but it can inhibit TNF-α mRNA expression induced by LPS in AMs.

Comparative study of respiratory tract immune toxicity induced by three sterilisation nanoparticles: Silver, zinc oxide and titanium dioxide

Silver, zinc oxide, and titanium dioxide nanoparticles are used as sterilisation materials to enhance the performance of disinfectants. We investigated the respiratory tract immune toxicity (“immunotoxicity”) of these nanoparticles in vivo and in vitro, and we explored the relationships between particle size, particle shape, chemical composition, chemical stability and the toxicological effects of these typical nanoparticles in rats. In vivo, the rats were exposed to nanoparticles by intratracheal instillation. Exposure to nanoparticles caused an increase in oxidative injury to the lungs and disorders in regulating the cytokine network, which were detected in the bronchoalveolar lavage fluid, suggesting that oxidative stress might be important for inducing the respiratory immunotoxicity of nanoparticles. In vitro, the phagocytic function of alveolar macrophages (AMs) was dose-dependently reduced by nanoparticles, and ZnO nanoparticles induced greater cytotoxicity than the silver and titanium-dioxide nanoparticles, which were coincident with the results of multiple measurements, such as a cell viability assay by WST-8 and LDH measurements. Comparative analyses demonstrated that particle composition and chemical stability most likely had a primary role in the biological effects of different nanoparticles.

Oxidized phospholipids impair pulmonary antibacterial defenses: Evidence in mice exposed to cigarette smoke

Patients with COPD are associated with poor pulmonary anti-bacterial innate defenses, which increase the risk for frequent acute exacerbations caused by bacterial infection. Despite elevated numbers of phagocytes (macrophages and neutrophils), airways of patients with COPD show stable bacterial colonization. A defect in the phagocytic ability of alveolar macrophages (AMs) is one of the primary reasons for failure to clear the invading bacteria in airways of smokers and COPD patients and also in mice exposed to cigarette smoke (CS). Oxidative stress, as a result of CS exposure is implicated; however, the factors or mediators that inhibit phagocytic activity of AMs in lungs of smokers remain unclear. In the current study, we provide evidence that accumulation of oxidized phospholipids (Ox-PLs) mediate inhibition of phagocytic function of AMs in CS-exposed mice. Mice exposed to 6months of CS showed impaired bacterial phagocytosis and clearance by AMs and elevated levels of Ox-PLs in bronchoalveolar lavage fluid (BALF), compared to mice exposed to room air. Intratracheal instillation of oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OX-PAPC) inhibited phagocytic activity of AMs and impaired pulmonary bacterial clearance in mice. In vitro studies demonstrated that exposure of J774 macrophages to OX-PAPC inhibited bacterial phagocytosis and clearance. However, pre-treatment of OX-PAPC with the monoclonal antibody EO6, which specifically binds to oxidized phospholipid but not native phospholipid, abolished OX-PAPC induced inhibition of bacterial phagocytosis and clearance. Incubation of BALF retrieved from CS-exposed mice impaired bacterial phagocytosis by J774 macrophages, which was abolished by pre-treatment of BALF with the EO6 antibody. In conclusion, our study shows that Ox-PLs generated following chronic CS exposure could play a crucial role in inhibiting phagocytic function of AMs and thus impair pulmonary anti-bacterial innate defenses in CS-exposed mice. Therapeutic approaches that augment pulmonary antioxidant defenses could be beneficial in reducing oxidative stress-driven impairment of phagocytosis by AMs in smokers and COPD patients.

Ethanol (EtOH)‐Induced TGF‐β1 and Reactive Oxygen Species Production Are Necessary for EtOH‐Induced Alveolar Macrophage Dysfunction and Induction of Alternative Activation

Previous studies have shown that chronic ethanol (EtOH) ingestion results in impaired alveolar macrophage function, increased TGF-β(1) production, and decreased antioxidant availability. Similarly, alternative activation (M2 activation) of alveolar macrophages also induces TGF-β(1) production and impairs macrophage function. However, the potential links between EtOH-induced alveolar macrophage derangements, M2 activation, TGF-β(1) production signaling, and oxidant stress have yet to be examined. We hypothesized that EtOH-induced oxidant stress and induction of TGF-β(1) signaling result in alternative activation which subsequently impairs the phagocytic capacity of alveolar macrophages. Primary rat alveolar macrophages and the alveolar macrophages cell line NR8383 were treated with 0.08% EtOH±the antioxidant glutathione (GSH) or a TGF-β(1) neutralizing antibody for 5days. Outcome measures included TGF-β(1) production, reactive oxygen species (ROS) production, phagocytic capacity, and expression of markers of M2 activation. Chronic EtOH treatment greatly decreased alveolar macrophage phagocytic function, increased ROS production, increased TGF-β(1) , and increased expression of markers of M2 activation. GSH supplementation and inhibition of TGF-β(1) signaling during EtOH treatment prevented these alterations. EtOH treatment increased oxidant stress, TGF-β(1) production, and alternative activation in NR8383 cells. However, GSH supplementation and ablation of TGF-β(1) signaling prevented these effects. This suggested that the EtOH-induced switch to an M2 phenotype was a result of decreased antioxidant availability and increased TGF-β(1) signaling. Preventing EtOH-induced induction of alternative activation may improve alveolar macrophage function in alcoholic subjects and decrease the risk of respiratory infections.

HIV-1 transgene expression in rats induces differential expression of tumor necrosis factor alpha and zinc transporters in the liver and the lung

BackgroundHighly effective antiviral treatment can suppress HIV-1 infection, but the chronic effects of HIV-1-related viral proteins, including gp120 and Tat, on organs such as the lungs can be damaging. HIV-1 transgenic rodent models are useful for studying the systemic effects of these proteins independently of viral infection. We have previously shown that HIV-1 transgene expression (and therefore, HIV-1-related protein expression) in rats decreases alveolar macrophage zinc levels and phagocytic capacity by unknown mechanisms. We hypothesized that HIV-1 transgene expression induces chronic inflammation and zinc sequestration within the liver and thereby decreases zinc bioavailability in the lung. We examined the expression of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFα), the zinc storage protein, metallothionein (MT1), and the zinc exporter, ZNT1 in the livers and the lungs of wild type and HIV-1 transgenic rats ± dietary zinc supplementation. In addition, we measured zinc levels, the zinc importing protein ZIP1, and the phagocytic capacity in the alveolar macrophages.ResultsHIV-1 transgene expression increased the liver-specific expression of TNFα, suggesting a chronic inflammatory response within the liver in response to HIV-1-related protein expression. In parallel, HIV-1 transgene expression significantly increased MT1 and ZNT1 expression in the liver as compared to the lung, a pattern that is consistent with zinc sequestration in the liver as occurs during systemic inflammation. Further, HIV-1 transgene expression decreased intracellular zinc levels and increased expression of ZIP1 in the alveolar macrophages, a pattern consistent with zinc deficiency, and decreased their bacterial phagocytic capacity. Interestingly, dietary zinc supplementation in HIV-1 transgenic rats decreased gene expression of TNFα, MT1, and ZNT1 in the liver while simultaneously increasing their expression in the lung. In parallel, zinc supplementation increased alveolar macrophage intracellular zinc levels and bacterial phagocytic capacity in HIV-1 transgenic rats.ConclusionTaken together, these findings suggest that chronic HIV-1-related protein expression causes liver inflammation and zinc sequestration, which in turn limits zinc bioavailability in the lung and thereby impairs alveolar macrophage phagocytic function. Importantly, dietary zinc supplementation decreases liver inflammation and zinc sequestration and restores alveolar macrophage phagocytic function in HIV-1 transgenic rats, a result with potential clinical implications for improving lung health in HIV-1-infected individuals.

Delayed neonatal lung macrophage differentiation in a mouse model of in utero ethanol exposure

We have previously demonstrated that fetal ethanol exposure deranges the function and viability of the neonatal alveolar macrophage. Although altered differentiation of the alveolar macrophage contributes to pulmonary disease states within the adult lung, the effects of fetal ethanol exposure on the normal differentiation of interstitial to alveolar macrophage in the newborn lung are unknown. In the current study, using a mouse model of fetal ethanol exposure, we hypothesized that altered terminal differentiation of the neonatal interstitial to alveolar macrophage contributes to the observed cellular dysfunction in the ethanol-exposed newborn mouse. Control alveolar macrophage differentiation was characterized by increased expression of CD32/CD11b (P < or = 0.05) and increased in vitro phagocytosis of Staphylococcus aureus (P < or = 0.05) compared with interstitial macrophage. After in utero ethanol exposure, both alveolar and interstitial macrophage lacked the acquisition of CD32/CD11b (P < or = 0.05) and displayed impaired in vitro phagocytosis (P < or = 0.05). Ethanol significantly increased transforming growth factor-beta(1) (TGF-beta(1)) in the bronchoalveolar lavage fluid (P < or = 0.05), as well as in both interstitial and alveolar macrophages (P < or = 0.05). Oxidant stress contributed to the ethanol-induced changes on the interstitial and alveolar cells, since maternal supplementation with the glutathione precursor S-adenosylmethionine during ethanol ingestion normalized CD32/CD11b (P < or = 0.05), phagocytosis (P < or = 0.05), and TGF-beta(1) in the bronchoalveolar lavage fluid and macrophages (P < or = 0.05). Contrary to our hypothesis, fetal ethanol exposure did not solely impair interstitial to alveolar macrophage differentiation. Rather, fetal ethanol exposure impaired both neonatal interstitial and alveolar macrophage phagocytic function and differentiation. Increased oxidant stress and elevated TGF-beta(1) contributed to the impaired differentiation of both interstitial and alveolar macrophage.

Response to Inhaled Granulocyte-Macrophage Colony-Stimulating Factor in a Patient With Alveolar Proteinosis

Pulmonary alveolar proteinosis is a rare disease characterized by the accumulation of lipoproteinaceous material derived from alveolar surfactant in the alveoli, with a consequent deterioration in gas exchange. Pathogenesis is related to impaired phagocytic function of alveolar macrophages. In recent years, a new treatment for pulmonary alveolar proteinosis—consisting of subcutaneous administration of granulocytemacrophage colony-stimulating factor (GM-CSF)—has become available. The commonly accepted treatment, and the one to have shown greatest efficacy in pulmonary alveolar proteinosis, is whole lung lavage. Instead of subcutaneous administration, GM-CSF can also be inhaled as an aerosol. This route of administration of GM-CSF is safe and effective in the treatment of pulmonary alveolar proteinosis and represents an alternative to subcutaneous administration or whole lung lavage. We present a patient with pulmonary alveolar proteinosis who was treated with inhaled GM-CSF and describe her clinical and functional outcome after 1 year of treatment.