TNF-α Up-regulates Matrix Metalloproteinase-9 Expression and Activity in Alveolar Macrophages from Patients with Chronic Obstructive Pulmonary Disease

To study the effects of tumor necrosis factor （TNF）-α on matrix metalloproteinase （MMP）-9 expression and activity in alveolar macrophages （AM） and to investigate the role of NF-κB in the induction, AM were collected from bronchoalveolar lavage fluid （BALF） of healthy subjects and patients with chronic obstructive pulmonary disease （COPD）. MMP-9 expression and activity were detected by semi-quantitative reverse transcription-polymerase chain reaction （RT-PCR）, Western blotting and zymography. NF-κB activity was detected by electrophoretic mobility shift assay （EMSA）. MMP-9 expression and activity induced by TNF-α in AM from healthy subjects or patients with COPD were significantly increased in a dose-dependent manner （P〈0.05）. NF-κB activity induced by TNF-α was significantly increased in AM from patients with COPD, and pyrrolidine dithiocarbamate （PDTC） and N-acetyl-L-cysteine （NAC） significantly inhibited the activation of NF-κB induced by TNF-α （P〈0.05）. The presents study suggested that the expression and activity of MMP-9 from AM can be induced by TNF-α, and TNF-α/NF-κB signal pathway may play an important role in the induction.

Dietary plant extracts modulate gene expression profiles in alveolar macrophages of pigs experimentally infected with porcine reproductive and respiratory syndrome virus

Background: Our previous study showed that 3 plant extracts enhanced the immune responses and growth efficiency of weaned pigs infected with porcine reproductive and respiratory syndrome virus(PRRSV), which is one of the most economically important disease in swine industry. However, each plant extract differently effected on growth efficiency and immune responses. Therefore, the objective of this study was conducted to characterize the effects and investigate the potential underlying mechanisms of 3 plant extracts on gene expression of alveolar macrophages in weaned pigs experimentally infected with PRRSV.Results: PRRSV infection altered(P < 0.05) the expression of 1,352 genes in pigs fed the control(CON;755 up, 597 down). Compared with the infected CON, feeding capsicum(CAP), garlic botanical(GAR), or turmeric oleoresin(TUR) altered the expression of 46 genes(24 up, 22 down), 134 genes(59 up, 75 down), or 98 genes(55 up, 43 down) in alveolar macrophages of PRRSV-infected pigs, respectively. PRRSV infection up-regulated(P < 0.05) the expression of genes related to cell apoptosis, immune system process, and response to stimulus, but downregulated(P < 0.05) the expression of genes involved in signaling transduction and innate immune response.Compared with the infected CON, feeding TUR or GAR reduced(P < 0.05) the expression of genes associated with antigen processing and presentation, feeding CAP up-regulated(P < 0.05) the expression of genes involved in antigen processing and presentation. Supplementation of CAP, GAR, or TUR also enhanced(P < 0.05) the expression of several genes related to amino acid metabolism, steroid hormone synthesis, or RNA degradation, respectively.Conclusions: The results suggest that 3 plant extracts differently regulated the expression of genes in alveolar macrophages of PRRSV-infected pigs, especially altering genes involved in immunity.

Dietary arachidonate in milk replacer triggers dual benefits of PGE2 signaling in LPS-challenged piglet alveolar macrophages

Background: Respiratory infections challenge the swine industry, despite common medicinal practices. The dual signaling nature of PGE2(supporting both inflammation and resolution) makes it a potent regulator of immune cell function. Therefore, the use of dietary long chain n-6 PUFA to enhance PGE2 effects merits investigation.Methods: Day-old pigs(n = 60) were allotted to one of three dietary groups for 21 d(n = 20/diet), and received either a control diet(CON, arachidonate = 0.5% of total fatty acids), an arachidonate(ARA)-enriched diet(LC n-6,ARA = 2.2%), or an eicosapentaenoic(EPA)-enriched diet(LC n-3, EPA = 3.0%). Alveolar macrophages and lung parenchymal tissue were collected for fatty acid analysis. Isolated alveolar macrophages were stimulated with LPS in situ for 24 h, and m RNA was isolated to assess markers associated with inflammation and eicosanoid production.Culture media were collected to assess PGE2 secretion. Oxidative burst in macrophages was measured by: 1)oxygen consumption and extracellular acidification(via Seahorse), 2) cytoplasmic oxidation and 3) nitric oxide production following 4, 18, and 24 h of LPS stimulation.Results: Concentration of ARA(% of fatty acids, w/w) in macrophages from pigs fed LC n-6 was 86% higher than CON and 18% lower in pigs fed LC n-3(P < 0.01). Following LPS stimulation, abundance of COX-2 and TNF-α mRNA(P < 0.0001), and PGE2 secretion(P < 0. 01) were higher in LC n-6 PAM vs. CON. However, ALOX5 abundance was1.6-fold lower than CON. Macrophages from CON and LC n-6 groups were 4-fold higher in ALOX12/15 abundance(P < 0.0001) compared to LC n-3. Oxygen consumption and extracellular acidification rates increased over 4 h following LPS stimulation(P < 0.05) regardless of treatment. Similarly, increases in cytoplasmic oxidation(P < 0.001)and nitric oxide production(P < 0.002) were observed after 18 h of LPS stimulation but were unaffected by diet.Conclusions: We infer that enriching diets with arachidonic acid may be an effective means to enhance a stronger innate immunologic response to respiratory challenges in neonatal pigs. However, further work is needed to examine long-term safety, clinical efficacy and economic viability.

Effects of Bilirubin on Alveolar Macrophages in Rats with Emphysema and Expression of iNOS and NO in Them

To explore the effects of bilirubin on alveolar macrophages (AM) and expression of iNOS and NO in them in emphysema model, the rats were pretreated with bilirubin before exposed to smoke. AM were isolated from bronchoalveolar lavage fluid (BALF) and cultured. Pathological microscopic examination of AM and immunohistochemical analysis of iNOS were performed. Nitric oxide (NO) content in the samples was determined by nitrate reductase technique. The results showed both alveoli and alveolar septum appeared normal in size and shape in normal group. AM showed kidney-shaped nucleus and were rich in Golgi complexes and primary lysosomes in the cytoplasm. The inner membrane of mitochondrion was continuous. Most cristae of the mitochondria were intact. In model group, the alveoli were expanded, ruptured and bullaes were formed. Both the population and sizes of AM increased significantly. Secondary lysosomes were rich in the cytoplasm. Deformation and pyknosis of the nucleus, swelling of the mitochondrions and rupture of the inner mitochondrial membrane could also be seen. At high magnification, most of the mitochondrial cristae were broken, or completely lost at certain points. In bilirubin group, alveoli partly expanded and the population of AM also increased, with morphological changes being slighter than that in model group. Both NO contents and expression of iNOS in model group were higher than those in normal group (P<0.05). In bilirubin group the two indice were lower than those in model group (P<0.05). Our findings suggested that high expression of iNOS and high NO content in AM accelerate the development of emphysema associated with smoking in rats. Bilirubin may exert protective effects on AM and retards the development of emphysema in rats.

Voltage-dependent K^+-channel Responses during Activation and Damage in Alveolar Macrophages Induced by Quartz Particles

The roles of voltage-dependent K^＋ channels during activation and damage in alveolar macrophages （AMs） exposed to different silica particles were examined. Rat AMs were collected by means of bronchoalveolar lavage, and were adjusted to 5× 10^5/mL. After AMs were exposed to different concentrations （0, 25, 50, 100, 200 μg/mL） of quartz particles and 100 μg/mL amorphous silica particles for 24 h, the voltage-depended K^＋ current in AMs was measured by using patch clamp technique. Meanwhile the leakage of lactate dehydrogenase （LDH） and the viability of AMs were detected respectively. Patch clamp studies demonstrated that AMs possessed outward delayed and inward rectifying K^＋ current. Exposure to quartz particles increased the outward delayed K^＋ current but it had no effect on inward rectifier K^＋ current in AMs. Neither of the two K^＋ channels in AMs was affected by amorphous silica particles. Cytotoxicity test showed that both silica particles could damage AM membrane and result in significant leakage of LDH （P〈0.05）. MTT studies, however, showed that only quartz particles reduced viability of AMs （P〈0.05）. It is concluded that quartz parti- cles can activate the outward delayed K^＋ channel in AMs, which may act as an activating signal in AMs to initiate an inflammatory response during damage and necrosis in AMs induced by exposure to quartz particle. K^＋ channels do not contribute to the membrane damage of AMs.

Induction of matrix metalloproteinase-9 in alveolar macrophages by TNF-α through NF-κB signal pathway

Objective： To explore the effect of tumor necrosis factor （TNF）-α on matrix metalloproteinase-9 （MMP-9） expression and activity in alveolar macrophages （AM） from patients with chronic obstructive pulmonary disease （COPD） and study its associated signal pathway. Methods： AM were collected from bronchoalveolar lavage fluid in patients with COPD. The AM were incubated for 1.5 h with pyrrolidine dithiocarbamate（PDTC） at concentrations from 0 μmol/L to 50μmol/L and then stimulated for 24 h by TNF-α at 10 ng/ml. MMP-9 expression and activity were respectively detected by semi-quantitative reverse transcription-polymerase chain reaction （RT-PCR）, Western blotting and Zymography. NF-κB activity was investigated by electrophoretic mobility shift assay （EMSA）. Results： Both the mRNA and protein levels of MMP-9 induced by TNF-α in AM were significantly elevated in a dose dependent manner （ P 〈 0.05）. The level of MMP-9 activity was also correspondingly significantly elevated in the induction （ P 〈 0.05）, which was possibly related with the over-expression of MMP-9. NF-κB activity was significantly increased when AM were stimulated by 10 ng/mL TNF-α （ P 〈 0.05）. The expression of MMP-9 induced by TNF-α could be significantly inhibited by PDTC （P 〈 0.05 ）. Conclusion： The expression and activity of MMP-9 from AM could be induced by TNF-α, and NF-κB signal pathway played an important role in the induction.

Pig macrophages with site-specific edited CD163 decrease the susceptibility to infection with porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome(PRRS)is recognized as one of the most infectious viral diseases of swine.Although Cluster of differentiation 163(CD163)is identified as an essential receptor for mediating PRRS virus(PRRSV)infection,the important residues involved in infection on CD163 are still unclear.Therefore,it is very important to identify these key residues to study the mechanism of PRRSV infection and to generate anti-PRRSV pigs.In this study,we first generated immortalized porcine alveolar macrophage(IPAM)cell lines harboring 40-residues(residues 523-562,including R561(arginine(R)at position 561))deletion of CD163.PRRSV infection experiments showed that these IPAM cell lines were completely resistant to PRRSV infection.We then generated cloned pigs carrying CD163-R561A(an arginine(R)to alanine(A)substitution at position 561 of CD163).PRRSV challenge experiments in porcine alveolar macrophages(PAMs)isolated from the CD163-R561A pigs showed significantly lower susceptibility to PRRSV than that of CD163-R561 PAMs.Through this study,we show that CD163523-562 contains essential residues for mediating PRRSV infection,and that CD163 R561 significantly contributes to PRRSV infection but is not essential for infection.These functional sites can therefore serve as new targets for understanding the mechanism of PRRSV infection.Furthermore,CD163-R561A pigs can be used as an important model for improving pig germplasm with resistance against PRRSV.

Radiation Effects on the Immunological Functions and Membranes of Alveolar Macrophages of Rats

Alveolar macrophages (AM) from BCG activated Wistar rat were irradiated with different doses of Gamma rays in vitro. The effects of radiation on their immunological functions and membrane damage were studied. The non-specific cytotoxicity and specific phagocytosis of AM irradiated with dose of 0, 100, 300 and 500 Gy decreased with the increase in dose. The relative fractions of Lactate Dehydrogenase and Beta-glucuronidase (β-glu) activity in supernatant increased with the increase in dose. There was a correlation between the suppression of immunological functions and the degree of damage of cytoplasmic and lysosomal membranes of AM after irradiation. Na2SeO3, a protective agent of cell membranes, alleviated this effect on the suppressive cytotoxicity indices of irradiated AM.

Monocyte and macrophage function in respiratory viral infections

Pulmonary macrophages,such as tissue-resident alveolar and interstitial macrophages and recruited monocyte-derived macrophages,are the major macrophages present in the lungs during homeostasis and diseased conditions.While tissue-resident macrophages act as sentinels of the alveolar space and play an important role in maintaining homeostasis and immune regulation,recruited macrophages accumulate in the respiratory tract after acute viral infections.Despite sharing similar anatomical niches,these macrophages are distinct in terms of their origins,surface marker expression,and transcriptional profiles,which impart macrophages with distinguished characteristics in physi-ological and pathophysiological conditions.In this review,we summarize the current view on these macrophage populations,their shared functions,and what makes them distinct from each other in the context of homeostasis andrespiratoryviral infections.

Essential role of monocytes and macrophages in the progression of acute pancreatitis

Acute pancreatitis(AP) is an inflammatory condition of the pancreas caused by an imbalance in factors involved in maintaining cellular homeostasis.Earliest events in AP occur within acinar cells accompanied by other principal contributors to the inflammatory response i.e.the endothelial cells,immunocytes(granulocytes,monocytes/macrophages,lymphocytes) and neutrophils.Monocytes/macrophages are important inflammatory mediators,involved in the pathophysiology of AP,known to reside in the peritoneal cavity(in the vicinity of the pancreas) and in peripancreatic tissue.Recent studies suggested that impaired clearance of injured acini by macrophages is associated with an altered cytokine reaction which may constitute a basis for progression of AP.This review focuses on the role of monocytes/macrophages in progression of AP and discusses f indings on the inflammatory process involved.

An In Vitro Investigation of Pulmonary Alveolar Macrophage Cytotoxicity Introduced by Fibrous and Grainy Mineral Dusts

In order to study the damage mechanism of mineral dusts on the pulmonary alveolar macrophage （AM）, the changes in their death ratio, malandialdthyde （MDA） content and activities of lactate dehydrogenase （LDH） and superoxide dismutase （SOD） were measured, and the technique of cell culture in vitro was used to investigate the cytotoxicity of six mineral dusts （twelve crystal habits） from twelve mineral deposits. The results show that woUastonite and clinoptilolite have no AM cytotoxicity, while other fibrous and grainy mineral dusts damage pulmonary AM in various degrees. The cytotoxicity of fibrous mineral dusts was greater than that of the grainy ones, and the cytotoxicity of dusts was positively correlated with the active OH- content in dusts, but not necessarily so with its SiO2 content. The high pH values produced by dust was unfavorable for the survival of cells and the dusts with low bio-resistance were safe for cells. The content of variable valence elements in dusts might influence their cytotoxicity and the surface charge of dusts was not a stable factor for their toxicity. It is demonstrated that the shape of mineral dusts was one of the factors affecting cytotoxicity, and that the cytotoxicity of mineral dusts depends mainly on their properties.

EFFECTS OF ALVEOLAR MACROPHAGE CONDITIONED MEDIA FROM INTERSTITIAL LUNG DISEASE PATIENTS ON THE PROCOLLAGEN mRNA EXPRESSION IN HUMAN LUNG FIBROBLASTS

Progressive inflammation and fibrosis are the central processes in the pathogenesis of pulmonary fibrosis. It is believed that macrophages in areas of chronically inflamed lung play a key role in fibrotic response. Therefore, we investigated the effects of alveolar macrophage (AmΦ) conditioned media from interstitial lung disease (ILD) patients on lung fibroblast proliferation and procollagen mRNA expression. After stimulating with AmΦ conditioned media from ILD patients, the fibroblast proliferation increased 71. 4 % compared with the control, but for media from bronchial carcinoma (BC) patients, it just increased 14. 3%. There is a significant difference between the two groups (P<0. 05). The procollagen a1 (Ⅰ) mRNA in fibroblasts stimulated with AmΦ conditioned media from ILD patients was increased 21. 3 %, and a1 ( Ⅲ) was 37. 2% higher than control (P<0.05). It increased 6. 8% and 12. 8% for media from BC patients respectively, but there was no difference when compared to the control. We considered that AmΦ from ILD patients might be in an activated state and could release some growth factors to stimulate fibroblast proliferation and promote collagen DNA expression.

Expression of Toll-like Receptor 2/4 on Alveolar Macrophage in the Model of Total Hepatic Ischemia/Reperfusion Injury in Mice

Objective： To explore the expression and meaning of Toll-like receptor 2/4 in alveolar macrophage during the process of total hepatic ischemia in mice. Methods： BALB/c mice were used in a model of total hepatic ischemia/reperfusion. Alveolar Macrophage were collected at the time point of lh, 6h and 12h by the means of bronchoalveolar lavage （BAL）, and its TLR2/4 mRNA and protein were detected with Flow Cytometry and Real-time PCR. The level of TNF in BAL fluid were measured. The concentration of MPO, the ratio of wet/dry and lung histological scores were used to assess the degrees of lung injuries. Results： At the three time points of hepatic ischemia reperfusion, the expression of TLR2/4 protein of and mRNA were up-regulated and the level of TLR2 was on the rise continually. TLR4 at the time of 6 h reached the peak value （P〈0.01）. The level of TNF-2 in BAL fluid reached the highest point at the time of 6 h （P〈0.01）. The ratio of wet/dry rose continually during hepatic ischemia reperfusion. After 1 h, the level of MPO increased rapidly. Then it reached the peak value during the period of 6 h to 12 h. Conclusion： TLR2/4 on the mice of alveolar macrophage were activated in the process of hepatic ischemia/reperfusion and involved in the injury of lung.

A novel reporter mouse line for studying alveolar macrophages

Alveolar macrophages(AMs)are self-maintained immune cells that play vital roles in lung homeostasis and immunity.Although reporter mice and culture systems have been established for studying macrophages,an accurate and specific reporter line for alveolar macrophage study is still not available.Here we reported a novel Rspo1-tdTomato gene reporter mouse line that could specifically label mouse AMs in a cell-intrinsic manner.Using this reporter system,we visualized the dynamics of alveolar macrophages intravitally under steady state and characterized the alveolar macrophage differentiation under in vitro condition.By performing ATAC-seq,we found that insertion of the tdTomato cassette in the Rspo1 locus increased the accessibility of a PPARE motif within the Rspo1 locus and revealed a potential regulation by key transcription factor PPAR-γfor alveolar macrophage differentiation in vitro and in vivo.Consistently,perturbation of PPAR-γby its agonist rosiglitazone or inhibitor GW9662 resulted in corresponding alteration of tdTomato expression in alveolar macrophages together with the transcription of PPAR-γdownstream target genes.Furthermore,global transcriptomic analyses of AMs from the wild type mice and the Rspo1-tdTomato mice showed comparable gene expression profiles,especially those AM-specific genes,confirming that the insertion of the tdTomato cassette in the Rspo1 locus does not impact the cell identity and biological function of AMs under normal condition.Taken together,our study provides an alternative tool for in vivo and in vitro labeling of alveolar macrophages with high specificity which could also be utilized as an indicator of PPAR-γactivity for future development of PPAR-γspecific targeting drugs.

Neodymium Oxide Induces Cytotoxicity and Activates NF-κB and Caspase-3 in NR8383 Cells

We investigated whether Nd_2O_3 treatment results in cytotoxicity and other underlying effects in rat NR8383 alveolar macrophages.Cell viability assessed by the MTT assay revealed that Nd_2O_3 was toxic in a dose-dependent manner, but not in a time-dependent manner. An ELISA analysis indicated that exposure to Nd203 caused cell damage and enhanced synthesis and release of inflammatory chemokines. A Western blot analysis showed that protein expression levels of caspase-3, nuclear factor-KB （NF-KB） and its inhibitor IKB increased significantly in response to Nd203 treatment. Both NF-KB and caspase-3 signaling were activated, suggesting that both pathways are involved in Nd203 cytotoxicity.

Increased activity of protein kinase C in alveolar macrophages in idiopathic pulmonary fibrosis

Objective To investigate the changes on protein kinase C (PKC) activity of alveolar macrophages (AMs) in patients with idiopathic pulmonary fibrosis (IPF) Methods The PKC activity of AM in 9 healthy volunteers and 15 patients with IPF was investigated by measuring the radioactivity Results The total, cytosolic and membrane PKC activity of AM in bronchoalveolar lavage fluid (BALF) from patients with IPF were higher than those from control group ( P <0 01, P <0 05 and P <0 05, respectively) The total and the membrane associated PKC activity had a positive correlation with the number of cells in BALF ( r =0 8135, P <0 01 and r =0 5917, P <0 05), respectively Conclusion As a bypass of transmembrane signal transduction, PKC was suggested to be involved in the origination and development of IPF

STAT1 Antisense Oligonucleotides Attenuate the Proinflammatory Cytokine Release of Alveolar Macrophages in Bleomycin-Induced Fibrosis

To investigate the effect of signal transducers and activators of transcription 1 （STAT1） antisense oligonucleotides （ASON） on concentrations of TNF-α IL-8, NO secreted by alveolar macrophages （AMs） in bleomycin-induced rat pulmonary fibrosis, five adult female Wistar rats were intratracheally instilled with bleomycin. After 7 days, the rats were killed by right ventricle of heart exsanguinations under ketamine anaesthesia and bronchoalveolar lavage （BAL） was performed to obtain AMs. AMs were divided into four groups, treated with STAT1 ASON, STAT1 sense oligonucleotides （SON）, dexamethasone （DEX） and medium alone （control）, respectively. AMs and media were collected after culture for 36 h. The mRNA and protein expressions of STAT1 and ICAM-1 in AMs were detected by RT-PCR and ELISA, respectively. The concentrations of TNF-α IL-8, NO in cultured medium were detected. The STAT1 mRNA expression by AMs in the STAT1 ASON group was lower than those of AMs in the STAT1 SON group, the DEX group and the control group （p 〈 0.05）. Moreover, the STAT1 mRNA expression by AMs in the DEX group was also lower than those of AMs in the STAT1 SON group and the control group （p 〈 0.05）, but the STAT1 mRNA expression by AMs in the STAT1 SON group was not different from that of the control group （p 〉 0.05）. The protein expressions of STAT1 and ICAM-1 and the mRNA expression of ICAM-1 showed similar changes to the STAT1 mRNA expression by AMs. The concentrations of TNF-α IL-8, NO in cultured medium from STAT1 ASON group were lower than those from STAT1 SON, DEX and the control groups （p 〈 0.05）. Moreover, the concentrations of TNF-α IL-8, NO in cultured medium from DEX group were also lower than those from the control and STAT1 SON group （p 〈 0.05）, but no difference between STAT1 SON group and the control （p 〉 0.05）. The results suggest that STAT1 ASON could inhibit the secretion of TNF-α IL-8, NO in AMs, and STAT1 could become a target of treating pulmonary fibrosis. Cellular ＆ Molecular Immunology. 2005;2（3）：211-217.

Regulative effect of P38MAPK on release of TNF and NO from alveolar macrophages under endotoxin stimulation

Objective:: To evaluate activation of P38 mitogen-activated protein kinase (P38MAPK) in alveolar macrophage (AM), release of TNFα and NO from cells, and their relationship following lipopolysacchride (LPS) stimulation. Methods: AM was isolated from branch alveolar lavage fluid (BALF). The activation of P38MAPK was assayed by Westernblot. SB203580, a specific inhibitor of P38MAPK, was used with gradient concentration to evaluate the regulative effect of P38MAPK on the release of TNFα and NO from AM. Results: P38MAPK was activated by LPS (100 ng/ml ) with peak activation at 30 minutes. The activation of P38MAPK was inhibited by SB203580. The secretion of TNFα and NO stimulated with LPS increased (P< 0.01 ) and was inhibited by SB203580 significantly. Conclusions: The results indicate that P38MAPK is involved in the secreting process of TNFα and NO following LPS stimulation. P38MAPK may be an important site for controlling the secretion of both inflammatory mediators during lung inflammatory disorders.

Role of Endoplasmic Reticulum Stress in Silica-induced Apoptosis in RAW264.7 Cells＊

Objective We investigated the role of endoplasmic reticulum stress （ERS） in silica-induced apoptosis in alveolar macrophages in vitro. Methods RAW264.7 cells were incubated with 200 μm/mL silica for different time periods. Cell viability was assayed by the MTT assay. Cell apoptosis was evaluated by DAPI staining, flow cytometry analysis, and Western blot analysis of caspase-3. Morphological changes in the endoplasmic reticulum were observed by transmission electron microscopy. The expression of ERS markers binding protein （BiP） and CCAAT-enhancer-binding protein homologous protein （CHOP） was examined by Western blotting and real-time PCR. As an inhibitor of ERS, 4-phenylbutyric acid （4-PBA） was used in the experiments. Results Silica exposure induced nuclear condensation and caspase-3 expression in RAW264.7 cells. The number of apoptotic cells increased after silica exposure in a time-dependent manner. Silica treatment induced expansion of the endoplasmic reticulum. In addition, the expression of BiP and CHOP increased in silica-stimulated cells. Furthermore, 4-PBA treatment inhibited silica-induced endoplasmic reticulum expansion and the expression of BiP and CHOP. Moreover, 4-PBA treatment attenuated nuclear condensation, reduced apoptotic cells, and downregulated caspase-3 expression in silica-stimulated cells. Conclusion Silica-induced ERS is involved in the apoptosis of alveolar macrophages

LIGHT of pulmonary NKT cells annihilates tissue protective alveolar macrophages in augmenting severe influenza pneumonia

CD1d-restricted natural killer T(NKT)cells are innate-like T lymphocytes with protective or pathogenic roles in the development of influenza pneumonia.Here,we show that lung-infiltrated and activated NKT cells are the major cellular source of LIGHT/TNFSF14,which determines the severity of pulmonary pneumonia by highly deteriorative influenza A virus(IAV)infection.Compared to wild-type mice,LIGHT^(-/-)mice exhibit much lower morbidity and mortality to IAV,due to alleviated lung damage and reduced apoptosis of alveolar macrophages(AMs).LIGHT preferentially promotes cell death of lymphotoxin β receptors positive(LTβR^(+))AMs but not herpesvirus entry mediator positive(HVEM^(+))AMs.Therefore,these results suggest that NKT-derived LIGHT augments cell death of the tissue protective AMs in exacerbating lung pathology and susceptibility to fatal influenza infection.Suppression of LIGHT signaling might be a viable option in the treatment of influenza-associated acute respiratory distress syndrome.