In order to study the signal pathway secreting type Ⅰ interferon in porcine alveolar macrophages (PAMs) infected with porcine circovirus type 2 (PCV2), the protein and the mRNA expression levels of cGAS/STING pathways were analyzed by ELISA, Western blotting and quantitative reverse transcriptase PCR in PAMs infected with PCV2. In addition, the roles of cGAS, STING, TBK1 and NF-κB/P65 in the generation of type I interferon (IFN-I) from PAMs were analyzed by using the cGAS and STING specific siRNA, inhibitors BX795 and BAY 11-7082. The results showed that the expression levels of IFN-I increased significantly at 48 h after infection with PCV2 (P<0.05), the mRNA expression levels of cGAS increased significantly at 48 h and 72 h after infection (P<0.01), the mRNA expression levels of STING increased significantly at 72 h after infection (P<0.01), and the mRNA expression levels of TBK1 and IRF3 increased at 48 h after infection (P<0.01). The protein expression levels of STING, TBK1 and IRF3 in PAMs infected with PCV2 were increased, the content of NF-κB/p65 was decreased, and the nuclear entry of NF-κB/p65 and IRF3 was promoted. After knocking down cGAS or STING expression by siRNA, the expression level of IFN-I was significantly decreased after PCV2 infection for 48 h (P<0.01). BX795 and BAY 11-7082 inhibitors were used to inhibit the expression of IRF3 and NF-κB, the concentration of IFN-I in BX795-treated group was significantly reduced than that of the PCV2 group (P<0.01), while no significant difference was observed between the BAY 11-7028 group and the PCV2 group. The results showed that PAMs infected with PCV2 induced IFN-I secretion through the cGAS/STING/TBK1/IRF3 signaling pathway.
Animals ; Cells, Cultured ; Circovirus ; Interferon Type I/genetics* ; Macrophages, Alveolar/virology* ; Membrane Proteins/metabolism* ; Nucleotidyltransferases/metabolism* ; Signal Transduction ; Swine

The aim of this study was to investigate the effects of polarization program on the ability of macrophages to regulate iron metabolism. M1 and M2 macrophages were propagated in vitro from porcine alveolar macrophages 3D4/2 and polarized by cytokines. The 3D4/2 macrophages were treated with 20 ng/mL interferon gamma (IFN-γ) and 10 ng/mL interleukin-4 (IL-4) combined with 10 ng/mL macrophage colony-stimulating factor (M-CSF) to induce polarization to M1 and M2, respectively. After incubation for 24 h, the expression levels of inflammatory factors and iron-metabolism genes were determined using real-time qPCR, Western bot and immunofluorescence. The M1/M2 macrophages culture media supernatant was collected and used to treat porcine intestinal epithelial cells IPEC-J2. The proliferation ability of IPEC-J2 was detected using CCK-8 assay kit. Following exogenous addition of ammonium ferric citrate (FAC) to M1/M2 macrophages, the phagocytic function of macrophages was detected using fluorescein isothiocyanate-dextran (FITC-dextran) and flow cytometry. The results showed that, compared with control, M1 macrophages had higher mRNA levels of iron storage proteins (ferritin heavy and light polypeptide, i.e. FtH and FtL), hepcidin and lipocalin-2, as well as iron content. Moreover, iron enhanced the ability of M1 macrophages to phagocytize FITC-dextran. There was no significant change in these mRNA expression levels in M2 macrophages, but the mRNA expression levels of ferroportin and transferrin receptor were up-regulated. In addition, the conditioned media supernatant from M2 macrophages promoted cell proliferation of IPEC-J2. These findings indicate that M1 macrophages tend to lock iron in the cell and reduce extracellular iron content, thereby inhibiting the proliferation of extracellular bacteria. While M2 macrophages tend to excrete iron, which contributes to the proliferation of surrounding cells and thus promotes tissue repair.
Animals ; Cytokines ; Ferritins ; Iron/metabolism* ; Macrophages/metabolism* ; Macrophages, Alveolar/metabolism* ; Swine

The aim of the present study was to investigate the effect of salidroside (Sal) on inflammatory activation induced by lipopolysaccharide (LPS) in the co-culture of rat alveolar macrophages (AM) NR 8383 and type II alveolar epithelial cells (AEC II) RLE-6TN. CCK-8 colorimetric method was used to detect cell proliferation percentage. The enzyme-linked immunosorbent assay (ELISA) was used to determine the content of tumor necrosis factor alpha (TNF-α), macrophage inflammatory protein-2 (MIP-2) and interleukin-10 (IL-10) in the supernatant. Western blot was used to examine the expression levels of phosphorylated AKT (p-AKT) and total AKT protein. The results showed that pretreatment of RLE-6TN cells or co-culture of RLE-6TN and NR 8383 cells with 32 and 128 µg/mL Sal for 1 h, followed by continuous culture for 24 h, significantly increased the cell proliferation (P < 0.05). Compared with control group, 32 and 128 µg/mL Sal pretreatment significantly increased the ratio of p-AKT/AKT in RLE-6TN cells (P < 0.05). Pretreatment of 32 µg/mL Sal not only inhibited the secretion of TNF-α and MIP-2 by NR 8383 cells induced by LPS (P < 0.05), but also enhanced the inhibitory effect of RLE-6TN and NR 8383 cells co-culture on the secretion of TNF-α and MIP-2 by NR 8383 cells induced by LPS (P < 0.05). In addition, 32 µg/mL Sal pretreatment promoted LPS-induced IL-10 secretion by NR 8383 cells (P < 0.05), and enhanced the promoting effect of co-culture of RLE-6TN and NR 8383 cells on the IL-10 secretion by LPS-induced NR 8383 cells (P < 0.05). In conclusion, Sal may directly inhibit LPS-induced inflammatory activation of AM (NR 8383), promote the proliferation of AEC II (RLE-6TN) through PI3K/AKT signaling pathway, and enhance the regulatory effect of AEC II on LPS-induced inflammatory activation of AM.
Alveolar Epithelial Cells ; drug effects ; metabolism ; Animals ; Cell Line ; Chemokine CXCL2 ; metabolism ; Coculture Techniques ; Glucosides ; pharmacology ; Interleukin-10 ; metabolism ; Lipopolysaccharides ; Macrophages, Alveolar ; drug effects ; metabolism ; Phenols ; pharmacology ; Phosphatidylinositol 3-Kinases ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Signal Transduction ; Tumor Necrosis Factor-alpha ; metabolism

Hypoxia (low oxygen level) is an important feature during infections and affects the host defence mechanisms. The host has evolved specific responses to address hypoxia, which are strongly dependent on the activation of hypoxia-inducible factor 1 (HIF-1). Hypoxia interferes degradation of HIF-1 alpha subunit (HIF-1α), leading to stabilisation of HIF-1α, heterodimerization with HIF-1 beta subunit (HIF-1β) and subsequent activation of HIF-1 pathway. Apical periodontitis (periapical lesion) is a consequence of endodontic infection and ultimately results in destruction of tooth-supporting tissue, including alveolar bone. Thus far, the role of HIF-1 in periapical lesions has not been systematically examined. In the present study, we determined the role of HIF-1 in a well-characterised mouse periapical lesion model using two HIF-1α-activating strategies, dimethyloxalylglycine (DMOG) and adenovirus-induced constitutively active HIF-1α (CA-HIF1A). Both DMOG and CA-HIF1A attenuated periapical inflammation and tissue destruction. The attenuation in vivo was associated with downregulation of nuclear factor-κappa B (NF-κB) and osteoclastic gene expressions. These two agents also suppressed NF-κB activation and subsequent production of proinflammatory cytokines by macrophages. Furthermore, activation of HIF-1α by DMOG specifically suppressed lipopolysaccharide-stimulated macrophage differentiation into M1 cells, increasing the ratio of M2 macrophages against M1 cells. Taken together, our data indicated that activation of HIF-1 plays a protective role in the development of apical periodontitis via downregulation of NF-κB, proinflammatory cytokines, M1 macrophages and osteoclastogenesis.
Alveolar Bone Loss ; metabolism ; prevention & control ; Amino Acids, Dicarboxylic ; pharmacology ; Animals ; Cytokines ; metabolism ; Down-Regulation ; Gene Expression ; drug effects ; Hypoxia-Inducible Factor 1, alpha Subunit ; physiology ; Macrophages ; physiology ; Mice ; NF-kappa B ; metabolism ; Osteogenesis ; physiology ; Periapical Periodontitis ; metabolism ; prevention & control ; Real-Time Polymerase Chain Reaction ; X-Ray Microtomography

We investigated whether Nd2O3 treatment results in cytotoxicity and other underlying effects in rat NR8383 alveolar macrophages. Cell viability assessed by the MTT assay revealed that Nd2O3 was toxic in a dose-dependent manner, but not in a time-dependent manner. An ELISA analysis indicated that exposure to Nd2O3 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-κB (NF-κB) and its inhibitor IκB increased significantly in response to Nd2O3 treatment. Both NF-κB and caspase-3 signaling were activated, suggesting that both pathways are involved in Nd2O3 cytotoxicity.
Animals ; Caspase 3 ; metabolism ; Cell Line ; Macrophages, Alveolar ; drug effects ; enzymology ; NF-kappa B ; metabolism ; Neodymium ; toxicity ; Oxides ; toxicity ; Rats ; Toxicity Tests

OBJECTIVETo investigate the effect of silicon dioxide (SiO₂) on the expression of E-cadherin, α-smooth muscle actin (α-SMA), and transforming growth factor β₁(TGF-β₁) in human pulmonary epithelial cells (A549) with epithelial-mesenchymal transition (EMT), and to study the roles of epidermal growth factor receptor (EGFR) signaling pathway in SiO₂-induced EMT in A549 cells in vitro.

METHODSAlveolar macrophages (AMs) were stimulated with 50 µg/ml SiO₂for 3, 6, 12, 18, 24, or 36 h, and the supernatants were collected to measure the expression of TGF-β₁protein by ELISA. The AM supernatant in which TGF-β₁reached the highest expression (T=18 h) was used as AM-conditioned supernatant. A549 cells were cultured in AM-conditioned supernatant and stimulated with indicated doses of SiO₂(0, 50, 100, and 200 µg/ml) for 48 h. The cell morphological changes were observed using an inverted microscope. The cells were collected at different times, and the mRNA and protein expression levels of E-cadherin, α-SMA, and EGFR were measured by RT-PCR and immunocytofluorescence, respectively.

RESULTSAfter stimulation by SiO₂, the expression level of TGF-β₁protein at each time point was significantly higher in the presence of AM supernatants than in the absence of AM supernatants (P<0.05). With the action time, the expression level of TGF-β₁protein increased at first and then decreased, and the highest level was reached at 18 h. After exposure to SiO₂, A549 cells exhibited mesenchymal characteristics, such as a spindle shape, pseudopodia change, and fibroblast-like morphology, as observed by inverted microscope, especially in the 200 µg/ml group. With increased concentration of SiO₂, the mRNA and protein expression of E-cadherin was down-regulated gradually, especially in the 200 µg/ml group, whereas the mRNA and protein expression of α-SMA and EGFR was up-regulated gradually, especially in the 200 µg/m1 group. There were significant differences between the SiO₂-treated groups (50, 100, and 200 µg/ml SiO₂) and the control group (P<0.05).

CONCLUSIONAfter being stimulated by SiO₂in vitro, AMs have significantly increased expression level of TGF-β₁protein. The AM supernatant together with SiO₂can induce the transition of pulmonary epithelial cells to mesenchymal cells, and its mechanism may be related to the EGFR signaling pathway.

Actins ; metabolism ; Cadherins ; metabolism ; Cell Line, Tumor ; Epithelial Cells ; cytology ; metabolism ; Epithelial-Mesenchymal Transition ; drug effects ; Humans ; Lung ; cytology ; Macrophages, Alveolar ; metabolism ; Receptor, Epidermal Growth Factor ; metabolism ; Signal Transduction ; Silicon Dioxide ; pharmacology ; Transforming Growth Factor beta1 ; metabolism

OBJECTIVETo evaluate the differences in the autophagy activity of alveolar macrophages between patients with different stages of coal workers' pneumoconiosis (CWP).

METHODSA total of 116 coal workers were investigated in the field. Their lung lavage fluid was collected and purified to obtain alveolar macrophages. The morphological characteristics of autophagy were observed by transmission electron microscopy. The expression of autophagy marker (LC3) and autophagy regulators (Beclin1, mTOR, and p-mTOR) was measured by Western blot. The autophagy activity of alveolar macrophages was compared between dust-exposed subjects and patients with stage I, II, and III CWP.

RESULTSThe autophagy activity of alveolar macrophages differed between patients with different stages of CWP, according to transmission electron microscopy. Patients with stage II CWP had significantly higher protein expression of LC3 II/I and Beclin1 in pulmonary macrophages than those with stage ICWP (P < 0.05); patients with stage III CWP had significantly lower protein expression of LC3 II/I and Beclin1 in pulmonary macrophages than those with stage II CWP (P < 0.05), but had significantly higher protein expression of LC3 II/I and Beclin1 than those with stage I CWP (P < 0.05); patients with stage II CWP had a significantly higher protein expression of Beclin1 than the dust-exposed subjects (P < 0.05). Patients with stage II CWP had significantly lower expression of mTOR and p-mTOR in pulmonary macrophages than the dust-exposed subjects and those with stage I CWP (P < 0.05), while patients with stage III CWP had significantly higher expression of mTOR and p-mTOR than those with stage II CWP (P < 0.05).

CONCLUSIONThe autophagy activity of alveolar macrophages varies between patients with different stages of CWP.

Anthracosis ; pathology ; Apoptosis Regulatory Proteins ; metabolism ; Autophagy ; Beclin-1 ; Biomarkers ; Bronchoalveolar Lavage Fluid ; Coal ; Coal Mining ; Dust ; Humans ; Macrophages, Alveolar ; pathology ; Membrane Proteins ; metabolism ; Microtubule-Associated Proteins ; metabolism ; Occupational Exposure ; Pneumoconiosis ; pathology

OBJECTIVETo investigate the role of calcium activated-potassium channels (KCa) in the injury to rat alveolar macrophages induced by quartz.

METHODSThe experiments were conducted on a rat alveolar macrophage cell line (NR8383) in vitro, where crystal silica (100 üg/ml) and amorphous silica (100 üg/ml) were used as the test substances and the cells without any treatment as negative controls. At first the effects of two kinds of quartz were compared. Then KCa special inhibitors (Paxilline for BK, Tram-34 for IK, Apamin for SK) were added in different doses to the in vitro test system with 100 üg/ml crystal quartz as matrix, to observe the function of such channels. Cell viability, lactate dehydrogenase (LDH), interleukin-1β (IL-1β) and tumor necrosis factor-a (TNF-α) were tested.

RESULTSComparing to the negative control group, cell viability reduced, LDH leakage, IL-1β and TNF-α release increased significantly in the amorphous quartz group, furthermore, the effects by crystal quartz were much more serious than those by amorphous quartz, with a statistical significance (P < 0.01). Comparing to the crystal quartz group, IK blockers (Tram-34) led to increase in cell viability significantly, with a statistical significance (P < 0.01); all the KCa specific blockers (Paxilline, Tram-34, Apamin) could reduce LDH leakage and IL-1β release, with a statistical significance (P < 0.05); meanwhile, BK and IK blockers (Paxilline,Tram-34) were able to reduce TNF-α release,with a statistical significance (P < 0.05).Reduction of IL-1β and TNF-α by Tram-34 was dose-dependent, but not so in the other two blockers.

CONCLUSIONBlocking calcium-activated potassium channels (KCa) could reduce cell membrane damage as well as IL-1β and TNF-α release induced by crystal quartz in the rat alveolar macrophages cell line in vitro, which might serve as a signal in the early regulation of inflammatory responses by quartz.

Animals ; Calcium ; metabolism ; Cell Line ; Interleukin-1beta ; metabolism ; Macrophages, Alveolar ; cytology ; metabolism ; Potassium Channels, Calcium-Activated ; metabolism ; Quartz ; toxicity ; Rats ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo investigate the role of oxidative stress in the endoplasmic reticulum stress-induced apoptosis of alveolar macrophages triggered by quartz dust.

METHODSSeventy-two healthy adult Wistar rats were randomly divided into control group, quartz dust group, quartz dust plus N-acetyl cysteine (NAC) group, and NAC group, with 18 rats in each group. One milliliter of sterile saline (for the control and NAC groups) or 1 ml of saline with 5%ultrafine quartz dust (for dust group and dust plus NAC group) was given to each rat by non-exposed endotracheal infusion. From the second day after dust infusion, rats in dust plus NAC group and NAC group received intragastric administration of NAC (100 mg/kg). In each week, the treatment with NAC lasted for 5 consecutive days, followed by 2 days' interval. For each group, 6 rats were randomly selected on the 14th, 28th, or 56th day after dust exposure; they were sacrificed by bloodletting from the femoral artery, and the lungs were collected. Bronchoalveolar lavage fluid was collected to separate macrophages. The protein expression of caspase-12 in alveolar macrophages, the apoptosis rate and reactive oxygen species (ROS) content of alveolar macrophages, and the protein carbonyl content of alveolar macrophages were determined by Western blot, flow cytometry, and colorimetry, respectively.

RESULTSIncreased protein expression of caspase-12, apoptosis rate, and content of ROS and protein carbonyl were discovered on the 14th day in the dust group, in comparison with the control group (P < 0.05), and the increase lasted till the 28th and 56th days. (P < 0.05). Compared with the dust group, the dust plus NAC group showed significant decreases in the content of ROS on the 14th, 28th, and 56th days (P < 0.05), significant decreases in the content of protein carbonyl on the 28th and 56th days (P < 0.05), and significant decreases in the protein expression of caspase-12 and apoptosis rate (P < 0.05).

CONCLUSIONOxidative stress is potentially involved in the endoplasmic reticulum stress-induced apoptosis of alveolar macrophages triggered by quartz dust. Oxidative damage of protein in the endoplasmic reticulum may play an important role in the process.

Animals ; Caspase 12 ; metabolism ; Dust ; Endoplasmic Reticulum Stress ; drug effects ; Macrophages, Alveolar ; drug effects ; pathology ; Male ; Oxidative Stress ; drug effects ; Protein Carbonylation ; Quartz ; toxicity ; Rats ; Rats, Wistar ; Reactive Oxygen Species ; metabolism

Exotoxins produced by Actinobacillus (A.) pleuropneumoniae (Apx) play major roles in the pathogenesis of pleuropneumonia in swine. This study investigated the role of ApxI in hemolysis and cellular damage using a novel apxIA mutant, ApxIA336, which was developed from the parental strain A. pleuropneumoniae serotype 10 that produces only ApxI in vitro. The genotype of ApxIA336 was confirmed by PCR, Southern blotting, and gene sequencing. Exotoxin preparation derived from ApxIA336 was analyzed for its bioactivity towards porcine erythrocytes and alveolar macrophages. Analysis results indicated that ApxIA336 contained a kanamycin-resistant cassette inserted immediately after 1005 bp of the apxIA gene. Phenotype analysis of ApxIA336 revealed no difference in the growth rate as compared to the parental strain. Meanwhile, ApxI production was abolished in the bacterial culture supernatant, i.e. exotoxin preparation. The inability of ApxIA336 to produce ApxI corresponded to the loss of hemolytic and cytotoxic bioactivity in exotoxin preparation, as demonstrated by hemolysis, lactate dehydrogenase release, mitochondrial activity, and apoptosis assays. Additionally, the virulence of ApxIA336 appeared to be attenuated by 15-fold in BALB/c mice. Collectively, ApxI, but not other components in the exotoxin preparation of A. pleuropneumoniae serotype 10, was responsible for the hemolytic and cytotoxic effects on porcine erythrocytes and alveolar macrophages.
Actinobacillus pleuropneumoniae/genetics/*pathogenicity/*physiology ; Animals ; *Apoptosis ; Bacterial Proteins/genetics/metabolism ; Blotting, Southern ; Exotoxins/*genetics ; Hemolysin Proteins/genetics/metabolism ; *Hemolysis ; Macrophages, Alveolar/metabolism/*microbiology ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; Swine ; Virulence