Epithelial Cell Line A549 Research Articles

Trichomonas vaginalis induces cytopathic effect on human lung alveolar basal carcinoma epithelial cell line A549

Trichomonas vaginalis, the causative agent of trichomoniasis is generally known to inhabit the genitourinary tract. However, several case reports with supporting molecular and immunological identifications have documented its occurrence in the respiratory tract of neonates and adults. In addition, the reports have documented that its occurrence is associated with respiratory failures. The medical significance or consequence of this association is unclear. Thus, to establish the possible outcome from the interaction of T. vaginalis with lung cells, the cytopathic effects of the parasites were evaluated using monolayer cultures of the human lung alveolar basal carcinoma epithelial cell line A549. The possible effect of association of T. vaginalis with A549 epithelial cells was analyzed using phase-contrast, scanning electron microscopy and fluorescence microscopy. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), crystal-violet and TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling) assays were conducted for cytotoxicity testing. The results demonstrate that T. vaginalis: (1) adheres to A549 epithelial cells, suggesting a density-dependent parasite-cell association; (2) adherence on A549 is through flagella, membrane and axostyle; (3) causes cell detachment and cytotoxicity (50–72.4%) to A549 and this effect is a function of parasite density; and (4) induces apoptosis in A549 about 20% after 6 h of incubation. These observations indicate that T. vaginalis causes cytopathic effects on A549 cell. To date, this is the first report showing a possible interaction of T. vaginalis with the lung cells using A549 monolayer cultures. Further studies are recommended to completely elucidate this association.

Abstract 3369: Differential biotherapeutic advantages of honey in targeting the Warburg effect and survival of MRC-5 and A549 cell lines

Abstract Lung cancer is a one of the most prevalent and deadly cancers in United States. Experimental evidence support that cancer cells do exhibit higher glycolytic rates than normal cells (Warburg effect). To exploit this unique cancer-dependent ATP generation phenomenon, we hypothesize that exposure of cancer cells to organic inhibitors of glycolysis would negatively impact their survival and alter their growth and viability resulting from the vast decrease in their essential glycolytic ATP production; no negative consequences will be seen on normal lung cells. The human lung fibroblast cell line MRC-5 and the human alveolar epithelial cell line A549 were used as models for normal lung and lung cancer in vitro in this study. Using standard methods, both cell lines were maintained and exposed to honey and D-glucose reagents at concentration levels ranging from 31.3-2,000 µg/ml in 96 well plates in quadruplets and experiments repeated at least three times using MTT, and cell counting (T4 Cellometer) assays as well as phase-contrast photo-imaging. Our results indicate that exposure of both cell lines to these natural nutraceutic organics resulted in concentration dependent cell destruction/cell survival depending on the cell line exposed. Honey and D-glucose showed statistically significant (p<0.05) differential negative effects on the A549 line in comparison to its unexposed control as well as to their effects on the MRC-5 cell line. Results show a promising role of honey and D-glucose as metabolites of interest for selective management of cancerous cells. Citation Format: Ibrahim O. Farah, Veshell L. Lewis, Wellington K. Ayensu, Joseph A. Cameron. Differential biotherapeutic advantages of honey in targeting the Warburg effect and survival of MRC-5 and A549 cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3369. doi:10.1158/1538-7445.AM2014-3369

The Moraxella catarrhalis-induced pro-inflammatory immune response is enhanced by the activation of the epidermal growth factor receptor in human pulmonary epithelial cells

BackgroundChronic lower airway inflammation is considered to be a major cause of pathogenesis and disease progression in chronic obstructive pulmonary disease (COPD). Moraxella catarrhalis is a COPD-associated pathogen causing exacerbations and bacterial colonization in the lower airways of patients, which may contribute to chronic inflammation. Increasing evidence suggests that the epidermal growth factor receptor (EGFR) modulates inflammatory processes in the human airways. The goal of this study was to investigate the role of EGFR in the M. catarrhalis-induced pro-inflammatory immune response in airway epithelial cells. MethodsThe effects of inhibition and gene silencing of EGFR on M. catarrhalis-dependent pro-inflammatory cytokine expression in human primary bronchial epithelial cells (NHBEs), as well as the pulmonary epithelial cell lines BEAS-2B and A549 were analyzed. We also assessed the involvement of EGFR-dependent ERK and NF-κB signaling pathways. ResultsThe M. catarrhalis-induced pro-inflammatory immune response depends, at least in part, on the phosphorylation and activation of the EGF receptor. Interaction of M. catarrhalis with EGFR increases the secretion of pro-inflammatory cytokines, which is mediated via ERK and NF-κB activation. ConclusionThe interaction between M. catarrhalis and EGFR increases airway inflammation caused by this pathogen. Our data suggest that the inhibition of EGFR signaling in COPD could be an interesting target for reducing M. catarrhalis-induced airway inflammation.

Xanthones with anti-tumor activity isolated from Securidaca inappendiculata

A new xanthone, 1,2-dihydroxy-6,7,8-trimethoxyxanthone, together with ten known xanthones and nine other compounds was isolated from the stem of Securidaca inappendiculata. The structure of the new compound was elucidated based on spectroscopic data analyses, and other compounds were identified by comparison with data from the literature. The anti-tumor activities of the xanthones were evaluated by MTT assay on human lung adenocarcinoma epithelial cell line A549, and a primary structure–activity relationship analysis was carried out based on results from MTT assay. It is revealed that all the xanthones possessed anti-tumor activity in vitro in a concentration-dependent manner. The IC50 values varied a lot among xanthones. 1,7-Dihydroxy-3,4-dimethoxyxanthone was proved to be the most efficient anti-tumor agent with IC50 of 50.66 μM, while 1,3,7-trihydroxy-2,8-dimethoxyxanthone and 1,7-dihydroxyxanthone possessed the weakest activities. The structure–activity relationship analysis revealed that the anti-tumor activity of xanthones was affected mostly by the position and number of hydroxyl and methoxyl groups. Free hydroxyl and ortho-methoxyl groups were believed to possess important potentials to the activity.

Role of SIRT1 in Streptococcus pneumoniae-induced human β-defensin-2 and interleukin-8 expression in A549 cell.

Streptococcus pneumoniae is an important pathogen of pneumonia in human. Human alveolar epithelium acts as an effective barrier and is an active participant in host defense against invasion of bacterial by production of various mediators. Sirtuin 1 (SIRT1), the prototypic class III histone deacetylase, is involved in the molecular control of lifespans and immune responses. This study aimed at examining the role of SIRT1 in mediating S. pneumoniae-induced human β-defensin-2 (hBD2) and interleukin-8(IL-8) expression in the alveolar epithelial cell line A549 and the underlying mechanisms involved. A549 cells were infected with S. pneumoniae for indicated times. Exposure of A549 cells to S. pneumoniae increased the expressions of SIRT1 protein, hBD2 and IL-8 mRNA, and protein. The SIRT1 activator resveratrol enhanced S. pneumoniae-induced gene expression of hBD2 but decreased IL-8 mRNA levels. Blockade of SIRT1 activity by the SIRT1 inhibitors nicotinamide reduced S. pneumoniae-induced hBD2 mRNA expression but increased its stimulatory effects on IL-8 mRNA. S. pneumoniae-induced activation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). SIRT1 expression was attenuated by selective inhibitors of ERK and p38 MAPK. The hBD2 mRNA production was decreased by pretreatment with p38 MAPK inhibitor but not with ERK inhibitor, whereas the IL-8 mRNA expression was controlled by phosphorylation of ERK. These results suggest that SIRT1 mediates the induction of hBD2 and IL-8 gene expression levels in A549 cell by S. pneumoniae. SIRT1 may play a key role in host immune and defense response in A549.

Development of dual‐channel surface plasmon resonance imaging system applied to living tumour cell analyses

Presented is homemade dual-channel surface plasmon resonance (SPR) imaging (SPRI) system enabling living cell analysis in various stimuli based on refractive index (RI) variations. The system was constructed with a laser source of 650 nm, a P-polariser, a glass prism, an objective lens, a CCD camera, a dual-channel gold sensor chip, a dual-channel PDMS flow cell and a mechanical scanning device. Living human type II alveolar epithelial cell line A549 cells were cultured on the surface of a gold sensor chip. Different solutions were loaded into two independently parallel flow channels to make comparison of the cells’ reaction results. Cells' responses in both the testing and the reference channels with and without K+ stimuli were collected. Furthermore, the epidermal growth factor (EGF) was loaded to stimulate cells in the testing channel while a mixture of EGF and Iressa (ZD1839) were loaded in the reference channel. The SPR response signal was different from the two channels, which indicated that Iressa as an EGFR inhibitor effectively inhibited the signal transduction of the EGF and EGFR bonding process of A549 cells. The use of the dual-channel SPRI system to study the behaviour of living cells to stimuli is of great help in understanding the life activities of living cells.

An Anti-Cancer Cordycepin Produced by Cordyceps militaris Growing on the Dead Larva of Bombyx mori Silkworm

In this study, we introduced the dead pupa and larva of Bombyx mori silkworms as nutrition medium for the growing of different fungi including Cordyceps militaris, Isaria tenuipes and Isaria farinose to produce Cordyceps mycelia and anti-cancer cordycepin. The anti-proliferative and anti-migratory activities of cordycepin extracted toward cancer cells were investigated. We found that the dead silk larva which contained high carbohydrate and moisture but low fat content could be a good host for the growth of Cordyceps militaris and Isaria tenuipes to produce Cordyceps. The cordycepin extracted from Cordyceps mycelia of Cordyceps militaris grown on dead silk larva showed the highest anti-proliferative potential toward human non-small cell lung cancer NCI-H460 cells with a half maximal inhibitory concentration (IC50) of 0.7 µM. Furthermore, the viability of human lung adenocarcinoma epithelial A549 cell line remained < 20% while that of human airway epithelial Calu-3 cell line was < 40% after treated with the cordycepin extracted (0.125-2 µM) due to the disruption of cell membrane by cordycepin. We also found that our cordycepin (0.25-2 µM) could inhibit the migration of A549 cells. On the other hand, the cordycepin was not toxic to small airway epithelial cells (SAEC) of non-cancer cells. Therefore, Cordyceps militaris grown on the dead larva of B. mori silkworms was introduced as a promising source for the production of Cordyceps mycelia and anti-cancer cordycepin without toxicity to non-cancer cells.

Characteristics and cellular effects of ambient particulate matter from Beijing

In vitro tests using human adenocarcinomic alveolar epithelial cell line A549 and small mouse monocyte-macrophage cell line J774A.1 were conducted to test toxicity of six PM (particulate matter) samples from Beijing. The properties of the samples differ significantly. The production of inflammatory cytokine (TNF-α for J774A.1) and chemokine (IL-8 for A549) and the level of intracellular reactive oxygen species (ROS) were used as endpoints. There was a positive correlation between water soluble organic carbon and DTT-based redox activity. Both cell types produced increased levels of inflammatory mediators and had higher level of intracelllar ROS, indicating the presence of PM-induced inflammatory response and oxidative stress, which were dose-dependent and significantly different among the samples. The releases of IL-8 from A549 and TNF-α from J774A.1 were significantly correlated to PM size, Zeta potential, endotoxin, major metals, and polycyclic aromatic hydrocarbons. No correlation between ROS and these properties was identified.

TMEM16A protein attenuates lipopolysaccharide-mediated inflammatory response of human lung epithelial cell line A549

ABSTRACTObjective: To observe the expression of endogenous TMEM16A in rat alveolar type II epithelial cells (AT-II) and A549, and study the effect of TMEM16A on lipopolysaccharide (LPS)-induced proinflammatory cytokine secretion. Methods: Rat AT-II cells were isolated and TMEM16A protein expression in rat AT-II cells was measured by Western blot. TMEM16A mRNA and protein expressions in A549 were measured by real-time quantitative polymerase chain reaction (PCR) and Western blot, respectively. TMEM16A gene was transfected into A549 using Lipofectamine 2000. Transfected cells were selected in the presence of G418 to create a stable TMEM16A overexpression A549 cell line. The expression of TMEM16A in A549 was knocked down by lentiviral vector-mediated RNA interference. TNF-α and IL-8 levels were determined by enzyme-linked immunosorbent assay (ELISA). A dual-luciferase reporter assay system was used to measure the transcriptional activity of NF-κB. Results: (1) Endogenous TMEM16A was expressed in rat AT-II and A549. (2) TMEM16A expression in A549 significantly increased at 24 hours and 36 hours, and then decreased at 48 hours after LPS treatment. (3) TMEM16A mRNA and protein expressions were increased in the stable TMEM16A overexpression A549 cell line. (4) TMEM16A overexpression decreased the LPS-induced TNF-α and IL-8 secretions. (5) TMEM16A mRNA and protein expressions were knocked down in TMEM16A-siRNA lentivirus transfected A549. (6) TMEM16A knockdown increased the LPS-induced TNF-α and IL-8 secretions. (7) TMEM16A overexpression inhibited LPS-induced NF-κB activation. Conclusions: TMEM16A is expressed in AT-II. TMEM16A in A549 inhibits LPS-induced NF-κB activation and decreases proinflammatory cytokines release, protecting A549 from acute LPS-mediated damage.

Highly Stable Positively Charged Dendron-Encapsulated Gold Nanoparticles

We report the development of a novel cationic dendron (TAG1-PCD) and a positively charged gold nanoparticle-dendron conjugate (PCD-AuNP). TAG1-PCD was designed by considering the reactivity, hydrophilicity, and cationic nature that is required to yield a stable gold conjugate in aqueous media. The PCD-AuNPs, nominally 10 nm in size, were synthesized by reduction of chloroauric acid in the presence of TAG1-PCD. The physicochemical properties of PCD-AuNPs were characterized by dynamic light scattering, transmission electron microscopy, UV-vis absorbance, and X-ray photoelectron spectroscopy for investigation of size distribution, shape uniformity, surface plasmon resonance bands, and Au-dendron bonding. Asymmetric-flow field flow fractionation was employed to confirm the in situ size, purity, and surface properties of the PCD-AuNPs. Additionally, the stability of PCD-AuNPs was systematically evaluated with respect to shelf life determination, stability in biological media and a wide range of pH values, chemical resistance against cyanide, redispersibility from lyophilized state, and stability at temperatures relevant to biological systems. Dose dependent cell viability was evaluated in vitro using the human lung epithelial cell line A549 and a monkey kidney Vero cell line. Observations from in vitro studies are discussed. Overall, the investigation confirmed the successful development of stable PCD-AuNPs with excellent stability in biologically relevant test media containing proteins and electrolytes, and with a shelf life exceeding 6 months. The excellent aqueous stability and apparent lack of toxicity for this conjugate enhances its potential use as a test material for investigating interactions between positively charged NPs and biocellular and biomolecular systems, or as a vehicle for drug delivery.

Epithelial–mesenchymal transition involved in pulmonary fibrosis induced by multi-walled carbon nanotubes via TGF-beta/Smad signaling pathway

Multi-walled carbon nanotubes (MWCNT) are a typical nanomaterial with a wide spectrum of commercial applications. Inhalation exposure to MWCNT has been linked with lung fibrosis and mesothelioma-like lesions commonly seen with asbestos. In this study, we examined the pulmonary fibrosis response to different length of MWCNT including short MWCNT (S-MWCNT, length=350–700nm) and long MWCNT (L-MWCNT, length=5–15μm) and investigated whether the epithelial–mesenchymal transition (EMT) occurred during MWCNT-induced pulmonary fibrosis. C57Bl/6J male mice were intratracheally instilled with S-MWCNT or L-WCNT by a single dose of 60μg per mouse, and the progress of pulmonary fibrosis was evaluated at 7, 28 and 56 days post-exposure. The in vivo data showed that only L-MWCNT increased collagen deposition and pulmonary fibrosis significantly, and approximately 20% of pro-surfactant protein-C positive epithelial cells transdifferentiated to fibroblasts at 56 days, suggesting the occurrence of EMT. In order to understand the mechanism, we used human pulmonary epithelial cell line A549 to investigate the role of TGF-β/p-Smad2 signaling pathway in EMT. Our results showed that L-MWCNT downregulated E-cadherin and upregulated α-smooth muscle actin (α-SMA) protein expression in A549 cells. Taken together, both in vivo and in vitro study demonstrated that respiratory exposure to MWCNT induced length dependent pulmonary fibrosis and epithelial-derived fibroblasts via TGF-β/Smad pathway.

Effects of fullerene C60 nanoparticles on A549 cells

Fullerene C60 nanoparticles (C60 NPs) have been widely applied in many fields due to their excellent physical and chemical properties. As production and applications of C60 NPs expand, public concern about the potential risk to human health has also risen. The toxicity of C60 NPs was evaluated by the CCK-8 assay using the cultured human epithelial cell line A549. Cellular uptake of the C60 NPs was observed by TEM imaging. In our findings, C60 NPs could readily enter A549 cells and showed no significant toxicity. Exposure of cultured A549 cells to C60 NPs led to an increase of intracellular reactive oxygen species (ROS) while glutathione reductase activity was probably activated to generate more GSH to maintain a cellular oxidation–reduction equilibrium. The A549 cells responded to the ROS increases through the inauguration of autophagic responses, aimed at restoring cellular health and equilibrium.

NANOTOXICITY OF MULTIWALL CARBON NANOTUBES TO A549 CELLS IN VITRO

Multiwall carbon nanotubes (MWCNTs) have been widely applied in many fields due to the excellent physical and chemical properties. As the production and applications of nanotubes expand, public concern about their potential risks to human health has also raised. Cytotoxicity of MWCNTs was evaluated in this study using a cultured human epithelial cell line A549. Uptake of MWCNTs by cultured A549 cells was observed by TEM imaging. Dose-dependent decrease of cell viability showed the cytotoxicity of MWCNTs. Significant reactive oxygen species (ROS) generation and GSH depletion which reduced the cellular antioxidant level could be the major factor of cytotoxicity induced by MWCNTs. MWCNTs seemed to trigger the activation of cell autophagy with the intracellular ATG16L1 level increase as a defense mechanism.

Differential signaling of inducible nitric oxide synthase induction in Mycobacterium tuberculosis infected alveolar epithelial cell line A549 in response to cytokines IFN-γ, TNF-α and IL-1β

BackgroundIn earlier studies, it was shown that ex vivo Mycobacterium tuberculosis-infected type II alveolar epithelial cells generate de novo nitric oxide (NO), but the mycobactericidal quantity of NO was released only by stimulation of these cells with proinflammatory cytokines, i.e. IFN-γ, TNF-α and IL-1β. In the present communication, it was demonstrated that M. tuberculosis-infected/mycobacterial antigens stimulated cells utilize both, JAK-STAT and NF-κB pathways for the induction of inducible Nitric Oxide Synthase (iNOS) mRNA and NO production. MethodsAlveolar epithelial cell line A549 were either infected with M. tuberculosis or stimulated with M. tuberculosis components. Confocal microscopy, NO estimation and EMSA were performed on the infected/stimulated A549 cells. ResultsNuclear extracts prepared from M. tuberculosis infected A549 cells alone or stimulated with IFN-γ or a combination of three cytokines (IFN-γ, TNF-α and IL-1β) formed DNA protein complexes with probes from both −5.2kb region (specific for binding of STAT-1 protein) and −5.8kb region (specific for binding of both STAT-1 and NF-κB) of the iNOS promoter. However, TNF-α or IL-1β stimulated M. tuberculosis-infected A549 cells showed no protein DNA complexes with construct from −5.2kb region. ConclusionsThis differential response indicated that TNF-α/IL-1β does not allow STAT-1 production or its translocation to nucleus in M. tuberculosis-infected A549 cells in the absence of IFN-γ. This differential signaling of iNOS induction in M. tuberculosis-infected alveolar epithelial cells by cytokines may be responsible for controlled production of NO intracellularly.

Involvement of epithelial-mesenchymal transition in methotrexate-induced pulmonary fibrosis

Epithelial-mesenchymal transition (EMT) plays a pivotal event in the development of pulmonary fibrosis. We have previously reported that methotrexate (MTX)-induced alveolar epithelial cell injury followed by pulmonary fibrosis as a result of the recruitment and proliferation of myofibroblasts. However, there is no data concerning whether EMT occurs in MTX-induced pulmonary fibrosis. In the present study, therefore, we investigated the expression of EMT markers such as E-cadherin, α-SMA, and vimentin by immunofluorescence analysis in mouse lung tissues after administration of MTX. We found that vimentin and α-SMA-positive cells of the MTX-induced pulmonary fibrosis were increased; on the other hand, E-cadherin was decreased, indicating that epithelial cells act as the main source of mesenchymal expansion. These results exhibited the down-regulation of E-cadherin expression and the up-regulation of α-smooth muscle actin (α-SMA) in primary mouse alveolar epithelial cells (MAECs) and A549 cell lines. Additionally, MTX-induced A549 cells exhibited an EMT-like phenotype accompanied by the elevation of the expression of interleukin-6 (IL-6) and transforming growth factor (TGF)-β1, as well as an enhancement of migration. All of these findings suggest that MTX-induced pulmonary fibrosis occurs via EMT.

Effect of CDH1 gene methylation on transforming growth factor (TGF-β)-induced epithelial-mesenchymal transition in alveolar epithelial cell line A549

The aim of this study was to investigate the specific molecular mechanism of the transforming growth factor β (TGF-β)-induced epithelial-mesenchymal transition in a lung cancer cell line, and to provide new ideas for targeting therapy of lung cancer. A549 cells were treated with different concentrations of TGF-β and 5-aza-deoxycytidine (5-aza-dC). The morphological changes after the intervention were observed. The change in the expression of the epithelial marker E-cadherin (E-cad) was detected by Western blot. The proliferation of A549 cells was measured using the MTT assay. Cell movement and invasion capacity was evaluated with the cell scratch test and invasion test. TGF-β induced A549 cells to transform to a mesenchymal cell morphology and downregulated the expression of E-cad, and 5-aza-dC inhibited this phenomenon. Compared with the control group, the number of transmembrane cells was higher and cell migration was markedly increased in the experimental group with continued culture in the presence of 10 ng/mL TGF-β, showing significant differences (P < 0.05). CDH1 gene methylation is involved in TGF-β-induced epithelial-mesenchymal transition in the alveolar epithelial cell line A549.

Cyto-genotoxicity Assessment of Potential Anti-tubercular Drug Candidate Molecule-trans-cyclohexane-1, 4-diamine Derivative-9u in Human Lung Epithelial Cells A549.

Increasing incidences of multiple drug-resistance (MDR) in Mycobacterium tuberculosis are emerging as one among the serious public health threats and socio-economic burden to the third world countries including India. Last couples of decades are witnesses of the dedicated and sustained efforts made toward the development of target specific and cost-effective antimicrobial agents against MDR-M. tuberculosis. However, the drugs in use are still incapable of controlling the upsurge of MDR. Thus, in order to address the issue, we synthesized a library of symmetrical trans-cyclohexane-1, 4-diamine derivatives and evaluated their anti-mycobacterium activity in H37RV strain of M. tuberculosis. A range of efficacy has been recorded in different derivatives of synthesized compounds and compound “9u” having i-propyl group substitution at p-position, was found to have more significant detrimental effects against the tested strain of M. tuberculosis. The present investigations were aimed to study whether the effective anti-mycobacterium concentrations of “9u” are biologically safe to human cells or not? The human lung epithelial cell line-A549 were exposed to a range of concentrations, i.e., at and above the anti-mycobacterium effective dose of “9u” for a period of 0-96 h. The standard endpoints of cytotoxicity viz., tetrazolium bromide salt (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide), neutral red uptake, lactate dehydrogenase release, trypan blue dye exclusion assays; and genotoxicity viz., micronucleus and chromosomal aberrations assays were used to evaluate the bio-safety of test compound. The compound “9u” shows no significant cytotoxicity and genotoxicity in A549 cells exposed to 10-5 M for 72 h, a concentration substantially higher than the concentration kill the H37Rv strain of M. tuberculosis. The compound 9u was found to be safe up to 10-4 M if given for 24 h. The data reveal the therapeutic potential of compound 9u against M. tuberculosis without any having any cytotoxicity and genotoxicity responses.

Different effects of a novel CaO–MgO–SiO2-based multiphase glass–ceramic on cell behaviors of normal and cancer cells in vitro

The effects in vitro of a novel multiphase glass–ceramic (with nominal composition of 43.19% CaO, 7.68% MgO, and 49.13% SiO2 in weight percent) on cell adhesion, proliferation, differentiation and ultrastructure of human osteosarcoma cell line MG63, mouse fibroblasts L929, and human lung adenocarcinoma epithelial cell line A549 were investigated in this research. Scanning electron microscopy (SEM) micrographs revealed that the surface morphology of this glass–ceramic was beneficial to cell adhesion. The glass–ceramic extracts at certain concentrations could stimulate the proliferation and differentiation of MG63 and L929 cells, whereas inhibit A549 proliferation, which might be resulted from the released Si ions. In addition, when cultured with 0.1mg/mL glass–ceramic powder suspension, the cell ultrastructure of MG63 showed abundant organelles and L929 displayed the phenomena of cellular stress response. While more interestingly, A549 exhibited chromatin condensation, mitochondria swell and RER expansion, which was presumed to be early signs of apoptosis. These results suggest that this novel CaO–MgO–SiO2-based multiphase glass–ceramic has potential for bone regeneration and tissue engineering applications.

Inhibition of toll-like receptor 2 (TLR-2)-mediated response in human alveolar epithelial cells by mycolic acids andMycobacterium tuberculosismce1operon mutant

In human lungs, the earliest encounter of Mycobacterium tuberculosis, the agent of tuberculosis, involves alveolar epithelial cells. Droplets expectorated by a patient with tuberculosis are likely to contain a mixed population of M.tuberculosis cells in different physiologic and metabolic states from the lung lesions of the patient. Here, we compared the chemokine expression patterns of human epithelial cell line A549 and RAW 264.7 macrophage cells infected with wild-type M.tuberculosis H37Rv against patterns induced by a mutant that accumulates free mycolic acids in its cell wall (Δmce1). We also examined the effect of free mycolic acids on toll-like receptor-2 (TLR-2). Wild-type M.tuberculosis induced significantly higher levels of IL-8, MCP-1, RANTES, and IP-10 in both cell types than did Δmce. Free mycolic acids reduced the ability of the mammalian cells to respond to a TLR-2 agonist in a dose-dependent manner. These observations suggest that differences in mycolic acid abundance in the M.tuberculosis cell wall can affect TLR-2-mediated pro-inflammatory response in both epithelial and macrophage cells. The final fate of a new infection may be ultimately determined by the proportion of M. tuberculosis cells expressing free mycolates in the infecting inoculum population.

The antimicrobial effect of silicon nanowires decorated with silver and copper nanoparticles

The paper reports on the preparation and antibacterial activity of silicon nanowire (SiNW) substrates coated with Ag or Cu nanoparticles (NPs) against Escherichia coli (E. coli) bacteria. The substrates are easily prepared using the metal-assisted chemical etching of crystalline silicon in hydrofluoric acid/silver nitrate (HF/AgNO3) aqueous solution. Decoration of the SiNWs with metal NPs is achieved by simple immersion in HF aqueous solutions containing silver or copper salts. The SiNWs coated with Ag NPs are biocompatible with human lung adenocarcinoma epithelial cell line A549 while possessing strong antibacterial properties to E. coli. In contrast, the SiNWs decorated with Cu NPs showed higher cytotoxicity and slightly lower antibacterial activity. Moreover, it was also observed that leakage of sugars and proteins from the cell wall of E. coli in interaction with SiNWs decorated with Ag NPs is higher compared to SiNWs modified with Cu NPs.