Inflammatory Response Of Epithelial Cells Research Articles

Chloride intracellular channel 4 participates in the regulation of lipopolysaccharide-induced inflammatory responses in human bronchial epithelial cells

The airway epithelium is located at the interactional boundary between the external and internal environments of the organism and is often exposed to harmful environmental stimuli. Inflammatory response that occurs after airway epithelial stress is the basis of many lung and systemic diseases. Chloride intracellular channel 4 (CLIC4) is abundantly expressed in epithelial cells. The purpose of this study was to investigate whether CLIC4 is involved in the regulation of lipopolysaccharide (LPS)-induced inflammatory response in airway epithelial cells and to clarify its potential mechanism. Our results showed that LPS induced inflammatory response and decreased CLIC4 levels in vivo and in vitro. CLIC4 silencing aggravated the inflammatory response in epithelial cells, while overexpression of CLIC4 combined with LPS exposure significantly decreased the inflammatory response compared with cells exposed to LPS without CLIC4 overexpression. By labeling intracellular chloride ions with chloride fluorescent probe MQAE, we showed that CLIC4 mediated intracellular chloride ion-regulated LPS-induced cellular inflammatory response.

Activation of ERK/NF-kB Pathways Contributes to the Inflammatory Response in Epithelial Cells and Macrophages Following Manganese Exposure.

Different types of metals, including manganese (Mn), are constantly encountered in various environmental matrices due to natural and anthropogenic activities. They induce a sustained inflammatory response in various organs, which is considered to be an important priming event in the pathogenesis of several diseases. Mn-induced neuroinflammation and subsequent neurodegeneration are well recognized. However, emerging data suggest that occupationally and environmentally relevant levels may affect various organs, including the lungs. Therefore, the present study was carried out to investigate the effects of Mn (as Mn2+) exposure on the inflammatory response in human normal bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells, as well as in murine macrophages (J774). Mn2+ exposure significantly induced mRNA and protein expression of various pro-inflammatory mediators (cytokines and chemokines) in all cells compared to corresponding vehicle controls. Furthermore, Mn2+ treatment also led to increased phosphorylation of extracellular-signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-kB) p65 in both epithelial cells and macrophages. As expected, cells treated with inhibitors of ERK1/2 (PD98059) and NF-kB p65 (IMD0354) effectively mitigated the expression of various pro-inflammatory mediators induced by Mn2+, suggesting that ERK/NF-kB pathways have a critical role in the Mn2+-induced inflammatory response. Further, in vivo studies are required to confirm these in vitro findings to support clinical translation.

Therapeutic effect and mechanism of silver nanowires on radiation pneumonitis by inhibiting the excessive inflammatory response of epithelial cells

Three new silver nanowire (Ag NW) samples with different diameters and lengths were synthesized by the polyol synthesis method. The diameter and length of Ag NWs 1–3 with high yield and purity were regulated by changing the amount of Fe3+ ions at 140 °C, producing new synthesized methods in designing and obtaining Ag NWs with desired size and morphology. Samples Ag NWs 1–3 were fully characterized by scanning electron microscopy and powder X-ray diffraction. ELISA was further conducted to measure the release of TNF-α and TGF-β1 from epithelial cells after Ag NWs 1–3 treatment. Then, real time RT-PCR was performed, and the activation of AMPK signaling pathway in epithelial cells was evaluated.

Two Co(II)-Metal Organic Frameworks (MOFs): Therapeutic Effect and Mechanism on Radiation Pneumonitis by Inhibiting the Excessive Inflammatory Response of Epithelial Cells

[Co(L1)2(HCOO)] (1) and [Co2(HL2)2(CH3COO)·(NH2)(CH3)] (2) [HL1 = 4-pyridinecarboxylic acid 1-oxide, HL2 = 4-(1H-tetrazol-5-yl)benzoic acid], are new 3D coordination polymers that were successfully obtained via solvothermal conditions as determined by elemental analysis and Fourier transform infrared spectroscopy. Single-crystal diffraction analysis showed that 1 and 2 have 3D porous structures that depend on secondary building units. Furthermore, the application values of the newly developed compounds on radiation pneumonitis were determined, and the corresponding mechanism was examined. First, enzyme-linked immunosorbent assay was performed work to measure the plasma-released inflammatory cytokine content. Then, real-time polymerase chain reaction was used to organize and observe the activation of the AMPK signaling pathway.

Targeting NF-κB mediated cell signaling pathway and inflammatory mediators by 1,2-diazole in A549 cells in vitro

Lung cancer is the leading cause of cancer deaths globally. The objective of this study was to investigate the effect of 1,2-diazole (pyrazole) as an anti-cancer drug on human non-small cell lung carcinoma A549 cells. We attempt to examine the expression level of pro-inflammatory proteins such as TNF-α, NF-κB-p65, MMP-2 and E-Cadherin which are commonly associated with an inflammatory response in epithelial cells and apoptosis in A549 cells. The LPS-induced cytokines and inflammatory mediators include TNF-α, IL-6, iNOS and COX-2 levels in A549 cells and the effect of pyrazole was studied. The present study reveals that, pyrazole inhibits A549 cells by suppressing TNF-α induced MMP-2 expression, thereby inhibiting the nuclear translocation of NF-κB-p65. Pyrazole significantly up-regulate the E-cadherin level and down-regulated MMP-2 expression that could probably preventing A549 cancer cells to invade. The study further substantiated the anti-cancer property of pyrazole by regulating the above mentioned level of LPS-induced cytokines and inflammatory mediators. The observations of the present study open a possibility for the development of an effective therapeutic agent that targets inflammatory and signaling pathway mediators to challenge human non-small cell lung carcinoma.

SDF-1 in Mammary Fibroblasts of Bovine with Mastitis Induces EMT and Inflammatory Response of Epithelial Cells.

Fibroblasts constitute the majority of the stromal cells within bovine mammary gland, yet the functional contributions of these cells to mastitis and fibrosis and the mechanism are poorly understood. In this study, we demonstrate that inflammation-associated fibroblasts (INFs) extracted from bovine mammary glands with clinical mastitis had different expression pattern regarding to several extracellular matrix (ECM) proteins, chemokines and cytokines compared to normal fibroblasts (NFs) from dairy cows during lactation. The INFs induced epithelial-mesenchymal transition (EMT) and inflammatory responses of mammary epithelial cells in a vitro co-culture model. These functional contributions of INFs to normal epithelial cells were mediated through their ability to secrete stromal cell-derived factor 1 (SDF-1). SDF-1 was highly secreted/expressed by INFs, lipopolysaccharide (LPS) -treated NFs, lipoteichoic acid (LTA) -treated NFs, as well as mastitic tissue compared to their counterparts. Exogenous SDF-1 promoted EMT on epithelial cells through activating NF-κB pathway, induced inflammation response and inhibited proliferation of epithelial cells. In addition, SDF-1 was able to induce mastitis and slight fibrosis of mouse mammary gland, which was attenuated by a specific inhibitor of the receptor of SDF-1. Our findings indicate that stromal fibroblasts within mammary glands with mastitis contribute to EMT and inflammatory responses of epithelial cells through the secretion of SDF-1, which could result in the inflammation spread and fibrosis within mammary gland.

Antibacterial activity and immunomodulatory effects on a bovine mammary epithelial cell line exerted by nisin A-producing Lactococcus lactis strains

Twenty-nine strains of mastitis pathogens were used to study the antibacterial activity of the cell-free supernatants (CFS) of 25 strains of Lactococcus lactis ssp. lactis. Out of the tested strains, only the CFS of L. lactis LL11 and SL153 were active, inhibiting and killing most of the pathogens. By means of ultra-performance liquid chromatography/high resolution mass spectrometry, they were shown to produce nisin A, a class I bacteriocin. A variable sensitivity to nisin A-containing CFS was observed among Streptococcus uberis and Enterococcus faecalis strains. Nonetheless, Streptococcus agalactiae, Strep. uberis, and E. faecalis displayed high minimum inhibitory concentration values, reaching 384 arbitrary units/mL. Interestingly, the minimum inhibitory values and the bactericidal concentrations were almost identical among them for each of the 2 stains, LL11 and SL153. Staphylococci were, on average, less sensitive than streptococci, but the 2 CFS inhibited and killed, at different dilutions, strains of methicillin-resistant Staphylococcus aureus. The immune response to nisin A-containing CFS was tested using the bovine mammary epithelial cell line BME-UV1. Application of CFS did not damage epithelial integrity, as demonstrated by the higher activity of N-acetyl-β-d-glucosaminidase (NAGase) and lysozyme inside the cells, in both treated and control samples. On the other hand, the increase of released NAGase after 15 to 24h of treatment with LL11 or SL153 live cultures demonstrated an inflammatory response of epithelial cells. Similarly, a significantly higher lysozyme activity was detected in the cells treated with LL11 live culture confirming the stimulation of lysosomal activity. The treatment of epithelial cells with SL153 live culture induced a significant tumor necrosis factor-α downregulation in the cells, but did not influence IL-8 expression. The control of tumor necrosis factor-α release could be an interesting approach to reduce the symptoms linked to clinical intramammary infections. Due to their antibacterial activity and to the stimulation of lysosomal activity of mammary epithelial cells, the L. lactis strains SL153 and LL11 could be of interest for the development of alternative intramammary treatments to control cow mastitis.

Piperine Suppresses the Expression of CXCL8 in Lipopolysaccharide-Activated SW480 and HT-29 Cells via Downregulating the Mitogen-Activated Protein Kinase Pathways.

The anti-inflammatory effect of piperine has been largely investigated in macrophages, but its activity on epithelial cells in inflammatory settings is unclear. The present study aimed to investigate the effect of piperine on the expression of inflammatory cytokines in lipopolysaccharide (LPS)-stimulated human epithelial-like SW480 and HT-29 cells. Our data showed that although piperine inhibited the proliferation of SW480 and HT-29 cells in a dose-dependent manner, it had low cytotoxicity on these cell lines with 50 % inhibiting concentration (IC50) values greater than 100 μM. As epithelial-like cells, SW480 and HT-29 cells secreted high levels of the chemokine CXCL8 upon LPS stimulation. Importantly, piperine dose-dependently suppressed LPS-induced secretion of CXCL8 and the expression of CXCL8 messenger RNA (mRNA). Although piperine failed to affect the critical inflammatory nuclear factor-κB pathway, it attenuated the c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) signaling. Consistent with previous reports, p38 signaling seemed to play a more pronounced role on the CXCL8 expression than JNK signaling since inhibition of p38, instead of JNK, greatly suppressed LPS-induced CXCL8 expression. Collectively, our results indicated that piperine could attenuate the inflammatory response in epithelial cells via downregulating the MAPK signaling and thus the expression of CXCL8, suggesting its potential application in anti-inflammation therapy.

Identification of the Flagellin Glycosylation System in Burkholderia cenocepacia and the Contribution of Glycosylated Flagellin to Evasion of Human Innate Immune Responses

Burkholderia cenocepacia is an opportunistic pathogen threatening patients with cystic fibrosis. Flagella are required for biofilm formation, as well as adhesion to and invasion of epithelial cells. Recognition of flagellin via the Toll-like receptor 5 (TLR5) contributes to exacerbate B. cenocepacia-induced lung epithelial inflammatory responses. In this study, we report that B. cenocepacia flagellin is glycosylated on at least 10 different sites with a single sugar, 4,6-dideoxy-4-(3-hydroxybutanoylamino)-D-glucose. We have identified key genes that are required for flagellin glycosylation, including a predicted glycosyltransferase gene that is linked to the flagellin biosynthesis cluster and a putative acetyltransferase gene located within the O-antigen lipopolysaccharide cluster. Another O-antigen cluster gene, rmlB, which is required for flagellin glycan and O-antigen biosynthesis, was essential for bacterial viability, uncovering a novel target against Burkholderia infections. Using glycosylated and nonglycosylated purified flagellin and a cell reporter system to assess TLR5-mediated responses, we also show that the presence of glycan in flagellin significantly impairs the inflammatory response of epithelial cells. We therefore suggest that flagellin glycosylation reduces recognition of flagellin by host TLR5, providing an evasive strategy to infecting bacteria.

Lactoferrin differently modulates the inflammatory response in epithelial models mimicking human inflammatory and infectious diseases.

Conflicting data are reported on pro- or anti-inflammatory activity of bovine lactoferrin (bLf) in different cell models as phagocytes or epithelial cell lines infected by bacteria. Here we evaluated the bLf effect on epithelial models mimicking two human pathologies characterized by inflammation and infection with specific bacterial species. Primary bronchial epithelium from a cystic fibrosis (CF) patient and differentiated intestinal epithelial cells were infected with Pseudomonas aeruginosa LESB58 isolated from a CF patient and Adherent-Invasive Escherichia coli LF82 isolated from a Crohn's disease patient. Surprisingly, bLf significantly reduced the intracellular bacterial survival, but differently modulated the inflammatory response. These data lead us to hypothesize that bLf differentially acts depending on the epithelial model and infecting pathogen. To verify this hypothesis, we explored whether bLf could modulate ferroportin (Fpn), the only known cellular iron exporter from cells, that, by lowering the intracellular iron level, determines a non permissive environment for intracellular pathogens. Here, for the first time, we describe the bLf ability to up-regulate Fpn protein in infected epithelial models. Our data suggest that the mechanism underlying the bLf modulating activity on inflammatory response in epithelial cells is complex and the bLf involvement in modulating cellular iron homeostasis should be taken into account.

Reducing background cytokine expression in epithelial cells without serum starvation

Cellular excretion of inflammatory cytokines is an important experimental read-out in a wide range of molecular biology fields. The addition of serum to growth media provides the optimal growing conditions for most cell types. When studying the effect of bacteria and bacterial products on these cells serum starvation is often performed as a standard procedure [1] to avoid unwanted stimulation by the serum components. The full effect of serum starvation on cell behaviour and inflammatory responses is unknown, though it has been suggested to induce various responses that can interfere with experimental results and conclusions [2]. Serum starvation has been shown to cause cells to undergo apoptosis and autophagy [3,4] as well as superoxide production and increasing cell susceptible to inflammatory stimuli [5]. In order to study stimulation of healthy epithelial cells, a new approach was required that limited unwanted stimulation but supported normal cell growth. Analysis of different serum preparations on the background cytokine expression of renal epithelial cells demonstrated conditions in which the background cytokine expression can be reduced without the need to serum starve the cells. Endotoxin content was not found to be the most relevant factor in inducing an inflammatory response in epithelial cells. Charcoal stripped preparations of foetal bovine serum (FBS) produced the lowest background expression of IL-6 and IL-8 without the need for serum starvation.•Selection of the serum source allows for cytokine expression experiments to be performed without serum starvation.•Charcoal stripped preparations of FBS produces the lowest background cytokine expression without serum starvation.•Serum factors other than endotoxin content influence cytokine secretion.

Piclamilast inhibits the pro-apoptotic and anti-proliferative responses of A549 cells exposed to H2O2 via mechanisms involving AP-1 activation

Aims. Reactive oxygen species (ROS) are involved in the pathogenesis of many inflammatory diseases such as chronic obstructive pulmonary disease (COPD). They can alter the expression of genes involved in cellular damage by activating transcription factors, including the NF-κB and the activator protein 1 (AP-1). Phosphodiesterase type 4 (PDE4) inhibitors have anti-inflammatory and antioxidant effects, as described in in vivo and in vitro COPD models. This study analysed the effects of piclamilast, a selective PDE4 inhibitor, on modulating the global gene expression profile in A549 cells exposed to H2O2. Main methods. Changes in gene expression were analysed using high-density Affymetrix microarrays and validated by RT-PCR. Cell proliferation was studied using BrdU incorporation. Apoptosis was assessed by flow cytometry using annexin V-fluorescein isothiocyanate. C-Jun phosphorylation and AP-1 activation were determined by ELISA and luciferase assay, respectively. Key findings. Our results indicate that H2O2 modified the expression of several genes related to apoptosis, cell cycle control and cell signalling, including IL8, FAS, HIG2, CXCL2, CDKN25 and JUNB. Piclamilast pre-treatment significantly inhibited the changes in 23 genes via mechanisms involving AP-1 activation and c-Jun phosphorylation at Ser63. Functional experiments confirmed our results, suggesting new targets related to the antioxidant properties of PDE4 inhibitors. Significance. This is the first study to demonstrate antioxidant effects of a selective PDE4 inhibitor at the global gene expression level, and the results support the importance of AP-1 as a key regulator of the expression of genes involved in the inflammatory response of epithelial cells to oxidative damage.

COMPARISON OF EFFECTS INDUCED BY FORMALDEHYDE EXPOSURE ON ALVEOLAR AND BRONCHIAL EPITHELIAL CELLS IN VITRO

Background and Aims Exposure to formaldehyde (FA) at environmental concentrations is suspected to be associated to asthma and respiratory disorders. Nevertheless, the physiopathology of this relation is still unclear and experimental data are needed. In vitro experimentation is complementary to epidemiological studies. However experimental procedure parameters need to be adapted, such as the choice of target cells of respiratory tract. The aim of this study was to compare the inflammatory response of FA exposure at environmental level on alveolar and bronchial epithelial cells. Methods Human alveolar (A549) and bronchial (BEAS-2B) epithelial cells were exposed at the air-liquid interface in a Vitrocell exposure module to FA (50 μg/m3) (or air for control) during 30 min. After 24h post-incubation, cellular viability was assessed using LDH release. Two chemokines (IL-8, MCP-1) were assayed in the apical supernatant by ELISA. In addition, to modulate inflammatory response, pre-sensitization was performed using LPS (5 μg/mL) (to mimic a bacterian activation), TNFα (1 ng/mL) or macrophages conditioned media (to mimic the macrophages/epithelial cells cooperation) during 16h before exposure. Results Whatever the cell type, cell viability was unaffected by air or FA exposure compared to cells not exposed at the air-liquid interface. Without presensitization or after LPS presensitization, FA had not effect on A549 or BEAS-2B, compared to air-exposed cells. FA exposure, after TNFα presensitization, resulted in an inflammatory response, an increase of IL-8 production by A549 cells; after macrophage conditioned media presensitization, an increase of IL-8 production by A549 cells, and decrease of MCP-1 production by BEAS-2B cells was observed. Conclusions After presensitization FA exposure at environmental levels provokes an inflammatory response in epithelial cells of the respiratory tract. Moreover, this response is differently modulated depending on the level of the cells in the respiratory tract.

MUC1-C Oncoprotein Promotes STAT3 Activation in an Autoinductive Regulatory Loop

Signal transducer and activator of transcription 3 (STAT3) is activated in human breast cancer and other malignancies. Mucin 1 (MUC1) is a heterodimeric cell surface glycoprotein that is overexpressed in human carcinomas and, like STAT3, promotes cell survival and induces transformation. We found that in breast cancer cells, the MUC1 carboxyl-terminal receptor subunit (MUC1-C) associates with the gp130-Janus-activated kinase 1 (JAK1)-STAT3 complex. The MUC1-C cytoplasmic domain interacted directly with JAK1 and STAT3, and MUC1-C was necessary for JAK1-mediated STAT3 activation. In turn, MUC1-C and activated STAT3 occupied the promoter of MUC1, and MUC1-C contributed to STAT3-mediated activation of MUC1 transcription. The MUC1-C inhibitor GO-201 blocked the MUC1-C interaction with STAT3, thereby decreasing MUC1-C and STAT3 occupancy on the MUC1 and STAT3 promoters and activation of STAT3 target genes, including MUC1 itself. These findings indicate that MUC1-C promotes STAT3 activation and that MUC1-C and STAT3 function in an autoinductive loop that may play a role in cancer cell survival.

Inflammatory response in epithelial cells induced by mechanical stress is suppressed by hyaluronic acid

Hyaluronic acid (HA) is a widely distributed component of the extracellular matrix that has been shown to play regulatory roles in inflammation. In the present study, we examined the inhibitory mechanism of HA related to mechanical stress-induced inflammatory response in mouse gingival epithelial GE1 cells. Application of compressive force in a three-dimensional cell culture system increased the expression of cyclooxygenase-2 (COX-2) mRNA in a force-dependent manner, while COX-2 protein and prostaglandin E2 (PGE2) levels were also increased in a time-dependent manner. Interestingly, we found that HA suppressed the expression of COX-2 and production of PGE2 under the same conditions. Western blotting analysis revealed that mechanical stress induced the phosphorylation of ERK and p38 MAPK at 60 minutes after loading, while that of IκBα was activated at 15 minutes and peaked at 30 minutes. In addition, IκBα degradation was activated at 30 minutes and recovered at 60 minutes. Furthermore, treatment with HA down-regulated the phosphorylation of p38 MAPK, ERK, and IκBα in GE1 cells. These results indicate that mechanical stress enhances the induction of COX-2 and PGE2 in epithelial cells, while HA inhibits those mechanical stress-induced inflammatory responses via MAPKs and the NF-κB signaling pathway.

EnterohemorrhagicEscherichia colisuppresses inflammatory response to cytokines and its own toxin

Infection with the enteric pathogen enterohemorrhagic Escherichia coli (EHEC) causes a variety of symptoms ranging from nonbloody diarrhea to more severe sequelae including hemorrhagic colitis, altered sensorium and seizures, and even life-threatening complications, such as hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. The more severe consequences of EHEC infection are attributable to the production of Shiga toxin (Stx) and its subsequent effects on the vasculature, which expresses high levels of the Stx receptor, Gb3. Interestingly, the intestinal epithelium does not express Gb3. Despite the lack of Gb3 receptor expression, intestinal epithelial cells translocate Stx. The effect of Stx on intestinal epithelial cells is controversial with some studies demonstrating induction of inflammation and others not. This may be difficult to resolve because EHEC expresses both proinflammatory molecules, such as flagellin, and factor(s) that dampen the inflammatory response of epithelial cells. The goal of our study was to define the effect of Stx on the inflammatory response of intestinal epithelial cells and to determine whether infection by EHEC modulates this response. Here we show that Stx is a potent inducer of the inflammatory response in intestinal epithelial cells and confirm that EHEC attenuates the induction of IL-8 by host-derived proinflammatory cytokines. More importantly, however, we show that infection with EHEC attenuates the inflammatory response by intestinal epithelial cells to its own toxin. We speculate that the ability of EHEC to dampen epithelial cell inflammatory responses to Stx and cytokines facilitates intestinal colonization.

Alterations in immune response and PPAR/LXR regulation in cystic fibrosis macrophages

Background Cystic fibrosis (CF) is characterized by an excessive inflammatory response in epithelial cells and macrophages. In CF mice, lung inflammation can be abrogated by oral treatment with docosahexaenoic acid (DHA). Since PPARs and LXRs are important regulators of inflammation and fatty acid metabolism in macrophages, we hypothesized that these pathways are dysregulated in CF macrophages and are corrected with DHA treatment. Methods Peritoneal macrophages were obtained from wild type and cftr −/− mice. LPS induced cytokine secretion and NFκB activity were analyzed with and without oral DHA treatment. The expression and activity of PPARα,γ, δ and LXRα were analyzed by RT-PCR and EMSA. Results LPS induced TNFα and IL-6 secretion and NFκB p65 activity were increased in CF macrophages. This was associated with low basal PPARγ expression and attenuated LPS induced induction of PPARδ, LXRα and ABCA1. DHA pretreatment in vivo decreased TNFα secretion and p65 activity, and increased PPARα and γ expression and function. The effects of DHA could be reproduced by PPAR agonists and blocked by a PPARα antagonist. Conclusion Impaired regulation of nuclear receptors may contribute to the abnormal LPS induced signaling in CF macrophages and is reversed by DHA.

Aggregative adherence fimbriae contribute to the inflammatory response of epithelial cells infected with enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC) causes watery diarrhoea that is often mildly inflammatory. Previous studies have reported that the flagellin of EAEC induces IL-8 from intestinal epithelial cells (IECs) in culture. To characterize more fully the inflammatory response to EAEC, we infected IECs with EAEC prototype strain 042 and assessed cellular responses by macroarray and reverse transcriptase polymerase chain reaction (RT-PCR). Genes upregulated in 042-infected non-polarized T84 cells included IL-8, IL-6, TNF-alpha, GRO-alpha, GRO-gamma, ICAM-1, GM-CSF and IL-1alpha. RT-PCR analyses performed with cDNA from T84 and HT-29 cells infected with an aflagellar mutant (042fliC) suggested that these responses were primarily mediated by flagellin. To better reproduce the conditions of the infection for this non-invasive pathogen, we assessed the responses of polarized IECs to strain 042 infection. As expected, 042 induced IL-8 production from both polarized T84 and HT-29 cells. However, significant IL-8 secretion was induced in polarized T84 cells infected with 042fliC, suggesting that a factor other than flagellin contributes to inflammation in this model. This non-flagellar IL-8 response required expression of the aggregative adherence fimbria (AAF) adhesin, and was related to the presence of the minor fimbria-associated protein AafB. Our data suggest that multiple factors contribute to EAEC-induced inflammation, and further characterization of the nature of EAEC proinflammatory factors will greatly advance our understanding of this emerging pathogen.

71 Increased Pseudomonas aeruginosa-induced inflammatory response in epithelial cells expressing mutated CFTR

71 Increased Pseudomonas aeruginosa-induced inflammatory response in epithelial cells expressing mutated CFTR

Pro-inflammatory properties for thiazolidinediones

Thiazolidinediones (TZDs) are pharmacological ligands of the peroxisome proliferator-activated receptor (PPAR)-γ that are extensively used in the treatment of type II diabetes. Recently, an anti-inflammatory potential for TZDs has been suggested, based on observations that these compounds may inhibit pro-inflammatory cytokine expression in vitro and may attenuate the inflammatory response in vivo. Here, we show that the TZDs rosiglitazone (RSG) and troglitazone (TRO) do not inhibit the inflammatory response to tumor necrosis factor (TNF)-α in various epithelial cell types. On the contrary, both RSG and TRO significantly potentiated TNF-α-induced production of granulocyte/macrophage-colony-stimulating factor, interleukin (IL)-6 and/or IL-8 in these cells. This increase in pro-inflammatory cytokine expression was functionally significant as supernatants from cells co-treated with TNF-α and TZDs displayed increased neutrophil pro-survival activity when compared with supernatants from cells treated with TNF-α alone. Additionally, it was shown that TZDs enhance cytokine expression at the transcriptional level, but that the pro-inflammatory effects of TZDs are independent on PPARγ, nuclear factor κB or mitogen-activated protein kinase activation. Our study shows that TZDs may potentiate the inflammatory response in epithelial cells, a previously unappreciated effect of these compounds.