Nuclear Factor kappaB (NF-êB) is a transcription factor whose activation is increased in settings of allergic asthma. At least two parallel NF-êB pathways exist: the classical pathway, which plays a role in inflammation and cell survival, and the alternative pathway, which regulates lymphoid cell development and organogenesis. The classical NF-êB pathway regulates inflammatory responses derived from lung epithelial cells; however, the role of the alternative pathway in lung epithelial cells remains unclear. We demonstrate that both classical and alternative NF-êB are activated in lung epithelial cells in response to multiple pro-inflammatory agonists, and siRNA-mediated knockdown of alternative NF-êB proteins largely attenuates pro-inflammatory cytokine production. Furthermore, simultaneous activation of both pathways leads to cooperative increases in pro-inflammatory responses, indicating a potential role for both classical and alternative NF-êB in the regulation of epithelial-derived pro-inflammatory responses. NF-êB activation in the epithelium modulates allergic inflammation in mouse models of allergic airway disease, however, its role in the context of an allergen relevant to human asthma remains unknown. In order to address the impact of inhibition of NF-êB in the epithelium in vivo, we utilized a House Dust Mite (HDM)-induced model of allergic airway disease. We demonstrate that HDM exposure activates classical and alternative NF-êB in both murine lung epithelium and human bronchial epithelial cells. Furthermore, following exposure to HDM, airway hyperresponsiveness, neutrophilic inflammation, and remodeling are attenuated in transgenic CC10-NF-êBSR (airway epithelial specific inhibitor of classical and alternative NF-êB) mice in comparison to wild type mice. Our data also demonstrate that specific knockdown of the alternative NF-êB protein, RelB, in the lung partially protects against HDM-induced pro-inflammatory responses, indicating that both classical and alternative NF-êB are important in HDM-induced responses. NF-êB proteins are modified by the redox-dependent post-translational modification, S-glutathionylation, under conditions of oxidative stress. S-glutathionylation of IKKâ, an upstream kinase in the NF-êB pathway, is known to decrease its catalytic activity; however, it is unknown how S-glutathionylation of IKKâ occurs. GSTP is an enzyme that catalyzes protein S-glutathionylation under conditions of oxidative stress and has been associated with the development of allergic asthma. We aimed to determine whether GSTP regulates NF-êB signaling, S-glutathionylation of IKKâ, and pro-inflammatory cytokine production. We demonstrate that siRNA-mediated knockdown of GSTP modulates NF-êB activation, NF-êB transcriptional activity, and pro-inflammatory cytokine production in response to LPS, a component of a bacterial cell wall. Furthermore, we demonstrate that GSTP associates with IKKâ in response to agonist stimulation and dampens IKKâ-induced pro-inflammatory cytokine production, surprisingly, independent of its catalytic activity. We also show that GSTP associates with other proteins of the NF-êB pathway, indicating a potential dual mechanism for repression of NF-êB-induced signaling. These studies collectively demonstrate that classical and alternative NF-êB contribute to epithelial-derived inflammatory responses, and GSTP may be a novel target by which NF-êB can be regulated.

The NF-κB/Rel family of transcription factors and IκB inhibitors play a key role in regulation of gene expression in inflammation and immunity. Previous studies from our laboratory suggested that steady-state levels of p65 and other NF-κB components in the normal mouse aorta determine the magnitude of NF-κB target gene expression in response to pro-inflammatory stimuli, however, the mechanism(s) by which steady-state levels of NF-κB components are set is not clear. This study aims at elucidating the mechanisms behind NF-κB homeostasis and how that affects atherosclerosis susceptibility. In HeLa cells and HUVEC, siRNA silencing of p65 correlated with reduced steady-state expression of a subset of NF-κB/Rel and IκB genes at the transcriptional and post-transcriptional levels, respectively, in addition to reducing TNFα-induced NF-κB/Rel and IκB gene expression. This correlation was also observed in atherosclerosis-susceptible mouse aortic endothelium suggesting the role of p65 in modulating NF-κB homeostasis and affecting atherosclerosis susceptibility.

The NF-κB/Rel family of transcription factors and IκB inhibitors play a key role in regulation of gene expression in inflammation and immunity. Previous studies from our laboratory suggested that steady-state levels of p65 and other NF-κB components in the normal mouse aorta determine the magnitude of NF-κB target gene expression in response to pro-inflammatory stimuli, however, the mechanism(s) by which steady-state levels of NF-κB components are set is not clear. This study aims at elucidating the mechanisms behind NF-κB homeostasis and how that affects atherosclerosis susceptibility. In HeLa cells and HUVEC, siRNA silencing of p65 correlated with reduced steady-state expression of a subset of NF-κB/Rel and IκB genes at the transcriptional and post-transcriptional levels, respectively, in addition to reducing TNFα-induced NF-κB/Rel and IκB gene expression. This correlation was also observed in atherosclerosis-susceptible mouse aortic endothelium suggesting the role of p65 in modulating NF-κB homeostasis and affecting atherosclerosis susceptibility.

Many inflammatory diseases are growing increasing common in the aging society of Taiwan. Inflammation cascades can cause diseases such as rheumatoid arthritis, osteoarthritis, chronic asthma, multiple sclerosis, and so on. The clinically used anti-inflammatory drugs have many side effects and are expensive. Therefore, it is imperative that we find alternatives to these drugs. Marine natural compounds offer great hope in the development of drugs for treating inflammatory diseases. In the present study, we found that Chao-10, which is a marine-derived compound isolated from Formosan soft coral, significantly inhibited the expression of the pro-inflammatory protein, inducible nitric oxide synthase (iNOS), in the lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophage cell line. We suggest that Chao-10 may serve as a potential new anti-inflammatory agent. However, the mechanism by which the anti-inflammatory effects of Chao-10 are mediated is yet unclear. Therefore, we performed two-dimensional electrophoresis (2-DE) to investigate the regulatory mechanism for the anti-inflammatory effect of Chao-10. We isolated some proteins that may be involved in the anti-inflammatory mechanism of Chao-10. In addition, we used immunoprecipitation to find that nucleophosmin (NPM) could interact with nuclear factor kappa B (NF-£eB). Therefore, we hypothesize that nucleophosminmay be involved in the regulation of NF-£eB to enhance the down-regulation of iNOS proteins. In summary, the anti-inflammatory effects of Chao-10 are probably mediated through the some other signaling pathway. Importantly, Chao-10 not only offers some new biomarkers of inflammation but also provides an encouraging outlook on therapeutic approaches.

All animals have evolved mechanisms to recognise and eliminate nonself in order to defend against invading pathogens and to prevent chimerism, the fusion between genetically distinct conspecifics. Like other metazoans, sponges are known to rely on sophisticated systems to maintain their self-integrity. As poriferans are also considered one of the most ancient extant metazoan phyla, they represent a critical comparative model for understanding the early evolution of immunity and self/nonself recognition in animals. The Toll-like receptor (TLR) signalling cascade plays a crucial role in immunity, and recent findings in the sponge Suberites domuncula suggest that its origin could predate eumetazoan cladogenesis. My genome and expressed sequence tag (EST) screens of the demosponge Amphimedon queenslandica detected homologues to most components of this pathway, supporting the notion that a primordial TLR signalling cascade emerged at the dawn of the Metazoa. The sponge also encodes a couple of putative TLR-related proteins (AmqIgTIRs) that consist of at least one extracellular immunoglobulin (Ig) and an intracellular Toll/Interleukin-1 receptor/resistance (TIR) domain. The presence of other unconventional TLRs in S. domuncula and in cnidarian representatives, implies that an ancestral TLR probably existed in the last common ancestor of all living metazoans, and independent duplication and divergence events led to the variety of forms observed in animals. Among the putative transcription factors present in Amphimedon, which are known to be activated by the TLR signalling cascade in other eumetazoans, I detected a single member of the Rel/nuclear factor-kappaB (NF-κB) family, AmqNF-κB, which is also the only Rel homology domain (RHD)-containing gene present in the sponge. This gene encodes a protein that is equipped with both a RHD and ankyrin (ANK) repeats, suggesting that the ancestral metazoan NF-κB was configured identically to contemporary vertebrate and sponge forms, and that the truncated NF-κB found in Nematostella vectensis resulted from the secondary loss of ANK. Aside from immunity, the Toll and TLR pathways contribute to a variety of biological processes in bilaterians, however their functions have only been investigated in detail in a limited number of metazoan model organisms. While studies have tested the immune role of various sponge genes, including components of the TLR cascade, no research has yet established whether they are also involved in development. Therefore, I investigated the expression of some of the immunity-related genes I isolated in Amphimedon in a developmental and immune context to shed light on the potential ancestral function(s) of the proteins they encode. Using in situ hybridisation, I demonstrate that AmqIgTIR2, AmqMyD88, AmqTollip, AmqPellino and AmqNF-ĸB are expressed during A. queenslandica early development. In contrast, the spatial and temporal expression of AmqIgTIR1 suggests it might encode a receptor that is specifically involved in the detection of metamorphic cues in larvae. A real-time quantitative PCR (qPCR) study performed on a pool of adult sponge cDNAs indicates that the expression levels of AmqIgTIR1, AmqIgTIR2, AmqMyD88 and AmqTollip are significantly affected by a nine-hour incubation in 50 µg/ml of lipopolysaccharide (LPS), and to a lesser extent by 105 colony forming units (cfu)/ml of live Vibrio harveyi. The gene expression of AmqIgTIR1 and AmqIgTIR2 suggests that they may encode proteins with antagonistic immunological functions. While AmqPellino and AmqNF-ĸB do not appear to be affected by LPS and Vibrio exposure, it is possible that these genes do not participate in the early immune response of poriferans. Together, my data indicate that the sponge genes surveyed might encode proteins that perform developmental, sensory and immunological functions, suggesting their roles could have also been multifaceted in the last common ancestor to all living metazoans. As is observed in other invertebrates, poriferans display an ontogenic shift in allorecognition; genetically different individuals can fuse during early development but, in most instances, not as adults. However, there is a limited understanding of the cellular organisation of sponge chimeras and the onset of poriferan allorecognition response. By following the fates of fluorescently tagged cells derived from genetically distinct Amphimedon larvae that are fused together at metamorphosis, I establish that there is a rapid ontogenic shift in the sponge allogeneic response about two weeks after the initiation of metamorphosis. Moreover, the molecular basis of the poriferan allorecognition system is possibly involved in creating differential cell affinities, which underlie the construction of the sponge body plan. Compatible with this scenario is the observation that cells from postlarvae that are allowed to develop for two weeks before contact do not fuse, and form a distinct boundary between genotypes. The molecules responsible for sponge cell reaggregation, the aggregation factors (AFs), have been proposed to drive the allorecognition response in poriferans. Notably, the Amphimedon genome encodes six putative AFs, of which five occur in a cluster. These findings indicate that the polymorphic variation observed in other poriferan AFs is probably the result of allelic variations of multiple genes belonging to the same family.

Doxorubicin (Dox) is a major anticancer chemotherapeutic agent. However, it causes cardiomyopathy due to the side effect of cardiomyocyte apoptosis. We have previously reported that angiopoietin-1 significantly reduced myocardial infarction after ischemic injury and protected cardiomyocytes from oxidative stress-induced apoptosis. It is hypothesized that angiopoietin-1 may protect cardiomyocytes from Dox-induced apoptosis. Cardiomyocytes H9C2 were transfected with adenovirus expressing angiopoietin-1 (Ad5-Ang-1) 24 h before the cells were challenged with Dox at a concentration of 2 μmol/L. Ad5-GFP served as the vector control. Cardiomyocyte apoptosis was evaluated using Annexin V-FITC staining and caspase-3 and caspase-8 activity was determined by Western blotting. The results showed that Dox treatment significantly induced cardiomyocyte apoptosis as evidenced by the greater number of Annexin V-FITC stained cells and increases in caspase-3 and caspase-8 activity. In contrast, overexpression of angiopoietin-1 significantly prevented Dox-induced cardiomyocyte apoptosis. To elucidate the mechanisms by which angiopoietin-1 protected cells from Dox-induced apoptosis, we analyzed both extrinsic and intrinsic apoptotic signaling pathways. We observed that angiopoietin-1 prevented Dox-induced activation of both extrinsic and intrinsic apoptotic signaling pathways. Specifically, angiopoietin-1 prevented DOX-induced in-creases in FasL and Bax levels and cleaved caspase-3 and caspase-8 levels in H9C2 cells. In addition, overexpression of angiopoietin-1 also activated the pro-survival phosphoinositide-3 kinase (PI3K)/Akt signaling pathway and decreased Dox-induced nuclear factor-kappaB (NF-κB) activation. Our data suggest that promoting the expression of angiopoietin-1 could be a potential approach for reducing Dox-induced cardiomyocyte cytoxicity.

Objective: We have previously demonstrated that nuclear factor kappa B (NFκB) activation is needed for the development of cardiac hypertrophy in vivo. NFκB is a downstream transcription factor in the Toll-like receptor (TLR)-mediated signaling pathway; therefore, we investigated a role of TLR4 in cardiac hypertrophy in vivo. Methods: TLR4-deficient mice (C.C3H-Tlr4 lps-d, n = 6), wild-type (WT) genetic background mice (BALB/c, n = 6), TLR4-deleted strain (C57BL/10ScCr, n = 8), and WT controls (C57BL/10ScSn, n = 8) were subjected to aortic banding for 2 weeks. Age-matched surgically operated mice served as controls. In a separate experiment, rapamycin (2 mg/kg, daily) was administered to TLR4-deficient mice and WT mice immediately following aortic banding. The ratio of heart weight/body weight (HW / BW) was calculated, and cardiac myocyte size was examined by FITC-labeled wheat germ agglutinin staining of membranes. NFκB binding activity and the levels of phospho-p70S6K in the myocardium were also examined. Results: Aortic banding significantly increased the ratio of HW / BW by 33.9% (0.601 ± 0.026 vs. 0.449 ± 0.004) and cell size by 68.4% in WT mice and by 10.00% (0.543 ± 0.011 vs. 0.495 ± 0.005) and by 11.8% in TLR4-deficient mice, respectively, compared with respective sham controls. NFκB binding activity and phospho-p70S6K levels were increased by 182.6% and 115.2% in aortic-banded WT mice and by 78.0% and 162.0% in aortic-banded TLR4-deficient mice compared with respective sham controls. In rapamycin-treated aortic-banded mice, the ratio of HW / BW was increased by 18.0% in WT mice and by 3.5% in TLR4-deficient mice compared with respective sham controls. Conclusion: Our results demonstrate that TLR4 is a novel receptor contributing to the development of cardiac hypertrophy in vivo and that both the TLR4-mediated pathway and PI3K/Akt/mTOR signaling are involved in the development of cardiac hypertrophy in vivo.

We examined whether blocking the MyD88 mediated pathway could protect myocardium from ischemia/reperfusion (I/R) injury by transfecting Ad5-dnMyD88 into the myocardium of rats (n = 8) 3 days before the hearts were subjected to ischemia (45 min) and reperfusion (4 h). Ad5-GFP served as control (n = 8). One group of rats was (n = 8) subjected to I/R without transfection. Transfection of Ad5-dnMyD88 significantly reduced infarct size by 53.6% compared with the I/R group (15.1 ± 3.02 vs 32.5 ± 2.59) while transfection of Ad5-GFP did not affect I/R induced myocardial injury (35.4 ± 2.59 vs 32.5 ± 2.59). Transfection of Ad5-dnMyD88 significantly inhibited I/R-enhanced NFκB activity by 50% and increased the levels of phospho-Akt by 35.6% and BCL-2 by 81%, respectively. Cardiac myocyte apoptosis after I/R was significantly reduced by 59% in the Ad5-dnMyD88 group. The results demonstrate that both inhibition of the NFκB activation pathway and activation of the Akt signaling pathway may be responsible for the protective effect of transfection of dominant negative MyD88.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Human mast cells are often found perivascularly and at mucosal sites and may play crucial roles in the inflammatory response. Recent studies have suggested a prominent role for mast cells in host defense. In this study, we analyzed the effects of a common airway pathogen, Moraxella catarrhalis and a commensal bacterium, Neiserria cinerea, on activation of human mast cells. Human mast cell leukemia cells (HMC-1) were activated with either phorbol myristate acetate (PMA) and calcium ionophore or with varying concentrations of heat-killed suspensions of bacteria. Supernatants were assayed for the cytokines interleukin-4 (IL-4), granulocyte macrophage colony stimulating factor (GM-CSF), IL-6, IL-8, IL-13 and monocyte chemotactic protein-1 (MCP-1). Nuclear proteins were isolated and assayed by electrophoretic mobility shift assay (EMSA) for nuclear factor kappaB (NF-κB) nuclear binding activity. In some experiments, NF-κB inhibitor, Bay-11 was added to determine functional significance. Both M. catarrhalis and N. cinerea induced mast cell activation and selective secretion of two key inflammatory cytokines, IL-6 and MCP-1. This was accompanied by NF-κB activation. Neither spun bacterial supernatants nor bacterial lipopolysaccharide induced cytokine secretion, suggesting need for direct bacterial contact with mast cells. Scanning electron microscopy revealed active aggregation of bacteria over mast cell surfaces. The NF-κB inhibitor, Bay-11, inhibited expression of MCP-1. These findings suggest the possibility of direct interactions between human mast cells and common bacteria and provide evidence for a novel role for human mast cells in innate immunity.