Lipopolysaccharide and TNF-alpha produce very similar changes in gene expression in human endothelial cells

TNF Induces Laminin-332-Encoding Genes in Endothelial Cells and Laminin-332 Promotes an Atherogenic Endothelial Phenotype

Laminins are essential components of the basement membranes, expressed in a tissue- and cell-specific manner under physiological conditions. During inflammatory circumstances, such as atherosclerosis, alterations in laminin composition within vessels have been observed. Our study aimed to assess the influence of tumor necrosis factor-alpha (TNF), a proinflammatory cytokine abundantly found in atherosclerotic lesions, on endothelial laminin gene expression and the effects of laminin-332 (LN332) on endothelial cells' behavior. We also evaluated the expression of LN332-encoding genes in human carotid atherosclerotic plaques. Our findings demonstrate that TNF induces upregulation of LAMB3 and LAMC2, which, along with LAMA3, encode the LN332 isoform. Endothelial cells cultured on recombinant LN332 exhibit decreased claudin-5 expression and display a loosely connected phenotype, with an elevated expression of chemokines and leukocyte adhesion molecules, enhancing their attractiveness and adhesion to leukocytes in vitro. Furthermore, LAMB3 and LAMC2 are upregulated in human carotid plaques and show a positive correlation with TNF expression. In summary, TNF stimulates the expression of LN332-encoding genes in human endothelial cells and LN332 promotes an endothelial phenotype characterized by compromised junctional integrity and increased leukocyte interaction. These findings highlight the importance of basement membrane proteins for endothelial integrity and the potential role of LN332 in atherosclerosis.

Multi-Layered Human Blood Vessels-on-Chip Design Using Double Viscous Finger Patterning

Blood vessel-on-a-chip models aim at reproducing vascular functions. However, very few efficient methods have been designed to address the need for biological replicates in medium- to high-throughput screenings. Here, vessels-on-chip were designed in polydimethylsiloxane-glass chips using the viscous finger patterning technique which was adapted to create channels with various internal diameters inside a collagen solution and to simultaneously seed cells. This method was refined to create blood vessels composed of two concentric, distinct, and closely appositioned layers of human endothelial and perivascular cells arranged around a hollow lumen. These approaches allowed the formation of structurally correct blood vessels-on-chips which were constituted of either only endothelial cells or of both cell types in order to distinguish the vascular barrier reactivity to drugs in the presence or not of perivascular cells. The established vessels showed a tight vascular barrier, as assessed by immunostaining of the adherens junctions, and were reactive to the natural vasopermeant thrombin and to inflammatory cytokines. The presence of perivascular cells markedly increased the tightness of the vascular barrier and lowered its response to thrombin. The design allowed us to simultaneously challenge in real-time several tens of 3D-reconstituted, multicellular blood vessels in a standard multiwell plate format suitable for high-throughput drug screening.

Menaquinone-4 Suppresses Lipopolysaccharide-Induced Inflammation in MG6 Mouse Microglia-Derived Cells by Inhibiting the NF-κB Signaling Pathway

The overactivation of microglia is known to trigger inflammatory reactions in the central nervous system, which ultimately induce neuroinflammatory disorders including Alzheimer's disease. However, increasing evidence has shown that menaquinone-4 (MK-4), a subtype of vitamin K2, can attenuate inflammation in the peripheral system. Whereas it was also observed at high levels within the brain, its function in this organ has not been well characterized. Therefore, we investigated the effect of MK-4 on microglial activation and clarified the underlying mechanism. Mouse microglia-derived MG6 cells were exposed to lipopolysaccharide (LPS) either with or without MK-4 pretreatment. Cell responses with respect to inflammatory cytokines (Il-1β, Tnf-α, and Il-6) were measured by qRT-PCR. We further analyzed the phosphorylation of TAK1, IKKα/β, and p65 of the NF-κB subunit by Western blotting. We observed that in LPS-induced MG6 cells, MK-4 dose-dependently suppressed the upregulation of inflammatory cytokines at the mRNA level. It also significantly decreased the phosphorylation of p65, but did not affect that TAK1 and IKKα/β. Furthermore, the nuclear translocation of NF-κB in LPS-induced MG6 cells was inhibited by MK-4. These results indicate that MK-4 attenuates microglial inflammation by inhibiting NF-κB signaling.

Quinic Acid-Conjugated Nanoparticles Enhance Drug Delivery to Solid Tumors via Interactions with Endothelial Selectins

Current nanoparticle (NP) drug carriers mostly depend on the enhanced permeability and retention (EPR) effect for selective drug delivery to solid tumors. However, in the absence of a persistent EPR effect, the peritumoral endothelium can function as an access barrier to tumors and negatively affect the effectiveness of NPs. In recognition of the peritumoral endothelium as a potential barrier in drug delivery to tumors, poly(lactic-co-glycolic acid) (PLGA) NPs are modified with a quinic acid (QA) derivative, synthetic mimic of selectin ligands. QA-decorated NPs (QA-NP) interact with human umbilical vein endothelial cells expressing E-/P-selectins and induce transient increase in endothelial permeability to translocate across the layer. QA-NP reach selectin-upregulated tumors, achieving greater tumor accumulation and paclitaxel (PTX) delivery than polyethylene glycol-decorated NPs (PEG-NP). PTX-loaded QA-NP show greater anticancer efficacy than Taxol or PTX-loaded PEG-NP at the equivalent PTX dose in different animal models and dosing regimens. Repeated dosing of PTX-loaded QA-NP for two weeks results in complete tumor remission in 40-60% of MDA-MB-231 tumor-bearing mice, while those receiving control treatments succumb to death. QA-NP can exploit the interaction with selectin-expressing peritumoral endothelium and deliver anticancer drugs to tumors to a greater extent than the level currently possible with the EPR effect.

PET Imaging in Psychoneuroimmunology Research

Positron-emission tomography (PET) imaging is a valuable research tool that enables in vivo quantification of molecular targets in the brain or of a physiologic process. PET imaging can be combined with various experimental and clinical model systems that are commonly used in psychoneuroimmunology research. As PET imaging can be used in animals and humans, promising results can therefore often be translated from an animal model to human disease.

Brugia malayi microfilariae adhere to human vascular endothelial cells in a C3-dependent manner

Brugia malayi causes the human tropical disease, lymphatic filariasis. Microfilariae (Mf) of this nematode live in the bloodstream and are ingested by a feeding mosquito vector. Interestingly, in a remarkable co-evolutionary adaptation, Mf appearance in the peripheral blood follows a circadian periodicity and reaches a peak when the mosquito is most likely to feed. For the remaining hours, the majority of Mf sequester in the lung capillaries. This circadian phenomenon has been widely reported and is likely to maximise parasite fitness and optimise transmission potential. However, the mechanism of Mf sequestration in the lungs remains largely unresolved. In this study, we demonstrate that B. malayi Mf can, directly adhere to vascular endothelial cells under static conditions and under flow conditions, they can bind at high (but not low) flow rates. High flow rates are more likely to be experienced diurnally. Furthermore, a non-periodic nematode adheres less efficiently to endothelial cells. Strikingly C3, the central component of complement, plays a crucial role in the adherence interaction. These novel results show that microfilariae have the ability to bind to endothelial cells, which may explain their sequestration in the lungs, and this binding is increased in the presence of inflammatory mediators.

Pyrrolidine Dithiocarbamate Inhibits Nuclear Factor κB and Toll-Like Receptor 4 Expression in Rats with Acute Necrotizing Pancreatitis

Background/Aims

To investigate the expression of Toll-like receptor 4 (TLR4) in the pancreases of rats with acute necrotizing pancreatitis (ANP) and any changes upon treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor κB (NF-κB), as well as to determine the relationship between TLR4 and NF-κB in ANP pathogenesis.

Methods

A total of 72 SD rats were randomly divided into three groups, namely, the control (sham-operation), ANP, and ANP with PDTC pretreatment groups. The PDTC-pretreated group was intraperitoneally injected with PDTC at a dose of 100 mg/kg 1 hour before the induction of ANP. The expressions of TLR4 and NF-κB in pancreatic tissue were evaluated by immunohistochemistry and Western blot analysis. The mRNA levels of cytokines tumor necrosis factor α, interleukin (IL)-1β, and IL-6 were measured by reverse transcription polymerase chain reaction.

Results

The expressions of TLR4, NF-κB, and cytokine (NF-κB target) genes in the pancreatic tissue increased more significantly in the ANP groups than in the sham-operation group at 3, 6, and 12 hours. Pretreatment with PDTC alleviated the inflammatory activation in the pancreas with ANP, causing a significant decrease in the expressions of TLR4, NF-κB, and cytokine genes in the pancreatic tissue.

Conclusions

The expressions of TLR4 and NF-κB were increased in the pancreases of rats with ANP. PDTC not only inhibits NF-κB but also suppresses the expression of TLR4 and downregulates the expression of the related cytokine genes.

TNFAIP2 Inhibits Early TNFα-Induced NF-x03BA;B Signaling and Decreases Survival in Septic Shock Patients

During septic shock, tumor necrosis factor alpha (TNFα) is an early response gene and induces a plethora of genes and signaling pathways. To identify robust signals in genes reliably upregulated by TNFα, we first measured microarray gene expression in vitro and searched methodologically comparable, publicly available data sets to identify concordant signals. Using tag single-nucleotide polymorphisms in the genes common to all data sets, we identified a genetic variant of the TNFAIP2 gene, rs8126, associated with decreased 28-day survival and increased organ dysfunction in an adult cohort in the Vasopressin and Septic Shock Trial. Similar to this cohort, we found that an association with rs8126 and increased organ dysfunction is replicated in a second cohort of septic shock patients in the St. Paul's Hospital Intensive Care Unit. We found that TNFAIP2 inhibits NF-x03BA;B activity, impacting the downstream cytokine interleukin (IL)-8. The minor G allele of TNFAIP2 rs8126 resulted in greater TNFAIP2 expression, decreased IL-8 production and was associated with decreased survival in patients experiencing septic shock. These data suggest that TNFAIP2 is a novel inhibitor of NF-x03BA;B that acts as an autoinhibitor of the TNFα response during septic shock.

Lipopolysaccharide-induced lung injury involves the nitration-mediated activation of RhoA

Acute lung injury (ALI) is characterized by increased endothelial hyperpermeability. Protein nitration is involved in the endothelial barrier dysfunction in LPS-exposed mice. However, the nitrated proteins involved in this process have not been identified. The activation of the small GTPase RhoA is a critical event in the barrier disruption associated with LPS. Thus, in this study we evaluated the possible role of RhoA nitration in this process. Mass spectroscopy identified a single nitration site, located at Tyr(34) in RhoA. Tyr(34) is located within the switch I region adjacent to the nucleotide-binding site. Utilizing this structure, we developed a peptide designated NipR1 (nitration inhibitory peptide for RhoA 1) to shield Tyr(34) against nitration. TAT-fused NipR1 attenuated RhoA nitration and barrier disruption in LPS-challenged human lung microvascular endothelial cells. Further, treatment of mice with NipR1 attenuated vessel leakage and inflammatory cell infiltration and preserved lung function in a mouse model of ALI. Molecular dynamics simulations suggested that the mechanism by which Tyr(34) nitration stimulates RhoA activity was through a decrease in GDP binding to the protein caused by a conformational change within a region of Switch I, mimicking the conformational shift observed when RhoA is bound to a guanine nucleotide exchange factor. Stopped flow kinetic analysis was used to confirm this prediction. Thus, we have identified a new mechanism of nitration-mediated RhoA activation involved in LPS-mediated endothelial barrier dysfunction and show the potential utility of "shielding" peptides to prevent RhoA nitration in the management of ALI.

Reverse causal reasoning: applying qualitative causal knowledge to the interpretation of high-throughput data

Background

Gene expression profiling and other genome-scale measurement technologies provide comprehensive information about molecular changes resulting from a chemical or genetic perturbation, or disease state. A critical challenge is the development of methods to interpret these large-scale data sets to identify specific biological mechanisms that can provide experimentally verifiable hypotheses and lead to the understanding of disease and drug action.

Results

We present a detailed description of Reverse Causal Reasoning (RCR), a reverse engineering methodology to infer mechanistic hypotheses from molecular profiling data. This methodology requires prior knowledge in the form of small networks that causally link a key upstream controller node representing a biological mechanism to downstream measurable quantities. These small directed networks are generated from a knowledge base of literature-curated qualitative biological cause-and-effect relationships expressed as a network. The small mechanism networks are evaluated as hypotheses to explain observed differential measurements. We provide a simple implementation of this methodology, Whistle, specifically geared towards the analysis of gene expression data and using prior knowledge expressed in Biological Expression Language (BEL). We present the Whistle analyses for three transcriptomic data sets using a publically available knowledge base. The mechanisms inferred by Whistle are consistent with the expected biology for each data set.

Conclusions

Reverse Causal Reasoning yields mechanistic insights to the interpretation of gene expression profiling data that are distinct from and complementary to the results of analyses using ontology or pathway gene sets. This reverse engineering algorithm provides an evidence-driven approach to the development of models of disease, drug action, and drug toxicity.

Relationship between nerve injury-induced protein gene 2 polymorphism and stroke in Chinese Han population

The aim of present study was to investigate the relationship between nerve injury-induced protein 2 (NINJ2) gene polymorphism and stroke in Chinese Han population. Fifty-two patients with large-artery atherosclerosis (LAA) infarction, 85 patients with small-artery occlusion lacunar (SAO) infarction, 50 patients with intracerebral hemorrhage (ICH) and 66 controls were included. Genotypes and alleles frequencies of the two single nucleotide polymorphisms (SNPs) of NINJ2 among different groups were analyzed and compared. In regard to rs12425791, the frequencies of the AG and AA+AG genotypes of the LAA and SAO groups were significantly higher than those in the control group; the frequency of the A allele of the SAO group was significantly higher than that of the control group. In regard to rs11833579, there were not any significant differences between the case and the control groups. The SNP rs12425791 is significantly associated with ischemic stroke, and the A allele increases the susceptibility to stroke. The SNP rs11833579 is not significantly associated with stroke.

E-selectin mediated adhesion and migration of endothelial colony forming cells is enhanced by SDF-1α/CXCR4

Objective

Endothelial-colony forming cells (ECFCs) can be readily expanded from human umbilical cord blood and can facilitate repair of endothelial injury. E-selectin and SDF-1α are produced following endothelial injury and can regulate endothelial progenitor homing. Mechanisms of vascular repair specific to the mode of injury have not been well described in homogenous cell populations such as ECFCs and are needed for development of more effective vascular repair strategies.

Methods and Results

Lipopolysaccharide (LPS)-induced endotoxic injury to mature human umbilical vein endothelial cells (HUVEC) was compared with hypoxic and radiation injury. E-selectin expression in HUVEC cells is markedly increased (208-fold) following LPS-induced injury and facilitates increased ECFC adhesion and migration function in vitro. SDF-1α expression remains unchanged in LPS-treated HUVEC cells but increases more than 2 fold in fibroblasts undergoing similar endotoxic injury. SDF-1α induces expression of E-selectin ligands on ECFCs and facilitates greater E-selectin-mediated adhesion and migration of ECFCs in a CXCR4-dependent manner. Induction of E-selectin expression in HUVECs following hypoxic or radiation injury is negligible, however, while SDF-1α is increased markedly following hypoxia, highlighting injury-specific synergism between mediators of vascular repair.

Conclusion

E-selectin mediates adhesion and migration of ECFCs following endotoxic endothelial injury. SDF-1α augments E-selectin mediated ECFC adhesion and migration in a CXCR4-dependent manner.

The application of PET imaging in psychoneuroimmunology research

Positron emission tomography (PET) imaging is a research tool that allows in vivo measurements of brain metabolism and specific target molecules. PET imaging can be used to measure these brain variables in a variety of species, including human and non-human primates, and rodents. PET imaging can therefore be combined with various experimental and clinical model systems that are commonly used in psychoneuroimmunology research.

Live Brugia malayi microfilariae inhibit transendothelial migration of neutrophils and monocytes

Lymphatic filariasis is a major tropical disease caused by the parasite Brugia malayi. Microfilariae (Mf) circulate in the peripheral blood for 2-3 hours in synchronisation with maximal feeding of the mosquito vector. When absent from the peripheral blood, Mf sequester in the capillaries of the lungs. Mf are therefore in close contact with vascular endothelial cells (EC) and may induce EC immune function and/or wound repair mechanisms such as angiogenesis. In this study, Mf were co-cultured with human umbilical vein EC (HUVEC) or human lung microvascular EC (HLMVEC) and the transendothelial migration of leukocyte subsets was analysed. In addition, the protein and/or mRNA expression of chemokine, cytokine and angiogenic mediators in endothelial cells in the presence of live microfilariae were measured by a combination of cDNA arrays, protein arrays, ELISA and fluorescence antibody tests.Surprisingly, our findings indicate that Mf presence partially blocked transendothelial migration of monocytes and neutrophils, but not lymphocytes. However, Mf exposure did not result in altered vascular EC expression of key mediators of the tethering stage of extravasation, such as ICAM-1, VCAM-1 and various chemokines. To further analyse the immunological function of vascular EC in the presence of Mf, we measured the mRNA and/or protein expression of a number of pro-inflammatory mediators. We found that expression levels of the mediators tested were predominantly unaltered upon B. malayi Mf exposure. In addition, a comparison of angiogenic mediators induced by intact Mf and Wolbachia-depleted Mf revealed that even intact Mf induce the expression of remarkably few angiogenic mediators in vascular EC. Our study suggests that live microfilariae are remarkably inert in their induction and/or activation of vascular cells in their immediate local environment. Overall, this work presents important insights into the immunological function of the vascular endothelium during an infection with B. malayi.

NADPH oxidase-derived superoxide destabilizes lipopolysaccharide-induced interleukin 8 mRNA via p38, extracellular signal-regulated kinase mitogen-activated protein kinase, and the destabilizing factor tristetraprolin

Expression of inflammatory cytokines is regulated by transcriptional and posttranscriptional mechanisms. We previously showed that NADPH oxidase-derived superoxide induces inflammatory mediators in response to tumor necrosis factor α (TNF-α) and lipopolysaccharide (LPS). In this study, we examined the role of endothelial NADPH oxidase in the regulation of mRNA stability of three inflammatory mediators: interleukin (IL) 8, IL-6, and intercellular adhesion molecule 1 (ICAM-1). Tumor necrosis factor α increased mRNA stability of ICAM-1, IL-8, and IL-6 by a p38 mitogen-activated protein kinase (MAPK)-dependent mechanism, but this did not involve NADPH oxidase. Surprisingly, whereas LPS treatment alone did not alter stability of these molecules, the antioxidant N-acetyl-L-cysteine; the flavine inhibitor diphenylene iodonium; short interfering RNA against Nox2, Nox4; and the p22(phox) subunit of NADPH oxidase all enhanced IL-8 mRNA stability in LPS-treated cells, indicating that LPS induced destabilization through NADPH oxidase. This occurred by a mechanism that involved extracellular signal-regulated kinase 1/2, p38 MAPK, and the mRNA-destabilizing factor tristetraprolin. On the other hand, N-acetyl-L-cysteine decreased mRNA stability of ICAM-1 and IL-6 in LPS-treated cells and IL-6 and ICAM-1 in TNF-α-treated cells. In conclusion, NADPH oxidase contributes to destabilization of IL-8 mRNA stability and propose a model for the complex underlying mechanism, which is dependent upon agonist (LPS vs. TNF-α) and target molecule (IL-8 vs. IL-6 and ICAM-1) and involves tristetraprolin, p38, and extracellular signal-regulated kinase 1/2 MAPK.

TNFα affects energy metabolism and stimulates biogenesis of mitochondria in EA.hy926 endothelial cells

Mitochondrial response of EA.hy926 endothelial cells to tumour necrosis factor alpha (TNFα) was investigated. It was confirmed that TNFα stimulates reactive oxygen species (ROS) generation and increases intercellular adhesion molecule-1 (ICAM-1) level. These changes were paralleled by elevated oxygen consumption, slightly raised total mitochondrial mass and increased manganese superoxide dismutase (Mn-SOD) and uncoupling protein 2 (UCP2) content. They also correlated with a rise of mitochondrial transcription factor 1 (TFAM), nuclear respiratory factor-1 (NRF-1) and peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α, which are involved in regulation of mitochondrial biogenesis and an elevated level of selected respiratory chain proteins. Thus, the apparent stimulatory effect of TNFα on mitochondrial metabolism probably reflects an increased amount of mitochondria rather than activation of biochemical processes per se, although the latter cannot be excluded definitely. These observations are similar to those described for cardiac muscle cells challenged with bacterial lipopolysaccharide (LPS), in which mitochondrial biogenesis was postulated. Stimulation of mitochondrial biogenesis could be a mechanism activated to prevent TNFα-induced cell death.

Lipopolysaccharide appears to activate human endometrial endothelial cells through TLR-4-dependent and TLR-4-independent mechanisms

PROBLEM

Uterine innate immunity remains poorly characterized, and while endometrial endothelial cells are known to express Toll-like receptors (TLRs), little is known about their function in these cells. The present study evaluated the effect of Gram-negative bacterial lipopolysaccharide (LPS) on human endometrial endothelial cell (HEECs) cytokine secretion and tissue factor expression, and the role of TLR-4 in these responses.

METHODS

Human endometrial endothelial cells were treated with or without LPS ± LPS-RS, a TLR-4 antagonist, via the binding of MD-2. After 24 hr, cell-free supernatants were evaluated for cytokines by multiplex analysis and cell lysates were analyzed for tissue factor expression by Western blot.

RESULTS

Treatment of HEECs with LPS significantly upregulated the secretion of IL-6, IL-8, and G-CSF, and this was prevented by LPS-RS. LPS also induced tissue factor expression by the HEECs; however, this was unaffected by LPS-RS.

CONCLUSION

These findings suggest that TLR-4 is functional in HEECs and its activation by bacterial LPS induces a specific cytokine/chemokine response. However, bacterial LPS also induced tissue factor expression in what seemed to be a TLR-4-independent fashion, suggesting that this bacterial component can act on the HEECs through TLR-4-dependent and TLR-4-independent pathways. These findings indicate that endometrial endothelial cells may play an active role in uterine innate immunity.

Ankaflavin and monascin regulate endothelial adhesion molecules and endothelial NO synthase (eNOS) expression induced by tumor necrosis factor-α (TNF-α) in human umbilical vein endothelial cells (HUVECs)

Previous studies have established that red mold rice can regulate blood pressure in spontaneously hypertensive rats (SHR) and that Monascus -fermented products, including monacolin K, ankaflavin (AF), and monascin (MS), can inhibit expression of adhesion factors such as E-selectin and endothelin-1 to prevent human acute monocytic leukemia cell line THP-1 monocytes from adhering to human aortic endothelial cells. However, it remains unknown whether AF and MS act directly on human umbilical endothelial cells (HUVECs) to enhance nitric oxide (NO) synthesis through the stimulation of endothelial NO synthase (eNOS) expression. To address this knowledge gap, this study investigated whether AF and MS directly regulate NO synthesis and attenuate adhesion factor expression induced by treatment with tumor necrosis factor-α (TNF-α) in HUVECs. The results revealed that both AF and MS (20 μM) treatments promoted increases in eNOS expression and decreases in vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and endothelin-1 mRNA and protein expression resulting from 12 h of TNF-α treatment. These effects are attributed to the ability of AF and MS to inhibit extracellular signal-regulated protein kinase (ERK) phosphorylation and nuclear factor κB (NF-κB) translocation from the cytoplasm into the nucleus, thereby exerting antihypertensive activity.

Cell signals influencing hepatic fibrosis

Liver fibrosis is the result of the entire organism responding to a chronic injury. Every cell type in the liver contributes to the fibrosis. This paper first discusses key intracellular signaling pathways that are induced during liver fibrosis. The paper then examines the effects of these signaling pathways on the major cell types in the liver. This will provide insights into the molecular pathophysiology of liver fibrosis and should identify therapeutic targets.

Heterotrimeric Gi/Go proteins modulate endothelial TLR signaling independent of the MyD88-dependent pathway

The innate immune recognition of bacterial lipopolysaccharide (LPS) is mediated by Toll-like receptor 4 (TLR4) and results in activation of proinflammatory signaling including NF-κB and MAPK pathways. Heterotrimeric G proteins have been previously implicated in LPS signaling in macrophages and monocytes. In the present study, we show that pertussis toxin sensitive heterotrimeric G proteins (Gα(i/o)) are involved in the activation of MAPK and Akt downstream of TLR2, TLR3, and TLR4 in endothelial cells. Gα(i/o) are also required for full activation of interferon signaling downstream of TLR3 and TLR4 but are not required for the activation of NF-κB. We find that Gα(i/o)-mediated activation of the MAPK is independent of the canonical MyD88, interleukin-1 receptor-associated kinase, and tumor necrosis factor receptor-associated factor 6 signaling cascade in LPS-stimulated cells. Taken together, the data presented here suggest that heterotrimeric G proteins are widely involved in TLR pathways along a signaling cascade that is distinct from MyD88-TRAF6.

Mast cell modulation of the vascular and lymphatic endothelium

Mast cells (MCs) promote a wide range of localized and systemic inflammatory responses. Their involvement in immediate as well as chronic inflammatory reactions at both local and distal sites points to an extraordinarily powerful immunoregulatory capacity with spatial and temporal versatility. MCs are preferentially found in close proximity to both vascular and lymphatic vessels. On activation, they undergo a biphasic secretory response involving the rapid release of prestored vasoactive mediators followed by de novo synthesized products. Many actions of MCs are related to their capacity to regulate vascular flow and permeability and to the recruitment of various inflammatory cells from the vasculature into inflammatory sites. These mediators often work in an additive fashion and achieve their inflammatory effects locally by directly acting on the vascular and lymphatic endothelia, but they also can affect distal sites. Along these lines, the lymphatic and endothelial vasculatures of the host act as a conduit for the dissemination of MC signals during inflammation. The central role of the MC-endothelial cell axis to immune homeostasis is emphasized by the fact that some of the most effective current treatments for inflammatory disorders are directed at interfering with this interaction.

Inflammation-induced up-regulation of TLR2 expression in human endothelial cells is independent of differential methylation in the TLR2 promoter CpG island

Toll-like receptors play an important role in endothelial inflammation; however, little is known on the mechanisms regulating their expression. Differential promoter DNA methylation is an increasingly recognized mechanism that determines a switch between gene silencing and gene transcription. We hypothesized that epigenetic mechanisms are involved in the regulation of endothelial TLR2 expression because of the localization of the TLR2 promoter on a CpG-island. Resting human umbilical vein endothelial cells (HUVECs) displayed rather low TLR2 mRNA expression, while a strong expression increase occurred under inflammatory conditions. We examined the TLR2 promoter methylation pattern in resting HUVECs and compared it to cells treated either with the inflammatory cytokine TNF-α or the DNA-demethylating agent 5-azacytidine. DNA bisulfite conversion was followed by either genomic sequencing or single nucleotide primer extension (SNuPE) HPLC. Results of both techniques showed a low- or non-methylated TLR2 promoter in resting HUVECs and no alteration of the methylation pattern under inflammatory conditions. Whereas 5-azacytidine significantly increased the mRNA expression of the epigenetically regulated gene H19, TLR2 expression was not affected. Taken together, employing different methodological approaches, our data show no implication of methylation pattern changes in inflammatory induction of TLR2 expression in human endothelial cells.

Compound C independent of AMPK inhibits ICAM-1 and VCAM-1 expression in inflammatory stimulants-activated endothelial cells in vitro and in vivo

Activation of the NF-κB and mitogen activated protein (MAP) kinases plays an important role in the expression of inflammatory genes such as adhesion molecules. Although compound C is known as an AMPK inhibitor, AMPK-independent action of it has been recognized. Effects on the expression of ICAM-1 and VCAM-1 by compound C were investigated in TNF-α-activated human umbilical vein endothelial cells (HUVECs) in vitro and in thoracic aorta of rats treated with lipopolysaccharide (LPS) in vivo. Compound C inhibited ICAM-1 and VCAM-1 expression at the transcriptional as well as translational level in TNF-α-activated HUVECs. In both DN-AMPK- and AMPKα(1)-siRNA-transfected HUVECs, compound C still inhibited TNF-α-induced VCAM-1 and ICAM-1 expression, indicating that this is AMPK-independent action. Interestingly, compound C significantly inhibited NF-κB activity and translocation of p65 to nucleus in HUVECs when activated with TNF-α. Importantly, administration of compound C (0.2 mg/kg) significantly reduced expression of both ICAM-1 and VCAM-1 in LPS-treated rat thoracic aortas. In addition, compound C significantly inhibited iNOS and production of NO in both TNF-α- and LPS-activated RAW 264.7 cells. Finally, compound C significantly inhibited phosphorylation of Akt and p-38MAPK but not protein kinase c or ERK1/2 in HUVECs. Taken together, we conclude that adhesion molecules (ICAM-1, VCAM-1) are to be the novel targets of compound C in preventing inflammatory insult to endothelial cells independent of AMPK inhibition via inhibition of NF-κB activity along with inhibition of phosphorylation of PI3K and P38 MAPK.

Expression of Toll-like receptor 4 on peripheral blood mononuclear cells and its effects on patients with acute myocardial infarction treated with thrombolysis

BACKGROUND AND AIMS

TLR4 has been shown to mediate inflammation in animal models of myocardial ischemia/reperfusion injury (MI/RI). Here we hypothesized that TLR4 on peripheral blood mononuclear cells (PBMCs) may be involved in the inflammatory response in this type of clinical event.

METHODS

Seventy two patients with acute myocardial infarction (AMI) who underwent thrombolysis were assigned into reperfusion group (n = 43) and non-reperfusion group (n = 29) according to recanalization of infarct-related artery (IRA) and 40 healthy volunteers were enrolled in this experiment. Eight mL of venous blood was taken from all patients 0 h before and 2, 6, 12, and 24 h after thrombolysis. Flow cytometry (FCM) was used to detect TLR4 protein expression and real-time quantitative RT-PCR was performed to determine TLR4 mRNA and myeloid differentiation protein-88 (Myd88) mRNA expression. The concentration of tumor necrosis factor-α (TNF-α) in plasma was evaluated using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with controls, all detected indicators in AMI patients were upregulated before thrombolysis (p <0.01). After thrombolysis, they were further increased. In reperfusion group, all attained their peaks in earlier hours and the peak values were lower compared with non-reperfusion group. In both cases, either reperfusion or non-perfusion, TLR4 mRNA expression was positively correlated with the levels of Myd88 mRNA (r = 0.886 and 0.694, p <0.01), respectively.

CONCLUSIONS

TLR4 expression on PBMCs was markedly elevated in AMI patients either reperfused or non-reperfused. Inflammatory reaction by activated TLR4 in MI/RI in patients may be through TLR4-Myd88-dependent signal pathway.

Ectopic expression of eIF2Bepsilon in rat skeletal muscle rescues the sepsis-induced reduction in guanine nucleotide exchange activity and protein synthesis

Eukaryotic initiation factor 2B (eIF2B) is a guanine nucleotide exchange factor (GEF) whose activity is both tightly regulated and rate-controlling with regard to global rates of protein synthesis. Skeletal muscle eIF2B activity and expression of its catalytic epsilon-subunit (eIF2Bepsilon) have been implicated as potential contributors to the altered rates of protein synthesis in a number of physiological conditions and experimental models. The objective of this study was to directly examine the effects of exogenously expressed eIF2Bepsilon in vivo on GEF activity and protein synthetic rates in rat skeletal muscle. A plasmid encoding FLAG-eIF2Bepsilon was transfected into the tibialis anterior (TA) of one leg, while the contralateral TA received a control plasmid. Ectopic expression of eIF2Bepsilon resulted in increased GEF activity in TA homogenates of healthy rats, demonstrating that the expressed protein was catalytically active. In an effort to restore a deficit in eIF2B activity, we utilized an established model of chronic sepsis in which skeletal muscle eIF2B activity is known to be impaired. Ectopic expression of eIF2Bepsilon in the TA rescued the sepsis-induced deficit in GEF activity and muscle protein synthesis. The results demonstrate that modulation of eIF2Bepsilon expression may be sufficient to correct deficits in skeletal muscle protein synthesis associated with sepsis and other muscle-wasting conditions.

Neuregulin-1, the fetal endothelium, and brain damage in preterm newborns

OBJECTIVE

To assess the potential role for Neuregulin-1 (NRG1) as a systemic endogenous protector in the setting of perinatal inflammatory brain damage.

METHODS

We measured NRG1-protein and mRNA levels in human umbilical venous endothelial cells (HUVECs) of different gestational ages at various durations of exposure to lipopolysaccharide (LPS). In parallel, we genotyped the donor individuals for SNP8NRG221533, a disease-related single nucleotide polymorphism in the 5' region upstream of the NRG1 sequence. Intracellular NRG1 localization was visualized by confocal microscopy. Furthermore we analyzed the relationship between SNP8NRG221533 genotype and neurodevelopmental outcome in children born preterm.

RESULTS

We observed a positive dose-response-relationship between NRG1-mRNA and intracellular protein levels with both advancing gestational age and duration of LPS exposure in HUVECs. The presence of allele C at the SNP8NRG221533 locus was associated with an increased cellular production of NRG1 in HUVECs, and with a significantly reduced risk for cerebral palsy and developmental delay in children born preterm.

INTERPRETATION

In conclusion, our data indicate that gestational age, duration of LPS exposure, and the SNP8NRG221533 genotype affect NRG1 levels. Our results support the hypothesis that NRG1 may qualify as an endogenous protector during fetal development.

Porcine aortic endothelial cell genes responsive to selected inflammatory stimulators

Use of porcine tissues has been suggested as a promising solution for severe shortage of transplantable human organs. The immediate hurdle for xenotransplantation is acute immune/inflammatory vascular rejection of the transplant. Because endothelial cells play a key role in the initiation and the amplification of inflammation, alteration of gene expression in human endothelial cells, by various inflammatory stimulators has been studied extensively. However, transcriptional changes induced by human and other inflammatory stimulators in porcine endothelial cells have thus far not been studied. In this study, we treated porcine endothelial cells with human tumor necrosis factor (TNF)-alpha, porcine interferon (IFN)-gamma, H(2)O(2) and lypopolysaccharide (LPS) and profiled transcriptional change at 1 hr, 6 hr and 24 hr, using pig oligonucleotide 13K microarray. We found that mRNA species such as chemokine (C-X-C motif) ligand 6 (CXCL6) and Cathepsin S were significantly induced in porcine endothelial cells, as was previously reported with human endothelial cell. We also found that mRNA species including secreted frizzled-related protein 2 (SFRP2), radical S-adenosyl methionine domain containing 2 (RSAD2), structure specific recognition protein 1 (SSRP1) also were highly overexpressed in porcine endothelial cells. This result shows clues to understand underlying mechanisms of xenotransplantation rejection and the highly responsive porcine genes may serve as novel targets to be regulated for improving the function of grafted porcine donor organs.

Monitoring of endothelial cell activation in experimental sepsis with a two-step cell culture model

The aim of this work was to establish and characterize a cell culture model for lipopolysaccharide (LPS)-induced activation of human endothelial cells. Monocytic THP-1 cells were stimulated for 4 h with 10 ng/ml LPS from Pseudomonas aeruginosa in media containing 10% human plasma. Culture supernatants containing LPS and factors secreted by THP-1 in response to stimulation were applied to human umbilical vein endothelial cells (HUVECs). Nuclear factor-κB (NF-κB) activity, expression of adhesion molecules, and cytokine secretion were quantified. In addition, the effect of adsorptive removal of tumour necrosis factor-α (TNF-α) from the THP-1 culture supernatant on HUVEC activation was assessed. After 4 h of stimulation, THP-1 cells secreted various mediators including TNF-α (854 ± 472 pg/ml), interleukin (IL)-8 (2069 ± 710 pg/ml), IL-18 (305 ± 124 pg/ml), IL-10 (14 ± 5 pg/ml), and IL-1β (24 ± 11 pg/ml). Stimulated HUVECs showed significantly increased NF-κB activity and secreted high amounts of IL-6 and IL-8. Additionally, adhesion molecules ICAM-1 and E-selectin were increased both in the culture supernatant and at the cell surface. Removal of TNF-α from the THP-1 culture supernatant prior to HUVEC stimulation resulted in a decrease in NF-κB activity, expression of adhesion molecules, as well as IL-6 secretion. The cell culture model established in this study permits the monitoring of LPS-induced endothelial activation, which plays a central role in sepsis and may serve to assess the effect of mediator modulation by methods such as extracorporeal blood purification.

A critical review of human endotoxin administration as an experimental paradigm of depression

The syndrome called depression may represent the common final pathway at which different aetiopathogenic processes converge. One such aetiopathogenic process is innate immune system activation. Some depressed patients have increased levels of inflammatory cytokines and other immunologic abnormalities. It is not known whether immune system activation contributes to the pathogenesis of depressive symptoms. Supporting this possibility is the observation that in both rodents and humans, exogenous immune stimuli such as endotoxin can produce symptoms that resemble depression. A new approach to depression research would be to use immune stimuli to elicit depressive symptoms in humans. Here we review each of the symptoms elicited in humans by endotoxin administration, and compare this model to two other immune depression paradigms: interferon-alpha treatment and typhoid vaccine administration, to assess to what degree endotoxin administration represents a valid model of immune depression. We also review corresponding behavioral changes in rodents and the potential molecular pathways through which immune system activation produces each symptom.

Modulation of splenic immune responses to bacterial lipopolysaccharide in rainbow trout (Oncorhynchus mykiss) fed lentinan, a beta-glucan from mushroom Lentinula edodes

Immunostimulants (IS) are considered a promising approach for improving resistance to pathogens in fish aquaculture. At present, development of IS are complicated due to limited knowledge on the mechanisms of their action. To assess the use of global gene expression analysis for screening of candidate IS we applied lentinan, a beta-glucan from the mushroom Lentinula edodes, as a model. After feeding rainbow trout (Oncorhynchus mykiss) with lentinan-supplemented (L) and control (C) diets for 37 days, fish were injected with bacterial lipopolysaccharide (LPS), a classical inducer of inflammation. Gene expression was analyzed in LPS-challenged compared to saline-injected fish using a salmonid 1.8k cDNA microarray (SFA2.0 immunochip) and real-time qPCR. Spleen was selected for data analyses due to highest magnitude of responses and its key role in the fish immune system. A group of genes implicated in acute inflammatory responses was higher induced in C versus L, including IFN-related and TNF-dependent genes (galectins and receptors, signal transducers and transcription factors), genes involved in MHC class I antigen presentation and leukocyte recruitment. A similar trend was observed in metabolism of iron and xenobiotics, markers of oxidative and cellular stress. Interestingly, differences between C and L were similar to those observed between salmon with low and high resistance to infectious salmon anemia virus. Genes with equal responses to LPS in L and C were related to cell communication (cytokines, chemokines and receptors), signal transduction, activation of immune cells, apoptosis, cellular maintenance and energy metabolism. In conclusion, lentinan decreased the expression of genes involved in acute inflammatory reactions to the inflammatory agent while major parts of the immune response remained unchanged. Such effects are expected for IS, which should modify immunity by enhancing beneficial and reducing detrimental responses.

Bench-to-bedside review: ventilatory abnormalities in sepsis

In septic patients increased central drive and increased metabolic demands combine to increase energy demands on the ventilatory muscles. This occurs at a time when energy supplies are limited and energy production hindered, and it leads to an energy supply-demand imbalance and often ventilatory failure. Problems related to contractile function of the ventilatory muscles also contribute, especially when the clinical course is prolonged. The increased ventilatory activity increases interactions between the ventilatory and cardiovascular systems, and when ventilatory muscles fail and mechanical ventilatory support is required a new set of problems emerges. In this review I discuss factors related to ventilatory muscle failure, giving emphasis to mechanical and supply demand aspects. I also review the implications of changes in ventilatory patterns for heart-lung interactions.

Sequential expression of TLR4 and its effects on the myocardium of rats with myocardial ischemia-reperfusion injury

This study was designed to explore the role of toll like receptor 4 (TLR4) in myocardial ischemia reperfusion injury (MI/RI). Male Sprague-Dawley rats were randomly divided into sham and IR groups (36/group). The rats were sacrificed at various times following reperfusion (0, 1/2, 1, 2, 4 and 8 h). The histopathological and ultrastructural changes in the myocardium were examined under a light microscope and a transmission electron microscope. The TLR4 protein and mRNA expression were detected by immunohistochemistry and real-time reverse transcription polymerase chain reaction, respectively. The levels of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 in the myocardium were measured by enzyme-linked immunosorbent assays. The injury to the myocardium was severe in the IR group, and there were no significant improvements in histopathology and ultrastructure of the myocardium during the first 8 h following reperfusion. Positive TLR4 protein staining was observed in both sham and IR groups. The TLR4 protein levels were significantly increased in the IR group, peaking at 1 h post reperfusion. Additionally, the TLR4 mRNA levels were also up-regulated in the IR group. At all time points, IR rats had significantly higher TNF-alpha and IL-6 levels than the sham rats (P<0.05). The TLR4 mRNA expression positively correlated with the levels of TNF-alpha and IL-6 (r=0.728 and 0.676, P<0.01). Myocardial TLR4 expression was elevated at the early stage of myocardial ischemia reperfusion. Activated TLR4 may play a role in MI/RI by increasing TNF-alpha and IL-6 expression.

Pro-inflammatory genetic background and zinc status in old atherosclerotic subjects

Inflammation and genetics are prominent mechanisms in the pathogenesis of atherosclerosis (AT) and its complications. In this review we discuss the possible impact on AT development of several genetic determinants involved in inflammation, oxidative stress and cytoprotection (IL-6, TNF-alpha, IL-10, CD14, TLR4, MT, HSP70). Genetic polymorphisms of these genes may affect a differential inflammatory response predisposing to AT. However, allelic polymorphisms of genes which increase the risk of AT frequently occur in the general population but, only adequate gene-environment-polymorphism interactions promote the onset of the disease. Zinc deficiency has been suggested as an environmental risk factor for AT. With advancing age, the incidence of zinc deficiency increases for several reasons. Among them, dietary intake, malabsorption and genetic background of inflammatory markers may be involved. A crucial contribution may also be played by increased oxidative stress which may lead to the appearance of dysfunctional proteins, including metallothioneins (MT) that are in turn involved in zinc homeostasis. The detection of candidate genes related to inflammation and promoting AT and their reciprocal influence/interaction with zinc status might allow earlier appropriate dietary interventions in genetically susceptible subjects.

Nicotinamide adenine dinucleotide phosphate (reduced form) oxidase is important for LPS-induced endothelial cell activation

Activation of the endothelium plays an important role in the innate immune response. This process is associated with an increase in the production of superoxide (O2-) by nicotinamide adenine dinucleotide phosphate (reduced form; NADPH) oxidase. Our objective was to determine if O2- from NADPH oxidase contributes to activation of human umbilical vein endothelial cells by LPS as it does for TNF-alpha. We used the adhesion molecule intracellular adhesion molecule 1 and cytokine IL-8 as indicators of human umbilical vein endothelial cell activation and measured O2- production with chemiluminescence. LPS increased baseline and NADPH-stimulated O2- production. The increase was reduced by tiron, a protein kinase C inhibitor (bisindolylmaleimide I hydrochloride), the flavin inhibitor (diphenylene iodonium), and by a short interfering RNA against the p22phox component of NADPH oxidase. Inhibition of NADPH oxidase with the short interfering RNA reduced the induction by LPS of intracellular adhesion molecule 1 mRNA, protein, and IL-8 release (by enzyme-linked immunosorbent assay). The production of O2- by NADPH oxidase contributes to intracellular signaling by LPS in endothelial cells as it does for TNF-alpha and helps turn on the innate immune response in these cells.

Inhibitory effect of simvastatin on the TNF-alpha- and angiotensin II-induced monocyte adhesion to endothelial cells is mediated through the suppression of geranylgeranyl isoprenoid-dependent ROS generation

Vascular endothelial cell activation by cytokines and other pro-inflammatory mediators is an initial event in atherosclerosis and in other vascular diseases. Simvastatin, a HMG-CoA reductase inhibitor, suppressed both tumor necrosis factor (TNF)-alpha- and angiotensin (Ang) II-induced monocyte adhesion to endothelial cells (an initial step in vascular inflammation) and reactive oxygen species (ROS) production. Diphenyleneiodonium and apocynin, both NADPH oxidase inhibitors, also suppressed TNF-alpha-induced ROS and monocyte-endothelial cell adhesion, demonstrating that TNF-alpha-induced monocyte adhesion is mediated through ROS produced by NADPH oxidase activation. Furthermore, exogenously applied mevalonate or geranylgeranylpyrophosphate in combination with simvastatin completely prevented the inhibitory effects of simvastatin on ROS generation and monocyte-endothelial cell adhesion by TNFalpha and Ang II. These results suggest that monocyte adhesion to endothelial cells induced by TNF-alpha or Ang II is mediated via the geranylgeranyl isoprenoid-dependent generation of ROS, and that this is inhibited by simvastatin.

Runx genes are direct targets of Scl/Tal1 in the yolk sac and fetal liver

Transcription factors such as Scl/Tal1, Lmo2, and Runx1 are essential for the development of hematopoietic stem cells (HSCs). However, the precise mechanisms by which these factors interact to form transcriptional networks, as well as the identity of the genes downstream of these regulatory cascades, remain largely unknown. To this end, we generated an Scl(-/-) yolk sac cell line to identify candidate Scl target genes by global expression profiling after reintroduction of a TAT-Scl fusion protein. Bioinformatics analysis resulted in the identification of 9 candidate Scl target transcription factor genes, including Runx1 and Runx3. Chromatin immunoprecipitation confirmed that both Runx genes are direct targets of Scl in the fetal liver and that Runx1 is also occupied by Scl in the yolk sac. Furthermore, binding of an Scl-Lmo2-Gata2 complex was demonstrated to occur on the regions flanking the conserved E-boxes of the Runx1 loci and was shown to transactivate the Runx1 element. Together, our data provide a key component of the transcriptional network of early hematopoiesis by identifying downstream targets of Scl that can explain key aspects of the early Scl(-/-) phenotype.

TNF-alpha-mediated inflammation in cerebral aneurysms: a potential link to growth and rupture

Intracranial aneurysm (IA) rupture is one of the leading causes of stroke in the United States and remains a major health concern today. Most aneurysms are asymptomatic with a minor percentage of rupture annually. Regardless, IA rupture has a devastatingly high mortality rate and does not have specific drugs that stabilize or prevent aneurysm rupture, though other preventive therapeutic options such as clipping and coiling of incidental aneurysms are available to clinicians. The lack of specific drugs to limit aneurysm growth and rupture is, in part, attributed to the limited knowledge on the biology of IA growth and rupture. Though inflammatory macrophages and lymphocytes infiltrate the aneurysm wall, a link between their presence and aneurysm growth with subsequent rupture is not completely understood. Given our published results that demonstrate that the pro-inflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), is highly expressed in human ruptured aneurysms, we hypothesize that pro-inflammatory cell types are the prime source of TNF-alpha that initiate damage to endothelium, smooth muscle cells (SMC) and internal elastic lamina (IEL). To gain insights into TNF-alpha expression in the aneurysm wall, we have examined the potential regulators of TNF-alpha and report that higher TNF-alpha expression correlates with increased expression of intracellular calcium release channels that regulate intracellular calcium (Ca2+), and Toll like receptors (TLR) that mediate innate immunity. Moreover, the reduction of tissue inhibitor of metalloproteinase-1 (TIMP-1) expression provides insights on why higher matrix metalloproteinase (MMP) activity is noted in ruptured IA. Because TNF-alpha is known to amplify several signaling pathways leading to inflammation, apoptosis and tissue degradation, we will review the potential role of TNF-alpha in IA formation, growth and rupture. Neutralizing TNF-alpha action in the aneurysm wall may have a beneficial effect in preventing aneurysm growth by reducing inflammation and arterial remodeling.

TNF-α-induced self expression in human lung endothelial cells is inhibited by native and oxidized α1-antitrypsin

Endothelial cells are among the main physiological targets of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). In endothelial cells TNF-alpha elicits a broad spectrum of biological effects including differentiation, proliferation and apoptosis. alpha1-antitrypsin (AAT), an endogenous inhibitor of serine proteases plays a vital role in protecting host tissue from proteolytic injury at sites of inflammation. Recently, it has been shown that AAT can be internalized by pulmonary endothelial cells, raising speculation that it may modulate endothelial cell function in addition to suppressing protease activity. Using Affymetrix microarray technology, real time PCR and ELISA methods we have investigated the effects of AAT on un-stimulated and TNF-alpha stimulated human primary lung microvascular endothelial cell gene expression and protein secretion. We find that AAT and TNF-alpha generally induced expression of distinct gene families with AAT exhibiting little activity in terms of inflammatory gene expression. Approximately 25% of genes up regulated by TNF-alpha were inhibited by co-administration of AAT including TNF-alpha-induced self expression. Surprisingly, the effects of AAT on TNF-alpha-induced self expression was inhibited equally well by oxidized AAT, a modified form of AAT, which lacks serine protease inhibitor activity. Overall, the pattern of gene expression regulated by native and oxidized AAT was similar with neither inducing pro-inflammatory gene expression. These findings suggest that inhibitory effects of native and oxidized forms of AAT on TNF-alpha stimulated gene expression may play an important role in limiting the uncontrolled endothelial cell activation and vascular injury in inflammatory disease.

Relationship of toll-like receptor 4, nuclear factor kappa B and acute pancreatitis

Acute pancreatitis (AP) is a serious commonly-occurring disease. Toll-like receptor 4 (TLR4) and nuclear factor kappa B (NF-κB) are closely related to the activation of many cytokines that have important roles in the occurrence and development of AP. It is already acknowledged that TLR4 and NF-κB have roles in the pathogenesis of acute necrotizing pancreatitis (ANP) because they are essential in the inducing and mediating of inflammation. It is thought that TLR4 induces LPS signaling, which leads to the activation and translocation of NF-κB, and then stimulates the production of proinflammatory cytokines that result in the occurrence of inflammation. Recently, however, new concepts about the specific signaling pathway of TLR4/NF-κB and the factors participating in it have been proposed. This review summarizes the TLR4/NF-κB signaling pathway and outlines the factors that can down- or up-regulate TLR4/NF-κB expression and other factors that activate NF-κB.