Proinflammatory Cytokine Stimulation Research Articles

Dysregulated expression of miR‐146a contributes to age‐related dysfunction of macrophages

Age-associated immune dysfunction, characterized by increased systemic levels of cytokines, manifests as an increased susceptibility to infections. Thus, understanding these negative regulators of the immune response has paved the way to delineating signaling pathways that impact immune senescence. In the present study, we found that miR-146a, which negatively regulated the expression of IL-1β and IL-6, was highly expressed in aged mice. However, there was a lack of response to the stimulation of lipopolysaccharide (LPS) and proinflammatory cytokines in macrophages of aged mice. As a result, the negative feedback regulation loop with miR-146a involving down-regulation of inflammation factors was interrupted in aged mice. Aberrant NF-κB binding to the miR-146a promoter was demonstrated to be associated with the abnormal expression of miR-146a in aged mice. The DNA methyltransferase inhibitor (5-aza-2-deoxycytidine) and the histone deacetylase inhibitor [trichostatin A (TSA)] both significantly up-regulated miR-146a transcriptional activation by altering the DNA-binding activity of NF-κB in macrophages isolated from aged mice, which suggests that DNA methylation and histone acetylation are involved in the suppression of age-dependent miR-146a expression. Additionally, high levels of histone deacetylase (HDACs) expressions contributed to the inhibition of miR-146a expression in LPS-stimulated macrophages from aged mice in vitro. While the suppression of HDACs activities by TSA could improve LPS-induced inflammatory responses owing to up-regulation of miR-146a expression in macrophages from aged mice. These data indicate that the dysregulated expression of miR-146a results in the age-associated dysfunction of macrophages, and miR-146a may be a good target for the treatment of age-related inflammatory diseases.

The role of the sympathetic and sensory nervous system in peritoneal endometriotic lesions

Question: The nervous system (NS) has an influence on the pathogenesis of chronic inflammatory autoimmune diseases (AID). The sympathetic NS exerts an anti-inflammatory effect while the sensory NS promotes inflammatory changes, through a stimulation of immune cells and proinflammatory cytokines. A reduced density of sympathetic nerve fibers (syNF) in inflammatory tissue and an increased density of sensory (se) NF could be seen. Similar to AID, endometriosis (EM) is a chronic inflammatory disease, associated with chronic pelvic pain. In human peritoneal endometriotic lesions (pEL), seNF and syNF are present.

Bile acid-induced expression of activation-induced cytidine deaminase during the development of Barrett’s oesophageal adenocarcinoma

Activation-induced cytidine deaminase (AID) induces somatic mutations in various host genes of non-lymphoid tissues, thereby contributing to carcinogenesis. We recently demonstrated that Helicobacter pylori infection and/or proinflammatory cytokine stimulation triggers aberrant AID expression in gastric epithelial cells, causing mutations in the tumour-suppressor TP53 gene. The findings of the present study provide evidence of ectopic AID expression in Barrett's oesophagus and Barrett's oesophageal adenocarcinoma, a cancer that develops under chronic inflammatory conditions. Immunoreactivity for endogenous AID was observed in 24 of 28 (85.7%) specimens of the columnar cell-lined Barrett's oesophagus and in 20 of 22 (90.9%) of Barrett's adenocarcinoma, whereas weak or no AID protein expression was detectable in normal squamous epithelial cells of the oesophagus. We validated these results by analysing tissue specimens from another cohort comprising 16 cases with Barrett's oesophagus and four cases with Barrett's adenocarcinoma. In vitro treatment of human non-neoplastic oesophageal squamous-derived cells with sodium salt deoxycholic acid induced ectopic AID expression via the nuclear factor-kappaB activation pathway. These findings suggest that aberrant AID expression occurs in a substantial proportion of Barrett's epithelium, at least in part due to bile acid stimulation. Considering the genotoxic activity of AID, our current findings suggest that aberrant AID expression might enhance the susceptibility to genetic alterations in Barrett's columnar-lined epithelial cells, leading to cancer development.

CXCL8 protects human neurons from amyloid-β-induced neurotoxicity: Relevance to Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by amyloid-β (Aβ) deposition in senile plaques colocalized with activated microglia and astrocytes. Recent studies suggest that CXCL8 is involved in the AD pathogenesis. The objective of this study was to determine the cellular sources of CXCL8 in the central nervous system during AD pathogenesis, and investigate the effects of CXCL8 on neuronal survival and/or functions. Our results showed significantly higher CXCL8 levels in AD brain tissue lysates as compared to those of age-matched controls. Upon Aβ and/or pro-inflammatory cytokine stimulation, microglia, astrocytes and neurons were all capable of CXCL8 production in vitro. Although CXCL8-alone did not alter neuronal survival, it did inhibit Aβ-induced neuronal apoptosis and increased neuronal brain-derived neurotrophic factor (BDNF) production. We conclude that microglia, astrocytes and neurons, all contribute to the enhanced CXCL8 levels in the CNS upon Aβ and/or pro-inflammatory cytokine stimulation. Further, CXCL8 protects neurons possibly by paracrine or autocrine loop and regulates neuronal functions, therefore, may play a protective role in the AD pathogenesis.

Human cardiac fibroblasts express ICAM-1, E-selectin and CXC chemokines in response to proinflammatory cytokine stimulation

Neutrophil attraction and adhesion to endothelial cells occurs via well defined mechanisms, yet the ability of other cell types to express neutrophil-binding adhesion molecules is not well studied. Cardiac fibroblasts (CF) are a key cell type involved in repair of the infarcted myocardium, a scenario in which neutrophil recruitment is perceived to be detrimental. Here we determined the effects of proinflammatory cytokines on expression of neutrophil-binding adhesion molecules and neutrophil-attracting chemokines in CF cultured from multiple patients, and explored the underlying regulatory mechanisms. An adhesion molecule focused RT-PCR array identified 5 transcripts that were increased markedly in human CF treated with the proinflammatory cytokine interleukin-1 (IL-1, 10 ng/ml, 6 h); including intercellular cell adhesion molecule (ICAM-1) and E-selectin. Real-time RT-PCR verified the array data and immunoblotting confirmed cytokine-induced ICAM-1 and E-selectin protein expression. Treatment with a panel of pharmacological inhibitors identified the NF-κB pathway as mediating IL-1-induced ICAM-1 and E-selectin mRNA and protein expression. Additionally, E-selectin expression in human CF was markedly potentiated by the JNK inhibitor SP600125, but this was not observed when a more selective inhibitor ((L)-JNKI-1) was used, or in human vascular endothelial cells. IL-1 also stimulated CF to secrete the neutrophil chemoattractant CXCL8 via a p38- and NF-κB-dependent mechanism, as well as inducing CXCL1, CXCL2 and CXCL5 mRNA expression. In conclusion, human CF express neutrophil-binding adhesion molecules and neutrophil chemoattractants in response to proinflammatory cytokines suggesting that, in addition to EC, CF may play an important role in regulating neutrophil recruitment into the infarcted myocardium.

The human T-cell leukemia virus type I (HTLV-I) oncoprotein Tax promotes persistent NF-κB activation by blocking the phosphorylation of the adaptor molecule TAX1BP

Persistent activation of the transcription factor NF-κB by HTLV-1 Tax plays a critical role in T-cell transformation and the onset of adult T-cell leukemia (ATL). Tax activates NF-κB by binding to the NEMO/IKKgamma subunit of the IKK complex, thus leading to persistent IKK activation and nuclear translocation of NF-κB dimers. In addition, Tax counteracts negative regulators of NF-κB such as A20 although the underlying mechanisms remain unclear. We have previously reported that the Tax interacting protein TAX1BP1 serves as a scaffold molecule for the A20 ubiquitin-editing complex, consisting of A20, TAX1BP1, Itch and RNF11, that is critical for the negative feedback of NF-κB. Here we demonstrate that the IKKalpha subunit of IKK phosphorylated TAX1BP1 at Ser593 and Ser624 in response to proinflammatory cytokine stimulation. TAX1BP1 phosphorylation by IKKalpha is essential for the inducible interactions between TAX1BP1, A20, Itch and RNF11 and the subsequent NF-κB inhibitory function of A20. Interestingly, HTLV-I Tax potently blocks TAX1BP1 phosphorylation by preventing the recruitment of IKKalpha to TAX1BP1. Therefore, Tax promotes constitutive NF-κB signaling by inhibiting TAX1BP1 phosphorylation, thus blocking the assembly of the A20 ubiquitin-editing complex and impairing the function of A20.

Abstract 1346: Discovery of novel MSK1 inhibitors with hybrid virtual screening and structure-based drug design

Abstract Mitogen- and stress-activated protein kinase 1 (MSK1) is a serine/threonine kinase that is involved in gene transcription regulation and pro-inflammatory cytokine stimulation. MSK1 is an attractive target for the treatment of chronic inflammatory diseases. Currently, no small molecule inhibitor has been identified that specifically targets MSK1 and only H-89 is a known inhibitor. In this study, we performed hybrid virtual screening (HVS) to identify novel small molecule inhibitors that target MSK1. For the screening, we used the active conformation of the C-terminal kinase domain of the dual kinase as the protein template. Computational screening of several well-known compound databases, including the FDA, Natural Product, ZINC all purchasable and PDB ligands databases, revealed 40 potential leads. We tested 11 lead compounds and found 5 that showed substantial in vitro inhibitory activity against MSK1. These results illustrated that our computational screening processes greatly enhanced the success rate of virtual screening. The high-performing HVS protocols were especially successful to retrieve thousands of promising new leads from millions of compounds in conjunction with structure-based drug design and then to further select true hits from the majority of high-scoring decoys. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1346. doi:10.1158/1538-7445.AM2011-1346

Adipose tissues from RA and OA patients differ in cytokine and adipokine production

ObjectivesCytokines and adipokines play fundamental role in synovial inflammation and articular destruction. Articular and subcutaneous adipose tissues have been suggested to play a role in inflammatory joint diseases. The aim...

FOXO3a inhibits TNF‐α‐ and IL‐1β‐induced astrocyte proliferation:Implication for reactive astrogliosis

Reactive astrogliosis is one of the pathological hallmarks of neurodegenerative diseases. Inflammatory cytokines, such as TNF-α and IL-1β, have been shown to mediate the reactive astrogliosis in neurodegenerative diseases; however, the molecular mechanism remains unclear. In this study, we investigated the role of transcription factor FOXO3a on astrocyte proliferation, one primary aspect of severe reactive astrogliosis. Our results confirmed that TNF-α and IL-1β increased astrocyte proliferation, as determined by Ki67 and BrdU immunostaining. Furthermore, we found that cytokine-mediated astrocyte proliferation was accompanied by an increase of the phosphorylation and reduced nuclear expression of FOXO3a. Intracranial injection of TNF-α and IL-1β induced astrocyte proliferation and hypertrophy, which was associated with reduced nuclear expression of Foxo3a in astrocytes. To determine the function of FOXO3a in astrocyte proliferation, wild type FOXO3a was overexpressed with adenovirus, which subsequently upregulated p27Kip1 and Gadd45α, and significantly inhibited cytokine-induced astrocyte proliferation. In contrast, overexpression of dominant negative FOXO3a decreased p27Kip1, upregulated cyclin D1 and promoted astrocyte proliferation. Along the same line, astrocytes isolated from Foxo3a-null mice have higher proliferative potential. In response to intracranial injection of cytokines, Foxo3a-null mice manifested severe astrogliosis in vivo. In conclusion, FOXO3a is important in restraining astrocyte proliferation during proinflammatory cytokine stimulation and loss of function of FOXO3a may be responsible for the proliferation of astrocytes in the severe form of reactive astrogliosis. Understanding the key regulatory role of FOXO3a in reactive astrogliosis may provide a novel therapeutic target during neuroinflammation.

Nanotoxicology : An Emerging Discipline

Nanotoxicology refers to the study of the interactions of nanostructures with biological systems with an emphasis on elucidating the relationship between the physical and chemical properties of nanostructures with induction of toxic biological responses. Nanotoxicology is aimed at providing information on the potential toxicological effects, risk assessment and safety evaluation of nanostructured materials on human health. Nanoparticles present possible dangers, both medically and environmentally. They are also able to pass through cell membranes in organisms and their interactions with biological systems are relatively unknown. Animal studies have shown that nanoparticles can penetrate cells and tissues, move through the body and brain and cause biochemical damage. The greater chemical reactivity of nanomaterials result in increased production of reactive oxygen species which may contribute to similar patterns of cell injury and alterations at the molecular level by initiation, propagation and autocatalytic chain reactions. Intracellular signaling activation and inactivation of enzymes, stimulation, secretion and release of pro-inflammatory cytokines, chemokines and nuclear factor activation and alteration are also common events.

Targeted expression of islet neogenesis associated protein to beta cells enhances glucose tolerance and confers resistance to streptozotocin-induced hyperglycemia

Islet neogenesis associated protein (INGAP) stimulates experimental pancreatic islet growth, as evidenced by elevated markers of beta cell mass, in rodents, dogs and primates. Previous analyses of mice that have a transgenic expression of INGAP targeted to the exocrine pancreas have indicated additional biological activity attributed to INGAP. In this study we report on mice with a targeted expression of INGAP to the islet beta cell. The beta cell transgenic mice (IP-INGAP) showed enhanced normalization of blood glucose during IPGTT. Further, IP-INGAP mice had a significant delay in development of hyperglycemia following a diabetogenic dose of streptozotocin. INGAP conferred beta cell protection and enhanced islet function. Analysis of oxidative stress genes in IP-INGAP mice revealed a decrease in islet expression of the NADPH oxidase, NOX1, in both basal state and in response to pro-inflammatory cytokine stimulation. These data are consistent with a pleiotropic role for INGAP and reveal new pathways to target in the discovery of improved diabetic therapies.

Acute resistance exercise results in catecholaminergic rather than hypothalamic–pituitary–adrenal axis stimulation during exercise in young men

Exercise is a paradigm of a stress situation. The adaptive response to stressors comprises the activation of the hypothalamic–pituitary–adrenal (HPA) axis and components of the autonomic sympathetic system. An aseptic inflammatory reaction is triggered by exercise, involving the stimulation of the so-called proinflammatory cytokines, such as tumor necrosis factor α (TNFα), interleukin-1 (IL-1), and IL-6. The anti-inflammatory cytokines IL-2, IL-8, and IL-10 increase moderately during resistance exercise. To investigate the effect of a short bout of resistance exercise on components of the stress and inflammatory responses during the exercise period, 17 healthy, young, untrained male volunteers were studied during 3 equal consecutive cycles of resistance exercises of 30 min total duration. Blood sampling was performed at baseline and at the end of each cycle. Lactate, cortisol, catecholamines (epinephrine, norepinephrine), IL-1α, IL-1β, IL-2, IL-6, IL-8, IL-10, epidermal growth factor (EGF), and monocyte chemotactic protein-1 (MCP-1) were measured at all time-points. Circulating levels of catecholamines and lactate increased significantly (P < 0.05) whereas cortisol did not. During the time course of the exercise, circulating levels of TNFα, IL-2, and EGF increased, whereas MCP-1 decreased significantly. IL-1α, IL-1β, IL-6, IL-8, and IL-10 levels did not change significantly. Statistically significant positive linear correlations were found between areas under the curve for increases in levels of IL-2 and TNFα, TNFα and cortisol, as well as epinephrine and norepinephrine. We conclude that acute resistance exercise results in catecholaminergic, but not HPA axis stimulation during exercise, in parallel with a mild inflammatory reaction. The absence of a major inflammatory reaction and of a cortisol increase during acute resistance exercise makes this a good candidate for the exercise of sedentary individuals.

Granzyme B-induced and Caspase 3-dependent Cleavage of Gelsolin by Mouse Cytotoxic T Cells Modifies Cytoskeleton Dynamics

Granule-associated perforin and granzymes (gzms) are key effector molecules of cytotoxic T lymphocytes (Tc cells) and natural killer cells and play a critical role in the control of intracellular pathogens and cancer. Based on the notion that many gzms, including A, B, C, K, H, and M exhibit cytotoxic activity in vitro, all gzms are believed to serve a similar function in vivo. However, more recent evidence supports the concept that gzms are not unidimensional but, rather, possess non-cytotoxic potential, including stimulation of pro-inflammatory cytokines and anti-viral activities. The present study shows that isolated mouse gzmB cleaves the actin-severing mouse protein, cytoplasmic gelsolin (c-gelsolin) in vitro. However, when delivered to intact target cells by ex vivo immune Tc cells, gzmB mediates c-gelsolin proteolysis via activation of caspases 3/7. The NH(2)-terminal c-gelsolin fragment generated by either gzmB or caspase 3 in vitro constitutively severs actin filaments without destroying the target cells. The observation that gzmB secreted by Tc cells initiates a caspase cascade that disintegrates the actin cytoskeleton in target cells suggests that this intracellular process may contribute to anti-viral host defense.

Current perspective of pathophysiological and interventional effects on endothelial progenitor cell biology: Focus on Pi3K/AKT/eNOS pathway

For more than a decade, endothelial progenitor cells (EPCs) have been implicated in cardiovascular homeostasis. EPCs are believed to reside within the bone marrow in close contact with surrounding stromal cells, and, under stimulation of pro-inflammatory cytokines, EPCs are mobilized out of the bone marrow. Hereafter circulating EPCs home to peripheral tissues, undergoing further proliferation and differentiation. Under certain pathophysiologic conditions this process seems to be blunted, resulting in a reduced capacity of EPCs to engage in vasculogenesis at sites of endothelial injury or tissue ischemia. In this review, we focus on the effects of traditional cardiovascular risk factors on EPC biology and we explore whether pharmacological, dietary and lifestyle interventions can favorably restore EPC mobilization, differentiation, homing and angiogenic properties. Because the PI3K/Akt/eNOS pathway plays a pivotal role in the process of EPC mobilization, migration and homing, we specifically emphasize the involvement of PI3K, Akt and eNOS in EPC biology under these different (patho)physiologic conditions. (Pre)clinically used drugs or lifestyle interventions that have been shown to ameliorate EPC biology are reviewed. These treatment strategies remain attractive targets to restore the regenerative capacity of EPCs in cardiovascular diseases.

Chylomicrons combined with endotoxin moderate microvascular permeability

Triglyceride-rich lipoprotein-bound endotoxin (CM-LPS) inhibits the host innate immune response to sepsis by attenuating the hepatocellular response to pro-inflammatory cytokine stimulation. This 'cytokine tolerance' in hepatocytes is a transient, receptor-dependent process that correlates with internalization of CM-LPS via low density lipoprotein (LDL) receptors. Since endothelial cells are integral to the immune response and similarly express LDL receptors, we hypothesized that CM-LPS could be internalized and ultimately attenuate the deleterious effects of pro-inflammatory molecules like tumor necrosis factor-α (TNF-α) and platelet activating factor (PAF) on endothelial permeability. Here, we show that CM-LPS complexes induce cytokine tolerance in endothelial cells. In rats, TNF-α increased hydraulic conductivity 2.5-fold over baseline and PAF increased it 5-fold; but, pretreatment with CM-LPS or an attenuated analog (CM-LPS*) inhibited these changes. Nuclear/cytoplasmic levels of p65 were reduced after TNF-α-stimulation in endothelial cell monolayers pretreated with CM-LPS, a finding consistent with inhibition of nuclear factor (NF)-κB translocation. Also consistent with inhibition was stabilized intercellular adhesion, as illustrated with antibody to VE-cadherin using confocal microscopy. These results provide additional support for the integral role of lipoproteins in the innate immune response to infection and lend further credence to developing lipid-based therapy for Gram-negative sepsis.

Abstract 2680: Nonautoinhibitory properties of the C-terminal helix of the mitogen- and stress-activated protein kinase 1

Abstract Mitogen- and stress-activated protein kinase 1 (MSK1) is a growth factor-stimulated serine/threonine kinase that is important in the regulation of gene transcription and proinflammatory cytokine stimulation. MSK1 is a dual kinase possessing two distinct kinase domains linked by a hydrophobic region. The C-terminal kinase domain (CTD MSK1) is an important regulatory domain activated by ERKs and p38 mitogen-activated protein kinases (MAPKs) in response to various cellular stimuli. The activity of full length MSK1 is controlled by multiple phosphorylation sites and is mediated through stimulation of the C-terminal kinase domain. We have determined the crystal structure of the isolated active CTD MSK1 (residues 414-738) in apo- form and in complex with the non-hydrolyzable ATP analogue AMP-PNP at 2.0 and 2.5 Å resolution, respectively. The structure showed that, despite overall similarity with the p90 ribosomal S6 kinase 2 (RSK2) and the MAPK-activated protein kinase 2 (MK2), the CTD MSK1 is unexpectedly not autoinhibited by the C-terminal αL-helix. The helix does not form hydrogen bonds with a substrate-binding loop and nearby helices and lacks putative “inhibitory” residues responsible for the interaction with the kinase core. CTD MSK1 undergoes active autophosphorylation in vitro as shown by luminescent assay, and mutation of two residues, H712K and F719Y, located on the αL-helix does not convert it to RSK2-like autoinhibitory state. The protein was phosphorylated at Thr581 in the T-activation loop, and a T581A mutant showed significantly impaired autokinase activity. The “full length” C-terminal domain of MSK1 (residues 414-802) possessed weaker autophosphorylation activity compared with the truncated fragment (residues 414-738), which lacks the MAPK-docking site. Overexpression of active truncated CTD MSK1 (residues 414-738) in JB6 cells resulted in neoplastic transformation in response to EGF or TPA stimulation in a manner similar to that induced by the full length MSK1. On the other hand, the “full length” CTD (residues 414-802) suppressed colony formation ex vivo. This results indicate that the extreme C-terminal tail (residues 739-802), which encloses the ERK/p38 docking site, inhibits CTD MSK1 kinase activity. Using surface plasmon resonance (SPR) binding experiments, we showed that the C-terminal end-deleted construct does not interact with ERK1 in vitro, but the “full length” CTD MSK1 binds with ERK1 in a dose-dependent manner with a KD ∼ 70 nM. Similar binding results were obtained for interaction with ERK2 and p38. The SPR data indicate that the αL-helix is not involved in the interaction with MAP kinases. The intrinsic non-autoinhibitory C-terminal αL-helix feature suggests that the CTD has a αL-helix-independent activation mechanism, and the MAPK-docking site may regulate CTD MSK1 activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2680.

The Crystal Structure of the Active Form of the C-Terminal Kinase Domain of Mitogen- and Stress-Activated Protein Kinase 1

Mitogen- and stress-activated protein kinase 1 (MSK1) is a growth-factor-stimulated serine/threonine kinase that is involved in gene transcription regulation and proinflammatory cytokine stimulation. MSK1 is a dual kinase possessing two nonidentical protein kinase domains in one polypeptide. We present the active conformation of the crystal structures of its C-terminal kinase domain in apo form and in complex with a nonhydrolyzable ATP analogue at 2.0 Å and 2.5 Å resolutions, respectively. Structural analysis revealed substantial differences in the contacts formed by the C-terminal helix, which is responsible for the inactivity of other autoinhibited kinases. In the C-terminal kinase domain of MSK1, the C-terminal αL-helix is located in the surface groove, but forms no hydrogen bonds with the substrate-binding loop or nearby helices, and does not interfere with the protein's autophosphorylation activity. Mutational analysis confirmed that the αL-helix is inherently nonautoinhibitory. Overexpression of the single C-terminal kinase domain in JB6 cells resulted in tumor-promoter-induced neoplastic transformation in a manner similar to that induced by the full-length MSK1 protein. The overall results suggest that the C-terminal kinase domain of MSK1 is regulated by a novel αL-helix-independent mechanism, suggesting that a diverse mechanism of autoinhibition and activation might be adopted by members of a closely related protein kinase family.

IL-1β Processing in Host Defense: Beyond the Inflammasomes

Stimulation and release of proinflammatory cytokines is an essential step for the activation of an effective innate host defense, and subsequently for the modulation of adaptive immune responses. Interleukin-1β (IL-1β) and IL-18 are important proinflammatory cytokines that on the one hand activate monocytes, macropages, and neutrophils, and on the other hand induce Th1 and Th17 adaptive cellular responses. They are secreted as inactive precursors, and the processing of pro-IL-1β and pro-IL-18 depends on cleavage by proteases. One of the most important of these enzymes is caspase-1, which in turn is activated by several protein platforms called the inflammasomes. Inflammasome activation differs in various cell types, and knock-out mice defective in either caspase-1 or inflammasome components have an increased susceptibility to several types of infections. However, in other infections and in models of sterile inflammation, caspase-1 seems to be less important, and alternative mechanisms such as neutrophil-derived serine proteases or proteases released from microbial pathogens can process and activate IL-1β. In conclusion, IL-1β/IL-18 processing during infection is a complex process in which the inflammasomes are only one of several activation mechanisms.

High Expression of Vascular Endothelial Growth Factor in EV71-Infected Patients Does Not Originate from EV71-Infected Cells

Background: Enterovirus (EV) 71 is an important pathogen causing death in children under 5 years of age worldwide. However, the core pathogenesis remains elusive. We reveal that the protein expression level of vascular endothelial growth factor (VEGF) in EV71 patients was 2-fold higher than in normal controls. However, the origin of VEGF in EV71-infected patients remains unclear. Methods: VEGF mRNA and protein expression in four EV71-infected cell lines was evaluated by RT-PCR, ELISA and Western blotting. Results: We found that only mRNA expression of VEGF was increased in the infected cells. Intra- and extracellular VEGF protein expression was decreased or unchanged in the four infected cell lines compared with the uninfected and inactivated EV71-infected cells. Conclusions: Our data reveal that EV71 infection of four human cell lines induced VEGF mRNA expression but did not induce VEGF protein expression in the infected cells. Therefore, the increased VEGF protein expression in EV71-infected patients may be due to the influence of surrounding non-infected cells following stimulation of proinflammatory cytokines secreted from the infected cells.

Effect of pro-inflammatory cytokine stimulation on human breast cancer: Implications of chemokine receptor expression in cancer metastasis

Interactions between tumour cells and microenvironments may affect their growth and metastasis formation. In search for a better understanding of the role of cellular mediators in the progression of cancer, we investigated the effect of pro-inflammatory cytokines IL-1, IL-6, TNF-α and IFN-γ on the regulation of expression of chemokine receptors CXCR4, CXCR2, CX3CR1, CCR9, and CCR5 in the human breast cancer cell line MCF-7. Our results showed that IL-1 increased CXCR4 expression whereas TNF-α increased CX3CR1, CCR9 and CCR5. Interestingly, this regulation was not homogeneous, emphasizing the inherent heterogeneity in cancer that may be responsive to specific inflammatory microenvironments.