Promoter elements responsible for antioxidant regulation of MCP-1 gene expression

Impact of exposure of human osteoblast cells to titanium dioxide particles in-vitro

Titanium Dental implant is the most successful treatment modality to replace missing teeth today. Although titanium is considered biologically biocompatible, strong, and corrosion-free, the risk of implant failure continues due to bone loss at the expense of optimum oral health. Current research points toward the presence of titanium dioxide (TiO₂) particles leached from dental implant surface, which occurred due to mechanical and chemical insults on the surface. This study aimed to investigate the influence of TiO₂ particles of different sizes leaching from implant surfaces on Human Osteoblast cells (HOB) in-vitro. Titanium dioxide particles in both nano (NPs) and micro (MPs) size and at different concentrations were introduced to human osteoblast cells with and without treatment with vitamin C. Production of ROS was measured using H2DCFDA cellular ROS Assay Kit and MCP-1 and IL-8 cytokines released were assayed at 24 h time point using ELISA technique. Results showed a dose dependent increase in ROS production following exposure of HOB to both nano and micro particles. MCP-1 and IL-8 were released and there was minimal difference between the amount generated by nano compared with micro size particles. Treatment of HOB with antioxidant vitamin C demonstrated a significant reduction in the generation of ROS. At the same time, MCP-1 release was reduced significantly for the 100 μg/mL TiO₂ NPs and MPs after Vitamin C treatment while IL-8 release increased significantly. This study suggests a positive role played by antioxidants in the control of ROS generation and chemokines production in the peri-implant tissue environment.

On the Immunometabolic Role of NF-κB in Adipocytes

Two decades of research have established that Nuclear Factor-κB (NF-κB) signaling plays a critical role in reprogramming the fat cell transcriptome towards inflammation in response to overnutrition and metabolic stress. Several groups have suggested that inhibition of NF-κB signaling could have metabolic benefits for obesity-associated adipose tissue inflammation. However, two significant problems arise with this approach. The first is how to deliver general NF-κB inhibitors into adipocytes without allowing these compounds to disrupt normal functioning in cells of the immune system. The second issue is that general inhibition of canonical NF-κB signaling in adipocytes will likely lead to a massive increase in adipocyte apoptosis under conditions of metabolic stress, leading full circle into a secondary inflammation (However, this problem may not be true for non-canonical NF-κB signaling.). This review will focus on the research that has examined canonical and non-canonical NF-κB signaling in adipocytes, focusing on genetic studies that examine loss-of-function of NF-κB specifically in fat cells. Although the development of general inhibitors of canonical NF-κB signaling seems unlikely to succeed in alleviating adipose tissue inflammation in humans, the door remains open for more targeted therapeutics. In principle, these would include compounds that interrogate NF-κB DNA binding, protein-protein interactions, or post-translational modifications that partition NF-κB activity towards some genes and away from others in adipocytes. I also discuss the possibility for inhibitors of non-canonical NF-κB signaling to realize success in mitigating fat cell dysfunction in obesity. To plant the seeds for such approaches, much biochemical “digging” in adipocytes remains; this includes identifying—in an unbiased manner–NF-κB direct and indirect targets, genomic DNA binding sites for all five NF-κB subunits, NF-κB protein-protein interactions, and post-translational modifications of NF-κB in fat cells.

Human monocytes subjected to ischaemia/reperfusion inhibit angiogenesis and wound healing in vitro

OBJECTIVES

The sequence of initial tissue ischaemia and consecutive blood flow restoration leads to ischaemia/reperfusion (I/R) injury, which is typically characterized by a specific inflammatory response. Migrating monocytes seem to mediate the immune response in ischaemic tissues and influence detrimental as well as regenerative effects during I/R injury.

MATERIALS AND METHODS

To clarify the role of classical monocytes in I/R injury, isolated human monocytes were subjected to I/R in vitro (3 hours ischaemia followed by 24 hours of reperfusion). Cellular resilience, monocyte differentiation, cytokine secretion, as well as influence on endothelial tube formation, migration and cell recovery were investigated.

RESULTS

We show that I/R supported an enhanced resilience of monocytes and induced intracellular phosphorylation of the prosurvival molecules Erk1/2 and Akt. FACS analysis showed no major alteration in monocyte subtype differentiation and surface marker expression under I/R. Further, our experiments revealed that I/R changes the cytokine secretion pattern, release of angiogenesis associated proteins and MMP-9 activity in supernatants of monocytes exposed to I/R. Supernatants from monocytes subjected to I/R attenuated endothelial tube formation as indicator for angiogenesis as well as endothelial cell migration and recovery.

CONCLUSION

In summary, monocytes showed no significant change in cellular integrity and monocyte subtype after I/R. Functionally, monocytes might have a rather detrimental influence during the initial phase of I/R, suppressing endothelial cell migration and neoangiogenesis.

Inhibitor of apoptosis proteins are potential targets for treatment of granulosa cell tumors - implications from studies in KGN

Background

Granulosa cell tumors (GCTs) are derived from proliferating granulosa cells of the ovarian follicle. They are known for their late recurrence and most patients with an aggressive form die from their disease. There are no treatment options for this slowly proliferating tumor besides surgery and chemotherapy. In a number of tumors, analogs of the second mitochondria-derived activator of caspases (SMAC), alone or in combination with other molecules, such as TNFα, are evolving as new treatment options. SMAC mimetics block inhibitor of apoptosis proteins (IAPs), which bind caspases (e.g. XIAP), or activate the pro-survival NF-κB pathway (e.g. cIAP1/2). Expression of IAPs by GCTs is yet not fully elucidated but recently XIAP and its inhibition by SMAC mimetics in a combination therapy was described to induce apoptosis in a GCT cell line, KGN. We evaluated the expression of cIAP1 in GCTs and elucidated the effects of the SMAC mimetic BV-6 using KGN as a model.

Results

Employing immunohistochemistry, we observed cIAP1 expression in a tissue microarray (TMA) of 42 GCT samples. RT-PCR confirmed expression of cIAP1/2, as well as XIAP, in primary, patient-derived GCTs and in KGN. We therefore tested the ability of the bivalent SMAC mimetic BV-6, which is known to inhibit cIAP1/2 and XIAP, to induce cell death in KGN. A dose response study indicated an EC₅₀ ≈ 8 μM for both, early (< 8) and advanced (> 80) passages, which differ in growth rate and presumably aggressiveness. Quantitative RT-PCR showed upregulation of NF-κB regulated genes in BV-6 stimulated cells. Blocking experiments with the pan-caspase inhibitor Z-VAD-FMK indicated caspase-dependence. A concentration of 20 μM Z-VAD-FMK was sufficient to significantly reduce apoptosis. This cell death was further substantiated by results of Western Blot studies. Cleaved caspase 3 and cleaved PARP became evident in the BV-6 treated group.

Conclusions

Taken together, the results show that BV-6 is able to induce apoptosis in KGN cells. This approach may therefore offer a promising therapeutic avenue to treat GCTs.

Electronic supplementary material

The online version of this article (10.1186/s13048-019-0549-6) contains supplementary material, which is available to authorized users.

Loss of the adaptor protein ShcA in endothelial cells protects against monocyte macrophage adhesion, LDL-oxydation, and atherosclerotic lesion formation

ShcA is an adaptor protein that binds to the cytoplasmic tail of receptor tyrosine kinases and of the Low Density Lipoprotein-related receptor 1 (LRP1), a trans-membrane receptor that protects against atherosclerosis. Here, we examined the role of endothelial ShcA in atherosclerotic lesion formation. We found that atherosclerosis progression was markedly attenuated in mice deleted for ShcA in endothelial cells, that macrophage content was reduced at the sites of lesions, and that adhesion molecules such as the intercellular adhesion molecule-1 (ICAM-1) were severely reduced. Our data indicate that transcriptional regulation of ShcA by the zinc-finger E-box-binding homeobox 1 (ZEB1) and the Hippo pathway effector YAP, promotes ICAM-1 expression independently of p-NF-κB, the primary driver of adhesion molecules expressions. In addition, ShcA suppresses endothelial Akt and nitric oxide synthase (eNOS) expressions. Thus, through down regulation of eNOS and ZEB1-mediated ICAM-1 up regulation, endothelial ShcA promotes monocyte-macrophage adhesion and atherosclerotic lesion formation. Reducing ShcA expression in endothelial cells may represent an obvious therapeutic approach to prevent atherosclerosis.

Positive effects of intermittent fasting in ischemic stroke

Intermittent fasting (IF) is a dietary protocol where energy restriction is induced by alternate periods of ad libitum feeding and fasting. Prophylactic intermittent fasting has been shown to extend lifespan and attenuate the progress and severity of age-related diseases such as cardiovascular (e.g. stroke and myocardial infarction), neurodegenerative (e.g. Alzheimer's disease and Parkinson's disease) and cancerous diseases in animal models. Stroke is the second leading cause of death, and lifestyle risk factors such as obesity and physical inactivity have been associated with elevated risks of stroke in humans. Recent studies have shown that prophylactic IF may mitigate tissue damage and neurological deficit following ischemic stroke by a mechanism(s) involving suppression of excitotoxicity, oxidative stress, inflammation and cell death pathways in animal stroke models. This review summarizes data supporting the potential hormesis mechanisms of prophylactic IF in animal models, and with a focus on findings from animal studies of prophylactic IF in stroke in our laboratory.

PERK and XBP1 differentially regulate CXCL10 and CCL2 production

Inflammation plays a key role in the pathogenesis of many retinal degenerative diseases related with photoreceptor dysfunction/degeneration. However the involvement of photoreceptor cells in inflammatory reactions is largely unknown as they are not considered as inflammatory cells. In this study, we assessed whether photoreceptor cells can produce CCL2 and CXCL10, two important players in inflammation during endoplasmic reticulum (ER) stress. After photoreceptor 661 W cells were treated with ER stress inducer thapsigargin (TG), induction of ER stress increased CXCL10 and CCL2 expression at both mRNA and protein levels, which was significantly blocked by an ER stress blocker 4-phenylbutyrate. ER stress contains three pathways: PERK, ATF6 and IRE1α. Knockdown of PERK attenuated TG-induced CXCL10 and CCL2 mRNA expression, associated with significant decreases in phosphorylation of NF-κB RelA and STAT3. In contrast to PERK, knockdown of XBP1, which is activated by IRE1α-mediated splicing, robustly enhanced TG-induced CXCL10 and CCL2 expression and phosphorylation of NF-κB RelA and STAT3. Blockade of NF-κB or STAT3 markedly diminished TG-induced CXCL10 and CCL2 expression. The specific roles of PERK and XBP1 in CXCL10 and CCL2 expression were further investigated by treating photoreceptor cells with advanced glycation end products (AGE) and high glucose (HG), two of the major contributors to diabetic complications. Similarly, AGE and HG induced CXCL10 and CCL2 expression in which PERK was a positive regulator while XBP1 was a negative regulator. These studies suggest that photoreceptors may be involved in retinal inflammation by expressing chemokines CXCL10 and CCL2. PERK and IRE1α/XBP1 in the unfolded protein response differentially regulate the expression of CXCL10 and CCL2 likely through modulation of ER stress-induced NF-κB RelA and STAT3 activation.

Genetic variation in the Mcp-1 gene promoter associated with the risk of polycystic ovary syndrome

Monocyte chemoattractant protein-1 (MCP-1) is a pivotal chemokine in the inflammatory response, which plays an important role in recruiting monocytes to sites of injury and infection. However, the exact mechanism of Mcp-1 associated with PCOS risk was unknown. In this study, we explored whether the Mcp-1 -2518G>A polymorphism increases the risk of PCOS. We performed a comparative study of -2518G>A polymorphism of the Mcp-1 gene with PCOS. In addition, luciferase reporter assay was performed to evaluate the Mcp-1 transcriptional activity. A strong association was observed between the -2518G>A polymorphism of Mcp-1 gene and PCOS (p-value = 0.016, odd ratio (OR) = 0.693). A p-value under 0.05 is considered statistically significant. The genotype and allelic frequencies were assumed to be in Hardy-Weinberg equilibrium (HWE). The luciferase assays in 2 cell lines showed that the Mcp-1 -2518G>A substitution can increase the expression of Mcp-1. MCP-1 levels in serum for PCOS group were significantly higher than those in serum for controls (p-value = 0.02). Furthermore, the patients carrying a genotype A/A had significantly increased levels of MCP-1 in serum compared with levels of the MCP-1 of the patients with genotypes G/G and G/A (p-value = 0.031). This is the first study on the genetic variation of the Mcp-1 gene and PCOS. This finding suggests that the Mcp-1 -2518G>A polymorphism is associated with PCOS risk by affecting transcriptional activity, leading to an increased expression level of Mcp-1.

Epithelial β1 integrin is required for lung branching morphogenesis and alveolarization

Integrin-dependent interactions between cells and extracellular matrix regulate lung development; however, specific roles for β1-containing integrins in individual cell types, including epithelial cells, remain incompletely understood. In this study, the functional importance of β1 integrin in lung epithelium during mouse lung development was investigated by deleting the integrin from E10.5 onwards using surfactant protein C promoter-driven Cre. These mutant mice appeared normal at birth but failed to gain weight appropriately and died by 4 months of age with severe hypoxemia. Defects in airway branching morphogenesis in association with impaired epithelial cell adhesion and migration, as well as alveolarization defects and persistent macrophage-mediated inflammation were identified. Using an inducible system to delete β1 integrin after completion of airway branching, we showed that alveolarization defects, characterized by disrupted secondary septation, abnormal alveolar epithelial cell differentiation, excessive collagen I and elastin deposition, and hypercellularity of the mesenchyme occurred independently of airway branching defects. By depleting macrophages using liposomal clodronate, we found that alveolarization defects were secondary to persistent alveolar inflammation. β1 integrin-deficient alveolar epithelial cells produced excessive monocyte chemoattractant protein 1 and reactive oxygen species, suggesting a direct role for β1 integrin in regulating alveolar homeostasis. Taken together, these studies define distinct functions of epithelial β1 integrin during both early and late lung development that affect airway branching morphogenesis, epithelial cell differentiation, alveolar septation and regulation of alveolar homeostasis.

Kolaviron improved resistance to oxidative stress and inflammation in the blood (erythrocyte, serum, and plasma) of streptozotocin-induced diabetic rats

AIMS

Bitter kola seed (Garcinia kola, family: Guttiferae) has been used as a social masticatory agent in Africa for several years and is believed to possess many useful medicinal properties. The present study evaluates the antioxidative, anti-inflammatory, and antilipidemic effects of kolaviron (an extract from the Garcinia kola seeds) in the blood of streptozotocin- (STZ) induced diabetic rats. METHODS. Diabetic rats were treated with kolaviron (100 mg/kg b·wt) orally, five times a week for a period of six weeks. Serum glucose and HBA(1C) concentrations were estimated in experimental groups. The activities of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) (in erythrocytes) as well as plasma concentration of malondialdehyde (MDA), a product of lipid peroxidation, oxygen radical absorbing capacity (ORAC) and ferric-reducing antioxidant power (FRAP) were investigated. Serum levels of proinflammatory cytokines and growth factor: interleukin- (IL-) 1, monocyte chemotactic protein-1 (MCP-1), and vascular endothelial growth factor (VEGF), respectively, were also analyzed.

RESULTS

Kolaviron treatment markedly improved antioxidant status and abated inflammatory response evidenced by reduction in the levels of proinflammatory cytokines and growth factor, lipid peroxidation product, and the restoration of activities of erythrocyte antioxidant enzymes in the blood of diabetic rats.

CONCLUSION

Kolaviron improved antioxidant status, reduced inflammation, and protected against hyperglycemic-induced oxidative damage in the blood of diabetic rats.

Constitutive and tumor necrosis factor-α-induced activation of nuclear factor-κB in adenomyosis and its inhibition by andrographolide

OBJECTIVE

To investigate the action of nuclear factor (NF)-κB in adenomyosis and evaluate the potential therapeutic effect of andrographolide on tumor necrosis factor (TNF)-α-induced expression of NF-κB-mediated genes cyclooxygease-2 (COX-2), vascular endothelial growth factor (VEGF), and tissue factor (TF) in adenomyotic stromal cells.

DESIGN

Laboratory study using human tissues.

SETTING

Academic hospital.

PATIENT(S)

Twenty-nine patients (cases) with histologically confirmed adenomyosis and 14 (controls) without adenomyosis or endometriosis.

INTERVENTION(S)

Endometrial stromal cells derived from tissue samples harvested from both cases and controls were subjected to electrophoretic mobility shift assay, and gene and protein expression analyses.

MAIN OUTCOME MEASURE(S)

The NF-κB DNA-binding activity and protein levels of NF-κB subunits p50 and p65 and the messenger RNA (mRNA) and protein levels of NF-κB-mediated genes COX-2, VEGF, and TF in cases and controls, and their changes after stimulation with TNF-α and treatment with andrographolide.

RESULT(S)

The constitutive NF-κB DNA-binding activity and protein expression levels of p50 and p65, and mRNA and protein levels of COX-2, VEGF, and TF in cases were significantly higher than that of controls. The binding activity level correlated positively with dysmenorrhea severity in cases. The TNF-α stimulation further increased the binding activity, and the mRNA and protein levels of COX-2, VEGF, and TF, but treatment with andrographolide significantly reduced them.

CONCLUSION(S)

NF-κB may be a pivotal transcription factor involved in the development of adenomyosis. Targeting NF-κB with inhibitors, like andrographolide, may hold promises of treating adenomyosis.

Tumour necrosis factor α enhances CCL2 and ICAM-1 expression in peripheral nerve microvascular endoneurial endothelial cells

Recruitment and trafficking of autoreactive leucocytes across the BNB (blood-nerve barrier) is an early pathological insult in GBS (Guillain-Barré syndrome), an aggressive autoimmune disorder of the PNS (peripheral nervous system). Whereas the aetiology and pathogenesis of GBS remain unclear, pro-inflammatory cytokines, including TNFα (tumour necrosis factor α), are reported to be elevated early in the course of GBS and may initiate nerve injury by activating the BNB. Previously, we reported that disrupting leucocyte trafficking in vivo therapeutically attenuates the course of an established animal model of GBS. Here, PNMECs (peripheral nerve microvascular endothelial cells) that form the BNB were harvested from rat sciatic nerves, immortalized by SV40 (simian virus 40) large T antigen transduction and subsequently challenged with TNFα. Relative changes in CCL2 (chemokine ligand 2) and ICAM-1 (intercellular adhesion molecule 1) expression were determined. We report that TNFα elicits marked dose- and time-dependent increases in CCL2 and ICAM-1 mRNA and protein content and promotes secretion of functional CCL2 from immortalized and primary PNMEC cultures. TNFα-mediated secretion of CCL2 promotes, in vitro, the transendothelial migration of CCR2-expressing THP-1 monocytes. Increased CCL2 and ICAM-1 expression in response to TNFα may facilitate recruitment and trafficking of autoreactive leucocytes across the BNB in autoimmune disorders, including GBS.

Manganese supplementation reduces high glucose-induced monocyte adhesion to endothelial cells and endothelial dysfunction in Zucker diabetic fatty rats

Endothelial dysfunction is a hallmark of increased vascular inflammation, dyslipidemia, and the development of atherosclerosis in diabetes. Previous studies have reported lower levels of Mn(2+) in the plasma and lymphocytes of diabetic patients and in the heart and aortic tissue of patients with atherosclerosis. This study examines the hypothesis that Mn(2+) supplementation can reduce the markers/risk factors of endothelial dysfunction in type 2 diabetes. Human umbilical vein endothelial cells (HUVECs) were cultured with or without Mn(2+) supplementation and then exposed to high glucose (HG, 25 mm) to mimic diabetic conditions. Mn(2+) supplementation caused a reduction in monocyte adhesion to HUVECs treated with HG or MCP-1. Mn(2+) also inhibited ROS levels, MCP-1 secretion, and ICAM-1 up-regulation in HUVECs treated with HG. Silencing studies using siRNA against MnSOD showed that similar results were observed in MnSOD knockdown HUVECs following Mn(2+) supplementation, suggesting that the effect of manganese on monocyte adhesion to endothelial cells is mediated by ROS and ICAM-1, but not MnSOD. To validate the relevance of our findings in vivo, Zucker diabetic fatty rats were gavaged daily with water (placebo) or MnCl2 (16 mg/kg of body weight) for 7 weeks. When compared with placebo, Mn(2+)-supplemented rats showed lower blood levels of ICAM-1 (17%, p < 0.04), cholesterol (25%, p < 0.05), and MCP-1 (28%, p = 0.25). These in vitro and in vivo studies demonstrate that Mn(2+) supplementation can down-regulate ICAM-1 expression and ROS independently of MnSOD, leading to a decrease in monocyte adhesion to endothelial cells, and therefore can lower the risk of endothelial dysfunction in diabetes.

Estrogen modulates NFκB signaling by enhancing IκBα levels and blocking p65 binding at the promoters of inflammatory genes via estrogen receptor-β

Background

NFκB signaling is critical for expression of genes involved in the vascular injury response. We have shown that estrogen (17β-estradiol, E2) inhibits expression of these genes in an estrogen receptor (ER)-dependent manner in injured rat carotid arteries and in tumor necrosis factor (TNF)-α treated rat aortic smooth muscle cells (RASMCs). This study tested whether E2 inhibits NFκB signaling in RASMCs and defined the mechanisms.

Methodology/Principal Findings

TNF-α treated RASMCs demonstrated rapid degradation of IκBα (10–30 min), followed by dramatic increases in IκBα mRNA and protein synthesis (40–60 min). E2 enhanced TNF-α induced IκBα synthesis without affecting IκBα degradation. Chromatin immunoprecipitation (ChIP) assays revealed that E2 pretreatment both enhanced TNF-α induced binding of NFκB p65 to the IκBα promoter and suppressed TNF-α induced binding of NFκB p65 to and reduced the levels of acetylated histone 3 at promoters of monocyte chemotactic protein (MCP)-1 and cytokine-induced neutrophil chemoattractant (CINC)-2β genes. ChIP analyses also demonstrated that ERβ can be recruited to the promoters of MCP-1 and CINC-2β during co-treatment with TNF-α and E2.

Conclusions

These data demonstrate that E2 inhibits inflammation in RASMCs by two distinct mechanisms: promoting new synthesis of IκBα, thus accelerating a negative feedback loop in NFκB signaling, and directly inhibiting binding of NFκB to the promoters of inflammatory genes. This first demonstration of multifaceted modulation of NFκB signaling by E2 may represent a novel mechanism by which E2 protects the vasculature against inflammatory injury.

Deficiency of Nrf2 accelerates the effector phase of arthritis and aggravates joint disease

AIMS

Although oxidative stress participates in the etiopathogenesis of rheumatoid arthritis, its importance in this inflammatory disease has not been fully elucidated. In this study, we analyzed the relevance of the transcription factor Nrf2, master regulator of redox homeostasis, in the effector phase of an animal model of rheumatoid arthritis, using the transfer of serum from K/BxN transgenic mice to Nrf2(-/-) mice.

RESULTS

Nrf2 deficiency accelerated the incidence of arthritis, and animals showed a widespread disease affecting both front and hind paws. Therefore, the inflammatory response was enhanced, with increased migration of leukocytes and joint destruction in front paws. We observed an increased production of tumor necrosis factor-α, interleukin-6, and CXCL-1 in the joint, with small changes in eicosanoid levels. Serum levels of CXCL-1 and receptor activator for nuclear factor κB ligand were enhanced and osteocalcin decreased in arthritic Nrf2(-/-) mice. The expression of cyclooxygenase-2, inducible nitric oxide synthase, and peroxynitrite in the joints was higher in Nrf2 deficiency, whereas heme oxygenase-1 was downregulated.

INNOVATION

Nrf2 may be a therapeutic target for arthritis.

CONCLUSION

Our results support a protective role of Nrf2 against joint inflammation and degeneration in arthritis.

High mobility group box 1 potentiates the pro-inflammatory effects of interleukin-1β in osteoarthritic synoviocytes

Introduction

High mobility group box 1 (HMGB1) is released by necrotic cells or secreted in response to inflammatory stimuli. Extracellular HMGB1 may act as a pro-inflammatory cytokine in rheumatoid arthritis. We have recently reported that HMGB1 is released by osteoarthritic synoviocytes after activation with interleukin-1beta (IL-1β) The present study investigated the role of HMGB1 in synovial inflammation in osteoarthritis (OA).

Methods

HMGB1 was determined in human synovium using immunohistochemistry, comparing normal to OA. OA synoviocytes were incubated with HMGB1 at 15 or 25 ng/ml in the absence or presence of IL-1β (10 ng/ml). Gene expression was analyzed by quantitative PCR and protein expression by Western Blot and ELISA. Matrix metalloproteinase (MMP) activity was studied by fluorometric procedures and nuclear factor (NF)-κB activation by transient transfection with a NF-κB-luciferase plasmid.

Results

In the normal synovium, HMGB1 was found in the synovial lining cells, sublining cells, and in the vascular wall cells. The distribution of HMGB1 in OA synovium was similar but the number of HMGB1 positive cells was higher and HMGB1 was also present in infiltrated cells. In normal synovial membrane cells, HMGB1 was found mostly in the nuclei, whereas in OA, HMGB1 was generally found mostly in the cytoplasm. In OA synoviocytes, HMGB1 alone at concentrations of 15 or 25 ng/ml did not affect the production of IL-6, IL-8, CCL2, CCL20, MMP-1 or MMP-3, but in the presence of IL-1β, a significant potentiation of protein and mRNA expression, as well as MMP activity was observed. HMGB1 also enhanced the phosphorylated ERK1/2 and p38 levels, with a lower effect on phosphorylated Akt. In contrast, JNK1/2 phosphorylation was not affected. In addition, HMGB1 at 25 ng/ml significantly potentiated NF-κB activation in the presence of IL-1β.

Conclusions

Our results indicate that HMGB1 is overexpressed in OA synovium and mostly present in extracellular form. In OA synoviocytes, HMGB1 cooperates with IL-1β to amplify the inflammatory response leading to the production of a number of cytokines, chemokines and MMPs. Our data support a pro-inflammatory role for this protein contributing to synovitis and articular destruction in OA.

Rho-kinase mediates lysophosphatidic acid-induced IL-8 and MCP-1 production via p38 and JNK pathways in human endothelial cells

Lysophosphatidic acid (LPA), an inflammatory mediator that is elevated in multiple inflammatory diseases, is a potent activator of Rho kinase (ROCK) signaling and of chemokine production in endothelial cells. In this study, LPA activated ROCK, p38, JNK and NF-kappaB pathways and induced interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) mRNA and protein expression in human endothelial cells. We mapped signaling events downstream of ROCK, driving chemokine production. In summary, MCP-1 production was partly regulated by ROCK acting upstream of p38 and JNK and mediated downstream by NF-kappaB. IL-8 production was largely driven by ROCK through p38 and JNK activation, but with no involvement of NF-kappaB.

Selective blockade of endothelial NF-kappaB pathway differentially affects systemic inflammation and multiple organ dysfunction and injury in septic mice

Endothelium has long been considered both a source and a target of systemic inflammation. However, to what extent endothelial activation contributes to systemic inflammation remains unclear. This study addresses the relative contribution of endothelial activation to systemic inflammation and multiple organ dysfunction and injury (MOD/I) in an E. coli peritonitis model of sepsis. We prevented endothelial activation using transgenic (TG) mice that conditionally overexpress a mutant I-kappaBalpha, a NF-kappaB inhibitor, selectively on endothelium. TG mice and their transgene negative littermates (WT) were injected with saline or E. coli (10(8) CFU per mouse). At 7 h after E. coli infection, markers of systemic inflammation, endothelial activation, and MOD/I were assessed. WT-E. coli mice showed significantly increased serum levels of TNF-alpha, IL-1beta, IFN-gamma, IL-6, KC, and MCP-1; tissue levels of TNF-alpha, IL-6, KC, MCP-1, ICAM-1, and VCAM-1; endothelial leakage index in heart, lungs, liver, and kidney; significantly increased serum levels of AST, ALT, BUN, and creatinine; and increased mortality. Blockade of NF-kappaB-mediated endothelial activation in TG mice had no effects on serum levels of TNF-alpha, IL-1beta, IFN-gamma, IL-6, KC, and MCP-1 (markers of systemic inflammation), and tissue levels of TNF-alpha, IL-6, KC, and MCP-1, but significantly reduced tissue levels of ICAM-1 and VCAM-1 (markers of endothelial inflammation and activation) in those four organs. TG-E. coli mice displayed reversed endothelial leakage index; reduced serum levels of AST, ALT, BUN, and creatinine; and improved survival. Our data demonstrate that endothelial NF-kappaB-driven inflammatory response contributes minimally to systemic inflammation, but plays a pivotal role in septic MOD/I, suggesting that endothelium is mainly a target rather than a source of systemic inflammation.

Suppression of nuclear factor-kappaB activity in macrophages by chylomicron remnants: modulation by the fatty acid composition of the particles

Current evidence indicates that chylomicron remnants (CMR) induce macrophage foam cell formation, an early event in atherosclerosis. Inflammation also plays a part in atherogenesis and the transcription factor nuclear factor-kappaB (NF-kappaB) has been implicated. In this study, the influence of CMR on the activity of NF-kappaB in macrophages and its modulation by the fatty acid composition of the particles were investigated using macrophages derived from the human monocyte cell line THP-1 and CMR-like particles (CRLPs). Incubation of THP-1 macrophages with CRLPs caused decreased NF-kappaB activation and downregulated the expression of phospho-p65-NF-kappaB and phospho-IkappaBalpha (pIkappaBalpha). Secretion of the inflammatory cytokines tumour necrosis factor alpha, interleukin-6 and monocyte chemoattractant protein-1, which are under NF-kappaB transcriptional control, was inhibited and mRNA expression for cyclooxygenase-2, an NF-kappaB target gene, was reduced. CRLPs enriched in polyunsaturated fatty acids compared with saturated or monounsaturated fatty acids had a markedly greater inhibitory effect on NF-kappaB binding to DNA and the expression of phospho-p65-NF-kappaB and pIkappaB. Lipid loading of macrophages with CRLPs enriched in polyunsaturated fatty acids compared with monounsaturated fatty acids or saturated fatty acids also increased the subsequent rate of cholesterol efflux, an effect which may be linked to the inhibition of NF-kappaB activity. These findings demonstrate that CMR suppress NF-kappaB activity in macrophages, and that this effect is modulated by their fatty acid composition. This downregulation of inflammatory processes in macrophages may represent a protective effect of CMR which is enhanced by dietary polyunsaturated fatty acids.

Neuroprotective and antiinflammatory properties of a novel demethylated curcuminoid

A demethylated derivative of curcumin (DC; 67.8% bisdemethylcurcumin, 20.7% demethylmonodemethoxycurcumin, 5.86% bisdemethoxycurcumin, 2.58% demethylcurcumin) was prepared by using a 95% extract of curcumin (C(95); 72.2% curcumin, 18.8% monodemethoxycurcumin, 4.5% bisdemethoxycurcumin). DC increased glutathione and reduced reactive oxygen species (ROS) in HT4 neuronal cells. In a model of glutamate-induced death of HT4, DC was more effective than C(95) in neuroprotection. The protective effects of DC were retained even when DC was withdrawn from culture media after pretreatment. DC treatment, unlike an equal dose of C(95), completely spared glutamate-induced loss of cellular GSH. Both DC and C(95) prevented glutamate-induced elevation of cellular ROS but failed to attenuate glutamate-induced elevation of intracellular calcium. In human microvascular endothelial cells (HMECs) challenged with TNF-alpha, GeneChip analysis revealed that only a subcluster of 23 TNF-alpha-inducible genes were uniquely sensitive to C(95). In sharp contrast, 1,065 TNF-alpha-inducible genes were sensitive to DC but not to C(95), suggesting that DC was more effective in antagonizing the effects of TNF-alpha on HMECs. Functional analysis identified that the genes uniquely sensitive to DC belonged in four functional categories: cytokine-receptor interaction, focal adhesion, cell adhesion, and apoptosis. Real-time PCR as well as ELISA studies demonstrated that TNF-alpha-inducible CXCL10 and CXCL11 expression was sensitive to DC but not to C(95). Flow-cytometry studies recognized ICAM-1 and VCAM-1 as TNF-alpha-inducible adhesion molecules that were uniquely sensitive to DC. Taken together, DC exhibited promising neuroprotective and antiinflammatory properties that must be characterized in vivo.

Curcumin supplementation lowers TNF-alpha, IL-6, IL-8, and MCP-1 secretion in high glucose-treated cultured monocytes and blood levels of TNF-alpha, IL-6, MCP-1, glucose, and glycosylated hemoglobin in diabetic rats

This study examined the hypothesis that curcumin supplementation decreases blood levels of IL-6, MCP-1, TNF-alpha, hyperglycemia, and oxidative stress by using a cell-culture model and a diabetic rat model. U937 monocytes were cultured with control (7 mM) and high glucose (35 mM) in the absence or presence of curcumin (0.01-1 microM) at 37 degrees C for 24 h. Diabetes was induced in Sprague-Dawley rats by injection of streptozotocin (STZ) (i.p., 65 mg/kg BW). Control buffer, olive oil, or curcumin (100 mg/kg BW) supplementation was administered by gavage daily for 7 weeks. Blood was collected by heart puncture with light anesthesia. Results show that the effect of high glucose on lipid peroxidation, IL-6, IL-8, MCP-1, and TNF-alpha secretion was inhibited by curcumin in cultured monocytes. In the rat model, diabetes caused a significant increase in blood levels of IL-6, MCP-1, TNF-alpha, glucose, HbA(1), and oxidative stress, which was significantly decreased in curcumin-supplemented rats. Thus, curcumin can decrease markers of vascular inflammation and oxidative stress levels in both a cell-culture model and in the blood of diabetic rats. This suggests that curcumin supplementation can reduce glycemia and the risk of vascular inflammation in diabetes.