Curcumin ameliorates TNF-α-induced ICAM-1 expression and subsequent THP-1 adhesiveness via the induction of heme oxygenase-1 in the HaCaT cells

Adhesion molecules such as ICAM-1 are important in the infiltration of leukocytes into the site of inflammation. In this study, we investigated the inhibitory effects of curcumin on ICAM-1 expression and monocyte adhesiveness as well as its underlying action mechanism in the TNF-α-stimulated keratinocytes. Curcumin induced expression of heme oxygenase-1 (HO-1) in the human keratinocyte cell line HaCaT. In addition, curcumin induced Nrf2 activation in dose- and time-dependent manners in the HaCaT cells. Curcumin suppressed TNF-α- induced ICAM-1 expression and subsequent monocyte adhesion, which were reversed by the addition of tin protoporphyrin IX (SnPP), a specific inhibitor of HO-1, or HO-1 knockdown using siRNA. Furthermore, Nrf2 knockdown using siRNA reversed the inhibitory effect of curcumin on the TNF-α-induced ICAM-1 expression and adhesion of monocytes to keratinocytes. These results suggest that curcumin may exert its anti-inflammatory activity by suppressing the TNF-α-induced ICAM-1 expression and subsequent monocyte adhesion via expression of HO-1 in the keratinocytes. [BMB Reports 2013;46(8): 410-415]     

Evidence that TNF-β (lymphotoxin α) can activate the inflammatory environment in human chondrocytes

Introduction

Inflammatory cytokines play a key role in the pathogenesis of joint diseases such as rheumatoid arthritis (RA). Current therapies target mainly tumor necrosis factor α (TNF-α) as this has proven benefits. However, a large number of patients do not respond to or become resistant to anti-TNF-α therapy. While the role of TNF-α in RA is quite evident, the role of TNF-β, also called lymphotoxin-α (LT-α), is unclear. In this study we investigated whether TNF-β and its receptor play a role in chondrocytes in the inflammatory environment.

Methods

An in vitro model of primary human chondrocytes was used to study TNF-β-mediated inflammatory signaling.

Results

Cytokine-induced inflammation enhances TNF-β and TNF-β-receptor expression in primary human chondrocytes accompanied by the up-regulation of inflammatory (cyclooxygenase-2), matrix degrading (matrix metalloproteinase-9 and -13) and apoptotic (p53, cleaved caspase-3) signaling pathways, all known to be regulated by NF-κB. In contrast, anti-TNF-β, similar to the natural NF-κB inhibitor (curcumin, diferuloylmethane) or the knockdown of NF-κB by using antisense oligonucleotides (ASO), suppressed IL-1β-induced NF-κB activation and its translocation to the nucleus, and abolished the pro-inflammatory and apoptotic effects of IL-1β. This highlights, at least in part, the crucial role of NF-κB in TNF-β-induced-inflammation in cartilage, similar to that expected for TNF-α. Finally, the adhesiveness between TNF-β-expressing T-lymphocytes and the responding chondrocytes was significantly enhanced through a TNF-β-induced inflammatory microenvironment.

Conclusions

These results suggest for the first time that TNF-β is involved in microenvironment inflammation in chondrocytes during RA parallel to TNF-α, resulting in the up-regulation of NF-κB signaling and activation of pro-inflammatory activity.     

Hypoxia-Inducible Factor-2α Is an Essential Catabolic Regulator of Inflammatory Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disorder that manifests as chronic inflammation and joint tissue destruction. However, the etiology and pathogenesis of RA have not been fully elucidated. Here, we explored the role of the hypoxia-inducible factors (HIFs), HIF-1α (encoded by HIF1A) and HIF-2α (encoded by EPAS1). HIF-2α was markedly up-regulated in the intimal lining of RA synovium, whereas HIF-1α was detected in a few cells in the sublining and deep layer of RA synovium. Overexpression of HIF-2α in joint tissues caused an RA-like phenotype, whereas HIF-1α did not affect joint architecture. Moreover, a HIF-2α deficiency in mice blunted the development of experimental RA. HIF-2α was expressed mainly in fibroblast-like synoviocytes (FLS) of RA synovium and regulated their proliferation, expression of RANKL (receptor activator of nuclear factor–κB ligand) and various catabolic factors, and osteoclastogenic potential. Moreover, HIF-2α–dependent up-regulation of interleukin (IL)-6 in FLS stimulated differentiation of T_H17 cells—crucial effectors of RA pathogenesis. Additionally, in the absence of IL-6 (Il6 ^−/− mice), overexpression of HIF-2α in joint tissues did not cause an RA phenotype. Thus, our results collectively suggest that HIF-2α plays a pivotal role in the pathogenesis of RA by regulating FLS functions, independent of HIF-1α.     

Additive Regulation of Adiponectin Expression by the Mediterranean Diet Olive Oil Components Oleic Acid and Hydroxytyrosol in Human Adipocytes

Adiponectin, an adipocyte-derived insulin-sensitizing and anti-inflammatory hormone, is suppressed in obesity through mechanisms involving chronic inflammation and oxidative stress. Olive oil consumption is associated with beneficial cardiometabolic actions, with possible contributions from the antioxidant phenol hydroxytyrosol (HT) and the monounsaturated fatty acid oleic acid (OA, 18:1n-9 cis), both possessing anti-inflammatory and vasculo-protective properties. We determined the effects of HT and OA, alone and in combination, on adiponectin expression in human and murine adipocytes under pro-inflammatory conditions induced by the cytokine tumor necrosis factor(TNF)-α. We used human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes and murine 3T3-L1 adipocytes as cell model systems, and pretreated them with 1-100 μmol/L OA, 0.1-20 μmol/L HT or OA plus HT combination before stimulation with 10 ng/mL TNF-α. OA or HT significantly (P<0.05) prevented TNF-α-induced suppression of total adiponectin secretion (by 42% compared with TNF-α alone) as well as mRNA levels (by 30% compared with TNF-α alone). HT and OA also prevented—by 35%—TNF-α-induced downregulation of peroxisome proliferator-activated receptor PPARγ. Co-treatment with HT and OA restored adiponectin and PPARγ expression in an additive manner compared with single treatments. Exploring the activation of JNK, which is crucial for both adiponectin and PPARγ suppression by TNF-α, we found that HT and OA additively attenuated TNF-α-stimulated JNK phosphorylation (up to 55% inhibition). In conclusion, the virgin olive oil components OA and HT, at nutritionally relevant concentrations, have additive effects in preventing adiponectin downregulation in inflamed adipocytes through an attenuation of JNK-mediated PPARγ suppression.     

Cyr61 is involved in neutrophil infiltration in joints by inducing IL-8 production by fibroblast-like synoviocytes in rheumatoid arthritis

Introduction

It is well known that neutrophils play very important roles in the development of rheumatoid arthritis (RA) and interleukin (IL)-8 is a critical chemokine in promoting neutrophil migration. We previously showed that increased production of Cyr61 by fibroblast-like synoviocytes (FLS) in RA promotes FLS proliferation and Th17 cell differentiation, thus Cyr61 is a pro-inflammatory factor in RA pathogenesis. In this study, we explored the role of Cyr61 in neutrophil migration to the joints of RA patients.

Methods

RA FLS were treated with Cyr61 and IL-8 expression was analyzed by real-time PCR and ELISA. The migration of neutrophils recruited by the culture supernatants was determined by the use of a chemotaxis assay. Mice with collagen-induced arthritis (CIA) were treated with anti-Cyr61 monoclonal antibodies (mAb), or IgG1 as a control. Arthritis severity was determined by visual examination of the paws and joint destruction was determined by hematoxylin-eosin (H&E) staining. Signal transduction pathways in Cyr61-induced IL-8 production were investigated by real-time PCR, western blotting, confocal microscopy, luciferase reporter assay or chromatin immunoprecipitation (ChIP) assay.

Results

We found that Cyr61 induced IL-8 production by RA FLS in an IL-1β and TNF-α independent pathway. Moreover, we identified that Cyr61-induced IL-8-mediated neutrophil migration in vitro. Using a CIA animal model, we found that treatment with anti-Cyr61 mAb led to a reduction in MIP-2 (a counterpart of human IL-8) expression and decrease in neutrophil infiltration, which is consistent with an attenuation of inflammation in vivo. Mechanistically, we showed that Cyr61 induced IL-8 production in FLS via AKT, JNK and ERK1/2-dependent AP-1, C/EBPβ and NF-κB signaling pathways.

Conclusions

Our results here reveal a novel role of Cyr61 in the pathogenesis of RA. It promotes neutrophil infiltration via up-regulation of IL-8 production in FLS. Taken together with our previous work, this study provides further evidence that Cyr61 plays a key role in the vicious cycle formed by the interaction between infiltrating neutrophils, proliferated FLS and activated Th17 cells in the development of RA.     

TNF-α Mediates PKCδ/JNK1/2/c-Jun-Dependent Monocyte Adhesion via ICAM-1 Induction in Human Retinal Pigment Epithelial Cells

Retinal inflammatory diseases induced by cytokines, such as tumor necrosis factor-α (TNF-α) are associated with an up-regulation of intercellular adhesion molecule-1 (ICAM-1) in the retinal pigment epithelial cells (RPECs). Retinal pigment epithelium (RPE) is a monolayer of epithelial cells that forms the outer blood-retinal barrier in the posterior segment of the eye, and is also implicated in the pathology of, such as neovascularization in age-related macular degeneration (AMD). However, the detailed mechanisms of TNF-α-induced ICAM-1 expression are largely unclear in human RPECs. We demonstrated that in RPECs, TNF-α could induce ICAM-1 protein and mRNA expression and promoter activity, and monocyte adhesion. TNF-α-mediated responses were attenuated by pretreatment with the inhibitor of PKCs (Ro318220), PKCδ (Rottlerin), MEK1/2 (U0126), JNK1/2 (SP600125), or AP-1 (Tanshinone IIA) and transfection with siRNA of TNFR1, TRAF2, JNK2, p42, or c-Jun. We showed that TNF-α could stimulate the TNFR1 and TRAF2 complex formation. TNF-α-stimulated JNK1/2 was also reduced by Rottlerin or SP600125. However, Rottlerin had no effect on TNF-α-induced p42/p44 MAPK phosphorylation. We observed that TNF-α induced c-Jun phosphorylation which was inhibited by Rottlerin or SP600125. On the other hand, TNF-α-stimulated ICAM-1 promoter activity was prominently lost in RPECs transfected with the point-mutated AP-1 ICAM-1 promoter plasmid. These results suggest that TNF-α-induced ICAM-1 expression and monocyte adhesion is mediated through a TNFR1/TRAF2/PKCδ/JNK1/2/c-Jun pathway in RPECs. These findings concerning TNF-α-induced ICAM-1 expression in RPECs imply that TNF-α might play an important role in ocular inflammation and diseases.     

Less Frequent and Less Severe Flu-Like Syndrome in Interferon Beta-1a Treated Multiple Sclerosis Patients with at Least One Allele Bearing the G>C Polymorphism at Position -174 of the IL-6 Promoter Gene

One of the most common adverse event of interferon beta (IFNβ) therapy for multiple sclerosis is flu-like syndrome (FLS), which has been reportedly related to increased levels of cytokines such as interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-α). Average cytokine levels can be affected by single nucleotide polymorphism in the gene promoter regions. To investigate whether IL-6 -174 G>C and TNF-α -376 G>A polymorphisms could be correlated to the incidence of FLS, and whether an anti-inflammatory/antipyretic therapy may influence FLS development, a prospective observational study was performed in 190 treatment naïve, multiple sclerosis patients who started IM IFNβ-1a 30mcg once weekly. The identification of IL-6 -174 G>C and TNF-α -376 G>A polymorphisms was achieved by performing an amplification-refractory mutation system. Serum IL-6 levels were measured using enzyme-linked immunosorbent assay in blood samples taken before therapy and then after the first and last IFNβ-1a injection of the follow-up. FLS-related symptoms were recorded by patients once per week during the first 12 weeks of therapy into a self-reported diary. We found that patients carrying at least one copy of the C allele at position -174 in the promoter of IL-6 gene produced lower levels of IL-6 and were less prone to develop FLS, which was also less severe. On the contrary, the polymorphism of TNF-α had no effect on FLS. Patients taking the first dose of anti-inflammatory/antipyretic therapy in the peri-injection period (within 1 hour) experienced a reduced FLS severity. In conclusion, the study of IL-6 -174 G>C polymorphism would allow the identification of patients lacking the C nucleotide on both alleles who are at risk of a more severe FLS, and may be addressed to a timely and stronger anti-inflammatory/antipyretic therapy for a more effective FLS prevention.     

Curcumin Inhibits Imiquimod-Induced Psoriasis-Like Inflammation by Inhibiting IL-1beta and IL-6 Production in Mice

Curcumin, a selective phosphorylase kinase inhibitor, is a naturally occurring phytochemical present in turmeric. Curcumin has been confirmed to have anti-inflammatory properties in addition to the ability to decrease the expression of pro-inflammatory cytokines in keratinocytes. The interleukin-23 (IL-23)/IL-17A cytokine axis plays a critical role in the pathogenesis of psoriasis. Here, we report that topical use of a curcumin gel formulation strongly inhibited imiquimod (IMQ)-induced psoriasis-like inflammation, the development of which was based on the IL-23/IL-17A axis. IMQ-induced epidermal hyperplasia and inflammation in BALB/c mouse ear was significantly inhibited following curcumin treatment. Real-time PCR showed that mRNA levels of IL-17A, IL-17F, IL-22, IL-1β, IL-6 and TNF-α cytokines were decreased significantly by curcumin in ear skin, an effect similar to that of clobetasol. In addition, we found that curcumin may enhance the proliferation of epidermis γδ T cells but inhibit dermal γδ T cell proliferation. We inferred that curcumin was capable of impacting the IL-23/IL-17A axis by inhibiting IL-1β/IL-6 and then indirectly down-regulating IL-17A/IL-22 production. In conclusion, curcumin can relieve the IMQ-induced psoriasis-like inflammation in a mouse model, similar to the effects of clobetasol. Therefore, we have every reason to expect that curcumin will be used in the treatment of psoriasis in the future.     

Demethylation of MicroRNA-124a Genes Attenuated Proliferation of Rheumatoid Arthritis Derived Fibroblast-Like Synoviocytes and Synthesis of Tumor Necrosis Factor-α

ObjectiveTo examine the impact of 5-Aza-2ʹ-deoxycytidine (5-AzadC) on methylation status of miR-124a genes in rheumatoid arthritis (RA) associated fibroblast-like synoviocytes (FLS) and its effect on RA-FLS proliferation and TNF-α expression.ResultsAfter 5-AzadC treatment, the expression of miR-124a was significantly increased compared with the control group (1.545 ± 0.189 vs 0.836 ± 0.166, p = 0.001). On the other hand, 5-AzadC significantly reduced IL-1β-mediated cell proliferation by nearly 2.5 fold (p = 0.006). Also, the level of TNF-α secreted from the cells treated with IL-1β plus 5-AzadC was considerably less than that from the cells treated with IL-1β alone (324.99 ± 22.73 ng/L vs 387.91 ± 58.51 ng/L, p = 0.022). After transfection with miR-124a inhibitor in RA-FLS treated with IL-1β plus 5-AzadC, the cell proliferation was increased by 18.2% and the TNF-α expression was increased by 19.0% (p = 0.001 and 0.011, respectively).ConclusionMethylation of miR-124a genes contributed to IL-1β-mediated RA-FLS proliferation and TNF-α expression.     

Thy-1 Attenuates TNF-α-Activated Gene Expression in Mouse Embryonic Fibroblasts via Src Family Kinase

Heterogeneous surface expression of Thy-1 in fibroblasts modulates inflammation and may thereby modulate injury and repair. As a paradigm, patients with idiopathic pulmonary fibrosis, a disease with pathologic features of chronic inflammation, demonstrate an absence of Thy-1 immunoreactivity within areas of fibrotic activity (fibroblast foci) in contrast to the predominant Thy-1 expressing fibroblasts in the normal lung. Likewise, Thy-1 deficient mice display more severe lung fibrosis in response to an inflammatory injury than wildtype littermates. We investigated the role of Thy-1 in the response of fibroblasts to the pro-inflammatory cytokine TNF-α. Our study demonstrates distinct profiles of TNF-α-activated gene expression in Thy-1 positive (Thy-1+) and negative (Thy-1−) subsets of mouse embryonic fibroblasts (MEF). TNF-α induced a robust activation of MMP-9, ICAM-1, and the IL-8 promoter driven reporter in Thy-1− MEFs, in contrast to only a modest increase in Thy-1+ counterparts. Consistently, ectopic expression of Thy-1 in Thy-1− MEFs significantly attenuated TNF-α-activated gene expression. Mechanistically, TNF-α activated Src family kinase (SFK) only in Thy-1− MEFs. Blockade of SFK activation abrogated TNF-α-activated gene expression in Thy-1− MEFs, whereas restoration of SFK activation rescued the TNF-α response in Thy-1+ MEFs. Our findings suggest that Thy-1 down-regulates TNF-α-activated gene expression via interfering with SFK- and NF-κB-mediated transactivation. The current study provides a novel mechanistic insight to the distinct roles of fibroblast Thy-1 subsets in inflammation.     

SKLB023 Blocks Joint Inflammation and Cartilage Destruction in Arthritis Models via Suppression of Nuclear Factor-Kappa B Activation in Macrophage

Rheumatoid arthritis (RA) is the most common arthritis and is mainly characterized by symmetric polyarticular joint disorders. Our previous study demonstrated a novel small molecule compound (Z)-N-(3-Chlorophenyl)-2-(4-((2,4-dioxothiazolidin-5-ylidene) methyl) phenoxy) acet-amide (SKLB023) showed potently anti-arthritic effects in a rat arthritis model, however, the underlying mechanisms for this are largely unknown. Both NF-κB and macrophages were reported to play important roles in the pathologic processes of RA. The purposes of this study were to indicate whether NF-κB and macrophages contributed to anti-arthritic effects of SKLB023 in two experimental arthritis models. Our results showed that SKLB023 could significantly improve joint inflammation and cartilage destruction both in adjuvant induced arthritis (AIA) and collagen-induced arthritis (CIA) models. We further found that the binding activation of NF-κB to DNA in joint tissues and RAW264.7 macrophages were suppressed by SKLB023. SKLB023 also inhibited the NF-κB activity in peritoneal macrophages by luciferase assay. Furthermore, the number of macrophages in synovial tissues was decreased after the treatment of different doses of SKLB023. The levels of TNF-α, IL-1β, and IL-6 in plasma, and the levels of TNF-α, NO, and IL-1β in peritoneal macrophages were down-regulated by SKLB023. Finally, SKLB023 attenuated the expression of iNOS and COX-2 in vivo and suppressed the phosphorylations of components of the mitogen-activated protein kinases (MAPKs). These observations identify a novel function for SKLB023 as an inhibitor of NF-κB in macrophages of RA, highlighting that SKLB023 was a potential therapeutic strategy for RA.     

Preclinical Potency and Biodistribution Studies of an AAV 5 Vector Expressing Human Interferon-β (ART-I02) for Local Treatment of Patients with Rheumatoid Arthritis

Introduction

Proof of concept for local gene therapy for the treatment of arthritis with immunomodulatory cytokine interferon beta (IFN-β) has shown promising results in animal models of rheumatoid arthritis (RA). For the treatment of RA patients, we engineered a recombinant adeno-associated serotype 5 vector (rAAV5) encoding human (h)IFN-β under control of a nuclear factor κB promoter (ART-I02).

Methods

The potency of ART-I02 in vitro as well as biodistribution in vivo in arthritic animals was evaluated to characterize the vector prior to clinical application. ART-I02 expression and bioactivity after transduction was evaluated in fibroblast-like synoviocytes (FLS) from different species. Biodistribution of the vector after local injection was assessed in a rat adjuvant arthritis model through qPCR analysis of vector DNA. In vivo imaging was used to investigate transgene expression and kinetics in a mouse collagen induced arthritis model.

Results

Transduction of RA FLS in vitro with ART-I02 resulted in high expression levels of bioactive hIFN-β. Transduction of FLS from rhesus monkeys, rodents and rabbits with ART-I02 showed high transgene expression, and hIFN-β proved bioactive in FLS from rhesus monkeys. Transgene expression and bioactivity in RA FLS were unaltered in the presence of methotrexate. In vivo, vector biodistribution analysis in rats after intra-articular injection of ART-I02 demonstrated that the majority of vector DNA remained in the joint (>93%). In vivo imaging in mice confirmed local expression of rAAV5 in the knee joint region and demonstrated rapid detectable and sustained expression up until 7 weeks.

Conclusions

These data show that hIFN-β produced by RA FLS transduced with ART-I02 is bioactive and that intra-articular delivery of rAAV5 drives expression of a therapeutic transgene in the joint, with only limited biodistribution of vector DNA to other tissues, supporting progress towards a phase 1 clinical trial for the local treatment of arthritis in patients with RA.     

Membrane Type 1–Matrix Metalloproteinase/Akt Signaling Axis Modulates TNF-α-Induced Procoagulant Activity and Apoptosis in Endothelial Cells

Membrane type 1–matrix metalloproteinase (MT1-MMP) functions as a signaling molecule in addition to a proteolytic enzyme. Our hypothesis was that MT1-MMP cooperates with protein kinase B (Akt) in tumor necrosis factor (TNF)-α-induced signaling pathways of vascular responses, including tissue factor (TF) procoagulant activity and endothelial apoptosis, in cultured human aortic endothelial cells (ECs). TNF-α (10 ng/mL) induced a decrease in Akt phosphorylation within 60 minutes in ECs. A chemical inhibitor of MMP, TIMP-2 and selective small interfering RNA (siRNA)-mediated suppression of MT1-MMP reversed TNF-α-triggered transient decrease of Akt phosphorylation within 60 minutes, suggesting that MT1-MMP may be a key regulator of Akt phosphorylation in TNF-α-stimulated ECs. In the downstream events, TNF-α increased TF antigen and activity, and suppressed the expression of thrombomodulin (TM) antigen. Inhibition of Akt markedly enhanced TNF-α-induced expression of TF antigen and activity, and further reduced the expression of TM antigen. Silencing of MT1-MMP by siRNA also reversed the changed expression of TF and TM induced by TNF-α. Moreover, TNF-α induced apoptosis of ECs through Akt- and forkhead box protein O1 (FoxO1)-dependent signaling pathway and nuclear factor-kB (NF-kB) activation. Knockdown of MT1-MMP by siRNA reversed apoptosis of ECs by inhibiting TNF-α-induced Akt-dependent regulation of FoxO1 in TNF-α-stimulated ECs. Immunoprecipitation demonstrated that TNF-α induced the changes in the associations between the cytoplasmic fraction of MT1-MMP and Akt in ECs. In conclusion, we show new evidence that MT1-MMP/Akt signaling axis is a key modifier for TNF-α-induced signaling pathways for modulation of procoagulant activity and apoptosis of ECs.     

Curcumin Protects Microglia and Primary Rat Cortical Neurons against HIV-1 gp120-Mediated Inflammation and Apoptosis

Curcumin is a molecule found in turmeric root that has anti-inflammatory, antioxidant, and anti-tumor properties and has been widely used as both an herbal drug and a food additive to treat or prevent neurodegenerative diseases. To explore whether curcumin is able to ameliorate HIV-1-associated neurotoxicity, we treated a murine microglial cell line (N9) and primary rat cortical neurons with curcumin in the presence or absence of neurotoxic HIV-1 gp120 (V3 loop) protein. We found that HIV-1 gp120 profoundly induced N9 cells to produce reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1). HIV-1 gp120 also induced apoptosis of primary rat cortical neurons. Curcumin exerted a powerful inhibitory effect against HIV-1 gp120-induced neuronal damage, reducing the production of ROS, TNF-α and MCP-1 by N9 cells and inhibiting apoptosis of primary rat cortical neurons. Curcumin may exert its biological activities through inhibition of the delayed rectification and transient outward potassium (K⁺) current, as curcumin effectively reduced HIV-1 gp120-mediated elevation of the delayed rectification and transient outward K⁺ channel current in neurons. We conclude that HIV-1 gp120 increases ROS, TNF-α and MCP-1 production in microglia, and induces cortical neuron apoptosis by affecting the delayed rectification and transient outward K⁺ channel current. Curcumin reduces production of ROS and inflammatory mediators in HIV-1-gp120-stimulated microglia, and protects cortical neurons against HIV-1-mediated apoptosis, most likely through inhibition of HIV-1 gp120-induced elevation of the delayed rectification and transient outward K⁺ current.