Is NF-kappaB a useful therapeutic target in rheumatoid arthritis?

Piperine suppresses inflammatory fibroblast-like synoviocytes derived from rheumatoid arthritis patients Via NF-κB inhibition

Rheumatoid Arthritis (RA) is a common autoimmune disease recognized by hyperplasia of synoviocytes and chronic joint inflammation. Activation of fibroblast-like synoviocytes (FLSs) is one of the main features of RA which can trigger inflammation leading to articular cartilage and joint destruction. Aberrant activation of NF-κB signaling cascade was found to be responsible for the high proliferation and defective apoptosis of FLSs and subsequent inflammation in RA. Piperine is a principal constituent of piper species frequently used as antitumor and anti-inflammatory natural compound. In this study we aimed to assess the anti-inflammatory effect of piperine on RA-FLS through NF-κB inhibition. FLSs were isolated from 68 RA patients and 30 healthy controls and were exposed to piperine. The main assays were MTT assay, flow cytometric analysis, PI staining, reverse transcription-PCR (RT-PCR), and ELISA. Results showed that piperine can induce the apoptosis and reduce the proliferation of RA-FLSs in vitro. Moreover, piperine directly reduced the phosphorylation of NF-kB and the expression of NF-κB target genes related to RA-FLSs proliferation (c-Myc and Cycline D1), apoptosis inhibition (Bcl2 and Bcl-xl) and inflammation (COX2, IL-1β, TNF-α,IL-6, CCL5 and CXCL10) while increasing the expression of apoptosis related ones (Bax) in vitro. Piperine also reduced the protein levels of cytokines and chemokines secreted by FLSs as a result of NF-κB inhibition. In conclusion, our results provide evidence for the anti-inflammatory capacity of piperine through inhibition of NF-κB pathway in FLSs proposing this compound as a suitable alternative for chemical treatment of RA.

Dexmedetomidine inhibits the invasion, migration, and inflammation of rheumatoid arthritis fibroblast-like synoviocytes by reducing the expression of NLRC5

Rheumatoid arthritis (RA) is a chronic, autoimmune disease characterized by inflammatory synovitis, but its pathogenesis remains unclear. NLRC5 is a newly discovered member of the NLR family that is effective in regulating autoimmunity, inflammatory responses, and cell death processes. Dexmedetomidine (DEX) has been reported to have a variety of pharmacological effects, including anti-inflammatory and analgesic effects. However, the role of DEX in RA has not been explored. In adjuvant-induced arthritis (AA) rat models, DEX (10 μg/kg and 20 μg/kg) reduced the pathological score, the arthritis score, paw swelling volume, and the serum levels of IL-1β, IL-6, IL-17A, and TNF-α. Moreover, by using Western blot and real-time quantitative PCR (RT-qPCR), it was demonstrated that DEX can inhibit the expression of IL-1β, IL-6, MMP-3, MMP-9 and P-P65 in the synovial tissue of AA rats. In human rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs), DEX (250 nM and 500 nM) was found to inhibit the expression of IL-1β, IL-6, MMP-3, MMP-9, and P-P65 following stimulation with TNF-α. Moreover, DEX can inhibit the invasion and migration of RA-FLSs stimulated by TNF-α. Finally, the expression of NLRC5 in RA-FLSs and AA rat models was also reduced by DEX. After silencing NLRC5 in RA-FLSs, the expression of IL-1β, IL-6, MMP-3, MMP-9, and P-P65, as well as the invasion and migration of cells, were significantly reduced. These results indicate that DEX inhibits the invasion, migration, and inflammation of RA-FLSs by reducing the expression of NLRC5 and inhibiting the NF-κB activation.

Dissecting the Role of NF-κb Protein Family and Its Regulators in Rheumatoid Arthritis Using Weighted Gene Co-Expression Network

Rheumatoid arthritis (RA) is a chronic synovial autoinflammatory disease that destructs the cartilage and bone, leading to disability. The functional regulation of major immunity-related pathways like nuclear factor kappa B (NF-κB), which is involved in the chronic inflammatory reactions underlying the development of RA, remains to be explored. Therefore, this study has adopted statistical and knowledge-based systemic investigations (like gene correlation, semantic similarity, and topological parameters based on graph theory) to study the gene expression status of NF-κB protein family (NK^PF) and its regulators in synovial tissues to trace the molecular pathways through which these regulators contribute to RA. A complex protein–protein interaction map (PPIM) of 2,742 genes and 37,032 interactions was constructed from differentially expressed genes (p ≤ 0.05). PPIM was further decomposed into a Regulator Allied Protein Interaction Network (RA^PIN) based on the interaction between genes (5 NK^PF, 31 seeds, 131 hubs, and 652 bottlenecks). Pathway network analysis has shown the RA-specific disturbances in the functional connectivity between seed genes (RIPK1, ATG7, TLR4, TNFRSF1A, KPNA1, CFLAR, SNW1, FOSB, PARVA, CX3CL1, and TRPC6) and NK^PF members (RELA, RELB, NFKB2, and REL). Interestingly, these genes are known for their involvement in inflammation and immune system (signaling by interleukins, cytokine signaling in immune system, NOD-like receptor signaling, MAPK signaling, Toll-like receptor signaling, and TNF signaling) pathways connected to RA. This study, for the first time, reports that SNW1, along with other NK regulatory genes, plays an important role in RA pathogenesis and might act as potential biomarker for RA. Additionally, these genes might play important roles in RA pathogenesis, as well as facilitate the development of effective targeted therapies. Our integrative data analysis and network-based methods could accelerate the identification of novel drug targets for RA from high-throughput genomic data.

miR-410-3p Suppresses Cytokine Release from Fibroblast-Like Synoviocytes by Regulating NF-κB Signaling in Rheumatoid Arthritis

miR-410-3p acts as an oncogene or a tumor suppressor in some malignancies. However, its role in rheumatoid arthritis (RA) is unknown. The study was conducted to investigate the effect of miR-410-3p on the pathogenesis of RA. Real-time RT-PCR was used to determine the mRNA levels of miR-410-3p in synovial tissues and fibroblast-like synoviocytes (FLSs). An ELISA was performed to examine the production levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and matrix metalloproteinase (MMP)-9. Western blotting was conducted to determine the protein levels of IκB-α, p-IκBα, p65, and p-p65. Nuclear factor (NF)-κB activation and nuclear translocation assays were performed to confirm the activation of NF-κB. We found that the expression level of miR-410-3p was downregulated in synovial tissues and FLSs from RA. Overexpression of miR-410-3p significantly reduced the secretion of TNF-α, IL-1β, IL-6, and MMP-9 in human RA fibroblast-like synoviocytes (HFLS-RA); whereas miR-410-3p inhibition increased the expression levels of these cytokines. Furthermore, miR-410-3p suppresses the activation of NF-κB signaling pathway. Moreover, NF-κB inhibitor restored the elevation of TNF-α, IL-1β, IL-6, and MMP-9 induced by miR-410-3p inhibition. Our results demonstrate that miR-410-3p acts an inflammatory suppressor in the pathogenesis of RA by regulating the NF-κB signaling pathway. These data suggest a novel function of miR-410-3p and provide insight into the complex mechanisms involved in RA.

The many facets of macrophages in rheumatoid arthritis

Macrophages are central to the pathophysiology of rheumatoid arthritis (RA). They constitute the main source of pro-inflammatory cytokines and chemokines such as TNF and IL-1β, they activate a wide range of immune and non-immune cells, and they secrete diverse tissue degrading enzymes driving chronic pro-inflammatory, tissue destructive and pain responses in RA. However, they can also produce anti-inflammatory cytokines such as IL-10, secrete inhibitors of tissue degrading enzymes and promote immunoregulatory and protective responses, suggesting the existence of macrophages with distinct and diverse functional activities. Although the underlying basis of this phenomenon has remained obscure for years, emerging evidence has now provided insight into the mechanisms and molecular processes involved. Here, we review current knowledge on the biology of macrophages in RA, and highlight recent literature on the heterogeneity, origins and ontogeny of macrophages as part of the mononuclear phagocyte system. We also discuss their plasticity in the context of the M1/M2 paradigm, and the emerging theme of metabolic rewiring as a major mechanism for programming macrophage functions and pro-inflammatory activities. This sheds light into the many facets of macrophages in RA, their molecular regulation and their translational potential for developing novel protective and therapeutic strategies in the clinic.

Losartan suppresses the inflammatory response in collagen-induced arthritis by inhibiting the MAPK and NF-κB pathways in B and T cells

The angiotensin II type 1 receptor (AT1R) antagonist losartan has been confirmed to have a moderate anti-inflammatory effect in vitro and in vivo. However, how it affects immune cells in Rheumatoid Arthritis (RA) is still unknown. We found that in human synovial tissues, AT1R is significantly expressed on T cells and B cells. Treatment with losartan (15 mg/kg) alone and in combination with a low dose of methotrexate (MTX 0.25 mg/kg/3 days) significantly suppressed the progression of CIA. Secondary paw swelling, joint destruction and the presence of pro-inflammatory cytokines (TNF-α and IFN-γ) in the serum were alleviated after treatment. The therapeutic effects of losartan were based on reduced T-cell and B-cell activation, specifically by decreased cell vitality and pro-inflammatory cytokine production. In addition, losartan combined with a low dose of MTX achieved a similar therapeutic effect, while protecting liver and kidney from MTX damage. Mechanistically, losartan inhibits the production of pro-inflammatory mediators, reduces the phosphorylation of p38, ERK, and p65, p50 nuclear transposition in T cells and B cells. Phosphorylation of JNK is not affected by losartan in the CIA rat model. losartan can be used as an effective RA treatment, which exhibits anti-arthritic effects potentially through down-regulating the phosphorylation of p38, ERK and signaling through NF-κB. While achieving similar anti-rheumatic effects, a combination therapy of losartan with a low dose of MTX, can protect from liver and renal damage caused by giving a high dose of MTX.

Presenting a New Standard Drug Model for Turmeric and Its Prized Extract, Curcumin

Various parts of the turmeric plant have been used as medicinal treatment for various conditions from ulcers and arthritis to cardiovascular disease and neuroinflammation. The rhizome's curcumin extract is the most studied active constituent, which exhibits an expansive polypharmacology with influence on many key inflammatory markers. Despite the expansive reports of curcucmin's therapeutic value, clinical reliability and research repeatability with curcumin treatment are still poor. The pharmacology must be better understood and reliably mapped if curcumin is to be accepted and used in modern medical applications. Although the polypharmacology of this extract has been considered, in mainstream medicine, to be a drawback, a perspective change reveals a comprehensive and even synergistic shaping of the NF-kB pathway, including transactivation. Much of the inconsistent research data and unreliable clinical outcomes may be due to a lack of standardization which also pervades research standard samples. The possibility of other well-known curcumin by-products contributing in the polypharmacology is also discussed. A new flowchart of crosstalk in transduction pathways that lead to shaping of nuclear NF-kB transactivation is generated and a new calibration or standardization protocol for the extract is proposed which could lead to more consistent data extraction and improved reliability in therapy.

Therapeutic effects of matrine derivate MASM in mice with collagen-induced arthritis and on fibroblast-like synoviocytes

MASM is a matrine derivate that exhibits a number of pharmacological effects, including immunosuppressive activity and anti-inflammatory properties. In this study, the mechanisms underlying the therapeutic efficacy of MASM in the treatment of rheumatoid arthritis were investigated using DBA/1 mice with collagen-induced arthritis (CIA) and fibroblast-like synoviocytes derived from rheumatoid arthritis patients (RA-FLS). We demonstrated that MASM markedly attenuated the severity of arthritis in CIA mice. The therapeutic effects were associated with ameliorated joint swelling and reduced bone erosion and destruction. Furthermore, the administration of MASM suppressed the expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). In vitro, MASM inhibited the expression of pro-inflammatory cytokines (TNF-α, IL-6, IL-8) and matrix metalloproteinases (MMP-1, MMP-3 and MMP-13) by inhibiting both the phosphorylation of MAPKs and the activation of NF-κB in IL-1β-stimulated RA-FLS. Additionally, MASM could induce apoptosis of RA-FLS via mitochondrial and Akt signaling pathways in human RA-FLS. These findings suggest that MASM could attenuate arthritis severity in CIA mice at least partially by blocking the phosphorylation of MAPKs and the activation of NF-κB and by inducing apoptosis in RA-FLS. MASM could be a potent therapeutic agent for the treatment of RA.

Mesenchymal stem cells alleviate experimental rheumatoid arthritis through microRNA-regulated IκB expression

Previous studies have demonstrated that mesenchymal stem cell (MSC) transplantation reduces the severity of collagen-induced arthritis (CIA) in mice, which is a model for rheumatoid arthritis (RA) in humans. However, the underlying molecular mechanisms remain ill-defined. Here, we showed that MSC transplantation reduced the activities of NF-κB signaling and decreased microRNA-548e (miR-548e) levels in the joint tissue in CIA-mice, seemingly through activation of transforming growth factor β receptor signaling. Bioinformatics analyses revealed that miR-548e inhibited protein translation of the NF-κB inhibitor, IκB, through binding to the 3′-UTR of the IκB mRNA. MSCs co-transplanted with adeno-associated virus (AAV) carrying miR-548e abolished the therapeutic effects of MSCs on CIA. On the other hand, transplantation of AAV carrying antisense of miR-548e (as-miR-548e) partially mimicked the effects of MSC transplantation on CIA. Together, these data suggest that MSC transplantation may alleviate experimental RA partially through suppressing miR-548e-mediated IκB inhibition.

Isocitrate dehydrogenase 2 inhibits gastric cancer cell invasion via matrix metalloproteinase 7

Isocitrate dehydrogenase 2 (IDH2) is a mitochondrial NADP-dependent isocitrate dehydrogenase and has been found to be a tumor suppressor in several types of tumors. However, the roles of IDH2 in hepatocellular carcinoma (GC) as well as underlying mechanisms remain unknown. Here, the IDH2 and matrix metalloproteinase 7 (MMP7) levels in the specimens from 30 GC patients were investigated by Western blot and ELISA, respectively. Their relationship was examined by correlation analyses. Patient survival with high IDH2 levels and low IDH2 levels was compared. IDH2 levels, and MMP7 levels were modified in a human GC cell line. The effects of IDH2 or MMP7 modulation on the expression of each other were analyzed. The dependence of nuclear factor κB (NF-κB) signaling was examined using a specific inhibitor. We found that the IDH2 levels significantly decreased in GC, and were even lower in GC with metastases, compared to those without metastases. IDH2 levels inversely correlated with MMP7 levels in GC. GC patients with low IDH2 had lower 5-year survival. MMP7 levels did not regulate IDH2 levels, while IDH2 inhibited MMP7 levels in GC cells, in a NF-κB signaling dependent manner. Together, these data suggest that IDH2 may be a tumor suppressor in that its loss may promote malignant progression of GC via NF-κB-dependent increases in MMP7 activity.

Multi-omic landscape of rheumatoid arthritis: re-evaluation of drug adverse effects

Objective: To provide a frame to estimate the systemic impact (side/adverse events) of (novel) therapeutic targets by taking into consideration drugs potential on the numerous districts involved in rheumatoid arthritis (RA) from the inflammatory and immune response to the gut-intestinal (GI) microbiome.

Methods: We curated the collection of molecules from high-throughput screens of diverse (multi-omic) biochemical origin, experimentally associated to RA. Starting from such collection we generated RA-related protein-protein interaction (PPI) networks (interactomes) based on experimental PPI data. Pharmacological treatment simulation, topological and functional analyses were further run to gain insight into the proteins most affected by therapy and by multi-omic modeling.

Results: Simulation on the administration of MTX results in the activation of expected (apoptosis) and adverse (nitrogenous metabolism alteration) effects. Growth factor receptor-bound protein 2 (GRB2) and Interleukin-1 Receptor Associated Kinase-4 (IRAK4, already an RA target) emerge as relevant nodes. The former controls the activation of inflammatory, proliferative and degenerative pathways in host and pathogens. The latter controls immune alterations and blocks innate response to pathogens.

Conclusions: This multi-omic map properly recollects in a single analytical picture known, yet complex, information like the adverse/side effects of MTX, and provides a reliable platform for in silico hypothesis testing or recommendation on novel therapies. These results can support the development of RA translational research in the design of validation experiments and clinical trials, as such we identify GRB2 as a robust potential new target for RA for its ability to control both synovial degeneracy and dysbiosis, and, conversely, warn on the usage of IRAK4-inhibitors recently promoted, as this involves potential adverse effects in the form of impaired innate response to pathogens.

Sumoylation modulates oxidative stress relevant to the viability and functionality of pancreatic beta cells

Sumoylation is an evolutionarily conserved regulatory mechanism to play an important role in various cellular processes through modulation of protein localization, stability and functionality. Recent studies including ours have consistently demonstrated that sumoylation provides protection for cells against oxidative stress. Given that pancreatic beta cells are a vulnerable target of oxidative stress, we thus in this minireview, updated the advancement of sumoylation in the regulation of ROS generation, and discussed its impact on several critical signaling pathways relevant to beta cells against oxidative stress and maintenance of functionality. Specifically, we bring together how sumoylation represses intracellular ROS formation, and protects beta cells against oxidative stress through regulating IκB/NFκB, JNK/c-Jun, and Maf/Nrf2 pathways. The tight implication of sumoylation in oxidative stress reflects that it could be an essential mechanism for beta cells to adapt to the detrimental cellular microenvironment.

Novel insights into the regulatory architecture of CD4+ T cells in rheumatoid arthritis

Rheumatoid arthritis (RA) is the most frequent autoimmune chronic inflammatory disease of the joints and it is characterized by the inflammation of the synovial membrane and the subsequent destruction of the joints. In RA, CD4+ T cells are the main drivers of disease initiation and the perpetuation of the damaging inflammatory process. To date, however, the genetic regulatory mechanisms of CD4+ T cells associated with RA etiology are poorly understood. The genome-wide analysis of expression quantitative trait loci (eQTL) in disease-relevant cell types is a recent genomic integration approach that is providing significant insights into the genetic regulatory mechanisms of many human pathologies. The objective of the present study was to analyze, for the first time, the genome-wide genetic regulatory mechanisms associated with the gene expression of CD4+ T cells in RA. Whole genome gene expression profiling of CD4+ T cells and the genome-wide genotyping (598,258 SNPs) of 29 RA patients with an active disease were performed. In order to avoid the excessive burden of multiple testing associated with genome-wide trans-eQTL analysis, we developed and implemented a novel systems genetics approach. Finally, we compared the genomic regulation pattern of CD4+ T cells in RA with the genomic regulation observed in reference lymphoblastoid cell lines (LCLs). We identified a genome-wide significant cis-eQTL associated with the expression of FAM66C gene (P = 6.51e−9). Using our new systems genetics approach we identified six statistically significant trans-eQTLs associated with the expression of KIAA0101 (P<7.4e−8) and BIRC5 (P = 5.35e−8) genes. Finally, comparing the genomic regulation profiles between RA CD4+ T cells and control LCLs we found 20 genes showing differential regulatory patterns between both cell types. The present genome-wide eQTL analysis has identified new genetic regulatory elements that are key to the activity of CD4+ T cells in RA.

Binding of NF-κB to nucleosomes: effect of translational positioning, nucleosome remodeling and linker histone H1

NF-κB is a key transcription factor regulating the expression of inflammatory responsive genes. How NF-κB binds to naked DNA templates is well documented, but how it interacts with chromatin is far from being clear. Here we used a combination of UV laser footprinting, hydroxyl footprinting and electrophoretic mobility shift assay to investigate the binding of NF-κB to nucleosomal templates. We show that NF-κB p50 homodimer is able to bind to its recognition sequence, when it is localized at the edge of the core particle, but not when the recognition sequence is at the interior of the nucleosome. Remodeling of the nucleosome by the chromatin remodeling machine RSC was not sufficient to allow binding of NF-κB to its recognition sequence located in the vicinity of the nucleosome dyad, but RSC-induced histone octamer sliding allowed clearly detectable binding of NF-κB with the slid particle. Importantly, nucleosome dilution-driven removal of H2A–H2B dimer led to complete accessibility of the site located close to the dyad to NF-κB. Finally, we found that NF-κB was able to displace histone H1 and prevent its binding to nucleosome. These data provide important insight on the role of chromatin structure in the regulation of transcription of NF-κB dependent genes.

In eukaryotes DNA is hierarchically packaged into chromatin by histones. The fundamental subunit of chromatin is the nucleosome. The packaging of DNA into nucleosomes not only restricts DNA accessibility for regulatory proteins but also provides opportunities to regulate DNA based processes. Accessibility of transcription factor NF-κB to their recognition sequences embedded in nucleosomes is highly controversial. On one hand in vivo studies have suggested that packaging of DNA into chromatin plays an important role in regulating the expression of NF-κB dependent genes, and on the other hand some in vitro studies reported that NF-κB can bind by itself to its recognition sequences embedded in the nucleosome. In this study, we show that NF-κB can specifically bind to its recognition sequences placed at the end of the nucleosome but not when placed inside the nucleosome core. We then demonstrate that disruption of nucleosome is necessary for the productive binding of NF-κB. Finally, we show that the presence of histone H1 does not affect the specific binding of NF-κB to its cognate sequence, when its binding region overlaps with the binding site of NF-κB. We propose that histone eviction is needed for NF-κB to bind specifically to its recognition sequence embedded in the nucleosome.

Kruppel-like factor 2 is a transcriptional regulator of chronic and acute inflammation

Although myeloid cell activation is requisite for an optimal innate immune response, this process must be tightly controlled to prevent collateral host tissue damage. Kruppel-like factor 2 (KLF2) is a potent regulator of myeloid cell proinflammatory activation. As an approximately 30% to 50% reduction in KLF2 levels has been observed in human subjects with acute or chronic inflammatory disorders, we studied the biological response to inflammation in KLF2(+/-) mice. Herein, we show that partial deficiency of KLF2 modulates the in vivo response to acute (sepsis) and subacute (skin) inflammatory challenge. Mechanistically, we link the anti-inflammatory effects of KLF2 to the inhibition of NF-κB transcriptional activity. Collectively, the observations provide biologically relevant insights into KLF2-mediated modulation of these inflammatory processes that could potentially be manipulated for therapeutic gain.

Attenuation of collagen-induced arthritis by orally available imidazoline-based NF-κB inhibitors

The pathogenesis of rheumatoid arthritis is mainly driven by NF-κB-mediated production of cytokines, such as TNF-α. We report herein that the orally available imidazoline-based NF-κB inhibitor, TCH-013, was found to significantly reduce TNF-α signaling and attenuate collagen antibody induced arthritis in BALB/c mice.

Anti-arthritic effects of magnolol in human interleukin 1β-stimulated fibroblast-like synoviocytes and in a rat arthritis model

Fibroblast-like synoviocytes (FLS) play an important role in the pathologic processes of destructive arthritis by producing a number of catabolic cytokines and metalloproteinases (MMPs). The expression of these mediators is controlled at the transcriptional level. The purposes of this study were to evaluate the anti-arthritic effects of magnolol (5,5'-Diallyl-biphenyl-2,2'-diol), the major bioactive component of the bark of Magnolia officinalis, by examining its inhibitory effects on inflammatory mediator secretion and the NF-κB and AP-1 activation pathways and to investigate its therapeutic effects on the development of arthritis in a rat model. The in vitro anti-arthritic activity of magnolol was tested on interleukin (IL)-1β-stimulated FLS by measuring levels of IL-6, cyclooxygenase-2, prostaglandin E(2), and matrix metalloproteinases (MMPs) by ELISA and RT-PCR. Further studies on how magnolol inhibits IL-1β-stimulated cytokine expression were performed using Western blots, reporter gene assay, electrophoretic mobility shift assay, and confocal microscope analysis. The in vivo anti-arthritic effects of magnolol were evaluated in a Mycobacterium butyricum-induced arthritis model in rats. Magnolol markedly inhibited IL-1β (10 ng/mL)-induced cytokine expression in a concentration-dependent manner (2.5-25 µg/mL). In clarifying the mechanisms involved, magnolol was found to inhibit the IL-1β-induced activation of the IKK/IκB/NF-κB and MAPKs pathways by suppressing the nuclear translocation and DNA binding activity of both transcription factors. In the animal model, magnolol (100 mg/kg) significantly inhibited paw swelling and reduced serum cytokine levels. Our results demonstrate that magnolol inhibits the development of arthritis, suggesting that it might provide a new therapeutic approach to inflammatory arthritis diseases.

Erratum to ‘‘Characterization of the regulatory roles of the SUMO

BACKGROUND

Type 1 diabetes is a multi-factorial autoimmune disease that results from the destruction of insulin-producing β cells of the pancreas; both genetic and environmental factors are thought to contribute to its development. Recently, a novel gene encoding small ubiquitin-like modifier protein 4 (SUMO4) was cloned and a single nucleotide substitution (M55V) was found to be strongly associated with type 1 diabetes. SUMO4 was shown to interact with IκBα and inhibit NFκB transcriptional activity. The M55V substitution of SUMO4 may affect its ability to modify IκBα by sumoylation, and so lead to activation of NFκB and transcription of genes implicated in the development of type 1 diabetes. However, the effects of sumoylation on immune cells are poorly understood.

METHODS

Human SUMO1, 2, 3, 4 and mouse SUMO2 (mSUMO2) were cloned and overexpressed in T and B cells using retroviral transduction. We then investigated whether SUMO overexpression affected their functions in vitro. To study the function of mSUMO2 in vivo, we made transgenic mice overexpressing mSUMO2 in T cells and pancreatic β cells and compared them with transgenic mice expressing a super-repressor of NFκB (a dominant negative form of NFκB, IκBαΔN) in T cells. Diabetes was induced in the two groups of mice by i.p. injection of streptozotocin.

RESULTS

Human SUMO1, 2, 3, 4 and mSUMO2 were all found to negatively regulate the transcriptional activity of T and B cells. Supporting this idea, mSUMO2 overexpression in T cells suppressed the production of both Th1 and Th2 cytokines unlike T cells from the IκBαΔN mice. However, transgenic mice overexpressing mSUMO2 had the same susceptibility to diabetes as wild type whereas the mice overexpressing IκBαΔN Tg were completely protected against diabetes.

CONCLUSION

These results indicate that at least in T cells, whereas NFκB has pro-apoptotic activity, mSUMO2 plays a more complex role in the development of autoimmune diabetes. The relative influence of NFκB and sumoylation on the development of autoimmune diabetes in vivo may vary depending on the developmental stage and cell type.

In Vitro and in Vivo Therapeutics of β-Thujaplicin on Lps-Induced Inflammation in Macrophages and Septic Shock in Mice

β-thujaplicin, an active constituent from Chamaecyparis obtusa, has been shown to have acaricidal and antimicrobial effects. Very few studies have focused on the potential of the anti-inflammatory effect of β-thujaplicin. Moreover, its capability of inhibiting inflammatory mediators e.g. TNF-α gene transcription, nitric oxide (NO) and prostaglandin E2, remains unknown. Besides those molecular mechanisms behind the anti-inflammatory effect of β-thujaplicin, solid proof of its effectiveness in vivo has not yet been studied. In our study, in vitro effects of β-thujaplicin were verified on RAW 264.7 macrophages which were stimulated by LPS. Indomethacin was used as a positive control. The inducible NO production after stimulation was measured by Griess reagent. PGE2, IL-6 and TNF-α were measured by ELISA methods. Protein expressions of iNOS, COX2, and NF-κB were evaluated by Western blotting. Septic ICR mice were administered 20 mg/kg of LPS and then the mortality rate was monitored. Within the concentration range which was devoid of cytotoxicty, β-thujaplicin exhibited a clear dose-dependent inhibition on LPS-induced NO production. Furthermore, β-thujaplicin inhibited LPS-induced PGE2, IL-6, and TNF-α production as well as iNOS, COX2, and NF-κB protein expression more substantially potent than indomethacin. In agreement with the in vitro study, β-thujaplicin was shown to be effective in vivo for inhibiting LPS-induced NO and TNF-α production and a significant decrease in mortality rate of mice suffering from septic shock was observed. This study demonstrates the potential of β-thujaplicin in treatment of inflammation and sepsis. These effects occur through an efficient blockage of TNF-α and iNOS production, β-thujaplicin efficacy is comparable to that of indomethacin thus it can be a substitution but bear less depletion of PGE2, making this compound very promising in clinical applications.

Characterization of the regulatory roles of the SUMO

BACKGROUND

Type 1 diabetes is a multi-factorial autoimmune disease that results from the destruction of insulin-producing β cells of the pancreas; both genetic and environmental factors are thought to contribute to its development. Recently, a novel gene encoding small ubiquitin-like modifier protein 4 (SUMO4) was cloned and a single nucleotide substitution (M55V) was found to be strongly associated with type 1 diabetes. SUMO4 was shown to interact with IκBα and inhibit NFκB transcriptional activity. The M55V substitution of SUMO4 may affect its ability to modify IκBα by sumoylation, and so lead to activation of NFκB and transcription of genes implicated in the development of type 1 diabetes. However, the effects of sumoylation on immune cells are poorly understood.

METHODS

Human SUMO1, 2, 3, 4 and mouse SUMO2 (mSUMO2) were cloned and overexpressed in dendritic, T and B cells using retroviral transduction. We then investigated whether SUMO overexpression affected their functions in vitro. To study the function of mSUMO2 in vivo, we made transgenic mice overexpressing mSUMO2 in T cells and pancreatic β cells and compared them with transgenic mice expressing a super-repressor of NFκB (a dominant negative form of NFκB, IκBαΔN) in T cells. Diabetes was induced in the two groups of mice by i.p. injection of streptozotocin.

RESULTS

Human SUMO1, 2, 3, 4 and mSUMO2 were all found to negatively regulate the transcriptional activity of T, B and dendritic cells. Although mSUMO2 overexpression in dendritic cells did not alter the expression of major histocompatibility complex class II proteins or B7, IL-1, IL-6 and IL-7, IL-12 expression decreased, switching Th1-directed immune responses into Th2 responses. Unlike T cells from the IκBαΔN mice, mSUMO2 overexpression in T cells suppressed the production of both Th1 and Th2 cytokines. Whereas the mice overexpressing IκBαΔN were completely protected against diabetes, those expressing mSUMO2 had the same susceptibility to diabetes as wild type.

CONCLUSION

These results indicate that at least in T cells, whereas NFκB has pro-apoptotic activity, mSUMO2 plays a more complex role in the development of autoimmune diabetes. The relative influence of NFκB and sumoylation on the development of autoimmune diabetes in vivo may vary depending on the developmental stage and cell type.

Lipopolysaccharide and hypoxia significantly alters interleukin-8 and macrophage chemoattractant protein-1 production by human fibroblasts but not fibrosis related factors

Besides extracellular matrix production, fibroblasts are able to produce various cytokines. Their ubiquitous position makes fibroblasts appropriate cells for sensing various noxious stimuli and for attracting immune cells in the affected area. In the present study the effect of lipopolysaccharide (LPS) and cobalt chloride (CoCl(2)) on the above fibroblasts functions were evaluated in primary human skin fibroblasts cultures. Collagen, matrix metalloproteinase-1, tissue inhibitor of metalloproteinases-1, transforming growth factor-β1, interleukin-8 (IL-8) and macrophage chemoattractant protein-1 (MCP-1) were measured in fibroblasts culture supernatants. Fibroblasts proliferation and viability were assessed as well. Hypoxia inducible factor-1α and the phosphorylated p65 portion of NF-κB were assessed in fibroblasts protein extracts. LPS and CoCl(2) had a minor effect on fibrosis related factors in human primary fibroblasts, possibly due to the absence of interplay with other cell types in the used experimental system. On the contrary both LPS and CoCl(2) increased significantly IL-8. LPS also increased considerably MCP-1, but CoCl(2) decreased it. Thus LPS and CoCl(2) induce a sentinel, nevertheless not identical, phenotype in primary human fibroblasts. The last disparity could result in different body response to infectious or hypoxic noxious stimuli.

Effects of hyaluronan on carrageenan-induced synovitis in rat TMJ

Nitric oxide is one of many proinflammatory mediators that are involved in temporomandibular joint (TMJ) inflammatory disorder and is synthesized by inducible nitric oxide synthase (iNOS). iNOS is transcriptionally regulated by nuclear factor-κB (NF-κB) in cases of inflammation, proliferation, and apoptosis. It has also been reported that nitric oxide is positively regulated by carrageenan and negatively regulated by hyaluronan in the knee joint. The aim of this study was to histologically evaluate how inflammation and cell proliferation of the synovial membrane are affected by the exogenous administration of carrageenan and hyaluronan in the rat TMJ by investigating iNOS, NF-κB, and anti proliferating cell nuclear antigen (PCNA) immunoreactivity. As results, immunoreactive cells to iNOS, NF-κB, and PCNA were normally localized only in the synovial membrane of wild type TMJs. The numbers of immunoreactive cells were extensively larger in the carrageenan-injected synovial membranes exhibiting excessive folding, and smaller in the hyaluronan-injected synovial membranes showing a few folds. These results indicate that a carrageenan injection induced inflammation and cell proliferation especially in the synovial membrane and that hyaluronan relieved the inflammation by decreasing inflammatory molecules in the synovial membrane.

Formulation and in vitro characterization of spray-dried antisense oligonucleotide to NF-kappaB encapsulated albumin microspheres

The aim of this study was to formulate and characterize microspheres containing antisense oligonucleotide to NF-kappaB using bovine serum albumin as the polymer matrix. Microspheres were prepared by spray-drying technique with 5, 10 and 15% drug loading. Glutaraldehyde was used as a cross-linking agent. The particle sizes ranged from 3-5 microm. Microspheres were smooth and spherical in shape, as determined by scanning electron microscopy (SEM). The yield of microspheres ranged from 70-75% and the encapsulation efficiencies were found to be in the range of 59-60%, as determined by a novel HPLC method. Zeta potential of the microspheres ranged between -39 to -53 mV, thus indicating good suspension stability in water. In-vitro release studies performed using phosphate buffer saline demonstrated extended drug release up to 72 h. Kinetic model fitting showed high correlation with the Higuchi model, suggesting that the drug release was primarily diffusion controlled.

Detecting and modulating the NF-kB activity in human immune cells: generation of human cell lines with altered levels of NF-kappaB

NF-kappaB plays a pivotal role in immunity and inflammation and is considered to be a promising candidate for drug development. However, global suppression of NF-kappaB may have undesirable side-effects. Our data and the results of others suggest that each of the five NF-kappaB subunits may have a specific function in controlling the expression of inflammatory mediators in immune cells. Identifying the role for each NF-kappaB subunit in primary human immune cells will allow a more targeted approach to inhibiting NF-kappaB subunit-specific cellular functions. However, results obtained with primary human cells can often be inconsistent due to donor heterogeneity. Therefore one possible approach could be to generate human immune cell lines with stably inhibited expression of specific NF-kappaB subunit(s) as described in this chapter.

Targeting NF-kappaB: a promising molecular therapy in inflammatory arthritis

The nuclear factor-kappa B family of transcription factors is intimately involved in the regulation of the inflammatory responses that play a fundamental role in the damage of articular tissues. Thus, many studies have examined the important contributions of components of the NF-kappaB signaling pathways to the pathogenesis of various rheumatic diseases and their pharmacologic modulation. Currently available therapeutic agents including nonsteroidal anti-inflammatory drugs, corticosteroids, nutraceuticals, and disease-modifying antirheumatic drugs, as well as novel specific small-molecule inhibitors have been employed. In addition, promising nucleic acid-based strategies have shown encouraging results. However, further research will be needed before NF-kappaB-aimed strategies become an effective therapy for inflammatory arthritis.

Treatment of adjuvant arthritis using microencapsulated antisense NF-κB oligonucleotides

Antisense oligonucleotides are promising new therapeutic agents used to selectively inhibit target genes such as Nuclear Factor Kappa B (NF-κB), an important transcription factor in the pathogenesis of inflammatory disease. The purpose of the present study was to evaluate microencapsulated antisense oligonucleotides specific to NF-κB for in vitro efficacy and treatment of adjuvant-induced arthritis in rats. Oligonucleotide-loaded albumin microspheres were prepared and characterized in terms of size, zeta potential, morphology and release pattern. This study reports significant NF-κB inhibition in vitro after treatment with microencapsulated antisense oligonucleotides. Furthermore, microencapsulated antisense NF-κB oligonucleotides were found to inhibit paw inflammation associated with rat adjuvant-induced arthritis in a dose-dependent manner. Taken together, the results presented in this work described albumin microspheres to be effective delivery vehicles for antisense NF-κB oligonucleotides and a potential treatment for inflammatory diseases.

The roles of the classical and alternative nuclear factor-kappaB pathways: potential implications for autoimmunity and rheumatoid arthritis

Nuclear factor-κB (NF-κB) is an inducible transcription factor controlled by two principal signaling cascades, each activated by a set of signal ligands: the classical/canonical NF-κB activation pathway and the alternative/noncanonical pathway. The former pathway proceeds via phosphorylation and degradation of inhibitor of NF-κB (IκB) and leads most commonly to activation of the heterodimer RelA/NF-κB1(p50). The latter pathway proceeds via phosphorylation and proteolytic processing of NF-κB2 (p100) and leads to activation, most commonly, of the heterodimer RelB/NF-κB2 (p52). Both pathways play critical roles at multiple levels of the immune system in both health and disease, including the autoimmune inflammatory response. These roles include cell cycle progression, cell survival, adhesion, and inhibition of apoptosis. NF-κB is constitutively activated in many autoimmune diseases, including diabetes type 1, systemic lupus erythematosus, and rheumatoid arthritis (RA). In this review we survey recent developments in the involvement of the classical and alternative pathways of NF-κB activation in autoimmunity, focusing particularly on RA. We discuss the involvement of NF-κB in self-reactive T and B lymphocyte development, survival and proliferation, and the maintenance of chronic inflammation due to cytokines such as tumor necrosis factor-α, IL-1, IL-6, and IL-8. We discuss the roles played by IL-17 and T-helper-17 cells in the inflammatory process; in the activation, maturation, and proliferation of RA fibroblast-like synovial cells; and differentiation and activation of osteoclast bone-resorbing activity. The prospects of therapeutic intervention to block activation of the NF-κB signaling pathways in RA are also discussed.

Resveratrol suppresses interleukin-1beta-induced inflammatory signaling and apoptosis in human articular chondrocytes: potential for use as a novel nutraceutical for the treatment of osteoarthritis

Osteoarthritis is an inflammatory disease of load-bearing synovial joints that is currently treated with drugs that exhibit numerous side effects and are only temporarily effective on pain, the main symptom of the disease. Consequently, there is an acute need for novel, safe and more effective chemotherapeutic agents for the treatment of osteoarthritis and related arthritic diseases. Resveratrol is a phytoalexin stilbene produced naturally by plants including red grapes, peanuts and various berries. Recent research in various cell models has demonstrated that resveratrol is safe and has potent anti-inflammatory properties. However, its potential for treating arthritic conditions has not been explored. In this study we provide experimental evidence that resveratrol inhibits the expression of VEGF, MMP-3, MMP-9 and COX-2 in human articular chondrocytes stimulated with the pro-inflammatory cytokine IL-1beta. Since these gene products are regulated by the transcription factor NF-kappaB, we investigated the effects of resveratrol on IL-1beta-induced NF-kappaB signaling pathway. Resveratrol, like N-Ac-Leu-Leu-norleucinal (ALLN) suppressed IL-1beta-induced proteasome function and the degradation of IkappaBalpha (an inhibitor of NF-kappaB) without affecting IkappaBalpha kinase activation, IkappaBalpha-phosphorylation or IkappaBalpha-ubiquitination which suppressed nuclear translocation of the p65 subunit of NF-kappaB and its phosphorylation. Furthermore, we observed that resveratrol as well as ALLN inhibited IL-1beta-induced apoptosis, caspase-3 activation and PARP cleavage in human articular chondrocytes. In summary, our results suggest that resveratrol suppresses apoptosis and inflammatory signaling through its actions on the NF-kappaB pathway in human chondrocytes. We propose that resveratrol should be explored further for the prophylactic treatment of osteoarthritis in humans and companion animals.

High levels of Lymphotoxin-Beta (LT-Beta) gene expression in rheumatoid arthritis synovium: clinical and cytokine correlations

Lymphotoxin-Beta (LT-Beta) is implicated in lymphoid follicle development, production of pro-inflammatory cytokines, and can enhance the proliferation of fibroblasts and synoviocytes. The objective of this study was to investigate LT-Beta and LT-BetaReceptor (LT-BetaR) gene expression in RA patient synovium and blood samples compared with control individuals, and correlate with LT-Alpha and TNF-Alpha gene expression and disease parameters. RT-PCR was used to investigate the gene expression of LT-Beta, LT-BetaR, TNF-Alpha and LT-Alpha in the blood and synovium of RA patients and a control group of individuals. LT-Beta gene expression was significantly higher in RA patient synovium compared to control synovium (P = 0.005). There was a significant positive correlation between LT-Beta and LT-Alpha gene expression in both the synovium (P = 0.001) and blood (P = 0.002) of RA patients. LT-Beta gene expression was significantly higher in RA patient synovial samples that were inflamed to a moderately severe degree compared to those inflamed to a minimal degree (P = 0.02). Analysis of clinical variables revealed a significant positive correlation between LT-BetaR gene expression in RA patient synovium and Pain VAS Score (P = 0.01) and also HAQ Score (P = 0.01). Increased LT-Beta gene expression occurs in RA synovium and correlates with the degree of inflammation. LT-Beta may play a role in RA disease pathogenesis by contributing to a more intense inflammatory reaction in the synovium.

CGRP, PACAP, and VIP Modulate Langerhans Cell Function by Inhibiting NF-κB Activation

The neuropeptides calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP), and vasoactive intestinal peptide (VIP) suppress Langerhans cell (LC) antigen presentation and modulate cytokine production. We have tested the hypothesis that these neuropeptides (NP) inhibit LC function by modulating activation of NF-kappaB. Lipopolysaccharide (LPS) activates NF-kappaB in both a LC-like cell line (XS52) and epidermal LC enriched to approximately 95% and this effect is inhibited by each of the NP. Furthermore, CGRP, PACAP, and VIP suppress phosphorylation of IkappaB kinase beta (P-IKKbeta), prevent degradation of the IkappaB alpha, and inhibit activation of NF-kappaB. Thus, these NP modulate LC function by reducing NF-kappaB activation. Bay 11-7085, an inhibitor of IKK, reduced tumor necrosis factor-alpha (TNFalpha) production from LPS-stimulated XS52 cells and inhibited the ability of LC to present antigen to a T-cell clone in vitro. Each NP also inhibited LPS-induced secretion of TNFalpha by XS52 cells and LC enriched to approximately 95% homogeneity. We suggest that the inhibitory activities of CGRP, PACAP, and VIP on LC function are mediated, at least in part, by inhibition of P-IKKbeta, which prevents IkappaB alpha degradation and activation of NF-kappaB. Modulation of this signaling pathway may be useful for therapeutic modulation of immunity in the skin.

Interleukin-18 induces angiogenic factors in rheumatoid arthritis synovial tissue fibroblasts via distinct signaling pathways

OBJECTIVE

Interleukin-18 (IL-18) is a proinflammatory cytokine implicated in the pathogenesis of rheumatoid arthritis (RA). This study was undertaken to examine the role of IL-18 in up-regulating secretion of the angiogenic factors stromal cell-derived factor 1alpha (SDF-1alpha)/CXCL12, monocyte chemoattractant protein 1 (MCP-1)/CCL2, and vascular endothelial growth factor (VEGF) in RA synovial tissue (ST) fibroblasts, and the underlying signaling mechanisms involved.

METHODS

We used enzyme-linked immunosorbent assays, Western blotting, and chemical inhibitors/antisense oligodeoxynucleotides to signaling intermediates to assess the role of IL-18.

RESULTS

IL-18 significantly enhanced the production of SDF-1alpha/CXCL12, MCP-1/CCL2, and VEGF in RA ST fibroblasts, in a time- and concentration-dependent manner. IL-18-induced SDF-1alpha/CXCL12 up-regulation was dependent on JNK, p38 MAPK, phosphatidylinositol 3-kinase (PI3K), and NFkappaB. While IL-18-induced production of SDF-1alpha/CXCL12 was also dependent on protein kinase Cdelta (PKCdelta), production of MCP-1/CCL2 was dependent on PKCalpha, not PKCdelta. Additionally, RA ST fibroblast IL-18-induced MCP-1/CCL2 production was mediated by JNK, PI3K, and NFkappaB. In contrast, IL-18 did not induce secretion of RA ST fibroblast MCP-1/CCL2 or VEGF via p38 MAPK. IL-18-induced RA ST fibroblast production of VEGF was mediated mainly by JNK-2, PKCalpha, and NFkappaB. IL-18 induced phosphorylation of JNK, PKCdelta, p38 MAPK, and activating transcription factor 2 (ATF-2) in RA ST fibroblasts in a time-dependent manner, with JNK-2 being upstream of PKCdelta, ATF-2, and NFkappaB.

CONCLUSION

These data support the notion that IL-18 has a unique role in inducing the secretion of angiogenic SDF-1alpha/CXCL12, MCP-1/CCL2, and VEGF in RA ST fibroblasts, via distinct signaling intermediates.

Suppression of NF-kappaB activation by curcumin leads to inhibition of expression of cyclo-oxygenase-2 and matrix metalloproteinase-9 in human articular chondrocytes: Implications for the treatment of osteoarthritis

Pro-inflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) play a key role in the pathogenesis of osteoarthritis (OA). Anti-inflammatory agents capable of suppressing the production and catabolic actions of these cytokines may have therapeutic potential in the treatment of OA and a range of other osteoarticular disorders. The purpose of this study was to examine the effects of curcumin (diferuloylmethane), a pharmacologically safe phytochemical agent with potent anti-inflammatory properties on IL-1beta and TNF-alpha signalling pathways in human articular chondrocytes maintained in vitro. The effects of curcumin were studied in cultures of human articular chondrocytes treated with IL-1beta and TNF-alpha for up to 72h. Expression of collagen type II, integrin beta1, cyclo-oxygenase-2 (COX-2) and matrix metalloproteinase-9 (MMP-9) was monitored by western blotting. The effects of curcumin on the expression, phosphorylation and nuclear translocation of protein components of the NF-kappaB system were studied by western blotting and immunofluorescence, respectively. Treatment of chondrocytes with curcumin suppressed IL-1beta-induced NF-kappaB activation via inhibition of IkappaBalpha phosphorylation, IkappaBalpha degradation, p65 phosphorylation and p65 nuclear translocation. Curcumin inhibited the IL-1beta-induced stimulation of up-stream protein kinase B Akt. These events correlated with down-regulation of NF-kappaB targets including COX-2 and MMP-9. Similar results were obtained in chondrocytes stimulated with TNF-alpha. Curcumin also reversed the IL-1beta-induced down-regulation of collagen type II and beta1-integrin receptor expression. These results indicate that curcumin has nutritional potential as a naturally occurring anti-inflammatory agent for treating OA through suppression of NF-kappaB mediated IL-1beta/TNF-alpha catabolic signalling pathways in chondrocytes.

The anti-rheumatic gold salt aurothiomalate suppresses interleukin-1beta-induced hyaluronan accumulation by blocking HAS1 transcription and by acting as a COX-2 transcriptional repressor

Gold compounds are among the oldest disease-modifying drugs and are still widely used today for treating rheumatoid arthritis. Despite decades of use, little is known about the mode of action of this class of drugs. Here we have demonstrated that aurothiomalate (AuTM) suppresses hyaluronan accumulation by blocking interleukin (IL)-1beta-induced hyaluronan synthase-1 transcription. We have further demonstrated that, in fibroblast-like synoviocytes (FLSs), AuTM acts as a specific COX-2 transcriptional repressor in that IL-1beta-induced COX-2 transcription is blocked, whereas COX-1 transcription and translation is unaffected. As a consequence, PGE2 levels released by FLS are dose-dependently reduced in cells exposed to AuTM. Of similar importance is the demonstration that AuTM does block NFkappaB-DNA interaction. In addition, two other transcription factors implicated in inflammatory events, namely AP-1 and STAT3, are blocked as well. The effect on NFkappaB likely explains the inhibition of COX-2 as well as that of HAS1, as both are genes that depend on the activation of NFkappaB. Interestingly, AuTM does not interfere with IL-1beta-induced IkappaB alpha degradation, in most cases a prerequisite for subsequent NFkappaB activation. Furthermore, evidence is presented that, in FLS, AuTM blocks NFkappaB-DNA interaction neither by binding to NFkappaB binding sites nor by interacting with activated NFkappaB proteins. Taken together, AuTM treatment of FLS blocks two of the most important proinflammatory events that are associated with rheumatoid arthritis. AuTM blocks the release of PGE2 and prevents the activation of NFkappaB, therefore blocking IL-1beta-induced hyaluronan accumulation and likely a series of other pro-inflammatory NFkappaB-dependent genes.

NF-kappaB as a potential therapeutic target in osteoarthritis and rheumatoid arthritis

The family of nuclear factor-kappaB (NF-kappaB) transcription factors is intimately involved in the regulation of expression of numerous genes in the setting of the inflammatory response. Since inflammatory processes play a fundamental role in the damage of articular tissues, many in vitro and in vivo studies have examined the contribution of components of the NF-kappaB signaling pathways to the pathogenesis of various rheumatic diseases, in particular, of osteoarthritis (OA) and rheumatoid arthritis (RA). Inflammation, cartilage degradation, cell proliferation, angiogenesis and pannus formation are processes in which the role of NF-kappaB is prominent. Consequently, large efforts have been devoted to the study of the pharmacologic modulation of the NF-kappaB pathways. These studies have employed currently available therapeutic agents including non-steroidal anti-inflammatory drugs, corticosteroids, nutraceuticals and disease-modifying anti-rheumatic drugs, as well as novel small molecule inhibitors targeted to specific proteins of the NF-kappaB pathways. In addition, promising strategies such as improved antisense DNA therapy and RNA interference have been examined with encouraging results. However, since NF-kappaB also plays a crucial beneficial role in normal physiology and technical problems for effective gene therapy still remain, further research will be needed before NF-kappaB-aimed strategies become an effective therapy for joint diseases, such as OA and RA.

Migration inhibitory factor up-regulates vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 via Src, PI3 kinase, and NFkappaB

Cell adhesion molecules are critical in monocyte (MN) recruitment in immune-mediated and hematologic diseases. We investigated the novel role of recombinant human migration inhibitory factor (rhMIF) in up-regulating vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) and their signaling pathways in human MNs. rhMIF-induced expression of VCAM-1 and ICAM-1 was significantly higher compared with nonstimulated MNs. rhMIF induced MN VCAM-1 and ICAM-1 expression in a concentration-dependent manner (P < .05). Antisense oligodeoxynucleotides (ODNs) and inhibitors of Src, PI3K, p38, and NFkappaB significantly reduced rhMIF-induced MN VCAM-1 and ICAM-1 expression (P < .05). However, Erk1/2 and Jak2 were not involved. Silencing RNA directed against MIF, and inhibitors of Src, PI3K, NFkappaB, anti-VCAM-1, and anti-ICAM-1 significantly inhibited rhMIF-induced adhesion of HL-60 cells to human dermal microvascular endothelial cells (HMVECs) or an endothelial cell line, HMEC-1, in cell adhesion assays, suggesting the functional significance of MIF-induced adhesion molecules (P < .05). rhMIF also activated MN phospho-Src, -Akt, and -NFkappaB in a time-dependent manner. rhMIF induced VCAM-1 and ICAM-1 up-regulation in 12 hours via Src, PI3K, and NFkappaB as shown by Western blotting and immunofluorescence. MIF and MIF-dependent signaling pathways may be a potential target for treating diseases characterized by up-regulation of cell adhesion molecules.

Regulation of osteoclast differentiation by the redox-dependent modulation of nuclear import of transcription factors

This study sought to characterize the reduced glutathione (GSH)/oxidized GSSG ratio during osteoclast differentiation and determine whether changes in the intracellular redox status regulate its differentiation through a RANKL-dependent signaling pathway. A progressive decrease of the GSH/GSSG ratio was observed during osteoclast differentiation, and the phenomenon was dependent on a decrease in total glutathione via downregulation of expression of the gamma-glutamylcysteinyl synthetase modifier gene. Glutathione depletion by L-buthionine-(S,R)-sulfoximine (BSO) was found to inhibit osteoclastogenesis by blocking nuclear import of NF-kappaB and AP-1 in RANKL-propagated signaling and bone pit formation by increasing BSO concentrations in mature osteoclasts. Furthermore, intraperitoneal injection of BSO in mice resulted in an increase in bone density and a decrease of the number of osteoclasts in bone. Conversely, glutathione repletion with either N-acetylcysteine or GSH enhanced osteoclastogenesis. These findings indicate that redox status decreases during osteoclast differentiation and that this modification directly regulates RANKL-induced osteoclastogenesis.

Signal transduction pathways: new targets for treating rheumatoid arthritis

Biotherapies and other new treatments introduced over the last few years have considerably enriched the therapeutic armamentarium for rheumatoid arthritis. Nevertheless, primary refractoriness or secondary escape phenomenon may occur, indicating a need for identifying new treatment targets. Promising candidates can be found among compounds involved in signal transduction pathways, most notably protein kinases (mitogen-activated protein kinase, MAPK and phosphatidylinositol-3 protein kinase, PI3) and transcription factors (nuclear factor kappa B, NF-kappaB; activating protein 1, AP-1; CCAAT/enhancer-binding protein, C/EBP and signal transducer and activator of transcription, STAT). Inhibition of signal transduction pathways may be achievable via three main strategies: pharmacological inhibitors, anti-sense or more specific inhibitors such as oligionucleotides or interfering mRNA, and induced overexpression of naturally occurring inhibitors. Clinical trials are under way to evaluate pharmacological inhibitors such as p38 MAPK. Although the preliminary results are promising, proof of safety has not yet been obtained. Signal transduction pathways are involved in normal processes, whose inhibition might produce untoward effects.

Cheongyeolsaseuptang inhibits production of TNF-alpha, IL-6 and IL-8 as well as NF-kappa B activation in human mast cells

Traditional Korean medicine, Cheongyeolsaseuptang (CYSST) has been widely applied as a treatment of rheumatoid arthritis (RA) in Korea. However, its effect in experimental models remains unknown. Recent reports suggest that in patients with RA, synovial mast cells increase in number and show signs of activation and production of cytokines. In this study, we investigated the effect of CYSST on production of cytokines by activated human mast cell line, HMC-1. When CYSST (1mg/ml) was added, the production of tumor necrosis factor-alpha, interleukin (IL)-6, and IL-8 was significantly inhibited about 37, 33.6, and 48%, respectively on phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187-stimulated HMC-1 cells. In addition, CYSST inhibited PMA plus A23187-induced activation of nuclear factor-kappaB. These findings may help understanding the mechanism of action of this medicine leading to control activated mast cells on inflammatory condition like RA.

Increased synovial tissue NF-kappa B1 expression at sites adjacent to the cartilage-pannus junction in rheumatoid arthritis

OBJECTIVE

To compare the expression of the Rel/NF-kappa B subunits, NF-kappa B1 (p50) and RelA (p65), in paired synovial tissue samples selected from sites adjacent to and remote from the cartilage-pannus junction (CPJ) in patients with inflammatory arthritis.

METHODS

Synovial tissue was selected at arthroscopy from sites adjacent to the CPJ and from the suprapatellar pouch of patients who were referred to an early arthritis clinic. Tissue samples from patients with osteoarthritis (OA) undergoing knee arthroplasty were also studied. Rel/NF-kappa B subunit activation and expression were measured by electrophoretic mobility shift assay and supershift analyses and by immunohistochemistry.

RESULTS

Tissue samples were obtained from 10 patients with rheumatoid arthritis (RA), 7 with a seronegative arthropathy (SnA), and 6 with OA. Rel/NF-kappa B was abundantly expressed in all samples. In both RA and SnA synovial tissue, the absolute number of NF-kappa B1+ cells at the CPJ was significantly higher than at non-CPJ sites (P = 0.006 and P = 0.02, respectively). The proportion of cells expressing NF-kappa B1 was also significantly higher at the CPJ compared with non-CPJ sites (P = 0.003 in RA, P = 0.009 in SnA). The numbers of RelA+ cells were consistently lower throughout. In RA synovial tissue, but not in SnA synovial tissue, both the absolute number and the proportion of RelA+ cells were significantly higher at the CPJ than at non-CPJ sites (P = 0.003 and P = 0.01, respectively). In OA synovial tissue, the numbers of cells expressing NF-kappa B1 and RelA were similar to those observed at the non-CPJ sites in all inflammatory tissues studied.

CONCLUSION

In this study of early inflammatory arthritis, expression of NF-kappa B1 in synovial tissue was highest at sites most likely to be associated with joint erosion. These observations are consistent with a critical role of NF-kappa B1 in joint destruction, and support the rationale for specific therapeutic inhibition of NF-kappa B in RA.

Selective inhibition of NF-κB blocks osteoclastogenesis and prevents inflammatory bone destruction in vivo

Bone destruction is a pathological hallmark of several chronic inflammatory diseases, including rheumatoid arthritis and periodontitis. Inflammation-induced bone loss of this sort results from elevated numbers of bone-resorbing osteoclasts. Gene targeting studies have shown that the transcription factor nuclear factor-kappa B (NF-kappa B) has a crucial role in osteoclast differentiation, and blocking NF-kappa B is a potential strategy for preventing inflammatory bone resorption. We tested this approach using a cell-permeable peptide inhibitor of the I kappa B-kinase complex, a crucial component of signal transduction pathways to NF-kappa B. The peptide inhibited RANKL-stimulated NF-kappa B activation and osteoclastogenesis both in vitro and in vivo. In addition, this peptide significantly reduced the severity of collagen-induced arthritis in mice by reducing levels of tumor necrosis factor-alpha and interleukin-1 beta, abrogating joint swelling and reducing destruction of bone and cartilage. Therefore, selective inhibition of NF-kappa B activation offers an effective therapeutic approach for inhibiting chronic inflammatory diseases involving bone resorption.

Distinct pathways of LPS-induced NF-κB activation and cytokine production in human myeloid and nonmyeloid cells defined by selective utilization of MyD88 and Mal/TIRAP

How lipopolysaccharide (LPS) signals through toll-like receptors (TLRs) to induce nuclear factor (NF)–κB and inflammatory cytokines in sepsis remains unclear. Major candidates for that process are myeloid differentiation protein 88 (MyD88) and MyD88 adaptor-like/TIR domain-containing adaptor protein (Mal/TIRAP) but their role needs to be further defined. Here, we have examined the role of MyD88 and Mal/TIRAP in primary human cells of nonmyeloid and myeloid origin as physiologically relevant systems. We found that MyD88 and Mal/TIRAP are essential for LPS-induced IκBα phosphorylation, NF-κB activation, and interleukin 6 (IL-6) or IL-8 production in fibroblasts and endothelial cells in a pathway that also requires IKK2. In contrast, in macrophages neither MyD88, Mal/TIRAP, nor IκB kinase 2 (IKK2) are required for NF-κB activation or tumor necrosis factor α (TNFα), IL-6, or IL-8 production, although Mal/TIRAP is still involved in the production of interferon β (IFNβ). Differential usage of TLRs may account for that, as in macrophages but not fibroblasts or endothelial cells, TLR4 is expressed in high levels at the cell surface, and neutralization of TLR4 but not TLR2 blocks LPS signaling. These observations demonstrate for the first time the existence of 2 distinct pathways of LPS-induced NF-κB activation and cytokine production in human myeloid and nonmyeloid cells defined by selective utilization of TLR4, MyD88, Mal/TIRAP, and IKK2, and reveal a layer of complexity not previously expected.

Prevention of allograft rejection by in vitro generated tolerogenic dendritic cells

Achieving immunological tolerance in transplantation has been a long sought-after goal since the 1960s. It is, therefore, interesting that the dendritic cells (DC), which are classically known as the most potent stimulators of T cell activation, are now also considered putative tools for tolerance induction. In line with this, much work has been performed using DC for vaccination and immune stimulation. Recently, great interest has been generated regarding the ability of DC to act as immune regulatory cells. Specific subsets of DC or immature DC (iDC) appear to be responsible for maintaining self-tolerance. In this review we will highlight our efforts at elucidating the contribution of DC in transplant tolerant in mice. Specifically, four strategies will be outlined that are currently being used for the generation of DC that have tolerogenic properties in the prevention of allograft rejection. The present study demonstrates that modulated iDC with blunted T cell stimulatory or antigen presentation abilities can afford transplant tolerance by minimizing T cell activation and proinflammatory cytokine production. Moreover, in an alternate strategy, normally matured DC have also been modulated such that alloreactive T cells are specifically targeted for deletion.