Immunopharmacology: anti-inflammatory therapy targeting transcription factors

Anti-Inflammatory Activity of the Active Compounds of Sanguisorbae Radix In Macrophages and in Vivo Toxicity Evaluation in Zebrafish

Sanguisorbae Radix (SR) is the root of the Sanguisorba officinalis L., a plant native to Asian countries and used in traditional medicine. We isolated the active components of SR and investigated their anti-inflammatory potential. Quercetin (QC), (+)-catechin (CC), and gallic acid (GA) were isolated from acetone extracts of SR. To elucidate the molecular mechanism by which these compounds suppress inflammation, we analyzed the transcriptional up-regulation of inflammatory mediators, such as nuclear factor-kappa B (NF-κB) and its target genes, inducible NOS (iNOS), and cyclooxygenase (COX)-2, in lipopolysaccharide (LPS)-stimulated macrophage RAW264.7 cells. Notably, QC, CC, and GA were found to inhibit the production of nitric oxide, tumor necrosis factor-alpha, and prostaglandin in a dose-dependent manner. Western blot results indicate that the compounds decreased the expression of iNOS and COX-2 proteins. Furthermore, the compounds decreased phosphorylation of IKK, IκB, ERK, p-38, and JNK proteins in LPS-induced cells. The results support the notion that QC, CC, and GA can potently inhibit the inflammatory response, with QC showing the highest anti-inflammatory activity. In in vivo toxicity studies in zebrafish (Danio rerio), QC showed no toxicity up to 25 μg/mL. Therefore, QC has non-toxic potential as a skin anti-inflammatory biomaterial.

Vanillic acid inhibits inflammatory mediators by suppressing NF-κB in lipopolysaccharide-stimulated mouse peritoneal macrophages

Vanillic acid is a benzoic acid derivative that is used as a flavoring agent. It is an oxidized form of vanillin. At present, the mechanisms by which vanillic acid exerts its anti-inflammatory effects are incompletely understood. In this study, we attempted to determine the effects of vanillic acid on lipopolysaccharide (LPS)-induced inflammatory responses in mouse peritoneal macrophages. Our findings indicate that vanillic acid inhibits LPS-induced production of tumor necrosis factor (TNF)-α and interleukin (IL)-6. During the inflammatory process, the levels of cyclooxygenase (COX)-2 and nitric oxide (NO) increased in mouse peritoneal macrophages, but vanillic acid suppressed both the enhanced levels of COX-2 and the production of prostaglandin E(2) and NO. Moreover, vanillic acid suppressed the activation of nuclear factor-kappa B (NF-κB) and caspase-1. These results provide novel insights into the pharmacological actions of vanillic acid and are indicative of the potential use of this molecule in the treatment of inflammatory diseases.

Fructus Ligustrum lucidi inhibits inflammatory mediator release through inhibition of nuclear factor-kappaB in mouse peritoneal macrophages

Fructus Ligustrum lucidi (FLL) is a widely used herbal medicine for the treatment of a variety of pathologies. We have investigated the anti-inflammatory mechanism of FLL in mouse peritoneal macrophages. FLL exerted an anti-inflammatory action through inhibition of lipopolysaccharide (LPS)-induced tumour necrosis factor (TNF)-alpha production in mouse peritoneal macrophages. The maximal inhibition rate of TNF-alpha production by FLL (0.5 mg mL(-1)) was 60.88 +/- 0.30%. In the inflammatory process, nitric oxide (NO) and prostaglandin E(2) (PGE(2)) increased in peritoneal macrophages. FLL decreased the protein level of NO and PGE(2) in LPS-stimulated mouse peritoneal macrophages. In addition, FLL inhibited nuclear factor-kappaB activation and IkappaB-alpha degradation by the decrease in IkappaB-alpha phosphorylation. Our study suggested that FLL reduced inflammation via an important molecular mechanism, which might explain its beneficial effect in the regulation of inflammatory reactions.

New aspect of immunosuppressive treatment in liver transplantation. How could you induce tolerance in liver transplantation?

New immunosuppressive strategies have improved short- and long-term graft survival. The current aim is to decrease the intensity of the immunosuppressive regimen, in an attempt to limit side effects and the direct toxicity of calcineurin inhibitor (CNI) for kidney function. We describe here current experience in liver and liver-kidney transplantation, the mechanism of tolerance and the immunosuppressive strategy used in liver transplantation.

Interleukin-18 bioactivity: a novel target for immunopharmacological anti-inflammatory intervention

Interleukin-18 is a member of the interleukin-1 family of cytokines with pro-inflammatory and tumor-suppressive properties. Its ability to potently enhance the production of interferon-gamma indicates in particular the crucial function of interleukin-18 as an immunomodulatory molecule. In fact, high levels of interleukin-18 are detected in human diseases associated with immunoactivation including viral or bacterial infections and chronic inflammation. Animal models suggest suppression of interleukin-18 bioactivity as a novel therapeutic concept specifically for the treatment of chronic inflammatory diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis. Here we introduce into the biology of interleukin-18 and review immunopharmacological strategies that aim at reducing interleukin-18 bioactivity in human disease.

Anti-inflammatory activity of gumiganghwaltang through the inhibition of nuclear factor-kappa B activation in peritoneal macrophages

Gumiganghwaltang (GMGHT) is an Oriental herbal prescription, which has been commonly used to treat a cold and inflammatory diseases in Korea. However, the mechanism of GMGHT is not clear. In this study, we investigated the anti-inflammatory mechanism of GMGHT in mouse peritoneal macrophages. GMGHT exerted an anti-inflammatory action through inhibiting lipopolysaccaride (LPS)-induced tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 production in mouse peritoneal macrophages. The maximal inhibition rate of TNF-alpha, and IL-6 production by GMGHT (1 mg/ml) was 52.31+/-2.8% and 56.31+/-3.1%, respectively. In the inflammatory process, cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) increased in peritoneal macrophages. GMGHT decreased the protein level of COX-2 and iNOS in LPS-stimulated mouse peritoneal macrophages. In addition, GMGHT inhibited nuclear factor-kappaB activation and IkappaB-alpha degradation. Our study suggests that an important molecular mechanism by GMKHT reduce inflammation, which might explain its beneficial effect in the regulation of inflammatory reactions.

Glucocorticoids for Human Skin: New Aspects of the Mechanism of Action

Topical glucocorticoids have always been considered first-line drugs for inflammatory diseases of the skin and bronchial system. Applied systemically, glucocorticoids are used for severe inflammatory and immunological diseases and the inhibition of transplant rejection. Owing to the progress in molecular pharmacology, the knowledge of the mechanism of action has increased during the last years. Besides distinct genomic targets, which are due to the activation of specific cytoplasmatic receptors resulting in the (trans-) activation or (trans-) repression of target genes, there are non-genomic effects on the basis of the interference with membrane-associated receptors as well as with membrane lipids. In fact, various glucocorticoids appear to differ with respect to the relative influence on these targets. Thus, the extended knowledge of glucocorticoid-induced cellular signalling should allow the design and development of even more specifically acting drugs - as it has been obtained with other steroids, e.g. estrogens for osteoporosis prevention.

Immunosuppression: towards a logical approach in liver transplantation

Over the last two decades there has been a significant increase in the number and types of immunosuppressive agents that have been available to clinicians. The protocols for immunosuppression used in liver transplantation have been derived historically from those in renal transplantation. During the last decade there has been a shift in the use of immunosuppression, with the introduction of interleukin (IL)-2 receptor antagonists in place of anti-lymphocyte preparations, substitution of tacrolimus for cyclosporin and mycophenolate for azathioprine. The use of corticosteroids has been reduced. For a variety of reasons, these changes have not always been made on the basis of properly randomized studies. The place of newer agents, such as sirolimus and leflunomide derivatives and of the microbiological agents, is unclear. In this review, we outline briefly the mechanism of action of drugs and suggest possible approaches to the management of the liver allograft recipient, suggesting how treatment could be adjusted according to the indication for transplantation as well as the individual's comorbidities.

IL-18BPa:Fc cooperates with immunosuppressive drugs in human whole blood

The proinflammatory cytokine interleukin (IL)-18 appears to be involved in the pathogenesis of diseases associated with immunoactivation and inflammation. Consequently, blockage of IL-18 bioactivity by use of IL-18 binding protein (IL-18 BP) is likely a promising therapeutic concept. In the present study, we investigated immunomodulatory activities of IL-18 BPa:Fc in human whole blood cultures. We report that IL-18 BPa:Fc (200 ng/mL) significantly inhibited lipopolysaccharide (LPS, 10 ng/mL)/IL-12 (5 ng/mL)-induced release of interferon-gamma (IFNgamma) and matrix metalloproteinase-9 (MMP-9) from whole blood cultures of healthy donors. Notably, IL-18 BPa:Fc (200 ng/mL) further reinforced dexamethasone (5 nM)- or mycophenolic acid (2 microM)-mediated reduction of LPS/IL-12-induced IFNgamma production by an additional 50.5 or 49.9%, respectively. To investigate effects of IL-18 BP:Fc in the context of autoimmune diseases, experiments were performed with whole blood obtained from patients with systemic lupus erythematosus or Wegener's granulomatosis undergoing immunosuppressive therapy. After ex vivo stimulation with LPS (10 ng/mL), production of IFNgamma and MMP-9 was determined. Both mediators likely contribute to renal inflammation frequently seen in these diseases. In accord with the aforementioned data, LPS (10 ng/mL)-induced IFNgamma was significantly reduced by coincubation with IL-18 BPa:Fc at 200 ng/mL. IL-18 BPa:Fc also inhibited production of MMP-9. The present data demonstrate that IL-18 BPa:Fc has the potential to amplify anti-inflammatory actions of immunosuppressive drugs, and thus may prove to be a valuable novel pharmacological component in the treatment of human autoimmune diseases.

Modulation of cadherin and catenins expression by tumor necrosis factor-alpha and dexamethasone in human bronchial epithelial cells

Asthma is an inflammatory disease, and the epithelial mesenchymal unit appears to be of importance in regulating the disease mechanisms. Cell-cell adhesion plays an important role in tissue morphogenesis and homeostasis and is commonly mediated by cadherins, a family of Ca(2+)-dependent transmembrane adhesion receptors. The cadherin family is involved in control of the cellular architecture. Proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha are involved in asthma and may interfere with epithelial integrity. In the present study, we investigated the role of TNF-alpha and dexamethasone on the expression of E-cadherin, beta-catenin, and gamma-catenin. We used two bronchial epithelial cell models: primary small airway epithelial cell cultures and primary culture obtained from human bronchial tubes. After 48 h of TNF-alpha stimulation with or without dexamethasone expression of E-cadherin, beta-catenin and gamma-catenin were analyzed using Western blot analysis and immunofluorescence. This study showed a decrease in the expression of adhesion molecules in both epithelial cell cultures after stimulation. Dexamethasone and anti-TNF-alpha inhibited this effect. In unstimulated cells, E-cadherin and beta- and gamma-catenin expression was membranous, expressed only on the lateral cell wall with minimal cytoplasmic expression. Immunoreactivity was cytoplasmic in stimulated cells. We demonstrated, using Western blot analysis and immunofluorescence, that proinflammatory cytokines could be responsible for structural damage to the epithelium and that this process was potentially reversed by steroids.

Effects of glucocorticoids on activation of c-jun N-terminal, extracellular signal-regulated, and p38 MAP kinases in human pulmonary endothelial cells

Mitogen-activated protein kinases (MAPK) play a central role in signal transduction by regulating many nuclear transcription factors involved in inflammatory, immune, and proliferative responses. The aim of this study was to investigate, in human pulmonary endothelial cells, the effects of synthetic glucocorticosteroids on activation of c-jun N-terminal kinases, extracellular signal-regulated kinases, and p38 subgroups of the MAPK family. Human microvascular endothelial cells from lung were stimulated for 2 h with either H(2)O(2) (2 mM), IL-1beta (10 ng/mL), or tumour necrosis factor-alpha (10 ng/mL). Under these conditions, a remarkable increase in the phosphorylation pattern of c-jun N-terminal kinases, extracellular signal-regulated kinases 1/2, and p38 was detected. Pretreatment for 12 h with dexamethasone (100 nM) was able to prevent phosphorylation-dependent MAPK activation in stimulated cells, without substantially affecting the expression levels of these enzymes. Our results suggest that inhibition of MAPK signaling pathways in human pulmonary endothelial cells may significantly contribute, by interfering with activation of several different transcription factors, to the antiinflammatory and immunosuppressive effects of glucocorticosteroids.

Minimal activators that bind to the KIX domain of p300/CBP identified by phage display screening

Human gene therapy approaches involving transcription factors often rely on artificial activation domains for transcriptional activation. These domains are often large (e.g., 80 amino acids for VP16), recruit multiple co-activation complexes at once, and offer no fine control over the level of transcription. In an attempt to understand the sequence and structural requirements of a minimal mammalian activator, we employed a molecular diversity approach with a peptide phage display library composed of random eight-amino acid peptides. Using the KIX domain of the mammalian co-activators p300 and CBP as target, we discovered a family of synthetic binding peptides. These peptides share significant homology with natural KIX domain ligands, and are shown to bind an overlapping, yet distinct, surface of p300/CREB-binding protein (CBP). When fused to a heterologous DNA binding domain, these synthetic peptides function as titratable, modular, and potent transcriptional activators in living cells through specific recruitment of p300/CBP, with the level of transcriptional activation proportional to the affinity of the synthetic peptide for the KIX domain. Taken together, our data demonstrate that a molecular diversity approach can be used to discover minimal, co-activator domain-specific synthetic activators, and that transcriptional activation can be modulated as desired at the level of co-activator recruitment.

Inhibition of NFkappaB-mediated pro-inflammatory gene expression in rat mesangial cells by the enolized 1,3-dioxane-4, 6-dione-5-carboxamide, CGP-43182

1. CGP-43182 has been described as a potent inhibitor of group IIA secreted phospholipase A(2) (group IIA sPLA(2)) activity in vitro. In rat mesangial cells, inhibition of group IIA sPLA(2) activity by CGP-43182 results in a 70% reduction of cytokine-stimulated prostaglandin E(2) biosynthesis, suggesting that group IIA sPLA(2) participates in arachidonic acid release and eicosanoid formation. Under these conditions the cytosolic phospholipase A(2) is not affected. 2. In mesangial cells, in addition to inhibition of catalytic activity, the membrane-permeant CGP-43182 completely blocked interleukin 1beta (IL1beta)-stimulated group IIA sPLA(2) gene expression. 3. A further action of CGP-43182 was a complete inhibition of cyclo-oxygenase-2 gene expression, resulting in a drastic reduction of prostaglandin formation in mesangial cells. 4. Moreover, CGP-43182 completely blocked IL1beta-induced gene expression of the inducible nitric oxide synthase, leading to an inhibition of cytokine-stimulated nitric oxide formation. 5. In contrast, the stimulatory effect of the cell-permeant cyclic AMP-analogue, dibutyryl-cAMP, on the induction of these enzymes was not inhibited by CGP-43182. These data indicate that CGP-43182 interferes with IL1beta- but not cyclic AMP-activated transcriptional regulation. 6. By studying components of the upstream transcription machinery, we observed an inhibition of NFkappaB activation by CGP-43182 in IL1beta-treated cells. Moreover, we observed that CGP-43182 prevented the phosphorylation and proteolytic degradation of the endogenous NFkappaB inhibitor, IkappaB, a process necessary for NFkappaB activation. 7. From our data, we propose that CGP-43182 is a potent anti-inflammatory drug useful for preventing the consequences of a concerted action of cytokine-stimulated pro-inflammatory genes mediated by NFkappaB.

Suppression of apoptosis by glucocorticoids in glomerular endothelial cells: effects on proapoptotic pathways

Tumour necrosis factor-alpha (TNF-alpha)- and lipopolysaccharide (LPS)-induced apoptosis of bovine glomerular endothelial cells is now recognized as an important part in the pathogenesis of glomerulonephritis characterized by early mitochondrial cytochrome c release, mitochondrial permeability transition, Bak protein upregulation, Bcl-X(L) protein downregulation and caspase-3 activation. Co-treatment of cells with 10 nM dexamethasone and TNF-alpha or LPS blocked roughly 90% of apoptotic cell death in glomerular endothelial cells. The action of glucocorticoids could be documented in that they prevented all apoptotic markers such as DNA laddering, DNA fragmentation measured by the diphenylamine assay as well as morphological alterations. To mechanistically elucidate the action of glucocorticoids we evaluated whether glucocorticoids elicit a time-dependent effect. For dexamethasone, to maximally inhibit DNA fragmentation a preincubation period was not required. Even if dexamethasone was supplemented 6 h following TNF-alpha or LPS we observed a maximal inhibitory effect. Concerning its influence on TNF-alpha and LPS signal transduction, we found that dexamethasone only partially prevented cytochrome-c-release as a first sign of apoptotic cell death but efficiently blocked mitochondrial permeability transition. Moreover, TNF-alpha- and LPS-induced Bak upregulation, Bcl-X(L)-downregulation, and the activation of caspase-3-like proteases, measured fluorometrically using DEVD-AMC and PARP cleavage, were efficiently blocked by dexamethasone. We postulate that glucocorticoids exert their inhibitory action upstream of the terminal death pathways but downstream of primary receptor mediated signals by blocking pro-apoptotic signals pre- and/or post cytochrome c release and mitochondrial signalling.