The Concise Guide to PHARMACOLOGY 2013/14: catalytic receptors

MD-2 as the target of a novel small molecule, L6H21, in the attenuation of LPS-induced inflammatory response and sepsis

BACKGROUND AND PURPOSE

Myeloid differentiation 2 (MD-2) recognizes LPS, which is required for TLR4 activation, and represents an attractive therapeutic target for severe inflammatory disorders. We previously found that a chalcone derivative, L6H21, could inhibit LPS-induced overexpression of TNF-α and IL-6 in macrophages. Here, we performed a series of biochemical experiments to investigate whether L6H21 specifically targets MD-2 and inhibits the interaction and signalling transduction of LPS-TLR4/MD-2.

EXPERIMENTAL APPROACH

The binding affinity of L6H21 to MD-2 protein was analysed using computer docking, surface plasmon resonance analysis, elisa, fluorescence measurements and flow cytometric analysis. The effects of L6H21 on MAPK and NF-κB signalling were determined using EMSA, fluorescence staining, Western blotting and immunoprecipitation. The anti-inflammatory effects of L6H21 were confirmed using elisa and RT-qPCR in vitro. The anti-inflammatory effects of L6H21 were also evaluated in septic C57BL/6 mice.

KEY RESULTS

Compound L6H21 inserted into the hydrophobic region of the MD-2 pocket, forming hydrogen bonds with Arg(90) and Tyr(102) in the MD-2 pocket. In vitro, L6H21 subsequently suppressed MAPK phosphorylation, NF-κB activation and cytokine expression in macrophages stimulated by LPS. In vivo, L6H21 pretreatment improved survival, prevented lung injury, decreased serum and hepatic cytokine levels in mice subjected to LPS. In addition, mice with MD-2 gene knockout were universally protected from the effects of LPS-induced septic shock.

CONCLUSIONS AND IMPLICATIONS

Overall, this work demonstrated that the new chalcone derivative, L6H21, is a potential candidate for the treatment of sepsis. More importantly, the data confirmed that MD-2 is an important therapeutic target for inflammatory disorders.

Induction of the inflammatory regulator A20 by gibberellic acid in airway epithelial cells

BACKGROUND AND PURPOSE

NF-κB-driven inflammation is negatively regulated by the zinc finger protein A20. Gibberellic acid (GA3 ) is a plant-derived diterpenoid with documented anti-inflammatory activity, which is reported to induce A20-like zinc finger proteins in plants. Here, we sought to investigate the anti-inflammatory effect of GA3 in airway epithelial cells and determine if the anti-inflammatory action relates to A20 induction.

EXPERIMENTAL APPROACH

Primary nasal epithelial cells and a human bronchial epithelial cell line (16HBE14o-) were used. Cells were pre-incubated with GA3 , stimulated with Pseudomonas aeruginosa LPS; IL-6 and IL-8 release, A20, NF-κB and IκBα expression were then evaluated. To determine if any observed anti-inflammatory effect occurred via an A20-dependent mechanism, A20 was silenced using siRNA.

KEY RESULTS

Cells pre-incubated with GA3 had significantly increased levels of A20 mRNA (4 h) and protein (24 h), resulting in a significant reduction in IL-6 and IL-8 release. This effect was mediated via reduced IκBα degradation and reduced NF-κB (p65) expression. Furthermore, the anti-inflammatory action of GA3 was abolished in A20-silenced cells.

CONCLUSIONS AND IMPLICATIONS

We showed that A20 induction by GA3 attenuates inflammation in airway epithelial cells, at least in part through its effect on NF-κB and IκBα. GA3 or gibberellin-derived derivatives could potentially be developed into anti-inflammatory drugs for the treatment of chronic inflammatory diseases associated with A20 dysfunction.

15-Lipoxygenases regulate the production of chemokines in human lung macrophages

BACKGROUND AND PURPOSE

15-Lipoxygenase (15-LOX) activity is associated with inflammation and immune regulation. The objectives of the present study were to investigate the expression of 15-LOX-1 and 15-LOX-2 and evaluate the enzymes' roles in the polarization of human lung macrophages (LMs) in response to LPS and Th2 cytokines (IL-4/-13).

EXPERIMENTAL APPROACH

LMs were isolated from patients undergoing surgery for carcinoma. The cells were cultured with a 15-LOX inhibitor (PD146176 or ML351), a COX inhibitor (indomethacin), a 5-LOX inhibitor (MK886) or vehicle and then stimulated with LPS (10 ng · mL(-1)), IL-4 (10 ng · mL(-1)) or IL-13 (50 ng · mL(-1)) for 24 h. Levels of ALOX15 (15-LOX-1) and ALOX15B (15-LOX-2) transcripts were determined by real-time quantitative PCR. Immunoassays were used to measure levels of LPS-induced cytokines (TNF-α, CCL2, CCL3, CCL4, CXCL1, CXCL8 and CXCL10) and Th2 cytokine-induced chemokines (CCL13, CCL18 and CCL22) in the culture supernatant.

KEY RESULTS

Stimulation of LMs with LPS was associated with increased expression of ALOX15B, whereas stimulation with IL-4/IL-13 induced the expression of ALOX15. PD146176 and ML351 (10 μM) reduced the release of the chemokines induced by LPS and Th2 cytokines. The effects of these 15-LOX inhibitors were maintained in the presence of indomethacin and MK886. Furthermore, indomethacin revealed the inhibitory effect of PD146176 on TNF-α release.

CONCLUSIONS AND IMPLICATIONS

Inhibition of the 15-LOX pathways is involved in the down-regulation of the in vitro production of chemokines in LMs. Our results suggest that the 15-LOX pathways have a role in the pathogenesis of inflammatory lung disorders and may thus constitute a potential drug target.

Constrictor prostanoids and uridine adenosine tetraphosphate: vascular mediators and therapeutic targets in hypertension and diabetes

Vascular dysfunction plays a pivotal role in the development of systemic complications associated with arterial hypertension and diabetes. The endothelium, or more specifically, various factors derived from endothelial cells tightly regulate vascular function, including vascular tone. In physiological conditions, there is a balance between endothelium-derived factors, that is, relaxing factors (endothelium-derived relaxing factors; EDRFs) and contracting factors (endothelium-derived contracting factors; EDCFs), which mediate vascular homeostasis. However, in disease states, such as diabetes and arterial hypertension, there is an imbalance between EDRF and EDCF, with a reduction of EDRF signalling and an increase of EDCF signalling. Among EDCFs, COX-derived vasoconstrictor prostanoids play an important role in the development of vascular dysfunction associated with hypertension and diabetes. Moreover, uridine adenosine tetraphosphate (Up4 A), identified as an EDCF in 2005, also modulates vascular function. However, the role of Up4 A in hypertension- and diabetes-associated vascular dysfunction is unclear. In the present review, we focused on experimental and clinical evidence that implicate these two EDCFs (vasoconstrictor prostanoids and Up4 A) in vascular dysfunction associated with hypertension and diabetes.

IL-1β reduces tonic contraction of mesenteric lymphatic muscle cells, with the involvement of cycloxygenase-2 and prostaglandin E2

BACKGROUND AND PURPOSE

The lymphatic system maintains tissue homeostasis by unidirectional lymph flow, maintained by tonic and phasic contractions within subunits, 'lymphangions'. Here we have studied the effects of the inflammatory cytokine IL-1β on tonic contraction of rat mesenteric lymphatic muscle cells (RMLMC).

EXPERIMENTAL APPROACH

We measured IL-1β in colon-conditioned media (CM) from acute (AC-CM, dextran sodium sulfate) and chronic (CC-CM, T-cell transfer) colitis-induced mice and corresponding controls (Con-AC/CC-CM). We examined tonic contractility of RMLMC in response to CM, the cytokines h-IL-1β or h-TNF-α (5, 10, 20 ng·mL(-1) ), with or without COX inhibitors [TFAP (10(-5)  M), diclofenac (0.2 × 10(-5)  M)], PGE2 (10(-5)  M)], IL-1-receptor antagonist, Anakinra (5 μg·mL(-1) ), or a selective prostanoid EP4 receptor antagonist, GW627368X (10(-6) and 10(-7)  M).

KEY RESULTS

Tonic contractility of RMLMC was reduced by AC- and CC-CM compared with corresponding control culture media, Con-AC/CC-CM. IL-1β or TNF-α was not found in Con-AC/CC-CM, but detected in AC- and CC-CM. h-IL-1β concentration-dependently decreased RMLMC contractility, whereas h-TNF-α showed no effect. Anakinra blocked h-IL-1β-induced RMLMC relaxation, and with AC-CM, restored contractility to RMLMC. IL-1β increased COX-2 protein and PGE2 production in RMLMC.. PGE2 induced relaxations in RMLMC, comparable to h-IL-1β. Conversely, COX-2 and EP4 receptor inhibition reversed relaxation induced by IL-1β.

CONCLUSIONS AND IMPLICATIONS

The IL-1β-induced decrease in RMLMC tonic contraction was COX-2 dependent, and mediated by PGE2 . In experimental colitis, IL-1β and tonic lymphatic contractility were causally related, as this cytokine was critical for the relaxation induced by AC-CM and pharmacological blockade of IL-1β restored tonic contraction.

Imidazole-based alkaloid derivative LCB54-0009 suppresses ocular angiogenesis and lymphangiogenesis in models of experimental retinopathy and corneal neovascularization

BACKGROUND AND PURPOSE

Abnormally induced angiogenesis and lymphangiogenesis are associated with human diseases, including neovascular eye disease. Substances that inhibit these processes may have potential as an attractive therapeutic strategy for these diseases.

EXPERIMENTAL APPROACH

In vitro and in vivo angiogenesis and/or lymphangiogenesis were assessed in VEGF- or hypoxia-stimulated endothelial and retinal cells and in animal models of oxygen-induced retinopathy (OIR), streptozotocin-induced diabetic retinopathy (SIDR), suture-induced inflammatory corneal neovascularization (SICNV) and silver nitrate-induced corneal neovascularization. HUVECs and retinal cells were cultured under hypoxic conditions or incubated with VEGF to identify the molecular mechanisms involved.

KEY RESULTS

The imidazole-based alkaloid derivative LCB54-0009 inhibited capillary-like tube formation in VEGF-induced HUVECs without inducing cytotoxic effects. Intravitreal injection of LCB54-0009 into retinas suppressed the formation of the pathological neovascular tufts and increased vascular permeability in both OIR of mice and SIDR of rats. Furthermore, subconjunctival injection of LCB54-0009 into the cornea suppressed corneal inflammation and inflammation-associated angiogenesis and lymphangiogenesis in SICNV of mice and silver nitrate cauterization of rats. These pharmacological activities were associated with effects on HIF-1α protein stability and HIF-1α/NF-κB redox sensitivity through its antioxidant activities. LCB54-0009 also inhibited the hypoxia-induced expression of angiopoietin-2, and VEGF-induced VEGFR-2 activation and downstream signalling, resulting in the down-regulation of the expression of pro-angiogenic factors and pro-inflammatory mediators and an up-regulation of the expression of anti-angiogenic factors.

CONCLUSIONS AND IMPLICATIONS

LCB54-0009 is a potential candidate molecule for blocking pathological angiogenesis and lymphangiogenesis mediated by HIF-1α- angiopoietin-2 expression and VEGFR-2 activation.

Pelitinib (EKB-569) targets the up-regulation of ABCB1 and ABCG2 induced by hyperthermia to eradicate lung cancer

BACKGROUND AND PURPOSE

Pelitinib is a potent irreversible EGFR TK inhibitor currently in clinical trials for the treatment of lung cancer. Hyperthermia has been applied concomitantly with chemotherapy and radiotherapy to enhance treatment outcome. In this study, we investigated the ability of the combination of pelitinib with other conventional anticancer drugs to specifically target cancer cells with up-regulated efflux transporters ABCB1/ABCG2 after hyperthermia as a novel way to eradicate the cancer stem-like cells responsible for cancer recurrence.

EXPERIMENTAL APPROACH

Alterations in intracellular topotecan accumulation, the efflux of fluorescent probe substrates, expression and ATPase activity of ABCB1/ABCG2 and tumoursphere formation capacity of side population (SP) cells sorted after hyperthermia were examined to elucidate the mechanism of pelitinib-induced chemosensitization.

KEY RESULTS

While pelitinib did not modulate ABCB1/ABCG2 expressions, the combination of pelitinib with transporter substrate anticancer drugs induced more marked apoptosis, specifically in cells exposed to hyperthermia. The flow cytometric assay showed that both ABCB1- and ABCG2-mediated drug effluxes were significantly inhibited by pelitinib in a concentration-dependent manner. The inhibition kinetics suggested that pelitinib is a competitive inhibitor of ABCB1/ABCG2, which is consistent with its ability to stimulate their ATPase activity. SP cells sorted after hyperthermia were found to be more resistant to anticancer drugs, presumably due to the up-regulation of ABCB1 and ABCG2. Importantly, pelitinib specifically enhanced the chemosensitivity but reduced the tumoursphere formation capacity of these SP cells.

CONCLUSIONS AND IMPLICATIONS

This study demonstrated a novel approach, exploiting drug resistance, to selectively kill cancer stem-like cells after hyperthermia.

Pharmacological actions of nobiletin in the modulation of platelet function

Background and Purpose

The discovery that flavonoids are capable of inhibiting platelet function has led to their investigation as potential antithrombotic agents. However, despite the range of studies on the antiplatelet properties of flavonoids, little is known about the mechanisms by which flavonoids inhibit platelet function. In this study, we aimed to explore the pharmacological effects of a polymethoxy flavonoid, nobiletin, in the modulation of platelet function.

Experimental Approach

The ability of nobiletin to modulate platelet function was explored by using a range of in vitro and in vivo experimental approaches. Aggregation, dense granule secretion and spreading assays were performed using washed platelets. Fibrinogen binding, α-granule secretion and calcium mobilization assays were performed using platelet-rich plasma and whole blood was used in impedance aggregometry and thrombus formation experiments. The effect of nobiletin in vivo was assessed by measuring tail bleeding time using C57BL/6 mice.

Key Results

Nobiletin was shown to suppress a range of well-established activatory mechanisms, including platelet aggregation, granule secretion, integrin modulation, calcium mobilization and thrombus formation. Nobiletin extended bleeding time in mice and reduced the phosphorylation of PKB (Akt) and PLCγ2 within the collagen receptor (glycoprotein VI)-stimulated pathway, in addition to increasing the levels of cGMP and phosphorylation of vasodilator-stimulated phosphoprotein, a protein whose activity is associated with inhibitory cyclic nucleotide signalling.

Conclusions and Implications

This study provides insight into the underlying molecular mechanisms through which nobiletin modulates haemostasis and thrombus formation. Therefore, nobiletin may represent a potential antithrombotic agent of dietary origins.

Small-molecule modulators of the OX40-OX40 ligand co-stimulatory protein-protein interaction

BACKGROUND AND PURPOSE

The OX40-OX40L protein-protein interaction (PPI) is an important cell-surface signalling co-stimulatory regulator within the TNFR superfamily (TNFRSF) and a promising therapeutic target for immunomodulation. PPIs are difficult to modulate using small-molecules. Here, we describe the identification of a small-molecule OX40 modulator and confirm its partial agonist character.

EXPERIMENTAL APPROACH

Cell-free screening assays were developed and used to identify OX40-OX40L inhibitors. Modified versions of this assay were used to elucidate the binding partner and the binding nature of active compounds. OX40-transfected sensor cells with NF-κB reporters were constructed and used to confirm and characterize activity and specificity. Immunomodulatory activity and partial agonist nature were further confirmed by ex vivo T-cell polarization assays.

KEY RESULTS

Several compounds that concentration-dependently affected OX40-OX40L were identified. Cell assays indicated that they were partial agonists with low micromolar potency and adequate selectivity. Under polarizing conditions based on TGF-β, the most promising compound mimicked the effect of an agonistic anti-OX40 antibody in suppressing regulatory T-cell generation and diverting CD4(+) CD62L(+) Foxp3(-) cells to TH 9 phenotype in vitro.

CONCLUSIONS AND IMPLICATIONS

We identified, to our knowledge, the first small-molecule compounds able to interfere with OX40-OX40L binding and, more importantly, to act as partial agonists of OX40. This is particularly interesting, as small-molecule agonism or activation of PPIs is considered unusually challenging and there are only few known examples. These results provide proof-of-principle evidence for the feasibility of small-molecule modulation of the OX40-OX40L interaction and for the existence of partial agonists for TNFRSF-PPIs.

The role of cannabinoids in adult neurogenesis

The processes underpinning post-developmental neurogenesis in the mammalian brain continue to be defined. Such processes involve the proliferation of neural stem cells and neural progenitor cells (NPCs), neuronal migration, differentiation and integration into a network of functional synapses within the brain. Both intrinsic (cell signalling cascades) and extrinsic (neurotrophins, neurotransmitters, cytokines, hormones) signalling molecules are intimately associated with adult neurogenesis and largely dictate the proliferative activity and differentiation capacity of neural cells. Cannabinoids are a unique class of chemical compounds incorporating plant-derived cannabinoids (the active components of Cannabis sativa), the endogenous cannabinoids and synthetic cannabinoid ligands, and these compounds are becoming increasingly recognized for their roles in neural developmental processes. Indeed, cannabinoids have clear modulatory roles in adult neurogenesis, probably through activation of both CB1 and CB2 receptors. In recent years, a large body of literature has deciphered the signalling networks involved in cannabinoid-mediated regulation of neurogenesis. This timely review summarizes the evidence that the cannabinoid system is intricately associated with neuronal differentiation and maturation of NPCs and highlights intrinsic/extrinsic signalling mechanisms that are cannabinoid targets. Overall, these findings identify the central role of the cannabinoid system in adult neurogenesis in the hippocampus and the lateral ventricles and hence provide insight into the processes underlying post-developmental neurogenesis in the mammalian brain.

Potent anti-inflammatory effects of the narrow spectrum kinase inhibitor RV1088 on rheumatoid arthritis synovial membrane cells

Background and Purpose

To investigate whether a narrow spectrum kinase inhibitor RV1088, which simultaneously targets specific MAPKs, Src and spleen tyrosine kinase (Syk), is more effective at inhibiting inflammatory signalling in rheumatoid arthritis (RA) than single kinase inhibitors (SKIs).

Experimental Approach

elisas were used to determine the efficacy of RV1088, clinically relevant SKIs and the pharmaceutical Humira on pro-inflammatory cytokine production by activated RA synovial fibroblasts, primary human monocytes and macrophages, as well as spontaneous cytokine synthesis by synovial membrane cells from RA patients. In human macrophages, RNAi knockdown of individual kinases was used to reveal the effect of inhibition of kinase expression on cytokine synthesis.

Key Results

RV1088 reduced TNF-α, IL-6 and IL-8 production in all individual activated cell types with low, nM, IC₅₀s. SKIs, and combinations of SKIs, were significantly less effective than RV1088. RNAi of specific kinases in macrophages also caused only modest inhibition of pro-inflammatory cytokine production. RV1088 was also significantly more effective at inhibiting IL-6 and IL-8 production by monocytes and RA synovial fibroblasts compared with Humira. Finally, RV1088 was the only inhibitor that was effective in reducing TNF-α, IL-6 and IL-8 synthesis in RA synovial membrane cells with low nM IC₅₀s.

Conclusions and Implications

This study demonstrates potent anti-inflammatory effect of RV1088, highlighting that distinct signalling pathways drive TNF-α, IL-6 and IL-8 production in the different cell types found in RA joints. As such, targeting numerous signalling pathways simultaneously using RV1088 could offer a more powerful method of reducing inflammation in RA than targeting individual kinases.

Inhibition of breast cancer progression by a novel histone deacetylase inhibitor, LW479, by down-regulating EGFR expression

BACKGROUND AND PURPOSE

Compounds targeting epigenetic events of tumours are likely to be an important addition to anticancer therapy. Histone deacetylase inhibitors (HDACI) have emerged as a promising novel class for therapeutic interventions associated with cancer, and many of them are currently in clinical investigation. Here, we assessed a novel hydroxamate-based HDACI, LW479, in breast cancer progression and explored its underlying mechanism(s).

EXPERIMENTAL APPROACH

LW479 was identified using the HDACI screening kit. Western blot and flow cytometry were used to analyse the biological effects of LW479 as a novel HDACI. The effects of LW479 were assessed in mouse models of spontaneous and experimental breast cancer. Co-immunoprecipitation, immunofluorescent staining and chromatin immunoprecipitation assays along with immunohistochemical analysis, were used to elucidate the molecular basis of the actions of LW479.

KEY RESULTS

LW479 was identified as a novel HDACI and showed marked cytotoxicity and induced apoptosis, as well as cell cycle arrest, in a panel of breast cancer cell lines. Intraperitoneal injections of LW479 markedly suppressed breast tumour growth and pulmonary metastasis in nude mice. LW479 also decreased levels of EGF receptors (EGFR) by blocking the binding of the transcription factor Sp1 and HDAC1 to the EGFR promoter region.

CONCLUSIONS AND IMPLICATIONS

Our data have elucidated the mechanisms underlying the inhibition by LW479 of tumour growth and metastasis, in models of breast cancer with aberrant EGFR expression. LW479 could be a candidate drug for breast cancer prevention.

Simvastatin alleviates cardiac fibrosis induced by infarction via up-regulation of TGF-β receptor III expression

BACKGROUND AND PURPOSE

Statins decrease heart disease risk, but their mechanisms are not completely understood. We examined the role of the TGF-β receptor III (TGFBR3) in the inhibition of cardiac fibrosis by simvastatin.

EXPERIMENTAL APPROACH

Myocardial infarction (MI) was induced by ligation of the left anterior descending coronary artery in mice given simvastatin orally for 7 days. Cardiac fibrosis was measured by Masson staining and electron microscopy. Heart function was evaluated by echocardiography. Signalling through TGFBR3, ERK1/2, JNK and p38 pathways was measured using Western blotting. Collagen content and cell viability were measured in cultures of neonatal mouse cardiac fibroblasts (NMCFs). Interactions between TGFBR3 and the scaffolding protein, GAIP-interacting protein C-terminus (GIPC) were detected using co-immunoprecipitation (co-IP). In vivo, hearts were injected with lentivirus carrying shRNA for TGFBR3.

KEY RESULTS

Simvastatin prevented fibrosis following MI, improved heart ultrastructure and function, up-regulated TGFBR3 and decreased ERK1/2 and JNK phosphorylation. Simvastatin up-regulated TGFBR3 in NMCFs, whereas silencing TGFBR3 reversed inhibitory effects of simvastatin on cell proliferation and collagen production. Simvastatin inhibited ERK1/2 and JNK signalling while silencing TGFBR3 opposed this effect. Co-IP demonstrated TGFBR3 binding to GIPC. Overexpressing TGFBR3 inhibited ERK1/2 and JNK signalling which was abolished by knock-down of GIPC. In vivo, suppression of cardiac TGFBR3 abolished anti-fibrotic effects, improvement of cardiac function and changes in related proteins after simvastatin.

CONCLUSIONS AND IMPLICATIONS

TGFBR3 mediated the decreased cardiac fibrosis, collagen deposition and fibroblast activity, induced by simvastatin, following MI. These effects involved GIPC inhibition of the ERK1/2/JNK pathway.

A novel snake venom-derived GPIb antagonist, anfibatide, protects mice from acute experimental ischaemic stroke and reperfusion injury

BACKGROUND AND PURPOSE

Ischaemic stroke is a serious disease with limited therapy options. Glycoprotein (GP)Ib binding to von Willebrand factor (vWF) exposed at vascular injury initiates platelet adhesion and contributes to platelet aggregation. GPIb has been suggested as an effective target for antithrombotic therapy in stroke. Anfibatide is a GPIb antagonist derived from snake venom and we investigated its protective effect on experimental brain ischaemia in mice.

EXPERIMENTAL APPROACH

Focal cerebral ischaemia was induced by 90 min of transient middle cerebral artery occlusion (MCAO). These mice were then treated with anfibatide (4, 2, 1 μg·kg(-1) ), injected i.v., after 90 min of MCAO, followed by 1 h of reperfusion. Tirofiban, a GPIIb/IIIα antagonist, was used as a positive control.

KEY RESULTS

Twenty-four hours after MCAO, anfibatide-treated mice showed significantly improved ischaemic lesions in a dose-dependent manner. The mice had smaller infarct volumes, less severe neurological deficits and histopathology of cerebrum tissues compared with the untreated MCAO mice. Moreover, anfibatide decreased the amount of GPIbα, vWF and accumulation of fibrin(ogen) in the vasculature of the ischaemic hemisphere. Tirofiban had similar effects on infarct size and fibrin(ogen) deposition compared with the MCAO group. Importantly, the anfibatide-treated mice showed a lower incidence of intracerebral haemorrhage and shorter tail bleeding time compared with the tirofiban-treated mice.

CONCLUSIONS AND IMPLICATIONS

Our data indicate anfibatide is a safe GPIb antagonist that exerts a protective effect on cerebral ischaemia and reperfusion injury. Anfibatide is a promising candidate that could be beneficial for the treatment of ischaemic stroke.

Pharmacological inhibition of caspase-8 limits lung tumour outgrowth

BACKGROUND AND PURPOSE

Lung cancer is one of the leading causes of cancer death worldwide. Despite advances in therapy, conventional therapy is still the main treatment and has a high risk of chemotherapy resistance. Caspase-8 is involved in cell death and is a recognized marker for poor patient prognosis.

EXPERIMENTAL APPROACH

To elucidate the role of caspase-8 in lung carcinoma, we used human samples of non-small cell lung cancer (NSCLC) and a mouse model of carcinogen-induced lung cancer.

KEY RESULTS

Healthy and cancerous NSCLC samples had similar levels of the active form of caspase-8. Similarly, lung tumour-bearing mice had high levels of the active form of caspase-8. Pharmacological inhibition of caspase-8 by z-IETD-FMK robustly reduced tumour outgrowth and this was closely associated with a reduction in the release of pro-inflammatory cytokines, IL-6, TNF-α, IL-18, IL-1α, IL-33, but not IL-1β. Furthermore, inhibition of caspase-8 reduced the recruitment of innate suppressive cells, such as myeloid-derived suppressor cells, but not of regulatory T cells to lungs of tumour-bearing mice. However, despite the well-known role of caspase-8 in cell death, the apoptotic cascade (caspase-3, caspase-9 and Bcl-2 dependent) was not active in lungs of z-IETD-treated tumour-bearing mice, but instead higher levels of the short segment of c-FLIP (c-FLIPs) were detected. Similarly, human healthy lung samples had higher levels of c-FLIPs than cancerous samples.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that caspase-8 is an important orchestrator of cancer-associated inflammation and the presence of short segment of c-FLIP determines whether caspase-8 induces tumour proliferation or tumour arrest/regression in the lung.

Effective suppression of pro-inflammatory molecules by DHCA via IKK-NF-κB pathway, in vitro and in vivo

BACKGROUND AND PURPOSE

Dehydrodiconiferyl alcohol (DHCA), a lignan compound isolated from Cucurbita moschata, has previously been shown to contain anti-adipogenic and antilipogenic effects on 3T3-L1 cells and mouse embryonic fibroblasts. As some of phytochemicals derived from natural plants show anti-inflammatory or antioxidative activities, we determined whether DHCA affects the production of pro-inflammatory mediators and also investigated its underlying mechanisms.

EXPERIMENTAL APPROACH

Raw264.7, a murine macrophage cell line, and primary murine macrophages derived from bone marrow cells were treated with LPS in the presence of DHCA. Furthermore, cells were treated with LPS and palmitate in the presence of DHCA to examine its effect on inflammasomes. The production of various pro-inflammatory mediators was examined and the underlying mechanisms investigated using a variety of molecular biological techniques. To test whether DHCA exhibits anti-inflammatory effects in vivo, mouse dextran sodium sulfate (DSS)-induced colitis model was used.

KEY RESULTS

DHCA reduced the production of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β and CCL2) and mediators (iNOS, COX-2 and ROS) by down-regulating the activity of I-κB kinase and, subsequently, the DNA binding activity of NF-κB. Moreover, DHCA effectively suppressed the palmitate-mediated activation of inflammasomes, which resulted in decreased production of IL-1β. DHCA also showed therapeutic effects in the mouse DSS-induced colitis model by suppressing the production of TNF-α and IL-1β and thus preventing weight loss and colon shrinkage.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that DHCA is a novel phytochemical that by regulating key molecules involved in inflammation and oxidative stress might exert a broad range of anti-inflammatory activities.

Combined treatment with bexarotene and rosuvastatin reduces angiotensin-II-induced abdominal aortic aneurysm in apoE(-/-) mice and angiogenesis

BACKGROUND AND PURPOSE

Abdominal aortic aneurysm (AAA) is a degenerative vascular disease associated with angiogenesis. Bexarotene is a retinoid X receptor (RXR) ligand with anti-angiogenic activity. Statins also exert anti-angiogenic activity and activate PPARs. Because RXR ligands form permissive heterodimers with PPARs and a single anti-angiogenic drug may not be sufficient to combat the wide array of angiogenic factors produced during AAA, we evaluated the effect of combined low doses of bexarotene and rosuvastatin in a mouse model of AAA.

EXPERIMENTAL APPROACH

The effect of the combined treatment was investigated in a murine model of angiotensin II-induced AAA in apoE(-/-) mice. This combination therapy was also evaluated in in vivo (Matrigel plug assay) and in vitro (endothelial cell differentiation assay) models of angiogenesis as well as the underlying mechanisms involved.

KEY RESULTS

Co-treatment with bexarotene plus rosuvastatin reduced aneurysm formation, inflammation and neovascularization compared with each single treatment. In HUVEC, the combination of suboptimal concentrations of bexarotene and rosuvastatin inhibited angiotensin II-induced morphogenesis, proliferation and migration. These effects were accompanied by diminished production of pro-angiogenic chemokines (CXCL1, CCL2 or CCL5) and VEGF, and seemed to be mediated by RXRα/PPARα and RXRα/PPARγ activation. This combined therapy reduced the activation of members of the downstream PI3K pathway (Akt/mTOR and p70S6K1) in vivo and in vitro.

CONCLUSIONS AND IMPLICATIONS

The combination of RXR agonists with statins at low doses synergistically interferes with the signalling pathways that modulate inflammation and angiogenesis and may constitute a new and safer therapeutic treatment for the control of AAA.

Dynasore enhances the formation of mitochondrial antiviral signalling aggregates and endocytosis-independent NF-κB activation

BACKGROUND AND PURPOSE

Dynasore has been used extensively as an inhibitor of clathrin-mediated endocytosis. While studying the role of endocytosis in LPS-induced signalling events, we discovered that dynasore itself induced activation of NF-κB, independently of its effects on endocytosis and without involving the Toll-like receptor 4 signalling pathways. The purpose of this study was to characterize this novel effect and to explore the underlying mechanism of action.

EXPERIMENTAL APPROACH

We utilized gel electrophoresis, microscopy, gene knockdown and luciferase-based promoter activity to evaluate the effect of dynasore on cell signalling pathways and to delineate the mechanisms involved in its effects,

KEY RESULTS

Dynasore activated the NF-κB and IFN-β pathways by activating mitochondrial antiviral signalling protein (MAVS). We showed that MAVS is activated by NOX/Rac and forms high molecular weight aggregates, similar to that observed in response to viral infection. We also demonstrated that dynasore-induced activation of JNK occurs downstream of MAVS and is required for activation of NF-κB and IFN-β.

CONCLUSION AND IMPLICATIONS

These findings demonstrate a novel effect of dynasore on cell signalling. We describe a novel Rac1-, ROS- and MAVS-mediated signalling cascade through which dynasore dramatically activates NF-κB, mimicking the viral induction of this key inflammatory signalling pathway. Our results call attention to the need for a broader interpretation of results when dynasore is used in its traditional fashion as an inhibitor of clathrin-mediated endocytosis. These results suggest the intriguing possibility that dynasore or one of its analogues might be of value as an antiviral therapeutic strategy or vaccine adjuvant.

The long-acting β2 -adrenoceptor agonist olodaterol attenuates pulmonary inflammation

Background and Purpose

β₂-adrenoceptor agonists are widely used in the management of obstructive airway diseases. Besides their bronchodilatory effect, several studies suggest inhibitory effects on various aspects of inflammation. The aim of our study was to determine the efficacy of the long-acting β₂-adrenoceptor agonist olodaterol to inhibit pulmonary inflammation and to elucidate mechanism(s) underlying its anti-inflammatory actions.

Experimental Approach

Olodaterol was tested in murine and guinea pig models of cigarette smoke- and LPS-induced lung inflammation. Furthermore, effects of olodaterol on the LPS-induced pro-inflammatory mediator release from human parenchymal explants, CD11b adhesion molecule expression on human granulocytes TNF-α release from human whole blood and on the IL-8-induced migration of human peripheral blood neutrophils were investigated.

Key Results

Olodaterol dose-dependently attenuated cell influx and pro-inflammatory mediator release in murine and guinea pig models of pulmonary inflammation. These anti-inflammatory effects were observed at doses relevant to their bronchodilatory efficacy. Mechanistically, olodaterol attenuated pro-inflammatory mediator release from human parenchymal explants and whole blood and reduced expression of CD11b adhesion molecules on granulocytes, but without direct effects on IL-8-induced neutrophil transwell migration.

Conclusions and Implications

This is the first evidence for the anti-inflammatory efficacy of a β₂-adrenoceptor agonist in models of lung inflammation induced by cigarette smoke. The long-acting β₂-adrenoceptor agonist olodaterol attenuated pulmonary inflammation through mechanisms that are separate from direct inhibition of bronchoconstriction. Furthermore, the in vivo data suggest that the anti-inflammatory properties of olodaterol are maintained after repeated dosing for 4 days.

Meta-chlorophenylpiperazine enhances leptin sensitivity in diet-induced obese mice

BACKGROUND AND PURPOSE

Most forms of human obesity are characterized by impaired leptin sensitivity and, therefore, the effectiveness of anti-obesity leptin therapy in these leptin-resistant obese patients is marginal. Hence, the development of strategies to increase leptin sensitivity is of high priority in the field of obesity research.

EXPERIMENTAL APPROACH

We first examined the effects of co-administration of leptin and meta-chlorophenylpiperazine (mCPP), an agonist of 5-HT2C and 5-HT1B receptors, on energy balance in leptin-resistant diet-induced obese (DIO) mice. We further assessed leptin-induced phosphorylation of the STAT-3 (pSTAT3) in various brain regions of DIO mice pretreated with mCPP or in mice genetically lacking 5-HT2C receptors.

RESULTS

Co-administration of mCPP with leptin had an additive effect on reducing body weight in DIO mice. Furthermore, mCPP pretreatment in DIO mice enhanced leptin-induced pSTAT3 in the arcuate nucleus, the ventromedial hypothalamic nucleus, and the ventral premammillary nucleus. Finally, deletion of 5-HT2C receptors significantly blunted leptin-induced pSTAT3 in these same hypothalamic regions.

CONCLUSIONS AND IMPLICATIONS

Our study provides evidence that drugs, which activate 5-HT2C receptors, could function as leptin sensitizers and be used in combination with leptin to provide additional weight loss in DIO.

Activation of NALP1 inflammasomes in rats with adjuvant arthritis; a novel therapeutic target of carboxyamidotriazole in a model of rheumatoid arthritis

BACKGROUND AND PURPOSE

Pro-inflammatory cytokines are important in rheumatoid arthritis (RA) and their production is mainly regulated by NF-κB and inflammasomes. Carboxyamidotriazole (CAI) exhibits potent anti-inflammatory activities by decreasing cytokines. Here, we have investigated NACHT, LRR and PYD domains-containing protein (NALP) inflammasomes in a rat model of RA and explored the therapeutic effects of CAI in this model and the involvement of NF-κB and inflammasomes in the actions of CAI.

EXPERIMENTAL APPROACH

The anti-arthritic effects of CAI were assessed in the adjuvant arthritis (AA) model in rats, using radiological and histological techniques. NALP1 and NALP3 inflammasomes, NF-κB pathway and pro-inflammatory cytokines levels were measured with Western blots, immunohistochemistry and ELISA.

KEY RESULTS

CAI decreased the arthritis index, improved radiological and histological changes, and reduced synovial IL-1β, IL-6, IL-18 and TNF-α levels in rats with AA. Compared with normal rats, the 70 kDa NALP1 isoform was up-regulated, NALP3 was down-regulated, and levels of the 165 kDa NALP1 isoform and the adaptor protein ASC were unchanged in synovial tissue from AA rats. CAI reduced the 70 kDa NALP1 isoform and restored NALP3 levels in AA rats; CAI inhibited caspase-1 activation in AA synovial tissue, but not its enzymic activity in vitro. In addition, CAI reduced expression of p65 NF-κB subunit and IκBα phosphorylation and degradation in AA rats.

CONCLUSION AND IMPLICATIONS

NALP1 inflammasomes were activated in synovial tissues from AA rats and appeared to be a novel therapeutic target for RA. CAI could have therapeutic value in RA by inhibiting activation of NF-κB and NALP1 inflammasomes and by decreasing pro-inflammatory cytokines.

The contribution of astrocytes and microglia to traumatic brain injury

Traumatic brain injury (TBI) represents a major cause of death and disability in developed countries. Brain injuries are highly heterogeneous and can also trigger other neurological complications, including epilepsy, depression and dementia. The initial injury often leads to the development of secondary sequelae; cellular hyperexcitability, vasogenic and cytotoxic oedema, hypoxia-ischaemia, oxidative stress and inflammation, all of which influence expansion of the primary lesion. It is widely known that inflammatory events in the brain following TBI contribute to the widespread cell death and chronic tissue degeneration. Neuroinflammation is a multifaceted response involving a number of cell types, both within the CNS and in the peripheral circulation. Astrocytes and microglia, cells of the CNS, are considered key players in initiating an inflammatory response after injury. These cells are capable of secreting various cytokines, chemokines and growth factors, and following injury to the CNS, undergo changes in morphology. Ultimately, these changes can influence the local microenvironment and thus determine the extent of damage and subsequent repair. This review will focus on the roles of microglia and astrocytes following TBI, highlighting some of the key processes, pathways and mediators involved in this response. Additionally, both the beneficial and the detrimental aspects of these cellular responses will be examined using evidence from animal models and human post-mortem TBI studies.

Toll-interacting protein contributes to mortality following myocardial infarction through promoting inflammation and apoptosis

BACKGROUND AND PURPOSE

Toll-interacting protein (Tollip) is an endogenous inhibitor of toll-like receptors, a superfamily that plays a pivotal role in various pathological conditions, including myocardial infarction (MI). However, the exact role of Tollip in MI remains unknown.

EXPERIMENTAL APPROACH

MI models were established in Tollip knockout (KO) mice, mice with cardiac-specific overexpression of human Tollip gene and in their Tollip(+/+) and non-transgenic controls respectively. The effects of Tollip on MI were evaluated by mortality, infarct size and cardiac function. Hypoxia-induced cardiomyocyte damage was investigated in vitro to confirm the role of Tollip in heart damage.

KEY RESULTS

Tollip expression was dramatically up-regulated in human ischaemic hearts and infarcted mice hearts. MI-induced mortality, infarct size and cardiac dysfunction were decreased in Tollip-KO mice compared with Tollip(+/+) controls. Ischaemic hearts from Tollip-KO mice exhibited decreased inflammatory cell infiltration and reduced NF-κB activation. Tollip depletion also alleviated myocardial apoptosis by down-regulating pro-apoptotic protein levels and up-regulating anti-apoptotic protein expressions in infarct border zone. Conversely, MI effects were exacerbated in mice with cardiac-specific Tollip overexpression. This aggravated MI injury by Tollip in vivo was confirmed with in vitro assays. Inhibition of Akt signalling was associated with the detrimental effects of Tollip on MI injury; activation of Akt largely reversed the deleterious effects of Tollip on MI-induced cardiomyocyte death.

CONCLUSIONS AND IMPLICATIONS

Tollip promotes inflammatory and apoptotic responses after MI, leading to increased mortality and aggravated cardiac dysfunction. These findings suggest that Tollip may serve as a novel therapeutic target for the treatment of MI.

Effect of tyrphostin AG879 on Kv 4.2 and Kv 4.3 potassium channels

BACKGROUND AND PURPOSE

A-type potassium channels (IA) are important proteins for modulating neuronal membrane excitability. The expression and activity of Kv 4.2 channels are critical for neurological functions and pharmacological inhibitors of Kv 4.2 channels may have therapeutic potential for Fragile X syndrome. While screening various compounds, we identified tyrphostin AG879, a tyrosine kinase inhibitor, as a Kv 4.2 inhibitor from. In the present study we characterized the effect of AG879 on cloned Kv 4.2/Kv channel-interacting protein 2 (KChIP2) channels.

EXPERIMENTAL APPROACH

To screen the library of pharmacologically active compounds, the thallium flux assay was performed on HEK-293 cells transiently-transfected with Kv 4.2 cDNA using the Maxcyte transfection system. The effects of AG879 were further examined on CHO-K1 cells expressing Kv 4.2/KChIP2 channels using a whole-cell patch-clamp technique.

KEY RESULTS

Tyrphostin AG879 selectively and dose-dependently inhibited Kv 4.2 and Kv 4.3 channels. In Kv 4.2/KChIP2 channels, AG879 induced prominent acceleration of the inactivation rate, use-dependent block and slowed the recovery from inactivation. AG879 induced a hyperpolarizing shift in the voltage-dependence of the steady-state inactivation of Kv 4.2 channels without apparent effect on the V1/2 of the voltage-dependent activation. The blocking effect of AG879 was enhanced as channel inactivation increased. Furthermore, AG879 significantly inhibited the A-type potassium currents in the cultured hippocampus neurons.

CONCLUSION AND IMPLICATIONS

AG879 was identified as a selective and potent inhibitor the Kv 4.2 channel. AG879 inhibited Kv 4.2 channels by preferentially interacting with the open state and further accelerating their inactivation.

Intrinsic defence capacity and therapeutic potential of natriuretic peptides in pulmonary hypertension associated with lung fibrosis

BACKGROUND AND PURPOSE

Idiopathic pulmonary fibrosis (IPF) is a progressive fibro-proliferative disorder refractory to current therapy commonly complicated by the development of pulmonary hypertension (PH); the associated morbidity and mortality are substantial. Natriuretic peptides possess vasodilator and anti-fibrotic actions, and pharmacological augmentation of their bioactivity ameliorates renal and myocardial fibrosis. Here, we investigated whether natriuretic peptides possess an intrinsic cytoprotective function preventing the development of pulmonary fibrosis and associated PH, and whether therapeutics targeting natriuretic peptide signalling demonstrate efficacy in this life-threatening disorder.

EXPERIMENTAL APPROACH

Pulmonary haemodynamics, right ventricular function and markers of lung fibrosis were determined in wild-type (WT) and natriuretic peptide receptor (NPR)-A knockout (KO) mice exposed to bleomycin (1 mg·kg⁻¹). Human myofibroblast differentiation was studied in vitro.

KEY RESULTS

Exacerbated cardiac, vascular and fibrotic pathology was observed in NPR-A KO animals, compared with WT mice, exposed to bleomycin. Treatment with a drug combination that raised circulating natriuretic peptide levels (ecadotril) and potentiated natriuretic peptide-dependent signalling (sildenafil) reduced indices of disease progression, whether administered prophylactically or to animals with established lung disease. This positive pharmacodynamic effect was diminished in NPR-A KO mice. Atrial natriuretic peptide and sildenafil synergistically reduced TGFβ-induced human myofibroblast differentiation, a key driver of remodelling in IPF patients.

CONCLUSIONS AND IMPLICATIONS

These data highlight an endogenous host-defence capacity of natriuretic peptides in lung fibrosis and PH. A combination of ecadotril and sildenafil reversed the pulmonary haemodynamic aberrations and remodelling that characterize the disease, advocating therapeutic manipulation of natriuretic peptide bioactivity in patients with IPF.

Effects of receptor tyrosine kinase inhibitors on VEGF165 a- and VEGF165 b-stimulated gene transcription in HEK-293 cells expressing human VEGFR2

Background and Purpose

Receptor tyrosine kinase inhibitors (RTKIs) targeted at VEGF receptor 2 (VEGFR2) have proved to be attractive approaches to cancer therapy based on their ability to reduce angiogenesis. Here we have undertaken a quantitative analysis of the interaction of RTKIs and two VEGF splice variants, VEGF₁₆₅a and VEGF₁₆₅b, with VEGFR2 by studying nuclear factor of activated T-cells (NFAT) reporter gene activity in live HEK-293 cells.

Experimental Approach

HEK-293 cells expressing the human VEGFR2 and a firefly luciferase reporter gene regulated by an NFAT response element were used for quantitative analysis of the effect of RTKIs on VEGF₁₆₅a- and VEGF₁₆₅b-stimulated luciferase gene expression.

Key Results

VEGF₁₆₅a produced a concentration-dependent activation of the NFAT-luciferase reporter gene in living cells that was inhibited in a non-competitive fashion by four different RTKIs (cediranib, pazopanib, sorafenib and vandetanib). The potency obtained for each RTKI from this analysis was similar to those obtained in binding studies using purified VEGFR2 kinase domains. VEGF₁₆₅b was a lower-efficacy agonist of the NFAT-luciferase response when compared with VEGF₁₆₅a. Analysis of the concentration–response data using the operational model of agonism indicated that both VEGF₁₆₅ isoforms had similar affinity for VEGFR2.

Conclusions and Implications

Quantitative pharmacological analysis of the interaction of VEGF₁₆₅ isoforms and RTKIs with VEGFR2 in intact living cells has provided important insights into the relative affinity and efficacy of VEGF₁₆₅a and VEGF₁₆₅b for activation of the calcineurin- NFAT signalling pathway by this tyrosine kinase receptor.

Toll-like receptor 4 contributes to vascular remodelling and endothelial dysfunction in angiotensin II-induced hypertension

BACKGROUND AND PURPOSE

Toll-like receptor 4 (TLR4) signalling contributes to inflammatory cardiovascular diseases, but its role in hypertension and the associated vascular damage is not known. We investigated whether TLR4 activation contributed to angiotensin II (AngII)-induced hypertension and the associated vascular structural, mechanical and functional alterations.

EXPERIMENTAL APPROACH

AngII was infused (1.44 mg · kg(-1) · day(-1), s.c.) for 2 weeks in C57BL6 mice, treated with a neutralizing anti-TLR4 antibody or IgG (1 μg · day(-1); systolic BP (SBP) and aortic cytokine levels were measured. Structural, mechanical and contractile properties of aortic and mesenteric arterial segments were measured with myography and histology. RT-PCR and Western blotting were used to analyse these tissues and cultured vascular smooth muscle cells (VSMC) from hypertensive rats (SHR).

KEY RESULTS

Aortic TLR4 mRNA levels were raised by AngII infusion. Anti-TLR4 antibody treatment of AngII-treated mice normalised: (i) increased SBP and TNF-α, IL-6 and CCL2 levels; (ii) vascular structural and mechanical changes; (iii) altered aortic phenylephrine- and ACh-induced responses; (iv) increased NOX-1 mRNA levels, superoxide anion production and NAD(P)H oxidase activity and effects of catalase, apocynin, ML-171 and Mito-TEMPO on vascular responses; and (v) reduced NO release and effects of L-NAME on phenylephrine-induced contraction. In VSMC, the MyD88 inhibitor ST-2825 reduced AngII-induced NAD(P)H oxidase activity. The TLR4 inhibitor CLI-095 reduced AngII-induced increased phospho-JNK1/2 and p65 NF-κB subunit nuclear protein expression.

CONCLUSIONS AND IMPLICATIONS

TLR4 up-regulation by AngII contributed to the inflammation, endothelial dysfunction, vascular remodelling and stiffness associated with hypertension by mechanisms involving oxidative stress. MyD88-dependent activation and JNK/NF-κB signalling pathways participated in these alterations.

The tyrosine kinase inhibitor bafetinib inhibits PAR2-induced activation of TRPV4 channels in vitro and pain in vivo

BACKGROUND AND PURPOSE

Protease-activated receptor 2 (PAR2) is expressed on nociceptive neurons, and can sensitize transient receptor potential (TRP) ion channels to amplify neurogenic inflammation and pain. The mechanisms by which this occurs are not fully understood. PAR2 causes receptor-operated activation of TRPV4 channels and TRPV4 null mice have attenuated PAR2-stimulated neurogenic inflammation and mechanical hyperalgesia. Here we investigate the intracellular signalling mechanisms underlying PAR2-induced TRPV4 channel activation and pain.

EXPERIMENTAL APPROACH

Responses of non-transfected and TRPV4-transfected HEK293 cells to agonists of PAR2 (trypsin and SLIGRL) and TRPV4 channels (GSK1016790A) were determined using calcium imaging. Inhibitors of TRPV4 channels (HC067047), sarcoendoplasmic reticulum calcium transport ATPase (thapsigargin), Gαq (UBO-QIC), tyrosine kinases (bafetinib and dasatinib) or PI3 kinases (wortmannin and LY294002) were used to investigate signalling mechanisms. In vivo effects of tyrosine kinase inhibitors on PAR2 -induced mechanical hyperalgesia were assessed in mice.

KEY RESULTS

In non-transfected HEK293 cells, PAR2 activation transiently increased intracellular calcium ([Ca(2+) ]i ). Functional expression of TRPV4 channels caused a sustained increase of [Ca(2+) ]i , inhibited by HC067047, bafetinib and wortmannin; but not by thapsigargin, UBO-QIC, dasatinib or LY294002. Bafetinib but not dasatinib inhibited PAR2-induced mechanical hyperalgesia in vivo.

CONCLUSIONS AND IMPLICATIONS

This study supports a role for tyrosine kinases in PAR2-mediated receptor-operated gating of TRPV4 channels, independent of Gαq stimulation. The ability of a tyrosine kinase inhibitor to diminish PAR2-induced activation of TRPV4 channels and consequent mechanical hyperalgesia identifies bafetinib (which is in development in oncology) as a potential novel analgesic therapy.

Opioid receptors and cardioprotection - 'opioidergic conditioning' of the heart

Ischaemic heart disease (IHD) remains a major cause of morbidity/mortality globally, firmly established in Westernized or 'developed' countries and rising in prevalence in developing nations. Thus, cardioprotective therapies to limit myocardial damage with associated ischaemia-reperfusion (I-R), during infarction or surgical ischaemia, is a very important, although still elusive, clinical goal. The opioid receptor system, encompassing the δ (vas deferens), κ (ketocyclazocine) and μ (morphine) opioid receptors and their endogenous opioid ligands (endorphins, dynorphins, enkephalins), appears as a logical candidate for such exploitation. This regulatory system may orchestrate organism and organ responses to stress, induces mammalian hibernation and associated metabolic protection, triggers powerful adaptive stress resistance in response to ischaemia/hypoxia (preconditioning), and mediates cardiac benefit stemming from physical activity. In addition to direct myocardial actions, central opioid receptor signalling may also enhance the ability of the heart to withstand I-R injury. The δ- and κ-opioid receptors are strongly implicated in cardioprotection across models and species (including anti-infarct and anti-arrhythmic actions), with mixed evidence for μ opioid receptor-dependent protection in animal and human tissues. A small number of clinical trials have provided evidence of cardiac benefit from morphine or remifentanil in cardiopulmonary bypass or coronary angioplasty patients, although further trials of subtype-specific opioid receptor agonists are needed. The precise roles and utility of this GPCR family in healthy and diseased human myocardium, and in mediating central and peripheral survival responses, warrant further investigation, as do the putative negative influences of ageing, IHD co-morbidities, and relevant drugs on opioid receptor signalling and protective responses.

Opioid receptors and cardioprotection - 'opioidergic conditioning' of the heart

Ischaemic heart disease (IHD) remains a major cause of morbidity/mortality globally, firmly established in Westernized or 'developed' countries and rising in prevalence in developing nations. Thus, cardioprotective therapies to limit myocardial damage with associated ischaemia-reperfusion (I-R), during infarction or surgical ischaemia, is a very important, although still elusive, clinical goal. The opioid receptor system, encompassing the δ (vas deferens), κ (ketocyclazocine) and μ (morphine) opioid receptors and their endogenous opioid ligands (endorphins, dynorphins, enkephalins), appears as a logical candidate for such exploitation. This regulatory system may orchestrate organism and organ responses to stress, induces mammalian hibernation and associated metabolic protection, triggers powerful adaptive stress resistance in response to ischaemia/hypoxia (preconditioning), and mediates cardiac benefit stemming from physical activity. In addition to direct myocardial actions, central opioid receptor signalling may also enhance the ability of the heart to withstand I-R injury. The δ- and κ-opioid receptors are strongly implicated in cardioprotection across models and species (including anti-infarct and anti-arrhythmic actions), with mixed evidence for μ opioid receptor-dependent protection in animal and human tissues. A small number of clinical trials have provided evidence of cardiac benefit from morphine or remifentanil in cardiopulmonary bypass or coronary angioplasty patients, although further trials of subtype-specific opioid receptor agonists are needed. The precise roles and utility of this GPCR family in healthy and diseased human myocardium, and in mediating central and peripheral survival responses, warrant further investigation, as do the putative negative influences of ageing, IHD co-morbidities, and relevant drugs on opioid receptor signalling and protective responses.

Noble gases as cardioprotectants - translatability and mechanism

Several noble gases, although classified as inert substances, exert a tissue-protective effect in different experimental models when applied before organ ischaemia as an early or late preconditioning stimulus, after ischaemia as a post-conditioning stimulus or when given in combination before, during and/or after ischaemia. A wide range of organs can be protected by these inert substances, in particular cardiac and neuronal tissue. In this review we summarize the data on noble gas-induced cardioprotection, focusing on the underlying protective mechanisms. We will also look at translatability of experimental data to the clinical situation.

Signalling pathways and mechanisms of protection in pre- and postconditioning: historical perspective and lessons for the future

Ischaemic pre- and postconditioning are potent cardioprotective interventions that spare ischaemic myocardium and decrease infarct size after periods of myocardial ischaemia/reperfusion. They are dependent on complex signalling pathways involving ligands released from ischaemic myocardium, G-protein-linked receptors, membrane growth factor receptors, phospholipids, signalling kinases, NO, PKC and PKG, mitochondrial ATP-sensitive potassium channels, reactive oxygen species, TNF-α and sphingosine-1-phosphate. The final effector is probably the mitochondrial permeability transition pore and the signalling produces protection by preventing pore formation. Many investigators have worked to produce a roadmap of this signalling with the hope that it would reveal where one could intervene to therapeutically protect patients with acute myocardial infarction whose hearts are being reperfused. However, attempts to date to show efficacy of such an intervention in large clinical trials have been unsuccessful. Reasons for this inability to translate successes in the experimental laboratory to the clinical arena are evaluated in this review. It is suggested that all patients with acute coronary syndromes currently presenting to the hospital and being treated with platelet P2Y12 receptor antagonists, the current standard of care, are indeed already benefiting from protection from the conditioning pathways outlined earlier. If that proves to be the case, then future attempts to further decrease infarction will have to rely on interventions which protect by a different mechanism.

High-affinity σ1 protein agonist reduces clinical and pathological signs of experimental autoimmune encephalomyelitis

BACKGROUND AND PURPOSE

Selective agonists of the sigma-1 receptor (σ1 protein) are generally reported to protect against neuronal damage and modulate oligodendrocyte differentiation. Human and rodent lymphocytes possess saturable, high-affinity binding sites for compounds binding to the σ1 protein and potential immunomodulatory properties have been described for σ1 protein ligands. Experimental autoimmune encephalomyelitis (EAE) is recognized as a valuable model of the inflammatory aspects of multiple sclerosis (MS). Here, we have assessed the role of a σ1 protein agonist, containing the tetrahydroisoquinoline-hydantoin structure, in EAE.

EXPERIMENTAL APPROACH

EAE was induced in SJL/J female mice by active immunization with myelin proteolipid protein (PLP)139-151 peptide. The σ1 protein agonist was injected i.p. at the time of immunization (day 0). Disease severity was assessed clinically and by histopathological evaluation of the CNS. Phenotyping of B-cell subsets and regulatory T-cells were performed by flow cytometry in spleen and cervical lymph nodes.

KEY RESULTS

Prophylactic treatment of EAE mice with the σ1 protein agonist prevented mononuclear cell accumulation and demyelination in brain and spinal cord and increased T2 B-cells and regulatory T-cells, resulting in an overall reduction in the clinical progression of EAE.

CONCLUSIONS AND IMPLICATIONS

This σ1 protein agonist, containing the tetrahydroisoquinoline-hydantoin structure, decreased the magnitude of inflammation in EAE. This effect was associated with increased proportions of B-cell subsets and regulatory T-cells with potential immunoregulatory functions. Targeting of the σ1 protein might thus provide new therapeutic opportunities in MS.

Class A1 scavenger receptors in cardiovascular diseases

Class A1 scavenger receptors (SR-A1) are membrane glycoproteins that can form homotrimers. This receptor was originally defined by its ability to mediate the accumulation of lipids in macrophages. Subsequent studies reveal that SR-A1 plays critical roles in innate immunity, cell apoptosis and proliferation. This review highlights recent advances in understanding the structure, receptor pathway and regulation of SR-A1. Although its role in atherosclerosis is disputable, recent discoveries suggest that SR-A1 function in anti-inflammatory responses by promoting an M2 macrophage phenotype in cardiovascular diseases. Therefore, SR-A1 may be a potential target for therapeutic intervention of cardiovascular diseases.

HuR mediates the synergistic effects of angiotensin II and IL-1β on vascular COX-2 expression and cell migration

BACKGROUND AND PURPOSE

Angiotensin II (AngII) and IL-1β are involved in cardiovascular diseases through the induction of inflammatory pathways. HuR is an adenylate- and uridylate-rich element (ARE)-binding protein involved in the mRNA stabilization of many genes. This study investigated the contribution of HuR to the increased expression of COX-2 induced by AngII and IL-1β and its consequences on VSMC migration and remodelling.

EXPERIMENTAL APPROACH

Rat and human VSMCs were stimulated with AngII (0.1 μM) and/or IL-1β (10 ng · mL(-1)). Mice were infused with AngII or subjected to carotid artery ligation. mRNA and protein levels were assayed by quantitative PCR, Western blot, immunohistochemistry and immunofluorescence. Cell migration was measured by wound healing and transwell assays.

KEY RESULTS

In VSMCs, AngII potentiated COX-2 and tenascin-C expressions and cell migration induced by IL-1β. This effect of AngII on IL-1β-induced COX-2 expression was accompanied by increased COX-2 3' untranslated region reporter activity and mRNA stability, mediated through cytoplasmic HuR translocation and COX-2 mRNA binding. These effects were blocked by ERK1/2 and HuR inhibitors. VSMC migration was reduced by blockade of ERK1/2, HuR, COX-2, TXAS, TP and EP receptors. HuR, COX-2, mPGES-1 and TXAS expressions were increased in AngII-infused mouse aortas and in carotid-ligated arteries. AngII-induced tenascin-C expression and vascular remodelling were abolished by celecoxib and by mPGES-1 deletion.

CONCLUSIONS AND IMPLICATIONS

The synergistic induction of COX-2 by AngII and IL-1β in VSMCs involves HuR through an ERK1/2-dependent mechanism. The HuR/COX-2 axis participates in cell migration and vascular damage. HuR might be a novel target to modulate vascular remodelling.

Pharmacological methyl group donors block skeletal metastasis in vitro and in vivo

BACKGROUND AND PURPOSE

DNA hypomethylation was previously implicated in metastasis. In the present study, we examined whether methyl supplementation with the universal methyl donor S-adenosylmethionine (SAM) inhibits prostate cancer associated skeletal metastasis.

EXPERIMENTAL APPROACH

Highly invasive human prostate cancer cells PC-3 and DU-145 were treated with vehicle alone, S-adenosylhomocysteine (SAH) or SAM and their effects on tumour cell proliferation, invasion, migration and colony formation were monitored. For in vivo studies, control (SAH) and SAM-treated PC-3 cells were injected into the tibia of Fox chase SCID mice and skeletal lesions were determined by X-ray and μCT. To understand possible mechanisms involved, we delineated the effect of SAM on the genome-wide methylation profile of PC-3 cells.

KEY RESULTS

Treatment with SAM resulted in a dose-dependent inhibition of tumour cell proliferation, invasion, cell migration, colony formation and cell cycle characteristics. Animals injected with 250 μM SAM-treated cells developed significantly smaller skeletal lesions, which were associated with increases in bone volume to tumour volume ratio and connectivity density as well as decreased trabecular spacing. Genome-wide methylation analysis showed differential methylation in several key signalling pathways implicated in prostate cancer including the signal transducer and activator of transcription 3 (STAT3) pathway. A selective STAT3 inhibitor decreased tumour cell invasion, effects which were less pronounced as compared with SAM.

CONCLUSIONS AND IMPLICATIONS

These studies provide a possible mechanism for the role of DNA demethylation in the development of skeletal metastasis and a rationale for the use of hypermethylation pharmacological agents to impede the development and progression of skeletal metastasis.

MPTP-induced changes in hippocampal synaptic plasticity and memory are prevented by memantine through the BDNF-TrkB pathway

BACKGROUND AND PURPOSE

Mild cognitive deficit in early Parkinson's disease (PD) has been widely studied. Here we have examined the effects of memantine in preventing memory deficit in experimental PD models and elucidated some of the underlying mechanisms.

EXPERIMENTAL APPROACHES

I.p. injection of 1-methyl-4- phenyl-1,2,3,6-tetrahydro pyridine (MPTP) in C57BL/6 mice was used to produce models of PD. We used behavioural tasks to test memory. In vitro, we used slices of hippocampus, with electrophysiological, Western blotting, real time PCR, elisa and immunochemical techniques.

KEY RESULTS

Following MPTP injection, long-term memory was impaired and these changes were prevented by pre-treatment with memantine. In hippocampal slices from MPTP treated mice, long-term potentiation (LTP) -induced by θ burst stimulation (10 bursts, 4 pulses) was decreased, while long-term depression (LTD) induced by low-frequency stimulation (1 Hz, 900 pulses) was enhanced, compared with control values. A single dose of memantine (i.p., 10 mg·kg(-1) ) reversed the decreased LTP and the increased LTD in this PD model. Activity-dependent changes in tyrosine kinase receptor B (TrkB), ERK and brain-derived neurotrophic factor (BDNF) expression were decreased in slices from mice after MPTP treatment. These effects were reversed by pretreatment with memantine. Incubation of slices in vitro with 1-methyl-4-phenylpyridinium (MPP(+) ) decreased depolarization-induced expression of BDNF. This effect was prevented by pretreatment of slices with memantine or with calpain inhibitor III, suggesting the involvement of an overactivated calcium signalling pathway.

CONCLUSIONS AND IMPLICATIONS

Memantine should be useful in preventing loss of memory and hippocampal synaptic plasticity in PD models.

LPS exacerbates functional and inflammatory responses to ovalbumin and decreases sensitivity to inhaled fluticasone propionate in a guinea pig model of asthma

BACKGROUND AND PURPOSE

Asthma exacerbations contribute to corticosteroid insensitivity. LPS is ubiquitous in the environment. It causes bronchoconstriction and airway inflammation and may therefore exacerbate allergen responses. This study examined whether LPS and ovalbumin co-administration could exacerbate the airway inflammatory and functional responses to ovalbumin in conscious guinea pigs and whether these exacerbated responses were insensitive to inhaled corticosteroid treatment with fluticasone propionate (FP).

EXPERIMENTAL APPROACH

Guinea pigs were sensitized and challenged with ovalbumin and airway function recorded as specific airway conductance by whole body plethysmography. Airway inflammation was measured from lung histology and bronchoalveolar lavage. Airway hyper-reactivity (AHR) to inhaled histamine was examined 24 h after ovalbumin. LPS was inhaled alone or 24 or 48 h before ovalbumin and combined with ovalbumin. FP (0.05-1 mg·mL(-1) ) or vehicle was nebulized for 15 min twice daily for 6 days before ovalbumin or LPS exposure.

KEY RESULTS

Ovalbumin inhalation caused early (EAR) and late asthmatic response (LAR), airway hyper-reactivity to histamine and influx of inflammatory cells into the lungs. LPS 48 h before and co-administered with ovalbumin exacerbated the response with increased length of the EAR, prolonged response to histamine and elevated inflammatory cells. FP 0.5 and 1 mg·mL(-1) reduced the LAR, AHR and cell influx with ovalbumin alone, but was ineffective when guinea pigs were exposed to LPS before and with ovalbumin.

CONCLUSIONS AND IMPLICATIONS

LPS exposure exacerbates airway inflammatory and functional responses to allergen inhalation and decreases corticosteroid sensitivity. Its widespread presence in the environment could contribute to asthma exacerbations and corticosteroid insensitivity in humans.

Dose-dependent biphasic leptin-induced proliferation is caused by non-specific IL-6/NF-κB pathway activation in human myometrial cells

BACKGROUND AND PURPOSE

Leptin, an adipokine synthesized by the placenta during pregnancy, has been proposed for the management of preterm labour (PTL), as it is able to prevent in vitro uterine contractility and remodelling associated with labour onset. Another common feature of labour onset is the phenotypic switch of myometrial smooth muscle cells from a proliferative to a hypertrophic state. As proliferative effects have been demonstrated for leptin in other tissues, we aimed to investigate its ability to induce myometrial proliferation and thus to maintain uterine quiescence.

EXPERIMENTAL APPROACH

We stimulated human primary myometrial smooth muscle cells with leptin in the presence or absence of receptor antagonists or signalling pathway inhibitors.

KEY RESULTS

Leptin induced myometrial cell proliferation in a biphasic manner. At 6.25 ng · mL(-1), leptin-induced proliferation was mediated by the leptin receptor and required the early activation of ERK1/2. At a concentration above 25 ng · mL(-1), leptin induced direct non-specific stimulation of the IL-6 receptor, leading to NF-κB activation, and exerted anti-proliferative effects. However, at 50 ng · mL(-1), leptin re-induces proliferation via IL-6 receptor stimulation that requires STAT3 and delayed ERK1/2 activation.

CONCLUSIONS AND IMPLICATIONS

These data bring new insights into leptin signalling-induced myometrial proliferation and its interrelationship with the IL-6/IL-6 receptor axis. In the light of our previous work, the present study emphasizes the potential value of leptin in the pharmacological management of PTL and it also strengthens the hypothesis that leptin might be a contributory factor in the parturition-related disorders observed in obese women.

Ten things you should know about protein kinases: IUPHAR Review 14

Many human malignancies are associated with aberrant regulation of protein or lipid kinases due to mutations, chromosomal rearrangements and/or gene amplification. Protein and lipid kinases represent an important target class for treating human disorders. This review focus on 'the 10 things you should know about protein kinases and their inhibitors', including a short introduction on the history of protein kinases and their inhibitors and ending with a perspective on kinase drug discovery. Although the '10 things' have been, to a certain extent, chosen arbitrarily, they cover in a comprehensive way the past and present efforts in kinase drug discovery and summarize the status quo of the current kinase inhibitors as well as knowledge about kinase structure and binding modes. Besides describing the potentials of protein kinase inhibitors as drugs, this review also focus on their limitations, particularly on how to circumvent emerging resistance against kinase inhibitors in oncological indications.

GPCR-mediated EGF receptor transactivation regulates TRPV4 action in the vasculature

BACKGROUND AND PURPOSE

Transient receptor potential vanilloid-4 (TRPV4) is a calcium-permeant ion channel that is known to affect vascular function. The ability of TRPV4 to cause a vasoconstriction in blood vessels has not yet been mechanistically examined. Further in neuronal cells, TRPV4 signalling can be potentiated by GPCR activation. Thus, we studied the mechanisms underlying the vascular contractile action of TRPV4 and the GPCR-mediated potentiation of such vasoconstriction, both of which are as yet unappreciated aspects of TRPV4 function.

EXPERIMENTAL APPROACH

The mechanisms of TRPV4-dependent regulation of vascular tone in isolated mouse aortae were studied using wire myography. TRPV4-dependent calcium signalling and prostanoid production was studied in cultured human umbilical vein endothelial cells (HUVECs).

KEY RESULTS

In addition to the well-documented vasorelaxation response triggered by TRPV4 activation, we report here a TRPV4-triggered vasoconstriction in the mouse aorta that involves a COX-generated Tx receptor (TP) agonist that acts in a MAPK and Src kinase signalling dependent manner. This constriction is potentiated by activation of the GPCRs for angiotensin (AT1 receptors) or proteinases (PAR1 and PAR2) via transactivation of the EGF receptor and a process involving PKC. TRPV4-dependent vascular contraction can be blocked by COX inhibitors or with TP antagonists. Further, TRPV4 activation in HUVECs stimulated Tx release as detected by an elisa.

CONCLUSION AND IMPLICATIONS

We conclude that the GPCR potentiation of TRPV4 action and TRPV4-dependent Tx receptor activation are important regulators of vascular function and could be therapeutically targeted in vascular diseases.

3,3'-Diindolylmethane attenuates LPS-mediated acute liver failure by regulating miRNAs to target IRAK4 and suppress Toll-like receptor signalling

BACKGROUND AND PURPOSE

Acute liver failure (ALF) is a severe and potentially lethal clinical syndrome. 3,3'-Diindolylmethane (DIM) is a natural plant-derived compound with anti-cancer activities. Recently, DIM has also been shown to have anti-inflammatory properties. Here, we tested the hypothesis that DIM would suppress endotoxin-induced ALF.

EXPERIMENTAL APPROACH

We investigated the therapeutic potential of DIM in a mouse model of D-galactosamine/Lipopolysaccharide (GalN/LPS)-induced ALF. The efficacy of DIM treatment was assessed by survival, liver histopathology, serum levels of alanine transaminase, pro-inflammatory cytokines and number of activated liver macrophages. Effects of DIM on the expression of two miRNAs, 106a and 20b, and their predicted target gene were measured by qRT-PCR and Western blotting. Effects of DIM on the release of TNF-α from RAW264.7 macrophages transfected with mimics of these miRNAs and activated by LPS was assessed by elisa.

KEY RESULTS

DIM treatment protected mice from ALF symptoms and reduced the number of activated liver macrophages. DIM increased expression of miR-106a and miR-20b in liver mononuclear cells and decreased expression of their predicted target gene IL-1 receptor-associated kinase 4 (IRAK4), involved in signalling from Toll-like receptor 4 (TLR4). In vitro transfection of RAW264.7 cells using miRNA mimics of miR-106a and 20b decreased expression of IRAK4 and of TNF-α secretion, following LPS stimulation.

CONCLUSIONS AND IMPLICATIONS

DIM attenuated GalN/LPS-induced ALF by regulating the expression of unique miRNAs that target key molecules in the TLR4 inflammatory pathway. DIM may represent a potential novel hepatoprotective agent.

The interferon regulatory factors as novel potential targets in the treatment of cardiovascular diseases

The family of interferon regulatory factors (IRFs) consists of nine members (IRF1-IRF9) in mammals. They act as transcription factors for the interferons and thus exert essential regulatory functions in the immune system and in oncogenesis. Recent clinical and experimental studies have identified critically important roles of the IRFs in cardiovascular diseases, arising from their participation in divergent and overlapping molecular programmes beyond the immune response. Here we review the current knowledge of the regulatory effects and mechanisms of IRFs on the immune system. The role of IRFs and their potential molecular mechanisms as novel stress sensors and mediators of cardiovascular diseases are highlighted.

Glial cell line-derived neurotrophic factor-mediated enhancement of noradrenergic descending inhibition in the locus coeruleus exerts prolonged analgesia in neuropathic pain

BACKGROUND AND PURPOSE

The locus coeruleus (LC) is the principal nucleus containing the noradrenergic neurons and is a major endogenous source of pain modulation in the brain. Glial cell line-derived neurotrophic factor (GDNF), a well-established neurotrophic factor for noradrenergic neurons, is a major pain modulator in the spinal cord and primary sensory neurons. However, it is unknown whether GDNF is involved in pain modulation in the LC.

EXPERIMENTAL APPROACH

Rats with chronic constriction injury (CCI) of the left sciatic nerve were used as a model of neuropathic pain. GDNF was injected into the left LC of rats with CCI for 3 consecutive days and changes in mechanical allodynia and thermal hyperalgesia were assessed. The α2 -adrenoceptor antagonist yohimbine was injected intrathecally to assess the involvement of descending inhibition in GDNF-mediated analgesia. The MEK inhibitor U0126 was used to investigate whether the ERK signalling pathway plays a role in the analgesic effects of GDNF.

KEY RESULTS

Both mechanical allodynia and thermal hyperalgesia were attenuated 24 h after the first GDNF injection. GDNF increased the noradrenaline content in the dorsal spinal cord. The analgesic effects continued for at least 3 days after the last injection. Yohimbine abolished these effects of GDNF. The analgesic effects of GDNF were partly, but significantly, inhibited by prior injection of U0126 into the LC.

CONCLUSIONS AND IMPLICATIONS

GDNF injection into the LC exerts prolonged analgesic effects on neuropathic pain in rats by enhancing descending noradrenergic inhibition.

Autophagy: an emerging therapeutic target in vascular diseases

Autophagy is a cellular catabolic process responsible for the destruction of long-lived proteins and organelles via lysosome-dependent pathway. This process is of great importance in maintaining cellular homeostasis, and deregulated autophagy has been implicated in the pathogenesis of a wide range of diseases. A growing body of evidence suggests that autophagy can be activated in vascular disorders such as atherosclerosis. Autophagy occurs under basal conditions and mediates homeostatic functions in cells but in the setting of pathological states up-regulated autophagy can exert both protective and detrimental functions. Therefore, the precise role of autophagy and its relationship with the progression of the disease need to be clarified. This review highlights recent findings regarding autophagy activity in vascular cells and its potential contribution to vascular disorders with a focus on atherogenesis. Finally, whether the manipulation of autophagy represents a new therapeutic approach to treat or prevent vascular diseases is also discussed.

Differential activation of human constitutive androstane receptor and its SV23 and SV24 splice variants by rilpivirine and etravirine

BACKGROUND AND PURPOSE

Rilpivirine and etravirine are second-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs) indicated for the treatment of HIV/AIDS. The constitutive androstane receptor (CAR) regulates the expression of genes involved in various biological processes, including the transport and biotransformation of drugs. We investigated the effect of rilpivirine and etravirine on the activity of the wild-type human CAR (hCAR-WT) and its hCAR-SV23 and hCAR-SV24 splice variants, and compared it with first-generation NNRTIs (efavirenz, nevirapine, and delavirdine).

EXPERIMENTAL APPROACH

Receptor activation, ligand-binding domain (LBD) transactivation, and co-activator recruitment were investigated in transiently transfected, NNRTI-treated HepG2 cells. Nuclear translocation of green fluorescent protein-tagged hCAR-WT and CYP2B6 gene expression were assessed in NNRTI-treated human hepatocytes.

KEY RESULTS

Rilpivirine and etravirine activated hCAR-WT, but not hCAR-SV23 or hCAR-SV24, and without transactivating the LBD or recruiting steroid receptor coactivators SRC-1, SRC-2, or SRC-3. Among the first-generation NNRTIs investigated, only efavirenz activated hCAR-WT, hCAR-SV23, and hCAR-SV24, but none of them transactivated the LBD of these receptors or substantively recruited SRC-1, SRC-2, or SRC-3. Rilpivirine, etravirine, and efavirenz triggered nuclear translocation of hCAR-WT and increased hCAR target gene (CYP2B6) expression.

CONCLUSION AND IMPLICATIONS

NNRTIs activate hCAR-WT, hCAR-SV23, and hCAR-SV24 in a drug-specific and isoform-selective manner. The activation occurs by a mechanism that does not appear to involve binding to the LBD or recruitment of SRC-1, SRC-2, or SRC-3.

Δ(9) Tetrahydrocannabinol attenuates Staphylococcal enterotoxin B-induced inflammatory lung injury and prevents mortality in mice by modulation of miR-17-92 cluster and induction of T-regulatory cells

BACKGROUND AND PURPOSE

Staphylococcal enterotoxin B (SEB) is a potent activator of Vβ8+T-cells resulting in the clonal expansion of ∼30% of the T-cell pool. Consequently, this leads to the release of inflammatory cytokines, toxic shock, and eventually death. In the current study, we investigated if Δ(9) tetrahydrocannabinol (THC), a cannabinoid known for its anti-inflammatory properties, could prevent SEB-induced mortality and alleviate symptoms of toxic shock.

EXPERIMENTAL APPROACH

We investigated the efficacy of THC against the dual administration (intranasal and i.p.) of SEB into C3H/HeJ mice based on the measurement of SEB-mediated clinical parameters, including cytokine production, cellular infiltration, vascular leak, and airway resistance. In addition, the molecular mechanism of action was elucidated in vitro by the activation of splenocytes with SEB.

KEY RESULTS

Exposure to SEB resulted in acute mortality, while THC treatment led to 100% survival of mice. SEB induced the miRNA-17-92 cluster, specifically miRNA-18a, which targeted Pten (phosphatase and tensin homologue), an inhibitor of the PI3K/Akt signalling pathway, thereby suppressing T-regulatory cells. In contrast, THC treatment inhibited the individual miRNAs in the cluster, reversing the effects of SEB.

CONCLUSIONS AND IMPLICATIONS

We report, for the first time a role for the miRNA 17-92 cluster in SEB-mediated inflammation. Furthermore, our results suggest that THC is a potent anti-inflammatory compound that may serve as a novel therapeutic to suppress SEB-induced pulmonary inflammation by modulating critical miRNA involved in SEB-induced toxicity and death.

Physiological, pharmacological and toxicological considerations of drug-induced structural cardiac injury

The incidence of drug-induced structural cardiotoxicity, which may lead to heart failure, has been recognized in association with the use of anthracycline anti-cancer drugs for many years, but has also been shown to occur following treatment with the new generation of targeted anti-cancer agents that inhibit one or more receptor or non-receptor tyrosine kinases, serine/threonine kinases as well as several classes of non-oncology agents. A workshop organized by the Medical Research Council Centre for Drug Safety Science (University of Liverpool) on 5 September 2013 and attended by industry, academia and regulatory representatives, was designed to gain a better understanding of the gaps in the field of structural cardiotoxicity that can be addressed through collaborative efforts. Specific recommendations from the workshop for future collaborative activities included: greater efforts to identify predictive (i) preclinical; and (ii) clinical biomarkers of early cardiovascular injury; (iii) improved understanding of comparative physiology/pathophysiology and the clinical predictivity of current preclinical in vivo models; (iv) the identification and use of a set of cardiotoxic reference compounds for comparative profiling in improved animal and human cellular models; (v) more sharing of data (through publication/consortia arrangements) on target-related toxicities; (vi) strategies to develop cardio-protective agents; and (vii) closer interactions between preclinical scientists and clinicians to help ensure best translational efforts.

Advances in exploring the role of microRNAs in the pathogenesis, diagnosis and therapy of cardiac diseases in China

Cardiovascular disease has become the most serious health threat and represents the major cause of morbidity and mortality in China, as in other industrialized nations. During the past few decades, China's economic boom has tremendously improved people's standard of living but has also changed their lifestyle, increasing the prevalence of cardiovascular disease, the so-called 'disease of modern civilization'. This new trend has attracted a significant amount of research. Many of the studies conducted by Chinese investigators are orientated towards understanding the molecular mechanisms of cardiovascular disease. At the molecular level, the long-standing consensus is that cardiovascular disease is associated with a sequence mutation (genetic anomaly) and expression deregulation (epigenetic disorder) of protein-coding genes. However, new research data have established the non-protein-coding genes microRNAs (miRNAs) as a central regulator of the pathogenesis of cardiac disease and a potential new therapeutic target for cardiovascular disease. These small non-coding RNAs have also been subjected to extensive, rigorous investigations by Chinese researchers. Over the years, a large body of studies on miRNAs in cardiovascular disease has been conducted by Chinese investigators, yielding fruitful research results and a better understanding of miRNAs as a new level of molecular mechanisms for the pathogenesis of cardiac disease. In this review, we briefly summarize the current status of research in the field of miRNAs and cardiovascular disease in China, highlighting the advances made in elucidating the role of miRNAs in various cardiac conditions, including cardiac arrhythmia, myocardial ischaemia, cardiac hypertrophy and heart failure. We have also examined the potential of miRNAs as novel diagnostic biomarkers and therapeutic targets.

ABT-263 enhances sorafenib-induced apoptosis associated with Akt activity and the expression of Bax and p21((CIP1/WAF1)) in human cancer cells

BACKGROUND AND PURPOSE

Sorafenib, a potent inhibitor that targets several kinases associated with tumourigenesis and cell survival, has been approved for clinical treatment as a single agent. However, combining sorafenib with other agents improves its anti-tumour efficacy in various preclinical tumour models. ABT-263, a second-generation BH3 mimic, binds to the anti-apoptotic family members Bcl-2, Bcl-xL and Bcl-w, and has been demonstrated to enhance TNFSF10 (TRAIL)-induced apoptosis in human hepatocarcinoma cells. Hence, we investigated the effects of ABT-263 treatment combined with sorafenib.

EXPERIMENTAL APPROACH

The effects of ABT-263 combined with sorafenib were investigated in vitro, on cell viability, clone formation and apoptosis, and the mechanism examined using western blot and flow cytometry. This combination was also evaluated in vivo, in a mouse xenograft model; tumour growth, volume and weights were measured and a TUNEL assay performed.

KEY RESULTS

ABT-263 enhanced sorafenib-induced apoptosis while sparing non-tumourigenic cells. Although ABT-263 plus sorafenib significantly stimulated intracellular reactive oxygen species production and subsequent mitochondrial depolarization, this was not sufficient to trigger cell apoptosis. ABT-263 plus sorafenib significantly decreased Akt activity, which was, at least partly, involved in its effect on apoptosis. Bax and p21 (CIP1/WAF1) were shown to play a critical role in ABT-263 plus sorafenib-induced apoptosis. Combining sorafenib with ABT-263 dramatically increased its efficacy in vivo.

CONCLUSION AND IMPLICATIONS

The anti-tumour activity of ABT-263 plus sorafenib may involve the induction of intrinsic cell apoptosis via inhibition of Akt, and reduced Bax and p21 expression. Our findings offer a novel effective therapeutic strategy for tumour treatment.