Hiroyuki Eda

Proinflammatory cytokines, IL-1β and TNF-α, induce expression of interleukin-34 mRNA via JNK- and p44/42 MAPK-NF-κB pathway but not p38 pathway in osteoblasts

The aim of this study is to investigate the induction of interleukin-34 (IL-34) and macrophage colony-stimulating factor (M-CSF) mRNA by inflammatory cytokines and the involvement of mitogen-activated protein kinases (MAPKs) in this signaling pathway in human osteoblasts as both IL-34 and M-CSF bind to the same receptor c-FMS. Among four inflammatory cytokines [(IL-1β, IL-6, IL-17, and tumor necrosis factor-α (TNF-α)], IL-34 mRNA expression level was dramatically induced by IL-1β (17-fold) and TNF-α (74-fold). IL-1β and TNF-α activated the intracellular mitogen-activated protein kinases (MAPKs): p44/42 MAPK, p38, and c-Jun N-terminal kinase (JNK) as well as nuclear factor-κB (NF-κB) in osteoblasts. IL-1β- and TNF-α-mediated induction of IL-34 mRNA expression was decreased by JNK inhibitor. Interestingly, although treatment of MEK-1/2 inhibitor showed no reduction in the increase of IL-34 mRNA expression by cytokines, combination of MEK-1/2 inhibitor and JNK inhibitor significantly inhibited IL-1β- and TNF-α-mediated IL-34 mRNA expression level compared to those by each inhibitor alone. On the other hand, M-CSF mRNA expression level was significantly induced by both IL-1β and TNF-α by up to 7- and 11-fold, respectively. IL-1β- and TNF-α-mediated induction of M-CSF mRNA was not affected by p38, JNK, and MEK-1/2 inhibitors. However, NF-κB inhibitor completely inhibited the elevation of M-CSF mRNA expression by these cytokines. These results showed that proinflammatory cytokines, IL-1β and TNF-α, induced the expression of IL-34 mRNA via JNK and p44/42 MAPK but not p38 in human osteoblasts while p38, JNK, and p44/42 MAPK were not involved in the induction of M-CSF mRNA expression by these cytokines.

Macrophage-colony stimulating factor and interleukin-34 induce chemokines in human whole blood

The aim of this study is to investigate if macrophage-colony stimulating factor (M-CSF) or interleukin-34 (IL-34) induces cytokines or chemokines using human whole blood (HWB) and if an M-CSF- or IL-34-induced cytokine or chemokine production from HWB is inhibited by soluble M-CSF receptor or c-FMS kinase inhibitors. Among eight cytokines or growth factors tested, only IL-6 level was increased by up to 6-fold by M-CSF or IL-34 in HWB. In contrast, chemokine levels (IP-10/CXCL10, IL-8/CXCL8, and MCP-1/CCL2) were dramatically increased by M-CSF or IL-34 in HWB while exhibiting a large variation among donors. Variability of the MCP-1 signal induced by M-CSF or IL-34 was relatively less among donors compared to the IP-10 and IL-8 signals. The elevation of these chemokine levels was significantly decreased by soluble M-CSF receptor, indicating the elevation of these chemokines was mediated by M-CSF or IL-34. Furthermore, GW2580, a c-FMS kinase inhibitor, inhibited the induction of MCP-1 by M-CSF or IL-34 in a concentration dependent manner. These indicate MCP-1 is the most appropriate chemokine target for a chemokine release assay to evaluate the potency of c-FMS kinase inhibitors and MCP-1 release assay using HWB would be useful, relevant tool for translational pharmacology of c-FMS kinase inhibitors.

Critical role for apoptosis signal-regulating kinase 1 in the development of inflammatory K/BxN serum-induced arthritis

In this report, we show that apoptosis signal-regulating kinase 1(-/-) (ASK1 KO) mice were resistant to inflammatory arthritis induced in the K/BxN serum transfer model of rheumatoid arthritis (RA). The p38 inhibitor, SD-0006 was administered to wild type (WT) mice as a comparator. Both ASK1 KO and p38 inhibition resulted in marked attenuation of edema, cartilage damage, bone resorption, and general inflammatory responses. Transcriptional profiling of mRNA prepared from paw tissue demonstrated that the production of many proinflammatory genes including cytokines, chemokines, and extracellular matrix degradative enzymes were maintained at basal levels by either ASK1 KO or prophylactic p38 MAPK inhibition. In the mouse whole blood (MWB) assay, tumor necrosis factor-α (TNF-α)-induced KC and CCL2 levels and also LPS-induced interleukin-6 (IL-6), CCL2, and KC levels in MWB from ASK1 KO were significantly lower than those from WT. Furthermore, both p38 and JNK were activated by TNF-α in human synovial fibroblasts isolated from RA patients (RASF). SD-0006 or SP600125, a JNK inhibitor, partially blocked the elevation of IL-6 production in RASF following stimulation with TNF-α. In contrast, dual inhibition with both p38/JNK inhibitors almost completely abolished TNF-α-induced IL-6 production from these cells. Ablation of ASK1 expression in RASF using siRNA for ASK1 resulted in inhibition of TNF-α-induced IL-6 and PGE(2) production. This study is the first to suggest that ASK1 is critical for the development of RA and that ASK1 may be involved in the production of proinflammatory mediators in response to TNF-α stimulation in the RA joint.

Interleukin-1β-induced interleukin-6 production in A549 cells is mediated by both phosphatidylinositol 3-kinase and interleukin-1 receptor-associated kinase-4

The aim of this study is to investigate whether PI3K (phosphatidylinositol‐3‐kinase) is involved in IL‐1β (interleukin‐1β)‐induced IL‐6 production in A549 (human lung adenocarcinoma epithelial cell) and human RASF (rheumatoid arthritis synovial fibroblast). PI3K inhibitor, LY294002 significantly reduced IL‐1β‐induced IL‐6 production in A549 cells but not in RASF, indicating that IL‐1β‐induced IL‐6 production was partially mediated by PI3Kin A549 cells but not in RASF. siRNA (small interfering RNA) of IRAK4 (IL‐1 receptor‐associated kinase 4) treatment decreased IRAK4 mRNA level by up to 90% in A549 cells. In this condition, IL‐1β‐induced increase of IL‐6 mRNA and protein level was decreased by up to 93% and 70%, respectively. Furthermore, the combination of IRAK4 siRNA and LY294002 treatment decreased protein induction level of IL‐6 in A549 cells compared with that of IRAK4 siRNA or LY294002 alone. These results indicate that IL‐1β‐induced IL‐6 production in A549 cells is mediated by both PI3K and IRAK4 and suggest that involvement of PI3K in the IL‐1‐induced IL‐6 production is cell type specific.

Apoptosis signal-regulating kinase 1 is crucial for oxidative stress-induced but not for osmotic stress-induced hepatocyte cell death

AIMS In this study, we investigated the involvement of apoptosis signal-regulating kinase 1 (ASK1) in oxidative stress and osmotic stress-induced hepatocyte death. MAIN METHODS Activation of ASK1-JNK/p38 cascade and resulting cell death induced by oxidative and osmotic stress was investigated by Western immunoblot analysis and cell toxicity assay using human hepatoma cell lines, Huh7 expressing high level of ASK1 and HepG2 cells expressing low level of ASK1. Gene knock-down of ASK1 using shRNA against ASK1 was conducted using mouse hepatocyte cell line, AML12. KEY FINDINGS Activation of ASK1-JNK/p38 cascade and cell death in Huh7 expressing high level of ASK1 was markedly induced by the oxidative stress. HepG2 expressing low level of ASK1 was resistant to oxidative stress while cell death induced by osmotic stress was comparable between Huh7 and HepG2 cells. Although the phosphorylation of ASK1 was not observed by osmotic stress, the phosphorylation of p38 and JNK and resulting cell death was induced in both cell lines. The phosphorylation of ASK1 and p38/JNK in the mouse primary hepatocyte were also increased by oxidative stress. Knock-down of ASK1 mRNA in AML12 in vitro significantly reduced oxidative stress-induced cell death, however, knock-down of ASK1 in cells did not affect the osmotic stress-induced cell death. SIGNIFICANCE This study revealed that ASK1 regulates oxidative stress- but not osmotic stress-induced hepatocyte death, suggesting ASK1 plays a critical role in oxidative-stress induced hepatocyte death. These results raise the possibility that an ASK1 may be a promising therapeutic target for liver diseases caused by oxidative stress.

In vitro and in vivo pharmacological characterization of PF-01354082, a novel partial agonist selective for the 5-HT4 receptor

The pharmacological profile of PF-01354082, a selective 5-HT(4) receptor partial agonist, was investigated. PF-01354082 displayed high affinity for human 5-HT(4d) and dog 5-HT(4h) receptors in binding studies, having Ki values of 2.0 nM and 4.2 nM, respectively. By contrast, PF-01354082 did not show significant affinity for several other 5-HT receptors (5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2B), 5-HT(2C), 5-HT(3A), and 5-HT(7)) or the dopamine D(2long) receptor. Functional assays using either cells expressing human recombinant 5-HT(4d) receptors or rat tunica muscularis mucosae demonstrated that PF-01354082 exhibited partial agonist activity at the 5-HT(4) receptor. The effects of PF-01354082 on in vitro receptor binding, ion channel activity, and sites of uptake were further investigated. PF-01354082 did not show biologically relevant binding activity at concentrations up to 10 microM except for binding to the 5-HT(4e) receptor. Furthermore, PF-01354082 decreased I(HERG) current by only 11% at a concentration of 300 microM, indicating that the compound had greater than 150,000-fold selectivity for the human 5-HT(4d) receptor over hERG channels. An in vivo study using a gastric motility model in conscious dogs demonstrated that oral administration of PF-01354082 resulted in marked and sustained stimulation of gastric motility in a dose-dependent manner. These results indicate that PF-01354082 is an orally active, highly selective, partial agonist of the human 5-HT(4) receptor that is expected to exert a favorable effect on gastrointestinal motor disorders with reduced adverse effects mediated by other related receptors.

Selective CB1 cannabinoid receptor antagonist, SR141716A, attenuates liver injury induced by Concanavalin A

Aim:  The aim of this study was to investigate the hepatoprotective activity of a selective cannabinoid receptor 1 (CB1) antagonist, SR141716A, in a Concanavalin A (Con A)‐induced mouse liver injury model and to determine whether SR141716A has an effect on the production of inflammatory cytokines and chemokines induced by Con A.

Synthesis and structure-activity relationships of oxamyl dipeptide caspase inhibitors developed for the treatment of liver disease.

The P4 region of a series of oxamyl dipeptide caspase inhibitors was optimized by the combination of anti-apoptotic activity in the Jurkat/Fas (JFas) cellular assay and membrane permeability in the PAMPA assay. Two highly potent anti-apoptotic agents with moderate membrane permeability, 29 and 36, showed strong in vivo efficacy in a murine model of alpha-Fas-induced liver injury.

Pharmacological characterization and determination of pharmacokinetic and pharmacodynamic relationship of PF-00885706, a novel partial agonist selective for the 5-HT4 receptor

The pharmacological profile of PF-00885706, a selective 5-HT(4) receptor partial agonist, was investigated. PF-00885706 displayed a high binding affinity for the human 5-HT(4d) receptor with a K(i) of 3.7 nM that translates to functional agonist activity in vitro with EC(50) values of 4.0 nM and 6.6 nM in cell-based assays of human recombinant 5-HT(4d) receptors and rat tunica muscularis mucosae tissues, respectively. In both assays, partial agonism was confirmed with E(max) values of 84% and 78%, respectively. Notably, PF-00885706 was highly selective, displaying >1000-fold higher affinity for 5-HT(4d) receptors compared to 5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), 5-HT(2B), 5-HT(2C), 5-HT(3), 5-HT(7), and D(2long) receptors. Furthermore, in vitro binding assays demonstrated that PF-00885706 had no biologically significant interaction with physiologically important enzymes, ion channels including hERG channel, or receptors at concentrations up to 10 microM except for binding to the sigma(2) receptor. PF-00885706 exhibited weak binding affinity for the sigma(2) receptor yielding a K(i) value of 3 microM, which is more than 800-fold weaker than that for the 5-HT(4d) receptor. Oral administration of PF-00885706 to dogs resulted in marked and long-lasting stimulation of gastric motility with a minimum effective dose of 0.001 mg/kg. Pharmacokinetic analysis revealed that PF-00885706 has a low to moderate volume of distribution and the complete absorption in dogs. Pharmacokinetic and pharmacodynamic analysis of PF-00885706 in the dog gastric motility model showed a correlation between plasma concentrations and enhancement of gastric motility. Thus, PF-00885706 is an orally active, highly selective partial agonist for 5-HT(4) receptors that is expected to be effective for the treatment with gastrointestinal dysmotility disorders with reduced adverse effects mediated by other related receptors.