Keisuke Yamaguchi

Human substance P receptor lacking the C‐terminal domain remains competent to desensitize and internalize

Substance P receptor (SPR) and its naturally occurring splice‐variant, lacking the C‐terminal tail, are found in brain and spinal cord. Whether C‐terminally truncated SPR desensitizes like full‐length SPR is controversial. We used a multivaried approach to determine whether human SPR (hSPR) and a C‐terminally truncated mutant, hSPRΔ325, differ in their desensitization and internalization. In HEK‐293 cells expressing either hSPRΔ325 or hSPR, SP‐induced desensitization of the two receptors was similar when measured by inositol triphosphate accumulation or by transient translocation of coexpressed PKCβII‐GFP to the plasma membrane. Moreover, translocation of β‐arrestin 1 or 2‐GFP (βarr1‐GFP or βarr2‐GFP) to the plasma membrane, and receptor internalization were also similar. However, hSPR and hSPRΔ325 differ in their phosphorylation and in their ability to form β‐arrestin‐containing endocytic vesicles. Unlike hSPR, hSPRΔ325 is not phosphorylated to a detectable level in intact HEK293 cells, and whereas hSPR forms vesicles containing either βarr1‐GFP or βarr2‐GFP, hSPRΔ325 does not form any vesicles with βarr1‐GFP, and forms fewer vesicles with βarr2‐GFP. We conclude that truncated hSPR undergoes agonist‐dependent desensitization and internalization without detectable receptor phosphorylation.

Signal transduction through substance P receptor in human glioblastoma cells: roles for Src and PKCδ

Substance P receptor (SPR), a G protein-coupled receptor (GPCR), is found in human glioblastomas, and has been implicated in their growth. Consistent with a role for SPR in cell growth, activation of SPR in U373 MG human glioblastoma cells leads to the phosphorylation of mitogen-activated protein kinases [extracellular signal-regulated kinase 1 and 2 (ERK1/2)] and stimulation of cell proliferation. The purpose of the present study was to elucidate the pathway through which these actions occur. Using either the epidermal growth factor receptor (EGFR) kinase inhibitor, AG 1478, or a small-interfering RNA (siRNA) directed against human EGFR, we found that transactivation of EGFR by SPR is only marginally involved in SP-dependent ERK1/2 phosphorylation. Src, however, is shown to be a major component of SPR signaling because the Src kinase inhibitor, PP2, and a kinase-dead Src mutant both inhibit SP-dependent ERK1/2 phosphorylation. We also report that SPR stimulates the phosphorylation of protein kinase Cδ(PKCδ), and that this stimulation is blocked by PP2. SP-dependent ERK1/2 phosphorylation is also blocked by rottlerin, a PKCδ inhibitor, and the calcium scavenger, BAPTA/AM. Finally, rottlerin and PP2 were both found to inhibit the growth of several glioblastoma cell lines, underscoring the potential of these agents to block glioblastoma growth.

Substance P receptor in U373 MG human astrocytoma cells activates mitogen-activated protein kinases ERK1/2 through Src.

Substance P (SP) acting through substance P receptor (SPR) increases the proliferation of glioblastoma cells. At the molecular level, stimulation of SPR in human U373 MG glioblastoma cells results in phosphorylation of mitogen-activated protein kinases ERK1/2. Examination of the underlying mechanism reveals that SPR mediates ERK1/2 phosphorylation in a calcium-dependent manner. Surprisingly, blockade of epidermal growth factor receptor (EGFR), which is transactivated by SPR, has a minimal effect on SPR-mediated ERK1/2 phosphorylation. However, SPR-mediated ERK1/2 phosphorylation is significantly reduced by the Src kinase inhibitor PP2. Interestingly, ERK1/2 in U373 MG cells is also activated by several other mitogenic G protein-coupled receptors (GPCRs) including α1B-adrenergic, M3-muscarinic, and H1-histaminergic in an Src-dependent manner. We conclude that c-Src is a mediator of SP-stimulated ERK1/2 phosphorylation in human U373 MG glioblastoma cells.

Effect of olprinone, a phosphodiesterase III inhibitor, on hepatic ischemia-reperfusion injury in rats.

I/R injury is the main cause for hepatic dysfunction and failure after liver transplantation and liver resection. Therefore, reduction of I/R injury is the most important goal to improve the outcome of these procedures. Olprinone is a newly developed selective phosphodiesterase III inhibitor, which has been reported to ameliorate renal I/R injury in rats. However, no clear evidence for the actions of olprinone on inflammatory response after hepatic I/R injury has been disclosed thus far. Our study was designed to evaluate the action of olprinone on the hepatic I/R injury in rats. Olprinone increased the cyclic adenosine monophosphate level in injured liver tissue and ameliorated the liver injury after hepatic I/R. Moreover, olprinone suppressed the activation of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and nuclear factor-&kgr;B, cytokine production (TNF-&agr;, IL-6, and cytokine-induced neutrophil chemoattractant factor 1), and intercellular adhesion molecule 1 expression in liver after hepatic I/R. These observations suggest that olprinone protects liver against I/R injury via the elevation of cyclic adenosine monophosphate level and suppression of intercellular adhesion molecule 1 expression and cytokine production (TNF-&agr;, IL-6, and cytokine-induced neutrophil chemoattractant factor 1), possibly by interfering with the signaling pathways of p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and nuclear factor-&kgr;B in rats.

Effects of anesthesia with sevoflurane and propofol on the cytokine/chemokine production at the airway epithelium during esophagectomy.

Post-operative pulmonary complications such as pneumonia, acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are closely associated with morbidity and mortality after esophagectomy. One lung ventilation (OLV) is commonly used during esophagectomy. However, the effect of the anesthetic agents on the inflammatory response induced by OLV has yet to be evaluated, particularly during esophagectomy, which causes several complications in the lung. The aim of the present study was to determine the effects of anesthetic agents, such as sevoflurane or propofol, on the inflammatory reactions at the airway. Twenty patients undergoing esophagectomy were randomized to receive either sevoflurane (n=10) or propofol (n=10) as a main anesthetic agent. Epithelial lining fluid (ELF) was obtained from ventilated‑dependent lung (DL) and collapsed non-dependent lung (NDL) by a bronchoscopic microsampling method. The levels of inflammatory cytokines and chemokine [tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, IL-10 and IL-12p70] in the ELF were measured using multiplexed bead-based immunoassays before and after OLV. The results indicated that the levels of IL-6 in ELF were significantly increased in both the ventilated DL and collapsed NDL after OLV compared with the levels prior to OLV in the sevoflurane group. By contrast, there was no significant change in the IL-6 levels in the propofol group in the ventilated DL and collapsed NDL before and after OLV. Similarly, IL-8 levels were markedly increased in the ventilated DL and collapsed NDL after OLV compared with those before OLV in the sevoflurane group, whereas there was no significant change in IL-8 levels in the propofol group in the ventilated DL and collapsed NDL before and after OLV. In contrast to the changes in IL-6 and IL-8 levels, levels of IL-10, an anti-inflammatory cytokine, were not obviously changed in both the ventilated DL and collapsed NDL before and after OLV in the sevoflurane group. However, IL-10 levels in the propofol group were increased in the ventilated DL and collapsed NDL after OLV compared with those before OLV. Of note, the levels of TNF-α, IL-1β and IL-12p70 in ELF were below the detection limits. These observations suggested that propofol anesthesia more potently suppresses the surgical stress-induced inflammatory perturbation at the local milieu of the airway during esophagectomy compared with sevoflurane anesthesia.

Sevoflurane suppresses tumour necrosis factor-α-induced inflammatory responses in small airway epithelial cells after anoxia/reoxygenation

BACKGROUND Lung ischaemia-reperfusion (I/R) injury is correlated with poor clinical outcome. The inflammatory cytokines interleukin (IL)-6, IL-8, and monocyte chemotactic protein-1 (MCP-1) are produced by pulmonary epithelial cells during lung transplantation and are considered to be involved in I/R injury. The volatile anaesthetic sevoflurane has been shown to exert a protective effect on I/R injury in various organs. We investigated the effect of sevoflurane on the inflammatory functions of pulmonary epithelial cells in vitro. METHODS Human normal small airway epithelial cells (SAEC) were incubated under anoxic conditions for 24 h with or without sevoflurane and then stimulated with tumour necrosis factor (TNF)-α under hyperoxic conditions for 5 h with or without sevoflurane. After incubation, IL-6, IL-8, and MCP-1 mRNA expression was analysed by quantitative real-time RT-PCR. The production of IL-6, IL-8, and MCP-1 was assayed by enzyme-linked immunosorbent assay, the effects of sevoflurane on inflammatory gene expression were examined by DNA microarray analysis, and the effects of sevoflurane on NF-κB-mediated inflammatory cytokine production were examined by immunoblotting. RESULTS Sevoflurane suppressed TNF-α-induced IL-6, IL-8, and MCP-1 gene expression and the production of IL-6 and IL-8 in SAEC under anoxia/reoxygenation conditions. DNA microarray analysis indicated that sevoflurane modulated NF-κB-related gene expression. Sevoflurane significantly inhibited TNF-α-induced translocation of p65 NF-κB into the nucleus. Sevoflurane enhanced TNF-α-induced gene expression of inhibitor κB (IκB) but not of NF-κB. CONCLUSIONS Sevoflurane suppressed the NF-κB-mediated production of pulmonary epithelial cell-derived inflammatory cytokines, including IL-6 and IL-8, which are capable of causing I/R injury.

Effects of sivelestat on bronchial inflammatory responses after esophagectomy.

Post-operative pulmonary complications such as systemic inflammatory response syndrome (SIRS), acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are strongly associated with morbidity and mortality after esophagectomy. Post-operative administration of sivelestat sodium hydrate (sivelestat), a selective inhibitor of neutrophil elastase (NE), has been shown to improve the post-operative clinical course after esophagectomy. This study aimed to evaluate the effect of prophylactic administration of sivelestat on bronchial inflammatory responses. We randomized 24 patients into two groups. One group received 0.2 mg/kg/h sivelestat from the induction of anesthesia to post-operative day 1 (sivelestat group) and the other group received the same amount of physiological saline (control group). Bronchial alveolar epithelial lining fluid (ELF) samples were obtained from both groups at the induction of anesthesia and at the end of surgery. The serum and ELF levels of interleukin (IL)-6 and IL-8 were measured by enzyme-linked immunosorbent assay, and NE activity was spectrophotometrically determined using the same samples. Although IL-6 levels in the ELF significantly increased at the end of surgery compared with the pre-operative levels in both groups, the IL-8 levels and NE activity did not significantly increase at the end of the surgery compared to the corresponding pre-operative values in the sivelestat group. Moreover, IL-8 levels and NE activity in the ELF were significantly reduced at the end of surgery in the sivelestat group compared with corresponding values in the control group. The durations of ALI and ARDS were apparently shorter in the sivelestat group and the duration of SIRS was significantly shorter in the sivelestat group compared to the control group. We demonstrated that prophylactic use of sivelestat mitigated bronchial inflammation by suppressing NE activity and IL-8 levels in the ELF and shortened the duration of SIRS after transthoracic esophagectomy.

Effects of nitrous oxide on the production of cytokines and chemokines by the airway epithelium during anesthesia with sevoflurane and propofol

The aim of this study was to evaluate the effects of nitrous oxide (a gaseous anesthetic) on the in vivo production of inflammatory cytokines and chemokines by the airway epithelium, when combined with sevoflurane or propofol. Subjects undergoing simple or segmental mastectomy were randomly assigned to the sevoflurane and nitrous oxide, sevoflurane and air, propofol and nitrous oxide, or propofol and air group (all n=13). Epithelial lining fluid (ELF) was obtained using the bronchoscopic microsampling method prior to and following the mastectomy to enable measurement of the pre- and post-operative levels of certain inflammatory cytokines and chemokines using a cytometric bead array system. Notably, the levels of interleukin (IL)-1β, IL-8 and monocyte chemotactic protein-1 (MCP-1) in the ELF were significantly increased following the operations which involved the inhalation of sevoflurane and nitrous oxide, although the levels of these molecules were not significantly changed by the inhalation of sevoflurane and air. Furthermore, the IL-12p70 levels were significantly reduced in the ELF following the operations that involved the inhalation of sevoflurane and air, although the IL-12p70 levels were not significantly changed by the inhalation of nitrous oxide and sevoflurane. These observations suggest that the combination of sevoflurane and nitrous oxide induces an inflammatory response (increased production of IL-1β, IL-8 and MCP-1) and suppresses the anti-inflammatory response (reduced production of IL-12p70) in the local milieu of the airway. Thus, the combination of these compounds should be carefully administered for anesthesia.

Additive effect of sirolimus and anti‐death receptor 5 agonistic antibody against hepatocellular carcinoma

Despite careful patient selection, hepatocellular carcinoma (HCC) recurs in 10–20% of cases after liver transplantation, and the use of potent adjuvant anticancer drugs would be welcome. The aim of this study was to evaluate the efficiency of a combined therapy of rapamycin (sirolimus) and anti‐death receptor (DR)5 monoclonal antibody (mAb) on HCC.

Anti‑inflammatory actions of gabapentin and pregabalin on the substance P‑induced mitogen‑activated protein kinase activation in U373 MG human glioblastoma astrocytoma cells

Gabapentin (GBP) and pregabalin (PGB) exert antinociceptive effects on chronic nociceptive responses with neuropathic or inflammatory conditions. Furthermore, it is considered that GBP and PGB exhibit anti‑inflammatory effects by modulating the substance P (SP)‑mediated neurokinin‑1 receptor (NK1R; a SP receptor) response. Thus, in the present study, the effects of GBP and PGB on SP‑induced activation were investigated in the human glioblastoma astrocytoma U373 MG cell line, which expresses high levels of functional high‑affinity NK1R, and produces interleukin (IL)‑6 and IL‑8 in response to SP. The results indicated that GBP and PGB suppressed the SP‑induced production of IL‑6, and IL‑8 in U373 MG cells. Furthermore, GBP and PGB inhibited the SP‑induced phosphorylation of p38 mitogen‑activated protein kinase (MAPK) and nuclear factor (NF)‑κB, and the nuclear translocation of NF‑κB in U373 MG cells. Together, these observations suggest that GBP and PGB likely prevent SP‑induced IL‑6 and IL‑8 production in U373 MG cells via the inhibition of signaling molecules, including p38 MAPK and NF‑κB, thereby exhibiting antineuroinflammatory effects.