Akihiko Kimura

Wakayama Medical University, Wakayama, Wakayama, Japan

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Publications (89)304.26 Total impact

  • Article: ID: 91

    No preview · Article · Nov 2015 · Cytokine
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    ABSTRACT: Gender is one of the essential factors in the development of various diseases and poisoning. Therefore, we herein examined gender differences in sodium arsenite (NaAsO2)-induced acute renal dysfunction. When male and female BALB/c mice were subcutaneously injected with NaAsO2 (12.5mg/kg), serum and urinary markers for proximal tubular injury were significantly higher in female mice than in male mice. NaAsO2-induced histopathological alterations were consistently more evident in females than in males. Ovariectomy, but not orchiectomy significantly attenuated NaAsO2-induced renal injury. These results imply that the hypersusceptibility of female mice is attributed to estrogen signals. NaAsO2 suppressed the autophagic flux in tubular cells through the activation of ERK. Enhancements in the activation of ERK were significantly greater in females than in males, with the eventual accumulation of LC3-II and P62 in the kidneys, implying that the autophagic flux is impaired in females. The IL-6/STAT3 signaling pathway had protective roles in NaAsO2-induced nephrotoxicity through the suppression of ERK activation. Despite the absence of differences in intrarenal IL-6 expression between male and female mice, STAT3 was less activated with enhanced SOCS3 expression in females than in males. An in vitro study using mProx24 cells revealed that the estrogen treatment induced SOCS3 expression, and eventually suppressed the autophagic flux, as evidenced by greater increases in the accumulation of LC3-II and p62 with ERK activation, which was canceled by the knockdown of Socs3 . Collectively, these results indicate that estrogen has a negative impact on the development of NaAsO2 nephrotoxicity through its suppression of the autophagic flux.
    No preview · Article · Nov 2015 · Toxicology
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    ABSTRACT: Ovarian cancer is the major cause of cancer death among female genital malignancies, and requires developing novel therapeutic measures. Immune escape and acquisition of tolerance by tumor cells are essential to cancer growth and progression. An immunoregulatory enzyme indoleamine 2, 3-dioxygenase (IDO) overexpression in tumors is essential for host immune tolerance. Janus-activated kinase-signal transducer and activator of transcription (JAK-STAT) pathway is involved in various kinds of tumor biology. Thus, we examined the effects of STAT1 inhibition by AG490 (a JAK2 inhibitor) on ovarian cancer progression in mice. In vitro study, IFN-γ treatment up-regulated Ido mRNA expression with STAT1 activation in OV2944-HM-1 cells, whereas AG490 treatment significantly inhibited this effect with the suppression of STAT1 phosphorylation. In vivo model, OV2944-HM-1 cells were intraperitoneally/subcutaneously transplanted into syngeneic immunocompetent female mice. AG490 treatment significantly suppressed subcutaneous tumor growth, compared with control. Consistently, in mice intraperitoneally inoculated HM-1 cells, the same treatment significantly improved survival rate with the reduced number of intraperitoneal tumors. Actually, intratumoral IDO expression was significantly suppressed with the reduction of STAT1 activation in AG490-treated mice. Moreover, in tumor microenvironment of mice treated with AG490, the accumulation of anti-tumor leukocytes such as CD8(+)T-cells, M1 macrophages, and NK cells was apparently exaggerated with the reciprocal reduction of regulatory T cells. Furthermore, intratumoral expression of anti-tumor cytokines such as IL-1α, IL-1β and IL-12 expression was significantly enhanced in mice treated with AG490. Collectively, JAK/STAT signal pathways may be good molecular target for immunotherapy of ovarian cancer.
    No preview · Article · Sep 2015 · European journal of pharmacology
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    ABSTRACT: Endothelial progenitor cells (EPCs), a newly identified cell type, are bone marrow-derived progenitor cells that co-express stem cell markers and vascular endothelial growth factor (VEGF) receptor (Flk-1). In this study, a double-color immunofluorescence analysis was carried out using anti-CD34 and anti-Flk-1 antibodies to examine the time-dependent appearance of EPCs, using 52 human skin wounds with different wound ages (Group I, 0-1 days; Group II, 2-6 days; Group III, 7-14 days; and Group IV, 17-21 days). In wound specimens with an age of less than one day, CD34(+)/Flk-1(+) EPCs were not detected. EPCs were initially observed in wounds aged two days, and their number was increased in lesions with advances in wound age. In morphometrical analysis, the average number of EPCs was the highest in the wounds of Group III. Especially, 20 out of 21 wounds aged 7-12 days had >20 EPCs, and all wound samples with postinfliction intervals of 14-21 days had <15 EPCs. These observations at least showed that >20 EPCs would indicate a wound age of 7-12 days. Taken together, our observations indicate the detection of EPCs would be useful for wound age determination.
    No preview · Article · Apr 2015 · Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin
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    ABSTRACT: Detection of vitality of mechanical wounds in human cadavers is one of the important issues in forensic medicine. In order to explore novel markers for vitality of acute mechanical wounds, we investigated autophagy in mouse and human skin wounds. Western blotting analysis of mouse skin wounds showed marked reduction of LC3-II and reciprocal increase of p62 in wound samples with the postinfliction intervals of ≥0.5 h, compared with the uninjured skin tissues. These observations indicated that autophagy level was reduced in the wound sites. In postmortem wound samples, there were no remarkable changes in LC3-II and p62 levels. Furthermore, the postmortem intervals of 1-4 days have no significant effects on the changes of LC3-II and p62 in the antemortem skin wounds. Like murine wound samples, these alterations of LC3-II and p62 could be detected in human skin wound samples. Collectively, our study using animal and human samples implied that the detection of autophagy-related molecules such as LC3-II and p62 might be useful for forensic practice as markers of wound vitality.
    No preview · Article · Mar 2015 · Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin
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    ABSTRACT: We performed immunohistochemical study combined with morphometrical analyses in order to examine the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 using 55 human skin wounds of different ages: group I, 0-3 days (n = 16); II, 4-7 days (n = 11); III, 9-14 days (n = 16); and IV, 17-21 days (n = 12). Immunopositive reactions for MMP-2 were observed in all human skin specimens including uninjured skin as control. The number of MMP-2(+) macrophages was significantly increased in accordance with wound ages. In contrast to MMP-2, no MMP-9(+) signals were detected in uninjured and wound specimens aged less than 1 day. However, the number of MMP-9(+) macrophages profoundly appeared in groups II and III. Morphometrically, in all of wound samples aged 9-12 days, MMP-2(+) cell number was more than 20. On the contrary, most of the remaining samples had <20 positive cells. However, only one sample (a 7-day-old wound) showed 21 positive cells. Thus, with regard to practical applicability with forensic safety, MMP-2(+) macrophages of >20 would indicate a wound age of 7-12 days. Additionally, 10 out of 12 wound specimens aged 9-12 days showed the MMP-2(+) cell number of >25, implying that MMP-2(+) cell number of >25 would indicate the wound age of 9-12 days. On the contrary, all wound samples aged 3-14 days except for only one sample had MMP-9(+) cell number of >30, indicating that MMP-9(+) cell number of >30 would indicate the wound age of 3-14 days. Collectively, MMP-2 seemed to be more distinct marker, compared with MMP-9.
    No preview · Article · Mar 2015 · Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin
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    ABSTRACT: We immunohistochemically examined intrathrombotic IL-6 expression using a murine model of deep vein thrombosis induced by the ligation of the inferior vena cava (IVC) and discussed the availability of intrathrombotic IL-6 for thrombus age estimation. IL-6(+) cells could be first detected at 1 day after IVC ligation in three of five samples, and all samples with postligation intervals of 3 days or more had intrathrombotic IL-6(+) cells. Thereafter, the numbers of IL-6(+) cells were elevated with the increase of postligation intervals. Double-color immunofluorescence analyses demonstrated that IL-6 was mainly expressed by intrathrombotic macrophages. In all samples with postligation intervals of 5 days or less, the IL-6/macrophage ratio (IL-6/Mϕ) was <0.5. In contrast, the IL-6/Mϕ was greater than 0.5 at ≥7 days after the IVC ligation. These observations implied that IL-6/Mϕ ratios of >0.5 would strongly indicate thrombus ages of ≥7 days. Reciprocally, the ratios of less than 0.5 would suggest thrombus ages of ≤5 days. The present study demonstrated that the immunohistochemical detection of IL-6 was suitable to estimate the age of venous thrombi.
    No preview · Article · Jan 2015 · Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin

  • No preview · Conference Paper · Nov 2014
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    ABSTRACT: Introduction: Cardiac hypertrophy is an adaptive response of the heart to prolonged increases in hemodynamic workload. This compensatory process is initially beneficial in normalizing wall stress. Although various molecules have been shown to be involved in the compensatory process, its molecular mechanism still remains unclear. Thus, we investigated roles of IFN-γ in the compensatory cardiac hypertrophy induced by pressure overload. Methods: Male Balb/c (WT) and IFN-γ-deficient (IFN-γ-KO) mice were subjected to transverse aortic constriction (TAC). Aortic constriction was achieved by tying around the transverse thoracic aorta against 27- or 28-gauge needles using a 7-0 silk suture, and then removing the needle. Cardiac hypertrophy, survival rate and hypertrophy-related signaling pathways in TAC-operated mice were examined. Results: Although TAC with 28-gauge needle induced rapid increase of heart weight/body weight ratio (HW/BW ratio) in WT mice even 3 days after TAC, most mice survived for 3 weeks after TAC. On the contrary, IFN-γ-KO mice showed no significant increase of HW/BW ratio 3 days after TAC, and about 60% of them died within 6 days after TAC. In the left ventricles (LV) of WT mice, PI3K/Akt signaling, a key signaling pathway in compensatory hypertrophy, was significantly activated 3 days after TAC, compared with sham operated mice. In contrast to WT mice, the activation of PI3K/Akt signaling was significantly reduced in LV of IFN-γ-KO mice, suggesting that IFN-γ plays a crucial role in the compensatory hypertrophic response through PI3K/Akt signaling. Administration of neutralizing antibody for IFN-γ to WT mice abrogated PI3K/Akt signal activation during compensatory hypertrophy. On the contrary, administration of recombinant IFN-γ to IFN-γ-KO mice restored activation of PI3K/Akt signaling, indicating that IFN-γ is actually involved in PI3K/Akt signaling in compensatory hypertrophy. Stat5 phosphorylation was significantly enhanced in LV of WT mice 3 day after TAC, and administration of Stat5-specific inhibitor significantly suppressed PI3K/Akt signaling activation in LV of WT mice, indicating that IFN-γ is involved in PI3K/Akt signaling through Stat5 phosphorylation. Conclusion: IFN-γ/Stat 5 axis plays a crucial role in compensatory cardiac hypertrophy induced by pressure overload through PI3K/Akt signaling.
    Preview · Article · Aug 2013 · European Heart Journal
  • Mizuho Nosaka · Yuko Ishida · Akihiko Kimura · Toshikazu Kondo
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    ABSTRACT: We immunohistochemically examined the expression of IFNγ, TNFα, and TNF receptor p55 (TNF-Rp55) in a stasis-induced venous thrombus murine model. IFNγ(+), TNFα(+), and TNF-Rp55(+) cells could be first detected 7, 3, and 3 days after inferior vena cava (IVC) ligation. Thereafter, the numbers of these positive cells increased with time after IVC ligation. Double-color immunofluorescence analyses demonstrated that each molecule was expressed by intrathrombotic macrophages. In all samples with postligation intervals of 7 days or less, IFNγ/macrophage ratio (IFNγ/Mϕ), TNFα/macrophage ratio (TNFα/Mϕ), and TNF-Rp55/macrophage ratio (TNF-Rp55/Mϕ) were <0.2, <0.2, and <0.4, respectively. In contrast, IFNγ/Mϕ and TNFα/Mϕ were greater than 0.2 and 0.3 at ≥10 days after the IVC ligation, respectively. These observations suggested that IFNγ/Mϕ ratios of >0.2 and TNFα/Mϕ ratios of >0.3 indicated thrombus age of ≥10 days. Moreover, TNF-Rp55/Mϕ ratios of >0.7 strongly suggested thrombus age of >14 days. The present study demonstrated that the immunohistochemical detection of IFNγ, TNFα, and TNF-Rp55 was suitable to estimate the age of venous thrombi. However, the variation in TNF-Rp55/Mϕ ratios is wider than those of the other two markers. Thus, IFNγ and TNFα could be more practical markers.
    No preview · Article · May 2013 · Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin
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    ABSTRACT: We report a case of sudden unexpected death due to late onset neonatal group B streptococcal sepsis. A male neonate weighing 2731g was born at 35week gestational age, and discharged at the age of 4days after the birth. At 6days after the discharge (10days after the birth), because of consciousness loss and hypothermia, the neonate was conveyed to an emergency hospital, eventually followed by his death. Forensic autopsy revealed neither severe trauma nor cardiac anomaly. Both lungs were edematous. Histopathologically, a lot of bacterial clusters were found in the lungs and intracerebral vessels. Cerebrospinal fluid contained a lot of leukocytes. Streptococcus agalactiae was detected in the specimens from the feces and the blood. Collectively, we diagnosed that the cause of the neonate's death was late onset group B streptococcal sepsis. In autopsy cases of neonates, careful macroscopic and microscopic observations and bacteriological/virological examination should be performed.
    No preview · Article · Mar 2013 · Legal Medicine
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    ABSTRACT: Cardiac hypertrophy is an adaptive response of the heart to prolonged increases in hemodynamic workload. This compensatory process is initially beneficial in normalizing wall stress, and sustained left ventricular hypertrophy significantly increases the risk of developing heart failure. Although various molecules have been shown to be involved in the compensatory process, its molecular mechanism still remains unclear. We investigated roles of IFN-γ in the process of compensatory cardiac hypertrophy induced by pressure overload.
    No preview · Article · Sep 2012 · Cytokine
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    ABSTRACT: Bone marrow-derived cells are known to play important roles in repair/regeneration of injured tissues, but their roles in pathological fibrosis are less clear. Here, we report a crucial role for CX3C chemokine receptor 1 (CX3CR1) in the recruitment of lung fibrocytes.Methods An intratracheal injection of bleomycin into wild-type mice caused a massive infiltration of leukocyte subsets, such as neutrophils, T lymphocytes, and macrophages, followed by the development of diffuse pulmonary fibrosis with accumulation of fibrocytes characterized by CD45+/collagen type I+ cells.ResultsIntrapulmonary CX3CR1 and its ligand CX3CL1 expression were enhanced significantly and remained at elevated levels until pulmonary fibrosis developed. Compared with wild-type mice, collagen deposition was attenuated in CX3CR1−/− mice with reduced number of lung fibrocytes although bleomycin increased leukocyte infiltration to a similar extent in wild-type and CX3CR1−/− mice, implying that less intrapulmonary recruitment of fibrocytes directly correlated with decreased collagen deposition in CX3CR1 deficiency. Furthermore, bone marrow transplantation from CX3CR1−/− to wild-type mice, but not that from wild-type to CX3CR1−/− mice, recapitulated the phenotypes in CX3CR1−/−- mice. Conclusion: These results demonstrated that CX3CL1-CX3CR1 interaction was involved in bleomycin-induced recruitment of bone marrow-derived fibrocytes and subsequent development of pulmonary fibrosis.
    No preview · Article · Sep 2012 · Cytokine
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    ABSTRACT: The chemotherapeutic agent cisplatin often causes severe renal dysfunction; however, the molecular mechanism causing renal injury remains unclear. In wild-type mice, intrarenal interferon (IFN)-γ gene expression was found to be enhanced while CD3(+) T cells and Ly-6G neutrophils were the main cellular source of IFN-γ following cisplatin injection. Compared to wild-type mice, cisplatin-treated IFN-γ-deficient (IFN-γ(-/-)) mice exhibited exaggerated histopathological changes with higher blood urea nitrogen and creatinine levels. Cisplatin-induced apoptosis was associated with enhanced caspase-3 activation in renal proximal tubular epithelial cells, with effects suppressed by IFN-γ resulting in increased cell viability. IFN-γ significantly reduced the levels of the autophagic markers LC3-II and p62, and enhanced cathepsin D expression in cisplatin-treated renal proximal tubule epithelial cells, implying that IFN-γ can accelerate autophagic flux. Tubular cell apoptosis was more evident with enhanced caspase-3 activation in IFN-γ-deficient compared to wild-type mice. Elevated intrarenal LC3-II and increased p62 accumulation were associated with reduced cathepsin D activation in IFN-γ-deficient mice, implying that the absence of IFN-γ suppressed autophagic flux. Thus, IFN-γ can accelerate autophagic flux by augmenting cathepsin D levels and reciprocally increasing the viability of renal tubular cells, thereby attenuating cisplatin-induced acute renal injury.Kidney International advance online publication, 11 July 2012; doi:10.1038/ki.2012.240.
    No preview · Article · Jul 2012 · Kidney International
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    ABSTRACT: We report a case of fatal intoxication caused by the ingestion of an organophosphate pesticide, methidathion (DMTP). An 80-year-old male was found dead in his bed. Forensic autopsy revealed no remarkable morphological changes. However, in a toxicological screening test, methidathion was qualitatively detected in extracts of stomach contents. Concentrations of methidathion (μg/g) in body fluids and organ tissues, determined by gas chromatography-mass spectrometry, were as follows; 66.2 in heart blood, 8.33 in peripheral blood, 8.80 in urine, 2000 in the brain (frontal lobe), 4800 in the left lung, 810 in the liver, 150 in the left kidney, and 64,000 in the stomach contents (total 1.9 g). These results strongly suggested that the victim orally ingested methidathion. Additionally, xylene was determined in body fluids and organ tissues. From the toxicological data together with autopsy findings, the cause of his death was diagnosed as acute poisoning by an emulsion of methidathion.
    No preview · Article · Jun 2012 · Legal Medicine
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    ABSTRACT: Immunohistochemical study combined with morphometry was carried out to examine the expression of cyclooxygenase-2 (COX-2) using 60 human skin wounds of different ages: group I, 0-4 h (n = 11); II, 8 h-2 days (n = 21); III, 3-9 days (n = 14); and IV, 12-21 days (n = 14). In wound specimens aged 2 h to 2 days, anti-myeloperoxidase-positive neutrophils observed at the wound site expressed immunopositive reaction to COX-2. In wound specimens of more than 3 days, CD68-positive macrophages as well as neutrophils were positively immunostained with anti-COX-2. In group II, all 21 wound samples had COX-2-positive ratios of >40 %, and 15 out of them showed >50 %. In group III, only three wound samples with the postinfliction intervals of 3 days showed positive ratios of 40-50 % and the remaining 11 cases less than 40 %. In groups I and IV, all 25 wound specimens had COX-2-positive ratio of <40 %. With regard to the practical applicability with forensic safety, these observations suggested that a COX-2-positive ratio of >40 % indicated a wound age of 8 h to 3 days. Moreover, COX-2-positive ratios, considerably exceeding a ratio of 50 %, indicate a wound age of 8 h to 2 days. Collectively, COX-2 would be a useful marker for the determination of early wound age.
    No preview · Article · Mar 2012 · Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin
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    ABSTRACT: We immunohistochemically examined the expression of urokinase-type plasminogen activator (uPA), tissue-type plasminogen activator (tPA), and plasminogen-activator inhibitor type-1 (PAI-1) using venous thrombi developed by ligation of the inferior vena cava (IVC) in mice. The uPA-, tPA- and PAI-1-positive cells could be firstly detected 5, 7, and 3 days, respectively, after IVC ligation. Morphometrically, the number of PAI-1-positive cells was significantly higher than those of uPA- and tPA-positive cells at later than 7 days. In all of the thrombus samples aged 10-21 days, the uPA/PAI-1 and tPA/PAI-1 ratios were >0.1 and >0.2, respectively. In contrast, all of the thrombus samples aged 1-7 days had uPA/PAI-1 of <0.1 and tPA/PAI-1 ratios of <0.2. These findings implied that uPA/PAI-1 of >0.1 and tPA/PAI-1 of >0.2 indicated an age of 10 days or more. Moreover, in four of five samples aged 10 days, uPA/PAI-1 ratios were <0.3, and the remaining one had uPA/PAI-1 of 0.32. All thrombi aged 14-21 days showed values greater than 0.3. Thus, uPA/PAI-1 ratios, markedly exceeding 0.3, strongly indicated an age of more than 14 days. The present study demonstrated that the immunohistochemical detection of uPA, tPA, and PAI-1 was suitable to estimate the age of venous thrombi.
    No preview · Article · Feb 2012 · Deutsche Zeitschrift für die Gesamte Gerichtliche Medizin
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    ABSTRACT: BM-derived endothelial progenitor cells (EPCs) are critical and essential for neovascularization in tissue repair and tumorigenesis. EPCs migrate from BM to tissues via the bloodstream, but specific chemotactic cues have not been identified. Here we show in mice that the absence of CCR5 reduced vascular EPC accumulation and neovascularization, but not macrophage recruitment, and eventually delayed healing in wounded skin. When transferred into Ccr5-/- mice, Ccr5+/+ BM cells, but not Ccr5-/- cells, accumulated in the wound site, were incorporated into the vasculature, and restored normal neovascularization. Consistent with these observations, CCL5 induced in vitro EPC migration in a CCR5-dependent manner. Moreover, expression of VEGF and TGF-β was substantially diminished at wound sites in Ccr5-/- mice, which suggests that EPCs are important not only as the progenitors of endothelial cells, but also as the source of growth factors during tissue repair. Taken together, these data identify the CCL5/CCR5 interaction as what we believe to be a novel molecular target for modulation of neovascularization and eventual tissue repair.
    Full-text · Article · Jan 2012 · The Journal of clinical investigation

  • No preview · Article · Nov 2011 · International journal of cardiology

  • No preview · Article · Oct 2011 · Cytokine