Biomedical subjects
Tooru Shimosegawa
Publications and source records attributed to Tooru Shimosegawa.
[Gastric inhibitory polypeptide (GIP)].
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[Effects of the interleukin-8 -251A/T polymorphism on the transcriptional activity and gastric atrophy in Helicobacter pylori infection].
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[Development of reflux esophagitis after H. pylori eradication].
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Protease-activated receptor-2-mediated proliferation and collagen production of rat pancreatic stellate cells.
Activated pancreatic stellate cells (PSCs) play a pivotal role in the pathogenesis of pancreatic inflammation and fibrosis. Trypsin and tryptase, which are agonists for protease-activated receptor-2 (PAR-2), are involved in the pathogenesis of pancreatitis. Here, we examined whether PSCs expressed PAR-2 and its agonists affect the cell functions of PSCs. PSCs were isolated from rat pancreas tissue. Expression of PAR-2 was examined by Western blotting and reverse transcription-polymerase chain reaction. Trypsin, activating peptide (SLIGRL-NH(2), corresponding to the PAR-2 tethered ligand), and tryptase were tested for their ability to affect proliferation, chemokine production, and collagen synthesis in culture-activated PSCs. Activation of mitogen-activated protein (MAP) kinases was assessed by Western blotting using antiphosphospecific antibodies. The effect of PAR-2 agonists on the activation of freshly isolated PSCs in culture was also examined. PAR-2 expression was observed in culture-activated PSCs, whereas it was undetectable in freshly isolated PSCs. PAR-2 agonists activated activator protein-1 and MAP kinases (extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 MAP kinase) but not nuclear factor kappaB. PAR-2 agonists induced proliferation of PSCs through the activation of extracellular signal-regulated kinase. PAR-2 agonists increased collagen synthesis through the activation of c-Jun N-terminal kinase and p38 MAP kinase. PAR-2 agonists did not induce the production of monocyte chemoattractant protein-1 and cytokine-induced neutrophil chemoattractant-1 or initiate the transformation of freshly isolated PSCs in culture. Taken together, our results suggest a role of PAR-2 in the sustenance of pancreatic fibrosis through the increased proliferation and collagen production in PSCs.
4-hydroxy-2, 3-nonenal activates activator protein-1 and mitogen-activated protein kinases in rat pancreatic stellate cells.
AIM: Activated pancreatic stellate cells (PSCs) are implicated in the pathogenesis of pancreatic inflammation and fibrosis, where oxidative stress is thought to play a key role. 4-hydroxy-2,3-nonenal (HNE) is generated endogenously during the process of lipid peroxidation, and has been accepted as a mediator of oxidative stress. The aim of this study was to clarify the effects of HNE on the activation of signal transduction pathways and cellular functions in PSCs. METHODS: PSCs were isolated from the pancreas of male Wistar rats after perfusion with collagenase P, and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. PSCs were treated with physiologically relevant and non-cytotoxic concentrations (up to 5 micromol/L) of HNE. Activation of transcription factors was examined by electrophoretic mobility shift assay and luciferase assay. Activation of mitogen-activated protein (MAP) kinases was assessed by Western blotting using anti-phosphospecific antibodies. Cell proliferation was assessed by measuring the incorporation of 5-bromo-2'-deoxyuridine. Production of type I collagen and monocyte chemoattractant protein-1 was determined by enzyme-linked immunosorbent assay. The effect of HNE on the transformation of freshly isolated PSCs in culture was also assessed. RESULTS: HNE activated activator protein-1, but not nuclear factor kappaB. In addition, HNE activated three classes of MAP kinases: extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 MAP kinase. HNE increased type I collagen production through the activation of p38 MAP kinase and c-Jun N-terminal kinase. HNE did not alter the proliferation, or monocyte chemoattractant protein-1 production. HNE did not initiate the transformation of freshly isolated PSCs to myofibroblast-like phenotype. CONCLUSION: Specific activation of these signal transduction pathways and altered cell functions such as collagen production by HNE may play a role in the pathogenesis of pancreatic disorders.
PKC-delta and -epsilon regulate NF-kappaB activation induced by cholecystokinin and TNF-alpha in pancreatic acinar cells.
Although NF-kappaB plays an important role in pancreatitis, mechanisms underlying its activation remain unclear. We investigated the signaling pathways mediating NF-kappaB activation in pancreatic acinar cells induced by high-dose cholecystokinin-8 (CCK-8), which causes pancreatitis in rodent models, and TNF-alpha, which contributes to inflammatory responses of pancreatitis, especially the role of PKC isoforms. We determined subcellular distribution and kinase activities of PKC isoforms and NF-kappaB activation in dispersed rat pancreatic acini. We applied isoform-specific, cell-permeable peptide inhibitors to assess the role of individual PKC isoforms in NF-kappaB activation. Both CCK-8 and TNF-alpha activated the novel isoforms PKC-delta and -epsilon and the atypical isoform PKC-zeta but not the conventional isoform PKC-alpha. Inhibition of the novel PKC isoforms but not the conventional or the atypical isoform resulted in the prevention of NF-kappaB activation induced by CCK-8 and TNF-alpha. NF-kappaB activation by CCK-8 and TNF-alpha required translocation but not tyrosine phosphorylation of PKC-delta. Activation of PKC-delta, PKC-epsilon, and NF-kappaB with CCK-8 involved both phosphatidylinositol-specific PLC and phosphatidylcholine (PC)-specific PLC, whereas with TNF-alpha they only required PC-specific PLC for activation. Results indicate that CCK-8 and TNF-alpha initiate NF-kappaB activation by different PLC pathways that converge at the novel PKCs (delta and epsilon) to mediate NF-kappaB activation in pancreatic acinar cells. These findings suggest a key role for the novel PKCs in pancreatitis.
Contribution of glutamine synthetase to ammonia-induced apoptosis in gastric mucosal cells.
BACKGROUND/AIMS: Glutamine synthetase is a key enzyme necessary for ammonia detoxification in the brain, but excessive activation of this enzyme can be cytotoxic to neural cells as a consequence of excessive consumption of ATP and glutamate. The stomach also expresses high levels of glutamine synthetase and this study aimed to investigate a possible pathophysiological role of glutamine synthetase in ammonia-induced gastric mucosal injury. METHODS: Normal rat gastric mucosal epithelial (RGM-1) cells were treated with ammonia, and a specific glutamine synthetase inhibitor (methionine sulfoximine) was used to assess the action of glutamine synthetase. RESULTS: Treatment with ammonia induced apoptotic cell death. Increased expression of p21 and Bax, decreased expression of Bcl-2, cytochrome C release from the mitochondria into the cytosol and subsequent activation of caspase-9 and -3 were identified in the cells treated with ammonia, although there was no apparent change in p53 expression. On the other hand, pretreatment with various concentrations of methionine sulfoximine reduced the glutamine synthetase activity in ammonia-treated RGM-1 cells, and prevented the induction of apoptosis and the reduction in intracellular ATP levels in a dose-dependent manner. CONCLUSIONS: Our results suggested that the energy exhaustion which resulted from an overload of ammonia to glutamine synthetase may have initiated the apoptotic signaling in gastric mucosal cells.
Systemic distribution of estrogen-responsive finger protein (Efp) in human tissues.
Estrogen-responsive finger protein (Efp), a target gene product of estrogen receptor (ER), is considered essential for estrogen-dependent cell proliferation. The biological significance of Efp remains unclear in human tissues, and therefore, we examined systemic distribution of Efp in human adult and fetal tissues using RT-PCR and immunohistochemistry. Efp mRNA expression was marked in the placenta and uterus, high in the thyroid gland, aorta, and spleen in adult, and relatively low in other human adult and fetal tissues examined in this study. Efp immunoreactivity was detected in epithelium of various adult tissues, and was also detected in cytotrophoblasts of the placenta and splenic macrophages. Efp immunolocalization in human fetus was generally similar as that in adult. These Efp-positive cells were previously reported to be associated with ERalpha and/or ERbeta expression. Therefore, these results indicate that Efp is widely expressed and may play important roles in various human tissues possibly through ERs.
A c-Jun NH2-terminal kinase inhibitor SP600125 (anthra[1,9-cd]pyrazole-6 (2H)-one) blocks activation of pancreatic stellate cells.
In response to pancreatic injury and in cell culture, pancreatic stellate cells (PSCs) are transformed ("activated") into highly proliferative myofibroblast-like cells that express alpha-smooth muscle actin and produce extracellular matrix components. Activated PSCs are implicated in the pathogenesis of pancreatic fibrosis and inflammation. We here evaluated the effects of SP600125 (anthra[1,9-cd]pyrazole-6 (2H)-one), an inhibitor of c-Jun NH(2)-terminal kinase (JNK), on the activation of PSCs. PSCs were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. Activation of JNK was determined by Western blotting using anti-phosphospecific JNK and c-Jun antibodies. Activation of transcription factors was determined by electrophoretic mobility shift assay. The effects of SP600125 on the key parameters of activation (chemokine production, collagen production, and proliferation) were examined. The effect of SP600125 on the activation of freshly isolated PSCs in culture also was examined. Interleukin-1beta activated both 46- and 54-kDa JNK, whereas platelet-derived growth factor-BB activated only 46-kDa JNK. SP600125 inhibited interleukin-1beta-induced JNK activity and activator protein-1 activation, but it did not affect the activation of extracellular-regulated kinase, p38 mitogen-activated protein kinase, and nuclear factor-kappaB. SP600125 inhibited platelet-derived growth factor-induced proliferation, inducible monocyte chemoattractant protein-1 production, and serum-induced type I collagen production. Although SP600125 did not inhibit the transformation, it attenuated the proliferation of freshly isolated PSCs in culture. Collectively, our results suggest a role of JNK in the activation of PSCs, and a potential application of JNK inhibitors for the treatment of pancreatic fibrosis and inflammation.
In vivo study on cross talk between inducible nitric-oxide synthase and cyclooxygenase in rat gastric mucosa: effect of cyclooxygenase activity on nitric oxide production.
The integrity of gastric mucosa during endotoxemia is maintained by the balance of inflammatory mediators, such as prostanoids originated from cyclooxygenase-2 (COX-2) and nitric oxide (NO) from inducible nitric-oxide synthase (iNOS). Thus, we elucidated in vivo cross talk between prostanoids and NO in gastric mucosa during endotoxemia, using an iNOS-specific inhibitor, N-(3-(aminomethyl)benzyl)acetamidine (1400W); a nonspecific COX inhibitor, indomethacin; and a COX-2-specific inhibitor, N-(2-[cyclohexyloxy]-4-nitrophenyl)methanesulfonamide (NS-398). Gastric mucosal NO and prostaglandin E2 (PGE2), a predominant product of COX, expressed as mean +/- S.D. of five rats per group, were assayed by electron paramagnetic resonance spectrometry and enzyme immunoassay technique, respectively. The levels of NO and PGE2 increased gradually up to 6 h after administration of bacterial lipopolysaccharide (LPS) (NO: control, 0.35 +/- 0.16; 6 h, 13.3 +/- 3.3 nmol/g tissue/30 min; and PGE2: control, 288 +/- 16; 6 h, 806 +/- 15 pg/g tissue). Pretreatment with 1400W decreased the increase in NO level without any effect on the PGE2 level (NO, 4.0 +/- 0.4 nmol/g tissue/30 min; PGE2, 788 +/- 26 pg/g tissue). In contrast, treatment with indomethacin and NS-398 inhibited not only PGE2 level but also NO level in a dose-dependent manner without any significant effect on both iNOS and COX protein and mRNA expression. These results demonstrate that in the LPS-treated rat gastric mucosa, PGE2 enhances the release of NO after activation of iNOS, although NO produced by iNOS does not stimulate the release of PGE2 by COXs. The effect of COX activity on iNOS-NO pathway can be important in the regulation of gastric mucosal integrity in inflammatory states.
Recovery of functional cytotoxic T lymphocytes during lamivudine therapy by acquiring multi-specificity.
To characterize cytotoxic T lymphocytes (CTLs) that appeared in circulation during lamivudine therapy, we analyzed HBV-specific CTLs using HLA-A24 tetramer and HBcAg-specific Th1 cells in patients receiving lamivudine therapy. Six patients (HLA-A24(+)) with chronic hepatitis B, six patients (HLA-A24(-)) with chronic hepatitis B, and six patients (HLA-A24(+)) with chronic hepatitis C were studied. In addition to known CTL epitopes (C117 and P756), three epitopes were confirmed as CTL epitopes (C23, S89, S226) by chromium release assay and by staining intracellular perforin. CTLs specific for P756 were most frequently found at pre-treatment. During lamivudine therapy, increase in the frequencies of HLA-tetramer(+) cells was found for C117, S89, and S226. Recovery of CTLs was observed earlier in patients with HBeAg(-)/anti-HBe(+) compared with those with HBeAg(+)/anti-HBe(-). HBcAg-specific Th1 cells did not increase significantly up to 8 weeks. T cell lines from patients with chronic hepatitis B had a lower level of proliferation (0- to 24.9-fold expansion by in vitro stimulation) and a higher ability to produce interferon-gamma (0-84% except for S89), while perforin-positive cells showed low frequencies (0-50% except for S89). In conclusion, these results suggest that lamivudine therapy induces mainly CTLs that were less frequent before the therapy. Since recovered CTLs maintained the ability to produce interferon-gamma in response to peptides, these CTLs apparently contribute to the efficacy of lamivudine therapy in patients with hepatitis B.
Inosine alleviates rat caerulein pancreatitis and pancreatitis-associated lung injury.
BACKGROUND: Recent studies have shown that inosine, a purine nucleoside produced during the breakdown of adenosine, has immunomodulatory and anti-inflammatory properties. The aim of this study was to examine the effects of inosine on the course of acute pancreatitis. METHODS: Edematous pancreatitis was induced by the intraperitoneal injection of caerulein (50 micro g/kg), seven times, at 1-h intervals, in male Wistar rats (caerulein pancreatitis). Inosine (100 mg/kg) was administered 30 min before or 1 h after the first injection of caerulein. The effects of inosine on the severity of pancreatitis were assessed by serum amylase, pancreatic edema (wet/dry ratio), myeloperoxidase activity, cytokine-induced neutrophil chemoattractant-1 concentrations, and histological changes. RESULTS: Prophylactic administration of inosine significantly decreased the elevation of serum amylase, myeloperoxidase activity, and cytokine-induced neutrophil chemoattractant-1 concentrations in the pancreas and the lung. Inosine did not significantly affect edema formation. Histologically, vacuole formation in pancreatic acinar cells, infiltration of inflammatory cells in the pancreas and the lung, and alveolar wall thickening in the lung were reduced. Inosine improved the histological findings and reduced myeloperoxidase activity even if it was administered 1 h after the first injection of caerulein. CONCLUSIONS: Inosine reduced the severity of acute pancreatitis, suggesting a possible application of this compound in the treatment of acute pancreatitis.
Lack of common mutation in the alfa-subunit of the mitochondrial trifunctional protein and the polymorphism of CYP2E1 in three Japanese women with acute fatty liver of pregnancy/HELLP syndrome.
BACKGROUND:: Acute fatty liver of pregnancy (AFLP) and the HELLP syndrome are the serious disorders during pregnancy. The aim of this study is to clarify the prevalence of common mutation in the alpha-subunit of the mitochondrial tri-functional protein: hydroxyacyl-CoA dehydrogenase (LCHAD)/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase as well as to determine the correlation with the polymorphism of microsomal cytochrome P4502E1 (CYP2E1) in these conditions. METHODS:: Genomic DNA was extracted from three patients with AFLP/the HELLP syndrome. Exon 15 of LCHAD and 5'-flanking lesion of CYP2E1 was amplified by PCR and analyzed by RFLP with either of Pst I or the combination of Pst I and Rsa I, respectively. RESULTS:: None of the patients demonstrated the 1528G-C mutation in LCHAD gene. All the patients had homozygous wild-type genotype (c1/c1) in the 5'-flanking lesion of CYP2E1. CONCLUSIONS:: Although limited size of study, our observations suggest the low incidence rate of LCHAD common mutation among Japanese patients with AFLP/HELLP syndrome. Moreover, all of the patients had wild-type genotype of CYP2E1 in this study. Considering with the fact that the neonates from these patients has been in good health for at least 6 years from birth, there might be diverse etiologic factors of Japanese patients with AFLP/HELLP syndrome other than reported genetic mutations.
Oligomycin and antimycin A prevent nitric oxide-induced apoptosis by blocking cytochrome C leakage.
Nitric oxide (NO) is a potent inducer of apoptosis, and its cytotoxicity is closely related to mitochondrial dysfunction. In this study we investigated the effects of a F0F1-ATPase inhibitor, oligomycin, and a mitochondrial respiratory chain complex III inhibitor, antimycin A, on NO-induced apoptosis. We used a normal rat gastric-epithelium cell line, RGM-1, treated with a pure NO donor, NOC-1 -1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene - in the presence or absence of oligomycin or antimycin A. Changes in the expressions of Bax or Bcl-2 proteins, release of cytochrome C from mitochondria into the cytosol, activation of caspase-3, and changes in the mitochondrial membrane potential (DeltaPsi) were measured with the use of Western blotting, c43 lorimetric assays, and a mitochondrial potential sensor, JC-1 dye. Treatment with NOC-18 induced dose-dependent apoptotic cell death in RGM-1 cells. Cell death was accompanied by mitochondrial depolarization, increases in Bax protein expression and cytochrome C leakage, and, subsequently, caspase-3 activation. Oligomycin and antimycin A prevented NO-induced apoptosis in a dose-dependent fashion by preventing cytochrome C release independent of Bcl-2 expression. However, neither compound affected the up-regulation of Bax protein. On the one hand, oligomycin treatment was not accompanied by a decline in DeltaPsi. On the other hand, antimycin A treatment decreased DeltaPsi regardless of NOC-18 treatment. The findings of this study suggest that various functional molecules that constitute the mitochondrial respiratory chain may contribute to cytochrome C release that occurs during NO-induced apoptosis.
IL-12 p40 prevents the development of chronic enterocolitis in IL-10-deficient mice.
T-helper-1 (Th1) cytokines play an important role in Crohn's disease, and interleukin-12 (IL-12), which is composed of two subunits, p40 and p35, drives Th1 differentiation. In previous reports, IL-12 p40 was shown to prevent IL-12 from binding to the receptor. We demonstrate here the effect of IL-12 p40 overexpression in intestinal epithelia on enterocolitis mediated by Th1 cells in IL-10-deficient (IL-10(-/-)) mice on a C57BL/6J background. IL-10 deficient (IL-10(-/-))/T3b-IL-12 p40+ (IL-12 p40+) mice and IL-10(-/-)/T3b-IL-12 p40- (IL-12 p40-) mice were generated by crossing T3b-IL-12 p40 transgenic mice and IL-10(-/-) mice. At 8 weeks of age, IL-12 p40+ mice did not show any clinical manifestations of colitis. The colon length of IL-12 p40- mice became shorter than that of IL-12 p40+ mice. The histological score of IL-12 p40+ mice was lower. Interferon-gamma (IFN-gamma) production was suppressed in both the mesenteric lymph node cell culture and colon tissue culture of IL-12 p40+ mice. There was no significant difference in IL-4 production and tumor necrosis factor-alpha (TNF-alpha) production between the two groups. These results show that overexpression of IL-12 p40 in intestinal epithelia prevents enterocolitis in IL-10(-/-) mice by suppressing IFN-gamma production, and suggest a potential clinical application of IL-12 p40 for Crohn's disease. Furthermore, these results also suggest that local gene transduction in the intestinal epithelium may be a potent therapeutic approach for Crohn's disease.
Hereditary pancreatitis: clinical characteristics and diagnostic criteria in Japan.
BACKGROUND/AIM: Hereditary pancreatitis (HP) is the strongest known risk factor for pancreatic cancer. The aim of the present study is to establish diagnostic criteria for HP to predict and identify high-risk groups for pancreatic cancer. METHOD: We collected clinical data for 210 patients with recurrent acute or chronic pancreatitis, and examined mutations of the cationic trypsinogen (CT) gene in 57 patients with a family history of pancreatitis or with early-onset idiopathic recurrent acute or chronic pancreatitis (40 years of age or younger). DNA was extracted from peripheral blood leukocytes, and exons 2 and 3 of the CT gene were individually amplified by polymerase chain reaction (PCR) and sequenced. RESULTS: Of these 57 patients in whom mutations of the CT gene were examined, the R122H (20 patients) and N29I (5 patients) mutations in the CT gene were observed in 25 patients (43.9%). From the analysis of clinical records and the CT gene of these patients, we proposed the following adaptations to the diagnostic criteria for HP: (1) at least one of the affected members in a family has no known etiological factors, (2) we deleted the definition of "different generation", but included the upper limit of the age of onset of pancreatitis in the case of siblings (at least 1 of the patients in a family <40 years of age). According to these criteria, all patients with the CT gene mutations in the present study could be classified as having HP, with the exception of 2 sporadic cases with the R122H and N29I mutations, respectively. Based on these findings, we revised the criteria for the diagnosis of HP; (1) recurrent acute or chronic pancreatitis with R122H or N29I mutation of the CT gene, or (2) recurrent acute or chronic pancreatitis with a family history of 2 or more affected patients, irrespective of generation, with at least 1 of the patients having no known etiological factors, and in case of siblings only, the onset of the disease in at least 1 of the patients is under age 40 years. CONCLUSION: The revised criteria in the present study are appropriate and of clinical usefulness to diagnose patients with HP even in cases without the genetic testing. However, if and when more genes are detected, it will be important to reexamine the mutation-negative patients now classified as HP based on our proposed criteria.
Hereditary pancreatitis as the premalignant disease: a Japanese case of pancreatic cancer involving the SPINK1 gene mutation N34S.
Mutations in the cationic trypsinogen gene are acknowledged as a risk factor for pancreatic cancer in patients with hereditary pancreatitis. However, whether patients with mutations in other genes, such as the serine protease inhibitor Kazal type 1 (SPINK1) gene, are also at a higher risk of pancreatic cancer remains unknown. We report a case of pancreatic cancer associated with chronic calcifying pancreatitis in a patient with a homozygous N34S mutation in the SPINK1 gene. A 44-year-old woman was hospitalized due to obstructive jaundice. Preoperative examination showed a tumor in the head of the pancreas and multiple pancreatic stones; pancreatoduodenectomy revealed a solid tumor, 3.0 x 2.5 cm in size, in the head of the pancreas, and numerous pancreatic stones throughout the pancreas. Pathologic studies revealed moderately differentiated tubular adenocarcinoma. Mutational analyses of the SPINK1 and PRSS1 genes in members of the patient's family were carried out. The homozygous N34S mutation in the SPINK1 gene was found in the patient and her older sister, who was previously diagnosed with chronic calcific pancreatitis and had undergone the Frey operation. The patient's parents and brother were unaffected carriers of the N34S heterozygous mutation. No family members had any mutations in the cationic trypsinogen gene. To our knowledge, this is the first reported case of chronic pancreatitis accompanied by pancreatic cancer in a patient with the SPINK1 N34S mutation. Although this case does not meet the classic criteria of hereditary pancreatitis, it does suggest that the SPINK1 N34S mutation may be associated with cancer development in patients with hereditary pancreatitis. Further prospective, multicenter trials investigating secondary screening for pancreatic cancer in hereditary pancreatitis are necessary to clarify the role of SPINK1 mutations in the development of pancreatic cancer.