Tatsuya Kiyohara

Production of adiponectin, an anti-inflammatory protein, in mesenteric adipose tissue in Crohn’s disease

Background and aims: A characteristic feature of Crohn’s disease (CD) is mesenteric adipose tissue hypertrophy. Mesenteric adipocytes or specific proteins secreted by them may play a role in the pathogenesis of CD. We recently identified adiponectin as an adipocyte specific protein with anti-inflammatory properties. Here we report on expression of adiponectin in mesenteric adipose tissue of CD patients. Methods and results: Mesenteric adipose tissue specimens were obtained from patients with CD (n = 22), ulcerative colitis (UC) (n = 8) and, for controls, colon carcinoma patients (n = 28) who underwent intestinal resection. Adiponectin concentrations were determined by enzyme linked immunosorbent assay, and adiponectin mRNA levels were determined by real time quantitative reverse transcription-polymerase chain reaction. Tissue concentrations and release of adiponectin were significantly increased in hypertrophied mesenteric adipose tissue of CD patients compared with normal mesenteric adipose tissue of CD patients (p = 0.002, p = 0.040, respectively), UC patients (p = 0.002, p = 0.003), and controls (p<0.0001, p<0.0001). Adiponectin mRNA levels were significantly higher in hypertrophied mesenteric adipose tissue of CD patients than in paired normal mesenteric adipose tissue from the same subjects (p = 0.024). Adiponectin concentrations in hypertrophied mesenteric adipose tissue of CD patients with an internal fistula were significantly lower than those of CD patients without an internal fistula (p = 0.003). Conclusions: Our results suggest that adipocytes in hypertrophied mesenteric adipose tissue produce and secrete significant amounts of adiponectin, which could be involved in the regulation of intestinal inflammation associated with CD.

STAT3 mediates the survival signal in oncogenic ras-transfected intestinal epithelial cells.

The oncogenic ras mutation is a common and critical step in gastrointestinal carcinogenesis. In a previous study, we demonstrated that oncogenic ras activated the EGF‐related peptide autocrine loop and that the apoptosis resistance observed in the oncogenic ras‐stimulated cell (IEC‐ras cell) was dependent on this activated EGF‐related peptide autocrine loop. STATs (signal transducers and activators of transcription), first identified as intracellular signal transducers stimulated by cytokines, are known to also be activated by EGF. However, the role of STATs in the survival signal of IEC‐ras cells is not clear. In the present study, we demonstrate that STAT3 is constitutively activated in ras‐stimulated cells and that STAT3 activation is considerably suppressed by the EGF‐specific receptor kinase inhibitor AG1478. We also show that disruption of the STAT3 pathway by introduction of a dominant‐negative STAT3 mutant abolishes the apoptosis resistance against UVC and MMC treatment observed in IEC‐ras cells without affecting proliferation. Moreover, the expression of Bcl‐2 and Bcl‐xL, apoptosis‐suppressive proteins, is reduced in dominant‐negative STAT3‐transfected cells. Thus, STAT3 appears to be an important mediator of the anti‐apoptotic signal in IEC‐ras cells. Int. J. Cancer 78:326–330, 1998.© 1998 Wiley‐Liss, Inc.

High Fas ligand expression on lymphocytes in lesions of ulcerative colitis

Background—The pathogenesis of ulcerative colitis is unclear, but cytotoxic T lymphocytes infiltrating the mucosa have been implicated in mucosal damage. The Fas ligand (FasL), expressed on cytotoxic T lymphocytes, induces apoptosis in cells expressing Fas. Aim—To analyse FasL expression in affected colonic mucosa to ascertain Fas-FasL interaction in ulcerative colitis. Methods—FasL mRNA was quantified in colonic mucosal specimens from healthy subjects and patients with ulcerative colitis or Crohn’s disease, using the competitive reverse transcription polymerase chain reaction. FasL mRNA localisation was determined by in situ hybridisation. Expression of Fas in colonic mucosa was analysed immunohistochemically. Phenotypes of lamina propria lymphocytes that expressed FasL were analysed by flow cytometry. Results—FasL mRNA was strongly expressed in active ulcerative colitis lesions, but not in those associated with active Crohn’s disease or active proctitis-type ulcerative colitis. In situ hybridisation showed that FasL mRNA expression occurred in mononuclear cells infiltrating lesions. Fas was expressed in epithelial cells in ulcerative colitis and Crohn’s disease, and in normal subjects. Cytometry showed that FasL was expressed in CD3 lymphocytes infiltrating the lamina propria in active lesions. Conclusions—FasL is expressed in CD3 lymphocytes infiltrating into ulcerative colitis but not Crohn’s disease lesions, suggesting that Fas-FasL induced apoptosis participates in the mucosal damage of ulcerative colitis.

Deficiency of KIT-positive cells in the colon of patients with diabetes mellitus.

Diabetes mellitus is a well‐known cause of gastrointestinal dysmotility. The pathogenesis of diabetic gastroenteropathy is mainly considered to be a neuropathy, but the cause of dysmotility remains unknown. Interstitial cells of Cajal (ICC), which express c‐kit receptor tyrosine kinase (KIT), are considered to be pacemaker cells for the gastrointestinal movement. Therefore, we investigated a possible involvement of ICC in the pathogenesis of diabetic gastroenteropathy in humans.

Disturbed gastrointestinal motility and decreased interstitial cells of Cajal in diabetic db/db mice

Background and Aim:  Diabetes mellitus (DM) often causes gastrointestinal dysmotility. Interstitial cells of Cajal (ICC), which express c‐kit receptor tyrosine kinase (KIT), are considered the pacemaker cells for gastrointestinal movement. The present study was designed to determine the role of ICC in the pathogenesis of gastroenteropathy in type 2 DM.

Peroxisome proliferator-activated receptor γ reduces the growth rate of pancreatic cancer cells through the reduction of cyclin D1

Peroxisome proliferator-activated receptor gamma (PPARgamma) forms a heterodimeric DNA-binding complex with the retinoid X receptor (RXR) and regulates the transcription of its target genes. Activation of PPARgamma has been shown to induce G1 arrest and to inhibit cell growth of human pancreatic carcinoma cell lines. The purpose of the present study was to examine the effect of ligand activation of PPARgamma and RXR on cell growth and on the expression of G1 cyclins in a pancreatic cancer cell line PANC-1, which expresses PPARgamma at high levels. Troglitazone, a specific ligand for PPARgamma, was found to cause a reduction in the growth rate and induced G1 cell cycle arrest and this effect was additive with that of 9-cis retinoic acid (9-cis RA), a ligand for RXR. Of the G1 cyclins tested, troglitazone specifically reduced the expression of cyclin D1 mRNA and the corresponding protein and this effect was also additive with 9-cis RA. These results suggest that the activation of PPARgamma together with RXR may be useful for the suppression of pancreatic cancer cell growth through the reduction in cyclin D1 levels.

Over-expression of bcl-xL gene in human gastric adenomas and carcinomas

The present study was designed to clarify whether bel‐xL is involved in the development of carcinoma in the stomach. Levels of bel‐xL and bc1‐2 mRNA were determined by a reverse‐transcription/polymerase‐chain reaction in endoscopic gastric biopsy specimens from 10 control subjects, 11 patients with adenomas and 14 patients with carcinomas. In 6 of 11 adenomas, 5 of 8 early carcinomas and 3 of 6 advanced carcinomas, the bel‐xL gene was over‐expressed. In carcinomas, overexpression of the bel‐xL gene was observed in 6 of 9 intestinaltype carcinomas and 2 of 5 diffuse‐type carcinomas. No correlation was observed between bel‐xL and bc1‐2 gene expression. In cases in which the bel‐xL gene was over‐expressed, an apparent increase in the protein level of Bcl‐xL was observed by immunoblot analysis and intense Bcl‐x immunoreactivity was detected immunohistochemically within the tumor cells. In conclusion, we showed that bel‐xL is over‐expressed in gastric carcinomas at both the RNA and protein levels, suggesting that overexpression of bel‐xL may play a role in gastric carcinogenesis.

Cd9-mediated activation of the p46 Shc isoform leads to apoptosis in cancer cells

CD9, a member of the tetraspanin family, has been shown to be involved in a range of cellular activities, including migration, proliferation and adhesion, but the molecular mechanisms by which it mediates such events is unclear. Here, we found that anti-CD9 monoclonal antibody ALB6 inhibited cell proliferation, reduced cell viability and induced not only morphological changes specific to apoptosis but also molecular changes, as evidenced by TUNEL and annexin-V staining. For the possible mechanism of ALB6-induced apoptosis, ALB6 activated the c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38 mitogen-activated-protein kinase (MAPK) within 5-15 minutes, as well as caspase-3 within 24-48 hours. It is noteworthy that ALB6 induced tyrosine phosphorylation of the p46 Shc isoform specifically and that the overexpression of its dominant-negative form completely suppressed the ALB6-induced activation of JNK/SAPK, p38 MAPK and caspase-3, resulting in the inhibition of apoptotic cell death. These results suggest that CD9 might regulate apoptosis through the specialized signals in human cancer cell lines.

Helicobacter pylori -induced enlarged-fold gastritis is associated with increased mutagenicity of gastric juice, increased oxidative DNA damage, and an increased risk of gastric carcinoma

Background and Aim:  The severe inflammation, increased cell proliferation and marked acid inhibition observed in subjects with Helicobacter pylori‐associated enlarged‐fold gastritis suggest that enlarged‐fold gastritis may be a risk factor for gastric carcinoma. The purpose of the present study was to determine whether a relationship exists between enlarged‐fold gastritis and gastric carcinoma.

Adiponectin plays a protective role in caerulein-induced acute pancreatitis in mice fed a high-fat diet

Background: Obesity is a risk factor for acute pancreatitis (AP), but the molecular mechanism remains unclear. Adiponectin, an adipose tissue-derived secretory factor, has anti-inflammatory properties in addition to various biological functions, and its plasma concentrations are reduced in obese subjects. However, the role of adiponectin in AP has not been investigated. Aim: To determine the effects of adiponectin on AP. Methods: We investigated the effects of adiponectin on experimental AP by using adiponectin-knockout (APN-KO) mice and adenovirus-mediated adiponectin over-expression. AP was induced by 10 hourly intraperitoneal injections of low-dose caerulein (10 μg/kg) after 2 week feeding of normal chow or a high-fat diet (HFD) in wild-type (WT) and APN-KO mice. We evaluated the severity of AP biochemically and morphologically. Results: Low-dose caerulein treatment did not induce pancreatic damage in either WT or APN-KO mice under normal chow feeding. APN-KO mice, but not WT mice, fed a HFD and then treated with caerulein developed pancreatic damage and inflammation, accompanied by increased macrophage/neutrophil infiltration and upregulation of pro-inflammatory mediators such as tumour necrosis factor α in the pancreas. Adenovirus-mediated over-expression of adiponectin attenuated the severity of HFD/caerulein-induced AP in APN-KO mice. Conclusions: Adiponectin plays a protective role in caerulein-induced AP in HFD-fed mice.