Kazuo Kusugami

Complete antithrombin deficiency in mice results in embryonic lethality

Antithrombin is a plasma protease inhibitor that inhibits thrombin and contributes to the maintenance of blood fluidity. Using targeted gene disruption, we investigated the role of antithrombin in embryogenesis. Mating mice heterozygous for antithrombin gene (ATIII) disruption, ATIII(+/-), yielded the expected Mendelian distribution of genotypes until 14.5 gestational days (gd). However, approximately 70% of the ATIII(-/-) embryos at 15.5 gd and 100% at 16.5 gd had died and showed extensive subcutaneous hemorrhage. Histological examination of those embryos revealed extensive fibrin(ogen) deposition in the myocardium and liver, but not in the brain or lung. Furthermore, no apparent fibrin(ogen) deposition was detected in the extensive hemorrhagic region, suggesting that fibrinogen might be decreased due to consumptive coagulopathy and/or liver dysfunction. These findings suggest that antithrombin is essential for embryonic survival and that it plays an important role in regulation of blood coagulation in the myocardium and liver.

Plakoglobin (gamma-catenin) has TCF/LEF family-dependent transcriptional activity in beta-catenin-deficient cell line.

β-Catenin is an essential element for the transcriptional activation of target genes in the Wnt signaling cascade and is also a cell adhesion molecule that couples with cadherins. Although plakoglobin (γ-catenin), a closely related homologue of β-catenin, is also known to be a cell adhesion molecule, its function as a transcriptional factor has not been revealed in detail. Using a human malignant mesothelioma cell line, NCI-H28, in which we have identified a homozygous deletion of the β-catenin gene, we studied whether plakoglobin has a T-cell factor/lymphocyte enhancer factor (TCF/LEF) family-dependent transcriptional activity. Transfection with the wild-type plakoglobin expression vector induced accumulation of plakoglobin in the nucleus. Immunoprecipitation assay with cotransfection of plakoglobin and either TCF-4 or LEF-1 detected binding of plakoglobin to TCF-4 or LEF-1. Luciferase reporter assay demonstrated transcriptional activity of the wild-type plakoglobin when transfected with TCF/LEF, although plakoglobin showed less activity than β-catenin. Exogenous plakoglobin was also shown to promote entrance of exogenous β-catenin into the nuclei. Furthermore, small interfering RNA directed against plakoglobin suppressed expression of endogenous plakoglobin and its transcriptional activity, suggesting that endogenous plakoglobin has a weak transcriptional activity. These results suggest that plakoglobin can activate the Wnt signaling cascade directly without interaction of β-catenin, and that plakoglobin has multiple functions as a transcriptional activator and a cell adhesion molecule like β-catenin.

Elevation of interleukin-6 in inflammatory bowel disease is macrophage- and epithelial cell-dependent

Local interleukin-6 (IL-6) activity was studied using colonic mucosal tissues in inflammatory bowel disease (IBD) and inflammatory control patients. Active IBD specimens exhibited significantly higher IL-6 activity than control specimens in both cultures of isolated lamina propria mononuclear cells (LPMC) and mucosal tissues with an increased number of IL-6-producing cells. However, the activity in inactive IBD or inflammatory controls did not differ from controls. Northern blot analysis demonstrated IL-6 messenger RNA in LPMC and colonic epithelial cells isolated from active IBD specimens but not in control cells. Furthermore, immunofluorescent microscopic study of active IBD specimens showed more conspicuous staining of IL-6 in infiltrating LPMC (mostly CD68+ cells) and colonic epithelial cells. These results suggest that elevation of local IL-6 activity may be a characteristic feature of active IBD and both macrophages and colonic epithelial cells are the major cell types responsible for this phenomenon.

Restriction–modification system differences in Helicobacter pylori are a barrier to interstrain plasmid transfer

Helicobacter pylori cells are naturally competent for the uptake of both plasmid and chromosomal DNA. However, we demonstrate that there are strong barriers to transformation of H. pylori strains by plasmids derived from unrelated strains. We sought to determine the molecular mechanisms underlying these barriers. Transformation efficiency was assessed using pHP1, an Escherichia coli–H. pylori shuttle vector conferring kanamycin resistance. Transformation of 33 H. pylori strains was attempted with pHP1 purified from either E. coli or H. pylori, and was successfully introduced into only 11 strains. Digestion of H. pylori chromosomes with different restriction endonucleases (REs) showed that DNA methylation patterns vary substantially among strains. The strain most easily transformed, JP26, was found to have extremely low endogenous RE activity and to lack a restriction–modification (R–M) system, homologous to MboI, which is highly conserved among H. pylori strains. When we introduced this system to JP26, pHP1 from MboI.M+ JP26, but not from wild‐type JP26, transformed MboI R−M+ JP26 and heterologous MboI R−M+ wild‐type H. pylori strains. Parallel studies with pHP1 from dam+ and dam−E. coli strains confirmed these findings. These data indicate that the endogenous REs of H. pylori strains represent a critical barrier to interstrain plasmid transfer among H. pylori.

Interleukin 15 activity in the rectal mucosa of inflammatory bowel disease

BACKGROUND & AIMS Interleukin (IL)-15 has been found to share many immunoregulatory activities in lymphocytes with IL-2. The aim of this study was to investigate IL-15 activity in organ cultures, localization of IL-15 messenger RNA (mRNA), and proliferation of lamina propria mononuclear cells (LPMCs) in response to recombinant IL-15 using the mucosal tissues obtained from patients with inflammatory bowel disease (IBD). METHODS The contents of IL-15, tumor necrosis factor alpha, and IL-2 in the culture supernatant of the rectal mucosal tissues were determined by an enzyme-linked immunosorbent assay. Expression of IL-15 mRNA was analyzed by in situ hybridization, and proliferative response of LPMCs to recombinant IL-15 was determined by [3H]thymidine incorporation into DNA. RESULTS Significantly greater IL-15 activity was detected in active IBD, and this elevation was also observed in inactive ulcerative colitis. In contrast, greater tumor necrosis factor alpha activity was observed only in active IBD, and IL-2 was not detected in organ cultures. In situ hybridization showed IL-15 mRNA in macrophages and epithelial cells in active IBD specimens, and recombinant IL-15 induced a dose-dependent proliferative response in LPMCs. CONCLUSIONS Mucosal IL-15 may be involved in the pathogenesis of IBD as one of the important mediators in activation of mucosal immune cells.

Interleukin‐6 and soluble interleukin‐6 receptor in the colonic mucosa of inflammatory bowel disease

Background : Interleukin‐6 (IL‐6) has multiple immunological effects on a wide variety of cells and tissues. The expression of IL‐6 and IL‐6 receptor (IL‐6R) may be important to the pathogenesis of inflammatory bowel disease (IBD).

Recurrent Peptic Ulcers in Patients Following Successful Helicobacter pylori Eradication: A Multicenter Study of 4940 Patients

Objective.  Although curative treatment of Helicobacter pylori infection markedly reduces the relapse of peptic ulcers, the details of the ulcers that do recur is not well characterized. The aim of this study is to describe the recurrence rate and specific features of peptic ulcers after cure of H. pylori infection.

Polymorphisms of Helicobacter pylori HP0638 Reflect Geographic Origin and Correlate with cagA Status

ABSTRACT Since the associations between Helicobacter pylori genotype and disease differ in Asia and the West, we investigated the correlation between HP0638, encoding an outer membrane protein, and potential markers of virulence (cagA, vacA, and iceA). For 109 strains from nine countries, the status of cagA, vacA, and iceA was determined by PCR and/or a line probe assay. We also studied 18 strains from 8 patients (parents and 6 daughters) from a Dutch family and paired strains collected on average 8 years apart from 11 patients. When the HP0638 signal sequences were amplified by PCR and DNA sequence determinations were performed, 89 (96%) of 93 cagA-positive strains had HP0638 in frame, versus none (0%) of 16 cagA-negative strains (P < 0.001). Among strains in which HP0638 was in frame, a six-CT dinucleotide repeat pattern was dominant in Western countries (23 of 33 strains [70%]), while a pattern of three CT repeats with another CT after four T’s (3 + 1-CT-repeat pattern) was dominant in East Asia (31 of 46 strains [67%]); however, specific CT repeat patterns did not correlate with clinical outcome. HP0638 phylogenetic trees also showed geographic characters. The HP0638 frame status and CT dinucleotide repeat patterns were identical for 9 of 11 pairs of strains obtained on average 8 years apart from individuals and the 15 strains obtained from the mother and all six daughters. Thus, HP0638 frame status and cagA status are strongly correlated. The CT dinucleotide repeat pattern in the putative HP0638 signal sequence has geographic characters and appears stable in particular patients and families over a period of years. Analysis of HP0638 CT polymorphisms may serve as a new typing system to discriminate H. pylori isolates for epidemiological purposes.

Syndecan‐4 deficiency impairs the fetal vessels in the placental labyrinth

Syndecan‐4 is a transmembrane protein bearing heparan sulfate chains, involved in anticoagulation and focal adhesion formation. Here, we revealed that syndecan‐4 was expressed in the fetal vessels in the placental labyrinth by in situ hybridization and immunohistochemical staining. At 17.5 gestational days, the area of degenerated fetal vessels in the placental labyrinth was more diffuse and larger in Synd4(‐/‐) embryos than wild‐type controls. Calcium and fibrin(ogen) depositions in the degenerated vessels were also more extensive and more severe in the placentas of Synd4(‐/‐) embryos. These findings suggest that syndecan‐4 deficiency impairs the fetal vessels in the placenta, probably due to a deficit in the anticoagulation mechanism. This article is the first report demonstrating that among a large number of core proteins of heparan sulfate proteoglycans, a defect of a single core protein caused impaired anticoagulation in a specific site.

Increased mucosal production of granulocyte colony‐stimulating factor is related to a delay in neutrophil apoptosis in Inflammatory Bowel disease

Tissue accumulation of polymorphonuclear neutrophils (PMN) in Inflammatory Bowel disease (IBD) might be, in part, due to a delay in apoptotic processes associated with the effects of their specific growth factors and inflammatory cytokines. We addressed this hypothesis by examining the activity of granulocyte colony‐stimulating factor (G‐CSF) and granulocyte–macrophage CSF (GM‐CSF) in the organ culture supernatants of colonic mucosal specimens and their regulatory effects on PMN apoptosis in patients with IBD. The contents of G‐CSF and GM‐CSF in the supernatants were measured by the enzyme‐linked immunosorbent assays and PMN apoptosis was evaluated by acridine orange/ethidium bromide staining, respectively. Mucosal specimens obtained from patients with active IBD exhibited higher levels of G‐CSF and GM‐CSF activity than controls. Notably, the levels of G‐CSF activity were approximately 1000‐fold higher than those of GM‐CSF activity. Freshly isolated PMN showed a time‐related increase in the proportion of cells with characteristic features of apoptosis when they were incubated with the culture medium alone and exposure of PMN to recombinant G‐CSF and GM‐CSF caused a concentration‐dependent inhibition of apoptosis. Incubation of PMN with the supernatants from patients with active IBD induced an inhibitory effect on PMN apoptosis; this effect was abrogated to a significant degree by pre‐incubation of the supernatants with anti‐G‐CSF serum. This study suggests that PMN apoptosis may be delayed under the influence of soluble mediators, especially G‐CSF, in the microenvironment of IBD‐affected mucosa, thus providing possible mechanisms for tissue accumulation of PMN in IBD.