Sakae Mikami

Usefulness of quantitative real-time PCR assay for early detection of cytomegalovirus infection in patients with ulcerative colitis refractory to immunosuppressive therapies

Background: Studies suggest that cytomegalovirus (CMV) infection exacerbates ulcerative colitis (UC) refractory to immunosuppressive therapies. Early and accurate diagnosis of CMV infection is important for the treatment of UC. We evaluated the usefulness of quantitative real‐time polymerase chain reaction (PCR) for detecting CMV infection in inflamed colonic mucosa of patients with UC refractory to immunosuppressive therapies. Methods: From 2003 to 2006, 30 patients (mean age: 41 ± 18 years; 14 men, 16 women) with UC refractory to immunosuppressive therapies were enrolled in the study. We evaluated CMV infection by CMV antigenemia, histologic examination, and quantitative real‐time PCR for CMV using colonic mucosa and investigated the clinical outcomes of antiviral therapy. Results: CMV‐DNA was detected only in the inflamed colonic mucosa in 17 (56.7%) of 30 patients. Of the 17 CMV‐DNA‐positive patients, 4 were positive for CMV antigenemia or inclusion bodies on histologic examination; of the 13 CMV‐DNA‐negative patients none was positive for CMV antigenemia or inclusion bodies. Of the 17 CMV‐DNA‐positive patients, 12 (70.6%) were treated with ganciclovir for 2 weeks and 10 patients went into remission. Two other patients required colectomy after antiviral therapy. In contrast, of the 13 CMV‐DNA‐negative patients 12 (92.3%) achieved remission after intensifying their immunosuppressive therapies. Conclusions: Quantitative real‐time PCR assay for detecting CMV‐DNA is useful for early, accurate diagnosis of CMV infection in patients with UC refractory to immunosuppressive therapies, enabling prompt and appropriate treatment. (Inflamm Bowel Dis 2007)

Long-term effect of tacrolimus therapy in patients with refractory ulcerative colitis

Background  Little is known about long‐term outcome of tacrolimus therapy for ulcerative colitis.

Random Walk Behavior of Migrating Cortical Interneurons in the Marginal Zone: Time-Lapse Analysis in Flat-Mount Cortex

Migrating neurons are thought to travel from their origin near the ventricle to distant territories along stereotypical pathways by detecting environmental cues in the extracellular milieu. Here, we report a novel mode of neuronal migration that challenges this view. We performed long-term, time-lapse imaging of medial ganglionic eminence (MGE)-derived cortical interneurons tangentially migrating in the marginal zone (MZ) in flat-mount cortices. We find that they exhibit a diverse range of behaviors in terms of the rate and direction of migration. Curiously, a predominant population of these neurons repeatedly changes its direction of migration in an unpredictable manner. Trajectories of migration vary from one neuron to another. The migration of individual cells lasts for long periods, sometimes up to 2 d. Theoretical analyses reveal that these behaviors can be modeled by a random walk. Furthermore, MZ cells migrate from the cortical subventricular zone to the cortical plate, transiently accumulating in the MZ. These results suggest that MGE-derived cortical interneurons, once arriving at the MZ, are released from regulation by guidance cues and initiate random walk movement, which potentially contributes to their dispersion throughout the cortex.

Blockade of CXCL12/CXCR4 Axis Ameliorates Murine Experimental Colitis

Recent studies indicate that the CXCL12/CXCR4 interaction is involved in several inflammatory conditions. However, it is unclear whether this interaction has a role in the pathophysiology of inflammatory bowel disease (IBD). We investigated the significance of this interaction in patients with IBD and in mice with dextran sulfate sodium (DSS)-induced colitis and the effect of a CXCR4 antagonist on experimental colitis. First, we measured CXCR4 expression on peripheral T cells in patients with IBD. Furthermore, we investigated CXCR4 expression on leukocytes and CXCL12 expression in the colonic tissue of mice with DSS-induced colitis, and we evaluated the effects of a CXCR4 antagonist on DSS-induced colitis and colonic inflammation of interleukin (IL)-10 knockout (KO) mice. Colonic inflammation was assessed both clinically and histologically. Cytokine production from mesenteric lymph node cells was also examined. CXCR4 expression on peripheral T cells was significantly higher in patients with active ulcerative colitis (UC) compared with normal controls, and CXCR4 expression levels of UC patients correlated with disease activity. Both CXCR4 expression on leukocytes and CXCL12 expression in colonic tissue were significantly increased in mice with DSS-induced colitis. Administration of a CXCR4 antagonist ameliorated colonic inflammation in DSS-induced colitis and IL-10 KO mice. CXCR4 antagonist reduced tumor necrosis factor-α and interferon-γ production from mesenteric lymph node cells, whereas it did not affect IL-10 production. The percentage of mesenteric Foxp3+CD25+ T cells in DSS-induced colitis was not affected by CXCR4 antagonist. These results suggest that blockade of this chemokine axis might have potential as a therapeutic target for the treatment of IBD.

SDF1/CXCR4 signalling regulates two distinct processes of precerebellar neuronal migration and its depletion leads to abnormal pontine nuclei formation.

The development of mossy-fibre projecting precerebellar neurons (PCN) presents a classical example of tangential neuronal migration. PCN migrate tangentially along marginal streams beneath the pial surface from the lower rhombic lip to specific locations in the hindbrain, where they form precerebellar nuclei. Among them, the pontine neurons follow a stereotypic anteroventral-directed pathway to form the pontine nuclei in the pons. The guidance mechanisms that determine the marginal migration of PCN and the anterior migration of pontine neurons are poorly understood. Here, we report that a chemokine SDF1 (also known as CXCL12) derived from the meningeal tissue regulates the migratory pathways of PCN. PCN are chemoattracted by the meningeal tissue, an effect that is mimicked by an SDF1 source. Analysis of knockout mice for the Sdf1 receptor Cxcr4 shows that both the marginal migration of PCN and the anterior migration of pontine neurons are disrupted. We provide further evidence that SDF1/CXCR4 signalling regulates these two processes cell-autonomously. As a result of disrupted neuronal migration, pontine nuclei formation was highly abnormal, with the presence of multiple ectopic pontine clusters posteriorly. The ectopic pontine clusters led to ectopic collateral branch formation from the corticospinal tract. Our results together demonstrate crucial roles for SDF1/CXCR4 in multiple aspects of PCN migration and highlight the deleterious consequence of derailed migration on proper nuclei formation. Furthermore, we provide the first in vivo evidence that pontine neurons themselves induce collateral branching from the corticospinal axons.

The effect of proteasome inhibitor MG132 on experimental inflammatory bowel disease

Immunoproteasome up‐regulation enhances the processing of nuclear factor‐κB (NF‐κB) and degradation of IκBα, which correlates with increased amounts of NF‐κB in the various cells. Aberrant activation of NF‐κB is involved in the pathogenesis of inflammatory bowel disease (IBD). The aim of this study was to elucidate the effect of proteasome inhibitor MG132 on experimental IBD. We investigated the effects of MG132 on intestinal inflammation and epithelial regeneration in both interleukin‐10‐deficient (IL‐10−/−) mice and mice with dextran sulphate sodium (DSS)‐induced colitis. Body weight, histological findings and tumour necrosis factor (TNF)‐α mRNA expression, epithelial cell proliferation and NF‐κB p65 activity in colonic tissues were examined. The effects of MG132 on cell proliferation, migration and multiple drug resistance 1 (MDR1) gene expression were determined in vitro. MG132 ameliorated intestinal inflammation of IL‐10−/− mice by decreasing TNF‐α mRNA expression in the colonic tissues, which was associated with suppression of NF‐κB activation, and reduced significantly the number of Ki‐67‐positive intestinal epithelial cells. On the other hand, MG132 did not reduce intestinal inflammation in mice with DSS‐induced colitis, and delayed significantly the recovery of body weight and epithelial regeneration. MG132 also suppressed significantly epithelial cell proliferation, cell migration and MDR1 gene expression in vitro. Proteasome inhibition reduces T cell‐mediated intestinal inflammation, but may interrupt both epithelial regeneration and barrier function of colonic mucosa. Optimal use of proteasome inhibitor should be kept in mind when we consider its clinical application for patients with IBD.

CXCR4 Is Required for Proper Regional and Laminar Distribution of Cortical Somatostatin-, Calretinin-, and Neuropeptide Y-Expressing GABAergic Interneurons

Cortical GABAergic interneurons are divided into various subtypes, with each subtype contributing to rich variety and fine details of inhibition. Despite the functional importance of each interneuron subtype, the molecular mechanisms that contribute to sorting them to their appropriate positions within the cortex remain unclear. Here, we show that the chemokine receptor CXCR4 regulates the regional and layer-specific distribution of interneuron subtypes. We removed Cxcr4 specifically in a subset of interneurons at a specific mouse embryonic developmental stage and analyzed the number of interneurons and their laminar distribution in 9 representative cortical regions comprehensively in adults. We found that the number of Cxcr4-deleted calretinin- and that of neuropeptide Y-expressing interneurons were reduced in most caudomedial and lateral cortical regions, respectively, and also in superficial layers. In addition, Cxcr4-deleted somatostatin-expressing interneurons showed a reduction in the number of superficial layers in certain cortical regions but of deep layers in others. These findings suggest that CXCR4 is required for proper regional and laminar distribution in a wider interneuron subpopulation than previously thought and may regulate the establishment of functional cortical circuitry in certain cortical regions and layers.

The effect of tacrolimus (FK-506) on Japanese patients with refractory Crohn’s disease

BackgroundRecent evidence indicates that intravenous or oral therapy with tacrolimus (FK-506) is effective in treating patients with Crohn’s disease. We evaluated the usefulness of tacrolimus therapy for Japanese patients with refractory Crohn’s disease.MethodsFourteen adult Japanese patients with Crohn’s disease that was refractory to conventional therapies, including prednisolone (n = 5), azathioprine (n = 6), and infliximab (n = 5), were enrolled. Treatment with tacrolimus was started orally or intravenously and aimed for serum trough levels of 10–15 ng/ml. After the patients achieved clinical improvement, tacrolimus maintenance therapy was administered to maintain the trough level at 5–10 ng/ml.ResultsAll patients achieved remission or significant improvement 40 days after starting tacrolimus treatment. By 120 days after the start of therapy, 9 (64%) patients achieved remission, 2 patients (14%) achieved significant improvement, and only 3 patients (21%) relapsed. The relapsed patients were treated with infliximab therapy and achieved remission. Steroids were discontinued by the 5 patients who had taken steroids before the study began. Adverse effects of tacrolimus included a temporary increase in serum creatinine concentration (n = 1, 7%), hyperkalemia (n = 1, 7%), and tremor (n = 1, 7%).ConclusionsTacrolimus therapy is effective and well tolerated in patients with Crohn’s disease that is refractory to conventional therapies.

SR-PSOX/CXCL16 plays a critical role in the progression of colonic inflammation

Background and aims Inflammatory bowel disease (IBD) is initiated and perpetuated by a dysregulated immune response to unknown environmental antigens such as luminal bacteria in genetically susceptible hosts. SR-PSOX/CXCL16, a scavenger receptor that binds phosphatidylserine and oxidised lipoprotein, has both phagocytic activity and chemotactic properties. The aim of this study was to investigate the role of SR-PSOX/CXCL16 in patients with IBD and experimental murine colitis. Methods The serum levels of SR-PSOX/CXCL16 were measured in patients with IBD. The roles of SR-PSOX/CXCL16 in phagocytosis of bacterial components and cytokine production by macrophages from wild-type (WT) and SR-PSOX/CXCL16 knockout (KO) mice were assessed. Colitis was induced by administering dextran sulfate sodium (DSS) to WT and SR-PSOX/CXCL16 KO mice. Colonic inflammation was analysed by clinical, histological and immunological parameters. Finally, the effect of a monoclonal antibody (mAb) to SR-PSOX/CXCL16 on DSS-induced colitis and trinitrobenzene sulfonic acid-induced colitis models was evaluated. Results Serum levels of SR-PSOX/CXCL16 correlated significantly with the disease activity of patients with IBD. Ex vivo experiments showed that SR-PSOX/CXCL16 was involved in both phagocytosis of bacterial antigens and the T helper 1 immune response through the production of interleukin 12 and interferon γ. In vivo murine experiments demonstrated the upregulated gene expression of SR-PSOX/CXCL16 in inflamed colonic tissues and the predominant expression of SR-PSOX/CXCL16 on macrophages. SR-PSOX/CXCL16 KO mice were less susceptible to colonic inflammation than were their WT littermates. Administration of SR-PSOX/CXCL16 mAb ameliorated the condition in the two different experimental colitis models. Conclusions SR-PSOX/CXCL16 plays a critical role in colonic inflammation and could be a potential therapeutic target for patients with IBD.

Modulation of Th1/Th2 Balance by Infliximab Rescues Postoperative Occurrence of Small-Intestinal Inflammation Associated with Ulcerative Colitis

In general, ulcerative colitis (UC) is defined as idiopathic inflammation limited to the colorectum, except for backwash ileititis and postcolectomy pouchitis. However, UC is also considered to be a systemic disease because of not only colonic inflammation but also joint, skin, and acute hepatic involvement. Recently, there have been several reports of UC patients with gastroduodenitis or enteritis [1–4]. Cases of gastroduodenitis or enteritis associated with UC are clinically rare but are an important issue for gastroenterologists in the point of no optimal treatment established. Here, we report a case of the postoperative occurrence of small-intestinal inflammation associated with UC successfully treated with infliximab.