Atsushi Sakuraba

Unique CD14+ intestinal macrophages contribute to the pathogenesis of Crohn disease via IL-23/IFN-γ axis

Intestinal macrophages play a central role in regulation of immune responses against commensal bacteria. In general, intestinal macrophages lack the expression of innate-immune receptor CD14 and do not produce proinflammatory cytokines against commensal bacteria. In this study, we identified what we believe to be a unique macrophage subset in human intestine. This subset expressed both macrophage (CD14, CD33, CD68) and DC markers (CD205, CD209) and produced larger amounts of proinflammatory cytokines, such as IL-23, TNF-alpha, and IL-6, than typical intestinal resident macrophages (CD14-CD33+ macrophages). In patients with Crohn disease (CD), the number of these CD14+ macrophages were significantly increased compared with normal control subjects. In addition to increased numbers of cells, these cells also produced larger amounts of IL-23 and TNF-alpha compared with those in normal controls or patients with ulcerative colitis. In addition, the CD14+ macrophages contributed to IFN-gamma production rather than IL-17 production by lamina propria mononuclear cells (LPMCs) dependent on IL-23 and TNF-alpha. Furthermore, the IFN-gamma produced by LPMCs triggered further abnormal macrophage differentiation with an IL-23-hyperproducing phenotype. Collectively, these data suggest that this IL-23/IFN-gamma-positive feedback loop induced by abnormal intestinal macrophages contributes to the pathogenesis of chronic intestinal inflammation in patients with CD.

Cytomegalovirus is frequently reactivated and disappears without antiviral agents in ulcerative colitis patients

OBJECTIVE: The clinical significance of cytomegalovirus (CMV) reactivation complicating ulcerative colitis (UC) patients has been uncertain. It has therefore remained undetermined whether or not CMV reactivation should be treated in UC patients under immunosuppression. The aim of the study was to clarify the natural history of CMV reactivation in UC patients.METHODS: Sixty-nine UC patients with moderate to severe activity were enrolled in the study. All of the patients were treated with prednisolone, and/or immunosuppressants such as cyclosporine A. We sequentially monitored CMV reactivation every 2 wk up until 8 wk using the CMV antigenemia (Ag) assay and plasma quantitative real-time polymerase chain reaction (PCR) assay for CMV.RESULTS: Immunoglobulin (Ig) G for CMV was positive in 48 patients (69.6%) and negative in 21 patients (30.4%). CMV was reactivated in 25 patients out of the 48 seropositive patients (52.1%) during the study period. The CMV Ag and PCR values were low and none of the patients showed any evidence of CMV infection on biopsy specimens by hematoxylin and eosin staining. While gancylovir (GCV) was not used except in two patients, clinical outcomes including rates of remission and colectomy were not significantly different among the CMV reactivation-positive, -negative, and CMV IgG negative groups. Furthermore, CMV disappeared without GCV in most of the CMV reactivation-positive patients.CONCLUSIONS: CMV is frequently reactivated in active UC patients; however, it disappears without antiviral agents. Therefore, antiviral therapies should not be necessary for most UC patients with only CMV reactivation as long as CMV Ag values are low.

Th1/Th17 Immune Response Is Induced by Mesenteric Lymph Node Dendritic Cells in Crohn's Disease

BACKGROUND & AIMS Dendritic cells (DCs) possess the most potent ability to induce acquired immunity. However, their involvement in the pathogenesis of Crohns disease (CD) has not yet been determined. We aimed to establish the immune status of mesenteric lymph nodes, the major gut-associated lymphoid tissue, and isolated DCs and determine their involvement in the pathogenesis of CD. METHODS CD4(+) T cells and DCs were isolated from mesenteric lymph nodes of CD, ulcerative colitis, and normal control. The immune status of CD4(+) T cells was analyzed by cytokine production and transcriptional profile. Surface phenotype of DCs was analyzed by flow cytometry. Cytokine production by myeloid DCs was analyzed by real-time polymerase chain reaction and exogenous bacterial stimulation. Immune stimulating activity of DCs was determined by mixed lymphocyte reaction. RESULTS In CD, mesenteric lymph node CD4(+) T cells produced higher amounts of interferon-gamma and interleukin (IL)-17 compared with ulcerative colitis and normal control, and this was dictated by increased T-bet and retinoic acid-related orphan receptor-gamma expression. Three subtypes of DCs, myeloid DC, plasmacytoid DC, and mature DC, were identified in all groups. When stimulated with exogenous bacterial derivative, myeloid DCs from CD produced a higher amount of IL-23 and a lower amount of IL-10. Myeloid DCs from CD induced stronger T helper cell (Th)1 immune response in mixed lymphocyte reaction compared with those from ulcerative colitis and normal control. CONCLUSIONS Our findings revealed that mesenteric lymph node is the key pathogenic location of CD elicited by the unique cytokine milieu produced by DCs leading to a dysregulated Th1/Th17 immune response.

T-bet upregulation and subsequent interleukin 12 stimulation are essential for induction of Th1 mediated immunopathology in Crohn’s disease

Background and aims: Many lines of evidence suggest that T helper cell type 1 (Th1) immune responses predominate in Crohn’s disease (CD). Recently, a novel transcription factor T-box expressed in T cells (T-bet) has been reported as the master regulator of Th1 development. This study was designed to investigate the role of T-bet and proinflammatory cytokines in Th1 mediated immunopathology in CD. Materials: CD4+ lamina propria mononuclear cells (LPMCs) were isolated from surgically resected specimens (CD, n = 10; ulcerative colitis (UC), n = 10; normal controls (NL), n = 5). Methods: (1) T-bet expression of CD4+ LPMCs was examined by quantitative real time polymerase chain reaction and western blotting. (2) T-bet expression of LPMCs stimulated by interleukin (IL)-12/IL-18 was analysed by western blotting. (3) Interferon γ (IFN-γ) production and T-bet expression of CD4+ peripheral blood mononuclear cells (PBMCs) were examined with or without stimulation by anti-CD3/CD28 monoclonal antibodies and/or IL-12. Results: (1) T-bet expression of CD4+ LPMCs was increased in CD compared with UC and NL. (2) Synergistically, augmentation of IFN-γ production by IL-12/IL-18 was independent of T-bet expression in LPMCs. (3) T-bet was induced by T cell receptor stimulation in CD4+ PBMCs. T-bet induction correlated with IFN-γ production and with augmentation of surface expressed IL-12 receptor β2. Conclusions: T-bet induction by antigenic stimulation and subsequent stimulation by macrophage derived IL-12/IL-18 are important for establishing Th1 mediated immunopathology in CD.

Granulocytapheresis is useful as an alternative therapy in patients with steroid-refractory or -dependent ulcerative colitis

Background:Recently, granulocyte and monocyte adsorption apheresis (GCAP) has been shown to be safe and effective for active ulcerative colitis (UC). We analyzed the safety and efficacy of GCAP (G-1 Adacolumn) in patients with steroid-refractory and -dependent UC. G-1 Adacolumn is filled with cellulose acetate carriers that selectively adsorb granulocytes and monocytes/macrophages. Methods:Forty-four patients with UC were treated with GCAP. These patients received 5 apheresis sessions over 4 weeks. Twenty patients had steroid-refractory UC (group 1) and 10 had steroid-dependent UC (group 2). Fourteen patients who did not want re-administration of steroids were treated with GCAP at the time of relapse, just after discontinuation of steroid therapy (group 3). Results:Of 44 patients treated with GCAP, 24 (55%) obtained remission (CAI ≤ 4), 9 (20%) showed a clinical response, and 11 (25%) remained unchanged. Only 2 of 10 patients (20%) with severe steroid-refractory UC (CAI ≥ 12) achieved remission, whereas 7 of 10 patients (70%) with moderate steroid-refractory UC achieved remission (p < 0.05). The dose of corticosteroids was tapered in 9 of 10 (90%) patients with steroid-dependent UC after GCAP therapy. Twelve (86%) of 14 patients in group 3 showed an improvement in symptoms and could avoid re-administration of steroids after GCAP. No severe adverse effects occurred. Conclusions:The findings of this study suggest that GCAP may be a useful alternative therapy for patients with moderate steroid-refractory or -dependent UC, although cyclosporin A or colectomy is necessary in patients with severe UC. GCAP may also be useful for avoiding re-administration of steroids at the time of relapse. Randomized, controlled clinical trials are needed to confirm these findings.

Osteopontin/Eta-1 upregulated in Crohn’s disease regulates the Th1 immune response

Background and aims: The pathogenesis of Crohn’s disease (CD), a chronic inflammatory bowel disease characterised by a Th1 immune response, remains unclear. Osteopontin (OPN) is a phosphoprotein known as an adhesive bone matrix protein. Recent studies have shown that OPN plays an important role in lymphocyte migration, granuloma formation, and interleukin 12 (IL-12) production. The present study investigated expression and the pathophysiological role of OPN in CD. Methods: Plasma OPN concentration was measured by enzyme linked immunosorbent assay. Expression of OPN in human intestinal mucosa was determined using reverse transcription-polymerase chain reaction and western blot, and localisation of OPN was examined by immunohistochemistry. Expression of integrin β3, an OPN receptor, on lamina propria mononuclear cells (LPMC) was assessed by flow cytometry. Functional activation of OPN in LPMC was investigated by measuring the production of cytokines. Results: Plasma OPN concentration was significantly higher in patients with CD compared with normal controls or patients with ulcerative colitis (UC). OPN was upregulated in intestinal mucosa from UC and CD patients. OPN producing cells were epithelial or IgG producing plasma cells, or partial macrophages. OPN was detected in areas surrounding granuloma from mucosa in CD. Integrin β3 expressing macrophages infiltrated inflamed mucosa in UC and CD; in contrast, there was no expression of integrin β3 on intestinal macrophages in normal mucosa. OPN induced production of IL-12 from LPMC in CD but not in normal controls or UC. Conclusions: Increased OPN expression facilitates cytokine production and is closely involved in the Th1 immune response associated with CD.

Animal models of inflammatory bowel disease.

models are adoptive transfer models and genetically engineered models of chronic intestinal inflammation, with many of these models resulting from the availability of gene targeting/transgenic technologies in mice, and a better understanding of the pathogenic role of certain cell populations with a pathogenic function. It became clear that, by inducing systemic immune disorders in these models, inflammation would occur in the intestine and this provided new insights into the pathogenic mechanisms and development of new therapies for inflammatory bowel disease (IBD). Some of these models, including those reported recently, are discussed in this review.

Efficacy of infliximab for induction and maintenance of remission in intestinal Behçet's disease

Background: Intestinal Behçet disease (BD) is characterized by intestinal inflammation with round and oval ulcers associated with gastrointestinal symptoms. Although several cases have been reported that infliximab is effective for induction of remission, the efficacy of infliximab for maintaining remission is unknown. Methods: Six cases with fulminant intestinal BD were treated with infliximab. All patients were steroid‐dependent and refractory to immunosuppressants; 3 patients were treated with 6‐mercaptopurine, 1 patient with azathioprine, 1 patient with cyclosporine A, and 1 patient with methotrexate. Results: Four patients achieved remission by infliximab and all of these patients maintained remission with scheduled treatments of infliximab, with the longest duration of remission being about 3 years. Another 2 patients with ileal ulceration required surgery; however, 1 patient has maintained remission by scheduled treatment of infliximab for 2 years after surgery. Conclusions: Infliximab appears to offer an option for fulminant intestinal BD to induce and maintain remission, although a randomized control trial is needed.

Retrieval of serum infliximab level by shortening the maintenance infusion interval is correlated with clinical efficacy in Crohn's disease.

Background: Infliximab has shown beneficial effects in the treatment of Crohns disease (CD). The aim of this study was to assess 1) the clinical efficacy of shortening the infusion interval from 8 to 4 weeks when patients had shown loss of response during maintenance therapy, and 2) the association between the serum trough level and clinical efficacy. Methods: This was an open‐label prospective multicenter study. Infliximab was administered at 5 mg/kg to patients with active CD at weeks 0, 2, and 6. Week 10 responders received infliximab every 8 weeks thereafter. In those with loss of response after week 14 the interval was switched to every 4 weeks. Co‐primary endpoints were the rate of patients achieving clinical response and remission at week 54. Serum level of infliximab was measured at each visit. Results: Fifty‐seven patients who responded to induction treatment received maintenance therapy after week 14. Thirty‐seven patients continued at the 8‐week interval and 20 patients were switched to a 4‐week interval. The overall clinical response and remission rates at week 54 were 82.5% and 61.4%, respectively. For those with loss of response, treatment at the 4‐week interval resulted in clinical response and remission rates of 83.3% (15/18) and 55.6% (10/18), respectively, at week 54. A correlation between clinical efficacy and serum trough level was found (P < 0.01, overall). Conclusions: A treatment strategy with an option of shortening the dosing interval of infliximab retrieves its trough level and may be useful for maintaining its efficacy. (Inflamm Bowel Dis 2012)

Efficacy and safety of medical therapy for low bone mineral density in patients with inflammatory bowel disease: a meta-analysis and systematic review.

BACKGROUND & AIMS Patients with inflammatory bowel disease (IBD) are at risk for osteoporosis and fracture. However, the efficacy of medical treatments for osteoporosis in increasing bone mineral density (BMD) in patients with IBD has not been well characterized. METHODS We conducted a meta-analysis and systematic review of controlled trials to evaluate the efficacy and safety of medical therapies used for low BMD in patients with IBD (Crohns disease, ulcerative colitis, or indeterminate colitis). We searched MEDLINE, EMBASE, Google scholar, the University Hospital Medical Information Network (UMIN) Clinical Trials Registry, and Cochrane Central Register of Controlled Trials for studies that assessed the efficacy of medical treatment for low BMD in patients with IBD. We also manually searched abstracts from scientific meetings and bibliographies of identified articles for additional references. The primary outcome assessed was changes in BMD at the lumbar spine. We also collected data on hip BMD, numbers of new fractures, and adverse effects. Data were pooled by using random-effects models and by mixed-effects analysis for primary aims, when subgroup analysis by individual drug was possible. RESULTS We analyzed data from 19 randomized controlled studies; 2 used calcium and vitamin D as therapies, 13 used bisphosphonates, 4 used fluoride, 1 used calcitonin, and 1 used low-impact exercise. The pooled effect of bisphosphonates was greater than that of controls in increasing BMD at the lumbar spine (standard difference in means, 0.51; 95% confidence interval, 0.29-0.72) and hip (standard difference in means, 0.26; 95% confidence interval, 0.04-0.49) with comparable tolerability, and the risk of vertebral fractures was reduced. Fluoride increased lumbar spine BMD, but its ability to reduce risk of fracture was unclear. There was no evidence that the other interventions increased BMD. CONCLUSIONS On the basis of a meta-analysis, bisphosphonate is effective and well tolerated for the treatment of low BMD in patients with IBD and reduces the risk of vertebral fractures. There are insufficient data to support the efficacy of calcium and vitamin D, fluoride, calcitonin, or low-impact exercise. However, the small number of randomized controlled trials limited our meta-analysis.