The cost of inflammatory bowel disease in high-income settings: a Lancet Gastroenterology & Hepatology Commission.

The cost of caring for patients with inflammatory bowel disease (IBD) continues to increase worldwide. The cause is not only a steady increase in the prevalence of Crohn's disease and ulcerative colitis in both developed and newly industrialised countries, but also the chronic nature of the diseases, the need for long-term, often expensive treatments, the use of more intensive disease monitoring strategies, and the effect of the diseases on economic productivity. This Commission draws together a wide range of expertise to discuss the current costs of IBD care, the drivers of increasing costs, and how to deliver affordable care for IBD in the future. The key conclusions are that (1) increases in health-care costs must be evaluated against improved disease management and reductions in indirect costs, and (2) that overarching systems for data interoperability, registries, and big data approaches must be established for continuous assessment of effectiveness, costs, and the cost-effectiveness of care. International collaborations should be sought out to evaluate novel models of care (eg, value-based health care, including integrated health care, and participatory health-care models), as well as to improve the education and training of clinicians, patients, and policy makers.

AJM300 (carotegrast methyl), an oral antagonist of α4-integrin, as induction therapy for patients with moderately active ulcerative colitis: a multicentre, randomised, double-blind, placebo-controlled, phase 3 study.

BACKGROUND: AJM300 is an oral, small-molecule α4-integrin antagonist. We assessed the efficacy and safety of AJM300 in patients with moderately active ulcerative colitis. METHODS: This multicentre, randomised, double-blind, placebo-controlled, phase 3 study consisted of two phases: a treatment phase and an open-label re-treatment phase. The study was done at 82 hospitals and clinics in Japan. Patients with a Mayo Clinic score of 6-10, endoscopic subscore of 2 or more, rectal bleeding subscore of 1 or more, and an inadequate response or intolerance to mesalazine were enrolled. Patients were randomly allocated (1:1) via a website to either AJM300 (960 mg) or placebo by the minimisation method, which was adjusted centrally by dynamic assignment against the Mayo Clinic score (≥6 to ≤7, ≥8 to ≤10 points), any use of corticosteroid, anti-TNFα antibody, or immunosuppressants during the disease-active period (yes vs no), duration of induction therapy until randomisation (<4 weeks vs ≥4 weeks) as the minimisation factors. Patients, investigators, site staff, assessors, and the sponsor were masked to treatment assignments. The study drug was administered orally, three times daily, for 8 weeks, and continued for up to 24 weeks if endoscopic remission was not achieved or rectal bleeding did not stop. The primary endpoint was the proportion of patients with a clinical response at week 8, and was analysed in the full analysis set. Clinical response was defined as a reduction in Mayo Clinic score of 30% or more and 3 or more, a reduction in rectal bleeding score of 1 or more or rectal bleeding subscore of 1 or less, and an endoscopic subscore of 1 or less at week 8. The study is registered with ClinicalTrials.gov, NCT03531892, and is closed to recruitment. FINDINGS: Between June 6, 2018, and July 22, 2020, 203 patients were randomly assigned to AJM300 (n=102) or placebo (n=101). At week 8, 46 (45%) patients in the AJM300 group and 21 (21%) patients in the placebo group had a clinical response (odds ratio 3·30, 95% CI 1·73-6·29; p=0·00028). During the 8-week treatment and 16-week extension treatment periods, adverse events occurred in 39 (39%) of 101 patients in the placebo group and 39 (38%) of 102 patients in the AJM300 group. We found no difference in the incidence of adverse events between groups or after repeated administration of AJM300. The most common adverse event was nasopharyngitis (11 [11%] of 101 patients in the placebo group and ten [10%] of 102 patients in the AJM300 group). The most common treatment-related adverse event was also nasopharyngitis (four [4%] of 101 patients in the placebo group and three [3%] of 102 patients in the AJM300 group). Most adverse events were mild-to-moderate in severity. No deaths were reported. A serious adverse event was reported in the AJM300 group (one patient with anal abscess), but this was judged to be unrelated to study drug. INTERPRETATION: AJM300 was well tolerated and induced a clinical response in patients with moderately active ulcerative colitis who had an inadequate response or intolerance to mesalazine. AJM300 could be a novel induction therapy for the treatment of patients with moderately active ulcerative colitis. FUNDING: EA Pharma and Kissei Pharmaceutical. TRANSLATION: For the Japanese translation of the abstract see Supplementary Materials section.

Importance of Telomere Shortening in the Pathogenesis of Ulcerative Colitis: A New Treatment From the Aspect of Telomeres in Intestinal Epithelial Cells.

BACKGROUND AND AIMS: Ulcerative colitis [UC] is a chronic inflammatory disease of the colon with frequent relapses. Telomere shortening in intestinal epithelial cells has been reported in severe or longstanding cases. However, its influence on UC pathogenesis remains unelucidated. To this end, we evaluated telomere shortening using a long-term organoid inflammation model that we had originally established. METHODS: A UC model using human colon organoids was established to assess telomere changes chronologically. MST-312 was used for the telomerase inhibition assay. The potential of telomerase activators as a novel UC treatment was evaluated with an in vitro model, including microarray analysis, and histological changes were assessed using xenotransplantation into mouse colonic mucosa. RESULTS: Our UC model reproduced telomere shortening in vitro, which was induced by the continuous suppression of telomerase activity via P53. MST-312-based analysis revealed that telomere shortening was involved in the pathogenesis of UC. Madecassoside [MD] improved the telomere length of the UC model and UC patient-derived organoids, which further promoted cell proliferation in vitro and improved the graft take-rate of xenotransplantation. Moreover, histological analysis revealed that MD induced normal crypt structure with abundant goblet cells. CONCLUSIONS: This study is the first to reveal the mechanism and importance of telomere shortening in the pathogenesis of UC. MD could be a novel candidate for UC treatment beyond endoscopic mucosal healing.

Predictive factors for achievement of mucosal healing by budesonide 2-mg foam in ulcerative colitis: a pooled analysis of data from two clinical trials.

BACKGROUND/AIMS: Mucosal healing (MH) of distal lesions in ulcerative colitis (UC) has recently been confirmed with budesonide 2-mg foam (BF) treatment in 2 clinical trials; however, few studies have investigated the predictive factors for complete MH. METHODS: We conducted a post hoc analysis using pooled data from phase II and III clinical trials evaluating the efficacy and safety of BF for UC. Additionally, we analyzed the relationships between complete MH and baseline factors and clinical symptoms from baseline to week 6. RESULTS: Among the 291 Japanese patients from the 2 pooled clinical studies, 119 patients in the BF twice a day group and 117 in the placebo group were included in the full analysis set. The proportion of patients with a rectal bleeding (RB) subscore of 0 was significantly higher in the BF group than in the placebo group after a 5-day treatment (P<0.05). After a 2-day treatment, significantly more patients in the BF group had a stool frequency (SF) subscore of 0 than patients in the placebo group (P<0.05). Multivariate analysis showed that complete MH at week 6 was influenced by baseline SF subscore and 5-aminosalicylic acid (5-ASA) enema or suppository use (P=0.0086 and P=0.0015, respectively). The relationship between complete MH at week 6 and RB subscore after week 2 was also confirmed. CONCLUSIONS: Normal SF at baseline, history of 5-ASA topical product use, and elimination of RB after week 2 are suggested predictors of complete MH at week 6 with twice-daily BF treatment.

Efficacy of Indigo Naturalis in a Multicenter Randomized Controlled Trial of Patients With Ulcerative Colitis.

BACKGROUND & AIMS: Indigo naturalis (IN) is a traditional Chinese medicine that contains ligands for the aryl hydrocarbon receptor and promotes regeneration of the mucosa by inducing production of interleukin 22. IN might induce mucosal healing in patients with ulcerative colitis (UC). We performed a randomized controlled trial to investigate the safety and efficacy of IN in patients with UC. METHODS: We performed a multicenter, double-blind trial evaluating the safety of 86 patients in Japan with active UC (Mayo scores of 6 or more), enrolled from March 30 through December 27, 2016. Patients were randomly assigned to groups and given a daily dose of 0.5, 1.0, or 2.0 g IN or placebo (1:1:1:1 ratio) for 8 weeks. The primary endpoint was the rate of clinical response at week 8, defined as a 3-point decrease in the Mayo score and a decrease of at least 30% from baseline, with a decrease of at least 1 point for the rectal bleeding subscore or absolute rectal bleeding score of 0-1. The main secondary endpoint was the rate of clinical remission at week 8, defined as a Mayo score or ≤2 and no subscores with a value >1. Mucosal healing was also assessed at week 8. RESULTS: The trial was terminated because of an external reason: a report of pulmonary arterial hypertension in a patient who used self-purchased IN for 6 months. In the intent-to-treat analysis, we observed a significant, dose-dependent linear trend in proportions of patients with clinical responses (13.6% with a clinical response to placebo; 69.6% to 0.5 g IN; 75.0% to 1.0 g IN; and 81.0% to 2.0 g IN) (Cochran-Armitage trend test P < .0001 compared with placebo). Proportions of patients in clinical remission at week 8 were significantly higher in the 1.0 g IN group (55.0%, P = .0004) and the 2.0 g IN group (38.1%, (P = .0093) than in the placebo group (4.5%). Proportions of patients with mucosal healing were 13.6% in the placebo group, 56.5% in the 0.5 g IN group, 60.0% in the 1.0 g IN group, and 47.6% in the 2.0 g IN group (P = .0278 compared with placebo). Although mild liver dysfunction was observed in 10 patients who received IN, no serious adverse events were observed. CONCLUSIONS: In a randomized, placebo-controlled trial, we found 8 weeks of IN (0.5-2.0 g per day) to be effective in inducing a clinical response in patients with UC. However, IN should not yet be used because of the potential for adverse effects, including pulmonary arterial hypertension. Clinical Trials Registry no: UMIN000021439 (http://www.umin.ac.jp/ctr/).

Evidence-based clinical practice guidelines for gastroesophageal reflux disease 2015.

As an increase in gastroesophageal reflux disease (GERD) has been reported in Japan, and public interest in GERD has been increasing, the Japanese Society of Gastroenterology published the Evidence-based Clinical Practice Guidelines for GERD (1st edition) in 2009. Six years have passed since its publication, and there have been a large number of reports in Japan concerning the epidemiology, pathophysiology, treatment, and Barrett's esophagus during this period. By incorporating the contents of these reports, the guidelines were completely revised, and a new edition was published in October 2015. The revised edition consists of eight items: epidemiology, pathophysiology, diagnosis, internal treatment, surgical treatment, esophagitis after surgery of the upper gastrointestinal tract, extraesophageal symptoms, and Barrett's esophagus. This paper summarizes these guidelines, particularly the parts related to the treatment for GERD. In the present revision, aggressive proton pump inhibitor (PPI) maintenance therapy is recommended for severe erosive GERD, and on-demand therapy or continuous maintenance therapy is recommended for mild erosive GERD or PPI-responsive non-erosive GERD. Moreover, PPI-resistant GERD (insufficient symptomatic improvement and/or esophageal mucosal break persisting despite the administration of PPI at a standard dose for 8 weeks) is defined, and a standard-dose PPI twice a day, change in PPI, change in the PPI timing of dosing, addition of a prokinetic drug, addition of rikkunshito (traditional Japanese herbal medicine), and addition of histamine H2-receptor antagonist are recommended for its treatment. If no improvement is observed even after these treatments, pathophysiological evaluation with esophageal impedance-pH monitoring or esophageal manometry at an expert facility for diseases of the esophagus is recommended.

Functional relevance of intestinal epithelial cells in inflammatory bowel disease.

The intestinal epithelium constitutes a physical barrier between inner and outer side of our body. It also functions as a "hub" which connects factors that determine the development of inflammatory bowel disease, such as microbiota, susceptibility genes, and host immune response. Accordingly, recent studies have implicated and further featured the role of intestinal epithelial cell dysfunction in the pathophysiology of inflammatory bowel disease. For example, mucin producing goblet cells are usually "depleted" in ulcerative colitis patients. Studies have shown that those goblet cells exhibit various immune-regulatory functions in addition to mucin production, such as antigen presentation or cytokine production. Paneth cells are another key cell lineage that has been deeply implicated in the pathophysiology of Crohn's disease. Several susceptibility genes for Crohn's disease may lead to impairment of anti-bacterial peptide production and secretion by Paneth cells. Also, other susceptibility genes may determine the survival of Paneth cells, which leads to reduced Paneth cell function in the patient small intestinal mucosa. Further studies may reveal other unexpected roles of the intestinal epithelium in the pathophysiology of inflammatory bowel disease, and may help to develop alternative therapies targeted to intestinal epithelial cell functions.

Wnt5a signaling mediates biliary differentiation of fetal hepatic stem/progenitor cells in mice.

UNLABELLED: The molecular mechanisms regulating differentiation of fetal hepatic stem/progenitor cells, called hepatoblasts, which play pivotal roles in liver development, remain obscure. Wnt signaling pathways regulate the development and differentiation of stem cells in various organs. Although a ß-catenin-independent noncanonical Wnt pathway is essential for cell adhesion and polarity, the physiological functions of noncanonical Wnt pathways in liver development are unknown. Here we describe a functional role for Wnt5a, a noncanonical Wnt ligand, in the differentiation of mouse hepatoblasts. Wnt5a was expressed in mesenchymal cells and other cells of wild-type (WT) midgestational fetal liver. We analyzed fetal liver phenotypes in Wnt5a-deficient mice using a combination of histological and molecular techniques. Expression levels of Sox9 and the number of hepatocyte nuclear factor (HNF)1ß(+) HNF4α(-) biliary precursor cells were significantly higher in Wnt5a-deficient liver relative to WT liver. In Wnt5a-deficient fetal liver, in vivo formation of primitive bile ductal structures was significantly enhanced relative to WT littermates. We also investigated the function of Wnt5a protein and downstream signaling molecules using a three-dimensional culture system that included primary hepatoblasts or a hepatic progenitor cell line. In vitro differentiation assays showed that Wnt5a retarded the formation of bile duct-like structures in hepatoblasts, leading instead to hepatic maturation of such cells. Whereas Wnt5a signaling increased steady-state levels of phosphorylated calcium/calmodulin-dependent protein kinase II (CaMKII) in fetal liver, inhibition of CaMKII activity resulted in the formation of significantly more and larger-sized bile duct-like structures in vitro compared with those in vehicle-supplemented controls. CONCLUSION: Wnt5a-mediated signaling in fetal hepatic stem/progenitor cells suppresses biliary differentiation. These findings also suggest that activation of CaMKII by Wnt5a signaling suppresses biliary differentiation. (HEPATOLOGY 2013;).

Luminal CD4⁺ T cells penetrate gut epithelial monolayers and egress from lamina propria to blood circulation.

BACKGROUND & AIMS: The egress of memory T cells from peripheral tissues, such as lung and skin, into the draining lymph nodes requires their expression of CC chemokine receptor 7 (CCR7). In the intestine, resident memory T cells in the intestinal lamina propria (LP) do not express CCR7, indicating that they are tissue bound and do not exit the intestine. METHODS: We developed a cell transfer system, using rectal administration of lymphocytes to C57BL/6 mice. Lymphotoxin α-deficient mice were crossed with RAG-2(-/-) (recombination-activating gene-2) mice to generate lymphotoxin α-deficient × RAG-2(-/-) mice. RESULTS: Severe combined immunodeficient (SCID) or RAG-2(-/-) mice given rectal administration of splenic CD4(+) T cells from normal mice developed colitis; the cells proliferated not only in the LP but also in spleen. SCID or RAG-2(-/-) mice given rectal administrations of CD4(+) T cells that expressed green fluorescent protein (GFP(+)CD4(+) T cells) localized to the LP within 6 hours but were not found in the spleen until 24 hours after administration. Immunohistochemical and electron microscopic analyses detected CD4(+) T cells in the intraepithelial space just 3 hours after intrarectal administration. However, neither CCR7 deficiency nor the sphingosine-1-phosphate receptor agonist Fingolimod impaired the egress of CD4(+) T cells from LP to systemic circulation. CONCLUSIONS: CD4(+) T cells not only penetrate from the luminal side of the intestine to the LP but also actively egress from the LP into the circulation. We developed a rectal administration system that might be used to further investigate cell trafficking in intestinal mucosa and to develop enema-based therapeutics for intestinal diseases.

Magnetic resonance enterocolonography is useful for simultaneous evaluation of small and large intestinal lesions in Crohn's disease.

BACKGROUND: We developed novel magnetic resonance enterocolonography (MREC) for simultaneously evaluating both small and large bowel lesions in patients with Crohn's disease (CD). The aim of this study was to evaluate the diagnostic performance of MREC by comparing results of this procedure to those of endoscopies for evaluating the small and large bowel lesions of patients with CD. METHODS: Thirty patients with established CD were prospectively examined by newly developed MREC. Patients underwent ileocolonoscopy (ICS) (24 procedures) or double-balloon endoscopy (DBE) (10 procedures) after MREC on the same day. Two gastroenterologists and two radiologists who were blinded to the results of another study evaluated endoscopy and MREC findings, respectively. RESULTS: In colonic lesions the sensitivities of the MREC for deep mucosal lesions (DML), all CD lesions, and stenosis were 88.2, 61.8, and 71.4%, respectively, while the specificities were 98.1, 95.3, and 97.7%, respectively. In small intestinal lesions, MREC sensitivities for DML, all CD lesions, and stenosis were 100, 85.7, and 100%, respectively, while specificities were 100, 90.5, and 93.1%, respectively. Endoscopic scores were significantly correlated with MREC scores. Eleven (46%) of the 24 patients who were clinically not suspected to show stricture were observed to demonstrate stricture by radiologists. CONCLUSIONS: Our results demonstrated that MREC can simultaneously detect the CD lesions of the small and large intestine. MREC can be performed without radiation exposure, the use of enema, or the placement of a naso-jejunal catheter. MREC and endoscopy have comparable abilities for evaluating mucosal lesions of patients with CD.

Inhibitory effect of a triterpenoid compound, with or without alpha interferon, on hepatitis C virus infection.

A lack of patient response to alpha interferon (α-IFN) plus ribavirin (RBV) treatment is a major problem in eliminating hepatitis C virus (HCV). We screened chemical libraries for compounds that enhanced cellular responses to α-IFN and identified a triterpenoid, toosendanin (TSN). Here, we studied the effects and mechanisms of action of TSN on HCV replication and its effect on α-IFN signaling. We treated HCV genotype 1b replicon-expressing cells and HCV-J6/JFH-infected cells with TSN, with or without α-IFN, and the level of HCV replication was quantified. To study the effects of TSN on α-IFN signaling, we detected components of the interferon-stimulated gene factor 3 (ISGF3), phosphorylated signal transducer and activator of transcription 1 (STAT1), and STAT2 by Western blotting analysis; expression levels of mRNA of interferon regulatory factor 9 using real-time reverse transcription-PCR (RT-PCR); and interferon-stimulated response element reporter activity and measured the expression levels of interferon-inducible genes for 2',5'-oligoadenylate synthetase, MxA, protein kinase R, and p56 using real-time RT-PCR. TSN alone specifically inhibited expression of the HCV replicon (50% effective concentration = 20.6 nM, 50% cytotoxic concentration > 3 µM, selectivity index > 146). Pretreatment with TSN prior to α-IFN treatment was more effective in suppressing HCV replication than treatment with either drug alone. Although TSN alone did not activate the α-IFN pathway, it significantly enhanced the α-IFN-induced increase of phosphorylated STATs, interferon-stimulated response element activation, and interferon-stimulated gene expression. TSN significantly increased baseline expression of interferon regulatory factor 9, a component of interferon-stimulated gene factor 3. Antiviral effects of treatment with α-IFN can be enhanced by pretreatment with TSN. Its mechanisms of action could potentially be important to identify novel molecular targets to treat HCV infection.

New therapeutic approaches to hepatitis C virus.

Year 201X will see a huge battle against hepatitis C virus (HCV) infection. HCV, a leading cause of end stage diseases and hepatocellular malignancies, is a negative legacy of the past in many regions worldwide, and has long been refractory to conventional treatments. The most effective peginterferons and ribavirin-based antiviral therapies can eliminate the virus in only half of patients treated, and the treatments are often poorly tolerated. Recently, the development of an HCV cell culture system has become a turning point of basic research. At present, novel therapeutic agents with different mechanisms of action are under development or on clinical trials. Some of these drugs have been proven to be effective when used with the conventional treatments, and may constitute antiviral therapies without being used in combination with interferons. This article reviews the current status of preclinical drug development, ongoing clinical trials, and near future perspectives in the field of HCV therapeutics.

Homeostatic (IL-7) and effector (IL-17) cytokines as distinct but complementary target for an optimal therapeutic strategy in inflammatory bowel disease.

PURPOSE OF REVIEW: This review focuses on CD4+ T cells involved in the mediation of inflammatory tissue damage in murine models of inflammatory bowel diseases (IBDs). In particular, we describe the distinct roles of the homeostatic cytokine IL-7, which is essential to the maintenance of colitogenic memory CD4+ cells, and the newly discovered effector cytokine IL-17. We also discuss the close correlation between colitogenic Th17-type CD4+ T cells and inducible CD4+CD25+Foxp3+ regulatory T cells. RECENT FINDINGS: IBDs are characterized by wasting and chronic intestinal inflammation induced by many different cytokine-mediated pathways. It is clearly recognized that medical and surgical interventions do not cure Crohn's disease because relapse is the rule after remission. Until a few years ago, IBD was classified into Th1-dependent, that is, Crohn's disease, and Th2-dependent, that is, ulcerative colitis, phenotypes. However, in recent years, it has been shown that new T-cell subclasses, that is, Th17 and regulatory T cells (T(R)), exist independently of Th1 and Th2 and that they play a central role in modulating IBD. SUMMARY: The persistence of IL-7-dependent colitogenic memory CD4+ T cells is critical to the maintenance of experimental colitis. On the other hand, though Th1 and Th2 colitogenic memory CD4+ cells exist, in recent years the central role of IL-17-producing Th17-type cells in IBD has attracted renewed interest. The development of molecularly targeted therapies aimed at a variety of different Th-dependent pathogenic mechanisms may represent a novel approach to IBD therapy.

Two flavonoids extracts from Glycyrrhizae radix inhibit in vitro hepatitis C virus replication.

AIM: Traditional herbal medicines have been used for several thousand years in China and other Asian countries. In this study we screened herbal drugs and their purified compounds, using the Feo replicon system, to determine their effects on in vitro HCV replication. METHODS: We screened herbal drugs and their purified extracts for the activities to suppress hepatitis C virus (HCV) replication using an HCV replicon system that expressed chimeric firefly luciferase reporter and neomycin phosphotransferase (Feo) genes. We tested extracts and 13 purified compounds from the following herbs: Glycyrrhizae radix; Rehmanniae radix; Paeoniae radix; Artemisiae capillari spica; and Rhei rhizoma. RESULTS: The HCV replication was significantly and dose-dependently suppressed by two purified compounds, isoliquiritigenin and glycycoumarin, which were from Glycyrrhizae radix. Dose-effect analyses showed that 50% effective concentrations were 6.2 +/- 1.0 microg/mL and 15.5 +/- 0.8 microg/mL for isoliquiritigenin and glycycoumarin, respectively. The MTS assay did not show any effect on cell growth and viability at these effective concentrations, indicating that the effects of the two compounds were specific to HCV replication. These two compounds did not affect the HCV IRES-dependent translation nor did they show synergistic action with interferon-alpha. CONCLUSION: Two purified herbal extracts, isoliquiritigenin and glycycoumarin, specifically suppressed in vitro HCV replication. Further elucidation of their mechanisms of action and evaluation of in vivo effects and safety might constitute a new anti-HCV therapeutics.

Fusion of OTT to BSAC results in aberrant up-regulation of transcriptional activity.

OTT/RBM15-BSAC/MAL/MKL1/MRTF-A was identified as a fusion transcript generated by t(1;22)(p13;q13) in acute megakaryoblastic leukemia. Previous studies have shown that BSAC (basic, SAP, and coiled-coil domain) activates the promoters containing CArG boxes via interaction with serum response factor, and OTT (one twenty-two) negatively regulates the development of megakaryocytes and myeloid cells. However, the mechanism by which OTT-BSAC promotes leukemia is largely unknown. Here we show that OTT-BSAC, but not BSAC or OTT strongly activates several promoters containing a transcription factor Yin Yang 1-binding sequence. In addition, although BSAC predominantly localizes in the cytoplasm and its nuclear translocation is considered to be regulated by the Rho-actin signaling pathway, OTT-BSAC exclusively localizes in the nucleus. Moreover, OTT interacts with histone deacetylase 3, but this interaction is abolished in OTT-BSAC. Collectively, these functional and spatial changes of OTT and BSAC caused by the fusion might perturb their functions, culminating in the development of acute megakaryoblastic leukemia.

Ameliorating effect of saporin-conjugated anti-CD11b monoclonal antibody in a murine T-cell-mediated chronic colitis.

BACKGROUND: Crohn's disease (CD) is an inflammatory bowel disease that is associated with several changes in the immune system, including an increased number of infiltrating macrophages. These macrophages release a variety of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) which are critically involved in the onset and the development of CD. The present study was performed to explore the initial involvement of macrophages in the development of T-cell-mediated chronic colitis. METHODS: The effects were evaluated of saporin-conjugated anti-CD11b monoclonal antibody (mAb) on the development of chronic colitis in severe combined immunodeficiency (SCID) mice induced by adoptive transfer of CD4(+)CD45RB(high) T cells as an animal model of CD. RESULTS: Significantly increased CD11b-expressing macrophages as well as CD4(+) T cells were found in inflamed colon from colitic mice. Administration of saporin-conjugated anti-CD11b mAb markedly ameliorated the clinical and histopathological disease. In vivo treatment with saporin-conjugated anti-CD11b mAb decreased CD4(+) T-cell infiltration in the colon and suppressed interferon-gamma (IFN-gamma) and TNF-alpha production by lamina propria CD4(+) T cells. CONCLUSIONS: Collectively, the present results suggest an initial role of macrophages in the pathogenesis of T-cell-mediated chronic colitis. Furthermore, the macrophage-specific targeting may be a promising strategy for therapeutic intervention in CD.