Targeting leukocyte trafficking for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic immune-mediated inflammatory disease of the intestine that includes both Crohn's disease and ulcerative colitis, and afflicts nearly 1 million people throughout North America. As our understanding of IBD pathogenesis grows, several new therapies have been developed that use monoclonal antibodies to specifically target key mediators and biological pathways implicated in IBD immune dysfunction. One important pathway involves leukocyte trafficking and infiltration into the affected intestinal tissues. This review provides a summary of the different therapies that have been developed to inhibit leukocyte trafficking to the inflamed gut, and evaluates the relative safety and efficacy of these novel drugs within the context of existing medical therapies for IBD.

ZBP-89, Sp1, and nuclear factor-kappa B regulate epithelial neutrophil-activating peptide-78 gene expression in Caco-2 human colonic epithelial cells

We reported previously that human colonic epithelial cells produce the C-X-C chemokine epithelial neutrophil-activating peptide-78 (ENA-78) and that its expression is up-regulated in ulcerative colitis. The aim of this study was to investigate the transcriptional regulation of ENA-78 gene expression in Caco-2 intestinal epithelial cells. Reporter gene transfection and electrophoretic mobility shift assay studies demonstrated that cooperation between two regions of the ENA-78 promoter were required for maximal gene expression in interleukin-1beta-stimulated Caco-2 cells. Binding of activated p50/p65 nuclear factor-kappaB to nucleotides -82 to -91 was essential for interleukin-1beta-dependent gene transcription, whereas binding of constitutively expressed zinc-requiring nuclear factors to nucleotides -125 to -134 (site A) was required for basal gene expression. Scanning mutagenesis of site A demonstrated overlapping binding elements at this locus. One site (CTCCCCC) bound Sp1 and Sp3, and overexpression of Sp1 (but not Sp3) up-regulated basal ENA-78 transcription. Another site (CCCCTCCCCC) was found to bind the zinc finger nuclear factor ZBP-89, and overexpression of this protein significantly repressed ENA-78 reporter gene activity. This study demonstrates that ENA-78 gene expression in Caco-2 intestinal epithelial cells is subject to complex regulation involving the coordinate binding of ZBP-89, Sp1, and nuclear factor-kappaB to the ENA-78 promoter.

Cost-utility of initial medical management for Crohn's disease perianal fistulae

BACKGROUND & AIMS

The cost-utility of infliximab is unknown. The aim of this study was to determine the incremental cost-utility (CU(inc)) of medical therapy for Crohn's disease (CD) perianal fistula.

METHODS

A Markov model was used to simulate a 1-year treatment period with the following: 6-mercaptopurine and metronidazole [6MP/met] (comparator), 3 infliximab infusions + 6MP/met as second-line therapy (intervention I), infliximab with episodic reinfusion (intervention II), and 6MP/met + infliximab as second-line therapy (intervention III). Utilities were elicited from patients with CD and healthy individuals by standard gamble, and costs were obtained from hospital billing data. Uncertainty was assessed by sensitivity analysis.

RESULTS

All strategies had similar effectiveness. Interventions I, II, and III were slightly more effective, but also more costly than 6MP/met (Intervention I: CU(inc) = $355,450/quality-adjusted life-years [QALY]; Intervention II: CU(inc) = $360,900/QALY; Intervention III: CU(inc) = $377,000/QALY). If the cost of infliximab were reduced to $304 per infusion, the CU(inc) for intervention II would be $54,050/QALY.

CONCLUSIONS

Based on available data, all strategies had similar effectiveness in our model, but infliximab was much more expensive than 6MP/met. The incremental benefit of infliximab for treating CD perianal fistulae over a 1-year period may not justify the higher cost. Prospective studies directly comparing 6MP/met and infliximab are warranted.

The incidence of lymphoid and myeloid malignancies among hospitalized Crohn's disease patients

An association may exist between Crohn's disease (CD) and lymphoid/myeloid malignancies. We aimed to evaluate the 2-year cumulative incidence rate of lymphoid/myeloid malignancy among hospitalized CD patients. This is a retrospective cohort study using hospital discharge data from California and Virginia. Cohorts were defined by the presence or absence of a CD diagnosis in all patients discharged during a single calendar year (Year-2). The presence or absence of lymphoid/myeloid malignancy was determined for all hospitalizations during a 4-year period (Year-1 to Year-4) for each member of both cohorts. To obtain a 2-year cumulative incidence rate, patients with lymphoid/myeloid malignancy prior to or at the time of their first admission in Year-2 were excluded. Patients were followed for 8 quarters after this admission for the incidence of lymphoid/myeloid malignancy. Cumulative incidence rates and odds ratios were calculated. The crude 2-year incidence rate of lymphoid/myeloid malignancy among hospitalized CD patients was 3.87/1.000 CD patients (21/5,426; 95% CI = 2.40-5.92). The odds ratio adjusted for age, gender, and race was 2.04 (95% CI = 1.33-3.14, p < 0.001). The 2-year cumulative incidence of lymphoid/myeloid malignancies among hospitalized CD patients is greater than that seen in hospitalized patients without CD. This finding supports the need for further prospective population-based studies.

Interleukin 16 is up-regulated in Crohn's disease and participates in TNBS colitis in mice

BACKGROUND & AIMS

Interleukin (IL)-16 is a T lymphocyte- derived cytokine that uses CD4 as its receptor and hence selectively recruits CD4-bearing cells. Infiltrating CD4(+) T cells are a feature of Crohn's disease; however, the role of IL-16 in intestinal inflammation is unknown. The aim of this study was to determine whether IL-16 production is increased in inflammatory bowel disease and whether IL-16 participates in trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice.

METHODS

IL-16 messenger RNA and protein levels in inflammatory bowel disease tissues were determined by reverse-transcription polymerase chain reaction and enzyme-linked immunosorbent assay. C57BL/6 or BALB/c mice were treated with vehicle, TNBS alone, TNBS + anti-IL-16 monoclonal antibody (mAb), TNBS + control mAb, or were untreated. Colonic injury and inflammation were evaluated after 3 or 10 days.

RESULTS

Colonic IL-16 protein levels were increased in patients with Crohn's disease (P<0.05) but not ulcerative colitis. Anti-IL-16 mAb treatment significantly reduced TNBS-induced weight loss (P< 0.001), mucosal ulceration (P<0.05), myeloperoxidase activity (P< 0.001), and TNBS-mediated increases in mucosal levels of IL-1beta (P<0.05) and tumor necrosis factor alpha (P<0.01).

CONCLUSIONS

Anti-IL-16 mAb reduced colonic injury and inflammation induced by TNBS in mice. Colonic mucosal IL-16 levels were elevated in Crohn's disease, suggesting a role for IL-16 in the pathophysiology of inflammatory bowel disease.

Discovering the cause of inflammatory bowel disease: lessons from animal models

The precise cause of inflammatory bowel disease remains unclear. Relevant animal models are important tools for studying the underlying mechanisms of inflammation and disease pathogenesis. The purpose of this review is to summarize the various types of animal models available for use in inflammatory bowel disease research and to illustrate how these models have contributed to a better understanding of the etiopathogenesis of inflammatory bowel disease, particularly focusing on papers published during calendar year 1999. Studies using appropriate animal models have provided important discoveries in this field of investigation. These include determination of the key role that pathogenic and regulatory T cells, proinflammatory and immunoregulatory cytokines, indigenous bacterial flora, and putative predisposing genes play in the disease process. The availability of new animal models that closely resemble the human disease is expected to allow further characterization of the initiating event(s) in inflammatory bowel disease and lead to a possible cure for this devastating disease.

Lessons from genetically engineered animal models XI. Novel mouse models to study pathogenic mechanisms of Crohn's disease

Crohn's Disease (CD) affects more than 500,000 individuals in the United States and represents the second most common chronic inflammatory disorder after rheumatoid arthritis. Although major advances have been made in defining the basic mechanisms underlying chronic intestinal inflammation, the precise etiopathogenesis of CD remains unknown. We have recently characterized two novel mouse models of enteritis that express a CD-like phenotype, namely the TNF DeltaARE model of tumor necrosis factor (TNF) overexpression and the SAMP1/Yit model of spontaneous ileitis. The unique feature of these models is that they closely resemble CD for location and histopathology. These genetically manipulated new models of intestinal inflammation offer a powerful tool to investigate potential causes of human disease and may allow the development of novel disease-modifying therapeutic modalities for the treatment of CD.

The relationship between infliximab treatment and lymphoma in Crohn's disease

The relationship between chronic inflammatory conditions and malignancy is complex. We describe the clinical course of 2 patients with Crohn's disease (CD) in whom lymphoma was diagnosed after treatment with infliximab. The first patient was a 61-year-old man with a 30-year history of fistulizing CD in whom B-cell non-Hodgkin's lymphoma was diagnosed 9 months after treatment with infliximab. The second is a 29-year-old man with CD in whom nodular sclerosing Hodgkin's lymphoma was diagnosed 3 weeks after infusion with infliximab. The lymphoma presented with pleural effusions, mediastinal and cervical adenopathy, and no gastrointestinal lesion. We describe the implications of these cases for the use of immunomodulatory therapy in CD and the questionable association between CD and lymphoma.