Natalizumab for active Crohn's disease

Distinctive pattern of cytokine production and adhesion molecule expression in peripheral blood memory CD4+ T cells from patients with active Crohn's disease

An expansion of both circulating and intestinal lamina propria CD4+ CD45RO+ T cells has been described in patients with Crohn's disease. We studied both the cytokine profile and the expression of adhesion molecules on this T-cell subset. Peripheral blood CD4+ CD45RO+ T cells from patients with Crohn's disease (n=45) were assessed by flow cytometry and RT-PCR methods. The cytokine profile was also measured in intestinal lamina propria from seven patients. They were classified according to the CDAI and the results were compared with those of patients with ulcerative colitis (n=21) and noninflammatory intestinal conditions (n=15), and healthy controls (n=39). The mean percentage of circulating CD4+ CD45RO+ T cells producing intracellular TNF was higher in active than in inactive Crohn's disease patients (p < 0.001), active (p = 0.49) and inactive ulcerative colitis (p = 0.019), and healthy controls (p =0. 017). TNF expression correlated with CDAI (p < 0.001). An increased expression of intracellular IL-2, IL-6, and IL-10 in active Crohn's disease patients was also found. CD62L was downregulated in active Crohn's disease patients while no differences were observed in CD49d and CD11a expression. Lamina propria CD4+ CD45RO+ T cells from active Crohn's disease lesions showed an increased intracellular staining of TNF, IFN-gamma, and IL-10. Both peripheral and intestinal mucosa CD4+ CD45RO+ T cells from active Crohn's disease patients show an increased production of TNF. In addition, the circulating CD4+ CD45RO+ T-cell subset expresses a pattern of adhesion molecules that promotes homing to extranodal lymphoid tissues. This T-cell subset may play a relevant role in the immunopathogenesis of Crohn's disease.

The changing face of treatment for Crohn's disease

Blocking lymphocyte migration holds promise

Euroconference on tissue repair and ulcer/wound healing: molecular mechanisms, therapeutic targets and future directions

The meeting was part of the Euroconference series organised at the Pasteur Institute in Paris. Comprising delegates from both academia and industry, it drew on expertise from many aspects of tissue repair in a wide range of human disease. The principal component of this report concerns progress with the therapeutic application of biological agents in promoting tissue repair, as gene therapeutics, monoclonal antibodies and therapeutic proteins. In addition, the effect of pioglitazone on the rate and quality of wound healing in diabetic rats is also reported.

Evolving knowledge and therapy of inflammatory bowel disease

With recent advances in the understanding of its pathophysiology, inflammatory bowel disease has become a very active area for the development of novel therapeutic agents. New targets for biologics include cytokines involved in T-cell activation, with antibodies directed against IL-12 and interferon-gamma. Selective adhesion molecule blockade has produced promising, though mixed, results. Recombinant human granulocyte-macrophage colony-stimulating factor might be effective in active Crohn's disease, presumably through stimulation of intestinal innate immune responses. With increasing evidence for a crucial role for luminal flora in maintaining the health of the bowel, strategies to manipulate intestinal bacteria using probiotics and prebiotics are being actively investigated as well.

Randomized, double blind controlled trial of subcutaneous recombinant human interleukin-11 versus prednisolone in active Crohn's disease

BACKGROUND

Interleukin-11 has shown benefit in animal inflammatory bowel disease models. Recently, recombinant human interleukin-11 (rhIL-11) has been observed to induce remission in a subset of patients with mild to moderate Crohn's disease (CD). The present study compared the efficacy of rhIL-11 versus prednisolone in remission induction in CD.

METHODS

Patients with active CD were randomly assigned to receive either subcutaneous rhIL-11 (1 mg once weekly) and prednisolone placebo tablets, or active prednisolone (60 mg/day) and rhIL-11 placebo, for 12 weeks. Prednisolone/placebo was tapered after week 1, and patients were assessed every second week.

RESULTS

Fifty-one patients received medication: 13/27 (rhIL-11) and 17/24 (prednisolone) completed 12 weeks of treatment. Remission rates (intent to treat) for rhIL-11 versus prednisolone were 4% versus 46% at week 4 (p < 0.001) and 19% versus 50% at week 6 (p < 0.05). Response to treatment (deltaCDAI > 100) was seen in 19% (rhIL-11) versus 63% (prednisolone) after 4 weeks (p < 0.002) and 37% versus 63% after 6 weeks (p = 0.1). After 12 weeks of treatment, it was observed that 22% (rhIL-11) versus 21% (prednisolone) had remained in remission. Frequent side effects of rhIL-11 included fever (n = 3), rash (4), arthralgia/arthritis (3), nausea/vomiting (3), and headache (6).

CONCLUSION

rhIL-11 is well tolerated but significantly inferior when compared to prednisolone in short-term remission induction in patients with active CD. In this patient cohort, both treatments appeared to be poor in maintaining remission over a period of 3 months.

Charting protein complexes, signaling pathways, and networks in the immune system

Systematic deciphering of protein-protein interactions has the potential to generate comprehensive and instructive signaling networks and to fuel new therapeutic and diagnostic strategies. Here, we describe how recent advances in high-throughput proteomic technologies, involving biochemical purification methods and mass spectrometry analysis, can be applied systematically to the characterization of protein complexes and the computation of molecular networks. The networks obtained form the basis for further functional analyses, such as knockdown by RNA interference, ultimately leading to the identification of nodes that represent candidate targets for pharmacological exploitation. No individual experimental approach can accurately elucidate all critical modulatory components and biological aspects of a signaling network. Such functionally annotated protein-protein interaction networks, however, represent an ideal platform for the integration of additional datasets. By providing links between molecules, they also provide links to all previous observations associated with these molecules, be they of genetic, pharmacological, or other origin. As exemplified here by the analysis of the tumor necrosis factor (TNF)-alpha/nuclear factor-kappaB (NF-kappaB) signaling pathway, the approach is applicable to any mammalian cellular signaling pathway in the immune system.

Nouvelles approches thérapeutiques des maladies autoimmunes

Over the past decade, new biological therapies have been developed to treat systemic autoimmune diseases. These new treatments, which target various steps of the immune response, include: B lymphocyte (BL) inhibitors, such as anti-CD20 monoclonal antibodies, BlyS antagonists, and tolerogens that inhibit specific BLs that produce pathogenic antibodies; inhibitors of costimulation between antigen-presenting cells and T lymphocytes (TL), such as monoclonal antibodies against CD40 ligand and CTLA4-Ig (abatecept); TL antagonists, which can inhibit proliferation of autoreactive T cells; cytokine antagonists; chemokine and adhesin antagonists, which inhibit trafficking of immunocompetent cells to target organs. These new approaches are based on a deeper understanding of the autoimmune response.

Aberrant homing of mucosal T cells and extra-intestinal manifestations of inflammatory bowel disease

Active inflammatory bowel disease (IBD) is often associated with simultaneous inflammation in the skin, eyes and joints. Inflammatory disease in the liver can also occur in patients with IBD but seems to be independent of inflammation in the bowel. In this Opinion article, we propose that the hepatic complications of IBD are mediated by long-lived mucosal T cells that are recruited to the liver in response to aberrantly expressed endothelial-cell adhesion molecules and chemokines that are normally restricted to the gut. Similar mechanisms might explain why certain diseases are associated with site-specific tissue distributions and might point to new therapeutic strategies that are based on modulating tissue-specific lymphocyte homing.

Current concept on the pathogenesis of inflammatory bowel disease-crosstalk between genetic and microbial factors: Pathogenic bacteria and altered bacterial sensing or changes in mucosal integrity take “toll”

The pathogenesis of inflammatory bowel disease (IBD) is only partially understood. Various environmental and host (e.g. genetic-, epithelial-, immune and non-immune) factors are involved. It is a multifactorial polygenic disease with probable genetic heterogeneity. Some genes are associated with IBD itself, while others increase the risk of ulcerative colitis (UC) or Crohn’s disease (CD) or are associated with disease location and/or behaviour. This review addresses recent advances in the genetics of IBD. The article discusses the current information on the crosstalk between microbial and genetic factors (e.g. NOD2/CARD15, SLC22A46A5 and DLG5). The genetic data acquired in recent years help in understanding the pathogenesis of IBD and can identify a number of potential targets for therapeutic intervention. In the future, genetics may help more accurately diagnose and predict disease course in IBD.

Critical role of endothelial P-selectin glycoprotein ligand 1 in chronic murine ileitis

L-selectin ligands might be relevant for inflammatory cell trafficking into the small intestine in a spontaneous model of chronic ileitis (i.e., SAMP1/YitFc mice). Immunoblockade of peripheral node addressin or mucosal addressin cell adhesion molecule 1 failed to ameliorate ileitis, whereas P-selectin glycoprotein ligand 1 (PSGL-1) neutralization attenuated both the adoptively transferred and spontaneous disease. PSGL-1 was detected in venules of mesenteric lymph node and small intestine by immunohistochemistry and confirmed by real-time reverse transcription polymerase chain reaction and flow cytometry. In addition, reconstitution of wild-type mice with PSGL-1^−/− bone marrow demonstrated that PSGL-1 messenger RNA and PSGL-1 protein expression remained on endothelium, localized within mesenteric lymph node and small intestine. Endothelial PSGL-1 bound P-selectin–IgG and its blockade or genetic deletion altered the recruitment of lymphocytes to the small intestine, as revealed by intravital microscopy and homing studies. Endothelial expression of PSGL-1 adds a new dimension to the various cellular interactions involved in small intestinal recruitment. Thus, the multiple roles of PSGL-1 may explain why targeting this single adhesion molecule results in attenuation of chronic murine ileitis, a disease previously resistant to antiadhesion molecule strategies.

Integrin alpha2beta1 regulates neutrophil recruitment and inflammatory activity in experimental colitis in mice

BACKGROUND

Human inflammatory bowel disease (e.g., Crohn's disease and ulcerative colitis), is associated with leukocyte accumulation in the inflamed intestinal tissue. Recent studies strongly suggest a role of beta1 integrin receptors in regulating tissue damage and disease symptoms related to inflammatory bowel disease. The aim of this study was to investigate the role of the collagen-binding alpha2beta1 integrin (CD49b/CD29) in dextran sodium sulfate-induced colitis in mice.

METHODS

Colitis was induced in mice through oral administration of 2% dextran sodium sulfate in drinking water. Rectal administration of anti-alpha2-monoclonal antibody (mAb) in 1 group was compared with oral treatment with betamethasone in another group and rectal administration of a control antibody in a third group. Clinical and histological signs of colitis, neutrophil infiltration into the colon mucosa, and gene expression of metalloproteinases were assessed.

RESULTS

Rectal administration of anti-alpha2-mAb was found to significantly reduce weight loss from 13.5% +/- 6.5% to 2.2% +/- 0.2% (P = 0.013 versus control mAb) and mucosal neutrophil infiltration from 47.2 +/- 10.0 to 6.6 +/- 8.0 neutrophils per counted area (P < 0.05 versus control mAb). Metalloproteinase gene expression was suppressed through anti-alpha2-mAb treatment. The protective effect against colitis seen after anti-alpha2beta1 integrin treatment was found to be favorable to the effect seen after high-dose oral betamethasone.

CONCLUSIONS

We demonstrate an alleviating action of the collagen-binding alpha2beta1 integrin in experimental colitis in mice and suggest that this effect is mediated by inhibition of neutrophil migration and activation. Local administration of function-blocking antibodies against integrin alpha2beta1 may provide novel avenues to treat inflammatory bowel disease.

Recent advances in the etiology and treatment of inflammatory bowel disease

Crohn's disease and ulcerative colitis, together comprising the inflammatory bowel diseases, currently affect up to 2 million people in the western developed countries. The pathogenesis of the disease is a complex one in which genetic, immunogenic, microbial and environmental factors contribute to the etiology of the disease. Recent advances in understanding the molecular mechanisms that determine this complex entity have provided insight for promising new therapies.

Crohn Disease: mural attenuation and thickness at contrast-enhanced CT Enterography--correlation with endoscopic and histologic findings of inflammation

PURPOSE

To determine retrospectively if quantitative measures of small-bowel mural attenuation and thickness at computed tomographic (CT) enterography correlate with endoscopic and histologic findings of small-bowel inflammation and to estimate the performance of these measures in predicting inflammatory Crohn disease.

MATERIALS AND METHODS

The institutional review board approved this HIPAA-compliant retrospective study, which was conducted with patient informed consent. CT enterography data in 96 patients (31 male patients and 65 female patients) who underwent ileoscopy with or without biopsy were examined for CT signs of active Crohn disease. The most highly enhancing segment of terminal ileum and a normal-appearing ileal loop were identified. After it was confirmed that semiautomated software could accurately measure mural attenuation and thickness, the selected terminal ileal and normal-appearing (control) ileal loops were examined (20 automated measurements at each location) to quantify mural attenuation and wall thickness. Results were compared with endoscopy and histology reports by using logistic regression analysis and receiver operating characteristic curves.

RESULTS

Quantitative measures of terminal ileal mural attenuation and wall thickness correlated significantly with active Crohn disease (P < .001). Small-bowel wall thickness was not a significant factor after attenuation was taken into account. A threshold attenuation value with a sensitivity of 90% (18 of 20) for definite Crohn disease (compared with a sensitivity of 80% [16 of 20] for radiologist assessment) was selected. In patients who underwent ileal biopsy, threshold attenuation had a sensitivity identical to that of ileoscopy (81% [26 of 32]; 95% confidence interval: 64%, 93%) in predicting histologic inflammation.

CONCLUSION

Quantitative measures of mural attenuation and wall thickness at CT enterography correlate highly with ileoscopic and histologic findings of inflammatory Crohn disease. Quantitative measures of mural attenuation are sensitive markers of small bowel inflammation.

Increased antigen presenting cell-mediated T cell activation in mice and patients without the autoimmune regulator

Patients with autoimmune polyendocrine syndrome type I (APS I)suffer from endocrine and non-endocrine disorders due to mutations in the autoimmune regulator gene (AIRE). Mouse Aire is expressed both in thymic medullary epithelial cells and in peripheral antigen-presenting cells, suggesting a role in both central and peripheral tolerance. We here report that Aire(-/-) dendritic cells (DC) activate naive T cells more efficiently than do Aire(+/+) DC. Expression array analyses of Aire(-/-) DC revealed differential regulation of 68 transcripts, among which, the vascular cell adhesion molecule-1 (VCAM-1) transcript was up-regulated in Aire(-/-) DC. Concurrently, the expression of the VCAM-1 protein was up-regulated on both Aire(-/-) DC and monocytes from APS I patients. Blocking the interaction of VCAM-1 prevented enhanced Aire(-/-) DC stimulation of T cell hybridomas. We determined an increased number of DC in spleen and lymph nodes and of monocytes in the blood from Aire(-/-) mice, and an increased number of blood monocytes in APS I patients. Our findings imply a role for Aire in peripheral DC regulation of T cell activation, and suggest that Aire participates in peripheral tolerance.

The role of alpha-4 integrin in the aetiology of multiple sclerosis: current knowledge and therapeutic implications

Multiple sclerosis (MS) has been recognised as a disease since the mid-19th century. The delineation of its CNS pathology, revealing the presence of inflammatory demyelination and relative sparing of axons, was originally interpreted as evidence of infection. Despite many studies, a primary infectious aetiology of MS has not been found. However, the occurrence of acute demyelinating disease following a variety of infections and vaccinations, leading to MS in about a third of cases, provides evidence for the existence of an auto-allergic pathogenesis for the disease. Improved understanding of the role of the blood-brain barrier in protecting the CNS, and the mechanisms by which cells gain entry into the brain and spinal cord has advanced the understanding of MS. Evidence of the central role of the adhesion molecule alpha4beta1-integrin (very late activation antigen-4 [VLA-4]) for lymphocytes in endothelial transmigration into the CNS specifically, has provided a major insight into the pathogenesis of human demyelinating disease and its experimental model, experimental autoimmune encephalomyelitis (EAE). This finding has led to a new window of therapeutic opportunity in MS. Monoclonal antibodies to VLA-4 abrogate the development of EAE in sensitised animals and may actually reverse its clinical and pathological findings in manifest disease. Natalizumab, one such monoclonal antibody, which is administered intravenously, has been found to be a promising agent in the treatment of MS. Although single doses produced no improvement in the speed or quality of recovery from acute exacerbations of MS in a phase II trial, long-term administration (in phase II and phase III trials) have produced significant benefits with results showing both a marked reduction in the risk of new magnetic resonance imaging lesions and a significant reduction in the risk of exacerbations within 2 months of the initiation of therapy. Phase III double-blinded controlled trials have provided additional evidence of safety and a favourable impact on exacerbation rates over the 1 year of administration. Unfortunately, the success of natalizumab has been curtailed by three cases of progressive multifocal leukoencephalopathy, which have prompted the manufacturer to voluntary withdraw the drug from the market. An independent review board is currently investigating the safety of the drug to determine whether it should return to the market. The demonstration that selective modulation (blocking) of the adhesion molecule VLA-4 by natalizumab in MS, resembling that observed in experimental disease, represents a major advance in rational therapy.

Projecting future drug expenditures—2006

PURPOSE

Drug expenditure trends in 2004 and 2005, projected drug expenditures for 2006, and factors likely to influence drug costs are discussed.

SUMMARY

Various factors are likely to affect drug costs, including drug prices, drugs in development, and generic drugs. In 2004 there was a continued moderation of the increase in drug expenditures. Drug expenditures increased by 8.7% from 2003 to 2004. Through the first nine months of 2005, expenditures increased by only 8.1% compared with 2004. This moderation can be attributed to several factors, including the continued trend toward higher prescription drug cost sharing for insured consumers, growing availability of generic drugs, and lack of "blockbuster" new drugs in recent years. Drug expenditures in 2006 will likely be influenced by similar factors, with few costly new products reaching the market, increased concern over product safety slowing the diffusion of those new agents that do reach the market, and several important patent expirations, leading to slower growth in expenditures.

CONCLUSION

Forecasting and managing rising drug expenditures remains a challenge. Pharmacy managers must remain vigilant in monitoring drug costs in their health system and take a proactive role in pursuing efficient drug utilization. The dynamic health policy environment further complicates drug budgeting and must be considered, especially in integrated health systems responsible for managing inpatient, outpatient, and clinic drug costs. The comparison of health-system-specific data and trends with the national information presented in this article may provide a useful context when presenting institutional drug costs to senior management.

Immune cell migration in inflammation: present and future therapeutic targets

The burgeoning field of leukocyte trafficking has created new and exciting opportunities in the clinic. Trafficking signals are being defined that finely control the movement of distinct subsets of immune cells into and out of specific tissues. Because the accumulation of leukocytes in tissues contributes to a wide variety of diseases, these 'molecular codes' have provided new targets for inhibiting tissue-specific inflammation, which have been confirmed in the clinic. However, immune cell migration is also critically important for the delivery of protective immune responses to tissues. Thus, the challenge for the future will be to identify the trafficking molecules that will most specifically inhibit the key subsets of cells that drive disease processes without affecting the migration and function of leukocytes required for protective immunity.

Emerging biological treatments in inflammatory bowel diseases

Although the advent of infliximab has changed the treatment paradigm and goals in inflammatory bowel disease, it does not provide a cure for it and recent evidence has demonstrated that the immunogenicity of this chimeric anti-tumor necrosis factor antibody is associated with secondary loss of response and intolerance. In ulcerative colitis the efficacy of infliximab was demonstrated in two large clinical trials, but long-term maintenance efficacy data are lacking. Novel biological agents have entered clinical development and pioneering trials have been reported in the last 2 years. For Crohn's disease the fully human IgG1 anti-tumor necrosis factor monoclonal adalimumab, and the humanized anti-alpha4-integrin IgG4 antibody, natalizumab have yielded the most promising results in controlled trials, but also agents inhibiting the crucial interleukin-12/interferon-gamma feedback loop suggest therapeutic potential. For severe ulcerative colitis infliximab has been shown to be an effective rescue treatment and the anti-T-cell CD3 antibody has shown promising open-label results. Crucial in the development of novel biological agents, however, is the benefit:risk ratio. As illustrated by unexpected but devastating brain infections with anti-adhesion molecules, clinicians should be aware that the powerful immunomodulatory capacity of biologicals necessitates a rigorous safety follow-up.

Complications of biological therapy for inflammatory bowel diseases

PURPOSE OF REVIEW

The purpose of this review is to analyze the complications associated with treatment of inflammatory bowel disease with biologic agents.

RECENT FINDINGS

There have been various biologic agents evaluated in patients with inflammatory bowel disease; that is, Crohn's disease and ulcerative colitis. Thus far only infliximab has been approved by the US Food and Drug Administration as induction and maintenance treatment in patients with active Crohn's disease (moderate-to-severe and/or fistulizing) who are refractory to conventional therapy. Recent data from two large multicenter, multicountry, randomized controlled clinical trials have demonstrated that infliximab is efficacious also for the treatment of ulcerative colitis. Other biologics considered potentially efficacious are still undergoing evaluation in various clinical trials.

SUMMARY

The data concerning biologics' associated toxicity in patients with inflammatory bowel disease are the most robust in the case of infliximab. These data are derived from both prospective, randomized clinical trials and from post-marketing experience. In the case of the remaining agents the data concerning safety in inflammatory bowel disease are limited, as these agents were not evaluated in as many trials as infliximab; indeed, some of them included only several patients.

Targeting integrin structure and function in disease

Initially linked to the pathogenesis of inflammatory and hematologic diseases, integrins have become validated drug targets with the approval of five drugs. Moreover, there are several promising drug candidates in preclinical and clinical stages of development for multiple clinical indications. Integrins are attractive drug targets as their antagonism can block several steps in disease progression or maintenance. Integrin inhibitors can block the proliferation, migration, or tissue localization of inflammatory, angiogenic, and tumor cells, as well as signaling and gene expression contributing to disease. There has been a rapid increase in the elucidation of integrin structure, their allosteric mechanisms of bidirectional signaling, and the structure of complexes with drugs. This information brings greater focus to how integrins support various cellular functions and how they have been and may be targeted to develop novel drugs. Here we review conformational switches, including an internal ligand, which allosterically regulate the transition from low- to high-affinity ligand binding. We address some of the successes, disappointments, and challenges in targeting competitive or allosteric sites to develop therapeutics. We also discuss new opportunities, including a structure-based approach to discover novel drugs to treat inflammatory and other diseases. This approach targets structural relatives of the von Willebrand factor A-domain present in integrins and many functionally diverse proteins.

Synthesis, biological evaluation, and pharmacokinetic study of prolyl-1-piperazinylacetic acid and prolyl-4-piperidinylacetic acid derivatives as VLA-4 antagonists

A series of prolyl-1-piperazinylacetic acid and prolyl-4-piperidinylacetic acid derivatives were synthesized and evaluated for their activity as VLA-4 antagonists. Of 22 compounds synthesized, 19 compounds showed potent activity with low nanomolar IC50 values. In addition, the representative compounds 11o and 11p with a hydroxy group in the pyrrolidine ring showed moderate plasma clearance in rats (11o, 30 ml/min/kg and 11p, 21 ml/min/kg) and in dogs (11o, 12 ml/min/kg and 11p, 9 ml/min/kg).

Early or late guided missile in the treatment of Crohn's disease?

Over the last few years, much light has been shed on the pathogenesis of Crohn's disease. Further knowledge in this field has provided a firm basis not only in the understanding of current treatment but also for the development of new therapeutic strategies. Aim of these new agents is primarily to selectively interact with the key processes of intestinal inflammation. At present, only anti-tumour necrosis factor-alpha antibodies namely infliximab, is licensed for clinical practice but it is feasible to foresee that, in the near future, a larger range of these agents will become available. Herein, the most promising biological agents in the treatment of Crohn's disease are outlined, which patients would benefit from these agents and when they should be administered. Attention is focused on the early (top-down) or late (step-up) use of biological agents, which for their very targeted mechanism of action may be compared to guided missiles. As yet, early use of biological agents remains to be supported by convincing evidence, nevertheless it may be advocated as first-line therapy for newly diagnosed severe Crohn's disease patients, both adults and children.

Advances in gastrointestinal pharmacotherapy

The medical management of patients with gastrointestinal diseases is advancing rapidly. At a recent symposium held during Digestive Disease Week in Chicago in May of 2005, specific attention was given to the future prospects for medical management of 3 common gastrointestinal disease areas: antisecretory therapy, chronic hepatitis C, and inflammatory bowel disease. Antisecretory approaches include drug combinations including a proton pump inhibitor, potassium competitive acid blockers, and antigastrin agents. The latter two classes are still experimental, but the former combinations have potential to enhance the highly effective agents currently available. The focus of treatment advances in chronic hepatitis C in the immediate future is the discovery of more effective treatment regimens for nonresponders to prior therapy, who are becoming the largest group of patients seeking treatment of hepatitis C. The combination of peginterferon with ribavirin results in 6%-15% sustained virologic response rates in patients who were prior nonresponders to standard interferon plus ribavirin. Newer strategies to eradicate hepatitis C virus infection using different interferons, such as interferon alfacon-1 or higher doses of peginterferon, or long-term maintenance peginterferon, are undergoing study and show promise based on data from preliminary studies. Several immunomodulators have promise in inflammatory bowel disease, although the risk-benefit ratio and costs of therapy require evaluation. Nevertheless, the success of new biologics such as anti-TNFalpha agents augurs well for effective future therapies.

Aza-bicyclic amino acid carboxamides as α4β1/α4β7 integrin receptor antagonists

A series of N-carboxy, N-alkyl, and N-carboxamido azabicyclo[2.2.2]octane carboxamides were prepared and assayed for inhibition of alpha4beta1-VCAM-1 and alpha4beta7-MAdCAM-1 interactions. Potency and alpha4beta1/alpha4beta7 selectivity were sensitive to the substituent R1-R3 in the structures 6, 7, and 8. Several compounds demonstrated low nanomolar balanced alpha4beta1/alpha4beta7 in vitro activity. Two compounds were selected for in vivo leukocytosis studies and demonstrated increases in circulating lymphocytes up to 250% over control.

Positioning novel biologic, probiotic, and apheresis therapies for Crohn's disease and ulcerative colitis

Traditional medications for inflammatory bowel disease are small molecule drugs, most of which were developed for use in other diseases before being found to be efficacious for the treatment of ulcerative colitis or Crohn's disease. Recently, several exciting alternative approaches to the medical treatment of inflammatory bowel disease have been developed. These include biologic, probiotic, and apheresis therapies that offer certain advantages over traditional drug therapy for inflammatory bowel disease. The purpose of this review is to assess the current state of knowledge about novel biologic, probiotic, and apheresis therapies and to analyze how best to incorporate these therapies into evolving management paradigms of inflammatory bowel disease.

A small molecule alpha 4 beta 1 antagonist prevents development of murine Lyme arthritis without affecting protective immunity

After infection with Borrelia burgdorferi, humans and mice under certain conditions develop arthritis. Initiation of inflammation is dependent on the migration of innate immune cells to the site of infection, controlled by interactions of a variety of adhesion molecules. In this study, we used the newly synthesized compound S18407, which is a prodrug of the active drug S16197, to analyze the functional importance of alpha4beta1-dependent cell adhesion for the development of arthritis and for the antibacterial immune response. S16197 is shown to interfere specifically with the binding of alpha4beta(1 integrin to its ligands VCAM-1 and fibronectin in vitro. Treatment of B. burgdorferi-infected C3H/HeJ mice with the alpha4beta1 antagonist significantly ameliorated the outcome of clinical arthritis and the influx of neutrophilic granulocytes into ankle joints. Furthermore, local mRNA up-regulation of the proinflammatory mediators IL-1, IL-6, and cyclooxygenase-2 was largely abolished. Neither the synthesis of spirochete-specific Igs nor the development of a Th1-dominated immune response was altered by the treatment. Importantly, the drug also did not interfere with Ab-mediated control of spirochete load in the tissues. These findings demonstrate that the pathogenesis, but not the protective immune response, in Lyme arthritis is dependent on the alpha4beta1-mediated influx of inflammatory cells. The onset of inflammation can be successfully targeted by treatment with S18407.

Absence of beta7 integrin results in less graft-versus-host disease because of decreased homing of alloreactive T cells to intestine

The alpha4beta7 integrin plays a central role in the homing of T cells to the gut. We hypothesized that absence of the beta7 subunit would result in a reduction of intestinal graft-versus-host disease (GVHD) and an improvement in overall GVHD morbidity and mortality in recipients of hematopoietic stem cell transplantation (HSCT). Analysis of alloreactive beta7-/- T cells showed intact activation, proliferation, cytokine production, and cytotoxicity. However, recipients of beta7-/- donor T cells in murine HSCT models experienced less GVHD morbidity and mortality than recipients of wild-type (WT) T cells, associated with a decrease in donor T-cell infiltration of the liver and intestine and with an overall significant decrease in hepatic and intestinal GVHD. In graft-versus-tumor (GVT) experiments, we demonstrated intact or even enhanced GVT activity of beta7-/- donor T cells. In conclusion, beta7-/- donor T cells caused less GVHD morbidity and mortality than WT donor T cells because of selectively decreased T-cell infiltration of the liver and intestines. Our data suggest that strategies to target the beta7 integrin have the clinical potential to alleviate or prevent GVHD while sparing or potentiating GVT activity.

Natalizumab induction and maintenance therapy for Crohn's disease

BACKGROUND

Natalizumab, a humanized monoclonal antibody against alpha4 integrin, inhibits leukocyte adhesion and migration into inflamed tissue.

METHODS

We conducted two controlled trials to evaluate natalizumab as induction and maintenance therapy in patients with active Crohn's disease. In the first trial, 905 patients were randomly assigned to receive 300 mg of natalizumab or placebo at weeks 0, 4, and 8. The primary outcome was response, defined by a decrease in the Crohn's Disease Activity Index (CDAI) score of at least 70 points, at week 10. In the second trial, 339 patients who had a response to natalizumab in the first trial were randomly reassigned to receive 300 mg of natalizumab or placebo every four weeks through week 56. The primary outcome was a sustained response through week 36. A secondary outcome in both trials was disease remission (a CDAI score of less than 150).

RESULTS

In the first trial, the natalizumab and placebo groups had similar rates of response (56 percent and 49 percent, respectively; P=0.05) and remission (37 percent and 30 percent, respectively; P=0.12) at 10 weeks. Continuing natalizumab in the second trial resulted in higher rates of sustained response (61 percent vs. 28 percent, P<0.001) and remission (44 percent vs. 26 percent, P=0.003) through week 36 than did switching to placebo. Serious adverse events occurred in 7 percent of each group in the first trial and in 10 percent of the placebo group and 8 percent of the natalizumab group in the second trial. In an open-label extension study, a patient treated with natalizumab died from progressive multifocal leukoencephalopathy, associated with the JC virus, a human polyomavirus.

CONCLUSIONS

Induction therapy with natalizumab for Crohn's disease resulted in small, nonsignificant improvements in response and remission rates. Patients who had a response had significantly increased rates of sustained response and remission if natalizumab was continued every four weeks. The benefit of natalizumab will need to be weighed against the risk of serious adverse events, including progressive multifocal leukoencephalopathy. (ClinicalTrials.gov numbers, NCT00032786 and NCT00032799.)

A novel cannabinoid peripheral cannabinoid receptor-selective inverse agonist blocks leukocyte recruitment in vivo

The expression of the cannabinoid peripheral cannabinoid receptor (CB(2)) receptor on peripheral immune cells suggests that compounds specific for CB(2) might be effective anti-inflammatory agents. In this report, we present the initial biological profiling of a novel triaryl bis-sulfone, Sch.336 (N-[1(S)-[4-[[4-methoxy-2-[(4-methoxyphenyl)sulfonyl]phenyl]-sulfonyl]phenyl]ethyl]methanesulfonamide), which is selective for the human cannabinoid CB(2) receptor (hCB(2)). Sch.336 is an inverse agonist at hCB(2), as shown by its ability to decrease guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) binding to membranes containing hCB(2), by the ability of GTPgammaS to left-shift Sch.336 binding to hCB(2) in these membranes, and by the compound's ability to increase forskolin-stimulated cAMP levels in CHO cells expressing hCB(2). In these systems, Sch.336 displays a greater potency than that reported for the CB(2)-selective dihydropyrazole, SR144528 (N-[(1S)-endo-1,3,3-trimethylbicyclo [2.2.1]heptan2-yl]-5-(4-chloro-3-methylphenyl)-1-[(4-methylphenyl)methyl]-1H-pyrazole-3-carboxamide). In vitro, Sch.336 impairs the migration of CB(2)-expressing recombinant cell lines to the cannabinoid agonist 2-arachidonylglycerol. In vivo, the compound impairs migration of cells to cannabinoid agonist HU210 [(6aR)-trans-3-(1,1-dimethylheptyl)-6a,7,10,10a-tetrahydro-1-hydroxy-6,6-dimethyl-6H-dibenzo [b,d] pyran-9-methanol]. Oral administration of the Sch.336 significantly inhibited leukocyte trafficking in several rodent in vivo models, induced either by specific chemokines or by antigen challenge. Finally, oral administration of Sch.336 blocked ovalbumin-induced lung eosinophilia in mice, a disease model for allergic asthma. We conclude that selective cannabinoid CB(2) inverse agonists may serve as novel immunomodulatory agents in the treatment of a broad range of acute and chronic inflammatory disorders in which leukocyte recruitment is a hallmark of disease pathology.

Medical treatment of inflammatory bowel diseases

PURPOSE OF REVIEW

Despite the advent of the anti-TNF agent, infliximab, an important unmet medical need characterizes the medical treatment of inflammatory bowel diseases. This review aims to summarize recent progress in the field.

RECENT FINDINGS

For Crohn's disease, the fully human IgG1 anti-TNF monoclonal antibody, adalimumab and the humanized anti-alpha4 integrin IgG4 antibody, natalizumab have yielded the most promising results in controlled trials, but agents inhibiting the crucial IL12/interferon-gamma feedback loop also suggest therapeutic potential. Maintenance treatment with azathioprine, although efficacious, is not tolerated by up to 25% of individuals, but 6-thioguanine, an active metabolite, is associated with liver toxicity and is no longer recommended. For severe ulcerative colitis, low intravenous cyclosporine doses have been demonstrated to be efficacious, and may serve to limit the toxicity with this agent. Biologic treatment is being developed to target severe ulcerative colitis. Efficacy of infliximab to stop fistula draining as a maintenance agent for fistulizing Crohn's disease has been demonstrated in a large controlled trial, but MRI imaging indicates that the improvement of inflammation in fistula tracks is delayed.

SUMMARY

In conclusion, medical therapy of inflammatory bowel diseases is a constantly moving field and recent evolutions will undoubtedly change clinical practice in the years to come.

Lymphocyte homing to the gut: attraction, adhesion, and commitment

Lymphocytes continuously migrate from the blood into the intestine. Naive lymphocytes leave the blood through high endothelial venules in Peyer's patches. During the multistep extravasation cascade, they sequentially roll on, firmly adhere to, and transmigrate through the endothelial layer using multiple adhesion molecules and chemotactic signals. In the organized lymphoid tissues of the gut, lymphocytes can become activated, if they meet their cognate antigens transported to Peyer's patches through the gut epithelium. During activation and proliferation, the lymphocytes become imprinted by the local dendritic cells, so that after returning to systemic circulation via the efferent lymphatic vasculature, they preferentially home to lamina propria of the gut to execute their effector functions. In inflammation, the recirculation routes of lymphocytes are altered, and these may explain the pathogenesis of certain extra-intestinal manifestations of gut infections and inflammatory bowel diseases. The increased knowledge on the mechanisms that regulate lymphocyte homing and imprinting has clear applicability in designing more effective vaccination regimens. A detailed understanding of the mucosal homing has recently led to the development of the first successful anti-adhesive therapeutics in human.

Natalizumab for the treatment of multiple sclerosis and Crohn's disease

OBJECTIVE

To review the pharmacology, pharmacokinetics, safety, and pivotal clinical trials for natalizumab in the treatment of multiple sclerosis (MS) and inflammatory bowel disease.

DATA SOURCES

A PubMed/MEDLINE search was conducted (1966-June 2005), and information was obtained from Iowa Drug Information Services. Additional data sources included meeting abstracts, bibliographies from identified articles, and information from the manufacturer.

STUDY SELECTION AND DATA EXTRACTION

Studies and review articles examining natalizumab were evaluated. All published, randomized clinical trials evaluating natalizumab in MS and IBD were included in this review.

DATA SYNTHESIS

Natalizumab is the first drug in a new class of agents called selective adhesion molecule inhibitors. It has shown promising results in MS and inflammatory bowel disease and appears superior compared with current therapies in reducing relapse rates. However, 3 recent, confirmed case reports of progressive multifocal leukoencephalopathy (PML) create concern about natalizumab's use in combination with existing therapies or in undefined patient subgroups. Natalizumab was voluntarily withdrawn from the market in March 2005 while the drug's safety is further evaluated.

CONCLUSIONS

Although long-term efficacy and safety of natalizumab have not been established, available data indicate that it is a novel drug for patients with MS or inflammatory bowel disease. Analysis of its possible association with PML will determine the risk-benefit evaluation and eventual place in therapy for natalizumab.

Down-regulation of endothelial adhesion molecules and leukocyte adhesion by treatment with superoxide dismutase is beneficial in chronic immune experimental colitis

Modulation of adhesion molecule expression that govern trafficking of leukocytes into the inflamed intestine is envisioned as a new strategy for treatment of inflammatory bowel disease (IBD). This study was designed to determine the impact of reducing oxidative stress on adhesion molecules expression and leukocyte recruitment in experimental chronic colitis. For that purpose, colitic interleukin-10 knockout and wild-type mice were studied. Groups of animals were treated with Cu/Zn superoxide dismutase (SOD1) 13 mg/kg/d or vehicle for either 7 or 14 days. Expression of vascular cell adhesion molecule-1 and mucosal addressin cell adhesion molecule-1 were determined; leukocyte-endothelial cell interactions in colonic venules were studied with intravital microscopy; and changes in colon pathology and biomarkers of colitis severity were determined. Development of colitis was associated with a marked increase in endothelial vascular cell adhesion molecule-1 and mucosal addressin cell adhesion molecule-1 expression, which were significantly reduced by treatment with SOD1. The increase in leukocyte rolling and adhesion in colonic venules of colitic mice were significantly reduced by administration of SOD1. This treatment markedly reduced colonic lipid hydroperoxidation, myeoloperoxidase activity, and plasma levels of serum amyloid A protein and resulted in significant, although modest, reductions in histologic damage score. The therapeutic value of SOD1 when administered prophylactically was assessed in the dextran sulfate sodium model of colitis with similar positive results. These results indicate that SOD1 affords significant amelioration of colonic inflammatory changes in experimental colitis. Down-regulation of adhesion molecule expression, reduction of lipid hydroperoxidation, and recruitment of leukocytes into the inflamed intestine contribute to this beneficial effect.