Mucosal gene signatures to predict response to infliximab in patients with ulcerative colitis

Gene expression in intestinal mucosal biopsy specimens obtained from dogs with chronic enteropathy

OBJECTIVE

To characterize mucosal gene expression in dogs with chronic enteropathy (CE).

ANIMALS

18 dogs with CE and 6 healthy control dogs.

PROCEDURES

Small intestinal mucosal biopsy specimens were endoscopically obtained from dogs. Disease severity in dogs with CE was determined via inflammatory bowel index scores and histologic grading of biopsy specimens. Total RNA was extracted from biopsy specimens and microchip array analysis (approx 43,000 probe sets) and quantitative reverse transcriptase PCR assays were performed.

RESULTS

1,875 genes were differentially expressed between dogs with CE and healthy control dogs; 1,582 (85%) genes were downregulated in dogs with CE, including neurotensin, fatty acid-binding protein 6, fatty acid synthase, aldehyde dehydrogenase 1 family member B1, metallothionein, and claudin 8, whereas few genes were upregulated in dogs with CE, including genes encoding products involved in extracellular matrix degradation (matrix metallopeptidases 1, 3, and 13), inflammation (tumor necrosis factor, interleukin-8, peroxisome proliferator-activated receptor γ, and S100 calcium-binding protein G), iron transport (solute carrier family 40 member 1), and immunity (CD96 and carcinoembryonic antigen-related cell adhesion molecule [CEACAM] 18). Dogs with CE and protein-losing enteropathy had the greatest number of differentially expressed genes. Results of quantitative reverse transcriptase PCR assay for select genes were similar to those for microchip array analysis.

CONCLUSIONS AND CLINICAL RELEVANCE

Expression of genes encoding products regulating mucosal inflammation was altered in dogs with CE and varied with disease severity. Impact for Human Medicine-Molecular pathogenesis of CE in dogs may be similar to that in humans with inflammatory bowel disease.

Use of the tumor necrosis factor-blockers for Crohn's disease

The use of anti-tumor necrosis factor-α therapy for inflammatory bowel disease represents the most important advance in the care of these patients since the publication of the National Co-operative Crohn's disease study thirty years ago. The recommendations of numerous consensus groups worldwide are now supported by a wealth of clinical trials and several meta-analyses. In general, it is suggested that tumor necrosis factor-α blockers (TNFBs) are indicated (1) for persons with moderately-severe Crohn's disease or ulcerative colitis (UC) who have failed two or more causes of glucocorticosteroids and an acceptably long cause (8 wk to 12 wk) of an immune modulator such as azathioprine or methotrexate; (2) non-responsive perianal disease; and (3) severe UC not responding to a 3-d to 5-d course of steroids. Once TNFBs have been introduced and the patient is responsive, therapy given by the IV and SC rate must be continued. It remains open to definitive evidence if concomitant immune modulators are required with TNFB maintenance therapy, and when or if TNFB may be weaned and discontinued. The supportive evidence from a single study on the role of early versus later introduction of TNFB in the course of a patient's illness needs to be confirmed. The risk/benefit profile of TNFB appears to be acceptable as long as the patient is immunized and tested for tuberculosis and viral hepatitis before the initiation of TNFB, and as long as the long-term adverse effects on the development of lymphoma and other tumors do not prone to be problematic. Because the rates of benefits to TNFB are modest from a population perspective and the cost of therapy is very high, the ultimate application of use of TNFBs will likely be established by cost/benefit studies.

How to guide therapeutic decisions in a patient-tailored approach to treatment of IBD?

Therapeutic decisions in the treatment of IBD involve the initial choice of therapy(ies) and designing a long-term strategy for the individual patient. Putting forward clear therapeutic aims is therefore critical in order to assess treatment success and to guide the sequential use of therapies. Although the ultimate goal of therapy is to achieve steroid-free remission and avoid complications and surgeries, the first therapeutic intervention will achieve these aims only in a minority of patients. Depending on the requirements and successes of each stage of therapy, interim goals are pursued which may be small steps towards the total control of the disease. A patient-tailored approach does not necessarily conflict with algorithm-based decision-making; indeed, they are complementary. The former allows the skipping of some steps in the algorithm, based on the individual patient characteristics. The latter supplies a basis for the rational sequential use of drugs. Many physicians use an accelerated step-up approach in the treatment of IBD, although it has not yet been established whether this is associated with a better outcome. Whether or not an endoscopic or (and) CT or MRI assessment is conducted, the therapeutic approach should be based on mucosal activity and the location and extent of the disease. Treatments that do not heal (or at least improve) ulcers are not to be continued if they have been given a reasonable time to work. Biomarkers like C-reactive protein and calprotectin can be useful surrogates in this setting.

Impaired butyrate oxidation in ulcerative colitis is due to decreased butyrate uptake and a defect in the oxidation pathway

BACKGROUND

In ulcerative colitis (UC) butyrate metabolism is impaired due to a defect in the butyrate oxidation pathway and/or transport. In the present study we correlated butyrate uptake and oxidation to the gene expression of the butyrate transporter SLC16A1 and the enzymes involved in butyrate oxidation (ACSM3, ACADS, ECHS1, HSD17B10, and ACAT2) in UC and controls.

METHODS

Colonic mucosal biopsies were collected during endoscopy of 88 UC patients and 20 controls with normal colonoscopy. Butyrate uptake and oxidation was measured by incubating biopsies with (14) C-labeled Na-butyrate. To assess gene expression, total RNA from biopsies was used for quantitative reverse-transcription polymerase chain reaction (qRT-PCR). In 20 UC patients, gene expression was reassessed after treatment with infliximab.

RESULTS

Butyrate uptake and oxidation were significantly decreased in UC versus controls (P < 0.001 for both). Butyrate oxidation remained significantly reduced in UC after correction for butyrate uptake (P < 0.001), suggesting that the butyrate oxidation pathway itself is also affected. Also, the mucosal gene expression of SLC16A1, ACSM3, ACADS, ECHS1, HSD17B10, and ACAT2 was significantly decreased in UC as compared with controls (P < 0.001 for all). In a subgroup of patients (n = 20), the gene expression was reassessed after infliximab therapy. In responders to therapy, a significant increase in gene expression was observed. Nevertheless, only ACSM3 mRNA levels returned to control values after therapy in the responders groups.

CONCLUSIONS

The deficiency in the colonic butyrate metabolism in UC is initiated at the gene expression level and is the result of a decreased expression of SLC16A1 and enzymes in the β-oxidation pathway of butyrate.

Genetics in diagnosing and managing inflammatory bowel disease

We believe the future clinical application of genomic information in IBD will lie in the use of a combination of “gene-chips” designed specifically for variation relevant to IBD and ultimately in the cataloging of an individual’s entire collection of genomic variation through whole-genome sequencing. In the short term, the expansion of pharmacogenomic tests and biomarker assessments are likely to have the most significant influence on prescribed IBD treatment therapies and disease management. Moreover, these pharmacogenomic and biomarker data are likely to benefit greatly from the ongoing genomic analyses, as they can begin to put these data in the proper genetic context as they relate to monitoring and assessing these effects across different ethnic and racial populations. Although mentioned only briefly in this review, a clearer understanding of environmental triggers of IBD will be of utmost importance to furthering our understanding of the genetic factors and the complex interactions that are likely to exist between genes and environment. The successful identification of genetic factors influencing IBD risk has been accelerating over the last few years and is likely to continue. Currently, these genetic factors provide no direct bearing on clinical treatments or therapies. Instead, these findings aid in our understanding of disease pathogenesis and indirectly to potential for development of novel therapeutics. In the near term, they may be able to provide some additional utility in distinguishing CD cases from UC cases. Future use of genomic information and its role in diagnosing and managing IBD patients is promising but not yet mature. The search for the so-called missing heritability in IBD will undoubtedly continue to uncover novel genes, biological pathways, and the likely interplay between genetic variation and environmental factors. The creation of a customized gene-chip (allowing for the creation of a patient-specific cataloging of IBD relevant genetic information), for use in clinical practice, is an almost certainty. Although this information will likely provide significant aid to diagnostics and treatment, it is doubtful that it could ever fully stand alone. It must be accompanied by thorough clinical evaluation and data, a more complete characterization of a patient’s potential environmental triggers, and integration with other known pharmacogenomic and molecular biomarker information.

Mucosal cytokine gene expression profiles as biomarkers of response to infliximab in ulcerative colitis

OBJECTIVE

Mucosal cytokine profile determines T cell differentiation and may play an important role in the clinical course of inflammatory bowel disease (IBD). Cytokines from different T helper (Th) cell subsets are elevated in inflamed mucosa of patients with ulcerative colitis (UC), contributing to the inflammation. The aim of this study was to determine the predictive value of pre-treatment mucosal cytokine profile in response to therapy with the anti-TNF agent infliximab (IFX).

MATERIAL AND METHODS

The expression of Th1, Th17, Th2 and T-regulatory (Treg)-related cytokines was quantified by real-time PCR in mucosal biopsies from 74 UC patients before initiation of IFX induction therapy. Clinical and endoscopic effects were assessed after three infusions. Remission was defined as ulcerative colitis disease activity index (UCDAI) below 3.

RESULTS

Higher gene expression levels of IL-17A and IFN-γ were significantly associated with remission after three IFX infusions (OR = 5.4, p = 0.013 and OR = 5.5, p = 0.011, respectively). IL-17A and IFN-γ mRNA expression showed positive correlation. Th2 and Treg-related mediators were not significantly associated with clinical outcome, but were expressed at higher levels in UC patients compared with the controls. Immunohistochemistry (IHC) confirmed the presence of cells expressing both IL-17A and IFN-γ.

CONCLUSIONS

High expression of Th1- and Th17-related cytokines in the mucosa of UC patients can potentially predict a favorable outcome of IFX induction therapy. Th2 and Treg-related mediators do not appear useful as predictive markers.

Results of the 2nd scientific workshop of the ECCO (III): basic mechanisms of intestinal healing

The second scientific workshop of the European Crohn's and Colitis Organization (ECCO) focused on the relevance of intestinal healing for the disease course of inflammatory bowel disease (IBD). The objective was to better understand basic mechanisms, markers for disease prediction, detection and monitoring of intestinal healing, impact of intestinal healing on the disease course of IBD as well as therapeutic strategies. The results of this workshop are presented in four separate manuscripts. This section describes basic mechanisms of intestinal healing, identifies open questions in the field and provides a framework for future studies.

Biomarkers in inflammatory bowel disease: current practices and recent advances

Crohn's disease and ulcerative colitis represent the two main forms of the idiopathic chronic inflammatory bowel diseases (IBD). Currently available blood and stool based biomarkers provide reproducible, quantitative tools that can complement clinical assessment to aid clinicians in IBD diagnosis and management. C-reactive protein and fecal based leukocyte markers can help the clinician distinguish IBD from noninflammatory diarrhea and assess disease activity. The ability to differentiate between forms of IBD and predict risk for disease complications is specific to serologic tests including antibodies against Saccharomyces cerevisiae and perinuclear antineutrophil cytoplasmic proteins. Advances in genomic, proteomic, and metabolomic array based technologies are facilitating the development of new biomarkers for IBD. The discovery of novel biomarkers, which can correlate with mucosal healing or predict long-term disease course has the potential to significantly improve patient care. This article reviews the uses and limitations of currently available biomarkers and highlights recent advances in IBD biomarker discovery.

Cytokine blockade in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are chronic disabling diseases with significant morbidity. A deregulated immune response towards the intestinal microbiota is thought to play an important role in the pathogenesis of IBD, and thus biological therapies targeting key molecules such as cytokines have been designed. Several anti-TNF-α agents are currently being used to treat Crohn's disease and ulcerative colitis. Although these molecules dramatically improved the treatment of patients, side effects and the development of antidrug antibodies limits their application. There is thus an urgent need for alternative approaches to decrease inflammation and limit immunogenicity. Small neutralizing molecules, active immunization, gene silencing, selective transcription inhibitors and delivery of agents through the oral route are some of the currently developed strategies to meet these needs. In parallel, neutralizing antibodies targeting other pathways of the immune system have been developed and tested. Antibodies targeting IL-12/IL-23 pathways, and proinflammatory cytokines such as IFN-γ, IL-17A, IL-2 and IL-6 often showed an initial promising result, but for none of these agents efficacy has unequivocally been established. Administration of the regulatory cytokines IL-10 and IL-11 also failed to induce reproducible clinical effects. This article focuses on the anti-TNF therapies and the current challenges with monoclonal antibody therapies, discusses the innovative strategies targeting cytokine pathways to decrease inflammation in the bowel, and summarizes the recently developed agents neutralizing proinflammatory cytokines.

The triad of success in personalised medicine: pharmacogenomics, biotechnology and regulatory issues from a Central European perspective

The population of the world has recently passed the 7 billion milestone and as the cost of human genome sequencing is rapidly declining, sequence data of billions of people should be accessible much sooner than anyone would have predicted 10 years ago. This will form the basis of personalised medicine. However it is still not clear, even in principle, whether these data, combined with data of the expression of one's genome in various cells and tissues relevant to different diseases, could be used effectively in clinical medicine and healthcare, or in predicting responses to different therapies. Therefore this is an important issue which needs to be addressed before more resources are wasted on less than informative studies and surveys simply because technologies exist. As a typical example, we have selected and summarise here key studies from the biomedical literature that focus on gene expression profiling of the response to biologic therapies in peripheral blood and biopsy samples in autoimmune diseases such as rheumatoid arthritis, spondylarthropathy, inflammatory bowel diseases and psoriasis. We also present the state of the biotechnology market from a European perspective, discuss how spin-offs leverage the power of genomic technologies and describe how they might contribute to personalised medicine. As ethical, legal and social issues are essential in the area of genomics, we analysed these aspects and present here the European situation with a special focus on Hungary. We propose that the synergy of these three issues: pharmacogenomics, biotechnology and regulatory issues should be considered a triad necessary to succeed in personalised medicine.

Genetic and genomic predictors of anti-TNF response

The introduction of anti-TNF therapy has dramatically improved the outlook for patients suffering from a number of inflammatory conditions including rheumatoid arthritis and inflammatory bowel disease. Despite this, a substantial proportion of patients (approximately 30-40%) fail to respond to these potentially toxic and expensive therapies. Treatment response is likely to be multifactorial; however, variation in genes or their expression may identify those most likely to respond. By targeted testing of variants within candidate genes, potential predictors of anti-TNF response have been reported; however, very few markers have replicated consistently between studies. Emerging genome-wide association studies suggest that there may be a number of genes with modest effects on treatment response rather than a few genes of large effect. Other potential serum biomarkers of response have also been explored including cytokines and autoantibodies, with antibodies developing to the anti-TNF drugs themselves being correlated with treatment failure.

Certolizumab pegol compared to natalizumab in patients with moderate to severe Crohn's disease: results of a decision analysis

INTRODUCTION

A significant proportion of patients with Crohn's disease (CD) lose response to antibodies directed against tumor necrosis factor α (TNF). Prior TNF-antagonist failure is associated with lower rates of response to subsequent TNF-antagonist therapy. In patients failing two anti-TNF agents, a choice exists between using a third-anti-TNF therapy or natalizumab (NAT), an α-4 integrin inhibitor. A cost-effectiveness analysis comparing these competing strategies has not been performed.

METHODS

A decision analytic model was constructed to compare the performance of certolizumab pegol (CZP) versus NAT in patients with moderate to severe CD. Previously published estimates of efficacy of third-line anti-TNF therapy and NAT were used to inform the model. Costs were expressed in 2010 US dollars. A 1-year time frame was used for the analysis.

RESULTS

In the base case estimate, use of NAT was only marginally more effective [0.71 vs. 0.70 quality adjusted life-years (QALYs)] than CZP but was expensive with an incremental cost-effectiveness ratio (ICER) of $381,678 per QALY gained. For CZP 2 months response rate of at least 24%, NAT had an ICER above the willingness-to-pay (WTP) threshold. The model was sensitive to the costs of both therapies; for all CZP costs below $2,300 per dose, NAT had higher ICER than the WTP threshold. Substituting adalimumab for CZP resulted in similar ICER estimates and thresholds for NAT use.

CONCLUSIONS

In patients with moderate to severe CD failing two TNF-antagonists, using a third TNF-antagonist therapy appears to be a cost-effective strategy without significantly compromising treatment efficacy.

The future of inflammatory bowel disease management: combining progress in trial design with advances in targeted therapy

Anti-tumour necrosis factor antagonists have appreciably improved patient outcomes in Crohn's disease, shifting the goals of treatment from control of symptoms to clinical remission (Crohn's disease activity index <150) combined with mucosal healing - the new concept of 'deep remission'. Achieving deep remission brings clinically meaningful benefits, including reduced hospitalization and reduced need for surgery. Aspects such as the dose, timing and intensification of anti-tumour necrosis factor therapy affect the likelihood of achieving deep remission, but definitive evidence on long-term benefits and the risk/benefit profile of treatment intensification is needed. A consequence of the success of anti-tumour necrosis factor therapies has been a change in the disease characteristics of the patient population entering clinical trials. Therefore, new clinical study paradigms, such as cluster randomization and therapeutic strategy trials, are needed. High placebo response rates and the ethics of testing emerging agents against placebo in an era of effective therapies are challenges to traditional randomized controlled trials. Overcoming these challenges will not only help to optimize anti-tumour necrosis factor therapy, but also advance development of emerging treatments for Crohn's disease.

MicroRNAs in inflammatory bowel disease

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate gene and protein expression. miRNAs are critical to a normal immune response and have altered expression in multiple immune-mediated disorders. This emerging role of miRNAs in the pathogenesis of multiple disease states has led to investigations into miRNA expression profiles in inflammatory bowel disease (IBD). The discovery of miRNAs in IBD is likely to contribute to our understanding of IBD pathogenesis and lead to clinical advances in IBD. This review focuses on miRNA expression in inflammation, autoimmune disorders, and inflammation-associated cancer, as well as their function in the biology and management of IBD.

Candidate mucosal and surrogate biomarkers of inflammatory bowel disease in the era of new technology

OBJECTIVE

There is increasing knowledge of the pathophysiology behind inflammatory bowel disease (IBD) although the exact mechanism is far from fully understood. In the era of new technology, over the last years molecular approaches have shed light on the inflammatory mechanisms and their metabolic end products. This opens for a molecular fingerprinting that can be used in the biomarker field of IBD. There is a great need of biomarkers for prediction of clinical outcome and prognostic biomarker for prediction of therapeutic effects in IBD. Although the biomarker concept is old, so far very few really useful biomarkers exist in IBD.

MATERIAL AND METHODS

Here, we review the predictive and prognostic biomarkers in IBD in the era of new technologies with emphasis on the potential of molecular fingerprinting.

RESULTS

Very few candidate biomarkers have been documented. The most promising candidate predictor is tumor necrosis factor-α, but there is a lack of validation.

CONCLUSION

So far, there are few biomarkers documented in IBD, but we are at the start of a new scientific field that will be of great value for the handling of the disease.

Update on the management of ulcerative colitis

The treatment options for inflammatory bowel disease have expanded with the introduction of biological therapies. Recently published controlled clinical trials were searched and those that impact the clinical management of ulcerative colitis (UC) are discussed in this review. In the management of mild to moderate UC, mesalamine still remains the first choice of drug. The newly developed once daily formulations have shown equal efficacy to divided doses and possibly portend better compliance owing to a simplified regimen. In outpatients with moderate to severe UC, recent data indicate that infliximab induced and maintained remission leads to decreased colectomy rates and fewer hospitalizations. An alternative anti-tumor necrosis factor (TNF) agent, adalimumab, was also recently shown to be effective for induction of remission in moderate to severe UC. The use of immunosuppressives, such as azathioprine and mercaptopurine, is associated with decreased colectomy rates and thioguanine was shown to be effective in maintaining clinical remission in those who are intolerant to azathioprine/mercaptopurine. In hospitalized patients with steroid resistant severe UC, infliximab and tacrolimus may be alternatives to cyclosporine in those who are otherwise candidates for colectomy. Adequate long-term maintenance therapy with immunosuppressives or anti-TNF therapy is required after rescue therapy for a sustained benefit. Future research is needed to position the available anti-TNF agents and combined immunosuppressive therapy in the treatment of UC to achieve and maintain steroid free remission.

Results of the 2nd part Scientific Workshop of the ECCO. II: Measures and markers of prediction to achieve, detect, and monitor intestinal healing in inflammatory bowel disease

The healing of the intestine is becoming an important objective in the management of inflammatory bowel diseases. It is associated with improved disease outcome. Therefore the assessment of this healing both in clinical studies and routine practice is a key issue. Endoscopy for the colon and terminal ileum and computerized tomography or magnetic resonance imaging for the small bowel are the most direct ways to evaluate intestinal healing. However, there are many unsolved questions about the definition and the precise assessment of intestinal healing using these endoscopic and imaging techniques. Furthermore, these are relatively invasive and expensive procedures that may be inadequate for regular patients' monitoring. Therefore, biomarkers such as C-reactive protein and fecal calprotectin have been proposed as surrogate markers for intestinal healing. Nevertheless, the sensitivity and specificity of these markers for the prediction of healing may be insufficient for routine practice. New stool, blood or intestinal biomarkers are currently studied and may improve our ability to monitor intestinal healing in the future.

Blood-based biomarkers can differentiate ulcerative colitis from Crohn's disease and noninflammatory diarrhea

BACKGROUND

Blood gene expression profiling has been used in several studies to identify patients with a number of conditions and diseases. A blood test with the ability to differentiate Crohn's disease (CD) from ulcerative colitis (UC) and noninflammatory diarrhea would be useful in the clinical management of these diseases.

METHODS

Affymetrix U133Plus 2.0 GeneChip oligonucleotide arrays were used to generate whole blood gene expression profiles for 21 patients with UC, 24 patients with CD, and 10 control patients with diarrhea, but without colonic pathology.

RESULTS

A supervised learning method (logistic regression) was used to identify specific panels of probe sets which were able to discriminate between UC and CD and from controls. The UC panel consisted of the four genes, CD300A, KPNA4, IL1R2, and ELAVL1; the CD panel comprised the four genes CAP1, BID, NIT2, and NPL. These panels clearly differentiated between CD and UC.

CONCLUSIONS

Gene expression profiles from blood can differentiate patients with CD from those with UC and from noninflammatory diarrheal disorders.

Gene expression profiling and response signatures associated with differential responses to infliximab treatment in ulcerative colitis

OBJECTIVES

Infliximab has been shown to induce clinical response and remission in ulcerative colitis (UC). To characterize the biological response of patients to infliximab, we analyzed the mRNA expression patterns of mucosal colonic biopsies taken from UC patients enrolled in the Active Ulcerative Colitis Trial 1 (ACT1) study.

METHODS

Biopsies were obtained from 48 UC patients before treatment with 5 or 10 mg/kg infliximab, and at 8 and 30 weeks after treatment (n = 113 biopsies). Global gene expression profiling was performed using Affimetrix GeneChip Human Genome U133 Plus 2.0 arrays. Expression profiling results for selected genes were confirmed using qPCR.

RESULTS

Infliximab had a significant effect on mRNA expression in treatment responders, with both infliximab dose and duration of treatment having an effect. Genes affected are primarily involved with inflammatory response, cell-mediated immune responses, and cell-to-cell signaling. Unlike responders, non-responders do not effectively modulate T(H₁), T(H₂), and T(H₁₇) pathways. Gene expression can differentiate placebo and infliximab responders.

CONCLUSIONS

Analysis of mRNA expression in mucosal biopsies following infliximab treatment provided insight into the response to therapy and molecular mechanisms of non-response.

Review article: Causative factors and the clinical management of patients with Crohn's disease who lose response to anti-TNF-α therapy

BACKGROUND

The addition of antitumour necrosis factor-α (TNF-α) agents to the therapeutic armamentarium against Crohn's disease has been a revolution in its management. However, approximately 25 to 40% of patients who initially benefit from anti-TNF-α treatment develop intolerable adverse events or lose their response during maintenance therapy.

AIM

To summarise the current knowledge on the mechanisms underlying loss of response in these patients and the therapeutic strategies available to counteract this clinical challenge.

METHOD

A literature search using PubMed, MedLine and Embase databases has been performed.

RESULTS

Anti-infliximab antibodies formation and autoantibodies (ANA, anti-DNA and other autoantibodies) have been associated with loss of response. Individual differences in drug metabolism may contribute to loss of response. Smoking may be a risk factor for loss of response. Dose escalation, reduction of infusion intervals and switch to other anti-TNF-α agents are effective as rescue strategies.

CONCLUSIONS

Loss of response appears to result from different causes not fully established by now. Optimization of therapies, or switch to other anti-TNF-α, are currently the best studied strategies in case of loss of response, and can be successful in 40-60% of patients who lose response.

Inflammatory bowel disease: beyond the boundaries of the bowel

Dysregulated inflammation in the gut, designated clinically as inflammatory bowel disease (IBD), is manifested by the prototypic phenotypes of an Arthus-like reaction restricted to the mucosa of the colon, as in ulcerative colitis, or a transmural granulomatous reaction, as in Crohn's disease, or an indeterminate form of the two polar types. That the inflammation of IBD can trespass the boundaries of the bowel has long been known, with articular, ophthalmologic, cutaneous, hepatobiliary or other complications/associations - some autoimmune and others not - affecting significant numbers of patients with IBD. Also notable is the frequency of diagnosis of IBD-type diseases on a background of systemic, (mostly myelo-hematological) disorders, associated with alterations of either (or both) innate or adaptive arms of the immune response. Finally, cases of IBD are reported to occur as an adverse effect of TNF inhibitors. Bone marrow transplant has been proven to be the only curative measure for some of the above cases. Thus, in effect, the IBDs should now be regarded as a systemic, rather than bowel-localized, disease. Genome-wide association studies have been informative in consolidating the view of three phenotypes of IBD (ulcerative colitis, Crohn's disease and mixed) and, notably, are revealing that the onset of IBD can be linked to polymorphisms in regulatory miRNAs, or to nucleotide sequences coding for regulatory lymphokines and/or their receptors. At the effector level, we emphasize the major role of the Th17/IL-23 axis in dictating the perpetuation of intestinal inflammation, augmented by a failure of physiological control by regulatory T-cells. In conclusion, there is a central genesis of the defects underlying IBD, which therefore, in our opinion, is best accommodated by the concept of IBD as more of a syndrome than an autonomous disease. This altered mindset should upgrade our knowledge of IBD, influence its medical care and provide a platform for further advances.

Future therapeutic approaches for inflammatory bowel diseases

In this review, we speculate about future therapeutic approaches for inflammatory bowel diseases (IBDs), focusing on the need for better preclinical and clinical models and approaches beyond small molecules and systemically administered biologics. We offer ideas to change clinical trial programs and to use immunologic and genetic biomarkers to personalize medicine. We attempt to reconcile past therapeutic successes and failures to improve future approaches. Some of our ideas might be provocative, but we hope that the examples we provide will stimulate discussion about what will advance the field of IBD therapy.

Assessing response and loss of response to biological therapies in IBD

OBJECTIVES

The advent of biological therapies for inflammatory bowel disease (IBD) began in 1998 with the approval of infliximab for the treatment of refractory (to conventional agents) Crohn's disease (CD). Since then, the indications for anti-tumor necrosis factor-α (anti-TNFα) therapy have increased to include induction and maintenance of clinical responses and remissions for luminal and fistulizing CD, the treatment of children with CD, and the treatment of adults with ulcerative colitis. Additional utilities of biological therapies have included demonstrable mucosal healing, improvement in quality of life, reduction in surgeries and hospitalizations, and the treatment of extraintestinal manifestations of IBD including central and peripheral arthritis and pyoderma gangrenosum. Natalizumab has also been approved for the treatment of refractory Crohn's in patients who have failed conventional agents and anti-TNFα therapies. Unfortunately, despite the overall effectiveness of biological agents in a spectrum of indications for IBD, a significant proportion of patients do not respond or lose response over time. In this review, we intend to appraise the latest evolution in treatment strategies in IBD and to suggest an evidence-based approach and risk stratification while coping with cases of non-responders or loss of response to biological therapies.

METHODS

We conducted a literature search of English publications listed in the electronic databases of MEDLINE (source PUBMED) and constructed an analytical review based on definitions of response and loss of response, considering potential responsible mechanisms, clinical assessment tools, and finally recommending a practical approach for its prevention and management.

RESULTS

Favorable clinical outcome appears to be the consequence of sustained therapeutic drug levels, and the current literature supports a practice of dose adjustments. When immunogenicity develops to a single biological agent, response can be regained by introduction of an alternative biological agent of the same or different class. Efficacy is reduced with second-line agents either within or across classes compared with naive patients. In the absence of direct measurement of drug levels and anti-drug antibodies, clinical judgment is necessary to assess the mechanisms of loss of response, and more empiric decision making may be necessary to determine the choice of second-line biological agents. Optimal treatment strategies are still controversial.

CONCLUSIONS

It is essential to recognize the spectrum of mechanisms affecting response and loss of response to form a logical and efficient management algorithm, and, perhaps, it is time to incorporate the measurement of trough levels and anti-drug antibodies in the strategy of such an assessment. Prospective controlled trials are direly needed to investigate the optimal tailored management in individual patients who lose response.

Mucosal gene expression of cell adhesion molecules, chemokines, and chemokine receptors in patients with inflammatory bowel disease before and after infliximab treatment

OBJECTIVES

Inflammatory bowel disease (IBD) is characterized by a continuous influx of leukocytes into the gut wall. This migration is regulated by cell adhesion molecules (CAMs), and selective antimigration therapies have been developed. This study investigated the effect of infliximab therapy on the mucosal gene expression of CAMs in IBD.

METHODS

Mucosal gene expression of 69 leukocyte/endothelial CAMs and E-cadherin was investigated in 61 IBD patients before and after first infliximab infusion and in 12 normal controls, using Affymetrix gene expression microarrays. Quantitative reverse transcriptase-PCR (qRT-PCR), immunohistochemistry, and western blotting were used to confirm the microarray data.

RESULTS

When compared with control colons, the colonic mucosal gene expression of most leukocyte/endothelial adhesion molecules was upregulated and E-cadherin gene expression was downregulated in active colonic IBD (IBDc) before therapy, with no significant colonic gene expression differences between ulcerative colitis and colonic Crohn's disease. Infliximab therapy restored the upregulations of leukocyte CAMs in IBDc responders to infliximab that paralleled the disappearance of the inflammatory cells from the colonic lamina propria. Also, the colonic gene expression of endothelial CAMs and of most chemokines/chemokine receptors returned to normal after therapy in IBDc responders, and only CCL20 and CXCL1-2 expression remained increased after therapy in IBDc responders vs. control colons. When compared with control ileums, the ileal gene expression of MADCAM1, THY1, PECAM1, CCL28, CXCL1, -2, -5, -6, and -11, and IL8 was increased and CD58 expression was decreased in active ileal Crohn's disease (CDi) before therapy, and none of the genes remained dysregulated after therapy in CDi responders vs. control ileums. This microarray study identified a number of interesting targets for antiadhesion therapy including PECAM1, IL8, and CCL20, besides the currently studied α4β7 integrin-MADCAM1 axis.

CONCLUSIONS

Our data demonstrate that many leukocyte/endothelial CAMs and chemokines/chemokine receptors are upregulated in inflamed IBD mucosa. Controlling the inflammation with infliximab restores most of these dysregulations in IBD. These results show that at least part of the mechanism of anti-tumor necrosis factor-α therapy goes through downregulation of certain adhesion molecules.

To what extent are genetics clinically useful?

The volume of research undertaken on the genetic susceptibility of inflammatory bowel diseases has been tremendous. International collaborative efforts which initiated in 1997 and have not stopped since, led to the identification at present of more than 100 IBD risk loci. Yet, only 25% of the genetic variance is explained. It is hypothesized that rare variants, other forms of genetic variation (copy number variation), as well as gene-gene and geneenvironment interactions, explain the missing heritability. From all genes identified, the pattern recognition receptor NOD2/CARD15 is still the most understood at present. The field of IBD genetics has translated itself so far in identifying pathways important for disease pathogenesis (autophagy, Th17/IL23, pattern recognition receptors and innate immunity, barrier integrity), some of which have promising therapeutic consequences. Second, although genetic testing will most likely have no or a very limited role in diagnosing patients, it is anticipated that genetic markers will be implemented in an integrated prognostic approach. Efforts to predict disease course and response to therapy have shown interesting results.

Gene expression profiles in peripheral blood for the diagnosis of autoimmune diseases

Gene expression profiling in clinical genomics has yet to deliver robust and reliable approaches for developing diagnostics and contributing to personalized medicine. Owing to technological developments and the recent accumulation of expression profiles, it is a timely and relevant question whether peripheral blood gene expression profiling can be used routinely in clinical decision making. Here, we review the available gene expression profiling data of peripheral blood in autoimmune and chronic inflammatory diseases and suggest that peripheral blood mononuclear cells are suitable for descriptive and comparative gene expression analyses. A gene-disease interaction network in chronic inflammatory diseases, a general protocol for future studies and a decision tree for researchers are presented to facilitate standardization and adoption of this approach.

IBD: of mice and men-shedding new light on IL-13 activity in IBD

a recent study in a mouse model of colitis has demonstrated that interleukin (Il)‑13, through inhibition of the mixed type 1 and type 17 T‑helper cell inflammatory response, has a protective effect. the decoyreceptor Il‑13rα2 inhibits this protective effect, suggesting blockade of Il‑13rα2 as a potential therapy for patients with IBD.

Seroreactivity against glycolytic enzymes in inflammatory bowel disease

BACKGROUND

Patients with inflammatory bowel disease (IBD) carry autoantibodies such as perinuclear antineutrophil cytoplasmic antibodies. The aim of the current study was to further characterize the immune reactivity in IBD.

METHODS

We used an immunoproteomic approach with extracts from granulocytes and serum from ulcerative colitis (UC) patients and controls to identify target antigens. By means of Western blot analysis, we screened 60 UC and 60 Crohn's disease (CD) patients, 60 diseased, and 60 healthy controls for the antibodies. We performed gene array experiments on RNA extracted from colonic mucosal biopsies from 42 IBD patients and six controls.

RESULTS

We identified aldolase A, phosphoglycerate mutase, alpha-enolase, triose-phosphate isomerase, and malate dehydrogenase as target antigens in IBD. Seroreactivity to at least one of these five antigens was detected in 53.3% of UC patients, 38.3% of CD patients, and 8.3% of controls. Seroreactivity to at least two antigens was detected in 16.7% of UC patients, 11.7% of CD patients, and none of the controls. Gene array experiments showed a significant upregulation of aldolase A, phosphoglycerate mutase, alpha-enolase, and pyruvate kinase mRNA in biopsies from IBD patients, but not controls. UC and CD patients also showed enhanced expression of hypoxia-inducible factor-1, a transcription factor that induces expression of glycolytic enzymes.

CONCLUSIONS

IBD patients show strong seroreactivity toward enzymes involved in the glycolysis. IBD patients also have increased colonic mRNA expression of glycolytic enzymes, which is triggered by hypoxia through the transcription factor HIF-1.

The London Position Statement of the World Congress of Gastroenterology on Biological Therapy for IBD with the European Crohn's and Colitis Organization: when to start, when to stop, which drug to choose, and how to predict response?

The advent of biological therapy has revolutionized inflammatory bowel disease (IBD) care. Nonetheless, not all patients require biological therapy. Selection of patients depends on clinical characteristics, previous response to other medical therapy, and comorbid conditions. Availability, reimbursement guidelines, and patient preferences guide the choice of first-line biological therapy for luminal Crohn's disease (CD). Infliximab (IFX) has the most extensive clinical trial data, but other biological agents (adalimumab (ADA), certolizumab pegol (CZP), and natalizumab (NAT)) appear to have similar benefits in CD. Steroid-refractory, steroid-dependent, or complex fistulizing CD are indications for starting biological therapy, after surgical drainage of any sepsis. For fistulizing CD, the efficacy of IFX for inducing fistula closure is best documented. Unique risks of NAT account for its labeling as a second-line biological agent in some countries. Patients who respond to induction therapy benefit from systematic re-treatment. The combination of IFX with azathioprine is better than monotherapy for induction of remission and mucosal healing up to 1 year in patients who are naïve to both agents. Whether this applies to other agents remains unknown. IFX is also effective for treatment-refractory, moderate, or severely active ulcerative colitis. Patients who have a diminished or loss of response to anti-tumor necrosis factor (TNF) therapy may respond to dose adjustment of the same agent or switching to another agent. Careful consideration should be given to the reasons for loss of response. There are insufficient data to make recommendations on when to stop anti-TNF therapy. Preliminary evidence suggests that a substantial proportion of patients in clinical remission for >1 year, without signs of active inflammation can remain in remission after stopping treatment.

Inflammatory bowel disease and colitis: new concepts from the bench and the clinic

PURPOSE OF REVIEW

The previous 18 months have shown important progress in unravelling the causes of inflammatory bowel disease (IBD) and in improving its management for the patients.

RECENT FINDINGS

More genome-wide association studies and meta-analyses of these have been published and have identified more than 100 confirmed genes for IBD, and highlighted a number of novel pathways. Two of the genes, NOD2/CARD15 and the autophagy gene ATG16L1 have recently been linked into one functional pathway of bacterial sensing, invasion and elimination. From the clinical side, the previous year has been dominated mainly by the results of the SONIC study, comparing efficacy and safety of azathioprine, infliximab and the combination of azathioprine and infliximab, in patients with active Crohn's disease, naive to these drugs. International consensus guidelines on infection prevention were released last year by the European Crohn's and Colitis Organisation.

SUMMARY

The recent findings in IBD include the increasing number of IBD susceptibility genes, the demonstration that NOD2 and ATG16L1 are linked in one functional pathway and the role of IL-33/ST2 in colitis. From the bedside, the novelties have been the results of SONIC and selecting the right patient for intensified treatment with immunomodulators and anti-tumor necrosis factor, and appropriate counselling regarding risk of infections and vaccinations.

IL-22+ CD4+ T cells are associated with therapeutic trichuris trichiura infection in an ulcerative colitis patient

Ulcerative colitis, a type of inflammatory bowel disease, is less common in countries endemic for helminth infections, suggesting that helminth colonization may have the potential to regulate intestinal inflammation in inflammatory bowel diseases. Indeed, therapeutic effects of experimental helminth infection have been reported in both animal models and clinical trials. Here, we provide a comprehensive cellular and molecular portrait of dynamic changes in the intestinal mucosa of an individual who infected himself with Trichuris trichiura to treat his symptoms of ulcerative colitis. Tissue with active colitis had a prominent population of mucosal T helper (T(H)) cells that produced the inflammatory cytokine interleukin-17 (IL-17) but not IL-22, a cytokine involved in mucosal healing. After helminth exposure, the disease went into remission, and IL-22-producing T(H) cells accumulated in the mucosa. Genes involved in carbohydrate and lipid metabolism were up-regulated in helminth-colonized tissue, whereas tissues with active colitis showed up-regulation of proinflammatory genes such as IL-17, IL-13RA2, and CHI3L1. Therefore, T. trichiura colonization of the intestine may reduce symptomatic colitis by promoting goblet cell hyperplasia and mucus production through T(H)2 cytokines and IL-22. Improved understanding of the physiological effects of helminth infection may lead to new therapies for inflammatory bowel diseases.

A multicenter experience with infliximab for ulcerative colitis: outcomes and predictors of response, optimization, colectomy, and hospitalization

OBJECTIVES

The objective of this study was to evaluate short- and long-term outcomes of infliximab in ulcerative colitis (UC), including infliximab optimization, colectomy, and hospitalization.

METHODS

This was a retrospective multicenter study. All adult patients who received at least one infliximab infusion for UC were included. Cumulative probabilities of event-free survival were estimated by the Kaplan-Meier method. Independent predictors were identified using binary logistic regression or Cox proportional-hazards regression, and results were expressed as odds ratios or hazard ratios (HRs), respectively.

RESULTS

Between January 2000 and August 2009, 191 UC patients received infliximab therapy. Median follow-up per patient was 18 months (interquartile range=25-75th, 8-32 months). Primary non-response was noted in 42 patients (22.0%). "Hemoglobin at infliximab initiation ≤ 9.4 g/dl" (odds ratio=4.35; 95% confidence interval (CI)=1.81-10.42) was a positive predictor of non-response to infliximab. Infliximab optimization was required in 36 (45.0%) of 80 patients on scheduled infliximab therapy. The only predictor of infliximab optimization was "infliximab indication for acute severe colitis" (HR=2.75; 95% CI=1.23-6.12). Thirty-six patients (18.8%) underwent colectomy. Predictors of colectomy were: "no clinical response after infliximab induction" (HR=7.06; 95% CI=3.36-14.83), "C-reactive protein at infliximab initiation > 10 mg/l" (HR=5.11; 95% CI=1.77-14.76), "infliximab indication for acute severe colitis" (HR=3.40; 95% CI=1.48-7.81), and "previous treatment with cyclosporine" (HR=2.53; 95% CI=1.22-5.28). Sixty-nine patients (36.1%) were hospitalized at least one time and UC-related hospitalizations rate was 29 per 100 patient-years (95% CI=24-35 per 100 patient-years). Predictors of first hospitalization were: "no clinical response after infliximab induction" (HR=3.87; 95% CI=2.29-6.53), "infliximab indication for acute severe colitis" (HR=3.13, 95% CI=1.65-5.94), "disease duration at infliximab initiation ≤50 months" (HR=2.14, 95% CI=1.25-3.66), "hemoglobin at infliximab initiation ≤11.8 g/dl" (HR=1.77; 95% CI=1.03-3.04), and "previous treatment with methotrexate" (HR=0.30; 95% CI=0.09-0.97).

CONCLUSIONS

Primary non-response to infliximab was noted in one fifth of patients and increased by seven and four the risks of colectomy and hospitalization, respectively. Infliximab optimization, colectomy, and hospitalization were required in half, one fifth, and one third of patients, respectively. Infliximab indication for acute severe colitis increased by three the risks of infliximab optimization, colectomy, and UC-related hospitalization.

Predictive value of epithelial gene expression profiles for response to infliximab in Crohn's disease

BACKGROUND

Infliximab (IFX) has become the mainstay of therapy of refractory Crohn's disease (CD). However, a subset of patients shows incomplete or no response to this agent. In this study we investigated whether we could identify a mucosal gene panel to predict (non)response to IFX in CD.

METHODS

Mucosal biopsies were obtained during endoscopy from 37 patients with active CD (19 Crohn's colitis [CDc] and 18 Crohn's ileitis [CDi]) before and after first IFX treatment. Response was defined based on endoscopic and histologic findings. Total RNA was analyzed with Affymetrix Human Genome U133 Plus 2.0 Arrays. Quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) was used to confirm microarray data.

RESULTS

At baseline, significant gene expression differences were found between CDc and CDi. For predicting response in CDc, comparative analysis of CDc pretreatment expression profiles identified 697 significant probe sets between CDc responders (n = 12) and CDc nonresponders (n = 7). Class prediction analysis of CDc top 20 and top 5 significant genes allowed complete separation between CDc responders and CDc nonresponders. The CDc top 5 genes were TNFAIP6, S100A8, IL11, G0S2, and S100A9. Only one patient with CDi completely healed the ileal mucosa. Even using less stringent response criteria, we could not identify a predictive gene panel for IFX responsiveness in CDi.

CONCLUSIONS

This study identified a 100% accurate predictive gene signature for (non)response to IFX in CDc, whereas no such a predictive gene set could be identified for CDi.

Maintenance of clinical benefit in Crohn's disease patients after discontinuation of infliximab: long-term follow-up of a single centre cohort

BACKGROUND

Tumour necrosis factor-blockade with infliximab has advanced the treatment of Crohn's disease. While infliximab is efficacious, it remains to be determined whether patients who enter clinical remission with an anti-tumour necrosis factor therapy can have their treatment stopped and retain the state of remission.

AIM

To assess in patients with Crohn's disease who obtained infliximab-induced remission, the proportion who relapsed after infliximab discontinuation.

METHODS

This longitudinal cohort study examined patients from a University-based IBD referral centre. Forty eight patients with Crohn's disease in full clinical remission and who then discontinued infliximab were followed up for up to 7 years. Crohn's disease relapse was defined as an intervention with Crohn's disease medication or surgery.

RESULTS

Kaplan-Meier analysis of the proportion of patients with sustained clinical benefit demonstrated that 50% relapsed within 477 days after infliximab discontinuance. In contrast, 35% of patients remained well, and without clinical relapse, up to the end of the nearly 7-year follow-up.

CONCLUSIONS

In patients with Crohn's disease with an infliximab-induced remission, stopping infliximab results in a predictable relapse in a majority of patients. Nevertheless, a small percentage of patients sustain a long-term remission.

Inflammatory bowel disease: Established and evolving considerations on its etiopathogenesis and therapy

Modern studies of inflammatory bowel disease (IBD) pathogenesis have been pursued for about four decades, a period of time where the pace of progress has been steadily increasing. This progress has occurred in parallel with and is largely due to developments in multiple basic scientific disciplines that range from population and social studies, genetics, microbiology, immunology, biochemistry, cellular and molecular biology, and DNA engineering. From this cumulative and constantly expanding knowledge base the fundamental pillars of IBD pathogenesis appear to have been identified and consolidated during the last couple of decades. Presently there is a general consensus among basic IBD investigators that both Crohn's disease (CD) and ulcerative colitis (UC) are the result of the combined effects of four basic components: global changes in the environment, the input of multiple genetic variations, alterations in the intestinal microbiota, and aberrations of innate and adaptive immune responses. There is also agreement on the conclusion that none of these four components can by itself trigger or maintain intestinal inflammation. A combination of various factors, and most likely of all four factors, is probably needed to bring about CD or UC in individual patients, but each patient or set of patients seems to have a different combination of alterations leading to the disease. This would imply that different causes and diverse mechanisms underlie IBD, and this could also explain why every patient displays his or her own clinical manifestations and a personalized response to therapy, and requires tailored approaches with different medications. While we are becoming increasingly aware of the importance of this individual variability, we have only a superficial notion of the reasons why this occurs, as hinted by the uniqueness of the genetic background and of the gut flora in each person. So, we are apparently facing the paradox of having to deal with the tremendous complexity of the mechanisms responsible for chronic intestinal inflammation in the setting of each patient's individuality in the response to this biological complexity. This obviously poses considerable challenges to reaching a full understanding of IBD pathogenesis, but being aware of the difficulties is the first step in finding answers to them.

Is the disease course predictable in inflammatory bowel diseases?

During the course of the disease, most patients with Crohn's disease (CD) may eventually develop a stricturing or a perforating complication, and a significant number of patients with both CD and ulcerative colitis will undergo surgery. In recent years, research has focused on the determination of factors important in the prediction of disease course in inflammatory bowel diseases to improve stratification of patients, identify individual patient profiles, including clinical, laboratory and molecular markers, which hopefully will allow physicians to choose the most appropriate management in terms of therapy and intensity of follow-up. This review summarizes the available evidence on clinical, endoscopic variables and biomarkers in the prediction of short and long-term outcome in patients with inflammatory bowel diseases.

Role of genetics in prediction of disease course and response to therapy

The clinical course of Crohn’s disease and ulcerative colitis is highly variable between patients, and this has therapeutic implications. A number of clinical features have been identified, which predict a mild or more severe outcome. However, several of these are subjective and/or not persistent over time. With the progress in genetics research in inflammatory bowel disease (IBD), genetic markers are increasingly being proposed to improve stratification of patients. Genetics have the major advantage of being stable over time and not prone to subjective interpretation. Nevertheless, none of the genetic variants associated with particular outcomes have shown sufficient sensitivity or specificity to have been implemented in daily management. Along the same line of thinking, pharmacogenetics or the study of association between variability in drug response and genetic variation has also received more attention as part of the endeavor for personalized medicine. The ultimate goal in this area of medicine is to adapt medication to a patient’s specific genetic background and therefore improve on efficacy and safety rates. Although pharmacogenetic studies have been performed for all classes of drugs applied in IBD, few have generated consistent findings or have been replicated. The only genetic test approved for clinical practice is thiopurine S-methyltransferase testing prior to starting treatment with thiopurine analogues. The other reported associations have suffered from lack of confirmation or still need replication efforts. Nevertheless, the importance and necessity of pharmacogenetic studies will increase further as more therapeutic classes are being developed.

Is the disease course predictable in inflammatory bowel diseases?

During the course of the disease, most patients with Crohn’s disease (CD) may eventually develop a stricturing or a perforating complication, and a significant number of patients with both CD and ulcerative colitis will undergo surgery. In recent years, research has focused on the determination of factors important in the prediction of disease course in inflammatory bowel diseases to improve stratification of patients, identify individual patient profiles, including clinical, laboratory and molecular markers, which hopefully will allow physicians to choose the most appropriate management in terms of therapy and intensity of follow-up. This review summarizes the available evidence on clinical, endoscopic variables and biomarkers in the prediction of short and long-term outcome in patients with inflammatory bowel diseases.

Mucosal biomarkers in inflammatory bowel disease: Key pathogenic players or disease predictors?

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders of the bowel, including ulcerative colitis and Crohn’s disease. A single etiology has not been identified, but rather the pathogenesis of IBD is very complex and involves several major and minor contributors, employing different inflammatory pathways which have different roles in different patients. Although new and powerful medical treatments are available, many are biological drugs or immunosuppressants, which are associated with significant side effects and elevated costs. As a result, the need for predicting disease course and response to therapy is essential. Major attempts have been made at identifying clinical characteristics, concurrent medical therapy, and serological and genetic markers as predictors of response to biological agents. Only few reports exist on how mucosal/tissue markers are able to predict clinical behavior of the disease or its response to therapy. The aim of this paper therefore is to review the little information available regarding tissue markers as predictors of response to therapy, and reevaluate the role of tissue factors associated with disease severity, which can eventually be ranked as “tissue factor predictors”. Five main categories are assessed, including mucosal cytokines and chemokines, adhesion molecules and markers of activation, immune and non-immune cells, and other mucosal components. Improvement in the design and specificity of clinical studies are mandatory to be able to classify tissue markers as predictors of disease course and response to specific therapy, obtain the goal of achieving “personalized pathogenesis-oriented therapy” in IBD.

Pharmacogenomics in the treatment of inflammatory bowel disease

In recent years, the benefits of early aggressive treatment paradigms for inflammatory bowel disease have emerged. Symptomatic improvement is no longer considered adequate; instead, the aim of treatment has become mucosal healing and altered natural history. Nonetheless, we still fail to achieve these end points in a large number of our patients. There are many reasons why patients fail to respond or develop toxicity when exposed to drugs used for inflammatory bowel disease, but genetic variation is likely to account for a significant proportion of this. Some examples, notably thiopurine methyltransferase polymorphism in thiopurine treatment, are already established in clinical practice. We present a review of the expanding literature in this field, highlighting many interesting developments in pharmacogenomics applied to inflammatory bowel disease and, where possible, providing guidance on the translation of these developments into clinical practice.

[Prediction of the disease course in inflammatory bowel diseases]

Clinical presentation at diagnosis and disease course of both Crohn's disease (CD) and ulcerative colitis (UC) are heterogeneous and variable over time. During follow up, intestinal strictures or perforation may eventually develop at most patients with CD, and significant number of patients will undergo surgery. Much emphasis was laid in recent years on the determination of important predictive factors. Since early introduction of immunomodulators and/or biologicals might be justified in patients at risk for disease progression, so it is important to identify these patients as soon as possible. This review article summarizes the available literature on important clinical, endoscopic, fecal, serological/routine laboratory and genetic factors and hopefully will assist clinicians in the decision making of daily practice when choosing the treatment strategy for their patients with inflammatory bowel diseases.

[Markers of the course of inflammatory bowel disease treated with immunomodulators or biological agents]

Immunosuppressive or biological treatment in patients with inflammatory bowel disease can modify the natural history of their disease, although these treatments are not universally effective and can have severe adverse effects. Attempts have been made to identify predictive factors of response to the various therapeutic options in order to aid the choice of the most appropriate therapeutic alternative in each patient. The possibility of modifying any one of these predictive factors would be of great interest since it would provide the opportunity to alter the course of the disease. Epidemiological, biological, clinical, endoscopic, radiological, genetic and even proteomic markers have been studied, in addition to others related to the disease itself or to specific treatments. The present article briefly discusses the real use of each of these markers and the evidence supporting their utility.

Future biologic targets for IBD: potentials and pitfalls

The treatment of patients with IBD has evolved towards biologic therapy, which seeks to target specific immune and biochemical abnormalities at the molecular and cellular level. Multiple genes have been associated with susceptibility to IBD, and many of these can be linked to alterations in immune pathways. These immune pathways provide avenues for understanding the pathogenesis of IBD and suggest future drug targets, such as the IL-12-IL-23 pathway. In addition, failed therapeutic drug trials can provide valuable information about pitfalls in study design, drug delivery and disease activity assessment. Future biologic drug development will benefit from the early identification of subsets of patients who are most likely to respond to therapy by use of biological markers of genetic susceptibility or immunologic susceptibility.

Mucosal gene expression of antimicrobial peptides in inflammatory bowel disease before and after first infliximab treatment

Background

Antimicrobial peptides (AMPs) protect the host intestinal mucosa against microorganisms. Abnormal expression of defensins was shown in inflammatory bowel disease (IBD), but it is not clear whether this is a primary defect. We investigated the impact of anti-inflammatory therapy with infliximab on the mucosal gene expression of AMPs in IBD.

Methodology/Principal Findings

Mucosal gene expression of 81 AMPs was assessed in 61 IBD patients before and 4–6 weeks after their first infliximab infusion and in 12 control patients, using Affymetrix arrays. Quantitative real-time reverse-transcription PCR and immunohistochemistry were used to confirm microarray data. The dysregulation of many AMPs in colonic IBD in comparison with control colons was widely restored by infliximab therapy, and only DEFB1 expression remained significantly decreased after therapy in the colonic mucosa of IBD responders to infliximab. In ileal Crohn's disease (CD), expression of two neuropeptides with antimicrobial activity, PYY and CHGB, was significantly decreased before therapy compared to control ileums, and ileal PYY expression remained significantly decreased after therapy in CD responders. Expression of the downregulated AMPs before and after treatment (DEFB1 and PYY) correlated with villin 1 expression, a gut epithelial cell marker, indicating that the decrease is a consequence of epithelial damage.

Conclusions/Significance

Our study shows that the dysregulation of AMPs in IBD mucosa is the consequence of inflammation, but may be responsible for perpetuation of inflammation due to ineffective clearance of microorganisms.