Review article: the evidence base for interventions used to maintain remission in Crohn's disease

Clinical remission in paired phase two and three studies in inflammatory bowel disease: a systematic review with meta-analysis

Discrepancies in phase two and three studies can result in significant patient and financial burden, as well as the nonapproval of potentially efficacious drugs. We aimed to determine whether this discrepancy exists for clinical trials in inflammatory bowel disease (IBD). Electronic databases (MEDLINE and Embase) and clinical trial repositories were searched from 1 January 1946 to 12 March 2021, for paired phase two and three studies of advanced therapies for Crohn's disease and ulcerative colitis. The primary outcome was to compare clinical remission rates between paired phase two and three studies for Crohn's disease and ulcerative colitis. Multivariable mixed-model meta-analysis was performed to calculate odds ratios (OR) with 95% confidence intervals (CI). The Cochrane risk-of-bias tool was used to grade the risk of bias. Of 2642 studies, 29 were included. Fifteen were phase three, 11 were phase two, one was phase one/two, and two were phase two/three. There were no differences in clinical remission rates between phase two and three studies for Crohn's disease (OR, 1.07; 95% CI, 0.86-1.34; P = 0.54) and ulcerative colitis (OR, 0.81; 95% CI, 0.48-1.36; P = 0.43). Furthermore, there was a lack of any appreciable differences in study characteristics, inclusion criteria and patient demographics among paired phase two and three studies. Most studies were considered low risk of bias. Overall, paired phase two and three studies demonstrate similar clinical remission rates for advanced therapies in IBD. Whether this applies to newer outcomes, such as endoscopic and mucosal healing remains to be determined.

Evidence-based clinical practice guidelines for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic disorder involving mainly the intestinal tract, but possibly other gastrointestinal and extraintestinal organs. Although etiology is still uncertain, recent knowledge in pathogenesis has accumulated, and novel diagnostic and therapeutic modalities have become available for clinical use. Therefore, the previous guidelines were urged to be updated. In 2016, the Japanese Society of Gastroenterology revised the previous versions of evidence-based clinical practice guidelines for ulcerative colitis (UC) and Crohn's disease (CD) in Japanese. A total of 59 clinical questions for 9 categories (1. clinical features of IBD; 2. diagnosis; 3. general consideration in treatment; 4. therapeutic interventions for IBD; 5. treatment of UC; 6. treatment of CD; 7. extraintestinal complications; 8. cancer surveillance; 9. IBD in special situation) were selected, and a literature search was performed for the clinical questions with use of the MEDLINE, Cochrane, and Igaku Chuo Zasshi databases. The guidelines were developed with the basic concept of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Recommendations were made using Delphi rounds. This English version was produced and edited based on the existing updated guidelines in Japanese.

Inflammatory bowel disease meta-evidence and its challenges: is it time to restructure surgical research?

AIM

The aim of this study was to compare the methodological quality and input paper characteristics of systematic reviews and meta-analyses reported in the medical and surgical literature by performing a systematic 'overview of reviews'. Ulcerative colitis (UC) and Crohn's disease (CD) were used as the framework for this comparison as they are relatively common serious conditions, with both medical and surgical options for therapy.

METHOD

Medline, Embase, CINHAL and the Cochrane Database were searched to November 2013. Eligible papers were systematic reviews or meta-analyses that considered a question of therapy in CD or UC. Two independent reviewers selected the papers, extracted the data and scored their methodology using the AMSTAR scoring system. The papers were categorized into medical therapy (M), surgical therapy (S) or medical and surgical therapy (MS) groups. Following retrieval of the sample of meta-evidence papers, the original input studies used in their creation were identified and a search of Medline, Embase, CINHAL and the Cochrane Database was performed. A team of researchers then examined the collection of papers for bibliographic and financial information.

RESULTS

Five hundred papers were identified in the meta-evidence search, of which 118 were deemed eligible. There was a difference in the AMSTAR-rated average quality of the papers between the S and M group (S 7.36 vs M 8.75, P = 0.01). On average S papers were published in journals with a lower impact factor (S 3.26, M 5.04, MS 5.30, P < 0.001). S papers also showed more heterogeneity (I(2) ; S 37%, M 24%, MS 10%, P < 0.001). Some 25% of S meta-analyses used data-sets with significant heterogeneity (I(2) > 75%), compared with 8% of M meta-analyses and 3% of the MS meta-analyses. Some 5% of S papers were done on data sets that had I(2) values > 90%. There was no difference in the average number of papers assessed in each group, the average number of patients per meta-paper, the average time covered by the reviews, the average number of papers considered within each meta-analysis, or the average number of patients considered within each meta-analysis. Considering the conclusions of each meta-analysis, S meta-evidence was 50% more likely than M meta-evidence to be unable to make recommendations for practice. A total of 1499 original input papers were identified, of which 283 were used in more than one review. Within the non-repeated papers (n = 1023) the average impact factor within the S group was lower than that of the M and the MS groups (3.720 vs 11.230 vs 7.563, respectively; ANOVAP < 0.001). M papers had higher rates of pharmaceutical sponsorship than S papers (M 56% vs S 1%) and twice the level of government support (M 16% vs S 8%). Of note, 21% of M papers had corporate sponsorship but did not list any conflict of interest.

CONCLUSION

Compared with M meta-analyses, S meta-analyses in the UC and CD domain are more likely to be of poorer methodological quality, are of a greater degree of heterogeneity and less often offer a positive conclusion. The papers used to generate meta-evidence in M papers have a greater degree of corporate and government sponsorship, and are more likely to come from journals with higher impact factors.

Systematic review with network meta-analysis: comparative efficacy and safety of budesonide and mesalazine (mesalamine) for Crohn's disease

BACKGROUND

Budesonide and mesalazine (mesalamine) are commonly used in the medical management of patients with mild to moderate Crohn's disease.

AIM

To assess their comparative efficacy and harm using the methodology of network meta-analysis.

METHODS

A comprehensive search of Medline, Embase, the Cochrane Library and ClinicalTrials.gov, through October 2014, was performed to identify randomised controlled trials (RCTs) that recruited adult patients with active or quiescent Crohn's disease, and compared budesonide or mesalazine with placebo, or against each other, or different dosing strategies of one drug.

RESULTS

Twenty-five RCTs were combined using Bayesian network meta-analysis. Budesonide 9 mg/day, or at higher doses (15 or 18 mg/day), was shown superior to placebo for induction of remission [odds ratio (OR), 2.93; 95% credible interval (CrI), 1.52-5.39, and OR, 3.28; CrI, 1.46-7.55 respectively] and ranks at the top of the hierarchy of the competing treatments. For maintenance of remission, budesonide 6 mg/day demonstrated superiority over placebo (OR, 1.69; CrI, 1.05-2.75), being also at the best ranking position among all compared treatment strategies. No other comparisons (i.e. different doses of mesalazine vs. placebo or budesonide, for induction or maintenance of remission) reached significance. The occurrence of withdrawals due to adverse events was not shown different between budesonide, mesalazine and placebo, in both the induction and maintenance phases.

CONCLUSIONS

Budesonide, at the doses of 9 mg/day, or higher, for induction of remission in active mild or moderate Crohn's disease, and at 6 mg/day for maintenance of remission, appears to be the best treatment choice.

Total glucosides of peony attenuates 2,4,6-trinitrobenzene sulfonic acid/ethanol-induced colitis in rats through adjustment of TH1/TH2 cytokines polarization

The present study is to investigate effects of total glucosides of peony (TGP) on 2,4,6-trinitrobenzene sulfonic acid (TNBS)/ethanol-induced colitis in rats and to explore potential clinical use of TGP for treatment of inflammatory bowel disease. Sixty Sprague-Dawley rats were randomly grouped into normal controls, model controls, sulfasalazine (SASP) controls (100 mg/kg/day), and low, medium, and high-dose TGP groups (25, 50, and 100 mg/kg/day, respectively). 24 h following colonic instillation of TNBS, TGP, and SASP were given by gastric gavage three times a day for 7 days. Disease activity index (DAI), colon macroscopic damage index (CMDI), histopathological score (HPS), and myeloperoxidase (MPO) activity were evaluated. Levels of serum TNF-α, IL-1β, and IL-10 were measured by ELISA, and expression of TNF-α, IL-1β, and IL-10 mRNA and protein in colonic tissues was detected by RT-PCR and western blot, respectively. Compared with rats in the model controls, TGP (50 or 100 mg/kg/day)-treated rats with TNBS/ethanol-induced colitis showed significant improvements of DAI, CMDI, HPS, and MPO activity. Moreover, administration of TGP (50 or 100 mg/kg/day) decreased the up-regulated levels of serum TNF-α and IL-1β, and expression of TNF-α and IL-1β mRNA and protein in colonic tissues, and increased the serum IL-10 and colonic IL-10 mRNA and protein level. And there was no significant difference compared with administration of SASP (P > 0.05). TGP attenuates TNBS/ethanol-induced colitis in rats and its efficacy is similar to SASP, the potential mechanism might be related to the adjustment of Th1/Th2 cytokines polarization by decreasing pro-inflammatory cytokine TNF-α and IL-1β, and increasing anti-inflammatory cytokine IL-10.

Inflammatory bowel disease and systemic AA amyloidosis

BACKGROUND

Systemic AA amyloidosis is a recognised complication of inflammatory bowel disease. AA amyloidosis is a potential cause of end-stage renal failure and mortality but little is known of the natural history of this condition in inflammatory bowel disease.

METHODS

We evaluated the clinical phenotype, disease progression and outcome amongst 26 patients with inflammatory bowel disease and AA amyloidosis followed prospectively at a single center between 1989 and 2010.

RESULTS

Twenty-two patients had Crohn's disease and four had ulcerative colitis. Fistulae and abscesses occurred in ten cases, all of whom had Crohn's disease. Amyloidotic proteinuric renal dysfunction occurred in all of the cases. It resolved in five patients with well-controlled inflammation, but was progressive in all of the other patients. Fifteen patients reached end-stage renal disease after a median time of 6.3 years from development of renal dysfunction (by Kaplan-Meier estimate), six of whom subsequently proceeded to renal transplantation. There were five functioning grafts at census 0.8, 3.2, 4.2, 20.1 and 24.6 years after transplantation. One graft failed 14.5 years after renal transplantation because of amyloid recurrence in a patient with sustained chronic inflammatory activity.

CONCLUSIONS

AA amyloidosis remains a serious complication of both Crohn's disease and ulcerative colitis, and is characterized by proteinuric renal dysfunction that may resolve following suppression of inflammatory activity. Patient and graft survival are excellent in patients who undergo renal transplantation.

Effects of increase in fish oil intake on intestinal eicosanoids and inflammation in a mouse model of colitis

BACKGROUND

Inflammatory bowel diseases (IBD) are chronic intestinal inflammatory diseases affecting about 1% of western populations. New eating behaviors might contribute to the global emergence of IBD. Although the immunoregulatory effects of omega-3 fatty acids have been well characterized in vitro, their role in IBD is controversial.

METHODS

The aim of this study was to assess the impact of increased fish oil intake on colonic gene expression, eicosanoid metabolism and development of colitis in a mouse model of IBD. Rag-2 deficient mice were fed fish oil (FO) enriched in omega-3 fatty acids i.e. EPA and DHA or control diet for 4 weeks before colitis induction by adoptive transfer of naïve T cells and maintained in the same diet for 4 additional weeks. Onset of colitis was monitored by colonoscopy and further confirmed by immunological examinations. Whole genome expression profiling was made and eicosanoids were measured by HPLC-MS/MS in colonic samples.

RESULTS

A significant reduction of colonic proinflammatory eicosanoids in FO fed mice compared to control was observed. However, neither alteration of colonic gene expression signature nor reduction in IBD scores was observed under FO diet.

CONCLUSION

Thus, increased intake of dietary FO did not prevent experimental colitis.

Evidence-based clinical practice guidelines for Crohn's disease, integrated with formal consensus of experts in Japan

Crohn's disease is a disorder of unknown etiology and complicated pathogenesis. A substantial amount of evidence has accumulated recently and has been applied to clinical practice. The present guidelines were developed based on recent evidence and the formal consensus of experts relevant to this disease. Here we provide an overview of these guidelines, as follows. Target disease: Crohn's disease Users: Clinical practitioners in internal medicine, surgery, gastroenterology, and general practice Purpose: To provide appropriate clinical indicators to practitioners Scope of clinical indicators: Concept of Crohn's disease, epidemiology, classifications, diagnosis, treatment, follow up, and special situations Intervention: Diagnosis (interview, physical examination, clinical laboratory tests, imaging, and pathology) and treatment (lifestyle guidance, drug therapy, nutritional therapy, surgery, etc.) Outcome assessment: Attenuation of symptoms, induction and maintenance of remission, imaging findings, quality of life (QOL), prevention of complications and harm of therapy Methods for developing these guidelines: Described in the text Basis of recommendations: Integration of evidence level and consensus of experts Cost-benefit analysis: Not implemented Evaluation of effectiveness: Yet to be confirmed Status of guidelines: Updated version of the first Guidelines published in 2010 Publication sources: Printed publication available and electronic information in preparation Patient information: Not available Date of publication: October 2011 These guidelines were intended primarily to be used by practitioners in Japan, and the goal of these guidelines is to improve the outcomes of patients with Crohn's disease.

The role of nutrition in the etiology of inflammatory bowel disease

Many foods have been implicated in theories about the etiology of inflammatory bowel disease. While evidence has accumulated that nutritional factors as part of overall lifestyle changes may play a role in the growing incidence, no specific dietary recommendations except the promotion of breastfeeding can currently be given to decrease the risk of developing Crohn's disease or ulcerative colitis. For the treatment of Crohn's disease in children and adolescents, however, enteral feeding with a semi-elemental diet seems to be as effective as corticosteroids in inducing and maintaining remission. In the meta-analyses, advantages of one formula over the other are evened out, and more research is warranted into the anti-inflammatory properties of different nutrients, such as polyunsaturated fatty acids, butyrate, glutamine, and cytokines, such as transforming growth factors-beta. Unfortunately, for practical reasons, nutritional therapy remains underutilized, even though pediatric patients are most vulnerable to the harmful effects of nutrient deficiencies on growth, pubertal development, and bone health. There is hope that in the future the new field of nutrigenomics may enable physicians to more accurately tailor a specific diet to the patient genotype.

Successful treatment of asymptomatic or clinically terminal bovine Mycobacterium avium subspecies paratuberculosis infection (Johne's disease) with the bacterium Dietzia used as a probiotic alone or in combination with dexamethasone: Adaption to chronic human diarrheal diseases

A naturally occurring gastrointestinal disease, primarily of ruminants (Johne disease), is a chronic debilitating disease that is caused by Mycobacterium avium subspecies paratuberculosis (MAP). MAP infection occurs primarily in utero and in newborns. Outside our Dietzia probiotic treatment, there are no preventive/curative therapies for bovine paratuberculosis. Interestingly, MAP is at the center of controversy as to its role in (cause of) Crohn disease (CD) and more recently, its role in diabetes, ulcerative colitis, and irritable bowel syndrome (IBS); the latter two, like CD, are considered to be a result of chronic intestinal inflammation. Treatments, both conventional and biologic agents, which induce and maintain remission are directed at curtailing processes that are an intricate part of inflammation. Most possess side effects of varying severity, lose therapeutic value, and more importantly, none routinely result in prevention and/or cures. Based on (a) similarities of Johne disease and Crohn disease, (b) a report that Dietzia inhibited growth of MAP under specific culture conditions, and (c) findings that Dietzia when used as a probiotic, (i) was therapeutic for adult bovine paratuberculosis, and (ii) prevented development of disease in MAP-infected calves, the goal of the present investigations was to design protocols that have applicability for IBD patients. Dietzia was found safe for cattle of all ages and for normal and immunodeficient mice. The results strongly warrant clinical evaluation as a probiotic, in combination with/without dexamethasone.

Increased response and remission rates in short-duration Crohn's disease with subcutaneous certolizumab pegol: an analysis of PRECiSE 2 randomized maintenance trial data

OBJECTIVES

We sought to analyze the efficacy (response and remission) and safety data from the PRECiSE 2 trial of certolizumab pegol according to duration of Crohn's disease since diagnosis at baseline.

METHODS

Responders to induction treatment with certolizumab pegol at week 6 in PRECiSE 2 (n=425) were randomized to receive certolizumab pegol 400 mg (n=215) or placebo (n=210) until week 26. Logistic regression analysis identified factors linked to Crohn's disease history (short duration, no prior infliximab use, no corticosteroids, no operations) as prognostics of outcome. Efficacy (response, remission) and safety data were reanalyzed according to duration of Crohn's disease since diagnosis at baseline.

RESULTS

The proportions of patients in response at study end were inversely related to duration of Crohn's disease. Maintenance of response with certolizumab pegol was achieved in 89.5% of patients with a diagnosis <1 year (P<0.01 vs. placebo), compared with 57.3% of patients with a diagnosis > or = 5 years (P<0.001 vs. placebo). Corresponding remission rates were 68.4% (P<0.05 vs. placebo) and 44.3% (P<0.001 vs. placebo), respectively. Response and remission rates did not differ significantly by disease duration in placebo subgroups. Incidences of adverse events were unaffected by duration of disease at baseline.

CONCLUSIONS

These data suggest that patients treated with certolizumab pegol 400 mg earlier rather than later, with a confirmed Crohn's disease diagnosis, may achieve better treatment outcomes.

Prospective clinical trial: enteral nutrition during maintenance infliximab in Crohn's disease

PURPOSE

Hitherto, the efficacy of enteral nutrition (EN) on clinical outcomes during biological maintenance therapy in Crohn's disease (CD) has not been investigated. This prospective study was to assess the efficacy of EN on the maintenance rate of clinical remission in patients with quiescent CD receiving infliximab as maintenance therapy.

METHODS

Fifty-six patients who achieved clinical remission with infliximab induction therapy received infliximab as maintenance therapy (5 mg/kg, every 8 weeks). Thirty-two of the 56 patients received concomitant EN: elemental diet infusion during night-time and a low fat diet during daytime (EN group), while the remaining 24 patients received neither nutritional therapy nor food restriction (non-EN group). All patients were followed for 56 weeks; CD activity index (CDAI) was assessed and CDAI < 150 was defined as clinical remission.

RESULTS

During the 56-week observation, the mean CDAI was not significantly different between the 2 groups. Seven patients in the EN group ceased EN therapy because they maintained complete remission. On an intention-to-treat basis, 25 patients in the EN group (78%) and 16 patients in the non-EN group (67%) remained in clinical remission during the 56-week observation (P = 0.51).

CONCLUSIONS

The outcomes of this prospective study showed that concomitant EN during infliximab maintenance therapy does not significantly increase the maintenance rate of clinical remission in patients with CD.

What is the optimal therapy for Crohn's disease: step-up or top-down?

Crohn's disease (CD) is an idiopathic chronic inflammatory disorder of the digestive tract, which is incurable. Present therapeutic guidelines follow a sequential step-up approach that focuses on treating acute disease or 'inducing clinical remission' and subsequently aims to 'maintain clinical response'. In view of the chronic relapsing-remitting disabling disease course, new treatment approaches have been sought with the ultimate end point of disease course modification and mucosal healing. A recent preliminary study from D'Haens et al. has provided evidence suggesting that reversing the treatment paradigm from a 'step-up' to a 'top-down' approach may positively alter the natural course of this illness. Their findings indicate that early use of biologic therapy, in combination with immunomodulators, resulted in remission occuring more rapidly than the conventional 'step-up' treatment, with a longer time period to relapse, a decreased need for treatment with corticosteroids, a faster reduction in clinical symptoms, rapid decline in biochemical inflammatory markers (C-reactive protein) and improved endoscopic mucosal healing. These results, supported by previous studies on infliximab use, may hold a promising outcome of fewer stricturing complications, hospitalizations and surgeries for patients with CD. However, we need to better define the timing and candidates for the 'top-down' approach as we are still uncertain about the safety data and the long-term benefits if biologic agents are given as routine maintenance treatment, since most of the trials in CD have been short term, and approximately 30% of patients might have been overtreated. Future clinical trials will be crucial in answering these questions.

Enteral nutrition for the maintenance of remission in Crohn's disease: a systematic review

OBJECTIVE

This review study was designed to evaluate the efficacy of enteral nutrition (EN) for the maintenance of remission in patients with Crohn's disease (CD) who achieved medically or surgically induced remission.

METHODS

The Medline, Embase, Ovid, and Cochrane database search of literature was carried out to identify studies that reported the efficacy of EN for the maintenance of remission in CD. The main outcome measure was the occurrence of clinical or endoscopic relapse.

RESULTS

Ten studies were included: one randomized controlled trial, three prospective non-randomized trials, and six retrospective studies. Elemental, semielemental or polymeric diets were used as an oral supplement or a nocturnal tube feeding in addition to ordinary foods. Comparing outcomes between patients who received EN and those who did not, the clinical remission rate was significantly higher in those with EN in all seven studies. In two studies, EN showed suppressive effects on endoscopic disease activity. In all four studies investigating impacts of the quantity of enteral formula on clinical remission, higher amounts of enteral formula were associated with higher remission rates: > or =30 kcal/kg ideal body weight/day (vs. <30 kcal/kg ideal body weight/day), > or =1200 kcal/day (vs. <1200 kcal/day), and > or =1600 kcal/day (vs. <1600 kcal/day). Quantitative pooling of studies was not feasible because of the diversity of interventions and outcome measures among the studies.

CONCLUSION

Although the evidence level is not high, the available data suggest that EN may be useful for maintaining remission in patients with CD. Large randomized controlled trials are necessary to assess a definite efficacy of EN for the maintenance of remission.

Long term efficacy and safety of allopurinol and azathioprine or 6-mercaptopurine in patients with inflammatory bowel disease

BACKGROUND AND AIMS

We previously reported that IBD patients who are non-responders to thiopurines with preferential shunting of metabolites to hepatotoxic 6-methylmercaptopurine ribonucleotides compared to 6-thioguanine nucleotides can reverse the ratio of 6-MMP/6-TGN and respond to thiopurines with the addition of allopurinol. The objective of this study is to report long term efficacy and safety, along with results for an additional 11 patients.

METHODS

Retrospective chart review of patients at the University of Chicago IBD Center treated with allopurinol in addition to thiopurines.

RESULTS

Twenty five patients with Crohn's disease or ulcerative colitis were enrolled. Within the first month of therapy 6-TGN metabolite levels increased from a mean of 186.5±17.4 (SE) to 352.8±37.8 pmol/8×10(8) (p=0.0001). Over the same period 6-MMP levels decreased from a mean of 11,966±1697 to 2004±536 pmol/8×10(8) (p<0.0001). The mean daily dosage of prednisone decreased from 19.8±3.8 mg to 5.3±2.7 mg (p=0.03). Thirteen patients have a minimum of one year follow-up. Nine of these thirteen patients have continued on therapy for at least 2 years. All thirteen of these patients continue to be in clinical remission at the last follow-up visit. No patients have had evidence of sustained thrombocytopenia or abnormal liver enzymes.

CONCLUSIONS

In AZA/6-MP non-responders with increased 6-MMP/6-TGN ratios, addition of allopurinol continues to demonstrate safety and efficacy for long-term maintenance and steroid-sparing in IBD.

Role of Klebsiella and collagens in Crohn's disease: a new prospect in the use of low-starch diet

Crohn's disease is suggested to result from a microbially triggered immune-mediated autoimmune process, involving mainly the terminal ileum and ileo-caecal junction. Klebsiella pneumoniae shares certain molecular structures present in pullulanase pulA and pulD secretion enzymes with various self-antigens present in collagens and HLA-B27 molecules, respectively. A link exists between high dietary starch intake and the growth of intestinal microflora, involving especially Klebsiella microbes. Increased exposure to Klebsiella in the gut as the result of high starch intake would lead to high production of antiKlebsiella antibodies as well as autoantibodies to the cross-reactive self-antigens with the resultant inflammation at the pathological sites. Eradication of these microbes from the gut in patients with Crohn's disease with the use of low-starch diet and antibacterial agents as well as immunomodulatory measures could be beneficial in the management of this disease.

Probiotics in pediatric inflammatory bowel diseases

The intestinal microbiota plays a key role in the initiation and perpetuation of inflammatory bowel diseases (IBD). As such, there is a strong rationale to use agents such as probiotics to modulate the gut microbiome as a treatment strategy for these disorders. Furthermore, the potential toxicities of current IBD therapies make probiotics attractive medications for patients and physicians. However, although much attention is being placed on probiotic therapy, relatively few well-designed trials have evaluated its efficacy in the management of IBD, particularly in the pediatric population. This article examines the currently available published trials studying probiotics for the treatment of IBD, with particular emphasis on their role in pediatric IBD patients.

Postoperative Crohn’s disease recurrence: A practical approach

Crohn's disease is a chronic inflammatory condition that may involve any segment of the gastrointestinal tract. Although several drugs have proven efficacy in inducing and maintaining disease in remission, resectional surgery remains as a cornerstone in the management of the disease, mainly for the treatment of its stenosing and penetrating complications. However, the occurrence of new mucosal (endoscopic) lesions in the neoterminal ileum early after surgery is almost constant, it is followed in the mid-term by clinical symptoms and, in a proportion of patients, repeated intestinal resections are required. Pathogenesis of postoperative recurrence (POR) is not fully understood, but luminal factors (commensal microbes, dietary antigens) seem to play an important role, and environmental and genetic factors may also have a relevant influence. Many studies tried to identify clinical predictors for POR with heterogeneous results, and only smoking has repeatedly been associated with a higher risk of POR. Ileocolonoscopy remains as the gold standard for the assessment of appearance and severity of POR, although the real usefulness of the available endoscopic score needs to be revisited and alternative techniques are emerging. Several drugs have been evaluated to prevent POR with limited success. Smoking cessation seems to be one of the more beneficial therapeutic measures. Aminosalicylates have only proved to be of marginal benefit, and they are only used in low-risk patients. Nitroimidazolic antibiotics, although efficient, are associated with a high rate of intolerance and might induce irreversible side effects when used for a long-term. Thiopurines are not widely used after ileocecal resection, maybe because some concerns in giving immunomodulators in asymptomatic patients still remain. In the era of biological agents and genetic testing, a well-established preventive strategy for POR is still lacking, and larger studies to identify good clinical, serological, and genetic predictors of early POR as well as more effective drugs (or drug combinations) are needed.

Pharmacogenetics of Crohn’s disease

The considerable interindividual differences in efficacy and side effects of commonly used medications in Crohn’s disease are partly owing to genetic polymorphisms. Many genetic variants have been studied in genes possibly involved in the metabolism or mechanism of action of therapeutic agents such as glucocorticosteroids, azathioprine/6-mercaptopurine, methotrexate, calcineurin inhibitors or anti-TNF agents. However, the only test translated into clinical practice is thiopurine S-methyltransferase (TPMT) genotyping for hematological toxicity of thiopurine treatment. To date, there are no other meaningful applications for pharmacogenomics in clinical practice of Crohn’s disease. In the future, designed therapeutic trials should possibly permit the development of predictive models including genotypic markers, such as that proposed for the clinical outcome after infliximab therapy, which includes an apoptotic pharmacogenetic index. The recent identification of new susceptibility genes provides additional candidate markers that have possible effects on the outcomes of therapies, and prioritizes new therapeutic targets, such as the IL-23 pathway. Futher innovative approaches might be relevant for the pharmacogenetic investigation of gene variants implied in innate immune pattern recognition and autophagy.

Rationale for probiotic treatment strategies in inflammatory bowel disease

Chronic inflammatory bowel diseases (IBD), such as Crohn's disease and ulcerative colitis, are recurrent and aggressive inflammatory disorders that are most likely the result of an overly aggressive immune response to ubiquitous intestinal antigens in a genetically susceptible host. Despite decades of intense research, our knowledge of factors causing IBD remains incomplete and, therefore, conventional therapy to induce and maintain remission works in a symptomatic fashion, merely suppressing the immune response. Probiotic bacteria have long been known to confer health benefits, especially with regard to intestinal disorders. Although there is mounting evidence from in vitro and animal experiments supporting the use of probiotics in IBD, clinical trials have not provided definite evidence for the therapeutic effect of probiotic therapy in IBD to date. This is with the notable exception of pouchitis and the maintenance of remission in ulcerative colitis, whereas Crohn's disease and active ulcerative colitis do not seem amenable to probiotic intervention. The next 5 years will see more trials targeting specific clinical settings using tailor-made probiotic combinations, taking into account our increasing knowledge of individual probiotic properties and the diversity of these microorganisms.