Plasma Oncostatin M, TNF-α, IL-7, and IL-13 Network Predicts Crohn's Disease Response to Infliximab, as Assessed by Calprotectin Log Drop.

BACKGROUND: Cytokines emerge as possible biomarkers of response in Crohn's disease (CD). We aimed to determine the plasmatic cytokine profiles of active CD patients who started infliximab (IFX) treatment and their capacity to predict the response to IFX. METHODS: A total of 30 active CD patients receiving an induction therapy of IFX were enrolled in the study. Peripheral blood samples pretreatment were collected. Concentrations of 15 cytokines were measured by Luminex technology. Responses to IFX were evaluated by the drop in fecal calprotectin based on its logarithm-transformed values. A random forest (RF) predictive model was used for data analyses. RESULTS: Samples of 22 patients were analyzed. The RF model ranked the following cytokines as the top predictors of the response: tumor necrosis factor alpha (TNFα), interleukin (IL)-13, oncostatin M (OSM), and IL-7 (p < 0.005). Partial dependency plots showed that high levels of IL-13 pretreatment, low TNFα levels, and low IL-7 levels were associated with a favorable IFX response. Increased levels of OSM and TNFα predicted unfavorable responses to IFX. CONCLUSIONS: We here show that a log drop in calprotectin strongly correlates with clinical parameters and it can be proposed as a useful objective clinical response predictor. Plasma TNFα, IL-13, Il-7, and OSM network could predict CD response to IFX before induction therapy, as assessed by calprotectin log drop.

Fecal Calprotectin Pretreatment and Induction Infliximab Levels for Prediction of Primary Nonresponse to Infliximab Therapy in Crohn's Disease.

INTRODUCTION: The association between infliximab (IFX) and fecal calprotectin (FC) levels on one hand, and the clinical and endoscopic response of patients with inflammatory bowel disease on the other, is well established. OBJECTIVE AND METHODS: To investigate the association between inflammatory biochemical parameters and serum concentrations of IFX during induction treatment with a primary nonresponse in a prospective cohort of Crohn's disease (CD) patients. RESULTS: Of the 35 patients included, 8 (22.8%) had primary nonresponse at the end of induction. Induction IFX levels were lower among primary nonresponders at weeks 6 and 14 (week 6: median IFX level 7.3 vs. 11.2 µg/mL, respectively, p = 0.090; week 14: median IFX level 1.5 vs. 4.7 µg/mL, respectively, p = 0.020). FC levels were higher in patients with primary nonresponse versus primary response at weeks 0, 6, and 14 (week 0: median FC level 1,830 vs. 410 µg/g, -respectively, p = 0.030; week 6: median FC level 1,150 vs. 230 µg/g, respectively, p = 0.074; week 14: median FC level 1,210 vs. 208 µg/g, respectively, p = 0.060). For the multivariate analysis, the median IFX level at week 14 and median FC level at week 0 were independently associated with primary nonresponse. A significant inverse correlation was determined between FC level at week 0 and IFX level at week 14 (Spearman's rho correlation, 0.440; p < 0.05). CONCLUSIONS: IFX levels (at week 14) and baseline FC levels could predict primary nonresponse after induction IFX therapy in patients with CD. A high baseline inflammatory load might modify the pharmacokinetic processes of anti-tumor necrosis factor drugs. Drug level monitoring and measurement of baseline inflammatory parameters could improve the efficacy of IFX in the induction therapy of patients with active CD.

Different Genetic Expression Profiles of Oxidative Stress and Apoptosis-Related Genes in Crohn's Disease.

BACKGROUND/AIMS: Increased oxidative stress and decreased immune cell apoptosis have been reported to be important factors in the pathogenesis of Crohn's disease (CD). Our aim was to characterize the genetic expression of molecules implicated in the regulation of oxidative stress and apoptosis in peripheral white mononuclear cells of 18 healthy volunteers (controls) and 20 patients at the onset of CD (active CD [aCD]): 10 who achieved remission (inactive CD [iCD]) and 10 who did not present a complete and deep response to treatment (aCD-T). METHODS: mRNA expression was measured by the Agena MassARRAY quantitative gene expression analysis application. The genes analyzed were Fas-receptor (FASR), Fas-ligand (FASL), signal transducer and activator of transcription 1 (STAT1), nuclear factor kappa-light-chain--enhancer of activated B cells (NFKB1), apoptosis signal-regulating kinase 1 (ASK1), serine/threonine-protein kinase H1 (PSKH1), ATP-binding cassette sub-family B1 (ABCB1) and peptidylprolyl isomerase D (PPID). RESULTS: During a CD flare, we found specific upregulated expression of the genes STAT1 and PSKH1, whereas ABCB1 and FASL were downregulated. In the patients with iCD, FASR and NFKB1 were upregulated. The expression levels of NFKB1, STAT1 and ABCB1 did not show any difference in patients with aCD at the onset of the disease and after treatment (aCD-T). The expression levels of PPID and ASK1 did not show any differences in the patients with aCD, iCD and the controls. We have also reviewed the cellular function and role of these genes in CD. CONCLUSIONS: These findings contribute to improving the understanding of the pathogenesis of CD and highlight potential genes involved.

Withdrawal of Azathioprine in Inflammatory Bowel Disease Patients Who Sustain Remission: New Risk Factors for Relapse.

BACKGROUND: The benefits of immunosuppressants for sustaining remission and preventing flares of IBD are well known. However, optimal timing for withdrawal has not been determined. AIMS: The objective of this study was to calculate the risk of relapse and predictors after withdrawal of azathioprine (AZA) monotherapy in patients who sustain deep remission. METHODS: This was a multicenter observational study of patients with IBD in remission whose immunosuppressant had been withdrawn. We recorded demographic variables, disease data, laboratory values, and the results of imaging tests performed at withdrawal and, in patients who relapsed, time to relapse and the efficacy of reintroducing the drug. RESULTS: Ninety-five patients were included (35 UC and 60 CD). The mean duration of AZA treatment was 87 and 77 months for UC and CD, respectively. Endoscopic remission was evaluated in 23 patients with UC and 35 with CD. After AZA withdrawal, 91% patients with UC and 67% with CD received high doses of salicylates. A total of 26 patients relapsed. The cumulative relapse rate at 5 years was 46% for CD and UC. AZA was reintroduced in 19 patients, of whom 14 responded. Predictors of relapse were corticosteroid dependence, early introduction of AZA (CD), and late introduction of AZA (UC). CONCLUSIONS: Almost half of the patients in whom AZA was withdrawn were in remission at 5 years. The candidates for withdrawal could be better identified based on corticosteroid dependence, previous surgery, timing of initiation, and indication for AZA.

Adsorptive granulocyte/monocyte apheresis use in severe ulcerative colitis and determination of changes in plasma cytokines.

Despite controversy regarding the use of granulocyte/monocyte adsorption (GMA) in inflammatory bowel disease, some studies have shown favorable outcomes when it is used in steroid-dependent patients with ulcerative colitis (UC). The mechanisms responsible for such outcomes are not well characterized, but changes in immune cell populations and cytokine levels have been suggested to play an important role. We report the cases of 3 patients with chronically active severe UC who underwent GMA due to an inadequate response to standard and rescue therapy, as well as changes to their plasma cytokine profile. All the patients presented severe UC that was only partially responsive to various immunosuppressive drugs, and they were, therefore, referred for colectomy; however, all 3 refused this option, which led to the compassionate use of GMA as a last therapeutic resort. Following GMA treatment, rapid normalization of the clinical, endoscopic and laboratory parameters was observed in all the patients. Despite having achieved a good response, most cytokines remained at high concentrations after GMA, and only two, IL-6 and IL-8, showed a clear decrease throughout the GMA sessions. In view of this outcome, we hypothesize that GMA can help to lower the inflammatory load, thereby enhancing the effect of biologic drugs. To confirm this hypothesis and explore further indications for GMA, we propose the need for research directed toward the characterization of immune cell populations and their specific cytokine production rather than global cytokine assessment.

Recommendations of the Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU) on the utility of the determination of faecal calprotectin in inflammatory bowel disease. / Recomendaciones del Grupo Español de Trabajo en Enfermedad de Crohn y Colitis Ulcerosa (GETECCU) sobre la utilidad de la determinación de calprotectina fecal en la enfermedad inflamatoria intestinal.

The management of inflammatory bowel disease (IBD) is currently based on the objective evaluation of intestinal lesions. It would therefore be interesting to have access to simple and non-invasive tools to monitor IBD activity and to identify the presence of lesions. Faecal calprotectin (FC) is the main cytosolic protein of neutrophils, it is resistant to bacterial degradation and it is stable at room temperature for several days, characteristics that make it suitable for use in clinical practice. It can be used to differentiate between inflammatory and functional processes, it correlates with endoscopic activity, it is associated with clinical and endoscopic response to treatment and it has short-term prognostic value. This paper offers an up-to-date perspective on the information that FC can provide clinicians to aid diagnosis, monitoring and management of IBD.

Correlation between fecal calprotectin and inflammation in the surgical specimen of Crohn's disease.

BACKGROUND: An accurate assessment of the inflammatory activity is crucial to establish the most appropriate treatment in Crohn's disease (CD). The present study aimed to evaluate the utility of preoperative fecal calprotectin (FC) measurement in small bowel CD and its relationship with inflammatory activity in surgical pathology specimens. METHODS: This was a prospective observational study including all the patients with small bowel CD operated on at our center between March 2011 and September 2013. Preoperative laboratory and stool tests were performed. A meticulous exploration of entire small bowel was performed during surgery, and the resected bowel (or a sample of whole intestinal wall, if strictureplasty) was submitted for pathologic analyses. Chiorean's score was used to grade pathologic features (inflammation or fibrosis). In case of multiple lesions, the most inflammatory component was considered. RESULTS: Thirty-eight consecutive patients were included in the study, and 81 small bowel lesions were identified. Among inflammatory markers, only FC was significantly associated with the degree of histologic inflammation in the surgical specimen (P < 0.003). FC reflected histologic inflammatory activity with an area under the receiver-operating characteristic curve of 0.85 (CI: 0.70-0.99; P < 0.001). A cutoff value of 170 µg/g had 81% sensitivity and 85% specificity for diagnosis of moderate or severe inflammation. Ordinal regression analysis showed the probability of a greater or lesser degree of inflammation based on the value of preoperative FC. CONCLUSIONS: FC is an excellent biomarker of inflammatory activity in small bowel CD as it correlates with histologic inflammation in the surgical specimen.

Immunological Mechanisms of Adsorptive Cytapheresis in Inflammatory Bowel Disease.

Ulcerative colitis and Crohn's disease are the two main forms of inflammatory bowel disease (IBD). The study of immunological pathways involved in the onset of IBD is of fundamental importance to identify potential biological markers of disease activity and specific targets for therapy. Removing excess and activated circulating leukocytes with adsorptive cytapheresis has been shown to be a potentially effective treatment for patients with an inflamed bowel. Adsorptive cytapheresis is a non-pharmacological approach for active IBD, in which known sources of inflammatory cytokines such as activated myeloid lineage leucocytes are selectively depleted from the circulatory system. The decrease in inflammatory load caused by removing these cells is thought to enhance drug therapy and thereby promote disease remission. The benefit of cytapheresis appears to rest upon its ability to reduce levels of certain immune cell populations; however, whether this depletion results in further changes in lymphocyte populations and cytokine production needs further clarification. In this review, we aim to summarize existing evidence on the role of cytapheresis in patients with IBD, its effect on cytokine levels and cellular populations, and to discuss its potential impact on disease activity.

[Oxidative stress in Crohn's disease]. / Estrés oxidativo en la enfermedad de Crohn.

Crohn's disease (CD) is characterized by transmural inflammation that is most frequently located in the region of the terminal ileum. Although the physiopathological mechanisms of the disease are not yet well defined, the unregulated immune response is associated with high production of reactive oxygen species (ROS). These elements are associated with complex systems known as antioxidant defenses, whose function is ROS regulation, thereby preventing the harmful effects of these elements. However, the presence of an imbalance between ROS production and ROS elimination by antioxidants has been widely described and leads to oxidative stress. In this article, we describe the most significant findings on oxidative stress in the intestinal mucosa and peripheral blood.

Endoscopic treatment (endoscopic balloon dilation/self-expandable metal stent) vs surgical resection for the treatment of de novo stenosis in Crohn's disease (ENDOCIR study): an open-label, multicentre, randomized trial.

BACKGROUND: Stenosis is one of the most common complications in patients with Crohn's disease (CD). Endoscopic balloon dilation (EBD) is the treatment of choice for a short stenosis adjacent to the anastomosis from previous surgery. Self-expandable metal stents (SEMS) may be a suitable treatment option for longer stenoses. To date, however, there is no scientific evidence as to whether endoscopic (EBD/SEMS) or surgical treatment is the best approach for de novo or primary stenoses that are less than 10 cm in length. METHODS/DESIGN: Exploratory study as "proof-of-concept", multicentre, open-label, randomized trial of the treatment of de novo stenosis in the CD; endoscopic treatment (EBD/SEMS) vs surgical resection (SR). The type of endoscopic treatment will initially be with EDB; if a therapeutic failure occurs, then a SEMS will be placed. We estimate 2 years of recruitment and 1 year of follow-up for the assessment of quality of life, costs, complications, and clinical recurrence. After the end of the study, patients will be followed up for 3 years to re-evaluate the variables over the long term. Forty patients with de novo stenosis in CD will be recruited from 15 hospitals in Spain and will be randomly assigned to the endoscopic or surgical treatment groups. The primary aim will be the evaluation of the patient quality of life at 1 year follow-up (% of patients with an increase of 30 points in the 32-item Inflammatory Bowel Disease Questionnaire (IBDQ-32). The secondary aim will be evaluation of the clinical recurrence rate, complications, and costs of both treatments at 1-year follow-up. DISCUSSION: The ENDOCIR trial has been designed to determine whether an endoscopic or surgical approach is therapeutically superior in the treatment of de novo stenosis in CD. TRIAL REGISTRATION: ClinicalTrials.gov NCT04330846. Registered on 1 April 1 2020. https://clinicaltrials.gov/ct2/home.

Initial management of intraabdominal abscesses and preventive strategies for abscess recurrence in penetrating Crohn's disease: a national multicenter study based on ENEIDA registry.

INTRODUCTION: Intra-abdominal abscesses complicating Crohn's disease (CD) are a challenging situation. Their management, during the hospitalization and after resolution, is still unclear. METHODS: Adult patients with CD complicated with intraabdominal abscess who required hospitalization were included from the prospectively maintained ENEIDA registry from GETECCU. Initial strategy effectiveness and safety to resolve abscess was assessed. Survival analysis was performed to evaluate recurrence risk. Predictive factors associated with resolution were evaluated by multivariate regression and predictive factors associated with recurrence were assessed by Cox regression. RESULTS: 520 patients from 37 Spanish hospitals were included; 322 (63%) were initially treated with antibiotics alone, 128 (26%) with percutaneous drainage, and 54 (17%) with surgical drainage. The size of the abscess was critical to the effectiveness of each treatment. In abscesses < 30mm, the antibiotic was as effective as percutaneous or surgical drainage. However, in larger abscesses, percutaneous or surgical drainage was superior. In abscesses > 50mm, surgery was superior to percutaneous drainage, although it was associated with a higher complication rate. After abscess resolution, luminal resection was associated with a lower 1-year abscess recurrence risk (HR 0.43, 95% CI 0.24-0.76). However, those patients who initiated anti-TNF therapy had a similar recurrence risk whether luminal resection had been performed. CONCLUSIONS: Small abscesses (<30mm) can be managed with antibiotics alone, while larger ones require drainage. Percutaneous drainage will be effective and safer than surgery in many cases. After discharge, anti-TNF therapy reduces abscess recurrence risk in a similar way to bowel resection.

Role of oxidative stress and antioxidant enzymes in Crohn's disease.

There is increasing interest in oxidative stress being a potential aetiological factor and/or a triggering factor in Crohn's disease, rather than a concomitant occurrence during the pathogenesis of the disease. Recent research has shown that the immune mononuclear cells of Crohn's disease patients are induced to produce hydrogen peroxide (H2O2). Similarly, the regulation of antioxidant enzymes during disease in these cells has been unravelled, showing that SOD (superoxide dismutase) activity and GPx (glutathione peroxidase) activity is increased during active disease and returns to normal in remission phases. However, catalase remains constantly inhibited which supports the idea that catalase is not a redox-sensitive enzyme, but a regulator of cellular processes. ROS (reactive oxygen species) can be produced under the stimulus of different cytokines such as TNFα (tumour necrosis factor α). It has been shown in different experimental models that they are also able to regulate apoptosis and other cellular processes. The status of oxidative stress elements in Crohn's disease and their possible implications in regulating cellular processes are reviewed in the present paper.

Specific Plasma MicroRNA Signatures in Predicting and Confirming Crohn's Disease Recurrence: Role and Pathogenic Implications.

INTRODUCTION: MicroRNAs (miRNAs) are important epigenetic regulators in Crohn's disease (CD); however, their contribution to postoperative recurrence (POR) is still unknown. We aimed to characterize the potential role of miRNAs in predicting POR in patients with CD and to identify their pathogenic implications. METHODS: Of 67 consecutively operated patients with CD, we included 44 with pure ileal CD. Peripheral blood samples were taken before surgery and during follow-up. The patients were classified according to the presence or absence of POR assessed by ileocolonoscopy or magnetic resonance imaging enterography. The miRNAs were profiled by reverse transcription polymerase chain reaction before surgery and during morphological POR or, for those who remained in remission, 1 year after surgery. R software and mirWalk were used. RESULTS: Five human miRNAs (miR-191-5p, miR-15b-5p, miR-106b-5p, miR-451a, and miR-93-5p) were selected for discriminating between the 2 patient groups at presurgery (PS), with an area under the curve of 0.88 (95% confidence interval [0.79, 0.98]). Another 5 (miR-15b-5p, miR-451a, miR-93-5p, miR-423-5p, and miR-125b-5p) were selected for 1 year, with an area under the curve of 0.96 (95% confidence interval [0.91, 1.0]). We also created nomograms for POR risk estimation. CCND2 and BCL9L genes were related to PS miRNA profiles; SENP5 and AKT3 genes were related to PS and 1 year; and SUV39H1 and MAPK3K10 were related to 1 year. DISCUSSION: Different plasma miRNA signatures identify patients at high POR risk, which could help optimize patient outcomes. We developed nomograms to facilitate the clinical use of these results. The identified miRNAs participate in apoptosis, autophagy, proinflammatory immunological T-cell clusters, and reactive oxygen species metabolism.

Real-life experience with 4 years of golimumab persistence in ulcerative colitis patients.

Golimumab has demonstrated its long-term efficacy and safety in ulcerative colitis in clinical trials, but no data of long-term persistence has been published from real world. To estimate long-term persistence of golimumab, as well as factors associated with longer persistence, in patients with ulcerative colitis in real life. Observational multicentre study including adult patients with ulcerative colitis treated with golimumab and with at least twelve months of follow-up. We included 190 patients, 105 (55.26%) naive to anti-TNF, with mean disease duration of 9.32 ± 8.09 years. Probability of persistence was 63%, 46%, 39% and 27% at 1, 2, 3 and 4 years, respectively. Persistence was lower in patients with primary failure to previous anti-TNF. Eighty-two (43.16%) patients needed dose intensification during follow-up, with a mean time until intensification of 8.03 ± 8.64 months. Dose intensification and lower disease duration predicted higher persistence with golimumab (p = 0.037 and p = 0.008, respectively). During a follow-up of 17.25 ± 15.83 months, 32 (16.5%) patients needed hospitalisation and 11 (6%) underwent colectomy. No unexpected adverse events were reported. Golimumab has demonstrated good persistence and safety profile for long treatment in ulcerative colitis patients.

A Nomogram Combining Fecal Calprotectin Levels and Plasma Cytokine Profiles for Individual Prediction of Postoperative Crohn's Disease Recurrence.

BACKGROUND: The aims of this study were to characterize the immune response profile in patients with Crohn's disease (CD) and early postoperative recurrence (POR), to identify predictive biomarkers, and to develop a noninvasive predictive tool for individual estimation of POR risk. METHODS: Sixty-one patients who had undergone ileocolonic resection for CD were prospectively included and followed up for 24 months. Fecal calprotectin (FC), analytical parameters, and plasma cytokines were obtained before surgery and at various time points during postoperative follow-up. Morphological recurrence was assessed by ileocolonoscopy or magnetic resonance enterography within 6-12 months after surgery. Clinical activity was scored using the Harvey-Bradshaw Index. RESULTS: Twenty-seven patients (44.3%) had morphological recurrence during follow-up. Fecal calprotectin values were significantly associated with POR risk over time. The receiver operating characteristic curve for FC provided an area under the curve (AUC) of 0.88 (95% confidence interval, 0.75-0.96), and morphological recurrence was best predicted by FC ≥160 µg/g at 6 months after surgery (85% sensitivity, 70% specificity, 26% predictive positive value, 98% negative predictive value [NPV]). The plasma cytokine profile showed higher presurgery interleukin (IL)-13 plasma levels and higher IL-6 and interferon (IFN)-γ levels at 6 months after surgery in patients with POR compared with patients without recurrence. The combination of FC, IL-6, and IFN-γ values at 6 months gave an AUC of 0.90 for predicting an early recurrence. CONCLUSIONS: FC values <160 µg/g at 6 months have a high NPV to rule out early lesions. Combined values of FC, IL-6, and IFN-γ levels at 6 months postsurgery constitute a prognostic index with a high predictive capacity to assess the risk of early POR.

Identification of Epigenetic Methylation Signatures With Clinical Value in Crohn's Disease.

INTRODUCTION: DNA methylation is an epigenetic mechanism that regulates gene expression and represents an important link between genotype, environment, and disease. It is a reversible and inheritable mechanism that could offer treatment targets. We aimed to assess the methylation changes on specific genes previously associated with Crohn's disease (CD) and to study their possible associations with the pathology. METHODS: We included 103 participants and grouped them into 2 cohorts (a first [n = 31] and a second validation [n = 72] cohort), with active CD (aCD) and inactive CD (iCD) and healthy participants (CTR). DNA was obtained from the peripheral blood and analyzed by the Agena platform. The selected genes were catalase (CAT), α-defensin 5 (DEFA5), FasR, FasL, tumor necrosis factor (TNF), TNFRSF1A, TNFRSF1B, PPA2, ABCB1, NOD2, PPARγ, and PKCζ. We used the elastic net algorithm and R software. RESULTS: We studied 240 CpGs. Sixteen CpGs showed differential methylation profiles among aCD, iCD, and CTR. We selected for validation those with the greatest differences: DEFA5 CpG_11; CpG_13; CAT CpG_31.32; TNF CpG_4, CpG_12; and ABCB1 CpG_21. Our results validated the genes DEFA5 (methylation gain) and TNF (methylation loss) with P values < 0.001. In both cases, the methylation level was maintained and did not change with CD activity (aCD vs iCD). The subanalysis comparison between aCD and iCD showed significant differential methylation profiles in other CpGs: TNF, FAS, ABCB1, CAT, and TNFRS1BF genes. DISCUSSION: The methylation status of DEFA5 and TNF genes provides a signature biomarker that characterizes patients with CD and supports the possible implication of the environment and the immune system in CD pathogenesis.

Possible Biomarkers in Blood for Crohn's Disease: Oxidative Stress and MicroRNAs-Current Evidences and Further Aspects to Unravel.

Crohn's disease (CD) is an inflammatory disorder characterised by a transmural inflammation of the intestinal wall. Although the physiopathology of the disease is not yet fully understood, it is clear that the immune response plays an important role in it. This hyperreactive immune system is accompanied by the presence of unregulated reactive oxygen species (ROS). These elements are modulated in normal conditions by different elements, including enzymes that function as antioxidant defences preventing the harmful effects of ROS. However, in CD there is an imbalance between ROS production and these antioxidant elements, resulting in oxidative stress (OxS) phenomena. In fact, now OxS is being considered more a potential etiological factor for Crohn's disease rather than a concomitant effect in the disease. The persistence of the OxS can also be influencing the evolution of the disease. Furthermore, the epigenetic mechanisms, above all microRNAs, are being considered key elements in the pathogenesis of CD. These elements and the presence of OxS have also been linked to several diseases. We, therefore, describe in this review the most significant findings related to oxidative stress and microRNAs profiles in the peripheral blood of CD patients.

Fecal Calprotectin in Ileal Crohn's Disease: Relationship with Magnetic Resonance Enterography and a Pathology Score.

BACKGROUND: Magnetic resonance enterography (MRE) is an effective method of assessing small bowel Crohn's disease (CD). Fecal calprotectin (FC) correlates well with endoscopic disease activity. We aimed to evaluate the correlation between FC and disease activity according to MRE and surgical pathology in small bowel CD. METHODS: One hundred twenty consecutive patients with ileal CD who underwent MRE assessment were included. Clinical data, C-reactive protein and FC, radiological and histological variables were obtained. Clinical activity was evaluated by the Harvey-Bradshaw Index and FC by enzyme-linked immunosorbent assay. MRE activity was assessed by means of the Magnetic Resonance Index of Activity score. Chiorean's score was used to grade pathological inflammation in surgical specimens. RESULTS: Seventy-five patients (62.5%) were in clinical remission (Harvey-Bradshaw Index < 5) and 45 (37.5%) had active disease (Harvey-Bradshaw Index ≥ 5). The Magnetic Resonance Index of Activity score was significantly associated with FC levels (P < 0.01), with a moderate overall correlation (Spearman's r = 0.56, P < 0.001). FC reflected MRE inflammatory activity with an area under the receiver operating characteristic curve of 0.914 (confidence interval, 0.849-0.958; P < 0.001). A cutoff value of 166.50 µg/g had 90% sensitivity, 74% specificity, 89% positive predictive value, and 76% negative predictive value for diagnosis of inflammation. Twenty-eight of 120 patients were operated. Surgical pathology showed a good agreement with FC for moderate (P = 0.03) and severe (P = 0.01) Chiorean's index. No relationship was detected for C-reactive protein. CONCLUSIONS: FC correlates with the degree of MRE inflammatory activity and with surgical pathology damage in ileal CD. Thus, FC could be a surrogate marker of disease control used to select patients for MRE assessment and therapeutic adjustment.