One in five patients with Inflammatory Bowel Disease (IBD) suffers from anemia, most frequently caused by iron deficiency. Anemia and iron deficiency are associated with worse disease outcomes, reduced quality of life, decreased economic participation, and increased healthcare costs. International guidelines and consensus-based recommendations have emphasized the importance of treating anemia and iron deficiency. In this review, we draw attention to the rarely discussed effects of iron deficiency and iron therapy on the redox status, the intestinal microbiota, and the potential interplay between them, focusing on the clinical implications for patients with IBD. Current data are scarce, inconsistent, and do not provide definitive answers. Nevertheless, it is imperative to rule out infections and discern iron deficiency anemia from other types of anemia to prevent untargeted oral or intravenous iron supplementation and potential side effects, including oxidative stress. Further research is necessary to establish the clinical significance of changes in the redox status and the intestinal microbiota following iron supplementation.

Summary: Background: Increased collagen remodelling is a key pathophysiological component underlying intestinal stricture and fistula development in Crohn's disease (CD).Aims: To investigate associations between serological biomarkers of collagen turnover and disease behaviour according to the Montreal classification in patients with CD.Methods: Serological biomarkers of type III/IV collagen formation (PRO‐C3, PRO‐C4) and matrix metalloproteinase (MMP) or granzyme‐B (GrzB)‐mediated type I, III, IV and VI collagen degradation (C1M, C3M, C4M, C4G, C6Ma3) were measured using neo‐epitope protein fingerprint assays in 101 patients with CD (Montreal B1: n = 37; B2: n = 27; B3: n = 37) and 96 controls. Patients were followed up until their last outpatient visit to monitor stricturing/penetrating disease progression and recurrence and the occurrence of surgical interventions.Results: C1M, C3M and C4M were significantly reduced in patients with stricturing disease (Montreal B2) and accurately differentiated them from patients with either non‐stricturing, non‐penetrating (B1) or penetrating (B3) disease (all p < 0.001, multivariable analysis). Similarly, the type IV collagen formation/degradation (PRO‐C4/C4M) ratio demonstrated high discriminative capacity (B1/B2: AUC = 0.90; B1/B3: AUC = 0.87, both p < 0.001, multivariable analysis). Prospectively, higher baseline levels of C1M and C4G were associated with an increased risk of penetrating disease progression (C4G: hazard ratio [HR] 1.71 [1.05–2.81], p < 0.05).Conclusions: Elevated degradation of type I, III and IV collagen and excessive (relative) formation of type IV collagen strongly associates with stricturing CD. Type I and IV collagen fragments show predictive potential for the risk of penetrating disease progression. These biomarkers may become valuable tools for detection and prediction of stricturing and penetrating CD.

Background: Iron deficiency (ID) and anemia in patients with Inflammatory Bowel Disease (IBD) are associated with a reduced quality of life. We assessed the prevalence of ID and anemia in Dutch outpatients with IBD and compared routine ID(A) management among medical professionals to the European Crohn’s and Colitis Organisation (ECCO) treatment guidelines. Methods: Between January and November 2021, consecutive adult outpatients with IBD were included in this study across 16 Dutch hospitals. Clinical and biochemical data were extracted from medical records. Additionally, medical professionals filled out questionnaires regarding routine ID(A) management. Results: In total, 2197 patients (1271 Crohn’s Disease, 849 Ulcerative Colitis, and 77 IBD-unclassified) were included. Iron parameters were available in 59.3% of cases. The overall prevalence of anemia, ID, and IDA was: 18.0%, 43.4%, and 12.2%, respectively. The prevalence of all three conditions did not differ between IBD subtypes. ID(A) was observed more frequently in patients with biochemically active IBD than in quiescent IBD (ID: 70.8% versus 23.9%; p < 0.001). Contrary to the guidelines, most respondents prescribed standard doses of intravenous or oral iron regardless of biochemical parameters or inflammation. Lastly, 25% of respondents reported not treating non-anemic ID. Conclusions: One in five patients with IBD suffers from anemia that—despite inconsistently measured iron parameters—is primarily caused by ID. Most medical professionals treat IDA with oral iron or standard doses of intravenous iron regardless of biochemical inflammation; however, non-anemic ID is often overlooked. Raising awareness about the management of ID(A) is needed to optimize and personalize routine care.

Background: Hepcidin, the systemic iron regulator, could be critical in differentiating iron deficiency (ID) from functional iron restriction in inflammatory bowel disease (IBD). We assessed hepcidin as a diagnostic ID marker and explored the relationship between hepcidin and its regulators in patients with IBD undergoing induction therapy with infliximab (IFX) or vedolizumab (VEDO). Methods: Patients with active IBD receiving induction therapy with IFX or VEDO were included. Serum samples at baseline and after 6 weeks of induction therapy were analyzed for hepcidin, inflammation- and hypoxia-associated cytokines, and oxidative stress. Data were analyzed by stratifying based on the response at week 14. Results were compared with samples from age- and sex-matched healthy control subjects. Results: Patients receiving induction therapy with IFX (n = 71) or VEDO (n = 51) and healthy control subjects (n = 50) were included. At baseline, hepcidin correlated positively with ferritin and negatively with soluble transferrin receptor/log ferritin index (P < .001). ID was prevalent in 96.7% of patients who had hepcidin levels below the median. Hepcidin accurately identified ID: the area under the curve (hepcidin) was 0.89 (95% confidence interval, 0.82-0.95; P < .001). In total, 75.4% of patients responded to induction therapy; inflammation, hepcidin, and ferritin decreased significantly, while transferrin increased during induction therapy. These changes were observed only in patients who responded to the therapy. Conclusions: Hepcidin levels in IBD are primarily determined by ID, even in an inflammatory state. In addition, induction therapy can decrease hepcidin levels, which might lead to better bioavailability of iron supplements. Therefore, hepcidin is a potential diagnostic ID biomarker that could assist therapeutic decision making.

Crohn’s disease (CD) is a relapsing-remitting inflammatory disease of the gastrointestinal (GI) tract characterized by increased extracellular matrix (ECM) remodeling. The introduction of the α4β7-integrin inhibitor vedolizumab (VEDO) has improved disease management, although there is a high rate of primary non-response in patients with CD. We studied whether ECM biomarkers of neutrophil activity and mucosal damage could predict long-term response to VEDO in patients with CD. Serum levels of human neutrophil elastase (HNE)-derived fragments of calprotectin (CPa9-HNE), and matrix metalloproteinase (MMP)-derived fragments of type I (C1M), III (C3M), IV (C4M), and VI (C6Ma3) collagen, type III collagen formation (PRO-C3), basement membrane turnover (PRO-C4) and T-cell activity (C4G), were measured using protein fingerprint assays in patients with CD (n = 32) before VEDO therapy. Long-term response was defined as VEDO treatment of at least 12 months. CPa9-HNE was significantly increased at baseline in non-responders compared with responders (p < 0.05). C1M, C3M, C4M, C6Ma3, and PRO-C4 were also significantly increased at baseline in non-responders compared with responders (all p < 0.05). All biomarkers were associated with response to VEDO (all p < 0.05). To conclude, baseline levels of serum biomarkers for neutrophil activity and mucosal damage are linked to the pathology of CD, and are associated with long-term use of VEDO in patients with CD. Therefore, these biomarkers warrant further validation and could aid in therapeutic decision-making concerning vedolizumab therapy.

Introduction Iron deficiency anaemia (IDA) is the most common systemic manifestation of inflammatory bowel disease (IBD) that has detrimental effects on quality of life (QoL) and disease outcomes. Iron deficiency (ID), with or without anaemia, poses a diagnostic and therapeutic challenge in patients with IBD due to the multifactorial nature of ID(A) and its frequent recurrence. Elevated hepcidin—a systemic iron regulator that modulates systemic iron availability and intestinal iron absorption—has been associated with oral iron malabsorption in IBD. Therefore, hepcidin could assist in therapeutic decision-making. In this study, we investigate whether hepcidin can predict response to oral and intravenous iron supplementation in patients with active IBD undergoing anti-inflammatory treatment. Methods and analysis PRIme is an exploratory, multicentre, open-label and randomised trial. All adult patients with active IBD and ID(A) will be assessed for eligibility. The participants (n=90) will be recruited at five academic hospitals within the Netherlands and randomised into three groups (1:1:1): oral ferrous fumarate, oral ferric maltol or intravenous iron. Clinical and biochemical data will be collected at the baseline and after 6, 14 and 24 weeks. Blood samples will be collected to measure hepcidin and other biomarkers related to iron status. In addition, patient-reported outcomes regarding QoL and disease burden will be evaluated. The primary outcome is the utility of hepcidin as a predictive biomarker for response to iron therapy, which will be assessed using receiver operating curve analysis. Ethics and dissemination The study has been approved by the Institutional Review Board at the Leiden University Medical Center (IRB No. P21.109) and other study sites. All participants will provide written informed consent to enrol in the study. The findings will be published in a peer-reviewed journal and disseminated at scientific conferences; the dataset will be available on reasonable request. Trial registration Prospectively registered in the https://clinicaltrials.gov/ and the Eudra registries. First submitted on 10 May 2022 to the ClinicalTrials.gov (ID: NCT05456932) and on 3 March 2022 to the European Union Drug Regulating Authorities Clinical Trials Database (ID: 2022-000894-16).